Gate Resistance Measurement Circuit Using Resonant Sine-Wave Sampling
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Solution Overview
Problem
Existing methods for detecting gate resistance in high breakdown voltage semiconductor switching devices are prone to errors due to parasitic inductance and capacitance, leading to inaccurate temperature estimation and device life prediction.
Innovation Solution
An electronic circuit comprising a current supply circuit, detection circuit, timing generation circuit, sample hold circuit, and calculation circuit is used to input a sine wave current with a frequency matching the resonant frequency of parasitic components, allowing for accurate detection of gate resistance and temperature by eliminating the influence of parasitic inductance and capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sine wave current is input to detect gate voltage, then gate resistance can be detected, but frequency component leaks into detection circuit output causing measurement error
Solution Approach 1:
The detection process is divided into multiple sampling points within one period of the sine wave current. By sampling at specific timing (when the current passes through zero or at peak points), the measurement separates the gate resistance component from the frequency component leakage, enabling accurate extraction of gate resistance value.
Solution Approach 2:
A timing generation circuit is introduced as an intermediary component that generates sampling timing signals based on the sine wave current period. This timing signal controls when sampling occurs, acting as a mediator between the sine wave input and the detection circuit to eliminate frequency component interference.
2Measurement precision
If pulse current is input to measure gate voltage, then gate resistance can be calculated, but parasitic inductance causes large ringing making accurate calculation difficult
Solution Approach 1:
Instead of using a single pulse current, the invention uses a periodic sine wave current to excite the gate. This periodic excitation allows the system to operate at or near the resonant frequency of the parasitic L-C circuit, transforming the harmful ringing into a predictable resonant response that can be accurately measured and used to determine gate resistance.
Solution Approach 2:
The invention changes the excitation parameter from a sharp pulse (high rise time) to a sine wave with controlled frequency and amplitude. By adjusting the sine wave frequency to match the resonant frequency of the parasitic components, the measurement process transforms the problematic ringing into a stable oscillatory response that facilitates accurate gate resistance calculation.
3Measurement precision
If output resistance of current source causes error in gate current value, then gate resistance calculation becomes inaccurate
Solution Approach 1:
The detection circuit measures the actual sine wave current that flows through the gate and uses this feedback information to calculate the gate resistance. By continuously monitoring the current and adjusting the calculation based on the actual current value (rather than assuming a fixed current), the system compensates for errors introduced by the current source's output resistance.
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 enables precise calculation of gate resistance and temperature, reducing errors and improving the accuracy of semiconductor switching device life prediction.
Implementation Method 1
inputting a sine wave current to a gate terminal to detect a gate voltage generated at the gate terminal, and calculating a gate resistance based on the detected gate voltage. The influence of parasitic inductor and parasitic capacitor can be ignored by inputting the sine wave current having the same frequency as a resonant frequency determined by the parasitic inductor and the parasitic capacitor of the gate electrode.
Data Source
AI summary
According to one embodiment, an electronic circuit includes: a current supply circuit, a detection circuit, a timing generation circuit, a sample hold circuit and a calculation circuit. The current supply circuit supplies a sine wave current for measurement to a gate terminal of a semiconductor switching device. The detection circuit detects a sine wave voltage generated in response to supply of the sine wave current to generate a detection signal. The timing generation circuit counts cycles of the sine wave voltage. The sample hold circuit samples the detection signal at a timing depending on a count value of the timing generation circuit. The calculation circuit calculates a gate resistance of the semiconductor switching device based on the sampled voltage.