Measure an inductor using a function generator and oscilloscope

inductor_measure.py

# Measure an inductor using a function generator and oscilloscope.
#
# Based on:
# https://www.tek.com/document/application-note/capacitance-and-inductance-measurements-using-oscilloscope-and-function-ge

import math
import quantiphy

def calc_inductance(f,Rref,Va1,Va2,phase):
    Z = (Va2*Rref)/math.sqrt(Va1*Va1-(2*Va1*Va2*math.cos(phase))+Va2*Va2)
    a = phase - math.atan((-Va2*math.sin(phase))/(Va1-Va2*math.cos(phase)))

    #print(Z,math.degrees(a))

    Resr = Z*math.cos(a)
    L = (Z*math.sin(a))/(2*math.pi*f)
    
    print("F:{}Hz: Inductance={}H ESR:{}Ohm".format(quantiphy.Quantity(f),quantiphy.Quantity(L),quantiphy.Quantity(Resr)))
    
    return(Resr,L)

# Reference numbers:
f = 10000
Rref = 1000

Va1 = 1.832
Va2 = 0.952
phase = math.radians(56.03)

[Resr, L] = calc_inductance(f,Rref,Va1,Va2,phase)

assert(math.isclose(Resr, 29.48, rel_tol=1e-04))
assert(math.isclose(L, 9.95e-3, rel_tol=1e-04))

# Measuring a CJIANG FNR201610S4R7MT
print("CJIANG FNR201610S4R7MT")

# Spec: 4.7uH +-20%, .479ohm max resistance, .7A saturation current

f = 1e6 # test frequency
Rref = 1e3 # reference resistor

Va1 = 18.3
Va2 = 0.478
phase = math.radians(86.5)

[Resr, L] = calc_inductance(f,Rref,Va1,Va2,phase)

f = 1e3 # test frequency
Rref = 1e3 # reference resistor

Va1 = 18.28
Va2 = 8.02e-3
phase = math.radians(2.8)

[Resr, L] = calc_inductance(f,Rref,Va1,Va2,phase)

# Measuring a CJIANG FNR201610R68MT
print("CJIANG FNR201610R68MT")

f = 1e6 # test frequency
Rref = 1e3 # reference resistor

Va1 = 19.79
Va2 = 78.4e-3
phase = math.radians(88.45)

[Resr, L] = calc_inductance(f,Rref,Va1,Va2,phase)