Junction temperature

About: Junction temperature is a research topic. Over the lifetime, 5058 publications have been published within this topic receiving 58643 citations.

Characterization of the thermal impedance of high–power LED assembly based on innovative printed circuit board technology

Abstract: We present a method of dynamic thermal characterization of an entire test assembly, consisting of high-power Light Emitting Diodes (LED) and a printed circuit board (PCB) by measuring the thermal response on a power-on-step function and describing the thermal impedance with a Foster RC network. For this purpose, we record temporal temperature functions on test assemblies during pulse load experiments under defined initial and boundary conditions (the assemblies were horizontally positioned under free air in a test chamber), establish the LEDs' junction temperature-versus-time functions for known power functions and calibrate the parameters of the Foster RC network. Moreover, we reveal connections between design parameters (conductor layout, thermal via geometry, and PCB material) and the thermal impedance of the assembly. The method allows the user to predict the LED's junction temperature as transient thermal response on an arbitrary pulse load function (as e.g. flashes with different intensity, duration and repetition rate) with low effort.

Junction-temperature measurements in GaN UV light-emitting diodes using the diode forward voltage

Abstract: A theoretical model for the dependence of the diode forward voltage (V/sub f/) on junction temperature (T) is developed. A new expression for dV/sub f//dT is derived that takes into account all relevant contributions to the temperature dependence of the forward voltage including the intrinsic carrier concentration, the bandgap energy, and the effective density of states. Experimental results on the junction temperature of GaN UV LEDs are presented. Excellent agreement between the theoretical and experimental temperature coefficient of the forward voltage (dV/sub f//dT) is found. The experimentally found linear dependence of the junction temperature on forward current is explained by a thermal conduction model. A thermal resistivity of 342.2 K/W is found for the UV LED.

Electric compressor controller

Abstract: An electric compressor controller includes a compressor (11) that compresses refrigerant of an air conditioning system; a motor (12) that drives the compressor; an inverter (13) that selectively control switching elements (TR1-TR6) based on PWM pulse signals to supply drive power to the motor (12) and heats the refrigerant by heat generated due to switching of the switching elements (TR1-TR6) during a heating operation; temperature detectors (134) each detects junction temperature of each of the switching elements; a drive controller (14,131) that supplies the pulse signals to the inverter (13) to control the inverter; and a slope varying unit (133) that variably controls precipitous degree of rising/falling slope waveforms of the pulse signals based on the junction temperature detected by the temperature detectors. According to the electric compressor controller, efficiency for heating refrigerant is improved, so that its own heating ability is improved.

Thermal Performance Evaluation of a 1.7-kV, 450-A SiC-MOSFET Based Modular Three-Phase Power Block With Wide Fundamental Frequency Operations

Abstract: To accelerate wide industry adoption of Silicon Carbide (SiC) based technology, a three-phase two-level inverter based power block is designed with the latest generation high performance 1.7 kV/450 A SiC- mosfet module from General Electric. The designed power block is expected to replace the currently standardized 1.7 kV/450 A Silicon (Si) insulated gate bipolar transistor (IGBT) based three-phase power block. Power converters face thermal challenges when subjected to very low fundamental frequency operations (below 10 Hz). This is particularly relevant in the wind power applications. At low operating fundamental frequencies, the junction temperature of the power device experiences high peak-to-peak ripple, which degrades the reliability of the power modules significantly. This paper presents the thermal performance of the designed power block and draws comparisons with a similar rated Si-IGBT module based power blocks, especially at low output fundamental frequency operations. Key performance indices, including power rating curves at different switching frequencies and power factors; temperature ripple at different fundamental frequencies, are examined. Simulation and experimental results are provided to validate the claims. The results indicate that the SiC- mosfet module based power block can be a promising replacement for the Si-IGBT based power block especially in applications where wide range of fundamental frequency operations are needed.

Comprehensive Assessment of Avalanche Operating Boundary of SiC Planar/Trench MOSFET in Cryogenic Applications

Abstract: The avalanche ruggedness of power devices becomes a crucial issue to ensure the safe operation of the power conversion systems, particularly under the extreme temperature conditions. In this article, the avalanche capability of SiC planar/trench MOSFETs is systematically evaluated and analyzed over the temperature range of 90 to 340 K. Importantly, the essential mechanisms and temperature dependence of avalanche failure under cryogenic conditions are further explored by combining many analysis methods such as TCAD simulations, the unclamped inductive switching characterizations, and the transient junction temperature prediction. The highest avalanche energy density of 171.24 mJ/mm2 at 90K indicates the great application potential of SiC planner mosfet in cryogenic electronics. Moreover, the safe avalanche operation boundary (AOB) model is established over the cryogenic temperature range. The relevant analysis method and AOB model can be used to accurately evaluate and quantitatively predict the avalanche capability of SiC planar/trench mosfet s for the cryogenic converter design.