A Novel Delta-sigma Modulated Single Phase PFC Converter Employing Current Rise Assisting Circuit

Considering the environmental problem or resource exhaustion problem, high efficiency switching inverters and converters are being used. And high efficiency power supplies can also reduce running costs. In recent years, with realizing high speed switching power devices, high frequency modulated switching inverters or converters appear. On the other hands, switching power supplies has a disadvantage of yielding harmonic noise owing to switching operation. Recently, the influence of emission noise from electronic equipments causes problems and the demand for reducing EMI noise is much increasing. Till now, pulse width modulation (PWM) technique is generally used for the switching converter. But by using this method, large noise peaks appear at the multiple numbers of carrier frequency, and this is disadvantageous to keeping noise regulation. When using delta-sigma modulator to inverters and converters, the noise near the fundamental frequency decreases by noise shaping characteristics and large noise peaks do not appear in high frequency band. This paper proposes a delta-sigma modulated power factor correction (PFC) converter. The proposed scheme refines delta-sigma modulator, and to track the sinusoidal reference signal around zero cross point easily, a current rise assisting inductor circuit is employed. And to improve the utilization rate of the power devices, the proposed circuit employs current limiting scheme. From the analytical results, it is proved that the proposed circuit is effective to keep the noise regulation and the proposed circuit can improve the utilization rate of the power devices