r. griñó, r. costa-castelló and e. fossas instituto de organización y control (ioc)

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34th IEEE Power Electronics Specialists Conference June 15-19, 2003. Acapulco

R. Griñó, R. Costa-Castelló and E. Fossas

Instituto de Organización y Control (IOC)Universitat Politècnica de Catalunya

Barcelona, Spain

Digital Control of a Single-Phase Shunt

Active Filter

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Introduction• Proliferation of nonlinear loads ->This fact

has deteriorated the power quality of electrical power systems.

• More stringent requirements proposals IEC-61000-3-{2,4} and IEEE-519.

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Basic Concepts

sv

si Linear Load

Nonlinear Load

Active Filter

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Complete Picture

Full BridgeBoost Converter

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Boost Converter

1 2 1

2 1

1 sL x x r x vu

C x x

1 2 1

2 1

1 sL x x r x vu

C x x

r L

CsV 2x

1x

r L

CsV 2x

1x

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Boost Converter II

1 2 1

2 1

1 sL x x r x vu

C x x

1 2 1

2 1

1 sL x x r x vu

C x x

1 2 1

2 1

sL x ux r x v

C x ux

1 2 1

2 1

sL x u x r x v

C x u x

[ 1,1]u

The averaged model

1,1u

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Control Goals• Constant average value of the voltage at the DC

bus capacitor:

• Current in phase with the voltage waveform:

*

2 0 dx V

* sins d ri I t

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Proposed Control Scheme• Two control loops :

– Current loop : Digital Repetitive Control– Voltage loop : Classical PI Control

sin r t

Boost Converter

Repetitive Controller

PI Controller2x

dVdI

1x lI

*sI

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Current Control loop1 2 1 sL x u x r x v

2 dx V

1 1d sL x u V r x V

1

1

d

p

Vx s r G s

Lu s sr

1 ( )( ) 1 pp

G sG z z Z

s

ZOH, T

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Repetitive Control Basics

Nz

+

pT p sT N T

1

1NR z

z

2 2j iN

i ip

z e iN T

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Repetitive Control Scheme

pG z cG z

xG z F zNz

Repetitive Controller

1

c po

c p

G z G zG z

G z G z

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Repetitive Stability Conditions

1. First stability Condition : The System without the Repetitive Controller must be stable.

2. Second stability Condition

3. Third stability Condition :

cG z 1F z

1 1o xG z G z

xG z

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Voltage Loop

2 1C x u x 1 2C y u x x

22

2

xy

11

sin cos sind r l r l rl

Iload

x t I t a l t b l t

Current loop in steady state

21 2 21 12

k T k kd l l dkT

l

E TC y r I b a b I b

1

12k T k

dkT

E TC y I b

r=0

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Voltage Loop

21

E T

z

1b

PI

2

2dV

y

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Setup : General view

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Setup : IGBT drivers

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Setup : Control hardware

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Experimental Setup• Active filter parameters:

– Capacitor: 6600 uF, 450 V DC – Inductor: 0.8 mH– parasitic resistance: 0.04 Ohm– IGBT: 1200 V, 100 A

• Feedback paths (sensors):– Network voltage: voltage

transformer (220V/15V) – Network current: Hall-effect

sensor (TECSA-HA-050053) (50A)

– DC bus voltage: AD-215BY isolation amplifier

• Control hardware:– ADSP-21161 floating-point

DSP – ADMC-200 coprocessor:

A/D channels and PWM generation

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Experimental Results: Nonlinear Load

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Experimental Results: No-Load

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Experimental Results: Full NL load

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Experimental Results: Full load to No-load

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Experimental Results: No-load to full load

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Conclusions• The paper shows the design of an all digital

multirate controller for a single-phase parallel active filter.

• The inner current control loop is designed using a repetitive control approach that.

• The outer slow sampling rate voltage control loop presents a good dynamic behavior in front of sudden changes of the load.

r. griñó, r. costa-castelló and e. fossas instituto de organización y control (ioc)

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