Power Converter Temperature Abnormality Detection
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Solution Overview
Problem
At low ambient temperatures, the difference between the cooling water temperature and the power conversion device temperature can exceed thresholds, leading to unnecessary restriction of the power conversion device's operation, even when the device is at a drivable temperature.
Innovation Solution
A temperature abnormality detection method that calculates the difference between the power conversion device temperature and the cooling fluid temperature, determining abnormalities based on preset thresholds, including a first threshold for normal operation and a second threshold for high ambient temperatures, to avoid excessive protection and ensure accurate determination of non-preferred operating states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature abnormality detection is based only on the difference between cooling water temperature and power conversion device temperature, then temperature abnormality can be detected, but at low ambient temperatures the device operation is unnecessarily restricted even when the device is at a drivable temperature
Solution Approach 1:
The patent introduces a dual-threshold mechanism that changes the detection parameters based on ambient temperature conditions. When ambient temperature is low, the system requires both a temperature difference threshold AND an absolute device temperature threshold to be exceeded before declaring an abnormality. This parameter change resolves the contradiction by making the detection system more selective under low ambient conditions, preventing unnecessary operational restrictions while maintaining reliability.
2Device complexity
If a single temperature threshold is used for abnormality detection, then the detection system is simple, but it cannot accurately distinguish between low ambient temperature conditions and actual temperature abnormalities
Solution Approach 1:
The patent segments the temperature abnormality detection into two distinct evaluation criteria: (1) temperature difference between cooling water and device, and (2) absolute device temperature. By dividing the detection logic into these two segments that work together, the system achieves high measurement precision without excessive complexity. The segmentation allows each criterion to address specific aspects of temperature assessment.
Solution Approach 2:
The detection system dynamically adjusts its criteria based on operating conditions. The control unit evaluates both temperature difference and absolute temperature thresholds, and only declares an abnormality when appropriate combinations of these dynamic criteria are met. This dynamic approach enables accurate distinction between low ambient temperature (normal operation) and actual temperature abnormalities (protective action required).
Data Source
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AI summary
To provide a temperature abnormality detection method for a power conversion device that can more accurately determine an abnormal temperature state, which is not preferred for driving a power conversion device. The temperature abnormality detection method for a power conversion device is characterized by comprising a difference calculation step (Step S12) for calculating a temperature difference (ΔT1) between a first inverter temperature (Tin1) and a cooling water temperature (Tw), and a first abnormality determination step (Step S13) for determining a temperature abnormality when a first abnormality determination condition is satisfied, i.e., when the temperature difference (ΔT1) exceeds a preset difference threshold (ΔTfail) and the first inverter temperature (Tin1) exceeds a preset power conversion unit threshold temperature (Tinfail).