V AK (t) I T (t) I TRM. V AK( full area) (t) t t 1 Axial turn-on. Switching losses for Phase Control and Bi- Directionally Controlled Thyristors

Transcription

1 Applicaion Noe Swiching losses for Phase Conrol and Bi- Direcionally Conrolled Thyrisors V AK () I T () Causing W on I TRM V AK( full area) () 1 Axial urn-on Plasma spread 2

2 Swiching losses for Phase Conrol and Bi- Direcionally Conrolled Thyrisors Applicaion Noe Björn Backlund, Jürg Waldmeyer ABB Swizerland Ld Semiconducors Ocober 2007 Table of Conens: 1 SWITCHING LOSSES FOR PHASE CONTROL AND BI-DIRECTIONALLY CONTROLLED THYRISTORS INTRODUCTION PARAMETER DEFINITIONS TURN-ON LOSSES THE TURN-ON PROCESS DETERMINING THE TURN-ON LOSSES THE DATA SHEET CURVES FOR TURN-ON TURN-OFF LOSSES THE TURN-OFF PROCESS DETERMINING THE TURN-OFF LOSSES THE DATA SHEET CURVES FOR TURN-OFF CALCULATION OF THE TOTAL THYRISTOR LOSSES ADDITIONAL NOTES REFERENCES APPLICATION SUPPORT...9 Page 2 of 9 Doc. No. 5SYA Oc. 07

3 1 Swiching losses for phase conrol and bi-direcionally conrolled hyrisors 1.1 Inroducion In hyrisor applicaions he on-sae power loss is he dominan par ha can be easily calculaed using he well-known equaion 1. P V + T = E qn 1 2 T 0 * ITav rt * ITrms I is someimes sufficien o calculae wih hese losses only, when using ample margins owards he maximum allowed juncion emperaure. For more careful hermal dimensioning, he swiching losses of he hyrisor mus also be aken ino accoun, as hey represen a par of he losses ha, especially for high volage devices, canno be ignored. Since relaions beween device parameers and losses are oo complex o be expressed in a simple formula as on-sae losses, ABB has included curves showing he swiching energies for a given se of condiions in he daa shees for heir hyrisor produc range. In his applicaion noe we explain he swiching processes and how he loss curves should be read. 1.2 Parameer definiions The relevan swiching parameers are in his secion defined and illusraed by figures where appropriae. For explanaion purposes, daa and diagrams associaed wih 5STP 26N6500 have been used, however he definiions are applicable o all phase conrol and bi-direcionally conrolled hyrisors. The parameers are defined according o sandard IEC I TRM I T (), V() -di T /d Q rr 3 4 -I RM V() -V 0 -dv/d com -V RRM Fig. 1 Definiions of reverse recovery parameers for phase conrol hyrisor. Q rr : Reverse recovery charge. Inegral of he reverse curren during commuaion a given condiions saring a he 0-crossing of he reverse curren, 3, and ending when he reverse curren goes back o 0, 4, (See Figure 1) as expressed by equaion 2. Q rr = 4 3 i T ( ) d I RM : Reverse recovery curren. Peak value of he reverse recovery curren a given condiions. See Figure 1. E qn 2 Page 3 of 9 Doc. No. 5SYA Oc. 07

