High frequency power generator

Claim 2

A static power generator for supplying an inductive load with a.c. power at a predetermined frequency up to at least 10 KHz. in response to energy from a d.c. power supply, said generator comprising a thyristor having a power circuit and a control circuit; a capacitive storage means coupled across said power supply by a charging path and across said load by a discharge path, said charging path including the power circuit of said thyristor coupled in series with a linear inductive element for limiting the time rate of current charge (di/dt) through said thyristor; and means for cyclically and rapidly switching said thyristor into a conductive state, including driven means for supplying a train of sharp, substantially rectangular firing pulses each having a duration of not more than 20 microseconds, said thyristor being latched in said conductive state for a period each cycle sufficient to permit charging of said storage means, whereby said storage means is cyclically and sequentially charged by energy from said power supply and discharged through said load to provide said a.c. power.

Claim 3

A static power generator for supplying ac. output power to a load at a predetermined frequency up to at least 10 KHz. in response to energy from a dc. power supply, said power generaTor comprising a power inverter circuit, including first and second dc. voltage supply lines of opposite polarity, a capacitor voltage divider connected across said supply lines providing first and second input voltage sources in series, output means coupled to a point between said voltage sources for delivering generator power to the load, switching means for selectively controlling current flow between said input sources and the load, said switching means comprising a first switching path including a charging circuit connected across a first one of said voltage sources and responsive for conduction to a control signal, said charging circuit including at least one thyristor coupled to a series resonant circuit including a linear inductive element and a capacitive storage element a discharge circuit coupled to said charging circuit for transferring stored energy from the series resonant circuit to said output means, said discharge circuit including uni-directional conductive means, including a second inductive element, for controlling current flow to said load, and limit means for protecting the thyristor in said charging circuit, said limit means including at least one clamping diode coupling said discharge circuit to the second of said voltage sources; and means for providing control signal to said switching means including clock means for sequentially applying sharp, substantially rectangular high amplitude firing pulses of less than approximately 20 microseconds duration to said thyristor at predetermined intervals to cyclically and rapidly gate said thyristor into conduction, whereby energy is stored in the series resonant portion of said charging circuit during each conduction period of said thyristor and thereafter discharged through said discharge circuit to the load.

Claim 4

A static power generator for supplying ac. output power to a load at a predetermined frequency up to at least 10 KHz. in response to energy from a dc. power supply, said power generaTor comprising a power inverter circuit, including first and second dc. voltage supply lines of opposite polarity, a capacitor voltage divider connected across said supply lines providing first and second input voltage sources in series, output means coupled to a point between said voltage sources for delivering generator power to the load, switching means for selectively controlling current flow between said input sources and the load, said switching means comprising a first switching path including a charging circuit connected across a first one of said voltage sources and responsive for conduction to a control signal, said charging circuit including at least one thyristor coupled to a series resonant circuit including a linear inductive element and a capacitive storage element a discharge circuit coupled to said charging circuit for transferring stored energy from the series resonant circuit to said output means, said discharge circuit including uni-directional conductive means, including a second inductive element, for controlling current flow to said load, and limit means for protecting the thyristor in said charging circuit, said limit means including at least one clamping diode coupling said discharge circuit to the second of said voltage sources; and means for providing control signal to said switching means including clock means for sequentially applying sharp, substantially rectangular high amplitude firing pulses of less than approximately 20 microseconds duration to said thyristor at predetermined intervals to cyclically and rapidly gate said thyristor into conduction, whereby energy is stored in the series resonant portion of said charging circuit during each conduction period of said thyristor and thereafter discharged through said discharge circuit to the load.

Claim 5

A static power generator for supplying ac. output power to a load at a predetermined frequency up to at least 10 KHz. in response to energy from a dc. power supply, said power generator comprising, a power inverter circuit, including first and second dc. voltage supply lines of opposite polarity, a capacitor voltage divider connected across said supply lines providing first and second input voltage sources in series, output means coupled to a point between said voltage sources for delivering generated power to the load, switching means for selectively controlling current flow between said input sources and the load, said switching means comprising first and second oppositely poled switching paths coupled respectively to said first and second voltage sources, each of said switching paths including a charging circuit responsive for conduction to a control signal and comprising at least one thyristor coupled to a series resonant circuit including a first linear inductive element and a capacitive storage element a discharge circuit coupled to said charging circuit for transferring stored energy from the capacitive storage element in said switching path to said output means and comprising uni-directional conductive means, including a second inductive element, for controlling current flow to said load, limit means for protecting the thyristors in said switching paths, said limit means including at least one clamping diode coupling each of said respective discharge circuits to the oppositely poled voltage source; and means for providing control signals to said switching means including clock means for sequentially applying sharp, substantially rectangular high amplitude firing pulses of less than approximately 20 microseconds duration alternately to the thyristors in said oppositely poled switching paths at predetermined intervals to cyclically and rapidly gate said thyristors into conduction, whereby the capacitive storage element in one of said switching paths charges while the capacitive storage element in the other, oppositely poled switching path discharges into the common loaD.

