Kyushu Institute of Technology

Exploration ofthe Electric Current Flow
inside Power Modules and Chipswith Tiny Sensors
Ichiro Omura
Kyushu Institute of Technology

Agenda• Introduction: Why?
• Chip current distribution measurement for DBC/Chiplevel screening• PCB Rogowski coil for current measurement inpower module and chip
• Integration possibility of output current sensor in
IPM with PCB Rogowski coil
• Conclusions

2

Measured current imbalance in DBC-module
IGBT Chips layout

8 waveforms of double pulse testfrom 16 paralleled IGBTs

IGBT

IGBT

T. Domon et al., IEEJ 2004Clearly, Current imbalance exists among parallel IGBT chips,
especially at turn-off and turn-on
3

Why electric current flow measurement
inside power modules and chips?

• Feedback to power module design forbalanced current flow
• Gate drive circuit optimization / feedback• DBC/chip level screening method inmass production lines• Integration of current sensing function in
the power module• Others, such as short-circuit protection
42 Chips

125mm
15mm

4

Agenda• Introduction: Why?
• Chip current distribution measurement for DBC/Chiplevel screening• PCB Rogowski coil for current measurement inpower module and chip
• Integration possibility of output current sensor in
IPM with PCB Rogowski coil
• Conclusions
By Y. Kasho, M. Tsukuda, H. Hirai, H. Tomonaga5

Basic idea for screening in DBC/chip level
Chips on DBC
SignalWaveforms

2.000

1.500

AMPs

16ch SensorCoils

1.000

V(vout_01)
V(vout_02)
V(vout_03)
V(vout_04)

0.500

V(vout_05)
V(vout_06)
V(vout_07)
0.000

V(vout_08)

電圧

V(vout_09)[V(vout_10)

V]

V(vout_11)-0.500V(vout_12)
V(vout_13)
V(vout_14)-1.000V(vout_15)
V(vout_16)-1.500

Bondingwires
IGBT-2.0000.000

50.000100.000
時間[us]

150.000

200.000

Display of GO judgment
Color image of thedifference of right IGBT

Left IGBTchip data

AbnormalThreshold
NormalColor image of thedifference of left IGBT

Sum of the Integral
value of thedifferenceStandard
score

Probability densityof Standard assembly

GO/NOGO

Plug-in to existing DBC
switching test machineStandard score of total difference
to reference signal(Left side chip)

Input standard
score as threshold Judgment

AbnormalAbnormal

NormalAbnormal

Data Processing

Standard score of total difference
to reference signal(Right side chip)

NormalAbnormalRight IGBT
chip data

Threshold6

Inductance matrix calculation with
“Sonnet-2D”SPICE simulation
2D simulation is more than X10 faster than 3D simulation.
16ch sensor coils
8 Bonding wires
Bonding wires
Bonding wire Bonding wire Bonding wire Bonding wire Bonding wire Bonding wire Bonding wire Bonding wire Sensor coil
1234567801

Bonding wires

16ch sensor coils

Bonding wire1
Bonding wire2
Bonding wire3
Bonding wire
4
Bonding wire
5
Bonding wire
6
Bonding wire
7
Bonding wire8
Sensor coil01
Sensor coil02
Sensor coil03
Sensor coil04
Sensor coil05
Sensor coil06
Sensor coil07
Sensor coil08
Sensor coil09
Sensor coil
10
Sensor coil
11
Sensor coil
12
Sensor coil
13
Sensor coil
14
Sensor coil
15
Sensor coil
16

Sensor coils

8 Bonding wires
2

Sensor coils
Sensor coil02

Sensor coil03

Sensor coil04

Sensor coil05

Sensor coil06

Sensor coil07

Sensor coil08

Sensor coil09

Sensor coil
10Sensor coil
11Sensor coil
12Sensor coil
13Sensor coil
14Sensor coil
15Sensor coil
16L1L2L3L4L5L6L7L8L9L10L11L12L13L14L15L16L17L18L19L20L21L22L23

