Junction Temperature Estimation in Power Semiconductor Modules
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Solution Overview
Problem
Current methods for determining the thermal resistance of power semiconductor devices are inefficient and inaccurate, often requiring the opening of encapsulated modules for external temperature measurements, which can damage the devices and rely on complex or expensive equipment.
Innovation Solution
A system and method using a constant current source, adjustable gate voltage source, and sensors to apply a constant drain current and measure drain-source voltage, allowing for closed-loop control to stabilize heat energy loss and calculate thermal resistance without external sensors, enabling precise junction temperature estimation within encapsulated modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external temperature sensors or infrared cameras are used to measure die temperatures, then temperature measurement capability is improved, but the device complexity increases and the semiconductor device must be opened or encapsulation removed
Solution Approach 1:
The patent replaces mechanical/physical temperature measurement systems (external sensors, infrared cameras) with an electrical measurement system that uses the semiconductor device's own electrical parameters. By measuring drain-source voltage and using the relationship between voltage and temperature, the system eliminates the need for external temperature sensing equipment while maintaining measurement capability.
Solution Approach 2:
The semiconductor device serves its own temperature measurement function by utilizing its inherent electrical characteristics. The drain-source voltage of the device changes with temperature, allowing the device to provide its own temperature information without requiring separate measurement systems or opening the encapsulation.
2Ease of manufacture
If conventional methods with predefined power supply are used to generate heat energy loss rate, then the measurement process is simplified, but the heat transfer capability determination becomes inaccurate under varying operational parameters
Solution Approach 1:
The patent transitions from static predefined power supply methods to dynamic operational parameter control. By controlling the gate-source voltage and measuring drain current, the system can dynamically adjust the power semiconductor device's operating state to generate the desired heat energy loss rate, ensuring accurate heat transfer capability determination under various operational conditions.
Solution Approach 2:
The system uses feedback control by measuring the drain-source voltage and comparing it with a reference value. The gate-source voltage is adjusted based on this feedback to maintain the desired operating conditions, ensuring accurate and consistent heat energy loss rate generation for reliable thermal resistance measurement.
3Measurement precision
If the power semiconductor device is opened or encapsulation is removed for thermal characterization, then temperature measurement access is improved, but the semiconductor device becomes inoperable or destroyed
Solution Approach 1:
The patent replaces physical access methods (opening encapsulation, attaching external sensors) with electrical measurement through existing terminals. By measuring electrical parameters like drain-source voltage that inherently change with temperature, the system obtains temperature information without any physical intervention that would damage or render the device inoperable.
Solution Approach 2:
The semiconductor device provides its own temperature measurement capability through its electrical characteristics. The drain-source voltage naturally varies with junction temperature, allowing the device to serve its own thermal characterization needs while remaining fully encapsulated and operational.
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 allows for efficient and accurate determination of thermal resistance and junction temperatures within encapsulated power semiconductor modules without damaging them, using only thermo-sensitive electrical parameters and eliminating the need for external sensors or complex equipment.
Implementation Method 1
Generating a predictable heat energy loss rate conventionally involves supplying a gate-source voltage in the linear operation regime of the power semiconductor device
Implementation Method 2
a constant current source configured to apply a constant drain current to a drain terminal of the power semiconductor device
Implementation Method 3
determine characteristic parameters of such heat transfer capabilities in order to plan and design power electronics equipment properly
Data Source
AI summary
A system for estimating junction temperatures of a power semiconductor module includes a constant current source to apply constant drain current to a drain terminal of a power semiconductor device, an adjustable gate voltage source to apply a gate voltage signal to a gate terminal, a drain-source voltage sensor between the drain terminal and the source terminal and configured to measure a value of the current drain-source voltage across the power semiconductor device and output a corresponding drain-source voltage signal, a gate controller to determine a difference between the drain-source voltage signal and a constant reference voltage and control output of the adjustable gate voltage source dependent on the determined difference, and a system controller to switch the power semiconductor device to its fully conducting state and to estimate junction temperature within the power semiconductor device in dependency from the on-state resistance in the fully conducting state.