Non-isolated Symmetric Self-coupling 18-pulse Rectifier
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Solution Overview
Problem
Traditional high-power power-frequency AC-DC rectifiers cause significant power harmonic pollution due to large, costly, and bulky isolated phase-shifting transformers, which are inconvenient for extending higher power AC-DC rectifier systems.
Innovation Solution
A non-isolated symmetric self-coupling 18-pulse rectifier power supply system utilizing a phase-shifting autotransformer, three circuits of output devices, and bidirectional switch BUCK converters with time sequence controllers, eliminating the need for a balancing reactor and achieving 18-pulse rectification with reduced transformer capacity and harmonic suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional isolated phase-shifting transformer is used, then power harmonic pollution is suppressed, but the transformer becomes bulky, heavy and high in cost
Solution Approach 1:
The patent combines the phase-shifting function and power transformation function into a single integrated transformer structure, eliminating the need for separate isolated phase-shifting transformers. The non-isolated symmetric self-coupling transformer integrates multiple functions that were previously required from separate components, thereby reducing overall weight and size while maintaining harmonic suppression capability.
Solution Approach 2:
The patent uses a non-isolated symmetric self-coupling transformer that replicates the phase-shifting functionality of traditional isolated transformers but with a different structural approach. By copying the essential phase-shifting function while using a lighter, more compact design, the system achieves harmonic suppression without the bulk and weight of conventional isolated transformers.
2Object-affected harmful factors
If traditional isolated phase-shifting transformer is used, then power harmonic pollution is suppressed, but the system becomes complex and expensive
Solution Approach 1:
The patent merges the phase-shifting transformer and balancing reactor functions into a single integrated transformer structure. This consolidation eliminates the need for separate balancing reactors and reduces the number of components, thereby simplifying the overall system while maintaining the ability to suppress power harmonic pollution.
Solution Approach 2:
The non-isolated symmetric self-coupling transformer is designed to perform multiple functions simultaneously: phase-shifting, power transformation, and harmonic suppression. This multi-functionality reduces the need for additional specialized components, simplifying the system architecture and reducing complexity compared to traditional designs that require separate devices for each function.
3Object-generated harmful factors
If traditional isolated phase-shifting transformer is used, then 12-pulse rectification is achieved, but the structure is not convenient for extension to higher power
Solution Approach 1:
The patent employs a modular three-group output device structure (leading group, original group, and lagging group) that can be independently configured and scaled. This segmented architecture allows the system to be easily extended to higher power applications by adding or adjusting individual groups, providing better adaptability compared to traditional monolithic transformer designs.
Solution Approach 2:
The system incorporates a time sequence controller that dynamically manages the operation of bidirectional switch BUCK converters across the three groups. This dynamic control enables flexible power distribution and system configuration, allowing the rectifier system to adapt to different power levels and load requirements, thereby improving extendability to higher power applications.
4Object-affected harmful factors
If balancing reactor is added to traditional rectifier, then power harmonic pollution is reduced, but the device becomes bulky and costly
Solution Approach 1:
The patent integrates the balancing function directly into the transformer structure through the non-isolated symmetric self-coupling design. By merging the balancing reactor function with the transformer, the system eliminates the need for separate bulky balancing reactors while maintaining the ability to reduce power harmonic pollution, thereby reducing overall device volume.
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
The system provides a compact, reliable, and adaptable solution with reduced harmonic pollution, improved stability, and ease of extension for high/medium-power AC-DC rectifier systems, effectively suppressing 5, 7, 11, and 13 harmonics while reducing the need for bulky transformers.
Implementation Method 1
a phase-shifting autotransformer provided with three groups of output ends and one group of input ends A, B and C
Implementation Method 2
a three-phase uncontrolled rectifier bridge in the leading group and a bidirectional switch BUCK converter in the leading group, which are connected to each other in turn
Implementation Method 3
a bidirectional switch BUCK converter in the leading group, which are connected to each other in turn
Data Source
AI summary
A non-isolated symmetric self-coupling 18-pulse rectifier power supply system comprises a phase-shifting autotransformer, three circuits of output devices, a time sequence controller and a power output end. The phase-shifting autotransformer is provided with three groups of output ends and one group of input ends, and the output device in each circuit comprises a zero-sequence suppression reversing inductor, a three-phase uncontrolled rectifier bridge and a bidirectional switch BUCK converter, which are connected to each other in turn. The time sequence controller is provided with three groups of control ends which are respectively connected to the control end of the bidirectional switch BUCK converter in each circuit. The output end of the bidirectional switch buck converter in each circuit is connected to the power output end.