L24

L1

1.000000

0.068908

0.046085

0.006228

0.001883

0.002714

0.000057

0.000463

0.008470

0.009142

0.006895

0.004500

0.002775

0.001677

0.001011

0.000614

0.000379

0.000239

0.000154

0.0001020.000069

0.000046

0.000030

0.000017

L20.0689081.000000

0.080611

0.034375

0.011681

0.002069

0.001885

0.000029

0.004150

0.006885

0.008098

0.0071150.004988

0.003012

0.001638

0.000807

0.000345

0.0001050.000010

0.000057

0.000069

0.000063

0.000049

0.000031

L3

0.046085

0.080611

1.000000

0.081626

0.023742

0.022944

0.002040

0.003414

0.002756

0.005556

0.009278

0.013308

0.015170

0.013074

0.0092090.005889

0.003627

0.002211

0.001352

0.000836

0.000522

0.000326

0.000198

0.000106

L4

0.006228

0.034375

0.081626

1.000000

0.126638

0.023697

0.012084

0.002088

0.000419

0.000922

0.001794

0.003223

0.005252

0.007360

0.008233

0.007086

0.004895

0.002911

0.001553

0.000749

0.000313

0.000098

0.000007

0.000019

L5

0.001883

0.011681

0.023742

0.126638

1.000000

0.081561

0.035262

0.007188

0.000069

0.000174

0.000408

0.000875

0.001731

0.003158

0.005194

0.007319

0.008217

0.007094

0.004922

0.002948

0.001596

0.000794

0.000358

0.000135

L6

0.002714

0.002069

0.022944

0.023697

0.081561

1.000000

0.081525

0.055806

0.000135

0.000282

0.000497

0.000834

0.001384

0.002298

0.003804

0.006199

0.009665

0.013528

0.015272

0.013083

0.009129

0.005700

0.003287

0.001642

L7

0.000057

0.001885

0.002040

0.012084

0.035262

0.081525

1.000000

0.078803

0.000026

0.000045

0.000056

0.000047

0.000001

0.0001220.000378

0.0008730.001761

0.003218

0.005277

0.007407

0.008282

0.007089

0.004763

0.002482

L8

0.000463

0.000029

0.003414

0.002088

0.007188

0.055806

0.078803

1.000000

0.000023

0.000048

0.000079

0.000124

0.000191

0.000299

0.000476

0.000773

0.001274

0.002117

0.003516

0.005740

0.008913

0.012244

0.013000

0.009086

L9

0.008470

0.004150

0.002756

0.000419

0.000069

0.000135

0.000026

0.000023

1.000000

0.058796

0.011685

0.004143

0.001842

0.000918

0.000491

0.000276

0.000161

0.000097

0.000059

0.000037

0.000024

0.000015

0.000009

0.000005

L10

0.009142

0.006885

0.005556

0.000922

0.000174

0.000282

0.000045

0.000048

0.058796

1.000000

0.060809

0.012699

0.004674

0.002135

0.001087

0.000592

0.000338

0.000200

0.000121

0.000075

0.000047

0.000030

0.000018

0.000009

L11

0.006895

0.008098

0.009278

0.001794

0.000408

0.000497

0.000056

0.000079

0.011685

0.060809

1.0000000.061311

0.012989

0.004842

0.002236

0.001149

0.000630

0.000362

0.000216

0.000131

0.000081

0.000050

0.000030

0.000016

L12

0.004500

0.007115

0.013308

0.003223

0.000875

0.000834

0.000047

0.000124

0.004143

0.012699

0.061311

1.000000

0.061467

0.013087

0.004904

0.002275

0.001174

0.000647

0.000373

0.000222

0.000134

0.000082

0.000048

0.000025

L13

0.002775

0.004988

0.015170

0.005252

0.001731

0.001384

0.000001

0.000191

0.0018420.004674

0.012989

0.061467

1.000000

0.061525

0.0131270.004929

0.002291

0.001184

0.000653

0.000376

0.000222

0.000132

0.000076

0.000039

L14

0.001677

0.003012

0.013074

0.007360

0.003158

0.002298

0.0001220.000299

0.000918

0.002135

0.004842

0.013087

0.061525

1.000000

0.061552

0.013144

0.004939

0.002297

0.001187

0.000653

0.000373

0.000217

0.000123

0.000061

L15

0.001011

0.001638

0.009209

0.008233

0.005194

0.003804

0.000378

0.000476

0.000491

0.001087

0.002236

0.004904

0.013127

0.061552

1.000000

0.061562

0.013150

0.004942

0.002298

0.001184

0.000647

0.000364

0.000202

0.000099

L16

0.000614

0.000807

0.005889

0.007086

0.007319

0.006199

0.000873

0.000773

0.000276

0.000592

0.001149

0.002275

0.004929

0.013144

0.061562

1.000000

0.061565

0.013150

0.004940

0.002292

0.001175

0.000632

0.000340

0.000164

L17

0.000379

0.000345

0.003627

0.004895

0.008217

0.009665

0.001761

0.001274

0.000161

0.000338

0.000630

0.001174

0.002291

0.004939

0.013150

0.061565

1.000000

0.061562

0.013144

0.004930

