US-20260128700-A1 - CONTROLLER AND DRIVE CIRCUIT FOR ELECTRIC MOTORS

US20260128700A1US 20260128700 A1US20260128700 A1US 20260128700A1US-20260128700-A1

Abstract

A controller for an electric motor including a first winding and a second winding is provided. The controller includes a processor configured to supply two-phase variable frequency power to the electric motor using an inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network, actuate the switching network to electrically decouple the run capacitor from the second winding, and, after actuating the switching network, supply three-phase variable frequency power to the electric motor.

Inventors

Ludovic Andre Chretien
Michael R. Koller

Assignees

REGAL BELOIT AMERICA, INC.

Dates

Publication Date: 20260507
Application Date: 20241104

Claims (20)

1 . A controller for an electric motor including a first winding and a second winding, the controller comprising a processor configured to: supply two-phase variable frequency power to the electric motor using an inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network; actuate the switching network to electrically decouple the run capacitor from the second winding; and after actuating the switching network, supply three-phase variable frequency power to the electric motor.
2 . The controller of claim 1 , wherein the processor is further configured to determine to open the switching network in response to two-phase variable frequency power being a target frequency.
3 . The controller of claim 1 , wherein the processor is further configured to supply the three-phase variable frequency power after a preset time window starting from electrically decoupling the run capacitor from the second winding.
4 . The controller of claim 1 , wherein the processor is further configured to determine a time at which to actuate the switching network based on at least one of a first winding voltage, a position of the electric motor, or a run capacitor voltage.
5 . The controller of claim 1 , wherein the processor is further configured to, while actuating the switching network, cause the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the run capacitor based on a detected run capacitor voltage.
6 . The controller of claim 1 , wherein the processor is further configured to, while actuating the switching network, cause the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the second winding based on a voltage of the second winding.
7 . The controller of claim 1 , wherein a first phase of the inverter is electrically coupled to the first winding and to the run capacitor, wherein a second phase of the inverter is electrically coupled to the first winding and to the second winding, and wherein the processor is further configured to supply the two-phase variable frequency power through the first phase and the second phase.
8 . The controller of claim 7 , wherein a third phase of the inverter is electrically coupled to the switching network, and wherein the processor is further configured to: actuate the switching network to electrically couple the third phase to the second winding; and supply the three-phase variable frequency power via the first phase, the second phase, and the third phase.
9 . The controller of claim 1 , wherein the processor is further configured to deactivate overcurrent protection while actuating the switching network.
10 . A method for controlling an electric motor including a first winding and a second winding, the method comprising: supplying two-phase variable frequency power to the electric motor using an inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network; actuating the switching network to electrically decouple the run capacitor from the second winding; and after actuating the switching network, supplying three-phase variable frequency power to the electric motor.
11 . The method of claim 10 , further comprising determining to open the switching network in response to the two-phase variable frequency power being a target frequency.
12 . The method of claim 10 , further comprising supplying the three-phase variable frequency power after a preset time window starting from electrically decoupling the run capacitor from the second winding.
13 . The method of claim 10 , further comprising determining a time at which to actuate the switching network based on at least one of a first winding voltage, a position of the electric motor, or a run capacitor voltage.
14 . The method of claim 10 , further comprising, while actuating the switching network, cause the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the run capacitor based on a detected run capacitor voltage.
15 . The method of claim 10 , further comprising, while actuating the switching network, causing the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the second winding based on a voltage of the second winding.
16 . A drive circuit comprising: an electric motor comprising a first winding and a second winding; an inverter electrically coupled to the electric motor; and a processor configured to: supply two-phase variable frequency power to the electric motor using the inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network; actuate the switching network to electrically decouple the run capacitor from the second winding; and after actuating the switching network, supply three-phase variable frequency power to the electric motor.
17 . The drive circuit of claim 16 , wherein the processor is further configured to, while actuating the switching network, cause the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the run capacitor based on a detected run capacitor voltage.
18 . The drive circuit of claim 16 , wherein the processor is further configured to, while actuating the switching network, cause the inverter to actuate one or more switches according to a switching pattern that prevents a shorting of the second winding based on a voltage of the second winding.
19 . The drive circuit of claim 16 , wherein the inverter comprises: a first phase is electrically coupled to the first winding and to the run capacitor; and a second phase electrically coupled to the first winding and to the second winding, and wherein the processor is further configured to supply the two-phase variable frequency power through the first phase and the second phase.
20 . The drive circuit of claim 19 , wherein the inverter further comprises a third phase electrically coupled to the switching network, and wherein the processor is further configured to: actuate the switching network to electrically couple the third phase to the second winding; and supply the three-phase variable frequency power via the first phase, the second phase, and the third phase.

