Motor control





Motorsteuerung mit Schützen + RekuThe motor control is called also Chopper or pulse width modulator (and is made by Curtis Instruments - RRY) With direct current there is to produce actually only the switching status or OUT all other switching status in the motor control warmth (P=Ua x I). the controller switches thus only / out around a variable rate will achieve the power-output stage in the Chopper with a square wave signal with variable and from times headed for. (These preceding sentences need some more work by the translator - RRY) With slow travels only short pulses are given. The engine cannot wind up at will fast. The mass inertia and the inductance of the engine prevent this - the engine turns slowly. During faster travel the pulses become ever longer, until with " full power " the transistors are finally fully on. Additionally a current monitoring is inserted, which the armature current in the engine monitored (27Ä), as well as a temperature monitoring so that the power-output stage damage does not take.


Technical data

Specification without guarantee

Rated voltage 36V / rated current 270A / undervoltage disconnection 21V / potentiometer value 5kOhm (0k=Stop/5k=max)/equipped with 20 Transistoren á 20A / clock frequency approx. 15kHz


Depending upon year of construction of el there was different controllers. The rated current all controllers was alike, however the number of accessible automatic controls was different.

Adjustment possibilities

Ankerstrom=Armature current

The engine torque depends directly proportional on the armature current. The adjusting screw in addition is at the page of the engine plate under a Inbusmadenschraube. An adjustment is possible only with the three potentiometers version!

The controller is good for 275 Amp, straight from the factory, it for town center el scarcely over 200Amp is adjusted. With right tweaks, over 300 Amp are released, the controller can destroy itself.

With the increase of this value the torque increases in such a way that the mechanics are overloaded in el (belt drive), since it was not counted for this load. Among other things enormously the belt wear goes enormously up - in my best times the belt 1000km held. A machine-builder would pull his hair out, if he sees the torque the belt must transfer. On the other hand a Harley Davidson also uses a belt drive.

Stromanstieg=Current rate of rise

With the right potentiometer on the controller, the current rate of rise can be adjusted, i.e. the time it takes the armature current to rise from 0 up to max. Shorten this and hill climbing and starting from a standing stop will be improved ( at a possibly cost in battery life -RRY)

Nominally this time is at approx. 5 seconds set, which is very long, with 3 seconds it goes better.

Service + repair

Normally the Curtis is very reliable, so that no problems emerge here. If actually problems emerge to it, I would exchange the controller. With a repair the sealing compound must be removed around the links carefully, and remove the screws on the lower surface. One can remove electronics then from the aluminum housing. Once on a vehicle I serviced, a contact problem between two circuit boards had occurred. After I after-soldered these, again everything functioned.


Motorraum A well-known error is the controller failure, with vehicles before serial number 3006. There the controller is mounted vertically with the connections upward. Water failure can be the result. If you have such a vehicle, I recommend to seal the connections again (silicone or the like).


A controller failure can express itself apart from the total failure also in such a way that the vehicle drives or ruckelt only modulation rate.

On hot days during slow uphill drive it can also be the fact that the controller down-regulates temperature-dependent or switches off - leaves cooling -