Patent ID: 6982886
Filing Date: 2006-01-03
Classification: H02J,H02M,H05B,Y02B

Abstract:
1. A parallel operating system of operating in parallel a multiplicity (N) of dc-ac converters, each dc-ac converter comprising: a transformer having a primary winding and at least one secondary winding connected to a load; a semiconductor switch circuit for flowing current from a dc power supply to said primary winding in a first direction and a second direction alternately; a current detection circuit for detecting the current flowing through said load and generating a current detection signal; an oscillator block for generating a triangular wave signal and a clock signal synchronized with said triangular wave signal when connected to a frequency determination capacitor and a frequency determination resistor; and a PWM control circuit for providing said semiconductor switch circuit with a PWM-controlled switch drive signal upon receipt of said triangular wave signal, clock signal, and current detection signal, wherein said system is adapted to: allow said frequency determination capacitor and frequency determination resistor to be connected to only one of said N dc-ac converters to generate said triangular wave signal and said clock signal from the oscillator block associated with said one dc-ac converter; and supply said triangular wave signal and said clock signal generated by said one dc-ac converter to the rest of said N dc-ac converters, whereby said N dc-ac converters are synchronized to said clock signal in performing in-phase PWM control of said N dc-ac converters.