科研之友
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摘要
This paper presents a new method to improve the power factor of a SEPIC converter which is designed to charge the serial batteries bank (BB) of an electrical vehicle (EV). A clamp capacitor connected in series with the source utility which brings a DC voltage clamp at input nodes, thus converter input voltage remains always positive. SEPIC circuit is a step up/down converter and has an inherent aptitude to be used in the charging applications. We employed here the hysteresis technique to make the input current shape sinusoidal and used a PI compensator to modulate its amplitude according to the power demanded by load. Then averaged instant value of the converter input current will be sinusoidal and inphase with the source voltage. Also, this converter can draw the sinusoidal current at any phase shift from the AC source. In other words, the proposed charger is capable of bi-directional power delivery. This feature is important especially in the intelligent charging applications. Also, output batteries voltage must be greater than the utility voltage amplitude (here is 110 root 2V to 360V). Two transistors with anti-parallel diodes are used as switches and converter efficiency achieved here is 93.4% at the rated power and its current THD is 4%. A noise filter placed at the converter input which prevents the high frequency contents from arrival to the utility network, then guarantees the electro-magnetic compatibility defined by FCC-15 standard. Proposed circuit is superior to the conventional rectifier followed by a DC/DC switching converter because of diode bridge elimination and removal of crossover distortion which is inevitable in the conventional power factor correction (PFC) techniques. Finally, using theoretical equations presented here, we select the circuit components correctly and simulate it by the PSim6 (Power Simulator) software. The simulation results confirm and validate the proposed converter operation and its control loop performance.
- 出版日期2016
