Download Turn-on behavior of power LTT and light driver modules

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Turn-on behavior of power LTT and light driver modules
A.A.Khapugin1, V.A.Martynenko1, A.V. Plotnikov1,
A.V.Konyukhov2, G.T. Mikaelyan3, S.N.Sokolov3
1
2
«Electrovypryamitel» JSC, Proletarskaya str., 126, 430001, Saransk, Russia,
Tel: +7-8342-48-07-33 Fax: +7-8342-48-07-33, Email: [email protected]
«The V.I. Lenin All-Russian Electrotechnical Institute», Krasnokazarmennaya str., 12,
111250, Moscow, Russia, Tel. +7-495-36-19-567, Fax: +7-495-36-19-407, Email:
[email protected]
3
«Inject» JOSC RME» , pr. 50 let Oktyabrya, 101, 410052, Saratov, Russia,
Tel. +7-8452-748140, Fax: +7-8452-437115, Email: [email protected]
Topics: Power Semiconductors
Preference: Poster Presentation
Abstract
This report presents turn-on characteristics of high voltage power Light Triggered Thyristors
(LTTs) and information about new light control drivers for different applications.
1. Introduction
High voltage LTTs are most perspective power switches for high power commutation in
megawatt range. These power semiconductors are now available with current up to 3500A
and voltage up to 8000V. They are controlled with infrared light pulses of some tens mW,
have excellent turn-on characteristics, low on-state and switching losses. Narrow dispersion
of td, VTM, Qrr enables parallel and series connection of components and realization of high
power systems in GW range, for example HVDC. In addition, LTTs can be used in pulse
power engineering instead of gas-filled tubes and vacuum dischargers.
This report presents investigation results of turn-on behavior of power LTTs with silicon
structure diameter 90 and 100 mm, and the development results of light drivers on the base
of laser diodes for different LTT applications.
2. Fiber optics light emitting diode module
Light absorption in silicon was investigated earlier [1,2], as well as LTT turn-on delay time
depending on wave length. It was shown that optimum wave lengths for LTT turn-on are 9501050 nm. Laser diodes and drivers were developed for this wave length range.
Laser diodes were made on the base of semiconductor MQW heterostructure type
Al0.3Ga0.7As/GaAs, grown by means of MOCVD gas-phase epitaxy. Laser diode has light
emitting area of 50 μm width.
Light emitter (Fig. 1) was developed in compact metal-glass case that contains laser diode
and feedback silicon photodiode (Si-PIN) for output optical power monitoring. Light output
from case occurs through multimode quartz light fiber with core diameter of 200 μm, coating
diameter of 220 μm. Light fiber has optical interface type ST at opposite end for connection
of LTT control light fiber
Fig. 1. Laser diode (photo)
1 – case
2 – light fiber in core
3 – optical interface type ST
Fig.2. Laser diode emission spectrum
by +70ºC and dependence of emission
peak from temperature
Fig. 2 shows laser diode emission spectrum, measured in pulse mode (f = 6000 Hz, tp = 10
μs) at -45ºC, +20ºC, +70ºC by means of MOPC-G spectrometer. Fig. 3 shows typical light
power - current characteristic of laser diode, measured at +20ºC, +40ºC and +70ºC in pulse
mode.
Fig. 4 shows photo-current of integrated Si-PiN diode in dependence on laser diode pump
current. It can be seen from fig.4 that operational area of Si-PiN diode transmission
characteristic has linear segment, and this linear segment allows monitoring and stabilization
of laser diode output light power by change of ambient temperature.
Fig. 3. Typical light power – current
characteristic of laser diode at
+20ºC, +40ºC, +70ºC
Fig. 4. Photo-current of integrated Si-PiN
diode in dependence on laser diode pump
current at +20ºC, +40ºC, +70ºC
3. Laser driver layout.
Three optical control drivers were developed on the base of these laser diodes, for pulse
power applications, power rectifiers, inverters and AC switches.
Basic characteristics of control drivers are shown in the table.
Parameter
type 1
type 2
type 3
The number of light output channels
1
1
1
Output light wave length, nm
900-980
900-980
950-1000
Output light pulse power, mW
50-300
50-300
200-300
Average light power, no more, mW
2.5
25
300
Output pulse duration, μs
10-50
10-50
0.2-∞
Output light pulse frequency, Hz
50
6000
Continuous
Operation temperature range, ºC
+5…+40
+5…+40
+5…+70
Case dimensions, mm
80x55x25
140x64x30
114x35x30
Power supply and control interface
D-SUB-
D-SUB-9F
IDC-10
Input control signal
9F
Positive front of CMOS logic
Recommended driver applications: type 1 – pulse current commutation, type 2 – rectifiers
and inverters, type 3– AC current control. Driver type 3 is multi-purpose driver and can be
used in pulse applications, DC-AC and AC-DC converters, besides of AC current control.
