Research On In-Situ Monitoring Of Wire Bonding Faults In IGBT Modules Of On-Line Three-Level Neutral-Point-Clamped Inverters

Because of large capacity,high pressure rating,less harmonic contents of output current,small switching loss,and many other advantages,the three-level converter has been used widely and it is the ideal choice fo r high-voltage high-power situations.Compared with other three level topologies,the neutral point clamped three-level converter topology is the most widely studied topology.The reliability of power electronic converters is a major concern in industrial applications because of the use of high-power semiconductor devices,which have high-power density and higher failure rates.Firstly,this paper introduces the research background of the three level NPC converter,and analyzes the reliability of the converter and the semiconductor power devices.It is important to improve the reliability of IGBT modules by considering the potential defects in the internal bonding wires of insulated gate bipolar transistor modules as failure precursor.Secondly,in this paper,the reliability evaluation of the three level inverter,adopt a more mature thermal electrical parameters as the fault sign,with reference value and the calibrated linear relationship obtained at offline state,evaluate junction temperature and the health status of the internal structure in IGBTs by collecting voltage and temperature data.Finally,the appropriate solution was proposed based on the circuit fault tolerant control and the unique inverter(or converter)fine-tuning,and the timing relationship was verified in the MATLAB environment simulation.The prediction method use terminal voltage of IGBT as the reference for monitoring bonding wire health,followed by testing three bridge arms of NPC three-level inverter,and control the PWM waveform to keep the output balance under the condition of not reducing the output power of the inverter.The control strategy can provide accurate prediction results,and allows the operator to locate the sub IGBT module in the power converter,and take appropriate measures to avoid breakdown in time.In the end,a 10 kW three-level NPC converter experiment platform is established,based on sequential logic in simulation,which is composed by DSP from TI Company TMS320F2808 and auxiliary control core CPLD.In this paper,the accuracy of voltage and temperature data acquisition and the output characteristics of the on-line monitoring system are verified.The experimental results verify the correctness and effectiveness of the proposed system and the proposed method.