Multi-Phase PMG Voltage Regulation via Passive Rectifier Segmentation
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Solution Overview
Problem
Conventional DC power generating systems using 3-phase variable-speed permanent magnet generators with active rectifiers require large passive components, leading to high costs and complexity, while multilevel topologies offer reduced harmonic distortion but are expensive and complex.
Innovation Solution
A power generating system incorporating a 9-phase permanent magnet generator with multiple six-pulse passive rectifiers and a boost DC to DC converter, where the output voltage is maintained constant by selectively coupling rectifiers and adjusting the duty cycle of the converter based on generator speed, allowing for reduced component size and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional two-level six switch active rectifier is used, then voltage regulation can be achieved, but the system requires large size passive components (dc link capacitor and output power quality filter) leading to high cost and complexity
Solution Approach 1:
The patent divides the single large passive component requirement into multiple smaller passive components distributed across multiple six-pulse rectifier bridges. Each bridge has its own smaller filter capacitor, eliminating the need for one large dc link capacitor while achieving the same voltage regulation effect.
Solution Approach 2:
The patent transitions from a single-phase active rectifier topology to a multi-phase passive rectifier topology, adding dimensional complexity in terms of phase multiplication while simplifying the control architecture. This dimensional change allows passive components to be distributed and reduced in size.
2Object-generated harmful factors
If multilevel topologies (unidirectional Vienna Rectifier or bi-directional neutral diode clamped multilevel converter) are used, then harmonic distortion is reduced with moderate switching frequency, but the system becomes complex and expensive
Solution Approach 1:
The patent uses multiple copies of simple six-pulse rectifier bridges instead of implementing a complex multilevel topology. By parallelizing identical simple units, the system achieves reduced harmonic distortion without the complexity of true multilevel converters, as each bridge contributes to harmonic cancellation through phase displacement.
3Power
If a 9-phase permanent magnet generator with multiple six-pulse passive rectifiers and boost DC to DC converter is used, then high power density with reduced losses is achieved, but the system requires selective coupling control based on generator speed
Solution Approach 1:
The patent implements dynamic switching of rectifier bridge connections based on generator speed. The controller selectively couples different numbers and combinations of six-pulse rectifier bridges to the output based on real-time speed conditions, optimizing power density across the operating range while maintaining manageable control complexity through rule-based switching.
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 with reduced losses, low torque pulsation, and affordable implementation by using passive rectifiers and a boost converter to maintain constant voltage across the output bus, independent of generator speed.
Implementation Method 1
A power generating system incorporating a 9-phase permanent magnet generator
Implementation Method 2
multiple six-pulse passive rectifiers
Implementation Method 3
boost DC to DC converter
Data Source
AI summary
An aircraft power generation unit to generate 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 control coil and a rectifier section that includes first through third six pulse rectifiers, a DC to DC to converter 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, wherein the negative output bus rail is connected to the negative output of the DC to DC converter and a controller that receives an input signal from at least one of the output sets and selectively couples the DC to DC converter and one or more of the first, second and third six-pulse rectifiers to the output bus.