Abnormal Voltage Detecting Device Using Three-Input Comparator
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Solution Overview
Problem
Conventional voltage monitoring systems in voltage generating apparatuses often incorrectly detect abnormal voltage decreases during the startup period, leading to erroneous interruptions of voltage output and a complex circuit design requiring multiple comparators.
Innovation Solution
A simplified abnormal voltage detecting device using a three-input comparator and a level shift circuit to generate a reduced reference voltage for the startup period, which inhibits output until the voltage exceeds a predetermined threshold, allowing normal operation monitoring after startup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional comparator is used to monitor voltage during startup, then voltage monitoring is enabled, but erroneous abnormality detection occurs due to slow voltage rise
Solution Approach 1:
The patent applies preliminary action by generating a soft-start reference voltage before normal operation begins. This reference voltage starts at a lower level and gradually increases, anticipating the slow rise of monitoring voltage during startup. By preparing this time-dependent reference voltage in advance, the system avoids erroneous abnormality detection during the startup phase while maintaining accurate monitoring throughout operation.
2Measurement precision
If multiple comparators are used to distinguish startup from normal operation, then detection accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent applies universality by designing a single comparator that performs multiple functions: it compares monitoring voltage against both the soft-start reference voltage during startup and the normal reference voltage during operation. The comparator's reference input is dynamically switched between these two reference voltages based on operational state, allowing one component to replace what would traditionally require multiple comparators and control logic.
Solution Approach 2:
The patent merges the startup detection function and normal operation monitoring function into a single integrated comparator circuit. By combining these functions and using a dynamically selected reference voltage, the system eliminates the need for separate comparators and control logic that would be required to distinguish between startup and normal operation phases.
3Reliability
If voltage monitoring is inhibited during startup, then erroneous detection is avoided, but inability to detect actual abnormalities occurs
Solution Approach 1:
The patent applies dynamics by making the reference voltage time-dependent and adaptive to the operational phase. The soft-start reference voltage dynamically adjusts its level during startup to match the expected slow rise of monitoring voltage, then transitions to the normal reference voltage for standard monitoring. This dynamic adaptation allows continuous monitoring without false alarms during startup and full abnormality detection capability during normal operation.
Data Source
AI summary
An abnormal voltage detecting device monitors abnormal decrease in monitoring voltage during a start up period of a voltage generating apparatus. The abnormal voltage detecting device comprises a level shift circuit that generates a reference voltage for a start up period by reducing, in a predetermined amount, voltage from a reference voltage for soft starting, and further comprises a three input comparator that receives a monitoring voltage, a reference voltage Vref, and the reference voltage for the start up period, and that reverses a logical output when the monitoring voltage is lower than the reference voltage Vref and the reference voltage for the start up period. An abnormality detecting signal is delivered when the logical output of the three input comparator is reversed, and operation of an output circuit is inhibited until the reference voltage for the start up period exceeds a predetermined start up determining voltage.