EV Power Module Junction Temperature Sensing via Body Diode
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Solution Overview
Problem
Existing power modules in electric vehicles face inaccuracies in determining the operating temperature of power switches due to the use of spatially separated and electrically isolated temperature sensors, leading to potential overheating and increased protection costs.
Innovation Solution
A power module with a temperature measurement device that directly measures the operating temperature of semiconductor switching elements by analyzing the voltage and current at a diode connected in series, using a method that determines the temperature from a mathematical dependency between measured voltage and current, eliminating the need for indirect temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spatially separated and electrically isolated temperature sensors are used to measure power switch temperature, then the power switches are protected against overheating, but the measurement accuracy is insufficient
Solution Approach 1:
The patent merges the temperature sensing function directly into the power switch structure by utilizing the body diode's voltage characteristics. Instead of using separate temperature sensors, the invention combines temperature measurement capability with the existing power switch component, achieving both accurate measurement and reliable protection.
Solution Approach 2:
The power switch's own body diode is used to provide temperature information about the switch junction. The diode's forward voltage drop, which has a known negative temperature coefficient, serves as an intrinsic temperature sensor, allowing the component to monitor its own temperature without external sensing elements.
2Device complexity
If indirect temperature estimation methods are used, then the measurement setup is simpler, but the accuracy of temperature determination is not high enough
Solution Approach 1:
The invention uses the power switch's intrinsic electrical characteristics (body diode voltage) to determine temperature, eliminating the need for separate temperature sensors and complex measurement setups. This self-service approach maintains simplicity while achieving direct and accurate temperature measurement at the switch junction.
3Ease of manufacture
If temperature sensors are placed at a large distance from the power switches, then the measurement system is easier to implement, but the accuracy of temperature estimate deteriorates
Solution Approach 1:
By integrating the temperature sensing function into the power switch's body diode, the invention eliminates the spatial separation between sensor and measured object. The temperature measurement is performed directly at the switch junction location, achieving both ease of implementation and high measurement accuracy simultaneously.
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 provides a more accurate and direct measurement of semiconductor switching element temperatures, enhancing protection against overheating and reducing costs associated with temperature estimation uncertainties.
Implementation Method 1
A method is proposed for measuring an operating temperature of the semiconductor switching element. To this end, a voltage which is present at a point located on a side of the diode facing away from the semiconductor switching element is measured. Moreover, a load current of the semiconductor switching element is measured. Moreover, a mathematical dependency between the measured voltage and the measured current is ascertained. The operating temperature of the semiconductor switching element can be ascertained from the mathematical dependency
Data Source
AI summary
Method for measuring an operating temperature of a power module (10) that is used for operating an electric vehicle drive, the power module (10) comprising a plurality of semiconductor switching elements (14) and drive electronics (16), wherein the semiconductor switching elements (14) can be switched by the drive electronics (16) in such a way that the semiconductor switching elements (14) allow or interrupt a drain-source current in order to convert the direct current fed into the power module (10) at the input side into an output-side alternating current, wherein the method comprises measurement of a voltage present at a point located on a side of a diode (22) that is connected in series with the semiconductor switching element (14) and that faces away from the semiconductor switching element (14), wherein the method comprises measurement of a drain-source current of the semiconductor switching element (14) that is generated by a current source (18), wherein the method comprises determination of a mathematical dependency between the measured voltage and the measured current.