Sensorless position detection for electric machine
AssigneeKohler Co.
InventorsIsaac S. Frampton, Adam Larson, Jonathan Bykowski
Life of this patent
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Abstract
An electric machine includes a rotor, a stator, at least one measurement circuit, and a controller. The rotor includes a plurality of salient poles arranged radially around a rotation axis of the electric machine and spaced apart from the rotation axis of the electric machine. The stator includes a plurality of coils configured to selectively align with the plurality of salient poles of the rotor. The at least one measurement circuit is configured to measure at least one current through at least one of the plurality of coils. The measured current includes a current ripple. The controller configured to compute a position of the rotor based on a characteristic of the current ripple.
Claims16
An electric machine comprising:
- a rotor having a plurality of salient poles arranged radially around a rotation axis of the electric machine and spaced apart from the rotation axis of the electric machine;
- a stator having a plurality of coils configured to selectively align with the plurality of salient poles of the rotor;
- a first measurement circuit configured to measure at least one current through a first phase or a first coil of the plurality of coils, wherein the measured current includes a current ripple;
- a second measurement circuit configured to measure at least one current through a second phase or a second coil of the plurality of coils, wherein the measured current includes a current ripple;
- and
- a controller configured to compute a characteristic of the current ripples of the measured currents from the first and second measurement circuits;
- wherein the controller is configured to calculate a first current ripple for the first phase from the first measurement circuit and calculate a second current ripple for the second phase from the second measurement circuit;
- and
- wherein the controller is configured to select a highest value between the first current ripple and the second current ripple to determine a position of the rotor.
A method for operation of an electric machine, the method comprising:
- receiving current values for first and second phases of stator windings;
- calculating first and second current ripples based on the current values for the first and second phases of stator windings;
- estimating a position of the electric machine based on the first and second current ripples, the position determined at least in part by selecting the highest value between the first current ripple and the second current ripple;
- and
- generating an applied signal for the stator in response to the estimated position.
A hybrid device comprising:
- an engine;
- and
- an electric machine comprising:
- a rotor having a plurality of salient poles arranged radially around a rotation axis of the electric machine and spaced apart from the rotation axis of the electric machine;
- a stator having a plurality of coils configured to align with one or more of plurality of salient poles of the rotor at specific rotor positions;
- first and second measurement circuits configured to measure first and second currents through first and second coils of the plurality of coils, wherein the measured first and second currents each includes a current ripple;
- and
- a controller configured to determine alignment of one or more salient poles of the rotor with one or more of the plurality of stator coils and determine a position of the engine;
- wherein the controller is configured to calculate a first current ripple for the first coil from the first measurement circuit and calculate a second current ripple for the second coil from the second measurement circuit;
- and
- wherein the controller identifies a highest reluctance path based on the first current ripple and the second current ripple and selects a rotor position based on the highest reluctance path.
Dependencies are inferred from the claim text.