View of Efficiency of BLDC Motor Regenerative Braking System on Electric Motorcycles

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e-ISSN(Online): 2460-8122 pp 72-81

Efficiency of BLDC Motor Regenerative Braking System on Electric Motorcycles

Fajar Kelana Buana¹, Erni Yudaningtyas², Mochammad Rusli³

1,2,3 Electrical Engineering, Universitas Brawijaya, Malang, Indonesia Email: fkelanabuana@student.ub.ac.id, erni@ub.ac.id, rusli@ub.ac.id Abstract— Electric vehicles, including electric

motorbikes, are increasingly receiving attention as a sustainable solution for transportation, especially in urban areas. One of the important features in electric vehicles is the regenerative braking system. The regenerative braking system allows the return of kinetic energy during the braking process to recharge the battery. This research aims to test the efficiency of regenerative braking for electric motorbikes with two different braking methods, namely switching and variable regenerative braking. The switching method is divided into three different levels of braking, namely 10%, 50% and 95% braking. With a focus on experimental data collection and analysis.

Based on tests that have been carried out using test scenarios, the efficiency values for regenerative braking resulting from two different methods are as follows. In the first test of 10% regenerative braking, the efficiency obtained was 10.76%, in the second test of 50%

regenerative braking, the efficiency obtained was 24.07%, and in the third, regenerative braking of 95%, the efficiency was 15.83%. Furthermore, the final test of regenerative braking using the variable method obtained an efficiency of 20.03%. From the data obtained, it can be concluded that an electric motorbike with specifications according to research and testing using a test scenario determined that the highest efficiency is 24.07%, namely regenerative braking of 50%.

Index Terms—About four key words or phrases in alphabetical order, separated by commas.

Abstrak–- Kendaraan listrik termasuk sepeda motor listrik, semakin mendapat perhatian sebagai solusi berkelanjutan untuk transportasi terutama di perkotaan. Salah satu fitur penting dalam kendaraan listrik adalah sistem pengereman regeneratif. Sistem pengereman regeneratif memungkinkan pengembalian energi kinetik selama proses pengereman untuk mengisi kembali energi baterai.

Penelelitian ini bertujuan untuk menguji efisiensi pengereman regeneratif sepeda motor listrik dengan dua metode pengereman berbeda, yaitu pengereman regeneratif metode switching dan variabel. Metode switching dibagi menjadi tiga tingkat besar pengereman yang berbeda, yaitu pengereman sebesar 10%, 50%, dan 95%. Dengan fokus pengumpulan dan analisis data secara eksperimental.

Berdasarkan pengujian yang telah dilaksanakan menggunakan skenario pengujian, nilai efisiensi pengereman regeneratif yang dihasilkan dari dua metode berbeda adalah sebagai berikut. Pada pengujian pertama pengereman regeneratif metode switching sebesar 10%

efisiensi yang didapatkan adalah 10,76%, pengujian kedua pengereman regeneratif sebesar 50% efisiensi yang didaptkan adalah 24,07%, dan yang ketiga yaitu pengereman regeneratif sebesar 95% efisiensinya adalah 15,83%. Selanjutnya, pengujian terakhir pengereman regeneratif menggunakan metode variabel mendapatkan efisiensi sebesar 20,03%. Dari data yang didapatkan, dapat

disimpulkan jika sepeda motor listrik dengan spesifikasi sesuai penelitian dan pengujian menggunakan skenario pengujian yang ditentukan efisiensi tertinggi adalah 24,07% yaitu pengereman regeneratif sebesar 50%.

Keywords— Electric vehicle, BLDC motor, regenerative brake.

I. INTRODUCTION

The use of motorbikes as a means of transportation has become commonplace and is the most widely used means of transportation in Indonesia. The choice of motorbikes as a means of transportation is not without reason, because motorbikes can be used to reach various goals in a short time. Apart from that, motorbikes are an affordable means of transportation. In fact, according to data published on the official website of the Badan Pusat Statistik (BPS), motorized vehicles, especially motorbikes, always increase every year. The increase in motorbikes that took place from 2018 to 2020 was 8,365,087 units [1]. The significant increase in the number of motorbikes every year will certainly have a negative impact, especially on the environment, namely increasing air pollution resulting from exhaust emissions from motorbikes passing on the road. Apart from that, the increasing number of motorbikes will also result in an increase in the need for fuel oil as the main energy source for conventional motorbikes. The increase in fuel demand will certainly affect the availability of fossil fuels, and these fuels will always experience price increases at any time. Therefore, more environmentally friendly means of transportation are needed to reduce air pollution and reduce the amount of fuel consumed, such as electric motorbikes.

The basic difference between electric motorbikes and conventional motorbikes is in the drivetrain and energy source used. On electric motorbikes, most of the drives used are Brushless Direct Current Motors (BLDC Motors). BLDC motors are widely used in types of electric vehicles, especially electric motorbikes because they have better efficiency in converting electrical energy into mechanical energy, and bldc motors can be optimal in controlling the speed of electric vehicles compared to DC motors [2]. In terms of energy sources, electric motorbikes use batteries as a place to store electrical energy. Differences in propulsion and energy sources on electric motorbikes can also affect the braking system.

