The thermal model and thermal management of high power IGBT PWM inverter

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1 The thermal model and thermal management o high ower GBT PWM inverter Xiaohong Hao*, Huimin Wang, Yixiong Wang University o Electronics Scien and Technology o China haoxiaohong@uestc.edu.cn EEE PEDS 07, Honolulu, USA 5 Dember 07 Abstract- For the ower electronics devis with the insulated gate biolar transistors (GBTs), its thermal management is very imortant and nessary or the devis reliability. n this aer, ower losses o the GBT (Fuji MB600N-0-50) PWM inverter were evaluated based on its electro-thermal model and control logic. Accordingly, its thermal management system using ord air cooling is designed and simulated, and the results showed that the thermal management system is easible and can guarantee the junction temerature o the GBT.. NTRODUCTON t is well known that ower semiconductor devis are now going through a raid evolution,esecially the GBT (insulated-gate biolar transistor) modules, which are getting more acted and increasingly used in the ower electrical devis as high ower and high voltage switching comonents, such as ulse width-modulated (PWM) inverters, voltage-sourd converter (SC)-based lexible AC transmission systems (FACTS) devis, and so on. With the develoment o widely alying requirement, GBT is develoed towards the high ower density, high ono switch requency and small volume. All these characteristics made its ower losses increases, and heat dissiation area decreases. Accordingly, its thermal roblem is becoming more and more serious. This will lead to high junction temeratures, and aect its transer erorman and outut characteristic. n addition, the thermal roblem also restricts the miniaturation o the GBT, and redus its alication ield. So, its thermal management system is very imortant or the ower electronics devis to ensure its reliability and stability. To develo the thermal management o GBTs, their ower losses needs to be evaluated at irst. GBT is a switching ower electronics, and they are turned on and o by logic control circuitry during the devi switching cycle. Thereby, their ower losses related with the control rule. So the electrical model related with control rule needs to be known. The earliest GBT model is Hener's GBT electrical model[], which comrehensively takes into account GBT's various oerating characteristics to ensure the model accuracy. Most GBT s oerating characteristics, such as static characteristics, dynamic characteristics and so on can be evaluated based on the electrical model. Till now, many GBT models are still built based on the Hener s electrical model[-4]. Qiang Li et al. calculate the GBT ower loss with the hel o the circuit simulation sotware, but it requires the accurate GBT s electrical model, and it also needs to use the rograms to achieve the ower loss[5]. Qing Wang et al otimized the GBT electrical model by united the existing ideal switch model with a non-linear resistor with the hel o the Matlab sotware[6]. Gensuo Lu roosed a simle GBT electrical model according to the external characteristics arameters in the Protel[7]. When GBTs are used in dierent devis, their logic control rule are dierent so that their thermal model are dierent. Their thermal model can be established using relaxation method and direction method[8-9]. The relaxation method couled the electrical circuit simulation (SPCE, Saber etc) with FEM together to dedu the thermal resistan and junction temerature; and the direct method calculates their thermal inormation in a couled manner along with the electrical models. J. H. Lee et al established an electro-thermal model o 00W boost converter using GBT using the relaxation method, and designed a natural convection cooling aluminum heat sink[8]. M. M. R. Ahmed used the direct method to redict junction temerature under transient condition[9]. A comound GBT electro-thermal model was built combined its hysical structure, the heating eect o Henner s electrical model by A.R. Hener et al.[0], then the GBT s loss and junction temeratures were simulated with the comuter aided circuit analysis sotware. To build the above model, the GBT s structural arameters need to be known which is diicult to obtain; also, because GBT s switching transient ross is nanosecond, the simulation ste is very short and the simulation cycle is time consuming; esecially or a multi-chi GBT module, the above question is more serious. A three-dimensional structure model o the GBT is established in the FEM sotware to derive its thermal model by the researcher C.S.Yun et al.[]. n summary, the researchers roosed various GBT electrical and thermal model according to its structure characteristic, but ew researchers ocused on its ower losses, thermal model, and thermal management according to its control rule. n this aer, an GBT ower losses is evaluated according to Hener s electrical model and its switching rule, and then its ower losses are evaluated taking into account the deendency o the switching losses on various actors such as /7/$ EEE 97

