Operation Of Insulated Gate Bipolar Transistor Research Articles

A current sharing snubber of parallel IGBTs based on duality principle

Parallel connection of multiple insulated gate bipolar transistors (IGBTs) is an important approach to improve the current level of equipment in applications of power electronics. The key to ensure the safe and stable operation of parallel IGBTs is to realize current sharing for them. A novel current sharing snubber of parallel IGBTs is proposed for high-power applications, which is derived from a voltage sharing snubber of series IGBTs by duality principle. It not only effectively suppresses the overcurrent and static and dynamic current imbalance, but also possesses advantages of simple structure and easy implementation. The operating principle and deficiencies of the proposed snubber are first analyzed, and then the improved topology is presented. In order to apply the snubber to multiple IGBTs, various topologies and their derivation processes are given. The improvements are carried out and suitable structures are determined by analysis and comparison. In addition, the effectiveness and feasibility of the proposed snubber are verified by experiments. Finally, the proposed snubber is compared with other current sharing methods.

방열판의 온도를 이용한 IGBT 모듈 및 공랭시스템의 상태 모니터링

The insulated gate bipolar transistor (IGBT) is one of the weakest components in the converter. Therefore, high reliability is very important in terms of price. However, it is very difficult to monitor IGBT’s condition because it is not easy to directly measure the junction temperature in practice. And cooling system also important element of converter, but additional method should be used to monitor cooling system. This paper proposes a method of monitoring the condition of IGBT module and cooling system at once by heatsink temperature that is easy to measure. Advantage of proposed method is very easy to implement without interfering operation of IGBT. Simulation tests were conducted to verify the effectiveness and accuracy of this proposed method. The results show that the proposed method can improve accuracy of the reliability of power converter.

Independent closed loop control of di/dt and dv/dt for high power IGBTs

As the insulated gate bipolar transistor (IGBT) modules have their own specific characteristic switching forms, their turn-on and turn-off times are changed according to practical applications. For the conventional gate drives, gate resistors are used to adjust the turn-on and turn-off times which change switching losses that have a significant amount in total losses. Collector current rate of change, $di_{C}/ dt$ and collector-emitter rate of change, $dv_{CE}/ dt$ are dependent on each other and they affect operating parameters in high power converters. Relations between current and voltages during the switching transitions are given and effects of the changes in electrical parameters for the operation of IGBT are described. Thereafter, closed-loop gate drive with analog control that performs independent control of $di_{C}/ dt$ and $dv_{CE}/ dt$ of a new generation IGBT module platform for high power applications is proposed. Unlike conventional gate drives, proposed closed-loop drive makes constant $di_{C}/ dt$ possible while $dv_{CE}/ dt$ is decreased to increase the efficiency of the power conversion system. This leads to decrease of the switching losses without changing the electromagnetic interference (EMI), IGBT voltage, and current stresses which are related with the rate of change of collector current. Simulations are performed in a double pulse test circuit in which new package next high power density dual (nHPD$^{2}$) family MBM450FS33F Hitachi dual IGBT with 3300V 450A ratings is modelled.

Condition monitoring of IGBT modules using online TSEPs and data‐driven approach

The nonlinear operating characteristics associated with the power electronic converters result in high mechanical and thermal stresses for the power modules. These stresses collectively result in failure modes such as wear-out and sudden failures, which lead to power loss for the system. To overcome these aspects, this paper proposes a condition monitoring approach based on data-driven methods for power modules. The proposed approach is aimed at achieving early detection of power module failure mode by measuring the temperature sensitive electrical parameters (TSEPS) with a measurement and monitoring unit (MMU). To develop the proposed monitoring approach, 12 different online TSEPs of insulated gate bipolar transistor (IGBT) power module are measured with the MMU and trained with a support vector data descriptor classifier. The training process is carried out with a two-chip half bridge IGBT leg which is further operated in a single-phase full bridge inverter configuration during the testing process. Both the training and testing processes of the developed classifier are carried out for IGBT operation at multiple temperatures, and multiple faults to identify the repeatability of the TSEPs. The results of numerical simulations and experimental analysis identified 96.3% training accuracy and 2.9% error in testing accuracy at 90°C junction temperature for degradation identification. For the failure mode classification, the training accuracy is identified to be 98.6%, and 100% testing accuracy at 25°C.

