Bidirectional EV Charging Cable for Single-Phase Grid Support
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Solution Overview
Problem
Existing charging solutions for electric vehicles, such as wallboxes and emergency charging cables, require complex and expensive power electronics, significant installation effort, and are often inefficient at lower power levels, limiting their accessibility and usability, especially for residential applications and grid support.
Innovation Solution
A portable single-phase charging cable with a lockable plug and integrated bidirectional AC/DC and DC/DC converters, allowing for efficient charging and discharging of vehicle batteries, enabling grid support and emergency power operation, while reducing installation complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wallboxes with three-phase connection and complex power electronics are used, then charging power is high (11-22 kW), but installation effort and cost increase significantly
Solution Approach 1:
The charging system is segmented into portable charging cables with integrated power electronics that can be easily connected to single-phase sockets, versus fixed wallboxes for high-power three-phase charging. This segmentation allows users to choose appropriate charging solutions based on their specific needs and infrastructure availability.
Solution Approach 2:
The patent introduces a portable charging cable as an intermediary solution between the vehicle and the electrical grid, particularly suitable for single-phase connections. This intermediary device bridges the gap between vehicles needing charging and locations with limited electrical infrastructure, without requiring complex wallbox installations.
2Adaptability or versatility
If wallboxes with bidirectional functionality are used, then grid support capability is enabled, but power electronics complexity and cost increase
Solution Approach 1:
The portable charging cable is designed with bidirectional AC/DC and DC/DC converters that enable multiple functions: charging the vehicle from the grid, discharging the vehicle battery to the grid, and providing emergency power supply. This multi-functionality is achieved in a compact, portable form factor rather than requiring separate specialized devices.
Solution Approach 2:
The patent merges the AC/DC conversion functionality and DC/DC conversion functionality into a single integrated portable charging cable. This combination allows the device to handle both grid charging and vehicle-to-grid discharge operations, consolidating what would traditionally require separate power electronic systems.
3Ease of operation
If emergency charging cables with unidirectional converters are used, then portability is achieved, but bidirectional energy flow and grid support are not possible
Solution Approach 1:
The charging cable incorporates dynamically controllable bidirectional converters that can switch between charging mode (AC/DC and DC/DC conversion) and discharging mode (DC/AC and DC/DC conversion). This dynamic capability allows the same portable device to adapt its function based on operational requirements, enabling both charging and grid support operations.
4Ease of operation
If charging operations are started at low power levels, then accessibility is improved, but conversion efficiency drops significantly
Solution Approach 1:
The patent employs advanced power electronic control that optimizes conversion parameters dynamically based on the operating power level. By adjusting conversion ratios, switching frequencies, and control strategies, the system maintains higher efficiency even at lower power levels compared to fixed-parameter converters. The bidirectional DC/DC converter specifically addresses efficiency concerns at partial load conditions.
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
The solution provides a cost-effective, efficient, and safe charging and discharging system that can operate at lower power levels, supporting grid stability and emergency power needs, with improved safety and operational reliability through bidirectional communication and efficient power management.
Implementation Method 1
the charging electronics include a bidirectional AC/DC converter
Implementation Method 2
in addition a first bidirectional DC/DC converter and a second bidirectional DC/DC converter are provided
Data Source
AI summary
A single-phase charging cable for an electric vehicle includes a single-phase mains plug including a charging plug, which can be locked in the electric vehicle, and charging electronics arranged electrically between the mains plug and the charging plug. The charging electronics include a bidirectional AC/DC converter and at least one bidirectional DC/DC converter.