Fleet Charging Controller Optimizing Reactive Power and Energy Costs
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Solution Overview
Problem
Current fleet management systems for electrified vehicles (EVs) do not effectively manage charging logistics and expenses, particularly due to the long charging time, limited infrastructure, and the impact of reactive power and power factor on grid connections, which discourages widespread adoption and increases operational costs.
Innovation Solution
A system and method that utilizes a controller to optimize EV charging by monitoring reactive power and power factor, allowing bidirectional power transfer within the fleet, using EV batteries to charge each other or supply power to the grid when grid connection is inefficient, and scheduling charging based on predicted demand and pricing to minimize costs and energy expenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If EV batteries are charged from the power grid, then the fleet can access charging infrastructure, but the reactive power and power factor deteriorate the grid connection efficiency and incur additional charges
Solution Approach 1:
The patent introduces stationary energy storage systems as intermediaries between the power grid and EV batteries. These storage systems absorb reactive power and power factor corrections, mediating the interaction between grid charging and fleet operations to eliminate harmful reactive power effects while maintaining charging accessibility
Solution Approach 2:
The system enables EVs to charge each other through bidirectional power transfer, allowing the fleet to serve its own charging needs without relying on grid infrastructure. This self-service approach eliminates reactive power issues associated with grid connection while maintaining operational flexibility
2Speed
If EVs charge from the power grid during peak demand, then charging speed is fast, but energy costs increase due to demand charges and power factor penalties
Solution Approach 1:
The system performs preliminary charging of EV batteries during off-peak hours when energy costs are lower and grid demand is reduced. Energy storage systems are charged in advance during low-cost periods, allowing fleet vehicles to be dispatched with sufficient charge without incurring peak demand charges
Solution Approach 2:
The charging strategy dynamically adjusts based on real-time grid conditions, energy prices, and fleet requirements. The system flexibly switches between grid charging, stationary storage discharge, and inter-vehicle power transfer to optimize the balance between charging speed and energy cost
3Adaptability or versatility
If the fleet uses bidirectional power transfer between vehicles, then grid dependency is reduced, but individual vehicle battery charge levels must be carefully managed
Solution Approach 1:
The system implements a universal charging architecture where any EV in the fleet can simultaneously function as a power consumer, power supplier, or both. This multi-functional capability allows flexible power distribution across the fleet while maintaining standardized charging protocols and simplified control logic
Data Source
AI summary
A fleet charging method and system include a plurality of chargers and a controller programmed to predict charge demand for fleet vehicles over a predetermined time interval and generate a charging strategy for the predetermined time interval including selecting at least one of a plurality of power sources for the plurality of chargers from at least a utility grid and a subset of fleet vehicles having stored charge capacity exceeding an associated threshold in response to: a predicted power factor of the utility grid during the predetermined time interval; meeting the predicted charge demand for the fleet vehicles; and minimizing a total energy expense for meeting the predicted charge demand.