application of medium voltage converters for a … of 4-level inverter phaselegs using igbt- and...

May 2004May 2004

APCG / 4JK_001_MeVoCo_Traction-Test-Benches_00EN.ppt

Application ofMedium Voltage Converters

for a Traction Test Bench

Dr. Roland Jakob

205.2004 APCG / 4JK 001 MeVoCo Traction-Test-Benches 00EN.PPT / Dr.R.JAKOB / Be

Medium Voltage Drive System forTest Bench and High Speed ApplicationsMedium Voltage Drive System forTest Bench and High Speed Applications

Application of Medium VoltageConverters for a Traction Test Bench

Content

� 4-Level Floating Capacitor Topology

� 4-Level Inverter Reduces Motor Stress

� Active Front End Application

� Gear Box Simulation Test Bench

� Locomotive Traction- and Auxiliary Drive Test Bench

� Block Diagram of Total Locomotive Test Bench using 4-Level IGBT Inverters connected to DC-Bus

� High Speed Medium Voltage Gearless Compressor Drive

� Conclusion


Application of Medium Voltage Converters for a Traction Test Bench

Main features:� Applied for MV-Inverter, Active Front End,

DC-Chopper� Series connection of three IGBT floating

capacitor cells with shared capacitors allow generation of medium voltage wave shape with low harmonics

� Average DC-voltage [VD] sharing of 2/3 VD and 1/3 VD by each floating capacitor

� Pulse pattern generation with shifted carriers by 120° allowing natural voltage sharing

� Output modulation frequency 3 times higher than IGBT switching frequency. This is the basis of “High speed drives” providing more than 300 Hz fundamental motor frequency to achieve 20.000 rpm.

� 4500 V IGBT modules with possible current ratings of 200 A / 400 A / 600 A or 900 A to achieve 4160 V AC output voltage in 4-level topology

� Using 6500 V IGBT’s modules, a max. motor voltage of 6600 V can be achieved.

4-Level Floating Capacitor Topology

+

DC-Busbar

AC

IGBT-FloatingCapacitorCell

SharedCapacitor

IGBT-Module

+

Electrical schematic of one 4-level inverter phaseleg consistíng of 3 IGBT-Floating capacitor cells



� Reduction of motor insulation stress because of lower dv/dt values and peak voltages

� Lower common mode voltage reduce possible, destructive bearing current

� Comparison of 2-level and 4-level inverter:� Peak overvoltage reduced� Reduced Filter losses� Common mode voltage reduced

4-Level Inverter Reduce Motor Stress

2-level inverterTypical waveforms of phase voltage and common mode voltage to DC link middle point (1 pu = 0.5 VDC). Phase current in Amp. below

4-level inverterTypical waveforms of phase voltage and common mode voltage to DC link middle point (1 pu = 0.5 VDC). Phase current in Amp. below

-1

-0.5

0

0.5

1

phas

e vo

ltage

[pu]

-1

-0.5

0

0.5

1

com

mon

mod

e vo

lt. [p

u]

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016

-500

0

500

phas

e cu

rren

t [A]

time [s]

-1

-0.5

0

0.5

1

phas

evo

ltage

[pu]

-1

-0.5

0

0.5

1

com

mon

mod

e vo

lt. [p

u]

0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016

-500

0

500

phas

ecu

rren

t[A]

time [s]



� Very low current and voltage harmonics for both, motor and AFE� Limits of all standards, including IEEE 519, are clearly observed� IGBT’s operating with 900 Hz create 4-level output voltage modulated with 2700 Hz

(see secondary voltage in left picture)

Active Front End Application (AFE) using 4-Level Topology

Primary & secondary voltage and current wave shapes.

Harmonic analysis of primary voltage, THD = 0.7

Harmonic analysis of current, THD = 2.2 %

-20

-10

0

10

20

prim

ary

L-L

volta

ge [k

V]

-2

0

2

sec.

L-N

pha

se v

olta

ge [k

V]

0.19 0.195 0.2 0.205 0.21 0.215 0.22

-500

0

500

sec.

pha

se c

urre

nt [A

]

time [s] 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000

0.05

0.1

0.15

0.2

0.25

0.3

0.35

frequency [Hz]

line

volta

ge a

mpl

itude

u_

net_

os[%

]

THD of primary L-L voltage: 0.68896 %

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 100000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

frequency [Hz]

curr

ent a

mpl

itude

i_os

[%]

THD of secondary phase current: 2.1676 %



� Simulation of typical and worst case loads for high power gear boxes.

