phase winding

An alternative viewpoint is obtained from the circuit model for the phase windings.

(i) A physical system allows phase windings different from .

At very high operating speeds the voltage induced in the phase windings by the rotor motion must also be considered.

Continuous rotation of the motor is produced by sequential excitation of the phase windings.

These secondary flux paths produce mutual coupling between the phase windings of the single-stack stepping motor.

The circuit operates by storing energy in the capacitor C, which can be discharged rapidly into the phase windings when additional torque is needed.

Polyphase synchronous motors rotate in a direction determined by the sequence of the currents in the phase windings.

The phase windings of a polyphase transformer can be connected internally in different configurations, depending on what characteristics are needed from the transformer.

The primary coil assembly consists of phase windings surrounded by steel laminations, and includes a thermal sensor within a thermal epoxy.

Correspondingly a vortex placed onto such a boundary acquires a fractional phase windings hence the term fractional vortex.

The full-step length of a stepping motor can be divided into smaller increments of rotor motion - known as "mini-steps" - by partially exciting several phase windings.

However the mini-step positions are critically dependent on the currents in each of the phase windings and any error in current level is translated directly into a position error.

A vortex resulting from such phase windings is called fractional or half-quantum vortex, in contrast to one-quantum vortex where a phase changes by .

The phase windings in a SRM are electrically isolated from each other, resulting in higher fault tolerance than inverter-driven AC induction motors.

Fig. 4.14(a) shows the variation of magnet flux linked with the two phase windings of a hybrid motor as the rotor position varies over a rotor tooth pitch.

The optimal drive waveform is not a pure sinusoid, due to the non-linear torque relative to rotor displacement, and the highly position-dependent inductance of the stator phase windings.

The transfer of energy to the electrical circuit is accomplished by means of the voltages induced in the phase windings when the rotor oscillates, so these voltages are considered first.

A hybrid motor has two phase windings, which are mounted on separate stator poles (Chapter 1) and therefore the phase circuit model must include the resistance and inductance of each winding.

The phase windings of both hybrid and variable-reluctance stepping motors are electrically isolated and each phase is excited by a separate drive circuit, so it is possible to excite several phases at any time.

Although the use of higher stack numbers is a great convenience to the manufacturer, it must be remembered that more phase windings require more drive circuits, so the user has to pay a penalty in terms of drive circuit cost.

Because the phase windings are situated on separate stator teeth in the single-stack motor, the mutual inductance is small and the error introduced in neglecting its torque contribution when several phases are excited is rarely more than 10%.

Physically, in a three phase winding a positive sequence set of currents produces a normal rotating field, a negative sequence set produces a field with the opposite rotation, and the zero sequence set produces a field that oscillates but does not rotate between phase windings.