基于事件触发的三电平感应电机低开关频率预测电流控制方法

Low Switching Frequency Predictive Current Control Method for Three Level Induction Motor Based on Event Trigger

摘要

随着高性能工业驱动领域的快速发展，对中高压电机驱动系统提出了更高的控制精度、响应速度和能效要求，如何在低开关频率条件下兼顾电流控制精度与系统效率，已成为三电平感应电机驱动系统中的关键技术难题．本文针对中点箝位型逆变器感应电机驱动系统在低开关频率下的电流控制精度下降、中点电压漂移以及动态响应性能不足等关键问题，提出了一种基于事件触发机制的三电平感应电机预测电流控制方法．首先，建立感应电机复矢量数学模型，为后续预测控制算法提供建模基础；其次，详细分析3L-NPC逆变器的结构及其电压矢量特性；再次，开展基于电流轨迹的枚举预测优化、同步角与反电动势估测方法、结合中点电压预测的电压矢量寻优准则等关键控制环节的研究；最终，构建完成基于事件触发机制的完整预测电流控制策略．在高调制系数条件下，电流轨迹会逐渐偏离线性轨迹，破坏控制算法对电流行为的线性假设．为确保系统始终运行，在满足电流轨迹线性假设的工况下在额定速度和额定负载条件下，监测不同励磁电流下的电流轨迹，通过调制系数判定其线性有效性，进而确定从线性向非线性过渡的临界励磁电流参考值，明确电流环稳定运行的边界条件．实验结果表明，所提出的控制方法在实现快速电流响应的同时，显著抑制了扰动下的中点电压漂移，降低了系统平均开关频率.

Abstract

With the rapid development of high-performance industrial drive systems，medium- and high-voltage motor drives face increasing demands for higher control accuracy，faster dynamic response，and improved energy efficiency. In three-level induction motor drive systems，a key challenge was balancing current control accuracy and system efficiency under low switching frequency conditions. To address critical issues such as degraded current control accuracy，neutral point voltage drift，and insufficient dynamic performance in such scenarios，this paper proposed a predictive current control method for three-level induction motors based on an event-triggered mechanism. First，a complex vector model of the induction motor was established to provide the foundation for the predictive control algorithm. Then，the structure and voltage vector characteristics of the three-level neutral point clamped(3L-NPC) inverter were analyzed. Subsequently，several key control components were investigated，including current-trajectory-based enumerative predictive optimization，synchronous angle and back electromotive force(EMF) estimation，and a voltage vector selection criterion incorporating neutral point voltage prediction. Based on these，a complete event-triggered predictive current control strategy was developed. Under high modulation index conditions，current trajectories deviated from ideal linear paths，violating the algorithm’s linearity assumption. To ensure stable operation at rated speed and load while maintaining the validity of the linear trajectory assumption，current trajectories under different excitation currents were monitored. A modulation index-based criterion was introduced to identify the transition from linear to nonlinear behavior，thereby defining the boundary conditions for stable current loop operation. Experimental results demonstrate that the proposed control method achieves fast current response，effectively suppresses neutral point voltage drift under disturbances，and reduces the system’s average switching frequency.

关键词

感应电机 / 预测控制 / 开关频率 / 中点电压

Key words

induction motor / predictive control / switching frequency / neutral point voltage

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基金资助

国家自然科学基金资助项目(51407007)

佛山市人民政府科技创新专项资金资助项目(BK21BE016)