Showing papers on "Junction temperature published in 2015"

In Situ Diagnostics and Prognostics of Solder Fatigue in IGBT Modules for Electric Vehicle Drives

Abstract: 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.

Junction Temperature Measurement of IGBTs Using Short-Circuit Current as a Temperature-Sensitive Electrical Parameter for Converter Prototype Evaluation

Abstract: This paper proposes a method to measure the junction temperatures of insulated-gate bipolar transistors (IGBTs) during the converter operation for prototype evaluation. The IGBT short-circuit current is employed as the temperature-sensitive electrical parameter (TSEP). The calibration experiments show that the short-circuit current has an adequate temperature sensitivity of 0.35 ${\rm A}/^{\circ}\hbox{C} $ . The parameter also has good selectivity and linearity, which makes it suitable to be used as a TSEP. Test circuit and hardware design are proposed for the IGBT junction temperature measurement in various power electronics dc–dc and ac–dc converter applications. By connecting a temperature measurement unit to the converter and giving a short-circuit pulse during the converter operation, the short-circuit current is measured, and the IGBT junction temperature can be derived from the calibration curve. The proposed temperature measurement method is a valuable tool for prototype evaluation and avoids the unnecessary safety margin regarding device operating temperatures, which is significant particularly for high-temperature/high-density converter applications.

High Junction Temperature and Low Parasitic Inductance Power Module Technology for Compact Power Conversion Systems

Abstract: Advanced power module technology capable of taking advantage of the superior features of next-generation power devices, such as those fabricated with SiC and GaN, must be developed to create much more compact and cost-effective power conversion systems. New power modules based on such technology are especially required to allow fast switching of power devices in the extended junction temperature range. This paper describes the major technical challenges involved in sufficiently improving the thermal stress reliability of the critical package systems in SiC power modules and in markedly reducing internal parasitic inductance. Thermal stress reliabilities of the die attachment system, wire bonding system, and encapsulant system are successfully improved, all of which are shown to be able to achieve common life targets: 1) 3000 h for a storage test at 250 °C and 2) 3000 cycles for thermal cycling between −40 °C and 250 °C. A novel phase-leg power module capable of substantially reducing the loop inductance along the principal current tracks is proposed and fabricated by applying SiC-JFETs, SiC-Schottky barrier diodes, and the abovementioned reliable thermal stress package systems. Double pulse switching testing of the module reveals smaller drain-source voltage spikes and ringing even in turn-ON and turn-OFF transients at very high slew rates of current and voltage. Finally, a 0.34 L forced-air-cooled dc 600 V input ac 50 Hz 400 V 25 kW output three-phase SiC inverter is fabricated using three-phase leg modules and its operation is demonstrated at high-power levels.

A High Temperature Silicon Carbide mosfet Power Module With Integrated Silicon-On-Insulator-Based Gate Drive

Abstract: This paper presents a board-level integrated silicon carbide (SiC) mosfet power module for high temperature and high power density application. Specifically, a silicon-on-insulator (SOI)-based gate driver capable of operating at 200 °C ambient temperature is designed and fabricated. The sourcing and sinking current capability of the gate driver are tested under various ambient temperatures. Also, a 1200 V/100 A SiC mosfet phase-leg power module is developed utilizing high temperature packaging technologies. The static characteristics, switching performance, and short-circuit behavior of the fabricated power module are fully evaluated at different temperatures. Moreover, a buck converter prototype composed of the SOI gate driver and SiC power module is built for high temperature continuous operation. The converter is operated at different switching frequencies up to 100 kHz, with its junction temperature monitored by a thermosensitive electrical parameter and compared with thermal simulation results. The experimental results from the continuous operation demonstrate the high temperature capability of the power module at a junction temperature greater than 225 °C.

