A Multi-Motor Architecture for Electric Vehicles

This paper proposes an architecture for EVs with three or more electric motors and highlights when adding more motors does not impact the battery state of charge (SOC). The proposed control algorithm optimizes the use of the motors onboard to keep them running in their most efficient regions. Simulation results along with a comparison with other current motors used in EVs is presented in this paper, and further discussion on the results is presented. With this architecture, the powertrain would see a combined efficiency map that incorporates the best operating points of the motors. Therefore, the proposed architecture will allow the EV to operate with a higher range for a given battery capacity

New Power Electronics Converter Interfacing a Hybrid Dc/Ac Microgrid

poster abstractDistributed loads can either be ac or dc. It is also possible to combine ac and dc subgrids to form the hybrid microgrid. The main advantage of the hybrid microgrid is that it has higher efficiency and lesser power conversion. In this work is proposed a new integrated power electronics converter able to connect a Distributed Generation (DG) unit with a hybrid dc/ac microgrid. The main advantage of the proposed circuit is the high level of integration by reducing one switch and drive circuitry. However the proposed circuit maintains the same features of the conventional solution (converter with six switches) such as: (i) bidirectional power flow between dc and ac micro grids, (ii) independent control in both ac and dc parts, and (iii) different operation conditions using a unique power conversion circuit. While proposing this new solution, this work also presents its models as well as an analysis of the converter in terms of its operation and Pulse-Width-Modulation (PWM) strategy. Furthermore, the power flow among ac and dc links and the hybrid microgrid will be demonstrated, highlighting the bidirectional characteristic of the converter. The outcomes of this research will be presented through a set of simulation results obtained by using the PSIM software. In order to demonstrate that this converter could be used successfully in a hybrid ac/dc micro grid environment, different operation modes have been selected, such as ac and dc links demanding energy from the DG (ModeI), dc microgrid demanding energy while the ac link is disconnected (ModeII), ac link demanding energy while the dc link is disconnected (ModeIII), and two modes in which ac and dc microgrids are generating power to the system respectively (Mode IV and V)

Bidirectional DC-DC-AC Three-phase Power Converter

poster abstractThis work proposes a dc-dc-ac three-phase converter in order to interface dc and ac variables allowing a bidirectional power flow. A comprehensive comparison between the proposed and conventional solutions will be addressed highlighting the advantages of the proposed circuit, such as reduced costs and high level of integration. A direct application of this converter is in Vehicle-to-Grid (V2G) system and interfacing dc microgrid with three-phase utility grid. Such power electronics solution guarantees: (i) full controllability at both dc and ac converter sides, (ii) high level of integration with a reduction of one power switch and its drive circuits, (iii) implementation of two functions by using a unique power conversion stage, and (iv) reduction of the capacitor losses. Despite proposing a new power converter solution, this work presents an optimized PWM strategy based on the hybrid PWM concept as well as a suitable control approach

Design of a Highly Efficient Microinverter

This paper proposes a grid-tied single-phase photovoltaic (PV) microinverter consisting of five-level four-switch (5L-4S) DC-AC converter fed by an isolated fly-back DC-DC converter. The microinverter utilizes a split-coil inductor to produce five levels of pulse width modulation (PWM) compared to the three levels of PWM using conventional four-switch topologies. These implementations reduce losses by up to 39% compared to a conventional topology. The results show that the proposed design improves performance throughout the switching frequency spectra with various loads. The theoretical expectations are validated with simulation and experimental results

Energy Conversion Unit with Optimized Waveform Generation

poster abstractThe ever-increasing demand for electrical energy has put pressure on identifying and implementing ways to increase the efficiency of the devices dealing with energy conversion. The power supplies devices able to generate ac voltage from dc one is crucial in automotive and computing industries. Different technologies have been developed to implement power supplies with higher efficiency, such as multilevel and interleaved converters. This paper proposes an energy conversion unit constituted by a single-phase DC-AC converter with five levels at the output converter side. The proposed converter has an optimized relationship between the numbers of levels per number of switches (nL/nS). The proposed five-level four-switch converter has nL/nS=5/4, which is by far the best relationship among the converters proposed in the technical literature. The most important characteristics of the proposed configuration are: (i) reduced number of semiconductor devices, while keeping the high number of levels at the output converter side, (ii) only one DC source without any need to balance capacitor voltages, and (iii) high efficiency. Details regarding the operation of the configuration and modulation strategy are presented, as well as the comparison between the proposed converter and the conventional ones. Simulated results are presented to validate the theoretical expectations

