Multimode power converter

Claim 2

Apparatus for producing a signal simulating a desired AC waveform having a sloped rising edge, comprising: first and second converter output terminals; a juncture node, at a voltage of predetermined polarity and variable magnitude relative to a common rail; a converter circuit, responsive to control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; and a controller for selectively generating the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, to create a predetermined waveform having a sloped rising edge at the converter output terminals, simulating the desired AC waveform.

Claim 3

The apparatus of claim 1, wherein the controller comprises a programmed microcomputer.

Claim 4

The apparatus of claim 1, wherein the controller generates, in sequence: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 5

The apparatus of claim 3, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal, and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 6

The apparatus of claim 1, wherein the converter circuit comprises: a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal.

Claim 7

The apparatus of claim 5, wherein the controller generates, in sequence: first control signals to first and fourth power switch circuits to initiate current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; fourth control signals to at least one of the first and fourth power switch circuits to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 8

The apparatus of claim 6, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal, and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 9

The apparatus of claim 5 wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 10

The apparatus of claim 5 wherein each power switch circuit comprises a power switching device and a firing circuit for generating actuating signals to turn the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise: a capacitor; a resistance cooperating with the capacitor to produce a predetermined discharge time constant; a switching circuit disposed to selectively effect connections to develop a voltage on the capacitor in excess of that required to render the power switching device fully conductive during periods when the switching device is non-conductive, and provide a discharge path for the capacitor to provide the actuating signal to the switching device in response to the control signal; the discharge time constant of the capacitor being such that the charge on the capacitor is only slightly above the threshold value required to render the power switching device fully conductive at the time the switching device is rendered non-conductive.

Claim 11

The apparatus of claim 1 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitor; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a charging path to the capacitor during dead time periods when no connection is effected by the converter, and selectively effecting a discharge path from the capacitor to the juncture node during a predetermined portion of the periods when the converter effects a current path between the juncture node and one of the first and second converter output terminals.

Claim 12

The apparatus of claim 5 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitor; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a charging path to the capacitor during dead time periods when none of the power switch circuits is conducting, and selectively effecting a discharge path from the capacitor to the juncture node during a predetermined portion of the periods when one of the power switch circuits effect a current path between the juncture node and one of the first and second converter output terminals.

Claim 13

The apparatus of claim 1 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitance, and a switching circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance.

Claim 14

The apparatus of claim 12, wherein the controller for selectively generating the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, generates: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 15

The apparatus of claim 13, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal, and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 16

The apparatus of claim 13, wherein: the second control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effect a current path between the juncture node and the common rail through the capacitance; the third control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effectively break the current path between the juncture node and the common rail through the capacitance.

Claim 17

The apparatus of claim 12 further including means for controllably discharging the capacitance, to facilitate generation of a relatively low voltage across the converter output terminals.

Claim 18

The apparatus of claim 12, wherein the converter circuit comprises: a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal.

Claim 19

The apparatus of claim 17 including means for selectively rendering at least one of the third or fourth power switch circuits partially conductive whereby the capacitance is controllably discharged through a resistance.

Claim 20

The apparatus of claim 17 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 21

The apparatus of claim 5 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 22

The apparatus of claim 5 wherein: the first and fourth power switch circuits are independently controlled; and the second and third power switch circuits are independently controlled.

Claim 23

The apparatus of claim 5 wherein: the control signals applied to the first and fourth power switch circuits are of different duration; and the control signals applied to the second and third power switch circuits are of different duration.

Claim 24

The apparatus of claim 1 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a generator with a rotor and a stator, and an auxiliary winding disposed such that relative movement between rotor and stator induces a current therein; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a connection to the auxiliary winding during a predetermined portion of the periods when one of the power switch circuits effect a current path between the juncture node and one of the converter output terminals.

Claim 25

Apparatus comprising: first and second rails, adapted to have a rectified rail voltage applied therebetween; first and second converter output terminals; a first power switch circuit, electrically connected to the first rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the first rail and the first converter output terminal; and a second power switch circuit, electrically connected to the first rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the first rail, and the second converter output terminal; a third power switch circuit, electrically connected to the second rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the second rail and the first converter output terminal; and a fourth power switch circuit, electrically connected to the second rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the second rail and the second converter output terminal; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC waveform; wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power switching device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 26

Apparatus comprising: first and second rails, adapted to have a rectified rail voltage applied therebetween; first and second converter output terminals; a first power switch circuit, electrically connected to the first rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the first rail and the first converter output terminal; and a second power switch circuit, electrically connected to the first rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the first rail, and the second converter output terminal; a third power switch circuit, electrically connected to the second rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the second rail and the first converter output terminal; and a fourth power switch circuit, electrically connected to the second rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the second rail and the second converter output terminal; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC waveform; wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power switching device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 27

The system of claim 24 wherein the first and second power switch circuits are isolated power switch circuits and the third and fourth power switch circuits are non-isolated power switch circuits.

