development of new inductive sensor - ansys · 2016-12-13 · development of new inductive sensor...

Development of New Inductive Sensor

Lingmin Shao KSR International

Outline

• Introduction• Optimization of electromagnetic structure of the inductive sensor

• Boundary conditions for ASIC design• Module level simulation• Conclusion

2012 Automotive Simulation World Congress 2Monday, October 08, 2012

http://www.ksrint.com


Inductive sensors are low‐cost and more robust in their life cycle compared to magnetic sensors.KSR initially developed its own patented inductive sensor technology for ETC pedal. Inductive sensor is further applied to suspension height, transmission , fuel level…

Current Inductive Sensor Structure


Analog ASIC:Driving the oscillatorSignal processing

Aluminum rotor

Coils:transmitting coil (CR)receiving coil1 (RM1)receiving coil2 (RM2)

Inductive Sensor Working Principle – Magnetic Field Point of View

When the rotor rotates, the magnetic field pattern rotates accordingly, the induced voltage on the receiving coil changes.

1. Transmitting coil generates an axial symmetric alternating magnetic field2. Eddy current is induced on the rotor3. Eddy current generates a secondary magnetic field of certain pattern depending on

the rotor geometry4. A differential voltage is induced on the receiving coil by this magnetic field pattern

Why new inductive sensor technology

Input from customer:• New functionality such as digital output (SENT, PSI5);• Wider measurement range up to 360 degrees;• Smaller size;• More robustness for mechanical variation and temperature variation;• Better EMC performance;

Solution:• New DSP based ASIC to provide more functionality and better flexibility;• New electromagnetic structure to provide better electrical performance


Challenge of new developmentDevelopment of a new ASIC costs more than $1M.ANSYS tool set used to reduce risk and speed the process of research and development

Electromagnetic structure:Improve the performance(linearity, robustness) while reducing the size;ASIC is not available to test out the design.

ASIC:Uncertainty of electromagnetic structure characteristics

‐ Impedance of electromagnetic structure‐ Raw signal strength

Module level:Integration of electromagnetic structure, ASIC and discrete components.Will it work? How much improvement can we expect?Need to be answered before building a physical part.


Electromagnetic structure design

Requirement:1. Power efficiency ‐maximum signal strength with the given driven power2. Robustness – output should not change with the mechanical and temperature

variation

Monday, October 08, 2012 2012 Automotive Simulation World Congress 8

Transmitting coil – circuitry perspective

Design parameter: turns, pitch, width…Design Target : high Q factor


7 turns 6 turns

0.00 2.00 4.00 6.00 8.00 10.00 12.00Freq

0.00

10.00

20.00

30.00

40.00

50.007 turnsCoil Q factor ANSOFT

Curve Info6 turns

Imported7 turns

Imported

7 turns has higher impedance, lower Q factor

PEX

ex1 ex2vhv vhv

ex1 ex2

cap

ex1:1ex1:1_ref

ex2:1ex2:1_ref

2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 6.00F

0.00

1.25

2.50

3.75

5.00

6.25

7.50

8.75loaded Q 7 turnsImpedance ANSOFT

Curve Info6 turns

Imported7 turns

Imported

Transmitting coil – magnetic field perspective

Design Target: High magnetic field strength with given driven power


0

ex2ex1

vhvvhvex2ex1

ex1 ex2

vhv

V1101

ex1:1ex1:1_ref

ex2:1ex2:1_ref

cap

AName=Is

AName=Itank

0.00 2.50 5.00 7.50 10.00 12.50 15.00 17.50 20.00Time

0

0

0

0

0

0

0ft LLC oscillator 7turnstank current ANSOFT

Curve Info7 turns

Imported6 turns

Imported

H field for 7 turns

6 turns has higher circulating current, it has slightly higher magnetic field strength

H field for 6 turns

Receiving coil and rotor

Design parameter: Geometry of receiving coil and rotorDesign Target: High receiving signal strength with given driven power


Nominal size

1.2time scaled

0.8time scaled

0.00 50.25 50.50 50.75 51.00 51.25 51.50 51.75 52.00Tim e

coupler size1signal ANSOFT

Curve Infoscaled by 0.8

Importednominal size

Importedscaled by 1.2

Imported

Rotor need match with the coil size, a mismatched rotor will reduce the signal

Signal quality in real life

Signal is susceptible to variability such as geometry tolerance and temperature Design Target: sensor output should be immune to the variabilitySolution: make a pair of offset coils, the ratio of two signals will factor out the variability

For signal quality, it is only needed to solve the impedance of the electromagnetic structure.


