适合高输入电压的高频隔离逆变器

High-frequency Isolated Inverter for High Input Voltage

不带变压器的逆变器缺少电气隔离,安全程度较低。将高频隔离环节引入多电平逆变器,在具备输出电压质量高、开关管电压应力低等多电平逆变器优点的同时,实现高频电气隔离,提高安全程度,因此适用于较高输入电压的应用场合。对此,文中提出一种高频隔离九电平逆变拓扑,分析该拓扑的工作模态,设计多重载波调制策略,研究直流侧电容电压与母线电流间存在的关系,并据此设计出对电容电压存在相反影响的2种开关序列,给出直流侧电容电压均衡策略。最后,在Power Simulation中搭建仿真模型,并制作1 kVA的实验样机,仿真和实验结果验证了所提新型拓扑、控制方法及均压策略的正确性和可行性。

Transformer-less inverters are less safe due to lack of electrical isolation. The high-frequency isolation link is introduced into the multi-level inverter, which makes the inverter have the advantages of high output voltage quality, low switch voltage stress, high-frequency electrical isolation and higher safety. All above makes transformer-less inverters suitable for high input voltage situations. In this regard, a high-frequency isolated nine-level inverter is proposed. Its working modes are analyzed, and the multi-carrier modulation strategy is designed. The relationship between DC-link capacitor voltages and DC bus currents is studied.Based on this, two switching sequences with opposite effects on capacitor voltages are designed, and the DC-link capacitor voltage balancing strategy is given. Finally, a simulation model is built in Power Simulation, and an experimental prototype with capacity of 1 kVA is manufactured. The simulation and experimental results verify the correctness and feasibility of both the proposed new topology and DC-link capacitor voltage balancing strategy.