Smoothing Capacitor Deterioration Detection During Power Converter Operation
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Solution Overview
Problem
Existing methods fail to accurately evaluate the deterioration state of smoothing capacitors in power conversion apparatuses without stopping the operation, particularly due to variations in initial capacitance of electrolytic capacitors.
Innovation Solution
A power conversion apparatus with a capacitance acquiring unit that measures initial and operation capacitance values, and a deterioration determining unit that uses statistical analysis to determine the capacitor's state based on characteristic information, allowing evaluation without stopping the apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the power conversion apparatus is stopped to evaluate the smoothing capacitor, then the measurement precision of capacitance can be improved, but the productivity is reduced
Solution Approach 1:
The patent applies preliminary action by acquiring multiple initial capacitance values at different operation states before formal deterioration evaluation begins. This creates a baseline dataset that enables accurate capacitance measurement without requiring the apparatus to be stopped, as the measurement can be performed during normal operation transitions.
Solution Approach 2:
The patent implements dynamics by performing capacitance measurements during changes in operation state rather than during steady-state operation. The smoothing capacitor's capacitance is evaluated while the power conversion apparatus transitions between different operating conditions, allowing continuous monitoring without interrupting productivity.
2Device complexity
If a single initial capacitance value is used for evaluation, then the device complexity is reduced, but the measurement precision deteriorates due to large variation in initial capacitance
Solution Approach 1:
The patent applies segmentation by dividing the capacitance evaluation into multiple discrete measurements taken at different operation states. Instead of relying on a single capacitance value, the system segments the evaluation into multiple initial capacitance measurements (C1, C2, C3, etc.) corresponding to different operating conditions, thereby capturing the variation in initial capacitance more accurately.
Solution Approach 2:
The patent implements parameter changes by utilizing multiple operation states as varying parameters for capacitance measurement. The operation state serves as a changing parameter that allows the system to capture capacitance values under different conditions, improving the accuracy of deterioration evaluation by accounting for initial capacitance variation.
3Productivity
If capacitance measurement is performed during operation state change, then the productivity is maintained, but the measurement precision may be affected by operation variability
Solution Approach 1:
The patent applies feedback by using the relationship between AC power and capacitance value, derived from initial measurements, to determine deterioration state during operation. The system continuously monitors capacitance during operation state changes and compares it against the established relationship, allowing accurate deterioration assessment while maintaining continuous operation and productivity.
Data Source
AI summary
A capacitance acquiring unit acquires a plurality of initial capacitance values indicating capacitance values of a smoothing capacitor in an initial state and acquires a plurality of operation capacitance values indicating capacitance values of the smoothing capacitor in an operation state, and a deterioration determining unit acquires characteristic information indicating a relationship between AC power and the capacitance value of the smoothing capacitor in the initial state on the basis of a statistic amount of the plurality of initial capacitance values acquired by the capacitance acquiring unit and determines a deterioration state of the smoothing capacitor on the basis of a statistic amount of the plurality of operation capacitance values acquired by the capacitance acquiring unit and the characteristic information.