00

)()()()()()()()()(

)()()(

22212

21111

21

2

1

cr

sigsigsigsigsigcr

sigsigsigsigsigcr

sigcrsigcrcrcrcr I

ZZZZZZZZZ

SigSigV

)(/)()(/)()((var)*)()(

(var)*)()(

21

2

1

XffsigsigoutputgXfsig

gfsig

)()(

)(2

1

sigcr

sigcr

ZZ

output

Signal quality simulation result


-25.00 -12.50 0.00 12.50 25.00rz [deg]

assy 6 turns xyzsignal ANSOFT

Curve Infosig1

Setup1 : LastAdaptiveFreq='0.004GHz' gap='1mm'

sig1Setup1 : LastAdaptiveFreq='0.004GHz' gap='1.25mm'


sig2Setup1 : LastAdaptiveFreq='0.004GHz' gap='1mm'



-25.00 -12.50 0.00 12.50 25.00rz [deg]

assy 6 turns xyzoutput ANSOFT

Curve Infooutput

Setup1 : LastAdaptiveFreq='0.004GHz' gap='1mm'

outputSetup1 : LastAdaptiveFreq='0.004GHz' gap='1.25mm'

outputSetup1 : LastAdaptiveFreq='0.004GHz' gap='1.5mm'

Two raw signals change significantly with the air gap

The ratio of two raw signals does not change with the air gap

ASIC design boundary


ASIC

Analog interface DSP

Signal

power

Electrical characteristic for oscillator driver design; Signal range for amplifier and ADC design; Signal quality for DSP calibration algorithm

SPICE model is the communication tool


chpdisck_dspcosinecr_mon

errex1ex2gdgdcgdengsel3gsel2

gsel1gsel0hbtlbt

poerm1rm2sinevddvgvhv

vhv_in

ex1:1ex1:1_ref

ex2:1ex2:1_ref

rm1:1rm1:1_ref

rm2:1rm2:1_ref

HFSS model

Coil design environment


errex1ex2gdgdcgdengsel3gsel2

gsel1gsel0hbtlbt


vhv_in

ex1:1_posex1:1_negex2:1_posex2:1_neg

rm1:1_posrm1:1_negrm2:1_posrm2:1_neg

ASIC design environment

Full wave SPICE model

inputinput

Typical and worst case of the electromagnetic structure is extracted to full wave SPICE model as the design boundary of the ASIC;ASIC can be imported to designer for validation;Two components can be designed in parallel.

Module level simulation


0 0

0

ex2

ex1

ex2

rm1

rm2

vhv

vhv

vhv

ex1

gdengdc

GD

GD

poelbthbt

err

ck_dsp

cr_mon

vdd

vhv_in

chpdis

vhvvg

rm1rm2

cos

sinex2ex1

cap cap

cap

V2100

AIvhv

AIex1


errex1ex2gdgdc

gdengsel3gsel2

gsel1gsel0hbtlbt


vhv_in

ex1:1ex1:1_ref

ex2:1ex2:1_ref

rm1:1rm1:1_ref

rm2:1rm2:1_ref

Larger gap need more circulating current

Larger gap consume more power

Signal strength remains same at different gap

90.00 292.00 294.00 296.00 298.00 300.00Time

moduleCurrent draw ANSOFT

Curve InfoIpositive(Ivhv)

Transientcap='820pF' gap='1mm' rz='0deg'

Ipositive(Ivhv)Transientcap='820pF' gap='1.5mm' rz='0deg'

90.00 292.00 294.00 296.00 298.00 300.00Time

moduleCR current ANSOFT

Curve InfoIpositive(Iex1)


Ipositive(Iex1)Transientcap='820pF' gap='1.5mm' rz='0deg'

290.00 292.00 294.00 296.00 298.00 300.00Time

moduleraw signal ANSOFT

Curve InfoV(rm2)


V(rm2)Transientcap='820pF' gap='1.5mm' rz='0deg'

25.00 -12.50 0.00 12.50 25.00rz [deg]

moduletransfer function ANSOFT

Curve Infomean(output)

Transientgap='1mm'

mean(output)Transientgap='1.5mm'

Transfer function remains same at different gap

Test result


0

20

40

60

80

100

150 200 250 300

Output vs. angle

X=0 Y=‐0.6 Z=1.1

X=0 Y=0 Z=1.1

X=0 Y=0.6 Z=1.1

X=‐0.6 Y=0 Z=1.1

X=0.6 Y=0 Z=1.1

X=0 Y=0 Z=1.7

X=0 Y=0 Z=0.5

‐1

‐0.5

0

0.5

1

150 200 250 300

Linearity vs. angle

X=0 Y=0 Z=1.1

X=0 Y=‐0.6 Z=1.1

X=0 Y=0.6 Z=1.1

X=‐0.6 Y=0 Z=1.1

X=0.6 Y=0 Z=1.1

X=0 Y=0 Z=1.7

For +/‐0.6mm variation in 3 axis, linearity is +/‐0.3%;From ‐40°C to 125°C, output change less than 0.3%

Improvement

• 30% area reduction;• Range of measurement increases from 70 degree to 180 degree with better

linearity;• Allow double mechanical tolerance;• Programmable transfer function;• Support PSI5 and SENT digital output.


Conclusion

• A large variety of electromagnetic structures can be tested quickly with the help of HFSS;

• Electrical characteristic can be extracted for circuit design in parallel;

• System level validation can be done in designer before prototype;

• Simulation has good correlation with the measurement;• A new generation inductive sensor has been developed in controlled time and with lower risk.


development of new inductive sensor - ansys · 2016-12-13 · development of new inductive sensor...

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