Multi-mode dimming circuit for low ripple wide range control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional dimming circuits fail to achieve a wide dimming range while maintaining low output current ripple, which is essential for applications like high-speed camera lighting, due to limitations in controlling output current and introducing power frequency ripple.
Innovation Solution
A multi-mode dimming control method that operates in various modes, including first, second, and third dimming modes, where control signals and peak current references are generated and managed differently to control the output current, allowing for a wide dimming range and low output current ripple by adjusting peak current references and turn-off times of the main switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional output feedback voltage control is used, then the control is simple, but power frequency ripple is introduced and dimming depth cannot be achieved
Solution Approach 1:
The patent segments the dimming control into three distinct modes (peak current reference control, turn-off time control, and chopped peak current reference control), each handling different dimming ranges. This segmentation allows the system to avoid power frequency ripple by not using feedback voltage control, while still maintaining ease of operation through automated mode selection based on the dimming signal.
Solution Approach 2:
The patent changes the control parameter from output feedback voltage to peak current reference, turn-off time, or chopped peak current reference depending on the operating mode. This parameter change eliminates the introduction of power frequency ripple while maintaining simple control through the controller's internal logic that automatically selects the appropriate parameter based on the dimming signal level.
2Object-generated harmful factors
If peak current reference control is used to achieve lower power frequency ripple, then output current ripple is reduced, but peak current reference error increases making dimming range insufficient
Solution Approach 1:
The patent implements dynamic control by automatically switching between three different control modes based on the dimming signal level. The controller dynamically adjusts which control parameter (peak current reference, turn-off time, or chopped peak current reference) is used, allowing the system to maintain low output current ripple across the entire dimming range from 100% to 0.1% without the peak current reference error limiting the dimming range.
Solution Approach 2:
The patent employs periodic chopped peak current reference control in the third dimming mode, where the peak current reference is periodically chopped to achieve deep dimming levels. This periodic action allows the system to extend the dimming range to 0.1% while maintaining low output current ripple, overcoming the limitation of continuous peak current reference control.
3Device complexity
If a single control mode is used, then the control logic is simple, but the dimming range cannot cover both high and low current requirements
Solution Approach 1:
The patent creates a universal dimming control system that can operate in three different modes depending on the application requirements. The controller is designed to universally handle both high current (100% to 30%) and low current (30% to 0.1%) dimming ranges by automatically selecting the appropriate control mode, making the system adaptable to various lighting conditions without requiring separate control circuits for different dimming ranges.
Data Source
AI summary
The present disclosure provides a multi-mode dimming control method and a dimming circuit. The multi-mode current control method includes: receiving a dimming signal, and controlling the dimming circuit to be operated in a plurality of modes in an arbitrary order according to the dimming signal, wherein the plurality of modes include any two or all of a first dimming mode, a second dimming mode, and a third dimming mode. Also, the dimming circuit can be operated in different combinations of different modes according to actual needs, so that the requirements of a wide dimming range and a low output current ripple can be realized.