Power Converter Switching Curves for Continuous Angle Modulation
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Solution Overview
Problem
Existing power electronic converter modulation methods often result in discontinuities in switching angles when changing modulation index values, leading to potential system drawbacks and electrical signal issues.
Innovation Solution
A method that divides the modulation index range into contiguous segments, calculates specific switching angles for each segment, and generates a continuous switching curve by ensuring consistent amplitude and slope across segment boundaries, using a polynomial relationship between switching coefficients and modulation index to maintain continuity and prevent discontinuities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If switching angles are calculated for each modulation index value independently, then the switching pattern can be optimized for each specific modulation index, but discontinuities occur in the switching curves when changing modulation index values
Solution Approach 1:
The method segments the modulation index range into multiple contiguous segments, where each segment shares boundary values with adjacent segments. By calculating switching angles for each segment independently while ensuring continuity at boundary values, the approach maintains both optimization within segments and overall continuity across the entire modulation index range, resolving the contradiction between precision and reliability.
Solution Approach 2:
The method performs preliminary calculation of switching angles for all segments and stores them in a lookup table before actual operation. This preliminary action ensures that when the modulation index changes, the system can smoothly transition between pre-calculated switching patterns without encountering discontinuities, thereby maintaining both precision and reliability.
2Productivity
If switching angles are pre-calculated and stored in lookup tables, then the system implementation is simplified and speed improved, but the adaptability to arbitrary modulation index values is limited
Solution Approach 1:
By dividing the modulation index range into segments with shared boundary values, the method enables pre-calculation of switching angles for discrete segments while maintaining the ability to handle any modulation index value within the segments. This segmentation approach preserves both the speed benefits of lookup tables and the adaptability to arbitrary modulation indices through linear interpolation between boundary values.
Solution Approach 2:
The method changes the parameter representation from storing switching angles directly to storing switching coefficients that define polynomial relationships. This allows the system to generate switching angles for any modulation index value within segments using polynomial expressions, thereby maintaining high adaptability while keeping the lookup table size manageable and implementation efficient.
3Reliability
If the modulation index range is divided into multiple segments, then switching curve continuity can be maintained across boundaries, but the complexity of the calculation process increases
Solution Approach 1:
The segmentation of the modulation index range into contiguous segments with shared boundary values provides a structured framework that simplifies the continuity enforcement process. By treating each segment independently while ensuring matching at boundaries, the method maintains switching curve continuity without requiring complex global optimization, thus balancing reliability with manageable calculation complexity.
Solution Approach 2:
The transformation from calculating switching angles directly to calculating switching coefficients that define polynomial relationships reduces the computational complexity. The polynomial approach allows for analytical solutions that are more efficient than numerical methods, thereby maintaining reliability through continuity while reducing the overall calculation process complexity.
Data Source
AI summary
The present invention relates to a method for obtaining switching angles (α1, . . . , αi), and to an associated conversion system. In the method, possible values (IM) are established for a modulation index, within a predetermined range of values (R) and divided into a plurality of segments (S1, . . . , Sj); a value is obtained for each of the switching angles (α1, . . . , αi) in each segment (S1, . . . , Sj) and for each of the possible values (IM); a switching curve (SC) is formed for each switching angle (α1, . . . , αi) over the entire range (R); and the height or amplitude and the slope of each switching curve (SC) at a possible value shared by two segments (S1, . . . , Sj) are considered constant.