CONTROL OF INVERTER CIRCUIT POWER SUPPLY

摘要

PROBLEM TO BE SOLVED: To obtain a method of controlling an inverter circuit that can acquire a charge pump power supply voltage without providing a power supply voltage monitor circuit. SOLUTION: In a motor control apparatus using a charge pump power supply C in a 3-phase inverter circuit to supply a voltage to a motor coil, a duty ratio of the PWM output waveform is determined by arithmetic process of a triangular wave signal, and the reference value for comparison with such triangular wave signal and an M microcomputer including a program for determining the ON/OFF timings of the upper/lower arms of a switching element of the inverter circuit generates the time to forcibly turn OFF the upper arm to prevent voltage drop of the charge pump power supply C, when the motor rotating speed is low (including the stop condition) and an operation torque is high so that the upper arm of the inverter circuit always becomes ON and thereby the duty ratio of the PWM output waveform does not become 100% even when the command torque rises.