Page 7
Uni Instructions
Braking
Regenerative braking is usually a desirable feature
whenever a controller is used from batteries and there
are very few instances where it is disadvantageous.
However for fixed use, from a mains power supply,
braking may prove a problem since, during braking,
energy is returned to the power supply where it can
pump up the power supply to about 36v(for the 24v
version), which could cause failure of some power
supplies.
From Issue 7 boards, it is possible to alter the board
to disable regen braking. Full details are in the
service section of our www site.
http://www.4qd.co.uk/serv/
Reversing
The Uni controllers are non-reversing.
4QD also manufacture reversing controllers such as
the VTX range. These are designed to decelerate and
reverse the motor properly even if the reversing
switch is operated at high speed.
However reversing can be done by a heavy duty
switch or relay.
You will require a double pole changeover switch or
relay to swap the armature connections. The diagram
on the back page shows the wiring.
The normally open contact of one pole connects to
the normally closed contact on the other pole and
vice versa.
Note that motor connects to the moving contacts. If
one pole of the switch jams the moving contacts can
short together which might damage the controller but
will not harm the motor.
Adjustments
There are three adjustments available: Gain,
Acceleration and Deceleration. These are indicated
on the drawing, above.
Important
: use an insulated screwdriver when
making adjustments: the metal centres of the
adjustments are 'live' to the internal circuitry. If a
non-insulated screwdriver touches anything other
than a preset the circuit can be damaged.
Gain
Adjust this so that, at maximum required pot rotation,
the controller just reaches full speed. This is easiest to
do with the motor unloaded (i.e. with the wheels
chocked up). Set the speed pot to your required
maximum point then, listening to the motor, adjust
the preset. It is usually quite easy to tell when the
motor stops accelerating and reaches full speed.
If you set the gain control too high, the controller will
probably cut out at full throttle: this is the pot fault
feature which can be implemented fully. See page 5.
As supplied, the controller is set so that it works
properly with a standard 10K pot. You may have to
readjust with, for example, a twist-grip throttle.
For the more technical:
The controller feeds
approximately 5.6v to the top of the pot. With the
gain at maximum, full speed is at about 3.5v on the
pot wiper (pin C) and at about 4.5v, pot fault
operates and the controller cuts out.
Acceleration
This adjustment controls the rate at which motor
speed increases if you turn the pot sharply up. Adjust
it to suit your machine.
Deceleration
This adjustment controls the rate at which motor
speed decreases if you turn the pot sharply down.
Adjust it to suit your machine.
If you get these adjustments wrong, little harm will
be done but the machine’s stopping and starting will
either be very jerky because it responds too rapidly,
or it will seem unresponsive as you have to wait for
anything to happen!
