A vector triangle method for the measurement of inductance and capacitance

摘要

A vector triangle method for the measurement of the parameters of inductors, capacitors and resistors is described. The method can measure the values of the impedance, quality factor (Q factor) or dissipation factor (D factor) and is independent of the phase measurements, as it only involves the effective values of three voltages. The unknown impedance is connected in series with a known standard resistor and this series circuit is excited by a sinusoidal voltage. With the value of the known standard resistance and the absolute value of three voltages, namely, voltage applied, voltage across the standard resistance and the voltage across the unknown impedance, we can compute the value of the impedance and the Q or D factor of it by using the vector triangle relationship between the three voltages. The proposed scheme was implemented using a MSP430 microcontroller and tested.