AC LED Drive Circuit with Voltage-Adaptive Series-Parallel Switching
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Solution Overview
Problem
Existing alternating-current LED drive circuits are limited to single RMS power supply voltage, restricting their application to environments with multiple voltage sources.
Innovation Solution
An alternating-current LED drive circuit with multiple LED strings, each equipped with a conversion switch, a voltage detection unit, and a switching logic control unit that adjusts the connection mode (series or parallel) based on the detected voltage interval, allowing the circuit to adapt to varying alternating-current voltage sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-capacity electrolytic capacitor is used as a power balancing element, then the input power and output power can be balanced, but the service life of the capacitor becomes much shorter than the LED service life
Solution Approach 1:
The patent removes the electrolytic capacitor from the circuit by extracting its power balancing function. Instead of using a capacitor to balance input and output power, the invention directly controls the LED string connection configuration (series/parallel switching) to match the input voltage, eliminating the capacitor entirely and thus achieving unlimited service life matching the LED lifespan.
Solution Approach 2:
The patent replaces the passive energy storage mechanism (capacitor) with an active control mechanism (switching control unit). The switching control unit dynamically reconfigures the LED strings between series and parallel connections based on detected input voltage levels, substituting the mechanical/electrical energy buffering function with a control-based adaptation approach.
2Reliability
If a high-capacity electrolytic capacitor is used as a power balancing element, then the input power and output power can be balanced, but the size and weight of the drive circuit increase
Solution Approach 1:
The patent removes the electrolytic capacitor from the circuit by extracting its power balancing function. Instead of using a capacitor to balance input and output power, the invention directly controls the LED string connection configuration (series/parallel switching) to match the input voltage, eliminating the capacitor entirely and thus reducing size and weight.
3Reliability
If an alternating-current high-voltage LED drive circuit is designed for single RMS power supply voltage, then the circuit can operate at that specific voltage, but it cannot be applied to environments with multiple voltage sources
Solution Approach 1:
The patent implements dynamic adaptability by enabling the LED string connections to switch between series and parallel configurations based on the detected input voltage level. The switching control unit responds to voltage changes by reconfiguring the circuit topology, allowing the same circuit to operate reliably across multiple voltage sources (e.g., 120V and 240V RMS) without requiring separate dedicated circuits for each voltage.
Solution Approach 2:
The patent creates a universal drive circuit that can handle multiple voltage sources through the voltage detection unit and switching control unit. By detecting the input voltage level and automatically adjusting the LED string connection mode, the circuit becomes multi-functional, capable of operating with different RMS voltage power supplies using the same hardware architecture.
Data Source
AI summary
An alternating-current LED drive circuit, comprising a plurality of LED strings connected between an alternating-current voltage source and a ground, any one of the LED strings being correspondingly provided with a conversion switch and one or more LED light sources being connected in series in any one of the LED strings; a voltage detection unit used for detecting a voltage root mean square value of an alternating-current power supply signal in the connected alternating-current voltage source; and a switching logic control unit used for outputting, according to a voltage interval into which the voltage root mean square value detected by the voltage detection unit falls, a conversion control signal corresponding to the voltage interval to each conversion switch to corresponding to each LED string respectively control each conversion switch to perform a corresponding conversion action, the conversion action of each conversion switch enabling all LED strings to be connected in series or in parallel to adapt to the alternating-current voltage source.