Modular Charging Device for Medium Voltage EV Networks
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Solution Overview
Problem
Existing charging systems for electric vehicles face challenges in efficiently connecting to medium voltage networks, leading to size and cost disadvantages due to the use of network transformers and high losses, as well as risks associated with the balancing of power semiconductors in series connections.
Innovation Solution
A modular charging device that converts medium voltage to suitable power and voltage for electric vehicle charging, comprising phase units with multiple modules, each containing an input unit, inverter unit, transformer unit, and rectifier unit, allowing for galvanic separation and flexible interconnection of modules to adapt to varying charging demands without the need for cost-intensive network transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If network transformers are used to connect charging systems to medium voltage networks, then the system can handle higher power requirements, but the system incurs size disadvantages, cost disadvantages, and high losses
Solution Approach 1:
The patent extracts and eliminates the network transformer from the charging system by directly connecting power semiconductors to the medium voltage network. This removes the source of energy losses, size, and cost associated with transformers while maintaining the ability to handle medium voltage power requirements through proper semiconductor configuration and control.
Solution Approach 2:
The patent changes the operating parameters by using power semiconductors capable of withstanding medium voltage directly, eliminating the need for transformation. This involves selecting semiconductors with appropriate voltage ratings and implementing control strategies that optimize power transfer efficiency without the intermediate transformation step.
2Ease of manufacture
If power semiconductors are connected in series to eliminate network transformers, then cost and size advantages are achieved, but the system requires very high effort for balancing and carries high risk of semiconductor breakdowns
Solution Approach 1:
The patent implements a control system that continuously monitors the voltage distribution across series-connected power semiconductors and actively balances the voltage share of each device. This feedback mechanism prevents overvoltage conditions that could lead to semiconductor breakdown while maintaining the cost and size advantages of the transformerless architecture.
Solution Approach 2:
The patent incorporates protective measures such as snubber circuits, voltage clamping devices, and careful selection of semiconductors with appropriate voltage margins. These protective elements are built into the system design beforehand to cushion against voltage transients and imbalances, preventing semiconductor breakdown before it occurs.
3Productivity
If network transformers are used for medium voltage connection, then higher performance for multiple vehicle charging is achieved, but the system becomes bound to mains frequency causing high losses
Solution Approach 1:
The patent replaces the mechanical/physical transformation system (transformer) with an electronic power conversion system using controllable power semiconductors. This substitution allows for frequency-independent operation, enabling efficient power conversion at any frequency and eliminating the energy losses inherent in transformer-based medium voltage connection.
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 modular design achieves efficient, cost-effective, and loss-minimized power transmission with high power density, enabling flexible adaptation to charging requirements and reducing the risk of semiconductor breakdowns, while allowing for easy expansion or reduction of modules to match charging park size.
Implementation Method 1
at least one converter which converts a voltage from a medium voltage network to a voltage suitable for a charging operation of the electric vehicle energy storage
Implementation Method 2
at least one inverter which converts the converted voltage to an appropriate frequency
Implementation Method 3
at least one transformer which transforms the voltage to a voltage of the charging point
Implementation Method 4
at least one rectifier which converts the current to a direct current
Data Source
Figure 1~2
Figure 3~4
Figure 5~9
AI summary
The present invention relates to a charging device (1) for charging electrical energy storage devices for motor vehicles, comprising a conversion device (2) for converting power drawn from a medium-voltage network (3) into power suitable for charging the energy storage device. The conversion device (2) includes at least one phase unit (4) connected to at least one phase (13) of the medium-voltage network (3), with at least two strands (14, 24), namely at least one strand (14) for a positive component of the phase (13) and at least one strand (24) for a negative component of the phase (13). Each strand (4, 14) is assigned at least one module (5) comprising at least one input unit (6), at least one inverter unit (7), at least one transformer unit (8), at least one rectifier unit (18) associated with the transformer unit (8), and at least one output unit (9).