Multi-Pulse Transformer Winding Phase Shift for Even Rectifier Currents
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Solution Overview
Problem
Existing centralized high-power electric vehicle charging systems face issues due to unequal output voltages from secondary windings of multi-pulse transformers, leading to uneven input currents and increased current stress on diodes in rectifier bridge arms, which complicates the design and increases costs.
Innovation Solution
A design method for transformers that involves adjusting the phase shift angle and calculating the number of turns for secondary windings to ensure that the differences in output voltages between secondary winding pairs are within a preset threshold, thereby stabilizing voltage and achieving even currents without the need for a balancing reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the number of turns of the secondary winding is rounded, then the transformer is easier to manufacture, 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 voltage inequalities caused by rounded turn numbers. By adjusting the phase shift angle, the output voltages of secondary windings with different turn numbers can be equalized, thus resolving the contradiction between ease of manufacture and manufacturing precision.
2Ease of operation
If a balanced inductor is adopted at the output terminal of the rectifier bridge, then even currents are achieved, but the dimension and cost of the AC-DC charging module increase
Solution Approach 1:
The patent extracts the current balancing function from the rectifier bridge output stage and transfers it to the transformer winding design. By optimizing the phase shift angle and turn numbers of transformer windings, the current balancing function is achieved at the input stage, eliminating the need for additional balanced inductors at the output stage.
Solution Approach 2:
The patent uses the transformer as an intermediary device to achieve current balancing. The transformer's winding configuration and phase shift angle act as a mediator that equalizes currents before they enter the rectifier bridge, preventing the need for additional balancing components downstream.
3Ease of manufacture
If the number of turns of the secondary winding is rounded, then the transformer is easier to manufacture, but the current stress of diodes in the rectifier bridge arm increases
Solution Approach 1:
The patent changes the phase shift angle parameter to compensate for voltage inequalities caused by rounded turn numbers. By optimizing this parameter, the output voltages are equalized, which ensures even current distribution and reduces current stress on diodes, thus resolving the contradiction between ease of manufacture and current stress.
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 method effectively reduces the dimension and cost of the charging system while ensuring voltage stabilization and even currents, improving the efficiency and design simplicity of the rectifier bridge and capacitor selection.
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
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.