Cell imbalance has always happened in the series-connected battery. Series-connected battery needs to be balanced to maintain capacity and maximize the batteries lifespan. Cell balancing helps to dispart energy equally among battery cells. For active cell balancing, the use of a DC-DC converter module for cell balancing is quite common to achieve high efficiency, reliability, and high power density converter. This paper describes the implementation of a LiFePO4 battery charger based on the DC-DC converter module used for cell balancing application. A constant current-constant voltage (CC-CV) controller for the charger, which is a general charging method applied to the LiFePO4 battery, is presented for preventing overcharging when considering the nonlinear property of a LiFePO4 battery. The prototype is made up with an input voltage of 43V to 110V and the maximum output voltage of 3.75V, allowing to charge a LiFePO4 cell battery and balancing the battery pack with many cells from 15 to 30 cells. The goal is to have a LiFePO4 battery charger with an approximate power of 40W and the maximum output current of 10A. Experimental results on a 160AH LiFePO4 battery for some state of charge (SoC) shows that the maximum battery voltage has been limited at 3.77 volt and maximum charging current could reach up to 10.64 A. The results show that the charger can maintain battery voltage at the maximum reference voltage and avoid the LiFePO4 battery from overcharging.

Abstractone of the present-day implementation of fuel cell is acting as main power source in Fuel Cell Hybrid Vehicle (FCHV). This paper proposes some strategies to optimize the performance of Polymer Electrolyte Membrane Fuel Cell (PEMFC) implanted with auxiliary power source to construct a proper FCHV hybridization. The strategies consist of the most updated optimization method determined from three point of view i.e. Energy Storage System (ESS), hybridization topology and control system analysis. The goal of these strategies is to achieve an optimum hybridization with long lifetime, low cost, high efficiency, and hydrogen consumption rate improvement. The energy storage system strategy considers battery, supercapacitor, and high-speed flywheel as the most promising alternative auxiliary power source. The hybridization topology strategy analyzes the using of multiple storage devices injected with electronic components to bear a higher fuel economy and cost saving. The control system strategy employs nonlinear control system to optimize the ripple factor of the voltage and the current and using the AOC-EMS system to improve the hydrogen consumption rate. ECMS and BERS strategy based on Time-Triggered Controller Area Network (TTCAN) also promoted to optimize hydrogen consumption rate from recovered kinetic energy while in braking regeneration mode. mencapai hibridisasi optimal dengan masa pakai lama, biaya rendah, efisiensi tinggi, dan perbaikan tingkat konsumsi hidrogen. Strategi sistem penyimpanan energi menggunakan baterai, super dan roda gila kecepatan tinggi (high-speed flywheel) AbstrakSalah satu implementasi sel bahan bakar saat ini adalah berfungsi sebagai sumber daya utama pada kendaraan hibrida berbasis sel bahan bakar (FCHV). Makalah ini mengusulkan beberapa strategi untuk mengoptimalkan kinerja sel bahan bakar jenis polymer electrolyte membrane (PEMFC) yang digabungkan dengan sumber energi lainnya untuk membangun sebuah hibridisasi FCHV yang tepat. Strategi terdiri dari metode optimasi terkini dilihat dari tiga sudut pandang yaitu sistem penyimpanan energi (ESS), topologi hibridisasi dan analisis sistem kontrol. Tujuan dari strategi ini adalah untuk sebagai sumber listrik alternatif yang paling menjanjikan. Strategi topologi hibridisasi menganalisis penggunaan beberapa perangkat penyimpanan energi digabungkan dengan komponen elektronik untuk menghasilkan bahan bakar yang ekonomis dan hemat biaya. Strategi sistem kontrol menggunakan sistem kontrol nonlinier untuk mengoptimalkan faktor riak tegangan dan arus dan menggunakan sistem AOC-EMS untuk meningkatkan efisiensi hidrogen. Strategi ECMS dan BERS berdasarkan Time-Triggered Controller Area Network (TTCAN) juga dipromosikan untuk mengoptimalkan tingkat konsumsi hidrogen dari pemulihan energi kinetik ketika terjadi pengereman.Kata KunciPEMFC, strategi optimalisasi, FCHV, ESS, sistem kendali, topologi hibrid

