Voltage definitions for phase control and bi-directionally controlled thyristors

Transcription

1 Applicaion Noe 5SYA Volage definiions for phase conrol and bi-direcionally conrolled hyrisors High power hyrisors have a number of volage raings which need o be clearly undersood for heir opimal applicaion. This applicaion noe will explain he definiions and he pracical meanings of hese various volages. Power and produciviy for a beer world

2 Conens Page 1 Volage definiions for phase conrol and bi-direcionally conrolled hyrisors Parameer definiions Repeiive volage raings for ABB high volage hyrisors Volage raings for ABB hyrisors a low emperaures 4 2 References 4 2 Volage definiions for phase conrol and bi-direcionally conrolled hyrisors I Applicaion Noe 5SYA

3 1 Volage definiions for phase conrol and bi-direcionally conrolled hyrisors 1.1 Parameer definiions Several blocking volages are defined in he daa shees of high power semiconducors. The differences beween he various raings are explained in his secion. The definiions are, of course, sandardised and can be found in various inernaional sandards such as IEC I is imporan o disinguish beween repeiive over-volages V DR /V RR (commuaion over-volages ha appear a line frequency) and non-repeiive over-volage surges V DS /V RS ha appear randomly (e.g. because of lighning and nework ransiens). Too high a single volage surge will lead o an avalanche breakdown of he semiconducor and oo high a repeiive volage peak may lead o hermal «runaway» even if he ampliude of hese repeiive volages is below he avalanche break-down limi. Fig. 1: Definiion of repeiive, non-repeiive and normal operaing volages V DWM, V RWM : Maximum cres working forward and reverse volages. This is he maximum working volage a line frequency. For safe operaion, he device raed V DWM (or V RWM ) mus be equal o or higher han, ha depiced in Fig. 1. V DSM, V RSM : Maximum surge peak forward and reverse blocking volage. This is he absolue maximum single-pulse volage ha he devices can insananeously block. If a volage spike above his level is applied, he semiconducor will fail. ABB measures his parameer wih 10 ms half-sine pulses and a repeiion rae of 5 herz For safe operaion, he device s raed V DSM /V RSM mus be higher han he surge peak volage depiced in Fig. 1. V DRM, V RRM : Maximum repeiive peak forward and reverse blocking volage. This is he maximum volage ha he device can block repeiively. Above his level he device may hermally «runaway» and fail. This parameer is measured wih a pulse widh and repeiion rae defined in he device specificaion as explained laer in his applicaion noe. For safe operaion he device s raed V DRM /V DRM mus be higher han ha depiced in Fig Repeiive volage raings for ABB high volage hyrisors The definiion of «high volage» for a hyrisor is somewha arbirary bu has been se, a ABB a abou 4500 vols (V) for reasons discussed in he following. The Device Under Tes (DUT) mus have a sable and welldefined emperaure during he blocking measuremen and his is achieved by «passive» heaing (hea supplied o he whole device) hrough heaed connecions (e.g., a hydraulic press). The press applies he correc clamping force o he DUT and also provides he elecrical connecions. Since here is no emperaure gradien in his measuremen sysem, he problem of «hermal runaway» arises during esing. Since he early beginnings of semiconducor devices, hermal runaway has been a well-known problem. Thermal runaway occurs when he power dissipaion of a device increases rapidly wih emperaure. A classic example is hermal runaway during blocking, whereby he applied volage generaes a «leakage» curren and he V x I produc heas he device. As he device ges hoer, leakage curren increases exponenially and so, herefore, does he heaing. If he cooling of he device is no adequae, he device will ge progressively hoer and will ulimaely fail. The developmen of high-volage hyrisors has lead o increased values of dissipaed power in he off-sae, due o he higher blocking volages, even if he leakage currens hemselves have remained a similar levels o hose of earlier, lower volage, devices. This causes problems when such devices are characerised and are measured in ougoing inspecion a elevaed emperaures (e.g. 125 C). In such cases, he enire measuremen sysem is heaed o a consan emperaure and no emperaure gradien exiss o sink he hea generaed by he measuremen iself. This is in sark conras o real-world applicaions where he juncion emperaure may indeed reach 125 C bu he case emperaure never exceeds, say, 110 C, allowing leakage curren losses o be cooled away across he emperaure gradien beween juncion and case. Since hermal runaway iniiaes only a or above a cerain saring emperaure, ABB radiionally quoed wo differen repeiive volage raings specified a wo differen emperaures. As an example, hyrisor 5STP 26N6500 was raed V DRM = V RRM = 6500 V for juncion emperaures up o 110 C and 5600 V for emperaures up o 125 C. In boh cases, hese volages were specified using half-sine waves wih p = 10 ms and f = 50 Hz. Because of heir lower power losses, lower volage devices are less prone o hermal run-away and are herefore raed and esed wih he same V DRM and V RRM hroughou he raed emperaure range, hus simplifying es procedures. A more realisic mehod of measuring power semiconducors is achieved by forcing he es condiion o emulae he definiion of hese differen volages as shown in Fig. 1. This is done by using a sinusoidal 50 or 60 Hz wave of peak value V DWM /V RWM and superimposing a narrow pulse of ampliude V DRM per Fig. 2. This pulse corresponds o repeiive volage peaks as migh be caused by commuaion over-volages. [Such over-volages, which should never exceed V DRM and V RRM, are parly deermined V AK V DRM, V RRM V DRW, V RRW Fig. 2: Waveform for repeiive high volage esing p s 3 Volage definiions for phase conrol and bi-direcionally conrolled hyrisors I Applicaion Noe 5SYA

