A SiC MOSFET Driver Self-Powered Method For DC Circuit Breaker Using Thermoelectric Generation

DC circuit breaker using fully controlled power electronic devices for DC fault current breaking is an important equipment for protecting the DC transmission system.The power electronic device driver board requires a highvoltage isolated energy supply system,which is generally achieved by taking energy from nearby sources in traditional power electronic equipment such as coverter.However,due to the long-term stable current flow state of DC circuit breaker,its internal power electronic devices do not withstand voltage or alternating current during operation.The devices can only be powered from the ground secondary power supply through a multi-channel high-voltage isolation power supply system,which is complex and expensive.In response to the power supply problem of secondary driver boards in DC circuit breaker,a self-power supply method for secondary driver boards using the high-temperature working characteristics of SiC MOSFET for thermoelectric generation is proposed in this paper.A multi-physical coupling model is established to optimize the self-power supply system with multiple parameters and a 1.7kV/400A DC switch prototype with long-term stable self-power supply is successfully developed.The proposed method provides a new solution for the self-power supply scheme of device driver boards in the DC circuit breaker.Firstly,utilizing the unique high-temperature operating characteristic of SiC devices,a device driver self-power supply scheme based on the Seebeck effect is proposed to extract electrical energy from the temperature difference between the high-temperature device and the surrounding environment.By establishing thermal circuit models for two configuration schemes,calculating and analyzing the impact of different configuration schemes on device junction temperature and power generation efficiency,a configuration scheme for the parallel connection mode of thermocouples and heat sinks was determined.And two specific application schemes under full operating condition and low load condition are proposed based on the existing DC circuit breaker energy supply methods.Secondly,a multi-physical coupling model of SiC MOSFET driver selfpower supply method is established,revealing the coupling relationship between fluid field,thermal field,and electric field in the self-power supply scheme.In response to the design requirements of self-power supply scheme,a multi parameter optimization method for self-power supply scheme with the goal of minimizing cost is proposed through in-depth analysis of the thermal constraint of power device,thermocouple output power constraint,and the heat transfer process of forced heat transfer through heat sinks.Finally,the 1.7kV/400A self-powered DC circuit breaker prototype is developed according to the proposed parameter optimization method.The overall temperature distribution of the prototype is calculated through simulation and provides the basis for the experimental scheme design combined with the characteristic measurement of thermocouples.The SiC MOSFET driver selfpower was realized experimently,and the relative error between the experimental results and the simulation results was less than 10%.The self-power supply system can provide 2.4W of power to the driver board when the circuit breaker is stably flowing,meeting the energy supply needs of SiC devices.