Thursday, 26 February 2009

First real drive

After a trip to the local weighbridge, I now have the EV Grin! 
... and in the excitement I forgot to take a photo or video. arrgh!

The total weight is as expected.

Front: 628kg - 41%
Rear: 916kg - 59%
===========
Total 1544kg.

The original dry curb weight was 1265. 58%F 42%R
279kg heavier

First run efficiency is 2.4kwh / 7.2km = 333kwh/km.
The silly thing with the Danfoss is that I think that the 2.4kwh includes driving and regen.

Points to note:
This is not counting regeneration.
I was driving quite aggressively, but not fast. Max speed was about 60kph.
I live at the top of a 100m hill.
The motor and controller were only warm to touch, even after a 100m climb in less than 1km.
Regen was set at 20% (3kw)/. I should be able to increase this to 66% (10kw) to have the diesel braking effect.

I have the tachometer reading kW but unfortunately it peaks at the motor maximum (15kw) so is not very useful. I will switch tacho back to RPM.



Wednesday, 18 February 2009

Latest results tweaking the conroller. Good news finally!

Latest results:  

The good news
I am happy(er) with open loop speed control now. After many hours diving up and down our short driveway, and logging 10kms! I found that the throttle response was too precise. 

After a lot of fiddling I lowered the switching frequency to 4.5kHz because I was curious about audible noise at a lower switching frequency. As a result, the throttle response is much less aggressive. Makes sense after you think about it for a minute.

I have also been able to decrease the acceleration ramp time without the 'bunny hopping'.  

The bad news. 
Closed loop and Torque open loop have been non starters. Perhaps you need many more that 40 pulses per revolution for closed loop to be useful. I still have a service call in with Danfoss as I would like to have the other control modes available.

Regardless the 40 pulse per revolution input is nicely scaled and outputs a programmable frequency that is proportional to speed to drive the speedo.

I also now have the tacho displaying Power output

Sunday, 1 February 2009

kWh Meter


I added a DIN rail kWh meter so I can assess the efficiency from wall to wheels. i will be able to calculate Wh/km. Hopefully it will be less than 250.

You can see after a few minutes of charging there has been 0.52kWh of electricity used.