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Power Converter Course, Warrington

12.05.2005

High Power Active Devices

Eric Carroll, ABB Switzerland

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INTRODUCTION

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Electronic Switches

ThyristorCan be turned on by gate signal but can only be turned off by reversal of the anode current

Gate Turn-Off Thyristor (GTO)Can be turned on and off by the gate signal but requires large

capacitor (snubber) across device to limit dv/dt

Transistor (transitional resistor)

Can be turned on and off by the gate (or base) signal but has high conduction losses (its an amplifier, not a switch)

Integrated Gate Commutated Thyristor (IGCT)Can be turned on and off by the gate signal, has low conduction loss and requires no dv/dt snubber

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Available Self-Commutated Semiconductor Devices

THYRISTORS TRANSISTORSGTO (Gate Turn-Off Thyristor) BIPOLAR TRANSISTOR

MCT (MOS-Controlled Thyristor) DARLINGTON TRANSISTOR

FCTh (Field-Controlled Thyristor) MOSFET

SITh (Static Induction Thyristor) FCT (Field Controlled Transistor)

MTO (MOS Turn-Off Thyristor) SIT (Static Induction Transistor)

EST (Emitter-Switched Thyristor) IEGT (Injection Enhanced(insulated) Gate Transistor)

IGTT (Insulated Gate Turn-off Thyristor) IGBT (Insulated Gate Bipolar Transistor)

IGT (Insulated Gate Thyristor)

IGCT (Integrated Gate-CommutatedThyristor)

Emitter

Collector

Base

P

N

P

N

Anode

Cathode

Gate

P

N

P

Anode

Cathode

Gate

N

P

N

Cathode

Gate

Anode

Emitter

P

N

P

Collector

Base

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High Power Turn-off Devices

Power Semiconductors

Turn-off Devices Thyristors Diodes

Transistors ThyristorsLine commutatedFastBi-directionalPulse

FastLine commutatedAvalanche

DarlingtonsIGBTs

GTOsIGCTs

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Power Semiconductors …

are switches….

VACVDC

….for converting electrical energy

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Turn-on Switches (Thyristors)

Thyristors (PCTs)thyristors produce voltage distortion

in phase control mode

will ultimately be replaced by ToDs, except...

in AC configuration for:

transfer switches

tap changers

line interrupters

V

t

V

t

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World Energy Consumption …

57100

200397

2

6

30

147

3%6%

15%37%

0.1

0

1

10

100

100019

40

1950

1960

1970

1980

1990

2000

2010

2020

2030

Mill

ions

of B

arre

ls/D

ay

total energyelectrification% electrification

Source :Mitsubishi Electric

... drives the need for high power electronics

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Energy trend

By 2020:• Energy consumption will double

• Electricity generation will double

• Electrification of end-consumption will quintuple

Today, only 15% of electricity flows via electronics

Medium Voltage conversion has only been economically possible inthe last 10 years

Power conversion at MV levels set to grow faster than LV (20% p.a.)

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SELF- COMMUTATED INVERTERS

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Basic Topologies

VR

S3

S4

S5

S6

S1

S2

Ls

L

Cclamp

Dclamp

R

FWD6Clamp circuit

IGCT Inverter

S5S3S1

S6S2 S4

VDC

FWD1

IGBT Inverter

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Turn-on waveforms for IGCTs and IGBTs

E I V t dton device load switch

t

t

− ≈ • ∫2

3

2( ). ............. ( )

E t t V I Ion circuit dc load rr− = − • • +( ) ( ) ....( )2 0 2 1

IloadIswitch

IFWD

t0 t3

di/dt|on

Irr

Ipk

ton

Vswitch or L = VDC

t1

Vswitch = f(t)

t2

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DEVICES

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IGBTs

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IGBTs – key features

Transistors with insulated gate

Allow dv/dt and di/dt control via gate signal(losses)

High on-state voltage(transistor)

High turn-on losses (no snubber)

Low gate power requirements(voltage control)

No passives required(independant dv/dt and di/dt control)

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HiPak™ High Power IGBT Modules

