外文翻譯---晶閘管的高能脈沖式開關(guān)特性 英文

1、IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 8, NO. 4, OCTOBER 1993 347 High-Energy Pulse-Switching Characteristics of Thyristors Venkateswara A. Sankaran, Member, IEEE, Jerry L. Hudgins, Senior Member, IEEE, and Will

2、iam M. Portnoy, Fellow, IEEE Abstract-Experiments were conducted to study the high en- ergy, high d i l d t pulse-switching characteristics of SCR's with and without the amplifying gate. High dildt. high-energy s

3、ingle- shot experiments were first done. Devices without the amplifying gate performed much better than the devices with the amplifying gate. A physical model is presented to describe the role of the amplifying gate

4、in the turn-on process, thereby explaining the differences in the switching characteristics. The turn-on area for the failure of the devices was theoretically estimated and correlated with observations. This allowed c

5、alculation of the current density required for failure. Since the failure of these devices under high d i l d t conditions was thermal in nature, a simulation using a finite-element method was performed to estimate

6、the temperature rise in the devices. The results from this simulation showed that the temperature rise was significantly higher in the devices with the amplifying gate than in the devices without the amplifying gate.

7、From these results, the safe operating frequencies for all the devices under high d i l d t conditions was estimated. These estimates were confirmed by experimentally stressing the devices under high d i l d t repet

8、itive operation. I. INTRODUCTION ECENT innovations in semiconductor device designs R and advances in manufacturing technologies have helped evolve high-power thyristors. These devices are designed to operate in a con

9、tinuous mode for applications such as ac- to-dc power conversion and motor drives. Until recently, their application to high-power pulse switching was mostly unknown. One of the main reasons that has discouraged the u

10、se of thyristors for high-speed, high-energy switching is their low d i l d t rating. The limiting value of the d i l d t before damage occurs is related to the size of the initial turn-on area and the spreading vel

11、ocity [I]. Recent experimental results presented in [2]-[4] show that with increased gate device, SCR's and GTO's having highly interdigitated gate-cathode structures can reliably operate under high d i l d t

12、 conditions on a single-shot basis. Previously, SCR's have also been used for repetitive switching of 1 kA, 10 ps wide pulses having a d i l d t of about 10 000 Alps, at 500 and 800 Hz for a 10 h period [SI. It i

13、s reported in [6] that GTO modules (five devices in series) can block 11.5 kV and switch 4.5 kA pulses having a dildt of 2500 A/ks at frequencies of 100 Hz. Asymmetric devices, such as the ASCR's in a stack assis

14、ted by saturable inductors, have Manuscript received August 6, 1991; revised July 16, 1993. V. A. Sankaran is with Ford Research Laboratory, Dearbom, M1. J. L. Hudgins is with the Department of Electrical and Computer

15、Engineer- W. M. Portnoy is with Texas Technical University, Lubbock, TX. IEEE Log Number 92 13643. ing, University of South Carolina, Columbia, SC 29208. shown the potential to repetitively switch high-current pulses w

16、ith d i / d t of about 2000 Alps, on the order of kilohertz [7]. Under high d i l d t conditions the junction temperatures can vary rapidly in high-power devices (-106“C/s) [8]. The failure of these devices under t

17、hese conditions is normally thermal in nature. It has been reported [9], that the temperature of destruction due to a tum-on d i l d t failure is in the range of I 100-13OO0C, below the melting point of silicon (1415

18、°C). The rise in average temperature is therefore completely inade- quate as a measure of device applicability for pulse-switching applications. Since a simple experimental technique is not available to measure

19、the instantaneous temperature rise, the spatio-temporal distribution of temperatures in the devices has to be estimated using computer-aided techniques. In this paper, the high d i l d t single-shot experimental re-

20、 sults are given in brief. A qualitative physical model is then proposed to explain the experimental results, which are presented in detail elsewhere [3]. Next, the results from the thermal analysis using FEM, given i

21、n detail in [lo], are briefly presented. The particulars of the experimental arrangement for the repetitive testing of the devices, results from these experi- ments, and their correlation with the numerical prediction

22、s are given in the discussion. 11. SINGLE-SHOT EXPERIMENTS Inverter-grade SCR's with the amplifying gate (unshorted device) and without the amplifying gate (shorted device) were used for experimental studies to d

