Vehicular Power Controller Backup Circuit for Microprocessor Failure
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Solution Overview
Problem
Existing vehicular power control systems using semiconductor switching elements fail to prevent battery exhaustion and provide clear indication of abnormalities when the microprocessor is unable to synchronize power supply switching with switch operations, leading to potential battery drain and difficulty in recognizing vehicle malfunctions.
Innovation Solution
A vehicular power source controller that includes a semiconductor switching element, a control unit for switching power based on a switch signal, and a backup control circuit that independently turns on/off the semiconductor switching element when an abnormal fuse state is detected, and synchronizes with an ignition switch signal during microprocessor abnormalities to prevent power supply to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the microprocessor controls the semiconductor switching element based on switch signals, then the power supply switching function is improved, but the reliability deteriorates when the microprocessor malfunctions causing battery exhaustion
Solution Approach 1:
The control system is segmented into two independent parts: a microprocessor-based control unit for normal operation and a backup control circuit for abnormal conditions. The backup control circuit includes separate analog circuits for each load that can independently respond to switch signals without relying on the microprocessor, ensuring continued reliability when the microprocessor malfunctions.
Solution Approach 2:
The backup control circuit is pre-configured with analog circuits for each load that are ready to take over control immediately when microprocessor malfunction is detected. The system preliminarily establishes independent control paths that can activate without delay, preventing battery exhaustion by ensuring power supply interruption capability is always available.
2Extent of automation
If the microprocessor controls power supply switching, then automation is improved, but the ease of detecting abnormality deteriorates when the microprocessor fails
Solution Approach 1:
The system uses indicator lights (different colors or states) to visually indicate the operational status of the power supply control. When the backup control circuit is activated due to microprocessor malfunction, the indicator changes to alert the operator, providing clear visual feedback about the abnormal state without requiring complex diagnostic equipment.
Solution Approach 2:
An indicator circuit serves as an intermediary between the control system and the operator. This intermediary provides direct visual information about the system state, bridging the gap between the automated control processes and human awareness, making abnormalities easily detectable without requiring the operator to understand complex control logic.
3Device complexity
If a single control unit is used for power supply control, then device complexity is reduced, but the reliability deteriorates when the control unit malfunctions
Solution Approach 1:
The control system is divided into a microprocessor-based control unit and multiple independent analog control circuits, one for each load. This segmentation allows the system to maintain simplicity at the circuit level while achieving redundancy at the system level, improving reliability without significantly increasing overall complexity.
Solution Approach 2:
Each load has its own dedicated analog control circuit with specific characteristics tailored to that load's requirements. This local quality approach ensures that each control path is optimized for its specific function while maintaining independence, so that a malfunction in one load's control circuit does not affect other loads.
Data Source
Figure 1
Figure 2~3
AI summary
A vehicular power source controller (1) is designed so that when there is abnormal action in a microprocessor (11) and an abnormal fuse state cannot be determined from the current of a load (5) detected by a current sensor circuit (15), power supply to the load (5) cannot be turned on and off by the operation of a combination switch (3) corresponding to the load (5), but can be turned on and off by the operation of an ignition switch (7). It is thereby possible to prevent continuing power supply to the load (5) when the combination switch (3) is turned on during the abnormal action of the microprocessor (11), and battery exhaustion can be suppressed. Power supply to the load (5) cannot be turned on and off by the operation of the combination switch (3) during the abnormal action of the microprocessor (11), and an operator is easily made aware of the abnormal action of the microprocessor (11).