4 I TRM : Peak forward curren. Maximum forward curren hrough he hyrisor. See Figure 1. V 0 : Commuaion volage. Quasi-saionary volage driving he commuaion. See Figure 1. W on : Turn-on swiching energy. The energy dissipaed during a single urn-on even. I is he inegral of he produc of anode curren and he surplus of anode-cahode volage due o he limied conducing area of he hyrisor a riggering. This produc is inegraed from insan 1, when he hyrisor sars conducing, o insan 2, when he plasma spread is finished and he whole hyrisor area is conducing (see Figure 2) as expressed by Equaion 3. 2 Won = ( it ( ) ( vak ( ) vak ( fullarea) ( ))) d E qn 3 1 W off : Turn-off swiching energy. The energy dissipaed during a single urn-off even. I is he inegral of he produc of anode curren and anode-cahode volage from he insan 3, when he reverse recovery crosses he 0-line, o he insan 4, when he reverse recovery is back o 0 (see Figure 1) as expressed by Equaion 4. W off 4 = ( it ( ) v 3 AK ( )) d E qn 4 2 Turn-on losses 2.1 The urn-on process Turn-on losses in a hyrisor are generaed when he device, jus afer riggering, has an anode o cahode volage differen from he saic volage drop, which he device would have, if he whole area was conducing. When he device is riggered (for recommendaions abou he gae riggering of a hyrisor see applicaion noe 5SYA2034) his surplus volage creaes an addiional energy loss. The urn-on energy W on is composed of mainly wo physical processes: (a) axial urn-on, where he anode and cahode emiers injec carriers and form a firs lached conducing channel in he iniially urned-on area of he hyrisor, and (b) plasma spread, where he iniially conducing channel spreads over he whole cahode area of he hyrisor. In normal cases wih di/d of he order of 1 o a few ens of A/µs, axial urn-on is fas and causes only a small conribuion o W on. Figure 2 visualizes he urn-on process of a hyrisor srucure. V AK () I T () Causing W on I TRM V AK( full area) () 1 Axial urn-on Plasma spread 2 Fig. 2 Typical curren and volage ransiens a urn-on of a hyrisor srucure. Page 4 of 9 Doc. No. 5SYA Oc. 07

5 Depending on size, gae design and he curren wave shape, he plasma spread can ake as long as 2 3 ms, meaning ha a shor curren pulses, he enire hyrisor area may no be conducive before he device is urned off. 2.2 Deermining he urn-on losses Since i is hardly possible o measure all he needed daa poins for daa shee curves, a model for urn-on energy calculaions was developed and calibraed using measured daa. For urn on, a simulaion mehod including plasma spread is used. The model separaes he hyrisor areas, conducing and non-conducing, a every insance of ime. The conducing area is assumed o have he same sandard on-sae volage vs. curren densiy behavior as he hyrisor conducing over is full area. The remaining area akes no curren. The conducing area is assumed o sar a he inner cahode area conour wih a minimum widh and o propagae owards he periphery a a velociy proporional o he square roo of he acual curren densiy. When he conducing area has spread over he oal hyrisor area, he urn-on process has reached is end and he complee urn-on energy has been dissipaed. To calibrae his calculaion mehod, comparisons of measured daa were made as shown in Figure 3. 5STP 26N6500, NV ms, 8 ka 16' '000 12'000 V AK () IT [A] 10'000 8'000 V AK( full area) () I T () VAK [V] 6' ' ' E E E E E E E E E E E-03 [s] Fig. 3 Comparison of measured (green) and simulaed urn-on ransiens (red and black) of 5STP 26N6500, using a half sine curren waveform. The calculaed values were hen used o creae he daa shee curves for urn-on energy. 2.3 The daa shee curves for urn-on The urn-on losses in he daa shees are presened as curves for urn-on energy for one urn-on even for sinusoidal curren and for recangular curren, which sricly speaking is a rapezoidal curren. Common for boh curves is he absence of V AK as a parameer. The reason for his is ha he volage will break down during he shor period of ime during axial urn-on o a value ha is almos independen of he volage level a which he device was riggered, before he plasma spread phase sars. Since he curren during he axial urn-on period is comparaively small, he influence of his par on he oal losses is minue, and herefore he influence of he volage a he insan of riggering can be disregarded. I should also be noed ha he small addiional urn-on energy caused by he discharge curren emanaing from he RCsnubber circui is no included in he curves. Page 5 of 9 Doc. No. 5SYA Oc. 07

6 Fig. 4 Turn-on energy, half sinusoidal waves. Figure 4 shows he urn-on energy per pulse, as a funcion of he peak value of he sinusoidal curren, for several pulse widhs. The dashed curve secions show ha for his hyrisor, shor pulse widhs in combinaion wih low peak currens are no sufficien o ge he device fully conducing before he curren pulse is over. Fig. 5 Turn-on energy, recangular waves. Figure 5 shows he urn-on energy per pulse as a funcion of he DC-curren level for differen raes of rise of he on-sae curren. Page 6 of 9 Doc. No. 5SYA Oc. 07

