MOTOR DRIVING APPARATUS

摘要

An inverter type driving apparatus for variable-speed control of a motor, and more particularly to a motor driving apparatus which restricts an overcurrent and the stop of the apparatus due to the overcurrent at the start of the motor operation and during acceleration. This motor driving apparatus, for driving an inverter connected to a D.C. power source in accordance with a desired output voltage and a desired output frequency, includes a current detection circuit for detecting a current supplied to the inverter from the D.C. power source, an overcurrent limiting circuit for limiting a current flowing through an output stage power device of the inverter to a level below the overcurrent level in accordance with a command from the current detection circuit to continue the operation of the inverter, and a control circuit for changing the amplitude of a carrier wave of PWM control in accordance with the period or frequency of the operation of the overcurrent limiting circuit. Alternatively, the driving apparatus includes a current detection circuit for detecting a current supplied from the D.C. power source to the inverter, an overcurrent limiting circuit for limiting a current flowing through an output stage power device of the inverter to a level below the overcurrent level in accordance with a command from the current detection circuit to continue the operation of the inverter, and a controlling circuit for changing an output voltage or an output frequency in accordance with the period or frequency of the operation of the overcurrent limiting circuit, wherein the overcurrent limiting circuit includes a current polarity detection circuit for detecting the polarity of the current outputted from each phase of the inverter in accordance with the output voltage and an ON signal of an arm in each phase, and a judgement circuit for specifying an arm in accordance with the command of the current polarity detection circuit of each phase and turning OFF the specified arm when the current detection circuit detects the current limit value.