双PWM变频功率平衡协调控制策略研究

发布时间：2018-06-24 08:30

本文选题：双PWM变换器 + 功率前馈　；参考：《河南科技大学》2017年硕士论文

【摘要】：由于双PWM变换器能够实现单位功率因数输出,能量双向流动,网侧电流正弦化等优点广泛应用于交流变频调速领域。从系统能量流动角度出发,在PWM整流器功率数学模型基础上分析能量失衡对系统的影响。在PWM整流器传统PI控制的基础上,提出一种功率动态补偿的方法。在负载功率突变时能够抑制直流母线电压的波动,提高系统的稳态性能,并且减少网侧电流谐波分量。将PWM整流器非线性储能器件如:电感、电容的能量周期性动态补偿以减少系统非线性误差。根据双PWM变换器能量平衡关系,在传统负载功率前馈的基础上,结合功率动态补偿方法,提出一种负载功率动态前馈的方法,实现双PWM变换器整流侧与逆变侧的协调控制。根据系统传递函数确定补偿周期,将负载功率与补偿功率相结合前馈至整流侧以减少直流侧电容容量,提高系统的响应速度,同时抑制直流母线电压波动。为简化系统控制结构,进一步提高系统的响应速度,在PWM整流器功率数学模型基础上,采用模型预测算法替代整流器功率内环PI控制结构。建价值函数减少功率参考值与实际输出功率所存在的误差,并引入功率补偿算法提高系统的整体性能。将功率补偿值与负载功率值作为模型预测有功功率指令值提高系统的鲁棒性以及降低系统对参数的敏感程度。将逆变器和三相异步电机视为一体,采用按转子磁链定向矢量控制的方法实现异步电机转矩电流与励磁电流的独立控制。根据仿真结果表明,在电机功率突变时,系统采用功率补偿算法能够减少系统非线性误差,有效抑制直流母线电压波动,减少网侧的谐波分量,使网侧电流正弦化。并且采用模型预测算法与功率补偿算法相结合的控制方法能够提高系统的响应速度和稳态性能。系统采用这两种控制方法均能够实现双PWM变换器的协调控制,减少直流侧电容容量,在工程应用中具有一定的实用价值。
[Abstract]:Dual PWM converters are widely used in the field of AC frequency conversion because of their advantages such as unit power factor output, bidirectional energy flow, sinusoidal current on the grid side and so on. Based on the power mathematical model of PWM rectifier, the influence of energy imbalance on the system is analyzed from the point of view of energy flow. Based on the traditional Pi control of PWM rectifier, a dynamic power compensation method is proposed. When the load power changes, the fluctuation of DC bus voltage can be restrained, the steady-state performance of the system can be improved, and the harmonic component of current on the grid side can be reduced. The nonlinear energy storage devices of PWM rectifier such as inductance and capacitance are compensated periodically and dynamically to reduce the nonlinear error of the system. According to the energy balance relation of double PWM converter, based on the traditional load power feedforward and combined with the power dynamic compensation method, a load power dynamic feedforward method is proposed to realize the coordinated control between the rectifier side and the inverter side of the double PWM converter. According to the system transfer function, the compensation period is determined, the load power and compensation power are fed forward to the rectifier side to reduce the capacitance capacity of the DC side, the response speed of the system is improved, and the fluctuation of DC bus voltage is restrained at the same time. In order to simplify the control structure of the system and further improve the response speed of the system, based on the power mathematical model of the PWM rectifier, the model prediction algorithm is used to replace the Pi control structure of the power inner loop of the rectifier. The value function is built to reduce the error between the power reference value and the actual output power, and the power compensation algorithm is introduced to improve the overall performance of the system. The power compensation value and load power value are used as the model to predict the active power instruction value to improve the robustness of the system and reduce the sensitivity of the system to the parameters. The inverter and the three-phase induction motor are regarded as an integral whole, and the torque current and excitation current of the induction motor are controlled independently by using the rotor flux oriented vector control method. The simulation results show that the power compensation algorithm can reduce the nonlinear error of the system, restrain the DC bus voltage fluctuation, reduce the harmonic component of the grid side, and make the current sinusoidal. The control method combining model prediction algorithm and power compensation algorithm can improve the response speed and steady-state performance of the system. The two control methods can realize the coordinated control of the double PWM converter and reduce the capacitance capacity of the DC side. It has certain practical value in the engineering application.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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