Applicaion Noe AN-8004 Revision: Issue Dae: Prepared by: 00 2008-05-21 Dr. Arend Winrich Ke y Words: SemiSel, Semiconducor Selecion, Loss Calculaion Sofware release of SemiSel version 3.1 New semiconducor available... 1 Temperaure ripple a low inverer oupu frequencies... 1 New SRM circui... 3 Improved user-friendliness... 3 Devices wih 175 C juncion emperaure... 3 Oher informaion... 4 Symbols and erms used... 4 A new version of SEMIKRON s online simulaion ool SemiSel has been released (hp://semisel.semikron.com). This sofware calculaes he losses and emperaures of power semiconducors in ypical power elecronic circuis and helps users selec he correc SEMIKRON producs for differen applicaions and operaing condiions. The ool has been in use since 2001 and has proven o be very successful several en housand imes already. The new sofware version has been improved o improve user-friendliess and produce more accurae resuls. New power device families have been inegraed and a new circui is available for calculaion. New semiconducor available The daabase is coninually updaed as new silicon generaions in exising housings are inroduced (e.g. IGBT modules wih Trench 4 Exension T4 ) and device parameers are changed. Besides his, new producs have been inroduced in he pas monh. As a resul, he SEMiX family now includes hyrisor and diode modules for AC/DC converers (recifiers) and AC/AC converer applicaions. This new produc group was added o he device selecion page. Fig. 2 IGBT in SEMIPONT modules can be seleced for brake chopper calculaion Fig. 1 Thyrisors and diodes in SEMiX modules can be seleced for calculaion Furhermore, IGBTs are now also available in he DC/DC converer secion, which is used as a brake chopper in a SEMIPONT recifier module. Temperaure ripple a low inverer oupu frequencies SemiSel always calculaes losses and emperaures as an average value of periodical funcions. The resuls are average losses and, consequenly, average device emperaures. For inverers wih high oupu frequencies (f ou >= 50Hz) his is accepable. If he frequencies are low in relaion o he device ime consans, a subsanial emperaure ripple around he average value has o be 1 / 5
aken ino accoun. This ripple increases as he inverer oupu frequency decreases. Fig. 3 Time funcion of calculaed (solid line) and real (doed line) losses and emperaures I C P v P v(av) T j T j(av) dt j To obain a more precise resul a ime funcion of he juncion emperaure is calculaed from he power dissipaion for each individual device using he new sofware version. The hermal impedance Z h(j-c) for modules wih baseplae or he hermal impedance Z h(j-s) for modules wihou baseplae is used o obain he ime funcion. The emperaures in he inverer page are now given as average values for nominal condiions and maximum values for minimum frequency. The corresponding emperaure graph shows an envelop funcion of he maximum juncion emperaures. Using 50Hz as he nominal and minimum frequency shows ha even a his frequency he average and he maximum values differ by several degrees. Fig. 5 New resuls page for inverer calculaion Up o now one fixed correcion facor for all devices was used o esimae he emperaure ripple. The emperaure difference juncion-o-case was muliplied by f corr (red line in Fig. 4) o obain he maximum emperaure. T j(max) = Tc + f corr Rh( j c) P v( av) This was only a firs-order approximaion wih a relaively high error margin, which was facored in by a high recommended safey margin. For emperaures above 10Hz he ripple was negleced enirely. Fig. 4 Former correcion funcion used o esimae he emperaure ripple a low frequencies Possible oher characerisic depending on hermal impedance A comparison beween he former and he new mehod of emperaure ripple calculaion shows ha far higher peak emperaures have o be considered han was he case in he pas, especially for frequencies beween 1 and 10Hz. This can be seen in he following example: SEMITRANS SKM400GB128D @ P16/200 heasink, V d =650V; f sw =4kHz, I ou =125A, 50% overload for 60s, fou=0.1 50Hz; V ou =41 400V; (f/u characerisic) Fixed, former funcion of f corr f ou [Hz] Table 1 Comparison of maximum juncion emperaure using old correcion facor or new hermal impedance f ou [Hz] T j(max)r T j(max)d T j(max)r T j(max)d dt [K] Old New 0,1 139 144 137 141-3 1 129 132 135 140 +8 2 123 126 131 138 +12 5 121 122 127 132 +10 10 120 120 125 126 +6 20 120 118 124 121 +4 50 122 116 124 116 +2 2 / 5
