基于LCL滤波的PWM整流器控制策略研究

发布时间：2018-07-08 11:14

本文选题：LCL滤波器 + PWM整流器　；参考：《河南科技大学》2014年硕士论文

【摘要】：三相电压型PWM整流器具有电网侧输入电流正弦化，，能够达到单位功率因数控制，直流侧电压稳定可调等优点，在电气传动、新能源发电和高压直流输电等领域得到了广泛的应用。但是三相PWM整流器会产生高次谐波，其会对一些敏感的负载设备产生严重影响，也会产生能量损耗。若增大整流器前端电感值，可以减少谐波，但是会影响系统的动态性能，并且使成本和体积增加。LCL滤波器可以由较小的电感值来达到较好的滤波效果，可以有效地抑制进网电流的高次谐波，同时电感还可以起到抑制冲击电流的作用，不但使系统具有很好的动态性能，而且可以降低成本和减小体积,因此深入研究LCL滤波的PWM整流器控制策略具有重大的理论意义和重要的实用价值。首先分析了LCL滤波的三相电压型PWM整流器拓扑结构，分别建立了在a-b-c坐标系下、α-β坐标系下和d-q坐标系下的数学模型，对LCL滤波器的性能、参数设计方法和阻尼方法进行了详细分析。其次，详细介绍了固定开关频率控制策略的原理和特性，然后针对LCL滤波器存在的谐振问题，提出一种基于LCL滤波的PWM整流器无阻尼控制策略。利用系统延时和固定开关频率控制本身的阻尼，通过调节PI调节器的采样时间实现系统稳定，采用简化电容传感器设计，优化系统结构。仿真结果表明，系统动态性能良好，网侧电流谐波明显减少，LCL滤波器产生的谐振得到了有效抑制。第三，对传统的基于L滤波的三相PWM整流器直接功率控制策略进行分析，然后对无阻尼LCL滤波的PWM整流器直接功率控制策略进行了详细的分析，仿真结果验证了无阻尼LCL滤波的PWM整流器直接功率控制策略的优越性能。最后，设计完成了LCL滤波的PWM整流器控制系统实验平台，并对硬件电路和软件设计进行了详细分析。实验结果表明，直流侧输出电压稳定，网侧电流畸变率低，LCL滤波器产生的谐振得到了有效抑制，基本达到了预期控制效果。
[Abstract]:Three-phase voltage source PWM rectifier has the advantages of sinusoidal input current on the grid side, can achieve unit power factor control, and the DC side voltage is stable and adjustable. New energy generation and HVDC transmission are widely used. But the three-phase PWM rectifier will produce high harmonic, which will have a serious impact on some sensitive load equipment, and will also produce energy loss. If the inductance of the rectifier is increased, the harmonic can be reduced, but the dynamic performance of the system will be affected, and the cost and volume of the. LCL filter can be increased by a smaller inductance to achieve a better filtering effect. It can effectively suppress the high order harmonics of the incoming current, and the inductor can also restrain the impulse current, which not only makes the system have very good dynamic performance, but also reduces the cost and volume. Therefore, it is of great theoretical significance and practical value to study the control strategy of PWM rectifier with LCL filter. Firstly, the topology of three-phase voltage-source rectifier is analyzed, and the mathematical models in a-b-c coordinate system, 伪-尾 coordinate system and d-q coordinate system are established respectively. The parameter design method and damping method are analyzed in detail. Secondly, the principle and characteristics of the fixed switching frequency control strategy are introduced in detail. Then, aiming at the resonance problem of the LCL filter, an undamped control strategy for the PWM rectifier based on the LCL filter is proposed. By adjusting the sampling time of Pi regulator, the system stability is realized by using the damping of system delay and fixed switch frequency control, and the system structure is optimized by using simplified capacitive sensor design. The simulation results show that the dynamic performance of the system is good, and the harmonics on the grid side can effectively reduce the resonance generated by the LCL filter. Thirdly, the direct power control strategy of traditional three-phase PWM rectifier based on L filter is analyzed, and then the direct power control strategy of undamped LCL filter is analyzed in detail. The simulation results verify the superior performance of the direct power control strategy of the undamped LCL filter PWM rectifier. Finally, the experiment platform of PWM rectifier control system with LCL filter is designed, and the hardware circuit and software design are analyzed in detail. The experimental results show that the output voltage of DC side is stable and the resonance generated by LCL filter with low current distortion rate on the grid side is effectively suppressed and the desired control effect is basically achieved.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM461

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