Speed measurement system for speed control of high-speed motors
View Patent ↗A system for measuring speed of a high-speed motor using a moving average filter. A position sensor generates a rotor position signal. A signal processing module determines a rotor angle from the rotor position signal. A speed observer module calculates a raw speed of the motor from the rotor angle. A filter module selectively generates a filtered speed of the motor from the raw speed of the motor. A frequency-to-period converter module calculates a rotor period from one of the raw speed of the motor and the filtered speed of the motor. A divider module calculates number of points in a moving average from the rotor period. A moving average filter module adjusts a window size of the moving average to the rotor period. A moving average filter removes ripple and harmonics of the ripple from the raw speed of the motor.
1. A method of measuring speed of a high-speed motor, comprising:
generating a rotor position signal;
determining a rotor angle from the rotor position signal;
calculating a raw speed of the motor from the rotor angle and generating a raw speed signal;
selectively generating a filtered speed of the motor from the raw speed of the motor and generating a filtered speed signal by filtering the raw speed signal;
calculating a rotor period from one of the raw speed and the filtered speed signals;
calculating a number of sample points in a moving average using the rotor period; and
controlling the speed of the motor based on the number of sample points in the moving average.
2. The method of claim 1 further comprising adjusting a window size of the moving average to the rotor period.
3. The method of claim 2 further comprising removing ripple and harmonics of the ripple from the raw speed of the motor.
4. The method of claim 3 further comprising removing harmonics of the ripple from the raw speed of the motor.
5. The method of claim 2 further comprising calculating the window size based on the number of points in the moving average and a sampling time.
6. A system for measuring speed of a high-speed motor, comprising:
a position sensor that generates a rotor position signal;
a signal processing module that determines a rotor angle from the rotor position signal;
a speed observer module that calculates a raw speed of the motor from the rotor angle;
a filter module that selectively generates a filtered speed of the motor from the raw speed of the motor;
a frequency-to-period converter module that calculates a rotor period from one of the raw speed of the motor and the filtered speed of the motor; and
a divider module that calculates a number of sample points in a moving average using the rotor period.
7. The system of claim 6 further comprising a moving average filter module that adjusts a window size of a moving average filter to the rotor period.
8. The system of claim 7 further comprising a moving average filter that removes ripple from the raw speed of the motor.
9. The system of claim 8 wherein the moving average filter removes harmonics of the ripple from the raw speed of the motor.
10. The system of claim 7 wherein the moving average filter module calculates the window size based on the number of points in the moving average and a sampling time.