Motor control apparatus

A motor control apparatus comprising:

• a converter circuit;
• a smoothing capacitor;
• an inverter circuit;
• a torque limiter;
• and
• a field-weakening limiter, wherein
• the converter circuit is configured to convert alternating current power from an alternating current power supply to direct current power,
• the smoothing capacitor is configured to smooth the direct current power,
• the inverter circuit is configured to convert the smoothed direct current power to alternating current power for driving a motor,
• the torque limiter is configured to limit torque on the motor based on a direct current voltage to be applied to the smoothing capacitor,
• the field-weakening limiter is configured to limit field-weakening based on the direct current voltage to be applied to the smoothing capacitor,
• the torque limiter is configured to limit torque in a power running direction on the motor to a first torque value upon the direct current voltage dropping to a first threshold,
• the field-weakening limiter is configured to limit the field-weakening to a first field-weakening value and raise an induced voltage of the motor to raise the direct current voltage upon the direct current voltage dropping to the first threshold,
• the torque limiter is configured to limit the torque in the power running direction on the motor to a second torque value greater than the first torque value upon the direct current voltage rising from the first threshold to a second threshold greater than the first threshold, and
• the field-weakening limiter is configured to limit the field-weakening to a second field-weakening value greater than the first field-weakening value upon the direct current voltage rising from the first threshold to the second threshold greater than the first threshold.