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October 2004 SC2000 Manual – 177/52301 Rev G Page 25
10.1.12 Regen Braking
- Regen provides vehicle braking by controlling the motor as a generator and
returning the generated energy back to the battery. Regen braking reduces motor heat dissipation
compared with plug braking. Regenerative braking can be initiated in 3 ways, each with an
independently settable braking level, as follows:
i) A direction switch change will initiate regen braking at a level set by the Direction Brake
Current level. Braking effort is proportional to the accelerator position, with a minimum
accelerator pedal position giving 50% of the set brake level increasing to 100% for a fully
depressed pedal. The proportionality range allows the driver to modify the braking effort
without allowing freewheeling. The proportionality feature is optional and can be configured in
the setup menu to give fixed braking at the set personality level.
ii) Closure of the foot-brake switch in neutral, will initiate regen braking at the Footbrake
personality level. An input is provided to allow braking effort to be proportional to the
Footbrake position if a potentiometer is fitted. Setting a 0 into the personality disables braking
on the Footbrake switch.
iii) When neutral (i.e. there is no direction selected or
FS1 is opened) is selected, regen is
initiated at the Neutral Brake Current level. Setting a 0 into the personality disables neutral
braking and allows freewheeling. Neutral braking will only be attempted if the % on in the
previous direction exceeded 20% above the set creep level. This helps minimise
unnecessary delays and contactor operations.
Regen braking is some times not possible at low speeds depending on the motor
characteristics. To help minimise delays attempting to regen, a Regen Time adjustment is
offered which can be set so that Regen is only attempted for a short period of time, which is
sufficient to initiate regen at medium to high speeds but not to cause unnecessarily long
delays at very slow speeds where regen is not possible. If the Regen Time setting is
increased then regen can be initiated at lower speeds. Setting the Regen Time to 0 disables
regen and forces plug braking only.
If regen is not possible due to low vehicle speed, the following action will be taken:
1) For direction braking, plugging will be used to slow, then reverse the vehicle.
2) For neutral or footbrake braking, the vehicle will freewheel.
The switching frequency in Regen is high frequency and silent.
10.1.13 Plug Braking
- Plug braking is achieved by controlling the rotating motor armature as a
generator and dissipating most of the energy in the motor and the plug diode.
For plugging-only controllers, the conditions for initiating braking are identical to those for regen
controllers: on a direction change, footbrake switch and in neutral. Plugging also operates on regen
controllers if the truck has been travelling too slowly to initiate regen direction braking.
The switching frequency in the Plug braking mode is high frequency and silent.
10.1.14 Brake Constant Factor
- This adjustment has been added to match braking levels between
Regen and Plug braking.
The plugging current on regen controllers is equal to the direction change regen current multiplied by
the constant factor. For example, if direction change regen in neutral is operating at 100A, a factor of
0.8 would give 80A of Plug braking when regen was not possible due to low vehicle speed.
This adjustment is not necessary on plugging-only applications as the 3 braking adjustments
are now dedicated to plug braking levels.
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