LED Power Adjusting Circuit Zero-Crossing Control
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Solution Overview
Problem
Existing LED power supplies generate significant electromagnetic interference due to high-frequency switching, which affects the normal operation of peripheral electronic and electrical products, and have lower power conversion efficiency compared to switching power supplies, limiting their use in high-power applications.
Innovation Solution
A power adjusting circuit that uses a zero-crossing detecting unit to generate a pulse or square wave signal from a high-frequency AC signal, a signal processing unit to determine adjustment signals based on full-load operation, and a switch unit to control the output, reducing the need for high-frequency switching and thereby minimizing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high-frequency switching mode is used in LED power supply, then power conversion efficiency is improved, but electromagnetic interference increases
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to control the MOS transistor switching at high frequency, creating periodic on-off cycles that achieve efficient power conversion while controlling electromagnetic interference through regulated switching patterns
Solution Approach 2:
The patent implements feedback control by using a controller to dynamically adjust the MOS transistor switching based on feedback signals, maintaining constant current output while optimizing power conversion efficiency and minimizing electromagnetic interference through closed-loop control
2Object-generated harmful factors
If linear power supply is used in LED power supply, then electromagnetic interference is reduced, but power conversion efficiency decreases
Solution Approach 1:
The patent replaces the linear power supply mechanism with a switching power supply system using MOS transistor and PWM control, substituting the continuous linear regulation with high-frequency switching operation to achieve superior power conversion efficiency while managing electromagnetic interference through controlled switching
3Loss of energy
If switching power supply is used in LED power supply, then power conversion efficiency is improved, but device volume is reduced
Solution Approach 1:
The patent uses high-frequency periodic switching action to enable compact component design, where the rapid on-off cycles allow for smaller magnetic components and capacitors, reducing overall device volume while maintaining high power conversion efficiency
Solution Approach 2:
The patent applies dynamics by using a controller to dynamically adjust the MOS transistor switching frequency and duty cycle based on load conditions, enabling the power supply to adapt to varying requirements and optimize both efficiency and size
Data Source
AI summary
A power adjusting circuit, an LED power supply and an LED luminaire. The power adjusting circuit includes: a zero-crossing detecting unit, adapted to generate a zero-crossing detection signal according to an high-frequency signal, wherein the zero-crossing detection signal is a pulse wave or a square wave, and the high-frequency signal is a sine wave or an AC wave; a signal processing unit, adapted to determine a second number of pulses or square waves of the zero-crossing detection signal corresponding to an adjustment signal that is input externally, according to a first number of pulses or square waves of the zero-crossing detection signal corresponding to a full-load operation of a functional device; a counting unit, adapted to generate a switch control signal according to the first number and the second number; and a switch unit, adapted to control an output of the high-frequency signal according to the switch control signal.