Abstract: A variable flux electric machine including a frame, an armature rotatably mounted within the frame, a first field having a plurality of windings that defines at least one wound pole fixedly mounted relative to the frame, a second field having at least one permanent magnet (PM) that defines at least one PM pole fixedly mounted relative to the frame, and a relay electrically coupled to the plurality of windings of the first field.

Abstract: In a travel-driving mechanism for a self-propelled working machine such as a self-propelled lawn mower travels by using power of an electric motor 30, the torque of a driving shaft 50, which is driven by the power of the electric motor 30 through a power transmission unit 40, is transmitted to travel-driving wheels 7 through two-way or bi-directional clutches 55 provided at both ends of the driving shaft 50. Power transmission units 61, 62 are provided between the bi-directional clutch 55 and the driving wheels 7. A travel control unit 70 is provided to input an instruction signal produced by the operation of a travel operation member 66, which is operated by the operator, and to control the electric motor 30.

Abstract: Disclosed is a circuit and method for preventing erroneous opening and closing caused particularly, by use of a DC motor in an automatically/manually foldable portable radio terminal having a main body and a sub-body rotatable with respect to the main body. In the circuit, a motor provides rotating force to automatically raise or lower the sub-body, a motor driver drives the motor according to a motor driving direction control signal, an inverse electromotive force eliminator eliminates inverse electromotive force by opening or shorting both terminals of the motor according to an automatic mode or a manual mode, and a motor power controller controls supplying a driving power voltage to the motor. In the method of operating a folder, it is determined whether an automatic folder operation key has been pressed. Upon receipt of the automatic folder operation key input, a rectifier is turned on to open both terminals of a motor. At the end of the opening of the motor terminals, the motor is driven.

Abstract: A circuit arrangement is disclosed for reducing field voltage peaks in direct current motors which are energized by way of an electronic D.C. regulator, and which have an exciter winding connected with the armature and commutating pole windings by means of diodes. The circuit arrangement includes a choke coil connected in series with the exciter winding. In addition, a resistor is connected in parallel with the exciter winding. This arrangement prevents a rapid rise in the field current or the magnetic field flux of the motor.

Abstract: Apparatus is disclosed for controlling the speed of an electric motor by selectively connecting a field weakening resistor across the field winding of an electric motor. A first means is provided for comparing the field voltage to a fixed reference voltage and for generating a first signal in response to the field voltage falling below a first predetermined value and a second signal in response to the field voltage rising above a second predetermined value. A second means responsive to the first and second signals is provided for selectively connecting a field weakening resistor across the field winding of the motor in response to the field voltage falling below the first predetermined value. The second means responsive also disconnects the field weakening resistor in response to the field voltage rising above the second predetermined value.

Abstract: A switch for speed control of an electric motor driven vehicle employs a combination of resistance switching, field weakening and voltage switching. A mechanical switch assembly has a speed switch and a voltage switch that are interconnected so that the voltage switch provides 36 volts when the speed switch is in neutral and fifth speed position and provides 18 volts when the speed switch is in first through fourth speed positions. The speed switch has an operator controlled rotor arm that successively engages a neutral contact and five driving speed contacts so that varying resistance is inserted in circuit with the motor armature in the first two speed positions and no external resistance is employed in the third and fifth speed positions. The motor field comprises pairs of first and second oppositely disposed series wound coils with the pairs of coils all connected and energized in series in all but the fourth speed position.