Frequency converter energetic performances analysis

The issue of non-conventional energy sources now is correlated with energy efficiency and clean energy. An application researched by the authors is vibration stress relieving, which consist in vibration of stress reliving piece with electromagnetic or electro-dynamic vibrator to determine frequencies of resonance. Technology is energy efficient and involves a single-phase inverter with variable frequencies, which generate a load current with minimal distortion factor in vibrator coil. The studied and experimental solution used by the authors is a classic inverter with LC turn-off circuit, who use sinusoidal modulation as command principle. This solution is compared from energetic point of view with un-modulated inverter and hybrid commutation inverter. For energy efficiency point of view power factor is interested. Active power P and total power S is analytic determined and is showed their dependence on quality factor Q. Paper emphasis dependence between angle of modulation a and power factor cosphi, for different values of resonance frequencies who making stress relieving.