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摘要： PO-1356

关键词： IGBT   Semi-superjunction   Trench gate   R-on.A  

摘要： In this paper, an asymmetric semi-superjunction (SJ) insulated gate bipolar transistor (IGBT) is proposed and investigated. The buffer layer of proposed device is split into two unequal segments with decreasing order of doping in x-direction. One segment is moderately doped, named B-N( (+)), while other is low doped known as B-N((-)). Region B-N((-)) offers maximum flow of carriers, resulting in increase of collector current density with similar breakdown voltage (BV). In off-state, excess electric field exists due to high voltage. This needs to be restricted which is achieved by B-N((+)) region. In semi-SJ device drift resistance is reduced which gives a better performance in the off-state, leading to the lower turn-off loss. Outcomes of TCAD simulation result show a 50.6% reduction in oN-state resistance without degrading the By. Furthermore, 48.8% and 20.3% reduction in turn-off loss and forward voltage drop, respectively, are also observed.

关键词： Insulated gate bipolar transistors   Short-circuit currents   Voltage   Snubbers   Clamps   Circuit faults   Aging   Clamp mode snubber   series insulated gate bipolar transistors (IGBTs)   short-circuit fault   voltage balancing  

摘要： This article proposes a scheme for balancing the voltage of series-connected insulated gate bipolar transistors (IGBTs), which is also very effective under short-circuit conditions. An optimized clamp-mode snubber is proposed, including an active-driver to balance the currents of the IGBTs during short-circuit, which in turn allows for a considerable reduction of the snubber capacitance. The approach is proven to be effective under short-circuit conditions by a maximum of 55 V voltage increment and a negligible difference in the current values. The effectiveness of the proposed approach is demonstrated through simulations in PSPICE software and experimental tests performed at 2 kV.

关键词： Semiconductor   Physicochemical-microstructural   Critical energy   Critical stress   Crack propagation  

摘要： The thermal fatigue of the bond-wire contacts at the topside interconnections of power electronic devices is one of the main reliability issues. This paper presents a new methodological approach to characterize and model the damages during aging by a combination of fracture mechanics and physicochemical approaches. The approach relies first on correlating the change of the microstructure with aging at the bond-wire contact, then on looking for possible links between the microstructure and the parameters of damage models. After reviewing the effect of the microstructure on the whole cycling process, the correlation is made by relating the driving force of the device failure which is the crack propagation to some physicochemical properties and microstructural parameters such as surface energy (gamma(s)), grain boundary energy (gamma(gb)), misorientation angle between neighbor grains (delta theta), plane of orientation of each singular grain, grain size and hardness values (H). This requires EBSD analysis and some post treatments. Those relationships were then used to configure the effect of the microstructure on cracks passage at the interconnection interfaces using cohesive zone models (CZM).

关键词： Condition monitoring   insulated gate bipolar transistors (IGBTs)   reliability   thermal resistance  

摘要： Condition monitoring is a cost-effective means to reduce the unscheduled maintenance cost of insulated gate bipolar transistor (IGBT) modules. The junction to case thermal resistance R-thjc is considered as a critical health indicator of IGBT module solder layer. However, thermal interface materials' (TIMs) deterioration will not only reduce the heat dissipation performance but also affects the accuracy of R-thjc monitoring of IGBT modules. This article investigates the effect of thermal grease deterioration on R-thjc monitoring of IGBT module. First, it is found that the thermal grease deterioration will lead to the decrease of monitored R-thjc of IGBT module under the same health status of IGBT solder layer, despite that the thermal resistance of TIM increasing as deterioration of the TIM takes place. That is, the same monitored increment ratio of R-thjc caused by the solder fatigue may correspond to different health status of the IGBT module, which cannot accurately reflect its actual health status. Then, a compensation strategy for thermal resistance monitoring based on the TIM aging rate is proposed, which uses the established mapping relationship to decouple the negative coupling part of TIM degradation. The compensated thermal resistance can better reflect the actual health status of the IGBT module and approximately eliminate the negative impact. Finally, the feasibility of the proposed compensation strategy is verified by finite element model (FEM) analysis and experiments.

