Abstract: A rotary breaker that interrupts a transmission of a driving force from a motor to a drive mechanism unit is provided between the motor having a permanent magnet incorporated therein and the drive mechanism unit of an electric vehicle. A second controller controls the rotary breaker based on operation states of a power converting unit that has a power converter that drives the motor by converting a direct-current voltage or an alternate-current voltage into an alternate-current voltage with an arbitrary frequency and a first controller that controls the power converter, operation states of the motor and the rotary breaker, and an operation state of the second controller itself.

Abstract: The present invention relates to a method of controlling the speed of rotation of a piezoelectric motor comprising at least one step of determining the variation of the speed of rotation as a function of the frequency of the excitation voltages of the piezoelectric motor for the actual temperature of the piezoelectric material.

Abstract: A motor control device includes a recording module and a controlling module. The recording module has a revolution speed table recording a plurality of predetermined revolution speed values. The controlling module receives a reference revolution speed control signal and measures the reference revolution speed control signal to correspondingly generate a reference measuring value. The recording module records the reference measuring value corresponding to one of the predetermined revolution speed values in the revolution speed table.

Abstract: A closed-loop system 10 is provided for controlling a DC motor. The system includes a DC motor 12, a controller 18 associated with the motor and constructed and arranged to control operation of the motor, a voltage sensor 14 constructed and arranged to measure a voltage supplied to the motor, a speed sensor 16 associated with the motor and constructed and arranged to obtain a measured speed of the motor, and a conditioning circuit 21 constructed and arranged to receive a speed signal and condition the speed signal to provide to the controller, a nominal speed based on the voltage supplied to the motor, or nominal rate of acceleration or deceleration upon a change in the desired speed. The controller 18 is constructed and arranged to compare the measured speed with a certain speed, that is less than the nominal speed, at a voltage corresponding to a measured voltage, and if the measured speed is less than the certain speed, a fault condition is defined by the controller.

Abstract: An electronically commutatable motor is disclosed, whose field windings are controllable via electronic control unit using PWM control signals via semiconductor output stages, a setpoint being selectable for the control unit and the control unit outputting corresponding PWM control signals to the semiconductor output stages.

Abstract: A computer having a hard disk drive includes a battery voltage monitor which establishes a shut down condition of the computer if the supply voltage falls below a chosen level V.sub.L. Upon start up of the hard disk drive motor, current through the motor is limited so that supply voltage of the battery to a computer does not fall below level V.sub.1, which level is greater than the level V.sub.L. Additionally during start up, current in the motor is controlled so that voltage supplied by the battery to the computer does not rise above a threshold level V.sub.2 which is greater than V.sub.1.