Self-Oscillating Power Supply Trigger Pulse Injection for LED Stability
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Solution Overview
Problem
Low-power LED lighting units experience unstable operation and optical flicker due to reduced power consumption, as self-oscillating power supplies struggle to maintain self-oscillation when the current drawn is below the minimum required, leading to early disruption and inefficient energy transfer.
Innovation Solution
A circuit arrangement that injects trigger pulses into the secondary side of a self-oscillating power supply to restart or maintain self-oscillation, ensuring stable operation even at low average currents, and includes a pulse generator and controller to manage the conduction time and power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a self-oscillating power supply is used to operate low-power LED lighting units, then energy efficiency is improved, but operational stability deteriorates due to early disruption of self-oscillation when current drawn is below minimum required
Solution Approach 1:
The circuit arrangement proactively detects when the power supply current approaches the minimum threshold required for self-oscillation maintenance, and preemptively injects trigger pulses to restart the oscillation before it disrupts. This prevents the instability and optical flicker that would otherwise occur when the current drops below the minimum required level.
Solution Approach 2:
The system continuously monitors the power supply current and uses this feedback to control the injection of trigger pulses. When the current is detected to be at or near the minimum threshold, the feedback mechanism activates the pulse generator to inject trigger pulses, thereby maintaining stable self-oscillation operation throughout the AC cycle.
2Reliability
If the conduction time of the power supply is extended to maintain stable operation, then operational stability is improved, but power factor deteriorates due to increased reactive power consumption
Solution Approach 1:
Instead of extending the continuous conduction time, the system uses periodic trigger pulses injected at strategically timed intervals during the AC cycle. These pulses are synchronized with the power supply's oscillation cycles, providing just enough excitation to maintain stability without requiring prolonged conduction periods that would increase reactive power consumption.
Solution Approach 2:
The system dynamically adjusts the timing and frequency of trigger pulse injection based on the instantaneous power supply current and load conditions. By optimizing these parameters, the circuit maintains stable operation with minimal conduction time, thereby preserving a good power factor.
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 enhances the operational stability and efficiency of low-power LED lighting units by maintaining self-oscillation, reducing optical flicker, and improving compatibility with dimming systems and electromagnetic transformers, while allowing flexible control of power transfer.
Implementation Method 1
a pulse generator (17), connected with said input and adapted to inject at least one trigger pulse into said power supply
Implementation Method 2
the 50/60 Hz sinusoidal mains voltage is converted to a higher frequency, resulting in smaller transformers to obtain the secondary voltage of e.g. 12V AC
Implementation Method 3
a switching regulator is arranged to alternate the polarity of the rectified mains voltage and thus to provide a high-frequency alternating voltage to a transformer
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5b
AI summary
A circuit arrangement (3) is provided for operating at least one low-power lighting unit with a power supply(4) and in particular with a self-oscillating power supply. The circuit arrangement (3)comprises at least an input (12) for receiving an operating voltage (28) from said power supply (4) and an output (11) for connection to one or more low-power lighting units. To allow an efficient operation of said low-power lighting unit with the power supply (4), the circuit (3) comprises a pulse generator (17), connected with said input (12) and adapted to inject at least one trigger pulse (40a, 40b) into said power supply (4) during operation.