Alternating Current Modulation With Dynamic Tolerance Band Control
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Solution Overview
Problem
Existing methods for generating alternating current in wind turbines using narrow tolerance bands to maintain a sinusoidal waveform result in excessively high switching frequencies, requiring significant effort and resources to ensure the total current does not exceed permissible deviations.
Innovation Solution
A method where the tolerance limits for partial currents are adjusted dynamically based on the total current, allowing independent control of upper and lower limits to maintain the total current within a predetermined tolerance band without increasing switching frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If narrow tolerance bands are used to maintain sinusoidal waveform quality, then current quality is improved, but switching frequency increases excessively
Solution Approach 1:
The patent applies dynamics by making the tolerance band width variable rather than fixed. The control device dynamically adjusts the tolerance band width based on the measured total current, narrowing it when current quality needs improvement and widening it when switching frequency becomes excessive. This resolves the contradiction by allowing the system to adapt between the two opposing requirements in different operating conditions.
Solution Approach 2:
The patent changes the parameter of tolerance band width from a static value to a variable parameter controlled by the control device. By monitoring the total current and adjusting the tolerance band width accordingly, the system can maintain current quality while preventing excessive switching frequency, thus resolving the technical contradiction between precision and speed.
2Power
If multiple inverters superimpose partial currents to form total current, then current generation capacity is improved, but total current may exceed permissible deviations
Solution Approach 1:
The patent implements feedback by having the control device continuously measure the total current formed by superimposing partial currents from multiple inverters. Based on this measured value, the control device adjusts the tolerance bands for each inverter to ensure the total current remains within permissible deviations. This feedback mechanism resolves the contradiction by enabling high power output while maintaining current quality through real-time monitoring and adjustment.
Solution Approach 2:
The patent merges the control of multiple independent inverters into a coordinated system. The control device combines information from all inverters and adjusts their tolerance bands collectively to ensure the superimposed total current meets quality requirements. This merging approach allows the system to utilize the combined power capacity of multiple inverters while maintaining precise control over the total current deviation.
3Manufacturing precision
If tolerance band width is reduced to improve current quality, then waveform accuracy is improved, but control complexity increases
Solution Approach 1:
The patent applies universality by using a single control device that performs multiple functions: measuring total current, calculating appropriate tolerance band widths, and adjusting tolerance bands for all inverters. This multi-functional approach simplifies the overall control architecture compared to having separate control systems for each inverter, thereby reducing control complexity while maintaining waveform accuracy through coordinated tolerance band management.
Data Source
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AI summary
The invention relates to a method for generating an alternating electric current (iG), comprising the steps of generating a plurality of partial currents (i1, i2, in) and superposing the partial currents (i1, i2, in) in order to form a total current (iG), wherein each of the partial currents (i1, i2, in) is generated by using a modulation method, the modulation method uses a tolerance band method having tolerance limits (T1, T2), and the tolerance limits (T1, T2) can be changed.