Description

FIELD The field of the disclosure relates generally to controlling electric motors, and specifically to permanent split-capacitor (PSC) and permanent magnet (PM) electric motors for compressor systems with a mechanism for modulating load on the compressor. BACKGROUND At least some known induction motors are fixed speed motors that operate most efficiently at line frequency power. Such motors exhibit uncontrolled acceleration during startup. Further, at low load conditions, such motors operate less efficiently. Alternatively, some induction motors may be driven with a variable speed motor controller to adapt motor speed to a load level. Such configurations are generally limited by power factor, electromagnetic interference, and electrical losses. A drive circuit for certain motors enables efficient operation at both high and low load conditions. For example, a motor operating a compressor in a heating, ventilation and air conditioning (HVAC) system may experience high load conditions during peak temperatures and low load conditions during milder temperatures. The drive circuit operates the motor using an inverter under low load conditions, and operates the motor using line frequency power under high load conditions. BRIEF DESCRIPTION In one aspect, a controller for an electric motor is provided. The controller includes a processor configured to supply line frequency power to the electric motor through a main switching network, determine to transition from supplying line frequency power to the electric motor to supplying two-phase variable frequency power to the electric motor, synchronize a time base for controlling an output of an inverter with a voltage signal of the line frequency power, open the main switching network to cease supplying line power to the electric motor, and, after a first time period starting from opening the main switching network, supply two-phase variable frequency power to the electric motor using the inverter. In another aspect, a method for controlling an electric motor is provided. The method includes supplying line frequency power to the electric motor through a main switching network, determining to transition from supplying line frequency power to the electric motor to supplying two-phase variable frequency power to the electric motor, synchronizing a time base for controlling an output of an inverter with a voltage signal of the line frequency power, opening the main switching network to cease supplying line power to the electric motor, and, after a first time period starting from opening the main switching network, supply two-phase variable frequency power to the electric motor using the inverter. In another aspect, a drive circuit is provided. The drive circuit includes an electric motor, a main switching network electrically coupled to the electric motor, an inverter electrically coupled to the electric motor, and a processor. The processor is configured to supply line frequency power to the electric motor through the main switching network, determine to transition from supplying line frequency power to the electric motor to supplying two-phase variable frequency power to the electric motor, synchronize a time base for controlling an output of the inverter with a voltage signal of the line frequency power, open the main switching network to cease supplying line power to the electric motor, and after a first time period starting from opening the main switching network, supply two-phase variable frequency power to the electric motor using the inverter. In another aspect, a controller for an electric motor including a first winding and a second winding is provided. The controller includes a processor configured to supply two-phase variable frequency power to the electric motor using an inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network, actuate the switching network to electrically decouple the run capacitor from the second winding, and, after actuating the switching network, supply three-phase variable frequency power to the electric motor. In another aspect, a method for controlling an electric motor including a first winding and a second winding is provided. The method includes supplying two-phase variable frequency power to the electric motor using an inverter with a run capacitor electrically coupled to one phase of the inverter and to the second winding via a switching network, actuating the switching network to electrically decouple the run capacitor from the second winding, and, after actuating the switching network, supplying three-phase variable frequency power to the electric motor. In another aspect, a drive circuit is provided. The drive circuit includes an electric motor including a first winding and a second winding, an inverter electrically coupled to the electric motor, and a processor. The processor is configured to supply two-phase variable frequency power to the electric motor us