THE SIGN SIGNAL GENERATOR FOR PAM DRIVE OF A PAM DRIVE APPARATUS

摘要

PURPOSE: A pulse amplitude modulation driving sine signal generating circuit of a pulse amplitude modulation driver is provided to minutely control a pulse width according to a level of a voltage which is supplied to an inverter. CONSTITUTION: A rectifier(61) rectifies an input AC power supply to obtain a DC voltage. A choke coil(62) and a smoothing capacitor(63) remove an AC component included in the DC voltage from rectifier(61). An inverter(64) converts the DC voltage outputted from smoothing capacitor(63) into a three-phase AC power supply and supplies the three-phase AC power supply to a motor(M). A switching element(Q1) is connected to a front terminal of smoothing capacitor(63) in parallel and controls charge and discharge operations of smoothing capacitor(63) according to a switching signal. A zero voltage detector(65) detects a zero point of an input AC power supply. A voltage level detector(67) detects a voltage across smoothing capacitor(63). A pulse amplitude modulation driving signal generator(66) controls an operation of the switching element(Q1) according to a zero point generating signal from the zero voltage detector(65) and a level of the voltage detected by voltage level detector(67).