International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 4- June 2015
A Novel Single Phase Bidirectional Frequency Based Transformer for
DC to AC
Madhusudana Rao Ranga
Assistant Professor
Department of EEE, VR Siddhardha Engineering College, Kanuru, Vijayawada
Abstract :In this paper we are proposing a novel single
phase bi directional extensive frequency based transformer
which links ac/dc converter model for adjustable
magnitude and frequency devices as drive.This king of
converters more suitable for energy resources, solar energy
services, fuel cells because it converts from low voltage dc
to high voltage ac. It is at low cost, optimal performance
and with less weight.Our proposed model gives optimal
results than the traditional models,there is no need of
auxiliary circuits and support for leakage of energy and
stabilization of voltages while dc to ac conversion.
I. Introduction:
In the years of approach various approaches proposed
from researchers, every converter has their ownadvantages
and disadvantages in terms of power consumption, energy
resources, weight of the device,auxillary circuit and cost
effectiveness of the architecture.Efficient switching
mechanism provided in the architecture for conversion of
the dc to ac in optimal manner. Many power converter
topologies, work has concentrated on the derivation of
modulation and control strategies and In comparison to a
dc-link voltage source inverter (VSI) to the modulation of
the switches in the matrix converter is more difficult since
three changing voltages can be used for the modulation.
Methods analogous to VSI modulation strategies which use
only the most positive and negative available voltages are
presented [1] [2].
Typically transformers can be used at different voltage
levels and there is safety is the primary concern during the
isolation. To make the factors like weight and cost we can
replace the line frequency transformer to high frequency
transformers[3]. Inverters works at high power density,this
is the reason it can be used at wide range of applications
including uninterruptible power sources (UPS), distributed
power generation from renewable energy sources like solar
and wind (connecting HVdc grid to offshore wind
generators [4]), energy storage systems (battery interfaced
grid tied inverters), vehicle to grid applications, fuel cell
powered electric motor drives, and also in space and naval
applications where a compact solution is necessary.
The control and modulation of a matrix converter is a very
significant research subject area, and detailed analysis is
ISSN: 2231-5381
beyond the scope of this paper. It is, however, in many
ways very similar to that of a traditional VSI. The
difference being that the switching states of the converter
do not need to be chosen based only on the desired output
voltage but can also include the input current. Many
modulation algorithms have been presented in the
literature. In [4], both the input current and the output
voltage are taken into account, and all three available input
voltages are used in the modulation of the converter. The
space vector modulation (SVM) technique described in [5]
and [6] has also been successfully applied to matrix
converters. In [7], the SVM technique under abnormal
input conditions is exam- ined. Advanced methods such as
the predictive control tech- nique described in [8] and the
sliding mode control described in [9] have also been
analyzed and implemented. A generalized technique for the
modulation of matrix converters is described in [10], and a
modulation technique for matrix converters with any
number of output phases is presented in [11].
II. Related Work :
The main building block of the matrix converter is the
bidirectional semiconductor switch. A single device that
can both conduct current in each direction and block
voltage in both directions is currently not commercially
available, although some work has been reported into the
monolithic bidirectional switch in [10]–[12], and various
bidirectional insulated gate bipolar transistor (IGBT)
structures were presented in [9]. The following section will
describe common arrangements used to generate the
necessary bidirectional switches.
Switch Technologies
In the infancy of the research into matrix converters, the
bipo- lar junction transistor was the most commonly used
controlled switch [8]. Other options include the MOSFET,
the gate turnoff thyristor (GTO), and the integrated gate
commutated thyristor (IGCT). The use of the MOSFET is
typically restricted to low-power applications due to the
limited blocking voltages available, and the limited
switching frequency of both the GTO and the IGCT limits
their use in matrix converter applications. Other power
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 4- June 2015
semiconductor devices include the MOS turnoff thyristor
(MTO) described in [11] and the MOS controlled thyristor
(MCT) described in [2]. The MTO, like the GTO, was
designed for high-power applications, and similar
limitations on switching frequency exist; nevertheless,
matrix converters using MTOs have been reported
together with the lower power MCTs . Most matrix
converter applications currently use IGBT de- vices and
diodes to create the power circuit. The reverse blocking
IGBT (RB-IGBT) is also gaining popularity since
antiparallel diodes can be eliminated from the converter.
switching speed of high-voltage switches. It has been
shown in this paper that additional switching transitions of
the input side converter required for leakage inductance
commutation can be made loss less. The proposed
modulation strategy results in high-quality PWM voltage
generation similar to conventional space vector modulation
(CSVPWM), [5]. The proposed topology is particularly
applicable to high-quality motor drives with a low dc bus
voltage.
