Full Voltage Segmented Linear LED Drive Circuit with Auto Switchover
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Solution Overview
Problem
Existing LED drive circuits face challenges in achieving flexible compatibility with power factor and reducing Total Harmonic Distortion (THD), particularly when accommodating different voltage supply modes and voltage fluctuations.
Innovation Solution
A full voltage segmented linear constant-current LED drive circuit with auto switchover mode, utilizing a voltage detection and control circuit to manage the series and parallel connection of LED groups, and employing change-over switches and control switches to adjust the connection mode and current based on detected voltage, ensuring efficient power factor and low THD across varying voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LED drive circuit uses fixed series or parallel connection mode, then circuit structure is simple, but cannot accommodate different voltage supply modes and voltage fluctuations
Solution Approach 1:
The patent implements dynamic switching between series and parallel connection modes of LED strings based on detected input voltage levels. The circuit automatically transitions from series connection at high voltage to parallel connection at low voltage, enabling adaptation to different voltage supply modes (120V and 277V) without manual intervention, thus resolving the contradiction between voltage adaptability and circuit complexity
Solution Approach 2:
The circuit changes the connection parameter (series/parallel configuration) of LED strings according to the input voltage parameter. By detecting voltage level and switching the connection mode accordingly, the system maintains optimal operation across different voltage conditions, achieving versatility while managing complexity through automated parameter adjustment
2Speed
If LED drive circuit switches between series and parallel modes manually, then can accommodate different voltages, but response time is slow and cannot dynamically follow voltage fluctuations
Solution Approach 1:
The circuit performs self-adjustment by automatically detecting input voltage levels and switching connection modes without external control signals. The voltage detection circuit monitors the input voltage and triggers appropriate switching actions, enabling the system to self-adapt to voltage fluctuations and achieve fast response through automated operation
Solution Approach 2:
The patent incorporates a voltage detection circuit that continuously monitors the input voltage and provides feedback to the switching control mechanism. This feedback loop enables the circuit to respond in real-time to voltage changes and automatically adjust the LED string configuration, achieving both fast response speed and high automation
3Reliability
If LED drive circuit uses constant current source for each LED independently, then fault isolation is good and flexibility is high, but cost is relatively higher
Solution Approach 1:
The patent segments the LED array into multiple independently controllable strings that can be selectively connected in series or parallel. Each string acts as an independent unit that can be controlled separately, providing fault isolation similar to constant current sources while using a more cost-effective shared constant current source, thus resolving the contradiction between reliability and manufacturing cost
Solution Approach 2:
The shared constant current source serves multiple functions by being able to drive different numbers of LED strings in different connection configurations. This multi-functional design eliminates the need for separate constant current sources for each LED, reducing cost while maintaining the ability to isolate faults through selective string control
Data Source
AI summary
The present invention discloses a full voltage segmented linear constant-current LED drive circuit in an auto switchover mode comprising a minimum of two groups of LEDs in series connection in proper sequence and a voltage detection and control circuit used for detection of an input power voltage from a power source, a positive terminal of each group of LEDs is connected to the power source via a change-over switch, a negative terminal of each group of LEDs is grounded via a control switch; wherein, one group of LEDs comprises a minimum of two LED units in series connection in proper sequence, a negative terminal of each LED unit is grounded via a control switch; the change-over switch and control switch are connected to and controlled by the voltage detection and control circuit to change inter-group series parallel connection mode and ON/OFF of different LED units.