Motor control using third harmonic stator voltage signal
AssigneeWhirlpool Corporation
InventorJulio C. Moreira
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Abstract
A method and apparatus for controlling operation of a brushless permanent magnet motor wherein a signal containing third harmonic component of the motor flux density is acquired and filtered to isolate the third harmonic components, the filtered third harmonic components are integrated to produce a time integral signal, the back EMF of one stator phase is sensed and the resulting EMF signal is filtered zero crossings of the filtered signals are sensed and then employed to drive an inverter controller.
Claims18
A method for controlling a brushless permanent magnet motor, said motor having stator phase windings relative to which the rotor rotates and in which are induced a back EMF force having a fundamental component and a third harmonic component, said motor being driven by an inverter bridge operatively coupled thereto, comprising the steps of:
- generating a first signal including the third harmonic component;
- filtering the first signal and generating from the first signal a second signal containing substantially only the third harmonic component;
- integrating the second signal and generating a third signal that comprises the integral of the second signal;
- detecting zero crossings of the third signal;
- generating a fourth signal that includes a stator voltage for one stator winding;
- filtering the fourth signal and generating a fifth signal that comprises a low pass filtered version of the fourth signal;
- detecting zero crossings of the fifth signal;
- and
- synchronizing application of stator currents by the inverter with motor operation based on the detection of the zero crossings of the third and fifth signals.
A system for controlling a brushless permanent magnet motor, said motor having stator phase windings relative to which the rotor rotates and in which are induced a back EMF force having a fundamental component and a third harmonic component, said motor being driven by an inverter bridge operatively coupled thereto, comprising:
- means for generating a first signal including the third harmonic component;
- a filter operatively coupled to the means for generating the first signal, which filter generates a second signal containing substantially only the third harmonic component;
- an integrator unit coupled to the filter and configured to generate a third signal signal that comprises the integral of the second signal;
- means for generating a fourth signal including a voltage for one of the stator windings;
- a second filter operatively coupled to the means for generating the fourth signal to generate a fifth signal which comprises a filtered version of the fourth signal;
- a zero crossings detector coupled to the integrator unit and to the second filter to detect zero crossings of the third and fifth signals and to generate a sixth and seventh signals with information concerning zero crossings of the third and fifth signals, respectively;
- and
- a controller operatively coupled and configured to control application of stator currents by the inverter based on the information in the sixth and seventh signals.
Dependencies are inferred from the claim text.