Power converter employing non-saturating interphase transformer

A power converter for use with a d.c. power source to produce a modulated output voltage comprising in combination, first and second chopper legs, first and second gate controlled thyristors coupled respectively in the first and second chopper legs, first and second gating means for initiating conductive cycles of the respective chopper legs, first and second commutating means for terminating the conductive cycles of the respective chopper legs, duty cycle control means operative upon said gating means and commutating means for varying the time relationship between the operation of the gating means and commutating means thereby to vary the duty cycle of the respective chopper legs, said duty cycle control means including means for operating the respective chopper legs out of phase with respect to each other, interphase transformer means coupled to the output of the respective chopper legs for combining the outputs thereof to form a single chopper output, said duty cycle control means including means for conforming the duty cycle of said second leg to the duty cycle of said first leg thereby to prevent average d.c. current flow between the outputs of the respective legs through the interphase transformer.

A power converter for use with a d.c. power source comprising in combination, first and second chopper legs, first and second gate controlled thyristors coupled respectively in the first and second chopper legs, said chopper legs having inputs coupled to the d.c. supply, gating means for initiating a conductive cycle of the respective thyristors and commutating means for terminating such cycle, duty cycle control means for adjusting the period between operation of the gating means and the commutating means, said duty cycle control means including means for conforming the duty cycle of one of said thyristors to that of the other of said thyristors, and an interphase transformer for combining the outputs of the respective chopper legs to produce a single output voltage controlled by the duty cycle of said chopper.

A power converter for use with a d.c. power source comprising in combination, a dual chopper having first and second chopper legs with first and second gate controlled thyristors interposed in the respective legs, first and second commutating means associated with the respective legs of the chopper for commutating the chopper thyristors, each of said commutating means including a commutating gate controlled thyristor, interphase transformer means merging the output signals of the respective chopper legs into a single chopper output, and gate signal producing means for driving all of the thyristor gates, said gate signal producing means including means for varying the on-time to off-time ratio for said first chopper leg, and means for causing the on-time to off-time ratio for said second chopper leg to match that of the first chopper leg whereby the duty cycle of the respective legs is varied in the synchronism thereby to avoid average d.c. current between the respective chopper legs through the interphase transformer means.

A power circuit comprising in combination, a storage battery for supplying d.c. power, said storage battery having an internal resistance, a chopper having an input and an output, said input being coupled to the storage battery, means for producing a control signal for controlling the duty cycle of the chopper thereby to control the average voltage at the output thereof, a load coupled to the chopper output for drawing an average current dependent upon the average voltage level at the chopper output, said chopper drawing an RMS current from the battery through the internal resistance thereof for delivering said average current to the load, said chopper comprising a pair of chopper legs operated out of phase with respect to each other and means combining the respective outputs of the out of phase legs thereby to raise said average current with respect to said RMS current.

A power converter for use with a source of d.c. power comprising in combination, a chopper circuit having a plurality of chopper legs, switching means within the respective legs, control means for turning the switching means on and off in a controlled phase relationship, duty cycle means operative upon said control means for establishing the duty cycle of said chopper, interphase transformer means for combining the outputs of the respective chopper legs to produce a single chopper output, and means associated with said duty cycle control means for maintaining the duty cycles of all the legs at identical levels, thereby to produce substantially identical average d.c. outputs at each of the legs for preventing saturation of the interphase transformer means.

A power converter for use with a d.c. power source comprising in combination, first and second chopper legs, first and second switch means coupled respectively in the first and second chopper legs, said chopper legs having inputs coupled to the d.c. supply, control means for turning the switch means on and off in a controlled phase relationship, duty cycle control means operative on the control means for varying the duty cycle of the chopper, said duty cycle control means including means for conforming the duty cycle of one of said switch means to that of the other of said switch means, and an interphase transformer for combining the outputs of the respective chopper legs to produce a single output voltage controlled by the duty cycle of said chopper.