LED Drive Circuit with Balancing Transformers for Current Equalization
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Solution Overview
Problem
Existing LED driving circuits face challenges in achieving high efficiency and low cost while maintaining precise current balancing between LED loads, especially when voltage disparities occur, leading to high power consumption and heat generation.
Innovation Solution
A high-frequency pulse AC current source driving circuit with a rectification and filtering circuit, including balancing capacitors and diodes, connected in series with LED loads, and current-balancing transformers to ensure equal current distribution across multiple LED branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear regulating constant-current circuits are used to achieve precise current control and low cost, then current balancing between LED loads is improved, but power consumption increases significantly and heat generation occurs when voltage disparities exist
Solution Approach 1:
The patent introduces a current balancing circuit as an intermediary component between the power source and multiple LED loads. This balancing circuit actively monitors and adjusts current distribution, using a small balancing current to compensate for voltage disparities across different LED branches, thereby achieving precise current control without requiring high power consumption from the main power path.
2Measurement precision
If DC/DC constant-current circuits are used after constant-voltage module to ensure current balancing, then current control precision is improved, but circuit cost increases and efficiency decreases due to significant voltage disparity
Solution Approach 1:
The patent extracts the current balancing function from complex DC/DC constant-current circuits and implements it through a simplified dedicated balancing circuit. This separation allows the main power path to remain simple and efficient while the extracted balancing function handles current distribution precision, reducing overall circuit complexity and cost.
3Loss of energy
If linear regulating devices are used to maintain output voltage slightly higher than LED loads for minimum power consumption, then efficiency is improved, but current balancing capability deteriorates when LED loads have different voltage requirements
Solution Approach 1:
The patent segments the power delivery function into two independent parts: a main power path that provides bulk current with minimal voltage headroom for efficiency, and a separate balancing circuit that handles fine-grained current distribution across different LED branches. This segmentation allows each part to optimize for its specific function without compromise.
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 achieves high-efficiency current balancing with low cost and high reliability, maintaining precise current control regardless of voltage differences across LED loads, reducing power loss and heat generation.
Implementation Method 1
The rectification and filtering circuit includes two independent half-wave rectification circuits and two filter capacitors; each of the half-wave rectification circuits includes two diodes connected in series
Implementation Method 2
each of the LED loads is connected in parallel with one of the filter capacitors
Implementation Method 3
the balancing capacitor C1 is connected in series with an input terminal of the rectification and filtering circuit
Data Source
AI summary
A drive circuit for realizing accurate constant current of multiple LEDs is disclosed. The drive circuit comprises a high-frequency impulse Alternating Current (AC) power carrying N circuit units with same structure. Each of the circuit unit comprises a rectifier filter circuit, a blocking capacitor C1 and two LED loads. The rectifier filter circuit comprises two independent half-wave rectifier circuits, and two filter capacitors. Each of the two half-wave rectifier circuits comprises two diodes connected in series to supply power for the corresponding LED load. The filter capacitor is connected in parallel with the two ends of an LED load respectively, and the blocking capacitor C1 is connected in series with the input end of the rectifier filter circuit. The circuit also comprises N−1 equalizing transformers, each of which connects in series between two adjacent circuit units. A drive circuit for constant output current of multiple LEDs with high efficient, low cost and great flow equalization is provided in the embodiment of the invention. When the differential voltage of the two LED loads is large, high efficiency can also be achieved.