# US 10,309,807 B2 · Resolver calibration for permanent magnet synchronous motor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,807 B2 - Document ID: US10309807B2 - Status: Granted - Kind: B2 - Application number: 14/496,079 - Filed: 2014-09-25 - Published: 2015-04-09 - Granted: 2019-06-04 - Earliest claimed: 2013-10-08 - Assignees: Infineon Technologies AG - Applicants: Infineon Technologies AG - Inventors: Wei Zhe Qian - Web page: https://patentgrep.com/patent/US10309807B2 ## CPC - G01D 18/00: Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00 - G01D 5/2046: {by a movable ferromagnetic element, e.g. a core} - H02P 6/183: {using an injected high frequency signal} - H02P 21/18: Estimation of position or speed - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract The present invention relates to resolver calibration for permanent magnet synchronous motor. According to embodiments of the present invention, the high frequency rotating voltage vector is generated and injected into a resolver associated with a permanent magnet synchronous motor (PMSM). Due to the saliency effect, when a reference point is detected in a phase current, the rotor position of the PMSM is known. At this point, by acquiring the resolver position, the resolver offset may be accurately determined for calibration. According to embodiments of the present invention, the resolver offset may be accurately determined and calibrated without increasing device dimension and cost. Respective methods, apparatuses, systems, and computer products are disclosed. ## Claims ### Claim 1 A method for calibrating a resolver associated with a permanent magnet synchronous motor, the method comprising: generating a high frequency rotating voltage vector; enhancing a resolution of the high frequency rotating voltage vector while it is subjected to pulse width modulation, wherein the enhancing includes increasing a switch frequency of a switch device for the pulse width modulation or increasing an effective modulation frequency of a carrier for the pulse width modulation, the increasing the effective modulation frequency including shifting pulse width modulation conductive time periods within adjacent carrier cycles together; and injecting the high frequency rotating voltage vector into the permanent magnet synchronous motor operating at a low speed to cause the permanent magnet synchronous motor to generate a phase current, wherein the phase current is for calibrating the resolver. ### Claim 2 (depends on 1) The method according to claim 1, wherein the permanent magnet synchronous motor is driven by a reference voltage vector, the method further comprising: merging the high frequency rotating voltage vector and the reference voltage vector during pulse width modulation for the high frequency rotating voltage vector and the reference voltage vector. ### Claim 3 (depends on 2) The method according to claim 2, wherein the high frequency rotating voltage vector has fixed amplitude and rotating frequency, wherein merging the high frequency rotating voltage vector and the reference voltage vector comprises: accessing a lookup table during the merging to determine a duty cycle of the high frequency rotating voltage vector, the lookup table storing pre-calculated duty cycles of the high frequency rotating voltage vector at a plurality of angles. ### Claim 4 (depends on 1) A non-transient computer-readable medium having a computer program tangibly stored thereon for calibration of a resolver associated with a permanent magnet synchronous motor, the computer program comprising machine executable instructions which, when executed, cause the machine to perform the method according to claim 1. ### Claim 5 A method for calibrating a resolver associated with a permanent magnet synchronous motor, the method comprising: responsive to a high frequency rotating voltage vector being injected into the permanent magnet synchronous motor operating at a low speed, detecting a reference point associated with a phase current generated by the permanent magnet synchronous motor, wherein a resolution of the high frequency rotating voltage vector is enhanced while it is subjected to pulse width modulation, wherein the enhancing includes increasing a switch frequency of a switch device for the pulse width modulation or increasing an effective modulation frequency of a carrier for the pulse width modulation, the increasing the effective modulation frequency including shifting pulse width modulation conductive time periods within adjacent carrier cycles together; acquiring a position of the resolver when the reference point is detected; and determining an offset between the acquired position of the resolver and a rotor position of the permanent magnet synchronous motor corresponding to the reference point for calibrating the resolver. ### Claim 6 (depends on 5) The method according to claim 5, wherein detecting the reference point associated with the phase current generated by the permanent magnet synchronous motor comprises: performing high-pass filtering on the phase current; extracting a low frequency component of the high-pass filtered phase current; and detecting the reference point based on the low frequency component of the phase current. ### Claim 7 (depends on 5) The method according to claim 5, further comprising at least one of: performing offset calibration on the phase current; and performing delay compensation on the phase current. ### Claim 8 (depends on 5) The method according to claim 5, further comprising: prior to injecting the high frequency rotating voltage vector, estimating a range of the offset by performing rotor positioning for the permanent magnet synchronous motor. ### Claim 9 (depends on 5) The method according to claim 5, further comprising: generating the high frequency rotating voltage vector; and injecting the high frequency rotating voltage vector into the permanent magnet synchronous motor operating at a low speed to cause the permanent magnet synchronous motor to generate the phase current. ### Claim 10 (depends on 5) The method according to claim 5, wherein the reference point is a zero-crossing point in a waveform of the phase current. ### Claim 11 (depends on 5) A non-transient