Logarithmic ADC Protection Circuit for Automotive Wire Overheating
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Solution Overview
Problem
Existing electronic switching and protection circuits fail to effectively manage current overload scenarios in long wires, leading to potential damage or destruction due to overheating, especially in automotive applications where multiple electric loads are connected, necessitating a solution that can monitor and control load currents efficiently.
Innovation Solution
An electronic circuit comprising an electronic switch, a control circuit with a first protection circuit that includes a logarithmic analog-to-digital converter, a filter, and a comparator, which generates a protection signal based on the current-time characteristic of the load current to drive the switch, thereby preventing overload and protecting the wire from overheating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electronic switch is used without advanced protection circuits, then the device complexity is reduced, but the wire and load are vulnerable to overheating and damage due to current overload
Solution Approach 1:
The logarithmic ADC continuously monitors the load current before dangerous overheating occurs, converting the current signal to a logarithmic digital value that enables early detection of overload conditions. This preliminary monitoring allows the system to take protective action before the wire temperature reaches critical levels, thus improving reliability without requiring overly complex protection mechanisms
Solution Approach 2:
The patent replaces traditional thermal-based protection mechanisms with an electronic monitoring system using logarithmic ADC and digital signal processing. Instead of relying on thermal fuses or mechanical breakers that react after overheating begins, the electronic system detects current anomalies electrically and triggers protective switching, substituting mechanical/thermal protection with more responsive electronic protection
2Measurement precision
If a logarithmic ADC with filtering and comparison circuits is implemented, then the current monitoring precision is improved, but the device complexity increases
Solution Approach 1:
The patent transforms the current monitoring approach by using a logarithmic ADC instead of a linear ADC. This parameter change in the conversion function provides higher precision for detecting current variations in the critical overload range, as the logarithmic scale compresses high current values while expanding low current values, enabling more precise measurement of current changes that indicate impending overload conditions
Solution Approach 2:
The system implements a feedback mechanism where the logarithmic ADC output is continuously filtered and compared against predefined thresholds. The comparison result feeds back to control the electronic switch, creating a closed-loop protection system. This feedback approach enables automatic adjustment and maintains high measurement precision while using standardized circuit blocks, thereby limiting the increase in overall device complexity
3Object-affected harmful factors
If the electronic switch is switched off immediately upon detecting overload, then the wire is protected from damage, but the loss of time occurs before the protection activates
Solution Approach 1:
The logarithmic ADC and filtering circuit continuously monitor the load current in real-time, maintaining a running assessment of current levels and trends. This continuous preliminary monitoring ensures that when an overload condition develops, the system detects it immediately and can switch off the electronic switch without delay, eliminating the time loss associated with detection while still preventing wire damage
Solution Approach 2:
The system applies preliminary anti-action by maintaining readiness to switch off the electronic switch at any moment through continuous monitoring. The predefined thresholds and filtering circuits are pre-configured to recognize overload patterns, so when conditions warrant protection, the switch-off action occurs immediately without detection delay, effectively preventing overheating before it can cause damage
Data Source
AI summary
An embodiment electronic circuit includes an electronic switch comprising a load path, a first protection circuit configured to generate a first protection signal based on a current-time-characteristic of a load current through the load path of the electronic switch, and a drive circuit configured to drive the electronic switch based on the first protection signal. The first protection circuit includes a logarithmic analog-to-digital converter (ADC) configured to receive an ADC input signal representing the load current and to output an ADC output signal that includes a sequence of values such that each of the values represents a respective sample of the ADC input signal, a filter configured to filter the ADC output signal and output a filter output signal, and a comparator circuit configured to generate the first protection signal based on comparing the filter output signal with a predefined threshold.