LED Driving Circuit Power Factor Correction via Inductor Timing
Solution Overview
Problem
Current LED driving circuits face limitations in achieving high power factor correction and stabilized current output due to design complexity, response speed issues, and reliance on phase signals, sample points, and digital-to-analog converter response, which complicates control and protection mechanisms.
Innovation Solution
The proposed LED driving circuit incorporates a power factor correction (PFC) circuit with an inductor, switch, current detection circuit, and time detection circuit, along with a driving controller that uses inductor current and energy discharging time information to control the switch, enabling efficient power factor correction and over-current protection without the need for complex phase sensing or high sample points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital control with phase sensing and sines table is used for PFC and current control, then power factor correction and current stabilization are achieved, but design complexity increases due to limitations in phase signal, sample points, and DAC response speed
Solution Approach 1:
The patent extracts and removes the complex digital control components (phase sensing, sines table, DAC) from the control system. Instead of using digital control with multiple sample points and phase signal processing, the invention employs a simplified control approach that directly monitors inductor current and switch timing, eliminating the need for complex digital-to-analog conversion and phase synchronization while maintaining current stabilization and power factor correction functionality
Solution Approach 2:
The patent inverts the conventional control approach by not using phase-locked loop or synchronous rectification methods. Instead of locking to the input voltage phase and deriving control signals from it, the invention uses independent timing control based on switch on/off events and inductor current measurement, fundamentally reversing the traditional control paradigm to achieve simpler design with comparable or superior performance
2Measurement precision
If digital control with multiple sample points and DAC is used, then current control precision is improved, but response speed decreases due to digital processing limitations
Solution Approach 1:
The patent replaces the digital mechanical system (DAC conversion, sequential sample point processing) with a direct analog measurement and timing-based control system. By using current detection circuitry that directly measures inductor current and timing circuits that track switch events, the system eliminates digital conversion delays and achieves both high precision and fast response simultaneously, as the measurement and control are performed in the analog domain without sequential digital processing steps
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
This solution simplifies the control mechanism, improves power factor correction, and achieves stable current output with over-current protection, reducing design complexity and enhancing response speed, while maintaining proportional input current and voltage phases.
Implementation Method 1
The inductor is configured to sense an inductor current and provide energy to at least one LED
Implementation Method 2
The current detection circuit is connected to the switch and is used to detect the inductor current information
Implementation Method 3
The transformer has a primary coil and a secondary coil. The first end of the primary coil is connected to a positive end of the power supply source. The secondary coil is coupled to energy stored in the primary coil to provide energy to the at least one LED
Data Source
AI summary
A light-emitting diode (LED) driving circuit includes a power factor correction (PFC) circuit and a driving controller. The PFC circuit controls a power factor of the LED driving circuit. The LED driving circuit includes an inductor, a switch, a current detection circuit, and a time detection circuit. The inductor senses an inductor current and provide energy to at least one LED. The switch connected to the inductor is conducted according to a driving signal. The current detection circuit connected to the switch detects inductor current information. The time detection circuit connected to the switch detects an energy discharging time during which the inductor current decrease from a peak value to zero. The driving controller connected to the switch, the current detection circuit, and the time detection circuit outputs the driving signal to the switch according to the voltage level and the energy discharging time.