Abstract: A circuit configuration for limiting the cutoff voltage occurring in controlling a servomotor (M) by means of width-modulated DC pulses comprises a power transistor (T2) which, via a capacitor (C) is connected through for a short time when a cutoff voltage appears thus limiting the cutoff voltage. Subsequently the transistor (T2) presents a high impedance. As a result a short-circuiting of the servomotor (M) will be prevented in the phase in which a spring force resets the servomotor into its zero position.

Abstract: An electric vehicle control device is disclosed, which includes an AC motor for driving a vehicle; a main electric power conversion unit for supplying an AC voltage to the AC motor; a battery for supplying a DC voltage to the main electric power conversion unit; an auxiliary electric power conversion unit connected to the battery and adapted to be connected to a load or a power supply; a controller for controlling the main and auxiliary electric power conversion units so as to act selectively as an inverter or a converter; and a switching unit for giving selectively the AC motor the AC voltage from the main and auxiliary electric power conversion units under control of the controller. In the running mode of the electric vehicle, the controller described above makes the main electric power conversion unit act as an inverter and controls the switching unit so that the AC voltage from the main electric power conversion unit is given to the AC motor.

Abstract: Here is disclosed an IC for controlling the spindle motor of a small hard disk drive unit, characteristic in being provided with a voltage detection circuit for a control circuit driving power source, responsive to the voltage at the connecting terminal of the control circuit driving power source for generating a signal to control the operation of the spindle motor; a voltage detection circuit for a motor driving power source, responsive to the voltage at the connecting terminal of the motor driving power source for controlling the operation of the motor; and further provided with a logic circuit for keeping valid the output signal of the voltage detecting circuit for said motor driving power source from the time the voltage at the motor driving power source terminal rises above a prescribed voltage higher than the upper limit of the prescribed voltage range of the control circuit power source until the time it falls below another prescribed voltage lower than the lower limit of said prescribed voltage range.

Abstract: Disclosed is a drive system for a motor, wherein a current proportional to a change of a load of a motor is sensed by a sensing resistor. A voltage produced across the sensing resistor controls an electronic switch in a manner that the output DC voltage of a DC - DC converter is used for a motor drive power source at a normal load and yet a DC power source with a higher voltage than the output DC voltage of the DC - DC converter is used therefor at an increased load.