Claim 28

The system of claim 24 wherein the power switching device is a power transistor.

Claim 29

The system of claim 24, further comprising means for varying the magnitude of the rail voltage, wherein the controller generates, in sequence: first control signals to first and fourth power switch circuits to initiate current paths between the first rail and the first converter output terminal and between the second rail and the second converter output terminal, the magnitude of the rail voltage initially being at a first level; a second control signal to the means for varying the magnitude of the rail voltage, to initiate a change in the magnitude of the rail voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the rail voltage, to initiate a change in the magnitude of the rail voltage back to the first level; fourth control signals to at least one of the first and fourth power switch circuits to cause the converter to effectively break at least one of the current paths between the first rail and the first converter output terminal and between the second rail and the second converter output terminal; and fifth control signals to the first and fourth power switch circuits to cause the converter to effect a current path between the first rail and the second converter output terminal and between the second rail and the first converter output terminal.

Claim 30

The apparatus of claim 27, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal, and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 31

The apparatus of claim 24 wherein: the first and fourth power switch circuits are independently controlled; and the second and third power switch circuits are independently controlled.

Claim 32

The apparatus of claim 24 wherein: the control signals applied to the first and fourth power switch circuits are of different duration; and the control signals applied to the second and third power switch circuits are of different duration.

Claim 33

Apparatus comprising: first and second converter output terminals; a juncture node, receptive of a rectified signal relative to a common rail; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal; a capacitance; a fifth power switch circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC waveform.

Claim 34

Apparatus comprising: first and second converter output terminals; a juncture node, receptive of a rectified signal relative to a common rail; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal; a capacitance; a fifth power switch circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC waveform.

Claim 35

The apparatus of claim 31 further including means for controllably discharging the capacitance, to facilitate generation of a relatively low voltage across the converter output terminals.

Claim 36

The apparatus of claim 31 including means for selectively rendering at least one of the third or fourth power switch circuits partially conductive whereby the capacitance is controllably discharged through a resistance.

Claim 37

The apparatus of claim 31 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 38

The apparatus of claim 31 wherein: the first and fourth power switch circuits are independently controlled; and the second and third power switch circuits are independently controlled.

Claim 39

The apparatus of claim 31 wherein: the control signals applied to the first and fourth power switch circuits are of different duration; and the control signals applied to the second and third power switch circuits are of different duration.

Claim 40

Apparatus comprising: high, intermediate, and common DC rails, an intermediate DC rail signal being applied between the intermediate and common rails, and a high DC rail signal being applied between the high and common rails; first and second converter output terminals; a juncture node, receptive of the intermediate DC rail signal; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the juncture node, and to the high DC rail, disposed to, responsive to control signals applied thereto, selectively effect a current path between the high DC rail and the juncture node; a fourth power switch circuit, electrically connected to the common DC rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common DC rail and the first converter output terminal; a fifth power switch circuit, electrically connected to the common DC rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common DC rail and the second converter output terminal; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC signal.

Claim 41

Apparatus comprising: high, intermediate, and common DC rails, an intermediate DC rail signal being applied between the intermediate and common rails, and a high DC rail signal being applied between the high and common rails; first and second converter output terminals; a juncture node, receptive of the intermediate DC rail signal; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; and a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the juncture node, and to the high DC rail, disposed to, responsive to control signals applied thereto, selectively effect a current path between the high DC rail and the juncture node; a fourth power switch circuit, electrically connected to the common DC rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common DC rail and the first converter output terminal; a fifth power switch circuit, electrically connected to the common DC rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common DC rail and the second converter output terminal; and a controller for selectively generating the control signals to the power switch circuits to create a predetermined waveform having a sloped rising edge at the converter output terminals simulating a desired AC signal.

Claim 42

The system of claim 37 wherein the first and second power switch circuits are isolated power switch circuits and the third and fourth power switch circuits are non-isolated power switch circuits.

Claim 43

The system of claim 37 wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power switching device on and off in accordance with the control signals.

