Adjustable frequency power supply of the inverter type

Claim 1

A power supply interposible between a source of electrical energy and the terminals of an alternating current device for effecting variable frequency energization of the device, said power supply comprising: a power source having an input connectable to said electrical energy source and having current conduction means intermittently switchable from a non conductive state into a current conductive state by a train of control pulses for providing unidirectional current of a controllable magnitude at the output thereof; first control circuitry coupled to said current conduction means for providing said train of control pusles to said current conduction means; an inverter having an input connected to said power source and an output connected to the terminals of said alternating current device, said inverter including at least a pair of current paths between the input and output thereof each containing a thyristor, second control circuitry coupled to the thyristors for providing triggering signals to the thyristors to sequentially place them in the current conductive state for providing variable frequency energization to the device, said second control circuitry including means responsive To a pulse train input signal for repetitively providing triggering signals to at least one of said thyristors, said inverter including means for transferring current between said paths and for placing said thyristors in the non conductive state; and signal means coupling said first control circuitry to said means in said second control circuitry for providing the train of control pulses of said first control circuitry to said second control circuitry for causing said second control circuitry to repetitively place at least one of the thyristors in the inverter simultaneously in the current state with the intermittently operable current conduction means in the power source for establishing a current conduction path in the power supply.