Converter For Electric Vehicles Research Articles

DC-DC Converter in Electric Vehicle

DC-DC Converter in Electric Vehicle

Analysis and design of a high gain non-isolated zero current switching bidirectional DC–DC converter for electric vehicles

ABSTRACTThis paper presents a dual inductor based current-fed bidirectional non-isolated DC–DC converter for energy storage applications. The main idea of this converter is to achieve a higher voltage conversion ratio by obtaining the operation of zero current switching. The proposed soft-switching bidirectional DC–DC converter reduces the turn-off switching losses with the aid of auxiliary network, where, the auxiliary network comprised with the resonant inductor and the resonant capacitor. This converter operates under two different operating modes such as a boost (discharge) and buck (charge) modes. In both the modes of converter operations, the IGBTs are operating under zero current turn-off in order to minimize the switch turn-off losses and to improve the efficiency of the converter. The principle of the operations and its theoretical analysis are validated by the experimental results using a 300W (50 V/250 V) converter system.

Design of a 1-MHz High-Efficiency High-Power-Density Bidirectional GaN-Based CLLC Converter for Electric Vehicles

In this paper, a bidirectional CLLC converter operating at MHz-level switching frequency is proposed to achieve high power density and high efficiency. An optimized stacked printed circuit board winding based planar transformer with adjustable leakage inductance is modeled and designed for the proposed converter. It is enabled using gallium nitride devices to achieve fast switching with low switching losses. A detailed power loss model is established for the efficient thermal design of the converter. A proof-of-concept hardware of 3.3 kW, 400–450 VDC input, 250–420 VDC output CLLC converter with 1 MHz operating frequency is built and tested over a wide range of loading conditions. The power density of the system is 9.22 W/cm3 (151.1 W/in3) and the peak efficiency achieves over 97%.

