Electric Power Converter Voltage Stabilization via Adaptive Reference Correction
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Solution Overview
Problem
Existing electric power converter systems face issues with voltage fluctuations from variable power sources, leading to excess current and torque pulsation in electric motors, causing instability in motor operation.
Innovation Solution
An electric power converter apparatus with a reference voltage correcting unit that adjusts the output voltage by calculating a DC voltage estimation and correction terms to maintain a constant output voltage, preventing saturation and sudden changes during power source variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference voltage value is increased to compensate for power source voltage drop, then the output voltage can be maintained, but the output voltage becomes saturated and cannot exceed the maximum value determined by carrier amplitude
Solution Approach 1:
The patent applies dynamics by making the reference voltage correction adaptive rather than static. The correction amount is dynamically adjusted based on the detected power source voltage, ensuring the corrected reference voltage remains within achievable limits while maintaining output stability. This resolves the contradiction by preventing saturation through dynamic adaptation to varying power source conditions.
Solution Approach 2:
The patent implements feedback by detecting the actual power source voltage and using this information to correct the reference voltage. The system continuously monitors the power source voltage and adjusts the reference voltage accordingly, creating a closed-loop control that prevents saturation while maintaining reliable output voltage despite power source fluctuations.
2Reliability
If the reference voltage value is suddenly decreased when power source voltage rises, then the output voltage can be reduced, but the output voltage experiences precipitous variation causing excess current flow
Solution Approach 1:
The patent applies beforehand cushioning by implementing rate-of-change limiting on the reference voltage correction. When the power source voltage rises, the reference voltage is decreased, but the rate of this decrease is limited to prevent sudden output voltage drops. This cushioning effect prevents excess current flow by anticipating and mitigating the harmful impact of rapid voltage changes before they occur.
Solution Approach 2:
The patent uses dynamics by implementing time-constant-based smoothing of the reference voltage correction. The correction is applied gradually rather than instantaneously, creating a dynamic response that filters out abrupt changes. This dynamic approach maintains reliable voltage control while preventing the precipitous variations that cause excess current.
3Reliability
If the reference voltage is corrected in response to power source voltage variations, then the inverter output voltage can be maintained constant, but torque pulsation occurs when output voltage is near square wave
Solution Approach 1:
The patent applies feedback by detecting the actual output voltage and comparing it with the desired reference voltage. This closed-loop control ensures the output voltage remains constant despite power source variations, while the feedback mechanism also helps maintain sinusoidal waveform quality, preventing torque pulsation by ensuring accurate voltage regulation.
Solution Approach 2:
The patent uses dynamics by implementing smooth, rate-limited adjustments to the reference voltage. This dynamic correction approach prevents abrupt changes that would cause the output voltage to approach square wave conditions, thereby maintaining motor torque stability while still achieving output voltage constancy through adaptive correction.
Data Source
AI summary
An electric power converter apparatus having a function of converting a power source voltage into an AC voltage having an arbitrary frequency and maintaining an output voltage constant even on the power source variation, in which the electric power converter apparatus decreases the output voltage when the output voltage drops to equal to or less than a predetermined value, afterward, increases the output voltage in response to a predetermined rate of change when the power source voltage rises.


