An actuator assembly comprising an output member rotatable about a center axis relative to a structure, a first actuator having a first stator fixed to the structure and a first rotor rotatable about the center axis relative to the first stator, a second actuator having a second stator coupled to the first rotor such that the second stator rotates about the center axis relative to the first stator with rotation of the first rotor about the center axis and having a second rotor rotationally coupled to the output member, a controller configured in a failure mode to drive one of the first actuator or the second actuator to selectively control the rotation of the output member about the center axis with an operational failure of the other of the first actuator or the second actuator.

An actuator assembly comprising an output member rotatable about a center axis relative to a structure, a first actuator having a first stator fixed to the structure and a first rotor rotatable about the center axis relative to the first stator, a second actuator having a second stator coupled to the first rotor such that the second stator rotates about the center axis relative to the first stator with rotation of the first rotor about the center axis and having a second rotor rotationally coupled to the output member, a controller configured in a failure mode to drive one of the first actuator or the second actuator to selectively control the rotation of the output member about the center axis with an operational failure of the other of the first actuator or the second actuator.

It is aimed to provide a power management system for an electrically driven vehicle that comprises a powertrain of at least two electric motors that can be selectively geared into the powertrain and an electric power source for powering the at least two electric motors. The power management system comprises a mechanical power demand indicator, indicating a level of mechanical power demanded from the powertrain, and an electrical power demand estimator, arranged to estimate an electrical power demand from the electric power source of a respective one of the at least two electrical motors as a function of the demanded mechanical power. The power management system is arranged to activate or deactivate a respective one of said at least two electric motors in response to the mechanical power demand indicator. The power management system is further arranged to deactivate a respective one of the at least two electric motors when the power management system detects that the demanded mechanical power does not exceed a maximum value for the powertrain having a respective one of said at least two electric motors deactivated; and that the estimated electric power demanded by the powertrain having the respective one of said at least two electric motors deactivated, is lower than the powertrain having the respective one of said at least two electric motors activated; or otherwise activate the respective one of the at least two electric motors.

A drive system for driving a and/or being driven by a coupled machine comprises an output for driving the and/or by the coupled machine, a first machine unit with at least one electric machine and a second machine unit with at least one electric machine. The first machine unit has a transmission gear and the drive system has a first switching unit which is set up in such a way that, in a first operating state of the first switching unit, it operatively connects the transmission gear of the first machine unit and the output in a torque-transmitting manner and, in a second operating state of the first switching unit, this operative connection is interrupted. In addition or alternatively, the drive system has a first switching device which is set up in such a way that, in a first operating state of the first switching device, the electrical machine of the first or second machine unit and a power supply and/or energy storage device are electrically connected by it, and, in a second operating state of the first switching device, said connection is disconnected and an active short circuit of said electrical machine is effected.

The variable-speed accelerator includes an electric device, a transmission device, and a power supply portion that supplies electric power of a constant rated frequency supplied from a power supply to the electric device when the electric device is started. The electric device includes a constant-speed electric motor that rotates a constant-speed input shaft of the transmission device, and a variable-speed electric motor that functions as a generator in a generator mode and also functions as an electric motor in an electric motor mode. When starting the electric device, the power supply portion supplies the electric power generated by the variable-speed electric motor in the generator mode to the constant-speed electric motor after supplying starting power to the constant-speed electric motor and the variable-speed electric motor.

A motor control apparatus that controls a first motor and a second motor that are synchronized includes a first motor control unit configured to control a driving voltage of the first motor based on the torque current instruction value, which is output based on a torque current of the first motor for the first motor, and a second motor control unit configured to control a driving voltage of the second motor based on the torque current instruction value, which is output based on a torque current of the second motor for the second motor, wherein the first torque correction unit or the second torque correction unit corrects the torque current instruction value for the first motor or the toque current instruction value for the second motor based on the torque current of the first motor and the torque current of the second motor.

Described herein are appliances such as a vacuum cleaners having an air flow passage and a fan assembly provided in the air flow passage. The fan assembly includes (a) a first motor comprising a first rotor, a first stator, and a first rotatable output shaft drivingly connected to the first rotor; and (b) a second motor comprising a second rotor, a second stator, and a second rotatable output shaft drivingly connected to the second rotor. The first rotatable output shaft is driving connected to the second stator; and a fan blade drivingly connected to the second rotatable output shaft. Also described herein are methods of energizing a fan assembly of a portable appliance.

The present disclosure relates to a power assist control apparatus and a power assist control method. The power assist control apparatus according to the present disclosure comprises: a main motor driven at a first rotation speed; a sub-motor driven at a second rotation speed; and a controller which receives steering information from a steering wheel to calculate a target rotation speed value of an output shaft, and controls the main motor and the sub-motor such that the output shaft is rotated at the target rotation speed.

A vehicle includes first and second electric machines constrained to rotate in unison and configured to power a common axle. A controller is programmed to, in response to activation of the vehicle, select one of the first and second speed sensors as a representative speed sensor, and, in reponse to the electric machines being in speed control, command speeds to the first and second electric machines based on a difference between a target speed of the electric machines and a measured speed of the representative speed sensor.

A method for reducing a cogging torque produced by at least two brushless electric motors used simultaneously includes determining a period of the cogging torque for each of the two brushless electric motors and putting the period for each motor into phase opposition. Each of the brushless electric motors may include a rotor connected to an output shaft and a stator. The rotor may include at least one permanent magnet, and the stator may have at least two receiving volumes for at least three coils generating a magnetic field.