Hemonster's ACIM conversion

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Hemonster's ACIM conversion

Post by Hemonster » Sun, 19 Apr 2009, 00:03

Hi all,

I'm starting my conversion and have choosen to go the ACIM route, looking forward to it.

Just wanted to know, has anybody given thought to a Mitsi RVR as a conversion? I was thinking the MPV characteristics with a flat deck at the back make it useful for placing batteries (esp green savers) - the spare tyre is on a rack at the back which makes even more space in the car.

It comes in 4WD which might make it great for dropping the gearbox and mating a 4 pole to the drive/tail shaft? Or will keep the gb with my 2 pole ACIM.

I've tried to dig up some info on the gearing, but all I can find is that final gear ratio is about 4.4 and top gear ratio is 0.7 (Car Folio). But I don't know if that is the ratio of the gb or effectively the diff? Would my 2 pole struggle with direct drive, output 48.8Nm and 2.9 breakdown? Original car weight is 1350kgs (1500kgs for turbo version). Not sure what the GVM is, does anybody here know?

Thanks in advance.

Hemonster

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Hemonster's ACIM conversion

Post by Hemonster » Mon, 20 Apr 2009, 19:04

Here is my what I'm planning to do:

1/
I managed to acquire a 2-pole 15kw Teco AC induction motor (near new) and a 15kw PDL VSD with vector drive all for not much more than ~NZD1200 all up. I thought the best way to learn is to jump into the deep end, so that's what I'm doing. The motor is rated at 3000rpm at synchronous speed, which I will attach to a gear box. The torque isn't as grunty a a 4-pole at lower revs, hence why I think a gearbox will be more suitable. Car will be rated to go at 100km/hr. Most cars do this at 3000rpm on 5th gear, so that's the speed target. I might also have to look into starting in star for higher torque, and switching to delta for higher speed - but I don't think I'll even need to do this as I'm retaining the gearbox.

The car/sedan/van/truck (currently considering the RVR) I'm looking for will be sized to what will fit the motor and controller. The unfortunate thing is that the motor I got was a cast iron one and it weighs a hefty 130kgs. An aluminium one would have been around 80-90kgs in the same frame size, 160M.

2/
The 15kw VFD is definitely underated for the motor, but probably enough for me to do some experiments on initially - it was after all only ~NZD$550 with shipping. I'll be looking for a 30kw VFD with 150% overating to 45kw, that should be plenty I'm sure. I don't think I'll be breaking any speed/acceleration records until I change the VFD.


3/
Due to cost of LiFePO4 and for my initial learning curve (I might kill some batteries by mistake), I'll use AGM SLAs as acmotor and a4x4kiwi have done. I plan to use 48-52 12V 20-25 AHr AGM cells, with a total pack weight in the vicinity of 300-350kgs. An extra 12V will be used for the accessory battery. Am considering greensavers at this stage - 54 cells + smart chargers comes to USD2004 including shipping to NZ. Not a bad price really ... unfortunately the smart chargers are required by greensaver to meet with their 1 year warranty. The good news is that there is no difference in shipping :)

4/
I plan to use 200A rated relays? that can handle 240V or higher? There will be one relay per 48V module.

5/
My battery protection circuit will be similar to acmotor's, utilising configurable zener shunts to set voltage limits and an equilisation shunt. The voltage limits will triger a warning line that is optically isolated back to the controller, and also a dash light so I can see when it happens.

I am also considering a voltage monitoring system per 48V block - not sure yet. Might have this as an optional placement using a 2-wire optically isolated comms line. The monitor will be a separate entity to the protection circuit so that it doesn't matter so much if it fails - but at least when something goes wrong in the battery, I might have a better chance at locating where the fault is. Either that or I have a latching LED circuit that recognises when a local warning line has been triggered - so that I can identify which 48V module is the culprit.

6/
Charging is going to be done per 48V module, utilising the gs battery charger (at this stage anyway). These are 48V 5A chargers that will be ganged up at the AC input side, so that each battery module has a dedicated charger.

When the ingnition is turned off, I'll have the breakup relays disconnecting the pack into 48V modules. As an added safety, I will disconnect the relays if the charger voltage is detected (probably DC side), so the traction pack will not be enablable when the charger is plugged in.

Each module will have a charging fuse and protection diodes (maybe? depends if it upsets the charger or not), ustilising the traction pack return as the common -ve rail for all 48V modules.

7/
Safety wise I plan to have two strings of 300Vdc each (about what mains voltage is in NZ), both connect up in series to create the HVDC bus. I'm not sure what to do with the middle point just yet, need advise here. Will also have a main fuse on the traction pack string and a couple of circuit breakers distributed in the engine well and near the driver ( a 3rd perhaps in the rear battery box) - the circuit breakers will cut power to the breakup relays, which are normally open. This signal will also go to the VSD for emergency shutdown. All circuit breaks are wired series with the ignition which energises the breakup relays. So all breakers must be online/active if the ignition is to work. An inertial switch will also be added in this string.

