Abstract
The thermal management of magnetic components for power electronics is crucial to ensure their reliability. However, conventional thermal models for magnetic components are known to have either poor accuracy or excessive complexity. Contrary to these models, the use of Thermal Resistance Matrices is proposed in this paper instead, which combine both accuracy and simplicity. They are usually used to characterize semiconductor devices, but not for magnetic components. The guidelines to apply Thermal Resistance Matrices for magnetic components are discussed in detail. The accuracy of this model is validated by 3D FEA simulations and experimental results, showing an absolute error lower than 5 ∘C and a relative error between −6.4% and 3.9%, which is outstanding compared to the carried-out literature review.
Highlights
The constantly increasing interest in miniaturising power components makes crucial a proper characterisation of the thermal behaviour of magnetic components, which are one of the limiting factors [1,2].The simplest and most widely used approach is the empirical Equation (1) from [3], or other simple equations like the one proposed in [4]
Since the voltage is imposed by the RF amplifier, a variable resistor (Rdamp in series for the inductor; Rload in the secondary of the transformer) is placed in order to adjust the demanded current by the circuit
A methodology to extract thermal resistance matrices from 3D Finite Element Analysis thermal simulations is developed in this paper, reducing the computational requirements while ensuring high accuracy
Summary
The constantly increasing interest in miniaturising power components makes crucial a proper characterisation of the thermal behaviour of magnetic components, which are one of the limiting factors [1,2]. Another recurrent approach is to use thermal networks for magnetic components [5,6,7] (or for semiconductors [8]), which shows better results than Equation (1) Their accuracy is associated with their granularity, to their complexity, which is still limited since a constant film coefficient is commonly assumed. This approach offers several advantages compared to the previous ones This model consists of a simple coefficients matrix of dimension NxN, where N is the number of characterised objects or parts (for example, the core, the windings and the bobbin). The temperature rise of an E25/13/7 transformer predicted by 3D Finite Element Analysis (FEA) simulations for a range of winding power losses with constant core losses Passive parts: a coil former or the pin connectors to a PCB do not have power losses, but their temperature depends on the heat flux coming from surrounding objects, which could be critical if the maximum ratings are exceeded
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