LED Driver PFC via Dynamic Input Current Wave Shaping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional LED driver circuits for active power factor correction rely on external components, leading to inflexibility, high costs, and inefficiencies in achieving optimal balance between current accuracy, power factor, total harmonics distortion, and peak inductor currents.
Innovation Solution
A system and method utilizing intelligent current control and peak current limit control through a customized wave shaping profile, implemented using a module-based architecture including an input module, computing module, subtractor module, and firmware control, which eliminates the need for external components by dynamically shaping the input current waveform and controlling peak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LED driver circuits use external components for active power factor correction, then power factor correction can be achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines the power factor correction functionality with the existing LED driver circuit by integrating the control logic into the microcontroller unit. The current sense resistor, inductor, and switching transistor are shared between the LED driving function and the PFC function, eliminating the need for separate external PFC components while achieving both LED current regulation and power factor correction.
Solution Approach 2:
The microcontroller unit is designed to perform multiple functions: it controls the switching transistor for LED current regulation, monitors the current through the sense resistor, implements the PFC control algorithm, and regulates the output current to the LED string. This multi-functional approach replaces dedicated external PFC components with a unified control system.
2Measurement precision
If external components are used for current detection and power factor correction, then accurate current regulation is achieved, but cost and resource efficiency decrease
Solution Approach 1:
The system uses the existing current sense resistor in the LED driver circuit to detect both the LED current and the input current for PFC control. The microcontroller unit processes these measurements to implement both LED current regulation and power factor correction without requiring additional external detection components, thereby reducing cost and resource requirements while maintaining measurement accuracy.
3Reliability
If conventional wave shaping is used for power factor correction, then power factor improves, but peak inductor currents increase leading to higher losses
Solution Approach 1:
The patent implements dynamic control of the switching transistor duty cycle based on real-time feedback from the current sense resistor and inductor current measurements. The microcontroller continuously adjusts the duty cycle to shape the input current waveform while preventing excessive peak currents, thereby achieving power factor correction without the energy losses associated with conventional fixed wave shaping approaches.
Solution Approach 2:
The system uses feedback from the current sense resistor and inductor current measurements to dynamically adjust the switching transistor duty cycle. This closed-loop control ensures that the input current waveform is shaped to achieve high power factor while the duty cycle is optimized to prevent excessive peak currents, thereby reducing energy losses in the inductor and switching components.
Data Source
AI summary
The present invention discloses a system and method for active power factor correction and current regulation in led circuit. The system (100) used in the LED driver circuit performs active PFC and current regulation through the dynamic input current wave shaping by limiting peak currents. The dynamic wave 5 shaping scheme is realized through hardware and firmware and is used to strike an optimal balance between current accuracy, Power factor, THD and peak inductor currents. The system (100) is versatile enough to improve PF and current accuracy in LED circuits and indimmers circuits.