Research On Bidirectional AC/DC Converter Modulation Strategy And Power Decoupling Technique For V2G

The development of new energy vehicles to replace traditional fuel vehicles as an important means to alleviate the two issues, environment pollution and energy shortage, received national attention and support. The battery energy storage unit of electric vehicles can be used as load and energy source to deliver energy to the grid, V2G (Vehicle-to-Grid) technique’s development is based on this, It describes the bidirectional interactive process of energy and information between the battery and the grid. Power electronic devices as the interface unit between the battery and the grid, are circuit carriers to achieve V2G technique. Therefore it’s important and valuable to research vehicle bidirectional converter. Under this background, this paper researches on bidirectional AC/DC converter modulation strategy and power decoupling technique based on V2G.The main content of the paper consists of two parts:the first part analyzes the principle of a novel reduced switching loss PWM modulation strategy, sets up mathematical model firstly. Then for the problem that current distortion appearing at voltage zero crossing caused by traditional double-loop control under this modulation strategy, adopting the duty cycle feed-forward control to improve current waveform. Simulation results demonstrate the effectiveness of the control strategy. Finally, through simulation analysis the application of the modulation strategy in bidirectional AC/DC reactive power compensation operation mode.In the second part, a strategy, adopted a bidirectional Boost/Buck converter to decouple the power of output bus was proposed, reduced the output bus decoupling capacitance value, thus providing convenience for film capacitors to replace electrolytic capacitors, overcomes the restrictions to improve the car converter power density and life expectancy, due to the short life, big volume and other factors of electrolytic capacitor. The basic working status of power decoupling circuit was analyzed detailed, relevant parameters were given consideration, and a new control scheme, introduced a feed-forward output bus voltage fluctuation control on the basis of double closed loop, was proposed, to further suppress the bus voltage ripple and reduce the output bus capacitance. Simulation and experiment results were presented to verify the effectiveness of the circuit and control scheme.