The charging infrastructure in developing countries is at developing stage. To endorse EV’s development, fastcharging stations installation is required in which batteries of EV’s can be charged. Although, Fast charging has some shortcomings of highpower demand and it has some adverse effect on public grid. Renewable sources can be used as power source at high power fast charging stations to counter these issues
During past years, several researchers have reported papers of EV charging with public utility (grid) electrical supply
This paper proposes a microgrid for charging the electrical twowheeler powered LiIon battery, with REbased DG energy sources rather than gridconnected charging station. This proposed arrangement helps to create an efficient, lowcost, locally resilient microgrid. This will reduce the dependency on the electric grid during peak load time which is an imminent concern mainly in cosmopolitan cities and this makes the novel contribution of this paper. It works during any faulty period, contingency condition, or grid failure. It will support the vehicle rental agency to enhance the reliability and provide continuous facility to the enduser of vehicles. The charging of an array of twowheelers will be possible in the parking area with charging docks which will reduce greenhouse gas emissions and saves fuel costs. The used bike specification is commercially available named as ATUM 1.0 with 100 km range and 1 unit of energy is needed for charging, which costs around 710 INR
In this study, the projected arrangement is mainly based on a DC microgrid consisting of 6 kW FCs and solar PV of 6 kW with the public grid as power sources. All these power sources are converted to DC using converters and centrally linked to charging station with breakers B1 and B2 which facilitates battery charging for EV's as shown in
During Grid Connected Mode of operation, the breaker B1 is closed and B2 is isolating the renewable power sources. The charging of vehicles will be through the public grid. However, this mode is considered for emergency periods. Hybrid Mode of operation integrates public grid and renewable sources connected to the grid to charge EVs. During the charging, the DG provides generated surplus extra power to the utility grid also.
Breaker 
Grid Associated Mode 
Hybrid Mode 
Autonomous Mode 
B1 
ON 
ON 
OFF 
B2 
OFF 
ON 
ON 
Autonomous mode can be used when public grid failure/fault happens and grid breaker B1 opens. The power to charging station is fed independently from DC microgrid and power outages can be reduced. It is helpful to loads when the grid is unavailable during contingency periods.
Mathematical modeling of the proposed system with its input and output components is determined for microgrid architecture. A PV array, FC, and public grid is available with PEC in microgrid. Modeling helps to obtain operational characteristics of connected components for the easy integration of the components and energy flow analysis
The solar PV array is considered the most essential and prerequisite sustainable resource due to its free and abundant availability in the atmosphere. The solar power in the model mainly depends upon irradiance and ambient temperature. Solar cell radiation is measured by air mass, incident angle, and radiation to measure cell power (S) given in equation 1 below:
Output power of solar PV is dependent on temperature and irradiance as equation 2.
Temperature affects the output power of the cell and as temperature goes down the current increases and voltage collapse at a higher rate than current increases. Thus, overall efficiency goes down. This phenomenon can be understood by the formula given in equation 3.
Equation 5 gives the output power of PV cell in kWh:
The DC/DC converter for power extraction to match the DC bus voltage of the microgrid employed, that gives inputoutput relation as in equation 6.
It is an electromechanical conversion device, in which electrical energy is produced from chemical energy with water and heat as byproducts using H_{2} energy. In existing research, PEMFC is used due to its lowtemperature operation suitability and quick response. FC output voltage (V_{FC}) is given by oxidized fuel and electricity is generated as given in equation 7 & power (P_{FC}) is given by equation 8 as:
The electrical FC efficiency is given by equation 10.
Nearly, a FC can yield 0.6–0.75 V and the power and voltage level can fluctuate from 2 kW to 50 MW and a couple of volts to 10 kV
The DC/DC boost converter is needed to boost the generated DC voltage for the conjunction of the required microgrid voltage level. The parameters needed for the computation of power stages are given in equations.
The switching current is derived by the duty ratio of the switch, the switching current and inductor value respectively are given below.
The input capacitor value mainly depends upon output voltage & current which is employed to attain the essential ripple output voltage which is given below.
The electric bike mainly consists of a battery for the power supply source during the running time which leads researchers to develop a battery model for proper mathematical calculations and predictions. The main concern of EV's is their charging behavior with required battery chemistry. The reason to select LiIon batteries is that these have a higher coulombic efficiency value than other available batteries. The SOC of battery is characterized as the charging remaining capacity to full charged capacity as in equation 14:
The SOC formula is given by equations 15 & 16.