Liquid Jet Impingement Cooling of a Silicon Carbide Power Conversion Module for Vehicle Applications

Abstract: Thermal management of power electronics is an extremely challenging problem in the harsh environment of military hybrid vehicles, where the local air and liquid coolant's temperature exceed 100 °C under regular operating conditions This paper presents the development work of a high heat flux, jet impingement-cooled heat exchanger for a 600-V/50-A silicon carbide (SiC) power module (rated at 175 °C device junction temperature), used for bidirectional power conversion between a 28-V battery and a 300-V dc bus A total of 50 volume% mixture of water–ethylene glycol (WEG) coolant at 100 °C inlet temperature is the only available coolant An array of WEG coolant microjets impinges on the base plate of the SiC module The jet impingement cooling system has been optimized by experimental studies on a surrogate module, along with a high-fidelity computational model, to accurately estimate the SiC device junction temperature in relevant operating conditions Results indicate that at the design heat load of 151 W (worst-case scenario), the SiC device junction temperature is reduced from 290 °C with commercial-off-the-shelf (COTS) cold plate cooling and 215 °C with COTS microchannel heat exchanger cooling, to 169 °C with a jet impingement-cooled heat exchanger, using the same flow rate

A Real-Time Thermal Model for Monitoring of Power Semiconductor Devices

Abstract: A resistance-capacitance $(RC) $ thermal network with temperature-dependent thermal conductivities and heat capacitances is used to calculate the junction temperature of insulated-gate bipolar-transistor modules using a device model realized in Simulink. The collector current $I_{C}$ , collector–emitter voltage $V_{CE}$ , and the case temperature $T_{C} $ measured during the cycling are used as input parameters of the proposed model. The proposed model is easier to implement compared with the thermosensitive electrical parameter (TSEP) method, and it is compared with an $RC$ network with constant thermal conductivity and heat capacitance model and experimentally verified by using a TSEP method. The results of the proposed model show an improvement of the accuracy for determining the junction temperature compared with the model with constant thermal conductivity and heat capacitance.

Active thermal control of IGBT power electronic converters

Abstract: Thermal cycling is one of the main sources of aging and failures in power electronics. A possibility to reduce the stress to semiconductors is to control the amount of losses that occur in the device during operation. This work presents an active thermal controller that aims at reducing the junction temperature variations in the case of variable power profile. The switching frequency of the converter is the parameter that is affected by the active thermal control, while the operation of the converter remains unchanged. The novelty of the approach is that the switching frequency variation is exploited to prevent excessive cooling down of the semiconductor during a power reduction. A thermal model is used to estimate the losses, so the prior knowledge of the mission profile is not needed. The results of the proposed solution are validated with an experimental prototype and a wide-bandwidth temperature measurement system directly applied to the semiconductor chip. Finally, the impacts of the controller on the module's lifetime is estimated.

Rapid Degradation of Mid-Power White-Light LEDs in Saturated Moisture Conditions

Abstract: Serious silicone carbonization has been reported in mid-power white-light LEDs during highly accelerated temperature and humidity stress test, although the junction temperature of the LED chip is much lower than the critical temperature of silicone carbonization (300 °C). This paper presents a comprehensive investigation, through which the effects of Joule heating and phosphor self-heating have been eliminated as main failure mechanisms. As a result, the over-absorption of blue lights by silicone bulk is considered as the root cause for silicone carbonization. This is mainly due to the scattering effect of water particles inside the silicone materials, which can increase the silicone temperature significantly. Furthermore, finite-element thermal simulation has also been performed, confirming the validity of the failure mechanism.

Thermally enhanced blue light-emitting diode

Abstract: We investigate thermoelectric pumping in wide-bandgap GaN based light-emitting diodes (LEDs) to take advantage of high junction temperature rather than avoiding the problem of temperature-induced efficiency droop through external cooling. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with nearly no reduction in the wall-plug efficiency (i.e., electrical-optical energy conversion efficiency) at bias V<ℏω/q. The LED is shown to work in a mode similar to a thermodynamic heat engine operating with charged carriers pumped into the active region by a combination of electrical work and Peltier heat (phonons) drawn from the lattice. In this optimal operating regime at 615 K, the LED injection current (3.26 A/cm2) is of similar magnitude to the operating point of common high power GaN based LEDs (5–35 A/cm2). This result suggests the possibility of removing bulky heat sinks in curre...

