Microsequencer Control of a Four Quadrant Synchronous Chopper-Converter Combination

The synchronous chopper-converter combination has been shown to have great potential for improving the ac side characteristics of high power ac/dc converters. The concept of a two quadrant circuit is easily extended to four quadrant operation by the addition of a pole-reversing switch. Control requirements of the resulting configuration are considerably more complex than for a conventional dual converter, especially for transitions between the various quadrants. Important timing and sequencing constraints for proper converter operation are identified, and are seen to necessitate the use of a powerful new programmable controller concept - the microsequencer. A detailed control strategy is developed for control of the synchronous chopper-converter combination, and the corresponding state diagram is implemented using the microsequencer. Experimental results are also presented confirming four quadrant operation of the circuit.