Noniterative digital AC bridge balance

Abstract

This paper proposes an automatic digital ac bridge-balance technique, which is fast and suitable for high-frequency phase and impedance measurement. Digital ac bridges are balanced by least-mean-square algorithms in the feedback path. This traditional heuristic method is less efficient to converge to the balance point of the digital ac bridge unless certain parameters are appropriately selected. In this paper, a simple method has been proposed, in which balance parameters can be analytically computed by a microcontroller and a corrective action is fed to the digital bridge to achieve null. The technique has four stages of measurement to compute to reach bridge balance without any iteration. This method has a promising potential in the development of accurate miniaturized seamlessly frequency-adjustable eddy-current nondestructive test instruments. Simulation examples, along with the experimental results, are shown in this paper to emphasize the accuracy and reliability of this technique.