| Higher switching frequency,more compact,low-weight,and high density OBCM(On Board Charger Module)is now becoming a technical trend.Heat dissipation of semiconductors rise eventually,which is a challenge caused by the critical outside cooling boundary.As a result,liquid-cooled cold-plate is now widely used in OBCM.So getting to know how to evaluate the temperature-rise from junction of semi-conductors to coolant is becoming important for designing a reliable product.This paper summarizes how to evaluate the junction temperature of vertical-mounted device based on calculation,simulation and testing in a liquid cooling application,and the effective solutions on how to evaluate the pressure drop from coolant inlet to outlet,including how to optimize the coolant passage to purge air bubbles during coolant filling process on vehicle side.Considering real auto application,thermal validation solutions are summarized in this paper as well.Firstly,this paper proposes a new method of evaluating thermally conductive interface material through the impedance curve provided by supplier which disclose the relation of mounting pressure and thermal impedance,and releases a two-step simulation solution via Flotherm XT to predict temperature of semi-conductors as well as the summary of thermally conductive interface materials for OBCM.Secondly,this paper summarizes a solution on how to calculate the pressure drop of cold-plate,which can be compared to the results calculated by simulation and tests.During cold-plate evaluation,simulation and tests are combined together for working out solutions to improve the coolant path to purge the air bubbles.Velocity boundary layer separation is regarded as a key factor that could contribute to trap air in OBCM.Two solutions are proposed to avoid the trapped air bubbles in this paper.Finally,this paper summarizes thermal validations,such as high temperature pre-aging,powered thermal cycling,thermal shock,salt,water,dust,shock & vibration. |
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