一种基于离散时域模型的单相PWM整流器控制参数多目标优化设计方法

A Multi-Objective Controller Parameter Design Optimization Method of Single-Phase PWM Rectifierwith Discrete-Time Domain Model

单相PWM整流器一般采用电压外环比例积分、电流内环比例谐振的双闭环控制方法,在实现交流侧高功率因数的同时稳定直流侧输出电压,因此受到国内外学者的广泛研究。然而,在内外环控制参数设计阶段,传统设计方法一般根据经验选取控制参数,参数选取范围较大,且无法量化评估控制参数的时域控制效果,导致参数优化整定困难。为此,该文提出一种基于离散时域模型的内外环控制参数多目标优化设计方法。首先,采用传统设计方法确定电压外环比例、积分控制参数以及电流内环比例、谐振控制参数的安全设计空间;然后,基于离散时域模型将安全设计空间正映射至控制参数的时域性能空间,实现电流内环控制参数对交流侧功率因数以及电压外环控制参数对直流侧电压超调量的量化评估。在此基础上,通过进一步约束性能目标得到性能优化设计空间,考虑内外环控制参数的耦合效应,对内外环性能优化设计空间进行重新组合,再将其映射至性能空间,得到内外环控制目标帕累托最优前沿下的最优设计空间,从中选取内外环控制参数的优化设计点,在典型工况下实验测得的交流侧功率因数为0.981 26,直流输出电压超调量绝对值为1.37%,证明了所提优化设计方法的正确性。

The double closed-loop control of single-phase PWM rectifier can achieve high power factor and stable output DC voltage,which has been widely studied by scholars.The double closed-loop control strategy of voltage outer loop and current inner loop is generally used in single-phase PWM rectifier.In current inner loop,PR controller is used to control AC current in phase with voltage to achieve power factor correction,while PI controller is usually applied to control stability of DC output voltage in voltage outer loop.However,in the design stage of the innerand outerloop controller parameters,traditional design method generally selects controller parameters by experience,which causes a wide range of parameter selection and cannot quantitatively evaluate the time-domain control effect of the controller parameters,leading to difficulties in parameter optimization and adjustment.Accordingly,this paper proposed a multi-objectiveoptimization design method for controller parameters based on discrete-time domain model.Firstly,traditional design method in frequency domain was used to determine safe design space of voltage outer loop and current inner loop controller parameters by constraint phase margin and bandwidth.Secondly,the PLECS software was applied to simulate discrete time domain model and automatic iterative controller parameters to obtain the time domain waveforms of controlled variables for analyzing the control performance parameters,thus establishing positive mapping relationship between the controller parameters and controller performance.Thirdly,power factor was selected for current inner loop PR controller performance parameter and the overshoot value was set for voltage outer loop PI controller performance parameter according to the control requirements.then,positively mapped the safe design space to the performance space by PLECS software,in which constrain the value of the performance space to get the performance optimized design space.Finally,the coupling effect of inner and outer loop controller parameters was considered by recombing them in the two performance optimized design spaces and positively mapping to the performance space,in which the multi-objective performance space of current inner loop power factor and voltage outer loop overshoot is obtained.Simulation results show that the minimum overshoot absolute value of 1.23%and the maximum power factor of 0.98614 can be obtained by Pareto front optimal design space respectively.However,these two objectives cannot be optimized at the same time,and the pursuit of higher power factor will certainly increase the overshoot.The Pareto Front shows an intuitive quantitative relationship between different optimization objectives and effectively makes the range of controller parameters values precise.An experimental platform was established and typical design points were selected from the multi-objective Pareto Front optimal design space.Experiments with control parameters by conventional design method demonstrated the accuracy of quantitative assessment of control effects based on discrete-time domain models.And optimized design control parameters proved the correctness of the Pareto front optimal design space,in which verified to achieve power factor value of 0.98126 and absolute overshoot value of 1.37%.Finally,power factors at different output powers were measured to verify that the optimized design control parameters showed good adaptability to different load conditions,thus proving the correctness of the optimizationdesign method in this paper.