| 摘要 |
To a neutral point of a motor (14) is connected a positive electrode of an auxiliary battery (18) and an auxiliary load (20). Voltage on a power supply line to the auxiliary load (20), a neutral point voltage, is detected, and disconnection of the auxiliary battery (18) is determined when an increase of ripples in the neutral point voltage is detected. When a voltmeter cannot be used, control of the neutral point voltage is continued by measuring current of the auxiliary battery and performing control such that the current value becomes 0. A control circuit generates, in accordance with the detected rotor angle, a voltage control signal for each phase current having the same amplitude as the carrier amplitude during startup, and compares the voltage control signal to carrier to obtain a gate signal having the same frequency as the carrier frequency. A large neutral point current is prevented. |
