چییە سەلێکدراو ترانسفۆرمەر؟ 2025Tech، سەرەکە و پڕینسیپیەکان بڵاو کراون

Noah

qalab: Dizajin & Baxtinîve

Australia

1. Pêşkçûya Cihazek (SST) çi ye?

1.1 Asîyên û Piranên Pêşkçûyanên Serast

Nivîsarka di hemena derbasde yên pêşkçûyanên serast (wêne Stanley's 1886 patent) û asîyên bingehîn de dîsa berjêrhat. Ber bi endamindarîya elektromagnêtîk, pêşkçûyanên serast ji nîvekanên silîkon demir, kirlîşeyan ên lîlî yane alûmînyum, û sisteman ên îzolasyon û berrdarxistin (mineral oil yane dry-type) tevgerandin. Wan di heman deqên serastan (50/60 Hz yane 16⅔ Hz), bi rêzanên serkeftina berjêrhatiya serast, guhertina girtîna, û xasînên deqa hewcekirin.

Zeviyên pêşkçûyanên serast:

Bi xercê bikar
Bikara zor (efficiency >99%)
Bikara herîna girtîna sereka qurt

Piranên bin include:

Mezin û bêr
Berbendîna harmonîk û DC bias
Taybetmendîya parastina overlaod
Rizgar û piranên cîhanî

1.2 Pêşnûma û Rewşa Pêşkçûya Cihazek (SST)

Pêşkçûya Cihazek (SST) divê jî pêşkçûyek alternatif be pêşkçûyanên serast ber bi teknolojiya elektrîkî ya guhertina guhertin, ku rewşa wekî "electronic transformer" concept di 1968 de yên McMurray. SSTs di heman deqên Medium-Frequency (MF) isolation stage de berjêrhatiya voltage transformation û galvanic isolation hêsan, û taybetmendîya control functions da zêde kirin.

Rewşa bingehîn a SST:

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

2. Piranên Design a SSTs

2.1 Piran: Handling Medium Voltage (MV)

Di heman deqên Medium-voltage (e.g., 10 kV) de hêsan bi ratingan ên voltage ên device-an ên semiconductors ên serast (Si IGBTs up to 6.5 kV, SiC MOSFETs ~10–15 kV). Bi heman wêne, approach ên multi-cell (modular) yane single-cell (high-voltage device) hewcekirin.

Zeviyên multi-cell solutions:

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

Zeviyên single-cell solutions:

Simpler structure
Suitable for three-phase systems

2.2 Piran: 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 Piran: Reliability

Pêşkçûyanên serast zor bikara, û SSTs ji bo semiconductors, control circuits, û cooling systems an hilbijart, ku reliability piran ek rastî. Nivîsarka Reliability Block Diagrams (RBD) û failure rate (λ in FIT) models, navkirina redundancy dikare system reliability biguheze.

2.4 Piran: 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 Piran: 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 Piran: 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 Piran: 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 Piran: 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 Piran: 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 Piran: 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 Piran: 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.