0.002277

0.001151

0.000595

0.000279

L18

0.000239

0.000105

0.002211

0.002911

0.007094

0.013528

0.003218

0.002117

0.000097

0.000200

0.000362

0.000647

0.001184

0.002297

0.004942

0.013150

0.061562

1.000000

0.061550

0.0131270.004906

0.002239

0.001091

0.000495

L19

0.000154

0.000010

0.001352

0.001553

0.004922

0.015272

0.005277

0.003516

0.000059

0.000121

0.000216

0.000373

0.000653

0.001187

0.002298

0.004940

0.013144

0.061550

1.000000

0.061528

0.013092

0.004846

0.002140

0.000922

L20

0.0001020.000057

0.000836

0.000749

0.002948

0.013083

0.007407

0.005740

0.000037

0.000075

0.000131

0.000222

0.000376

0.000653

0.001184

0.002292

0.004930

0.013127

0.061528

1.000000

0.061474

0.0129940.004678

0.001846

L21

0.000069

0.000069

0.000522

0.000313

0.001596

0.009129

0.008282

0.008913

0.000024

0.000047

0.000081

0.000134

0.000222

0.000373

0.000647

0.001175

0.002277

0.004906

0.013092

0.061474

1.000000

0.061315

0.012702

0.004146

L22

0.000046

0.000063

0.000326

0.000098

0.000794

0.005700

0.007089

0.012244

0.000015

0.000030

0.000050

0.000082

0.000132

0.000217

0.000364

0.000632

0.001151

0.002239

0.004846

0.012994

0.061315

1.000000

0.060810

L23

0.000030

0.000049

0.000198

0.000007

0.000358

0.003287

0.004763

0.013000

0.000009

0.000018

0.000030

0.000048

0.000076

0.000123

0.000202

0.000340

0.000595

0.001091

0.002140

0.004678

0.012702

0.060810

1.000000

0.058799

L24

0.000017

0.000031

0.0001060.000019

0.000135

0.001642

0.002482

0.009086

0.000005

0.000009

0.000016

0.000025

0.000039

0.000061

0.000099

0.000164

0.000279

0.000495

0.000922

0.0018460.004146

0.011687

0.058799

1.000000

0.011687

2.000

1.500

1.000

V(vout_01)

V (V)V(vout_02)
V(vout_03)
V(vout_04)

0.500

V(vout_05)

0V(vout_06)
V(vout_07)
0.000

V(vout_08)

電圧

V(vout_09)[V(vout_10)

V]

V(vout_11)-0.500V(vout_12)
V(vout_13)
V(vout_14)-1.000V(vout_15)
V(vout_16)-1.500-2-2.000
0.000

50.000Turn-off 1

100.000
時間[us]

10 ms/div150.000

200.000

SPICE simulation
including integration
amplifier7

Configuration of 16ch sensor array module
CuAnalog amplifier

Trough hole

1ch

2ch
3ch

1mm

4chSensor

X-ray image of sensor

Polyimide film

ShieldThe 16ch sensor array module consists of spiral coils on the bothside of the films, analog amps
8Demonstration setup
Test head
Screening tester
Power supply

Control unit

Main unit (Power circuit)

High/Low inductor

Sensor arraymodules

Contact pinsfor gate

Display

Low side DBCmodule of IGBT

Multi-channel Diodes
digitizer

Test head Gate drivers
Oscilloscope

Emergencystop button

Contact pins foremitter and collector

High side DBCmodule of IGBT

DBC-moduleIGBTs

Inductance switching terminal

9

Magnetic flux distribution example(Double pulse test)10

Method of normal/abnormal classification(two IGBTs on a DBC)

AbnormalThreshold
NormalProbability densityof Standard assemblyStandard score of total difference
to reference signal(Left side chip)

Left IGBT
chip data

AbnormalAbnormal

NormalAbnormalStandard score of total difference
to reference signal(Right side chip)

NormalAbnormalRight IGBT
chip data

ThresholdStandard score of total difference
to reference signal(Right side chip)

Normal/abnormal classification method with statistical approach

NormalBending
Disconnection
Imbalanced RG

Standard score of total difference
to reference signal(Left side chip)Agenda• Introduction: Why?
• Chip current distribution measurement for DBC/Chiplevel screening• PCB Rogowski coil for current measurement inpower module and chip
• Integration possibility of output current sensor in
IPM with PCB Rogowski coil
• Conclusions
By M. Koga, M. Tsukuda, K. Nakashima, H. Yamaguchi
12Technology• Use of tiny core-less coil on PCB– Reproducibility, mass-productivity(Low cost), less flexibility– Improvement with advancement of PCB technology– Integration in gate circuit board etc.
• Analog + digital processing– Automatic calibration, Signal equalizing• In-house high speed design tool
– Application specific design

