Space Vector Modulation (SVM)-exploited Binary Capacitor Voltage Control (BCVC)-based Flying-Capacitor-Clamped Multilevel Converter (FCCMC) for Low Nominal DC Voltage Applications

Maximizing DC-AC power conversion quality and efficiency while minimizing hardware and control complexity is a major technical challenge for multilevel converters in low nominal DC voltage applications. Among the conventional multilevel converters, the flying-capacitor-clamped multilevel converter (FCCMC) has the least hardware and control complexity; and redundant switching combinations for each reference multilevel voltage due to its flying capacitors clamped to serially-connected switches. The space vector modulation (SVM) method synthesizes a reference voltage vector by utilizing the three adjacent voltage vectors, and each voltage vector has a three-phase multilevel-voltage combination redundancy. Furthermore, these switching combination and three-phase multilevel-voltage combination redundancies can lead to various clamped flying-capacitor voltage and converter-leg voltage control strategies. This paper proposes a new FCCMC concept utilizing the advantages of FCCMC and SVM to address the above primary technical challenge. The proposed SVM-exploited binary capacitor voltage control (BCVC) regulates the clamped flying-capacitor voltages at the power-of-two reference values and the converter-leg voltages at the multilevel reference values through a Lyapunov stability-based cost-function optimization approach exploiting the binary numeral system. In low nominal DC voltage applications, the proposed FCCMC significantly improves the DC-AC power conversion quality and efficiency by synthesizing a sinusoidal AC voltage with a large number of voltage levels while extensively reducing the hardware and control complexity. Simulation results demonstrate the steady-state and dynamic performance of the proposed FCCMC under various operating conditions.