Method and apparatus for measuring speed of a brush motor

摘要

A system for determining motor speed of a brush DC motor in an apparatus, including circuitry for sensing current in the brush DC motor; a first filter for receiving a substantially DC component of the sensed current and parameters corresponding to the brush DC motor, for calculating a speed estimate thereof; an adaptive bandpass filter having a center frequency corresponding to the speed estimate of the first filter, for receiving the sensed current and substantially isolating a periodic current fluctuation thereof; a block for determining a frequency of the periodic current fluctuation, the periodic current fluctuation frequency being a commutation frequency of the brush DC motor and corresponding to motor speed of the brush DC motor. The motor speed determined from the periodic current fluctuation of the motor current is then used to control the speed of the motor.

主权项

1. In an apparatus having a brush DC motor, a system for determining motor speed thereof, comprising:
memory having stored therein model parameters corresponding to the brush DC motor; first circuitry for sensing a current in windings of the brush DC motor and digitizing same; a first filter for receiving a substantially DC component of the sensed, digitized current and the stored model parameters and for calculating a speed estimate of the brush DC motor; an adaptive bandpass filter having a center frequency corresponding to the speed estimate of the first filter, for filtering the sensed, digitized current of the brush DC motor to isolate a periodic current fluctuation component thereof; a zero crossing detect block for receiving the isolated periodic current fluctuation component of the adaptive bandpass filter and identifying consecutive zero crossings thereof, a time period between consecutive zero crossings corresponding to motor speed of the brush DC motor; and a calibration block for regularly calibrating the first filter block.