Uninterrupted power supply using slip-power recovery induction generator

This paper describes an uninterrupted power supply (UPS) using a slip-power recovery induction generator with a battery-inverter system. This UPS has the following merits. The induction generator is started and accelerated quickly without load, since the UPS function is realized by a battery-inverter system. Once the generator is accelerated to a substantial speed, connection to the power system is performed without synchronization, since it is an induction machine. It also means that there is no need for fast frequency control. Only small battery capacity, which can supply electricity between the utility interruption and the induction generator connection, is necessary. Fast voltage regulation is accomplished by a chopper circuit connected to the rotor circuit of the induction generator. The principle of the UPS operation and experimental results are also shown