Stress analysis of welded steel-to-steel, bolted steel-to-steel, and bolted composite-steel chassis in an electric low floor medium bus structure is presented in this paper. The analysis was carried out on the condition that is when the bus is full of load in idle/static. This condition reflects the situation of the vehicle in full load with passengers and components, which is important to be analyzed to anticipate the unwanted structural failure of the chassis. Finite Element Method (Harmonic response simulation) is used to investigate the structural behavior of both welded and bolted methods. Several parameters such as 2 Hertz for the maximum frequency, 5000 kg for the total vehicle weight, and the uniform distribution of load are used for this study to simulate the simplified, real application in the real world. The first comparison is between the welded and bolted steel-to-steel chassis which results in the bolted method has a lower stress value by the difference of 4.3 MPa in the joint section than the welded joint. This means that the bolted joint is more recommended than welded for the use as an electric low floor medium bus and has the potential to be optimized further. In terms of reducing the weight of the chassis structure, then lightweight material (carbon fiber composite) is used to replace the full steel chassis to be a composite-steel chassis. The use of this hybrid material depicts the stress value of 61.5 MPa in the joint area, this value is still far below the limit of carbon fiber that is 3200 MPa makes this bolted composite-steel is considerably safe in full load condition as an electric low floor medium bus structure. Using this hybrid bolted composite-steel chassis structure also reduces the total chassis weight by about 22.7 % compared to the full steel chassis structure, thus one could expect to extend the mileage of electric vehicles by more than 20 %

Well-regulated DC bus voltage is the important point to guarantee power demand fulfillment in hybrid vehicle applications. Voltage regulation can be achieved with control method that determines switching signal on DC-DC converter. This paper describes the design and small scale experiment results of bus voltage regulation control for DC-DC bidirectional converter with battery and supercapacitor as energy sources. The control system consisted of two control loops. The outer loop got DC bus voltage feedback using anti-windup PI back calculation control method. This outer loop would generate a reference current for the inner loop that implemented hysteresis control. The inner control loop compared that reference curent with the source current obtained from the current sensor. Simulation and experiment results showed that bus voltage was well-regulated under the load changes of 1% ripple voltage. I. PENDAHULUANKebutuhan akan energi terus meningkat seiring berjalannya waktu. Bahan bakar minyak masih menjadi pilihan utama bagi kebanyakan orang. Pertumbuhan jumlah kendaraan yang sangat pesat tidak sebanding dengan jumlah bahan bakar minyak yang tersedia. Jumlah kendaraan di dunia yang mencapai ratusan juta unit merupakan konsumen bahan bakar minyak terbesar yang membakar ratusan milyar galon bahan bakar tiap tahunnya. Selain faktor ketersediaan bahan bakar minyak yang terbatas, faktor lingkungan juga menjadi isu yang sangat krusial. Penggunaan bahan bakar minyak dapat menimbulkan polusi berupa gas buang CO 2 dan gas CO yang berbahaya bagi manusia, dan juga dapat merusak lapisan ozon.

Cell imbalance can cause negative effects such as early stopping of the battery charging and discharging process which can reduce its capacity. In the previous active balancing research, the energy used for the balancing process was taken from the cell or battery pack, resulting in drop of electric vehicle driving range. In this paper, a cell charger based battery balancing system is proposed with a reduction in the number of switches. The use of a cell charger aims to increase the usable energy of the battery pack, since the energy used for the balancing process is taken directly from the grid. The use of fewer switches aims to reduce the cost and space used on the battery management system (BMS) hardware. The charger used for the balancing process has a maximum current of 3 A and a maximum voltage of 3.65 V while the number of switches used is <em>n</em>+5 for <em>n</em> batteries. A 15S1P 200 Ah LiFePO₄ battery pack consists of 15 cells used for testing purpose. The test results show that the time needed to equalize the 15 cell battery voltage reaches 6 hours from the difference between the highest and lowest battery cell voltages of 145.1 mV to 15.1 mV.