On conventional motorbikes, the braking system occurs when the brake lever is pressed which makes the brake lining clamp the rotor, this functions to slow down the speed or even stop the motorbike [2]. This braking

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e-ISSN(Online): 2460-8122 system is certainly very inefficient if fully implemented

on an electric motorbike because the energy produced during the braking process will be wasted. Therefore, electric motorbikes use electric braking which is called a regenerative braking system.

The regenerative braking system is an electric braking system that can slow down the vehicle while absorbing some of the kinetic energy from the braking process and converting it into electrical energy to be stored in the battery [3]. Therefore, a regenerative braking system is one of the important features that can be added and applied to electric motorbikes. With a regenerative braking system, kinetic energy that is usually wasted during braking can be converted into electrical energy that can be stored in the vehicle battery. The application of regenerative braking on electric motorbikes is currently quite efficient. However, regenerative braking, which is currently widely applied to electric motorbikes, still has shortcomings in that when applied, the amount of regenerative braking is set at a certain number. Where the brake or gas lever is used as on/off switching, which functions to activate regenerative braking. This is of course still not comfortable and efficient, for example if we set the regenerative braking to 90% and at low speed, then the motorbike which is rotating slowly will suddenly reduce its speed very significantly or even stop immediately even though we don't want to stop. Another example, if we set regenerative braking at 10% and drive at high speed, when we want to stop, the fast-rotating motorbike will not be able to stop quickly and will require more help from other braking systems such as conventional braking to stop the speed of the electric vehicle completely. fast. This will certainly affect driving comfort and energy efficiency which will affect the distance traveled.

Based on the problems that have been described, this research proposes a regenerative variable braking system. The regenerative variable braking method is by making the brake lever an input value which can make the amount of braking flexible. So, the magnitude of the braking force and the intensity of the regen will be in accordance with the value of the input variable. In this research, testing was carried out experimentally. The proposed regenerative variable braking system is expected to increase the efficiency of electric motorbikes because the driver can determine the amount of braking force according to needs. The efficiency of electric vehicles can refer to several aspects such as the efficiency of the driving motor, energy consumption, battery capacity, and energy recovered, so in this study to be able to determine the overall efficiency of electric motorbikes is to calculate the ratio of the energy recovered to the energy consumed [4].

II. THEORETICAL FRAMEWORK

In research on the efficiency of regenerative braking systems, there are several theoretical bases related to the research, as follows.

A. Regenerative Braking

Regenerative braking is a braking system that is able to absorb kinetic energy and convert it into electrical energy which is stored in the battery when braking so that it can be used for other needs in the vehicle. In general, when an electric vehicle moves, the electrical energy in the battery is converted into mechanical energy in the load, namely the motor. However, when performing regenerative braking, energy flows from the wheels to the battery. This process is caused by the electromotive force (back-EMF) produced by the electric motor when it functions as a generator. Electromotive force (back EMF) arises in response to changes in magnetic flux produced by the magnetic field in the motor rotor. When the rotor rotates, the resulting magnetic field also changes, which then induces an electric current in the motor stator windings. This electric current flows through the cable and is returned to the battery for energy storage. In regenerative braking, the electric current flowing from the motor as a generator to the battery produces regenerative torque that opposes the movement of the wheels. This regenerative torque helps in the vehicle braking process, reducing wheel speed and removing kinetic energy that would previously be wasted in a conventional braking system. By using regenerative braking, kinetic energy that is usually wasted in conventional braking systems can be converted into electrical energy and stored back in the vehicle battery.

This reduces the need for conventional braking which uses friction and heat, and in turn increases the energy use efficiency of electric vehicles.

Fig. 1. Regenerative Braking Concept.

Regenerative braking systems are a fairly effective approach to extending the range of electric vehicles and can be used to save 8% to 25% of the total energy used by the vehicle, depending on the driving cycle and how the vehicle is driven [5]. Generally, regenerative braking torque cannot be made large enough to provide all of the vehicle's required braking torque. Additionally, regenerative braking systems should not be used in many conditions, such as high state of charge (SOC) or high battery temperatures. In this case, the conventional braking system works to cover the total braking torque required. Thus, the cooperation between the conventional braking system and the regenerative braking system is a key part of the design of the braking control strategy of electric vehicles and is known as torque mixing. This torque mixing strategy helps avoid driveline interference (transfer of power from the engine to the wheels).

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Because it is necessary to know the SOC of the battery, to find out the SOC of the battery you can use the SOC estimation method, which is a method that uses the battery discharge current as input and integrates the discharge current over a certain period of time to calculate the SOC status as shown in the following equation.

𝑆𝑂𝐶 = 𝑆𝑂𝐶₀− ¹

𝐶_𝑛∫ 𝐼 ∗ 𝑑𝑡_𝑡0^𝑡 (1) Where 𝐶_𝑛, corresponds to the nominal capacity of the battery, I corresponds to the current flowing in and out of the battery, and t is time. However, there is another calculation method that can be used to calculate the SOC of a battery, namely by multiplying it by a Coloumbic efficiency factor (µi) which is represented between discharge capacity and load capacity, the representation of the equation is as follows.

