Junction temperature

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

A new method to extract HBT thermal resistance and its temperature and power dependence

Abstract: This paper introduces a new technique for the measurement of the thermal resistance of HBTs. The method is very simple, because it requires only standard dc I/sub C/-V/sub CE/ measurements taken at different baseplate temperatures, but it is able to account for the dependence of the thermal resistance on both the baseplate temperature and the dissipated power (under the simplifying assumption that the thermal resistance increases linearly with the dissipated power). We have obtained and shown consistent results extracted from devices with an emitter area ranging from 90 /spl mu/m/sup 2/ (1 finger) to 1080 /spl mu/m/sup 2/ (12 fingers). The thermal-resistance values extracted with a standard and well-known technique are seen to fall inside the range of our results. We have also applied an alternative method that assumes a linear dependence between thermal resistance and junction temperature, and we have shown that both models lead to similar results, which points to the consistency and robustness of our extraction technique.

Reduced junction temperature control during low-voltage ride-through for single-phase photovoltaic inverters

Abstract: Future photovoltaic (PV) inverters are expected to comply with more stringent grid codes and reliability requirements, especially when a high penetration degree is reached, and also to lower the cost of energy. A junction temperature control concept is proposed in this study for the switching devices in a single-phase PV inverter in order to reduce the junction temperature stress, and thus to achieve improved reliability of a PV inverter. The thermal stresses of the switching devices are analysed during low-voltage ride-through operation with different levels of reactive power injection, allowing an optimal design of the proposed control scheme with controlled mean junction temperature and reduced junction temperature swings. The effectiveness of the control method in terms of both thermal performance and electrical performance is validated by the simulations and experiments, respectively. Both test results show that single-phase PV inverters with the proposed control approach not only can support the grid voltage recovery in low-voltage ride-through operation but also can improve the overall reliability with a reduced junction temperature.

Estimation and measurement of junction temperatures in a three-level voltage source converter

Abstract: The design of a power converter must guarantee that the operating junction temperatures v/sub j/ of all devices do not exceed their limits under all specified operating conditions. Usually, this is ensured by a simulative or analytical junction temperature estimation based on simple electrical and thermal models and semiconductor datasheet values. This paper discusses the difficulties and quantifies the limitations of this approach on the example of a three-level NPC VSC with IGBTs. The calculations are compared to the results of direct junction temperature measurements with an infrared camera. The paper also provides the experimental proof for the unequal loss and junction temperature distribution in the three-level NPC VSC.

An IGBT Driver Concept with Integrated Real-Time Junction Temperature Measurement

Abstract: This paper presents an IGBT driver concept that is suitable to measure the junction temperature of a conventional IGBT power module during inverter operation. Thereby the temperature of the internal gate resistor is determined by superimposing the negative gate voltage with a highfrequency, sinusoidal identification signal. New aspects are the parallel feeding in of the identification voltage into an existing IGBT driver circuit and the generation of an ADC compatible sensor voltage using a fast rectifier and an offset compensation. The driver concept is easy to realize and enables junction temperature measurement without affecting the IGBT switching behavior and the regular inverter operation. On the basis of the theoretical backgrounds this paper presents the subsystems of the driver concept and discusses its technical feasibility. First measurement results found the remaining noise of the temperature measurement to be smaller than +- 1 Celsius. In the introduction existing approaches to measure the junction temperature are reviewed and valued regarding their usability during inverter operation.

Accelerated aging test of Ga1−xAlxAs DH lasers

Abstract: An accelerated aging test is performed at temperatures of 70, 110, and 140 °C to estimate the activation energy Samples are operated in the LED mode at high temperatures of 110 and 140 °C At 70 °C samples are operated in lasing mode of optical output 027 mW/μm The laser lifetime is defined to be a time at which the cw threshold current measured at a standard temperature 25 °C reaches 15 times the initial value The activation energy 074 eV is obtained It is shown that the degradation does not depend on the optical output power below the power level of 03 mW/μm and that the activation energy is indifferent to the operation mode, LED mode, or lasing mode, at a low power level The use of the LED mode operation and the definition of the laser lifetime in terms of the characteristics at low standard temperature enable one to perform the accelerated aging test at high temperatures above 110 °C where cw operation is almost impossible The reliability is examined at 70 °C using 50 samples and an average laser lifetime is obtained The application of the activation energy gives the average laser lifetime at the junction temperature of 30 °C to be 3×105 h