Diapositiva 1

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UNIVERSITY OF NOTTINGHAM SCHOOL OF ELECTRICAL
AND ELECTRONIC ENGINEERING POWER ELECTRONICS
MACHINES AND CONTROL RESEARCH GROUP ACTIVE
FILTERS FOR AIRCRAFT POWER SYSTEMS
Supervisors Dr Pericle ZANCHETTA Dr Mark SUMNER
PhD Student Elisabetta LAVOPA
EPE-PEMC Portoroz, Slovenia, 30th August 1st
September 2006
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MORE ELECTRIC AIRCRAFT

• Emphasizes the use of electrical power in place
  of hydraulics, pneumatic
• and mechanical power to optimize the performance
  and life cycle cost of
• the aircraft.

• more electrical loads
• more complex topology of the electrical network
  (400Hz, 115V)
• more generation demand
• more power electronic equipment
• more harmonic distortion and stability problems

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APPROXIMATE MODEL OF AN AIRCRAFT POWER NETWORK
2 twin generators
line impedances
non linear loads
linear loads
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TRANSIENT RESULTS All loads initially
disconnected and then connected at t 0.005 sec
Ripple due to non linear loads
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STEADY STATE RESULTS All loads connected to
the grid
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PASSIVE FILTERING TECHNIQUE
2 passive shunt filters tuned on the 5th and 7th
harmonic frequencies.
R-L-C shunt filter tuned on 5th harmonic (2000Hz)
R-L-C shunt filter tuned on 7th harmonic (2800Hz)
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PASSIVE FILTERING TECHNIQUE
R 10 mO C 0.01 mF L 0.63 mH fnotch 2000
Hz
5th harmonic filter
R 10 mO C 0.01 mF L 0.32 mH fnotch 2800
Hz
7th harmonic filter

• Drawbacks
• weight
• high fundamental current
• one filter for each harmonic
• interaction with supply impedance
  (resonance)

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ACTIVE FILTERING TECHNIQUE
generator
non linear load
active filter
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ACTIVE FILTERING TECHNIQUE
An active filter injects harmonics at the point
of common coupling in order to compensate the
harmonics due to non linear loads. Current
injected by the filter (output current) has to be
equal to non linear loads current (reference
current), but with opposite phase angle
A control technique is used in order to ensure
the filter current follows the reference current
in the fastest and most precise way
ANALYSIS OF 2 CONTROL TECHNIQUES SYNCHRONOUS PI
CONTROLLER TECHNIQUE PREDICTIVE CONTROL TECHNIQUE
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ACTIVE FILTER CONTROL Synchronous PI controller
technique
PI controllers
PWM voltage control
reference current
load voltage a-b-c to d-q
load current a-b-c to d-q
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ACTIVE FILTER CONTROL Synchronous PI controller
technique
5th HARMONIC CONTROL
Reference current
Output current
PI controller
Closed loop poles z -0.0158 j0.0535 Damping
ratio 0.841 Natural frequency 1.09e4 Hz
Steady state error Amplitude 0.25 A
(8.3) Phase 70º
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ACTIVE FILTER CONTROL Predictive control
technique
This technique takes into account digital
controller delays, performing a prediction of the
main variables like reference current, filter
output current, supply voltage. The prediction is
based on a polynomial-type extrapolation method.
Power part (generator inverter)
DC link voltage control
PWM voltage control
Voltage prediction
Reference current generation
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ACTIVE FILTER CONTROL Predictive control
technique
5th HARMONIC CONTROL
Reference current
Output current
Steady state error Amplitude 0.341 A
(6.3) Phase 4º
Smaller steady state amplitude and phase errors,
compared to PI control. Good tracking performance
for high frequency signals. Predictive control is
more suitable than PI synchronous control for
active filter applications on aircrafts (400 Hz).
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FUTURE WORK

• design the predictive control for high order
  harmonics (11th and 13th besides 5th and 7th)
• more detailed comparison analysis between the
  two control techniques
• real time calculation of reference current by
  means of harmonic detection algorithms
• simulate the active filter on a more complex
  network, carrying out system analysis to
  determine the best set of specifications of the
  filter for a certain network configuration and
  topology
• stability analysis