Reliability Analysis of a Three-Port Converter with a Semi-Regulated Bus Voltage Structure with an MPPT Function for Near-Space Vehicles

With the improvement of system integration and complexity, reliability has become an important quality index of near-space vehicles. The non-regulated bus structure cannot meet the requirements for the bus voltage of near-space vehicles in the daytime although it has a high reliability in traditional method of reliability identification. Furthermore, the power density of the fully-regulated bus structure is relatively low while it decreases the reliability of the system. Therefore, the semi-regulated bus structure is more suitable for near-space vehicles. In order to improve the reliability of the energy system, a three-port converter is proposed here according to the working mode and functional requirements of near-space vehicles. The converter can realize highly reliable energy management of the energy system. An approach for systematic full state mission effect reliability modeling and evaluation is proposed. The indices can quantify the functional reliability of the system. A prototype machine with high frequency, high power density and high integration is developed. The proposed structure can improve far more reliability than parallel structure did. The reliability analysis results show that the proposed structure has higher reliability than traditional structures and the similar type structures. It comes to a more accurate conclusion contrary to traditional methods when systematic full state mission effect reliability is considered. The calculation method has higher accuracy than traditional method which evaluated the reliability of different converters working on near-space vehicles.