AC Peak Sampling Circuit Using Delayed Rectified Signal Comparison
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Solution Overview
Problem
Existing peak sampling methods for AC voltage, especially those without digital elements, are not accurate in capturing varying peak values cycle by cycle, leading to inefficiencies in AC voltage measurement and control in switching converters.
Innovation Solution
A peak sample circuit comprising a rectifier, delay circuit, and comparison circuit that rectifies AC voltage, generates a delayed signal, and compares it to determine a square signal for precise peak sampling, enabling accurate capture of AC voltage peaks without digital processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a diode and capacitor are used for peak sampling without digital elements, then the device complexity is reduced, but the measurement precision of peak voltage deteriorates due to propagation delays and inability to accurately capture varying peak values
Solution Approach 1:
The circuit is divided into separate functional modules: rectifier circuit for voltage rectification, delay circuit for timing control, comparison circuit for peak detection, and sampling circuit for voltage capture. Each module performs a specific function, achieving accurate peak sampling without complex digital processing while maintaining clear signal processing stages
Solution Approach 2:
The delay circuit generates a delayed version of the rectified voltage signal in advance, which is then compared with the original rectified signal to generate a square wave that triggers sampling at the precise peak moment. This preliminary timing preparation eliminates propagation delays and ensures accurate peak capture
2Measurement precision
If digital processors and memories are used for peak sampling, then the measurement precision of peak voltage is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces digital processing systems with an all-analog circuit implementation. The rectifier, delay circuit, comparator, and sampling switches are all implemented using analog electronic components, eliminating the need for digital processors and memories while achieving equivalent or superior peak detection accuracy
Solution Approach 2:
The comparison circuit acts as an intermediary between the rectified voltage signal and the sampling circuit. By comparing the rectified signal with its delayed version, it generates a precise trigger signal that controls the sampling switch, enabling accurate peak capture without direct digital intervention
3Ease of operation
If simple diode-capacitor peak sampling is used, then the ease of operation is improved, but the reliability of switching converter control deteriorates due to inaccurate peak detection under varying input conditions
Solution Approach 1:
The delay circuit creates a feedback mechanism by comparing the past state of the rectified voltage with its current state. This feedback through the comparison circuit ensures that sampling occurs precisely at peak moments, maintaining reliable control of the switching converter even when input voltage conditions vary
Solution Approach 2:
The circuit dynamically adapts to varying input voltage conditions by continuously comparing the rectified signal with its delayed version. The delay time and comparison threshold automatically adjust to capture peaks regardless of voltage magnitude or frequency variations, ensuring reliable operation across different operating conditions
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
This solution provides a simple and accurate method for determining peak AC voltage values, reducing overshoot in switching converters and improving the control of AC voltage-based systems by ensuring precise sampling of peak values.
Implementation Method 1
The rectifier is configured to receive an AC voltage, and to provide a rectified signal by rectifying the AC voltage
Implementation Method 2
The comparison circuit is configured to generate a square signal based on the comparison of the rectified signal and the delayed rectified signal
Data Source
AI summary
A peak sample circuit for AC voltage, including: a rectifier coupled to receive an AC voltage and to rectify the AC voltage to generate a rectified signal; a delay circuit coupled to receive the rectified signal and to delay the rectified signal to generate a delayed rectified signal; a comparison circuit coupled to receive the delayed rectified signal and to generate a square signal based on the comparison of the rectified signal and the delayed rectified signal; and a sample output circuit coupled to receive the rectified signal, wherein the sample output circuit samples the rectified signal under the control of the square signal and provides a peak sample signal representative of the peak value of the AC voltage.