PRESENTER: POOYA DAVARI 26 AUG 2015 WWW.NHTD.ET.AAU.DK Pooya Davari 1 , Yongheng Yang 1 , Firuz Zare 2 and Frede Blaabjerg 1 1 Department of Energy Technology, Aalborg University, Denmark 2 Danfoss Power Electronics A/S, Grasten, Denmark A Multi‐Pulse Pattern Modulation Scheme for Harmonic Mitigation in Three‐Phase Multi‐Motor Drives
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1 Yang1 Firuz Zare2 and Frede 1 - Aalborg Universitet · PRESENTER: POOYA DAVARI 26 AUG 2015 Pooya Davari1, Yongheng Yang1, Firuz Zare2 and Frede Blaabjerg1 1Department of Energy
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PRESENTER: POOYADAVARI26AUG2015
WWW.NHTD.ET.AAU.DK
Pooya Davari 1, Yongheng Yang1, Firuz Zare2 and Frede Blaabjerg1
From power quality point of view the main concern with ASD systems is the generation ofcurrent harmonics which may lead to high losses and stability issues in the grid
Developing energy efficientmotor drive systems holds agreat potential for reducing theworldwide energy consumption.
Introducing Adjustable SpeedDrive (ASD) based on powerelectronics technology leads tomore energy efficient motordrive systems.
4Introduction
StandardThree‐PhaseMotorDriveSystem
Diode rectifier: simple, cost effective and efficient solution. But it imposes high level of inputcurrent harmonics.
AC or DC side passive filtering (inductor): simple and effective to some extent. But they arebulky, costly, causes resonance, worsen system dynamic, and etc.
Active harmonic mitigation solutions have been introduced to improve the input current quality.But they are complex, costly and reduce system efficiency.
In many applications it is a common practice to employ parallel connected drive units. In thissituation the application demand is met using multiple modestly sized motor units ratherthan one single large unit.
The undesirable nonlinearity of theconventional AC‐DC conversion stagebecomes significant, when a largenumber of industrial converters andASD systems are connected to thePoint of Common Coupling (PCC).
The feasibility of this solution isattained only when suitable andaccessible communication amongthe nonlinear units can beperformed. Single‐Drive Multi‐Drive
Although an appropriate adjustmentof the phase angle of the SCR unit cancontribute to an improvement of thecurrent quality, a new currentmodulation technique is applied toeach DC‐DC converter in order tofurther improve the current quality.
Symbol PARAMETER Valuevg,abc Grid phase voltage 220 Vrmsfg Grid frequency 50 HzZg (Lg, Rg) Grid impedance 0.1 mH, 0.01 ΩLdc DC link inductor 2 mHCdc DC link capacitor 470 µFVo Output voltage 700 VdcKp, Ki PI controller (Boost converter) 0.01, 0.1Kf, ts, ξ PLL parameters 0.8, 0.2 s, 1.41HB Hysteresis Band 2APo_total Total output power ≈5.5 kW
Parameters of the multi-rectifier systemLs
Cdc RL1
Vos*
vos
PI
iLs
iLsums
iLs*
Ld
Cdc RL2
Vod*
vod
PI
iLd
iLdumd
iLd*
is
id
ig,abc
PLL1 Firing Driverα
vab
PCC
GridZg
ωt
Modulation Signal
ωtα
Modulation Signal ωt
vrec_s
vrec_d
vab
ωtPLL2
20ExperimentalResults
Harmonic Mitigation Strategy
Harmonic Distribution and THDi (%)
ia (5)/ ia (1) ia(7)/ ia (1) ia(11)/ ia (1) ia (13)/ ia (1) THDi
As long as the following equation holds true, therectifiers will draw equal amount of current form thegrid; otherwise it should be reflected in theoptimization process.