EV Charger DC Voltage Range Extension via Switchable Capacitor Bank
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Solution Overview
Problem
Existing electrical vehicle charging devices face limitations in providing a large voltage range due to component stress and cost considerations, particularly in resonant converter topologies, which are impractical for handling wide voltage variations required by different electrical vehicle battery states.
Innovation Solution
An electrical vehicle charging device with a power converter and transformer, incorporating a full wave rectifier and bi-directional switch, allowing adjustable DC voltage output by splitting output capacitors and using a switch to operate in full bridge or voltage doubler mode, enabling extension of the DC output voltage range without excessive component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If resonant converter modules are used with fixed component ratings (e.g., 500V), then the converter can operate reliably within its rated voltage, but the charging voltage range is limited and currents increase to unacceptable levels when higher voltages are required
Solution Approach 1:
The patent applies dynamics by making the output capacitor configuration adjustable between series and parallel connections. This dynamic reconfiguration allows the charging device to adapt its output voltage range from 0-500V to 0-1000V based on the charging requirements, while keeping component ratings fixed at 500V. The switchable capacitor arrangement enables the system to operate reliably within component stress limits while expanding the usable voltage range.
Solution Approach 2:
The patent changes the electrical parameters of the output stage by switching between series and parallel capacitor configurations. When capacitors are connected in series, the output voltage range extends to 1000V; when connected in parallel, the voltage range is 0-500V. This parameter change allows the same hardware to serve multiple voltage requirements without exceeding component stress limits.
2Adaptability or versatility
If resonant converters are designed to handle wide voltage ranges, then the voltage adaptability improves, but the cost increases significantly due to requiring components to handle wide range of stress
Solution Approach 1:
The patent segments the output capacitor function into multiple identical capacitor units that can be reconfigured. Instead of using one large capacitor rated for 1000V (which would be expensive), the system uses multiple 500V-rated capacitors that can be switched between series and parallel connections. This segmentation allows the system to achieve 1000V capability only when needed, while using cheaper 500V components for the majority of operating conditions.
Solution Approach 2:
The patent makes the output capacitor bank multi-functional by enabling it to serve dual purposes: providing 0-500V output for standard charging and 0-1000V output for fast charging applications. The same physical capacitors perform different voltage functions based on their switching configuration, eliminating the need for separate capacitor sets for different voltage requirements and reducing overall system cost.
3Adaptability or versatility
If the output capacitor is split into at least two output capacitors connected in series via a center tap, then the DC voltage range can be extended to higher levels, but the device complexity increases due to additional switches and control circuitry
Solution Approach 1:
The patent introduces dynamic switching capability to reconfigure the output capacitor bank. A switch connected between the center tap and one end tap allows the system to dynamically change the capacitor configuration from series to parallel connection. This single switch, controlled based on the required DC voltage level, enables the output voltage range to be extended from 0-500V to 0-1000V without requiring complex multi-switch arrangements.
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 allows for flexible DC voltage adjustment to accommodate different electrical vehicle types, extending the voltage range while maintaining component reliability and reducing costs, enabling charging with voltages up to 1000 V or higher.
Implementation Method 1
a full wave rectifier having a first and a secondary input connected to the secondary side and a positive and a negative output
Implementation Method 2
at least two output capacitors connected between respective end taps in series via a center tap and between the positive and the negative output
Implementation Method 3
a transformer having a primary side connected to the output side and a secondary side
Data Source
Figure 1a~2
Figure 3
AI summary
The invention relates to an electrical vehicle charging device for charging an electrical vehicle (1) with a DC voltage, comprising a power converter (2) having an input side (3) adapted for receiving an AC voltage from an AC grid (4) or a DC voltage from a DC grid and an output side (5), a transformer (7) having a primary side (6) connected to the output side (5) and a secondary side (8), a full wave rectifier (10) having a first and a secondary input (9) connected to the secondary side (8) and a positive and a negative output (14), at least two output capacitors (11) connected between respective end taps (12) in series via a center tap (13) and between the positive and a negative output (14), whereby the end taps (12) are adapted for providing the DC voltage to the electrical vehicle (1), and a switch (15) connected in series between the first or the secondary input (9) and the center tap (13), and whereby the electrical vehicle charging device is adapted for closing and/or opening the switch (15) depending on a DC voltage level required for charging the electrical vehicle (1).