# US 11,451,176 B2 · Apparatus and method for ascertaining a rotor position, and electric drive system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,451,176 B2 - Document ID: US11451176B2 - Status: Granted - Kind: B2 - Application number: 17/416,637 - Filed: 2019-12-06 - Published: 2022-03-10 - Granted: 2022-09-20 - Earliest claimed: 2018-12-20 - Assignees: Robert Bosch GmbH - Applicants: Robert Bosch GmbH - Inventors: Lei Chen; Sebastian Paulus - Web page: https://patentgrep.com/patent/US11451176B2 ## CPC - H02P 21/18: Estimation of position or speed - H02P 6/18: without separate position detecting elements - H02P 21/22: Current control, e.g. using a current control loop - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract Signal processing for determining a rotor position without the use of encoders. To this end, test signals are applied to the electrical currents in the phase connections of an electric machine, and the total currents in the phase connections of the electric machine are measured. The current responses to the test signals are determined by establishing the difference between the measured phase currents and the setpoint-value settings for the phase currents. On the basis of this difference, any method for calculating the rotor angle position can be performed. ## Claims ### Claim 1 An apparatus (10) for ascertaining a rotor position of an electric machine (30), the apparatus comprising: a power converter (21) configured to provide electrical currents at the terminals of the electric machine (30) using a setpoint variable (S); a current sensor (11) configured to detect measured values of the electrical phase currents at the terminals of the electric machine (30); an input terminal (12) configured to receive a setpoint variable (S) for electrical phase currents of the electric machine (30); a processing device (13) configured to form a difference between the measured values detected by the current sensor and the setpoint variable (S) for the electrical phase currents, and to ascertain the rotor position of the electric machine (30) using the difference formed; and a signal generation device (23), which is configured to generate test signals and to superimpose the generated test signals on the electrical currents provided by the power converter (21) at the phase terminals of the electric machine (30). ### Claim 2 (depends on 1) The apparatus (10) as claimed in claim 1, comprising a filter device (15) configured to perform low-pass filtering of the setpoint variable (S) for the electrical phase currents. ### Claim 3 (depends on 1) The apparatus (10) as claimed in claim 1, wherein the processing device (13) comprises a transformation device (14) configured to transform the measured values of the electrical phase currents at the terminals into a rotor-fixed system. ### Claim 4 (depends on 3) The apparatus (10) as claimed in claim 3, wherein the transformation device (14) is configured to perform a Clarke transformation and a Park transformation of the measured values of the electrical phase currents at the terminals. ### Claim 5 (depends on 1) The apparatus (10) as claimed in claim 1, wherein the processing device (13) is configured to ascertain the rotor position of the electric machine (30) during standstill, slow rotation and/or quick rotation of the rotor. ### Claim 6 An electric drive system, comprising: an electric machine (30); a power converter (21) configured to provide electrical currents at the terminals of the electric machine (30) using a setpoint variable (S); and an apparatus (10) for ascertaining a rotor position of an electric machine (30), the apparatus including a signal generation device (23), which is configured to generate test signals and to superimpose the generated test signals on the electrical currents provided by the power converter (21) at the phase terminals of the electric machine (30); a current sensor (11) configured to detect measured values of the electrical phase currents at the terminals of the electric machine (30); an input terminal (12) configured to receive a setpoint variable (S) for electrical phase currents of the electric machine (30); and a processing device (13) configured to form a difference between the measured values detected by the current sensor and the setpoint variable (S) for the electrical phase currents, and to ascertain the rotor position of the electric machine (30) using the difference formed. ### Claim 7 A method for ascertaining a rotor position of an electric machine (30), the method comprising the following steps: generation and superposition of test signals on electrical currents provided by a power converter (21) at the phase terminals of the electric machine (30); detection (S1) of measured values of the electrical phase currents at the terminals of the electric machine (30); reception (S2) of a setpoint variable for electrical phase currents of the electric machine (30); formation (S3) of a difference between the detected measured values of the electrical currents at the phase terminals of the electric machine (30) and the setpoint variable (S) for the electrical phase currents; and ascertainment (S4) of the rotor position of the electric machine (30) using the difference formed.