Harmonic Analysis and Practical Implementation of a Two-Phase Microgrid System

This paper analyzes the harmonic contents of a non-linear load connected to a two-phase microgrid system. Although having the same harmonic content as the single-phase power system when supplying a non-linear load under balanced conditions, the two-phase microgrid system presents the following advantages: 1) constant power through the power line at the balanced condition; 2) two voltages i.e., line-to-line and phase voltages, available by using a three wire system; 3) optimized voltage utilization compared to a three-phase system; and 4) a direct connection of both symmetrical two-phase and single-phase electrical machines. This paper presents an approach for analyzing the harmonics of a two-phase non-linear load in a balanced and unbalanced cases. The mathematical model for the symmetrical component of an unbalanced two-phase system has also been presented in this paper. Finally, a practical implementation of the two-phase system has been performed, where different types of loads are connected to the two-phase power line to test the voltage control performance

Alternative Breed of Three-Phase Four-Wire Shunt Compensators based on Cascaded Transformer with Single Dc-link

This paper introduces a new breed of four-wire (4W) multilevel shunt compensator to deal with either harmonic or reactive power compensation. The converter configurations are generalized for K-stages and the main benefits of proposed topologies lie on i) multilevel waveforms generation, ii) single dc-link unit and iii) modular characteristic. The configurations are based on cascaded transformers along with three-phase-bridge (TPB) converters. These converters are directly connected to the transformer primary side. A suitable PWM strategy combined with an appropriate transformer turns ratio guarantees the desirable multilevel output waveforms. The modularity feature provides simple maintenance and makes the proposed shunt active power filters (SAPFs) an attractive solution in comparison with conventional configurations. The configuration model and overall control are addressed, as well. Simulation and experimental results are presented for theoretical validation

Adaptive Rule-Based Energy Management Strategy for a Parallel HEV

This paper proposes an Adaptive Rule-Based Energy Management Strategy (ARBS EMS) for a parallel hybrid electric vehicle (HEV). The aim of the strategy is to facilitate the aftermarket hybridization of medium- and heavy-duty vehicles. ARBS can be deployed online to optimize fuel consumption without any detailed knowledge of the engine efficiency map of the vehicle or the entire duty cycle. The proposed strategy improves upon the established Preliminary Rule-Based Strategy (PRBS), which has been adopted in commercial vehicles, by dynamically adjusting the regions of operations of the engine and the motor. It prevents the engine from operating in highly inefficient regions while reducing the total equivalent fuel consumption of the vehicle. Using an HEV model developed in Simulink®, both the proposed ARBS and the established PRBS strategies are compared over an extended duty cycle consisting of both urban and highway segments. The results show that ARBS can achieve high MPGe with different thresholds for the boundary between the motor region and the engine region. In contrast, PRBS can achieve high MPGe only if this boundary is carefully established from the engine efficiency map. This difference between the two strategies makes the ARBS particularly suitable for aftermarket hybridization where full knowledge of the engine efficiency map may not be available

A Machine Learning Model for Average Fuel Consumption in Heavy Vehicles

This paper advocates a data summarization approach based on distance rather than the traditional time period when developing individualized machine learning models for fuel consumption. This approach is used in conjunction with seven predictors derived from vehicle speed and road grade to produce a highly predictive neural network model for average fuel consumption in heavy vehicles. The proposed model can easily be developed and deployed for each individual vehicle in a fleet in order to optimize fuel consumption over the entire fleet. The predictors of the model are aggregated over fixed window sizes of distance traveled. Different window sizes are evaluated and the results show that a 1 km window is able to predict fuel consumption with a 0.91 coefficient of determination and mean absolute peak-to-peak percent error less than 4% for routes that include both city and highway duty cycle segments.This research was supported in part by Allison Transmission, Inc