impedance characterization of high frequency power ... - kit

KIT – University of the State of Baden-Wuerttemberg and National Research Center of the Helmholtz Association

Light Technology Institute (LTI), Department of Electrical Engineering and Information Technology

www.kit.edu

Impedance Characterization of High Frequency Power Electronic Circuits

Michael Meisser , Karsten Haehre, Rainer Kling

Light Technology Institute (LTI)

KIT, Karlsruhe, Germany

2 29.03.2012 Dipl.-Ing. Michael Meisser, PEMD 2012: “Impedance Characterization of High Frequency Power Electronic Circuits”

Introduction: Half-Bridge at Challenges

VD

S,L

S

output: storage elements, resonant tanks

input: ideal voltage source: no resistance, no AC impedance

inductively coupled plasma sources (discharge lamps)

task: higher operating frequency

capacitively coupled plasma sources (discharge lamps)

1 – 100 MHz




Challenge 1: Providing Broadband Voltage Source Input

low-switch VDS waveform – frequency band

lower corner frequency: operation frequency

DClink capacitor must provide low impedance between flow - fhigh

f

Zsource

C

ESR

ESL

C

ESR

ESL

flow fhigh




Challenge 1: Providing Broadband Voltage Source Input

low-switch VDS waveform – frequency band

lower corner frequency: operation frequency

higher corner frequency: maximum slope

DClink capacitor must provide low impedance between flow - fhigh

f

Zsource

C

ESR

ESL

C

ESR

ESL

flow fhigh




fV

DS

,LS

VS

positive

overshoot

negative

overshoot

Challenge 2: Providing low Series Inductance

LPKG

LPKG

Lw

Lw

ESRClink

ESLClink

Clink

HS

LS

prevent voltage overshoot

lower electromagnetic radiation




Impedance Measurement – Information to be Extractedim

pe

da

nce

Z

parpar

par

parpar L

CR

Z

RQ ========

C

L

RR

ZQ ser

serser

serser

1========

Lser

CZ

Rser

Lpar Rpar




Impedance Measurement Setup with DC -bias

com

pen

satio

n,

calib

ratio

n

Cblock

Dclamp

HV

inputto

analyser

DC+AC AC

Cblock = NP0 MLCC 1 kV 1.5 nF

8 parallel; XC @ 1 MHz = 13 Ω

Dclamp = 4x antiparallel BAV74

Si RF diodes




Impedance Measurement – DC-blocker validation

1.E-03

1.E-01

1.E+01

1.E+03

1.E+05

1.E+07

1.E+09

1.E+04 1.E+05 1.E+06 1.E+07 1.E+08frequency [Hz]

impe

danc

e [

Ω]

120111 impedance Auswer tung.xl s




high

switch

low

switch

CDC

ceramic DClink

capacitors

TR

(backside)

L

(backside,

not assembled)

HF HV

pulse output

DClink input

VS

Vbridge

VDS,LS

VTR,prim

RF resonant pulse generator




CD

S,H

SC

DS

,LS V

DS

,LS

VS

Vb

rid

ge

VT

R,s

ec

VT

R,p

rim

RF resonant pulse generator

Reference: Meisser et. al., PEMD 2010, Brighton




Resonant Behaviour Without DC -bias

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

frequency [Hz]

impe

danc

e [

Ω]

120110 impedance Ausw ertung.xls

Coss,LS

+ CDBD,prim

= 15.9 nF

42 nH

Lm

+ Lstray

= 127 µH

VTR

VDS,LS

CDC = 440 nF

Coss,LS

= 13.2 nF4.8 nH

VDS,LS

VTR

with lamp

connected

without lamp

connected

RAC,ser = 0.25 – 0.35 Ω

resonances of freewheeling circuit, both switches off




Variance in Switch Output Capacitance

0.1

1

10

0 100 200 300 400 500 600

VDS,LS [V]

capa

cita

nce

[nF

]

C measured

C compl

C low switch only

C high switch only

120108 C variat ion of Coss DE475102N21.xls

HS

LS

Clink Impedance

measurement @

variable DC-bias

constant

voltage

source




RF-half-bridge Decoupling Performance

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

frequency [Hz]

impe

danc

e [

Ω]

DC-blocker: Vbridge = 600 V


Vbridge

120111 impedance Auswer tung.xls

impedance rises to 1 Ω at 2 MHz and 600 VDC

HF DC-rail decoupling performance fails at high voltage(X7R ceramic drift)




Summary

Impedance measurement with DC bias:DC-blocker built and characterizedinvestigates RF circuit performance

RF half-bridges:ensure low leg inductanceensure low source impedance

Resonance behaviour of RF half-bridge measured

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+04 1.E+05 1.E+06 1.E+07 1.E+08frequency [Hz]

impe

danc

e [

Ω]

120110 impedance Auswertung.xls

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

frequency [Hz]

impe

danc

e [

Ω]



Vbridge

120111 i mpedance Auswer tung.xls

Bottleneck detected: impedance peak due to X7R ceramics




Question and Answer Part




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impedance characterization of high frequency power ... - kit

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