Three-phase Electric Vehicle Research Articles

Experimental investigation on the design of a three-phase power factor corrector utilizing a SEPIC converter

A new configuration for a three-phase electric vehicle (EV) charger based on the Single-Ended Primary Inductor Converter (SEPIC) topology. The proposed charger operates as a power factor correction (PFC) converter, offering both step-up (boost) and step-down (buck) functions, enabling efficient adaptation to different input voltage levels while ensuring a stable DC output. By incorporating closed-loop current control and fast-switching regulation, the system attains unity power factor, which helps to reduce power losses and improve overall power quality. A unique control technique is proposed to regulate input current under unbalanced voltage conditions, ensuring reliable operation and high efficiency even during grid fluctuations. Simulations using MATLAB/Simulink demonstrate that, in unbalanced voltage scenarios, the control method maintain stable input current shaping, highlighting the system’s resilience. The results validate the SEPIC-based EV charger’s ability to consistently deliver efficient charging performance in both balanced and unbalanced voltage conditions, while achieving unity power factor and stable voltage regulation.

Distributed Energy Resource Deployment to Mitigate Adverse Effects of High EV Penetration in Unbalanced Distribution System by Analytical Sensitivity-Based Optimization

The rapid integration of electric vehicles (EVs) into distribution systems in response to environmental concerns poses challenges for power system operators. This article addresses the operational difficulties faced by unbalanced distribution systems (UDS) when incorporating three-phase EV loads. We propose a novel method for supporting EV integration and enhancing UDS operational indicators, including voltage unbalance, bus voltage stability, and bus voltage deviation. Our approach utilizes analytical loss sensitivity index (ALSI)-based meta-heuristic wild horse optimization for the optimal allocation of distributed energy resources (DERs) and capacitor bank during EV load connections. The ALSI is employed to identify potential DER locations, streamlining the computation process and reducing search space. Tested on a modified 123-bus UDS, the proposed method demonstrates a 76.71% reduction in total active power loss and a 96.43% reduction in total voltage deviation. The results underscore the effectiveness and applicability of the proposed approach. While showcasing promising outcomes, the article also discusses the potential limitations and implications for practical implementation.

A decentralized optimization approach to the power management of electric vehicles parking lots

To reduce the transportation sector's environmental impact, a transition to electric mobility is being witnessed worldwide. However, to avoid any issues on the grid, the charging process of electric vehicles (EVs) must be carefully managed. One valid solution to this problem is aggregating EVs and managing their collective charge and discharge. Parking lots equipped with charging stations are likely to become more prevalent in the future. Careful management of such infrastructures is essential to avoid local overloads and to provide flexibility to the electrical grid. In this context, this paper formalizes an optimization model for the optimal power management of a smart PL, with the objective of minimizing the power withdrawn from the grid while considering customers’ needs. The main novelties regard how the PL is modeled and how the solution to the optimization problem is achieved. In fact, as far as the modeling is concerned, both single- and three-phase EVs are considered, and batteries are modeled via a non-linear charging profile. As regards the solution method, an augmented Lagrangian-based decentralized model predictive control technique is proposed. The adopted algorithm has been tested on a smart PL in a Genova Municipality (Italy) and its performance has been evaluated by implementing two different scenarios: in the first one only 5 EVs are considered, while the second one regards a scalability analysis where the number of served EVs is increased to 40. The conducted tests confirm that the proposed algorithm can provide a computationally efficient solution, while preserving an accurate model.

A Three-Phase Electric Vehicle Charger Integrated With Dual-Inverter Drive

Lack of charging stations and long charge times are critical barriers to widespread electric vehicle (EV) adoption. High power off-board charging stations can address these issues but are expensive to implement. This article presents a three-phase EV charger integrated with the dual-inverter drive. Integrated charging can substantially reduce the charging station costs by reusing drivetrain components, such as power electronics and cooling systems, for charging when the EV is parked. The dual-inverter drive allows for significant current ripple reduction throughout the charger. Operation and control of the presented charger are discussed while functionality is experimentally verified with a 10- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$kW$ </tex-math></inline-formula> -rated prototype. The prototype is able to perform constant current, constant voltage (CCCV) charging of two isolated energy storage units (ESUs) from a three-phase grid with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt; 0.99$ </tex-math></inline-formula> power factor. Charging is performed with balanced dc current passing through the dual-inverter’s motor windings to prevent torque generation during charging. The prototype achieves a peak efficiency of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt; 94\%$ </tex-math></inline-formula> while meeting grid current harmonic standards set by International Electrotechnical Commission (IEC)-61000-3-12.

