Variable Time Constant PFC Controller for LED Lighting
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Solution Overview
Problem
Actively clocked Power Factor Correction (PFC) circuits in lighting systems experience transient energy imbalances during controller setting changes, leading to brief flashes of light or low light intensities, which are perceptible to the human eye.
Innovation Solution
The PFC controller determines a control parameter, such as switch-on time, based on a mean value calculated from multiple controller settings, and only changes settings when the switch-on time is within a predefined corridor around the mean value, ensuring a smooth transition and minimizing energy imbalances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the controller setting of the PFC circuit is changed quickly to respond to load changes, then the response speed is improved, but transient energy imbalances occur causing perceptible flashes or intensity changes
Solution Approach 1:
The patent applies dynamics by making the time constant of the PFC controller variable rather than fixed. The controller dynamically adjusts the time constant based on operating conditions, allowing fast response when needed while preventing transient imbalances that cause perceptible flashes. This resolves the contradiction by enabling speed improvement without sacrificing lighting stability.
Solution Approach 2:
The patent changes the parameter of the time constant from a fixed value to a variable parameter that can be adjusted based on operating conditions. By modifying this key parameter, the system achieves both fast response capability and stable lighting output, resolving the contradiction between response speed and lighting stability.
2Loss of time
If the time constant of the PFC controller is reduced to improve transient response, then the response time is improved, but energy imbalances during transitions become more severe
Solution Approach 1:
The patent makes the time constant dynamic, allowing it to be reduced for faster response when appropriate, while being increased or adjusted to prevent severe energy imbalances during transitions. This dynamic adjustment resolves the contradiction between reducing transition time and preventing energy loss.
Solution Approach 2:
The controller monitors operating conditions and uses feedback to adjust the time constant appropriately. This feedback mechanism ensures that the time constant is optimized for each operating phase, achieving fast response without causing severe energy imbalances during transitions.
Data Source
AI summary
The invention proposes a method for operating an actively clocked PFC circuit (2) having a directly or indirectly connected load circuit (5) at the output of the PFC circuit (2), wherein the load circuit (5) has at least one luminous means, in particular one or more LEDs (4), wherein the PFC circuit (2) is controlled by a PFC controller (30) in such a manner that the PFC controller (30) determines a control parameter, in particular a switched-on time period (ton), for the clocking of the PFC circuit (2) on the basis of at least one first controller setting (RE_fast) and one second controller setting (RE_slow), wherein the time of a change from the first controller setting (RE_fast) to the second controller setting (RE_slow) is dependent on the directly or indirectly determined average value of the control parameter, in particular the switched-on time period (ton).