DC-to-DC power conversion with high current output

Claim 2

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges for connecting a DC power source to the primary side of the transformer, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures for connecting the secondary side of the transformer to a load; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 3

The power conversion apparatus of claim 1 wherein the transformer is a co-axial winding transformer.

Claim 4

The power conversion apparatus of claim 2 wherein the secondary side of the transformer is constructed from a copper tube and the primary side of the transformer is enclosed within the tube.

Claim 5

The power conversion apparatus of claim 3 wherein the transformer includes two straight cooper tubes connected by a cooper strap to form the secondary side.

Claim 6

The power conversion apparatus of claim 1 wherein the DC power source is an AC to DC converter.

Claim 7

The power conversion apparatus of claim 1 wherein the switching devices are transistors.

Claim 8

The power conversion apparatus of claim 6 wherein the switching devices are insulated gate bipolar transistors.

Claim 9

The power conversion apparatus of claim 1 wherein the bias voltage is provided by a DC to DC converter having an input connected to the DC power source and an output which provides the bias voltage.

Claim 10

The power conversion apparatus of claim 1 wherein the rectifier structures include multiple diodes connected in parallel.

Claim 11

The power conversion apparatus of claim 9 wherein the multiple diodes in the rectifier structures are configured symmetrically to provide approximately equal current sharing among the diodes.

Claim 12

The power conversion apparatus of claim 1 wherein the output side circuit includes: (a) first and second bus conductors connected to the secondary side of the transformer; (b) a common bus conductor providing a first output terminal for the power conversion apparatus; (c) a rectifier assembly connecting the first rectifier structure between the first bus conductor and the common bus conductor and the second rectifier structure between the second bus conductor and the common bus conductor; and (d) first and second inductors, the first inductor connecting the first bus conductor to a second output for the power conversion apparatus and the second inductor connecting the second bus conductor to the second output for the power conversion apparatus.

Claim 13

The power conversion apparatus of claim 11 wherein the first and second inductors are ferrite cores placed around the first and second bus conductors.

Claim 14

The power conversion apparatus of claim 11 including cooling means for cooling the rectifier assembly.

Claim 15

The power conversion apparatus of claim 13 wherein the cooling means includes a channel in the common bus conductor which is capable of containing a cooling fluid.

Claim 16

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges for connecting a DC power source to the primary side of the transformer, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures to produce a DC output across the first and second terminals of the output, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 17

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges for connecting a DC power source to the primary side of the transformer, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures to produce a DC output across the first and second terminals of the output, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 18

The power conversion apparatus of claim 15 wherein the transformer is a co-axial winding transformer.

Claim 19

The power conversion apparatus of claim 15 wherein the DC power source is an AC to DC converter.

Claim 20

The power conversion apparatus of claim 15 wherein the bias voltage is provided by a DC to DC converter having an input connected to the DC power source and an output which provides the bias voltage.

Claim 21

The power conversion apparatus of claim 15 wherein the rectifier structures include multiple diodes connected in parallel.

Claim 22

The power conversion apparatus of claim 19 wherein the multiple diodes in the rectifier structures are configured symmetrically to provide approximately equal current sharing among the diodes.

Claim 23

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges connected in parallel across a DC power source, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures for connecting the secondary side of the transformer to a load; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 24

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges connected in parallel across a DC power source, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures for connecting the secondary side of the transformer to a load; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 25

The power conversion apparatus of claim 21 wherein the transformer is a co-axial winding transformer.

Claim 26

The power conversion apparatus of claim 21 wherein the DC power source is an AC to DC converter.

Claim 27

The power conversion apparatus of claim 21 wherein the bias voltage is provided by a DC to DC converter having an input connected to the DC power source and an output which provides the bias voltage.

Claim 28

The power conversion apparatus of claim 21 wherein the output side circuit includes first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output.

Claim 29

The power conversion apparatus of claim 25 wherein the rectifier structures include multiple diodes connected in parallel.

Claim 30

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges connected in series across a DC power source, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures for connecting the secondary side of the transformer to a load; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 31

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges connected in series across a DC power source, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer and for connecting and disconnecting a unipolar bias voltage source having a voltage of polarity opposite to that of the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures for connecting the secondary side of the transformer to a load; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures, and for further controlling the switching devices to connect the unipolar bias voltage to the primary side of the transformer to drive a current in a one of the rectifier structures to zero in a period of time after a one of the converter bridges disconnects the DC source from the primary of the transformer and before an other of the converter bridges connects the DC source to the primary of the transformer.

Claim 32

The power conversion apparatus of claim 27 wherein the transformer is a co-axial winding transformer.

Claim 33

The power conversion apparatus of claim 27 wherein the DC power source is an AC to DC converter.

Claim 34

The power conversion apparatus of claim 27 including first and second input side capacitors connected in series across the DC power source and wherein the first converter bridge is connected in parallel with the first input side capacitor and wherein the second converter bridge is connected in parallel with the second input side capacitor.