8/
There will be two DCDC converters that will go from each 300V string to 13.8V to charge the accessory pack. I plan to use off the shelf AC mains rated DCDC regulators for this - some of which are rated up to 250Vac or higher.

9/
I plan to use a RPM encoder so that the VFD can operated the in close loop flux vector (with optional flux capacitor for time travel Image). For this I will take off the existing plastic fan to attach the encoder directly to the shaft. I'll replace the fan with 120mm PC fans instead which will operate at all times the ignition enables the accessory line.


I welcome your thoughts, ideas and criticisms.

Hemonster

ps: some pictures of motor and controller to follow soon.

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Hemonster's ACIM conversion

Post by Hemonster » Mon, 20 Apr 2009, 19:36

Some photos of the project so far (still early days):
http://picasaweb.google.com/HemonDey/ACIMConversion#

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Post by coulomb » Tue, 21 Apr 2009, 02:39

Hemonster wrote: 1/
I managed to acquire a 2-pole 15kw Teco AC induction motor (near new) and a 15kw PDL VSD with vector drive all for not much more than ~NZD1200 all up. I thought the best way to learn is to jump into the deep end...
Well done! Quite heavy motor, and 380V delta (380V star would have been better, but these are much less common). The controller is too weak as you note, but will be plenty to practice on.
The motor is rated at 3000rpm at synchronous speed, which I will attach to a gear box.
It will likely run safely at about 4500 rpm, even though it isn't designed to run that fast.
The torque isn't as grunty a a 4-pole at lower revs, hence why I think a gearbox will be more suitable.
Good decision, especially with a weak controller initially.
Car will be rated to go at 100km/hr. Most cars do this at 3000rpm on 5th gear, so that's the speed target.
You'll likely go a little faster than this with a gearbox, depending on the dynamics of the vehicle.
I might also have to look into starting in star for higher torque, and switching to delta for higher speed - but I don't think I'll even need to do this as I'm retaining the gearbox.
Right; no need at all for star/delta with a gearbox.
The car/sedan/van/truck (currently considering the RVR) I'm looking for will be sized to what will fit the motor and controller.
Can you tell us a bit about the RVR? I don't think it's a model we see in Australia, at least by that name. What's the kerb weight? Is it a large 4WD?
The unfortunate thing is that the motor I got was a cast iron one and it weighs a hefty 130kgs. An aluminium one would have been around 80-90kgs in the same frame size, 160M.
ABB make aluminium motors at 15, 18.5, and even 22kW (high output) in one frame size down (132). So don't put this in a Mini.
The 15kw VFD is definitely underated for the motor, but probably enough for me to do some experiments on initially - it was after all only ~NZD$550 with shipping. I'll be looking for a 30kw VFD with 150% overating to 45kw, that should be plenty I'm sure. I don't think I'll be breaking any speed/acceleration records until I change the VFD.
The 15 kW rating of the motor is continuous; breakdown torque will be about 3.5-4 times that, so you likely won't be getting everything out of your motor with a 45 kW peak controller. It seems to be rated at 15 kW for either 380 V or 415 V, meaning it can handle the higher voltage and the higher current comfortably, so I'd say there is more reserve there too. So I'd consider a slightly higher peak controller power, say 50 kW or more, if you can afford it, and if you are interested in getting the most from your motor.
3/
Due to cost of LiFePO4 and for my initial learning curve (I might kill some batteries by mistake), I'll use AGM SLAs as acmotor and a4x4kiwi have done. I plan to use 48-52 12V 20-25 AHr AGM cells, with a total pack weight in the vicinity of 300-350kgs.
That's some 12 kWh nominal, but with lead, that will translate to a lot less than 12 kWh usable at EV discharge rates. So range won't be fantastic, but I agree it's a good starter pack, and more in keeping with the cost of the other components.
4/
I plan to use 200A rated relays? that can handle 240V or higher? There will be one relay per 48V module.
200A sounds good for the relays, but you could possibly get away with 100A. You'll need them to be DC rated at at least 60 VDC, and make sure they never have to break under load. Relays designed for 240 VAC may or may not be suitable.
ps: some pictures of motor and controller to follow soon.

Thanks; pictures are always appreciated.
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Post by coulomb » Tue, 21 Apr 2009, 03:15

Hemonster wrote: 5/
My battery protection circuit will be similar to acmotor's, utilising configurable zener shunts to set voltage limits and an equalisation shunt. The voltage limits will trigger a warning line that is optically isolated back to the controller, and also a dash light so I can see when it happens.
Acmotor is the pioneer here!
I am also considering a voltage monitoring system per 48V block - not sure yet.
We're also considering monitoring - basically, being able to read the voltage or temperature of any cell. That likely requires a microcontroller per BMS board, which I am not particularly in favour of. I'll actually consider a PWM-analogue solution with shift registers to implement a crude "addressing mechanism".
6/
Charging is going to be done per 48V module, utilising the gs battery charger (at this stage anyway). These are 48V 5A chargers that will be ganged up at the AC input side, so that each battery module has a dedicated charger.
That should work, though the inrush current of 13 chargers connecting at the same instant might be a bit fearsome, depending on their input circuit. They are only ~70W output, so even 13 of them, even if not "power factor corrected", should still be OK from a 10A outlet.