Thermally enhanced blue light-emitting diode

Abstract: We investigate thermoelectric pumping in wide-bandgap GaN based light-emitting diodes (LEDs) to take advantage of high junction temperature rather than avoiding the problem of temperature-induced efficiency droop through external cooling. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with nearly no reduction in the wall-plug efficiency (i.e., electrical-optical energy conversion efficiency) at bias V<ℏω/q. The LED is shown to work in a mode similar to a thermodynamic heat engine operating with charged carriers pumped into the active region by a combination of electrical work and Peltier heat (phonons) drawn from the lattice. In this optimal operating regime at 615 K, the LED injection current (3.26 A/cm2) is of similar magnitude to the operating point of common high power GaN based LEDs (5–35 A/cm2). This result suggests the possibility of removing bulky heat sinks in curre...

An Online Frequency-Domain Junction Temperature Estimation Method for IGBT Modules

Abstract: This letter proposes a new frequency-domain thermal model for online junction temperature estimation of insulated-gate bipolar transistor (IGBT) modules. The proposed model characterizes the thermal behavior of an IGBT module by a linear time-invariant (LTI) system, whose frequency response is obtained by applying the fast Fourier transform (FFT) to the time derivative of the transient thermal impedance from junction to a reference position of the IGBT module. The junction temperature of the IGBT is then estimated using the frequency responses of the LTI system and the heat sources of the IGBT module. Simulation results show that the proposed method is computationally efficient for an accurate online junction temperature estimation of IGBT modules in both steady-state and transient loading conditions.

Evaluating different implementations of online junction temperature sensing for switching power semiconductors

Abstract: Switching power semiconductor online junction temperature (T j ) sensing is essential for device switching performance evaluation, device switching control, and device lifetime optimization. The contribution of this paper is a detailed evaluation of implementation issues (including circuit invasiveness, hardware integration, signal processing, and so forth) of different online T j sensing methods. This paper includes T j sensing methods based on device power dissipation, T j sensing methods based on the “diode-on-die technology”, T j sensing methods based on device on-state analysis, and T j sensing methods based on device switching transients. Advantages and limits of these methods are also provided.

High temperature dependence of thermal transport in graphene foam

Abstract: In contrast to the decreased thermal property of carbon materials with temperature according to the Umklapp phonon scattering theory, highly porous free-standing graphene foam (GF) exhibits an abnormal characteristic that its thermal property increases with temperature above room temperature. In this work, the temperature dependence of thermal properties of free-standing GF is investigated by using the transient electro-thermal technique. Significant increase for thermal conductivity and thermal diffusivity from ∼0.3 to 1.5 W m(-1) K(-1) and ∼4 × 10(-5) to ∼2 × 10(-4) m(2) s(-1) respectively is observed with temperature from 310 K to 440 K for three GF samples. The quantitative analysis based on a physical model for porous media of Schuetz confirms that the thermal conductance across graphene contacts rather than the heat conductance inside graphene dominates thermal transport of our GFs. The thermal expansion effect at an elevated temperature makes the highly porous structure much tighter is responsible for the reduction in thermal contact resistance. Besides, the radiation heat exchange inside the pores of GFs improves the thermal transport at high temperatures. Since free-standing GF has great potential for being used as supercapacitor and battery electrode where the working temperature is always above room temperature, this finding is beneficial for thermal design of GF-based energy applications.

Investigation of the dynamic on-state resistance of 600V normally-off and normally-on GaN HEMTs

Abstract: In this paper, current collapse phenomena and thermal effects in newly developed normally-off and normally-on GaN HEMTs are investigated. The experimental results show that a high off-state voltage and high switched drain current at high junction temperature cause an increase of the on-state resistance. During switching from 50 kHz to 400 kHz, an increase of R DSON is observed for both types of GaN devices. It is evident that the number of switching transients significantly influences the increase of the on-state resistance, suggesting that this increase is due to a current collapse in GaN HEMTs. A detailed comparison of the evaluated R DSON between GaN transistors and the newest high-speed CoolMOS-C7 transistor is presented.

Electro-thermal simulation of 1200 V 4H-SiC MOSFET short-circuit SOA †

Abstract: The purpose of this paper is to introduce a dynamic electro-thermal simulation and analysis approach for device design and short-circuit safe-operating-area (SOA) characterization using a physics-based electro-thermal Saber®∗ model. Model parameter extraction, simulation, and validation results are given for several commercially available 4H-silicon carbide (SiC) power MOSFETs with a voltage rating of 1200 V and with current ratings of 31.6 A and 42 A. The electro-thermal model and simulations are used to analyze the short-circuit SOA including the measured failure time (t failure ) and simulated device internal junction temperature (T j ) at failure for different gate voltages (V GS ) and drain voltages (V DS ).

