Adjustable pulse injection in electric machine control

A method of controlling an electric machine having a rotor and a stator, the stator including a plurality of phase windings each associated with a separate phase of the stator, the method comprising:

• measuring a phase current in a phase winding of the stator using a measurement module;
• receiving at a pulse injection module a signal from the measurement module indicative of the phase current in the phase winding of the stator;
• receiving at the pulse injection module rotor position feedback data from a feedback loop;
• receiving at the pulse injection module a first signal from a torque control module indicating a torque applied to or output by the rotor of the electric machine;
• receiving at the pulse injection module a second signal from one of a speed control module or a feedback loop indicating a rotational speed of the rotor of the electric machine;
• determining at least one characteristic of a pulse signal for use in estimating a position of the rotor, the at least one characteristic being based on at least one of the first or second signal;
• generating the pulse signal with the pulse injection module, the pulse signal including a plurality of high frequency pulses having a pulse period lower than a period of the phase current and based at least in part on the measured phase current received from the measurement module and the rotor position feedback data provided by the feedback loop;
• injecting the pulse signal with the pulse injection module into the phase winding of the stator via a converter circuit;
• receiving the pulse signal at an integrator module and integrating the pulse signal to calculate a corresponding total flux value induced in the phase winding of the stator in which the pulse signal is injected;
• receiving the total flux value at an adder from the integrator module and a mutual flux value resulting from a mutual coupling of a set of phases of the stator of the electric machine and subtracting the mutual flux value from the total flux value to determine a decoupled flux value;
• and
• receiving the decoupled flux value at a decoupled flux module and estimating a current position of the rotor based on the decoupled flux.

An electric drive, comprising:

• an electric machine having a rotor and a stator, the stator including a plurality of phase windings each associated with a separate phase of the stator;
• a converter circuit in electrical communication with the stator;
• and
• a controller in electrical communication with the converter circuit, the controller including:
• a measurement module configured to measure a phase current passing through each of the phase windings of the stator;
• a pulse injection module configured to:
• receive a signal from the measurement module indicative of a phase current in a phase winding of the stator;
• receive rotor position feedback data from a feedback loop;
• receive a first signal from a torque control module indicating a torque applied to or output by the rotor;
• receive a second signal from one of a speed control module or a feedback loop indicating a rotational speed of the rotor;
• determine at least one characteristic of a pulse signal for use in estimating a position of the rotor, the at least one characteristic being based on at least one of the first or second signal;
• generate the pulse signal including a plurality of high frequency pulses having a pulse period lower than a period of the phase current and based at least in part on the measured phase current received from the measurement module and the rotor position feedback data provided by the feedback loop;
• and
• inject the pulse signal into the phase winding of the stator via the converter circuit;
• an integrator module configured to receive the pulse signal generated by the pulse injection module and integrate the pulse signal to calculate a corresponding total flux value induced in the phase winding of the stator in which the pulse signal is injected;
• an adder configured to receive the total flux value from the integrator module and a mutual flux value resulting from a mutual coupling of a set of phases of the stator of the electric machine and subtract the mutual flux value from the total flux value to determine a decoupled flux value;
• and
• a decoupled flux module configured to receive the decoupled flux value and estimate a current position of the rotor based on the decoupled flux.