JL/X130 - 1680
3
2.1 Operation of Slip Ring Motor
2.1.1 Stator Voltage Control
The Speed / Torque curve for a Slip Ring Motor is shown in the diagram below for the case where the Rotor
resistors are static.
The curved lines represent the Speed / Torque
relationship at 100% and 80% Stator voltage.
The voltage on the Stator is controlled by adjusting the
phase angle of the 3 phase thyristor stack within the
JL/X. This is controlled with reference to the speed
setpoint and speed feedback.
In this case it is possible to alter the speed of the motor
for a given load, requiring the same torque, by adjusting
the Stator voltage.
A reduced Stator voltage will reduce the the peak torque
by approximately the square of the voltage reduction.
Here a reduction in Stator voltage from 100% to 80%
will reduce the speed from 78% to 63%
2.1.2 Bi-directional control using the JLX
The JL model has a single 3 phase stack with 3 pairs of anti-
parallel thyristors which provide a phase controlled 3 phase
ouput driving the Stator. Thyristor pairs are 1, 2 and 3
The JLX model has 2 further pairs of anti-parallel thyristors
(4 and 5) which allow the direction of the Stator phase
rotation to be reversed. In this case the Stator is driven by
Thyristor pairs 1,4 and 5.
This implementation allows all 4 quadrants of Speed and
Torque to be controlled.
