Multi-winding Transformer Phase Shift for Harmonic Reduction
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Solution Overview
Problem
Conventional series-connected multi-level power conversion devices face challenges in reducing harmonic currents in the primary winding, particularly due to the phase differences between secondary windings of the multi-winding transformer.
Innovation Solution
The configuration includes a multi-winding transformer with specific voltage phase differences between secondary windings connected to single-phase power converters, generating steepled-wave currents with a phase difference of 10 degrees in the primary winding, effectively dispersing harmonic influences and reducing current harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional phase difference configuration (20 degrees between groups, 20/3 degrees within groups) is used, then harmonic current reduction is achieved, but device complexity increases due to multiple transformers and complex wiring
Solution Approach 1:
The patent combines multiple transformer functions into a single multi-winding transformer that integrates primary and secondary windings with specific phase relationships. This merging approach achieves the same harmonic current reduction effect as conventional multiple-transformer configurations but with simplified structure and wiring, directly resolving the contradiction between harmonic reduction and device complexity.
2Productivity
If multiple single-phase power converters are used to reduce harmonic current, then power conversion efficiency improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The multi-winding transformer is designed to serve multiple functions simultaneously: voltage transformation, phase shifting for harmonic reduction, and power distribution to multiple single-phase converters. This universal design achieves high power conversion efficiency while simplifying the overall system structure and easing manufacturing requirements compared to multiple specialized components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces current harmonics in the primary winding by dispersing the influence of steepled-wave currents, enhancing the efficiency of the power conversion process.
Implementation Method 1
The multi-winding transformer transforms a multiphase alternating input voltage into a primary winding and outputs the transformed voltage to a plurality of secondary windings
Data Source
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Figure 5
AI summary
A series-connected multi-level power conversion device (1, 1A, 1B) according to an aspect of embodiments includes a multi-winding transformer (10) and a power conversion unit (20). The multi-winding transformer (10) has a relationship that n secondary windings (12a to 12f) respectively connected to n single-phase power converters (21a to 21f) in the same output phase have a voltage phase difference of 60/n degrees and a relationship that the m secondary windings (12a to 12f) respectively connected to the m single-phase power converters (21a to 21f) corresponding to the m output phases have a voltage phase difference of 60/m degrees.