Re: Vehicle control observations

[Bernard M. <bme...@gm...>]

Hi Johannes,

Most of those "requests" you mentioned are incorporated in the QP version
of the code (i.e you can't start with throttle pressed, and the pre-charge
delays are done in software)
What code base are you running?

Cheers,
Bernie



On Mon, Apr 22, 2013 at 11:43 PM, Johannes Hübner <j...@jo...>wrote:

> Hi all,
>
> I'm am currently build a VW polo EV with the tumanako inverter of
> course. I have taken it on a few test drives and am still delighted by
> the performance of the simple slip control. It can do slight hill starts
> in 5th gear. Though I cannot compare it to FOC. The motor I use is rated
> 18,5 kW@120Hz.
>
> While driving was all smooth, there were a couple of observations that
> should be reflected in the software:
>
> - When the throttle is pressed or stuck and the inverter is started, the
> following happens:
>    - PWM is activated and generates a sine wave
>    - With the mechanical delay, the DC contactor closes
>    -> Contactor welds closed,it is not designed to switch loads.
>    -> There must be a delay between closing the contactor and starting
> the PWM
>    -> Maybe the start should be inhibited when the throttle > 0.
> - The other way around seems ok. If the inverter shuts down due to an
> error, the PWM is stopped and the contactor is opened. Due to the
> mechanical delay it does not weld closed. But maybe its advisable to
> insert an actual delay as well
> - When manually started (i.e. using the command console) the inverter is
> started but the contactor isn't closed. The precharge relay stays closed
> though. High current through the precharge resistor occurs and it
> overheats and fails.
>    -> Pay more attention to that stuff...
>
> I have also made some good observations:
> - Most vehicle signals are ground-switched, so using open collector
> outputs is perfectly sane.
> - I use the key switch for the actual power to the inverter. Saves an
> input and theres absolutely no current draw when ignition is off.
> -  For the 840µF bus capacitor in my inverter an 11W, 120R precharge
> resistor is sufficient. No heat sink required. It charges the caps from
> 0 to 480V in around a second. Also tried 5W, but that died after a
> handful of precharges.
>
> I will add low voltage, high voltage, temperature and BMS throttling
> next. Probably just linear derating curves that affect the maximum
> acceptable throttle input.
>
> Cheers,
> Johannes
>
>
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