Ten-Phase Transformer Rectifier for Shipboard DC Bus Weight Reduction
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Solution Overview
Problem
In shipboard and aircraft applications, high rectified DC voltage is desired to reduce feeder weight, but it often results in increased common mode voltages on the DC bus, which can be cumbersome and weight-intensive due to the need for larger common mode inductors to smooth out the rectified DC voltage.
Innovation Solution
A power system incorporating a three-phase to ten-phase step-up transformer and diode pairs is used to rectify the voltage, forming a DC voltage on the bus with reduced common mode voltage, thereby eliminating or reducing the size of the common mode inductor, and efficiently converting variable frequency 230 Vrms AC to a fixed frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a higher rectified DC voltage is provided to reduce feeder weight, then the weight of feeders is decreased, but the common mode voltages on the DC bus increase
Solution Approach 1:
The patent segments the traditional three-phase rectification into ten-phase rectification by dividing each phase into multiple sub-phases. This segmentation allows the system to operate at higher DC voltages while distributing the common mode voltage across more phases, thereby reducing the harmful common mode voltage on the DC bus while achieving weight reduction in feeders.
Solution Approach 2:
The patent changes the rectification parameter from three-phase to ten-phase operation. By increasing the number of phases from 3 to 10, the system achieves higher rectified DC voltage for reduced feeder weight while the increased phase count distributes and reduces the common mode voltage amplitude, resolving the contradiction between feeder weight and common mode voltage.
2Object-affected harmful factors
If common mode inductors are increased in size to smooth rectified DC voltage, then the common mode voltage is reduced, but the weight of the power system increases
Solution Approach 1:
The patent applies preliminary action by using ten-phase rectification to pre-reduce common mode voltage before it reaches the DC bus. This preliminary reduction of common mode voltage through the ten-phase configuration means that smaller common mode inductors are needed for smoothing, thereby reducing the overall power system weight while still achieving effective common mode voltage control.
Solution Approach 2:
By changing the rectification parameter from three-phase to ten-phase, the system inherently reduces common mode voltage amplitude. This parameter change eliminates the need for large common mode inductors, as the ten-phase configuration naturally produces lower common mode voltages that require less filtering, thus reducing power system weight.
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 solution reduces the weight of the power system by minimizing the size of the common mode inductor and efficiently converting AC to DC, while maintaining a stable output voltage.
Implementation Method 1
a three-phase to ten-phase step-up transformer includes a plurality of primary winding groupings, a plurality of secondary winding windings, and a plurality of third windings
Implementation Method 2
The plurality of the sets of diode pairs operatively rectify the output voltage from the three-phase to ten-phase step-up transformer to form a DC voltage on the positive dc bus and the negative d bus
Data Source
AI summary
An electric power system is provided that includes a three-phase to ten-phase step-up transformer. The transformer includes primary winding groupings, secondary windings, and third windings. The primary winding groupings include sub windings. Primary winding groupings are coupled to form a delta configuration and coupled to secondary windings and third windings, which may also be coupled to each other. The outputs at second ends of secondary windings and third windings are greater than the outputs at the second ends of primary windings. Diode pairs are connected to each other, each diode pair having an inner connection connected to one of the outputs of the transformer and first and second ends respectively connected to a positive dc bus and a negative dc bus. An inverter is connected to the d busses. The diode pairs operatively rectify the transformer output voltage to form a DC voltage with a reduced common mode voltage.