Research On Power Factor Correction Technology For Electric Vehicle On-board Charger

Due to its use of power electronic devices, Electric vehicles decrease power quality of utility grid as it causes harmonic pollution during charging or discharging.Hence, certain measures must be taken to handle this issue. According to the current researching status of PFC technology of on-board EV charger, this paper specifies its research orientation and concrete content.Firstly, aimed at improve the deficiency of traditional Boost Power Factor Correction (PFC) rectifier used in on-board EV charger, this paper researches a single-phase single-switch three-level Boost PFC topology and does a solid research into the adopted topology and conducts math analysis and builds a mathematical model based on the working modes of the circuit. Then two kinds of control strategy,i.e classic cascaded PI control algorithm and new sliding mode control algorithm, are proposed. The PI parameters of PI controller are elaborately analyzed and designed as well as the sliding surface and control law of sliding mode controller.Secondly, detailed simulations about proposed EV on-board charger circuit are done in Simulink, simulation results show that single-switch three-level Boost PFC topology has an edge over traditional Boost PFC circuit as it reduces voltage stress on power switches and downsizes the input inductor from 3mH to 0.64mH, which shrinks the circuit size and lower the EMI noise. In the meantime, THD is about 6%and PF is greater than 0.99 under cascaded PI control, whereas under sliding mode control, THD is only 1.8% and PF is greater than 0.995. Both control strategy achieve the purpose of power factor correction for EV on-board charging. On top of this,sliding mode controller has a better dynamic response to load disturbances over PI controller.To verify and validate the simulation results, a scaled model machine is elaborately designed and built. It consists of mainly two parts, i.e hardware circuit and software program. Hardware circuit designs include Boost rectifier circuit, sampling and conditioning circuit, zero voltage comparing circuit and drive circuit. Primary Software designs include several main blocks, such as main program, interrupt program, initializing and self-checking block, signal sampling block, SMC control algorithm block etc . Experiments are conducted on the scaled model machine and experimenting results are consistent with simulation, which proves the validity and effectiveness of this research.