𝑆𝑂𝐶 = 𝑆𝑂𝐶₀−^µi

𝐶_𝑛∫ 𝐼 ∗ 𝑑𝑡_𝑡0^𝑡 (2) The battery charging charge can be expressed by the equation,

Charge = I * t (3) Where I is the charging current (Ampere), and t is the charging period (Hours). SOC is generally notated in percentage form using the following equation.

SOC (%) = ^(𝑅^𝑐(𝐴ℎ) + 𝐶ℎ𝑎𝑟𝑔𝑒(𝐴ℎ))

𝑇𝑜𝑡𝑎𝑙 𝐵𝑎𝑡𝑡𝑒𝑟𝑦 𝐶𝑎𝑝𝑎𝑐𝑖𝑡𝑦 (𝐴ℎ)× 100% (4) Where 𝑅_𝑐is the Remaining Capacity or remaining capacity (Ah), then add it to the charge or load (Ah) that fills the battery divided by the total capacity of the battery and multiplied by 100%, then you get the current battery percentage.

In regenerative braking, to be able to know and analyze the efficiency value of an electric vehicle, it is also necessary to know the kinetic energy of the vehicle and the amount of energy recovery that occurs during regenerative braking, especially including the amount of energy consumed and the amount of energy recovered during braking [6]. Because kinetic energy is a form of energy that arises as a result of the movement or speed of an object, and the amount of kinetic energy depends on its mass and speed, the amount of kinetic energy according to the law of conservation of energy can be expressed by the following equation.

𝐸_𝐾𝑖𝑛= ∑¹

2𝑚(𝑉₂²− 𝑉₁²) (5) Where m is the mass of the vehicle (Kg), 𝑉₂ is the initial speed of the vehicle when braking (m/s), 𝑉₁ is the final speed of the vehicle (m/s).

Meanwhile, to find out the amount of energy recovered (𝐸_𝑟𝑒𝑔) during regenerative braking, you can use the following equation,

𝐸_𝑟𝑒𝑔= ∫ 𝑉_𝑏𝐼_𝑏∗ 𝑑𝑡 (6) Where, 𝑉_𝑏 is the voltage on the motor controller during regenerative braking, 𝐼_𝑏 is the current on the motor controller during the braking process, and t is the time/duration of motor braking.

From formulas (5) and (6), the regenerative braking efficiency (η_b) of electric vehicles can be calculated using the equation.

𝜂_𝑏=^𝐸^𝑟𝑒𝑔

𝐸_𝐾𝑖𝑛= ^{∫ 𝑉}^𝑏^𝐼^𝑏^∗𝑑𝑡

∑¹𝑚(𝑉₂²−𝑉₁²)∗ 100% (7)

Because 𝐸_𝑟𝑒𝑔 is the same as the power that can be recovered and 𝐸_𝐾𝑖𝑛 is the same as the power used, the efficiency equation becomes.

𝜂_𝑏 = ^𝑊ℎ^𝑟𝑒𝑔

𝑊ℎ_{𝑈𝑠𝑒𝑑}∗ 100% (8)

B. Brushless Direct Current (BLDC)

A BLDC motor is a type of synchronous motor where the magnetic field produced by the stator and the magnetic field produced by the rotor rotate at the same frequency. In simple terms, a BLDC motor (Brushless DC Motor) is a type of electric motor that uses permanent magnets and direct current (DC) to produce rotation in the rotor. BLDC motors have a structure that is almost the same as ordinary DC motors, but do not use brushes and commutators. Instead, BLDC motors use electronics to control the current flowing to the stator. The source that can be used to drive a BLDC motor is a direct current (DC) source such as a battery or power supply which can produce DC voltage. Using a BLDC motor requires an electronic controller that can control the current flowing to the stator so that the motor can rotate properly.

The advantage of a BLDC motor is that it is more efficient and durable because it does not have rubbing parts (such as brushes and commutators in conventional DC motors), and is able to produce higher and more responsive rotation. Because of these advantages, BLDC motors are often used in applications that require high speed, good position accuracy, and high energy efficiency, such as in the automotive, robotics, and medical equipment industries. The very simple construction is a consideration for using BLDC motors in the development of the automation field. Apart from that, electric vehicles such as cars and electric motorbikes, which have become a trend recently, also use BLDC motors as propulsion because they have very high efficiency, reaching 95% [7]..

Fig. 2. Outrunner BDLC motor.

C. Bidirectional Converter

Technological advances in the field of power electronics have increased the efficiency of converter circuits. Currently the converter on an electric vehicle controller can work in two-way mode, it can become an inverter when driven (driven) and a reactifier (rectifier) when the electric vehicle is in regenerative braking mode based on input signals from the brake lever and controller. Most bidirectional converters use MOSFET switching because they have a high switching frequency and suit your needs.

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e-ISSN(Online): 2460-8122

Fig. 3. Equivalent circuit of BDLC motor as load.

The bidirectional converter shown in Figure 3 shows the converter circuit using a MOSFET as switching with loads R, L, and, R representing the resistance (Ohms), L the inductance (Web/A), and e the electromotive force (Volts) of the electric motor. Where 𝑖𝑎, 𝑖𝑏, 𝑎𝑛𝑑 𝑖𝑐

represent the phase current in the stator. For 𝑒_𝑎, 𝑒_𝑏, 𝑎𝑛𝑑 𝑒_𝑐 it is the reverse electromotive force per phase for phases a, b, and c. The switching sequence is generated by considering the output of the hall sensor for every 120° phase shift. Gate Pulse is generated by the controller by considering the current requirements of the load and the resulting work cycle is as follows. So while driving, the high side switch will be given PWM (Pulse Width Modulation), while the low side will be given normal switching pulses. This aims to reduce switching loss in the lower switch section.

