LED Driver Voltage Regulation Using Current-Based Feedback
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Solution Overview
Problem
Existing LED lighting systems in the automotive industry face challenges in efficiently regulating voltage across multiple LED current sources, leading to inefficiencies and increased waste heat, as they rely on complex diode-based feedback systems that are susceptible to electromagnetic interference (EMC) and misalignments.
Innovation Solution
A method and device utilizing voltage-controlled current sources to regulate output voltage across multiple integrated circuits, where each circuit adjusts its LED group current and detects voltage drops to generate a control signal, reducing the control voltage when necessary, and using a control bus to synchronize PWM modulation across integrated circuits, thereby reducing EMC susceptibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diode-based feedback systems are used to regulate voltage across multiple LED current sources, then voltage regulation can be achieved, but the system becomes susceptible to electromagnetic interference and misalignments
Solution Approach 1:
The patent replaces the mechanical/diode-based feedback system with an electronic control approach. Each integrated circuit generates control value signals based on its characteristic voltage drop values, and these signals are combined through analog addition at the control input of the voltage regulator. This electronic signal processing approach eliminates the susceptibility to electromagnetic interference that plagues diode-based systems while maintaining reliable voltage regulation across multiple LED current sources.
2Device complexity
If multiple integrated circuits with LED current sources are supplied from a common voltage source, then system complexity is reduced, but efficient voltage regulation becomes difficult to achieve
Solution Approach 1:
The patent segments the voltage regulation control into multiple independent integrated circuits, each responsible for its own LED current source. Each integrated circuit independently determines its characteristic voltage drop value and generates corresponding control value signals. These segmented control signals are then combined at the voltage regulator's control input, allowing efficient and independent regulation of each LED string while maintaining a relatively simple common voltage source architecture.
Solution Approach 2:
The patent implements feedback control in each integrated circuit by detecting the voltage drop across its LED current source and using this information to generate appropriate control value signals. The feedback mechanism ensures that each integrated circuit can independently regulate its LED string's current based on its specific characteristics, achieving efficient voltage regulation across the entire system while keeping the overall structure relatively simple.
3Ease of operation
If voltage signals are used for control, then regulation can be implemented, but the system becomes susceptible to EMC signals and potential misalignments
Solution Approach 1:
The patent replaces vulnerable voltage control signals with current-based control signals. Each integrated circuit generates control value signals that are proportional to its characteristic voltage drop, and these current signals are combined through analog addition. Current signals are inherently more resistant to electromagnetic interference than voltage signals, as they maintain their integrity better in noisy environments. This substitution maintains ease of control implementation while significantly reducing susceptibility to EMC signals and misalignments.
Data Source
AI summary
A method supplies a lighting device with electrical energy, wherein the lighting device includes at least two integrated circuits with at least one LED group by a current source associated with this LED group. The method includes generating a supply voltage by a voltage regulator, adjusting a LED group current passing the LED groups by one of the respective current sources , detecting the voltage drops across the current sources, selecting one voltage drop of each integrated circuit as a characteristic voltage drop, generating a control value of the respective integrated circuit, according to the characteristic voltage drop, reducing the control voltage when the control voltage is greater than a control value of the respective integrated circuit, and controlling the output voltage in accordance with the control voltage and/or in accordance with a control bus voltage derived from the control voltage.