Patent ID: 9077269
Filing Date: 2015-07-07
Classification: H02M,H02P

Abstract:
1. A control system for an AC electric motor, comprising: a boost converter configured to execute bidirectional DC electric power conversion between a power storage device and an electric power line such that a DC voltage on said electric power line is controlled in accordance with a voltage command value; an inverter configured to convert the DC voltage on said electric power line into an AC voltage to be applied to the AC electric motor; a pulse width modulation control unit configured to control said AC voltage output from said inverter to said AC electric motor by pulse width modulation control based on a comparison between a sinusoidal voltage command signal for operating said AC electric motor in accordance with a torque command value and a carrier signal; and a rectangular-wave voltage control unit configured to control said AC voltage output from said inverter to said AC electric motor such that a rectangular wave voltage is applied from said inverter to said AC electric motor when a modulation degree of said AC voltage by said pulse width modulation control on said DC voltage exceeds a predetermined reference value, said rectangular-wave voltage control unit controlling said inverter in accordance with said torque command value such that an absolute value of a voltage phase of said rectangular wave voltage is increased when the absolute value of torque of said AC electric motor is increased, said control system further comprising a phase restriction control unit configured to operate said AC electric motor such that rectangular wave voltage control is avoided from being performed in a state where the absolute value of said voltage phase falls within a region exceeding a limit phase set in accordance with said DC voltage and a rotational speed of said AC electric motor.