ABSTRACT
This paper introduces a power management system for a hybrid energy storage system (PMHESS) configuration for urban electric vehicles utilizing a speed control loop. Consequently, the configuration includes two DC/DC interleaved converters that establish a connection between the battery and ultra-capacitors (UCs), thereby ensuring a substantial power capacity. The speed control unit is adaptable and sturdy, considering information from sources other than the vehicle, such as other vehicles or road infrastructure. The study explores incorporating road topography into the control structure to improve hybrid storage performance. Simulation results show that combining lithium batteries with UCs improves the energy source’s performance and reliability. The power management algorithm reduces sudden demands on the battery by considering the slope of the ground. The work proposes energy storage integration for electric vehicles, exploring its benefits through simulations. Overall, the proposed hybrid energy storage system (HESS) demonstrates high efficiency and power for urban electric vehicles. The simulation work is to be done using MATLAB/Simulink.
INTRODUCTION
In densely populated urban regions, battery electric vehicles (BEV) are often considered as a potential remedy for the clean environment as huge harm is being caused by conventional automobiles (internal combustion engine (ICE) vehicles). Pollutants emitted by ICE vehicles pose a significant threat to both human and environmental health. Furthermore, traffic noise can lead to several health problems, including heart disease, disrupted sleep patterns, and tinnitus. Some municipalities have implemented restrictions or bans on the use of ICE cars within city limits to combat poor air quality and excessive noise. Electric vehicle (EV) is one of the practical solutions to address the noise and pollution associated with traditional fuels such as gasoline and diesel. Although BEVs have a shorter range than ICE vehicles, they are well suited for use as city cars, such as for commuters, rental cars, and public transportation vehicles. BEVs also offer the potential for reduced transportation costs due to their excellent energy efficiency. While BEVs have a lower energy cost per kilometer than ICE cars, the cost of battery replacement is a significant factor that needs to be considered into account. This cost may deter more people from using BEVs, highlighting the need for innovative approaches to extend the useful life of batteries. Warsaw University developed an EV significantly designed for navigating in urban areas. Initially, the vehicle is available for rent based on the price and durability factors. To drive a BEV, a suitable motor is to be selected and the selection varies based on the vehicle parameters and the dynamics. Most of the BEV are using brushless DC motors (BLDC) or permanent magnet synchronous motors (PMSM) with outer rotors integrated into wheels. These motors utilize a battery and ultra-capacitor (UC) as hybrid energy storage system (HESS) to provide electric propulsion. The direct drive layout employed in this vehicle is highly efficient and offers excellent potential for a long lifespan, making it a promising option for EV. The gearless design of this vehicle provides improved dependability and reduces noise output. Moreover, the design with fewer mechanical parts lowers the frequency and severity of necessary repairs.
PROBLEM STATEMENT
This research proposes a configuration of the vehicle, where the energy storage systems, namely the battery pack and UC, are interconnected to the common DC bus through two DC/DC interleaved converters. This arrangement enables the hybrid source to be fully operational, facilitating efficient power distribution between the two storage systems and allowing the output voltage of the source to be adjusted using bidirectional converters in a parallel active topology. The PMDC motor, which is situated in the electric vehicle, is energized by DC/DC converters, and is connected to the gearbox and ultimately to the Final drive of the vehicle. The vehicle control unit is responsible for vehicle control, while the energy management (EM) system governs the control of the energy sources.