一种融合最近电平逼近调制的空间矢量调制算法

多电平变换器由于具有较小的电压应力、较高的器件耐压等级和过流能力及较低谐波含量等优点已取代两电平变换器在中高压大功率场合中的应用.级联型多电平H桥变换器(CHMC)由于具有较好的灵活性与高度集成化使得其在工业领域得到广泛应用,文中针对三相CHMC的应用提出一种基于最近电平逼近调制(NLM)技术原理的空间矢量脉宽调制(SVPWM)算法.相比于传统SVPWM算法,所提算法只需检测离参考矢量最近的调制矢量点而无需同时检测三个作用矢量点,算法实时性较强.利用SVPWM算法与NLM算法之间的等效性由三相占空比推出三个作用矢量占空比,利用三相占空比比值的大小推出开关矩阵表达式,由所得表达式直接决定优化的开关序列,并根据该开关矩阵进而推出触发脉冲表达式.所提SVPWM算法不依赖于电平数,算法简便,运算速度快.仿真与实验验证了所提算法的正确性与可行性.

A Cascaded Multilevel Converter-Based Space Vector Pulse Width Modulation Algorithm

Multilevel converters (MCs) have been widely used in medium- and high- voltage applications in terms of their advantages, such as smaller voltage stress, higher voltage and current ratings of switching devices, and optimized harmonic characteristics. Among MCs, cascaded H-bridge multilevel converter (CHMC) is popular for its better flexibility and scalability. Therefore, this paper proposes a nearest level modulation (NLM)-based space vector pulse width modulation (SVPWM) algorithm for a three-phase CHMC. Compared with the traditional SVPWM algorithm, the proposed algorithm only needs to detect the dwelling modulation vector closest to the reference vector instead of detecting three active dwelling vectors at the same time. The proposed algorithm has strong real-time performance. Secondly, according to the equivalence between the SVPWM algorithm and the NLM algorithm, the duty cycles of the three active vectors are derived from three-phase duty cycles, and subsequently, the switch matrix expressions are obtained to directly determine the optimized switching sequences. Finally, the trigger pulses are generated. The proposed SVPWM algorithm is simplified, fast, and independent of level numbers. Finally, simulations and experiments verify the correctness and feasibility of the proposed algorithm.