Dynamic Intermediate Circuit Voltage Control for LED Matrix Headlights
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Solution Overview
Problem
Existing adaptive LED matrix headlight systems face inefficiencies due to high intermediate circuit voltage requirements, leading to increased load on power supplies and energy consumption, especially when only a few LEDs are active, and require high voltage even when all LEDs need to be lit.
Innovation Solution
The system predicts the maximum number of switched-on LEDs in each branch, calculates the minimum necessary intermediate circuit voltage, and dynamically adjusts the step-up converter output based on temperature corrections to optimize voltage supply and reduce energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the intermediate circuit voltage is set to the maximum required value to ensure all LEDs can be powered, then all LED branches can be supplied with sufficient voltage, but the power supply and buck converters are subjected to unnecessary high voltage load and energy consumption increases when fewer LEDs are active
Solution Approach 1:
The patent implements dynamic adjustment of the intermediate circuit voltage based on the actual number of active LEDs in each branch. The control unit continuously monitors which LEDs are currently active and adjusts the DC link voltage accordingly, transitioning from a static maximum voltage approach to a dynamic adaptive voltage level that matches actual demand, thereby reducing energy losses while maintaining sufficient voltage for active LEDs
Solution Approach 2:
The patent changes the voltage parameter of the intermediate circuit dynamically based on operating conditions. By calculating the minimum required voltage based on the forward voltages of currently active LEDs and adding a margin, the system adjusts the DC link voltage to an optimal value rather than maintaining a fixed maximum voltage, thus reducing power supply stress and energy consumption while ensuring reliable operation
2Loss of energy
If the intermediate circuit voltage is dynamically adjusted based on the number of active LEDs, then energy consumption is reduced, but the control complexity and calculation requirements increase
Solution Approach 1:
The patent stores forward voltage values for all LEDs in a lookup table during the design phase. This preliminary action allows the control unit to quickly retrieve and sum pre-stored values to calculate the minimum required voltage, avoiding complex real-time measurements and simplifying the runtime control logic while still achieving dynamic voltage adjustment
Solution Approach 2:
The control unit continuously monitors the actual operating state by detecting which LEDs are active in each branch and uses this feedback information to adjust the intermediate circuit voltage. This closed-loop feedback mechanism ensures the voltage is optimally adapted to current demands while maintaining system reliability through continuous monitoring and adjustment
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 minimizes losses and achieves high efficiency by optimizing the intermediate circuit voltage according to the number of active LEDs and temperature, reducing strain on power supplies and energy consumption.
Implementation Method 1
The input voltage of this power supply can be, for example, the vehicle's electrical system. During the dynamically changing light distribution of a headlight, especially in lighting scenarios where, on average, only a few LEDs in the branches are active and the remaining LEDs are bypassed, the power supply that generates the intermediate circuit voltage is subjected to a greater load.
Implementation Method 2
The individual branches, which can also be called strings, are powered by hysteretically controlled buck converters (step-down converters), designed as highly dynamic current sources.
Data Source
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AI summary
The invention relates to a headlight for motor vehicles with at least two LED branches (Z1, Z2, Zn), each of which has a series circuit of LEDs (LED11…LED1x; LED21…LED2x; LEDn1…LED3x), and at least one LED of each branch can be bridged by a controlled switch (S11...S1x; S21…S2x; Sn1…Snx). Each LED branch (Z1, Z2, Zn) is supplied by a step-down controller (T1, T2, Tn) paired with the respective branch, wherein the step-down controllers are designed as constant power sources and lie at a common intermediate circuit voltage (Uz) on the input side, said voltage being generated by a voltage source (H) which lies at an input voltage (Ue). A control unit (C) is provided which is designed to actuate the switches in a pulse width-modulated manner on the basis of a desired light pattern, wherein the switch times of the LEDs of a branch are temporally offset to each other in a uniform manner within a PWM period. The control unit (C) has a memory unit (S) in which the assignment of the LEDs of the matrix headlight to the spatial angles to be illuminated by the headlight is stored, and the control unit is supplied request signals (d) relating to the desired light pattern. The control unit (C) is designed to calculate the maximum number of active LEDs of each branch (Z1, Z2, Zn), and thus also the maximally occurring flux voltage of said branches, from the information, originating from the memory unit (S), which relates to the assignment of the LEDs to the spatial angles in combination with the information, provided in the matrix IC (M), on the assignment of the LEDs to the respective controlled switches (S11...S1x; S21…S2x; Sn1…Snx) and to the respective sampling degree which determines the brightness of the individual LEDs, to select the LED branch with the most active LEDs therefrom, said LED branch specifying the minimum required intermediate circuit voltage (Uz), and to supply the information relating to the selected LED branch to the voltage supply (H) in the form of a command signal (b) in order to dynamically set the voltage supply to the intermediate circuit voltage (Uz) value required for the respective supply of the selected LED branch.