Motor Control Device Temperature Estimation at Restart
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Solution Overview
Problem
Existing motor control devices fail to accurately estimate the temperature of an evaluation place at restart after halting, due to ambient temperature changes affecting temperature detector readings, leading to incorrect temperature estimation and potential breakdown of elements.
Innovation Solution
A motor control device with two temperature detectors that estimate the temperature of evaluation places by calculating a temperature difference ratio and multiplying it with an estimated gain, allowing for accurate temperature estimation at restart regardless of ambient temperature changes, and limiting current command values based on estimated temperatures to prevent element breakdown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single temperature detector is used to estimate temperature at restart after halting, then the device complexity is reduced, but the temperature estimation accuracy deteriorates due to ambient temperature changes
Solution Approach 1:
The temperature detection function is segmented into multiple detectors placed at different locations (heat sink and IC). This segmentation allows the system to capture temperature variations at different points, enabling accurate estimation of temperature at restart even when ambient temperature changes occur during halting periods.
Solution Approach 2:
The patent introduces an intermediary calculation method that uses the temperature difference ratio between two detectors as a mediator. By calculating the ratio of temperature differences between the heat sink and IC at restart versus at halt, the system can estimate the IC temperature at restart without being directly affected by ambient temperature changes.
2Device complexity
If temperature estimation is performed without considering ambient temperature changes, then the calculation process is simplified, but the reliability of temperature estimation deteriorates
Solution Approach 1:
The patent changes the estimation parameter from absolute temperature to temperature difference ratio. By using the ratio of temperature differences (ΔT1/ΔT2) between two detectors, the system eliminates the influence of ambient temperature changes while maintaining a relatively simple calculation process. This parameter transformation ensures reliable temperature estimation at restart.
3Productivity
If current supply is restarted immediately after halting without temperature re-estimation, then the productivity is improved, but the safety of the system deteriorates due to potential element breakdown
Solution Approach 1:
The patent performs preliminary temperature estimation at restart by calculating the IC temperature based on the stored temperature difference ratio and current temperature measurements. This preliminary action ensures that the system has accurate temperature information before allowing current supply to restart, preventing element breakdown while enabling quick restart response.
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 device effectively estimates temperatures at restart without ambient temperature interference, preventing element breakdown and maintaining high motor output by accurately controlling energization.
Implementation Method 1
a substrate arranged on a heat sink to radiate heat generated at a time of energization
Data Source
AI summary
A motor control device includes: a substrate on a heat sink; switching elements providing a power converter; a drive circuit IC having a pre-driver; a control circuit IC having a current control unit; first and second temperature detectors; and a temperature estimation unit of evaluation places. When the current control unit is halted after operation and is restarted after halt, the temperature estimation unit: stores estimated temperature and the first and second detected temperature at the halt; calculates, as an estimated gain, a ratio of a temperature difference at the halt to a temperature difference at restart; and estimates temperature at the restart based on a temperature difference obtained by multiplying a temperature difference between the first detected temperature and the estimated temperature at the halt by the estimated gain, and increased temperature.