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Wednesday, 4 February 2015
Wednesday, 21 January 2015
Study of Induction Motor Drive with Direct Torque Control Scheme and Indirect Field Oriented Control Scheme Using Space Vector Modulation
Study of Induction Motor Drive with Direct Torque Control Scheme and
Indirect Field Oriented Control Scheme Using Space Vector Modulation
ABSTRACT:
Induction
motors are the starting point to design an electrical drive system which is
widely used in many industrial applications. In modern control theory,
different mathematical models describe induction motor according to the
employed control methods. Vector control strategy can be applied to this
electrical motor type in symmetrical three phase version or in unsymmetrical
two phase version. The operation of the induction motor can be analyzed similar
to a DC motor through this control method. With the Joint progress of the power
electronics and numerical electronics it is possible today to deal with the
axis control with variable speed in low power applications. With these
technological projections, various command approaches have been developed by
the scientific community to master in real time, the flux and the torque of the
electrical machines, the direct torque control (DTC) scheme being one of the
most recent steps in this direction. This scheme provides excellent properties
of regulation without rotational speed feedback. In this control scheme the
electromagnetic torque and stator flux magnitude are estimated with only stator
voltages and currents and this estimation does not depend on motor parameters
except for the stator resistance. In this dissertation report conventional DTC
scheme has been described. Induction motor has been simulated in stationary d-q
reference frame and its free acceleration characteristics are drawn.
Conventional DTC scheme has been simulated with a 50 HP, 460V, 60 Hz induction
motor. Literature review has been done to study the recent improvements in DTC
scheme which somehow is able to overcome the drawbacks of conventional one. The
space vector modulation technique (SVPWM) is applied to 2 level inverter
control in the vector control based induction motor drive system, thereby
dramatically reducing the torque ripple. Later in this project space vector PWM
technique will be applied to DTC drive system to reduce the torque ripple.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig.1
Block diagram of conventional DTC scheme for IM drives
EXPECTED SIMULATION RESULTS:
Fig.2
Electromagnetic torque
Fig.3
Rotor speed
Fig.4
Stator current
Fig.5
d-axis stator flux
Fig.6
q-axis stator flux
For
TL = 2 Nm
Fig.7
Electromagnetic torque
Fig.8
Rotor speed
Fig.9
Trajectory of d axis and q axis stator flux in stationary reference frame
Fig.10 Electromagnetic torque
Fig.10 Electromagnetic torque
Fig.11
Rotor speed
Fig.12
d-axis stator flux
Fig.13
q-axis stator flux
Fig.14
d-axis stator current
Fig.16 Mean value of
Phase voltage of inverter
Fig.17
Line voltage output of inverter
Fig.18
Electromagnetic torque
Fig.19
Rotor speed
Fig.20
q-axis stator flux
Fig.21
d-axis stator flux
CONCLUSION:
For
any IM drives, Direct torque control is one of the best controllers proposed so
far. It allows decoupled control of motor stator flux and electromagnetic
torque. From the analysis it is proved that, this strategy of IM control is
simpler to implement than other vector control methods as it does not require
pulse width modulator and co-ordinate transformations. But it introduces undesired
torque and current ripple. DTC scheme uses stationary d-q reference
frame with d-axis aligned with the stator axis. Stator voltage space
vector defined in this reference frame control the torque and flux. The main
inferences from this work are:
1.
In transient state, by selecting the fastest accelerating voltage vector which
produces maximum slip frequency, highest torque response can be obtained.
2.
In steady state, the torque can be maintained constant with small switching
frequency by the torque hysteresis comparator by selecting the accelerating
vector and the zero voltage vector alternately.
3.
In order to get the optimum efficiency in steady state and the highest torque
response in transient state at the same time, the flux level can be
automatically adjusted.
4.
If the switching frequency is extremely low, the control circuit makes some
drift which can be compensated easily to minimize the machine parameter variation.
The
estimation accuracy of stator flux is very much essential which mostly depends
on stator resistance because an error in stator flux estimation will affect the
behavior of both torque and flux control loops. The torque and current ripple
can be minimized by employing space vector modulation technique.
