Abstract：In recent years, switched-capacitor multilevel inverters (SCMLIs) have attracted extensive attention in fields such as renewable energy generation and motor drives. To meet the challenges posed by photovoltaic system application requirements—such as a wide input-voltage range, leakage-current suppression, and high power density—this paper proposes a single-stage switched-capacitor multilevel inverter with a wide voltage gain. Its common-ground structure can effectively eliminate leakage current. Compared to traditional SCMLIs, it requires only one additional input inductor to achieve wide-voltage-gain regulation through switching-device reuse. It is because the input voltage source is disconnected from the load during the negative half-cycle of the output, leaving the capacitor to supply the load and continue discharging for milliseconds. Consequently, capacitors in the millifarad (mF) range are usually necessary. To improve the converter's power density, this paper introduces a new modulation strategy for the proposed topology. By extending the capacitors' charging interval, the voltage ripple is minimized, thereby significantly reducing the required capacitance. This paper first examines the working principle of the proposed topology. Combined with an improved level-shifted sinusoidal pulse width modulation (LS-SPWM) method, a quantitative analysis of the system's input and output characteristics is conducted. Thus, key parameters, such as capacitor and inductor ripples, voltage and current stresses on the switching devices, are analyzed. The capacitor voltage and inductor current ripple comprise both high-frequency and low-frequency components. The magnitude of the high-frequency component is inversely proportional to the switching frequency, making it several orders of magnitude smaller than in traditional common-ground SCMLIs. Meanwhile, the low-frequency component associated with the conventional DC-link capacitance has been distributed across multiple smaller capacitors in the proposed topology, thereby reducing the volume and size of each capacitor. The proposed inverter also achieves multilevel output, thereby reducing the total harmonic distortion of the AC output voltage. The proposed topology offers a wider voltage-gain regulation range and lower capacitor usage than existing common-ground SCMLI solutions. A simulation model was built on the PSIM 12.0 platform, and a prototype circuit was constructed in the laboratory. Simulation and experimental results verify the correctness of the aforementioned theoretical analysis. The experiments demonstrate that the topology can maintain efficient and stable multilevel output over a wide input voltage range (Vin is 30 V to 60 V, Vout is 220 V), with continuous input current and effective suppression of leakage current in photovoltaic systems. The operational performance and control effectiveness of the prototype were tested under varying load and input voltage conditions. When the load is switched from a resistive load to a resistive-inductive (RL) load (from full load to half load), the output voltage waveform remains almost unaffected. Moreover, even with a significant change in input voltage, the proposed inverter can output a stable 220 V AC multilevel voltage without noticeable fluctuations. The measured peak efficiency under rated conditions reaches 96.3%.
嵇保健, 张建栋, 刘国梁, 姚佳. 一种宽增益开关电容多电平逆变器及其低容值调制策略[J]. 电工技术学报, 2026, 41(20): 7058-7070.
Ji Baojian, Zhang Jiandong, Liu Guoliang, Yao Jia. A Switched-Capacitor Multilevel Inverter with Wide Voltage Gain and Its Low-Capacitance Modulation Strategy. Transactions of China Electrotechnical Society, 2026, 41(20): 7058-7070.
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