Patent ID: 8520412

Claim:
A synchronous operating system for a plurality of DC-AC converters, oscillator capacitors of the plurality of DC-AC converters being commonly connected, AC power from the plurality of DC-AC converters being supplied to a plurality of loads, each of the plurality of DC-AC converters comprising: a resonant circuit including a capacitor connected to at least one of primary and secondary windings of a transformer, an output thereof being connected to the load; a plurality of switching elements of network configuration to supply AC power to the load through the resonant circuit; a first oscillator configured to generate a first triangular wave signal whose inclination for charging the oscillator capacitor and inclination for discharging the oscillator capacitor are the same; a second oscillator configured to generate a second triangular wave signal that is an inverted signal of the first triangular wave signal; an error amplifier configured to amplify a voltage related to a current passing through the load with respect to a reference voltage; a signal generator of an initialize signal configured to alternately allow a first drive signal and a second drive signal during every half period of the first triangular wave signal, wherein the first drive signal is generated for driving at least one of the plurality of the switching elements to supply current to the load, and the second drive signal is generated for driving at least one of the rest of the plurality of the switching elements to supply current to the load in an opposite manner to that of the first drive signal; and wherein: in a period while the first drive signal is allowed to generate, the first triangular wave signal and an output of the error amplifier are compared to generate the first drive signal with a pulse width related to the current of the load; and in a period while the second drive signal is allowed to generate, the second triangular wave signal and the output of the error amplifier are compared to generate the second drive signal having a pulse width substantially equal to that of the first drive signal and an opposite phase with respect to the first drive signal.