REFERENCES:
[1]
B. K.Bose. 1997. Power Electronics and Variable Frequency Drives. IEEE Press,
New York.
[2]
Kazmierkowski, R.Krishnan, Blaabjerg, Control in Power Electronics, Selected
Problems.
[3]
Takahashi Isao, Noguc hi Tos hihiko, „‟A New Quick-Response and High-Efficiency
Control Strategy of an Induction Motor‟‟, IEEE Transactions on Industry
Applications, Vol. IA-22 No-5, Sept/Oct 1986.
[4]
Thomas G.Habetler, Francesco Profumo, Michele Pastorelli and Leon M. Tolbert
“Direct Torque Control of IM us ing Space Vector Modulation” IEEE
Transactions on Industry Applications, Vol.28, No.5, Sept/Oct 1992.
[5]
E.Bassi, P. Benzi, S. Buja, “A Field Orientation Scheme for
Current-Fed Induction Motor Drives Based on the Torque Angle Closed-Loop
Control” IEEE Transactions on Industry Applications, Vol. 28, No. 5,
Sept./ Oct. 1992.
Sunday, 18 January 2015
24-Pulse Rectifier Realization By 3-Phase To Four 3-Phase Transformation Using Conventional Transformers
24-Pulse Rectifier Realization By 3-Phase To Four 3-Phase
Transformation Using Conventional Transformers
ABSTRACT:
A 24-pulse rectifier has been designed for high
voltage, low current applications. Four 3-phase systems are obtained from a
single 3-phase source using novel interconnection of conventional single- and 3-phase
transformers. From two 30º displaced 3-phase systems feeding two 6-pulse
rectifiers that are series connected, a 12-pulse rectifier topology is
obtained. Thus, from the four 3-phase systems that are displaced by 15º two
12-pulse rectifiers are obtained that are cascaded to realize a 24-pulse
rectifier. Phase shifts of 15º and 30º are made using phasor addition of
relevant line voltages with a combination of single-phase and three-phase
transformers respectively. PSCAD based simulation and experimental results that
confirm the design efficacy are presented.
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Figure 1 24-pulse rectifier realized by transforming
a single 3-phase system to four 3-phase systems using conventional single- and
three-phase transformers
EXPECTED SIMULATION RESULTS:
Figure 2 Input line voltages Va0b0, Vb0c0 and Vc0a0 at
diode bridge I
Figure 3 Input line voltages Va30b30, Vb30c30 and Vc30a30
at diode bridge II
Figure 4 Input line voltages Va15b15, Vb15c15 and Vc15a15
at diode bridge III
Figure 5 Input line voltages Va45b45, Vb45c45 and Vc45a45
at diode bridge IV
Figure 6 Line current in phase a of y0 winding of
Yy0d1 main transformer
Figure 7 Line current in phase a of d1 winding of
Yy0d1 main transformer
Figure 8 Six-pulse dc output voltage of diode bridge,
DBI
Figure 9 DC 6-pulse output voltage of diode bridge,
DBII
Figure 10 DC 12-pulse output voltage by cascading
diode bridges I and II
Figure 11 Six-pulse dc output voltage of diode
bridge, DBIII
Figure 12 DC 6-pulse output voltage of diode bridge,
DBIV
Figure 13 DC 12-pulse output voltage by cascading
diode bridges III and IV
Figure 14 DC 24-pulse voltage by cascading DBI,
DBII, DBIII and DBIV
Figure 15 Line current in phase a of Y winding of
Yy0d1 main transformer
Figure 16 Line current in phase a of Y winding of
Yy0d1 main transformer
Figure 17 Panned view of 24-pulse dc voltage
Figure 18 24-pulse dc voltage
Figure 19 Experimental set up
CONCLUSION:
A
24-pulse rectifier is realized by conventional transformers that meets the
theoretical harmonic
and
ripple estimates.
REFERENCES:
[1] IEEE Recommended Practices and
Requirements for Harmonics Control in Electric Power Systems, IEEE Std. 519, 1992.
[2]
Electromagnetic Compatibility (EMC)—Part 3: Limits-Section 2: Limits for
Harmonic Current Emissions (Equipment Input Current (16A per Phase),
IEC1000-3-2, Dec., 1995.
