This paper proposes a new zero-voltage and zerocurrent switching (ZVZCS) full-bridge (FB) three-level DC/DC converter (TLDC) with the reduced device count (RDC). The merits of the proposed converter with the corresponding modulation strategy are concluded as follows. In comparison with the zero-voltage-switching (ZVS) FB TLDC, 1) only one blocking capacitor is added to realize the ZVZCS strategy, 2) the primary circulating current and duty cycle loss can be effectively reduced. Also, the wide input voltage range can be satisfied because of having two working patterns. More significantly, the proposed converter with the corresponding modulation strategy can reduce the device count by removing the primary blocking diodes in comparison with other ZVZCS FB TLDCs, which would reduce the conduction losses of primary power devices and thus increase the converter's efficiency. Finally, experimental results are presented to verify the proposed converter with the corresponding modulation strategy. Index Terms-Full-bridge (FB), three-level DC/DC converter (TLDC), wide input voltage range, reduced device count (RDC), zero-voltage and zero-current switching (ZVZCS).

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The nearest level modulation (NLM) based submodule capacitor voltage measuring technology for a modular multilevel converter (MMC) with reduced sensors can effectively reduce the costs of the data acquisition system of MMC and simplify the operation system. One of the technical challenges of this submodule capacitor voltage measuring technology is to reduce the measurement errors of submodule capacitor voltage. This paper proposes an improved submodule capacitor voltage measuring algorithm to overcome this challenge. In the proposed algorithm, by keeping the operation states of submodules unchanged during the continuous control period, the probability of obtaining the actual capacitor voltage is increased, and then the number of corrections of observed capacitor voltage is significantly increased. Thus, the proposed algorithm can effectively reduce the measuring errors. More significantly, the proposed algorithm can also improve the measurement accuracy even in the capacitance deviation situation. Finally, both simulation and experimental results are provided to verify the feasibility and effectiveness of the proposed voltage measuring algorithm.

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Algebraic algorithms are powerful methods in solv-1 ing the selective harmonic elimination (SHE) problem, which 2 can find all exact solutions without the requirements of choosing 3 initial values. However, the huge computational burden and long 4 solving time limit the solving capability of algebraic algorithms. 5 This article presents a novel Newton's identifies-based method to 6 simplify the SHE equations including the order reduction and the 7 variable elimination, thereby reducing the computational burden 8 and the solving time of algebraic algorithms or in other words 9 improving the solving capability of the algebraic algorithms. 10 Compared with existing simplification methods, the proposed 11 method significantly improves the efficiency of solving SHE 12 equations. With the proposed method, the degree of reduction 13 is no longer the bottleneck of solving the SHE equations by 14 using algebraic algorithms. By using the proposed method, the 15 SHE equations with ten switching angles are completely solved 16 with the algebraic algorithm for the first time. The simulation 17 and experimental results indicate that the proposed method is 18 effective and correct.19