title: Tutorial 902: Transformer Design¶

Tutorial 902: Transformer Design¶

Overview¶

Design and simulate power transformers for switched-mode power supplies. Learn to model ideal and non-ideal transformer behavior including leakage inductance, winding capacitance, and core saturation.

Level: Advanced (3/3)

Duration: 45-60 minutes

Series: Magnetics & Mechanical

Status: Placeholder - Circuit files to be added

Learning Objectives¶

• Design transformers for flyback, forward, and full-bridge converters
• Model leakage inductance and its effects
• Simulate winding capacitance and high-frequency behavior
• Understand transformer core selection

Transformer Equivalent Circuit¶

Complete Model¶

    Primary                                    Secondary
    ───┬──[Rp]──[Llkp]──┬────n:1────┬──[Llks]──[Rs]──┬───
       │                │           │                │
      Cp               Lm          Rc               Cs
       │                │           │                │
    ───┴────────────────┴───────────┴────────────────┴───

Design Procedure¶

Step 1: Determine Requirements¶

Step 2: Select Turns Ratio¶

n = Np/Ns = (Vin × D) / (Vout × (1-D))  [Flyback]
n = Np/Ns = Vin × D / Vout              [Forward]

Step 3: Calculate Magnetizing Inductance¶

For flyback (energy storage):

Lm = (Vin × Dmax)² / (2 × Pout × fs)

For forward (no energy storage):

Lm > (Vin × Dmax) / (ΔIm × fs)

Step 4: Select Core¶

Area product method:

Ap = Aw × Ac = (Pout × 10⁴) / (Kw × Bmax × fs × J)

Step 5: Calculate Turns¶

Np = (Vin × Dmax) / (Bmax × Ac × fs)
Ns = Np / n

Exercises¶

Exercise 1: Ideal Transformer¶

1. Model ideal transformer with n = 10:1
2. Apply 100V AC at 100kHz
3. Verify Vs = Vp/n

Exercise 2: Leakage Inductance¶

1. Add 2% leakage to flyback transformer
2. Observe voltage spike at turn-off
3. Design snubber to limit spike

Exercise 3: Core Saturation¶

1. Model transformer with Bsat = 0.3T
2. Apply excessive volt-seconds
3. Observe saturation effects

Circuit Files¶

Status: Placeholder - transformer_ideal.ipes - transformer_leakage.ipes - transformer_fullmodel.ipes

Tutorial Version: 1.0 (Placeholder)