LED Operating Circuit Dynamic Switching Frequency Control
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Solution Overview
Problem
Existing operating circuits for LEDs often cause light flickering at different dimming levels due to variations in switching cycles, leading to unwanted flickering perceived by the human eye, especially at high dimming levels, without effectively managing switching losses.
Innovation Solution
The operating circuit dynamically adapts the switching frequency and current ripples based on the dimming level, with the switching frequency being a monotonically decreasing function for dimming levels below a threshold and constant for higher levels, ensuring that the amplitude and intensity of current ripples depend on the dimming level to minimize flickering while maintaining low switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed switching frequency is used in the operating circuit, then the circuit operation is simple and stable, but light flickering occurs at high dimming levels due to variations in switching cycles
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The control device dynamically adjusts the switching frequency based on the dimming level, transitioning from a higher frequency at low dimming levels to a lower frequency at high dimming levels. This dynamic adaptation eliminates light flickering while maintaining manageable circuit complexity through automated control.
2Reliability
If the switching frequency is increased to reduce flickering at high dimming levels, then light stability improves, but switching losses increase
Solution Approach 1:
The patent resolves this contradiction through dynamic switching frequency adjustment. At high dimming levels, the system automatically reduces the switching frequency to minimize switching losses, while maintaining sufficient frequency to prevent flickering. This dynamic optimization balances light stability and energy efficiency across different operating conditions.
Solution Approach 2:
The patent applies parameter changes by modifying the switching frequency parameter based on the dimming level. The control device changes the switching frequency from high to low as the dimming level increases, optimizing the balance between flicker prevention and switching loss minimization for each operating point.
3Stability of the object's composition
If pulse packets are used for brightness control, then light spectrum shifts are reduced, but current ripples cause unwanted flickering
Solution Approach 1:
The patent applies dynamics by adjusting the switching frequency within the pulse packets based on the dimming level. At high dimming levels, the reduced switching frequency within each pulse packet minimizes current ripples and associated flickering, while the pulse packet structure itself maintains light spectrum stability. This nested dynamic control addresses both issues simultaneously.
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 approach significantly reduces light flickering at all dimming levels while keeping switching losses low, providing a stable and efficient energy supply to LEDs, thereby enhancing the brightness control and reducing perceptible flicker.
Implementation Method 1
When the switch is on, current flows through the LED array and a coil, thereby charging it with energy. The energy stored in the coil is discharged via the LEDs when the switch is switched off.
Implementation Method 2
The light emission from LEDs depends on a current flow through the LEDs.
Data Source
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AI summary
The invention relates to an operating circuit for at least one lighting diode, comprising a coil, a controllable switching means, and a control device. Said control device is configured, for the purpose of providing a pulse packet to the at least one lighting diode, to switch on said controllable switching means repeatedly during a pulse duration so as to store energy temporarily in the coil, and to switch it off in order to discharge, by means of a diode and said at least one lighting diode, the energy that is stored temporarily in the coil. The control device is configured such that a switching frequency (45) with which the controllable switching means is switched on or off depends on a dimmer level, at least in one dimmer level range (9).