Reverse Recovery Charge Measurement Isolating Parasitic Inductance
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Solution Overview
Problem
Existing measurement methods for reverse recovery charge in semiconductor elements with diode components are inaccurate due to parasitic inductance effects, leading to excessive measurement of reverse recovery charge, especially at higher current change rates and parasitic inductance levels.
Innovation Solution
A measurement device and method that adjust variable inductance to determine the true reverse recovery charge by establishing relationships between parasitic inductance, current change rate, and measured charge, isolating the parasitic inductance-independent true value by identifying saturated parasitic inductance and current change rates, and using these to correct for parasitic inductance-induced oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If parasitic inductance is present in the measurement device, then the measurement can be performed, but the measured reverse recovery charge becomes excessively large due to oscillation
Solution Approach 1:
The patent converts the harmful parasitic inductance effect into a useful measurement tool by deliberately adding a variable inductance component. By measuring at multiple inductance values and analyzing how the measured charge changes with inductance, the method extracts the true reverse recovery charge independent of inductance effects. The harmful oscillation behavior is transformed into a characteristic that enables separation of parasitic effects from the actual device under test parameters.
Solution Approach 2:
The patent changes the inductance parameter of the measurement device systematically. By varying the inductance value and observing the corresponding changes in measured reverse recovery charge, the method establishes a relationship between inductance and measurement error. This parameter variation enables the identification and compensation of parasitic inductance effects, leading to accurate extraction of the true reverse recovery charge.
2Productivity
If current change rate is increased to improve measurement speed, then measurement efficiency improves, but parasitic inductance effects become more significant causing larger measurement errors
Solution Approach 1:
The patent implements a feedback mechanism where the measured reverse recovery charge values at different inductance levels are used to calculate the saturated current change rate. This calculated rate then serves as feedback to determine the appropriate measurement conditions and extract the true reverse recovery charge. The feedback loop enables continuous optimization of measurement accuracy while maintaining efficient measurement speeds.
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
Accurately measures the reverse recovery charge by isolating the true value independent of parasitic inductance, ensuring precise characterization of semiconductor elements.
Implementation Method 1
a variable inductance connected in series with a semiconductor element in a circuit
Data Source
AI summary
A measurement method includes determining a first relationship by measuring a reverse recovery charge of a semiconductor element at a plurality of conditions of a measurement device. The measurement device has mutually-different parasitic inductances at the plurality of conditions. The semiconductor element includes a diode component. The first relationship is between the parasitic inductance and a measured value of the reverse recovery charge. The method includes estimating a true value of the reverse recovery charge when the parasitic inductance is zero based on the first relationship.