Main Switch Voltage Sensing for Accurate Power Module Temperature Detection

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Solution Overview

Problem

Existing methods for detecting the temperature of a main switch in power modules, such as using negative temperature coefficient thermistors or diodes, are not ideal as they introduce errors due to parasitic resistance and inductance, leading to inaccurate temperature calculations.

Innovation Solution

A power module device with a detection unit directly connected to the ends of the main switch to measure the voltage across it, converting this voltage into a temperature value using a processor and a conversion table, while employing a withstand voltage circuit and clamp circuit to prevent damage and ensure accurate readings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional temperature detection methods (using thermistors or diodes) are employed, then temperature can be detected, but measurement precision deteriorates due to parasitic resistance and inductance errors

Engineering Contradiction:

Improvetemperature detection accuracyVSAvoidparasitic resistance and inductance errors

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the temperature detection function directly from traditional indirect methods (thermistor/diode) to a direct voltage measurement across the main switch terminals. By measuring the voltage drop directly at the switch terminals where current flows, the method eliminates the influence of parasitic resistance and inductance that plague traditional approaches, achieving accurate temperature detection through direct electrical measurement rather than indirect thermal sensing

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces voltage as an intermediary parameter to indirectly measure temperature. Instead of directly measuring temperature or using components susceptible to parasitic effects, the method measures the voltage across the main switch terminals, which correlates with temperature through the semiconductor's electrical characteristics. This intermediary measurement approach bypasses the harmful parasitic effects while maintaining temperature detection capability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If detection unit is directly connected to main switch terminals for accurate measurement, then measurement precision improves, but reliability worsens due to potential damage from high voltage

Engineering Contradiction:

Improvevoltage measurement accuracyVSAvoiddetection unit protection

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by placing a withstand voltage circuit in parallel with the detection unit before connection to the main switch terminals. This circuit is designed to withstand high voltage spikes and transient conditions that occur during switch operation, thereby protecting the sensitive detection unit from damage while allowing accurate voltage measurement during normal operation

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The withstand voltage circuit acts as an intermediary protective layer between the high-voltage main switch terminals and the sensitive detection unit. It provides galvanic isolation or voltage clamping functionality, allowing the detection unit to measure voltage accurately without being directly exposed to damaging voltage levels, thus ensuring both measurement precision and reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method provides accurate temperature detection of the main switch without errors from parasitic impedance, ensuring reliable operation and preventing damage to the detection unit.

Implementation Method 1

detecting, by a detection unit, a voltage across the two ends of the main switch to generate a detection voltage

Methodology Applied

Scientific EffectVoltage detection: Ohm's Law

Implementation Method 2

converting the detected voltage to a detected temperature value

Methodology Applied

Scientific EffectVoltage-temperature conversion:

Data Source

PatentUS12130310B2Power module device and temperature detection method thereof

Publication Date: 2024.10.29 DELTA ELECTRONICS INC(CN)

AI summary

A power module device, comprising a main switch and a detection unit. The main switch is electrically connected between a first detection node and a second detection node. The first detection node and the second detection node are electrically connected between a plurality of power supply nodes, and are substantially two ends of the main switch. When the main switch is turned on, the main switch is configured to transmit a current flowing through the plurality of power supply nodes. The detection unit is electrically connected to the first detection node and the second detection node, and configured to detect a voltage across the two ends of the main switch to generate a detection voltage.