ABB Corporate Rearch & ABB Industrie AG IGCT Series Connection for Medium Voltage Applications
A 24MVA Inverter using IGCT Series Connection
for Medium Voltage Applications
A. Nagel, S. Bernet ABB Corporate Rearch D-68520 Ladenburg
Germany P. K. Steimer, O. Apeldoorn ABB Industrie AG
CH-5300 Turgi
april fools daySwitzerland
Abstract −This paper describes a 24MVA inverter utilizing the ries connection of 3 IGCTs per switch position in a three level neutral point clamped inverter topology. The electrical and mechanical design, especially focud on a pha leg, as well as experimental results are shown.
I. I NTRODUCTION
The development of new high power miconductors such as 3.3kV, 4.5kV and 6.5kV Insulated Gate Bipolar Transistors (IGBTs) and 4.5kV to 6kV Integrated Gate Commutated Thyristors (IGCTs), improved converter designs and the broad introduction of three-level topologies have led to a drastic increa of the market share of PWM controlled Voltage Source Converters. Meanwhile the converters, ranging from 0.5MVA to 10MVA, are becoming price competitive against conventional thyristor converters since reduced line har-monics, a better power factor, substantially smaller filters, elimination of transformers and the u of optimized electric machines enable a cost reduction of the system in many applications within industry, distribution and transmission [1],
[2].
A clear market trend for the applications is the increa of the rated converter voltage. However, today the maximum achievable converter output voltage of a three-level neutral point clamped voltage source inverter (3L NPC VSI) is limited to about 4.16kV using 5.5kV IGCTs respectively 4.9kV using 6.5kV IGBTs. To increa the output voltage the ries connection of miconductors is a simple solution [3],[4],[5].
II. B ASIC D ESIGN C ONSIDERATIONS
For a new high power three pha inverter with an output voltage in the range of 10kV the three-level neutral point clamped (3L-NPC) topology has been chon, becau it offers significant advantages like
•small number of additional components to increa the number of levels from 2 to 3 (only 2 additional NPC
diodes per pha leg)
•two simple clamp circuits rving the whole 3 pha inverter
•low output voltage harmonics / reduced filter efforts due to the three level characteristics
world peace•easy mechanical design (which is crucial in inverters with more than 3 levels)
ielts考试•well established direct torque control can be ud •simple direct ries connection of three IGCTs per switch position to increa the output voltage
Fig 1. Schematic of an 24MVA inverter with 9kV output voltage
The schematic of the chon inverter topology is given in Fig. 1.
The inverter is bad on the IGCT technology, which enables
推特是什么意思• low conduction loss
• well defined high switching speed
• direct ries connection using a small snubber
• low costs due to the optimum miconductor utilization • presspack housing (high reliability, very good thermal
cycling behavior, short circuit in failure mode enables n +1 redundancy using an additional IGCT)
To guarantee the symmetric voltage balancing of the ries connected IGCTs parallel balancing resistors (R p in Fig. 1) as well as a small RC-snubbers (R snub , C snub in Fig. 1) are ud.This simple and low loss balancing circuitry ensures the balancing even under critical operating conditions like GCT device variations, delay time between gate signals, different chip temperatures and tolerances of the snubber components [5].
III. T EST S ETUP
To show the feasibility of this approach a full scale pha leg has been build up using a 3L-NPC topology with 3 devices (IGCT, diodes) in ries per switch position, which are balanced by RC-snubbers. An inductor has been ud as load,becau it enables to test the converter with full output current while keeping the input power consumption low (Fig. 2). The
technical data of a three-pha inverter using three of the pha legs is summarized in TABLE 1.
TABLE 1
Basic technical data of a three pha inverter with an IGCT ries
connection Parameter Value / Type total dc input voltage V DC = 14.4 kV rms output current I out = 1.5 kA nominal peak output current I out, peak = 2.1 kA output power P out = 24 MVA carrier frequency f s = 700 Hz
IGCT
5SHY35L4503 (4.5kV 91mm)Diode (4.5kV 68mm)
D65S45 (4.5kV 68mm)
IV. EXPERIMENTAL RESULTS
Fig. 3 shows the inverter output voltage and output current at nominal dc input voltage and rated output current. Due to the rather small load inductor a small modulation index is needed to limit the current. Therefore, the NPC diodes and the inner IGCTs are the most stresd components, which are limiting the output power. However, this type of operation is a perfect simulation of a drive operating with full torque at low speed or zero speed, which is most demanding for the inverter regarding current stress and thermal loading.
