Estimation of heat transfer coefficient temperature dependence from cooling curve measurements
20 Aug 2015-pp 422-425
TL;DR: This paper discusses on the practical example of a power diode attached to a heat sink the problem of heat transfer coefficient temperature dependence and its importance for free convection cooled electronic systems.
Abstract: This paper discusses on the practical example of a power diode attached to a heat sink the problem of heat transfer coefficient temperature dependence and its importance for free convection cooled electronic systems. The average values of this coefficient are estimated from multiple measurements of device cooling curves performed for different device heating currents. These values are used then for transient simulations of the device with compact thermal models.
Citations
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TL;DR: The experiments carried out for a natural convection cooled power device with a heat sink showed that the temperature dependence of the heat transfer coefficient results in the appearance of a characteristic hump in this curve.
13 citations
Cites background or methods from "Estimation of heat transfer coeffic..."
...Consequently, as discussed in [12], the time constant spectra presented in the figuremight be used to generate for this system a compact thermalmodel in the form of four stage RC Foster ladder by dividing the curves in the location of minima indicated in the figure by the black arrows....
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...Based on the results published in [8,12], for temperatures below 400 K in the case of radiation and natural convection cooling the experimentally determined values of α are in the range of 0....
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TL;DR: In this paper, the authors presented improvements introduced in a behavioural electrothermal model of silicon carbide merged PIN-Schottky (SiC MPS) diodes, aimed at a better representation of device characteristics for a more accurate prediction of power dissipation.
Abstract: This study presents improvements introduced in a behavioural electro-thermal model of silicon carbide merged PIN-Schottky (SiC MPS) diodes, aimed at a better representation of device characteristics for a more accurate prediction of power dissipation. In the electrical domain, the junction capacitance model has been thoroughly validated with a new parameter extraction procedure, yielding realistic values of the turn-off charge as well as current and voltage waveforms for various operating conditions, which is crucial for dynamic loss evaluation. The validity of the thermal sub-model has been extended by reflecting the temperature dependence of thermal conductivity. As a result, temperature evolution on both the long and short time scales is properly computed, providing correct on-state voltage drop and on-state power loss results. Device behaviour with a heat sink attached is also correctly simulated.
10 citations
18 Apr 2016
TL;DR: In this paper, the average value of the convective heat transfer coefficient in the case of a free convection cooled power device with a heat sink was investigated and an empirical formula was proposed allowing the determination of the average heat transfer coefficients value in function of the heat sink surface temperature rise.
Abstract: The investigations presented in this paper illustrate the problem of modelling the average value of the convective heat transfer coefficient in the case of a free convection cooled power device with a heat sink. The total junction-to-ambient thermal resistance is dominated then by its component reflecting the heat exchange with the ambient at outer surfaces of the heat sink. Therefore, the proper modelling of this physical phenomenon is crucial for the accurate prediction of device junction temperature. Based on obtained temperature measurement results an empirical formula is proposed allowing the determination of the average heat transfer coefficient value in function of the heat sink surface temperature rise.
4 citations
23 Jun 2016
TL;DR: The proposed empirical formulas are fitted to the results of temperature measurements taken for a power diode attached to a heat sink, and these empirical relations were used subsequently in device simulation with compact thermal models.
Abstract: This paper discusses, based on a practical example, the problem of estimating the average radiation and convection heat transfer coefficient value in thermal models of electronic systems. The proposed empirical formulas are fitted to the results of temperature measurements taken for a power diode attached to a heat sink. The measurements were repeated in natural and forced air cooling conditions. These empirical relations were used subsequently in device simulation with compact thermal models.
3 citations
01 Sep 2016
TL;DR: In this paper, the authors discuss the problem of heat transfer coefficient variation in air cooled hybrid circuits, based on a practical example of a circuit containing a bipolar transistor heat source, its temperature is measured using the base-emitter junction.
Abstract: This paper discusses the problem of heat transfer coefficient variation in air cooled hybrid circuits. The investigations are based on a practical example of a circuit containing a bipolar transistor heat source. Its temperature is measured using the base-emitter junction. Additionally, infrared measurements of circuit surface temperature are taken. The measurements are carried out in a wind tunnel for different values of dissipated power and with variable cooling air speed. The measurement results are analysed allowing the assessment of heat transfer coefficient variation with surface temperature and cooling air velocity. Based on the analyses, compact thermal models are generated for the circuit allowing fast and accurate simulation of circuit temperature in various cooling conditions.
1 citations
References
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TL;DR: In this paper, a deconvolution operation performed in the logarithmic time domain gives the "timeconstant spectrum" of the chip-case-ambient thermal structure.
Abstract: A new method has been developed in order to identify the thermal environment of a semiconductor device chip. The identification algorithm operates on the thermal transient response of the device recorded during a one-shot pulse measurement. A deconvolution operation performed in the logarithmic time domain gives the “time-constant spectrum” of the chip-case-ambient thermal structure. A further transformation leads to the “structure-function” that is the cross-sectional area of the heat conducting materials vs thermal resistance (related to the heat source). The structure function has a good and quantitatively evaluable correspondence to the physical chip environment and heat conducting structure. Separating the different regions of the heat-flow path (corresponding to the chip, bond, header, case) as well as the detection of eventual heat-transport irregularities (mounting errors) is possible.
419 citations
"Estimation of heat transfer coeffic..." refers methods in this paper
...For electronic systems the values of these thermal quantities describing the entire heat flow path from the regions where heat is generated to the ambient can be identified employing the Network Identification by Deconvolution (NID) method proposed in [2]....
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TL;DR: The presented experimental results demonstrate that the nonlinearities due to the temperature dependence of thermal model parameters might have important influence on the results, especially when still air cooling is applied.
25 citations
"Estimation of heat transfer coeffic..." refers methods in this paper
...The models were identified employing the technique presented in [5] by segmenting the time constant spectra at the locations of their local minima into four different sections; below 7 ms, 7÷70 ms, 70 ms÷9 s and over 9 s....
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