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5.2.1 Back EMF control (load control)
LokSound decoders utilize fourth generation load
Control assuring constant speed regardless of the
actual load when using DC motors. Load control was
optimized and tested with motors from:
• ROCO®,
• Bachmann (Liliput),
• BRAWA®,
• Märklin®,
• LGB,
• Bühler,
• Mabuchi.
Load control may be deactivated (if desired).
Please note that load control is always turned off
when using AC motors – no matter what settings
are used.
AC motors are not suitable for load control
How to switch on load control
Set the first bit of CV 49. Read out the CV: load
control is deactivated if the value is 0 or 2. To activate
it, just add 1 to the actual value and enter. Example:
CV 49 reads 2. To activate load control set CV 49 to 3.
You will find a detailed description of all possible
values for CV 49 in Chapter 7.1.
Parameters of Back EMF control
The internally used PI-control algorithm of Back EMF
control depends on 3 parameters: the control
reference voltage is stored in CV 53, the control
parameters are in CVs 54 and 55.
Reference voltage:
In CV 53 you set the voltage that should come back
from the motor.
This value depends on the track voltage and the
coefficient of utilization of the motor. A coefficient
of 75 % and a track voltage of 16 Volts adds up to
a voltage of 16 V * 75 % = 12 Volts. This value has
to be written into CV 56. The voltage (here: 12 V)
may be entered in 0.25V-increments. This results in
a value of 30 (12 V * 2.5) for CV 53. If you don't know
the exact motor coefficient, you may obtain the
value experimentally as follows:
Check if the engine really reaches top speed at the
highest speed step or if you cannot detect any speed
changes at the maximum speed step. In the latter
18
Back EMF control (load control)
case you have to reduce the value for CV 56, in the
first case increase the value. The internal PI regulation
of LokSound can be adjusted with CV 54 and CV 55.
Depending on the type of motor the parameters may
have to be adjusted to achieve optimal running
performance.
LokSound decoders are factory pre-set for the use
with ROCO®-, Brawa®- or Kato motors.
Parameter „K", stored in CV 54, influences how
strongly load control will effect the driving
performance. The higher the value, the more load
control will respond to any changes. Adjust this value
with care, because too high values could lead to
irregular and „hard" driving performance. If you
prefer smooth running, try to reduce the value step
by step until you reach an optimum.
Parameter „I", stored in CV 55 provides important
information to the LokSound decoder regarding the
motor type used: certain electric motors respond
differently to adjustments of the rpm's. The longer a
motor takes to respond, the lower the value in CV 55.
However, it is not easy to recognize the degree of
inertia. In general: the more poles a motor has and
the bigger it is, the more fly wheels it has, the slower
it is and the lower the value should be set in CV 55.
For optimal programming proceed as follows:
Read out the value in CV 53 as described above. Leave
the value of CV 55 (parameter I .I.) for the time being
and test the engine. Now change the value of CV 54
in steps of 5 downwards or upwards and monitor the
running properties of the engine. If there is no
improvement leave the value of CV 54 and change
the value of CV 55 (intensity of control) in steps of 5
until an optimum is reached.
Parameters for Fleischmann® motors
Engines with the traditional Fleischmann® motor
should be programmed as follows:
CV 54 = about 14 – 18
CV 55 = 20
User Manual LokSound / LokSoundXL V3.5, 4 th edition, 08/2005
Please note, that incorrectly set parameters
may impede the effect of Back EMF control
to the point that the motor may stop
altogether. Refer to our website http://
www.loksound.de for suggested values for
commonly used motor / drive combinations
such as:
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