12-Phase PMG Rectifier Voltage Regulation
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Solution Overview
Problem
Conventional DC power generating systems using 3-phase variable-speed permanent magnet generators require large passive components and complex, expensive multilevel topologies to achieve high power density and low harmonic distortion, while maintaining output voltage stability across varying generator speeds and loads.
Innovation Solution
A power generation system incorporating a 12-phase permanent magnet generator with four sets of three-phase windings and passive six-pulse rectifiers, where a controller selectively couples rectifiers to maintain a constant output voltage by adjusting switch configurations based on generator speed, allowing for the combination of rectifier outputs to stabilize voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional two-level six switch active rectifier is used, then the system can generate DC power, but the size of passive components (dc link capacitor and output power quality filter) becomes large
Solution Approach 1:
The patent divides the three-phase AC input into four separate three-phase winding sets, each connected to its own six-pulse rectifier. This segmentation allows the system to process power in multiple parallel channels, reducing the burden on individual passive components and enabling higher power density without proportionally increasing component size.
Solution Approach 2:
The patent transitions from a conventional two-level rectifier topology to a multilevel voltage structure by stacking four six-pulse rectifier outputs. This dimensional change in voltage level organization reduces harmonic distortion and allows for smaller filter components while maintaining high power density.
2Object-generated harmful factors
If multilevel topologies (unidirectional Vienna Rectifier or bi-directional neutral diode clamped multilevel converter) are used to achieve high power density, then harmonic distortion is reduced and EMI emissions are reduced, but the system complexity and cost increase
Solution Approach 1:
The patent employs passive six-pulse rectifiers instead of active switching rectifiers, eliminating the need for complex control circuits, sensors, and microprocessors. The rectification process is self-regulating through the natural characteristics of the passive components and the controller's simple switching logic, significantly reducing system complexity while maintaining low harmonic distortion.
Solution Approach 2:
The patent combines four six-pulse rectifier outputs in series to create a high-voltage DC output. This merging approach achieves multilevel voltage characteristics and reduced EMI emissions without requiring the complex switching networks and control mechanisms of traditional multilevel active rectifiers, thus reducing overall system complexity.
3Speed
If a conventional active rectifier is used, then the system can operate at variable speeds, but the output voltage becomes unstable across varying speeds and loads
Solution Approach 1:
The controller monitors the generator speed and load conditions, then dynamically adjusts the switching configuration of the rectifier connections. This feedback mechanism ensures that the output voltage remains stable across varying speeds and loads by optimizing the rectification process in real-time based on actual operating conditions.
Solution Approach 2:
The patent implements dynamic reconfiguration of the rectifier circuit connections through the controller. The switching network can dynamically change the topology to optimize performance at different operating points, maintaining voltage stability while accommodating variable-speed operation from the permanent magnet generator.
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 achieves high power density, reduced losses, low torque pulsation, and improved power quality with reduced complexity and cost by using passive rectifiers and switch-controlled voltage stabilization, suitable for aircraft power generation.
Implementation Method 1
A 12-phase permanent magnet generator with four sets of three-phase windings generates alternating current (AC) power
Implementation Method 2
converting the AC power produced by the PMG into a DC output with a rectifier section. The rectifier section includes: a first six-pulse rectifier connected to the first set of windings
Data Source
AI summary
An aircraft power generation unit to generate direct current (DC) power provided to a load includes a permanent magnet generator (PMG) that includes first, second, third and fourth sets of windings, each of the winding sets including three windings and a rectifier section with four six pulse rectifiers the produce outputs of Vdc1 to Vdc4 respectively and a common local output bus. The unit also includes an output bus configured to be connected to the load and including a positive output bus rail and a negative output bus rail and a controller that receives an input signal from at least one of the output sets and selectively couples either the common local output bus and fourth rectifier negative rail to the output bus negative rail and one or more of the first to third six-pulse rectifiers to the output bus positive rail to provide a constant voltage to the load.