Dynamic DC Link Capacitor Configuration for Vehicle Charging
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Solution Overview
Problem
Existing vehicle charging systems face inefficiencies due to the need for overdimensioned DC link capacitors, which are either underutilized in terms of capacitance or voltage rating when switching between single-phase and multi-phase charging, leading to suboptimal performance and complexity.
Innovation Solution
The use of multiple DC link capacitors connected in parallel for single-phase charging and in series for multi-phase charging, with a switch device to adjust their configuration, ensures optimal utilization of capacitance and voltage rating for each charging type.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single DC link capacitor is used for both single-phase and multi-phase charging, then the device complexity is reduced, but the capacitor must be overdimensioned in terms of capacitance or voltage rating, leading to suboptimal performance
Solution Approach 1:
The patent divides the DC link capacitor into multiple separate capacitors (at least two) that can be connected in different configurations. This segmentation allows each capacitor to be optimally sized for specific charging modes, avoiding the need for a single overdimensioned capacitor and improving voltage smoothing performance for both single-phase and multi-phase charging.
Solution Approach 2:
The patent implements a dynamic reconfiguration system where the connection topology of the DC link capacitors changes based on the charging mode. A switch device connects the capacitors in parallel for single-phase charging (to handle higher voltage ripple) and in series for multi-phase charging (to achieve higher voltage rating), optimizing performance for each operational state.
2Quantity of substance
If DC link capacitors are connected in parallel for single-phase charging, then the capacitance is increased to handle higher voltage ripple, but the voltage rating becomes less critical and can be accepted as lower
Solution Approach 1:
The switch device dynamically reconfigures the capacitor connection based on charging mode. For single-phase charging, capacitors are connected in parallel to maximize capacitance and handle the higher voltage ripple characteristic of single-phase rectification, accepting that the voltage rating requirement is lower in this mode.
3Strength
If DC link capacitors are connected in series for multi-phase charging, then the voltage rating is increased to handle higher peak voltages, but the capacitance decreases and is less critical since multi-phase charging produces lower voltage ripple
Solution Approach 1:
The switch device reconfigures the capacitors from parallel to series connection when transitioning from single-phase to multi-phase charging. This dynamic reconfiguration increases the voltage rating to handle the higher peak voltages of multi-phase charging, accepting that the reduced capacitance is acceptable since multi-phase rectification inherently produces lower voltage ripple.
4Adaptability or versatility
If different charging points with different numbers of phases are used, then the adaptability of the vehicle charging system is improved, but the device complexity increases without the ability to reconfigure capacitors
Solution Approach 1:
The patent implements a dynamic reconfiguration system with a switch device that automatically or manually switches the capacitor connection topology based on the detected charging mode. This allows the vehicle charging system to adapt to different charging points (single-phase or multi-phase) while maintaining optimized performance, without requiring different capacitor configurations for different charging scenarios.
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
This approach allows for efficient smoothing of pulsating DC voltage in both single-phase and multi-phase charging scenarios, eliminating the need for overdimensioned capacitors and reducing complexity by optimizing capacitor usage based on the charging mode.
Implementation Method 1
A first DC link capacitor (C1) and a second DC link capacitor (C2) are connected in a first circuit configuration in parallel during single-phase charging in order to smooth a pulsating DC voltage
Data Source
AI summary
An alternating voltage charging device for a vehicle is equipped with a rectifier, a battery terminal, and at least one first DC link capacitor, which is provided between the rectifier and the battery terminal. The charging device includes a switch device, which connects at least one second DC link capacitor to the at least one first DC link capacitor. The switch device interconnects the DC link capacitors in parallel in a first switching state and in series in a second switching state. There is also described a method to be carried out by the charging device.