Power Module Junction Temperature Estimation Without Diode Sensors
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Solution Overview
Problem
Conventional methods for estimating the junction temperature of power semiconductor devices without embedded temperature sensors are inaccurate, particularly when coolant supply abnormalities occur, leading to potential overheating and reduced endurance life.
Innovation Solution
A method and system that utilize a first power semiconductor device with a temperature sensor and a second device without a sensor, computing junction temperature prediction values based on power loss and thermal resistance, and deriving the heat sink temperature to accurately estimate the junction temperature of the second device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coolant temperature sensor is installed at the inlet of the coolant passage to measure coolant temperature, then the measurement system is simple and cost-effective, but the junction temperature estimation becomes inaccurate when coolant supply abnormalities occur
Solution Approach 1:
The patent introduces an intermediary approach by using the temperature sensor embedded in the first power semiconductor device (IGBT) to indirectly estimate the heat sink temperature, which then serves as a basis for estimating the junction temperature of the second power semiconductor device (diode) that lacks an embedded sensor. This mediator (heat sink temperature derived from IGBT data) bridges the gap between available sensor data and the required temperature information.
Solution Approach 2:
The patent creates a thermal model that copies the thermal behavior characteristics from the first power semiconductor device (with embedded sensor) to the second power semiconductor device (without embedded sensor). By measuring the temperature gradient between junction and heat sink in the first device, the system replicates this relationship to estimate the junction temperature of the second device, effectively creating a virtual temperature sensor for the diode.
2Reliability
If only the first power semiconductor device (IGBT) has an embedded temperature sensor, then the device complexity is reduced and cost is lowered, but the junction temperature of the second device (diode) cannot be accurately detected when coolant supply abnormalities occur
Solution Approach 1:
The patent makes the embedded temperature sensor in the first power semiconductor device serve multiple functions: it not only monitors the temperature of the IGBT itself but also enables estimation of the heat sink temperature and subsequently the junction temperature of the second power semiconductor device. This multi-functionality allows a single sensor to provide comprehensive thermal monitoring for the entire power module.
Solution Approach 2:
The system copies the thermal relationship model from the first power semiconductor device to the second device. By establishing the temperature gradient relationship between junction and heat sink in the IGBT, the system replicates this model to infer the diode's junction temperature, effectively extending the sensing capability without adding physical sensors.
3Measurement precision
If conventional thermal models use only coolant temperature for estimation, then the estimation process is simple, but the junction temperature prediction fails to reflect actual temperature increases when coolant is not properly transferred
Solution Approach 1:
The patent implements feedback by continuously monitoring the temperature difference between the first power semiconductor device junction and the heat sink, and using this information to dynamically adjust and refine the heat sink temperature estimation. This feedback mechanism ensures that the thermal model adapts to actual operating conditions, including coolant supply abnormalities, improving the accuracy of junction temperature predictions for both devices.
Solution Approach 2:
The system performs preliminary action by pre-establishing thermal relationship models and temperature gradient characteristics during normal operation. These pre-characterized thermal parameters are stored and later used to rapidly estimate temperatures during abnormal conditions, enabling quick and accurate temperature prediction without requiring complex real-time calculations during critical events.
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 improves the accuracy of junction temperature prediction for power semiconductor devices without embedded sensors, preventing overheating and extending their operational life by accurately detecting temperature anomalies.
Implementation Method 1
a first power semiconductor device disposed adjacent to a heat sink for cooling and having a temperature sensor
Implementation Method 2
a heat sink for cooling
Implementation Method 3
adjacent to a heat sink for cooling
Data Source
AI summary
A method for estimating the junction temperature of the power semiconductor device of the power module is provided. The method includes computing a junction temperature prediction value of the first power semiconductor device based on a power loss and a thermal resistance of the first power semiconductor device and computing a junction temperature prediction value of the second power semiconductor device based on a power loss and a thermal resistance of the second power semiconductor device. A temperature prediction value of the heat sink is computed by subtracting the junction temperature prediction value of the first power semiconductor device from a sensing temperature sensed by the temperature sensor. The junction temperature of the second power semiconductor device is then finally determined by adding the temperature prediction value of the heat sink to the junction temperature prediction value of the second power semiconductor device.