Abstract: A method for controlling speed of a single phase induction motor using frequency variation, including the steps of generating an operation start signal and a speed command signal according to a user's selection, outputting a digital data for formation of a sinusoidal wave signal of a desired frequency, to converting means at an interval of a predetermined time period set by a timer to thereby generate the sinusoidal wave signal of the frequency desired by the user, generating the sinusoidal wave based on the digital data, comparing the sinusoidal wave with a triangular signal for controlling a speed of a motor, and converting a DC voltage from a power source into an AC voltage of a frequency band desired by the user to thereby operate the motor. An apparatus for controlling the speed of a single phase induction motor is also provided.

Abstract: A control circuit for an induction motor calculates the d-axis current and q-axis current of a rotor in the motor and estimates the variation of the flux and resistance of the rotor on the basis of the d-q axis currents. As a result, a three-phase current for compensating for the resistance of the rotor varied due to the temperature and environment is suitably controlled to obtain high-performance of the motor.

Abstract: The present invention relates to an induction motor, and a method of adjusting slip angular velocity of an induction motor, based on the voltage, current and velocity of the induction motor and compensating the slip angular velocity using vector control of the induction motor by way of a current controllable inverter.

Abstract: The present invention relates to a velocity control method for a synchronous ac servo motor, more particularly, to a velocity control method for an ac servo motor, in which the motor is controlled by an acceleration ,control mode and a feedforward control mode in systems having severe external load torque and inertia, such as robots, computer numerical control machine tools and the like, to thereby attain a rapid response characteristic and a powerful property endurable to the variation of the load torque and inertia.

Abstract: A detecting circuit is provided with at least one transformer, in which a first transformer is connected at its primary winding to an input power source and has two windings at its output portion to control the operation of two transistors respectively mounted in two switching portions in turn, the detecting resistor is coupled to the first transformer to detect a changing amount of current applied to a load, and a second transformer is provided with two input windings having a tap connected to the resistor and two output windings facing to the input windings, thereby outputting the signals isolated from the ground.

Abstract: This invention relates to a motor current phase delay compensating method and apparatus thereof enabling the driven system to efficiently operate by compensating current phase delay of the stator coil winding such that an alternating current servo motor for driving a FA system, a CNC, or a robot for industry generates maximum torque. An output signal of an A/D converter and a rotational direction discriminating signal of an alternating current servo motor are received whereby a phase delay value with respect to the speed is generated. The phase delay value and an output signal from the A/D converter are summed whereby a phase delay compensation amount is computed to compensate the phase delay amount. The phase delay compensation amount and an output from the speed PI controller are respectively received whereby U-phase and V-phase analog current reference instruction values area generated.

Abstract: This invention relates to an inverse electromotive force eliminating device which protects a motor controller of a motor utilizing a MOS-FET by effectively eliminating the inverse electromotive force generated in a process for accelerating and decelerating a mobile device by utilizing an alternating current servo motor operated by applying the power supply of an inverter. A voltage, generated by an inverse electromotive force upon accelerating and decelerating of a motor in a state when the direct current required for circuit operation is supplied by power supply, increases at an input of an inverter. The voltage is detected by an inverse electromotive force detector and thereafter it is applied to an inverse electromotive force eliminator by utilizing a MOS-FET base driver so that the inverse electromotive force of motor is eliminated. Simultaneously, first and second indicators indicate whether the power supply is inputted and whether the inverse electromotive force is generated.