| 摘要 |
A parallel inverter system needs neither a dedicated line for synchronizing common portions nor switching operations, and includes a plurality of inverter units operating in parallel. An inverter control circuit of each inverter unit includes a sinusoidal signal generating circuit, a PWM control signal generating circuit, a phase difference circuit, a frequency difference circuit, and a feedback circuit. The feedback circuit inputs to the sinusoidal signal generating circuit an addition result value which is obtained by adding to a commanded value for reference frequency a value obtained from multiplication of a phase difference by a predetermined gain and a value obtained from multiplication of a frequency difference by a predetermined gain. The phase difference among outputs from the inverter units occurring in the parallel operation of the inverter units is reduced by changing the output frequencies of the inverter units.
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