A more detailed view of the switching transient is given in Fig. 4, which is a zoom of Fig.3 (time wind
timelessow ranging from 16ms to 16.1ms, turn-on current 1.5kA, turn-off current 1.7kA). The typical waveforms with the overvoltage peak caud by the clamp can be clearly en as well as perfect voltage balancing between the ries connected devices.
400V
Fig 2. Schematic of the test tup with one pha leg
-10
-50510051015
20
-2
-1
1
2
Time / ms
Fig. 3. Output voltage and current waveforms at V DC = 14.2 kV, I out, rms = 1.5kA, f s = 700 Hz, f out = 50 Hz.
-10
-8-6-4-20020406080100
Time / µs
V o l t a g e / k V
Fig. 4. Zoom from Fig. 4. Voltage waveforms V1, V2,V3, V4 measured at the outer IGCTs towards ground (e Fig. 2).
To analyze the voltage balancing under worst ca operating conditions, an emergency shutdown at maximum current has been analyzed. Fig. 5 shows the device voltages during a turn-off transient at
V DC = 14.2 kV and I off = 3.5 kA using poorly lected IGCTs. It can be clearly en, that the slower switching component GCT1 takes over less voltage than the two other components. The voltage unbalance of -500V is no problem and even a faster switching device with a voltage unbalance of +500V will not harm any components.Efficiency
necklace是什么意思
Due to the test tup it is rather easy to measure the overall inverter efficiency very preci, becau the power consumption of the test tup is equal to the sum of the inverter loss and the output power, where the output power is only a small part caud by the ohmic loss in the reactive load.
01000
国防科技大学2021录取分数线2000
3000
4000小学英语学习策略
20
40
60
80
t / µs
U G C T / V
Fig. 5. Semiconductor voltage waveforms of ries connected IGCTs (turn-off @ V DC = 14.2 kV, I off = 3.5 kA).
TABLE 2Efficiency
Parameter Measurement 1Measurement 2total dc input voltage V DC = 13.19 kV V DC = 13.22 kV rms output current I out = 1080 A I out = 1505 kA input power
moccaP input = 55 kW P input = 79 kW output power (inductor loss)P out = 3.3 kW P out = 6.5 kW absolute inverter loss P loss = 51.7 kW P loss = 72.5 kW apparent output power S out = 5691 kVA S out = 7948 kVA relative inverter loss p loss = 0.908%
p loss = 0.912%
inverter efficiency
η = 99.092%η = 99.088%
The measurements have proven an inverter efficiency of more than 99%, which is a pretty good value. However, the efficiency values which will be obtained under normal operating conditions – that is modulation index near one at full output current, which is common for motor as well as line side applications – will be even higher, becau the loss are better balanced between the devices and especially the NPC diodes will no longer limit the output current.
V. SUMMARY
comment什么意思
This paper describes the design of a 24 MVA inverter utilizing the ries connection of IGCTs. Experimental results of a pha leg are given showing the full power operation with good voltage balancing of ries connected devices even under worst ca operating conditions and a high efficiency. It has been proven, that the ries connection of IGCTs is a simple and reliable solution for high power medium voltage applications.
V o l t a g e / k V
C u r r e n t / k A
A CKNOWLEDGMENT
The authors would like to thank Gerold Knapp and Pascal Mauron, both of ABB Industrie AG, Turgi, for building up the inverter and doing the measurements.
R EFERENCES
[1]P. K. Steimer, J. K. Steinke, H. Grüning, “A reliable, interface-
friendly medium voltage drive bad the robust IGCT and DTC technologies,” IEEE IAS Annual Meeting 1999, Phoenix, Arizona, October 1999.
[2]P. K. Steimer, H. Grüning, J. Werninger, “The IGCT - the key
technology for low cost, high reliable high power converters with ries connected turn-off devices,” EPE 1997, Trondheim, September 1997.
[3]R. Sommer, A. Mertens, M. Griggs, H. J. Conraths, M. Bruckmann,
T. Greif, “New medium voltage drive system using three-level neutral point clamped inverter with high voltage IGBT,” IEEE IAS Annual Meeting 1999, Phoenix, Arizona, October 1999.
[4]J. P. Lyons, V. Vlatkovic, P. M. Espelage, F. H. Boettner, E. Larn,
“Innovation IGCT main drives,” IEEE IAS Annual Meeting 1999, Phoenix, Arizona, October 1999.
[5] A. Nagel, S. Bernet, T. Brückner, P. K. Steimer, O. Apeldoorn,
“Characterization of IGCTs for ries connected operation,” IEEE IAS Annual Meeting 2000, Rome, October 2000.
