Isolated LED Converter Startup Using a Battery-Fed Secondary Controller
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Solution Overview
Problem
Existing isolated DC-DC converters require two controllers, leading to high power consumption, complexity, and cost due to the need for a primary-side controller and additional isolation transformers to supply the secondary-side controller, which is impractical and expensive.
Innovation Solution
A primary-side switched, isolated converter with a secondary-side controller that uses a start-up circuitry powered by a battery to supply the secondary-side controller, eliminating the need for a primary-side controller and reducing complexity by using an optocoupler or transformer for isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary-side controller is used to control the isolated converter, then the converter can operate properly with galvanic isolation, but the device complexity and power consumption increase due to requiring an additional controller
Solution Approach 1:
The invention extracts the control function from the primary side and relocates it to the secondary side. The secondary-side controller alone controls both the primary-side switch and secondary-side elements, eliminating the need for a separate primary-side controller while maintaining proper converter operation and galvanic isolation through the transformer coupling
Solution Approach 2:
The transformer serves as an intermediary that enables control signals to be transmitted from the secondary side to the primary side. The secondary-side controller generates control signals that are coupled through the transformer to drive the primary-side switch, allowing indirect control across the galvanic isolation barrier
2Reliability
If a primary-side controller is used, then the converter can be controlled properly, but the power consumption increases due to multiple controllers operating simultaneously
Solution Approach 1:
By extracting the control function to a single secondary-side controller, the invention eliminates the power consumption associated with a separate primary-side controller. Only one controller needs to operate, significantly reducing total power consumption while maintaining proper converter control
Solution Approach 2:
The secondary-side controller performs multiple functions: it controls the primary-side switch through transformer coupling, manages secondary-side switching elements, and regulates the overall converter operation. This multi-functionality consolidates control tasks into a single controller, reducing power consumption
3Ease of operation
If an additional transformer is used to supply the secondary-side controller, then the controller can be powered during start-up, but the device complexity and cost increase
Solution Approach 1:
The invention makes the existing transformer serve a dual function: it provides galvanic isolation for power conversion and simultaneously supplies power to the secondary-side controller during start-up and operation. This eliminates the need for an additional dedicated transformer for controller power supply
Solution Approach 2:
The transformer serves itself by providing power to the controller that enables it to generate the control signals that in turn control the transformer's primary-side switch. The system uses its own existing components to enable controller operation without requiring external or additional dedicated components
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
Reduces power consumption, complexity, and cost by integrating the primary-side and secondary-side controllers into a single controller, while using existing battery energy for start-up, thus eliminating the need for additional transformers.
Implementation Method 1
a start-up signal transmitted from the primary-side to the secondary-side via an isolation stage of the converter
Implementation Method 2
using an optocoupler or transformer for isolation
Data Source
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AI summary
The invention relates to a primary-side switched, isolated converter for supplying an LED load, having: a primary-side having terminals for supplying a mains voltage, a secondary-side controller arranged on a secondary-side of the isolated converter, wherein the secondary-side controller is configured to issue a control signal for a primary-side switch of the switched isolated converter, a secondary-side circuitry on the secondary-side of the converter comprises: terminals configured to directly or indirectly supply the LED load, and a battery configured to supply the secondary-side circuitry, and a start-up circuitry configured to supply the secondary-side controller off the battery, wherein the start-up circuitry has a control terminal for supplying a start-up signal transmitted from the primary-side to the secondary-side via an isolation stage of the converter.