Research Of Three Phase Voltage Source PWM Rectifier Control Technology

With the development of power electronics, microelectronics and computer, the power conversion apparatus based on the PWM (Pulse Width Modulation) technique is gaining more and more application. PWM rectifiers have the characteristics of large power factor, small harmonic pollution, bidirectional power flow, small capacity power storage segment and constant direct voltage, so they have more and more application perspective in active filtering, reactive-load compensation, tide control, solar electrical energy generation and motor control systems. This thesis focused on the VSR (Voltage Source Rectifier) research and has completed the following work:1. The thesis has analyzed the system models based on the three-phase static coordinate system and the two-phase synchronous rotating coordinate system from the point of the topology of the main circuit. The thesis has also discussed the two closed-loop control schemes combining the internal current control loop and the external voltage control loop, the principle of the space vector pulse width modulation and their application in the three-phase VSR based on the analysis on the system models. This thesis also put forward a new analysis method for current switching based on the direction of the voltage vector and the current. This method divided the status of the three-phase into 12 sub-statuses, gave out the transition of the inductors on the AC side, the rectification bridge, the capacitor on the direct side and the current on the load corresponding to the individual status and studied the three-phase VSR further.2. The thesis gave out the design method of the internal current loop and external voltage loop based on the system control models. The design of the inductor on the electrical network is a bottleneck of the system design and this thesis presented a new design technique based on the preset power amount and the depression of the current ripples. The thesis also constructed simulation platforms based on MATLAB/Simulink and SaberDesigner and verified the validation of the system models. The platform based on the SaberDesigner can construct the behavior models based on the physical components and simulate the models with realistic cases such as temperature variation, switching dissipation and the conduction/shutoff time. So the platform is especially suitable for the digitized control system and mixed-signal simulation. In order to improve the dynamic response of the system, the thesis also introduced the expert system control and the fuzzy control into the system. The optimized algorithm can improve the performance of the system much.3. The thesis also discussed a new control scheme without the amplitude and phase detection based on the model reconstruction. The control scheme can simplify the control system design without the modification of the main circuit topology, so it has the theoretical and practical value. 4. The unbalanced three-phase voltage system is common in the electrical network and the thesis analyzed the three-phase VSR model, the optimized control scheme, the positive and negative sequence component detection, the synchronous coordinate transform and the orientation method of the unbalanced case in detail. The thesis also gave out a new three-dimension complex space power definition based on the synchronous rotating coordinate and this definition can explain all kinds of the instantaneous power component and is suitable for the VSR control and the power analysis of the unbalanced case. The thesis also improved the method of the instantaneous power component computation and the synchronous coordinate orientation. The thesis has done several simulations with individual control method and given out the experiment waveforms and data for the individual control method. The simulation is the basis for the further research on the case of the unbalanced voltage systems. 5. The thesis has constructed the physical experiment platform and completed the diode bridge rectification, the basic VSR control and the amplitude and phase reconstruc...