Claims:1. Charging EVs by PV and Grid reduces the overall cost of the parking lot. Model Predictive Control controls EVs using real-time and forecasted data for future time intervals.

2. Incorporated battery storage allows both grid-connected and off-grid operation.

3. The power flow scheme considers solar unreliability and EV charging needs. Solar PV is used to capture all EVs in the charging station.

4. This system uses Maximum Output Point Tracking (MPPT) with Perturb and Observe (P&O) to maximise solar power. If the energy rises, the voltage is changed until the intensity decreases.

5. It was discovered that the DC bus voltage varied while preserving the 48V DC bus voltage restrictions.

6. The suggested design shows the charging station running continuously throughout the day.
ELECTRICAL VEHICLE CHARGING STATION WITH
POWER MANAGEMENT
FIELD OF INVENTION:
This invention relates to the Design and Power Management of Solar Powered Electric Vehicle
Charging stations with an Energy Storage System. The method presents a predicted PV system
and EV pattern prediction based on acquired data. By lowering the overall cost of the parking
lot, a charging schedule for EVs through PV and Grid is provided. Model Predictive Control is
used for a current time slot and expected data in future time slots using accurate-time
knowledge about EVs.
BACKGROUND OF THE INVENTION:
Greenhouse gas emissions have caused many people to worry about climate change. This has
made finding new energy sources that don't have as much pollution is essential. It has helped
to spread the idea of electrifying transportation, which has led to the rise in the popularity of
Electric Vehicles (EVs). Furthermore, charging electric cars with electricity from traditional
sources doesn't help. Thus, there is a need for an efficient way to charge electric vehicles that
use renewable energy sources. It is suitable for the environment to use solar energy, but the
Photo-voltaic (PV) system isn't always reliable, and each electric vehicle has different needs
for charging. This complicates how solar energy can be used to assess cars. This solar-powered
charging station with a battery storage system is explained.
The best way to design and manage the power of an Electric Vehicle charging station powered
by solar PV and a battery energy storage system (BESS) with an AC grid is shown. For the
power flow strategy, things like the unreliability of solar and the dynamic charging needs of
electric vehicles are taken into account. PV stands for solar power, and it is used to charge all
of the electric cars in the charging station. Solar power doesn't work at night, so a battery stores
energy and charges the EVs connected to the station.
SUMMARY:
With the growth in the number of EVs on the road, charging EVs has become a significant
problem. A solar-powered charging station combined with a battery storage system and extra
grid assistance provides a viable option for meeting the charging needs of all EVs connected
throughout the day. THE NEEDED POWER IS OBTAINED using PID, current control, and
voltage control while holding the station's DC bus voltage constant. The proposed station's
architecture and power management are described and verified in MATLAB/Simulink by
examining five distinct modes of operation and two distinct scenarios of EV need, so ensuring
the design and algorithm are robust. This may be used in big power ratings and capacities to
serve as a charging station for EVs at the office or parking lot.
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig.1 illustrates the schematic Layout diagram of the proposed charging station.
Fig.2 illustrates the EV charging station model with controllers.
Fig. 3 depicts t h e Maximum power harvested from the PV array.
Fig. 4 depicts the Power from solar and total power required for EVs and power BESS
Fig. 5 depicts the electric Vehicle charging for case 1 and case 2.
Fig.6 depicts t h e Current drawn from BESS by EVs for case 1 and case 2.
Fig.7 depicts DC bus voltage.
Fig.8 depicts Power management showing all modes of operation.
BRIEF DESCRIPTION OF THE INVENTION:
Growing worry about climate change due to greenhouse gas emissions has heightened the
demand for other energy sources with the least pollution. It has contributed to electrification in
transportation, leading to the popularity of Electric Vehicles(EVs) (EVs). But with the
deployment of more EVs on the road, charging the car will be arduous if electric grid power is
utilised. When a more significant number of EVs are linked to the grid, it will inevitably
influence its function and control. Moreover, charging the EVs via the electric grid supplied by
traditional energy sources delivers no advantages. Thus, there is a need for an effective
charging system for EVs employing renewable energy sources. Solar energy is green and
sustainable, but the undependable collected power from the Photo-voltaic (PV) system and
dynamic charging demands of individual EVs introduce additional difficulties to the effective
charging of cars from solar sources. Different charging strategies and power management for
EV charging stations are reviewed depending on the various energy sources and EV demand.
It is described how to set up a solar-powered charging station with a battery storage system.
