标题：A Family of Neutral-Point-Clamped Circuits of Single-Phase PV Inverters: Generalized Principle and Implementation
作者：Zhou, Liwei; Gao, Feng; Xu, Tao
作者机构：[Zhou, Liwei; Gao, Feng; Xu, Tao] Shandong Univ, Minist Educ, Key Lab Power Syst Intelligent Dispatch & Control, Jinan 250061, Peoples R China.
通讯作者地址：[Zhou, L]Shandong Univ, Minist Educ, Key Lab Power Syst Intelligent Dispatch & Control, Jinan 250061, Peoples R China.
来源：IEEE TRANSACTIONS ON POWER ELECTRONICS
关键词：Common-mode voltage; neutral-point-clamped (NPC) circuit; photovoltaic; (PV) inverter; single-phase inverter
摘要：The common-mode leakage current should be carefully considered when designing a transformer-less photovoltaic (PV) inverter since the leakage current can cause the output current distortion and increase the operational risk. The unipolar sinusoidal pulse width modulation of the traditional H-bridge inverter can produce the superior output performance but will cause a high-frequency fluctuated common-mode voltage and consequently the nonnegligible leakage current. To attenuate the fluctuation phenomena of common-mode voltage, few neutral-point-clamped (NPC) circuits have been designed to clamp the neutral-point voltage andmaintain the common-mode voltage constant. This paper analyzes the equivalent common-mode circuit of single-phase inverters and proposes a generalized design principle of multiterminal NPC circuits, whose unidirectional and bidirectional variations are fully analyzed. Subsequently, two types of single-phase PV inverters with the NPC circuits are proposed. Also, the operational losses and component counts are compared between the proposed topologies and the traditionalNPC inverters. The experimental results verified the theoretical findings.