7 3 Turn-off losses 3.1 The urn-off process The urn-off process for a hyrisor and he calculaion of he RC-circui are described in applicaion noe 5SYA2020. In he applicaion noe we describe differen simulaion mehods for he urn-off energy and one of he mehods is used o creae he daa shee urn-off energy curves. 3.2 Deermining he urn-off losses Simulaion of urn-off energies of a hyrisor a moderae di/d is easily possible under a number of assumed simplificaions. Here we are using he exponenial recovery curren model mehod described in 5SYA2020. The hyrisor is considered as a curren source during he urn-off process. A a given di/d, he curren decreases linearly hrough zero down o he reverse recovery curren I RM and from here decays exponenially wih a ime consan compaible wih he given recovery charge Q rr. A simple circui simulaion can predic he reverse volage ransien and hus he urn-off energy. This simulaion is performed using Pspice and is calibraed using a number of measuremen poins. To simplify he calculaions and o obain consisency, an RC-circui wih R = 22 Ω and C = 1.0 µf was chosen. The calculaed values were hen used o creae he daa shee curves for urn-off energy. 3.3 The daa shee curves for urn-off The urn-off losses in he daa shees are presened as curves for urn-off energy for one urn-off even for sinusoidal curren and for recangular curren, which sricly speaking is a rapezoidal curren. A specific RC-circui, wih values chosen o correspond o a ypical RC-circui as can be expeced o be used in normal applicaions, is common for boh curves. For RC-circui values differing significanly from hose used for he curves, he losses should be measured or calculaed, preferably using he mehods proposed in applicaion noe 5SYA2020. The reverse recovery parameers of a hyrisor have a fairly srong emperaure dependency and consequenly he urn-off losses also have a significan emperaure dependency. The curves are given for 125 C which is he wors case. For lower emperaures, he urn-off losses will be lower. Fig. 6 Turn-off energy, half sinusoidal waves. Page 7 of 9 Doc. No. 5SYA Oc. 07

8 Figure 6 shows he urn-off energy per pulse, as a funcion of he commuaion volage V 0 for a few peak values of sinusoidal curren pulses. The pulse widh of 10 ms corresponds o 50 Hz. For 60 Hz he pulse widh is 8.3 ms, and he losses will be abou 15 % higher due o he higher di/d. Fig. 7 Turn-off energy, recangular waves. Figure 7 shows he urn-off energy per pulse, as a funcion of he commuaion volage V 0 for differen raes of decrease of he on-sae curren. The di/d is given as a posiive number in he curve alhough i is acually a rae of decrease. The influence of I TRM is no included in hese curves, as he influence is no very large for normal operaing currens a given di/d. The reverse recovery parameers and also W off will decrease only a low currens. 4 Calculaion of he oal hyrisor losses When he commuaion angle is sable he oal hyrisor losses can be calculaed using equaion 5 where f is he swiching frequency for he hyrisors. P = P + f ( W + W ) E qn 5 Toal T * on off In addiion o he on-sae and he swiching losses, he hyrisor also has gae and blocking losses, bu hese are so small ha hey can be disregarded in almos all cases. Only for very special applicaions and operaing condiions may he blocking losses need aenion. I should be noed ha he daa shee values for V T0, r, W on and W off are maximum values. I is quie unlikely ha any device will have his combinaion, so calculaions using he daa shee values will very probably inroduce some margin in relaion o an acual componen. Page 8 of 9 Doc. No. 5SYA Oc. 07

9 5 Addiional noes 5.1 References 1) IEC Semiconducor Devices 2) 5SYA2020 Design of RC Snubbers for Phase Conrol Applicaions 3) 5SYA2034 Gae-drive Recommendaions for Phase Conrol and Bi-Direcionally Conrolled Thyrisors The applicaion noes, References 2 and 3, are available a Applicaion suppor For furher informaion please conac: Produc markeing engineer: Björn Backlund Phone , fax bjoern.backlund@ch.abb.com Address: ABB Swizerland Ld Semiconducors Fabriksrasse 3 CH-5600 Lenzburg Swizerland abbsem@ch.abb.com Inerne Daa shees for he devices and your neares sales office can be found a he ABB Swizerland Ld, Semiconducors inerne web sie: hp:// Page 9 of 9 Doc. No. 5SYA Oc. 07