Junction Temperature Balancing Strategy for Parallel Insulated Gate Bipolar Transistors Based on Thermal Resistance and Gate Resistance Compensation

An electro-thermal parametric degradation model of insulated gate bipolar transistor modules

Bonded interfaces in power converters add thermal resistances to heat dissipation. Under cyclic power, temperature, or chemical loading, these interfaces degrade, raising the thermal resistances. Reliability of the thermal interfaces is especially problematic when the bonded area is large because the larger the area the more likely it is to have preexisting defects from processing. To help qualifying the development of a bonding process and quantifying the interface reliability, it would be desirable to have a simple, reliable, and nondestructive measurement technique to obtain a 2-D map of the interface thermal resistance across a large bonded area. Based on the transient thermal method of JEDEC standard 51-14, in this article, we develop a measurement technique that involves moving a thermal probe discretely across a large-area bonded substrate and acquiring the thermal interface resistance under the probe at each location. The probe is made by custom-packaging an insulated-gate bipolar transistor (IGBT) power device. An analytical thermal model is developed to gain insights into the effects of probe materials and structural parameters on the sensitivity of the measurement technique. To obtain a 2-D thermal resistance map of a bonded substrate, the probe is thermally coupled to the substrate at one location through a thermal pad or grease; the device is powered up to a steady-state junction temperature; the power is cutoff; and then the junction temperature during cool-down is recorded. The recorded temperature data are analyzed to derive a thermal structure function of the multilayer material stack. The process is repeated at other locations until a 2-D map of the interface thermal resistance across the entire substrate is completed. This technique is demonstrated on copper–copper bonded samples using either a thermal grease or sintered silver. The resolution of the 2-D mapping technique is evaluated by a copper–grease–copper stack with defects implanted at the bond line.

In most of the power electronic applications like electric and hybrid electric vehicles, renewable energy applications, electric traction, power electronic drives and power grid, Insulated Gate Bipolar Transistors (IGBTs) are playing crucial role. For better efficiency, safe operation and gate drive circuit building for the IGBT, it is required to know the static and dynamic characteristics of the IGBT. The dynamic characteristics totally depend on gate resistance and static characteristics depend on junction temperature, collector to emitter voltage, and the gate voltage. In this paper, the static and dynamic characteristics of IGBT have been analyzed at different temperatures, gate resistances and gate voltages. The value of the gate resistance for IGBT can be estimated according to the power range of the IGBT. The recommended gate resistances, gate voltages, and temperature for the application purpose have been given in this paper. For experimentation purpose, Star Power 600 V, 50 A IGBT power module has been used.

With the development of large capacity variable speed constant frequency wind turbines, wind power converters with the multi-chip paralleled insulated gate bipolar transistor (IGBT) modules are widely used as an energy flow interface, a valid junction temperature calculation is vital considering the multichip electro-thermal influences, because thermal analysis is of great significance in terms of safe operation and reliability for the wind power converter. Focusing on the multi-chip thermal coupling effects, this paper proposes an improved thermal couple impedance model for a real multi-chip IGBT module in the power converter of a 2MW doubly fed induction generator (DFIG) wind turbine. First, the steady state junction temperature and thermal coupling profiles are analyzed by using finite element method (FEM). Second, by introducing into the equivalent thermal couple impedance matrix, an improved electro-thermal model is derived. Finally, junction temperatures of chips in different position are calculated by using the improved thermal coupling impedance model, and the results are further compared with those of the traditional thermal model and real tested case temperatures of the 2MW DFIG. Results show that the improved thermal model is much more valid than the traditional model for the thermal analysis of the multi-chip paralleled power module in the wind turbine power converter, and junction temperatures of the chips in non-edge position could be higher and this should be carefully considered in design and operational management control.

This paper proposes a novel method for optimizing the Cauer-type thermal network model considering both the temperature influence on the extraction of parameters and the errors caused by the physical structure. In terms of prediction of the transient junction temperature and the steady-state junction temperature, the conventional Cauer-type parameters are modified, and the general method for estimating junction temperature is studied by using the adaptive thermal network model. The results show that junction temperature estimated by our adaptive Cauer-type thermal network model is more accurate than that of the conventional model.

