small signal measurement techniques for magnetic components€¦ · impedance measurements,” ieee...

Small Signal Measurement Techniques for Magnetic Components

Dr. Jenna Pollock

PSMA: Power Magnetics @ High Frequency Workshop 2019

Component Characterization

• Small signal measurements• R, L, C

• Analytical method to calculate impedances• Magnetizing inductance

• Al value• Reluctance with core permeability

• Leakage inductance• Pot core configuration

• Resistances• Dc resistance• Ac resistance

• Fr

• 1D field approximation

• Could use numerical methods


Two Winding Transformer Circuit Model

1:nRp RsLleakage,all 1:n

Cw,p

Lm

Rcore

Cw,s

Cinterwinding


Inductor Circuit ModelsResr

Cw

Lm

Resr

Cw

Lm

Resr


Inductor Measurement


Transformer Measurements


Test Fixture 16047E


Test Fixture 16047E• Calibration


Accuracy• Keysight

• E4990A


Predicting Inductance Roll-off with DC Excitation


Extracting Winding Resistance


Impedance-Analyzer Measurements


Example Inductor using ShapeOptPrototype:PQ4040 PC9520 turns 650 x 44 AWGAll legs gapped to 2 mm


• http://power.thayer.dartmouth.edu/shapeopt_spec.html

ShapeOpt: Data Entry

• Frequency = 300 kHz

• Peak current = 10 A


ShapeOpt: Outputs


ShapeOpt: Outputs

• Note:• Samples built with 650 strands and ShapeOpt calls for 682

• That’s a pretty good match• Could use “Force fixed number of strands” mode

• Many more parameters to vary

• Play with the tool at:• http://power.thayer.dartmouth.edu/shapeopt_spec.html

Prototype:PQ4040 PC9520 turns 650 x 44 AWGAll legs gapped to 2 mm


Measured Inductor Resistance

0.00E+00 1.00E+05 2.00E+05 3.00E+05 4.00E+05 5.00E+05 6.00E+05

PQ4040 PC9520 turns 650 x 44 AWGAll legs gapped to 2 mm

Rectangular Shaped

Frequency, Hz

50

100

150

200

250

300

350

400

Res

ista

nce

, mill

ioh

ms

Full bobbin rectangular winding vs. Shaped winding

Shaped winding reduces measured resistance


Inductor BuildsRectangular Winding LayoutShaped Winding Layout

PQ4040 PC9520 turns 650 x 44 AWGAll legs gapped to 2 mm


Inductor Build: Winding LayoutsRectangular Winding Layout Shaped Winding Layout

Build samples:

Rectangular Winding Layout

Shaped Winding Layout

centerline

centerline


Special Thanks to:

• Keysight Technologies

• Ed Herbert, PSMA

• Duanyang Wang, SF Motors


References:• Keysight Technologies, www.keysight.com

• J. Pollock and C.R. Sullivan, “Design Consideration for High-Efficiency Leakage Transformers,” IEEE APEC 2015

• J. D. Pollock, T. Abdallah, and C. R. Sullivan, “Easy-to-use CAD tools for litz-wire winding optimization,” in 2003 IEEE Applied Power Electronics Conference, vol. 2, 2003, pp. 1157–1163.

• Dartmouth Magnetic Component Research Web Site, http://engineering.dartmouth.edu/inductor.

• C. R. Sullivan and R. Zhang;, “Simplified design method for litz wire,” in IEEE 29th Annual Applied Power Electronics Conference, 2014, pp. 2667–2674.

• E. C. Snelling, Soft Ferrites, Properties and Applications, 2nd ed. Butterworths, 1988.

• C. R. Sullivan, “Optimal choice for number of strands in a litz-wire transformer winding,” IEEE Transactions on Power Electronics, vol. 14, no. 2, pp. 283–291, 1999

• Keysight Impedance Handbook, http://literature.cdn.keysight.com/litweb/pdf/5950-3000.pdf

• B. X. Foo, A. L.F Stein, C.R. Sullivan, A” Step-by-Step Guide to Winding Resistance Extraction from an Impedance Measurements,” IEEE APEC 2017.

• J.D Pollock, W. Lindquist, C. R. Sullivan , “Predicting Inductance Roll-off With DC Excitations,” IEEE ECCE 2010.

• S. Prabhakaran, C. R. Sullivan, “Impedance-Analyzer Measurements of High-Frequency, High Power Passives,


http://literature.cdn.keysight.com/litweb/pdf/5950-3000.pdf

small signal measurement techniques for magnetic components€¦ · impedance measurements,” ieee...

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