Research On Modulation Technology And Control Strategy Of Three-phase Current Source Rectifier

The PWM rectifier is widely used in various power electronic devices because of its advantages of bidirectional energy flow and low harmonic pollution.Compared with the voltage source rectifier,the current source rectifier has the characteristics of adjustable power factor and wide output range.It has a broader development space in voltage-reducing occasions such as superconducting energy storage and data center power supply.This paper focuses on how to reduce the current harmonics of the rectifier grid side and suppress the DC-side inductor current ripple,etc.from the aspects of operating characteristics,modulation strategies,loss analysis,control methods,etc.Firstly,analyzing the three-phase current-source rectifier topology and working principle.According to Kirchhoff's law,the equations of state in the three-phase stationary coordinate system are established,and through coordinate transformations,mathematical models are established in the two-phase stationary coordinate system and the two-phase rotating coordinate system,respectively,which lays the foundation for the subsequent research on modulation strategies and control methods Theoretical basis.Secondly,the basic principles of sine pulse width modulation technology and space vector pulse width modulation technology are analyzed and compared in terms of sector division,two-three logic conversion,and current vector formation.Aiming at the problem of large inductor current ripple on the DC side,based on the traditional six-sector space vector modulation strategy,a new twelve-sector space vector modulation strategy is proposed.By controlling the current vector without changing the hardware structure Order to reduce the current ripple.Then,in combination with the proposed modulation strategy,the IGBT's switching losses and conduction losses are quantitatively analyzed,and the loss distribution is drawn from the analysis results.Since the rectifier system is susceptible to grid-side filter parameters,an improved indirect current control strategy with phase correction is proposed.By introducing a delay angle in each phase modulation signal,the accuracy of the control system is improved,using MATLAB / SISO tools The controller zero position and proportional gain in each control loop are reasonably configured so that the control parameter design meets the system requirements.In order to provide reactive power compensation for the grid-side LC filter,a double closed-loop control strategy based on current compensator is proposed in the d-q coordinate system,and the control parameters of the voltage outer loop and current inner loop are reasonably configured.Simulations using MATLAB / Simulink verify the effectiveness of the control strategy.Finally,in order to verify the feasibility of the above scheme,build an experimental prototype.The hardware system consists of three parts: main circuit,control circuit and drive circuit.The software system uses MATLAB / Simulink real-time code generation tools,and the program code is compiled and downloaded to the DSP in the CCS development environment for experimental verification.The experimental results prove the correctness of the modulation strategy and control method.