Active Device Arrangements
The proposed model provides an effective means of
feedback controllers for uncertain systems, most of the
traditional models developed under assumption of full state
can be completed directly, If the full-state information is
not available and only the output is accessible, in single
phase to three phase converters, it is directly connected to
secondary HFT to reduce the load, initially it normalizes
the high frequency ac and generates a three phase ac.
Most of the bidirectional switches are constructed of
available in unidirectional or bidirectional devices and with
typical arrangements, even though it contains one active
device,it losses are higher than other arrangements, since
the current flows through one switch and two diodes and
common emitter (CE) common collector (CC)
arrangements allow the current direction to be controlled
and this allows greater flexibility when performing the
commutation of current between input phases.
The adverse effects (shaft voltage build up, bearing
currents, and EMI issues) of switching the common-mode
voltage in a two-level inverter have been extensively
studied in the context of PWM ac drives ,One solution to
this problem is the use of active or passive common-mode
filter .It is well known that modulation-based schemes for
common- mode voltage elimination that do not require
extra filter circuits usually results in the reduction in the
quality and the range of the output voltage . Dual-inverterbased topologies with a single dc link for an open-end
winding machine
and parallel phase windings) are presented and for the
common-mode voltage elimination. The problem of ground
leakage current in PV and battery connected inverters is
well known .Some applications even require grounding of
the PV panel or negative rail of the battery. Isolation may
reduce the effect but does not eliminate it . This paper
presents a single-stage high-frequency link in- verter
topology with a modulation strategy that leads to the
suppression of the common-mode voltage; . The three wire
nature of the ac side connection also avoids the flow of the
additional circulating currents . Power flow is completely
bidirectional. A source-based commutation technique
similar to has been outlined that results in the complete
recovery of leakage energy without any additional circuits
along with minimization of common-mode voltage
switching due to com- mutation. The secondary-side
converter is soft switched. This feature is particularly
desirable in a high-voltage ac application due to the slow
ISSN: 2231-5381
III. Proposed work:
For both of these topologies or models it is known that it is
possible to switch the primary side of the H bridge at zero
current by applying a zero state in the output or upper
sideconverter. Here the modulation strategies have been
proposed for the partial or complete soft switching of the
secondary-side of the converter and auxiliary circuits are
used for the commutation of leakage energy and a sourcebased commutation of the leakage energy has been
proposed that obviates the need of additional circuits. This
idea has been extensively applied to the single-phase highfrequency link inverters and more over adverse effects the
shaft voltage build up levels, bearing of currents and other
EMI issues) of switching the common-mode voltage in a
two-level inverter have been extensively studied in the
context of PWM ac drives. One optimal solution to this
problem is the use of active or passive common-mode filter
. It is well known that modulation-based schemes for
common- mode voltage elimination that do not require
extra filter circuits usually results in the reduction in the
quality and the range of the output voltage and Dualinverter-based topologies with a single dc link for an openend winding machine .
We consider the sliding-mode output feedback controller
(SMOFC) design problem for a class of uncertain multivariable systems. We first design a stabilizing SMOFC for
matched uncertain systems. Using linear matrix inequalities
(LMIs), we derive a necessary and sufficient condition for
the existence of a linear sliding surface depending on
outputs and compensator states. Using the solution of the
LMI existence condition, we characterize the gain matrices.
We give the nonlinear switching feedback gain
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 4- June 2015
guaranteeing the reachability condition. Second, we give an
LMI-based design method to combine various useful
performance criteria which can be used to guarantee a
desired robust performance in spite of mismatched
uncertainties. The performance criteria include α-stability,
LQ performance, H2/H∞ performance, and peak-to-peak
gain bound. In particular, we show that by including H∞
performance constraints, we can easily solve the SMOFC
design problem for challenging system models to which the
previous methods are not easily applicable. Finally, we
give a numerical design example showing that our method
can be successfully applied to the problem of designing
reduced-order SMOFCs for uncertain time-delay systems
or mismatched uncer- tain systems.
