Current Sensing for Coupled Inductors in Multi-Phase Power Converters
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Solution Overview
Problem
Current current sensing techniques for coupled inductors in switching regulator circuits either provide incomplete information or are overly complex, making them impractical for real-world implementation in power converter designs.
Innovation Solution
A current sensing technique using a simple RC network with two resistors and two capacitors for 2-phase operation, which can be extended to multi-phase configurations like DrMOS modules to provide complete current information, including peak, valley, and intermediate ripples, enhancing signal-to-noise ratio for reliable control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional current sensing techniques are used for coupled inductors, then the circuit can operate, but the current information obtained is incomplete or the sensing circuit becomes overly complex
Solution Approach 1:
The patent merges the current sensing function into the existing RC network that is already present in the power converter circuit. By utilizing the interaction between the RC network and the coupled inductor windings, the circuit simultaneously performs its original function and provides complete current information through voltage measurements at existing nodes, eliminating the need for separate sensing circuits.
Solution Approach 2:
The patent uses the voltage across the capacitor in the RC network as an intermediary signal that contains complete current information about the coupled inductor. This voltage measurement serves as a mediator that translates the magnetic coupling between windings into usable current data without requiring direct current measurement or additional complex sensing circuitry.
2Device complexity
If simple sensing circuits are used, then the device complexity is reduced, but the signal-to-noise ratio deteriorates
Solution Approach 1:
The patent makes the existing RC network serve dual purposes: its original timing/filtering function and current sensing function. The capacitor voltage, which already exists in the circuit for other purposes, automatically provides complete current information when the circuit operates, requiring no additional components or complex signal processing to achieve high signal-to-noise ratio.
3Measurement precision
If separate sensing circuits are implemented for each winding, then complete current information is obtained, but the number of components increases
Solution Approach 1:
The patent combines multiple sensing functions into a single RC network. The interaction between the coupled inductor windings and the shared RC network allows one set of components (one resistor and one capacitor) to provide complete current information for both windings, eliminating the need for separate sensing circuits for each winding.
Solution Approach 2:
The RC network is designed to perform multiple functions simultaneously: it provides timing control, signal filtering, and complete current sensing for both coupled inductor windings. This multi-functionality reduces the total component count while maintaining complete measurement capability.
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 proposed technique effectively senses and provides complete current information for power converter design and protection, improving efficiency and reliability in switching regulator circuits, particularly in multi-phase operations.
Implementation Method 1
a first capacitor coupled between the first resistor and a first sensing node... receive a first voltage across the first capacitor, wherein the first voltage represents a current through the first winding
Implementation Method 2
a first resistor coupled to receive a signal representing voltage information at an input of the first winding
Data Source
AI summary
A current sensing technique for coupled inductors in switching regulator circuits, where the current sensing technique can provide the current information needed for a power converter design and can be implemented as a real-world solution. The current sensing techniques can provide complete information of the coupled inductor current, such as peak current, valley current, and intermediate ripples. The current sensing techniques can use a simple RC network, such as two resistors and two capacitors for 2-phase operation. The techniques, however, are not limited to two-phase operation. The current sensing techniques of this disclosure can be extended to power stage assembly implementations, e.g., DrMOS modules, with current output in order to increase signal-to-noise ratio, which is significant for reliable control. In addition, the current sensing techniques of this disclosure can be extended to multi-phase operation, such as three or more phases.