A PWM current amplifier for testing protective relay

Digital simulator systems used for protective relay testing require power conditioning amplifiers to interface their D/A outputs to apparatus under test. This paper describes a feasible design approach for the current amplifier utilizing a PWM (pulse width modulated) switching method With the use of a double hysteresis band control scheme and an active compensation technique, it is demonstrated that a highly efficient switching amplifier with a good quality output waveform can be developed This can be a promising replacement for a conventional analog current amplifier used in the applications of relay testing.