P.32
The structure of single-phase series motor decides it can use not only alternating current
but also DC. To predigest its circuit and reduce cost of this machine, it is usually to use
AC practically. Between the exciter windings and the armature windings are in series one
single-phase power supply. When it is in a positive and negative half-cycle AC, the
current passing the exciter windings and the armature windings are shown in the figure C
and D separately. In a word, the revolve direction of series motor which is used to AC
power supply has nothing to the power supply.
Change the shift of single-phase series motor before change the series polity of the exciter
windings and the armature windings, and show in the figure E.
Series motor usually changes voltage to adjust its rotate speed and the calculating
formula of its rotate speed is following:
(r/min)
E------inductive-voltage of the armature windings
a------the number of shunt-wound pairs of the armature windings
P------the number of magnetic polity
average flux of magnetic polity
N------the number of windings of armature windings
From the followed formula, if you change the structure parameter (P, N, a) of single-phase
series motor, and you can change its rotate speed. But as for the typed series motor, you
can change E and by adjusting the voltage value of the motor to change its rotate speed.
For drum washing machine, modulate the voltage using the electronic actiyator or the
PCB panel to adjust its rotate speed.
n=60aE/(PØN)
Ø------
n
+
-
n
+
-
Figure C: rotor revolve direction in
a positive half-cycle AC
Figure D: rotor revolve direction in
a negative half-cycle AC
n
+
-
S
N
n
+
-
N
S
Figure E:rotating direction of motor after change the series polity of the
exciter windings and the armature windings
4.OVERVIEW OF MAIN COMPONENTS