Fig.5 shows functional electrical circuit of optical driver type 2.
Fig. 5. Functional electrical circuit of optical driver type 2.
Input pulses of necessary duration (10-400 μs) and CMOS-logic level enters to
MOSFET driver input. The driver is designed for conversion of CMOS-level into driving
pulses of transistor gate. When transistor is in on-state, current flows through laser diode.
This current is limited by resistor R1. Laser emission enters to light fiber, one part of that gets
into feedback detector and is used for diagnostics. Diagnostics comparators recognize
minimal and maximal light power levels. The scaling is carried out by means of resistor R2,
and output triggers memorize power level of passed pulse. In that way two signals are
produced, and control system evaluates emission power according to states log. “0” or log.
“1”, when PL > Pmin , PL > Pmax. Output power can decrease during long time operation of
laser diodes due to aging. The control system can recognize laser diode aging by means of
diagnostics and switch the reserve driver on without stopping of power converter.
4. Experimental results
Turn-on characteristics of high voltage power LTT PP with blocking capacity of 5000V for
pulse applications and 8000V Phase Control LTT were investigated by means of these
drivers in different measurement conditions. Fig. 6 shows turn-on delay time of 5000V LTT in
dependence on laser diode wave length (λ) for PLM = 200 mW and direct blocking voltage VD
= 100V. Solid line – calculation, points – measurement results.
Fig. 7 shows turn-on delay time of 5000V LTT in dependence on direct blocking voltage for
PLM = 200 mW, λ = 880 nm and λ = 980 nm. It can be seen that more close to optimum wave
length 980 nm shows lower turn-on delay times in the whole of voltage range. Additionally,
turn-on delay time for λ = 980 nm has weak dependence on anode voltage (tgd ≈ 0.5 μs by VD
= 4000V and tgd ≈ 1.0 μs by VD = 100V). For λ = 880 nm turn-on delay time increases sharply
when anode voltage decreases (tgd = 0.8 μs by VD = 4000V and tgd = 2.7 μs by VD = 100V).
The investigation has shown also that turn-on losses power of LTT PP decreases by growth
of wave length from 880 up to 980 nm.
Fig. 6. Turn-on delay time of LTT PP
in dependence on laser diode wave
length for PLM = 200 mW, VD = 100V.
Solid line – calculation, points –
measurement results
Fig. 7. Turn-on delay time of LTT PP
in dependence on anode voltage and laser
diode wave length for PLM = 100 and 200 mW
Fig. 8 and 9 show turn-on delay times of 5000V and 8000V LTTs in dependence on light
power of new optical drivers for wave length 980 nm. It can be seen that LTT (5000V) turnson more rapidly than LTT(8000V) by all mentioned values of PLM and VD, due to greater nbase width of LTT in comparison with that of LTT PP.
VD=2500V VD=4000V
Fig. 8. Turn-on delay time of LTT PP
(5000V) in dependence on light power
and anode voltage for λ = 980 nm
VD=2500V VD=4000V
Fig. 9. Turn-on delay time of LTT (8000V)
in dependence on light power and anode
voltage for λ = 980 nm
Fig. 10. High voltage power block with six LTT PP (5000V) in series, for pulse applications up to 120
kA with 6-canal control plate on the base of optical driver type 1
4. Conclusion
Turn-on delay time dependencies of high voltage LTTs on optical emission wave length and
power, as well as on direct blocking voltage, were calculated and measured. These
dependencies can be useful for definition of LTT operation mode.
Presented in this article optical control drivers were successfully tested and today they are
applicated as main elements of control systems for modern LTTs. Fig. 10 illustrates one
application example of new LTTs and optical control drivers – high voltage pulse current
commutation unit for current pulse commutation up to 120 kA complete with 6-channel
control plate on the base of optical driver type 1. Operation capability of system was tested
by 5000 current commutations.
References
[1] V. Martynenko, A. Khapugin, A. Grishanin et al. The development of power thyristors with
direct control of lighting and protection functions // Power Electronics, №5, 2009. pp. 8-14.
[2] A.V.Grishanin, V.A.Martynenko, A.A.Khapugin et al., Novel Light Triggered Thyristors for
Phase Control and Pulsed Power Applications, Bodo´s Power systems June 2012, 36-41
(2012)