LED Converter Control Unit for Light Power Fluctuation Reduction
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Solution Overview
Problem
Existing control units for actively clocked converters used in light-emitting diodes experience fluctuations in light output due to inaccuracies in detecting the current threshold value, leading to inconsistent light intensity, particularly at lower dimming values.
Innovation Solution
A control unit that adjusts switching durations based on the time when the current reaches a threshold value during a switching cycle, using a combination of duration control and threshold value control to ensure precise timing and reduce sampling errors caused by clocking inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If threshold value control with clocked sampling is used to control switch timing, then the control mechanism is simple, but the detection precision of the current threshold value is inaccurate causing light output fluctuations
Solution Approach 1:
The patent implements a feedback mechanism where the actual switching time is measured and compared against the expected threshold crossing time. The error signal generated from this comparison is used to adjust the switching duty cycle, creating a closed-loop control system that compensates for sampling inaccuracies and maintains precise current threshold control despite clocked sampling limitations.
Solution Approach 2:
The patent changes the control parameter from direct threshold voltage comparison to time-based measurement. By measuring the actual time when the current reaches the threshold value and using this time information to adjust the switching duty cycle, the system transforms the control approach from voltage-domain to time-domain, thereby achieving higher precision in detecting the threshold crossing moment.
2Stability of the object's composition
If sampling is synchronized with clocking cycles, then the control timing is regular, but the detection accuracy of the exact threshold crossing time is reduced
Solution Approach 1:
The patent uses preliminary action by measuring and recording the actual threshold crossing time during each switching cycle before the next cycle begins. This measured time information is stored and used to calculate the appropriate duty cycle adjustment for the subsequent cycle, ensuring that the precise timing information is captured and applied without being lost to clock synchronization limitations.
Solution Approach 2:
The system performs self-correction by automatically adjusting its own switching duty cycle based on the measured timing errors from previous cycles. The control unit uses the accumulated timing information to self-regulate the switching parameters, eliminating the need for external intervention and maintaining accurate threshold control autonomously despite fixed clocking intervals.
3Ease of operation
If the switching duration is fixed based on predetermined thresholds, then the control is simple, but the light output consistency varies particularly at lower dimming values
Solution Approach 1:
The patent introduces dynamics by making the switching duty cycle adjustable based on actual measured performance rather than fixed predetermined values. The system continuously adapts the switching duration and timing by incorporating feedback from actual threshold crossing measurements, allowing the control parameters to dynamically change in response to varying operating conditions and achieving consistent light output across all dimming levels.
Data Source
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AI summary
According to the present invention, a control unit is provided for controlling at least one actively switched converter for the electrical supply of at least one light source, in particular a light-emitting diode, wherein the actively switched converter comprises at least two switches and an energy storage unit, in particular an inductor or a choke. The control unit according to the invention is configured to control the charging and discharging of the energy storage unit by switching the at least two switches on and off; and the control unit is configured to receive the current flowing through the energy storage unit as a feedback variable.Furthermore, the control unit is configured to control the switching of at least one of the at least two switches during at least one switching cycle, depending on a switching time; to determine, based on the feedback variable, the time at which the current flowing through the energy storage unit reaches a threshold value; and to adjust the switching time for the subsequent switching cycle depending on the determined time. The present invention further relates to a control device comprising such a control unit according to the invention and at least one actively switched converter; a luminaire comprising at least one such control device according to the invention and at least one light source, in particular at least one light-emitting diode; and a method for controlling at least one actively switched converter for the electrical supply of at least one light source, in particular a light-emitting diode.