Pre-Charging Resistor Temperature Estimation for Inrush Current Limiting
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Solution Overview
Problem
Existing methods for limiting inrush current in high-voltage networks, such as those used in hybrid and electric vehicles, face overheating issues with pre-charging resistors due to frequent switching, which can lead to system failures and safety concerns.
Innovation Solution
A method that employs a monitoring unit to record and estimate the temperature of the pre-charging resistor using variables like current, voltage, and switch-on frequency, initiating countermeasures such as warning signals or preventing re-precharge when temperature thresholds are exceeded, without the need for direct temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pre-charging is carried out via a pre-charging resistor during switch-on processes, then inrush current is limited and battery safety is improved, but the pre-charging resistor overheats due to frequent switching
Solution Approach 1:
The monitoring unit performs preliminary assessment of pre-charging requirements by evaluating operating data (current, voltage, temperature, switch-on frequency) before each pre-charging operation. This preliminary action prevents unnecessary pre-charging cycles that would cause overheating, while still ensuring safety when pre-charging is actually needed.
Solution Approach 2:
The system implements feedback control by continuously monitoring operating data and using it to control subsequent pre-charging operations. The monitoring unit provides feedback information about resistor temperature and operating conditions, which determines whether pre-charging should be performed, thereby preventing overheating while maintaining safety.
2Measurement precision
If a temperature sensor is used to measure the temperature of the pre-charging resistor, then temperature monitoring accuracy is improved, but device complexity and cost increase
Solution Approach 1:
Instead of directly measuring resistor temperature with a temperature sensor, the system uses an intermediary approach by monitoring related operating parameters (current, voltage, ambient temperature, switch-on frequency) and calculating temperature indirectly. This intermediary method achieves sufficient monitoring accuracy without adding complex sensing hardware.
Solution Approach 2:
The patent replaces the physical temperature sensor measurement system with an electronic calculation system. By substituting direct thermal measurement with computational estimation based on electrical parameters, the system reduces hardware complexity while maintaining functional equivalence.
3Reliability
If pre-charging is prevented when temperature threshold is exceeded, then resistor overheating is avoided and reliability is improved, but the number of pre-charging operations successful is reduced
Solution Approach 1:
The system dynamically adjusts pre-charging operation availability based on real-time temperature conditions. When temperature thresholds are exceeded, pre-charging is temporarily prevented; when conditions normalize, pre-charging becomes available again. This dynamic approach maintains reliability while maximizing operational success rate.
Solution Approach 2:
The monitoring system periodically reassesses temperature conditions and switches pre-charging availability on and off accordingly. This periodic evaluation ensures that pre-charging operations are only blocked when necessary for safety, allowing high success rates during normal conditions while maintaining reliability during high-temperature periods.
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 enhances safety and reliability by preventing overheating of the pre-charging resistor, thereby reducing the risk of system failures and ensuring continuous operation of electrical systems.
Implementation Method 1
pre-charging is carried out via a pre-charging resistor during a switch-on process, so that an inrush current which flows through a battery and a connected consumer is diminished
Implementation Method 2
the pre-charging resistor is heated up by the high switch-on current. If several switch-on processes are carried out within a short period of time, the temperature model can calculate the self-heating of the pre-charging resistor
Data Source
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AI summary
The invention describes a method for limiting a switch-on current in an electrical system which is supplied with power by a battery (100). During a switch-on process, an electrical load is connected to the electrical system and precharged by means of a precharging resistor (12). A monitoring unit (18) regularly records operating data of at least one variable (S11) which influences a temperature of the precharging resistor (12) and estimates the temperature of the precharging resistor (12) on the basis of said operating data. The invention also describes an apparatus and a battery (100) which are designed to execute the method according to the invention.