Multi-output Current-balancing Circuit for LED Drivers
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Solution Overview
Problem
Conventional LLC resonant DC/DC converters struggle to achieve current balancing among multiple LED strings, leading to increased withstand voltage, conduction losses, and higher production costs due to large bulk capacitors, which limits system conversion efficiency and complicates design.
Innovation Solution
A multi-output current-balancing circuit utilizing a transformer with multiple secondary windings and current balancing components to balance currents between rectifier circuits, allowing for efficient current balancing across multiple LED groups with reduced voltage requirements and smaller capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple LED strings are connected in series to form LED groups, then current balancing between LED strings is achieved, but the withstand voltage of each LED string increases and conduction losses increase
Solution Approach 1:
The patent divides the power conversion function into multiple independent full-bridge DC/DC converter modules, each handling a portion of the total power. This segmentation allows each module to operate at optimized voltage levels, reducing conduction losses while maintaining current balancing across multiple LED strings through parallel configuration
Solution Approach 2:
The patent introduces a current balancing circuit as an intermediary component that actively regulates and balances the current distribution among parallel LED strings. This mediator ensures uniform current sharing without requiring increased withstand voltage, thereby reducing conduction losses in high-voltage configurations
2Reliability
If high withstand voltage diodes are used to handle high cross voltage, then current balancing is achieved, but forward voltage drops increase and conduction losses cannot be ignored
Solution Approach 1:
By segmenting the power conversion into multiple full-bridge modules operating in parallel, each module uses diodes at lower voltage stress levels. This segmentation eliminates the need for high withstand voltage diodes in each individual module, reducing forward voltage drops and conduction losses while maintaining overall current balancing
Solution Approach 2:
The patent combines multiple full-bridge DC/DC converter modules in parallel to achieve the total required power output. This merging approach allows the system to handle high total power while each individual module operates at lower voltage levels, using diodes with lower withstand voltage ratings and reduced conduction losses
3Reliability
If large bulk capacitors are configured as filter capacitors, then current balancing is achieved, but system conversion efficiency decreases and production costs increase
Solution Approach 1:
The patent segments the filtering function across multiple parallel full-bridge modules, each with its own smaller bulk capacitor. This segmentation eliminates the need for a single large bulk capacitor, reducing the overall capacitance requirement while maintaining effective current balancing and filtering across the parallel LED string configuration
Solution Approach 2:
The patent uses multiple identical full-bridge DC/DC converter modules operating in parallel, each with its own set of filter capacitors. This copying approach distributes the filtering function across multiple smaller capacitor sets, achieving the same current balancing effect as a single large capacitor while improving system efficiency and reducing cost
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 enables efficient current balancing across multiple LED channels, increasing system conversion efficiency, reducing product costs and circuit volume, and simplifying design, while supporting high-power applications with low-voltage rectifier diodes and small bulk capacitors.
Implementation Method 1
a transformer having a primary winding and a plurality of secondary windings, where the primary winding receives an AC input current
Implementation Method 2
a plurality of first and second rectifier circuits and a plurality of first current balancing components, where each of the first and second rectifier circuits and the first current balancing components is coupled to a corresponding secondary winding
Data Source
AI summary
The present invention relates to a multi-output current-balancing circuit, which in one embodiment can include: (i) a transformer having a primary winding and a plurality of secondary windings, where the primary winding receives an AC input current; (ii) a plurality of first and second rectifier circuits and a plurality of first current balancing components, where each of the first and second rectifier circuits and the first current balancing components is coupled to a corresponding secondary winding, where each the first current balancing component is configured for current balancing between each of the first and second rectifier circuits of the corresponding secondary winding; and (iii) at least one second current balancing component, where each second current balancing component is coupled to a pair of the second rectifier circuits that correspond to different secondary windings, where the second current balancing components are configured for current balancing between different the secondary windings.