# US 2018/0323613 A1 · Electric motor control device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0323613 A1 - Document ID: US20180323613A1 - Status: Published application - Kind: A1 - Application number: 15/764,559 - Filed: 2016-01-14 - Published: 2018-11-08 - Earliest claimed: 2016-01-14 - Assignees: Mitsubishi Electric Corporation - Applicants: Mitsubishi Electric Corporation - Inventors: Chiaki FUJIMOTO; Kenta TANAKA; Tatsuya MORI; Isao KEZOBO - Web page: https://patentgrep.com/patent/US20180323613A1 ## CPC - H02J 3/1892: the arrangements being an integral part of the loads or of their control circuits - H02P 23/26: Power factor control [PFC] - H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence) - H02P 27/08: with pulse width modulation - H02P 29/024: Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load - H02P 29/0241: {the fault being an overvoltage} - H02P 29/028: the motor continuing operation despite the fault condition, e.g. eliminating, compensating for or remedying the fault - H02P 29/032: Preventing damage to the motor, e.g. setting individual current limits for different drive conditions - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract A control unit of an electric motor control device includes an inverter circuit 6 that supplies power to an electric motor, a current control unit that outputs a voltage command value as a drive command of the inverter circuit, a current detecting unit that detects current flowing to each phase of the electric motor, and a failed phase identifying unit that identifies a location of a failure in the current detecting unit. The failed phase identifying unit determines whether or not a magnitude or a phase of a frequency component of the test voltage command included in a detected current value when the inverter circuit is driven with a test voltage command having a frequency higher than a rotational frequency of the electric motor as a drive command is within a predetermined range, and determines that a failure has occurred in a phase that is not within the predetermined range. ## Claims ### Claim at position 1 -8. (canceled) ### Claim 9 An electric motor control device including a controller that controls a multi-phase winding electric motor, the controller including an inverter circuit that supplies power to the electric motor, a current controller that outputs a voltage command value as a drive command of the inverter circuit, a current detector that detects current flowing to each phase of the electric motor, and a failed phase identifier that identifies a location of a failure in the current detector, wherein the failed phase identifier has a test voltage command generator, which generates a test voltage command having a frequency higher than a rotational frequency of the electric motor, determines whether or not a magnitude or a phase of a frequency component of the test voltage command included in a detected current value when the inverter circuit is driven with the test voltage command as a drive command is within a predetermined range, and determines that a failure has occurred in a phase that is not within the predetermined range. ### Claim 10 (depends on 9) The electric motor control device according to claim 9, wherein the controller includes an abnormality detector that detects that an abnormality has occurred in the electric motor, the inverter circuit, or the current detector, drives the inverter circuit with the voltage command output from the current controller as the drive command when the abnormality detector is not detecting an abnormality, and drives the inverter circuit with a test voltage command generated by the test voltage command generator as the drive command when the abnormality detector detects an abnormality, and the failed phase identifier starts an identification of a failed phase when the abnormality detector detects an abnormality. ### Claim 11 (depends on 9) The electric motor control device according to claim 9, wherein the failed phase identifier computes a sum total of detected current values of each phase, determines whether or not the sum total is smaller than a threshold value, and determines that the current detector has failed when an absolute value of the sum of the detected current values of three phases is smaller than the threshold value. ### Claim 12 (depends on 10) The electric motor control device according to claim 10, wherein the failed phase identifier computes a sum total of detected current values of each phase, determines whether or not the sum total is smaller than a threshold value, and determines that the current detector has failed when an absolute value of the sum of the detected current values of three phases is smaller than the threshold value. ### Claim 13 (depends on 9) The electric motor control device according to claim 9, wherein the failed phase identifier includes induced current determination means that determines whether or not current flowing due to an induced voltage of the electric motor is equal to or less than a threshold value, and determines that a failure of the current detector has occurred when determining that the current flowing due to the induced voltage is equal to or less than the threshold value. ### Claim 14 (depends on 10) The electric motor control device according to claim 10, wherein the failed phase identifier includes induced current determination means that determines whether or not current flowing due to an induced voltage of the electric motor is equal to or less than a threshold value, and determines that a failure of the current detector has occurred when determining that the current flowing due to the induced voltage is equal to or less than the threshold value. ### Claim 15 (depends on 13) The electric motor control device according to claim 13, wherein the induced current determination means determines whether or not the current flowing due to the induced voltage of the electric motor is equal to or less than the threshold value based on a rotational speed of the electric motor. ### Claim 16 (depends on 14) The electric motor control device according to claim 14, wherein the induced current determination means determines whether or not the current flowing due to the induced voltage of the electric motor is equal to or less than the threshold value based on a rotational speed of the electric motor. ### Claim 17 (depends on 9) The electric motor control device according to claim 9, wherein the inverter circuit includes switching elements in upper and lower arms corresponding to each phase of the electric motor, and includes the current detector connected in series with the switching elements of the lower arm in each phase, and the failed phase identifier computes the magnitude or the phase of the frequency component of the test voltage command based on the current of each phase detected when all of the switching elements of the lower arm are in an on-state. ### Claim 18 (depends on 10) The electric motor control device according to claim 10, wherein the inverter circuit includes switching elements in upper and lower arms corresponding to each phase of the electric motor, and includes the current detector connected in series with the switching elements of the lower arm in each phase, and the failed phase identifier computes the magnitude or the phase of the frequency component of the test voltage command based on the current of each phase detected when all of the switching elements of the lower arm are in an on-state. ### Claim 19 (depends on 17) The electric motor control device according to claim 17, wherein the failed phase identifier distinguishes between a failure of the switching elements provided in the upper and lower arms and a failure of the current detector based on the current of each phase detected when all of the switching elements of the lower arm are in an off-state. ### Claim 20 (depends on 18) The electric motor control device according to claim 18, wherein the failed phase identifier distinguishes between a failure of the switching elements provided in the upper and lower arms and a failure of the current detector based on the current of each phase detected when all of the switching elements of the lower arm are in an off-state. ### Claim 21 (depends on 9) The electric motor control device according to claim 9, wherein the inverter circuit includes switching elements in upper and lower arms corresponding to each phase of the electric motor, and includes the current detector connected in series with the switching elements of the lower arm in each phase, and the failed phase identifier distinguishes between a failure of the switching elements provided in the upper and lower arms and a failure of the current detector based on the current of each phase detected when all of the switching elements of the lower arm are in an off-state. ### Claim 22 (depends on 10) The electric motor control device according to claim 10, wherein the inverter circuit includes switching elements in upper and lower arms corresponding to each phase of the electric motor, and includes the current detector connected in series with the switching elements of the lower arm in each phase, and the failed phase identifier distinguishes between a failure of the switching elements provided in the upper and lower arms and a failure of the current detector based on the current of each phase detected when all of the switching elements of the lower arm are in an off-state.