The correlation between the capacity fade of LiFePO4 batteries and cycle life

A new model is developed by fitting the capacity of LiFePO$_4$ batteries, which can be used to investigate the relationship between capacity fade, state of health (SoH), electrochemical reactions and the number of cycles. The equation for the proposed model based on modified Thevenin circuit, Butler-Volmer kinetics and regression analysis consists of a constant term, a sine-exponential term and an exponential term. The constant term represents the rated capacity of a battery, while the sine-exponential term represents the variation in capacity in the active status and the exponential term represents the variation in capacity in the stable status. The model is divided into two parts. The first part is represented by the sine-exponential term, responsive to the activation of electrolyte and electrodes in the first 180 cycles; the second part can be described by the exponential term, estimating the capacity from cycle 180 to cycle 2000. In addition, the comparison between the model and mean absolute percentage error (mape) is able to predict the serious decay of capacity. The MAPE is only 0.47% for the tested battery. The proposed model also successfully estimates the capacity of a tested battery where the number of cycles is 2000 with the error of 0.90%. The results mean that the model is able to closely describe the correlation between capacity and the cycle numbers. References M. Zhao, G. Huang, W. Zhang, H. Zhang and X. Song, Electrochemical behaviors of limn1-xfexpo4\(/\)c cathode materials in an aqueous electrolyte with/without dissolved oxygen, Energy and Fuels 27 (2013), 2:1162-1167. doi:10.1021/ef301893b Y.-C. Wang, F.-M. Ni and T.-L. Lee, Hybrid modulation of bidirectional three-phase dual-active-bridge dc converters for electric vehicles, Energies 9 (2016), no. 7, 492. doi:10.3390/en9070492 A. H. N. Galapitage and P. Pudney, Scheduling electric vehicles with shared charging stations, ANZIAM Journal 57 (2016), 208. doi:10.21914/anziamj.v57i0.10443 T. Zhu, H. T. Min, Y. B. Yu, Z. M. Zhao, T. Xu, Y. Chen, X. Y. Li and C. Zhang, An optimized energy management strategy for preheating vehicle-mounted li-ion batteries at subzero temperatures, Energies 10 (2017), no. 2. doi:24310.3390/en10020243 K. M. Tsang and W. L. Chan, State of health detection for lithium ion batteries in photovoltaic system, Energ Convers Manage 65 (2013), 7-12. doi:10.1016/j.enconman.2012.07.006 Z. Rao, S. Wang, M. Wu, Z. Lin and F. Li, Experimental investigation on thermal management of electric vehicle battery with heat pipe, Energ Convers Manage 65 (2013), 92-97. doi:0.1016/j.enconman.2012.08.014 A. Nikolian, Y. Firouz, R. Gopalakrishnan, J.-M. Timmermans, N. Omar, P. van den Bossche and J. van Mierlo, Lithium ion batteries-development of advanced electrical equivalent circuit models for nickel manganese cobalt lithium-ion, Energies 9 (2016), no. 5, 360. doi:10.3390/en9050360 Z. Gao, C. Chin, W. Woo and J. Jia, Integrated equivalent circuit and thermal model for simulation of temperature-dependent lifepo_4 battery in actual embedded application, Energies 10 (2017), no. 1, 85. doi:10.3390/en10010085 S.-Y. Lee, W.-L. Chiu, Y.-S. Liao, K.-Y. Lee, J.-H. Chen, H.-J. Lin and K. Li, Modified empirical fitting of the discharge behavior of lifepo_4 batteries under various conditions, ANZIAM Journal textbf55 (2014), 368. doi:10.21914/anziamj.v55i0.8182 C.-Y. Chung, K.-Y. Lee, T.-J. Kuo, Z.-Y. Lin, S.-D. Wu, C. Fu, Mathematical fitting for the variation in capacity of lithium iron phosphate batteries corresponding to cycles, ANZIAM Journal 57 (2016), 291. doi:10.21914/anziamj.v57i0.10436 T. Zahid and W. Li, A comparative study based on the least square parameter identification method for state of charge estimation of a lifepo_4 battery pack using three model-based algorithms for electric vehicles, Energies 9 (2016), no. 9, 720. doi:10.3390/en9090720 T. Sasaki, Y. Ukyo and P. Novak, Memory effect in a lithium-ion battery, Nat Mater 12 (2013), no. 6, 569-575. doi:10.1038/nmat3623 B. R. Tiwari and M. M. Ghangrekar, Enhancing electrogenesis by pretreatment of mixed anaerobic sludge to be used as inoculum in microbial fuel cells, Energy \(and\) Fuels 29 (2015), no. 5, 3518-3524. doi:10.1021/ef5028197 P. Bai and M. Z. Bazant, Charge transfer kinetics at the solid-solid interface in porous electrodes, Nat Commun 5 (2014), 3585. doi:10.1021/ef990039t A. Eddahech, O. Briat and J.-M. Vinassa, Determination of lithium-ion battery state-of-health based on constant-voltage charge phase, Journal of Power Sources 258 (2014), 218-227. doi:10.1016/j.jpowsour.2014.02.020 R. Castaing, Y. Reynier, N. Dupre, D. Schleich, S. J. S. Larbi, D. Guyomard and P. Moreau Degradation diagnosis of aged li4ti5012-lifepo_4 batteries, Journal of Power Sources 267 (2014), 744-752. doi:10.1016/jpowsour.2014.06.002 H. Bulter, F. Peters, J. Schwenzel and G. Wittstock, In situ quantification of the swelling of graphite composite electrodes by scanning electrochemical microscopy, J Electrochem Soc 163 (2016), no. 2, A27-A34. doi:10.1149/2.1061514jes

Conducted EMI Prediction and Mitigation Strategy Based on Transfer Function for a High-Low Voltage DC-DC Converter in Electric Vehicle

