AC Input Voltage Detection Circuit Eliminating Waveform Distortion
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Solution Overview
Problem
Existing alternating current input voltage detection circuits suffer from waveform distortion due to parasitic capacitance, leading to inaccurate detection of average and effective values, zero cross, and abnormalities in alternating current power supplies, especially during light and heavy loads.
Innovation Solution
An alternating current input voltage detection circuit comprising a first and second voltage waveform detection circuit, and a voltage waveform generation circuit that calculates and eliminates waveform distortions, using operational amplifiers and resistances to generate a sinusoidal wave shape voltage detection signal without distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional alternating current input voltage detection circuit is used, then the circuit structure is simple, but waveform distortion occurs due to parasitic capacitance leading to inaccurate detection
Solution Approach 1:
The patent introduces an operational amplifier as an intermediary component to buffer and isolate the detection circuit from the parasitic capacitance effects. The operational amplifier acts as a mediator between the voltage detection point and the measurement system, preventing the parasitic capacitance from causing waveform distortion while maintaining circuit functionality.
Solution Approach 2:
The patent replaces the conventional passive resistance-based detection method with an active operational amplifier-based detection system. This substitution eliminates the waveform distortion caused by parasitic capacitance interaction with resistance, achieving accurate sinusoidal waveform detection without requiring complex compensation circuits.
2Ease of manufacture
If parasitic capacitance is present in the detection circuit, then the circuit is easier to manufacture, but waveform distortion occurs during light and heavy loads
Solution Approach 1:
The operational amplifier serves as a stable intermediary that isolates the detection circuit from load variations. By placing the operational amplifier between the voltage detection point and the measurement system, the circuit maintains stable sinusoidal waveform detection regardless of whether the load is light or heavy, preventing waveform distortion while keeping the circuit manufacturable.
3Measurement precision
If conventional detection methods are used, then the device complexity is low, but accurate detection of average and effective values is compromised
Solution Approach 1:
The patent substitutes the conventional passive detection method with an active operational amplifier-based detection system. This replacement enables accurate detection of voltage waveforms for calculating average and effective values by eliminating the waveform distortion that occurs in conventional circuits, achieving high measurement precision with manageable circuit complexity.
Data Source
AI summary
An alternating current input voltage detection circuit comprises: a first voltage waveform detection circuit that detects a voltage waveform of one alternating current input terminal of the diode rectification circuit, based on a reference potential of the device; a second voltage waveform detection circuit that detects a voltage waveform of the other alternating current input terminal of the diode rectification circuit, based on the reference potential of the device, and a voltage waveform generation circuit that: calculates a first detection voltage waveform, which is output from the first voltage waveform detection circuit, and a second detection voltage waveform, which is output from the second voltage waveform detection circuit; generates a voltage waveform signal, in which waveform distortions generated in the first detection voltage waveform and the second detection voltage waveform are eliminated; and outputs the voltage waveform signal as the voltage detection signal.