# US 12,216,165 B2 · Method for categorizing performance of an electric traction machine being a permanent magnetic synchronous motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,216,165 B2 - Document ID: US12216165B2 - Status: Granted - Kind: B2 - Application number: 17/643,548 - Filed: 2021-12-09 - Published: 2022-06-23 - Granted: 2025-02-04 - Earliest claimed: 2020-12-18 - Assignees: Volvo Truck Corporation - Applicants: Volvo Truck Corporation - Inventors: Sebastian Hall - Web page: https://patentgrep.com/patent/US12216165B2 ## CPC - G01R 31/34: Testing dynamo-electric machines - H02P 23/0031: {implementing a off line learning phase to determine and store useful data for on-line control} - H02P 21/141: {Flux estimation} - H02P 21/20: Estimation of torque - H02P 29/662: {the rotor having permanent magnets (H02P29/67 takes precedence)} - H02P 2207/05: Synchronous machines, e.g. with permanent magnets or DC excitation - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A method for categorizing performance of a PMSM coupled to a drive shaft, and powered by a battery via an inverter. The method comprising: decoupling the PMSM from drive shaft; performing a first retardation test to measure the flux linkage of the permanent magnets, PM flux, in the PMSM; performing a second retardation test in which the inverter is disconnected, to measure the no-load power losses of the PMSM; correlating the PM flux with the no-load power losses in a health parameter of the PMSM, and comparing the health parameter with reference data of known health parameters of a population of PMSMs; categorizing the performance of the PMSM based on the compared health parameter. ## Claims ### Claim 1 A method for categorizing performance of an electric traction machine being a permanent magnetic synchronous motor, PMSM, the PMSM being coupled to a drive shaft, and powered by a battery via an inverter, the method comprising: decoupling the PMSM from drive shaft; performing a first retardation test to measure the flux linkage of the permanent magnets, PM flux, in the PMSM; performing a second retardation test in which the inverter is disconnected, to measure the no-load power losses of the PMSM; correlating the PM flux with the no-load power losses in a health parameter of the PMSM, and comparing the health parameter with reference data of known health parameters of a population of PMSMs; categorizing the performance of the PMSM based on the compared health parameter. ### Claim 2 (depends on 1) The method according to claim 1, comprising: prior to the first retardation test, determining a steady state temperature for the permanent magnets in the PMSM. ### Claim 3 (depends on 2) The method according to claim 2, comprising: measuring the temperature inside of the PMSM; comparing the measured temperatures inside and outside of the PMSM by a compared temperature parameter, determine a steady state temperature of the PMSM and the permanent magnets in the PMSM in response of determining that the compared temperature parameter is below a threshold temperature difference. ### Claim 4 (depends on 1) The method according to claim 1, wherein the PMSM is operated by a current controller, and wherein the first retardation test and/or the second retardation test is performed by accelerating the PMSM to a base speed whereupon a current reference of the current controller is set to zero. ### Claim 5 (depends on 4) The method according to claim 4, wherein the PM flux is determined by a ratio of a voltage reference of the current controller and the electrical angular velocity. ### Claim 6 (depends on 1) The method according to claim 1, wherein the no-load power losses are determined by multiplying the loss torque of the PMSM with the mechanical angular velocity. ### Claim 7 (depends on 6) The method according to claim 6, wherein the loss torque is estimated by multiplying the magnitude of acceleration and the moment of inertia of the rotating shaft of the PMSM. ### Claim 8 (depends on 6) The method according to claim 6, wherein the magnitude of acceleration is dependent on the PM flux, and the correlation of the PM flux with the no-load power losses in the health parameter of the PMSM includes the dependence of the PM flux and the no-load power losses. ### Claim 9 (depends on 1) The method according to claim 1, wherein the health parameter is multi-values parameter and the known health parameters of the reference data are corresponding multi-values parameters. ### Claim 10 (depends on 1) The method according to claim 1, comprising: determining whether or not the compared health parameter achieves a pre-set criteria, and categorizing the performance of the PMSM if the health parameter achieves the pre-set criteria, wherein the categorization is related to a reduced performance of the PMSM. ### Claim 11 (depends on 1) The method according to claim 1, wherein the PMSM is installed in a vehicle and the method is performed off-line, when the vehicle is at a standstill. ### Claim 12 The method, comprising: performing a stand still characterisation of the PMSM to estimate linked magnetic flux as a function of current; adding the PM flux to the estimated linked magnetic flux to provide a flux characteristic of the PMSM, the flux characteristics being included in the categorization of the performance of the PMSM; adapting the control parameters of the PMSM based on the flux characteristic. ### Claim 13 (depends on 12) The method according to claim 12, wherein the categorization of the performance of the PMSM is used for adapting the control parameters the PMSM. ### Claim 14 (depends on 1) A non-transitory computer readable medium storing a computer program comprising program code for performing the method of claim 1, when the program code is run on a computer. ### Claim 15 A controlling apparatus for controlling the operation of an electric traction machine being a permanent magnetic synchronous motor, PMSM, the PMSM being coupled to a drive shaft, and powered by a battery via an inverter, the controlling apparatus being configured to: decouple the PMSM from drive shaft; perform a first retardation test to measure the flux linkage of the permanent magnets, PM flux, in the PMSM; perform a second retardation test in which the inverter is disconnected, to measure the no-load power losses of the PMSM correlate the PM flux with the no-load power losses in a health parameter of the PMSM, and comparing the health parameter with reference data of known health parameters of a population of PMSMs; categorize the performance of the PMSM based on the compared health parameter. ### Claim 16 (depends on 15) An arrangement comprising: an electric traction machine being a permanent magnetic synchronous motor, PMSM, the PMSM being connectable to a drive shaft of a vehicle, and configured to be powered by a battery via an inverter, and a controlling apparatus according to claim 15. ### Claim 17 (depends on 16) A vehicle comprising an arrangement according to claim 16. ### Claim 18 (depends on 3) The method according to claim 3, wherein measuring the temperature includes measuring the temperature in the stator windings of the PMSM, and the temperature outside of the PMSM and in the drive shaft or gearbox.