When power flows from the motor as an electric generator to the DC-Link, the converter will operate as a reactifier (rectifier). In the condition that no switch is active, the output voltage can be considered as the output of a three-phase rectifier diode.

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(b)

Fig. 4. (a). BLDC motor equivalent circuit in regenerative braking, and (b). Voltage waveform in the phase winding of the BLDC

generator and the output voltage from the reactifier.

In order for power to flow to the DC-Llink, the voltage at the converter output must be greater than the voltage of the battery connected to the DC-Link. To achieve the

required conditions, it can be adopted based on the DC- DC boost converter (chopper) concept. Therefore, two operating modes are needed to jack up the chopper. In the first mode, energy will be stored in the inductor (phase winding) and in the second mode, it transfers energy to the load side (DC-Link). The phase coil that has maximum and minimum back emf must be used as a source for the boost chopper, in the equivalent circuit when phase A and phase B coils have high and low back emf for the first mode of boost chopper shown in figure 5(a). This is implemented by activating the bottom switch of the phase coil with high back emf (S2), so that the two phase windings (phase A and phase B) will be connected via switch S2 and diode D4. By ignoring the phase resistance, the simplified circuit is shown in Figure 5(b).

(a)

(b)

Fig. 5. The path of the bldc motor is in regenerative braking when 𝒗_𝒂> 𝒗_𝒄> 𝒗_𝒃 and stores energy in the windings, and (b). Equivalent circuit of bldc generator when 𝒗𝒂> 𝒗𝒄> 𝒗𝒃 in energy storage in the

winding.

Based on the circuit in Figure 5, the equation corresponding to the instantaneous voltage and current can be derived as follows.

𝑒_𝑎− 𝑒_𝑏= 𝑣_𝑙 (9) 𝑒_𝑎− 𝑒_𝑏= 2𝐿^𝑑𝑖^𝑎

𝑑𝑡 (10)

∆𝑖_𝑎=^𝑒^𝑎^−𝑒^𝑏

2𝐿 𝑡_𝑜𝑛 (11) Where 𝑒_𝑎, 𝑒_𝑏, 𝑣_𝑙, 𝑖_𝑎, and ∆𝑖_𝑎 respectively are b-emf phase A, b-emf phase B, inductor voltage, current in phase A, and current fluctuations in phase A. After the first mode the energy is stored in in the inductor, then in the second operating mode the boost chopper is activated by turning off all the switches, this results in the energy stored in the inductor being completely transferred to the DC-Link. In this mode the sum of the voltage from the inductor and b-emf is the same as the voltage from the DC-Link (Vdc). More details are shown in figure 6.

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Fig. 6. (a). The current path of the bldc motor in regenerative braking when 𝒗_𝒂> 𝒗_𝒄> 𝒗_𝒃 and energy is transferred to the DC-Link, and (b). The equivalent circuit of the bldc generator when 𝒗_𝒂> 𝒗_𝒄> 𝒗_𝒃 is in the condition that the energy is transferred to the DC-Link.

The equation that corresponds to the above conditions is as follows.

(𝑒_𝑎−𝑒_𝑏) + 𝑣_𝐿= 𝑉_𝑑𝑐 (12) 2𝐿^𝑑𝑖^𝑎

𝑑𝑡 = 𝑉_𝑑𝑐− (𝑒_𝑎− 𝑒_𝑏) (13)

∆𝑖_𝑎=^𝑉^𝑑𝑐^−(𝑒^𝑎^−𝑒^𝑏⁾

2𝐿 𝑡_𝑜𝑓𝑓 (14) By substituting equation (11) into (14), it produces a converter output voltage which functions as a reactifier (Vdc). This voltage is a function of the duty cycle (d).

𝑉_𝑑𝑐= ¹

1−𝑑(𝑒_𝑎− 𝑒_𝑏) (15) When the internal resistance and voltage of the battery are 𝑟_𝑑 and E, then the battery charging current (𝐼_𝑐ℎ𝑔) is.

𝐼_𝑐ℎ𝑔=^𝑉^𝑑𝑐^−𝐸

𝑟_𝑑 (16) III. METHOD

This research uses a battery as an energy source, a controller with a bidirectional converter to control a bldc motor, and a bldc motor which plays a dual role on an electric motorbike, first as a motor that functions as a driver when the motorbike is used for driving and secondly as a generator which functions to produce electricity during the braking process. The block diagram of this research's regenerative braking system can be seen in Figure 7.

BATERAI 48V 15Ah

KONTROLER

MOTOR BLDC MOTOR BLDC PUTARAN MOTOR Masukan

ADC 1&2

BLDC Sebagai Generator

Fig. 7. Block diagram of the regenerative braking system.

A. BLDC Motor

In this research, the BLDC motor used is the Tiger Motor BLDC with the following specifications.