AlSiC base-plate & AlN substrate

Voltage Current Type Part Number Vce125°C

VF125°C

Eoff125°C

Eon125°C

Vdc

2500V 1200A Single 5SNA 1200E250100 3.1V 1.8V 1.25J 1.15J 1250V3300V 1200A Single 5SNA 1200E330100 3.8V 2.35V 1.95J 1.89J 1800V3300V 1200A Single 5SNA 1200G330100* 3.8V 2.35V 1.95J 1.89J 1800V6500V 600A Single 5SNA 0600G650100* 4.7V 4.0V 3.5J 4.0J 3600V* High voltage version

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StakPak™ - stackable press-packs (collector side)

StakPak-H4: 2.5 kV/1300 to 3000 A

StakPak-H6: 2.5 kV/ 2000A to 3000 A

StakPak-L2: 4.5 kV/600 to 1000 A

StakPak-J6: 4.5 kV/2000 to 3000 A

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IGBT Press-packsConventional IGBT press-pack:requires tight mechanical tolerances

copper

copper

molybdenum

siliconchip

ceramicinert gas

close-up

base-platesilicon chip

spring washer packcurrent bypass

sub-module frame(polymeric)

module outer frame(fibreglass reinforced polymer)module lid

(copper)

silicon gel

∆x

StakPak™ IGBT press-pack with individual springs:suitable for long stacks with compounded tolerances

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StakPak™ HVDC Valve

Long stacks would require very tight mechanical tolerances to ensure identical force on each chip in each housing:

on assembly

over time

with temperature cycling

with shock and vibration

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IGBT Trends

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IGBT Trends

Higher voltages

Higher Safe Operating Area (SOA)

Softer (controlled) switching

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-20-10

01020

30405060

708090

100110

Time [250 nsec/div]

Ic (A

), Vg

e (V

)

-400-200

0200400

60080010001200

140016001800

20002200

Vce (V)

Vge

Vce

Ic

-150

-125

-100

-75

-50

-25

0

25

50

75

100

125

150

Time [250 nsec/div]

IF (A

)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

2200

2400

VR (V)

VRIF

IGBT Turn-offVcc= 1800V

Ic= 50A RGoff= 33ohm

Ls= 2.4µHTj= 125°C

Diode Turn-offVR= 1800VIF= 100A RGon= 33ohmLs= 2.4µHTj= 125°C

Soft switching: 3.3kV SPT* IGBT/Diode chip-set

* Soft Punch Through

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Soft switching: 8 kV IGBT PT vs SPT

0

10

20

30

40

50

60

70

80

90

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0

time [microseconds]

curr

ent [

A]

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

volta

ge [V

]

conventionalPT device

SPThigh di/dt giving

rise to EMI issues

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3.3kV Diode RBSOA Performance

-300

-250

-200

-150

-100

-50

0

50

100

150

200

250

Time [250 nsec/div]

IF (A

)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

VR (V)

Dynamic Avalanche

Inominal

SSCM

IF = 2 x Inominal

VR

3.3kV/100A Diode RBSOA during Reverse RecoveryVR= 2500V, IF= 200A, di/dt=1000A/µs, Ls= 2.4µH, Tj= 125°C

Peak Power = 0.8 MW/cm2

No clamp, no snubber

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4.5kV IGBT RBSOA Performance

-20

0

20

40

60

80

100

120

140

160

180

200

220

Time [250 nsec/div]

Ic (A

), Vg

e (V

)

-500

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500Vce (V)

Dynamic Avalanche

Inominal

SSCM

Ic = 3 x Inominal

Vge

Vce

4.5kV/40A IGBT RBSOA during Turn-offVcc= 3600V, Ic= 120A, RG= 0ohm, Ls= 12µH, Tj= 125°C

Peak Power = 0.5 MW/cm2

No Clamp, No Snubbers

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6.5kV IGBT RBSOA Performance

-20-10

0102030405060708090

100110120130140

T im e [250 nsec /d iv ]

Ic (A

), Vg

e (V

)

-1000-50005001000150020002500300035004000450050005500600065007000

Vce (V)D ynam ic A va lancheInom ina l

S S C MIc = 2 x Inom ina l

V g e

V ce

6.5kV/2x25A IGBT RBSOA during Turn-offVcc= 4500V, Ic= 100A, RG= 0ohm, Ls= 20µH, Tj= 125°C

Peak Power = 0.25 MW/cm2

No Clamp, No Snubbers

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6.5kV IGBT Short Circuit Performance

0

25

50

75

100

125

150

175

200

225

250

275

300

Time [2 usec/div]

Ic (A

)

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

Vce (V)

