Multi-Pulse Transformer Winding Phase Shift for Voltage Equality
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Solution Overview
Problem
Existing centralized high-power electric vehicle charging systems face challenges in achieving even current input to rectifier bridge arms due to unequal output voltages from secondary windings of multi-pulse transformers, leading to increased current stress on diodes and higher system dimensions and costs.
Innovation Solution
A design method for transformers that iteratively adjusts phase shift angles of secondary windings to minimize voltage differences between winding pairs, thereby optimizing the number of turns and ensuring even currents while reducing system dimensions and costs without the need for balancing reactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of turns of the secondary winding is rounded to an integer, then the manufacturing precision is improved, but the output voltages of the secondary windings become unequal
Solution Approach 1:
The patent changes the phase shift angle parameter of the transformer windings to compensate for the voltage inequality caused by rounding the number of turns. By adjusting the phase shift angle, the output voltages of secondary windings with different turn numbers can be made equal, thus resolving the contradiction between manufacturing precision and voltage equality.
2Reliability
If the output voltages of secondary windings are made equal by adjusting phase shift angles, then the current stress of diodes is reduced, but the device complexity increases
Solution Approach 1:
The patent adjusts the phase shift angle parameter to equalize output voltages, which reduces diode current stress and improves reliability. While this introduces additional design parameters, the complexity is manageable through systematic calculation methods provided in the patent.
3Reliability
If balancing reactors are added to achieve even currents, then the current distribution is improved, but the system dimensions and costs increase
Solution Approach 1:
The patent extracts the need for balancing reactors by addressing the voltage equality issue at the transformer output stage. By equalizing the output voltages of secondary windings through phase shift angle adjustment, the patent eliminates the requirement for additional balancing reactors, thus reducing system dimensions and costs while maintaining current distribution uniformity.
4Adaptability or versatility
If the number of turns of secondary windings are made different to achieve phase shift, then the phase shift function is improved, but the output voltage equality deteriorates
Solution Approach 1:
The patent uses phase shift angle as a compensating parameter to maintain output voltage equality despite different numbers of turns in secondary windings. By carefully selecting the phase shift angle, the patent achieves both phase shift functionality and voltage equality simultaneously.
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 stabilizes voltages and achieves even currents in the rectifier bridge arms, effectively reducing the size and expense of the charging system by optimizing transformer design.
Implementation Method 1
a primary winding of a multi-pulse transformer is connected to the power grid, secondary windings of the multi-pulse transformer are respectively connected to AC-DC charging modules
Data Source
Figure 1
Figure 2~3
Figure 4~5A
AI summary
A design method of a transformer repeats following steps until a preset condition is met: calculating an output voltage of each secondary winding according to a phase shift angle and a number of turns of the each secondary winding; obtaining a difference between output voltages of each secondary winding pair in a secondary winding set; adjusting the phase shift angle of at least one secondary winding in the secondary winding set; and obtaining a final number of turns for the each secondary winding according to a resultant phase shift angle corresponding to when the preset condition is met; where the preset condition is that the difference between the output voltages of any secondary winding pair in the secondary winding set is less than or equal to a preset threshold.