AC Detection Circuit Voltage Fluctuation
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Solution Overview
Problem
Conventional AC detection circuits are affected by fluctuations in battery voltage, leading to inaccurate power supply state detection and increased design complexity due to dependency on battery voltage for judgment thresholds.
Innovation Solution
An AC detection circuit utilizing a current mirror module with a fixed current ratio, a unidirectional conduction module, and a current comparison module with an oscillator, timer, and current comparator to detect resistance values independently of power supply fluctuations, ensuring reliable power supply state judgment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a battery is used as the power supply for the detection circuit, then the detection circuit can operate independently, but the detection accuracy deteriorates due to battery voltage fluctuations affecting the judgment threshold
Solution Approach 1:
The patent changes the detection parameter from voltage-based comparison to current-based comparison. By using a current mirror circuit to generate a reference current that is a fixed ratio of the detection current, the judgment threshold becomes independent of battery voltage fluctuations. The current comparison module compares currents rather than voltages, eliminating the direct coupling between power supply voltage and detection threshold.
2Device complexity
If conventional voltage-based comparison is used, then the circuit structure is simple, but the design complexity increases due to the need to meet judgment threshold requirements under varying battery voltages
Solution Approach 1:
The patent transitions from voltage parameter detection to current parameter detection. The current mirror circuit provides a fixed current ratio relationship that is independent of voltage variations, simplifying the design constraints. The judgment threshold is now determined by the current ratio in the mirror circuit rather than by voltage divider ratios that must satisfy inequalities under varying supply voltages.
3Ease of operation
If battery voltage fluctuations are not compensated, then the circuit operation is straightforward, but misjudgment of power supply state occurs
Solution Approach 1:
The current mirror circuit provides a feedback mechanism where the reference current is continuously adjusted to maintain a fixed ratio relationship with the detection current. This feedback ensures that the judgment threshold adapts to battery voltage fluctuations automatically, preventing misjudgment while requiring no additional operational steps from the user.
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
The circuit provides stable and accurate detection of power supply states, simplifying design and debugging with a reduced number of components and eliminating the impact of power supply voltage fluctuations on detection thresholds.
Implementation Method 1
a current mirror module, provided with an input end, a first output end and a second output end, the input end of the current mirror module being connected to the power supply, and the value of the current outputted from the first output end of the current mirror module and the value of the current outputted from the second output end of the current mirror module having a fixed ratio
Data Source
AI summary
An AC detection circuit, including a live wire input end and a neutral wire input end; a first diode and a second diode being both Zener diodes and with anodes connected to each other; a first resistor and a second resistor; a rectification module connected to the live wire input end and the neutral wire input end; a power supply for supplying power; a current mirror module with a current value at the first output end and a current value at the second output end having a fixed ratio; a unidirectional conduction module, configured to enable unidirectional conduction of the current from the current mirror module to the first diode; and a current comparison module, including an oscillator, a timer, a current comparator and a reference current source, and configured to compare the current value of the second output end of the current mirror module with a reference current value.