Semiconductor Switch Control Device for Fast Over-Current Protection
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Solution Overview
Problem
Conventional semiconductor-switch control devices are slow to detect over-currents, which can lead to inadequate protection of circuits in electric vehicles and hybrid electric vehicles.
Innovation Solution
A semiconductor-switch control device that includes a semiconductor switch, a determination unit to detect over-currents based on digital signals from the load current or voltage, and a detector that can also identify over-currents through analog processing without digital conversion, allowing for immediate interruption of the current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If over-current is detected by microcomputer using digital signal processing, then measurement precision is improved, but response speed deteriorates
Solution Approach 1:
The detection function is segmented into two independent paths: an analog detection path for immediate response and a digital determination path for accurate measurement. The analog detector processes signals directly without A/D conversion for speed, while the determination unit performs precise digital analysis when needed.
Solution Approach 2:
A detection signal acts as an intermediary between the analog detector and the drive unit. When the analog detector identifies an over-current condition, it generates a detection signal that can immediately trigger the drive unit to interrupt the semiconductor switch, bypassing the slower digital processing path.
2Measurement precision
If analog signal is converted to digital signal for determination, then measurement precision is improved, but response time increases
Solution Approach 1:
The signal processing is divided into two segments: analog processing for time-critical detection and digital processing for precision measurement. The analog detector handles immediate over-current detection without conversion, while the determination unit performs precise digital measurement when time permits.
Solution Approach 2:
The system performs partial digital conversion only when necessary for precise determination, rather than converting all signals. The analog detector provides sufficient detection capability for immediate response without the overhead of complete A/D conversion and digital processing.
Data Source
AI summary
A semiconductor-switch control device includes a controller that detects an analog signal of a load current, converts the detected analog signal into a digital signal, and determines an over-current based on the converted digital signal; a short circuit detector that detects an analog signal of a load voltage, and detects an over-current based on the analog signal without converting the detected analog signal into a digital signal; and a drive unit that drives an FET based on a determination result of the over-current determined by the controller or a detection result of the over-current detected by the short circuit detector.