| 摘要 |
PURPOSE: To eliminate the phase difference when a parallel operation is started by establishing the voltage waveform of an inverter according to a waveform correction signal, correcting a reference pulse from a PLL circuit according to the signal, and operating the inverters in parallel. CONSTITUTION: A zero-crossing detector 15 for forming a zero-crossing signal of a sine wave formed by a sine wave generator 12 is provided in the control circuit 10 of an inverter 1, and a zero-crossing detector 25 for forming a zero- crossing signal of a sine wave formed by a sine wave generator 22 is provided in the control circuit 20 of an inverter 2. The zero-crossing signals are input to a phase corrector 40 in a parallel operation control board 4 to form a phase correction signal, which is input to PLL circuits 11, 21 in the circuits 10, 20 to correct the reference pulses. Accordingly, the phase difference when the parallel operation is started can be eliminated, and a cross current or the distortion of the voltage waveform of the inverter can be prevented. |
