Mohamed O. Badawy

Parallel Power Processing Topology for Solar PV Applications

A high efficiency converter topology for extracting maximum power from a photovoltaic (PV) module to charge standalone storage devices is presented in this paper. A reversed buck-boost converter enabling parallel power processing with a power switch referenced to the common return is the main core of the charging system. Small signal analysis of the proposed charging system is carried out to facilitate the design of a compensator for the maximum power point (MPP) tracking. The simulation and experimental results confirmed the validity of the model, and verified the high efficiency system operation with MPP tracking. The use of the PPP with the split loads is also presented, which would improve the size, efficiency and step down duty ratio of the converters.

Performance Analysis of Bidirectional DC–DC Converters for Electric Vehicles

This paper presents the performance analysis and comparison of two types of bidirectional dc-dc converters-cascaded buck-boost capacitor in the middle and cascaded buck-boost inductor in the middle for use in plug-in electric and hybrid electric vehicles. The comparison of the two converters is based on device requirements, rating of switches and components, control strategy, and performance. Each of the converter topologies has some advantages over the other in certain aspects. Efficiency analysis has been carried out for specific scenarios in vehicle applications. The simulation and experimental results are provided for both converter types.

A Novel Control for a Cascaded Buck–Boost PFC Converter Operating in Discontinuous Capacitor Voltage Mode

This paper presents a new dual-switch control structure for an ac/dc noninverting cascaded buck-boost power factor correction converter. The proposed converter operates at a discontinuous capacitor voltage mode providing an inherent high-power factor and a zero voltage turn-off switching. Additionally, the proposed control structure enables for a nondistorted sinusoidal current for a wide range of output voltage levels. Unlike the conventional methods, a mode detector is not required and consequently there is no hard transition between buck and boost modes. Although both converter switches are controlled, only one feedback control loop is required to obtain the desired power flow at a unity power factor. The principle of operation, theoretical analysis, simulation, and experimental results of a 1.6-kW prototype grid-connected converter are presented. The results confirmed the validity of the proposed system under various operating conditions.

Power Flow Management of a Grid Tied PV-Battery System for Electric Vehicles Charging

The prospective spread of electric vehicles (EV) and plug-in hybrid EV raises the need for fast charging rates. High required charging rates lead to high power demands, which may not be supported by the grid. In this paper, an optimal power flow technique of a PV-battery powered fast EV charging station is presented to continuously minimize the operation cost. The objective is to help the penetration of PV-battery systems into the grid and to support the growing need of fast EV charging. An optimization problem is formulated along with the required constraints and the operating cost function is chosen as a combination of electricity grid prices and the battery degradation cost. In the first stage of the proposed optimization procedure, an offline particle swarm optimization (PSO) is performed as a prediction layer. In the second stage, dynamic programming (DP) is performed as an online reactive management layer. Forecasted system data is utilized in both stages to find the optimal power management solution. In the reactive management layer, the outputs of the PSO are used to limit the available state trajectories used in the DP and, accordingly, improve the system computation time and efficiency. Online error compensation is implemented into the DP and fed back to the prediction layer for necessary prediction adjustments. Simulation and 1 kW prototype experimental results are successfully implemented to validate the system effectiveness and to demonstrate the benefits of using a hybrid grid tied system of PV-battery for fast EVs charging stations.

Performance analysis of bi-directional DC-DC converters for electric vehicles and charging infrastructure

This paper presents the performance analysis and comparison of two different types of bidirectional DC-DC converters - Cascaded Buck-Boost (CBB) and Combined Half-Bridge (CHB) for use in Plug-in EV and HEV. The comparison of the two converters is based on device requirements, rating of switches and elements, control strategy and performance. Each of the converter topologies has some advantages over the other in certain aspects. Feasibility studies are carried for practical applications in specific scenarios. The simulation and experimental results are provided for both converter types to support the theoretical findings.

Design and implementation of a 75 KW mobile charging system for electric vehicles

A mobile charging system (MCS) for Electric vehicles (EVs) is presented in this paper. The designed MCS have 2 MWhr energy storage capacity and capability of charging five EVs simultaneously with individual 75 kW charging rates. The MCS would be rechargeable from the available power substations (3 phase-480v) with 375 KW charging rate. The appropriate modular power interface is designed and implemented between the MCS, batteries of the EVs and the power substations. Experimental validation is presented in this paper to demonstrate the system performance and effectiveness under rapid charging requirements.

Power flow management of a grid tied PV-battery powered fast electric vehicle charging station

The prospective spread of Electric vehicles (EV) and plug-in hybrid electric vehicles arises the need for fast charging rates. High required charging rates lead to high power demands, which may not be supported by the grid. In this paper, an optimal power flow technique of a PV-battery powered fast EV charging station is presented to minimize the operation cost. The objective is to help the penetration of PV-battery systems into the grid to support the growing need for fast charging of EVs. An optimization problem is formulated along with the required constraints and the operating cost function is chosen as a combination of electricity grid prices and the battery degradation cost. In the first stage of the proposed optimization procedure, an offline particle swarm optimization (PSO) is performed as a prediction layer. In the second stage, dynamic programming (DP) is performed as an online reactive management layer. Forecasted system data is utilized in both stages to find the optimal solution for the power management. In the reactive management layer, the outputs of the PSO are used to limit the available state trajectories used in the DP and, accordingly, improve the system computation time and efficiency. Online error compensation is implemented into the DP and fed back to the prediction layer for necessary prediction adjustments. Simulation and experimental results are successfully implemented to validate the effectiveness of the proposed management system.

Reliability and cost analysis of solar photovoltaic and fuel cell based microgrids

Maintaining a reliable operation in microgrids has significant importance. One factor required for the reliable microgrid operation is to keep certain energy reserve without sacrificing the cost for satisfying any load variation. Reliability and cost optimization of photovoltaic and fuel cell based microgrid system is investigated in this paper. A typical residential load is considered in order to introduce an optimal power sharing approach for cost effective and reliable system operation. A nonlinear frequency droop scheme is then applied to achieve the optimization objectives at the intended operating scenarios. The simulation and experimental results are presented to verify the effectiveness of the proposed technique.

A partial power processing of battery/ultra-Capacitor hybrid energy storage system for electric vehicles

A new hybrid energy storage system is proposed in this paper based on partial power processing concept. Unlike the conventional designs, the proposed HESS processes only a portion of the vehicle power through the interfacing DC/DC converter. The new concept reduces the converter losses, enables the full usage of stored energy in the storage units and provides stable DC bus voltage irrespective of the operating conditions. The interfacing converter is only active when there is a need to supply power from the ultra-capacitors (UC). The regenerative braking energy is captured by both the UC, and the battery via the bidirectional converter. The proposed topology is analyzed, simulation and experimental results are presented in the paper to confirm the validity and the effectiveness of the proposed system.

Non-isolated individual MPP trackers for series PV strings through partial current processing technique

Novel individual power extraction topologies through partial current processing (PCP) technique are proposed for series connected photovoltaic panels. In the presented PCP technique only the mismatch currents between the series connected panels are processed. Both of the proposed current fed and voltages fed topologies process the mismatch currents without the need for an isolation transformer. These features increase the system efficiency while decreasing the ratings of the power electronics interface. The simulation and experimental results are presented in this paper to confirm the validity of the proposed configurations, and to verify its effectiveness.