US 8,508,178 B2 · Torque based electronic pulse width modulation control system for a switched reluctance motor

Abstract

Methods and systems of accelerating a brushless, DC electric motor based on torque may include determining a slope based on a maximum torque of the BLDC motor at a lower operating load and a maximum torque of the motor at a higher operating load, determining a period of the rotor based on sensor signals, and determining and applying a phase advance to a PWM pulse for a subsequent revolution of the rotor based on the period and the slope. In some embodiments, the amount of the phase advance is further based on maximum load optimum advance and/or maximum load speed. In some embodiments, a phase dwell is determined based on a positive torque zone and applied to the PWM pulse. In some embodiments, when the motor is operating below a given threshold, fixed-width PWM pulses are applied to subsequent revolutions of the rotor instead of phase-advanced PWM pulses.

Claims23

Dependent claims

A method of accelerating a brushless, DC (BLDC) electric motor based on torque, comprising:

applying, in the BLDC electric motor, pulse-width modulation (PWM) pulses to a stator with a plurality of stator poles to cause a rotor with a plurality of rotor poles to rotate;
determining a slope based on a maximum torque of the BLDC electric motor at a first operating load and a maximum torque of the BLDC electric motor at a second operating load, the second operating load being greater than the first operating load;
generating, by a sensor for each partial revolution of the rotor, a first signal and a second signal;
determining a period of each partial revolution based on the first signal and the second signal;
determining a phase advance for a subsequent partial revolution of the rotor based on the period of each partial revolution and the slope;
and
applying the phase advance to a subsequent PWM pulse applied to the plurality of stator poles corresponding to the subsequent partial revolution of the rotor.

4 more elements

A system for controlling pulse-width modulation for a switched reluctance motor, comprising:

a controller;
a stator of the switched reluctance motor having a plurality of stator poles and communicatively coupled to the controller;
and
a rotor of the switched reluctance motor having a plurality of rotor poles and configured to rotate in response to pulse-width modulation (PWM) pulses applied to the plurality of stator poles,
wherein the controller includes a memory having computer-executable instructions stored thereon for controlling acceleration of the switched reluctance motor based on torque, including:
determining a period of a first rotation of the rotor based on a first signal and a second signal generated by a sensor;
determining a phase advance for a subsequent rotation of the rotor based on the period of the first rotation and a slope, wherein the slope is based on a maximum torque of the switched reluctance motor at a lower operating load and a maximum torque of the switched reluctance motor at a higher operating load;
and
applying the phase advance to a subsequent PWM pulse applied to a respective stator pole corresponding to the subsequent rotation of the rotor.

6 more elements

A system for controlling pulse-width modulation (PWM) of a switched reluctance motor, comprising:

a controller in electrical communication with a plurality of stator poles of a stator of the switched reluctance motor;
and
a memory included in the controller and having computer-executable instructions for controlling pulse-width modulation (PWM) pulses delivered to the plurality of stator poles, including instructions for:
when a rotational speed of a rotor of the switched reluctance motor is less than or equal to a threshold, communicating that fixed-width PWM pulses are to be applied to the plurality of stator poles;
and
when the rotational speed of the rotor is greater than the threshold, communicating that torque-based PWM pulses are to be applied to the plurality of stator poles for each partial revolution of the rotor, including:
determining a period of an immediately previous partial revolution of the rotor based on signals generated by an optical sensor, and
determining a phase advance, a positive torque zone and a phase dwell for each torque-based PWM pulse, wherein:
the phase advance is based on the period of the immediately previous partial revolution of the rotor and a slope,
the slope is based on a maximum torque of the switched reluctance motor at a first operating load and a maximum torque of the switched reluctance motor at a second operating load, the second operating load being greater than the first operating load,
the positive torque zone is based on a portion of a radial relationship between the rotor and the stator during which a torque in a desired direction of rotor rotation is produced when a phase of the stator is energized, and
the phase dwell is based on the positive torque zone and the period of the immediately previous partial revolution of the rotor.

9 more elements

Dependencies are inferred from the claim text.

Torque based electronic pulse width modulation control system for a switched reluctance motor

Life of this patent

Torque based electronic pulse width modulation control system for a switched reluctance motor

Life of this patent

Abstract

Claims23