The turn number of the inductor winding N increases, and the efficiency decreases because of the
copper loss. Based on the aforementioned trend, the inductor has the operation condition to maximize its power density for each switching frequency.
The reduction of stator
copper loss can improve the motor efficiency as shown in Fig.
The
copper losses are proportional to square of the stator current amplitude and can be calculated using:
According to the Joule's and Lenz's law, winding
copper loss is equal to the product of the resistance and square of the winding current.
Copper loss was calculated using measured resistance and current.
Interestingly, there was an inverse relationship between retention and
copper loss in that lowest retention samples showed that the micronized formulation lost about 30 percent as much copper as ACQ-D did while the highest retention samples showed that the micronized formulation lost about 10 percent as much copper as ACQ-D did.
The motor's
copper loss variations are shown in Fig.