Performance Prediction of Commercial Thermoelectric Cooler Modules using the Effective Material Properties

Abstract: This work examines the validity of formulating the effective thermoelectric material properties as a way to predict thermoelectric module performance The three maximum parameters (temperature difference, current, and cooling power) of a thermoelectric cooler were formulated on the basis of the hot junction temperature Then, the effective material properties (Seebeck coefficient, electrical resistance, and thermal conductivity) were defined in terms of the three maximum parameters that were taken from either a commercial thermoelectric cooler module or the measurements It is demonstrated that the simple standard equation with the effective material properties predicts well the performance curves of the four selected commercial products Normalized parameters over the maximum parameters were also formulated to present the characteristics of the thermoelectric coolers along with the normalized charts The normalized charts would be universal for a given thermoelectric material

A simple approach on junction temperature estimation for SiC MOSFET dynamic operation within safe operating area

Abstract: A simple approach of sensorless junction temperature estimation is proposed for SiC power MOSFET devices. The junction temperature is derived in real-time by finding the instantaneous on-state resistance which is temperature sensitive and can be used as an indicator for device thermal estimation. Based on the scheme, a high-speed circuit is designed to quickly detect the on-state resistance and estimate the corresponding internal temperature. This circuit is able to provide fast thermal estimation within microseconds without using any temperature sensors. The scheme is tested on the SiC power MOSFET C2M0080120D with the laboratory hardware measurement results verified.

Sensing IGBT junction temperature using gate drive output transient properties

Abstract: Insulated Gate Bipolar Transistor (IGBT) junction temperature sensing is normally achieved with a temperature detector. To optimize accuracy, the temperature detectors are placed very close to the power semiconductor chip or embedded on the power semiconductor die. This is inconvenient for power integration and requires further consideration for high voltage, high current, EMI protection, and the detector's thermal-mechanical stress. This paper presents a non-invasive method that integrates junction temperature sensing into the IGBT gate drive and enables high bandwidth sensing. In order to demonstrate the IGBT junction temperature sensing, an IGBT power module is implemented in an H-bridge, and driven by four push-pull type gate drives. The gate drive switching transient properties are used for IGBT junction temperature estimation. The “gate drive-IGBT” switching properties are modeled to explain the junction-temperature-dependent gate drive output dynamics. A hardware implementation for IGBT junction temperature extraction is provided. Experimental results are compared with circuit Spice model simulation.

Electro-Thermal Model of Power Semiconductors Dedicated for Both Case and Junction Temperature Estimation

Abstract: The thermal model for power semiconductors devices from junction to ambient can be modeled by a series thermal resistance R th and capacitance C th networks [1, 2, 3].

Junction Temperature Measurement during Inverter Operation using a TJ-IGBT-Driver

Abstract: The junction temperature of an IGBT power module is a key parameter for its optimal operation and reliability. In recent years different sensor systems were presented for real-time TJmeasurement, but none of these solutions could prove its functionality during the real inverter operation. For the first time this paper presents an IGBT gate driver with integrated real-time TJ-measurement and investigates its properties within a working voltage source inverter. The measurement is based on the on-chip internal gate resistor RGi, whose temperature is determined by superimposing the negative gate voltage with a high-frequency identification signal. Therefore the driver consists of a small control unit that manages the entire identification process during the regular switching operation of the IGBT and calculates its junction temperature using a pre-programmed reference sensor curve. Within an automatic one-point calibration at room temperature a certain power modules can be adjusted to this sensor curve. To demonstrate the functionality of the TJ-measurement during inverter operation the driver is integrated into one phase of a voltage source inverter. The junction temperature variations that can be measured at low-frequency phase currents and during the emulation of different load-profiles show very good agreement with the temperature that is measured with an IRcamera. Thereby the so-called TJ-IGBT-Driver offers a very good temperature and time resolution of 1 K and 2.5 ms. In summary, this paper shows a working sensor system that allows real-time junction temperature measurement of conventional IGBT power modules with very good sensor properties and in a way that is suitable for series production.