Fast-Predictive Optimal Control of NPC Multilevel Converters
Fast-Predictive Optimal Control of NPC Multilevel Converters
复制标题
DOI：
10.1109/tie.2012.2206352
复制
发表时间：
2013-02
影响因子：
7.7
通讯作者：
J. Barros;J. F. Silva;Élvio G. A. Jesus
中科院分区：
文献类型：
--
作者：
J. Barros;J. F. Silva;Élvio G. A. Jesus
高处理能力微处理器的发展为电力电子应用中的中点钳位(NPC)多电平转换器实现了新的数字控制方法。本文提出了一种新的多电平变流器预测数字控制方法，称为“快速预测”。该方法在每个控制周期内只需使用NPC三相多电平动态模型方程计算一次最优矢量，而目前的预测方法需要27次计算。通过最小化27个可用向量中的每个向量到最优向量之间的距离来找到最接近最优向量的向量。也可以使用空间矢量调制。所获得的性能类似于预测最优控制，它使用转换器模型来寻找多电平的所有27个响应，然后搜索使控制误差最小的矢量。相对于预测最优控制，在具有27个矢量的多电平变流器中，快速预测将数字处理速度提高了至少150%。这种速度改进将允许使用与三电平逆变器相同的采样频率来控制具有五个或更多电平数量(125个而不是27个矢量)的多电平转换器。将快速预测控制器应用于功率因数接近1的多电平整流器中，以实现交流电流的控制。在整流直流电压中还采用了快速预测控制，以降低直流电压对直流负载扰动的敏感性。仿真和实验结果表明，该快速预测控制器能够控制三相多电平整流器的交流电流，在平衡电容器直流电压的同时，实现了近1.5%的总谐波失真。使用预测控制来调节直流电压，与比例积分控制器相比，改善了约7%。
The development of high-processing-capability microprocessors allows the implementation of new digital control methods for neutral-point-clamped (NPC) multilevel converter in power-electronic applications. This paper presents a new predictive digital control method for multilevel converters, called “fast predictive.” This method computes the optimal vector using the NPC three-phase multilevel dynamic model equations just once in each control cycle, while current predictive methods need 27 calculations. The closest vector to the optimal vector is found by minimizing the distance between each one of the 27 available vectors to the optimal vector. Space vector modulation could be also used. The obtained performance is similar to the predictive optimal control that uses the converter model to find all the 27 responses of the multilevel and then searches for the vector that minimizes control errors. Relative to predictive optimal control, the fast predictive improves digital processing speed by at least 150% in multilevel converters with 27 vectors. This speed improvement would allow multilevel converters with five or higher number of levels (125 instead of 27 vectors) to be controlled using the same sampling frequency of the three-level inverter. The fast-predictive controller is used in a multilevel rectifier with near-unity power factor to enforce the ac currents. Fast predictive control is also used in the rectifier dc voltage to reduce sensitivity of the dc voltage to dc load disturbances. The simulation and experimental results show that the fast-predictive controller is able to control the ac currents of a three-phase multilevel rectifier, achieving nearly 1.5% total harmonic distortion while balancing the capacitors' dc voltages. The use of predictive control to regulate the dc voltage shows an improvement of approximately 7% compared to a proportional-integral controller.