Download a non isolated three-port dc–dc converter and three

A NON ISOLATED THREE-PORT DC–DC CONVERTER AND THREEDOMAIN CONTROL METHOD FOR PV-BATTERY POWER SYSTEMS
ABSTRACT:
A new no isolated multiinput multioutput dc–dc boost converter is proposed in this
paper. This converter is applicable in hybridizing alternative energy sources in
electric vehicles.In fact, by hybridization of energy sources, advantages of different
sources are achievable. In this converter, the loads power can be flexibly
distributed between input sources. Also, charging or discharging of energy storages
by other input sources can be controlled properly. The proposed converter has
several outputs with different voltage levels which makes it suitable for interfacing
to multilevel inverters. Using of a multilevel inverter leads to reduction of voltage
harmonics which, consequently, reduces torque ripple of electric motor in electric
vehicles. Also, electric vehicles which using dc motor have at least two different dc
voltage levels, one for ventilation system and cabin lightening and other for
supplying electric motor. The proposed converter has just one inductor. Depending
on charging and discharging states of the energy storage system (ESS), two
different power operation modes are defined for the converter. In order to design
the converter control system, small-signal model for each operation mode is
extracted. The validity of the proposed converter and its control performance are
verified by simulation and experimental results for different operation conditions.
INTRODUCTION:
Except for direct energy transfer power systems, a pulse-width modulation
switching dc/dc converter controlled by the maximum power point tracking
(MPPT) algorithm has been used to extract the maximum power of photovoltaic
(PV) in PV-battery power systems.
Recently, three-port converters, interfacing one PV port, one bidirectional battery
port, and one load port of a PV-battery dc power system, are a good candidate for
such a renewable power system, particularly for a spacecraft power supply system.
Because of the high power density and high efficiency merit of the three-port
converters, it has increasingly attracted research interest toward various
applications
In general rules were carried out to derive no isolated and isolated multiple-input
converters from the single-input versions, which are adopted to identify the
feasible input cell that complies with some assumptions and conditions. the simple
and cost-effective approach based on a buck or a buck–boost topology was
proposed.
However, these converters have no power flow path for charging when a battery is
connected, which are not fit for a PV-battery dc power system. The converter
proposed in can interface two unidirectional input power ports and a bidirectional
port for a storage element. Only two power inductors have been utilized; however,
the number of metal–oxide– semiconductor field-effect transistor (MOSFET) and
power diode reaches eight.
A systematic approach is given in to generate nonisolated three-port converters;
these converters feature high integration and high efficiency due to one-stage
conversion. However, the inherent right-half-plane zero (RHPZ) of traditional
boost deteriorates both the dynamic performance and ac characteristic of the
converter, and the current of the port is discontinuous.
In a multiple-port dc/dc converter for regulated satellite power bus has been
proposed. The converter has high power density by sharing common power
devices and merits a good modularity property by using conductance current
control.
However, the battery port voltage of the converter must be higher than the bus
voltage, which will make the battery design difficult and unsafe. Moreover, it is a
two-stage power conversion from PV to bus, deteriorating the whole converter
efficiency.
Furthermore, in order to make the PV voltage close to the battery voltage for
higher efficiency, the PV voltage design will be difficult, since the voltage of the
battery will be changed when charging and discharging. In, a threeport converter
with high-voltage gain has been proposed, and the port current of the converter in
the low-voltage side can be continuous. However, semiconductor power devices
reach seven, which will complicate the whole system design.
EXISTING SYSTEM:
The dc–dc full-bridge converter uses resonant techniques in which resonant
elements such as capacitors and inductors are used to shape the current through a
converter switch so that it can fall to zero to allow the switch to turn off with ZCS.
The resonant elements, however, are large and bulky, which makes their use
impractical for many applications, and the converter is operated with variable
frequency control, which makes the design of the converter more difficult and also
increases the size of the converter as it must operate with low switching
frequencies at lighter loads
PROPOSED SYSTEM:
VSA, VBAT, and VBUS denote the voltage of the PV port, the battery port,
and the load port, respectively. L1, L2, and L3 refer to the dc inductor. CIN,
CBAT, and CBUS are the filter capacitors paralleled with the corresponding port.
The duty cycles of Q1 to Q3 are represented by d1 to d3, respectively, where d2
and d3 are complementary. The proposed B3C merits high power density by
sharing some common power devices, high efficiency by making one stage power
conversion from PV or battery or load, high dynamic performance by employing
the two-inductor boost topology, and modular and recurrent property by
controlling both battery and load port. In addition, battery voltage can be lower
than that of main bus for safety purposes.
ADVANTAGES:
 Improving the whole topology EMC property and making B3C able to
extract maximum power from PV.
 The efficiency of the converter is greatly improved.
 Leading to high power density.
 Reduced costs.
 Based on the three-domain main bus control method, the bus voltage is
always regulated with high quality in all power flow conditions
BLOCK DIAGRAM:
TOOLS AND SOFTWARE USED:
 MPLAB – microcontroller programming.
 ORCAD – circuit layout.
 MATLAB/Simulink – Simulation
APPLICATIONS:
 PV-battery power systems.
CONCLUSION:
A new multiinput multioutput dc–dc boost converter with unified structure
for hybridizing of power sources in electric vehicles is proposed in this paper. The
proposed converter has just one inductor. The proposed converter can be used for
transferring energy between different energy resources such as FC, PV, and ESSs
like battery and SC. In this paper, FC and battery are considered as power source
and ESS, respectively. Also, the converter can be utilized as single input
multioutput converter. It is possible to have several outputs with different voltage
levels. The converter has two main operation modes which in battery discharging
mode both of input sources deliver power to output and in battery charging mode
one of the input sources not only supplies loads but also delivers power to the other
source (battery). For each modes, transfer functions matrices are obtained
separately and compensators for closed loop control of the converter is designed. It
is seen that under various conditions such as rapid rise of the loads power and
suddenly change of the battery reference current, output voltages and battery
current are regulated to desired values. Outputs with different dc voltage levels are
appropriate for connection to multilevel inverters. In electric vehicles, using of
multilevel inverters leads to torque ripple reduction of induction motors. Also,
electric vehicles which use dc motors have at least two different dc voltage levels,
one for ventilation system and cabin lightening and other for supplying electric
motor. Moreover, in grid connection of renewable energy resources like PV, using
of multilevel inverters is useful. Finally, operation of this converter was
experimentally verified using low-power range prototype.
.
REFERENCES:
[1] X. Zhang and C. Mi, Vehicle Power Management, New York, NY, USA:
Springer, 2011.
[2] M. Ehsani, Y. Gao, and A. Emadi, Modern Electric, Hybrid Electric and Fuel
Cell Vehicle Fundamentals, Theory and Design, 2nd ed., New York, NY, USA:
CRC Press, 2010.
[3] P. Thounthong, V. Chunkag, P. Sethakul, B. Davat, and M. Hinaje
“Comparative study of fuel-cell vehicle hybridization with battery or
supercapacitor storage device,” IEEE Trans. Veh. Technol., vol. 58, no. 8, pp.
3892–3905, Oct. 2009.
[4] L. Wang, E. G. Collins, and H. Li “Optimal design and real-time control for
energy management in electric vehicles,” IEEE Trans. Veh. Technol., vol. 60, no.
4, pp. 1419–1429, May 2011.