Adjustable pulse injection in electric machine control

Patent metadata

Field	Value
Publication number	US-10097117-B2
Application number	US-201615380790-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Dec 15, 2016
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

A control system is provided for an electric machine having a rotor and a stator. The control system has a converter circuit in electrical communication with the stator and a controller in electrical communication with the converter circuit. The controller is configured to receive a first signal indicating a torque applied to or output by the rotor and receive a second signal indicating a rotational speed of the rotor. The controller is also configured to determine at least one characteristic of a pulse signal based on at least one of the first or second signal. The controller is also configured to inject the pulse signal into one or more phases of the stator via the converter circuit according to the determined at least one characteristic. The controller is also configured to determine a position of the rotor based on the injected pulse signal.

First claim

What is claimed is:

1. A control system for an electric machine having a rotor and a stator, the control system comprising:
a converter circuit in electrical communication with the stator of the electric machine, the stator including a plurality of phase windings each associated with a separate phase of 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 of the electric machine;
receive 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;
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.

2. The control system of claim 1 , wherein the at least one characteristic includes at least one of a current peak of the pulse signal or an injection timing indicating a start or finish of injecting the pulse signal.

3. The control system of claim 1 , wherein the controller is configured to:
determine a torque value based on the first signal; and
determine the at least one characteristic of the pulse signal according to a predetermined relationship between the at least one characteristic and the torque value.

4. The control system of claim 3 , wherein the predetermined relationship includes a proportional relationship between the at least one characteristic and the torque value.

5. The control system of claim 3 , wherein the controller is configured to:
determine whether the torque value is within a predetermined range defined by a lower torque threshold and an upper torque threshold;
when the torque value is within the predetermined range, determine the at least one characteristic according to the predetermined relationship between the at least one characteristic and the torque value;
when the torque value is greater than the upper torque threshold, clamp the at least one characteristic at a predetermined upper bound value; and
when the torque value is smaller than the lower torque threshold, clamp the at least one characteristic at a predetermined lower bound value.

6. The control system of claim 1 , wherein the controller is configured to:
determine a rotational speed value based on the second signal; and
determine the at least one characteristic of the pulse signal according to a predetermined relationship between the at least one characteristic and the rotational speed value.

7. The control system of claim 6 , wherein the predetermined relationship includes a proportional relationship between the at least one characteristic and the rotational speed value.

8. The control system of claim 6 , wherein the controller is configured to:
determine whether the rotational speed value is within a predetermined range defined by a lower rotational speed threshold and an upper rotational speed threshold;
when the rotational speed value is within the predetermined range, determine the at least one characteristic according to the predetermined relationship between the at least one characteristic and the rotational speed value;
when the rotational speed value is greater than the upper rotational speed threshold, clamp the at least one characteristic at a predetermined upper bound value; and
when the rotational speed value is smaller than the lower rotational speed threshold, clamp the at least one characteristic at a predetermined lower bound value.

9. The control system of claim 1 , wherein the controller is configured to:
determine a first value associated with the at least one characteristic based on the first signal;
determine a second value associated with the at least one characteristic based on the second signal;
when the first value is equal to the second value, determine a value of the at least one characteristic to be equal to either the first or second value; and
when the first value is different from the second value, determine the value of the at least one characteristic to be equal to a larger one of the first and second values.

10. 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 cur

Assignees

• Caterpillar Inc

Inventors

• Khalil Ahmed
• Han Seok-Hee
• Wai Jackson
• Sonth Sangameshwar
• Gerdes Jesse
• Thorne James M

Classifications

• H02P6/185 Primary

  using inductance sensing, e.g. pulse excitation · CPC title

• H02P25/089

  Sensorless control (direct torque control H02P23/30) · CPC title