Improved Simulation Approach to Predict IGBT Lifetime in Wind Turbine Systems

摘要

Repairs due to Electrical Systems failures are 27% of the total number of needed repairs on wind turbines from 2.5 kW to 1.5MW, according to a US Department of Energy report on energy efficiency and renewable energy [1]. Moreover, electronic control unit failures represent 16% of the total failures, 3 times more than the failures caused by mechanical or gearbox breaks. Once an IGBT system is past its early life stage where most of the failures occur due to human errors, it goes through a life-time where failures depend on operating conditions including environment of whole systems where IGBT modules and other components are installed together. Advanced simulation techniques used in very early stages of a design flow could heavily assist in making the appropriate decision of selecting the IGBT that matches the life time requirements of the system. In a cycle-accurate variable-time step simulations of the complete system (including wind generators, IGBTs, and FPGA controllers) power cycle life of the IGBT at both the junction and the case temperature can be accurately determined. In this paper, modeling and simulation of IGBTs from Fuji Electric used in a Smart Power Stack is accomplished using novel co-simulation technology of the inverter plant and the controller [2-3]. The system simulation leverages detailed IGBT models to estimate power dissipation, efficiency, and operating temperatures of the devices and of the overall switch-mode circuit that these devices are used in. Correlation of the simulation results with the power cycle curves of the Fuji IGBT leads to the estimation of the IGBT life time under specific stress conditions of the turbine system. Moreover, in today's market 50% of wind turbine inverters do not provide advanced diagnostic and monitoring capabilities, which is another advantage of the Smart Power Stack discussed in this example.