SMD power inductors diameter / number of turns is calculated

Source: Time: 2012-09-04 12:27:57

Power inductors load its inductance is calculated as follows: Formula coil

Impedance (ohm) = 2 * 3.14159 * F (operating frequency) * Inductance (mH), set the required 360ohm impedance, thus:

Inductance (mH) = impedance (ohm) ÷ (2 * 3.14159) ÷ F (operating frequency) = 360 ÷ (2 * 3.14159) ÷ 7.06 = 8.116mH

Accordingly wound coils can be calculated:

Number of turns = [{inductance * (18 * circle diameter (inches)) + (40 * Cycle Length (inches))}] ÷ circle diameter (inches)

Number of turns = [8.116 * {(18 * 2.047) + (40 * 3.74)}] ÷ 2.047 = 19 laps

Core inductor formula

Core inductor formula: L (mH) = (0.08D.D.N.N) / (3D + 9W + 10H)

Coil diameter D ------

N ------ turns

d ----- Wire

H ---- coil height

W ---- coil width

In mm and mH. .

Hollow coil inductance calculation formula:

l = (0.01 * D * N * N) / (L / D + 0.44)

Coil inductance l Unit: micro-henry

Coil diameter D unit: cm

The number of turns N Unit: turns

Coil length L Unit: cm

Frequency inductor-capacitor formula:

l = 25330.3 / [(f0 * f0) * c]

Operating frequency: f0 unit: MHZ The problem f0 = 125KHZ = 0.125

Resonant capacitor: c units: PF this question Jianyi c = 500 ... 1000pf are free to decide, or the Q

Value is determined

Resonant inductor: l Unit: micro-henry

1. For ring CORE, the following formula can be used: (IRON)

L = N2. AL L = inductance (H)

H-DC = 0.4πNI / l N = number of turns (turns)

AL = Inductance

H-DC = DC magnetizing force I = current through (A)

l = magnetic path length (cm)

l and AL size value, reference may Micrometal table. For example: In T50-52 timber, semi-circle coil 5, an L value of T50-52 (OD represented 0.5 inches), the look-up table its AL value of about 33nH

L = 33. (5.5) 2 = 998.25nH≈1μH

When electric current flows through 10A, the L value changes by l = 3.74 (look-up table)

H-DC = 0.4πNI / l = 0.4 × 3.14 × 5.5 × 10 / 3.74 = 18.47 (after a look-up table)

To learn the extent of decline in the value of L (μi%)

2. Describes an empirical formula

L = (k * μ0 * μs * N2 * S) / l

among them

for the permeability of vacuum μ0 = 4π * 10 (-7). (10 minus seven parties)

mu] S is the relative permeability of the magnetic core within the coil, when the hollow coil μs = 1

N2 is the number of turns squared

Sectional area S of the coil, in square meters

l the coil length in meters

k-factor, depending on the coil radius (R) and length (l) ratio.

Calculate the inductance Henrys.