Abstract: The invention relates to a variable speed drive comprising a direct-current power bus having a positive line (16) and a negative line (17), and an inverter module (14) supplied by the direct-current bus in order to supply a variable voltage to an electric load (M). The drive comprises an energy-recovery device (10) comprising a first direct-current/direct-current converter (20), the output stage of the first converter (20) being connected in series to the positive line of the direct-current bus, a second direct-current/direct-current converter (30), the input stage of the second converter (30) being connected between the positive line and the negative line of the direct-current bus, and an electric energy storage module (Cs) connected in parallel with the input stage of the first converter (20) and with the output stage of the second converter (30).

Abstract: The invention relates to a method and a circuit for regulating the speed of a commutator series-wound motor, especially a universal motor (10), which is supplied with a current from an a.c. voltage source (22) by means of a semiconductor switching element (18) mounted in series with an armature winding (12) and a field winding (14, 16) and controlled by a control unit (28) according to a nominal speed value. The control unit (28) receives, as input signals, signals corresponding to the total voltage drop (Umot) when the motor (10) is supplied with a current, and a substitute signal for the intensity of the motor current (I), corresponding to the voltage drop (Ua, Ufa) on the armature (12) alone or on the armature (12) and on a part (14) of the field winding (14, 16).

Abstract: A three phase motor starting system is provided to reduce the in-rush current to the motor in order to obtain a soft start of the motor. The soft start of the motor equates to reduced impact forces on motor parts and device components connected to the motor during startup of the motor, especially a startup resulting from a reversal of the direction of rotation of the motor. The system uses an impedance load in series with the motor windings of the motor to reduce the in-rush current to the motor windings, which results in a reduced acceleration of the motor shaft and a soft start to the motor. The impedance loads used by the system can be a resistive load, a capacitive load or an inductive load, depending on the type of impedance load that is desired for the soft start of the motor.

Abstract: A device for at least partially driving a vehicle, such as a golf buggy, a trolley, or a parcel carrier, which is adapted to be pushed or pulled by an operator in a forward or a reverse direction. The device comprises a wheel adapted to rotate about an axle of the vehicle, the wheel having an internal chamber; and an electromagnetic assembly located in the chamber operable to provide drive for the vehicle.

Abstract: A control system for reversing the rotation of a field wound motor is used in electric power steering systems. The system responds to control signals from a control means 25 to energize opposite legs of a bridge circuit 14 to direct current through the field winding 10 in the correct direction. At the same time the armature winding is energized. The control system provides a failure detection means 18 for the checking of the various control signals and the operation of the system to determine if there is any system failure to provide for a failsafe operation.

Abstract: A braking control apparatus for an electric motor operated vehicle including contactors for controlling the direction of rotation of a DC electric motor to effect change-over between the forward and backward modes of running of the vehicle, and a chopper circuit whose duty cycle is varied in response to the accelerator position is disclosed to comprise forward/backward change-over detecting means for detecting a change-over from the forward mode of running to the backward mode of running or vice versa, and regenerative braking activating means for effecting regenerative braking whe the forward/backward change-over detecting means detects the occurrence of change-over from the forward to the backward mode of running or vice versa.

Abstract: A control system for a separately excited DC electric traction motor in an electrically powered vehicle incorporates a plurality of current limit functions designed to protect both the motor and control electronics. A time dependent current limit is utilized to permit overcurrent conditions for limited time intervals such that additional power can be obtained for sudden torque requirements without having to design the motor or control electronics to function under continuous high torque conditions. The continuous current limit values based on percent conduction time of a thyristor chopper circuit in the control system is modified in response to overheating of the motor and the main switching thyristor, to overvoltage on the thyristor commutating capacitor and to available voltage for powering the motor.