International Journal of Recent Advances in Engineering & Technology (IJRAET)
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An Advanced Technique of Bidirectional DC-DC Converter for Reduction in Leakage Current
1Kumar Goswami, 2Shrutika Suryawanshi
1,2Dept. of ECE MATS University Gullu Aarang, Raipur Chhattisgarh, India
Abstract—This paper presents a brand new resonant twin active bridge (DAB) topology, that uses a tuned inductor–
capacitor–inductor (LCL) network. compared to standard DAB topologies, the planned topology considerably reduces the bridge currents, lowering each conductivity and switch losses and therefore the VA rating related to the bridges.
The performance of the DAB is investigated employing a mathematical model below varied operational conditions.
Experimental results of a 2.5-kW model, that has a potency of 96 at rated power, are conferred with discussions to demonstrate the improved performance of the tuned LCL DAB topology. Results clearly indicate that the planned DAB topology offers higher potency over a good vary of each input voltage and load compared to standard DAB topologies
Keywords— DC-DC converter, PID Controller, Neural Network, Gain constant, Battery source
I. INTRODUCTION
IN recent years, world considerations concerning future fuel shortages have spurred efforts to scale back the reliance on oil, coal, and gas to come up with electricity.
Consequently, electricity is progressively generated from star, wind, or recurrent event energy sources.
These source a renewable in nature[1], however extremely variable, resulting in the chance of great dynamic mismatches between electricity offer and demand levels. How-ever, it's been planned that the degree of mismatching may be reduced through desegregation the batteries of electrical vehicles (EVs), that aren't getting used at any given time, into national electrical grid. this may give a method for dynamic grid stabilization, however needs a bi face power interface between the grid and EVs to permit vehicle-to-grid (V2G) energy transfers to require place.[2-5]
Among the numerous varieties of bi face dc–dc converters that might be employed in a V2G system, the DAB device could be a most well-liked choice, because it features a tiny element count, offers isolation, and permits for prime power operation. additionally, it's the power to accommodate a good vary of voltage levels, because it could also be controlled to work in buck or boost modes.[8] However, a traditional DAB device victimization single phase-shift (SPS) control attracts an
oversized reactive current element at low operational power levels,that will increase the device conductivity losses. This current element conjointly necessitates the utilization of a bigger dc-link condenser [9-11].
Therefore, varied techniques are wont to lower the reactive current levels. Pulse breadth modulation (PWM) of the upper voltage bridge was used with SPS to increase the zero-voltage-switching (ZVS) vary to extend the device low-load potency, through a discount within the reactive current[12], [16]. Triangular and quadrangle modulation schemes were investigated in an attempt to scale back the present and, therefore, the conductivity losses. Primarily, this resulted during a reduction within the switch losses by achieving zero current switch in a number of the switches, the re-active power was reduced by victimization equal PWM on every bridge, moreover as a part shift between the bridges. Similar control techniques to it in were used, except that the PWM was actively controlled by an rule.
Bridge losses were decreased within the former, whereas ZVS was extended to the total operational point the latter. However, the device efficiencies in each cases were still restricted for big variations within the voltage conversion magnitude relation, significantly below low power operational conditions [17]. instead of minimizing bridge losses, the main focus was the step- down of either the reactive power, or the rms, or peak current values, in line with a selectable rule. For this method, twin phase-shift control comprising equal PWM of every bridge was used, moreover as a part shift between the bridges. Whereas every of the algorithms was effective in up the converter’s performance over that of SPS, the ensuing potency was but ninetieth at full power, and notably less at low power[20-22]. In an attempt to scale back the rms currents and increase the ZVS vary, freelance PWM control of every bridge, moreover as a part shift between the bridges, was utilized. A composite modulation theme was planned, whereby the control rule transitioned from twin PWM, at low phase-shift values, through to single PWM that varied linearly to a most for a phase-shift price of π/2 at full power[14]. This provide important enhancements in low-load potency while not a loss within the full-power capability. For a dc conversion ratio of 2:1, the potency varied from seventy seven at a third load through to around ninetieth at full load. However, this device
needed a lot of sophisticated system than SPS[15].
