Power Module Junction Temperature Estimation Without Full Sensor Arrays
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Solution Overview
Problem
Existing temperature determination methods for power modules in motor driving systems rely heavily on water temperature sensors, which are not always effective in determining junction temperatures, especially when direct detection is impossible, and can lead to reduced durability and performance due to temperature management limitations.
Innovation Solution
A temperature determination device that includes a first temperature sensor in some switching elements to measure temperatures, a water temperature estimation unit to calculate the temperature increase based on operation information and influence coefficients, and a junction temperature determination unit to estimate junction temperatures, reducing dependence on water temperature sensors and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If water temperature sensors are used to determine junction temperature, then temperature management is simplified, but measurement precision deteriorates when direct junction detection is impossible
Solution Approach 1:
The patent introduces an intermediary estimation mechanism that uses water temperature as a baseline and adds temperature increase values calculated from switching element operation information. This intermediary approach bridges the gap between easy-to-measure water temperature and the desired precise junction temperature, resolving the contradiction between simplicity and precision.
Solution Approach 2:
The patent replaces direct physical temperature sensors on switching elements with a computational estimation system. Instead of mechanically installing sensors on each switching element (which would be complex), the system substitutes a calculation-based approach using operation information and influence coefficients, achieving precision without the mechanical complexity.
2Measurement precision
If temperature sensors are installed on all switching elements, then junction temperature measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts the temperature sensing function from physical sensors and relocates it to a computational estimation process. By taking out the need for physical sensors on each switching element and replacing it with calculation based on operation information, the system achieves measurement precision without the complexity of extensive sensor installation.
Solution Approach 2:
The patent creates a virtual copy of temperature measurement through estimation rather than physical measurement. The estimation unit generates virtual temperature data based on operation information and influence coefficients, serving as a copy of what physical sensors would measure, thereby avoiding the complexity of actual sensor installation while maintaining measurement precision.
3Reliability
If direct junction temperature detection is implemented for all switching elements, then reliability is improved, but manufacturing cost increases due to increased sensor dependencies
Solution Approach 1:
The patent replaces expensive, durable physical temperature sensors with a low-cost computational estimation approach. The estimation unit uses readily available operation information and preset influence coefficients to generate reliable temperature data without requiring expensive sensor hardware, thereby improving reliability while reducing manufacturing cost.
Solution Approach 2:
The system enables the power module to self-determine its junction temperature using its own operation information and preset coefficients, without relying on external sensors. This self-service capability achieves reliable temperature monitoring while eliminating the need for additional sensor components, reducing manufacturing cost.
Data Source
AI summary
Provided is a temperature determination device for a power module, including a water temperature estimation unit configured to determine a temperature increase in each of switching elements based on operation information of the switching elements and to determine an estimated temperature of cooling water based on an influence coefficient preset to correspond to each of remaining switching elements that are not provided with the first temperature sensor and the temperature increase, and a junction temperature determination unit configured to determine a junction temperature based on the estimated water temperature.