Abstract: Research and analysis of the characteristics of an electrolytic capacitor-less Inverter system, which voltage and current both ripple with twice the frequency of input grid voltage. Study and analysis of the corresponding control techniques for electrolytic capacitor-less Inverter system. Moreover, combining with the characteristics of electrolytic capacitor-less Inverter, most important ,flux weakening is very easy to be unstable and out of control. To solve this problem , a novel flux weakening method for electrolytic capacitor-less Inverter system is proposed. The proposed method is validated by Load experiments , test and verify the control stability of the electrolytic capacitor-less Inverter system. Accordingly, the motor efficiency is improved .

Key words: Compressor, Electrolytic capacitor-less, Inverter, Flux weakening