Short Circuit Protection for Electronic Computers
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Solution Overview
Problem
Existing engine control computers face challenges in protecting against short circuits, particularly due to the complexity and resource-intensive nature of monitoring current source sensors, which can lead to destruction of the computer during a short circuit event.
Innovation Solution
A device comprising a transistor driving module and a comparator module is used to detect and prevent short circuits independently of the microcontroller's operation, utilizing a high-side or low-side driver integrated circuit to cut power to the sensor and reduce the size and cost of the shunt resistor, thereby improving reaction time and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a microcontroller-based active protection system is used to monitor the sensor, then the computer can detect and respond to short circuits, but the reaction time is too slow (around 100 ms) and extensive software resources are required
Solution Approach 1:
The patent replaces the microcontroller-based software monitoring system with a hardware-based protection circuit. The protection circuit uses a comparator to monitor the voltage across the shunt resistor and a transistor to cut off power to the sensor, eliminating the need for software intervention and achieving near-instantaneous response to short circuits.
Solution Approach 2:
The patent introduces a comparator as an intermediary device between the shunt resistor and the power supply control. The comparator continuously compares the voltage across the shunt resistor with a reference voltage and triggers the transistor to cut off power when a short circuit is detected, providing faster response than direct microcontroller monitoring.
2Reliability
If a high-power shunt resistor is used to support maximum short circuit power, then the computer is protected during short circuits, but the shunt resistor size and cost increase significantly
Solution Approach 1:
The patent implements preliminary protection action by detecting short circuits before they can cause excessive power dissipation in the shunt resistor. The protection circuit monitors the voltage across the shunt resistor and cuts off power to the sensor at the first sign of a short circuit, preventing the need for an oversized shunt resistor designed to handle maximum possible short circuit power.
3Adaptability or versatility
If a two-wire current source sensor is used instead of a three-wire voltage source sensor, then one pin is freed on the computer, but a shunt resistor is required and the detection interface becomes more complex
Solution Approach 1:
The patent merges the detection function with the existing power supply circuitry. The same transistor that controls power to the sensor also serves as the detection mechanism through its base current requirements, and the comparator that monitors shunt voltage is integrated into the existing power management architecture, reducing overall system complexity despite the additional sensing requirements.
Data Source
AI summary
A device for protecting an electronic computer against a short circuit. The electronic computer including a shunt resistor, a first computer pin and being coupled to at least one sensor comprising a first sensor pin and a second sensor pin. Furthermore including a transistor driving module having a first driving pin coupled to a first shunt pin, a second driving pin coupled to a positive power supply, a second shunt pin being coupled firstly to a first sensor pin and secondly to a first comparator pin of a comparator module and designed to no longer supply electric power to the sensor through the first sensor pin when a short circuit is detected at the sensor.