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.