Battery Charger Design with PI Control Based on Arduino Uno R3

In line with the increase in the electrification ratio target to 100% in 2025, the electricity demand is projected to increase more than 7 times to 1,611 TWh in 2050. the share reached 58% or about 50 GW. On the other hand, the current energy diversification carried out by the government is directed at the utilization of renewable energy that exists in nature. One of the important components in this power plant is the battery. This is because the battery functions as a store of energy generated from the vertical wind turbine. After use, the battery needs to be recharged. The process of recharging the battery that is not suitable can cause a decrease in battery performance. Therefore, in the process of charging this battery, a safe battery charging system is needed for the battery to maintain battery performance and extend battery lifetime. This battery charging system uses a PI control system. From the research that has been done, it was found that. From the research that has been done, it is found that the output voltage value of the battery charger that is made has an average error percentage of 1.373% and the power output efficiency of the battery charger is 83-95%.


INTRODUCTION
In line with the increase in the electrification ratio target to 100% in 2025, the electricity demand is projected to increase more than 7 times to 1,611 TWh in 2050 [1]. Taking into account various factors, additional power generation capacity during the period 2015 s.d. 2019 is estimated at only 12 GW. Currently, power plants that have COD (Commercial Operation Date) only operate about 4% (± 1.5GW). Under these conditions, the implementation of the 35 GW program is estimated to be achieved in 2025 -2026 [2]. In 2025 coal-fired power plants are estimated to continue to dominate with a share of 58% or around 50 GW [3]. According to BPPT in 2018, coal reserves will run out within 68 years. One of the largest electricity users in Indonesia is the household sector [4]. During January-July 2020, the largest electricity consumption from the household sector was 42.25% or reached 47.5 TWh.
One way that can be done is by utilizing renewable energy that is so abundantly available in nature [5]. On the other hand, the current energy diversification carried out by the government is directed at the utilization of renewable energy that exists in nature. As a solution to the high consumption of household electricity and to take advantage of the potential of wind and water as a manifestation of energy diversification, a portable power plant design was created [6]. One of the important components in this power plant is the battery. In another study conducted by Jamal in 2019, research was carried out on the angle of the vertical wind turbine blade placement which was carried out with 4 angle variations, namely 22.5°, 45°, -22.5°, and -45°. Where the purpose of this study is to find out how the position of the most efficient wind turbine blades. From the research conducted, it was found that the highest power coefficient that can be produced by wind turbines is in wind turbine research with a pitch angle of 45° Cp max 7.39% with a tsr of 0.422 [7]. Furthermore, one of the important components in this power plant is the battery. This is because the battery functions as a store of energy generated from a vertical wind turbine. After use, the battery needs to be recharged [8].
The process of recharging the battery that is not suitable can cause a decrease in battery performance. In a previous study conducted by Robiansyah in 2017, a study was conducted on charger controllers using a buck converter. The purpose of this research is to design a charge controller for small scale utilization. Where from the research conducted, it was found that the output voltage value of the charger controller was a maximum of 13.5 V with a maximum current output of 3 A. This is because the battery functions as a store of energy generated from the vertical wind turbine. After use, the battery needs to be recharged [9]. The process of recharging the battery that is not suitable can cause a decrease in battery performance [10]. Therefore, in the process of charging this battery, a safe battery charging system is needed for the battery to maintain battery performance and extend battery lifetime. This battery charging system uses a PI control system.

