Modular Multi-Pulse Transformer Rectifier Harmonic Cancellation
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Solution Overview
Problem
Multi-level power converters face challenges with harmonic current components causing electromagnetic interference (EMI) due to the need for large numbers of isolated DC voltage sources and the difficulty in optimizing harmonics cancellation in single-stage transformers with limited manufacturing flexibility.
Innovation Solution
The use of modular transformers with phase-shifted primary and secondary windings allows for optimized harmonics cancellation and improved power quality by eliminating troublesome harmonics, enabling scalability and modularity in inverter topologies like series H-bridge inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a single-stage transformer with multiple phase-shifted secondary windings is used, then harmonics cancellation is achieved, but manufacturing complexity increases and degree of freedom is reduced
Solution Approach 1:
The patent divides the transformer into multiple modular units, each with its own primary and secondary windings. This segmentation allows independent optimization of each module while achieving overall harmonics cancellation through the combined effect of multiple phase-shifted secondary windings across different modules.
Solution Approach 2:
The patent introduces an additional phase-shifting dimension by incorporating phase-shifted primary windings in addition to phase-shifted secondary windings. This dual phase-shifting approach provides extra degrees of freedom for optimizing harmonics cancellation while maintaining manufacturing feasibility.
2Reliability
If multiple isolated DC voltage sources are used to supply each power cell, then power conversion capability is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent designs modular transformer units that can universally supply multiple power cells through their multiple secondary windings. Each modular transformer can serve multiple functions by providing isolated DC voltage to different power cells, reducing the total number of isolated sources needed while maintaining system reliability.
3Object-generated harmful factors
If small phase shift angles are implemented for efficient harmonics cancellation, then power quality improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the overall phase-shifting requirement into multiple smaller, manageable phase shifts across different modular units. This allows each individual module to use standard, achievable phase shift angles while the cumulative effect achieves the desired small overall phase shift for optimal harmonics cancellation.
Solution Approach 2:
The patent optimizes the phase shift angles as configurable parameters that can be adjusted during design and manufacturing. By treating phase shift angles as adjustable parameters rather than fixed values, the system can achieve efficient harmonics cancellation while accommodating manufacturing tolerances.
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 approach reduces harmonic distortion to levels below IEEE 519 standards, enhances power quality, and provides reliability by allowing continued system operation even if one transformer fails, with benefits including reduced manufacturing complexity and improved packaging.
Implementation Method 1
modular transformers each including a phase-shifted primary winding coupled to an input power source and phase-shifted secondary windings each coupled to a power cell
Data Source
AI summary
In one embodiment, the present invention includes a system having multiple modular transformers each including a primary winding coupled to an input power source and phase-shifted secondary windings each coupled to a power cell. The system further includes different phase output lines coupled to a load. These lines may include first, second and third phase output lines.