AY 2018 19 Test 4 Numerical part with solutions

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·. 1 Problem 2. A DC/DC buck converter is based on the discrete IGBT and diode whose ratings are reported below. Each power semiconductor device is mounted on its own heat sink. Calculate the minimum heat sinks thermal resistanc e that allow to keep the temperature of the junctions below 130 •c in the following operating conditions: ► Input voltage: V; n = 370 V DC. ► Output voltage: V out = 190 V (neglect the voltage drop across the output filter). ► Output power: P out = 6.5 kW. ► Switching frequency: fsw = 13 kHz. ► Gate signal range: VGE = O - 15 V. ► Ambient temperature Tam b = 30 ° C. IGBT Parameter Characterlstic IGBT thermal resistance, junction - case Diade thermal resistance, junction - case Thermal resistance, junction - ambient IGBT Characterlstlc Turn-on delay time Rise time PG-T0247-3 Turn-off delay time Fall time Turn-on energy Turn-off energy Total switching energy DIODE Parameter 1 2 Thermal resistance, junction-case Thermal resistance, junction- ambient (negligible recovery losses) 120A et:: 90A et:: o t.) 60A o t.) � 30A OA ov 1V 2V 3V VcE, COLLECTOR-EMITTER VOLTAGE 3 Symbol Condltlons RthJC RthJCD RlhJA la1onJ T1=25 °C, - t, Vcc =400V, /c =7 SA, -VGe=0/1 SV, la1offJ rG=S0, L 0=100nH, - t, c. =39pF Eon La, Ca from Fig. E -Energy losses include Eorr "tail'" and diode reverse - E,, recovery. - l5ymbol Values Unii Mln. Typ. Max. RlhJC - 0.6 0.8 RlhJA 62 K/W - - BO 70 - 60 - --. - - =-5-5."_C---,---,--,. I ì---..1 --l 25'C -� i',, 50 � 40 � 30 - 20 10 o o 2 V,[VJ Max. Value Unlt 0.35 K/W 0.6 40 33 - ns 36 - 330 - 35 - 2.0 - mJ 2.5 - 4.5 - NotefTest Condltlon leaded