Development of high-speed AC elevator control with thyristors

The high-speed AC elevators with a speed of 105 mpm (350 fpm) were developed by applying thyristors to their control. The acceleration of the elevators is controlled by two-phase primary voltage control of AC motor, while their deceleration is regulated by DC braking through thyristor convertor. The new technology to enable continuous torque control from motoring to braking has been developed by the Push-Pull characteristics of the control for the higher and lower speed motors. Thus, complex DC motor and motor-generator were replaced by simple AC motor and economical control system was realized.