A reactorless slip recovery system

Slip energy recovery technology for asynchronous motors is becoming increasingly important to achieve efficient utilization of energy in the context of issues facing the protection of the environment. Improvements are, therefore, continually sought in products to exploit the advances made in technologies. The authors present ABB´s new generation of slip recovery drive, which the company is presently introducing, developed from such a point of approach. The system employs a patented solution for the control of the rectifier. The problem of circulating currents, which do not contribute to any torque production, does not exist with this solution. The need for an inductor in the DC link and the resulting active and reactive power losses are thereby eliminated. Further, the system is insensitive to interruptions in the mains supply. By using thyristors with a high current and voltage rating, the continuous connection of the rectifier to the motor has become possible