OVMS User Manual page 33

OVMS: Renault Twizy User Guide 2019/05/02 RT3.9.1
it's been used on other vehicles (i.e. the german Hotzenblitz) and not as poor quality as it sounds.
For the driver protection, it should be obvious that the Twizy gets the harder to control the faster it
goes. After all this is a very light, very small vehicle with small wheels and poor aerodynamics.
Strong side wind is an issue at 80 kph already, especially if you're using addon windows. Bad roads
can make the Twizy jump. Now imagine a jumping Twizy at 100 kph... not funny.
Of course the motor power limits the maximum speed as well, even if you also raise the torque
level, an aerodynamically unmodified Twizy will run into it's power limitations finally at ~110 kph.
The SEVCON's severe overspeed fault level is set to 11000 rpm = ~121 kph, but that does not seem
to be reachable without a long steep downhill passage. Nevertheless, the macro commands will use
an upper limit of 10.900 rpm for all overspeed limits and an upper limit of 10.000 rpm for the
forward speed.
See below for necessary changes to the power map.
Torque
Higher torque means stronger acceleration and is especially useful when starting on a steep incline.
Using a higher torque results in higher battery and controller currents and higher load on the gear
box. Currents should (?) be limited to the safety frame defined by the basic controller configuration
and capabilities. The gear box is specified at a maximum output torque of 1000 Nm, this translates
to 108 Nm input torque.
Of course, higher currents will also mean higher temperatures for all components, this may be an
issue for hot climate conditions. All component temperatures are monitored, critical temperatures
will result in power cutback, but you should keep an eye on the OVMS temperature readings when
experimenting.
The Twizy motor has a rated torque of 57 Nm at 2100 rpm. Interestingly, only 55 Nm are
configured usable by default in the SEVCON (0x6076 and points 1+2 in the torque/speed map at
0x4611), while the flux map (0x4610) is defined up to 70.125 Nm. The flux map also defines
maximum magnetising currents to be 149 A at 55 Nm and just +7 A (156 A) at 70 Nm.
So it seems the motor should safely be capable of producing 70 Nm (not continuous of course!) but
has been limited to 55 Nm, probably to provide a consistent drive experience for all battery SOC
levels and temperature conditions. The controller will do short boosts up to 540 A, and the motor is
specified for 175 A phase current. None of these limits will be exceeded by 70 Nm, but
temperatures will rise faster at this torque level.
70 Nm at 2100 rpm equals a mechanical output of ~15.4 kW. This would be ~18% above the
motor's rated output, so the power map will be adjusted (see below). Electrical input depends on the
actual load situation, but we can assume the controller will limit the power according to the
controller and battery current limits, so the full 70 Nm will probably not be available in every load
(and temperature) situation.
Higher torque levels (V3.7)
70 Nm has now (Dec 2015) been used since two years by many users without any problems so can
be considered safe. Beginning with V3.7, you can raise the torque level above 70 Nm if you also set
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