� Control of speed & torque in a closed loop for energy.

� Both drives may operate as motor/generator, in all 4 quadrants including field weakening with high dynamics.

� Active Front End provide low voltage and current harmonics and controls energy flow in both directions.

Gear Box Simulation Test Bench

Gear Box SimulationTest Bench, 2 x 5 MWBack-to-Back Configuration

ActiveFront End

Drive 1

DynamicBrake

Drive 2

PC

T

N

T

N

AC Input

Transformerwith extraimpedance

DC-BUS 6 KV

4 KV AC 4 KV AC

Unit under Test

M~

M~

Gear Box

Moni-toring



Locomotive Traction- and Auxiliary Drive Test Bench

Our customer is dealing with the development of traction motors. Existing and future Generators and Motors will be tested on availability, reliability, efficiency, lifetime, temperature etc.



ALSTOM provide test stand for locomotive utilities with DC-bus drive systems, operating energy in close loop, controlling speed, torque, energy in both directions. AFE provide low mains harmonics, to meet IEEE 519 requirements.

Block Diagram of Total Locomotive Test Bench using 4-Level IGBT Inverters connected to DC Bus

AC AC DC

DC

AC

AC AC DC

DC

DC

AC DC

DC

AC

AC

DC

AC

AC

DC

DC

ACGM

Inverter

DC

DC

DCDC

AC

DC

AC

Location 13 Location 4Location 2Location 1

Activefrontend

2400 V

Mains13.2 kV

DC-Bus 4 KV

Ind.-Motor

A(Test)

Ind.-Motor

F

DC-Motor

B(Test)

Ind.-Motor

A(Test)

Ind.-Motor

F

DC-Motor

B(Test)

Syn.-Motor

D(Test)

DC-Motor

E(Test)

Syn.-Motor

C(Test)

Ind.-Motor

F

Ind.-Motor

A(Test)

In.-Motor

(Test)

DC-Motor

J

Syn.-Motor

G

Syn.-Motor

C(Test)

DC

AC

ACAC

Location 3

DC

AC

DCACorDC

Loc. 1 & 2 Loc. 3 Loc. 4 Loc. 13 AC & DC traction motors Main Alternator Set Main and Auxiliary Alternator Set AC traction motor controlled

by inverter



� Electrical, gearless gas compressor drives can improve overall efficiency by 5 %

� High power, high speed induction motors are using magnetic bearings

� Motor dates require inverter range between 5 MVA and 30 MVA, 6 kV AC

� Using 6.5 kV IGBT in 4-level topology, the above requirements can be achieved without using sinusoidal filters, because 300 Hz motor frequency can be modulated with low harmonic content.

High Speed Medium Voltage Gearless Compressor Drive

Turn-on behaviour of 6.5 kV IGBT module

Parameters:VCE : 500 V/div PV : 500 kW/divIC : 200 A/div Eoff: 0.5 J/divIG : 5 A/div t : 1 µs/divVD: 4200 V

Turn-on behaviour of 6.5 kV IGBT module

Parameters:VCE : 500 V/div PV : 500 kW/divIC : 200 A/div Eoff: 1 J/divIG : 5 A/div t : 1 µs/divVD: 4200 V



� Low manufacturing cost because of using modules and reusing components for different power ratings

� Clear mechanical design reduce time for assembling and test

� Standard test procedure for basic drives guaranties high availability and reliability

� Customer witness tests for total AFE and drive systems allow presettings of control in the factory, to reduce time for final commissioning at customer site

Assembling and Testing

Assembling of 4-level inverter phaselegs using IGBT- and capacitor modules

Customer witness tests of an AFE based on 4-level topology.



� 4-Level Topology with floating capacitors with clear advantages for high power Test Benches and High Speed Applications.

� Typical “Gear Box” Test Bench with 2 x 5 MW, back-to-back, Active Front End and dynamic breaking is introduced.

� Special System Test Bench for Locomotive Traction- and Auxiliary Drives uses all features of this inverter system.

� 4-Level Topology meets all aspects of medium voltage IGBT drives� high fundamental frequency, � 6600 V motor voltage with existing IGBT’s, � low motor stress for insulation and bearings, � low harmonics for motor torque and AFE net voltage.

Conclusion

www.powerconv.alstom.com

application of medium voltage converters for a … of 4-level inverter phaselegs using igbt- and...

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