Ic > 10 x Inominal

Vce

6.5kV/25A IGBT SCSOA during Short CircuitVcc= 4500V, Icpeak= 290A, VGE= 18V, Ls= 2.4µH, Tj= 25°C

Peak Power = 1.35 MW/cm2

No Clamp, No Snubbers

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3.3kV IGBT Module RBSOA Performance

3.3kV/1200A IGBT module during Turn-off (24 IGBTs)Vcc= 2600V, Ic= 5000A, RG= 1.5ohm, Ls= 280nH, Tj= 125°C

No clamp, no snubbers

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IGCTs

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IGCTs – key features

Thyristor with integrated gate unit

Low on-state voltage(thyristor)

Negligible turn-on losses(turn-on snubber)

No explosive failures(fault current limitation by circuit)

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Principle of IGCT Operation

P

N

P

N

Anode

Cathode

GateIAK

IGK

P

N

P

N

Anode

Cathode

Gate

- VGK

VAK

Conducting Thyristor Blocking Transistor

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IGCT turn-off

4

1

Ia (kA)

Vdm

Tj = 90°C

Itgq

4

3

2

1

0

-10

-20

Vg (V)

2

3

0

anode voltage Vd

anode currentIa

gate voltage Vg

thyristor transistorx

starts to block

Vd (kV)

2015 3025 35 t (µ s)

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General turn-on waveforms for IGCTs and IGBTsEon-circuit

IloadIFWD

t0 t3

di/dton

Ipk

ton

Vswitch or L = VDC

t1

Vswitch = f(t)

t2

Iswitch

Eon-device

IRR

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1500 A IGBT turning on 1000 A from 3000 V

IC [250 A/div]

VCE [500 V/div]

833 A/µs

time [ 2 µs/div]

EON = 7.4 WS

EON deviceEON circuit

EON-circuit = 4.1 Ws

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4000 A IGCT turning on 1000 A from 3000 V

0

500

1000

1500

2000

2500

3000

3500

0.E+00 5.E-06 1.E-05 2.E-05 2.E-05 3.E-05

t [s]

VAK,

I A, [

V, A

]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Eon

[Ws]

1340 A/µs

E t t V I Ion circuit dc load rr− = − • • +( ) ( ) ....( )2 0 2 1

EON-device

=1.5 µs • 3000V • 1900 A /2 = 4.3 Ws

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Adjustment of dv/dt by lifetime control

0

1000

2000

3000

4000

6 8 10 12 14

t [µs]

I A, V

AK, [

A, V

]

medium lifetimelow lifetimehigh lifetime

IA

VAK

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Low inductance housing

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4 kA/4.5 kV IGCTs

visible LEDindicators

Status Feedback Command Signal

optical fibre connectors

power supply connection

all copper housing

IGCT

GCT

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30 MW IGCT Power Management

15 + 15 MW 3-Level Back-to-Back Converterfor three-phase to single-phase conversion Converter efficiency = 99.2%

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4 kA/4.5 kV IGCT at 25 kHz in burst mode

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0.E+00 2.E-04 4.E-04 6.E-04 8.E-04 1.E-03

time (s)

Anod

e vo

ltage

and

cur

rent

(V, A

)

vI

VDC start = 3.5 kV VDM peak = 4.5 kV ITGQ peak = 4 kATJ start = 25 °C α = 0.5

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IGCT Outlook

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IGDT

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Structure of IGDT – Integrated Gate Dual Transistor

K

A

G1

G2

G1

G2

Dual Gate Turn-off Thyristor

G1

G2PNPN

K

AA

K

G1

G2

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91 mm 4.5 kV IGDT turn-off

Dual-gate IGCT @ 85°C - gates triggered simultaneouslyVDC = 2.8 kVITGQ = 3.3 kAVDRM = 4.5 kVVTM = 2.1 V @ 4 kA/125°C

no tail current

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IGDT Series connection: leakage current reduction

(V DC = 2800 V)

0

20

40

60

80

100

120

140

75 100 125 150 175

T J (°C)

I D(m

A)

anode gate floating(no bias)

anode gate with 20V reverse biased

140°C

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91 mm 4.5 kV IGDT - Leakage current control

VGK= -20V, TJ = 25°C

05

101520253035

0 5 10 15 20 25IGA Anode gate current [mA]

