Apparatus and method for measuring physical properties of hairpin coils, and method of forming hairpin coils based on the same

1 . An apparatus for measuring physical properties of hairpin coils, comprising:

a first current sensor configured to perform a first measurement prior to a flattening process on a material of a hairpin coil, by applying a first current for a frequency to the material to measure a first induced current applied to the material;

a measurement processor configured to measure physical properties of the material by measuring an impedance of the material with the first induced current measured by the first current sensor and applying the impedance to an established distribution and a trend of the established distribution to extract an induced current parameter that reflects the physical properties of the material;

a flattening process module configured to perform a flattening process after the first measurement by wounding the material around a bobbin by pressing the material with a plurality of rollers;

a second current sensor configured to perform a second measurement after the flattening process, by applying a second current for the frequency to the material to measure a second induced current applied to the material,

wherein the measurement processor is further configured to, based on the induced first and second currents respectively measured by the first and second current sensors, extract a change in the physical properties before and after the flattening process due to a plastic deformation occurred during the flattening process, and transmit the change in the physical properties to a process processor for forming the hairpin coils.

2 . The apparatus according to claim 1 , wherein the first current sensor is configured to be in contact with the material to measure the first induced current generated in the material in a non-destructive manner.

3 . A method for measuring physical properties of hairpin coils, comprising:

applying, by a first current sensor, a first current for a frequency to a material of a hairpin coil to measure a first induced current applied to the material;

measuring, by a measurement processor, physical properties of the material by measuring an impedance of the material with the first induced current measured by the current sensor and applying the impedance to an established distribution and a trend of the established distribution to extract an induced current parameter that reflects the physical properties of the material;

after the measurement, flattening the material by wounding the material around a bobbin by pressing the material with a plurality of rollers;

after the flattening, applying, by a second current sensor, a second current for the frequency to the material to measure a second induced current applied to the material;

based on the induced first and second currents respectively measured by the first and second current sensors, extracting, by the measurement processor, a change in the physical properties before and after the flattening due to a plastic deformation occurred during the flattening; and

transmit, by the measurement processor, the change in the physical properties to a process processor for forming the hairpin coils.

4 . The method according to claim 3 , wherein the induced current parameter comprises at least one of an amplitude, a phase, a real component, and an imaginary component of the induced current.

5 . The method according to claim 3 , wherein the physical properties of the material comprise at least one of yield strength, tensile strength, and elongation of the material.