Claim 44

The system of claim 39 wherein the power switching device is a power transistor.

Claim 45

The system of claim 39 wherein the firing circuits for the first, second and third power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 46

The apparatus of claim 1, wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a rotor, adapted for selective rotation; a stator, including at least one stator winding disposed such that rotation of the rotor induces current in the stator winding; and a switching circuit, responsive to control signals applied thereto, selectively applying a voltage developed from the current induced in the stator winding between the juncture node and common rail.

Claim 47

The apparatus of claim 42 wherein the means for controllably varying the magnitude of the juncture node voltage further comprises a capacitance disposed to develop a voltage from the current induced in the stator winding.

Claim 48

The apparatus of claim 43, further comprising means for rotating the rotor.

Claim 49

The apparatus of claim 43 wherein the means for controllably varying the magnitude of the juncture node voltage further comprises a further switching circuit disposed to selectively connect and disconnect the capacitance between the juncture node and the common rail.

Claim 50

The apparatus of claim 1, wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a rotor, adapted for selective rotation; a stator, including a plurality of stator windings disposed such that rotation of the rotor induces current in the stator windings; and a switching circuit, responsive to control signals applied thereto, selectively completing current paths between individual stator windings and the juncture node.

Claim 51

The apparatus of claim 24 further comprising means for generating the unipolar rail voltage.

Claim 52

The apparatus of claim 46, wherein the means for generating the unipolar rail voltage comprises: a rotor, adapted for selective rotation; a stator, including at least one stator winding disposed such that rotation of the rotor induces current in the stator winding; and a switching circuit, responsive to control signals applied thereto, selectively applying a voltage developed from the current induced in the stator winding between the juncture node and common rail.

Claim 53

The apparatus of claim 47 wherein the means for generating the unipolar rail voltage further comprises a capacitance disposed to develop a voltage from the current induced in the stator winding.

Claim 54

The apparatus of claim 48 wherein the means for generating the unipolar rail voltage further comprises a further switching circuit disposed to selectively connect and disconnect the capacitance between the juncture node and the common rail.

Claim 55

The apparatus of claim 31 further comprising means for generating the junction node signal.

Claim 56

The apparatus of claim 50, wherein the means for generating the junction node signal comprises: a rotor, adapted for selective rotation; a stator, including at least one stator winding disposed such that rotation of the rotor induces current in the stator winding; and a switching circuit, responsive to control signals applied thereto, selectively effecting a current path between the stator winding and the juncture node.

Claim 57

The apparatus of claim 51, further comprising means for rotating the rotor.

Claim 58

Apparatus for producing a signal simulating a desired AC waveform having a sloped rising edge, comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; and means, for selectively generating the control signals to the converter circuit and to the means for varying the magnitude of the juncture node voltage, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 59

Apparatus for producing a signal simulating a desired AC waveform having a sloped rising edge, comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; and means, for selectively generating the control signals to the converter circuit and to the means for varying the magnitude of the juncture node voltage, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 60

The apparatus of claim 53, wherein the controller generates, in sequence: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 61

The apparatus of claim 54, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 62

The apparatus of claim 53, wherein the converter circuit comprises: a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; and a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal.

Claim 63

The apparatus of claim 56, wherein the controller generates, in sequence: first control signals to first and fourth power switch circuits to initiate current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; fourth control signals to at least one of the first and fourth power switch circuits to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 64

The apparatus of claim 57, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 65

The apparatus of claim 56 wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 66

The apparatus of claim 56 wherein each power switch circuit comprises a power switching device and a firing circuit for generating actuating signals to turn the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise: a capacitor; a resistance cooperating with the capacitor to produce a predetermined discharge time constant; and a switching circuit disposed to selectively effect connections to develop a voltage on the capacitor in excess of that required to render the power switching device fully conductive during periods when the switching device is non-conductive, and provide a discharge path for the capacitor to provide the actuating signal to the switching device in response to the control signal, the discharge time constant of the capacitor being such that the charge on the capacitor is only slightly above the threshold value required to render the power switching device fully conductive at the time the switching device is rendered non-conductive.

Claim 67

The apparatus of claim 53 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitor; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a charging path to the capacitor during dead time periods when no connection is effected by the converter, and selectively effecting a discharge path from the capacitor to the juncture node during a predetermined portion of the periods when the converter effects a current path between the juncture node and one of the first and second converter output terminals.

