Safe start of an ac motor
AssigneeABB Schweiz AG
InventorsJoakim Lindgren, Erik Thenander
Life of this patent
Estimating the term…
Abstract
A method for safely starting an alternating-current, AC, motor from a pre-loaded stationary condition, the method including: applying a brake to immobilize the AC motor's axle; feeding the AC motor with a predefined drive signal waveform configured not to generate torque and sensing resulting stator currents; comparing the sensed stator currents with reference currents associated with the drive signal; and enabling release of the brake in response to finding that the sensed stator currents match the reference currents.
Claims19
A method for safely starting an alternating-current, AC, motor from a pre-loaded stationary condition, the method comprising:
- applying a brake to immobilize the AC motor's axle;
- feeding the AC motor with a predefined drive signal waveform configured not to generate torque and sensing resulting stator currents;
- comparing the sensed stator currents with reference currents associated with the drive signal;
- and
- enabling release of the brake in response to finding that the sensed stator currents match the reference currents.
A motor controller arranged to control an electric drive unit configured to feed an alternating-current, AC, motor,
- the motor controller comprising processing circuitry configured to perform the method of:
- applying a brake to immobilize the AC motor's axle;
- feeding the AC motor with a predefined drive signal waveform configured not to generate torque and sensing resulting stator currents;
- comparing the senses stator currents with reference currents associated with the drive signal;
- and
- enabling release of the brake in response to finding that the sensed stator currents match the reference currents.
A computer program comprising instructions to cause a motor controller arranged to control an electric drive unit configured to feed an alternating current,
- the motor controller having processing circuitry configured to perform the method of:
- applying a brake to immobilize the AC motor's axle;
- feeding the AC motor with a predefined drive signal waveform configured not to generate torque and sensing resulting stator currents;
- comparing the senses stator currents with reference currents associated with the drive signal;
- and
- enabling release of the brake in response to finding that the sensed stator currents match the reference currents, to execute the steps of the method.
Dependencies are inferred from the claim text.