A Flexible Discontinuous Modulation Scheme With Hybrid Capacitor Voltage Balancing Strategy for Three-Level NPC Traction Inverter
A Flexible Discontinuous Modulation Scheme With Hybrid Capacitor Voltage Balancing Strategy for Three-Level NPC Traction Inverter
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DOI：
10.1109/tie.2018.2851967
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发表时间：
2019-05
影响因子：
7.7
通讯作者：
S. Mukherjee;S. Giri;Subrata Banerjee
中科院分区：
文献类型：
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作者：
S. Mukherjee;S. Giri;Subrata Banerjee
多电平逆变器现在正被应用于电动汽车（EV）。针对感应电动汽车的动态运行工况，提出了一种三电平中点箝位逆变器（NPC逆变器）的柔性断续调制策略，该策略可实现正弦脉宽调制（SPWM）到断续PWM（DPWM）的无缝转换。在每个程度的不连续性，以确保最小的开关损耗为可变负载功率因数的调制方案是广义的。此外，一个混合的电压平衡策略，其中包括两组补偿偏移信号具有互补的功能，已被引入到减轻在逆变器的中性点电压偏差问题。所提出的混合平衡方法的独特之处在于，它产生均匀的补偿中性点电流，而不管不连续性的水平。这导致覆盖SPWM和DPWM的整个调制过渡的相同且可预测的电压平衡动态。它已被证明，所提出的混合平衡策略不会失去其不平衡补偿强度，即使在过渡期间从一个调制模式到另一个。通过大量的仿真研究了所提出的方案的有效性，在广泛的变化的操作条件下，并在实验中使用的原型NPC逆变器与感应电动机负载进行验证。
Multilevel inverters are now-a-days being applied in electric vehicles (EV). Considering the dynamic operating conditions of an EV propelled by an induction motor, this paper proposes a flexible discontinuous modulation strategy for three-level neutral-point-clamped (NPC) inverter that can shift modulation pattern seamlessly from sinusoidal pulsewidth modulation (SPWM) to discontinuous PWM (DPWM). The modulation scheme is generalized at each degree of discontinuity to ensure minimum switching losses for variable load power factors. Additionally, a hybrid voltage balancing strategy, which comprises two sets of compensating offset signals with complementary features, has been introduced to mitigate voltage deviation problem at neutral point of the inverter. The unique feature of the proposed hybrid balancing approach is that it generates uniform compensating neutral current regardless of the level of discontinuity. This results in identical and predictable voltage balancing dynamics for the entire modulation transition covering SPWM and DPWM. It has been shown that the proposed hybrid balancing strategy does not lose its unbalance compensation strength even during transition from one modulation pattern to another. The effectiveness of the proposed scheme for wide variations in operating conditions is studied through extensive simulation, and validated in experimentation using a prototype NPC inverter with induction motor loads.