Efficient Microchannel Cooling of Multiple Power Devices With Compact Flow Distribution for High Power-Density Converters

Abstract

In this work, we describe a new approach for compact and energy-efficient cooling of converters where multiple miniaturized microfluidic cold-plates are attached to transistors providing local heat extraction. The high pressure drop associated with microchannels was minimized by connecting these cold-plates in parallel using a compact 3D-printed flow distribution manifold. We present the modeling, design, fabrication and experimental evaluation of this microfluidic cooling system and provide a design strategy for achieving energy-efficient cooling with minimized pumping power. An integrated cooling system is experimentally demonstrated on a 2.5 kW switched capacitor DC-DC converter, cooling down 20 GaN transistors. A thermal resistance of 0.2 K/W was measured at a flow rate of 1.2 ml/s and a pressure drop of 20 mbar, enabling the cooling of a total of 300 W of losses in the converter using several mW of pumping power, which can be realized with small micropumps. Experimental results show a 10fold increase in power density compared to conventional cooling, potentially up to 30 kW/l. This proposed cooling approach offers a new way of co-engineering the cooling and the electronics together to achieve more compact and efficient power converters.

A Generalized Phase-Shift PWM Extension for Improved Natural and Active Balancing of Flying Capacitor Multilevel Inverters

“…Now the matrix that incorporates all independent switching states, SI(N), can be derived by concatenating matrices SPS(N) and SSW(N), leading to a (N-2) x (N-1) matrix. An example of the SI( 7) is presented in (8).…”

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