The technique incorporates a predicted photovoltaic system and an EV pattern prediction based
on acquired data. Provides charging schedule for EVs through solar and grid by lowering the
overall cost of the parking lot. Model Predictive Control is used to forecast future time slots
using real-time information about EVs. Discusses the need to prioritise EV charging from the
limited available solar energy. The feasibility of various PV and BESS charging forms for
commercial, residential, and business purposes was discussed in. depicts a solar-powered ebike
charging station capable of charging e-bikes by AC, DC, or contactless charging. The
charging station has a battery storage system that enables grid-connected and off-grid
operation. The study [7] illustrates a concept of a grid-connected quick electric car charging
station that provides high-quality electricity with low harmonics. The control of each vehicle's
charging is centralised, whereas the transmission of electricity from the AC grid to the DC bus
is decentralised. Thus, for a well-established EV charging station, the notion of using both
renewable energy and an energy storage system with extra grid assistance becomes more
important in the present context.
The proposed work explains an optimal design and power management approach of an Electric
Vehicle charging station powered by solar PV and a Battery Energy Storage System (BESS)
with an AC grid. The unreliability of solar and dynamic charging requirements of EVs are
considered for the power flow strategy. Solar PV acts as the primary source to charge all the
connected EVs in the charging place. Since the power from PV at night is not there, a battery
as an energy storage device is provided to charge the EVs connected to the charging station.
Whenever there is a deficiency in the power output of solar or BESS to charge the EVs, the
required amount of power will be taken from the AC grid, ensuring continuous operation of
the charging station throughout the day. The proposed system is formulated, designed and
validated using MATLAB/Simulink.
Fig. 1 gives the block diagram of the proposed EV charging station. As per Bharat EV
specifications, a 48V DC bus with a 3kW power outlet for each EV is considered for the
charging station. This paper adopts a charging station with five power outlets for charging 5
EVs to design the proposed work.
1. Electric Vehicle as load
A load of five electric vehicles, 48V, 28Ah with 0.5 hours to a maximum of 2 hours as
charging time [9], is studied for the charging station. Charging requirements of incoming
EVs varies time to time. The user can specify the State of Charge (SOC) limit, SOClt and
the time required h hours for charging the EVs. The power requirement for capturing all
the EVs are calculated in terms of their SOC according to [10]. The remaining SOC, SOCr
required to charge the vehicle is calculated from time to time with the difference between
SOClt and current SOC, SOCc.
2. Solar PV with Boost Converter
PV array of 250W at 37.3V as the open-circuit voltage is considered for the charging
station design in MATLAB/Simulink. To step up the PV array voltage, a boost converter
is used to get the required DC bus voltage as 48V. With a boost converter efficiency of
90%, the solar PV is designed for a load of 5 EVs to charge from 20% to 100% SOC for 2
hours. Thus, a total of 24 panels are required for the specified charging station.
3. BESS with Bidirectional DC-DC Converter
A battery energy storage system stores the excess power from the solar for charging the
EVs at night. A bi-directional DC-DC converter controls the charging and discharging
operation of the BESS. Considering charge-discharge efficiency and bi-directional
converter efficiency as 90%, for supplying maximum energy to the connected EVs for 2
hours, a 24V 350Ah BESS is used for the charging station. It is assumed that BESS
maintains/ discharges to a minimum of 20%SOC and charges to a maximum of 95% SOC.
4. Grid with Rectifier
For additional power requirements for the charging station, a 230V AC grid is considered.
In MATLAB/Simulink, a 230V AC source with a linear transformer is viewed as a grid to
shift the voltage to 48V AC. A controlled rectifier is provided to convert the AC voltage
to a constant 48V DC bus voltage.
Modes of Operations:
Mode 1
PP V > Ptot and SOCBESS < maxSOCBESS If the delivered power from the solar PV is more
than the required power of all the connected EVs, then the EVs will be charged to its SOClt
using the solar power only. If the current SOC of BESS is lower than its maximum SOC, then
the surplus power from the solar is used to charge the BESS by connecting it to the bus.
Mode 2:
PP V > Ptot and SOCBESS maxSOCBESS With the power from the solar, EVs are charged,
but if the SOC of BESS reaches its maximum, it is disconnected from the grid, and dummy
loads are tied for the power balance.
Mode 3:
PP V < PT ot
Due to rain or cloudy conditions, if the power harvested from the solar PV is lower than the
power required by the EVs for charging, then the deficient power will be taken from the AC
grid by connecting it to the DC bus.
Mode 4
PP V = 0 and SOCBESS > minSOCBESS
In night conditions, when there is no solar output, BESS provides energy for charging the EVS