[3]
Draft-Revision of Publication IEC 555-2: Harmonics, Equipment for Connection to
the Public Low Voltage Supply System, IEC SC 77A, 1990.
[4]
Bhim Singh, B. N. Singh, A. Chandra, Kamal Al-Haddad, Ashish Pandey, and D. P.
Kothari, “A Review of Three-Phase Improved Power Quality AC-DC Converters”,
IEEE Trans. Ind. Electron., vol. 51, No. 3, June 2004, 641-660.
[5]
S. Choi, “New pulse multiplication technique based on six pulse thyristor
converters for high power applications,” IEEE Trans. Ind. Appl., vol.
38, no. 1, pp. 131–136, Jan./Feb. 2002.
Sunday, 4 January 2015
Implementation Of Perturb And Observe MPPT Of PV System with Direct Control Method Using Buck And Buck boost Converters
Implementation Of Perturb And Observe MPPT Of PV System with Direct Control
Method Using Buck And Buck boost Converters
ABSTRACT:
The Maximum Power Point Tracking (MPPT) is a
technique used in power electronic circuits to extract maximum energy from the
Photovoltaic (PV) Systems. In the recent decades, photovoltaic power generation
has become more important due its many benefits such as needs a few maintenance
and environmental advantages and fuel free. However, there are two major
barriers for the use of PV systems, low energy conversion efficiency and high
initial cost. To improve the energy efficiency, it is important to work PV system
always at its maximum power point. So far, many researches are conducted and
many papers were published and suggested different methods for extracting
maximum power point. This paper presents in details implementation of Perturb
and Observe MPPT using buck and buck-boost Converters. Some results such as
current, voltage and output power for each various combination have been
recorded. The simulation has been accomplished in software of MATLAB Math works.
KEYWORDS
1. Maximum Power Point Tracking
2. Perturb and
Observe
3. DC-DC Converters
4. Photovoltaic System
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Figure
1. PV module and dc/ dc converter with MPPT
Figure
2. Block diagram of a PV array connected to the load
EXPECTED SIMULATION RESULTS:
Figure
3. Output current, voltage and power of PV panel (insolation changed from 400
to 200 w/ m² at a time of 4.915 sec.)
Figure
4. Output current, voltage and power of buck converter with P&O algorithm
(Insolation
changed from 400 to 200 w/ m² at a time of 4.915 sec.)
Figure
5. output current, voltage and power of PV panel (Insolation changed from 400
to 200 w/ m² at a time of 5.017 sec.)
Figure
6. Output current, voltage and power of buck-boost converter with P&O
algorithm
(Insolation
changed from 400 to 200 w/ m² at a time of 5.017 sec.)
CONCLUSION:
P&O
MPPT method is implemented with MATLAB-SIMULINK for simulation. The MPPT method
simulated in this paper is able to improve the dynamic and steady state
performance of the PV system simultaneously. Through simulation it is observed
that the system completes the maximum power point tracking successfully despite
of fluctuations. When the external environment changes suddenly the system can
track the maximum power point quickly. Both buck and buck-boost converters have
succeeded to track the MPP but, buck converter is much more effective specially
in suppressing the oscillations produced due the use of P&O technique.
REFERENCES:
[1]
A.P.Yadav, S. Thirumaliah and G. Harith. “Comparison of MPPT Algorithms for
DC-DC Converters Based PV Systems” International Journal of Advanced Research
in Electrical, Electronics and Instrumentation Engineering Vol. 1, Issue 1,
July 2012.
[2]
Y.-H.Chang and C.-Y. Chang, "A Maximum Power Point Tracking of PV System
by Scaling Fuzzy Control," presented at International Multi Conference of
Engineers and Computer Scientists, Hong Kong, 2010.
[3]
S.Mekhilef, "Performance of grid connected inverter with maximum power
point tracker and power factor control," International Journal of Power
Electronics, vol.1, pp. 49-62.
