Power Loss Calculation and Thermal Modelling for a Three Phase ...

Z. Zhou et al: Loss Calculation and Thermal Modelling for 3 Phase Inverter...E ( k) = f ( i ( k), T ( k))(4)sw −on sw −on c jE ( k) = f ( i ( k), T ( k))(5)sw −off sw −off c jThe total switching loss is calculated byE ( k) = E ( k) + E ( k)(6)sw sw −on sw −offand represented asEsw( k )= fsw ( ic ( k), Tj( k))(7)where, k denotes the k th PWM switching pluse. The measured total IGBTswitching energy losses against collect current and junction temperature isshown in Figure 2. It can be seen that the total switching energy loss increaseswith increase of collect current and junction temperature, and can be consideredas a function of the collect current and junction temperature The averageswitching power loss of a switching cycle is then calculated by1P ( k) = E ( k)(8)sw _ ave swTswIf the dc link voltage is changed, the the switching losse characteristics willvary to reflect this change. Adding Eq. (3) and (8), the average power lossP over each switching cycle is calculated byave _ lossP ( k) = P ( k) + P ( k)(9)ave _ loss sw _ ave cond _ ave3. PWM AND DEVICE CURRENT RECONSTRUCTION FOR POWERLOSSES CALCULATIONThe simulation in Figure 3 gives the effective motor voltages and currents,which are continuous quantities (rather than the actual PWM switchingwaveforms) and cannot directly be used for power losses calculation.Therefore, a PWM reconstruction technique is proposed for the power lossessimulation. By using PWM reconstruction technique, device current and the ontimeof device can be mathematically reconstructed for power lossescalculation. Figure 3 shows the block diagram of the PWM and device currentreconstruction.where,mV andmI are the effective motor terminal voltage and current vectors.The mathematical method to reconstruct the PWM signals will depend on theactual PWM strategy applied. Figure 4 shows a three-phase PWM invertercircuit.36

Z. Zhou et al: Loss Calculation and Thermal Modelling for 3 Phase Inverter...to describe the heat-source terms for a thermal solver, this allows electrothermalperformance of the inverter to be predicted over long periods of realtime. This simulation methodology brings together accurate models of theelectrical systems performance, state of the art-device compact models and arealistic simulation of the thermal performance in a useable period of CPUtime.10050Torque (Nm)0-50-1000 100 200 300 400 500 60040003000Speed (rpm)2000100000 100 200 300 400 500 600Time (second)Figure 16: Motor torque (Nm) and speed (rpm).300Motor phase currents (A)2001000-100-200-3000 100 200 300 400 500 600150Motor phase voltages (V)100500-50-100-1500 100 200 300 400 500 600Time (second)Figure 17: Motor stator three phase currents and voltages.44

J. Electrical Systems 1-4 (2005): 33-46Figure 18: power losses of IGBT (W).Figure 19: Junction temperature of IGBT ( o C).45

Z. Zhou et al: Loss Calculation and Thermal Modelling for 3 Phase Inverter...AcknowledgmentThe authors would like to thank Toyota Motor Corporation for their financialsupport and technical advice.REFERENCES[1] M. Ishiko, M. Usui, T. Ohuchi and M. Shirai, Design Concept for Wire- BondingReliability Improvement by Optimizing Position in Power Devices, ISPS’04 7 thInternational Conference on Power Semiconductors, Prague, 31 August – 3September 2004, pp 39 44, 2004.[2] T. Kojima, Y. Yamada, M. Ciappa, M. Chiavarini and W. Fichtner, A NovelElectro-thermal Simulation Approach of Power IGBT modules for automotivetraction applications, Proceeding of 2004 international symposium on powersemiconductor devices & ICs, Kitakyushu, 2004.[3] H. A. Mantooth and A. R. Hefner, Electrothermal Simulation of an IGBT PWMinverter, IEEE Transaction on Power Electronics, vol. 12, no.3, May 1997.[4] R. Hefner and D. L. Blackburn, Thermal component models for electro-thermalnetwork simulation, IEEE Transactions on Components Package. Manufacture.Technology, vol. 17, p. 413, 1994.[5] A. D. Rajapakse, A. M. Gole, and P. L. Wilson, Electromagnetic TransientSimulation Models for Accurate Representation of Switching Losses and ThermalPerformance in Power Electronic Systems, IEEE Transactions on PowerDelivery, vol.20, no.1, pp 319-327, 2005.[6] D. Xu, H. Lu, L. Hang, S. Azuma, M. Kimata and R. Uchida, Power Loss andJunction Temperature Analysis of Power Semiconductor Devices, IEEETransaction on Industry Applications, Vol..38, No.5, pp, 1426-1431,September/October 2002.[7] Introduction to the 600V ADD-A-pak TM and INT-A-pak TM IGBT Modules,International Rectifier Application notes 1992.[8] A. Laprade and R. H. Randal, Numerical Method for Evaluating IGBT Losses,Application Note 7520 Rev. A1.[9] Analog Devices: ADMC401 Double Update Mode of PWM generation Unit,Analog Devices, Inc., 1999.[10] Semikron application notes on heat sink systems.46