Buck Converter Inductor Current Sensing Without Isolation Transformer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional buck converters for LED lighting require an isolation transformer to sense and control the switch, increasing cost, size, and complexity.
Innovation Solution
A buck converter design that eliminates the isolation transformer by using a primary inductor and a primary inductor current integrator circuit to sense current and control the switch directly, allowing the controller to manage the switch's on and off states without the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an isolation transformer is used to sense current and control the switch, then the controller can sense the average current through the load, but the cost, size, and complexity of the converter increase
Solution Approach 1:
The patent extracts and eliminates the isolation transformer from the conventional buck converter circuit. By removing this component, the design achieves current sensing and switch control without the complexity, cost, and size associated with transformer-based isolation, while maintaining the essential control functionality through alternative sensing methods.
Solution Approach 2:
The patent makes the controller perform multiple functions without requiring an isolation transformer. The controller directly senses current through the primary inductor and controls the switch, combining sensing and control functions in a single integrated approach that eliminates the need for separate transformer-based isolation.
2Ease of operation
If an isolation transformer is used to sense current and control the switch, then the controller can be referenced to ground, but the cost and size of the converter increase
Solution Approach 1:
The patent removes the isolation transformer from the circuit, thereby reducing the quantity of physical components. The controller is redesigned to operate without transformer-based ground reference, achieving ground referencing through alternative circuit topology that uses fewer components overall.
Solution Approach 2:
The patent merges the functions of current sensing and ground referencing into a single integrated approach. The controller senses current and maintains ground reference simultaneously without requiring separate transformer components, combining multiple functions into a streamlined circuit design.
3Extent of automation
If an isolation transformer is used in the buck converter, then the switch can be controlled, but the complexity of the converter increases
Solution Approach 1:
The patent extracts the isolation transformer from the switch control path. The switch control is achieved directly through the controller without requiring transformer-based isolation, simplifying the circuit while maintaining automated switch control capability through alternative sensing and control mechanisms.
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 design reduces the cost, size, and complexity of the converter while maintaining consistent current delivery to the LED light source, enhancing efficiency and reliability.
Implementation Method 1
The primary inductor current integrated circuit senses current through the primary inductor, provides a primary inductor current signal indicative of the current through the primary inductor, and induces, in the primary inductor, a current equal to an integral of the sensed current through the primary inductor
Data Source
AI summary
A light fixture includes a converter operable to drive a light source of the light fixture. The buck converter is operable to provide a predetermined average current to the light source or load. A switch of the buck converter is located in the low side of the buck converter such that a controller of the buck converter may drive the switch directly without the use of an isolation transformer. The buck converter controls operation of the switch based on current through the switch and current through the primary inductor of the buck converter.