Page 1 of 11
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online: https://ejbss.org/ P a g e | 1959
DFIG Control of Wind Energy Conversion System Using
Indirect Matrix Converter
PANDIARAJ .J
PG Student,
PRIST Deemed to be University, Thanjavur
ABSTRACT
This paper discusses a control scheme of Indirect Matrix
Converter which includes space vector modulation to
stabilize the frequency variations. The terminal voltage
and frequency of any synchronous machine can be
controlled easily with this scheme. The proposed method
leads to reduction of harmonics and losses predominantly
increasing the efficiency of output. More over the control
strategy is also very much flexible in their operation at
any rated power. This work is mainly focused on the
Matlab/Simulink implementation of SVM technique with
Zero current switching for IMC. The novelty of this work
is that a detailed analysis of directly AC to AC conversion
with no energy storage element has been done and the
SVM technique for IMC is implemented in
Matlab/Simulink embedded system. The techniqe has
been successfully implemented in wind energy
conversion system and results have been analyzed.
INTRODUCTION
The Cyclo-converters are direct AC to AC converter without
any DC-Link passive component in between. The demerits of
cyclo-converter are requirement of large number of switching
devices and complex control strategies for large 3 phase Cyclo- converter. Further, using Cyclo-converters the output frequency
can be varied only to 1/3rd of the input frequency. In Matrix
Converter topological scheme, there is no requirement of DC- Link storage elements. Further, it has a unique inherent bi- directional power flow capability. By using proper modulation
strategies, desirable Sinusoidal output voltage can be generated
by using this converter. Further, the input power factor can be
fully controlled. The Matrix Converter technology can be used
in all the Variable speed Drives. Now a days wind turbines are
subjected to variation of load and impact of frequent change in
wind speed with respect to the nonlinear behaviour of nature.
Induction motors are frequently used in real world for industrial
drive applications. Due to the advantage of bidirectional power
flow and controllable power factor the IMC can replace the
conventional back to back converter which has been
experimentally verified.
TOPOLOGICAL SCHEME OF IMC
The control strategy of IMC requires coordination between the
control of rectifier and inverter Stage unlike VBBC.
Page 2 of 11
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online: https://ejbss.org/ P a g e | 1960
The Space Vector based control strategy for MC gives better
performance compared to carrier based control strategies.
Further, the zero current switching of IMC can be easily
achieved in Space Vector based control strategy. The advantage
of zero current switching compared to forced commutation
process is that the switching loss is less. A major breakthrough
in the field of reduced and less complex switching strategy of
IMCs was brought by Kolar and Ertl with the development of
SMC in 2001. To understand this reduction in the switches, a
detailed study has been done considering a single phase leg of
the IMC as shown in figure. This leg of IMC is considered to be
connected to the Input phase "a". This phase "a" is connected to
the DC link through the switch Spa and Sap to the positive DC
link and Sna and San to the negative DC link. The switches in
this topology are arranged in such a manner that bi-directional
power flow can take place for both positive and negative DC- Link Voltages. The fig. 2.1(1) and fig. 2.1(2) shows the
condition when the DC-Link Voltage is positive and the current
direction is positive. In fig. 2.1(1) the current flows from the
Rectifier side to the Inverter side through Sap and Dap. In fig.
2.1(2) the current from Inverter side enters Rectifier side phase
"a" through Dna and Sna. The fig. 2.1(3) and fig. 3.3(4) shows
the condition when the DC-Link Voltage is negative and the
current direction is negative. In fig. 2.1(4) the current flows
from the Rectifier side to the inverter side through Dan and San.
In fig. 2.1(3) the current from Inverter side enters Rectifier side
phase "a" through Spa and Dpa. So, fig. 2.1 explains the bi- directional four quadrant power flow
Page 3 of 11
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 04
April 2019
Available online: https://ejbss.org/ P a g e | 1961
capability of IMC. At this point there is another important
concept to note that the inverter stage of the IMC can handle
only positive DC-Link polarity, but the four quadrant switch
current source type rectifier is capable of generating both
positive and negative DC Link voltage polarities. For the
inverter to work with negative DC-Link polarity the
arrangement of the switches has been reversed which is not
practically feasible.
Fig. 2.1. Current flow for positive power flow in one leg
Fig. 2.2. Four quadrant power flow in IMC
MODULATION SCHEME
The modulation strategy is devised in such a way that the DC- Link Voltage is always positive. With reference to the
symmetry of the circuit topology and an assumed symmetry of
the three phases input voltage system the input voltage to the
system can be considered as:
ua U1cos( )
ua U1cos(
2
3) (3.1)
ua U1cos(
2
3)
ua ub uc 0
