A polyphase source of alternating current is converted to a low voltage high current regulated d.c. in a manner to conserve power and reduce costs by reduction of the number of components required therefor. To achieve this end, a single transistor is employed for each phase of the polyphase input transformer secondary winding configuration which transistor acts to perform the dual function of providing both rectification and regulation of the a.c. input.
Disclosed is a three phase AC power regulator using a single power modulating element. The element may be operated class A or in switching mode. A transformer primary is connected in Y configuration with the common junction being made through a 6 diode bridge and the single control element. The single control element thereby controls the common current in all three sections of the transformer primary. The transformer secondary windings are coupled to a second 6 diode bridge to produce a DC voltage level which is fed back to drive the control element.
A DC power supply is disclosed which returns excessive regenerative energy to the AC line. The regenerative power supply generates a DC bus voltage from an AC power line and regulates the maximum DC bus voltage by returning to the AC power line energy supplied through the DC bus from the load. A conventional full wave rectifier bridge is used to rectify the incoming AC power line voltage into a DC bus voltage. A capacitor is connected across the DC bus to dampen high frequency transient voltages which may be present on the DC bus voltage. In anti-parallel with each of the rectifying diode circuits is a power transistor which is controllable to allow current conduction in a direction opposite to its associated rectifying diode. Control circuitry, associated with each of the anti-parallel transistors, senses excessive DC bus voltage and initiates conduction of the transistor when the AC power line phases are at the correct potential for receiving the regenerative energy.
