EV Charging Feed-In Unit for Bidirectional Grid Support
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Solution Overview
Problem
Existing electric vehicle charging stations face challenges in efficiently managing large numbers of batteries, requiring high charging capacity and grid connection, especially in distributed settings, and need to support the AC power grid during peak loads.
Innovation Solution
A charging device with a feed-in unit and DC link, incorporating a converter and inverter, allows for bidirectional energy exchange between batteries and the AC grid, supporting reactive power injection and peak load management, using wind turbine feed-in units for efficient energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of batteries are stocked at a charging station to ensure reasonable availability, then the charging capacity must be increased to 2.5 to 5 MW, but this places high demands on the charging equipment and the connection to the power grid
Solution Approach 1:
The charging station is divided into multiple independent charging lines, each with its own power supply unit and converter group. This segmentation allows the system to serve multiple batteries simultaneously with distributed power requirements, reducing the peak power demand on any single grid connection while maintaining high overall availability.
Solution Approach 2:
The power supply units and converter groups are designed to be multi-functional, capable of charging multiple battery types and serving different charging needs. This universality allows the same infrastructure to handle variable power demands efficiently, reducing the need for oversized dedicated power capacity.
2Device complexity
If several accumulator units are connected to a common DC link, then the system complexity is reduced, but the DC link voltage varies depending on the charging or discharging status of the accumulators
Solution Approach 1:
The system accepts and adapts to dynamic DC link voltage variations based on the operational state of connected accumulators. The converter groups are designed to operate across a range of voltage conditions, adjusting their operation to maintain system functionality despite voltage fluctuations caused by varying charge/discharge states.
3Adaptability or versatility
If a converter is designed to convert direct current or voltage from the DC link into alternating current for injection into the AC electrical grid, then the system can support the AC grid, but the converter must handle bidirectional energy flow and reactive power
Solution Approach 1:
The converter groups are designed as multi-functional units that can perform multiple functions: converting DC to AC for grid injection, converting AC to DC from the grid, handling bidirectional energy flow, and managing reactive power compensation. This universal design consolidates what would otherwise require separate specialized equipment into single integrated units.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient charging and discharging of multiple batteries, supports the AC power grid by reducing the need for peak gas-fired power plants, and facilitates widespread grid support even in remote locations.
Implementation Method 1
The feed-in unit (202) includes a converter (208), also called a frequency converter or inverter, which is designed to convert direct current or voltage from the DC link (206) into alternating current for injection into the AC electrical grid (214). The converter (208) is also designed to convert alternating current from the AC grid (214) into direct current and/or voltage for injection into or charging the DC link (206).
Implementation Method 2
The feed-in unit (202) is designed to feed electrical energy into the AC electrical grid (214).
Implementation Method 3
The battery unit (204) is designed to charge and/or discharge an electrical storage device (228).
Data Source
Figure 1
Figure 2
AI summary
The present invention relates to an electric vehicle charging station. The electric vehicle charging station comprises a wind turbine (250) for converting wind energy into electrical energy and a charging device (1) for charging electrical storage devices (28) of electric vehicles. The charging device (1) comprises a feed-in unit (2) for feeding electrical energy into an AC electrical network (14), which includes a DC intermediate circuit (6) and an inverter (8). The electric vehicle charging station further comprises at least one inverter and a battery unit (4) and/or at least one charging port for connecting a battery unit (4). Preferably, at least one electrical storage device (28) is connected to the charging device (1).The present invention further relates to a use of a feed-in unit (2) of a wind power plant (250) and a method for controlling a charging device (1) of an electric vehicle charging station connected to an alternating current network (14).