13Fishbone coil pattern
Forward line

Cross section

Return line
Through holes

Pattern name

PCB Rogowski
coil

Fishbone(Novel)Saw bladeTriangle

Fishbone w/oreturn line

±7%±10%±26%

±218%

X-ray
photographPictureX ray photoMax. variation
with outsideconductor

14

Analog + digital processing• 2-stage signal processing– Analog incomplete
integration circuit(Shorter RC-constant)– Digital compensation oflow frequency region

Hirai et al ISPSD 201215

In-house high speed design tool
Distribution of the mutual inductance by in-house highspeed simulator (MATLAB)
2 nH
2 nH
0 nH
0nH

Circle geometry

Square geometry

Method of mutual inductance calculation

Simplified

Actual modelQ3D 1 day3D data needed

Calculation

Simplified
model

In-house simulator 30 min.
Only a table of throughhole positions is required 16

Coil pattern design
in-house high-speed simulation and experimental results for mutual
inductance error ratio

17Demonstration• Two IGBTs are parallel connection on DBC• Gate signal delay to IGBT B• Current imbalance during turn-off is measured• Total current is coincided to CT result
18

Demonstration
Measurement of the switching waveform
Power MOSFET(TO-220 package)

Current[A]Output voltage from amp[V]PCB Rogowski coil
(D=3.2mm)

PCB Rogowski coilCT

500 ns

It is possible to current measurement even in a limited space19

16 channel system

Labview (NI digitizer setting)Labview (calibration)20

Agenda• Introduction: Why?
• Chip current distribution measurement for DBC/Chiplevel screening• PCB Rogowski coil for current measurement inpower module and chip
• Integration possibility of output current sensor inIPM with PCB Rogowski coil
• Conclusions
By K. Takahara, K. Hasegawa, S. Tabata
21

Inverter output current measurement
function integration in IPM

New Method

Reproducing Circuit

Output Current

PCB coils are placed on
negative/positive busReproduction of output current
from switching current
K. Hasegawa, S. Takahara, S. Tabata, M. Tsukuda, and I. Omura,“A New Output Current Measurement Method with Tiny PCB
Sensors Capable of Being Embedded in an IGBT Module,” IEEE
Trans. Power Electron, vol. 32. no. 3, pp. 1707-1712, Mar. 2017.

2222

Current Reproducing Procedure
IOFF

ION

iO

Inverter output current

iSW

IGBT current

Output signalof PCB Coil∝ diSW/dt
ION

Integrated
waveformby OP amp.

R2
R1

Ct = CR2-IOFF
IOFF

Rectifiedwaveform

IONt

Output current isreproduced by peak
tracking
23

Experimental setup with IGBT Module
PCB Rogowski coil
PCB Rogowski coil

IGBT Module

IGBT
705μH Hall current sensor

Voltage
supplyGate Drive

220μF

PiN Diode

NEXYS 3

SPARTAN-6∫5Ω

８８ ８８100μF

Digital Circuit

Duty: 40% → 50%

FPGA A/D Converter

integrator

FPGA eliminates influence by reverse recovery or turn-off tail current
24Transient response
Duty:40%

Duty:50%

New method

Hall Current
SensorNote: Delay of half of PWM cycle will appear in practical implementation
25

Conclusions• Why: package design, gate drive optimization, new screening
method, sensor for protection and possibility of output current
sensor integration in IPM, etc.
• Practical examples– DBC/Chip level screening method– PCB Rogowski coil for power module– Integration of output current sensor in IPM• PCB coils advantage and requirement– PCB coil has advantage of reproduction of the performance,
cost, size (thickness), physical strength (but less flexibility)– Design tool is required for application specific design– Digital system will help the measuremrnt for automatic
calibration, waveform processing26

Related papers••••••••••••

M. Koga et al. CIPS2016
Google “power kyutech”
M. Tsukuda et al. ESREF2016
M. Tsukuda et al. CIPS2016
H. Tomonaga et a;. ESREF2015
M. Tsukuda et al. ESREF2015
S. Tabata / K. Hasegawa et al. ISPSD2017
H. Hasegawa et al. IEEE Trans on PE, 2017-03
K. Nakashima(中島), IEEJ Workshop, 2015 in Japanese
K. Takahara（高原）, IEEJ Workshop, 2015, in Japanese
H. Yamaguchi（山口）, IEEJ Workshop, 2014, in Japanese
H. Hirai, ISPSD 2012
Y. Kasho, ESREF 2011

• Find at Kyushu Institute of Technology Academic Repository– http://power.kyutech.ac.jp/en/publications.html
27