Research On Analysis And Elimination Of Harmonic In Electric Vehicle Charging Station

In recent years, with the car holding number increasing continuously in China, cars’oil consumption has been a big part composition of the total national oil consumption, about35%, which from energy-economy-environment point of view, is a serious threat to the whole country. The electric vehicle (EV) can be powered by electricity instead of gasoline. Due to its advantages such as environmental friendly, clean, energy-saving, especially their zero emissions, the application of electric vehicle is considered to be an inevitable trend in auto industry. However, lots of harmonic pollution will be induced with the popularization of EV and the large range construction of charger stations. To date, study around the harmonic of charger station, particularly the treatment part, is rarely reported. In this thesis, harmonic features of charger station are studied with the combination of theoretic analysis and modeling simulation. In addition, an Active Power Filter (APF) is designed for a charger station, whose detailed effects are also analyzed accordingly.First, the structure of the charger with six pulse rectifier is analyzed, and the feature of harmonic current is studied in detail. Supposing that every charger in the station is independent, then according to the Chebyshev Law of Large Numbers, the expectation of each harmonic current content can be calculated by Monte Carlo Method. With the obtained expectation value, the station’s actual harmonic content can be estimated.Second, with charger station modeled in the SIMULINK platform, various aspects of the charge station, such as the harmonic’s features, the relationship between numbers of chargers and harmonic content, the largest harmonic content and the sudden change of harmonic current, are studied. The simulation of the largest harmonic content could give some guidance value for the construction of stations.Finally, based on the study about harmonic in the charger station, an APF’s structure is designed, which contains the main parameters about the APF. The stability of capacitor’s voltage is implemented by PI control method. Meanwhile, the power exchanging situation between the capacitor and the main power system is also studied. Two kinds of control strategies--hysteresis control and deadbeat control based on the unbiased GM(1,1) model are utilized to produce the desired PWM, and effects between them are compared accordingly.The problem about the harmonic in charger station is studied comprehensively in the aspects of harmonic detection and elimination. The harmonic features of charger station are studied by mathematical deduction and modeling simulation. Then the APF is designed to control the harmonic. The stability of capacitor’s voltage is implemented by PI control method, and the delay issue of APF system is resolved by the deadbeat control.