IGBT Driver MOSFET Temperature Sensing via Superimposed AC Voltage
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Solution Overview
Problem
Existing methods for determining the temperature of IGBT drivers are inaccurate and slow, requiring large safety factors to prevent thermal failure, and precise switching times are difficult to adhere to, necessitating additional components like NTC thermistors.
Innovation Solution
A method involving two interconnected MOSFET elements in an IGBT driver with complementary control voltages and a high-frequency alternating voltage, allowing continuous superposition of base direct and alternating voltages to determine temperature through output voltage analysis, eliminating the need for additional components and precise timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NTC thermistor is used for temperature monitoring, then thermal failure prevention is achieved, but measurement accuracy and speed deteriorate
Solution Approach 1:
The patent extracts the temperature measurement function from the external NTC thermistor and relocates it to an internal gate resistor element that is already present in the MOSFET structure. This eliminates the need for separate monitoring components and provides direct access to the temperature at the critical active region through the temperature-dependent resistance of the gate resistor.
Solution Approach 2:
The MOSFET's internal gate resistor element serves dual purposes: it performs its original function of limiting gate current while simultaneously acting as the temperature sensing element. The resistance of this existing component changes with temperature, allowing the device to monitor its own temperature without requiring external sensing components.
2Measurement precision
If alternating voltage measurement method is used, then temperature measurement capability is added, but switching time precision and control accuracy deteriorate
Solution Approach 1:
The patent enables continuous temperature monitoring by permanently superimposing the alternating voltage on the base direct voltage, allowing the measurement process to occur continuously without interrupting the normal operation of the IGBT driver. This eliminates the need for separate measurement phases and maintains both operational and measurement functions simultaneously.
3Reliability
If large safety factor is provided for temperature monitoring, then thermal failure prevention is secured, but system complexity and component requirements increase
Solution Approach 1:
The patent makes the gate resistor element multi-functional by having it serve both as a current-limiting component for MOSFET operation and as a temperature sensing element. This universal use of existing components eliminates the need for additional dedicated temperature monitoring components, reducing system complexity while maintaining reliable thermal protection.
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
Accurately determines MOSFET temperatures without additional components, enhancing precision and speed, thereby preventing thermal failure while simplifying the control process.
Implementation Method 1
The alternating voltage and the base direct voltage are thereby provided permanently and always superimposed
Implementation Method 2
the resistance of the internal gate resistor element can be measured, and the temperature of the active region of the MOSFET can be determined therefrom
Data Source
AI summary
A method for determining a temperature of an Insulated-Gate Bipolar Transistor (“IGBT”) driver, the IGBT driver may include two Metal-Oxide-Semiconductor Field-Effect Transistor (“MOSFET”) elements, two direct voltage terminals for providing a base direct voltage for the two MOSFET elements, two gate terminals for providing two control voltages for the two MOSFET elements, a measurement output for outputting an output voltage, and an alternating voltage source for providing an alternating voltage, the method may include providing the control voltages, the base direct voltage, and the alternating voltage, superimposing the alternating voltage with the base direct voltage, capturing the output voltage at the measurement output of the IGBT driver, and determining the temperature of the respective MOSFET elements from the captured output voltage.