Control device for alternating-current electric motor

A control device for an alternating-current electric motor, comprising:

• an inverter that converts direct-current power to alternating-current power by operations of a plurality of switching elements under PWM control, and supplies the alternating-current power to the alternating-current electric motor;
• and
• a processor programmed to:
• acquire a rotation angle of the alternating-current electric motor at a timing of a peak or a valley of a triangular wave carrier of the PWM control, from a rotation angle sensor that divides a mechanical angle by a number of pole pairs of the alternating-current electric motor;
• use a current value acquired from a current sensor detecting a current flowing to the alternating-current electric motor and the rotation angle of the alternating-current electric motor to perform a control computation in a (N/2) cycle (N is a natural number) of the carrier;
• at the acquisition of the current value detected by the current sensor, acquire an average of the current value in a carrier half cycle as a period between a peak and a valley of the carrier, or acquire a current value regarded as an average of the current value at an acquirable timing;
• and
• when a detection delay time is defined as a time during which a current signal flowing to the alternating-current electric motor passes through the current sensor and a reception circuit of the control device and is recognized as a value usable for the control computation, acquire the current value detected by the current sensor at a timing delayed by the detection delay time from a timing of a peak or valley of the carrier.