student name: fong yat chi student id: 14900129r
TRANSCRIPT
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EE6821Special Topics in
Advanced Utilization ICoursework ppt2
Student Name: FONG Yat ChiStudent ID: 14900129R
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Skin Effect◦Derivate the Skin Depth
Level-shifting Circuits for Controlling Signal◦Non-isolating Techniques
Some Results of Capacitor Test
Content
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◦ Increase in → Increase in Because the current concentrated near to the
surface of the conductor
Skin depth:δ =
Skin Effect
AC current distribution in a cylindrical conductor(Picture from the Internet)
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◦ Cause of Skin Effect:Magnetic Induction
(due to the changing field in the conductor)
◦ Inside the conductor:
Skin Effect (Cont’d)
Coordinates for the cylindrical conductor
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◦ Relationship between J and B
• J: flow in y-direction Equal in x-direction
B: flow in x-direction Equal in y-direction
◦ J and B only change in z-direction
Skin Effect (Cont’d)
Coordinates for the cylindrical conductor
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◦ J and B only change in z-direction
◦ This become a 2nd Order ODE
◦ Solution:
→
Skin Effect (Cont’d)
Coordinates for the cylindrical conductor
𝐽 𝑠
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◦ Extract the attenuation term:
◦ Attenuation term:
◦ Skin depth (Decay Constant)
Skin Effect (Cont’d)
Coordinates for the cylindrical conductor
𝐽 𝑠
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Shift Signal level from V1 to V2
◦ A Passive Level Shifting Circuit
Easy to implement Suffer from many problems
Level-shifting Circuits
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◦ Active Level-Shifting Circuits Often use in digital interface
Require a voltage source for output Use active switch
Level-shifting Circuits (Cont’d)
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◦ Active Level-Shifting Circuits
Level-shifting Circuits (Cont’d)
Higher Voltage Version The resistors limit the current→ Low Speed
Higher Speed→ Higher Current
→ Higher Loss Some solutions in the
industry
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◦ Reduce the Duty-ratio of the Switch
◦ Use encoding and latch◦ Mature technique in commercial Products
Level-shifting Circuits (Cont’d)
Functional diagram for a high-side gate drive IC(from Fairchild Application Note)
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Conclusion◦ Passive Level-Shifter Easy to implement No voltage source (use Vs to supply) Easily get malfunction
◦ Active Level-Shifter Require a voltage supply More complicated digital circuits
Level-shifting Circuits (Cont’d)
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Capacitor Test
1st Sample
3rd Sample
2nd Sample4th Sample
5th Sample
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Network Analyzer with Impedance Module
FRA5087 Network Analyzer
Impedance Module
Result:
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1st Sample: Panasonic 1μF 275V Polypropylene
Compare with LCR Meter (Con’t)
From LCR MeterCs ≈ 0.86μFLs ≈ 41.4nHRs ≈ 0.037Ωfr ≈ 850kHz
From Network AnalyzerCs ≈ 0.86μFLs ≈ 188nHRs < 0.037Ωfr ≈ 400kHz
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2nd Sample: Epcos 4.4μF 250V Polypropylene
Compare with LCR Meter (Con’t)
From LCR MeterCs ≈ 4.42μFLs ≈ 28.6nHRs ≈ 0.0155Ωfr ≈ 440kHz
From Network AnalyzerCs ≈ 4.48μFLs ≈ 213nHRs < 0.0123Ωfr ≈ 160kHz
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3rd Sample: Unknown 0.56μF 275V Polypropylene
Compare with LCR Meter (Con’t)
From LCR MeterCs ≈ 0.57μFLs ≈ 30.4nHRs ≈ 0.041Ωfr ≈ 1.21MHz
From Network AnalyzerCs ≈ 0.58μFLs ≈ 254nHRs < 0.0329Ωfr ≈ 410kHz
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4th Sample: BC 2.2μF 100V Polypropylene
Compare with LCR Meter (Con’t)
From LCR MeterCs ≈ 2.24μFLs ≈ 20.5nHRs ≈ 0.0226Ωfr ≈ 742kHz
From Network AnalyzerCs ≈ 2.21μFLs ≈ 251nHRs < 0.0222Ωfr ≈ 210kHz
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5th Sample: Kemet 680nF 50V Ceramic
Compare with LCR Meter (Con’t)
From LCR MeterCs ≈ 0.58μFLs ≈ 16.1nHRs ≈ 0.0619Ωfr ≈ 1.68MHz
From Network AnalyzerCs ≈ 0.56μFLs ≈ 238nHRs < 0.0281Ωfr ≈ 440kHz
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Network Analyzer◦ Resonant frequency shift to left due to the
increase in Ls◦ Low resolution of phase angle◦ Convenient to plot the frequency response
Further Works to be Done◦ More samples of each model◦ Try different of types (e.g. Electrolyte)◦ Test with higher voltage/current using amplifier◦ AC vs AC superposed with DC◦ Reduce the effect of additional inductance
Comments
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Thankyou!Q&A