Research On Parallel Control Of Voltage-type Rectifier

Rectifier module parallel technology has become a research hotspot in the field of power electronics.The parallel system has high power output,high redundancy and high reliability,It has been widely used in the field of battery charging technology,the realization of electric vehicle and power grid interaction(V2G),high power uninterruptible power supply and DC microgrid In addition,the power output of the system is increased in parallel,but it also brings the problems of circulation,energy loss and the increase of the number of sensors.The circulation is due to the existence of the circulation circuit and zero sequence voltage difference.In order to solve the circulation problem,the academic circles generally analyze from the point of view of current sharing technology and zero sequence circulation suppression.In this paper,the advantages and disadvantages of each control method are compared in detail.In practical application and the direct parallel connection of multiple modules,higher requirements are put forward for the parallel system.PWM rectifier needs to have greater power output,better realization of two-way flow of energy,the output voltage can be adjusted high power factor and so on.Therefore,the research on voltage source parallel PWM rectifier is carried out in this paper.Firstly,the single phase PWM rectifier parallel technology is analyzed in detail in this paper.The improved control strategy can reduce the operating times of the switching tube and reduce the loss of the parallel system.Secondly,the three-phase voltage source PWM rectifier is analyzed in detail.The advantages and disadvantages of the vector control strategy based on grid voltage orientation and the direct power control strategy based on virtual flux orientation are comparedFinally,the direct virtual power control algorithm based on space vector modulation direct power control is applied to the parallel rectifier system,an improved SVPWM control strategy based on unified voltage regulator is realized.By constructing a virtual grid flux linkage vector as a directional vector,to cancel the AC side voltage sensor and reduce the hardware cost of the parallel system.By optimizing and improving the traditional SVPWM control module to achieve the purpose of suppressing the circulation,thereby reducing the energy loss of the system.The optimized method can achieve the same performance as the traditional method in the circulation control,and can greatly reduce the number of sensors,and increase the robustness of the system.The simulation model is built in MATLAB/SIMIULINK to verify the correctness of the control strategy.Finally,on the basis of theoretical analysis and simulation verification,designing hardware design and software.,trying to build the experimental platform of three-phase voltage source parallel PWM rectifier.