# US 12,119,763 B2 · Harmonic current command with four degrees of freedom for electric motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,119,763 B2 - Document ID: US12119763B2 - Status: Granted - Kind: B2 - Application number: 17/979,215 - Filed: 2022-11-02 - Published: 2024-05-09 - Granted: 2024-10-15 - Earliest claimed: 2022-11-02 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: Vinod Chowdary Peddi; Cheng Gong; Le Chang; Song He - Web page: https://patentgrep.com/patent/US12119763B2 ## CPC - H02P 21/22: Current control, e.g. using a current control loop - H02P 6/10: Arrangements for controlling torque ripple, e.g. providing reduced torque ripple - H02P 29/50: Reduction of harmonics - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A propulsion system for a device includes an electric motor configured to generate torque to propel the device. A controller is in communication with the electric motor and is adapted to select at least one harmonic order for a harmonic current command. The controller is adapted to define a plurality of operating regions, including a first operating region, a second operating region and a third operating region, each associated with a respective objective function for generating the harmonic current command. The controller is adapted to operate the harmonic current command with four degrees of freedom by selectively varying a q-axis current magnitude, a d-axis current magnitude, a q-axis phase and a d-axis phase as a function of the torque and a motor speed. ## Claims ### Claim 1 A propulsion system for a device, comprising: an electric motor configured to generate torque to propel the device, the electric motor having a motor speed; a controller in communication with the electric motor and having a processor and tangible, non-transitory memory on which instructions are recorded, the controller being adapted to select at least one harmonic order for a harmonic current command; wherein the controller is adapted to define a plurality of operating regions, including a first operating region, a second operating region and a third operating region each associated with a respective objective function for generating the harmonic current command; wherein the controller is adapted to operate the harmonic current command with four degrees of freedom by selectively varying a q-axis current magnitude, a d-axis current magnitude, a q-axis phase and a d-axis phase as a function of the torque and the motor speed; and wherein the harmonic current command has a d-axis component represented by [IHx*sin(Hxθe+ϕd)] and a q-axis component represented by [Iq_Hx*cos(Hxθe+ϕq)], with Id_Hx denoting the d-axis current magnitude, Iq_Hx denoting the q-axis current magnitude, ϕq denoting the q-axis phase, ϕd denoting the d-axis phase, Hx denoting the at least one harmonic order and θe denoting a motor position. ### Claim 2 (depends on 1) The propulsion system of claim 1, wherein the controller is adapted to select the respective objective function for the first operating region i such that a harmonic current magnitude is minimized, the first operating region extending over a lower value torque region. ### Claim 3 (depends on 2) The propulsion system of claim 2, wherein the controller is adapted to select the respective objective function for the second operating region i such that a radial force density is minimized, the second operating region extending over an intermediate value torque region. ### Claim 4 (depends on 3) The propulsion system of claim 3, wherein the controller is adapted to select the respective objective function for the third operating region i such that the radial force density is minimized, and the harmonic current magnitude is partially constrained, the third operating region extending over a higher value torque region. ### Claim 5 (depends on 4) The propulsion system of claim 4, wherein the radial force density is based in part on a radial flux density, a tangential flux density and a permeability constant of free space. ### Claim 6 (depends on 4) The propulsion system of claim 4, wherein a harmonic current magnitude is obtained as sqrt(Id_Hx*Id_Hx+Iq_Hx*Iq_Hx), with Id_Hx denoting the d-axis current magnitude and Iq_Hx denoting the q-axis current magnitude. ### Claim 7 (depends on 1) The propulsion system of claim 1, further comprising: a first blended region between the first operating region and the second operating region, the controller being adapted to blend the harmonic current command between the first operating region and the second operating region. ### Claim 8 (depends on 1) The propulsion system of claim 1, wherein the controller is adapted to determine if a modulation index is less than a predefined threshold value prior to operating the harmonic current command, the modulation index being a ratio of a commanded voltage to an available DC link voltage. ### Claim 9 (depends on 1) The propulsion system of claim 1, wherein the at least one harmonic order includes a first harmonic and a second harmonic. ### Claim 10 A method of operating a propulsion system in a device, the propulsion system having an electric motor configured to generate torque, and a controller having a processor and tangible, non-transitory memory, the method comprising: selecting at least one harmonic order for a harmonic current command, the electric motor having a motor speed; defining a plurality of operating regions, including a first operating region, a second operating region and a third operating region each associated with a respective objective function for generating the harmonic current command; operating the harmonic current command with four degrees of freedom by selectively varying a q-axis current magnitude, a d-axis current magnitude, a q-axis phase and a d-axis phase as a function of the torque and the motor speed; selecting the respective objective function for the first operating region such that a harmonic current magnitude is minimized, the first operating region extending over a lower value torque region; and selecting the respective objective function for the second operating region such that a radial force density is minimized, the second operating region extending over an intermediate value torque region. ### Claim 11 (depends on 10) The method of claim 10, further comprising: selecting the respective objective function for the third operating region such that the radial force density is minimized, and the harmonic current magnitude is partially constrained, the third operating region extending over a higher value torque region. ### Claim 12 (depends on 10) The method of claim 10, further comprising: representing a d-axis component of the harmonic current command as [IdHx*sin(Hxθe+ϕd)] and representing a q-axis component of the harmonic current command as [Iq_Hx*cos(Hxθe+ϕq)], with Id_Hx denoting the d-axis current magnitude, Iq_Hx denoting the q-axis current magnitude, ϕq denoting the q-axis phase, ϕd denoting the d-axis phase, Hx denoting the at least one harmonic order and θe denoting a motor position. ### Claim 13 (depends on 10) The method of claim 10, further comprising: obtaining a harmonic current magnitude as sqrt(Id_Hx*Id_Hx+Iq_Hx*Iq_Hx), with Id_Hx denoting the d-axis current magnitude and Iq_Hx denoting the q-axis current magnitude. ### Claim 14 (depends on 10) The method of claim 10, further comprising: obtaining the harmonic current command in a first blended region between the first operating region and the second operating region via linear interpolation. ### Claim 15 (depends on 10) The method of claim 10, further comprising: including a first harmonic and a second harmonic in the at least one harmonic order. ### Claim 16 A propulsion system for a device, comprising: an electric motor configured to generate torque to propel the device, the electric motor having a motor speed; a controller in communication with the electric motor and having a processor and tangible, non-transitory memory on which instructions are recorded, the controller being adapted to select a first harmonic and a second harmonic for a harmonic current command; wherein the controller is adapted to define a plurality of operating regions, including a first operating region, a second operating region and a third operating region each associated with a respective objective function for generating the harmonic current command; and wherein the controller is adapted to operate the harmonic current command with four degrees of freedom by selectively varying a q-axis current magnitude, a d-axis current magnitude, a q-axis phase and a d-axis phase as a function of the torque and the motor speed; and wherein the controller is adapted to: select the respective objective function for the first operating region such that a harmonic current magnitude is minimized; select the respective objective function for the second operating region such that a radial force density is minimized with no constraint on the harmonic current magnitude; and select the respective objective function for the third operating region such that the radial force density is minimized, and the harmonic current magnitude is partially constrained. ### Claim 17 (depends on 16) The propulsion system of claim 16, further comprising: a first blended region between the first operating region and the second operating region, the controller being adapted to blend the harmonic current command between the first operating region and the second operating region.