Simulation Study on Dual Gate Control of Surface Buffer Insulated Gate Bipolar Transistor for High Switching Controllability

A new device design in trench-gate insulated gate bipolar transistor (IGBT) with dual gate control is proposed for high switching controllability with low loss operation. Injection enhancement effect is effective to obtain low power loss operation of IGBTs. However, excess drift carriers limit turn-off dV/dt, and turn-on dI/dt, and the switching controllability by the external gate resistance is degraded. Surface buffer (SB) IGBT with dual gate control is effective to improve the switching controllability, because the hole current can be modulated effectively by the p-MOS control. TCAD simulation results show the SB-IGBT type-II with dual gate control is the best choice for good turn-off and turn-on switching performances.

Temperature Control Concept for Parallel IGBT Operation

This paper addresses the concept of load balancing in the operation of parallel insulated-gate bipolar transistors (IGBTs), in which the temperature is used as the main control parameter. In parallel IGBT operation, it is essential to ensure an equal load distribution across all IGBTs. Two basic algorithm concepts for temperature control were developed for the purpose of balancing. A test model based on the parallel IGBTs operation was assembled in a laboratory and the developed algorithms were tested for the chosen parameters. MATLAB was used for final data processing. The comparison between the two implemented basic algorithms provides insights into the temperature behavior of parallel IGBTs in terms of individual IGBT’s heating and cooling trajectories and time constants. All tests were conducted without the heatsinks to obtain the worst-case scenario in terms of thermal conditions. The test results show that temperature control in the operation of parallel IGBTs is possible but limited.

IGBT Heat Dissipation Design and Optimization

The reliable operation of IGBT (insulated gate bipolar transistor) is the key to the performance of motor control system, which directly affects the performance of the vehicle. By contacting with the surface of the radiator, the heat device rapidly transfers heat to the fin, which is then absorbed by the high-speed airflow between the fins and taken away to form a cooling channel to ensure that the heat device is always at an appropriate temperature during work. The power loss of IGBT under rated working conditions was estimated theoretically. The temperature field of the radiator under typical working conditions was simulated by ICEPAK, and the radiator was parameterized. The simulation results show that under the condition of forced cooling and heat dissipation, the optimized radiator meets the heat dissipation requirements of the motor controller.

Base solder voids identification of IGBT modules using case temperature

Solder voids has an important impact on healthy operation of insulated-gate bipolar transistor (IGBT) modules, but voids damage is difficult to be estimated accurately by conventional methods due to the lack of calculation in mutual thermal effect between chips. So this paper proposes a base solder voids identification method by using case temperature, takes into account both self-thermal diffusion and coupling inside module, and adopts case temperature distribution on bottom of baseplate to assess voids damage indirectly. Firstly, finite element method (FEM) of IGBT module with base solder voids was established to study junction and case temperature response with different voids distribution, the practicability of base solder voids identification based on case temperature is verified. Then the influence mechanism of voids on case temperature was discussed theoretically, voids identification is extended to dynamic load conditions, temperature-to-thermal resistance conversion and dynamic thermal resistance reference calibration with different power loss ratio were realized by improved thermal network, recursive least square (RLS) algorithm was designed for dynamic identification of real-time identifiable thermal resistance, the difference between RLS results and thermal resistance reference was compared to confirm the severity of base solder voids, two or more groups of comparison results with different power conditions are used to complete the voids analysis. Finally, validity of proposed method is demonstrated by simulation. Compared with conventional method, it shows better ability in dynamic identification.

Power Loss and Thermal Impedance Modeling of Multilevel Power Converter With Discontinuous Modulation

The hard switching operation of the insulated gate bipolar transistor (IGBT)-based multilevel converters (MLCs) in the transformer less direct integration of renewable power plants produces a considerable amount of switching and conduction power loss. This eventually causes higher junction temperature and lower thermal stability. The symmetrically designed MLC using third harmonic sixty-degree bus-clamped pulse width modulation (BCPWM) technique demonstrates reduced switching losses and better harmonic spectra. However, the development of analytical power loss model is a complex and challenging issue due to the discontinuous switching mode of IGBTs for the BCPWM in MLC. In this regard, an analytical model for calculating the average and the rms currents for the hard switching operation of IGBTs and antiparallel diodes (APDs) with BCPWM is proposed. Furthermore, to calculate the device turn-on and turn-off losses, a discrete form of equation is presented to evaluate the transition times of switching more precisely. The numerical power loss values of IGBTs and APDs found from the derived analytical equations for MLC are compared with the simulation and experimental results. The numerical results agree well with the simulated and the experimental outcomes, which validate the proposed analytical loss model. Moreover, an advanced three dimensional thermal impedance model with chip-wise interdependent multilayer thermal coupling effect is also considered in this paper to realize the critical thermal loading condition of the switching devices.