TABLE I.

TIGER MOTOR BLDC SPECIFICATIONS

Merk Tiger

Type BLDC

Power 350 W

Diameter 45 cm

V Suplai 48 V

Wheel Angular Speed 420 rpm

Torsi 180 kg.cm

From the specifications in Table 1, it can be seen that the maximum speed that the motorbike can produce in km/hour is with the following equation.

The angular velocity of the wheel (rpm) is converted to speed (^𝑚

𝑠) by equation,

𝑣_(𝑚.𝑠⁻¹₎= 𝑟 × 𝜔_{(𝑟𝑎𝑑.𝑠}⁻¹₎= 𝑟 ×^2𝜋

60× 𝑁_{(𝑟𝑝𝑚)} (17) If the speed (^𝑚

𝑠) is converted into (^𝑘𝑚

𝐻𝑜𝑢𝑟), the following equation is obtained,

𝑣_{(𝑘𝑚.𝐽𝑎𝑚}⁻¹₎=³⁶⁰⁰

1000× 𝑣_(𝑚.𝑠⁻¹₎= 3.6 × 𝑣_(𝑚.𝑠⁻¹₎ (18) So, the angular speed of the wheel (rpm) when converted to speed ( ^𝑘𝑚

𝐻𝑜𝑢𝑟𝑠) is, 𝑣_{(𝑘𝑚.𝐻𝑜𝑢𝑟}⁻¹₎=³⁶⁰⁰

1000× 𝑣_(𝑚.𝑠⁻¹₎ =³⁶⁰⁰

1000× 𝑟 ×^2𝜋

60× 𝑁_{(𝑟𝑝𝑚)} =³⁶⁰⁰

1000× (⁴⁵

2 ÷ 100) ×^2(3,14)

60 × 420 = 35,6076 𝑘𝑚. 𝐻𝑜𝑢𝑟⁻¹

So, the electric motorbike being built will have a maximum speed without load of 35 Km. 𝐻𝑜𝑢𝑟⁻¹.

B. Test Preparation

At this stage the researcher creates a test scenario by paying attention to several aspects of the test parameters that must be equalized because they can influence the test results, including the total mass of the vehicle (vehicle and driver), the test route or track, vehicle speed, and SOC (state of charge) of the battery. Next, the tests will be differentiated based on the braking method used, namely using regenerative braking with the on/off switching method with three major variations of braking and using the regenerative variable method. The test scenarios that will be carried out can be seen in table 2 below.

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TABLE II.

TESTING SCENARIO OF REGENERATIVE BRAKING METHOD ON ELECTRIC MOTORCYCLES

No Test Parameters

METHOD Switching On/Off Variabel

Regeneratif

1 Total mass ±105 Kg ±105 Kg

2 Rute Jalan Perumahan

Tidar

Jalan Perumahan Tidar

3 Route Length ±850 Meter ±850 Meter 4 Velocity ± 0-35 Km/Hour ± 0-35 Km/Hour 5 Battery Voltage ± 52-53 Volt ± 52-53 Volt 6 Braking Level 10%

50%

95%

Flexible According to Needs

In accordance with the test scenario in table 4, before carrying out a regenerative braking test on an electric motorbike, several preparations are required, including ensuring the total weight of the vehicle, determining the route, and ensuring battery voltage using an Avometer.

Ensure that the total weight of the vehicle, namely the weight of the vehicle and driver in each test, must be the same at ±105 Kg, with the vehicle weight being ±40 Kg and the driver's weight being ±65 Kg. Ensuring the total weight of the vehicle aims to obtain valid test results data, because the total weight of the vehicle can affect the amount of kinetic energy produced when an electric motorbike is driven. This can affect the efficiency of regenerative braking, therefore paying attention to and ensuring the total weight of the vehicle in testing is one of the keys to ensuring the validity of the test results data.

The next preparation is determining the testing route.

Based on several aspects that are considered to carry out testing such as road conditions, including inclines, descents, flat roads, and vehicle density to represent daily use, drivers can ride electric motorbikes with various levels of speed and varying levels of braking. By considering these aspects and paying attention to the security and safety of the driver and other motorists, the appropriate test route is on a Tidar residential road with a route distance of ±850 meters as shown in Figure 8.

This route selection is considered to be in accordance with testing requirements according to aspects of road conditions without ignoring security and safety for drivers and other motorists, because this route has inclines, flat roads, descents, and most importantly the vehicles passing on this road are not as congested as in the middle of the city. So drivers can still drive at various levels of speed and braking variations as needed to get test results safely.

Fig. 8. Tidar Residential Road Testing Route Map.

IV. RESULTS AND DISCUSSION

Based on the test preparation scenario that has been described, the test carried out is an experimental test which aims to determine and compare the efficiency of regenerative braking using the on/off switching method with regenerative braking using the variable method. The results of the tests that have been carried out are as follows.

A. Regenerative Switching Braking Testing

In regenerative braking testing using the on/off switching method, the test will be carried out with three levels of braking magnitude according to the scenario in table 2, namely with braking magnitudes of 10%, 50%

and 95% divided into three driving cycles. So, regenerative braking testing using the on/off switching method will be carried out three driving cycles with the braking level as stated above. The results of the regenerative braking test using the on/off switching method according to the scenario are as follows.