[4]
M.E.Ahmad and S.Mekhilef, "Design and Implementation of a Multi Level
Three-Phase Inverter with Less Switches and Low Output Voltage
Distortion," Journal of Power Electronics, vol. 9, pp. 594- 604, 2009.
[5]
H.N.Zainudin and S. Mekhilef, "Comparison Study of Maximum Power Point
Tracker Techniques for PV Systems" Proceedings of the 14th International Middle
East Power Systems Conference (MEPCON’10), Cairo University, Egypt, December
19-21, 2010.
Simulation and Analysis of Perturb and Observe MPPT Algorithm for PV Array Using ĊUK Converter
Simulation and Analysis of Perturb and Observe MPPT
Algorithm for PV Array Using ĊUK Converter
ABSTRACT:
This
paper presents the comparative analysis between constant duty cycle and Perturb
& Observe (P&O) algorithm for extracting the power from Photovoltaic
Array (PVA). Because of nonlinear characteristics of PV cell, the maximum power
can be extract under particular voltage condition. Therefore, Maximum Power
Point Tracking (MPPT) algorithms are used in PVA to maximize the output power.
In this paper the
MPPT algorithm is implemented using Ćuk converter. The
dynamics of PVA is simulated at different solar irradiance and cell temperature.
The P&O MPPT technique is a direct control method enables ease to implement
and less complexity.
KEYWORDS
1. Photovoltaic Array (PVA)
2. MPPT
3. ĆUK Converter
SOFTWARE: MATLAB/SIMULINK
BLOCK DIAGRAM:
Fig. 1: Block Diagram of MPPT
Using PI Controller
Fig. 2: Block Diagram of Direct
Duty Cycle (δ) Control MPPT
EXPECTED SIMULATION RESULTS:
Fig. 3: MATLAB/SIMULINK Model of PVCC for δ
=0.6
Fig. 4: Output Power Curve of the PV Module and Ćuk Converter for Constant
δ = 0.6 and Different β.
Fig. 5: Output Power Curve of the PV Module and Ćuk Converter for Constant
δ = 0.6 and Different T
Fig. 6: MATLAB/SIMULINK Model
of PVCC Using P & O Algorithm
Fig. 7: Output Power Curve of the PV Module and Ćuk
Converter for Different β and P&O MPPT
Fig. 8: Output Power Curve of the PV Module
and Ćuk Converter for Different T and P & O MPPT.
CONCLUSION:
In
this paper, P&O and constant duty cycle algorithm of MPPT is implemented
using ĆUK converter. The model is
simulated with MATLAB/SIMULINK. It is shown that PV system
output power increases with rise in solar irradiance and fall in cell temperature.
Therefore, solar cell performance better in winter season than summer. The
P&O gives the optimum duty cycle as compare to Constant duty cycle control,
to extract the maximum power from PV system.
REFERENCES:
[1]
Ali Chermitti, Omar Boukli-Hacene and Samir Mouhadjer (2012) “Design of a
Library of Components for Autonomous Photovoltaic System under Matlab/Simulink”,
International Journal of Computer Applications (0975 – 8887), Volume
53– No.14.
[2]
Ankur Bhattacharjee (2012) “Design and Comparative Study of Three Photovoltaic
Battery Charge Control Algorithms in MATLAB/SIMULINK Environment”, International
Journal of Advanced Computer Research (ISSN (print): 2249-7277 ISSN
(online): 2277-7970), Volume-2 Number-3 Issue-5.
[3]
Athimulam Kalirasu and Subharensu Sekar Dash (2010) “Simulation of Closed
Loop Controlled Boost Converter for Solar Installation,” SERBIAN JOURNAL
OF ELECTRICAL ENGINEERING, Vol. 7, No. 1.
[4]
Azadeh Safari and Saad Mekhilef (2011) “Simulation and Hardware Implementation
of Incremental Conductance MPPT with Direct Control Method Using Cuk
Converter”, IEEE Transaction on Industrial Electronics, Vol.58,
no.4.
[5]
E. Durán, M.B. Ferrera, J.M. Andújar, M.S. Mesa (2011) “I-V and P-V Curves
Measuring System for PV Modules based on DC-DC Converters and Portable
Graphical Environment” IEEE, 978-1-4244.
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