The high dv/dt and di/dt outputs from power devices in a high-low voltage DC-DC converter on electric vehicles (EVs) can always introduce the unwanted conducted electromagnetic interference (EMI) emissions. A conducted EMI prediction and mitigation strategy that is based on transfer function for the high-low voltage DC-DC converter in EVs are proposed. A complete test for the DC-DC converter is conducted to obtain the conducted EMI from DC power cables in the frequency band of 150 kHz-108 MHz. The equivalent circuit with high-frequency parasitic parameters of the DC-DC converter is built`1 based on the measurement results to acquire the characteristics of the conducted EMI of the DC power cables. The common mode (CM) and differential mode (DM) propagation coupling paths are determined, and the corresponding transfer functions of the DM interference and CM interference are established. The simulation results of the conducted EMI can be obtained by software Matlab and Computer Simulation Technology (CST). By analyzing the transfer functions and the simulation results, the dominated interference is the CM interference, which is the main factor of the conducted EMI. A mitigation strategy for the design of the CM interference filter based on the dominated CM interference is proposed. Finally, the mitigation strategy of the conducted EMI is verified by performing the conducted voltage experiment. From the experiment results, the conducted voltage of the DC power cables is decreased, respectively, by 58 dBμV, 55 dBμV, 65 dBμV, 53 dBμV, and 54 dBμV at frequency 200 kHz, 400 kHz, 600 kHz, 1.4 MHz, and 50 MHz. The conduced voltage in the frequency band of 150 kHz–108 MHz can be mitigated by adding the CM interference filters, and the values are lower than the limit level-3 of CISPR25 standard (GB/T 18655-2010).

Isolated step-down DC -DC converter for electric vehicles

Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.

Electromechanical converters for electric vehicles

The paper presents the analysis of various constructive schemes of synchronous electromechanical converters with permanent magnets fixed on the rotor and asynchronous with the short-circuit rotor. Various electrical stator winding schemes have also been compared, demonstrating the efficiency of copper utilization in toroidal windings. The electromagnetic calculus of the axial machine has particularities compared to the cylindrical machine, in the paper is presented the method of correlating the geometry of the cylindrical and axial machines. In this case the method and recommendations used in the design of such machines may be used.

A High Frequency Converter for EV Application

<p>An electrical vehicle (EV) is advancing as alternative power trains for green transportation. the DC–DC converter for auxiliary power supply of electric loads .In this paper presented a new topologyof high frequency converter for electric vehicle was proposed,This converter has to be capable of handling the energy transfer from the 28V DC bus and the 550 high voltage DC bus (used for the electric traction). The control strategy is phase shift of the full bridge converter. Using this topology we reduce the switching losses. Conventional converter at two levels of voltage by only one full bridge converter using two planar transformers in high frequency the primary are coupled in parallel and the secondary are in series. We minimized the size and the weight of the converter. The high frequency converter advantages in terms of cost, efficiency, flexibility, and increased due to the possibility of easy synchronous rectification implementation.<strong><em></em></strong></p>

Off-Line Optimization Based Active Control of Torsional Oscillation for Electric Vehicle Drivetrain

As there is no clutch or hydraulic torque converter in electric vehicles to buffer and absorb torsional vibrations. Oscillation will occur in electric vehicle drivetrains when drivers tip in/out or are shifting. In order to improve vehicle response to transients, reduce vehicle jerk and reduce wear of drivetrain parts, torque step changes should be avoided. This article mainly focuses on drivetrain oscillations caused by torque interruption for shifting in a Motor-Transmission Integrated System. It takes advantage of the motor responsiveness, an optimal active control method is presented to reduce oscillations by adjusting motor torque output dynamically. A rear-wheel-drive electric vehicle with a two gear automated manual transmission is considered to set up dynamic differential equations based on Newton’s law of motion. By linearization of the affine system, a joint genetic algorithm and linear quadratic regulator method is applied to calculate the real optimal motor torque. In order to improve immediacy of the control system, time consuming optimization process of parameters is completed off-line. The active control system is tested in AMEsim® and limitation of motor external characteristics are considered. The results demonstrate that, compared with the open-loop system, the proposed algorithm can reduce motion oscillation to a satisfied extent when unloading torque for shifting.

