| PWM rectifier as ac to dc power conversion unit with the characteristics of the sinusoidal input current and power factor control is widely used in power transformation system,its performance directly determines the power quality of the front and back,especially,it requires higher stablility in the field of new energy power generation and electric vehicle charging for the input and load randomness wide fluctuations,hence,it is desired to put forward a new designed requirement for the control of PWM rectifier.Based on this,this thesis mainly studies the control strategy based on dq coordinate transformation for the single-phase PWM rectifier,and explores a kind of analog circuits to realize the control to improve the steady state performance of the system,in addition,improves the control based on dq coordinate transformation of single-phase PWM rectifier respectively from the perspective of control mode and control strategy to make it has better performance.The main research work and achievements are summarized as follows:First of all,in view of the control structure usually introduce dq coordinate transformation for the single-phase PWM rectifier,it will bring the the AD sampling quantization error and sampling time delay when digital control be used.This article designed a kind of analog circuit realize the coordinate transformation,it combines the cycle delay unit constituted by all-pass filter with the operational circuit consisted by operational amplifier,based on the circuit,the double-loop control on dq coordinate system of the single-phase PWM rectifier is realized.Furthermore,it analyzes the system model and control structure,the design method of the compensator parameters is given.Finally,the validity of the circuit design and the correctness of the compensator parameter design are verified by simulation and experiment.The proposed analog coordinate transform circuit are universal and applicable for other control strategies of coordinate transformation,which provides a simple and effective analog implementation method for the control strategy based on dq coordinates.Secondly,single-phase PWM digital control system of the rectifier is designed because it has some advantages such as simple structure,easy to change the control parameters and control structure.control.In the control system,the main control chip of DSP processor TMS320F28335 be used and the detailed methods of hardware circuit design with software design be gived.It comes ture single-phase PWM rectifier dq transform the double closed loop digital.Finally,the feasibility of the double closed loop digital PI control based on dq transform for single-phase PWM rectifier is verified by experiments.This part of the research work furtherly improves the double loop control base on dq transform of the single-phase PWM rectifier,in addition,the digital control system design for the single-phase PWM rectifier is a general system,which can easily adjust the control parameters and control structure.Finally,when the load varying in a broad range,the performance of the single-phase PWM rectifier under the double closed loop PI control will be changed greatly and even instable,the Lyapunov control strategy based on dq transform is therefore proposed in this paper.In fact,the Lyapunov stable ility theory is applied to the single-phase PWM rectifier,and the energy function of dq coordinate system is built by the Lyapunov direct method,similarly,the control equations for system convergence are derived,likewise,the Lyapunov control structure based on dq transform of the single-phase PWM rectifier is given to meet the needs of a wide range of system asymptotical stablitity.Finally,the corresponding simulation analysis and experimental prototype is built,which verifies the correctness of the proposed control method.This part of the research can effectively reduce the influence of load disturbance on the performance of the PWM rectifier system. |
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