Characteristics and Influence Factors of Radiated Disturbance Induced by IGBT Switching

The setup for testing radiated disturbance induced by insulated gate bipolar transistor (IGBT) and auxiliary circuits was established. The radiated disturbance characteristics of auxiliary circuits and methods to suppress the radiated electromagnetic interference (EMI) were experimentally studied. The radiated EMI bandwidth of the auxiliary circuit was concentrated in the range 30–300 MHz. The mathematical model for an IGBT was proposed based on the setup, which includes all the structures of the IGBT in detail. The electric fields were calculated from the IGBT model using the method of moments. Moreover, the characteristics of the radiated disturbances due to the IGBT operation and the effects of metal on the radiated electric fields were experimentally and calculatingly studied in the frequency range 1–30 MHz. The metal shielded box of drive can increase the radiated electric fields by approximately 10–30 dB in the range 1–30 MHz. The electric fields for all the frequencies decreased rapidly with the increase of distance. Additionally, methods to shield the IGBT in order to suppress the radiated EMI were proposed. The effective radiated EMI reduction from a shielded net was approximately 20 dB, and that of a shielded box was around 30 dB.

Prediction of IGBT power module remaining lifetime using the aging state approach

Insulated Gate Bipolar Transistor (IGBT) is the core power device in the fields of railways, new energy sources, and automobiles. The safe and reliable operation of IGBT is the basis to ensure the sustained and steady development of all walks of life. The junction-to-case thermal resistance of the IGBT power modules can manifest the fatigue degree of the solder layer. The saturation voltage drop manifests the aging degree of the IGBT bonding wire. Therefore, the IGBT reliability can be judged by a certain rule along with the external parameters such as the junction-to-case thermal resistance Rth and the saturation voltage drop Vce. In order to grasp this rule, this study illustrates the correlations between the external parameters of IGBT and the number of power cycles. As a result, the functional relationships between the average change rate of junction-to-case thermal resistance and the number of power cycles (ΔR¯th—n) as well as the average saturation voltage drop rate of change and the number of power cycles (ΔV¯ce—n) have been gained from IGBT test samples. After obtaining these functional relationships, for any IGBT of the same model in working condition, a proposition of judging the aging degree can be obtained. Here, the aging degree of the IGBT is represented by a real number in the interval [0, 1] and the reliability of the above proposition is calculated from the standard deviation of the working lifetime of each test sample. The method proposed in this study can not only be used to judge the aging degree of IGBT, but also to estimate the remaining lifetime.

Analysis of <italic>V</italic>th Variations in IGBTs Under Thermal Stress for Improved Condition Monitoring in Automotive Power Conversion Systems

Today, power conversion in automotive industry depends heavily on the reliable operation of insulated-gate bipolar transistors (IGBTs). Condition monitoring of IGBTs and reporting imminent faults to driver dashboard are critical for avoiding any fatal accidents. In this study, first, a comprehensive comparison is carried out between on-state collector–emitter drop ( $V_{ce,on}$ ) with gate threshold voltage ( V th), as two reliable aging precursors. In order to enrich current understanding of IGBT aging prognosis, accelerated aging methods are applied under a wide variety of thermal stresses. Aging mechanisms and physical phenomena responsible for variation in both $V_{ce,on}$ and V th have been methodically investigated. These explanations are also supported by detailed failure analysis. Based on the extensive result sets for tested samples from different manufacturers with different structural types, it is found that $V_{ce,on}$ show different trends at different stress levels, whereas under the same test conditions V th provides more consistent and robust state-of-health information. Finally, an example experiment has been performed in which continuous $V_{ce,on}$ measurements coupled with V th information has been used to provide more insight about the device aging as well as faults in an automobile's sub-systems.

Unified view on energy and electrical failure of the short-circuit operation of IGBTs

This work investigates the relation of the two destruction modes, the so-called energy destruction and the electrical destruction, during short-circuit operation of an Insulated Gate Bipolar Transistor (IGBT). The critical energy as a function of the short circuit current reveals a kink indicating the transition between two different failure modes. The failure signatures show that energy destruction takes place at lower currents and electrical destruction at higher currents. This supports the hypothesis that there is a huge current range with non-destructive filaments at low dc-link voltages. For both destruction mechanisms, the final failure occurs locally. For the energy destruction, the current crowding happens very late during the runaway itself, whereas in the case of an electrical destruction, filaments are formed mainly by an electrical mechanism leading to a stronger local self-heating. Both mechanisms take place far above the safe operating area of the chip.

