Frequency dependent current control system for an AC motor

摘要

In a method and apparatus for motor control in an electric vehicle, current feedback control from an AC motor is performed using a digital arithmetic unit. The motor control equipment includes a power converter having a maximum output frequency of at least 500 Hz for driving the AC motor, and the digital arithmetic unit outputs an AC voltage command to the power converter based on current feedback from the AC motor up to the maximum output frequency of the power converter. The digital arithmetic unit includes a first subtractor for calculating the deviation between a detected value and a command value for the d-axis current, and a second subtractor for calculating the deviation between a detected value and a command value for the q-axis current. A phase calculator calculates a d-axis phase corresponding to the resistance and reactance components of the impedance of the d-axis, and a q-axis phase corresponding to the resistance components of the impedance of the q-axis. A voltage control calculator calculates control signals for the d- and q-axis voltages, due to the d-axis current deviation and the q-axis current deviation, based on the d-axis phase and the q-axis phase. The AC voltage command is output to the power converter based on the d- and q- axis voltage control signals.