Electric vehicles (EVs) are emerging as a viable option to gasoline-powered automobiles. The functioning of these vehicles necessitates the “recharging” of their batteries. Although EV charging has usually been done via the grid, solar-powered chargers have emerged as a promising alternative. In addition to this, the biggest concern for experts was to charge EV when solar irradiance is decreased to zero. For this the proposed model used a battery bank as an alternative source of energy and is responsible for providing enough power to EV battery in absence of sunlight. This is done efficiently by using the solar PV panels, sepic dc-dc boost converter, MPPT charging controller, alternate battery bank.This paper proposes an electric vehicle battery charger using PV array with FOPID (fractional order PID) controller. The proposed model works in three modes, firstly when EV battery and battery bank is getting charged by the PV panels, secondly when EV battery is getting charged by the battery bank and third, when battery bank supply is cut off and EV battery is getting charged by solar panel only. Experiments were conducted on MATLAB platform and the simulated outcomes proved that the proposed model is effective in charging the batteries of EVs. A comparative performance analysis of the battery bank SOC and that of EV battery reflects that the proposed FOPID controlleris definitely more efficient and effective for charging the EV.
Over the last few years, the use of renewable power generation techniques has expanded drastically,
thus it is critical to develop a mechanism in order to ease the implementation of Renewable Energy
Resources (RER) so that the overall efficiency, safety and dependability of the grid is enhanced. As there
is a drastic increase in electricity demand all over the world which makes it crucial to use new sources of
power generation which include solar, wind fuel cells etc. [
In a typical solar power generation system, solar PV panels are installed serially or parallelly to
maximize power generation. The power generated by the solar panel directly depends on the intensity
of sunlight which means if intensity of sunlight is more, more power is generated and vice versa [
This paper proposes an electric vehicle battery charger using PV array with FOPID(fractional order PID)controller.Experiments were performed in MATLAB platform and a comparative performance analysis with the results obtained by using PI and PID controller is done to illustrate the effectiveness of the proposed method. It uses controller having two stages using a FOPID witha MPPT algorithm to extract maximum power from the PV system. The FOPID controller is used to vary the duty cycle of boost converter.
Fractional-order calculus is amathematical tool fordealing with derivatives and integrals from noninteger orders. In recent times lots of research have been done both by the academicians andindustrialists dealing with Fractional-order proportional-integral-derivative (FOPID) controllers. Fractional system provides a better understanding of system characteristic like system response, rejection of disturbance , better and improved capability of handling model uncertainties in nonlinear as well as real time applications.
The ‘s’ domain representation of PID controller is: C(s)= (Kp +sKd + (Ki/s)) E(s) (1) Where ‘C(s)’ represents the output of the system, ‘E(s)’is error and Kp,Kdand Kirepresent theproportional, derivate and integral parameters of the control system.
And the ‘s’ domain representation of FOPID controller is:
C(s)= (Kp +sμKd + (Ki/sλ)) E(s) (2)
Thus, in case of FOPID the power of ‘s’ is fraction compared to PID controller where it is integer. The aim thus is to optimize the value of the two additional parameters ‘μ’ and ‘λ’ in addition to the three Kp ,Kdand Ki parameters. Thus, they have additional flexibility in the controller design, compared to the standard PID controller, because they have five degrees-of-freedom (DOF), compared to three DOFs of its integer-order counterpart. Higher DOF provides better time and frequency responses of the control system.
The proposed model consists of solar PV panels, sepic dc-dc boost converter, MPPT charging with FOPID controller, alternate battery bank. The proposed model works in following three modes, Thesepic converter is used to regulate the voltage and current supply. The MPPT technique is thus used to obtain maximum power from solar panels by usingthe FOPID controller.
Mode 1: When the sunlight is at peak, the sunlight falls on the solar panel which converts it into the electrical energy that is capable of charging the battery bank as well as the battery of electric vehicle. Mode 2: In the next mode, when the input irradiance of sun is very low in such case, the supply of solar panel is cut off and the battery bank is used as a charging source for EV. The battery bank starts getting discharged slowly.
Mode 3: In the 3rd mode of operation, the irradiance is increased so that EV is charged by the solar panel but the battery bank is not charged in this case.
(i) Sepicconverter,
Figure1. shows the block diagram of the SEPIC dc-dc boost converter. The main job of FOPID controller is to pass duty ratio cycle(D1) to the sepic converter in order to pass a consistent output voltage to the EV regardless of the input PV voltage.
Another major advantage of using the Sepic converter is that it can operate in boost and buck modes depending on the duty ratio cycle. C2 = (6)
∆ Where represents the minimum voltage generated by PV panels, ΔiPVrepresents the input current ripple, fSWrepresent the switching frequency, Idcrepresents the dc link current, ΔVC1represents the voltage ripple of capacitor C1, ΔVdc represents the output voltage ripple, and Dmax represents the maximum duty ratio which can be calculated by the equation 7.
