IGBT Temperature Signal Correction for Output Diode Voltage Drop
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Solution Overview
Problem
Conventional IGBT temperature sensors experience measurement errors due to voltage drops in output limiting diodes, leading to inaccuracies in temperature sensing signals.
Innovation Solution
An apparatus that calculates the conduction current through the output limiting diode and determines the voltage drop, then corrects the temperature sensing signal by increasing its voltage by the calculated drop value, using a calculating part, determining part, and correcting part within the IGBT temperature sensing device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an output limiting diode is used to output only temperature sensing signals with voltage equal to or higher than a preset voltage value, then the signal output reliability is improved, but a voltage drop occurs in the diode causing measurement error
Solution Approach 1:
The patent introduces a feedback mechanism where the voltage drop of the output limiting diode is measured and fed back to adjust the reference voltage. The microcontroller measures the actual voltage drop across the diode during operation and dynamically adjusts the reference voltage threshold to compensate for this drop, thereby eliminating the measurement error while maintaining the reliability function of the diode.
Solution Approach 2:
The patent changes the reference voltage parameter dynamically based on the actual operating conditions. Instead of using a fixed reference voltage threshold, the system measures the actual voltage drop across the output limiting diode and adjusts the reference voltage accordingly, transforming a static parameter into a dynamic one that adapts to compensate for the diode's voltage drop.
2Measurement precision
If the voltage of the temperature sensing signal is increased by the voltage drop value, then the measurement precision is improved, but the device complexity increases due to additional calculation and correction circuits
Solution Approach 1:
The patent implements a self-service mechanism where the system uses its own existing resources (the output limiting diode itself and the microcontroller's analog-to-digital converter) to measure and compensate for its own voltage drop. The microcontroller measures the voltage drop across the diode using the same ADC channel and performs the compensation calculation internally, eliminating the need for external correction circuits or additional hardware components.
Solution Approach 2:
The patent merges the voltage drop measurement function with the existing temperature sensing signal processing function. The same analog-to-digital converter and microcontroller that process temperature signals are also used to measure the diode's voltage drop and perform compensation calculations, combining multiple functions into existing components rather than adding separate dedicated circuits.
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 enables precise measurement of IGBT temperature by correcting errors in the temperature sensing signal caused by voltage drops, improving the accuracy of temperature sensing.
Implementation Method 1
an NTC (Negative Temperature Coefficient) thermistor. The NTC thermistor is a thermistor whose electrical resistance is continuously changed with a negative temperature coefficient
Implementation Method 2
when the output limiting diode D1 is conducted in a forward direction, a voltage drop occurs in the output limiting diode D1
Data Source
AI summary
The present invention relates to an apparatus for correcting a temperature sensing signal of an IGBT temperature sensing device which outputs only a temperature sensing signal having a voltage value equal to or higher than a preset voltage value, by using an output limiting diode. The apparatus includes: a calculating part configured to calculate a conduction current value of the output limiting diode by using the resistance of an NTC thermistor included in the IGBT temperature sensing device; a determining part configured to determine a drop voltage value of a voltage drop occurring in the output limiting diode based on the conduction current value; and a correcting part configured to correct the temperature sensing signal by increasing the voltage of the temperature sensing signal output from the IGBT temperature sensing device by the drop voltage value.