LED Driver Reference Voltage Control for Heat Reduction
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Solution Overview
Problem
Existing LED driving devices generate excessive heat due to uneven cathode voltages and currents across multiple LED channels, particularly in large vehicle-mounted display devices, leading to increased power consumption and heat issues.
Innovation Solution
An LED driving device with a DC-DC controller and constant current circuit that maintains the cathode voltage of LEDs at a reference voltage, with a reference voltage generator adjusting based on set LED current values, and a dimming controller switching between PWM and DC dimming to optimize current usage and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the cathode voltage of LEDs is controlled to maintain reference voltage across multiple channels, then the luminous intensity and power consumption are stabilized, but heat generation increases due to uneven voltage distribution among channels
Solution Approach 1:
The patent changes the reference voltage parameter dynamically based on the LED current value. As the LED current decreases, the reference voltage is reduced proportionally. This parameter change ensures that the voltage difference between channels remains consistent while absolute voltage levels are optimized, reducing power consumption and heat generation in constant current driver circuits without compromising luminous intensity stability
Solution Approach 2:
The patent introduces dynamic control where the reference voltage is not fixed but varies according to the LED current setting. The control circuit continuously adjusts the reference voltage to match the current level, creating a dynamic system that adapts to different operating conditions. This dynamic approach allows optimal power efficiency across various dimming levels while maintaining stable LED operation
2Device complexity
If the reference voltage is kept constant for all LED current values, then the control circuit is simple, but power consumption and heat generation increase
Solution Approach 1:
The patent implements parameter changes by making the reference voltage variable rather than constant. The reference voltage is adjusted according to the LED current value, creating a proportional relationship between current and reference voltage. This approach increases power efficiency without requiring complex control mechanisms, as the parameter change follows a predictable pattern that can be implemented with relatively simple circuitry
3Illumination intensity
If PWM dimming control is used to reduce LED current, then luminous intensity is reduced, but heat generation from constant current driver circuits increases due to fixed reference voltage
Solution Approach 1:
The patent applies parameter changes by reducing the reference voltage in proportion to the LED current during PWM dimming operation. When the LED current is reduced through PWM control, the reference voltage is simultaneously reduced, which decreases the power consumption and heat generation in the constant current driver circuits. This coordinated parameter adjustment maintains system efficiency across different dimming levels
Solution Approach 2:
The patent creates a dynamic response where the reference voltage automatically adjusts to the actual LED operating conditions. During PWM dimming, as the LED current varies, the reference voltage dynamically changes to match, ensuring that the driver circuits operate efficiently at all dimming levels. This dynamic adaptation reduces heat generation without requiring separate control mechanisms for different operating modes
Data Source
AI summary
In an LED driving device, a DC-DC controller performs control such that the voltage at an LED terminal remains equal to a reference voltage, and a reference voltage generator generates the reference voltage such that it decreases as the set value of the LED current set by an LED current setter decreases.