Provided is a control device for an electric motor which includes multiple energization systems each including an inverter and coils corresponding to different phases, and which generates a steering assist force in an electric power steering system. Control device diagnoses whether any of inverters 1A and 1B fails, and, when either of the inverters is diagnosed as having failed, reduces the output ratio of the failing inverter to 0% while increasing the output ratio of the normally operating inverter to 100% so as to prevent a drop in the total output from all the inverters after the failure-positive diagnosis. If steering operation is performed after the failure-positive diagnosis, control device performs overheat protection processing for gradually lowering the limit value for the total output from all the inverters in accordance with the sensed temperature of the normally operating inverter.

A method of diagnosing an open phase fault condition comprising the steps of: determining the q axis motor current in the motor, the motor speed, the q axis motor current demand, and the demanded phase voltage from the controller and outputting a signal indicative of that an open phase fault condition of motor is present when the following conditions are met: (1) the q axis current demand amplitude is above a threshold; (2) the q axis motor current is below a first predefined fraction of the demanded q axis motor current; (3) the demanded phase voltage is greater than a second predefined fraction of the saturated phase voltage value of the motor circuit; and (4) the motor speed is below a threshold speed.

A drive circuit for driving an electronically commutated motor contains a DC voltage intermediate circuit, and an inverter which is connected to the latter and has a bridge circuit containing a plurality of transistors, to which the motor phases of a motor configuration containing the motor can be connected. For detecting an insulation fault in the motor configuration, a positive or negative transistor of the inverter is switched on, while all other transistors of the inverter are switched off before all transistors of the inverter are switched off. A motor phase voltage of a selected motor phase of the motor phases with respect to a reference potential is then captured, while all transistors of the inverter remain switched off in order to determine whether there is an insulation fault on the motor phase on a basis of a voltage profile of the motor phase voltage.

The disclosure relates to an electric machine and in particular to the monitoring of the electric machine for the presence of a fault, (e.g., in the stator windings). A monitoring unit is provided, wherein the monitoring unit measures the multiphase electrical time signals transmitted from or to the machine and with the aid of a Hilbert filter determines substantially in real time the envelopes and the phase positions of the individual phases of the time signal. The envelopes corresponding to the different phases or the corresponding phase positions are compared with one another by way of forming differences and, in the event that one or more of the differences deviate(s) from a specified expectation value, the presence of a fault is inferred. The approach allows significantly increased operational reliability of the electric machine to be achieved in particular.

A power conversion device of an embodiment includes a rectifier that full-wave rectifies alternating current of a plurality of phases supplied from a power supply side, a capacitor that smoothes an output voltage of the rectifier, a voltage detection unit that detects the smoothed voltage, and an open phase detection unit that detects that an open phase has occurred in the alternating current of the plurality of phases based on a component having a frequency that is twice as high as a fundamental frequency of the alternating current of the plurality of phases included in frequency components of the smoothed voltage.

A motor driver control system is configured for connection to a plurality of motors, the motor control system includes a motor driver command module, and the motor driver command module is configured to: access information related to one or more operating metrics of the plurality of motors; analyze the information to determine whether a maintenance condition exists in any of the plurality of motors; and if a maintenance condition exists in any of the plurality of motors: prevent electrical power from reaching any of the plurality of motors, identify which one or more of the plurality of motors has the maintenance condition, disconnect the one or more identified motors from the motor driver control system, and restore electrical power to all of the plurality of motors other than the identified motors after disconnecting the one or more identified motors.

A short detection apparatus configured to detect a layer short in a motor in which a plurality of sets of multi-phase windings are independently disposed in a stator includes an acquisition unit configured to acquire electricity information corresponding to windings of individual phases in the sets of the multi-phase windings; and a determination unit configured to determine, based on the electricity information which the acquisition unit acquires with respect to windings of a mutually identical phase in the sets of the multi-phase windings, whether a layer short occurs in any one of the windings of the mutually identical phase.

A method for detecting an imbalance in a synchronous motor drive, the method including reading an output voltage signal, and extracting a signature of a parameter imbalance from the output voltage signal. The parameter imbalance is in the synchronous motor drive. Responsive to extracting the signature of the parameter imbalance, the method further includes identifying a certain parameter having the parameter imbalance based on an operating condition of a synchronous motor controlled by the synchronous motor drive, and determining at least one phase of the synchronous motor in which the certain parameter is manifesting the parameter imbalance.

A rotary-machine control device includes: a connection switching device switching a connection state of stator windings of a rotary machine; a current detection unit detecting a rotary machine current flowing in the rotary machine; a voltage application unit applying voltage to the rotary machine; a control unit generating a voltage command provided to the voltage application unit and outputting a switching command to switch the connection state to the connection switching device; and an open-phase determination unit determining presence or absence of disconnection in the rotary machine or presence or absence of disconnection of a power distribution line to the rotary machine. During rotation of the rotary machine, the control unit outputs the switching command and the open-phase determination unit determines presence or absence of disconnection.

A method of controlling a multi-phase electric machine includes implementing a first control method to control the operation of a six-phase machine that is configured as a combination of two three-phase machines. The method also includes determining whether a fault exists in the six-phase machine. In response to determining that the fault exists in the six-phase machine, the method includes implementing a second and different control method to control the operation of the six-phase machine.