1) Regenerative Switching Braking 10%

The first test of regenerative braking used the switching method, namely by using the gas throttle as input to run the electric motorbike when the gas throttle was pulled and vice versa, braking when the gas throttle was released. In this test the controller was set to be able to perform regenerative braking by 10%.

The results obtained are presented in table 3. The initial to final parameter values include voltage, ampere hours draw, ampere hours charge, watt hours draw, watt hours charge, and distance. Other data results such as battery voltage, motor current, power consumption and vehicle speed in one driving cycle are presented in graphical form as shown in the following image.

TABLE III.

INITIAL AND FINAL PARAMETER VALUES OF REGENERATIVE SWITCHING BRAKING TEST 10%

Regenerative Switching Braking 10%

No Parameters Initial Value Final Value 1 Battery Voltages (V) 52,50 52,00

2 Ah Draw (mAh) 0 217,60

3 Ah Charge (mAh) 0 22,70

4 Wh Draw (Wh) 0 11,044

5 Wh Charge (Wh) 0 1,189

6 Distances (Meter) 895,96

(a)

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(b)

(c)

(d)

Fig. 9. Graph of Battery Voltage (a), Motor Current (b), Motor Power (c) and Vehicle Speed (d) Regenerative braking Switching 10%

during one driving cycle.

In the second test of regenerative switching braking, the amount of braking applied to the controller was 50%.

The resulting data obtained is presented in table 4. The initial to final parameter values include voltage, ampere hours draw, ampere hours charge, watt hours draw, watt hours charge, and distance. Other data results such as battery voltage, motor current, power consumption and vehicle speed in one driving cycle are presented in graphical form as shown in the following image.

TABLE IV.

2 Ah Draw (mAh) 0 250,00

4 Wh Draw (Wh) 0 12,702

5 Wh Charge (Wh) 0 3,057

(a)

(b)

(c)

(d)

Fig. 10. Graph of Battery Voltage (a), Motor Current (b), Motor Power (c) and Vehicle Speed (d) Regenerative braking Switching 50%

during one driving cycle.

The third test of the regenerative switching braking system, the amount of braking applied to the controller was 95%. The resulting data obtained is presented in table 5, the initial to final parameter values include voltage, ampere hours draw, ampere hours charge, watt hours draw, watt hours charge, and distance. Other data results such as battery voltage, motor current, power consumption and vehicle speed in one driving cycle are presented in graphical form as shown in the following image.

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TABLE V.

2 Ah Draw (mAh) 0 269,6

4 Wh Draw (Wh) 0 13,749

5 Wh Charge (Wh) 0 2,177

(a)

(b)

(c)

(d)

Fig. 11. Graph of Battery Voltage (a), Motor Current (b), Motor Power (c) and Vehicle Speed (d) Regenerative braking Switching 95% during one driving cycle.

B. Regenerative Variable Braking Testing

In regenerative braking testing using the variable method, the test is carried out with the level of flexible braking according to the braking requirements in one driving cycle according to the predetermined route. So, the driver can brake as needed while driving.

The results obtained from testing the regenerative variable braking system are presented in table 6. The initial to final parameter values include voltage, ampere hours draw, ampere hours charge, watt hours draw, watt hours charge, and distance. Other data results such as battery voltage, motor current, power consumption and vehicle speed in one driving cycle are presented in graphical form as shown in the following image.

TABLE VI.

INITIAL AND FINAL PARAMETER VALUES OF REGENERATIVE VARIABLE BRAKING TEST

Regenerative variable braking

2 Ah Draw (mAh) 0 235,8

4 Wh Draw (Wh) 0 12,105

5 Wh Charge (Wh) 0 2,425

(a)

(b)

(c)

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(d)

Fig. 12. Graph of Battery Voltage (a), Motor Current (b), Motor Power (c), and Vehicle Speed (d) regenerative variable braking during

one driving cycle.

C. Discussion

Based on the test graph data for regenerative switching braking and regenerative variable braking in Figures 9(a), 10(a), 11(a) and 12(a), the battery voltage graph is shown during the testing process. From this graph, it can be seen that during the testing process of electric motorbikes, the battery voltage value decreases and increases when riding. The battery voltage value will decrease when the motorbike enters drive mode (riding), this is because the bldc motorbike consumes battery power to maintain speed and overcome gravitational obstacles such as on uphill roads or overcome frictional forces with the road when driving. The voltage drop occurs because when the motorbike experiences resistance, the load on the motorbike will increase. This increase in load causes the motor to require more power to maintain speed or overcome obstacles. Therefore, when the power required by a bldc motor increases as the load increases, the battery must supply a greater current to maintain power from the motor so that it can maintain speed or overcome resistance.

The voltage value will be inversely proportional to the motor current value, this can be seen from the motor current graph in Figures 9(b), 10(b), 11(b) and 12(b). In accordance with the power equation, where power is the product of voltage and current. So, in this case the amount of power will be proportional to the amount of current. Therefore, when the motor experiences resistance and the load increases, to maintain motor power so that it can maintain speed, the current flowing from the battery to the motor must also be increased. This can be seen in the motor power graph presented in figures 9(c), 10(c), 11(c) and 12(c). In this graph, it can be seen that the amount of power in the regenerative braking testing process using the switching and variable method increases and decreases with a rhythm that is in line with the amount of current flowing through the motor. This makes the graphic image of motor current and motor power seem to have the same thing, which also proves that the amount of motor power to maintain speed and overcome obstacles is greatly influenced by the amount of current flowing from the battery to the electric motor.

