PWM Strategy for improved natural balancing of a four-level H-bridge Flying Capacitor Converter
PWM Strategy for improved natural balancing of a four-level H-bridge Flying Capacitor Converter
复制标题
用于改善四电平 H 桥飞电容转换器自然平衡的 PWM 策略
DOI：
10.1109/optim.2015.7426747
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
A. Ruderman
中科院分区：
文献类型：
--
作者：
A. Ibrayeva;V. Ten;Y. Familiant;A. Ruderman
基于飞跨电容的多电平PWM变换器由于电容电压的自然平衡特性而可能是有吸引力的选择。针对四电平H桥飞跨电容变换器（FCC）的自然平衡问题，提出了一种基于移相（PS）PWM的FCC自然平衡方法。理论上的自然平衡时间常数对于零输出电压（调制指数）变得无限大。这可能是许多研究人员对这种和其他电容性多电平电压源逆变器的主动平衡方法感兴趣的原因。本文讨论了自然电压平衡的改善可能性，采用改进的PWM策略不同于经典的PS PWM。由于更好地利用了开关状态冗余，在小输出电压的自然电压平衡率的显着改善。提出了一系列改进的PWM策略，并根据自然平衡阻尼率的考虑确定了最佳策略。自然的平衡机制进行了分析，使用时域平均的方法，结果在简单，易于解释的表达式参数的影响。
Flying capacitor based multilevel PWM converter may be an attractive choice due to the natural balancing property of the capacitor voltages. Previous research on natural balancing of a 4-level H-bridge Flying Capacitor Converter (FCC) with Phase Shifted (PS) PWM showed slow natural balancing rate for small modulation indices. Theoretical natural balancing time constant becomes infinitely large for zero output voltage (modulation index). This was probably the reason that many researchers became interested in active balancing methods for this and other capacitive multilevel voltage source inverters. The paper addresses natural voltage balancing improvement possibilities by employing modified PWM strategies different from classical PS PWM. Dramatic improvement in natural voltage balancing rate for small output voltages is achieved due to making a better use of switching states redundancy. Suggested is a family of improved PWM strategies and the best strategy is identified based on natural balancing damping rate considerations. Natural balancing mechanisms are analyzed using time domain averaging methodology that results in simple easy to interpret expressions regarding parameter influence.