Research On SVPWM Control Strategy And Neutral Voltage Balance For VIENNA Rectifier

Multi-level rectifier has many advantages, such as under low voltage stress, low current harmonics and having no possible for bridge-arm short-circuit. So it gradually becomes the research direction in the field of high-power high voltage. So far, the main research focuses three-level topology because of the hardware conditions and the control complexity. In many topologies, Vienna rectifier contains the least amount of power devices, and it is the simplest topological structure. So it has practical significance to reseach and analyse the Vienna rectifier.Firstly, this paper analyses the operation principle of Vienna rectifier and present the operation mode on a different switch state. on the base of which, this paper analyses the operation feature of Vienna rectifier, and deduces the mathematical mode and equivalent circuit based on switching function in three kinds of coordinate system.On the basis of the second, and then the last chapter, in the dq reference frame for the decoupling control of current, based on voltage loop, current double closed-loop control structure diagram of the inner ring.In-depth analyses the SVPWM control algorithm, and implements a three-level SVPWM and the equivalent of two level SVPWM, simplifies the complexity of the space vector synthesis algorithm, to facilitate the realization of the digital control.Aiming at neutral voltage fluctuation in the problems in the Vienna rectifier, based on the analysis of the effects of different amount on the basis of vector function by changing the positive and negative time ratio k, analyzes the modulation ratio is less than 0.875 and greater than 0.875 two cases of neutral voltage control algorithm.Through the MATLAB/Simulink simulation validate the correctness of theoretical analysis.This paper builts a 2 kw power rating, switching frequency is 50 KHZ, the output voltage of 650 v test model, design a digital control system based on TMS320F2812, gives the simplified digital implementation of the program flow diagram of the algorithm.Waveform simulation and experiment indicate that: the Vienna rectifier again based on SVPWM control algorithm of voltage and current double closed-loop control strategy, the advantages of low harmonic content, high power factor, good dynamic performance and steady-state performance, neutral voltage balance control effect is good wait for a characteristic.