A motor controller includes: a main motor drive circuit configured to control driving of a multi-phase electric motor; a backup motor drive circuit configured to control driving of the multi-phase electric motor, when an abnormality occurs at the main motor drive circuit; and an abnormality diagnosis unit configured to diagnose the abnormality of the main and backup motor drive circuits. In a normal drive state, only the main motor drive circuit is configured to drive the multi-phase electric motor, and in a backup drive state, when the abnormality diagnosis unit diagnoses that the abnormality occurs at the main motor drive circuit as a diagnoses result, a motor current of a phase output unit where the abnormality occurs is cut off, and the phase output unit that has been cut off is replaced with another phase output unit of a same phase in the backup motor drive circuit.

An electric power steering apparatus that calculates a current command value based on at least a steering torque, performs a PWM-control of a brushless motor by an inverter based on the current command value, performs a current control by detecting a rotational angle of the brushless motor, and performs an assist-control of a steering system. The apparatus includes three rotational angle detecting systems to detect three rotational angles of the brushless motor; and an angle diagnosing section that compares absolute values of differences on respective angles outputted from the three rotational angle detecting systems with a threshold, and performs a process by diagnosing whether the rotational angle detecting systems are normal or abnormal; wherein the assist control is continuously performed by using output angles outputted from systems diagnosed as being normal.

A steering control device capable of suppressing a reduction in reliability even in the case where the redundancy of the power source is increased is provided. A steering ECU includes two control systems in which different external power sources are connected to two drive circuits. The low potential sides of the drive circuits and the low potential sides of the corresponding external power sources are independently connected to each other via power source ground lines for the two control systems. The low potential sides of the drive circuits are connected to each other via an internal ground. Two current detection circuits are provided between the power source ground lines and the internal ground to detect power source ground current values, respectively. The steering ECU includes microcomputers that detect a ground abnormality on the basis of the results of detection performed by the current detection circuits.

A current sensor state determination device determines that an abnormality is caused in a current sensor when a sum of phase currents based on current detection values from each of the current sensors in three phases is greater than a first determination value, and determines that no abnormality is caused in the current sensor when the sum of phase currents is equal to or less than the first determination value. The state determination device determines that the current sensor is normal when it is determined that (i) no abnormality is caused in a preset electric angle range equal to or less than one electric-angle cycle of the rotating electric machine and (ii) a value of an electric current flowing in the rotating electric machine in a rotating coordinates system calculated based on the current detection value is equal to or greater than a second determination value.

A motor drive circuit for use in driving a motor having two or more phases comprising a motor bridge having, for each phase of the motor, a bridge arm comprising an upper switch and a lower switch that in normal operation may be opened and closed to modulate the voltage applied to the respective phases in response to drive signals from a motor control circuit, at least one solid state phase isolation relay that is provided in series in an electrical path connecting a respective phase of the motor to a respective bridge arm, the relay being closed in normal operation so that current can flow in the phase and is held open in a fault mode of operation to prevent the flow of current in the phase. The circuit also includes monitoring means for monitoring the current waveform in the phase to provide, at least in a fault mode of operation, an output indicative of when it is safe to open the SSPIR without causing damage due to the SSPIR due to an avalanche mode, and a control circuit that during normal operation applies a voltage to each device that is sufficient to hold the SSPIR closed and which, in the fault mode of operation, responds to the output of the monitoring means to reduce the voltage applied to each SSPIR to a level that causes the SSPIR to open at the safe time.

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 motor drive device for driving a motor, which has a plurality of winding pairs, includes a plurality of inverter units for the plurality of winding pairs. The inverter units are coupled in parallel to a power source. A plurality of capacitors provided for the plurality of inverter units, and a plurality of power relays are disposed between the power supply and the inverter units. In particular, a power relay is provided for each of the inverter units. A control unit detects a short failure of the power relay, and simultaneously turns ON the power relays that do not have a short failure. In such manner, damage to the power relays as well as damage to other electronic components of the motor driver device due to a large electric current is prevented.

A motor vehicle steering system may include an electric motor disposed in a motor housing. The electric motor may have at least three phases, and for each phase a high side MOSFET and a low side MOSFET may be assigned. The MOSFETs may be part of an inverter that supplies voltages into the electric motor. A first non-insulated contact point of the electric motor and a second non-insulated contact point of the motor housing may be configured such that water that ingresses into the motor housing electrically connects the electric motor with the motor housing via the non-insulated contact points. A pull-up resistor may be disposed in parallel with one of the high side MOSFETs of one of the at least three phases. A measurement unit may detect a phase voltage of the one of the at least three phases as being indicative of water present in the motor housing.

A motor control device includes at least one power converter. The at least one power converter is connected between a DC power supply and a motor. The at least one power converter converts a DC electric power into a multi-phase AC electric power by operating a plurality of switching elements and supplies the multi-phase AC electric power to the motor. The motor control device calculates a command value for operating the at least one power converter to control electrical conduction to the motor. The motor control device determines an overcurrent fault when a value of a current flowing through the at least one power converter or a motor winding of the motor exceeds an overcurrent threshold value. The motor control device estimates or detects a power supply current that is a direct current flowing between the DC power supply and the at least one power converter.

An apparatus for driving a motor of an MDPS may include: first to fourth driving power supply units configured to supply driving power to a driving motor; first to fourth inverters configured to switch the driving power supplied from the first to fourth driving power supply units, and supply the switched driving motor to the driving motor, in order to drive the driving motor; first to fourth driving units configured to drive the first to fourth inverters, respectively; a first control unit configured to operate the driving motor by switching the first and second inverters through the first and second driving units; a second control unit configured to operate the driving motor by switching the third and fourth inverters through the third and fourth driving units.