The reason for he high emperaure peak is ha he hermal impedance Z h(j-c) of he Semirans module reaches is final value afer abou 100ms. The IGBT is 500ms in operaion wih an inverer oupufrequency of New SRM circui Owing o increased ineres in device proposals for swiched relucance moor (SRM) applicaions, his ype of circui has now been included in SemiSel. From a power elecronic poin of view, he moor is driven by a pulsed DC curren in an asymmerical H-bridge. The circui is herefore available as a DC/DC converer. One H-bridge is used per phase. 1Hz. The emperaure difference reaches almos seadysae condiions a maximum power dissipaion. The formulas ha apply are hose for he Buck converer (sep-down converer). The value of he duy cycle DC corresponds o he average urn-on ime of he IGBT during he curren pulse. The curren pulse widh is referred as pw and he period ime as T P. Deails can be seen in he sofware help file. Fig. 6 Circui diagram for one phase of a swiched relucance moor (SRM) Improved user-friendliness In he pas, i was difficul o read he exac values from plos showing emperaure and power loss funcion. To allow for deailed analyses a zoom funcion for graphics has now been added (Java apple mus be insalled). Furhermore, i is now possible o ransfer raw funcions and characerisics daa o able calculaion sofware (XY able values). Furher, in user-specific load cycles addiional lines ofen had o be added afer a firs calculaion. Unforunaely he whole able had o be rearranged if one line was missed. An addiional line (or ime sep) of a load cycle can now be added o he end of an exising able. The ime is adaped auomaically in increasing order using he Sor buon. Fig. 7 Zoom and ransfer funcion Fig. 8 Sor funcion Devices wih 175 C juncion emperaure New IGBT and diode generaions are able o operae up o a juncion emperaure of 175 C. 3 / 5
Daa shee high emperaure enries for hese devices are given a 150 C (insead of 125 C for previous generaions). Now, all of he device parameers are considered wih regard o he reference emperaure in he daa shee (e.g. 125 C or 150 C). This affecs he emperaure coefficiens used inernally for he power loss calculaion. The maximum recommended juncion emperaure for IGBT during operaion is se a T j(max) - 25 C, e.g. 150 C for 175 C devices. Oher informaion Low numbers (<10) are now calculaed o wo digial poins greaer precision for calculaions for small SEMITOP or MiniSKiiP devices Swiching frequency is limied o maximum raings of he seleced device Comparison of circui curren agains I CRM (repeiive maximum curren) of he device User load cycle: calculae buon afer an exising file has been modified User load cycle of DC/DC converer: conducing ime of diode is available for non-coninuous curren. Calculaion wih negaive ambien emperaure also possible Device proposal: number of displayed devices can be changed Device proposal: limi of T j(max) for he selecion can be changed Symbols and erms used Symbol Term f corr Correcion facor (used here o esimae T j(max) ) f ou f sw IGBT I C I CRM P cond P d P sw P r P o P V P V(av) R h(j-c) Inverer oupu frequency Swiching frequency Insulaed Gae Bipolar Transisor Collecor curren of an IGBT Repeiive maximum collecor curren Conducing losses of a semiconducor Diode losses, sum of P cond + P sw Swiching losses of a semiconducor Transisor losses, sum of P cond + P sw Toal losses (of all devices a he hea sink) Power losses general Average value of power losses over a period of inverer oupu frequency Thermal resisance beween juncion and case SRM T c T d T j T j(av) T j(max) T s T r T P pw V d Z h(j-c) Z h(j-s) Swiched relucance moor Case emperaure Diode (juncion) emperaure Juncion emperaure Calculaed average juncion emperaure over a period of inverer oupu frequency Calculaed maximum juncion emperaure wihin a period of inverer oupu frequency Hea sink emperaure Transisor (juncion) emperaure Period of one winding curren sequence of he SRM Widh of one winding curren pulse of he SRM DC-Link volage Thermal impedance beween juncion and case Thermal impedance beween juncion and sink DISCLAIMER SEMIKRON reserves he righ o make changes wihou furher noice herein o improve reliabiliy, funcion or design. Informaion furnished in his documen is believed o be accurae and reliable. However, no represenaion or warrany is given and no liabiliy is assumed wih respec o he accuracy or use of such informaion. SEMIKRON does no assume any liabiliy arising ou of he applicaion or use of any produc or circui described herein. Furhermore, his echnical informaion may no be considered as an assurance of componen characerisics. No warrany or guaranee expressed or implied is made regarding delivery, performance or suiabiliy. This documen supersedes and replaces all informaion previously supplied and may be superseded by updaes wihou furher noice. SEMIKRON producs are no auhorized for use in life suppor appliances and sysems wihou express wrien approval by SEMIKRON. 4 / 5 11 28 36 00 05 / 2008
SEMIKRON INTERNATIONAL GmbH P.O. Box 820251 90253 Nürnberg Deuschland Tel: +49 911-65 59-234 Fax: +49 911-65 59-262 sales.skd@semikron.com www.semikron.com 5 / 5