A reverse conducting (RC) insulated-gate bipolar transistor (IGBT) with p-poly trench-collectors is proposed. A narrow n-drift region between two p-poly trench-collectors is formed as a self-controlled electron path to the collector contact. Owing to the built-in potential between the p-poly and n-drift regions, the narrow n-drift region is depleted to offer a high-resistance electron path at forward bias, which helps to suppress snapback. At reverse bias, holes accumulate at the n-drift/trench-collector interface and then the potential difference between the p-poly and n-drift regions mainly drops at the thin oxide layer. Thus, the narrow n-drift becomes undepleted to offer a low-resistance electron path, and the RC diode can be turned on. Simulation results show that the proposed RC-IGBT is able to suppress snapback with a much smaller cell width and obtain a 21% lower turnoff loss compared to the conventional RC-IGBT.

Aiming at the problems of high power consumption, weak scalability and short wireless transmission distance of dam safety monitoring system, the key technology of dam safety monitoring based on Lora is proposed. An intelligent monitoring terminal is designed based on ARM LPC1788 and Lora wireless communication module. The low-power relay mode with Lora and 4G transmission function is adopted, and the active loop calling process and threshold trigger early warning process are designed. The platform software automatically receives data to realize the intelligent collection, analysis and early warning of dam multi factor safety data. The engineering application effect is good.

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