The currentbased SOC is denoted by coulomb counted method as in equation 17.
The systematic correction factor (
The final equation of SOC can be presented using equation 19.
Here, w is an additional weighing factor. A LiIon battery consists of series resistance, capacitance for ohmic resistance drop, and storage capacitance respectively. The terminal voltage, given by equation 20.
The SOC of the battery can also be calculated at any time as equation 21.
The battery pack with the terminal output voltage of 48V is directly coupled to the motor drive. The SOC of the battery is presumed to range between 30% to 100%, with an initial SOC of 80%.
The proposed microgrid for rental bike charging with a 27 Ah battery is designed in Simulink, which is powered by solar PV, FC, and grid. The simulation model is shown in
Solar PV block from Simulink library is used for model development with 25°C temperature and 1000 W/m^{2} irradiance for simulation. The PV array used with 10 parallel strings with 2 series associated cells to each string constituting 6 kW. A PEMFC FC of 6 kW is directly connected to a DC link with a DCDC boost converter. The model using H_{2} as the fuel and O_{2} as an oxidant with a cell efficiency of 55%.
Boost converter is employed in the microgrid to step up DC voltage for required grid voltage level with solar PV and FC stack. The P&O MPPT controller is employed to obtain maximum power. The converter has an inductor of 5 mH, the input capacitance of 0.5 µF and 12 mH respectively. A standard threephase grid with 220 V and 23000 MVA at 50 Hz is utilized for model realization. The connection of the grid is supported with threephase AC to DC voltage source converter. The VSC controller works as a regulator in the circuit with feedback of grid current and voltage.
The battery of newly launched electric twowheelers ATUM 1.0 is considered to be the load that is less costly and suitable for the Indian market and customers. The battery employed is LiIon, commonly used in various applications. Specifications of the battery are given in
S. No. 
Parameter 
Value 
1 
Nominal Voltage 
48 V 
2 
Battery Capacity 
27 Ah 
3 
Battery Energy 
1300wh 
4 
Optimal Charging Time 
34 hours 
5 
Battery Life Cycle 
1000 Cycles 
6 
Initial Battery SOC 
40% 
MATLAB was used for validation of DC microgrid model for charging of plugin electric twowheeler. The charging station was taken as a standalone microgrid with three modes of operation; grid associated, hybrid and autonomous mode. The grid is directly connected to the twowheeler charging point which is a blockset of 27 Ah battery. The model was run for a threesecond operation (1 second for grid associated mode, next 1 second for hybrid mode, and last 1 second for autonomous mode) and SOC variation is evaluated by reducing the battery response time. The model was run on accelerator mode with just a time algorithm. The charging profile of the used battery block system is shown in
During Grid Associated Mode of operation, only the public grid is connected while the DG source is isolated.
The battery charging rate is around 0.1808% per second with an injection of DC sources FC and solar PV which can be noted from figure 3(a) during hybrid mode. Hence, the ripple in voltage profile is less than compared to grid associated mode and the range of output voltage ranges between 46.927 to 54.712 V.
Islanded Mode works when the grid is not available due to fault or abnormality i.e. solar PV & FCs are being employed. The battery charging rate is around 0.0312% per second. The voltage ripple is also very less because only DG sources are working and the major AC source (public grid) is disconnected. The output ripple voltage range is around 47.106 to 48.293 V. Simulink model, efficiency & reliability of charging station is also improved during the offgrid period.
Electric vehicles are more popular due to less running costs and they doesn’t emit environmental polluting agents. Electric twowheelers have been more pocketfriendly as they can run for a 100 km distance with only 1 kWh of electric energy consumption. Market of electrical vehicles is growing rapidly but the lack of charging stations affects it negatively. This paper is devoted to design a charging station powered by a public grid as well as FC & solar PVbased RE sources. The study presents mathematical modeling of individual components along with a complete integrated arrangement. The proposed work is simulated and implemented in MATLAB and its feasibility is tested with RE sources. The islanded mode of operation also reduces the power burden on the public grid and it can also be used during grid failure or unavailability. The implemented model has an ideal electric twowheeler LiIon battery with its parameters to charge it. The proposed model has the feasibility of charging methodology by integrating the renewable sources into the system. This manuscript haven’t considered any method for cost analysis, vehicle dynamics, and battery management system.
The future scope of this work can also be extended for reducing the ripple in output voltage by using filters or other arrangements. The optimization methods can also be implemented for power flow, cost analysis and economic analysis can also be performed for the charging station.
We express our gratitude and thankfulness to all those who contributed and aided to this work, the Department of Electrical Engineering (Rajasthan Technical University, Kota in India) and the Power System Modeling and Simulation Laboratory of MATLAB.
List of Symbols 
Column1 
Vo 
Voltage output 