4 Blocking Maximum raed values 1) Parameer Symbol Condiions 5STP 12K6500 Uni Max. surge peak forward and reverse blocking volage V DSM, p = 10 ms, f = 5 Hz 6500 V V RSM T vj = C, Noe 1 Max repeiive peak forward and reverse blocking volage V DRM, f = 50 Hz, p = 10 ms, p1 = 250 μs, 6500 V V RRM Tvj = C, Noe 1, Noe 2 Max cres working forward and reverse volages V DWM, V AK V DRM, V RRM 3300 V V RWM Criical rae of rise of commuaing volage dv/d cri Exp. o 3750 V, T vj = 125 C 2000 V/µs Characerisic values p1 p V DWM,V RWM Parameer Symbol Condiions min yp max Uni Forward leakage curren I DRM V DRM, T vj = 125 C 600 ma Reverse leakage curren I RRM V RRM, T vj = 125 C 600 ma Fig. 3 : Volage raings in he daa shee for device 5STP 12K6500. Noe 1: Volage de-raing facor of 0.11% per C is applicable for Tvj below +5 C Noe 2: Recommended minimum raio of VDRM / VDWM or VRRM / VRWM = 2. See App. Noe 5SYA Due o he absence of a forward or reverse direcion in he case of Bi-direcionally Conrolled Thyrisors (BCTs) he erms VWM, VRM and VSM are used for he working volage, he repeiive peak volage and he non-repeiive peak (surge) volages respecively as can be seen in Fig. 4. Parameer Symbol Condiions 5STP 12K6500 Uni Max. surge peak forward and reverse blocking volage V SM p = 10 ms, f = 5 Hz 6500 V T vj = C, Noe 1 Max repeiive peak forward and reverse blocking volage V RM f = 50 Hz, p = 10 ms, p1 = 250 μs, 6500 V T vj = C, Noe 1, Noe 2 Max cres working forward and reverse volages V WM 3300 V V AK V RM p1 V WM Fig. 4: Deail from he volage raings in he daa shee for device 5STB 13N6500. p by «snubbers» (RC-circuis). See Applicaion Noe 5SYA2020 for snubber design]. By using he es mehod of Fig. 2, volage capabiliy will be esed a applicaion-like condiions in accordance wih inernaional sandards and wihou risk of hermal runaway during esing. ABB has inroduced his es mehod on hyrisors raed above 4500 V in compliance wih boh applicaion condiions and sandards definiions while avoiding hermal runaway a final es. V DWM and V RVM have been se o he maximum expeced working volage for he device s repeiive peak blocking volage according o he guidelines found in Applicaion Noe 5SYA2051. A volage peak of pulse widh s = 250 microsecond is added o he working volage cres such ha he sum corresponds o V DRM or V RRM. How hese new raings are presened in he daa shee can be seen in Fig. 3. Noe ha he given V DWM is boh a raing and a device es condiion and ha he supply volage in a given applicaion should no exceed i. For he selecion of raed volage for a given supply volage, see Applicaion Noe 5SYA Volage raings for ABB hyrisors a low emperaures A low emperaures hermal runaway is no an issue bu here is a limiaion of he blocking volage due o he emperaure dependence of he avalanche breakdown volage. The avalanche breakdown volage decreases wih decreasing emperaure a a rae of abou 0.11 percen/k. This means ha a de-raing of V DRM and V DSM for he device is needed when operaing a low emperaures. As can be seen on he device daa shees, his is applicable o emperaures below 5 C and is explained in he daa shee in Noe 1 of Fig References 1) IEC «Semiconducor Devices» 2) 5SYA2020 «Design of RC Snubbers for Phase Conrol Applicaions» 3) 5SYA2051 «Volage raings of high power semiconducors» The applicaion noes, References 2 and 3, are available a www. abb.com/semiconducors 3 Revision hisory Version Change Auhors 01 Björn Backlund Thomas Sez 4 Volage definiions for phase conrol and bi-direcionally conrolled hyrisors I Applicaion Noe 5SYA

5 Conac us ABB Swizerland Ld Semiconducors Fabriksrasse 3 CH-5600 Lenzburg Swizerland Tel: Fax: abbsem@ch.abb.com m.abb.com Noe We reserve he righ o make echnical changes or o modify he conens of his documen wihou prior noice. We reserve all righs in his documen and he informaion conained herein. Any reproducion or uilisaion of his documen or pars hereof for commercial purposes wihou our prior wrien consen is forbidden. Any liabiliy for use of our producs conrary o he insrucions in his documen is excluded. Applicaion noe 5SYA Power and produciviy for a beer world