Integrated Electric Vehicle Shunt Current Sensing System for Concurrent Revenue Metering and Detection of DC Injection

Certified electric vehicle power converters can inject DC current into the AC grid if they fail. Verification of DC injection by electric vehicle supply equipment can be a cost-effective extra measure to ensure power quality from a variety of plugged-in electric vehicles. As electric vehicle supply equipment typically performs high-accuracy revenue energy metering, we propose that measurement of AC current and DC injection with a single sensor is the most economically efficient design. This article presents an integrated shunt current sensing system with separation of AC and DC signals for concurrent revenue metering and DC injection detection. It also shows how the combined sensor is integrated into 19.2 kW single-phase electric vehicle supply equipment, and outlines how the design would be extended to 100 kW three-phase electric vehicle supply equipment. The prototype can detect DC injection of ≥400 mA in an AC current up to 80 A in accordance with the IEEE 1547-2018 standard. The prototype can also conduct revenue metering within the 1.0 accuracy class. The prototype does not have high power dissipation at high currents typical for shunt systems. Finally, the prototype is less costly than common electric vehicle supply equipment revenue metering CT systems with the addition of the popular Hall-effect sensor.

Unbalance characteristics of fundamental and harmonic currents of three‐phase electric vehicle battery chargers

Three-phase electric vehicle (EV) battery chargers are expected to not impact the unbalance of distribution networks; moreover, using active power factor correction topologies they are expected to behave like resistive loads not affecting the system harmonic distortion. In this study, unexpected unbalance characteristics of fundamental and harmonic currents of three-phase EV battery chargers are analysed by means of experimental tests performed on two EV cars of different technology. In order to quantify unbalance and harmonic distortion, proper comprehensive indices, in part developed in this study with specific reference to currents, are utilised. The unbalanced current absorbed even under ideal voltage balanced supply conditions by one of the two EV tested is shown and quantified constituting a real-life case study of endogenous unbalance. Then, the influence of voltage unbalance supply conditions on fundamental and harmonic currents is evaluated by means of a proposed testing procedure, obtaining case studies of exogenous unbalance. The experimental results obtained for the two EVs should be extended to a larger set of cars; anyway, they show the need, before moving forward to full grid EV connection, for utilities and for designers to improve the current standard certification process and the control performances of three-phase battery chargers.

Interleaved Isolated Single-Phase PFC Converter Module for Three-Phase EV Charger

This paper presents an interleaved isolated power factor correction (PFC) converter module for three-phase electric vehicle (EV) chargers requiring for wide output voltage ranges. The proposed circuit is comprised of two half-bridge (HB) voltage-fed isolated PFC converters with parallel-input-series -output structure, which is operated in interleaved discontinuous conduction mode (DCM). Due to zero-voltage and zero-current switching (ZV-ZVS) characteristics in the primary side, it is possible to operate IGBTs at a high frequency with several tens of kHz. Also, the voltage ratings of secondary devices can be reduced so that switching devices with low turn-off losses such as MOSFETs are available. The proposed converter has only single voltage loop and the harmonic regulation is accomplished by feed-forward compensation. The feasibility of the proposed PFC module has been verified with a 5 kW prototype.

Black-Box Small-Signal Structure for Single-Phase and Three-Phase Electric Vehicle Battery Chargers

At present, it is safe to say that the future belongs to sustainable technologies. Electric vehicles are one of the most representative sustainable solutions for mobility. Some of the many advantages they offer are a clean operation, a profit gain from a possible power return to the grid in vehicle to grid applications, grid power support, etc. As it is expected, an increase in the production of electric cars, and other battery-based systems, lead to an increment in battery chargers. Therefore, energy distributors must deal with many different schemes in the grid and with the amount of energy demanded from a fleet of cars and other electric vehicles. This paper deals with the modeling of AC/DC battery chargers by identifying the transfer functions in any operating condition without knowing the specific details inside those chargers. This approach is called black-box modeling and the strategy is based on the information provided by the input and output variables of the charger. The research illustrates the flexibility of the model to work with single-phase and three-phase AC/DC chargers which are linked to on-board and off-board charging stations. An extensive set of tests is shown, verifying the accuracy of the proposed models in a wide variety of operating conditions.

