LED Driver Circuit with Charge-Pump Capacitors for Transformer Stability
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Solution Overview
Problem
Lighting devices with light emitting diodes (LEDs) face suboptimal behavior when replacing low-voltage lamps, particularly with transformers and other voltage sources, due to differing voltage-current characteristics, and may exhibit flickering or inadequate performance across various voltage sources.
Innovation Solution
A lighting device circuit comprising diodes for rectification, a buffer capacitor, and additional charge-pump capacitors that act as a voltage quadrupler, enabling energy transfer and load current extraction even at lower voltage amplitudes, ensuring sustained oscillation of electronic transformers and improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a simple rectifier circuit is used, then the device complexity is low, but the lighting device exhibits suboptimal behavior and flickering with multiple voltage sources
Solution Approach 1:
The patent introduces intermediary capacitors (second and third capacitors) coupled in parallel to diodes in the rectifier circuit. These capacitors act as mediators to transfer energy from the voltage source to the converter input, enabling stable operation across multiple voltage sources by providing an energy reservoir that smooths out voltage variations and maintains minimum load requirements.
Solution Approach 2:
The patent modifies the electrical parameters of the rectifier circuit by adding capacitors that change the voltage-current characteristics. The second and third capacitors create a charge-pump effect that increases the voltage amplitude delivered to the converter, transforming the circuit's behavior to satisfy minimum load requirements across different voltage source amplitudes and frequencies.
2Use of energy by moving object
If the voltage source amplitude is small, then energy transfer is insufficient, but adding charge-pump capacitors enables energy transfer even at lower voltage amplitudes
Solution Approach 1:
The second and third capacitors serve as energy intermediaries that accumulate charge during voltage peaks and release it during low-voltage periods. This charge-pump mechanism enables continuous energy transfer to the converter input even when the voltage source amplitude is insufficient, effectively decoupling the energy transfer capability from the instantaneous voltage amplitude.
Solution Approach 2:
The capacitors perform preliminary energy accumulation during high-voltage periods (when the voltage source amplitude is sufficient) so that energy is available for transfer during low-voltage periods. This preliminary charging action ensures that the converter always receives adequate energy regardless of the instantaneous voltage source amplitude.
3Speed
If electronic transformers are used, then high frequency oscillation is achieved, but minimum load requirements cause suboptimal behavior and flickering
Solution Approach 1:
The second and third capacitors act as energy intermediaries between the electronic transformer and the converter, providing a buffered energy supply that maintains minimum load requirements. This intermediary energy reservoir ensures stable high-frequency oscillation by preventing voltage drops that would otherwise cause the transformer to fall out of oscillation, thereby eliminating flickering and suboptimal behavior.
Solution Approach 2:
The capacitors provide beforehand cushioning by pre-storing energy during voltage peaks to compensate for potential energy deficits during voltage troughs. This energy cushioning ensures that the electronic transformer always operates with sufficient load, preventing oscillation failure and maintaining stable high-frequency operation under all voltage source conditions.
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
The solution allows the lighting device to function optimally with multiple voltage sources, including electronic transformers, by maintaining efficient operation and reducing flickering, while being economical and robust, with the charge-pump capacitors optimizing the charge-pump effect and preventing overboosting.
Implementation Method 1
a first circuit coupled to input terminals, for receiving the first voltage signal from the voltage source, the first circuit comprising diodes for rectifying the first voltage signal and supplying a second voltage signal
Implementation Method 2
a first capacitor for buffering the second voltage signal
Implementation Method 3
By having introduced a second capacitor, which is coupled in parallel to (exactly) one of the diodes of the diode circuit, the first circuit becomes able to extract load current from the voltage source and to transfer energy from the voltage source to the input of the second circuit even when the amplitude of the first voltage signal of the voltage source is smaller than the magnitude of the second voltage signal buffered by the first capacitor
Implementation Method 4
The first circuit, according to the invention provided with a fourth circuit, acts as a voltage quadrupler with rectification
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
Lighting device suitable for multiple voltage sources, comprising a first circuit (1) with diode circuits coupled to input terminals (2, 3) for receiving first voltage signals from first circuits (21) such as voltage-to-voltage converters. The diode circuits comprise diodes (11-14) for rectifying the first voltage signals and are coupled to output terminals (4, 5) for supplying second voltage signals. First capacitors (15) are coupled to the output terminals (4, 5) for buffering the second voltage signals and for offering buffered second voltage signals to second circuits (22) such as voltage-to-current-converts for feeding light circuits (30) comprising one or more light emitting diodes. Second capacitors (16, 17) coupled in parallel to one of the diodes (11-14) provide a charge-pump effect to improve performances of the first and second circuits (21, 22) and the light circuits (30).