Design of a 1kVA intelligent voltage sag compensator for semiconductor industry

Abstract

Nowadays, in order to achieve high automatic production processing and decrease the human working hours, more and more voltage sensitive equipment are in widespread use in the industry. The power quality problem of voltage sag has become a major apprehension in semiconductor industry. The voltage sensitive equipment in semiconductor processing includes an adjustable speed motor, microcontroller, AC controller relay and PLC etc. This equipment could be easily interrupted by voltage sags in the AC mains. The voltage sag possibly stops the working process and causes damage in the equipment. As a result, the whole manufacturing semiconductor process could be delayed while for waiting repair. Furthermore, voltage sag is an unpredictable event; it causes semiconductor production to be continuously behind in the market needs. Therefore semiconductor industry directly relates to the voltage sag problem. This thesis explains the issue of power quality problem arising from voltage sags, which affects the semiconductor industry. The characteristics of the voltage sag are investigated and the existing solutions to solve the voltage sag problem are evaluated. A new topology of parallel type AC voltage sag compensator is introduced. The compensation method of the AC voltage sag compensator is discussed in detail with program a flow chart and circuit block diagram. The function of this compensator is to tolerate transient open-circuit faults in the AC mains during voltage sag compensation period. A practical 120Vac 50Hz/60Hz 1kVA intelligent voltage sag compensator is constructed for evaluating the compensation method. Experimental results show the compensator can support sensitive equipment under different types of voltage sags.