Integrated battery charger for electric scooter

The paper deals with a battery charger integrated into the traction hardware of an electric scooter, for recharging the scooter batteries by means of a single-phase AC source. A mechanical switch and a rectifier bridge are the only additional components required to transform the electric scooter powetrain into a PFC battery charger, suitable for current-controlled or voltage-controlled recharge. The AC current is controlled at unitary power factor with no harmonic distortion. Switching harmonics are also drastically reduced by means of phase-interleaving. The battery charge is regulated according to the requests of the Battery Monitor System (BMS) that is embedded into the battery packs. The effectiveness of the integrated battery charger is demonstrated here on an electric scooter with high voltage Li-Ion battery (260V) and DC/DC/AC power conversion scheme. The integrated PFC charger concept is also valid for electric vehicles with AC traction drives based on a direct DC/AC conversion scheme, as demonstrated throughout the paper

An Integral Battery Charger with Power Factor Correction for Electric Scooter

This paper presents an integral battery charger for an electric scooter with high voltage batteries and interior-permanent-magnet motor traction drive. The battery charger is derived from the power hardware of the scooter, with the ac motor drive that operates as three-phase boost rectifier with power factor correction capability. The control of the charger is also integrated into the scooter control firmware that is implemented on a fixed-point DSP controller. Current-controlled or voltage-controlled charge modes are actuated according to the requirements of the battery management system, that is embedded into the battery pack. With respect to previous integrated chargers, the ac current is absorbed at unitary power factor with no harmonic distortion. Moreover, no additional filtering is needed since the pulsewidth modulation ripple is minimized by means of phase interleaving. The feasibility of the integral charger with different ac motors (induction motor, surface-mounted phase modulation motor) is also discussed, by means of a general model purposely developed for three-phase ac machines. The effectiveness of the proposed battery charger is experimentally demonstrated on a prototype electric scooter, equipped with two Li-ion battery packs rated 260 V, 20 A

Integrated battery charger for electric scooter

The paper deals with a battery charger integrated into the traction hardware of an electric scooter, for recharging the scooter batteries by means of a single-phase AC source. A mechanical switch and a rectifier bridge are the only additional components required to transform the electric scooter powetrain into a PFC battery charger, suitable for current-controlled or voltage-controlled recharge. The AC current is controlled at unitary power factor with no harmonic distortion. Switching harmonics are also drastically reduced by means of phase-interleaving. The battery charge is regulated according to the requests of the Battery Monitor System (BMS) that is embedded into the battery packs. The effectiveness of the integrated battery charger is demonstrated here on an electric scooter with high voltage Li-Ion battery (260V) and DC/DC/AC power conversion scheme. The integrated PFC charger concept is also valid for electric vehicles with AC traction drives based on a direct DC/AC conversion scheme, as demonstrated throughout the paper

Design and realization of a smart battery management system

Battery management system (BMS) emerges a decisive system component in battery-powered applications, such as (hybrid) electric vehicles and portable devices. However, due to the inaccurate parameter estimation of aged battery cells and multi-cell batteries, current BMSs cannot control batteries optimally, and therefore affect the usability of products. In this paper, we proposed a smart management system for multi-cell batteries, and discussed the development of our research study in three directions: i) improving the effectiveness of battery monitoring and current sensing, ii) modeling the battery aging process, and iii) designing a self-healing circuit system to compensate performance variations due to aging and other variations.published_or_final_versio

Unified power converters for battery charging and traction drive systems for electric vehicles: cost and performance analysis

Electric vehicles (EVs) are a promising solution to mitigate the emission of greenhouse gases and atmospheric pollution. Although EVs existence spans from more than one century, only in the recent years there has been a considerable development in the electric mobility paradigm. This development is also verified in the operation modes for the EV, giving it an important role in smart grids. Moreover, the implementation of unified power converters for battery charging and traction drive systems is also a key topic about EVs, allowing at the same time a hardware reduction and an increasing in its functionalities. However, no economic studies about the practical feasibility of these unified systems for EVs have been reported in the literature. In this context, this paper presents a cost assessment of unified battery charging and traction drive systems for EVs focusing on practical aspects. An economic comparison is performed between a traditional EV and a unified system in order to attain a cost/performance analysis for the unified power converters that can be used in EVs.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019. This work has been supported by FCT within the Project Scope DAIPESEV – Development of Advanced Integrated Power Electronic Systems for Electric Vehicles: PTDC/EEI-EEE/30382/2017. This work is part of the FCT project 0302836 NORTE-01-0145-FEDER-030283. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency

Integrated system for traction and battery charging of electric vehicles with universal interface to the power grid

This paper proposes an integrated system for traction and battery charging of electric vehicles (EVs) with universal interface to the power grid. In the proposed system, the power electronics converters comprising the traction drive system are also used for the battery charging system, reducing the required hardware, meaning the integrated characteristic of the system. Besides, this interface is universal, since it can be performed with the three main types of power grids, namely: (1) Single-phase AC power grids; (2) Three-phase AC power grids; (3) DC power grids. In these three types of interfaces with the power grid, as well as in the traction drive operation mode, bidirectional operation is possible, framing the integration of this system into an EV in the context of smart grids. Moreover, the proposed system endows an EV with an on-board fast battery charger, whose operation allows either fast or slow battery charging. The main contributes of the proposed system are detailed in the paper, and simulation results are presented in order to attain the feasibility of the proposed system.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT -Fundacao para a Ciencia e Tecnologia within the Project Scope: UID/CEC/00319/2013. This work has been supported by FCT within the Project Scope DAIPESEV - Development of Advanced Integrated Power Electronic Systems for Electric Vehicles: PTDC/EEI-EEE/30382/2017. Mr. Tiago Sousa is supported by the doctoral scholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency. This work is part of the FCT project 0302836 NORTE-01-0145-FEDER-030283