Moreover, variety of resonant kind DAB device topologies, consisting of series resonant networks, are planned. These topologies exhibit associate degree extended soft-switching vary and lower eddy current losses within the electrical device windings[22-25], thanks to improved current waveforms. However, in spite of the management and resonant schemes utilized, all existing DAB device topologies inherently draw an oversized reactive current element at full power and, therefore, incur large conductivity losses[13].
Fig. 1. New Bidirectional DC-DC converter This paper, therefore, proposes a unique DAB topology, that utilizes a resonant network to reduce the reactive power demand of the device over the complete load vary. The pro-posed device employs a tuned inductor–
capacitor–inductor (LCL) network, which has the escape inductance of the isolation electrical device, to considerably cut back the magnitude of bridge currents and, therefore, the switch and copper losses. an easy control theme is used, wherever every bridge is driven with equal PWM whereas maintaining the part shift between the bridges fastened at 90◦ or −90◦, to manage the direction and magnitude of power flow. Theoretical analyses moreover as simulated results ar bestowed compared with experimental proof of a two.5-kW paradigm system, demonstrating the power of the planned topology to transfer bidirectional power at a high potency over a good vary of power and dc offer voltages. The applicable criteria that follow.
II. PRAPAOSED METHOD
A schematic of the planned resonant DAB convertor is shown in Fig. 1, during which S1 − S8 represent semiconductor switches. For simplicity, the active load on the secondary aspect is drawn by a voltage supply, VD C 2 . In apply, this volt-age supply, that is connected to the output of the secondary convertor, is battery pack used for storing or retrieving energy. moreover, during a sensible system, L2 is also incorporated with the discharge inductance of the electrical device instead of using a distinct inductance. the first aspect full-bridge
convertor, Bridge 1, of the planned resonant DAB, is operated at a hard and fast frequency, fs , and converts dc provide voltage social disease C one to a three-level pulse-width-modulated ac voltage supply v1 . Similarly, Bridge two is operated at an equivalent frequency because the primary and converts its dc provide voltage Vdc2 to a pulse width modulated ac voltage supply Vb2 . These 2 ac voltage sources square measure connected along through AN isolation electrical device And an L1 C1 L2 network, that is tuned to fs .
Traditional resonant DAB converters use quasi-resonant networks, comprising inductors and capacitors to reduce switch losses by up the soft-switching vary. These converters exhibit multiple operational or resonant modes inside a switch cycle,
DC INPUT CONVERTER
CIRCUIT
RESONANT LCL FILTER
TRANSFORM ER n:n RATIO
CONVERTE R CIRCUIT
DC OUTPUT
(battery storage)
fig. 2 Block diagram of Forward Mode
DC OUTPUT CONVERTER
CIRCUIT
RESONANT LCL FILTER
TRANSFORM ER n:n RATIO
CONVERTE R CIRCUIT
DC INPUT (battery source)
fig. 3 Block Diagram of Reverse mode
and usually complicated modulation schemes square measure used to manage the switches so as to realize soft-switching. However, as a results of the tuned (resonant) L1 C1 L2 network used, the planned system doesn't exhibit multiple operational modes as each the resonant and switch frequencies square measure identical and might be controlled employing a easy PWM theme. Within the planned system, the direction and magnitude of power flow is regulated by dominant the heartbeat breadth of voltages v1 and VB2 , whereas keeping the section shift between them constant. This is often achieved by operational switches S1 and S2 of Bridge one in anti-phase at the switch frequency fs with a requirement cycle of fifty to come up with voltage Vs2 , as indicated in Fig. 2. Switches S3 and S4 square measure operated within the same means, except that vS4 lags Vs2 by a displacement of α1 degrees. The ensuing voltage v1 , driving the network, is adequate to the distinction between Vs2 and vS4 .
Fig.4. New Dual Active Bridge Topology
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Thus, α1 modulates the heartbeat breadth (i.e., duty cycle) of the ac voltage v1 within the vary of 0–50% as α1 changes from 0◦ to 180◦. Bridge two is controlled during a similar means, employing a section displacement of α2 ,to supply a pulse-width-modulated ac voltage Vb2 that is offset from v1 by a section shift φ.
