Multiphase Transformer Rectifier Unit Phase Shift Interleaving
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Solution Overview
Problem
Conventional multiphase transformer rectifier units face challenges in reducing current distortion and improving power factor in three-phase AC to DC conversion, leading to increased complexity, weight, and conduction losses due to the need for additional windings, and complex selection of contact points.
Innovation Solution
The solution involves arranging a multiphase transformer rectifier unit with a secondary winding set generating N equally distributed output phases and a primary winding set providing a phase shift of 360/N degrees, and connecting two identical units in parallel with altered phase connections to achieve interleaved pulses, reducing current distortion and increasing power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If more windings are added to the secondary winding set to provide more output phases, then current distortion decreases, but conduction losses increase and weight increases
Solution Approach 1:
The invention divides the system into two separate multiphase transformer rectifier units, each with a manageable number of windings. Instead of one complex unit with many windings causing high conduction losses, two simpler units work together to achieve the same current distortion reduction, thereby segmenting the complexity and reducing energy losses in each individual unit.
Solution Approach 2:
The invention combines two multiphase transformer rectifier units with different primary-to-secondary phase shifts to achieve the desired current distortion reduction. By merging the outputs of these two units with complementary phase shifts, the system achieves low current distortion without requiring each unit to have excessive windings, thus avoiding high conduction losses.
2Object-generated harmful factors
If more windings are added to the secondary winding set to provide more output phases, then current distortion decreases, but the weight of the unit increases
Solution Approach 1:
The system is segmented into two separate transformer units, each with a moderate number of windings. This segmentation avoids the need for a single heavy unit with excessive windings, distributing the weight across two units while achieving the same current distortion performance.
Solution Approach 2:
The invention uses two identical or similar transformer rectifier units with different phase shift configurations rather than one complex unit with many windings. This copying approach achieves the desired electrical performance without duplicating excessive weight in a single unit.
3Object-generated harmful factors
If additional contact points are provided to the multiphase transformer, then harmonic current cancellation is achieved, but transformer cost increases
Solution Approach 1:
The system segments the harmonic cancellation function across two separate transformer units, each with a moderate number of contact points. This avoids the need for a single transformer with many additional contact points, reducing manufacturing complexity and cost while still achieving effective harmonic current cancellation through the combined output.
Solution Approach 2:
The invention merges the outputs of two transformer units with different phase shifts to achieve harmonic current cancellation. By combining these units rather than adding numerous contact points to a single transformer, the system achieves harmonic reduction at lower manufacturing cost.
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 effectively reduces current distortion and increases power factor by interleaving pulses, achieving performance similar to a unit with twice the output phases while maintaining lower complexity and cost, and allowing separate isolation of loads.
Implementation Method 1
a magnetic core with a primary winding set and secondary winding set
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
The object of the present invention is to provide an inventive multiphase transformer rectifier unit (1) for converting a three-phase (R, S, T) alternating current (AC) supplied from a power distribution system (2) to direct current (DC) supplied to at least one load (3). The multiphase transformer rectifier unit (1) comprises a magnetic core (5) having a primary winding set (17) and secondary winding set (18), and a rectifier circuit (22). The secondary winding set (18) is arranged to generate N substantially equally distributed output phases, wherein N is an odd number multiple of 3, and N > 3, and the primary winding set (17) is arranged to provide a positive or negative phase shift equal substantially to 360/(8x N) degrees of said output phases. By connecting two such multiphase transformer rectifier units (1) to the three- phase power distribution system, one thereof with changed order of connection of the input phases, the number of output pulses from the combination of two multiphase transformer rectifier units (1) will appear as doubled compared with a single inventive multiphase transformer rectifier unit (1) due to interleaved pulses from the two multiphase transformer rectifier units (1), thus reducing current distortion. It is also the object of the present invention to provide a corresponding inventive method of an arrangement of two inventive multiphase transformer rectifier units (1) for reducing current distortion in the power distribution system (2).