Power Module Die Junction Temperature Sensing via Gate Voltage
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Solution Overview
Problem
The junction temperature of semiconductor power modules cannot be directly measured due to its theoretical average nature and the encapsulation, which makes traditional methods impossible, and existing methods are intrusive or impractical for industrial use.
Innovation Solution
A method and device that determine the junction temperature of semiconductor power modules by applying a current-limited voltage to the gates of dies during non-conducting states, using a single analogue-to-digital converter to measure the gate voltage, allowing for real-time, non-intrusive temperature determination of individual dies without additional hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional temperature sensing methods are used, then direct temperature measurement is achieved, but the method is impossible due to encapsulation and theoretical average nature of junction temperature
Solution Approach 1:
The patent uses an intermediary parameter (gate voltage Vge during turn-on delay) that can be measured externally and is linearly dependent on junction temperature. This mediator allows indirect measurement of the inaccessible junction temperature through a measurable electrical parameter.
Solution Approach 2:
The patent replaces traditional mechanical/physical temperature sensing methods with an electrical measurement approach. Instead of using physical temperature sensors that would require direct contact with the die, the invention uses electrical characterization (gate voltage measurement during switching) to infer temperature.
2Measurement precision
If intrusive measurement methods are used, then junction temperature can be measured, but the method is not suitable for industrial operation
Solution Approach 1:
The patent utilizes the existing gate driver circuitry and switching operations of the power semiconductor device itself to perform the temperature measurement. The device's own operational characteristics (gate voltage during turn-on delay) are used as the measurement signal, eliminating the need for external intrusive sensors or separate measurement systems.
Solution Approach 2:
The measurement is performed periodically during the natural switching cycles of the power device. By measuring gate voltage during the turn-on delay period of each switching cycle, the system continuously monitors temperature without interrupting normal operation.
3Measurement precision
If individual die temperature measurement is implemented, then individual state of health can be detected, but additional hardware costs increase
Solution Approach 1:
The patent measures each die individually by controlling their switching operations separately. Each die's gate voltage is measured during its own turn-on delay period, allowing individual temperature determination without requiring separate physical sensors for each die.
Solution Approach 2:
The existing gate driver and voltage measurement circuitry serve dual purposes: controlling the power device switching and simultaneously enabling temperature measurement. The same electrical paths used for device operation are utilized for sensing, eliminating the need for dedicated measurement hardware.
4Productivity
If high sampling rate measurement is used, then real-time temperature monitoring is achieved, but hardware cost and complexity increase
Solution Approach 1:
The measurement is synchronized with the periodic switching operation of the power device. By measuring gate voltage during each natural switching cycle, the system achieves continuous temperature monitoring at the switching frequency without requiring high-speed sampling hardware beyond what is already present for device control.
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
Enables reliable, real-time measurement of junction temperature in normal operation, reducing hardware costs and sampling time, while allowing for the detection of individual die anomalies and average temperature measurement across the power module.
Implementation Method 1
A gate driver charges a gate capacitance of the die with a current limited voltage
Implementation Method 2
A gate driver charges a gate capacitance of the die with a current limited voltage and measures a gate voltage of the die
Implementation Method 3
the junction temperature of the die is determined from Vge, as Vge is linearly dependent on temperature during turn-on delay
Data Source
Figure 1a~1b
Figure 2~3a
Figure 3b~4
AI summary
The present invention concerns a method for determining the junction temperature of at least one die of a semiconductor power module, the semiconductor power module being composed of plural dies connected in parallel and switching between conducting and non conductor states according to pattern cycles. The method comprises the steps of: - disabling the conducting of the at least one die during at least a fraction of one switching cycle, - applying a current limited voltage to the gate of the at least one die during a period of time of the cycle wherein the at least one die is not conducting, the resulting voltage excursion having a value that does not enable the die to be conducting, - measuring the voltage at the gate of the die, - deriving from the measured voltage a temperature variation of the junction of the at least one die or the temperature of the junction of the die.