1. COMPERE Project Meeting Dr Dawei Xiang 18/07/2008

2. Content I. Characteristic harmonic identification for CM
II. Further work plan
III. Questions
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3. Characteristic harmonic identification for CM
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4. Devices degradation and its effects
Device characteristics affected by
temperature (as shown left)
device condition (e.g. gate oxide)
Temperature depends on
• operating point and ambient etc.
• device condition (e.g. bond wire lifting)
1200V/100A
Mitsubishi IGBT module including anti-parallel diode
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5. Cause of characteristic harmonics
Harmonics depend on
• operating/ambient condition
• device condition
Device voltage drop
at VSI terminal
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6. Devices degradation and its effects
Area of trajectory increased by ~25%
5th harmonic increased by ~0.5V
5th harmonic
phase angle
as affected by power factor angle
a.c. side power factor angle
Simulated characteristic harmonics before and after aging (Von increased by 15%, Ron increased by 15%, ton-toff decreased by 200 ns?)
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7. Basic idea of detecting small change of harmonic (5th order)
• creating a resonance condition at harmonic frequency
• compensating the harmonic and eliminate it
• extracting CM information from compensating signal
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8. Harmonic identification & compensation
VSI
Converter
Control to eliminate harmonic current u
ref h i_
Filter
Grid
Harmonic
reference frame SV
calculation i h
Coordinate
transformation f hd hq * =0
P I u U , θ _
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9. Studied system: a 400V / 50Hz / 10kVA / 700Vdc VSC rectifier
Simulation work
Studied system: a 400V / 50Hz / 10kVA / 700Vdc VSC rectifier
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10. Simulation work without introducing resonance
with introduced resonance
about 60 times amplification to 5th harmonic
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11. (determined by control)
Simulation work
Amplitude of required 5th harmonic voltage for compensation (determined by control)
I (A) PF
Uh (V)/θ_Uh (deg)
(measured)
(determined by control)
14.4 1
3.763/173.34
3.765/173.96 10
0.9(lag)
3.790/-38.02
3.783/-38.40
7.2
0.9(lead)
3.769/56.47
3.768/56.06
3.6
0.95(lag)
3.736/-63.71
3.718/-63.07
Max error: 0.5/1 (%)
Uh determination
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12. Simulation work A suggested condition index
Points on circle correspond
to different power factors
Separation of grid background harmonic
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13. Is the assumption of such a study valid?
Question
Is the assumption of such a study valid?
How to prove or disprove it?
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14. II. Further work plan
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15. Based on power converter low frequency characteristics
Theoretical work
Characteristic harmonic identification based CM
On-state resistance identification based CM
DC offset identification based CM
Based on power converter low frequency characteristics
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16. Initial idea for Ron identification
Synchronous machine:
460V/ 60Hz/ 200HP
Rs=2.01e-3 ohm
Ψs_transient decays during Us sudden drop from 1pu to 0.95pu
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17. Experimental work Accelerated aging test platform (Warwick?)
VSC rectifier system
VSI fed AC drive system
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18. Accelerated aging tests
Accelerated power cycling test system
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19. Accelerated aging test
Over loading the IGBT by DC power supply for 1h to simulate a long period operation.
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20. VSC rectifier system
Rating: 400Vac /10kVA/ 800 Vdc ?
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21. VSI fed AC drive system
Rating: 400V /10kW ?
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22. III. Questions
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23. Questions Power devices terminal characteristics
How much do the Von and Ron change after aging?
How much do the switching times change after aging?
Accelerated aging test
How long does a power cycling test take?
How to built a BTB cycling test system?
Power electronics modelling and simulation
Can I get the detailed power electronics simulation model from UoW in order to study the system characteristics at low frequency and/or high frequency?
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24. Thanks for you attention!