# US 2014/0152212 A1 · Method for smooth motor startup > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152212 A1 - Document ID: US20140152212A1 - Status: Published application - Kind: A1 - Application number: 14/163,462 - Filed: 2012-07-26 - Published: 2014-06-05 - Earliest claimed: 2011-07-27 - Assignees: Carrier Corporation - Inventors: Da Zhang; Thomas Gietzold; Subbarao Varigonda; Salih Baris Ozturk - Web page: https://patentgrep.com/patent/US20140152212A1 ## CPC - H02P 6/21: Open loop start - H02P 1/46: for starting an individual synchronous motor {(H02P27/04 takes precedence)} - H02P 21/18: Estimation of position or speed - H02P 21/26: Rotor flux based control - H02P 21/32: Determining the initial rotor position (H02P21/34 takes precedence) - H02P 21/34: Arrangements for starting - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A method of conducting smooth motor startup is provided and includes operating a motor in an open loop control scheme at startup, operating the motor in a closed loop sensorless control scheme at a time after startup and transitioning between the open loop control scheme and the closed loop control scheme by reducing a difference between an estimated rotor angle of the motor and a commanded ramping angle of the motor. ## Claims ### Claim 1 A method of conducting smooth motor startup, the method comprising: operating a motor in an open loop control scheme at startup; operating the motor in a closed loop sensorless control scheme at a time after startup; and transitioning between the open loop control scheme and the closed loop control scheme by reducing a difference between an estimated rotor angle of the motor and a commanded ramping angle of the motor. ### Claim 2 (depends on 1) The method according to claim 1, further comprising setting an initial rotor position to a known starting position. ### Claim 3 (depends on 1) The method according to claim 1, wherein the operating in the open loop control scheme follows a startup reference curve to a target speed. ### Claim 4 (depends on 1) The method according to claim 1, further comprising calculating the difference between the estimated rotor angle and the commanded ramping angle. ### Claim 5 (depends on 1) The method according to claim 1, wherein the reducing comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the difference. ### Claim 6 (depends on 5) The method according to claim 5, wherein the difference is gradually reduced to zero. ### Claim 7 (depends on 1) The method according to claim 1, wherein the reducing comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference times a constant, where the constant is initialized as 1 and the difference is continually computed as a function of time; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the constant to zero. ### Claim 8 A method of operating a permanent magnet synchronous motor (PMSM) compressor for smooth motor startup, the method comprising: operating the PMSM in an open loop control scheme at startup; operating the PMSM in a closed loop sensorless control scheme at a time after startup; and transitioning between the open loop control scheme and the closed loop control scheme by determining a difference between an estimated rotor angle and a commanded ramping angle and controlling the commanded ramping angle to reduce the difference. ### Claim 9 (depends on 8) The method according to claim 8, further comprising setting an initial rotor position to a known starting position. ### Claim 10 (depends on 8) The method according to claim 8, wherein the operating of the PMSM in the open loop control scheme follows a startup reference curve to a target speed. ### Claim 11 (depends on 8) The method according to claim 8, wherein the determining comprises calculating the difference between the estimated rotor angle and the commanded ramping angle. ### Claim 12 (depends on 8) The method according to claim 8, wherein the controlling of the commanded ramping angle to reduce the difference comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the difference. ### Claim 13 (depends on 12) The method according to claim 12, wherein the difference is gradually reduced to zero. ### Claim 14 (depends on 8) The method according to claim 8, wherein the reducing comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference times a constant, where the constant is initialized as 1 and the difference is continually computed as a function of time; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the constant to zero. ### Claim 15 A method of operating a permanent magnet synchronous motor (PMSM) compressor for smooth motor startup, the method comprising: operating the PMSM in an open loop control scheme at startup with a predefined load condition; operating the PMSM in a closed loop sensorless control scheme at a time after startup; and transitioning between the open loop control scheme and the closed loop control scheme by determining a difference between an estimated rotor angle and a commanded ramping angle and controlling the commanded ramping angle to reduce the difference to zero. ### Claim 16 (depends on 15) The method according to claim 15, further comprising setting an initial rotor position to a known starting position. ### Claim 17 (depends on 15) The method according to claim 15, wherein the operating of the PMSM in the open loop control scheme follows a startup reference curve to a target speed. ### Claim 18 (depends on 15) The method according to claim 15, wherein the determining comprises calculating the difference between the estimated rotor angle and the commanded ramping angle. ### Claim 19 (depends on 15) The method according to claim 15, wherein the controlling of the commanded ramping angle to reduce the difference comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the difference. ### Claim 20 (depends on 15) The method according to claim 15, wherein the reducing comprises: replacing the commanded ramping angle with a sum of the estimated rotor angle and the difference times a constant, where the constant is initialized as 1 and the difference is continually computed as a function of time; connecting an output of a speed regulator as a reference signal to a current regulator; and gradually reducing the constant to zero.