Temperature Prediction Circuit for Power Semiconductor Devices

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Solution Overview

Problem

The thermal conduction time between the heat generating unit of a switching device and a temperature detector causes a delay in temperature detection, leading to inadequate protection for power semiconductor devices in power converters like inverters.

Innovation Solution

A semiconductor integrated circuit device with a temperature prediction circuit that stores a history of electric power values based on steady and switching losses of the switching transistor, and calculates a prediction temperature using a time factor corresponding to temperature heat dissipation characteristics, reducing the delay in temperature detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature detector is used to detect the temperature of a power semiconductor device, then the temperature can be monitored, but the thermal conduction time causes a delay in detection

Engineering Contradiction:

Improvetemperature detection accuracyVSAvoidtemperature detection delay

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by calculating and storing the history of electric power values (steady loss and switching loss) before temperature detection is needed. The delay circuit stores electric power history for a specific number of times, and the temperature prediction circuit uses this pre-stored data to predict temperature, eliminating the detection delay caused by thermal conduction time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses copying by creating a predicted temperature value based on electric power history instead of directly measuring the actual temperature. The temperature prediction circuit calculates a prediction temperature value that copies the temperature trend without waiting for thermal conduction, thereby resolving the time delay issue while maintaining measurement accuracy.

Inventive Principle:

Principle #26Copying

2Speed

If the thermal conduction time is reduced to improve response speed, then temperature detection delay is reduced, but the physical distance between heat generating unit and detector cannot be shortened

Engineering Contradiction:

Improvetemperature detection response speedVSAvoidtemperature prediction circuit complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/physical thermal conduction system with an electrical calculation system. Instead of physically reducing the distance between the heat generating unit and detector, the invention substitutes the thermal conduction process with electrical power calculation and historical data processing, achieving fast response speed without physical modification.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary approach by using electric power values as a mediator between the heat generating unit and temperature detection. The delay circuit and temperature prediction circuit act as intermediaries that process electric power history to predict temperature, avoiding the need for direct physical proximity and thermal conduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If electric power values are stored for multiple times to improve prediction accuracy, then temperature prediction becomes more accurate, but the device complexity increases

Engineering Contradiction:

Improvetemperature prediction reliabilityVSAvoiddelay circuit and calculation circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies partial action by storing electric power values for a specific number of times rather than continuously storing all historical data. This selective storage provides sufficient prediction accuracy while limiting the complexity of the delay circuit and calculation circuit, achieving a balance between reliability and device simplicity.

Inventive Principle:

Principle #16Partial or excessive action

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 solution enables timely prediction and detection of abnormal temperatures, preventing device failure by reducing the response time and allowing for prompt interrupt control, thus enhancing the protection of power semiconductor devices.

Implementation Method 1

The thermal conduction time between the heat generating unit of a switching device and a temperature detector causes a delay in the detection of a temperature

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS10175275B2Semiconductor integrated circuit device and electronics device

Publication Date: 2019.01.08 RENESAS ELECTRONICS CORP

AI summary

A semiconductor integrated circuit device includes a temperature prediction circuit that predicts the temperature of a power semiconductor device having a built-in switching transistor. The temperature prediction circuit includes: a delay circuit that stores a history of electric power values for a specific number of times, the electric power values being calculated based on the steady loss and switching loss of the switching transistor; and a circuit that calculates the temperature prediction value of the power semiconductor device based on the value of the delay circuit and a time factor corresponding to a temperature heat dissipation characteristic.