开关电感型单相五电平电流源逆变器

多电平电流源逆变器因具有高安全性、低输出谐波特性等优点得到广泛关注。提出了一种开关电感型单相五电平电流源逆变器，其直流控制单元采用Buck结构，为电感提供了独立的充放电回路，实现了电感电流控制与输出电流控制的完全解耦，使用较小电感即可控制电流稳定。所提逆变器采用开关电感结构形成多电平输出，减少了器件数目，利用其高度对称性可简化外围电路设计。针对于单相逆变器输入侧电感电流存在二倍频波动的问题，在传统比例积分控制的基础上，增加功率前馈控制，以储能电感在每个开关周期内实现电流恒定作为先决条件，折算不同状态下直流侧开关器件的占空比扰动量，在不增加电路复杂度的前提下，采用较少器件和小储能电感有效抑制了电感电流的二倍频波动，减小了输出电流中3次谐波含量和总谐波畸变率，提高了输出电能质量。最后，通过仿真和实验验证了所提拓扑和控制策略的可行性。

Single-phase five-level current source inverter based on switched-inductor

Multi-level current source inverter has attracted extensive attention because of its high security and low output harmonic. A single-phase five-level current source inverter based on switched-inductor is proposed. The DC control unit adopts Buck structure, which provides an independent charging and discharging circuit for the inductor, realizes the complete decoupling of inductor current control and output current control, and controls the current stability by using a small inductor. The proposed inverter adopts the structure of switched-inductor, which reduces the number of devices, and its high symmetry can simplify the design of peripheral circuits. Aiming at the problem of double frequency fluctuation of inductor current at the input side of single-phase inverter, the power feedforward control is increased based on the traditional proportional integral control. Taking the constant current of the energy storage inductor in each switching cycle as the prerequisite, the duty cycle disturbance of the DC side switching devices under different states is converted. Without increasing the complexity of the circuit, less devices and small energy storage inductors are used to effectively suppress the double frequency fluctuation of the inductive current, reduce the third harmonic content and total harmonic distortion of the output current, and improve the output power quality. Finally, the feasibility of the proposed topology and control strategy is verified by simulation and experiment.