LED Driver Circuit Primary-Side Current Regulation
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Solution Overview
Problem
Existing driver circuits for LEDs face challenges in accurately regulating current without strict isolation, as the relationship between primary-side and secondary-side currents is influenced by LED voltage changes due to temperature and LED configuration variations, necessitating complex feedback mechanisms like optocouplers.
Innovation Solution
A driver circuit design that includes a control unit to determine the secondary-side current indirectly using actual current and voltage signals from the primary side, allowing for correction of the primary-side current by processing the magnetizing current, thereby eliminating the need for secondary-side feedback and optocouplers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If secondary-side current feedback is implemented using optocouplers for isolation, then current regulation precision is improved, but device complexity increases
Solution Approach 1:
The invention extracts the feedback measurement from the secondary side and relocates it to the primary side. By measuring the primary-side current and voltage and calculating the secondary-side current indirectly through control unit computations, the patent eliminates the need for optocouplers and secondary-side feedback paths, thereby reducing device complexity while maintaining regulation precision
Solution Approach 2:
The invention introduces computational processing as an intermediary between primary-side measurements and secondary-side current control. The control unit acts as a mediator that receives primary current and voltage signals, performs calculations to determine secondary current, and generates appropriate control signals, replacing the direct feedback path that would require optocouplers
2Device complexity
If primary-side current measurement is used for control, then device complexity is reduced, but measurement precision deteriorates due to LED voltage variations
Solution Approach 1:
The invention implements a computational feedback mechanism where the control unit continuously processes primary-side current and voltage measurements, calculates the corresponding secondary-side current, and adjusts switching parameters accordingly. This closed-loop computational feedback compensates for LED voltage variations and maintains precise current regulation without requiring secondary-side measurements
Solution Approach 2:
The invention changes the control parameters from direct secondary-side current measurement to primary-side current and voltage measurements combined with computational processing. By monitoring both primary current and voltage and using their relationship to infer secondary current, the system adapts to LED voltage variations while maintaining regulation precision
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 approach enables precise current regulation for LEDs without requiring complex feedback across the galvanic barrier, accurately accounting for variable magnetization effects and maintaining constant current through the LED path, thus improving regulation and reducing operational complexity.
Implementation Method 1
A transformer following the resonant circuit is provided for transmitting electrical energy from a primary winding to a secondary winding
Implementation Method 2
a resonant circuit, such as an LLC converter, responsible for transferring current across a galvanic barrier
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a driver circuit (1) for lighting means, particularly for one or more LEDs, comprising: a circuit (20) which can be supplied with a voltage (Vdc), is clocked by means of at least one switch (LS, HS) and feeds a resonant circuit (21); a transmitter (22) which follows said resonant circuit (21) and transmits electrical energy from a primary winding (L1) to a secondary winding (L2), said resonant circuit (21) being coupled to the primary winding (L1) and the lighting means being able to be supplied with current from the secondary winding (L2); and a control unit (9) to which are fed back an actual current signal (S_iLLC) that reproduces the current (iLLC) through the resonant circuit (21), and an actual voltage signal (VL1) that reproduces the voltage applied to the primary winding (L1), said control unit (9) being designed to determine an indirect reproduction of the secondary side current on the basis of the actual current signal (S_iLLC) and actual voltage signal (VL1) that were obtained on the primary side.