Next, figures 9(d), 10(d), 11(d) and 12(d) present graphs of the speed of electric motorbikes during regenerative braking tests in one driving cycle. If you look and observe that the motorbike speed graph has a

different pattern from the three previous graphs, if the voltage graph has a pattern that is inversely proportional to the pattern on the current and power graphs, then the motorbike speed graph has a slightly irregular pattern, p.

This is because the test route is designed to reflect real conditions so that the route has varied contours such as ascents, descents and flat roads. For example, when the power increases during initial acceleration, the vehicle speed also increases, but in situations such as an incline or descent, this will be different. Where when a motorbike goes up an incline the power required is large but the vehicle speed tends to be slow or low. On the other hand, when road conditions decrease, the power required is small but the vehicle speed tends to be high.

Therefore, when road conditions decrease, the efficiency of regenerative braking tends to be high. However, in this test the braking efficiency value is calculated from the cumulative power absorbed compared to the cumulative power used to run the motorbike in one driving cycle according to the same scenario for both braking methods.

To simplify efficiency calculations, the data obtained is summarized in the two tables below. Where in table 7 contains data from testing regenerative switching braking and table 8 contains data on regenerative variable braking. The following is the data table.

TABLE VII.

COMPARISON OF INITIAL VALUE WITH FINAL VALUE OF REGENERATIVE SWITCHING BRAKING TESTING

Braking Level

10% 50% 95%

No Parameter Initial Value

Final Value

Initial Value

Final Value

Initial Value

Final Value 1 Battery

Voltages (V)

52,50 52,00 52,60 52,00 52,60 52,10

2 Ah Draw (mAh)

0 217,60 0 250,00 0 269,6

3 Ah Charge (mAh)

0 22,70 0 57,80 0 40,9

4 Wh Draw (Wh)

0 11,044 0 12,702 0 13,74

9 5 Wh

Charge (Wh)

0 1,189 0 3,057 0 2,177

6 Distances (Meter)

895,96 840,82 840,08

TABLE VIII

COMPARISON OF INITIAL VALUE WITH FINAL VALUE OF VARIABLE BRAKING TEST

2 Ah Draw (mAh) 0 235,8

4 Wh Draw (Wh) 0 12,105

5 Wh Charge (Wh) 0 2,425

Based on Tables 7 and 8, the efficiency of regenerative switching braking according to the level of braking and regenerative braking variables can be calculated according to equation (2.8) which is presented in table 9.

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TABLE IX

MAXIMUM SPEED AND EFFICIENCY VALUE IN EVERY REGENERATIVE BRAKING TEST

Braking level Velocity (m/s) Velocity

(Km/Jam) Efisiensi

Switching 10% 8,43 30,34 10,76%

Switching 50% 8,23 29,63 24,07%

Switching 95% 8,23 29,63 15,83%

Variabel Regeneratif

8,45 30,42 20,03%

So, from the data obtained including the maximum speed of electric motorbikes and efficiency calculations, it can be seen that the efficiency of regenerative braking using the switching method with a braking amount of 50% has a greater efficiency compared to the efficiency of regenerative switching braking of 10%, 95%, and only has a 4% difference from regenerative variable braking.

V. CONCLUSIONS

Based on the discussion of the results and analysis of the regenerative braking tests presented in the previous chapter, the conclusions that can be drawn are as follows.

When testing regenerative braking, it is necessary to pay attention to variables or factors that can influence the efficiency value, such as determining the trajectory, weight of the vehicle and driver, and vehicle speed. By paying attention to these factors, the validity of the data obtained is much higher.

Regenerative braking using the switching method with a braking level of 50% gets the highest efficiency, namely 24.06%, followed by regenerative variable braking with 20.03%, the third regenerative braking using the switching method with a braking level of 95%

has an efficiency of 15.83%, and finally regenerative braking using the switching method with a braking level of 10% has an efficiency of 10.76%.

Regenerative variable braking has an efficiency slightly below regenerative braking using a 50%

switching method. However, regenerative variable braking is still superior in terms of comfort because it has a flexible braking level according to the driver's needs.

Apart from that, it is possible that in test scenarios such as different road conditions, regenerative variable braking gets better efficiency than regenerative switching braking because of its flexible braking level.

REFERENCES

[1] Badan Pusat Statistik, “Perkembangan Jumlah Kendaraan Bermotor Menurut Jenis (Unit), 2018-2020,” Badan Pusat Statistik, 2022. https://www.bps.go.id/indicator/17/57/1/jumlah- kendaraan-bermotor.html (accessed Nov. 11, 2022).

[2] Rusli, M., Wibawa, U., Hasanah, R.N., Zainuri, A., Parameter Estimation of Li-Polymer Battery Using Non-Linear Feedback Structure Aproximation Proceedings - 11th Electrical Power, Electronics, Communications, Control, and Informatics Seminar, EECCIS 2022, 2022, pp. 264–269.

