OVMS User Manual page 44

OVMS: Renault Twizy User Guide 2019/05/02 RT3.9.1
...will set drive level to 70%, activate auto power with ref=18.1 kW and minimum=10%, set
kickdown threshold to 30 and compensation zero to 100.
Currently the compensation factor (1/8) is fixed, as well as the kickdown release delay (5 seconds).
Be aware that the OVMS will not always be able to react immediately on a kickdown event. For
example an ongoing network data transmission needs to finish or time out before the next kickdown
check can be done. The kickdown event is not "lost", just the drive level adjustment will be delayed.
This is normally in the order of some tenths of a second, but recognizable. To get best kickdown
reaction times, cut down data transmissions – for example don't use GPS streaming (or at least
restrict to streaming mode 1).
Ramps and smoothing
These control how the SEVCON shapes the actual torque curve depending on the driver input
(throttle and brake pedals).
Higher ramp levels mean faster changes. Lower smoothing means less leveling out.
The first ramp parameter ("start") is mapped to the gear box oscillation damping ramp. It depends
on your gear box quality how high you can set this.
Important note: the "start" ramp actually applies to every load change situation, so for starts as
well as for transitions from driving to braking and vice versa. There's a side effect from this: if you
set this ramp too fast combined with high recuperation, an abrupt change to braking/neutral can
trigger the recuperation power limitation function, as a sudden gear hit can produce a current peak.
This can also lead to a feedback loop between torque ramping and power limiting, if you encounter
that you really need to lower the ramp. Also take into account that raising maximum torque and/or
the overall ramp speeds (RAMPL, see below) can make lowering the start ramp necessary as well.
Since version 3.4.0, the start ramp parameter is interpreted in per mille and allows a range of
1..250. This is to allow fine control over this ramp, most Twizy gear boxes will not allow to make
the ramp much faster than the default (40 per mille on T80, 30 on T45).
The overall rpm change limits for all ramps can be set using the RAMPL command. Default ramp
limits are 6000 rpm/s for both acceleration and deceleration, which translates to 30% of the valid
range. 100% will primarily affect intermediate accelerations and decelerations.
Note: even if you set the start and accel level to 100% there still is a short start delay. The source of
this delay needs to be identified yet, current candidates are the maximum rpm change per second
(0x2920.15) or some throttle pedal signal smoothing (0x3814). There's also a battery current ramp
that could apply.
Twizy 45
The OVMS firmware reads the controller type on every login and automatically uses the
appropriate parameter defaults. This means you can plug a T80 OVMS module into a T45 any time,
and vice versa. Caveat: if you upgrade your T45 to a G4845, the OVMS will think this is a Twizy
80 – this will not work without modifications.
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