Solid State Light Source Driver Circuit Buck Boost Switching
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Solution Overview
Problem
Conventional driver circuits for solid state light sources face challenges in efficiently managing varying output voltages when driving light sources of different colors, leading to inductor losses and reduced efficacy due to AC input voltage fluctuations.
Innovation Solution
A driver circuit with a single switching converter controller that dynamically switches between buck and boost configurations based on output voltage feedback, coupled with an energy storage circuit to maintain consistent current delivery during input voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a buck-boost or flyback converter configuration is used to handle varying output voltages, then the driver circuit can accommodate different current draw requirements, but inductor losses increase significantly
Solution Approach 1:
The patent implements a dynamic switching mechanism that automatically selects between buck and boost converter modes based on real-time comparison between input rectified voltage and output voltage. The controller monitors voltage levels and switches configurations accordingly, allowing the system to adapt to varying load conditions without the energy losses associated with buck-boost or flyback topologies
Solution Approach 2:
The patent divides the voltage conversion function into two separate operational modes (buck and boost) rather than using a single buck-boost or flyback converter. This segmentation allows each converter type to operate in its optimal efficiency range for specific voltage conditions, reducing overall energy losses while maintaining versatility
2Reliability
If conventional switching converter configurations are used, then voltage regulation is achieved, but energy storage requirements increase due to complete energy storage in inductor before delivery
Solution Approach 1:
The patent uses capacitor-based energy storage that charges during high-voltage periods and discharges during low-voltage periods, providing preliminary energy preparation without requiring complete energy storage in an inductor. This approach reduces energy losses while maintaining reliable voltage regulation
3Ease of operation
If AC input voltage is used directly, then the driver circuit receives power from standard sources, but efficacy decreases during voltage drop periods
Solution Approach 1:
The patent implements continuous energy delivery to the load by using capacitor storage to bridge voltage drop periods. The capacitors charge when input voltage is high and discharge when voltage drops, ensuring uninterrupted and efficient energy transfer to the light source throughout the entire AC cycle without efficacy loss
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 light source efficacy by minimizing inductor losses and maintaining consistent energy delivery, improving lumens per watt (LPW) performance.
Implementation Method 1
a switching converter circuit receives a rectified AC output from the rectifier, and provides a stable, regulated DC output to the solid state light source
Implementation Method 2
These devices include a switch, e.g. a transistor, which is selectively operated to allow energy to be stored in an energy storage device, e.g. an inductor
Implementation Method 3
Another known type of switching converter includes a transformer-based switching regulator, such as a 'flyback' converter. In a transformer-based switching regulator, the primary side of the transformer is coupled to the rectified AC output of the rectifier. The regulated DC output voltage is provided at the secondary side of the transformer
Implementation Method 4
A driver circuit for a solid state light source typically converts an alternating current (AC) input, such as a 120V/60 Hz line input or input from a dimmer switch, to a stable direct current (DC) voltage, which is used to drive the solid state light source. Such a circuit typically incorporates a rectifier, which receives the AC input
Data Source
AI summary
A solid state light source driver circuit that operates in either a buck convertor or a boost convertor configuration is provided. The driver circuit includes a controller, a boost switch circuit and a buck switch circuit, each coupled to the controller, and a feedback circuit, coupled to the light source. The feedback circuit provides feedback to the controller, representing a DC output of the driver circuit. The controller controls the boost switch circuit and the buck switch circuit in response to the feedback signal, to regulate current to the light source. The controller places the driver circuit in its boost converter configuration when the DC output is less than a rectified AC voltage coupled to the driver circuit at an input node. The controller places the driver circuit in its buck converter configuration when the DC output is greater than the rectified AC voltage at the input node.