Active Thermal Management Method for Improving Current Capability of Power Devices under Influence of Random Convection

Abstract

The active thermal management (ATM) method can improve the current capability of power devices safely by utilizing the thermal limit of the device. However, the existing methods are not suitable for power devices affected by random convection. This is because the randomness of convection will lead to the uncertainty of increased current capability, which is unacceptable in most engineering applications. To overcome the shortcomings of existing ATM methods, this paper proposed a novel ATM method for power devices under the influence of random convection. In the proposed method, the short-time current capability of the power device is maximized according to the thermal inertia of the device and maximum load current. The continuous current capability of the power device is determined by a maximum continuous current that satisfies the over-temperature risk constraint of the device. To accurately estimate the maximum continuous current, an uncertainty model is presented for the convective thermal resistance of the power device based on wavelet packet transform and Markov chain. A series of experimental studies are carried out by taking a power MOSFET as an example. The experimental results show that the proposed method can safely improve the output performance of the power device without causing random fluctuations in the current capability.