AC Voltage Drop Detection Circuit for Sub-Half-Cycle Backup Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing systems fail to detect a drop in AC power supply voltage within a time period of less than half an alternation, leading to delayed activation of energy reserves in electrical equipment, particularly in aircraft systems.
Innovation Solution
A device comprising a full-wave rectifier, comparator, capacitor charging and discharge circuits, and a control circuit to activate energy reserves when the voltage across a capacitor exceeds a predetermined threshold, allowing for rapid detection of voltage drops or total loss in AC power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a simple comparison of voltage to a threshold is used for AC power supply, then the detection circuit is simple, but the detection time cannot be shorter than half the power supply cycle
Solution Approach 1:
The detection circuit is segmented into multiple functional modules: a full-wave rectifier that processes the AC voltage signal, a comparator that compares the rectified voltage with a reference threshold, and a control circuit that triggers the energy reserve. This segmentation allows each module to perform a specific function efficiently, enabling detection within less than half an alternation period while maintaining reasonable circuit complexity.
Solution Approach 2:
A full-wave rectifier is introduced as an intermediary component between the AC power supply and the comparator. The rectifier converts the AC voltage into a unidirectional signal that can be quickly compared against a threshold, enabling faster detection than direct AC voltage comparison while keeping the overall circuit design manageable through modular functionality.
2Reliability
If energy reserves are used to compensate for power supply deficiency, then the power supply reliability is improved, but the device complexity increases due to additional control circuits
Solution Approach 1:
Energy reserves are pre-charged and prepared in advance through a control circuit that monitors power supply voltage. When a voltage drop or total loss is detected, the pre-charged energy reserve is immediately activated to compensate for the deficiency. This preliminary preparation ensures rapid response and improved reliability while minimizing the complexity of continuous monitoring and control mechanisms.
3Loss of time
If detection time is reduced to less than half an alternation period, then the response time to power loss is improved, but the measurement precision requirements increase
Solution Approach 1:
The full-wave rectifier performs preliminary processing of the AC voltage signal by converting it into a unidirectional waveform. This preliminary action allows the subsequent comparator to make rapid threshold comparisons with sufficient precision, enabling detection within less than half an alternation period while maintaining accurate voltage measurement through the rectified signal characteristics.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables detection of voltage drops or total loss in AC power supply within less than half an alternation period, reducing false detections and ensuring timely activation of energy reserves, thus maintaining stable power supply to electrical equipment.
Implementation Method 1
a full-wave rectifier (310) to rectify the AC supply
Implementation Method 2
a capacitor charging circuit (320) to charge the capacitor when the rectified voltage is below the predetermined threshold
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
The invention relates to a device (100) for detecting a voltage drop in an AC power supply (110) delivering electrical energy to an energy converter (130) in order to supply an electrical appliance (140a, 140b, 140c), the device (100) being connected to an electrical energy store (120) in order to supply the energy converter. The device (100) has: - a full-wave rectifier for rectifying the AC power supply, - a comparator that compares a predetermined first voltage with a full-wave rectified voltage, - a circuit for charging a capacitor, for charging the capacitor when the rectified voltage is lower than the predetermined threshold, - a circuit for discharging the capacitor, for discharging the capacitor when the rectified voltage is greater than the predetermined threshold, - a comparator for comparing the voltage across the terminals of the capacitor with a predetermined second voltage, - a circuit for controlling the electrical energy store.