DC Bus Charging Current Limiting for Diode Thermal Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing charging current methods in DC voltage circuits, particularly in frequency converters and DC-to-DC converters, lead to thermal overload and potential damage of diodes due to high charging currents during voltage recovery, necessitating the use of overdimensioned and expensive diodes to handle worst-case scenarios, which is inefficient and constraining user configurations.
Innovation Solution
A method and device that dynamically adjust a variable undervoltage threshold to limit charging currents based on real-time electrical conditions, such as DC voltage, capacitance, and grid impedance, reducing the voltage difference to minimize thermal stress on diodes and allowing for smaller, less expensive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diodes are overdimensioned to handle worst-case charging current scenarios, then reliability of diode operation is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a dynamic undervoltage threshold that automatically adjusts based on the DC voltage level and charging current magnitude. During voltage recovery events, the threshold dynamically lowers to enable charging current limiting, while during normal operation it maintains higher values for efficient charging. This dynamic adaptation eliminates the need for static overdimensioning of diodes.
Solution Approach 2:
The patent changes the operational parameters of the diodes by introducing charging current limiting that modifies the voltage threshold based on current conditions. The undervoltage threshold is transformed from a fixed parameter to a variable parameter that adapts to charging current magnitude, allowing diodes to operate within safe thermal limits without requiring oversized design margins.
2Device complexity
If static undervoltage threshold is used for charging current limiting, then device complexity is reduced, but adaptability to different operational conditions deteriorates
Solution Approach 1:
The patent transforms the static undervoltage threshold into a dynamic parameter that automatically adapts to different operational conditions including voltage recovery events, normal charging, and varying load conditions. The threshold is continuously adjusted based on the relationship between DC voltage and charging current, providing versatile adaptability without complex external control mechanisms.
3Volume of moving object
If charging current is not limited during voltage recovery, then installation space requirements are reduced, but thermal damage risk to diodes increases
Solution Approach 1:
The patent implements a feedback mechanism where the undervoltage threshold is continuously monitored and adjusted based on the actual charging current magnitude and DC voltage level. During voltage recovery events, the system detects the high charging current and automatically lowers the threshold to limit current flow, providing real-time thermal protection without requiring oversized physical components with increased installation space.
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 effectively reduces the risk of thermal damage to diodes and allows for more efficient use of electrical components by adapting to actual operational conditions, reducing the need for oversized diodes and minimizing installation space requirements.
Implementation Method 1
The limit load integral is linked via an ohmic resistance R of the electrical component that is awaiting consideration, in this case the diode as a semiconductor component, in relation to a consumed energy E according to the following formula E=i2t·R. Moreover, the resistance R is temperature-dependent and the consumed energy E leads, as a function of a mass m and a specific heat capacity c of an electrically active zone on the wafer or on the die of the semiconductor component, to a temperature rise AT
Data Source
AI summary
In a charging current method for limiting a charging current in a DC voltage circuit, the charging current is conducted from an electric supply grid into the DC voltage circuit via diodes. A DC voltage of the DC voltage circuit is ascertained and is based on the supply voltage of the electric supply grid. A variable undervoltage threshold on the DC voltage circuit is determined and a limit of the charging current is activated when the DC voltage reaches or falls below the variable undervoltage threshold.