computer-readable medium having a computer program tangibly stored thereon for calibrating a resolver associated with a permanent magnet synchronous motor, the computer program comprising machine executable instructions which, when executed, cause the machine to perform the method according to claim 5. ### Claim 12 An apparatus for calibrating a resolver associated with a permanent magnet synchronous motor, the apparatus comprising: a voltage generator configured to generate a high frequency rotating voltage vector; a resolution enhancer configured to enhance a resolution of the high frequency rotating voltage vector while it is subjected to pulse width modulation, wherein the resolution enhancing includes increasing a switch frequency of a switch device for the pulse width modulation or increasing an effective modulation frequency of a carrier for the pulse width modulation, the increasing the effective modulation frequency including shifting pulse width modulation conductive time periods within adjacent carrier cycles together; and a voltage injector configured to inject the high frequency rotating voltage vector into the permanent magnet synchronous motor operating at a low speed to cause the permanent magnet synchronous motor to generate a phase current, wherein the phase current is for calibrating the resolver. ### Claim 13 (depends on 12) The apparatus according to claim 12, wherein the permanent magnet synchronous motor is driven by a reference voltage vector, the apparatus further comprising: a voltage merger configured to merge the high frequency rotating voltage vector and the reference voltage vector during pulse width modulation for the high frequency rotating voltage vector and the reference voltage vector. ### Claim 14 (depends on 13) The apparatus according to claim 13, wherein the high frequency rotating voltage vector has fixed amplitude and rotating frequency, and wherein the voltage merger is configured to access a lookup table during the merging to determine a duty cycle of the high frequency rotating voltage vector, the lookup table storing pre-calculated duty cycles of the high frequency rotating voltage vector at a plurality of angles. ### Claim 15 An apparatus for calibrating a resolver associated with a permanent magnet synchronous motor, comprising: a current detector configured to detect, responsive to a high frequency rotating voltage vector being injected into the permanent magnet synchronous motor operating at a low speed, a reference point associated with a phase current generated by the permanent magnet synchronous motor; a resolution enhancer configured to enhance a resolution of the high frequency rotating voltage vector while it is subjected to pulse width modulation, wherein the resolution enhancing includes increasing a switch frequency of a switch device for the pulse width modulation or increasing an effective modulation frequency of a carrier for the pulse width modulation, the increasing the effective modulation frequency including shifting pulse width modulation conductive time periods within adjacent carrier cycles together; a position acquirer configured to acquire a position of the resolver when the reference point is detected; and an offset determiner configured to determine an offset between the acquired position of the resolver and a rotor position of the permanent magnet synchronous motor corresponding to the reference point for calibrating the resolver. ### Claim 16 (depends on 15) The apparatus according to claim 15, further comprising: a filter configured to perform high-pass filtering on the phase current; and a component extracter configured to extract a low frequency component of the high-pass filtered phase current, wherein the current detector is configured to detect the reference point based on the low frequency component of the phase current. ### Claim 17 (depends on 15) The apparatus according to claim 15, further comprising at least one of: a current offset calibrator configured to perform offset calibration on the phase current; and a current delay compensator configured to perform delay compensation on the phase current. ### Claim 18 (depends on 15) The apparatus according to claim 15, further comprising: a rotor positioner configured to estimate, prior to injecting the high frequency rotating voltage vector, a range of the offset by performing rotor positioning for the permanent magnet synchronous motor. ### Claim 19 (depends on 15) The apparatus according to claim 15, wherein the reference point is a zero-crossing point in a waveform of the phase current. ### Claim 20 A system for calibrating a resolver associated with a permanent magnet synchronous motor, the system comprising: a voltage generator configured to generate a high frequency rotating voltage vector; a resolution enhancer configured to enhance a resolution of the high frequency rotating voltage vector while it is subjected to pulse width modulation, wherein the resolution enhancing includes increasing a switch frequency of a switch device for the pulse width modulation or increasing an effective modulation frequency of a carrier for the pulse width modulation, the increasing the effective modulation frequency including shifting pulse width modulation conductive time periods within adjacent carrier cycles together; a voltage injector configured to inject the high frequency rotating voltage vector into the permanent magnet synchronous motor operating at a low speed to cause the permanent magnet synchronous motor to generate a phase current, wherein the phase current is for calibrating the resolver; a current detector configured to detect, responsive to the high frequency rotating voltage vector being injected into the permanent magnet synchronous motor operating at a low speed, a reference point associated with the phase current generated by the permanent magnet synchronous motor; a position acquirer configured to acquire a position of the resolver when the reference point is detected; and an offset determiner configured to determine an offset between the acquired position of the resolver and a rotor position of the permanent magnet synchronous motor corresponding to the reference point for calibrating the resolver.