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The proposed work is divided into two parts ,one is
regarding power transfer and computation of the energy
leakage The following figure shows the control signals of
the modulation of the topology and controlled by the
signal. second upper half transfers the power to the system
,then power goes low and transfers through lower half of
the secondary windings.it reduces the power consumption
and weight
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 4- June 2015
Problem Formulation
Assume here that the desired command output profile is
given in the form
yc = A’ + B’ sinωnt……………………… (1)
e−sτ≈(1− (sτ/2) + (s2τ2/10)–(s3τ3/120))/( 1+(sτ/2 )+
(s2τ2/10) + (s3τ3/120)) ……………….(7)
Where s is the Laplace variable. We introduce a new output
variable ˜ y to make the approximation exact. By
introducing a new variable η =˜ y +(−1)jq,
In the following discussion, we will abuse notation by
setting q1 = q. Then, we can assume the output tracking
(command) profile qc (corresponding to q) as follows:
the system (13) can be approximated by
qc = A + B sinωnt + C cosωnt……………….(2)
˙y =˙ η−(−1)jq2˙
where A, B, C, and ωn are piecewise constants and A, B,
and C can be calculated using the output redefinition
function (6). The signal can be described by a linear system
of ex- ogenous differential equations with the following
characteristic polynomial:
q2 = ˆ φ(˜y,q2,ζ,t)+ˆ b(˜y,q2,ζ)u-------------(8)
3
2
2
λ +0λ + ω nλ +0 …………………………. (3)
Now, we restrict φ^(·) to be bounded. B^(·) is nonsingular.
Assume that the output of y is accessible with a fixed time
delay τ. This is equivalent to the modified output q with a
time delay τ; we define
Y^(t)=q(t−τ)………………………………. (4)
The problem is to design SM control u(t) that forces the
output variable y^ to track asymptotically the command
profile qc or the delayed output y(t−τ) to track
asymptotically yc. Note that the fixed time delay τ should
not be assumed large since the Padé approximation works
only for smaller time delays.
IV. PADÉ APPROXIMATIONS AND TIME-DELAY
SYSTEMS
In this section, we use the Padé approximation to approximate the time delay. The Padé approximation [1] uses the
quotient of two polynomials to estimate a power series. We
will use the direct solutions of the Padé equations
˙ ζ = ˜ Q1ζ + ˜ Q2˜ y
where η is the first row of ζ and j is the Padé order. For the
first-order Padé approximation ˜
Q1 =2/ τ
Q2 =−4 /τ
for the second order
˜ Q1 =
Q2
=-12/
----------------(9)
and for the third order ˜ Q1
Q2
=
For (7)–(8), respectively, system (6) is non minimum phase
because ˜ Q1 has at least one non-Hurwitz eigenvalue.
Note that the output delay system tracking problem has
been transformed into a non minimum-phase-system output
tracking problem (with no delay) by the Padé
approximation. However, there is an important difference
between ˆ y and ˜ y. We will investigate this in Section.
[L/M]=PL(x)/QM(x) ---------------------------(5)
V.Conclusion :
where PL(x) is a polynomial of degree L and QM(x) is a
polynomial of degree M. When we approximate a formal
power series f(x), the explicit equation is
We are concluding our current research work with
efficient converter topology with three phase PWM drive
model. The proposed mechanism provides advantages: It
efficiently provides the bidirectional power, optimal
voltage stabilization with low cost for high frequency
transformers. Switch on the power whenever switching
required otherwise it can be set to zero, provides complete
leakage energy recovery withoutauxiliary circuits and
provides high quality output than traditional approaches
and provides optimal switching for output side converter.
lim x→0QM(x)f(x)−PL(x) xL+M=0 .----------(6)
The corresponding Laplace transform of (6) ˆ y(s)/q(s)=
e−sτ can always be approximated by first-, second- and
third- order Padé approximations as
e−sτ ≈ (1− sτ/ 2)/(1+sτ /2)
e−sτ≈(1−( sτ /2) +( s2τ2/12))/ (1+(sτ/2) +( s2τ2 /12))
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International Journal of Engineering Trends and Technology (IJETT) – Volume 24 Number 4- June 2015
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