Patent ID: 7859866
Filing Date: 2010-12-28
Classification: H02M,H05B,Y02B

Abstract:
1. A parallel running system of a plurality of DC-AC conversion apparatuses, the system comprising: a transformer having a primary winding with a center tap and at least one secondary winding, the center tap being connected to a first potential point of a DC power source; a first semiconductor switch connected between one end of the primary winding and a second potential point of the DC power source; a second semiconductor switch connected between the other end of the primary winding and the second potential point; and N DC-AC conversion apparatuses, N being an integer of 2 or more, comprising a controller IC for controlling the first and second semiconductor switches for driving a load, wherein the controller IC comprises: a current detection signal input terminal to which a current detection signal is inputted, the current detection signal being based on a current flowing through the load connected to the at least one secondary winding; an oscillator block for generating a first triangular wave signal and a second triangular wave signal, the second triangular wave signal being reversed relative to the first triangular wave signal; a PWM control signal generation circuit for generating a PWM control signal for switching the first and second semiconductor switches based on the first triangular wave signal, the second triangular wave signal, and an error signal, the error signal being generated based on the current detection signal; a connection terminal to which a resistor for frequency decision is to be connected, the resistor for frequency decision being used for setting frequencies of the first and second triangular wave signals, wherein the resistor for frequency decision is connected to only the connection terminal provided in one of the N DC-AC conversion apparatuses, so that only the oscillator block of said one of the DC-AC conversion apparatuses generates the first and second triangular wave signals, wherein only the first triangular wave signal of the first and second triangular wave signals generated from said one of the DC-AC conversion apparatuses is supplied to other DC-AC conversion apparatuses, and wherein all of the N DC-AC conversion apparatuses perform in-phase PWM control in synchronization with each other by using the first triangular wave signal.