Claim 6

A static power generator for supplying ac. output power to a load at a predetermined frequency up to at least 10 KHz. in response to energy from a dc. power supply, said power generator comprising, a power inverter circuit, including first and second dc. voltage supply lines of opposite polarity, a capacitor voltage divider connected across said supply lines providing first and second input voltage sources in series, output means coupled to a point between said voltage sources for delivering generated power to the load, switching means for selectively controlling current flow between said input sources and the load, said switching means comprising first and second oppositely poled switching paths coupled respectively to said first and second voltage sources, each of said switching paths including a charging circuit responsive for conduction to a control signal and comprising at least one thyristor coupled to a series resonant circuit including a first linear inductive element and a capacitive storage element a discharge circuit coupled to said charging circuit for transferring stored energy from the capacitive storage element in said switching path to said output means and comprising uni-directional conductive means, including a second inductive element, for controlling current flow to said load, limit means for protecting the thyristors in said switching paths, said limit means including at least one clamping diode coupling each of said respective discharge circuits to the oppositely poled voltage source; and means for providing control signals to said switching means including clock means for sequentially applying sharp, substantially rectangular high amplitude firing pulses of less than approximately 20 microseconds duration alternately to the thyristors in said oppositely poled switching paths at predetermined intervals to cyclically and rapidly gate said thyristors into conduction, whereby the capacitive storage element in one of said switching paths charges while the capacitive storage element in the other, oppositely poled switching path discharges into the common loaD.

Claim 7

A static power generator as set forth in claim 3 wherein said means for supplying control signals to said switching means comprises an oscillator, a clock pulse generator responsive to the output frequency of said oscillator, and digital sequencer means controlled by said clock pulse generator and responsive to the output frequency of said oscillator for emitting, in sequence, said train of sharp, substantially rectangular firing pulses.

Claim 8

A static power generator as set forth in claim 4 further comprising a power regulator circuit, said power regulator circuit including means for setting the operating level of the power generator by selectively adjusting the operating frequency of the oscillator, means for controlling the rate at which the oscillator will respond to changes in the operating level settings, and means for overriding said means for setting the operating level of the generator when said oscillator is turned off so as to simulate a zero power level setting and to minimize current drain through the oscillator when the power generator is idle.

Claim 9

A static power generator as set forth in claim 5 further including sensor means for detecting the amount of power being drawn by the load, and comparator means for comparing the level of the power actually being drawn against the power level setting of the regulator circuit and for applying a corrective signal to the oscillator when a difference appears between said power levels.

Claim 10

A static power generator as set forth in claim 5 further including sensor means for detecting the actual voltage level at which said output power is supplied to the load, and comparator means for comparing said actual voltage against a pre-set voltage and for applying a corrective signal to the oscillator when the output voltage exceeds the pre-set level.

Claim 11

A static power generator as set forth in claim 3 wherein said charging circuit and said discharge circuit are characterized by respective charging and discharging periods not exceeding more than one half the period of the generated output frequency.

Claim 12

A static power generator as set forth in claim 3 wherein said thyristors are silicon rectifiers and a plurality of said power inverter circuits are combined in parallel relationship and driven by said means for providing control signals for providing energy, on a time sharing basis, to a common load.

Claim 13

A static power generator as set forth in claim 3 wherein the uni-directional conductive means in the discharge circuit of each of said oppositely poled switching paths comprises a blocking diode connected in series with a saturable reactor, said saturable reactor being sized to remain unsaturated during the conduction period of the associated charging circuit and thereafter for a period of time sufficient to cause the thyristor in said charging circuit to commutate, whereby the respective charging and discharging circuits of each of said switching paths are effectively isolated from one another during the respective charging and discharge cycles of the storage element located therein.

Claim 14

A static power generator as set forth in claim 3 wherein the uni-directional conductive means in the discharge circuit of each of said oppositely poled switching paths comprises at least one thyristor connected in series with a second linear inductive element, said discharge circuit thyristors being operatively coupled to said means for providing control signals for conducting alternately with the corresponding charging circuit thyristor located in the same switching path, whereby the respective charging and discharge circuits of each of said switching paths are isolated from one another during the respective charging and discharge cycles of the storage element located therein.

Claim 15

An improved control circuit, particularly suited for use in a static high frequency power generator of the type which includes a power inverter circuit in which thyristors and inductive elements are utilized in controlling the alternate chArging and discharge of capacitive storage means, for cyclically and rapidly firing thyristors into conduction, said control circuit comprising an oscillator, a clock pulse generator responsive to the output frequency of said oscillator, digital sequencer means controlled by said clock pulse generator and responsive to the output frequency of said oscillator for emitting, in sequence, a train of sharp, substantially rectangular firing pulses each having a duration of not more than 20 microseconds, and a series of separate, parallel circuit paths corresponding in number to the thyristors in said inverter circuit for delivering said pulse signals to the respective thyristors, each circuit path including a pulse transformer having an input winding coupled to said digital sequencer means and an output winding coupled to said thyristor, said transformer having a response characteristic selected to retain the substantially rectangular shape of the individual pulses, and amplification means in circuit with said pulse transformer for increasing the amplitude of the pulses passing to the respective thyristors.

Claim 16

An improved control circuit, particularly suited for use in a static high frequency power generator of the type which includes a power inverter circuit in which thyristors and inductive elements are utilized in controlling the alternate chArging and discharge of capacitive storage means, for cyclically and rapidly firing thyristors into conduction, said control circuit comprising an oscillator, a clock pulse generator responsive to the output frequency of said oscillator, digital sequencer means controlled by said clock pulse generator and responsive to the output frequency of said oscillator for emitting, in sequence, a train of sharp, substantially rectangular firing pulses each having a duration of not more than 20 microseconds, and a series of separate, parallel circuit paths corresponding in number to the thyristors in said inverter circuit for delivering said pulse signals to the respective thyristors, each circuit path including a pulse transformer having an input winding coupled to said digital sequencer means and an output winding coupled to said thyristor, said transformer having a response characteristic selected to retain the substantially rectangular shape of the individual pulses, and amplification means in circuit with said pulse transformer for increasing the amplitude of the pulses passing to the respective thyristors.