Prototyping of a CR-Type Ideal Integrator and DC Magnetic Properties

Abstract

The B-H loop is a widely used method of evaluating the magnetic properties of magnetic material. While AC excitation supplies are most commonly used, there are also citations in the literature for DC magnetic properties. The coercive force of magnetic materials is known to be dependent on excitation frequency, decreasing as excitation frequency decreases. The authors experimentally determined the B-H loop DC magnetic properties for the minimum excitation frequency. The experiment required an integrator with an opamp capable of generating stable B-H loops at 0.01 [Hz] or below. There has been no ideal CR-type integrator with an opamp yet because the opamp's gain cannot be increased to infinite. The authors resolved the problem of opamp infinite gain, and prototyped an integrator capable of generating stable B-H loops of 0.01 [Hz] or below, dubbed the CR-type ideal integrator, as described in this paper. The prototyped CR-type ideal integrator was used with a Ni-Fe-based amorphous, 2-3 [mHz] supermalloy magnetic core and an excitation frequency of about 20 [mHz] to generate what can be accurately described as a DC B-H loop. This prototyped CR-type ideal integrator enables B-H loop measurement as frequencies too low for existing CR-type integrators equipped with opamps.