Development and validation of an electrical and magnetic characterization device for massive parallelepiped specimens

Abstract

Claw pole machine performances are strongly related to the electromagnetic properties of ferromagnetic materials. These properties are impacted by the manufacturing processes, in a heterogeneous way, as well as by the thermal behavior of the machine and the mechanical stress distribution. Due to the complexity of CP geometry, extracted samples cannot respect the dimensions prescribed in international standards of electric and magnetic measurements. This paper proposes a specific methodology to characterize the electrical conductivity and the magnetic behavior of massive parallelepiped specimens extracted from different locations of a CP rotor.

Magnetic ageing investigation of bulk low-carbon silicon steel

“…Finally, ten samples (all samples except of S.1-E and F) were submitted to microstructural analysis and mechanical hardness test. The magnetic properties of the samples are measured with a specifically developed miniaturized SST (mini SST), as in [14], [15]. Indeed, as mentioned previously (see 2.1), because of the complex shape of the claw pole rotor and its relatively small size, the sample extraction is limited to small dimensions [14].…”

“…The magnetic properties of the samples are measured with a specifically developed miniaturized SST (mini SST), as in [14], [15]. Indeed, as mentioned previously (see 2.1), because of the complex shape of the claw pole rotor and its relatively small size, the sample extraction is limited to small dimensions [14]. The characterization of the B-H magnetic hysteresis loops is based on the flux-metric method.…”

“…In the configuration with a sensor having four aligned needles, a DC current is imposed between the outer pair of needles and the voltage is measured between the inner needles. However, since this method is dependent on the position of the electrical contact points and the shape of the sample, a geometry correction factor is applied as in [14], [17].…”

“…The difference of dimensions between the two sets is due to the fact that between the claws, the dimensions of the area do not allow samples longer than 27 mm to be extracted. It has been shown that, with our measurement device (see 2.3), developed in [14], a variation of length from 35 mm to 27 mm have few influence on the measured magnetic characteristics.…”

“…The four needles technic is no destructive which enables to measure several times the same sample during the ageing process like the sample S1.E and S1.F. According to the homogeneity of the electrical conductivity in the claw pole attested in [14] and [15], all the samples are supposed to have fairly close conductivities before ageing. Therefore, the electrical conductivity measured on the sample S.2-a is representative of those of the other samples.…”