Curtiss-Wright | PG Drives Technology
SK77981-14
104 | R-net Technical Manual | Chapter 3 – Programming
Example:
Maximum Current Limit is set to 80A
Current Foldback Threshold is set to 50A
Current Foldback Time is set to 20 Seconds
Current Foldback Level is set to 50%
If the motor current is above 50A for a period of 20 Seconds, then it will reduce to 50% of 80A = 40A. It will then remain at this
reduced level for 5 x 20 Seconds = 100 Seconds.
12.3
COMPENSATION
This matches the Power Module to the motors used on the wheelchair. This is necessary to achieve optimal performance and
control, especially on a gradient.
The programmable range is 0mOhms to 500mOhms in steps of 5mOhms.
Curtiss-Wright recommend this value is initially set to 70% of the total resistance of the motor’s armature, and all the
connectors and cables between the motor and the Power Module motor output. Motor manufacturers should be able to supply
a figure for the motor’s armature resistance and typical connector and cables may be around 40mOhm.
Example:
The motor has a specified armature resistance of 100mOhms, and cables and connectors between the motor
and the Power Module are estimated to be 40mOhm. This gives a total value of 140mOhm. The value of
Compensation should therefore be set to 70% of 140mOhm = 100mOhm.
Once this value has been programmed, some drive testing should be carried out.
First of all, check that the wheelchair is controllable and comfortable to drive on a smooth, level surface. If it is not, th en the
value of Compensation may be too high and should be reduced.
Then drive the wheelchair towards a gradient at a very low speed, perhaps 10%. There should be no reduction in speed as the
wheelchair climbs the gradient. If the speed drops or the wheelchair stops, then the value of Compensation may be too low and
should be increased.
As a final check, drive the wheelchair up a gradient at full speed and release the joystick. The wheelchair should come to a
smooth, complete stop and should not rollback before the brakes are applied. If the wheelchair does roll -back, then try
increasing the value of Compensation sli ghtly. If the wheelchair appears to drive slightly up the gradient before the brakes are
applied, then the value of Compensation should be reduced slightly.
All these tests should be conducted when the motors are cold and hot.
WARNING:
These tests should be conducted in an open space and a restraining device such as a seat belt should always be used.