The tuned (resonant) L1 C1 L2 network presents a high impedance to harmonics generated by the converters, and so, the currents i1 and ib2 square measure close to curving. Underneath tuned conditions, the magnitudes of the bridge currents i1 and ib2 measure proportional to Vb2 and v1, severally. Additionally, i1 are leading Vb2 by 90◦, whereas Ib2 are insulation v1 by 90◦, therefore inflicting the bridge currents to align with the voltages once φ is ±90◦. As such, the facility flow of the planned resonant DAB is regulated by dominant α1 and α2, where as maintaining φ mounted at ±90◦ to reduce the VA rating of the bridges.
III. RESULTS
A model 2.5-kW resonant DAB was designed and tested and therefore the results obtained from this model square measure given together with theoretical results to verify the viability of the planned system and therefore the accuracy of the mathematical model derived. The time-domain theoretical waveforms of the system operative below steady-state conditions were obtained employing a MATLAB perform to gauge by summing the forced responses of the primary hundred frequency parts in an exceedingly Fourier decomposition of v1 and v2 . the planning parameters of the epitome system, that has an potency of ninety six at rated load, square measure given in Table I. The bridges were controlled by an open-loop controller, exploitation equal modulation values of set φ of +90◦ or −90◦. To demonstrate the flexibility of the planned DAB to transfer power within the forward direction at close to unity power issue, Bridge a pair of was controlled to come up with a voltage Vb a pair of that's insulation 90◦
with regard to v1 , and therefore the results square measure. each bridges were operated with modulations of 165◦ and, as expected by, below these conditions, roughly a pair of.5 kilowatt was delivered to Vdc2 from Vdc1 . The bridge currents were roughly curving and in section with their individual V ages, so indicating close to zero reactive power transfer between the bridges and therefore the LCL resonant network.
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 350
360 370 380 390 400
time
Voltage(Volts)
Input Voltage
fig 5. Input voltage of forward mode
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
10 20 30 40 50 60
time
Volatge(Volts)
Output voltage
fig 6. output voltage of forward mode
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 -0.01
0 0.01 0.02 0.03 0.04
time
Current(Amps.)
Leakage current
fig 7. Leakage current in forward mode using PID controller
When reverse direction is required then or say that if the using the resonant phenomena of the DC-DC converter topology then we should provide if the 50 volts as a input in the load side then figure show that the boost process is getting proceed and the developed simulation result is
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
10 20 30 40 50 60
time
Voltage(Volts)
Input Voltage(Reverse Mode)
fig 8 . Input voltage in reverse mode using PID controller
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
50 100 150 200 250 300 350 400
time
Voltage(Volts)
Output Voltage(Reverse Mode)
fig 9. output voltage in reverse mode using PID controller
And the develop leakage current in these input voltage when we provides to converter circuit is like a around 3 amps.. so that these leakage current is generates the conduction losses and any other losses in the circuit
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 -10
-8 -6 -4 -2 0 2 4 6 8 10
time
current(amp.)
leakage current(reverse mode)
fig 10 . Leakage current in reverse mode using PID controller
When we using neural network as a controller circuit and defined the situation as same like a PID controller, in these case same two cases are there for forward mode and the reverse mode situation, s first for the forward mode, the below figures indiacated the simulated output of the system when we are using the neural network
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 350
360 370 380 390 400
time
Voltage(volts)
Input Voltage
fig 11. Input voltage in forward mode using neural network
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
10 20 30 40 50 60
time
Voltage(Volts)
Output Voltage
fig 12. Ouput voltage in forward mode using neural network
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
1 2 3 4 5 6x 10-4
time
current(amps.)
Leakage cuurent
fig 13.Leakage current in forward mode using neural network
0 200 400 600 800 1000 1200
-60 -40 -20 0 20 40 60
time
Voltage(Volts)
Total harmonics distortion
fig 15.THD Generation in forward mode using neural network
When the reverse mode is operated then the level of output voltage and the lekage current is changed in these case so that we applied same situation for the neural network as compare to the neural network topology
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
10 20 30 40 50 60
time
Voltage(Volts)
input voltage(reverse mode)
fig 15. Input voltage in reverse mode using neural network
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
50 100 150 200 250 300 350 400
time
voltage(volts)
output voltage(reverse mode)
fig 16. Output voltage in reverse mode using neural network
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0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 -0.01
-0.008 -0.006 -0.004 -0.002 0 0.002 0.004 0.006 0.008 0.01
time
current(amps.)
