Stability improvement of constant voltage transformer for triport UPS system

A novel method for improving the stability of the AVR (automatic voltage regulator) constant voltage transformer for triport UPS (uninterruptible power supply) systems is introduced. An active filter with an operational amplifier as the feedback element for controlling the AVR is shown to reduce the system instability; this device is more compact and economical than the alternative magnetic feedback amplifier. Experimental and simulation results demonstrate the effectiveness of active filter feedback of a higher order for suppressing the instability.<<ETX>>