Claim 68

The apparatus of claim 56 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitor; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a charging path to the capacitor during dead time periods when none of power switch circuits are during a predetermined portion of the periods when one of the power switch circuits effect a current path between the juncture node and one of the first and second converter output terminals.

Claim 69

The apparatus of claim 53 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitance; and a switching circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance.

Claim 70

The apparatus of claim 63, wherein the controller for selectively generating the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, generates: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 71

The apparatus of claim 64, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 72

The apparatus of claim 64, wherein: the second control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effect a current path between the juncture node and the common rail through the capacitance; and the third control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effectively break the current path between the juncture node and the common rail through the capacitance.

Claim 73

The apparatus of claim 63 further including means for controllably discharging the capacitance, to facilitate generation of a relatively low voltage across the converter output terminals.

Claim 74

The apparatus of claim 63, wherein the converter circuit comprises: a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the first converter output terminal; a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; and a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal.

Claim 75

The apparatus of claim 68 including means for selectively rendering at least one of the third or fourth power switch circuits partially conductive whereby the capacitance is controllably discharged through a resistance.

Claim 76

The apparatus of claim 68 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 77

The apparatus of claim 56 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 78

The apparatus of claim 56 wherein: the first and fourth power switch circuits are independently controlled; and the second and third power switch circuits are independently controlled.

Claim 79

The apparatus of claim 56 wherein: the control signals applied to the first and fourth power switch circuits are of different duration; and the control signals applied to the second and third power switch circuits are of different duration.

Claim 80

The apparatus of claim 53 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a generator with a rotor and a stator; an auxiliary winding disposed such that relative movement between rotor and stator induces a current therein; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a connection to the auxiliary winding during a predetermined portion of the periods when one of the power switch circuits effect a current path between the juncture node and one of the converter output terminals.

Claim 81

Apparatus for a producing a signal simulating a desired AC waveform, comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; a controller for selectively generating, in sequence: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level; greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal; and the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, effecting a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 82

Apparatus for a producing a signal simulating a desired AC waveform, comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; a controller for selectively generating, in sequence: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level; greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal; and the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, effecting a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 83

The apparatus of claim 75, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 84

Apparatus for producing a signal simulating a desired periodic AC waveform comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit comprising; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the first converter output terminal; a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; and a controller for selectively generating control signals at periodic predetermined times in the desired AC waveform to the converter circuit and to the means for varying the magnitude of the juncture node voltage, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 85

Apparatus for producing a signal simulating a desired periodic AC waveform comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit comprising; a first power switch circuit, electrically connected to the juncture node, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the first converter output terminal; a second power switch circuit, electrically connected to the juncture node, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node, and the second converter output terminal; a third power switch circuit, electrically connected to the common rail, and to the first converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the first converter output terminal; a fourth power switch circuit, electrically connected to the common rail, and to the second converter output terminal, disposed to, responsive to control signals applied thereto, selectively effect a current path between the common rail and the second converter output terminal; means, responsive to control signals applied thereto, for controllably varying the magnitude of the juncture node voltage; and a controller for selectively generating control signals at periodic predetermined times in the desired AC waveform to the converter circuit and to the means for varying the magnitude of the juncture node voltage, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 86

The apparatus of claim 5, wherein the controller generates, in sequence: first control signals to first and fourth power switch circuits to initiate current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; fourth control signals to at least one of the first and fourth power switch circuits to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 87

The apparatus of claim 79, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 88

The apparatus of claim 77 wherein each power switch circuit comprises a power switching device and a firing circuit for turning the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise means for quickly driving the associated power switching device into a saturated state when the associated control signal changes state to minimize power dissipation during the switching interval.

Claim 89

The apparatus of claim 77 wherein each power switch circuit comprises a power switching device and a firing circuit for generating actuating signals to turn the power device on and off in accordance with the control signals; and the firing circuits for the first and second power switch circuits comprise: a capacitor; a resistance cooperating with the capacitor to produce a predetermined discharge time constant; and a switching circuit disposed to selectively effect connections to develop a voltage on the capacitor in excess of that required to render the power switching device fully conductive during periods when the switching device is non-conductive, and provide a discharge path for the capacitor to provide the actuating signal to the switching device in response to the control signal the discharge time constant of the capacitor being such that the charge on the capacitor is only slightly above the threshold value required to render the power switching device fully conductive at the time the switching device is rendered non-conductive.