Variable Inductor Based Bidirectional DC–DC Converter for Electric Vehicles

This paper presents the feasibility study of variable inductor (VI)-based bidirectional dc–dc converter for applications with a wide range of load variations such as electric vehicles. An additional winding is introduced to the conventional power inductor to inject a control current for adjusting the permeability of magnetic cores. This has significant merits in controlling the current ripple and enhancing the current handling capability of power inductors, thereby reducing the size of magnetic components and improving the performance. For current values, twice and three times the rated current, the current ripple is reduced by 40.90 % and 36.10 %, respectively. Nonetheless, this device requires a precisely controlled dc-current. As such, a small current controlled, low-power and low-cost buck converter is built to power up the auxiliary winding. To improve the reliability and robustness of the VI, an integrated closed loop control that enables the control of the main converter and the auxiliary converter is also implemented and tested in real time to test the viability of the VI.

Novel Bidirectional Single-phase Single-Stage Isolated AC–DC Converter With PFC for Charging of Electric Vehicles

This paper proposes a novel bidirectional single-phase single-stage ac–dc converter for Electric Vehicle (EV) charging application. AC side of the proposed converter has current-fed half-bridge converter that is connected to the full-bridge converter on secondary side of a high-frequency transformer. Current at the input of the ac side can be regulated to realize power factor correction. The proposed converter achieves Zero Current Switching of primary side switches and zero current turn-ON for secondary side devices throughout the operation without any additional components. This paper also presents novel modulation technique and control algorithm to ensure soft switching throughout the operation range of the converter in both directions of power flow. Design equations are derived to help suitable selection of components for a given specification. Design of the converter, control strategy, and the results are presented for a 1.5-kVA converter for EV charger.

A New High-Voltage Gain Non-Isolated Zero-Current-Switching Bidirectional DC–DC Converter

This paper deals with a new high-voltage-gain zero-current switching bidirectional DC–DC converter for electric vehicles. The hard-switched non-isolated bidirectional converter integrated with auxiliary active switches and resonant elements were designed to attain the zero-current switching turn-off operation in the main IGBTs. This converter has dual characteristics as battery charge (buck) mode and discharge (boost) mode. By individual mode, all the active switches operate under zero-current switching turn-off operation for the minimized turn-off losses. The proposed converter has high voltage gain with reduced turn-off losses when operating in discharge mode and has low output voltage conversion in charge mode. The topology described with the aid of theoretical waveforms were tested using a laboratory prototype 70/300 V, 800 W system functioned under 50 kHz operating frequency.

Design and Simulation of a New ZVT Bi-directional DC-DC Converter for Electric Vehicles

<p>This paper presents a new zero voltage transistion (ZVT) bi-directional DC-DCconverter for energy storage system in DC traction. This bidirectional converter can transfers the power flow from low voltage side to high voltage side and viceversa. The conventional hard-switched non-isolated converter improved with the additional auxiliary cell to obtain zero voltage transition for the IGBTs. The main advantages of this topology are reduced the switching losses and improved the efficiency as well.The main aim of this converter is to achieve the operation of zero voltage transition during the commutation of main switches from off to on by utilizing auxiliary cell, which consist active and passive elements.The boost and buck modes of operations are achieved with the zero voltage transistion, which reduce the IGBTs current stresses and switching losses.This paper mainly describes the operation principles and the evaluation of the simulation results with the aid of Matlab simulations.The obtained results were proved the expected assumptions of the theoretical analysis.</p>

A 3 kW Bidirectional DC-DC Converter for Electric Vehicles

A bidirectional DC-DC converter (BDC) is an indispensable electrical unit for the electric vehicles (EVs). High efficiency, high power density, isolation, light weight and reliability are all essential requirements for BDC. In this paper, a 3 kW BDC for the battery charger of EVs is proposed. The proposed converter consists of a half-bridge structure on the primary side and an isolation transformer and a synchronous rectifier structure on the secondary side. With this topology, minimum number of switching devices are required for bidirectional power flow between the two dc buses of EVs. The easy implementation of the synchronous rectification gives advantages in terms of efficiency, cost and flexibility. The proposed BDC achieves high efficiency when operating in both modes (step-up and step-down). A 3 kW prototype is implemented to verify theoretical analysis and the performance of the proposed converter.

