WINDING CHANGE-OVER SWITCH OF THREE-PHASE AC MOTOR

摘要

A winding change-over switch of a three-phase AC motor which can switch the motor current quickly while minimizing disturbance of a sine wave current and can prevent an abnormal operation or the destruction of an apparatus by detecting wrong wiring or abnormality of a component. A winding change-over section ((2(11)) connects a positive-side charging resistor (5(14)), a negative-side charging resistor (21(22)) and a capacitor (6(15)) in series between the DC positive-side bus (9) and the DC negative-side bus (10) of an inverter (7), connects the positive side of the capacitor with the cathode of a diode portion (3(12)) and then changes over a high-speed winding to from a low-speed winding under such a state that the potential of the capacitor is equalized to the DC bus voltage of the inverter. In addition, wrong wiring or abnormality of a component is detected by means of a state detector (25(27)) and a comparator (26(28)).