Semiconductor Temperature Estimation via Switching Noise
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Solution Overview
Problem
Existing techniques for measuring the Miller plateau phase of IGBT devices require high-speed measurement circuits with good RF characteristics and necessitate individual detection circuits for each device, leading to complex and large-scale circuitry, especially for systems with multiple IGBTs.
Innovation Solution
An electric device with a drive circuit, a detector for high-frequency switching noise, and a deviation time measurement unit that estimates semiconductor element temperature based on the difference between control signal timing and switching noise detection, using a relationship storage unit to correlate deviation time with element temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual measurement circuits are used for each IGBT device to detect the Miller plateau phase, then the measurement precision is improved, but the device complexity increases significantly
Solution Approach 1:
The patent merges the measurement functions for multiple IGBT devices into a single shared measurement circuit. The circuit captures switching noise from multiple devices simultaneously through a common current path, and the control unit processes signals from multiple devices using one measurement circuit, thereby reducing circuit complexity while maintaining measurement capability
Solution Approach 2:
The measurement circuit is designed with universal functionality to handle multiple IGBT devices. The current sensor and measurement circuit can detect switching noise from any connected IGBT device, and the control unit can identify and process Miller plateau phases from multiple devices through signal analysis, making the circuit adaptable to different device configurations
2Measurement precision
If high-speed measurement circuits with good RF characteristics are used to detect the Miller plateau phase, then the measurement precision is improved, but the device complexity and circuit scale increase
Solution Approach 1:
The patent replaces complex high-speed RF measurement circuits with a simpler approach based on detecting switching noise through current sensing. Instead of using sophisticated RF measurement infrastructure, the system uses a current sensor to detect noise signals and a control unit to process them, substituting hardware complexity with software-based signal analysis
Solution Approach 2:
The patent introduces switching noise as an intermediary signal to indirectly measure the Miller plateau phase. Rather than directly measuring the voltage characteristics of the Miller plateau which require high-speed circuits, the system detects the switching noise generated during the phase transition, which contains the timing information needed for temperature estimation
3Measurement precision
If multiple individual measuring circuits are deployed for N IGBT devices, then the measurement precision for each device is maintained, but the ease of manufacture deteriorates due to large scale requirements
Solution Approach 1:
The patent combines multiple measurement functions into a single integrated measurement circuit that can handle N IGBT devices. The current sensor and measurement circuit are designed to capture switching noise from multiple devices through their common current path, and the control unit processes all device signals centrally, eliminating the need for N separate measurement circuits and simplifying assembly
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 simple and accurate estimation of semiconductor element temperature with a reduced circuit scale, allowing for efficient temperature monitoring and potentially shared circuits across multiple IGBT devices.
Implementation Method 1
a detector which detects a high-frequent switching noise superimposed on a current flowing from the semiconductor element when it is turned off and on
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(f)
AI summary
Provided is an electric device which estimates a semiconductor element temperature with a simple configuration. The electric device is therefore provided with one or a plurality of semiconductor elements (104 and 106), drive circuits (107 and 108) which receive a control signal (Va) for directing an on state or an off state of the semiconductor elements (104 and 106) to drive the semiconductor elements (104 and 106) on the basis of the control signal(Va), a direct current voltage power supply (150) which provides output power to the semiconductor elements (104 and 106), a detector (114) which detects a noise component (In) generated in the semiconductor elements and superimposed on an output from the direct current voltage power supply, a detector (114), and a deviation time measurement unit (111) which measures a deviation time being a difference between timing at which the control signal (Va) directs the off state and timing at which the noise component (In) is generated.