Design and Development of Charging Schemes for Light Electric Vehicles

Abstract

In this research work, the design and implementation of various converter topologies integrated with dual energy sources for charging of light electric vehicles (LEVs) are presented. The topologies are broadly classified as unidirectional and bidirectional DC to DC converters. These converters are additionally classified into non-isolated, isolated, and bridgeless types. This work presents a novel architecture for an on-board charging (OBC) system that integrates dual energy sources, viz., single-phase AC grid and solar PV. The system employs a Modified Single-Ended Primary-Inductor Converter (SEPIC) converter topology to facilitate Light Electric Vehicle (LEV) charging. A diode bridge rectifier is used to convert AC to DC from the AC mains. An improved CC-CV control technique is developed to ensure robust operation of the converter, maintaining unity power factor (UPF) operation. In the event of a grid outage, an integrated solar photovoltaic (PV) system efficiently charges the LEV battery using a Maximum Power Point Tracking (MPPT) converter, adapting to varying environmental conditions. The Modified SEPIC converter manages LEV charging, emphasizing enhanced efficiency, low conduction losses, reduced component count, and high gain. The designed system offers soft-starting features of the BLDC drive in propulsion mode without using any current and voltage sensors on the motor side. The performance of the system is tested by using the MATLAB simulation and validated by a hardware prototype, the results prove the improved performance of the advanced charging methodology by the proposed converter. This work also proposes an efficient configuration for a solar-powered on-board charging system utilizing a coupled inductor and switched capacitor bidirectional high-gain DC to DC converter with Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) operations. The bidirectional power flow capability of an on-board charger (OBC) benefits utilities and enhances the functionality of light electric vehicles (LEVs). The design of an OBC consists of an active front-end converter (AFC) for bidirectional power flow and unity power factor (UPF) operations. A proposed coupled inductor bidirectional high-gain SEPIC converter and a switched-capacitor bidirectional high-gain ZETA converter are designed and developed for the DC-DC stage. The AFC restricts the THD of supply current within the limits specified in international standards. In the event of a grid outage, an integrated solar photovoltaic (PV) system efficiently charges the LEV battery using a Maximum Power Point Tracking (MPPT) converter, adapting to varying environmental conditions. In addition, the brushless DC (BLDC) motor is used as a traction motor in this work due to its unique features, such as high density, low cost, simple control, etc. The presented LEV with a charging system is simulated in the MATLAB/Simulink platform, and real-time validation is performed using the OPAL-RT platform. The results obtained through both the simulation and real-time prototype indicate the effectiveness of the developed charging schemes with the coupled inductor and switched capacitor converter. Moreover, it introduces the design and implementation of a high-efficiency bidirectional isolated integrated DC to DC converter intended for the optimal charging and discharging of Light Electric Vehicle (LEV) batteries, utilizing dual power sources. The proposed system supports both Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) operations, ensuring stable performance even during grid voltage disturbances, including sags, swells, and outages. To enhance the robustness of the controller, an advanced mixed second-order–third-order generalized integrator (IMSTOGI) control algorithm is introduced to facilitate reliable operation of the Active Front-End Converter (AFC) under grid disturbances. During normal grid conditions, the converter ensures unity power factor (UPF) and constant current performance. In the event of a grid outage, an integrated solar photovoltaic (PV) system efficiently charges the LEV battery using a Maximum Power Point Tracking (MPPT) converter, adapting to varying environmental conditions. The functionality and power management strategy of the system are validated through real-time experiments, showcasing its effectiveness, reliability, and potential for seamless integration with the smart grids and renewable energy sources. Both simulation and experimental results from an OPAL-RT prototype support the system’s economic and operational advantages, confirming the efficiency of the proposed advanced charging methodology with the isolated integrated converter. Additionally, this work introduces the design and implementation of a modified bridgeless SEPIC AC to DC converter topology with single-stage operations to facilitate LEV charging. The developed system utilizes two energy sources such as solar PV and single-phase grid. In the event of a grid outage, an integrated solar photovoltaic (PV) system efficiently charges the LEV battery using a Maximum Power Point Tracking (MPPT) converter, adapting to varying environmental conditions. The developed bridgeless converter manages LEV charging, with an emphasis on enhanced efficiency, low conduction losses, reduced component count, and high gain. The designed system offers soft-starting features of the BLDC drive in propulsion mode without using any current and voltage sensors on the motor side. The performance of the system is tested by using the MATLAB simulation and validated by hardware prototype, the results prove the improved performance of the advanced charging methodology by the proposed converter. This research presents an in-depth exploration of advanced DC-to-DC converter architectures integrated with dual power sources, namely solar photovoltaic (PV) systems and single-phase AC grid supply. The proposed solutions, which include modified SEPIC, bridgeless SEPIC, and high-gain bidirectional converters utilizing coupled inductors and switched capacitors, support both unidirectional and bidirectional power transfer—enabling efficient Grid-to-Vehicle (G2V) and Vehicle-to-Grid (V2G) functionality. Advanced control strategies such as Maximum Power Point Tracking (MPPT), Improved Mixed Second-Third Order Generalized Integrator (IMSTOGI), and Constant Current-Constant Voltage (CC-CV) ensure stable and efficient performance under varying grid and environmental conditions. The integration of smart grid capabilities alongside BLDC motor propulsion demonstrates the system’s flexibility. Simulation studies conducted in MATLAB/Simulink, along with real-time validation using the OPAL-RT platform, confirm the reliability, efficiency, and practicality of the proposed converter designs for Light Electric Vehicle (LEV) charging applications.