Claim 35

The power conversion apparatus of claim 27 wherein the bias voltage is provided by a DC to DC converter having an input connected to the DC power source and an output which provides the bias voltage.

Claim 36

The power conversion apparatus of claim 27 wherein the bias voltage is applied across first and second bias voltage capacitors connected in series, and wherein the bias voltage across the first bias voltage capacitor is the bias voltage source for the first converter bridge and the bias voltage across the second bias voltage capacitor is the bias voltage source for the second converter bridge.

Claim 37

The power conversion apparatus of claim 27 wherein the output side circuit includes first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output.

Claim 38

The power conversion apparatus of claim 33 wherein the rectifier structures include multiple diodes connected in parallel.

Claim 41

The method of claim 35 comprising the additional step of opening the fourth switching device to remove the unipolar bias voltage from the primary of the transformer after the step of closing the first switching device to apply the DC source voltage having a first polarity to the transformer.

Claim 42

The method of claim 35 wherein the step of closing the third switching device to apply the DC source voltage having a second polarity to the transformer and the step of opening the second switching device to remove the unipolar bias voltage from the transformer are accomplished approximately simultaneously.

Claim 43

The method of claim 35 comprising the additional step of repeating steps (a)-(g) at a frequency of at least 20 kHz.

Claim 44

The method of claim 35 wherein the steps of closing and opening the first and third switching devices include the step of switching devices in a converter bridge to connect and disconnect a DC voltage source to and from the primary of the transformer, and wherein the steps of closing and opening the second and fourth switching devices include the step of switching the devices in the converter bridge to connect a unipolar bias voltage source to and from the transformer.

Claim 45

A co-axial winding transformer for high currents, comprising: (a) two straight conducting tubes connected by a conducting strap to form a secondary winding of the transformer; (b) primary windings enclosed within the conducting tubes; and (c) a transformer core positioned around the conducting tubes.

Claim 46

A co-axial winding transformer for high currents, comprising: (a) two straight conducting tubes connected by a conducting strap to form a secondary winding of the transformer; (b) primary windings enclosed within the conducting tubes; and (c) a transformer core positioned around the conducting tubes.

Claim 47

The transformer of claim 40 wherein the conducting tubes and conducting strap are made of copper.

Claim 48

A rectifier and filter apparatus for the output side of a high current power conversion apparatus, comprising: (a) first and second bus conductors adapted for connection to the secondary of a transformer; (b) a common bus bar; (c) a rectifier assembly including first and second diode configurations, the rectifier assembly connecting the first diode configuration between the first bus conductor and the common bus bar and the second diode configuration between the second bus conductor and the common bus bar; and (d) ferrite cores placed around the first and second bus conductors to form output side inductances.

Claim 49

A rectifier and filter apparatus for the output side of a high current power conversion apparatus, comprising: (a) first and second bus conductors adapted for connection to the secondary of a transformer; (b) a common bus bar; (c) a rectifier assembly including first and second diode configurations, the rectifier assembly connecting the first diode configuration between the first bus conductor and the common bus bar and the second diode configuration between the second bus conductor and the common bus bar; and (d) ferrite cores placed around the first and second bus conductors to form output side inductances.

Claim 50

The rectifier and filter apparatus of claim 42 additionally comprising cooling means for cooling the rectifier assembly.

Claim 51

The rectifier and filter apparatus of claim 43 wherein the cooling means includes a channel in the common bus bar which is capable of containing a cooling fluid.

Claim 52

The rectifier and filter apparatus of claim 42 wherein the diode configurations include multiple diodes connected in parallel such that there is approximately equal current sharing among the diodes in each configuration.

Claim 53

The rectifier and filter apparatus of claim 45 wherein the diodes are dual Shottky diodes.

Claim 54

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges for connecting a DC power source to the primary side of the transformer, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, a one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output, and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures to produce a DC output across the output terminals.

Claim 55

DC to DC power conversion apparatus, comprising: (a) a transformer having a primary side and a secondary side; (b) first and second converter bridges for connecting a DC power source to the primary side of the transformer, each converter bridge including switching devices for connecting and disconnecting the DC power source to the primary side of the transformer; (c) an output side circuit including first and second rectifier structures having anode ends and cathode ends, first and second output side inductors, and an output, a one of the anode ends or cathode ends of the first and second rectifier structures connected together and connected to a first terminal of the output, the other of the cathode end or anode end of the first rectifier structure connected to a first end of the secondary side of the transformer and the other of the cathode end or anode end of the second rectifier structure connected to a second end of the secondary side of the transformer, and the first output side inductor connected between the other of the cathode end or anode end of the first rectifier structure and a second terminal of the output, and the second output side inductor connected between the other of the cathode end or anode end of the second rectifier structure and the second terminal of the output; (d) control means for controlling the switching devices to alternately connect the DC source to the primary through the first converter bridge and the second converter bridge to produce a waveform on the secondary side of the transformer which is rectified by the first and second rectifier structures to produce a DC output across the output terminals.