Zapi EPS-AC, Operating And Users Manual, Page: 31 / 52

Page 31
3) CREEP SPEED
Provides an increased torque for slow turning steering wheel. It's used to compen-
sate the drop in V/f (flux) when the frequency applied to the motor is low.
- Level 0 is for no torque compensation
- Level 9 is for a very strong torque compensation
Intermediate levels are for proportionally increasing torque setting. This parameter
is useful in two ways. First of all it guarantees a large torque for very slowly turned
handwheel. Secondly this large torque allows it to neutralize the elastic tire effect
when the handwheel is close to being released it.
4) COMPENSATION
Provides stator flux compensation. The ideal motor control provides constant flux
value for each working frequency. While CREEP SPEED provides low frequency
feedforward flux compensation effect, COMPENSATION produces a feedback flux
compensation effect. This is a very important setting for an application without the
shaft encoder be cause by turning compensation to a different value than zero gets
the motor flux (and torque) indipendent from the battery voltage. So torque is
guaranteed when the battery is low:
- Level 0 means no compensation but a flux degradation when current is too high
- Level 1 compensate the drop on power mosfets and cables
- Level 2 compensate the drop on power mosfets, cables and stator resistance
- Level 3 means no compensation.
This should normally be set to Level 2 as a strong compensation reduces the slip
(difference between the speed and the frequency applied to the motor). An
exception can be a smaller motor (small torque required) in which a strong flux (and
a greater magnetization current) is not necessary (Level 0).
5) ANTIROLLBACK
Adjusts the stand still torque value with a released handwheel. This setting is a
percentage of Imax. The stand still torque is used to neutralize the elastic tire effect
which would move the MDU an angle back in the direction it was coming from. This
parameter is specified as a percentage of the maximum current.
6) AUXILIARY TIME
Defines the time, after the handwheel is released, for which the stand still torque is
applied.
- Level 0 is for no stand still torque
- Level 1 is for a short application of a stand still torque (about 6sec)
- Level 9 is for a long application of a stand still torque (about 90sec)
Intermediate levels are for proportionally increasing auxiliary time.
7) AUX FUNCTION 3
Through the Can comunication, the traction chopper supplies the truck speed
information to the EPS-AC. The EPS-AC can reduce the steering motor speed as
the truck speed increase. Aux function 3 make it possible to alter the amount of the
max steering speed reduction with increasing truck speed.
- level 0
no effect
- level 9 maximum steering speed reduction