Cell Power 
Vi 
Input voltage 
w/m2 
Electric Solar Power Output 
Io 
Output Current 
G 
Solar Radiation 
fs 
Switching Frequency 

Beam 

Efficiency of converter 
D 
Diffuse 
Q 
Currently stored charge 
Ρg 
Ground 
Qmax 
Maximum charge in battery 
M 
Air Mass Modifier 
Qmin 
Minimum charge in battery 
Β 
Angstrom Turbidity Constant 
SOC0 
Initial SOC 
Rb 
Ratio of beam Radiation 
SOCv 
Voltage based SOC 
Τα 
Fraction absorbed by absorber plate 
a0 
Terminal voltage at 0% SOC 
Tmod 
Temperature of Module 
a1 
Terminal voltage at 100% SOC 
Tair 
Temperature of Air 
Cp 
Battery capacity in Ah 
KT 
Clearness Index of Location 
Η 
Systematic correction factor 
Vmax 
Maximum voltage 
R0 
Ohmic resistance drop 
Imax 
Maximum current 
Cs 
Storage capacitance 
Pin 
Input Power 
Rd 
Diffusion resistance drop 
kWh 
Power of Cell 
Cd 
Diffusion capacitance 
Vpv 
PV Array Voltage 
Vt 
Terminal voltage 
Vdc 
DC Bus Voltage 
Vo 
Output voltage 
IL 
Ripple current 


D 
Duty Ratio 
Abbreviations 

VFC 
Fuel Cell Output Voltage 
INR 
Indian rupees 
mH 
Mili henry 
VSC 
Voltage source converter 
E 
Internal voltage of fuel cell 
DG 
Distributed generation 

Activation voltage 
PE 
Power electronics 
Vcon 
Concentration Voltage 
DC 
Direct current 
PFC 
Fuel Cell Output power 
PV 
Photovoltaic 

number of cells 
PEMFC 
Proton exchange membrane fuel cell 
IFC 
Fuel cell current 
LiIon 
Lithiumion 
MH2 (kg/s) 
mass flow rate 
EV 
Electric vehicle 
HHVH2 
higher heating value of the hydrogen 
SC 
supercapacitor 
Ah 
Amperehour 
CAGR 
Compound annual growth rate 
fs 
Switching Frequency 
AC 
Alternating current 

Efficiency of converter 
PEC 
Power electronics converter 
Vi 
Input voltage 
SOC 
State of charge 
Io 
Output Current 

