Abstract: A dual motor drive assembly comprising a housing, a shaft rotatably mounted to the housing, a first gear rotatably connected to the shaft, first and second motors, each having an output driving a respective output gear, the output gears being engaged with the first gear, a torque allocation arrangement for allocating torque demands to each of the first and second motors, a measurement arrangement for measuring first and second temperature relating to the first and second motors respectively, a torque limit allocation arrangement for allocating a maximum torque limit based on the first and second temperature respectively, wherein a maximum total torque is equal to the sum of maximum torque limits of the first and second motors, wherein in a first mode the allocated torque demand to each of the motors is to provide opposing torques to the shaft, and in a second mode to provide torques in the same direction to the shaft, wherein the torque demand allocations change from the first mode to the second mode at a thr

Abstract: A handwheel actuator assembly 600 for a steer by wire steering system of a vehicle is disclosed. The assembly 600 comprises a steering wheel 601 and a feedback torque generator. The steering wheel 601 has at least one hand grip portion rotatable around an axis of rotation of the steering wheel 601 which can be gripped by a driver and a hub 602 that supports the hand grip portion. The feedback torque generator comprises an electric motor which has a stator 609 and a rotor 610. The rotor 610 is directly or indirectly fixed to and rotates with the hub of the steering wheel 601 and the stator 609 is secured to a fixed part of the vehicle body such that it cannot rotate relative to the vehicle body. The motor comprises a brushless permanent magnet Vernier motor.

Abstract: A method of determining an offset between an angular position indicated by a rotary position sensor assembly secured directly or indirectly to the rotor of a multi-phase permanent magnet AC motor and an actual electrical position of the motor rotor, includes the steps of: applying a voltage vector to the motor, which is aligned with a known angular position of the motor; waiting for the motor rotor to move to a location in which the vector when considered in the dq frame of reference is centered on the d-axis; measuring the angular position of the rotor indicated by the position sensor, and determining the offset from the difference between the measured angular position and the known actual position of the vector.

Abstract: A handwheel actuator assembly 600 for a steer by wire steering system of a vehicle is disclosed. The assembly 600 comprises a steering wheel 601 and a feedback torque generator. The steering wheel 601 has at least one hand grip portion rotatable around an axis of rotation of the steering wheel 601 which can be gripped by a driver and a hub 602 that supports the hand grip portion. The feedback torque generator comprises an electric motor which has a stator 609 and a rotor 610. The rotor 610 is directly or indirectly fixed to and rotates with the hub of the steering wheel 601 and the stator 609 is secured to a fixed part of the vehicle body such that it cannot rotate relative to the vehicle body. The motor comprises a brushless permanent magnet Vernier motor.

Abstract: A method of determining an offset between an angular position indicated by a rotary position sensor assembly secured directly or indirectly to the rotor of a multi-phase permanent magnet AC motor and an actual electrical position of the motor rotor, includes the steps of: applying a voltage vector to the motor, which is aligned with a known angular position of the motor; waiting for the motor rotor to move to a location in which the vector when considered in the dq frame of reference is centered on the d-axis; measuring the angular position of the rotor indicated by the position sensor, and determining the offset from the difference between the measured angular position and the known actual position of the vector.

Abstract: An electric power assisted steering system comprises a motor adapted to apply an assistance torque to a portion of a steering shaft in response to a motor drive signal from a drive circuit, in which the motor comprises a synchronous wound field motor of the kind comprising a stator and a rotor, in which the rotor includes at least one pole and at least one coil winding associated with the pole and the stator comprises a number of phase windings, and in which the drive circuit which is configured to provide current in the coils of the stator and rotor during operation of the motor.

Abstract: A rotor structure for an interior permanent magnet electric motor comprising: A laminated rotor core which comprises stack of thin plates, the stack having a first end and a second end, each plate in the stack including at least one window which is aligned with a corresponding window of an adjacent plate so that the window together form an elongate pocket that extends along at least a part of the length of the core starting at a first end of the core, and at least one permanent magnet located in the pocket. At least one plate at the first end of the stack includes an integral retention feature which projects away from a main body of the plate to project above the window in the plate and which engages the first end of the magnet thereby to retain the magnet in the pocket.

Abstract: A rotor structure for an interior permanent magnet electric motor comprising: A laminated rotor core which comprises stack of thin plates, the stack having a first end and a second end, each plate in the stack including at least one window which is aligned with a corresponding window of an adjacent plate so that the window together form an elongate pocket that extends along at least a part of the length of the core starting at a first end of the core, and at least one permanent magnet located in the pocket. At least one plate at the first end of the stack includes an integral retention feature which projects away from a main body of the plate to project above the window in the plate and which engages the first end of the magnet thereby to retain the magnet in the pocket.

Abstract: An electric power assisted steering system comprises a motor adapted to apply an assistance torque to a portion of a steering shaft in response to a motor drive signal from a drive circuit, in which the motor comprises a synchronous wound field motor of the kind comprising a stator and a rotor, in which the rotor includes at least one pole and at least one coil winding associated with the pole and the stator comprises a number of phase windings, and in which the drive circuit which is configured to provide current in the coils of the stator and rotor during operation of the motor.