LED Driver Circuit for Flicker-Free Phase-Cut Dimming
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Solution Overview
Problem
Existing LED luminaires with ballast-compatible drivers face high maintenance and energy inefficiency due to the need for constant ballast power consumption and labor-intensive replacement, while AC mains-operable luminaires lack seamless dimming capabilities without flickering.
Innovation Solution
An LED luminaire with a driver comprising a full-wave rectifier, input filter, and electric current bypass circuit, allowing for phase-cut line voltage conversion and stable dimming without flickering by adapting switching frequencies and duty cycles to maintain LED driving currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If AC mains-operable LED luminaire uses phase-cut line voltage from power-line dimmer, then dimming capability is achieved, but flickering occurs due to unstable LED driving current
Solution Approach 1:
The patent introduces an intermediary circuit between the phase-cut line voltage and the LED driver. This circuit includes a holding current path with a resistor and capacitor that mediates the transition from unstable phase-cut voltage to stable LED driving current, eliminating flickering while preserving dimming capability
Solution Approach 2:
The patent changes the electrical parameters by converting the phase-cut line voltage through full-wave rectification to DC voltage, then regulating it through a holding current path that maintains stable current flow to the LED driver, transforming the unstable AC signal into stable DC current for flicker-free operation
2Adaptability or versatility
If ballast-compatible driver is used in LED luminaire, then compatibility with existing ballasts is achieved, but energy efficiency deteriorates due to constant ballast power consumption
Solution Approach 1:
The patent extracts the ballast component from the lighting system by designing an AC mains-operable LED luminaire that directly interfaces with the power line without requiring a ballast. This eliminates the constant power consumption associated with ballast operation while maintaining LED functionality
Solution Approach 2:
The LED driver circuit is designed to be self-sustaining by directly rectifying and regulating the AC mains voltage to provide stable DC current to the LEDs, making the system self-service capable without external ballast assistance, thereby eliminating parasitic power consumption
3Duration of action of stationary object
If replacement of failed ballast is required, then ballast-compatible luminaire can continue operating, but maintenance complexity and labor costs increase
Solution Approach 1:
The patent removes the ballast component entirely from the luminaire design, eliminating the need for ballast replacement maintenance. The integrated AC mains-operable driver handles all power conversion functions, simplifying the system to components with longer operational life and reduced maintenance requirements
Solution Approach 2:
The LED driver circuit performs multiple functions including rectification, filtering, and current regulation within a single integrated unit, replacing the specialized ballast component. This multi-functional design eliminates the need for separate ballast replacement while maintaining luminaire operation
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
The solution enables efficient dimming of LED luminaires without flickering, reduces maintenance costs, and improves compatibility with power-line dimmers, enhancing energy efficiency and operational stability.
Implementation Method 1
The full-wave rectifier is coupled to an external power-line dimmer which is coupled to AC mains and configured to convert a phase-cut line voltage into a first DC voltage
Implementation Method 2
The LED driving circuit can provide a second DC voltage with various driving currents according to various input power levels to drive LED arrays without flickering
Data Source
AI summary
An LED luminaire comprises LED arrays, a full-wave rectifier, an LED driving circuit, and electric current bypass circuit(s). The full-wave rectifier is coupled to an external power-line dimmer which is coupled to the AC mains and configured to convert a phase-cut line voltage into a first DC voltage. With the electric current bypass circuit(s) to partially provide a holding current path to cause the external power-line dimmer to sustain a dimming function, the LED driving circuit can provide a second DC voltage with various driving currents according to various input power levels to drive LED arrays without flickering. By adapting switching frequencies and a duty cycle, the LED driving circuit can regulate the second DC voltage to reach a voltage level equal to or greater than a forward voltage of the LED arrays no matter whether the first DC voltage is higher or lower than the second DC voltage.