Load Compensation Circuit for Electronic Transformer Startup
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Solution Overview
Problem
Electronic transformers in LED illumination systems face challenges in starting up properly due to low input power levels, which can lead to operational failures, unlike halogen lamps that provide a resistive load and do not experience similar issues.
Innovation Solution
A transformer load compensation circuitry is coupled to the output of an electronic transformer, using a bridge rectifier for full-wave rectification and sensing the rectified AC supply to compensate the load, ensuring the transformer starts up and operates correctly even when the signal envelope is below a threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If LED power consumption is reduced to achieve energy efficiency, then power consumption decreases, but electronic transformer startup reliability deteriorates
Solution Approach 1:
The load compensation circuit is activated during the startup phase to provide preliminary assistance. It generates a compensation current that mimics the inrush current characteristics, enabling the transformer to start up properly before the LED driver reaches its normal operating current level.
Solution Approach 2:
The load compensation circuit acts as an intermediary between the LED driver and the transformer. It introduces a virtual load that compensates for the insufficient real load during startup, bridging the gap between the low-power LED operation and the transformer's startup requirements.
2Use of energy by moving object
If LED operating current is limited to maintain energy efficiency, then energy consumption decreases, but transformer current ramp-up rate deteriorates
Solution Approach 1:
The load compensation circuit operates periodically during each AC cycle, activating when the transformer current needs boosting and deactivating when the LED driver current is sufficient. This periodic intervention maintains fast ramp-up rates without continuously increasing power consumption.
Solution Approach 2:
The compensation circuit dynamically adjusts the load current parameter based on the transformer's operating state. By varying the compensation current magnitude and duration, it accelerates the current ramp-up rate during critical phases while maintaining low overall energy consumption.
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 enables proper startup and operation of the electronic transformer by providing additional power through the load compensation circuitry, enhancing the slew rates at the leading edges of the LED driver and transformer currents, ensuring consistent power delivery to LEDs and maintaining system functionality.
Implementation Method 1
a bridge rectifier provides full-wave rectification to the second AC supply
Implementation Method 2
The electronic transformer, coupled to a power outlet, converts a first AC supply to a second AC supply that is contained within a signal envelope, and the frequency of the signal envelop is substantially equal to that of the first AC supply
Data Source
AI summary
The invention relates to a light emitting diode (LED) illumination system, and more particularly, to systems, devices and methods of rapidly ramping up a transformer current and a LED driver current by coupling a transformer load compensation circuitry to an output of an electronic transformer. A bridge rectifier is coupled to the electronic transformer and provides full-wave rectification to an AC supply at the output of the electronic transformer. The load compensation circuitry senses the rectified AC supply and compensates the load of the electronic transformer, such that the electronic transformer starts up properly when the level of the signal envelope is below a threshold voltage. Therefore, the load compensation circuit is active for a programmed time during which the LED driver current has been increased to a sufficient value to keep the electronic transformer operational.