# US 12,191,788 B2 · Controller and drive circuits for electric motors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,191,788 B2 - Document ID: US12191788B2 - Status: Granted - Kind: B2 - Application number: 18/316,800 - Filed: 2023-05-12 - Published: 2023-09-07 - Granted: 2025-01-07 - Earliest claimed: 2021-03-15 - Assignees: Regal Beloit America, Inc. - Applicants: Regal Beloit America, Inc. - Inventors: Ludovic Andre Chretien - Web page: https://patentgrep.com/patent/US12191788B2 ## CPC - H02P 27/047: {V/F converter, wherein the voltage is controlled proportionally with the frequency} - H02P 1/44: by phase-splitting with a capacitor - H02P 23/28: Controlling the motor by varying the switching frequency of switches connected to a DC supply and the motor phases - H02P 27/08: with pulse width modulation - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract An electric motor system is described. The electric motor system includes a drive circuit configured to supply variable frequency current and a contactor configured to supply line frequency current, wherein the drive circuit includes a three-phase inverter and an H-bridge including two phases of the inverter. The electric motor system also includes an electric motor and a controller. The controller is configured to control the inverter to supply variable frequency current to the electric motor over a first duration and determine to control the drive circuit to transition from supplying variable frequency current to supplying line frequency current. The controller is also configured to determine a polarity of a sensed alternating current (AC) voltage, disable at least two switches of the H-bridge, and control the contactor to close, thereby preventing the contactor and the inverter from energizing the electric motor at the same time once the contactor is closed. ## Claims ### Claim 1 An electric motor system comprising: a drive circuit comprising: a contactor; and an inverter; and at least one processor in communication with the drive circuit, wherein the at least one processor is configured to: cause at least two switches of the inverter to be disabled while the drive circuit supplies variable frequency current to an electric motor, wherein the at least two switches are disabled to prevent a line short circuit based at least in part on the at least two switches and the contactor; and cause the contactor to close while the at least two switches are disabled. ### Claim 2 (depends on 1) The electric motor system of claim 1, wherein the at least one processor is further configured to determine a polarity of alternating current (AC) voltage. ### Claim 3 (depends on 2) The electric motor system of claim 2, wherein the at least one processor is further configured to determine to disable the at least two switches based on the polarity of the AC voltage. ### Claim 4 (depends on 1) The electric motor system of claim 1, wherein an H-bridge of the inverter comprises the at least two switches. ### Claim 5 (depends on 1) The electric motor system of claim 1, wherein the at least one processor is further configured to: cause the contactor to begin closing; and control pulse width modulation (PWM) of the electric motor before the contactor is closed. ### Claim 6 (depends on 1) The electric motor system of claim 1, wherein the at least one processor is further configured to: cause the inverter to supply variable frequency current to the electric motor over a first duration; while controlling the inverter to supply variable frequency, determine to control the drive circuit to transition from supplying variable frequency current to supplying line frequency current; and cause the drive circuit to supply line frequency current over a second duration. ### Claim 7 (depends on 1) The electric motor system of claim 1, wherein the at least one processor is further configured to: cause motor speed of the electric motor to be synchronized to a desired speed for transitioning from variable frequency current to line frequency current; and cause a phase of motor voltage to be synchronized to a desired phase for transitioning from variable frequency current to line frequency current. ### Claim 8 (depends on 1) The electric motor system of claim 1, wherein the at least one processor is further configured to determine to transition from supplying variable frequency current to supplying line frequency current. ### Claim 9 (depends on 8) The electric motor system of claim 8, wherein the at least one processor is further configured to determine to transition from supplying variable frequency current to supplying line frequency current based upon at least one input signal received by the at least one processor. ### Claim 10 A non-transitory computer-readable storage medium with instructions stored thereon that, in response to execution by at least one processor, cause the at least one processor to: cause at least two switches of an inverter to be disabled while a drive circuit supplies variable frequency current to an electric motor, wherein the drive circuit comprises the inverter and a contactor, and wherein the at least two switches are disabled to prevent a line short circuit based at least in part on the at least two switches and the contactor; and cause the contactor to close while the at least two switches are disabled. ### Claim 11 (depends on 10) The non-transitory computer-readable storage medium of claim 10, wherein the instructions further cause the at least one processor to determine a polarity of alternating current (AC) voltage. ### Claim 12 (depends on 11) The non-transitory computer-readable storage medium of claim 11, wherein the instructions further cause the at least one processor to determine to disable the at least two switches based on the polarity of the AC voltage, wherein an H-bridge of the inverter comprises the at least two switches. ### Claim 13 (depends on 10) The non-transitory computer-readable storage medium of claim 10, wherein the instructions further cause the at least one processor to: cause the contactor to begin closing; and control pulse width modulation (PWM) of the electric motor before the contactor is closed. ### Claim 14 (depends on 10) The non-transitory computer-readable storage medium of claim 10, wherein the instructions further cause the at least one processor to: cause the inverter to supply variable frequency current to the electric motor over a first duration; while controlling the inverter to supply variable frequency, determine to control the drive circuit to transition from supplying variable frequency current to supplying line frequency current; and cause the drive circuit to supply line frequency current over a second duration. ### Claim 15 (depends on 10) The non-transitory computer-readable storage medium of claim 10, wherein the instructions further cause the at least one processor to: cause motor speed of the electric motor to be synchronized to a desired speed for transitioning from variable frequency current to line frequency current; and cause a phase of motor voltage to be synchronized to a desired phase for transitioning from variable frequency current to line frequency current. ### Claim 16 (depends on 10) The non-transitory computer-readable storage medium of claim 10, wherein the instructions further cause the at least one processor to determine to transition from supplying variable frequency current to supplying line frequency current based upon at least one input signal received by the at least one processor. ### Claim 17 A method of operating a motor implemented by at least one processor in communication with at least one memory, the method comprising: causing at least two switches of an inverter to be disabled while a drive circuit supplies variable frequency current, wherein the drive circuit comprises the inverter and a contactor, and wherein the at least two switches are disabled to prevent a line short circuit based at least in part on the at least two switches and the contactor; and causing the contactor to close while the at least two switches are disabled. ### Claim 18 (depends on 17) The method of claim 17, further comprising determining to disable the at least two switches based on a polarity of alternating current (AC) voltage. ### Claim 19 (depends on 17) The method of claim 17, wherein an H-bridge of the inverter comprises the at least two switches. ### Claim 20 (depends on 17) The method of claim 17, further comprising: causing motor speed of the motor to be synchronized to a desired speed for transitioning from variable frequency current to line frequency current; and causing a phase of motor voltage to be synchronized to a desired phase for transitioning from variable frequency current to line frequency current.