Leakage current(reverse mode)
fig 17. Leakage current in reverse mode using neural network
Fig. nine shows the waveforms obtained through the theoretical analysis and therefore the epitome system once the DAB is transferring a pair of kilowatt within the reverse direction. As evident from the results, each bridges were operated at a modulation of 120◦, with VB a pair of leading v1 by 90◦ thereby transferring seventieth of rated power from Vdc2 to Vdc1 in accordance. Since the bridges square measure operated at a modulation of 120◦, the present waveforms exhibit considerably lower harmonic content as compared with the currents in Fig. 8, as expected. additionally, the bridge cur rents square measure in ant phase with regard to the corresponding bridge voltages, needless to say for reverse power transfer.
TABLEI:CIRCUITPARAMETEROFSYSTEM Parameter Theoretical
value
Experimental value Rated power 2.5 kW
VDC1 380 V
VDC2 50 V
Turns ratio n 7.54
Magnetics Ferro cube E65/32/27
fs 50KHz
L1 145 µH 144 µH
L2 145 µH 146 µH
C1 69.8 nF 66 nF
HV Switches FDP054N10 MOSFET
LV SIDE FDP054N10 MOSFET
comparison of the theoretical and experimental losses within the 2 bridges of the resonant DAB convertor at varied power levels, for forward and reverse operation.
The theoretical shift and physical phenomenon losses within the switches were calculative exploitation datasheet specifications of the devices. The IGBT losses were assumed, for a given temperature, to be proportional to the scale of the switched current, and therefore the MOSFET losses were calculated in line with [24]. a small discrepancy between the measured losses and theoretical losses may be ob-served.
However, agreement exists within the trends, together with the dip within the losses for power levels on top of
2 kilowatt such as modulation levels on top of 165◦, at that there's a decrease within the shift losses. As evident, the quantity of legs having ZVS goes from a pair of to four, because the modulation will increase on top of 165◦, and thus, the losses square measure expected to be lower once α1 and α2 are bigger than 165◦. The theoretical calculations more show that at full power, the physical phenomenon losses square measure roughly 80th of the entire losses .though this proportion can, in general, rely upon the actual devices used, it justifies efforts to scale back conductivity losses and emphasizes the advantage of the planned resonant DAB convertor.
The experimental and theoretical potency values, every of which has the facility losses within the magnetic parts similarly as those from the shift devices, square measure shown in Fig. 19. Though the model DAB given during this paper has not been optimized for potency, because it was strictly developed as a signal of construct system, the results recommend a big improvement within the performance as compared to standard DAB converters with SPS management. Additionally, even higher efficiencies square measure possible to be obtained if the Bridge a pair of voltage is raised, avoiding the comparatively massive conductivity losses within the secondary a part of the circuit. As evident from Fig. 18, each the theoretical and experimental efficiencies are in smart agreement. As such, the mathematical analysis given may be accustomed accurately characterize the losses in an exceedingly resonant DAB below varied operative conditions and accounting for variations in element values.
IV. COMPARATIVE ANALYSIS
So in below the comparative analysis is provided, which may clearly indicated that the level of output voltage and the leakage current of the circuit is what, when we using different kind of controller to the circuit for controlling the pulses of the switches, below two figure indicates that the level of the deviation of the values when we are used a different kind of controller.
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
x 105 0
50 100 150 200 250 300 350 400
time
output voltages(volts)
Output Voltage(Reverse mode) Neural Network Output Voltage(Reverse Mode) PID Controller
fig 18. Output voltage comparison using different controller
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 x 105 -0.01
-0.005 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
time
laekage current(amps.)
leakage current(forward mode) PID Controller leakage current(forward mode)Neural Network
fig 19. Leakage current comparison using different controller
V. CONCLUSION
A new twin DAB topology that employs an LCL resonant network has been represented. A mathematical model has been given to accurately predict the performance of the projected topology. Experimental results of a 2.5-kW model DAB, operated under numerous conditions, have additionally-been given to demonstrate the improved performance of the convertor.
Results indicate that the projected DAB topology has lower bridge currents when we are using the different kind of controller for controlling the pulses of the devices, so that the value of leakage current is decreases and the output voltage is getting increased we used different controller and, consequently, offers higher potency over a wider offer voltage and load point comparison to standard DAB topologies
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