Zero-Cross Detection Circuit Power Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for detecting zero-cross points of an AC voltage using photocouplers consume significant power, necessitating a technology that reduces power consumption while maintaining detection reliability.
Innovation Solution
A power supply system that includes a low-capacity power supply circuit with a smoothing capacitor and a signal generating circuit to produce a zero-cross detection signal, allowing for efficient detection of zero-cross points by determining the feasibility of the detection process based on the voltage value of the zero-cross detection signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photocouplers are used to detect zero-cross points, then detection reliability is maintained, but power consumption increases
Solution Approach 1:
The patent extracts the zero-cross detection function from the high-power photocoupler circuit and implements it separately using a low-power dedicated detection circuit with capacitor C3 and comparison circuit. This separates the detection function from the main power supply circuit, allowing independent optimization of power consumption while maintaining detection reliability.
Solution Approach 2:
The patent changes the operating parameters of the detection circuit by using a small-capacity capacitor C3 (0.1μF to 10μF) instead of large capacitors, and by using a comparison circuit that operates at lower power levels. This parameter change enables the detection circuit to consume significantly less power while maintaining accurate zero-cross detection capability.
2Use of energy by moving object
If small-capacity capacitors are used in the power supply circuit, then power consumption is reduced, but voltage smoothing capability deteriorates
Solution Approach 1:
The patent segments the capacitor functions into two distinct roles: large-capacity capacitors (C1, C2) for bulk energy storage and voltage smoothing in the main power supply circuit, and a small-capacity capacitor (C3) dedicated to zero-cross detection timing. This segmentation allows each capacitor to be optimized for its specific function, maintaining voltage stability while reducing overall power consumption.
Solution Approach 2:
The patent introduces a comparison circuit as an intermediary between the small-capacity capacitor C3 and the control unit. This comparison circuit buffers and conditions the voltage signal from C3, ensuring that the small capacitor's voltage fluctuations do not directly affect system stability while still enabling accurate zero-cross detection through voltage threshold comparison.
3Measurement precision
If dedicated zero-cross detection circuit is added, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent designs the small-capacity capacitor C3 to serve multiple functions: it acts as a timing element for zero-cross detection, a signal source for the comparison circuit, and a power-saving mechanism by discharging during non-detection periods. This multi-functionality reduces the need for additional dedicated components, thereby limiting the increase in device complexity while maintaining high detection accuracy.
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 approach enables further reduction in power consumption while maintaining the reliability of zero-cross point detection, allowing for accurate and efficient detection processes.
Implementation Method 1
a rectifier circuit that is electrically connected between the second electrode of the first capacitor and the second electrode of the second capacitor, and is configured to rectify an AC voltage applied between the first and second capacitors
Implementation Method 2
a smoothing capacitor that is connected at a subsequent stage of the rectifier circuit and is configured to smooth the AC voltage
Implementation Method 3
a signal generating circuit that is connected to the smoothing capacitor, and is configured to generate a zero-cross detection signal corresponding to zero-cross points of the AC power supply based on a rectified current flowing in the smoothing capacitor
Data Source
AI summary
A power supply system includes: a switching power supply configured to rectify and smooth an AC voltage of an AC power supply to generate a predetermined DC voltage; a low-capacity power supply circuit that generates a zero-cross detection signal corresponding to zero-cross points of the AC power supply based on a rectified current flowing in a smoothing capacitor; and a controller configured to receive the zero-cross detection signal from the signal generating circuit and perform a determining process of determining whether it is possible to perform detection process of the zero-cross points based on a voltage value of the zero-cross detection signal. If the control unit determines that it is possible to perform the detection process of the zero-cross points, the control unit performs a zero-cross point detecting process of detecting the zero-cross points based on the zero-cross detection signal.