Claim 90

The apparatus of claim 77 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitor; and a switching circuit, for, responsive to control signals applied thereto, selectively effecting a charging path to the capacitor during dead time periods when none of power switch circuits are conducting, and selectively effecting a discharge path from the capacitor to the juncture node during a predetermined portion of the periods when one of the power switch circuits effect a current path between the juncture node and one of the first and second converter output terminals.

Claim 91

The apparatus of claim 77 wherein the means for controllably varying the magnitude of the juncture node voltage comprises: a capacitance; and a switching circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance.

Claim 92

The apparatus of claim 83 further including means for controllably discharging the capacitance, to facilitate generation of a relatively low voltage across the converter output terminals.

Claim 93

The apparatus of claim 77 wherein at least one of the third or fourth power switch circuits comprises: a switching device which is rendered fully conductive by application thereto of a control signal of a first predetermined magnitude, and rendered into a linear mode of operation by application thereto of a control signal of a second predetermined magnitude; and driver circuits for selectively applying respective control signals of said first and second magnitudes.

Claim 94

The apparatus of claim 77 wherein: the first and fourth power switch circuits are independently controlled; and the second and third power switch circuits are independently controlled.

Claim 95

The apparatus of claim 77 wherein: the control signals applied to the first and fourth power switch circuits are of different duration; and the control signals applied to the second and third power switch circuits are of different duration.

Claim 96

Apparatus for producing a signal simulating a desired periodic AC waveform comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; a capacitance; a switching circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance; and a controller for selectively generating control signals at periodic times in the desired AC waveform to the converter circuit and to the switching circuit, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 97

Apparatus for producing a signal simulating a desired periodic AC waveform comprising: first and second converter output terminals; a juncture node, at a voltage of variable magnitude relative to a common rail; a converter circuit, responsive to respective control signals applied thereto, for selectively effecting current paths between the juncture node and one of the first and second converter output terminals and between the common rail and the other of the first and second converter output terminals; a capacitance; a switching circuit, electrically connected to the capacitance, disposed to, responsive to control signals applied thereto, selectively effect a current path between the juncture node and the common rail through the capacitance; and a controller for selectively generating control signals at periodic times in the desired AC waveform to the converter circuit and to the switching circuit, to create a predetermined waveform at the converter output terminals simulating the desired AC waveform.

Claim 98

The apparatus of claim 88, wherein the controller for selectively generating the control signals to the converter circuit and means for varying the magnitude of the juncture node voltage, generates: a first control signal to the converter to cause the converter to effect a current path between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal, the magnitude of the juncture node voltage initially being at a first level; a second control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage to a second level, greater than the first level; a third control signal to the means for varying the magnitude of the juncture node voltage, to initiate a change in the magnitude of the juncture node voltage back to the first level; a fourth control signal to the converter to cause the converter to effectively break at least one of the current paths between the juncture node and the first converter output terminal and between the common rail and the second converter output terminal; and a fifth control signal to the converter to cause the converter to effect a current path between the juncture node and the second converter output terminal and between the common rail and the first converter output terminal.

Claim 99

The apparatus of claim 89, wherein: the fourth control signal to the converter causes the converter to effectively break the current path between the juncture node and the first converter output terminal; and the controller generates, after the fourth control signal but before the fifth control signal, a further control signal to the converter to cause the converter to effectively break the current path between the common rail and the second converter output terminal.

Claim 100

The apparatus of claim 89, wherein: the second control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effect a current path between the juncture node and the common rail through the capacitance; and the third control signal comprises a control signal to the switching circuit, electrically connected to the capacitance, to effectively break the current path between the juncture node and the common rail through the capacitance.

Claim 101

The apparatus of claim 88 further including means for controllably discharging the capacitance, to facilitate generation of a relatively low voltage across the converter output terminals.

Claim 102

The apparatus of claim 89 wherein said periodic times a rising edge and a falling edge of the predetermined waveform.

Claim 103

The apparatus of claim 89 wherein a present half-cycle of the predetermined waveform includes a pulse having a leading portion, an internal portion, and a trailing portion, the pulse being between the first and third portion, wherein the control signals are generated to the switching circuit such that the current path between the juncture node and the common rail is not effected during the leading portion and the trailing portion of the pulse.

Claim 104

The apparatus of claim 95 wherein the desired waveform includes a dead time between the trailing portion of the present half-cycle and a successive leading portion of the pulse of a successive half-cycle, the successive leading portion having the same position in the next successive half-cycle as the leading portion of the successive half-cycle.