Curtis 1205 Guide de dépannage télécharger pdf (Page 43)

Curtis 1204/1205 Manual, Rev. C

Plug braking

The vehicle can be braked electrically by selecting the opposite direction

with the forward/reverse switch without releasing the throttle. When the

motor is reversed, the armature acts as a generator; the controller regulates

the current in the motor ﬁeld winding to give an appropriate level of plug

braking torque. The vehicle brakes smoothly to a stop, then accelerates

in the other direction. (NOTE: The controller may be unable to provide

plug braking if the vehicle is moving too slowly for the motor to generate

the necessary plug braking current.)

The plug current limit is factory set to meet customer requirements.

On some 1204/1205 models, the plug current limit is adjustable via an

externally accessible trimpot. See Section 4 for adjustment instructions.

If plug braking is not desired, the vehicle can be wired so that

moving the forward/reverse switch through neutral causes the vehicle to

freewheel as long as the accelerator is applied. If the throttle is released

and reapplied, plug braking will then occur. To inhibit plug braking in

this way, your controller must have the optional HPD feature. Wiring

details are provided in Section 3.

A 1 kHz tone may be heard during plug braking.

PWM

PWM (

Pulse Width Modulation), also called “chopping,” is a technique

that switches battery voltage to the motor on and off very quickly, thereby

controlling the speed of the motor. Curtis 1200 series controllers use high

frequency PWM—15 kHz—which permits silent, efﬁcient operation.

PWM is described in more detail in Appendix B.

Smooth, stepless operation

Like all Curtis 1200 Series controllers, the 1204 and 1205 models allow

superior operator control of the vehicle’s drive motor speed. The amount

of current delivered to the motor is set by varying the “on” time (duty

cycle) of the controller’s power MOSFET transistors. This technique—

pulse width modulation—permits silent, stepless operation. Pulse width

modulation is described in Appendix B.

Thermal protection

Because of their efﬁciency and thermal design, Curtis controllers should

barely get warm in normal operation. Overheating can occur, however, if

the controller is undersized for its application or otherwise overloaded.

If the internal temperature of the controller exceeds 75°C (167°F), the

6 — GLOSSARY

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Curtis 1205 Guide de dépannage Page 43