EV Charging Device Balancing Three-Phase Grid Load
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Solution Overview
Problem
Conventional single-phase AC charging systems in private households are not suitable for high-speed charging of electric vehicles, as they require higher currents and power, leading to complex changes in the energy distribution grid and potential overloading.
Innovation Solution
A charging device that converts three-phase alternating current from an external AC grid into single-phase alternating current, using a converter device like an AC-to-DC-to-AC converter, allowing for higher currents to be supplied to the vehicle without unevenly loading the AC grid, thus enabling quick-charging without grid modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If single-phase AC charging is used with conventional household connections, then the charging system is simple and compatible with existing infrastructure, but the charging power is limited to 3.7 kW and cannot support high-speed charging
Solution Approach 1:
A converter device is introduced as an intermediary between the three-phase AC grid connection and the single-phase charging output. This converter device converts three-phase AC to single-phase AC while distributing the phase load uniformly across all three line phases, enabling high-power charging (7.4 kW at 32 A) without requiring modifications to the household's energy distribution grid
Solution Approach 2:
The system changes the electrical parameters by converting from three-phase AC input to single-phase AC output with controlled current distribution. The converter device transforms the input three-phase current into a single-phase output while maintaining uniform load distribution across the three line phases, achieving both high power output and grid compatibility
2Productivity
If higher current is supplied for quick-charging, then charging speed increases, but the single-phase line causes uneven phase loading and potential overloading of the AC grid
Solution Approach 1:
The converter device transforms the current distribution parameters by taking three-phase AC input and producing single-phase AC output with uniformly distributed phase loads. This parameter transformation enables high charging currents (32 A for 7.4 kW charging) while maintaining balanced loading across all three line phases, preventing grid overloading and ensuring stable operation
Solution Approach 2:
The converter device acts as a mediator that decouples the high-current single-phase charging demand from the three-phase grid supply. It absorbs the high current demand and redistributes it uniformly across the three-phase system, allowing quick-charging functionality without compromising grid stability or causing uneven phase loading
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 single-phase AC quick-charging of electric vehicles with higher currents, reducing the load on the external AC grid and preventing overloading, while maintaining symmetrical phase loads, thus avoiding faults in the power distribution system.
Implementation Method 1
the converter device comprises an AC-to-DC-to-AC converter (also referred to as DC-link converter), which converts the three-phase alternating current into a direct current and this direct current into a single-phase alternating current
Data Source
AI summary
The invention relates to a charging device for an electric vehicle that can be driven by an electrical energy store. The charging device has a charging interface outside the electric vehicle, which can be fed by a three-phase alternating current from an external three-phase alternating current network. The charging device provides a charging current at the output that can be fed via a charging cable to the electric vehicle in order to charge the electrical energy store. The charging interface comprises a converter device configured to convert the three-phase alternating current into a single-phase alternating current as the charging current, and to distribute a phase load on the conduction phase of the single-phase alternating current substantially uniformly onto the three conduction phases of the three-phase alternating current during operation.