Hybrid Modulation of Bidirectional Three-Phase Dual-Active-Bridge DC Converters for Electric Vehicles

Bidirectional power converters for electric vehicles (EVs) have received much attention recently, due to either grid-supporting requirements or emergent power supplies. This paper proposes a hybrid modulation of the three-phase dual-active bridge (3ΦDAB) converter for EV charging systems. The designed hybrid modulation allows the converter to switch its modulation between phase-shifted and trapezoidal modes to increase the conversion efficiency, even under light-load conditions. The mode transition is realized in a real-time manner according to the charging or discharging current. The operation principle of the converter is analyzed in different modes and thus design considerations of the modulation are derived. A lab-scaled prototype circuit with a 48V/20Ah LiFePO4 battery is established to validate the feasibility and effectiveness.

LLC DC/DC Converter with Input Voltage Balancing Capacitor for Electric Vehicles

This paper presents a new parallel output LLC DC/DC converter for electric vehicle. There are a high voltage battery for the power train of the vehicle and a low voltage battery for the vehicle electric system in the electric vehicle. The new LLC converter with the input voltage compensation is proposed for the high voltage input and the low voltage output DC/DC converter to charge the low voltage battery from the high voltage battery. The proposed circuit has two LLC converters with the series input voltage from the battery for the power train and the parallel output low battery voltage for the vehicle electric system. Also, the input series voltage compensation capacitor is used for balancing the input current in the two LLC converters. The proposed converter has an equal electric stress of the semiconductor parts and the reactive components, high efficiency and good heat dissipation. Features of the proposed circuit are verified with a simulation result.

A Charge Equalizer With a Combination of APWM and PFM Control Based on a Modified Half-Bridge Converter

A charge equalizer with a combination of asymmetrical pulse width modulation and pulse frequency modulation control based on a modified half-bridge converter for electric vehicles is proposed in this paper. The reliability of the charge equalizer can be improved because the split capacitors are not required and the soft switching of power switches can be achieved by the proposed control. In addition, with the proposed rectification, the number of bridge rectifiers at the secondary side of the transformer can be reduced by half, which also cuts the cost and conduction loss by half. The circuit topology, operation analysis, and control strategy of the proposed charge equalizer are described in detail. Finally, the experimental results are provided to verify the feasibility and performance of the proposed charge equalizer.

Design and Control Algorithms for Power Electronic Converters for EV Applications

The power electronic components within Electric Vehicles (EV) need to operate in several important modes. Some modes directly influence safety, while others influence vehicle performance. Given the variety of functions and operational modes required of the power electronics, it needs to meet efficiency requirements to minimize power losses. Another challenge in the control and construction of such systems is the ability to support bidirectional power flow. This paper considers the construction, operation, and feasibility of available converters for electric vehicles with feasible configurations of electrical buses and loads. This paper describes logic and control signals for the converters for different operations conditions based on the efficiency and energy usage bases.

Performance Analysis of Bidirectional DC–DC Converters for Electric Vehicles

This paper presents the performance analysis and comparison of two types of bidirectional dc-dc converters-cascaded buck-boost capacitor in the middle and cascaded buck-boost inductor in the middle for use in plug-in electric and hybrid electric vehicles. The comparison of the two converters is based on device requirements, rating of switches and components, control strategy, and performance. Each of the converter topologies has some advantages over the other in certain aspects. Efficiency analysis has been carried out for specific scenarios in vehicle applications. The simulation and experimental results are provided for both converter types.

Design of a 2.5-kW 400/12-V High-Efficiency DC/DC Converter Using a Novel Synchronous Rectification Control for Electric Vehicles

This paper proposes the design of a 2.5-kW 400/12 V high-efficiency isolated dc/dc converter for electric vehicles. The designed system accommodates the wide-range input voltage (450 V–220 VDC) and output voltage (16 V–6 VDC). An LLC half-bridge topology is adopted as the primary side of the dc/dc converter. For the secondary side, a novel synchronous rectification control (SRC) strategy is developed to switch metal oxide semiconductor field effect transistors (MOSFETs) through accurately tracking the target switching moments. Experimental results were carried out to charge the on-board 12-V battery and validate the proposed control algorithm. The maximum system efficiency is 93.2%. System power loss is also itemized.