[3] Ardhenta, L., Rusli, M., Sliding Mode Control of Output Voltage in DC-DC Boost Converter Using PI Sliding Surface, Proceedings–IEIT 2021: 1st International Conference on Electrical and Information Technology, 2021, pp. 228–232.

[4] Rusli, M., Widjonarko, Rahmadwati, Abidin, Z., Synthesis- algorithm of bang-bang controller with delayed feedback on

temperature controlled systems EECCIS 2020 - 2020 10th Electrical Power, Electronics, Communications, Controls, and Informatics Seminar, 2020, pp. 122–127, 9263463.

[5] S. H. Karthik, “How Regenerative Braking Works in Electric Vehicles,” 2019.

https://circuitdigest.com/article/how-regenerative-braking- works-in-electric-vehicles (accessed Feb. 13, 2023).

[6] Valladolid, Juan, et al. “Analysis of Regenerative Braking Efficiency in an Electric Vehicle Through Experimental Tests.”

Ingenius, vol. 2023, no. 29, 2023, pp. 24–31, https://doi.org/10.17163/ings.n29.2023.

[7] D. Laskay, “Conneccvity Power Control,” October, 2015.

[8] Anthony Ingram, “Ford : Regenerative Braking Has Saved 100 Million Gallons of Gas,” Green Car Reports, 2013.

https://www.greencarreports.com/news/1084850_ford- regenerative-braking-has-saved-100-million-gallons-of-gas.

[9] B. J. Varocky, “Benchmarking of Regenerative Braking for a Fully Electric Car,” Rep. No. D&C 2011.002, vol. 2, no. D, p. 44, 2011, [Online]. Available:

https://web.archive.org/web/20100706214811/http:/www.formul a1.com/inside_f1/understanding_the_sport/8763.html.

[10] Binggang, C., Zhifeng, B., & Wei, Z. (2005). Research on control for regenerative braking of electric vehicle. 2005 IEEE International Conference on Vehicular Electronics and Safety Proceedings, 2005, 92–97.

https://doi.org/10.1109/ICVES.2005.1563620.

[11] Cui, W., Zhang, H., Ma, Y. L., & Zhang, Y. J. (2011).

Regenerative braking control method and optimal scheme for electric motorcycle. International Conference on Power Engineering, Energy and Electrical Drives, May.

https://doi.org/10.1109/PowerEng.2011.6036557.

[12] L. B. Diwakar, S. L. Diwakar, & V. V. Deshpande. (2020). Design and Selection of the Braking System for All Terrain Vehicle.

International Journal of Engineering Research And, V9(04), 730–

733. https://doi.org/10.17577/ijertv9is040663.

[13] Liu, H., He, X., Chu, L., & Tian, J. (2011). Study on control strategy of regenerative braking for electric bus based on braking comfort. Proceedings of 2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, 2, 1037–1040.

https://doi.org/10.1109/EMEIT.2011.6023184.

[14] Mochamad Rachmadi, M. Aziz Muslim, & Erni Yudaningtyas.

“Sistem Kontrol Kecepatan Sepeda Listrik Menggunakan Metode Self-Tuning Parameter PI Dengan Metode Logika Fuzzy.” Jurnal EECCIS vol. 10, no. 1, 2016, pp. 26–32,

https://doi.org/10.21776/jeeccis.v10i1.480.

[15] Zakiyah Amalia, Achsanul Khabib, Erni Yudaningtyas, et al.

“Field Oriented Control Untuk Pengaturan Kecepatan Motor BLDC Pada Sepeda Motor Listrik.” Jurnal Elektronika Dan Otomasi Industri, vol. 10, no. 1, 2023, pp. 1–8,

https://doi.org/10.33795/elkolind.v10i1.1977.

[16] Rozan, M. I., Rusli, M., Muslim, M. A. Control of Direct Current (DC) Output Voltage for Two Level DC/DC Boost Converter by Sliding Mode Controller in Application of Fuel Cell, ICCoSITE 2023 - International Conference on Computer Science, Information Technology and Engineering: Digital Transformation Strategy in Facing the VUCA and TUNA Era, 2023, pp. 12–16.

[17] Rusli, M., Choiron, M.A., Muslim, M.A., Modified loop shaping algorithm in designing 2-DOF controller of a ladder-secondary double-sided linear induction motors International Journal of Advanced Trends in Computer Science and Engineering, 2019, 8(1.6 Special Issue), pp. 536–542, 79.

[18] Kim, Jongkuk and Kim, Youngchul. "Analysis of Regenerative Braking Efficiency in Electric Vehicles Based on Road Load and Speed Profile." Energies, vol. 13, no. 14, 2020, pp. 3591-3605.

[19] Wu, Jian and Hua, Jinsong. "Analysis and Simulation of Energy Recovery Efficiency of Electric Vehicle Regenerative Braking System." International Journal of Energy Engineering, vol. 9, no.

2, 2019, pp. 54-61.

[20] Akbar Gumilang, Y.S., Rusli, M., Siswoyo, B., Linear Quadratic Regulator and Luenberger Observer for Solar Tracking System Proceedings - IEIT 2021: 1st International Conference on Electrical and Information Technology, 2021, pp. 106–113.