With the breeding phase winding
down, shot-gun season upon me and having no new ideas to try, I did all I could think to do: I relied on history.
where [u.sub.a], [u.sub.b], and [u.sub.c] are the terminal phase voltages of three-phase windings; [i.sub.a], [i.sub.b], and [i.sub.c] are phase winding
currents; [e.sub.a], [e.sub.b], and [e.sub.c] are trapezoidal back-EMFs; and L, R, [U.sub.N], and [[omega].sub.m] are the stator equivalent inductance, phase resistance, neutral point voltage, and mechanical angular velocity of the BLDC motor, respectively.
All In the premise of no influences of control performance, Experimental assumptions are as follows (Hemati, 1990): stator of a brushless DC motor is completely symmetrical, three-phase windings use Y-connected style, each phase winding
difference at 120[??], and each winding's resistance and inductance are the same.
In the fully-aligned position, the phase winding
inductance is maximum and the reluctance of the magnetic circuit is minimum.
In order to carry out the d axis current decay tests, the U phase winding
should be series connected with the parallel connected V and W phase windings
as shown in Fig.
where u is the applied voltage, R the winding resistance, [L.sub.e] the end winding inductance, l the axial length, s the conductor area of each turn of phase winding
, and [[OMEGA].sub.e] the total cross-sectional area of conductors of each phase winding
Connection of concentrated double layer short pitch coil six- phase winding
However, the current should be constant in the phase winding
when the load is important.
* A single phase winding
that provides easy control.
e) If the start and the end of each phases of block wave winding are connected in short or through an additional resistance, we can get a phase winding
similar to a rotor winding of conventional IM.
The number of turns per phase winding
of a conventional electrical machine is used to scale its operating voltage, which leads to the core of the proposed novel drive: there is only half a turn per phase.