2 the switching voltage, switching current, stray inductan, and the reverse recovery ross o the reewheelingdiode (). alidation o the model was conducted by comarison with ublished characteristic curves by the manuacturer. The thermal model o GBTs PWM inverter comosed o six GBTs is established, and their thermal management system is designed and simulated. CE. THE ELECTRCAL MODEL OF THE GBT As well known, the GBT can be regarded as a Darlington structural comonents which consists o Biolar Junction Transistor (BJT) and Metal-Oxide-Semiconductor Field- Eect Transistor (MOSFET), where BJT is the conduction element, MOSFET is the driving element. Accordingly, its electrical model can be established in the Psi as shown in Fig.. Where, R s is the arasitic resistan or MOS; R G, R C and R E are resistan which servi or the conduction o the devi, resectively, H is controlled ower, D BE and D SD are diode, resectively. Then, its transer characteristics and outut characteristics can be simulated and shown in Fig., and the according characteristic curves came rom the data sheet shown in Fig.3. As can be seen that the simulation curves are agree with those rom the data sheet. Thereore, the electrical model can be used to simulate the switching ross o the GBT. Also, the thermal loss o the GBT can be calculated according to its working condition. CE (b) Transer characteristic curve o simulation Fig. the curves o transer characteristic and outut characteristic simulated or the GBT C R C (a) Transer characteristic curve o data sheet R R H D BE BJT G R G MOSFET D SD R S R E E Fig. the electrical model o the GBT in the simulation sotware CE (b) Outut characteristic curves o data sheet Fig. 3 the curves o transer characteristic and outut characteristic given by the data sheet THERMAL MODEL OF THE GBT GE (a) Transer characteristic curve o simulation The ower losses o GBT come rom the GBT chi and the aralleled chi, and GBT chi losses include conduction losses and switching loss, and the reewheeling diode losses include the conduction loss and turn-o loss. Based on its electrical model and control rule, these losses can be evaluated as ollows: a. The GBT conduction losses: 98

3 The conduction losses comes rom the saturation voltage dro, its general ormula is P *cos cond-igbt r M r () Where P cond-igbt is conduction losses, is saturation voltage dro, is the eak value o outut current, r is conduction equivalent resistan, M is the duty cycle o the PWM modulation outut, cosφ is the PWM outut Power actor. b. The GBT switching loss The switching loss comes rom ower losses during its turn on and turn o, its general ormula is Psw-igbt * * E on E o () Where P sw-igbt is switching loss, is switching requency, E on is the single ulse turn-on ower consumtion under the rated condition, and E o is the single ulse turn-o ower consumtion under the rated condition. c. conduction loss o Similar to GBT chis, the conduction loss o comes rom the conduction voltage dro and junction thermal resistan, and it can be calculated as: P *cos cond-diode r - M r (3) Where P cond-diode is conduction loss, is the saturation voltage dro, is the eak value o the outut current, r is conduction equivalent resistan, M is the PWM modulation outut duty cycle, cosφ is the PWM outut Power actor. d. turn-o loss o The turn-o loss o the is mainly caused by its recovery o state, and it can be calculated as: P sw-diode * * (4) E rr Where P sw-diode is the turn-o loss, is switching requency, E rr is the single ulse turn-o ower consumtion under the rated condition. Then, the total ower losses o the GBT are as ollows: P total P c P P P (5) ondigbt swigbt conddiode swdiode t can be seen that the ower losses can be evaluated according to the GBT control rule, such as working requency, collector current, duty cycle and so on. When the GBTs are used in the PWM inverter, its heat transer model can be described in the Fig.4. Here, totally six GBTs are used in the inverter, and there are three GBTs working together in every hase. Switching rule o the GBTs at every hase is shown in Fig.5. T-T6 denote six GBTs. THERMAL SMULATON OF THE GBT PWM NERTER According to their control rule, a orcing air cooling thermal management system is designed and simulated. The simulation model built in the FEM are shown in Fig.6. The attribute arameters o each art o the simulation model are shown in Tab.. PGBT GBT P PGBT : ower o the GBT P : ower o the GBT : the total ower o the GBT and Rha + Ta _ Six legs GBT : Thermal resistan o GBT : Thermal resistan o heat sink : Thermal resistan o : The thermal resistan between GBT casing and heat sink Rha : Thermal resistan o the heat sink Fig. 4 the thermal resistan network model o the GBTs used in the inverter 3 4 No./GBT T T T3 T4 T5 system T6 t/s T T T3 T4 T5 T6 T Fig.5 The switching rule o the GBTs in the PWM inverter during one cycle T T3 T5 T T4 T6 : GBT module; : substrate;; 3: an; 4: heat sink. Fig.6 the simulation model o the GBT used in the inverter with the cooling system Tab. The attribute arameters o each art o the simulation model in ak Name Material Size (mm) GBT Si 6 7 Power Thermal conductivity (W/(m K)) Model 60W 48 MB60 0N substrate Cu TM grease 6 Heat sink 0.3 AlN an DXC SKF According to the working rincile o the inverter, there are six working state, and three GBTs working together in 99