23、etermine the role of the amplifying gate during the turn-on processes of the device. The SCR's used for the tests were symmetric with involute gate-cathode structures. They were rated for a forward and reverse bl

24、ocking voltage of 2.4 kV (at 25°C) and 2.2. kV (at 125°C). The experimental details and results are fully presented elsewhere [3]. The experimental arrangement and the results are given in brief below. The

25、devices were electrically characterized initially and recharacterized after testing in a type E pulse-forming network (PFN) that has a total impedance of 0.1 0. This network delivers a 15 kA, 10 ps wide pulse when cha

26、rged to a voltage of 2.5 kV. The di/dt of this 15-kA pulse is 125000 Alps. The gate trigger used for switching the SCR's was a 100 A, 500 ns trapezoidal current pulse. The di/dt of the gate pulse was 980 Alps. T

27、he unshorted devices failed while switching a peak anode current of 10.5 kA at a d i l d t of about 26000 Alps in a PFN 0885-8993/93$03.00 0 1993 IEEE SANKARAN et al.: PULSE-SWITCHING CHARACTERISTICS OF THYRISTORS 34

28、9 Amplifying Pilot gate Cathode contact gate contact Fig. 4. Cross-sectional view of the unshorted device c I A I CHI Fig. 6. Typical IC (CHI), (CH2) and power loss (MULT) of the unshorted device. C H I 4 0 A/d

29、iv, CH2-20 V/div, MULT4096 W/div. Time base-100 ns/div. Cathode contact Pilot gate contact I ' I /Main cathode areas I n I2 I I Main IA I P Igate current ( 1 ~ ) and the increase in the gate-cathode voltag

30、e (VGK), shown in Fig. 6, corresponds in time, to the pilot anode current flow. This supports the above suggestion that the anode current is initially forced to flow through a small area (high resistance) near the

31、pilot-gate contact. Therefore the current density during phase I and phase I1 is very high and leads to a considerable increase in the local temperature. It was reported earlier in [9] that failure temperature of the

32、 device is about 1200°C. Based on this the conduction area and the current density for the failure of the device can be estimated as follows. f i e adiabatic heat energy of dissipation in a volume can be mathem

33、atically related to the temperature rise in the volume as given below. Fig. 5. Cross-sectional view of the shorted device. the p-base by the n+ emitter with a certain emitter injection taken for this process is called t

34、he transit time) and accumulate near the depletion region. This negative charge accumulation leads to injection of holes from the anode. At this time the device turns on after a certain delay, dictated by the P-base

35、transit time [ll], and the pilot anode current (2) begins to flow through a small region near the pilot gate contact as shown in Fig. 4. This flow of pilot anode current corresponds to the initial sharp rise in the an

36、ode current waveform (phase I) shown in Fig. 1. The device then goes into phase 11, during efficiency. These electrons traverse through the p-base (time E = MC,(AT) (1) where E is the energy dissipated in the volume,

37、M is the mass of the volume, c, is the heat capacity (specific heat at constant pressure) of the material, and AT is the temperature rise in the volume. Equation (1) can be modified as: E = pVC,(AT) (2) which the an

38、ode current remains fairly constant, suggesting that the resistance of the region has reached its lower limit. This is because the pilot anode current (2) takes a finite time to traverse through the p-base laterally a

39、nd become the gate where p is the mass density of the material and V is the volume of the material = area A x thickness h. Therefore, the conduction area for failure can be estimated as current for the main cathode ar

40、ea. As a result, the n+ emitters start to inject electrons, which traverse the p-base vertically and after a certain finite time (transit time of the p-base) (3) reach the region. The time taken by the above said Sp

41、ecific heat is a function of temperature, but Saturates at about 140°C. Since the failure temperature is 1000°C, the value of values for the properties of silicon used in the calculations are given below. pro

42、cesses is the reason for observing this characteristic phase to the switching delay, suggesting that the p-base transit time is responsible. Once the main cathode region tums on, the resistance of the device decreases

43、and the anode current begins The width Of the phase 'I is specific heat used for the calculation is its saturated value. The to rise again (transition from phase I1 to phase 111). From here on the plasma-spreading