Curie Temperature Transformer for Isolated LED Driver Thermal Protection
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Solution Overview
Problem
Existing LED power sources lack electrical isolation and effective thermal management, particularly in applications where grounding is necessary and overheating is a concern.
Innovation Solution
A self-oscillating DC-DC converter with isolated supply-side and load-side ground connections, a boost converter with power factor correction, and a control transformer with a Curie temperature core to prevent overheating, ensuring electrical isolation and thermal protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical isolation is implemented between LED array and input power supply, then safety is improved, but device complexity increases
Solution Approach 1:
A transformer is introduced as an intermediary component between the input power supply and LED array to provide galvanic isolation. The transformer couples the primary and secondary circuits magnetically without direct electrical connection, thereby achieving safety isolation while maintaining power transfer functionality.
Solution Approach 2:
The power supply circuit is segmented into isolated primary and secondary sides by the transformer. The primary side handles input rectification and power factor correction, while the secondary side provides isolated output to the LED array, allowing independent grounding on each side for enhanced safety.
2Reliability
If thermal management measures are added to prevent overheating, then reliability is improved, but device complexity increases
Solution Approach 1:
The transformer core utilizes its inherent Curie temperature property for automatic thermal protection. When the core temperature exceeds the Curie point, the magnetic permeability drops sharply, causing the inductance to decrease and limiting further power transfer, thereby preventing overheating without requiring external thermal management components.
Solution Approach 2:
The transformer core material is selected with a specific Curie temperature that corresponds to the maximum operating temperature of components in the power source. This parameter change in the core material's magnetic properties at the Curie point provides passive thermal protection.
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
The solution provides reliable electrical isolation and self-protection against overheating, enabling safe and efficient power delivery to LED arrays while maintaining desired brightness control.
Implementation Method 1
The transformer in some embodiments has a core made of a material having a Curie temperature associated with a maximum operating temperature of a component in the power source, where the control transformer reduces the inductance of the secondary windings when the core temperature exceeds the Curie temperature to prevent the power source from overheating.
Implementation Method 2
The power source includes an input rectifier which receives an input AC voltage signal and produces an initial DC voltage
Implementation Method 3
The output rectifier is coupled with the load-side ground connection and receives the intermediate AC signal from which it produces an output DC voltage
Data Source
AI summary
Isolated LED power sources and DC-DC converters therefor are presented in which the DC-DC converter includes a self-oscillating inverter driving an output rectifier for operating an LED array of one or more LEDs, where the inverter uses a control transformer with core having a Curie temperature set to a maximum operating temperature of one or more power supply components to reduce inductances of secondary windings in the inverter oscillation circuitry to lower the power supplied to the load so as to prevent the inverter from overheating.