Control Strategy for Electric Vehicle Charging Station Power Converters with Active Functions

Based on the assumption that vehicles served by petrol stations will be replaced by Electric Vehicles (EV) in the future, EV public charging station facilities, with off-board fast chargers, will be progressively built. The power demand of these installations is expected to cause great impact on the grid, not only in terms of peak power demanded but also in terms of power quality, because most battery chargers behave as non-linear loads. This paper presents the proposal of a novel comprehensive global control strategy for the power electronic converters associated with bidirectional three-phase EV off-board fast chargers. The Charging Station facility Energy Management System (CS-EMS) sends to each individual fast charger the active and reactive power setpoints. Besides, in case the charger has available capacity, it is assigned to compensate a fraction of the harmonic current demanded by other loads at the charging facility. The proposed approach works well under distorted and unbalanced grid voltages. Its implementation results in improvement in the power quality of each fast charger, which contributes to improvement in the power quality at the charging station facility level, which can even provide ancillary services to the distribution network. Simulation tests are conducted, using a 100 kW power electronic converter model, under different load and grid conditions, to validate the effectiveness and the applicability of the proposed control strategy.

Strategies Comparison for Voltage Unbalance Mitigation in LV Distribution Networks Using EV Chargers

The increasing penetration of Electric Vehicles (EVs) in LV distribution networks can potentially cause voltage quality issues such as voltage unbalance and under-voltage conditions. According to the EV charger characteristics, some strategies can be adopted to mitigate the aforementioned effects. Smart decentralized charging controls seem to be a more practical solution than centralized controls, since there is no need for communication because they rely only on local measurements. The four most relevant decentralized charging strategies, two for single-phase and two for three-phase EV chargers, have been implemented in a typical three-phase four-wire European LV distribution network. Simulations have been carried out for scenarios with single-phase EV chargers, three-phase EV chargers, and a combination of both. Single-phase controls are aimed at under-voltage regulation, while three-phase controls are focused on mitigating voltage unbalance. Results show that the implementation of a decentralized EV charging control is an adequate solution for Distribution System Operators (DSOs) since it improves the reliability and security of the network. Moreover, even though decentralized charging control does not use any communication, the combination of three-phase and single-phase controls is able to mitigate voltage unbalance while preventing the under-voltage condition.

Design of 10kW three-phase EV charger with wide output voltage range based on voltage-fed isolated PFC converter

ABSTRACTThis article presents a design of the three-phase Electric vehicle (EV) charger with a wide-output voltage range. The proposed charger is based on a voltage-fed/isolated power factor correction (PFC) converter followed by a non-isolated DC/DC converter. The three-phase PFC converter come from asymmetrical dual active bridge (ADAB) converter having zero-voltage- and zero-current-switching (ZV-ZCS) operation in the primary side so that a low-cost device such as Insulated gate bipolar junction transistor (IGBT) is available despite of a high switching frequency. Also, since the PFC converter adopts the harmonic modulation technique that can be implemented in a simple equation, all the controls for the three-phase PFC converter and the non-isolated DC/DC converter can be implemented with a simple digital controller by excluding fast current loops for input current harmonic regulation. The feasibility of the proposed charger has been verified with a 10kW prototype.

Virtual Synchronous Motor Based-Control of a Three-Phase Electric Vehicle Off-Board Charger for Providing Fast-Charging Service

This study introduces a three-phase virtual synchronous motor (VSM) control and its possible application for providing fast-charging service from off-board chargers of electric vehicles (EVs). The main circuit of the off-board charger consists of a three-phase voltage source PWM rectifier (VSR) and a resonant LLC zero-voltage-switching converter. In the proposed control approach, VSM-controlled pre-stage VSR emulates the external characteristics of a synchronous motor (SM), simultaneously, droop control based on charging mode in the VSM can satisfy the demand of the EVs constant-current fast-charging; The post-stage DC–DC converter is responsible for stabilizing the DC bus voltage. The feature of this control strategy is that VSM and fast charging control are implemented by the pre-stage converter, which has better coordination. In the MATLAB, the equivalent synchronous grid of the distribution network supplies to the power battery through the off-board charger, and the effectiveness of the presented control is demonstrated by typical working conditions.

Study of an Electric Vehicle Drive Dynamic Testing System with Energy Recovery

To save the test energy of the electric drive vehicle, an electric vehicle drive dynamic testing system, with energy recovery is proposed. The electric vehicle DC/AC power drive can be regulated by a speed control mode and a torque control mode in a three-phase electric vehicle induction motor. The three-phase electric vehicle induction motor is directly coupled with a three-phase load induction motor through a coupler. The load of the DC/AC power drive is also regulated by the torque control mode and the speed control mode to drive the three-phase load induction motor. The three-phase load induction motor is operated in the regenerative braking mode, and the regenerative energy of the load induction motor can be transferred to the utility system by a power regenerative DC/AC inverter that feedbacks the energy to the utility system with a unit power factor. Therefore, the proposed electric drive vehicle dynamic testing system not only achieves the dynamic test function, but saves energy.