II. METHODS
After taking data and studying literature, then the turbine design and charge controller will be made, this activity is useful to provide an overview of the tool to be made. Where in the picture below is a block diagram of the charge controller system that will be made. The working system of this tool is that the mechanical energy from the wind turbine will be converted into electrical energy [11]. where the output of the generator will be measured by the voltage and current values by the voltage sensor and the input current sensor. Furthermore, the output from the generator goes to the input buck converter where after that the output from the buck converter will be measured again for the voltage and current values, then the voltage value from the output buck converter will be processed by the PI controller and the output from the PI controller is the PWM duty cycle which is used to regulate the output. from the buck converter [12]. After that the output of the buck converter passes through the relay and is used to charge the battery. where when the battery is full then the relay will be disconnected [13].
After that, proceed with making a wiring diagram of the charge controller system in this study where in the picture below is a wiring diagram of the system that will be made.  From the circuit that has been made, run simulation is carried out and the output voltage waveform of the buck converter is known as below. = [14] (1) = 0,99 Next is the determination of the value of the time constant (τ) = 5τ [15] (4) So that the open loop transfer function can be determined as follows [16]: = 0,99 13,378 S + 1 As for the Close Loop Transfer function (CLTF) as follows [18]: So: * = * = 13,378 5 = 2,6756 So that:  In this design there is a solar panel that is useful as a hybrid of a savonious turbine in order to increase the output power of the power plant.
After getting data on wind speed characteristics testing, the next step is to design a vertical wind turbine blade. The first design stage is done by calculating the total area of the turbine blades (the area of the tube blanket).
The average turbine Cpr value is 0.158 [21], so: From the calculations that have been made, it is found that the total number of turbine blades is 3 m 2 . After that proceed with determining the size of each blade [22]. In this study, a vertical axis wind turbine with 3 blades was used. = After obtaining the length and width of the blade, the next calculation will be on the length of the bowstring of the blade [24]. This is used to find out how big the curvature of the blade is. This calculation technique is done by using the formula for a triangle in a circle with an equilateral triangle shape.
After that, the length of the bowstring for each blade is determined. This is done to determine the curvature of the turbine blades that are designed. r = 4 [25] (28) Because a = b = c [26], so: The following is a detail of the size of the turbine that has been carried out in the design process:

III. RESULTS AND DISCUSSIONS
A. Turbine Testing on Hydro Energy This test was conducted to determine the power generated by the turbine to hydro energy. This test was conducted in Singopadu Village, Tulangan District, Sidoarjo. The test data can be seen in table below.   Based on the tests that have been carried out, it is known that the higher the speed of the water flow, the greater the power generated and vice versa. From the data obtained, each rotation, the turbine can produce a power of 55.2 W.

B. Turbine Testing on Wind Energy
This test aims to determine the amount of electrical power produced by wind energy with a power plant prototype. The test was carried out on July 14, 2020 at Kenjeran Beach with 4 variations of speed. The test result data can be seen in the following table.  Based on the test data obtained, the average output voltage is 17.25 volts. In this test, a good wind speed was taken for this savonious turbine, this is because previously the savonious turbine was designed for wind with a speed of 4 m/s. The faster the wind speed, the greater the power generated.

C.
Solar Panel Test This test is carried out with the aim of knowing the maximum power that can be produced by solar panels. The test was carried out at 9:00 to 15:00 WIB. The test is carried out using a 120 ohm load resistor and measured using a multimeter to determine the amount of voltage and current output from the solar panel. The data can be seen in the table below. From the tests that have been carried out, a graph can be made as below. From these data, it can be explained that testing solar panels for one day can produce a voltage of 18.12 to 18.95 volts.

D.
Open Loop and Close Loop Buck Converter Test System integration testing without control aims to determine the output voltage generated from the system when it has not yet received control. The test is carried out with the source of the power supply where the output voltage is 15-19 volts. The test was carried out on August 1, 2021. The data below is the data obtained from the open loop buck converter test. Next, a close loop test was conducted on the buck converter circuit during charging with the aim of finding out whether the system can maintain a constant voltage according to the design and comparing the system when it is without control and when it is given control. Below is a comparison of data on the results of the open loop and close loop tests of the buck converter circuit. 17 From the data from experiments conducted by varying the input voltage, it is known how the response of the given control is. From these data it proves that the use of PI control in the system is able to maintain the output voltage. The error comparison between the openloop and closeloop test results will be displayed in the graph shown in the image below.

E.
Hybrid System Test This test is carried out using three hybrid power plants using a chargec controller that has been made. The output of the charger controller will be hybridized and used to charge the battery. The data obtained are as follows. From the tests that have been carried out, a graph can be made as below.

Figure 13. Charger controller integration test chart
From the tests carried out, it was found that to charge the battery with an initial voltage of 12.3 V to 12.8 V it takes 31 minutes and the relay will turn off when the battery is full.

IV.
CONCLUSIONS AND RECOMMENDATIONS Some conclusions can be drawn from the previous discussion and suggestions regarding problems that can be discussed as a continuation of this research. The results of this study shown that from data collection characteristics of wind speed, data obtained wind speed of 3.66 m/s and air density of 1.2 kg/m3. It also shown that the power that can be generated by the hybrid power plant is 95.47-101.62 Watt. From the research that has been done, it is found that the output voltage value of the battery charger made has an average error percentage of 1.373% and the power output efficiency of the battery charger is 83-95%.
For the research's recommendation in this study that there is a need for research on the calculation of the type of ferrite material in the inductor and the magnitude of the switching frequency used in this charge controller in order to produce a more efficient output. Integration test V input V output