Quasi-balanced bridge method for the measurements of the impedances

A measurement method called 'a quasi-balanced bridge' is described in this study. It can be applied for the determination of the value of the active and reactive impedance parameters separately, as well as the module and the phase of the electric circuit. This can be possible by using a false balancing bridge state, called a quasi-balanced state. This method gives the possibility of measuring the inductance, capacitance, resistance, quality factor, and dissipation factor of a component's impedance, without caring of the frequency influence. The quasi-balance corresponds to the phase quadrature between two arms of the bridge. The detection of the quadrature is given by using a synchronous detector. The automation of the bridge consists of conceiving a control system that acts in one of the bridge parameters to obtain the required state. The analyses illustrate that an accuracy better than 0.08% is possible using a simple configuration of a quasi-balanced bridge method. Experimental results are included to demonstrate its performances. The automation of the quasi-balanced bridge is made through an interface board of the type CIGAL exploiting a multiplier digital to analogue converter (MDAC) of the type (AD7542), which functions as a virtual potentiometer.