4 every stage. The GBTs are lad on the dierent osition o the heat sink, thereore its temerature distribution is dierent at every stage. Fig. 7 to show the temerature simulation results at dierent stage. For T hase, T, T4 and T5 are working and have ower losses, the temerature distribution is shown in Fig.7. At this time the three GBT module are lad uniormly on the heat sink, the heat rodud don t aect each other, so the cooling result is relatively ideal. For T hase, T, T4 and T6 are working, the temerature distribution is shown in Fig.8. At this time, T4 and T6 are neighbor, and arthest rom the an simultaneously, so the cooling eect o this hase relative to several other stages is oorer, but the maximum temerature is below 80. For T3 hase, T, T3 and T6 are working, the temerature distribution is shown in Fig.9. At this time, comared with Figure 8, although the T and T3 are neighbor, they are close to the an, so the highest temerature o the stage is lower than the T stage. For T4 hase, T, T3 and T6 are working, the temerature distribution is shown in Fig.0. At this time, the three GBT are lad uniormly, but they are ar away rom the an comared with hase T, so the overall temerature increases a little. For T5 hase, T, T3 and T5 are working, the temerature distribution is shown in Fig.. At this time, the three GBT modules are neighbor, so the temerature at this hase is higher than other stage. For T6 hase, T, T4 and T5 are working, the temerature distribution is shown in Fig.. At this time comared with Figure,under the two hases, the three GBT modules which are adjant each other are oerating at the same time, but sin the three GBT modules in Fig. are arer than the three GBT modules in Figure, so the temerature under this hase is slightly higher than hase T5. Fig.8 Temerature distribution or T hase Fig.9 Temerature distribution or T3 hase Fig.0 Temerature distribution or T4 hase Fig. Temerature distribution or T5 hase Fig.7 Temerature distribution or T hase 00

5 [8] J Hoon Lee,H Cho Bo, Large time-scale electro-thermal simulation or loss and thermal management o ower MOSFET, EEE Annual Power Electronics Secialist Coneren,. -7, January, 003. [9] M MR Ahmed,G A Putrus, A method or redicting GBT junction temerature under transient condition, 34th Annual Coneren o EEE ndustrial Electronics, , 008. [0] A. R. Hener, A dynamic electro-thermal model or the GBT, ndustry Alications Society Meeting EEE, vol., : , 99. [] C. S. Yun, P. Regli, J. Waldmeyer, et al., Static and dynamic thermal characteristics o GBT ower modules, The nternational Symosium on Power Semiconductor Devis and cs, : 37-40, 999. Fig. Temerature distribution or T6 hase n summary, the ord air cooling system can guarantee the GBT PWM inverter working temerature.. CONCLUSONS The main work and conclusions o this aer are summarized as ollows: () Based on the circuit equivalent method, the GBT (Fuji: MB600N-0-50) electrical model are built. And its transer characteristic curve and outut characteristics curve are comared with the oicial data sheet, which veriied the accuracy o the electrical model. () According the working rincile o the GBTs, its ower losses are evaluated and thermal resistan model are established to evaluate its temerature. (3) A thermal management system is designed or the GBT PWM inverter. The simulation result showed that the thermal management system can ensure the working temerature or every working hase. ACKNOWLEDGMENT This work was suorted by the National Natural Scien Foundation o China (No and No ), the Doctoral Fund o the Ministry o Education o China (No. 04M55333), the Doctoral Fund o the Sichuan rovin, the Fundamental Research Funds or the Central Universities (No.ZYGX04Z004 and ZYGX05J083) and the Research Funds o State Key Laboratory or Manuacturing Systems Engineering (sklms06009). REFERENCES [] A. R. Hener, D. M. Diebolt, An exerimentally veriied GBT model imlemented in the Saber circuit simulator, Power Electronics Secialists Coneren, 99, Pesc '9 Record. EEE. 99:0-9. [] A. R. Hener, Modeling buer layer GBTs or circuit simulation, EEE Trans. J. Power Electronics, vol.,. -3, 995. [3] G. vensky,. Zeltser, A. Kats, et al., Reducing GBT losses in ZCS series resonant converters, EEE Trans. J. ndustrial Electronics, vol. 46,.67-74, January 999. [4] J. Zheng, X. B. Wang, Y. X. Guan, Research on heat transer in the high ower GBT module based on Ansys, Power Electronics, vol 45, , January, 0. [5] Q. Li, M. Y. L, et al., GBT ower loss estimation based on si simulation, Electric ower automation equiment, vol. 5,. 3-33, January, 005. [6] Q. Wang, X. J. Zhang, et al., Modeling o nsulated Gate Biolar Transistor(GBT), Trans. China Welding nstitution, vol.,. 38-4, Aril, 000. [7] G. S. Lu, Simliicational model o GBT in Protel99se, Proedings o the EPSA, vol. 5,. 80-8,