TRIAC Dimmable LED Driver Circuit Eliminating Bleeder Heat
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Solution Overview
Problem
Conventional TRIAC dimmable LED driver circuits suffer from high power dissipation and heat issues due to the bleeder circuit, leading to low efficiency and high system complexity and cost.
Innovation Solution
The proposed TRIAC dimmable LED driver circuit eliminates the bleeder circuit by using the converter input current to provide holding current for the TRIAC dimmer, employing a source driving scheme with power and low voltage MOS transistors, and incorporating a peak current comparator, maximum on-time timer, OR logic gate, RS flip-flop, and voltage sensing networks to simplify the control and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bleeder circuit with resistor R1 and switch M2 is used to provide holding current for the TRIAC dimmer, then the TRIAC dimmer can maintain proper operation, but the circuit dissipates too much power and generates excessive heat
Solution Approach 1:
The patent removes the traditional bleeder circuit (resistor R1 and switch M2) from the system. Instead of using a dedicated bleeder circuit to provide holding current, the invention extracts the holding current requirement and satisfies it through the converter input current itself, which is already present in the circuit for other purposes.
Solution Approach 2:
The converter input current serves multiple functions simultaneously: it provides power to the LED load and also serves as the holding current for the TRIAC dimmer. This multi-functional approach eliminates the need for separate bleeder circuitry that would otherwise be required.
2Reliability
If a traditional bleeder circuit with resistor R1 and switch M2 is used, then holding current for TRIAC dimmer is provided, but the control circuit becomes complex and system cost increases
Solution Approach 1:
The patent eliminates the bleeder circuit components (resistor R1 and switch M2) entirely from the system. The holding current function is extracted from the separate bleeder circuit and integrated into the existing converter input current path, thereby simplifying the overall circuit architecture.
Solution Approach 2:
The invention merges the holding current function with the existing converter input current path. Instead of having separate bleeder circuitry, the same current path that powers the converter also provides the holding current for the TRIAC dimmer, reducing the number of components and simplifying the control circuit.
3Reliability
If resistor R1 and switch M2 are used to provide holding current, then the TRIAC dimmer can operate, but the LED driver efficiency decreases due to power loss
Solution Approach 1:
The patent removes the inefficient bleeder circuit (resistor R1 and switch M2) that was causing power losses. By extracting this unnecessary component, the system eliminates the associated power dissipation and improves overall LED driver efficiency while maintaining TRIAC dimmer operation.
Solution Approach 2:
The converter input current is made multi-functional, serving both as the primary power source for the LED load and as the holding current for the TRIAC dimmer. This eliminates the need for separate bleeder circuitry that would otherwise dissipate power unnecessarily.
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 solution results in a more efficient, cost-effective, and reliable TRIAC dimmable LED driver with reduced power dissipation and complexity, achieving improved LED driver performance and compatibility.
Implementation Method 1
The rectifier bridge rectifies the input AC voltage and generates a sinusoidal voltage on capacitor C1
Implementation Method 2
The LED load is connected to an inductor or a transformer
Implementation Method 3
employing a source driving scheme with power and low voltage MOS transistors
Implementation Method 4
A peak current comparator is used to compare the voltage between a current sensing resistor and a reference voltage
Implementation Method 5
A maximum on-time timer is used to detect the on time of the low voltage MOS transistor
Data Source
AI summary
A TRIAC dimmable light-emitting diode (LED) driver circuit is disclosed, compromising: An alternating-current (AC) voltage connected to a rectifier bridge; An LED load, which is connected to an inductor or a transformer, a power MOS transistor, a low voltage MOS transistor and a current sensing resistor. The LED driver also compromises: a peak current comparator which is used to compare the voltage between a current sensing resistor and a reference voltage; a maximum on-time timer, which is used to detect the on time of the low voltage MOS transistor. When the voltage on the current sensing resistor is higher than the reference voltage or the on time of the low voltage MOS transistor reaches the preset time of the maximum on-time timer, the low voltage MOS transistor is turned off.