DC Voltage Source Shunts Excess Current for Linear Transfer Curve
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Solution Overview
Problem
The 0-10V interface used in dimmable LED drivers experiences inaccuracies and temperature dependency in its transfer curve due to excess current flowing through the first diode, leading to non-linearity and inaccuracy in the output current, especially with variations in magnetizing inductance and temperature.
Innovation Solution
A DC voltage source design that shunts excess current away from the first diode by connecting a second input node to the transformer's secondary side, using a branch diode to divert excess current, thereby ensuring only a predetermined amount of current flows through the first diode, reducing non-linearity and temperature dependency in the transfer curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess current is shunted by the current regulator circuit, then the circulating current can be maintained, but the transfer curve accuracy deteriorates due to non-linearity and temperature dependency
Solution Approach 1:
The patent extracts the harmful excess current from the main current path by providing a separate shunt path through the current regulator circuit. This separates the useful circulating current (which maintains LED operation) from the harmful excess current (which causes inaccuracies), allowing the latter to be diverted without affecting the precision of the transfer curve for the former.
Solution Approach 2:
The current regulator circuit acts as an intermediary component between the transformer and the set resistor. It mediates the circulating current by selectively allowing the predetermined amount to pass through to control LED current while diverting the excess current, thus protecting the transfer curve accuracy from the harmful effects of excess current.
2Reliability
If a transformer is used to create isolation barrier, then safety is improved, but the circuit complexity increases
Solution Approach 1:
The transformer in the patent serves multiple functions: it provides galvanic isolation for safety, transforms voltage levels to match the LED driver requirements, and generates the circulating current through its magnetic coupling. By consolidating these multiple functions into a single component, the overall circuit complexity is reduced despite the added isolation capability.
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 design provides an accurate, temperature-independent, and linear transfer curve by isolating excess current from the first diode, enhancing the precision and reliability of the output current regulation.
Implementation Method 1
The current magnetically couples to a second side, being the input side of the transformer
Data Source
AI summary
A Direct Current, DC, voltage source arranged for providing a DC voltage based on an input voltage between two input terminals, wherein said DC voltage source comprises a transformer arranged for receiving a supply current, at a first side of the transformer, and for transforming said supply current to a circulating current at a second side of the transformer, a first and a second input terminal for receiving an input voltage for setting a DC voltage to be provided by said DC voltage source, a first diode, wherein an anode of said first diode is connected to a first end of said second side of said transformer, and wherein a cathode of said first diode is connected to said first input terminal, a current regulator circuit for assuring that an amount of current circulating current is shunted from the first diode.