Research And Design Of The Three-Level Four-Quadrant Rectifier With Energy Feedback

Energy is an important resource for human survival and development.In the modern inverter industry,general inverter is one of the two-quadrant inverter that can only work in the electric state.It uses diode bridge rectifier connected to the DC side and the power grid,and energy cannot achieve the two-way flow,so there is no way to the energy of motor feedback system back to the grid.In the application of some motor regenerative energy,such as lift,hoist and etc,they can only increase the resistance braking unit in two quadrant frequency converter and consume the motor feedback energy.In addition,the diode bridge rectifier will produce serious harmonic pollution to the power grid.With the rapid development of frequency conversion technology,in order to solve those energy problems,the design will use three-level four-quadrant rectifier instead of diode rectifier bridge.This paper mainly carries on research and design of three-level four-quadrant rectifier.Author understands the background of the topic and analyzes the basic principle of four-quadrant rectifier after reading a lot of domestic and foreign literature.Firstly,the paper analyzes the topological structure of the three-level four-quadrant rectifier and sets up the mathematical model of three three-level four-quadrant rectifier basing on three-phase static coordinate system abc,two-phase stationary coordinate system αβ and two-phase rotating coordinate system dq,and optimize the model.Secondly,analyze the three-level SVPWM modulation method by using a SVPWM algorithm basing on the reference vector,moreover,analyze the neutral point potential balance control strategy and put forward a new neutral point potential control strategy according to the current flow and the factors of the neutral point potential changes.The paper study mainly the control strategy of three-level four-quadrant rectifier.Firstly,use the direct current control strategy of double loop,namely the voltage and current loop.Then,on this basis,realize the dynamic process of active power and reactive power decoupling control combining with the instantaneous reactive power theory,which is a direct and new power control method,the advantages are simple algorithm,fast dynamic response,and small current harmonics.Finally,verify the correctness and effectiveness of the SVPWM algorithm and the algorithm of the entire three-level four-quadrant rectifier control system through the PLECS system simulation software.Furthermore,on the basis of three-phase asynchronous motor control experimental platform in the laboratory,in the core of the TMS320F28335 DSP controller,build a experimental platform of three-level four-quadrant rectifier control system,design the hardware control circuit of platform,and prove the correctness of the control strategy through the experiments.Achieve two-way flow of energy and the inverter can smoothly make the motor regenerative energy feedback to the grid reaching the effect of reducing energy consumption and saving energy.