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In view of problem that it is difficult to accurately locate device failure of inverter, a fault tolerance topology of three-level four-leg NPC inverter was proposed. In the topology, short-circuit fault and open-circuit fault can be located accurately by switching device used when topology changes, so as to provide a basis for fault-tolerant control of inverter. The topology enables half-leg replacement, and can achieve fault-tolerant control of up to three inverter legs at the same time.

For problem of large calculated amount of existing distinguishing method of open-circuit IGBT of three-level NPC inverter, all kinds of open-circuit states of IGBT were simulated, and the causes of bus neutral-point voltage deviation were analyzed, then a simple method to distinguish the open-circuit IGBT was proposed. The method achieves distinguishing of open-circuit IGBT by detecting bus neutral-point voltage and three-phase output voltage of inverter, which needs no extra hardware. The simulation results verify effectiveness of the method.

To improve virtual human motion simulation and generation efficiency in virtual assembly and maintenance (A&M) environment, based on a detailed analysis of virtual human control methods in A&M simulation, a virtual human hybrid control method is presented in this paper. In the proposed method, virtual human A&M motion is divided into three types: primitive motion (PM), fine motion (FM) and transitional motion (TM). For PM, a real operator can drive a virtual human in real time for A&M operation via virtual reality interactive devices; in this way, the PM can be quickly generated. As for FM and TM generation, their semantic-level parameterized models including engineering attributes are created; then, their generation processes are represented; in the generation processes, a virtual human posture automatic reasoning model is established to support auto-generating A&M motion. The approaches in the present study are validated by generating virtual human motions in partial assembly process of auto engine. Results show that the proposed method can improve A&M motion simulation efficiency and support the fast generation of realistic A&M motion. [ABSTRACT FROM PUBLISHER]