US 6,982,886 B2
Dc-ac converter parallel operation system and controller ic therefor
Kenichi Fukumoto, Kyoto (Japan)
Assigned to Rohm Co., LTD, Kyoto (Japan)
Appl. No. 10/505,061
PCT Filed Sep. 25, 2003, PCT No. PCT/JP03/12239
§ 371(c)(1), (2), (4) Date Aug. 19, 2004,
PCT Pub. No. WO2004/059826, PCT Pub. Date Jul. 15, 2004.
Claims priority of application No. 2002-373748 (JP), filed on Dec. 25, 2002.
Prior Publication US 2005/0128775 A1, Jun. 16, 2005
Int. Cl. H02M 7/48 (2006.01)
U.S. Cl. 363—72 11 Claims
OG exemplary drawing
 
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.