Hvað er fastastaða ummyltingsgervi? 2025Tech Skýring á skipan og stefnur

Svæði: Hönnun & viðhald

Australia

1. Hvað er fastastöðuþrýstur (SST)?

1.1 Grundvallaratriði og takmarkanir hefðbundinnar þrýstara

Grein hefur fyrst yfirferð yfir sögu (t.d. Stanley's einkaleyfi árið 1886) og grundvallaratriði hefðbundinnar þrýstara. Byggðar á rafmagnsinductance, eru venjulegar þrýstara samsett af silícíjárstálkerfi, kopar eða alúmínívélbandum og dreifis/valda kerfi (mineralóli eða dry-type). Þeir virka við fast frekvens (50/60 Hz eða 16⅔ Hz), með fastu spennaumbreytingarhlutföld, orkuflæðistækni og frekvens eiginleikar.

Forskur hefðbundinnar þrýstara:

Lágt verð
Hátt traust (efficiency >99%)
Takmarka sturtström

Ungerskur inniheldur:

Stór stærð og tungur vægi
Følsamur fyrir harmonics og DC bias
Engin ofbyrðingarskydd
Brandar og umhverfisris

1.2 Skilgreining og uppruni fastastöðuþrýstara

Fastastöðuþrýstur (SST) er aðgerð við hefðbundna þrýstara byggð á rafmagnstechnology, með upprunum til McMurray's "electronic transformer" hugmynd árið 1968. SST-nir ná spennaumbreytingu og galvanic isolation gegn Medium-Frequency (MF) isolation stage, en skapa líka mörg intelligent control functions.

Grundvallaratriði SST-innar inniheldur:

Medium-Voltage (MV) interface
Medium-Frequency (MF) isolation stage
Communication and control links

2. Hönnunarherðir SST-ra

2.1 Herð: Að vinna við Medium Voltage (MV)

Miðalstraumsstig (t.d. 10 kV) fara langt yfir spennugreinar núverandi semilegir einblái (Si IGBTs upp í 6.5 kV, SiC MOSFETs ~10–15 kV). Því miður, verður annaðhvort multi-cell (modular) eða single-cell (high-voltage device) aðgangur að vera valdir.

Forskur multi-cell lausnir:

Modular og redundant hönnun
Multi-level output waveforms, reducing filter requirements
Support for hot-swapping and fault tolerance

Forskur single-cell lausnir:

Einfaldari strauktur
Eignar fyrir three-phase systems

2.2 Herð: Topology Selection

SST topologies can be categorized as:

Isolated Front-End (IFE): Isolation before rectification
Isolated Back-End (IBE): Rectification before isolation
Matrix converter type: Direct AC-AC conversion
Modular Multilevel Converter (M2LC)

2.3 Herð: Reliability

Venjulegar þrýstara eru mjög trúaðar, en SST-nir innihalda margar semilegar einblái, stýringarvefur og valda kerfi, sem gerir reliability að mikilvæga athygli. Greininni hefur Reliability Block Diagrams (RBD) og failure rate (λ in FIT) models, sem benda til að redundancy getur marktækt bætt við system reliability.

2.4 Herð: Medium-Frequency Isolated Power Converters

Common topologies include:

Dual Active Bridge (DAB): Power flow controlled via phase shift, enabling soft switching
Half-Cycle Discontinuous Mode Series Resonant Converter (HC-DCM SRC): Achieves ZCS/ZVS, exhibiting "DC transformer" characteristics

2.5 Herð: Medium-Frequency Transformer Design

Medium-frequency transformers operate at kHz-level frequencies, facing challenges such as:

Smaller magnetic core volume
Conflict between insulation and thermal management
Uneven current distribution in Litz wire

2.6 Herð: Isolation Coordination

Medium-voltage units require high insulation to ground, necessitating consideration of:

Combined 50 Hz power frequency and medium-frequency electric field stress
Dielectric losses and risk of localized overheating

2.7 Herð: Electromagnetic Interference (EMI)

Common-mode currents generated during MV switching can flow to ground through parasitic capacitance and must be suppressed using common-mode chokes.

2.8 Herð: Protection

SSTs must handle overvoltage, overcurrent, lightning strikes, and short circuits. Traditional fuses and surge arresters remain applicable but should be combined with electronic current limiting and energy absorption strategies.

2.9 Herð: Control

SST control systems are complex and require a hierarchical structure:

External control: Grid interaction, power dispatch
Internal control: Voltage/current regulation, redundancy management
Unit-level control: Modulation and protection

2.10 Herð: Construction of Modular Converters

Building practical MV modular systems involves:

Insulation design
Cooling systems
Communication and auxiliary power
Mechanical structure and hot-swappable support

2.11 Herð: Testing of MV Converters

MV testing facilities are complex and require:

High-voltage, high-power sources/loads
High-precision measurement equipment (e.g., high-voltage differential probes)
Backup test strategies (e.g., back-to-back testing)

3. Applicability and Use Cases of SSTs

3.1 Grid Applications

SSTs can be used in power grids for:

Voltage regulation and reactive power compensation
Harmonic filtering and power quality improvement
DC interface integration (e.g., energy storage, photovoltaics)

However, compared to conventional Line Frequency Transformers (LFTs), SSTs face an "efficiency challenge":

LFT efficiency can reach 98.7%
SSTs typically achieve only ~96.3% due to multi-stage conversion
Limited reduction in size and weight (~2.6 m³ vs. 3.4 m³)
Significantly higher cost (>52.7k USD vs. 11.3k USD)

3.2 Traction Applications

Traction systems (e.g., electric locomotives) have stringent requirements for size, weight, and efficiency, where SSTs offer clear advantages:

Significantly reduced transformer size through higher operating frequencies (e.g., 20 kHz)
Dual optimization of efficiency and volume reduction

3.3 DC-DC Applications

In DC systems (e.g., offshore wind power collection, data centers), SSTs are the only viable isolation solution, as their operating frequency can be freely chosen without being constrained by grid frequency.