This paper proposes an in situ diagnostic and prognostic (D&P) technology to monitor the health condition of insulated gate bipolar transistors (IGBTs) used in EVs with a focus on the IGBTs' solder layer fatigue. IGBTs' thermal impedance and the junction temperature can be used as health indicators for through-life condition monitoring (CM) where the terminal characteristics are measured and the devices' internal temperature-sensitive parameters are employed as temperature sensors to estimate the junction temperature. An auxiliary power supply unit, which can be converted from the battery's 12-V dc supply, provides power to the in situ test circuits and CM data can be stored in the on-board data-logger for further offline analysis. The proposed method is experimentally validated on the developed test circuitry and also compared with finite-element thermoelectrical simulation. The test results from thermal cycling are also compared with acoustic microscope and thermal images. The developed circuitry is proved to be effective to detect solder fatigue while each IGBT in the converter can be examined sequentially during red-light stopping or services. The D&P circuitry can utilize existing on-board hardware and be embedded in the IGBT's gate drive unit.

Insulated gate bipolar transistors (IGBT) are used broadly in DC power transmission, power converters, and drives. These applications are cost-sensitive and require high module reliability. Researchers have been found that IGBT degradation over time is directly dependent on its junction temperature. Normally the temperature is measured with a temperature sensor close to the IGBT case or module. This requires the predesigning of the converter or results in a cost-effective and inconvenient process. In this paper, we are proposing a non-invasive method of junction temperature extraction, which do not suffer from the difficulties mentioned above. The method is based on the analysis of electromagnetic radiation (EMR) generated by the IGBT. It has been found that the radiation is a function of switching delay of the IGBT, and this delay is directly proportional to the junction temperature. Thus the junction temperature of IGBT is extracted from the EMR. The method requires only a single loop antenna to capture the radiation. Experimentally to increase the junction temperature of IGBT, an accelerated aging method is adopted. Then the junction temperature, the delay time, and the electromagnetic radiations are measured. The junction temperature is extracted from the inverse relation of these three parameters.

In the exploration of new energy sources and the search for a path to sustainable development the reliable operation of wind turbines is of great importance to the stability of power systems. To ensure the stable and reliable operation of the Insulated Gate Bipolar Transistor (IGBT) power module, in this work the influence of changes with aging of different electro-thermal parameters on the junction temperature and the case temperature was studied. Firstly, power thermal cycling tests were performed on the IGBT power module, and the I-V characteristic curve, switching loss and transient thermal impedance are recorded every 1000 power cycles, and then the electrical parameters (saturation voltage drop and switching loss) and the thermal parameters (junction-to-case thermal resistance) of the IGBT are obtained under different aging states. The obtained electro-thermal parameters are substituted into the established electro-thermal coupling model to obtain the junction temperature and the case temperature under different aging states. The degrees of influence of these electro-thermal parameters on the junction temperature and case temperature under different aging states are analyzed by the single variable method. The results show that the changes of the electro-thermal parameters under different aging states affects the junction temperature and the case temperature as follows: (1) Compared with other parameters, the transient thermal impedance has the greatest influence on the junction temperature, which is 60.1%. (2) Compared with other parameters, the switching loss has the greatest influence on the case temperature, which is 79.8%. The result provides a novel method for the junction temperature calculation model and lays a foundation for evaluating the aging state by using the case temperature, which has important theoretical and practical significance for the stable operation of power electronic systems.

Base solder voids identification of IGBT modules using case temperature

This paper presents an improved thermal network model of insulated-gate bipolar transistor (IGBT) module, which considers the effects of base-plate solder fatigue on the junction temperature of the said module used in wind power converters. First, the coupling thermal structure 3-D finite-element model of the IGBT module is established based on the structure and material parameters of the module used in the wind power converters of a doubly fed induction generator. The junction temperature of the module is investigated at different thermal desquamating degrees of the base-plate solder. Second, the thermal resistance parameters are determined at different desquamating degrees, and the improved thermal network model that considers the effects of the base-plate solder fatigue is established. Finally, the IGBT junction temperature results through the improved thermal network, and the 3-D FEM models are compared.

Insulated gate bipolar transistor (IGBT) module is the critical device of modular multi-level converter (MMC) for flexible high voltage direct current (HVDC) transmission systems. The reliability of the IGBT is directly related to the safety of the converter station, and even affects the stability of the entire flexible HVDC transmission system. In this paper, we take the IGBT commonly used in MMC as the object of study. A coupled electric-thermal-mechanical field simulation model is proposed for 3.3 kV/ 50 A press-pack IGBTs. The model takes full account of multi-physics interactions and the non-linear properties of the material. The influence of pressure on component electrical contact resistance (R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">electrical</inf> ) and thermal contact resistance (R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thermal</inf> ) is considered. The trend of the IGBT junction temperature and voltage drop with increasing conduction current is also investigated. The results show that the junction temperature of the IGBT chip is 55.615°C, and the voltage drop is 2.3342 V under 50 A conduction current. The junction temperature and voltage drop of IGBT increases nonlinearly with the increase of conduction current. This work can support the simulation and reliability evaluation of the press-pack IGBT for flexible HVDC converter valve.