关键词： physics-based   current characteristics   high voltage soft-punch   output voltage   insulated gate bipolar transistors   Zener diodes   dynamic avalanche characteristic   IGBT   high-voltage soft-punch   output characteristic analysing expressions   safe operating area   switching self-clamping mode   excellent soft turn-off behaviour   piece-wise analysing expressions   extreme SOA conditions   output-characteristic analysing expressions   extreme SOA turn-off waveforms   parameter estimation  

摘要： A physics-based turn off model and its output characteristic analysing expressions have been investigated for the high voltage soft-punch through IGBTs under extreme SOA (safe operating area) conditions to depict the excellent soft turn-off behaviour in this paper. The main contributions have been made as the followings: (1) Based on the interior structure and features, one virtual capacitor and two Zener diodes are respectively employed to model its dynamic avalanche characteristic and switching self-clamping mode. (2) By using the user datasheet and typical experimental waveforms, a parameter estimation approach is developed. (3) To simulate extreme SOA turn-off waveforms of the IGBT by using MATLAB and MATHCAD program, the piece-wise analysing expressions have been given out to simulate the output voltage and current characteristics. The new model and its analysing expressions have been validated with experiments. The simulation results show a good agreement with its experimental waveforms.

关键词： 4H-SiC   P-floating   snapback   turn-off loss  

摘要： In this paper, a 4H-SiC IGBT with a multifunctional P-floating layer (MP-IGBT) is proposed and investigated by Silvaco TCAD simulations. Compared with the conventional 4H-SiC field stop IGBT (FS-IGBT), the MP-IGBT structure features a P-floating layer structure under the N-buffer layer. The P-floating layer increases the distributed path resistance below the buffer layer to eliminate the snapback phenomenon. In addition, the P-floating layer acts as an amplifying stage for the hole currents' injection. The snapback-free structure features a half-cell pitch of 10 mu m. For the same forward voltage drop, the turn-off loss of the MP-IGBT structure is reduced by 42%.

关键词： multifaceted parameters   electromagnetic interference   voltage overshoot   active voltage gate driver   digitalized active gate driver   switching transitions   insulated gate bipolar transistors   three-step segmented method   semiconductor diodes   sophisticated gate driver   segmented drive booster   IGBT switching improvement   dynamic switching waveforms   parasitic turn-on fault   four-step AVGD control   ancillary functions   driver circuits   switching losses   traditional constant voltage gate driver method   low voltage control circuits   complementary freewheeling diode   power semiconductor switches   high power transistors   four-step gate control method   transistor switching operations   turn-on switching losses   segmented voltage control   voltage control   field effect transistor switches   power converters  

摘要： Gate drivers form an essential interface between the high power transistors and low voltage control circuits in power converters to govern the transistor switching operations and maintain other ancillary functions. A sophisticated gate driver with a segmented drive booster allows optimized trajectories to be staged out during switching transitions, which provides an extended degree of control freedom at the device level. This helps to improve the trade-offs between multifaceted parameters such as switching losses, overshoots, ringing, and electromagnetic interference, parasitic turn-on fault, etc. In this paper, a digitalized active gate driver with segmented voltage control is designed and experimentally verified, which is capable of shaping the dynamic switching waveforms of Insulated Gate Bipolar Transistors (IGBT) using a four-step gate control method. Compared to the traditional constant voltage gate driver method and the three-step segmented method, the proposed four-step AVGD control demonstrates reductions of the IGBT turn-on current overshoot and suppressions of the voltage overshoot on the complementary freewheeling diode without sacrificing its turn-on switching losses.

关键词： Electric inverters  

摘要： Estimation of accurate IGBT junction temperature is crucial for reliability assessment. The well-known RC lumped approach can help predict junction temperature. However, this method suffers from inaccuracy while characterizing the thermal behaviour of several IGBT modules mounted to the liquid-cooled heatsink. Specifically, the thermal challenge originates from the thermal cross-coupling and module-to-module heat spreading and the converter cooling condition. This article explores the impact of heat spreading, thermal interface material, and massive size liquid cold-plate on the overall thermal behaviour. A case study of 50kW traction inverter is chosen to conduct electro-thermal simulation. Power loss is initially estimated using an analytical loss model and later the estimated power loss is used in FEA (Finite Element Analysis) thermal model. This paper also compares the performance of single-phase and two-phase liquid cooling and various thermal interface materials (TIM) to determine which type of cooling system and TIM is most suitable for real applications. Simulation results obtained from two-phase liquid cooling show reduction of flow rate by a factor of 2 compared to a single-phase liquid cooling. The use of appropriate TIM can reduce junction temperature by 4.5%, 4.2%, 4.6% for the traction power load 30kW, 40kW, and 50kW, respectively. © 2022, The Authors. All rights reserved.