Hi Guys.
I'm in the UK and have a Renault Fluence ZE.
I've been lurking for a while, seeing what the 'Leaf' experience is like. I signed up mainly to access the 'search' function here (... can't search unless logged in, it appears!).
OK, well, I'll dive straight into what I was looking for here today - I was wondering if field weakening has ever been discussed?
Reason I'm asking is because the Fluence is a bigger, heavier car with a smaller battery, but it seems to have a better range? This isn't just the NEDC test talking (it reckons on Fluence at 115 miles, cf. Leaf at 109 miles). It's also me in dialogue with the one other private owner of a Fluence here in the UK I'm aware of. We get 100 miles range out of ours as a matter of routine. Well, in my case I've only done 300 miles in it in the week I've had it so far (so, not quite 'routine', perhaps). But my experience so far is consistent with the other guy who has put 2,000 miles on his.
Anyhow, I was wondering whether it comes down to the different motor technologies. The Leaf has a permanent magnet motor, and it'll have a design speed of around 3,000 rpm in the constant V/Hz region of operation. Above that, I presume it'll have to do some sort of field weakening scheme, which'll make it less efficient for fast, light load conditions. Usually, field weakening is done by injecting Q-axis current, which, in effect, opposes the magnetic fields of the PMs (in fact, in extremis, field weakening can begin to demagnetise PMs!).
The Renault ZE cars have Continental's coil rotor motors, which therefore don't need to perform any field weakening, and would therefore likely simply alter the field/phasing to pick [presumably] whatever V/Hz characteristic is demanded. I started out driving very cautiously so as to judge how much range I might get (I used the 'Leaf Range Chart' initially), but soon realised after covering nearly 30 miles on less than a quarter of indicated charge I was doing better than that chart. So I simply started picking the speed up and up. I now aim for 60~65 on the motorways, and aim to stay under ~15kW power up and down hills (I slow down to ~50 on the uphills I take, but would hit 80 on the downhills if I keep feeding in 15kW so I usually back off then). With that sort of driving, I get 4.7~5.2 M/kWh.
So, what do you guys think? Is field weakening sucking up some of the Leaf's range, or maybe we cruise more gently because we have less power at our toe-tips? Or is there some miscalculation of energy/distance afoot, or ... ?
I'm in the UK and have a Renault Fluence ZE.
I've been lurking for a while, seeing what the 'Leaf' experience is like. I signed up mainly to access the 'search' function here (... can't search unless logged in, it appears!).
OK, well, I'll dive straight into what I was looking for here today - I was wondering if field weakening has ever been discussed?
Reason I'm asking is because the Fluence is a bigger, heavier car with a smaller battery, but it seems to have a better range? This isn't just the NEDC test talking (it reckons on Fluence at 115 miles, cf. Leaf at 109 miles). It's also me in dialogue with the one other private owner of a Fluence here in the UK I'm aware of. We get 100 miles range out of ours as a matter of routine. Well, in my case I've only done 300 miles in it in the week I've had it so far (so, not quite 'routine', perhaps). But my experience so far is consistent with the other guy who has put 2,000 miles on his.
Anyhow, I was wondering whether it comes down to the different motor technologies. The Leaf has a permanent magnet motor, and it'll have a design speed of around 3,000 rpm in the constant V/Hz region of operation. Above that, I presume it'll have to do some sort of field weakening scheme, which'll make it less efficient for fast, light load conditions. Usually, field weakening is done by injecting Q-axis current, which, in effect, opposes the magnetic fields of the PMs (in fact, in extremis, field weakening can begin to demagnetise PMs!).
The Renault ZE cars have Continental's coil rotor motors, which therefore don't need to perform any field weakening, and would therefore likely simply alter the field/phasing to pick [presumably] whatever V/Hz characteristic is demanded. I started out driving very cautiously so as to judge how much range I might get (I used the 'Leaf Range Chart' initially), but soon realised after covering nearly 30 miles on less than a quarter of indicated charge I was doing better than that chart. So I simply started picking the speed up and up. I now aim for 60~65 on the motorways, and aim to stay under ~15kW power up and down hills (I slow down to ~50 on the uphills I take, but would hit 80 on the downhills if I keep feeding in 15kW so I usually back off then). With that sort of driving, I get 4.7~5.2 M/kWh.
So, what do you guys think? Is field weakening sucking up some of the Leaf's range, or maybe we cruise more gently because we have less power at our toe-tips? Or is there some miscalculation of energy/distance afoot, or ... ?