DESIGNING METHOD FOR INTEGRATED BATTERY CHARGERS IN ELECTRICAL VEHICLES

Electrical vehicles often make use of multi-phase induction motors. At the same time, the vehicles have an on-board charger, the power electronics device that converts the ac power from the mains and charges the traction battery. The traction inverter can be integrated with the charger, reducing in this way the component count, weight and cost, while the windings of the ac motor can be used as the inductors required to complete the charger topology, thus saving on passive components, iron and copper. The integrated charger performances depend on the configuration of the stator windings as well as on the topology of the power converter. The objective in charging mode is reaching a high efficiency while keeping the charging-mode electromagnetic torque at zero. In traction mode, the goals include the efficiency and the torque-per-Amps ratio. In order to compare and distinguish between the available topologies and configurations, the paper starts with the analysis of the magnetic field in the air-gap of the electric machine in both charging and traction modes. Based upon that, a novel algorithm is proposed which determines the space-time distribution of the air-gap field, eventually deriving all the relevant pulsating and revolving component of the magnetic field, thus providing the grounds for studying the losses, efficiency and torque pulsations in both charging and traction modes

A V2G Integrated Battery Charger Based on an Open End Winding Multilevel Configuration

A new approach to obtain an integrated battery charger is described in this paper, based on the Asymmetrical Hybrid Multilevel Converter topology. Such a particular open-end winding motor configuration, which has proved to be more efficient than conventional inverter topologies in EV motor drive applications, can be turned in an on-board battery charger only by acting on the control system. Thus, no circuit reconfiguration through electro-mechanical switches is required. Moreover, by introducing a single extra power switch, a bilateral power flow can be managed enabling vehicle to grid operations. The obtained integrated battery charger can be supplied either by a standard ac single-phase grid, either by a dc power source for direct connection to domestic energy resources. The proposed approach enables a new remarkable function to the asymmetrical hybrid multilevel converter at a marginal extra cost, thus mitigating the larger complexity and cost of such an inverter if compared with conventional topologies

Design and Analysis of an On-Board Electric Vehicle Charger for Wide Battery Voltage Range

The scarcity of fossil fuel and the increased pollution leads the use of Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV) instead of conventional Internal Combustion (IC) engine vehicles. An Electric Vehicle requires an on-board charger (OBC) to charge the propulsion battery. The objective of the project work is to design a multifunctional on-board charger that can charge the propulsion battery when the Electric Vehicle (EV) connected to the grid. In this case, the OBC plays an AC-DC converter. The surplus energy of the propulsion battery can be supplied to the grid, in this case, the OBC plays as an inverter. The auxiliary battery can be charged via the propulsion battery when PEV is in driving stage. In this case, the OBC plays like a low voltage DC-DC converter (LDC). An OBC is designed with Boost PFC converter at the first stage to obtain unity power factor with low Total Harmonic Distortion (THD) and a Bi-directional DC-DC converter to regulate the charging voltage and current of the propulsion battery. The battery is a Li-Ion battery with a nominal voltage of 360 V and can be charged from depleted voltage of 320 V to a fully charged condition of 420 V. The function of the second stage DC-DC converter is to charge the battery in a Constant Current and Constant Voltage manner. While in driving condition of the battery the OBC operates as an LDC to charge the Auxiliary battery of the vehicle whose voltage is around 12 V. In LDC operation the Bi-Directional DC-DC converter works in Vehicle to Grid (V2G) mode. A 1KW prototype of multifunctional OBC is designed and simulated in MATLAB/Simulink. The power factor obtained at full load is 0.999 with a THD of 3.65 %. The Battery is charged in A CC mode from 320 V to 420 V with a constant battery current of 2.38 A and the charging is switched into CV mode until the battery current falls below 0.24 A. An LDC is designed to charge a 12 V auxiliary battery with CV mode from the high voltage propulsion batter

Vehicle electrification: technologies, challenges and a global perspective for smart grids

Nowadays, due to economic and climate concerns, the private transportation sector is shifting for the vehicle electrification, mainly supported by electric and hybrid plug-in vehicles. For this new reality, new challenges about operation modes are emerging, demanding a cooperative and dynamic operation with the electrical power grid, guaranteeing a stable integration without omitting the power quality for the grid-side and for the vehicle-side. Besides the operation modes, new attractive and complementary technologies are offered by the vehicle electrification in the context of smart grids, which are valid for both on-board and off-board systems. In this perspective, this book chapter presents a global perspective and deals with challenges for the vehicle electrification, covering the key technologies toward a sustainable future. Among others, the flowing topics are covered: (1) Overview of power electronics structures for battery charging systems, including on-board and off-board systems; (2) State-of-the-art of communication technologies for application in the context of vehicular electrification, smart grids and smart homes; (3) Challenges and opportunities concerning wireless power transfer with bidirectional interface to the electrical grid; (4) Future perspectives about bidirectional power transfer between electric vehicles (vehicle-to-vehicle operation mode); (5) Unified technologies, allowing to combine functionalities of a bidirectional interface with the electrical grid and motor driver based on a single system; and (6) Smart grids and smart homes scenarios and accessible opportunities about operation modes.Fundação para a Ciência e Tecnologia (FCT