DC-Link Capacitor Precharge Using a Boost DC-DC Converter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-voltage power supply systems for electric vehicles require a parallel current path with additional components, space, weight, and cost to charge the DC-link capacitor, which is inefficient and costly.
Innovation Solution
A method that uses a DC-DC converter to charge the DC-link capacitor by determining the voltage difference between the energy source and the DC-link capacitor and driving the DC-DC converter into boost converter mode, eliminating the need for a parallel current path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a parallel current path with precharging resistor is used to charge the DC-link capacitor, then the charging function is achieved and compensation currents are limited, but additional components, space, weight, and costs are required
Solution Approach 1:
The patent merges the precharging function into the existing DC-DC converter by utilizing its bidirectional capability. The DC-DC converter is controlled to operate in boost mode during precharging, eliminating the need for a separate parallel current path with precharging resistor. This combines multiple functions (power conversion and precharging) into a single device, reducing component count while maintaining reliability.
Solution Approach 2:
The DC-DC converter is designed to perform multiple functions: normal power conversion operation and precharging operation. By controlling the converter to operate in boost mode during precharging, the same hardware component serves dual purposes, eliminating the need for dedicated precharging components and reducing overall system complexity.
2Reliability
If a parallel current path with precharging resistor is used to charge the DC-link capacitor, then the charging function is achieved, but additional space and weight are required
Solution Approach 1:
The precharging function is merged into the existing DC-DC converter structure. By utilizing the converter's bidirectional capability and controlling it in boost mode during precharging, the patent eliminates the need for separate precharging components such as resistors and switches, thereby reducing the overall system weight while maintaining the charging function.
3Reliability
If a parallel current path with precharging resistor is used to charge the DC-link capacitor, then the charging function is achieved, but additional costs are incurred
Solution Approach 1:
The patent combines the precharging function with the existing DC-DC converter, eliminating the need for additional components such as precharging resistors, switches, and associated control circuitry. This reduction in component count directly lowers manufacturing costs while maintaining the essential charging function through bidirectional control of the converter.
Solution Approach 2:
By designing the DC-DC converter to perform both normal power conversion and precharging functions, the patent eliminates the need for dedicated precharging components. This multi-functionality approach reduces the bill of materials and assembly costs, making the system more cost-effective to manufacture while maintaining reliability.
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 method reduces costs and complexity by eliminating the need for additional components, while ensuring safe and efficient charging of the DC-link capacitor, thereby preventing impermissibly high compensation currents.
Implementation Method 1
The DC-DC converter is driven into a boost converter operating mode for charging the DC-link capacitor
Data Source
AI summary
The invention relates to a method (100) for charging an intermediate circuit capacitor (210) in a high-voltage network (205). The high-voltage network can be connected to a power source (220) by means of at least one switch (230) and is coupled to a low-voltage network (295) by means of a DC voltage converter (250). The method comprises the steps: determining (110) a first voltage (U1) across the power source (220); determining (120) a second voltage (U2) across the intermediate circuit capacitor (210); determining (130) a first difference (D1) between the first voltage (U1) and the second voltage (U2); switching (140) the DC voltage converter (250) to the boost converter operating mode to charge the intermediate circuit capacitor (210) according to the determined first difference (D1).