Parallel Transistor Load Driving for Wire Breakage Detection
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Solution Overview
Problem
Conventional electrical load driving apparatuses experience reliability issues and frequent transistor degradation due to continuous failure detection during sole-on periods, especially in applications requiring continuous current supply, such as vehicle ignition systems, where current supply is interrupted during wire breakages or transistor open failures.
Innovation Solution
An electrical load driving apparatus with a check period generating mechanism that turns on all current supply transistors in a low current state to detect wire breakages without interrupting the current supply, using a voltage difference threshold to determine wire breakages without overburdening the transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one of the current supply transistors is turned on during each sole-on period for failure detection, then open failures can be detected, but excessive current burden is placed on the transistors
Solution Approach 1:
The system performs failure detection periodically during check periods rather than continuously during the entire current supply period. During check periods, all current supply transistors are turned on to detect open failures, but this high-current state is maintained only briefly. The majority of the time, during the current supply period, only the necessary transistors are active, reducing the overall current burden and energy consumption while still maintaining accurate failure detection capability.
2Measurement precision
If current supply is interrupted during sole-on periods to detect wire breakages, then wire breakage detection is achieved, but the electrical load experiences current supply interruption
Solution Approach 1:
The patent performs wire breakage detection during check periods that occur before the current supply period begins. By detecting wire breakages in advance during the check period, the system can identify faulty current supply wires before they are needed for actual current supply. This preliminary detection allows the control unit to prepare appropriate responses, ensuring that current supply to the electrical load is not interrupted.
Solution Approach 2:
The patent introduces a control unit that acts as an intermediary between the failure detection mechanism and the current supply transistors. The control unit monitors the detection results during check periods and coordinates the switching between check periods and current supply periods. This intermediary ensures that failure detection activities do not directly interrupt current supply to the load, as the control unit can manage the timing and sequencing to maintain continuous current supply.
Data Source
AI summary
The electrical load driving apparatus includes means for alternately lowering the gate voltages of two current supply transistors connected in parallel to each other at regular time intervals, a current being supplied to an electrical load through drain-source paths of both the current supply transistors, and means for detecting wire breakage in two current supply wires in which the current supply transistors are interposed respectively at portions opposite the electrical load with respect to the current supply transistors based on the drain-source voltages of the current supply transistors.