Investigation of artificial neural network algorithm based IGBT online condition monitoring

Reliability of Insulated Gate Bipolar Transistor (IGBT) has drawn much attention in recent years. Online monitoring of IGBT is an effective mehod to improve IGBT operation reliability. State-of-the-art online monitoring methods for IGBT are based on thermal sensitive electrical parameters (TSEPs) extraction, but the TSEPs can be hardly obtained with required accuracy in practical application. This paper investigates Artificial Neural Network (ANN) based IGBT online monitoring method. DC link voltage and H-bridge output voltage, which are practical measurable parameters, are selected as the input of ANN. Both single input single output (SISO) and multiple input single output (MISO) neural networks are analysed and discussed. With the proposed method, the relationship of the practical measurable parameters and investigated TSEP, on-resistance of IGBT, can be established. By applying the existing criterion of TSEPs for the IGBT reliability, the prediction of the IGBT failure can be achieved. Simulations verify that the errors brought by the established model are within precision requirements.

A Hybrid Active Gate Drive for Switching Loss Reduction and Voltage Balancing of Series-Connected IGBTs

Insulated gate bipolar transistors (IGBTs) are usually connected in series to form high-voltage switches in power electronics applications. However, the series operation of IGBTs is not easy due to the unbalanced voltage sharing between them, especially during the switching transients and the tail-current period. In this paper, a hybrid active gate drive is presented for both switching loss reduction and voltage balancing of the series-connected IGBTs. Compared with the conventional gate drive, the proposed method allows dynamical adjustment of the switching speed of IGBTs; thus the switching loss can be suppressed without increasing the current and voltage stresses of the power device. For series connection, the transient voltage sharing is achieved by using an adaptive control method, while the voltage balancing during the tail-current period is optimized by a low-loss snubber circuit. The performance of the proposed hybrid active gate drive and control method has been validated by experimental results.

Investigation of Si IGBT Operation at 200$\,{}^\circ$C for Traction Applications

In order to satisfy the high-density requirement and harsh thermal conditions while reducing cost in future electric and hybrid electric vehicles (HEV), a systematic study of a 1200-V trench-gate field-stop Si insulated gate bipolar transistor (IGBT) operating up to 200°C is performed to determine its feasibility, issues, and application guideline. The device forward conduction characteristics, leakage current, and switching performance are evaluated at various temperatures. Based on the device characterization, the impact of the increased junction temperature on a traction drive converter loss and thermal management is analyzed. It is shown that by extending the device junction temperature to 200°C, the additional 65°C coolant loop can be eliminated without compromising power density and thermal management design. Furthermore, the possible failure mechanisms including latching, short circuit fault, and avalanche capability are tested at elevated temperatures. The criteria considering thermal stability, thermal management, short circuit capability, and avalanche capability are given at 200°C to ensure the safe and reliable operation of Si IGBTs.

Si/SiGe heterojunction collector for low loss operation of Trench IGBT

A new concept of Insulated Gate Bipolar Transistor (IGBT) which uses a SiGe layer for the collector is proposed to suppress the tail-current which is a major cause of the power loss and limits the operation speed of the device. By using p +-SiGe layer for the collector of a n +pn −-type IGBTs, holes injected from the collector into the n − drift region during the on-state can be easily swept away to the SiGe collector when the device is cut-off. Two dimensional device simulation has been carried out for IGBTs which have trench gates. The device is assumed to be thined from the backside of the wafer to about 100 μm and the SiGe collector layer is deposited on the back surface. Simulation results indicated that, the turn-off time is reduced from a few microseconds of the conventional Si collector device to a few hundred nanoseconds of the newly proposed SiGe collector device. Preliminary experiments using SiGe/Si diodes verify the fast reverse recovery. On the other hand, turn-on voltage loss is increased by the use of SiGe collector. We also demonstrate that this drawback can be minimized by adjusting the composition of SiGe and employing a Si-SiGe stripe-shaped collector.

A comparison of IGBT models for use in circuit design

In choosing an accurate insulated gate bipolar transistor (IGBT) model for power electronic circuit design, physics-based models are frequently preferred due to their high accuracy and fast simulation speed in comparison to other types of models. In this paper, an experimental comparison of two such models is made, using parameters extracted from experimental measurements. The comparison focuses on two particular IGBTs-the BUP202 and the BUK854-representing the two common types of IGBT, respectively, the nonpunchthrough and the punchthrough IGBT. The models are investigated for the IGBT's operation in three situations typical of low-power (600 V, 10 A) applications.