Temperature measurement of a power semiconductor switching element
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Solution Overview
Problem
Existing methods for determining the temperature of semiconductor power switching elements are inaccurate due to dependence on current intensity, which is a concern for reliable operation, especially in engine control units.
Innovation Solution
A device with a non-inverting amplifier circuit and a temperature-dependent gate resistor is used, where the gain of the amplifier in a specific frequency range is a measure of the temperature, independent of current intensity, allowing precise temperature measurement of the semiconductor power switching element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current intensity-dependent temperature measurement methods are used, then temperature can be measured, but measurement precision deteriorates due to current intensity variations
Solution Approach 1:
The patent extracts the temperature measurement function from the power switching element itself by using a separate measurement circuit. The measurement circuit includes a measurement amplifier connected to the gate resistor, allowing temperature measurement without requiring current flow through the power element. This separates the measurement function from the power function, eliminating current intensity dependency and improving both measurement precision and reliability.
Solution Approach 2:
The patent uses the gate resistor as an intermediary element for temperature measurement. The gate resistor, which is inherently present in the power switching element, serves as a temperature sensor. By measuring the voltage across the gate resistor through the measurement amplifier, the system obtains temperature information without requiring the gate resistor to carry switching current, thus eliminating the conflict between power function and measurement function.
2Measurement precision
If temperature measurement is performed during switching operation, then operational temperature can be monitored, but measurement accuracy deteriorates due to current intensity interference
Solution Approach 1:
The patent extracts the measurement function from the power switching path by using a separate measurement circuit with a measurement amplifier. This allows temperature measurement to be performed independently of the switching current, eliminating current intensity interference while maintaining the ability to monitor operational temperature.
Solution Approach 2:
The measurement circuit can be activated periodically or continuously during switching operation without affecting the power function. The measurement amplifier samples the voltage across the gate resistor at appropriate times, allowing temperature monitoring during operation without current interference, as the measurement draws negligible current compared to the switching current.
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 method provides accurate and reliable temperature measurement of semiconductor power switching elements, specifically the junction temperature, independent of current intensity, enhancing their operational reliability.
Implementation Method 1
a temperature-dependent gate resistor is used, where the gain of the amplifier in a specific frequency range is a measure of the temperature, independent of current intensity
Implementation Method 2
A device with a non-inverting amplifier circuit and a temperature-dependent gate resistor is used, where the gain of the amplifier in a specific frequency range is a measure of the temperature
Data Source
AI summary
A device for determining a temperature of a semiconductor power switch with a built-in temperature-dependent gate resistor may include a non-inverting amplifier circuit comprising an operational amplifier and a feedback resistor. Inverting input of the operational amplifier may be connected to the semiconductor power switch such that a gain of the non-inverting amplifier circuit in a predefined frequency range of an input signal depends on the built-in temperature-dependent gate resistor and the feedback resistor and is a measure of the temperature of the semiconductor power switch. The feedback resistor may be disposed between a negative input and an output of the operational amplifier.