Power Converter Switch Temperature Estimation From Remote Sensors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing power conversion devices face challenges in accurately estimating the temperature of switches in power conversion circuits due to the separation between temperature sensors and switches, leading to errors in both temperature detection and power loss calculation.

Innovation Solution

A power conversion device with a temperature estimation method that includes a temperature sensor, a loss calculation unit, a loss correction unit, and a temperature correction unit, which calculate and correct power loss and temperature detection results to accurately estimate switch temperatures based on voltage, current, and on/off timing, thereby improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a temperature sensor is placed at a position separated from the switch, then the temperature detection is simpler and the device structure is easier, but the temperature detection accuracy deteriorates

Engineering Contradiction:

Improvetemperature sensor placementVSAvoidtemperature detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary calculation model that uses the temperature sensor reading at the first position, power loss calculation, and thermal resistance parameters to estimate the temperature at the switch position. This intermediary computational approach bridges the gap between the sensor position and the switch position, enabling accurate temperature estimation without direct contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical/physical approach of direct temperature sensing at the switch with a computational thermal model. Instead of mechanically placing the sensor at the switch location, the system uses mathematical calculations involving power loss, thermal resistance, and temperature gradients to substitute for direct measurement.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If power loss calculation is performed without temperature correction, then the calculation is simpler and faster, but the power loss calculation accuracy deteriorates

Engineering Contradiction:

Improvecalculation speedVSAvoidpower loss calculation accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary temperature correction to the power loss calculation by first calculating the temperature at the switch position using the thermal model, then using this corrected temperature to adjust the power loss calculation. This preliminary action ensures that subsequent calculations use accurate temperature-dependent parameters.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by using the temperature sensor reading to correct the power loss calculation through the thermal model. The calculated temperature at the switch position feeds back into the power loss calculation to improve accuracy, creating a closed-loop correction mechanism.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If temperature correction is applied to the detection result, then the temperature estimation accuracy improves, but the calculation complexity increases

Engineering Contradiction:

Improvetemperature estimation accuracyVSAvoidcalculation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameters used in temperature estimation from direct sensor reading to a composite calculation involving power loss, thermal resistance, and temperature gradient. By transforming the estimation approach to use these additional parameters, the system achieves higher accuracy despite increased computational complexity.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12123900B2Power conversion device, temperature estimation method, and non-transitory computer readable storage medium with an executable program recorded thereon

Publication Date: 2024.10.22 YASKAWA DENKI KK

AI summary

A power conversion device includes a power conversion circuit including a temperature sensor configured to detect a temperature at a sensor position and a switch configured to switch a connection on and off at a switch position separated from the sensor position; a loss calculation processing circuitry configured to calculate a power loss in the switch; a loss correction processing circuitry configured to correct a calculation result of the power loss on the basis of a detection result of the temperature at the sensor position; a temperature correction processing circuitry configured to correct the detection result of the temperature on the basis of the calculation result of the power loss; and a temperature estimation processing circuitry configured to estimate a temperature at the switch position on the basis of a corrected calculation result of the power loss and a corrected detection result of the temperature.