Electric motor control strategies for using a low resolution position sensor
AssigneeHamilton Sundstrand Corporation
InventorGregory I. Rozman
Life of this patent
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Abstract
An electric motor control strategy includes using a low resolution position sensor that provides a square wave output signal. The position sensor information is converted into sinusoidal commutation signals for motor control that reduces torque ripple. In one disclosed example, square wave commutation is used at low motor speeds and a controller switches to sinusoidal commutation once a selected threshold speed of the motor is reached. In another disclosed example, sinusoidal commutation is used at all motor speeds with two different techniques for converting the square wave sensor signal into a sinusoidal commutation signal, depending on the motor speed.
Claims26
A method of controlling an electric motor using a low resolution position sensor, comprising:
- converting a square wave output signal from a low resolution position sensor into a sinusoidal motor commutation signal by generating a torque reference signal based on the square wave output signal and generating the sinusoidal motor commutation signal by multiplying the torque reference signal by a sinusoidal signal.
A motor controller, comprising:
- a low resolution position sensor;
- and
- a processor that processes a square wave output signal from the low resolution position sensor to generate a commutation signal, the processor converting the square wave output signal into a sinusoidal commutation signal by generating a torque reference signal based on the square wave output signal and generating the sinusoidal motor commutation signal by multiplying the torque reference signal by a sinusoidal signal.
A method of controlling an electric motor using a low resolution position sensor, comprising:
- using a square wave output signal from the low resolution position sensor for commutation at low motor speeds;
- switching to using sinusoidal motor commutation at motor speeds above a selected threshold, the sinusoidal motor commutation being based upon a sinusoidal motor commutation signal that is obtained by converting the square wave output signal from the low resolution position sensor into the sinusoidal motor commutation signal;
- and
- providing a plurality of sensors that equals a number of phases in the motor and using 120° commutation when using the square wave output for commutation at the low motor speeds and using 180° commutation when using the sinusoidal motor commutation signal.
A motor controller, comprising:
- a low resolution position sensor;
- a processor that processes a square wave output signal from the low resolution position sensor to generate a commutation signal, the processor converting the square wave output signal into a sinusoidal commutation signal;
- a position detector that generates a staircase signal having step increments that correspond to edges of the square wave output signal;
- and
- an integrator that integrates the staircase signal to generate a saw tooth signal that is indicative of an electrical position of the motor and the controller uses the saw tooth signal to generate the sinusoidal commutation signal.
A motor controller, comprising:
- a plurality of sensors that equals a number of phases in a motor;
- and
- a processor that processes a square wave output signal from the sensors and wherein the controller uses 120° commutation and the square wave output for commutation at low motor speeds, the controller using 180° commutation and a sinusoidal commutation signal at motor speeds above a selected threshold, the processor converting the square wave output signal into the sinusoidal commutation signal.
Dependencies are inferred from the claim text.