Methods for determining inductance and resistance of an inductor
View Patent ↗A resistor (having a resistance of R s ) is connected in series with an inductor whose inductance and/or resistance is desired to be determined. An alternating voltage (such as a sinusoidal voltage) is applied across the series-connected resistor and inductor, wherein the alternating voltage has a frequency ω, a unique maximum or minimum value V m , an average value and a unique crossover of the average value. The voltage V r is measured across the resistor when the alternating voltage is at its maximum or minimum value. The voltage V l is measured across the resistor when the alternating voltage is at its average value. The resistance R L of the inductor is calculated from an equation in which R L is a function of V m , V r , R s and V l . The inductance L of the inductor is calculated from an equation in which L is a function of V l , R l , R s , V r and ω.
1. A method for determining the inductance L of an inductor comprising the steps of:
a) connecting a resistor in series with the inductor, wherein the resistor has a resistance of R s ;
b) applying a sinusoidal voltage across the series-connected resistor and inductor, wherein the sinusoidal voltage has a frequency ω, a maximum or minimum value V m and an average value;
c) measuring the voltage V r across the resistor when the sinusoidal voltage is at its maximum or minimum value;
d) measuring the voltage V l across the resistor when the sinusoidal voltage is at its average value;
e) calculating the resistance R L of the inductor from the following equation: R L =V m V r R s /(V r 2 +V l 2 )−R s and
f) calculating the inductance L of the inductor from the following equation: L=V l (R l +R s )/(V r ω), wherein any initially calculated negative value of L has its sign changed to a positive value.
2. The method of claim 1 , wherein the inductor is a coil.
3. The method of claim 1 , wherein the inductor is a circuit.
4. The method of claim 1 , wherein the average value is zero.
5. A method for determining the inductance L of an inductor comprising the steps of:
a) connecting a resistor in series with the inductor, wherein the resistor has a resistance of R s ;
b) applying an alternating voltage across the series-connected resistor and inductor, wherein the alternating voltage has a frequency ω, a unique maximum or minimum value V m , an average value and a unique crossover of the average value;
c) measuring the voltage V r across the resistor when the alternating voltage is at its maximum or minimum value;
d) measuring the voltage V l across the resistor when the alternating voltage is at its average value;
e) calculating the resistance R L of the inductor from an equation in which R L is a function of V m , V r , R s and V l and
f) calculating the inductance L of the inductor from an equation in which L is a function of V l , R l , R s , V r and ω.
6. The method of claim 5 , wherein the inductor is a coil.
7. The method of claim 5 , wherein the inductor is a circuit.
8. The method of claim 5 , wherein the average value is zero.
9. The method of claim 5 , wherein the alternating voltage has a triangular waveform.
10. The method of claim 5 , wherein the alternating voltage has a sinusoidal waveform.
11. A method for determining the resistance R L of an inductor comprising the steps of:
a) connecting a resistor in series with the inductor, wherein the resistor has a resistance of R s ;
b) applying a sinusoidal voltage across the series-connected resistor and inductor, wherein the sinusoidal voltage has a frequency ω, a maximum or minimum value V m and an average value;
c) measuring the voltage V r across the resistor when the sinusoidal voltage is at its maximum or minimum value;
d) measuring the voltage V l across the resistor when the sinusoidal voltage is at its average value; and
e) calculating the resistance R L of the inductor from the following equation: R L =V m V r R s /(V r 2 +V l 2 )−R s .
12. The method of claim 11 , wherein the inductor is a coil.
13. The method of claim 11 , wherein the inductor is a circuit.
14. The method of claim 11 , wherein the average value is zero.
15. A method for determining the resistance R L of an inductor comprising the steps of:
a) connecting a resistor in series with the inductor, wherein the resistor has a resistance of R s ;
b) applying an alternating voltage across the series-connected resistor and inductor, wherein the alternating voltage has a frequency ω, a unique maximum or minimum value V m , an average value and a unique crossover of the average value;
c) measuring the voltage V r across the resistor when the alternating voltage is at its maximum or minimum value;
d) measuring the voltage V l across the resistor when the alternating voltage is at its average value; and
e) calculating the resistance R L of the inductor from an equation in which R L is a function of V m , V r , R s and V l .
16. The method of claim 15 , wherein the inductor is a coil.
17. The method of claim 15 , wherein the inductor is a circuit.
18. The method of claim 15 , wherein the average value is zero.
19. The method of claim 15 wherein the alternating voltage has a triangular waveform.
20. The method of claim 15 , wherein the alternating voltage has a sinusoidal waveform.