Temperature Detector Anode Potential Holding Circuit

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Solution Overview

Problem

Conventional temperature detectors for semiconductor switching devices, such as IGBTs, often output erroneous signals during switching operations due to negative noise affecting the anode potential of the temperature sensing diode, leading to potential thermal damage from excessive heating.

Innovation Solution

A temperature detector configuration that includes a temperature sensing diode with a negative temperature coefficient, a constant current circuit, and an anode potential holding mechanism using a capacitor, one-shot pulse generating circuit, and switching means to maintain the anode potential during switching operations, preventing erroneous signal output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a CR filter is inserted to shape the temperature signal, then the temperature signal is filtered, but the potential level decreases at high switching frequencies causing erroneous output signals

Engineering Contradiction:

Improvetemperature signal accuracyVSAvoidsignal potential level

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The one-shot pulse generating circuit generates a hold signal in advance during the switching operation period before the temperature signal is affected by negative noise. This preliminary action allows the switching means to hold the anode potential at its correct value during the critical switching period, preventing erroneous output signals while maintaining signal integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The anode potential holding means acts as an intermediary between the temperature sensing diode and the output. It captures and maintains the correct anode potential value during switching operations, mediating between the noisy raw signal and the filtered output signal to prevent erroneous readings.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the switching frequency increases, then the productivity improves, but the temperature signal potential decreases due to negative noise

Engineering Contradiction:

Improveswitching frequencyVSAvoidtemperature signal potential

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The system applies preliminary anti-action by generating a hold signal before the switching operation causes negative noise to affect the temperature signal. The anode potential holding means preemptively maintains the correct potential level during the switching period, counteracting the harmful effect of negative noise that would otherwise cause signal potential to decrease at high switching frequencies.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If the anode potential is held during switching operation, then erroneous signal output is prevented, but the device complexity increases

Engineering Contradiction:

Improvesignal output accuracyVSAvoidcircuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The temperature detector circuit is segmented into distinct functional modules: the temperature sensing diode, the constant current circuit, the CR filter, and the anode potential holding means. This segmentation allows each module to perform its specific function independently, making the overall complex system manageable and maintainable while achieving reliable operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The anode potential holding means serves multiple functions: it holds the anode potential during switching operations, prevents erroneous signal output, and maintains signal integrity without requiring separate correction circuits. This multi-functionality reduces the need for additional complex components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

The solution effectively prevents erroneous temperature signal output during semiconductor switching operations, ensuring accurate temperature monitoring and preventing thermal damage to the devices.

Implementation Method 1

a temperature sensing diode formed on the same chip as a semiconductor switching device and having a specific temperature vs. voltage characteristic

Methodology Applied

Scientific EffectNegative temperature coefficient:

Implementation Method 2

anode potential holding means for holding the anode potential of the temperature sensing diode as the temperature signal at the start of switching operation of the semiconductor switching device

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS7535128B2Temperature detector

Publication Date: 2009.05.19 MITSUBISHI ELECTRIC CORP

AI summary

A temperature detector for outputting a temperature signal comprises: a temperature sensing diode formed on the same chip as a semiconductor switching device and having a specific temperature vs. voltage characteristic, wherein the temperature detector outputs the anode potential of the temperature sensing diode as the temperature signal; a constant current circuit for supplying a current to the anode of the temperature sensing diode; and anode potential holding means for holding the anode potential of the temperature sensing diode as the temperature signal at the start of switching operation of the semiconductor switching device.