OUTPUT VOLTAGE CONTROL METHOD FOR VOLTAGE TYPE INVERTER

摘要

PURPOSE:To make it possible to provide a constant voltage between the ends of a motor even though a load current/power factor fluctuates by calculating a voltage drop at an output filter circuit from a power factor and an output current detected by an inverter. CONSTITUTION:A power factor detecting circuit 14 detects a power factor from an inverter output voltage Vinv. and an inverter output current Iinv. An output voltage correction circuit 15 outputs a correction amount Vc of an output voltage of a voltage drop portion due to fluctuation from a power factor Pf of the power factor detecting circuit 14 and an inverter output current detection value Ifb detected by a current detector 16 and a current detecting circuit 13. The correction amount Vc and the output voltage detection value Vfb of the inverter together with a voltage reference value Vref from a voltage reference generating circuit 9 are input to a comparative adder 12. Their difference Verr is input to a PI control circuit 10, an output voltage of a chopper circuit 3 is controlled by an output Ec of the PI control circuit 10, and the output voltage Vinv of an inverter circuit 5 is controlled.