Use a simplified thermal model:
| Parameter | Formula | Unit | |-----------|---------|------| | | ( E = 4.44 \cdot f \cdot N \cdot B_m \cdot A_e ) | Volts | | Turns per volt | ( TPV = \frac14.44 \cdot f \cdot B_m \cdot A_e ) | turns/V | | Primary turns | ( N_p = V_p \cdot TPV ) | – | | Secondary turns | ( N_s = V_s \cdot TPV ) (adjust for regulation) | – | | Core area (EI lamination) | ( A_e = \textstack \times \texttongue width ) | m² | | Window area | ( W_a = \textheight \times \textwidth of winding window ) | m² | | Copper area per winding | ( a_cu = I / \delta ) (δ = current density, e.g. 2.5 A/mm²) | mm² | | Wire diameter | ( d = \sqrt\frac4 \cdot a_cu\pi ) | mm | | Resistance | ( R = \frac\rho \cdot MLT \cdot Na_cu ) | Ω | | Copper loss | ( P_cu = I^2 R ) | W | | Core loss | ( P_core = \textspecific loss (W/kg) \times \textcore mass ) | W | | Regulation | ( %Reg = \fracI_p R_p \cos\theta + I_s R_s \cos\thetaV_s \times 100 ) | % | | Temperature rise | Approx. ( \Delta T = \fracP_totalA_surf \times k ) | °C | transformer design calculation excel
: This is the moment of truth. The spreadsheet calculates the "Window Space Factor"—the area inside the core where the wire must fit. If the total area of the chosen wires exceeds the available space (a fill factor over 100%), the Excel sheet might flash a red warning, telling the engineer to pick a larger core. The Verdict: Efficiency and Performance Use a simplified thermal model: | Parameter |