Motor control for brushless permanent magnet using only three wires
First Claim
1. A method of controlling a brushless permanent magnet motor having stator windings connected in a star configuration which provides a stator neutral node and in which windings are induced back EMF fundamental and third harmonic components, and a rotor which rotates relative to the stator windings, the motor being driven by an inverter having electrical nodes, including phase nodes to which are coupled a star network of resistors which provides an artificial neutral node separate and apart from, but in correspondence with, the stator neutral node, comprising the steps of:
- extracting a first signal in which the third harmonic component is dominant from across one of the nodes of the inverter and the artificial neutral node without requiring connection to the stator neutral node;
filtering the first signal to generate a second signal which substantially contains only the third harmonic component; and
communicating the second signal to a controller which controls operation of the inverter based in part on information in the second signal.
1 Assignment
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Accused Products
Abstract
A method and system for controlling operation of a brushless permanent magnet motor having stator windings in star configuration in which back EMF fundamental and third harmonic components are induced, a rotor which rotates relative to the stator windings, and an inverter operatively coupled to the motor to drive same, wherein a star configuration of resistors is coupled to nodes of the inverter and third harmonic components of the flux density of the motor are obtained from across an artificial neutral node present in a network coupled to the stator phase nodes and either the stator neutral node or a direct current midpoint reference node positioned between the direct current nodes of an inverter used to drive the motor. The network preferably is a stator network of resistors each of which is coupled between one stator phase node and the artificial neutral node.
87 Citations
20 Claims
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1. A method of controlling a brushless permanent magnet motor having stator windings connected in a star configuration which provides a stator neutral node and in which windings are induced back EMF fundamental and third harmonic components, and a rotor which rotates relative to the stator windings, the motor being driven by an inverter having electrical nodes, including phase nodes to which are coupled a star network of resistors which provides an artificial neutral node separate and apart from, but in correspondence with, the stator neutral node, comprising the steps of:
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extracting a first signal in which the third harmonic component is dominant from across one of the nodes of the inverter and the artificial neutral node without requiring connection to the stator neutral node; filtering the first signal to generate a second signal which substantially contains only the third harmonic component; and communicating the second signal to a controller which controls operation of the inverter based in part on information in the second signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A control system for a brushless permanent magnet motor having stator windings connected in a star configuration which provides a stator neutral node and in which stator windings are induced back EMF fundamental and third harmonic components, and a rotor which rotates relative to the stator windings, the motor being electrically coupled to and driven by an inverter having electrical nodes, including phase nodes to which are coupled a star network of resistors which provides an artificial neutral node separate and apart from, but in correspondence with, the stator neutral node, comprising:
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an interface unit electrically coupled to at least one inverter node and the artificial neutral node and configured to obtain a first signal including only the third harmonic component therefrom without requiring connection to the stator neutral node and to generate a second signal containing substantially only the third harmonic component; and a controller electrically coupled to the inverter and the interface unit and configured to control application of stator current signals by the inverter to the motor based on the second signal. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method of controlling a brushless permanent magnet motor in an appliance having stator windings connected in a star configuration which provides a stator neutral node and in which windings are induced back EMF fundamental and third harmonic components, and a rotor which rotates relative to the stator windings, the motor being driven by an inverter having electrical nodes, including phase nodes to which are coupled a star network of resistors which provides an artificial neutral node separate and apart from, but in correspondence with, the stator neutral node, comprising the steps of:
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extracting a first signal in which the third harmonic component is dominant from across one of the nodes of the inverter and the artificial neutral node without requiring connection to the stator neutral node; filtering the first signal to generate a second signal which substantially contains only the third harmonic component; extracting a third signal from an inverter phase node; filtering the third signal to generate a fourth signal which contains a phase voltage for one phase; and communicating the second and fourth signals to a controller which controls operation of the inverter. - View Dependent Claims (16, 17, 18, 19)
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20. A control system for a brushless permanent magnet motor in an appliance having stator windings connected in a star configuration which provides a stator neutral node and in which stator windings are induced back EMF fundamental and third harmonic components, and a rotor which rotates relative to the stator windings, the motor being electrically coupled to and driven by an inverter having electrical nodes, including phase nodes to which are coupled a star network of resistors which provides an artificial neutral node separate and apart from, but in correspondence with, the stator neutral node, comprising:
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an interface unit electrically coupled to at least one inverter node and the artificial neutral node and configured to obtain a first signal including only the third harmonic component therefrom without requiring connection to the stator neutral node and to generate a second signal containing substantially only the third harmonic component, the interface unit also coupled to an inverter phase node and configured to extract a third signal therefrom and to generate a fourth signal comprising a phase voltage for the respective phase; and a controller electrically coupled to the inverter and the interface unit and configured to receive the second and fourth signals to control application of stator current signals by the inverter to the motor, the controller also configured to measure the speed of the motor based on the second signal.
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Specification