Dmax = + (7)
+ + where VD represents the voltage drop in diode.
(ii) Bidirectional dc-dc converter Figure 2. below presents the circuit for bidirectional charging circuit.
The diagram of the proposed model is shown in Figure 3, along with its basic components which include PV panel, battery bank, EV battery, switches, MPPT algorithm etc.When the rays of sunlight fall on the solar PV panels, these are converted into the electrical energy in order to provide sufficient amount of voltage and current for charging the EV and battery bank.
To maximize the poweroutput from the solar PV panels, the proposed model utilized the FOPID MPPT controller.
The FOPID controller block diagram is as shown in figure 4.
The process opted by the proposed FOPID system to charge electric vehicles by using solar PV panels are
explained briefly here;
1. Initially, when the sunlight falls on the PV panels that are converted to the electrical energy in order
to charge the batteries of EVs. As the proposed model is working in three modes, the first mode is
when battery bank and EV battery are getting charged by the solar PV panel. A number of
parameters are defined such as input solar irradiance, temperature, open circuit voltage etc. Other
than this there are some other important parameters which are given in table1.
2. Once the voltage is generated, DC-DC converter requires a duty cycle to perform effective
operations. For this a MPPT technique is designed which would assist the converter to produce duty
cycle, whichin this case is generated using the FOPID converter (taking λ= 0.0675 and μ= 0.5).
3. In the second mode, the battery of EV is getting charged by the battery bank and solar PV supply is
switched off. The different parameters of the battery bank are defined which are shown in table 2
along with their values[
Table2.Table 3.
Battery bank parameters EV battery parameters The third mode of the proposed system is when alternate charging source i.e., battery bank is turned off and battery of EV is getting charged by the solar PV panels. Table 3. below represents the different EV parameters along with their configurational values.
4. The waveforms of the energy produced by the solar PV panels for voltage, current and total power in three modes of operation are evaluated and are shown in figure5 (a) and (b)and Fig. 6respectively. Furthermore, in order to track the MPPT in the system duty ratio is passed to the sepic dc-dc boost converter by the FOPID controller. The regulated voltage and current generated by the sepic dc-dc boost converter is as shown in figure 7.
600 500 400 )s taW300 r( oew P200 100
0 0 0.2 0.4 0.6 0.8 Time(s1ec) 1.2 1.4 1.6 1.8 2
The performance of the proposed FOPID model is analyzed and compared with the conventional PI and PID models in terms of the voltage generated by solar PV panels.
The simulation outcomes are obtained in terms of the voltage and current generated. In case of the proposed FOPID model, the voltage and current doesn’t fluctuate much and can effectively charge EVs and battery bank of EVs. Similarly, the performance of the proposed FOPID model is compared with the conventional PI and PID models in terms of the voltage and current generated by the sepic dc-dc converter. The voltage generated by the sepic dc-dc converter remains constant in all three operating modes which ultimately provides sufficient amount of current to the EV for charging. Lastly, the charging state of the battery bank and EV battery is determined in which the proposed model outperforms the classical PI and PID models. All these factors, make the proposed FOPID model more efficient and effective for charging the EV.
FOPID has more number of parameters to be tuned, thus providing better and finer tuning than PID controllers to meet the system target. In spite of the technical advantages offered by FOPID over its integer-order counterparts the adoption of the fractional order controller in the industry is slow. The cost of producing such controllers, the cost-benefit to the end user and the complexity of implementation of FOPID controllers with respect to its extra tuning flexibility verses the extent of performance improvement are certain factors which needs to be investigated to make it readily acceptable to the industry. [11] Z.Alqarni and J. Asumadu, (2019), "Battery Charging Application Thorough PVA and MPPT Controller with Voltage Regulation," 2019 IEEE 10th Annual Ubiquitous Computing, Electronics & Mobile Communication Conference (UEMCON), pp. 0523-0527. [12] S. S. Nadkarni, S. Angadi and A. B. Raju, "Simulation and Analysis of MPPT Algorithms for Solar PV based Charging Station, (2018)", “Electronics and Mechanical Systems (CTEMS)”, 2018 International Conference on Computational Techniques pp. 45-50. [13] Subramanian, K., & N, S. (2020). An Off-board Electric Vehicle Battery Charger using PV Array. IET Electrical Systems in Transportation. doi:10.1049/iet-est.2019.0035 [14] Fatemidokht, H., Rafsanjani, M. K., Gupta, B. B., & Hsu, C. (2021), “Efficient and Secure Routing Protocol Based on Artificial Intelligence Algorithms With UAV-Assisted for Vehicular Ad Hoc Networks in Intelligent Transportation Systems”, IEEE Transactions on Intelligent Transportation Systems, vol22, no.7, pp4757-4769