In recent years, IGBT (Insulated Gate Bipolar Transistor) is being more and more widely used in many fields such as new energy generation system, electric vehicle, smart grid and so on. To keep IGBT run stably and reliably is the basis of normal operation of these equipments so the reliability state detection of IGBT modules has become one of the research hotspots in power electronics fields. Many existing researches show that the key factor that determines the failure of IGBT modules and affects their reliability is temperature, which means that the junction temperature of IGBT modules is closely related to its reliability. Therefore, a novel junction temperature extraction technology of IGBT module for on-line reliability state detection is proposed in this paper. Apparently different from thermosensitive parameter which is of low measurement accuracy and poor real-time performance, the IGBT turn-off loss parameter has the advantages of quick response, easy detection and no damage to IGBT structure. This paper describes the correlation between junction temperature and turn-off loss principally and establish a 3D database of current, IGBT turn-off loss and temperature at the rated voltage. Through the theoretical analysis, simulation results and physical verification, it can be obviously figured out that this novel technology is feasible and effective.

Power cycling accelerated aging experiment is an important way to study the evolution process and failure mechanism of insulated gate bipolar transistor (IGBT) power modules under high power load impact. In the accelerated aging experiment, the thermal resistance as a sign of the fatigue fault of the IGBT module solder layer needs to be extracted online in real time, so as to achieve real-time monitoring of the aging degree of the aging process of the IGBT module. Measuring the case temperature with a thermocouple is an important step in the process of extracting the thermal resistance in each power cycle. However, the thermocouple is glued to the IGBT module, and the glue will fall off due to the constant impact and circulation of the temperature during the accelerated aging of the IGBT module. In this paper, in order to avoid the measuring error caused by thermocouple glue in the process of accelerated aging experiment, the correction method in the process of extracting IGBT module thermal resistance is proposed. In this paper, the influence of glue on the thermal resistance extraction is illustrated by finite element simulation and experiment, and the correction method is verified by the stability data in the experiment.

Insulated gate bipolar transistor (IGBT) junction temperature monitoring is crucial for converter's healthy management and condition monitoring. However, most conventional IGBT junction temperature estimation methods are device-level, which means that monitoring junction temperatures of all IGBTs in converters require the same number of monitoring units as IGBTs, which is of high complexity and cost. A converter-level IGBT junction temperature estimation method based on the dc bus voltage ringing is proposed in this article. The peak values of the bus voltage ringing during switching transient display a linear dependence on the junction temperatures of the corresponding switching IGBTs. Hence, the bus voltage ringing can be used for estimating the junction temperatures of the IGBTs in a converter. The validity of the proposed method is verified by experiments on a double-pulse and three-phase converter. Besides, implementation schemes and calibration approaches for practical applications are discussed. The proposed method has a higher resolution as compared with a traditional <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -state voltage-based IGBT junction temperature monitoring method. Besides, the proposed method reduces the circuit complexity, size, and cost, and it is easy to install. Moreover, the proposed method has a fast response and high resolution, and it does not disturb the normal operation. The proposed method is independent of bond wire degradation of the IGBT module.

ABSTRACTThe insulated gate bipolar transistor (IGBT) is one of the most important power semiconductor devices in power electronics and is also prone to failure. High junction temperature and junction temperature fluctuation of IGBT are the main causes of IGBT module aging failure. The high‐precision monitoring of the junction temperature of the IGBT module is a prerequisite for IGBT life prediction, which is crucial for reducing maintenance costs and improving equipment reliability. Therefore, an IGBT junction temperature estimation method based on long short‐term memory (LSTM) neural network and sliding window estimation model is proposed and applied in practical industrial scenarios. This method uses the operating data of the motor drive device in the actual industrial application scenario as the training and test data set and uses the external operating parameters of the IGBT module to estimate the junction temperature of the IGBT module. Compared with the internal operating parameters of the IGBT module based on switching transient, the external operating parameters are easier to collect and process, and more suitable for practical application scenes. A sliding window estimation model is proposed to estimate the junction temperature of the IGBT module. Compared with the point‐to‐point estimation method, the sliding window estimation method can capture the influence of historical operation data better and has a higher capability of time series data estimation. The IGBT junction temperature estimation of sliding windows is realized by the LSTM neural network, which is more suitable for time series estimation in real industrial scenarios. The experimental results show that the estimation accuracy of the sliding window estimation method is better than that of the point‐to‐point estimation method, and the accuracy of the sliding window estimation method based on LSTM is better than that of the sliding window estimation method based on other machine learning models. It proves that the proposed method can better capture the dynamic process of the system and has higher estimation accuracy.