A novel high-voltage power modulator based on PLC has been developed for PIII. The pulse length can be varied from 10 to 300 μs and the frequency from 10 to 1000 Hz. The PLC system can control the PIII processes and pulse parameters in a flexible manner. In particular, a circuit has been developed to realize the exact control of the frequency and pulsewidth of the pulser. More importantly, the energy-number spectrum of incident ions can be arbitrarily set using the procedure mode combined with numerical calculation or simulation. The power system has robust protection against overcurrent and short circuits.