Inverter with constant voltage to frequency ratio output capability

Claim 1

An electronic inverter comprising: a pair of DC link conductors; a plurality of output power pole terminals; an output circuit having a plurality of branch circuits connected in parallel between said DC link conductors, each of said branch circuits including a pair of switching transistors connected in series wherein each output power pole is connected to a point between the transistors in one of said branch circuits; a plurality of drive circuits for supplying base current to each of said transistors, each drive circuit including a controlled current feedback transformer which uses the collector current of the associated switching transistor to supply the required base drive current; and means for generating a switching pattern waveform for controlling the duty cycle of each of said switching transistors, said switching pattern alternating between a logic high level and a logic low level wherein each successive logic level lasts for a time which is less than the saturation time of the controlled current feedback transformer in each drive circuit while the period of the fundamental frequency of the inverter output voltage is greater than the saturation time of the controlled current feedback transformer in each drive circuit.

Claim 6

The method of operating a multiple phase electronic inverter having a transistor bridge output circuit with first and second series connected transistors in each output phase leg adapted to be connected between a pair of conductors for supplying direct current to opposite ends of each phase leg, wherein a connection point between the transistors of each phase leg serves as an output power pole, said method comprising the step of: switching said bridge output circuit transistors in accordance with two alternating complementary operating modes, such that one of said operating modes causes said first transistor in each phase leg to function in a non-commutation mode and the other one of said operating modes causes said second transistor in each phase leg to function in a non-commutation mode, wherein the time during which any transistor operating in a non-commutation mode continuously remains in the non-commutation mode is less than the saturation time of a controlled current feedback transformer in each transistor base drive circuit; and wherein the power pole voltage resulting from switching said transistors in accordance with said switching pattern has a constant voltage to frequency ratio.

Claim 7

The method of operating a multiple phase electronic inverter having a transistor bridge output circuit with first and second series connected transistors in each output phase leg adapted to be connected between a pair of conductors for supplying direct current to opposite ends of each phase leg, wherein a connection point between the transistors of each phase leg serves as an output power pole, said method comprising the step of: switching said bridge output circuit transistors in accordance with two alternating complementary operating modes, such that one of said operating modes causes said first transistor in each phase leg to function in a non-commutation mode and the other one of said operating modes causes said second transistor in each phase leg to function in a non-commutation mode, wherein the time during which any transistor operating in a non-commutation mode continuously remains in the non-commutation mode is less than the saturation time of a controlled current feedback transformer in each transistor base drive circuit; and wherein the power pole voltage resulting from switching said transistors in accordance with said switching pattern has a constant voltage to frequency ratio.