in the station by maintaining the minimum SOC in the battery.
Mode 5
PP V = 0 and SOCBESS < minSOCBESS
When the current SOC of BESS is less than its minimum SOC, then the required power for
charging the vehicles will be taken from the AC grid by connecting it to the DC bus.
Two forms of control are required for the proposed work: power management and maintaining
a constant DC bus voltage. Fig. 2 depicts the charging station's model with the selected control
architecture.
MPPT and PID Control for Boost Converter:
For obtaining the maximum power from the solar, Maximum Power Point Tracking (MPPT)
using Perturb and Observe (P&O) method is adopted in this system. Using the P&O method,
the voltage is adjusted if the power increases until power no longer increases. The duty ratio
for the converter obtained by the P&O method is noted as D1. Here a PID controller makes the
DC bus voltage constant at 48V. DC bus voltage Vbus is measured and considered with the
desired voltage, and the obtained error is given to the PID controller. D2 gives the desired duty
ratio from the PID controller. The average of the two duty ratios, D1 and D2, is fed to the boost
converter for getting the maximum power from the solar by keeping the DC bus voltage
constant.
Current Control for Bi-directional Converter:
Whenever there is excess power in the solar, the battery storage system is to be charged, and
at night, this is to be discharged to supply power for the EVs. Here, the current control strategy
is adapted for the charging/discharging of the BESS. The converter’s duty ratio is in Buck
mode when the battery is charging. When in boost mode, BESS releases to supply power for
charging for all the EVs in the charging station. D boost is the duty ratio for boost mode of
operation in the bidirectional converter.
Voltage Control for Rectifier:
Using a PWM rectifier, the voltage at the DC bus is made constant at 48V by comparing it with
Vbus and reference voltage 48V.
≈
For the simulation study, 2 cases of EV requirements are investigated. In case 1, five EVs are
connected to charge from 20% to 95% SOC for 2 hours. Case 2 explains the requirement of 2
EVs to set from 50% SOC to 95% SOC, 1 EV to charge from 80% to 95% SOC and 2 EVs to
charge from 30% to 95% SOC is used.
Mode 1
A lookup table of irradiance and temperature for a day is given as the data to the PV panel
block in MATLAB/Simulink. Fig. 3 shows the extreme power obtained from the PV array by
MPPT for the corresponding data. A maximum of 4500W at peak time is obtained from 24
parallel-connected solar panels of the selected PV array. In this work, for considered 2 hours
of operation, solar output increases from 3050W to 4000W. In a simulation study, the power
needed for charging all the five EVs is obtained as 2688W to 980W for case 1 and 1780W to
600W case 2, respectively, as shown in Fig. 4 and Fig. 5. The battery of EV charging from
20%, 30%, 50% and 80% to 95% SOC is shown in Fig. 6 for case 1 and case 2, respectively.
The EVs are charged from their current SOC, SOCc, to 95% SOC in 2 hours. The current taken
from the bus for charging the EV at 40 minutes, for case 1, the SOC of EV is set from 20% to
70% with 6.5A at a power of 1500W, thus validating the equation (3). The total current required
for capturing all the EVs at an instant of 40 minutes is case 2. As in mode 1, the solar power is
more than the power needed for all EVs; BESS is connected to the DC bus for charging. BESS
can be charged till it reaches the maximum SOC using the excess energy.
Mode 2
In mode 2, BESS is disconnected, and dummy loads are connected to the system for
maintaining power balance. A simulation study obtained that PP V PT to + Pdummy. The
dummy loads are connected to the system to maintain a power balance in the charging station
design. In practice, this excess power from the solar can be utilised for any residential or
commercial purpose.
Mode 3
Since the PV power is more minor, the switch closes, and the AC grid is cascaded to the system.
Non-peak hours of solar output is taken for simulation purpose. Considering the rectifier
efficiency, the current drawn from both cases and the current taken from the grid varies from
25A to 10A in case 1 and nearly 5A in case 2.
Mode 4
BESS discharges from its maximum SOC 95% to nearly 89% drawing 55A and 35A for case
1 and case 2. The current drawn from the BESS for charging the EVs are shown in Fig.6. The
duty ratio is obtained to boost the operation of the bi-directional converter.
Mode 5
With BESS state of charge, 35% to discharging nearly 20%, the power in the storage system is
lower than the power needed to charge all the EVs. Grid is connected to the system, and joint
control is drawn.
The DC bus voltage was observed to range from 47.86V to 48.13V using the proposed
voltage management technique. Fig. 6 shows the DC bus voltage for 2 hours. In Fig. 7, the
suggested charging station is shown functioning continuously throughout the day. The
power management between solar, BESS, and grid with the EV is displayed in all modes of
operation by keeping the maximum power required constant at 2688W. Power from PV,
grid, dummy loads, and all EVs are shown with BESS state of charge. This validates the
infrastructure for increased EV demand and parking space.