System and method for improving the operation of electronically controlled motors
AssigneeNidec Motor Corporation
InventorRobert K. Hollenbeck
Life of this patent
Estimating the term…
Abstract
An electrical motor controller changes the PWM frequency that is used by a motor driver to form the fundamental frequency and voltage magnitude for the electrical power delivered to an electrical motor. The electrical motor controller compares a signal generated by a first sensor that indicates an output speed of the motor to a predetermined speed threshold and compares a signal generated by a second sensor that corresponds to phase currents in the electrical motor to a predetermined motor power threshold. These comparisons are used to set the PWM frequency for the motor driver. The PWM frequency either corresponds to a frequency in a humanly imperceptible audio range or to a frequency that is in a humanly perceptible audio range.
Claims16
An electrical motor control circuit comprising:
- a motor driver operatively connected to a power supply and operatively connected to an electrical motor;
- a first sensor configured to generate a signal indicative of a speed of the electrical motor;
- a second sensor configured to generate a signal indicative of at least one phase current in the electrical motor;
- and
- a controller operatively connected to the motor driver, the second sensor, and the first sensor, the controller being configured to:
- receive the signal generated by the first sensor;
- receive the signal generated by the second sensor;
- compare the received signal to a predetermined speed threshold;
- compare the signal generated by the second sensor to a predetermined motor power threshold;
- set a pulse width modulated (PWM) frequency to a frequency in a first range of frequencies for the motor driver in response to the received signal being less than the predetermined speed threshold;
- and
- set the PWM frequency to a frequency in a second range of frequencies for the motor driver in response to the signal received from the first sensor being greater than the predetermined speed threshold and the signal received from the second sensor being greater than the predetermined motor power threshold, all of the frequencies in the first range of frequencies being greater than each frequency in the second range of frequencies.
A method of controlling an electrical motor comprising:
- providing electrical power to an electrical motor through a motor driver with reference to frequency parameters received from a controller;
- generating with a first sensor a signal indicative of a speed of the electrical motor;
- receiving with the controller the signal generated by the first sensor;
- comparing with the controller the signal received from the first sensor to a predetermined speed threshold;
- setting a pulse width modulated (PWM) frequency to a frequency in a first range of frequencies for the motor driver in response to the signal received from the first sensor being less than the predetermined speed threshold;
- generating with a second sensor a signal indicative of at least one phase current in the electrical motor;
- receiving with the controller the signal generated by the second sensor;
- comparing with the controller the signal generated by the second sensor to a predetermined motor power threshold;
- setting the PWM frequency to a frequency in the first range of frequencies for the motor driver in response to the signal received from the first sensor being greater than the predetermined speed threshold and the signal from the second sensor being less than the predetermined motor power threshold;
- and
- setting the PWM frequency to a frequency in a second range of frequencies for the motor driver in response to the signal received from the first sensor being greater than the predetermined speed threshold and the signal received from the second sensor being greater than the predetermined motor power threshold, all of the frequencies in the first range of frequencies being greater than each frequency in the second range of frequencies.
Dependencies are inferred from the claim text.