Abstract: The present invention provides method and apparatus to control a plurality of DC motors each having an encoder by a sole microcomputer. The actual rotating speed of each DC motor is detected in response to the signal from the encoder. A pulse width of a voltage which is applied to each motor is controlled due to the deviation between the actual speed and a preset speed. The output signals from the encoders regarding a specific DC motor to the other DC motor are sequentially selected by a selection signal, thereby controlling the speed measurements and calculations regarding a plurality of DC motors and the duties of electric powers which are applied to the DC motors.

Abstract: A motor speed control method and system allow the motor to be accelerated to the steady state in the minimum time even under conditions of varying load torque, varying load inertia and varying power voltage. The motor is controlled by a voltage including a component of proportional term which is a function of a difference between a command speed and a detected speed, and a component of integral term which is summed during an acceleration phase. The acceleration of the motor during the starting process is measured and the integral term is modified basing on the result. The integral term may be memorized so that it is used as the integral term when the subsequent starting phase is completed. The integral term may be obtained from the acceleration and deceleration in the starting process.

Abstract: A miniature brushless motor in which driving coils and magnetically responsive elements such as Hall elements are disposed around a permanent magnet rotor. An output appears from the successive Hall elements detecting the rotating position of the permanent magnet rotor so as to control the current supplied to the driving coils. In the brushless motor, the portion of the permanent magnet rotor opposed to the Hall elements is magnetized through an angle which is selected to be smaller than the angle through which the rotor portion opposed to the driving coils is magnetized.