Inductor Core Loss Measurement Using Series Resonance
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Solution Overview
Problem
Current techniques for measuring core losses in inductors and transformers are inadequate, particularly at high frequencies, due to sensitivity to phase discrepancies and difficulties in estimating winding losses, which hinders the development of optimal core designs for power circuits.
Innovation Solution
A method involving a series resonant circuit with a reactive component to cancel a portion of the magnetizing inductance voltage, allowing for accurate measurement of core losses by integrating the measured voltage and current with a phase difference less than 80°, reducing measurement errors caused by phase discrepancies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement techniques are used for core losses, then measurement can be performed, but measurement precision deteriorates due to sensitivity to phase discrepancies and difficulty in estimating winding losses
Solution Approach 1:
The patent extracts and separately measures winding losses using a dedicated measurement circuit, then subtracts them from the total loss measurement. This isolates the core loss component from the problematic phase sensitivity issues that affect total loss measurements, thereby improving core loss measurement precision.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using a separate winding loss measurement circuit as a mediator. This intermediary measurement allows the determination of core losses through subtraction, bypassing the direct measurement problems caused by phase discrepancies in conventional single-circuit methods.
2Productivity
If high frequency switching is used to meet size and power density requirements, then productivity and power density improve, but measurement precision deteriorates due to increased phase discrepancy sensitivity
Solution Approach 1:
The patent segments the loss measurement into two separate measurements: total loss measurement and winding loss measurement. By dividing the measurement process, it enables accurate core loss determination at high frequencies where conventional single-measurement approaches fail due to phase sensitivity.
Solution Approach 2:
The patent performs an additional measurement (winding loss measurement) beyond the conventional single total loss measurement. This excessive action of measuring twice allows for accurate core loss extraction through subtraction, overcoming the limitations of high frequency operation.
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 approach provides accurate core loss measurements with reduced error, supporting the optimization of inductor and transformer core designs, even at high frequencies, and aligns well with datasheet values for commercial materials.
Implementation Method 1
resonating a winding of the inductor or transformer with a reactive component in a series resonant circuit with the winding to cancel a portion of a reactive voltage of a magnetizing inductance
Data Source
AI summary
Core loss in an inductor is measured with reduced sensitivity to phase measurement error by connecting a reactive component to resonate with the inductor and thus cancel a portion of the reactive voltage on the inductor; reducing the phase difference between the inductor voltage and current and making the observed power more resistive. The reactive component may be a capacitor for sinusoidal excitation or an inductance such as an air core transformer for arbitrary excitation.