500V1000V1500V2000V2400V

I D- a

node

leak

age

curr

ent [

mA

]

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IGDT anode gate control of tail currentIDUT2 V1 VG1 VG2

0.0

0.2

0.4

0.6

0.8

1.0

kA

0.0

0.5

1.0

1.5

2.0

2.5

kV

1.4

1.6

1.8

2.0

2.2

2.4V

300 320 340

µs

IDUT2 V1 VG1 VG2

0.0

0.2

0.4

0.6

0.8

1.0

kA

0.0

0.5

1.0

1.5

2.0

2.5

kV

1.4

1.6

1.8

2.0

2.2

2.4V

300 320 340

µs

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Increased SOA

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IGCT SOA improvement at 4.5 kV

38 mm reverse conductingTODAY

250 kW/cm2

250 kW/cm2

TOMORROW

1000 kW/cm2

400 kW/cm2

91 mm asymmetric

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6.5 kA @ 2.8 kVDC on 91 mm wafer

0

1000

2000

3000

4000

5000

6000

7000

1 3 5 7 9

t [µs]

VAK,

I T [V

. A]

-25

-20

-15

-10

-5

0

5

V GK [

V]

Snubberless turn-off Tj = 125°C, VD = 2.8kV

IT

VAK

Developmental 4” 4.5 kV IGCT with improved GU and silicon design allowing 50% SOA improvement

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1.3 kA @ 2.8 kVDC on 38 mm RC wafer

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

-3 -2 -1 0 1 2 3 4 5 6 7

t [µs]

V AK [k

V], P

[MW

]

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

I off [

kA]

VAK

P

Ioff

TJ = 115°C

Developmental 2” 4.5 kV RC_IGCT with improved GU and silicon design allowing 300% SOA improvement

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10 kV IGCT

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Engineering Sample of 68 mm 10 kV IGCT

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Forward Blocking Characteristics at 25°C

magnified by factor 1000:1 µA / div

(<17 µA @ 10 kV, 25°C)

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Forward Blocking Characteristics at 125°C

(<14 mA @ 7 kV, 125°C)

(8-13 mA @ 6 kV, 125°C, PL=50W-80W ( 5%-10% of PRP)

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Turn-off Waveforms (SOA)

Operating conditions:VDC= 7kV, IA = 1000A, Tj = 85°C

Switching characteristics:Eoff = 14.8 J, VAK,max = 8 kV, toff = 8µs, tf = 1µs, ttail = 5µs, 250 kW/cm2

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Conclusions

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SOA Limits of HV Devices are increasing

IPushing the RBSOA Limits

Vrated

n x I nom

VSSCM

State-Of-The-Art Limits

2 x I nomNew Limits

Device Capability

V

Under RBSOA operational conditionsDevices withstands dynamic avalanche mode IGBTs withstands “SSCM” mode

Devices achieve the ultimate square SOA behaviour

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Switching-Self-Clamping-Mode “SSCM”

Dynamic Avalanche

Self Clampingdv/dt

ICVDC

Dynamic Avalanche

Self Clampingdv/dt

ICVDC

S

DCSSCM

LVV

dtdi −

=

IGBT SOA turn-off waveforms including SSCMdevices start to limit voltage during turn-offover-voltage safely reaches the static breakdown after turn-off

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For high power conversion, only two devices possible today:

IGBTIGCT

Safe Operating Area is increasing from 250 kW/cm2

to 1 MW/cm2

IGDT offers possibility of high voltage devices with low losses (future?)

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Challenges

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Challenges for HV Power ToDs

High voltage devices present following challenges:Dynamic Avalanche ruggedness (for reliable operation)

Short Circuit Failure Modes (IGBT) and fault interruption (IGCT)

Design Trade-off between Losses and SOA

Critical Punch-Through voltages (for controllable voltage, low EMI)

High DC link voltage (leakage stability, cosmic ray withstand)

Large inductance and overshoot voltages in HV power systems

High frequency (limited by losses, TJ)

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Challenges for this decade

10 kV switches with 1 kHz snubberless operation(for the 6.9 kVRMS MV line for drives and power conditioners)

Snubberless series operation(static and dynamic for MV lines > 6.9 kVRMS)

Power supply free operation(autogenous power supply for series connection)

System cost-reduction(e.g. pay-back times ≈ 1 year for MV Drives)

Reduced thermal resistance and increased TJ

Reduced losses?