Edit: oops, factor of 4 out. Each charger is about 300 W output, so up to 500 VA input; even 11 of these would be over 5 kVA, more than a 15A outlet.

I don't see a problem with say 4 chargers on board, more at home where you have a 15 A or 20 A outlet, all in parallel, with all the 48 V nominal groups in parallel (when the contactors separate the groups, of course). The multi-pin connector does this automatically. The lower voltage 48 V groups will hog the current; the higher voltage groups will mark time while the others catch up. The devil is in the low-impedance detail, of course...
When the ignition is turned off, I'll have the breakup relays disconnecting the pack into 48V modules. As an added safety, I will disconnect the relays if the charger voltage is detected (probably DC side), so the traction pack will not be enablable when the charger is plugged in.
Yes, some form of interlock is essential.
Each module will have a charging fuse and protection diodes (maybe? depends if it upsets the charger or not), ustilising the traction pack return as the common -ve rail for all 48V modules.
I'm not so sure any more that this is the best way. I'm liking acmotor's multipin connector idea (but beware of voltage ratings), so each 48 V group can be essentially independent and floating. It probably depends most on what you do for leakage detection.
7/
Safety wise I plan to have two strings of 300Vdc each (about what mains voltage is in NZ), both connect up in series to create the HVDC bus. I'm not sure what to do with the middle point just yet, need advise here.
You may have noted some lengthy arguments on that topic a month or so ago. I think it starts about here: viewtopic.php?p=8745&t=618#p8745.
Weber and I are leaning towards fully floating, and I can't remember if the midpoint is used for the detection or not. Others seem to be adamant that connecting the centre point to chassis is a good idea.
8/
There will be two DCDC converters that will go from each 300V string to 13.8V to charge the accessory pack. I plan to use off the shelf AC mains rated DCDC regulators for this - some of which are rated up to 250Vac or higher.
Beware: 250 V x sqrt(2) ~= 350 VDC. If you have 13 12 V nominal batteries in series, that's 780 V at 15 V each (heavy regen or just after equalisation), or an average of 390 V. Even 265 VAC is only 375 V, so if that's the DC-DC's limit, you may have to do something (brake resistor? Controller limit parameter?) to limit the DC bus voltage.
9/
I plan to use a RPM encoder so that the VFD can operated the in close loop flux vector. For this I will take off the existing plastic fan to attach the encoder directly to the shaft. I'll replace the fan with 120mm PC fans instead which will operate at all times the ignition enables the accessory line.
Ok, or you could use a 10" thermatic fan or two, to save power when the motor isn't hot, and really cool it when it is.
Last edited by coulomb on Mon, 20 Apr 2009, 20:21, edited 1 time in total.
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Post by acmotor » Tue, 21 Apr 2009, 03:57

Hemonster,
Please throw your pics up on this forum so it shows a more complete record of your project. If you use outside links and they get broken then the record is lost for us on this forum.

Weber has covered most of the points Image
I can only add that both Mal(4x4kiwi) and I run DC-DC pairs up to 750 volts or so and so far they are fine. The main limit seems to be the input caps on the DC-DC at 400V ea. ( I have also removed the VDR out of the DC-DC input stage as this could have a problem with the higher voltage.) Image
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Post by weber » Tue, 21 Apr 2009, 16:33

acmotor wrote:Weber has covered most of the points Image

Hi acmotor,
I'm afraid you're confusing me with my electrostatic analog. It was probably the flux capacitor that did it. Image

Just so we're clear:
A coulomb (charge) is an amp second or a farad volt or a joule per volt.
A weber   (flux)   is a volt second or a henry amp or a joule per amp. Image

Hemonster,
You did an awesome job of summarising that huge thread on AC motors. Now here's another one for you (not quite so long) on "To chassis-earth or not to chassis-earth?".

As a relatively low cost learning experience I think your plan is a good one. But I have briefly driven an EV (a LiteAce van) limited to 15 kW and it was not a good experience. You can feel the annoyance of drivers behind you as a palpable radiation, particularly starting off from traffic lights or going up the merest slope. However this was a 4-pole motor with no gearbox, so you may be a little ahead.

However I suspect the weight and volume of the cast-iron motor will mean that your base vehicle will need to be fairly large and heavy, negating any advantage of keeping the gearbox.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

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Post by Hemonster » Wed, 22 Apr 2009, 02:07

Ok, some pics here ... though picasa just make it so much easier ... a one by one uploader really can be made better... IMHO :) It has been an intrepid journey ... Image

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Post by Hemonster » Wed, 22 Apr 2009, 02:33

coulomb wrote:
Can you tell us a bit about the RVR? I don't think it's a model we see in Australia, at least by that name. What's the kerb weight? Is it a large 4WD?
I imagine that you probably do have such a vehicle in Oz, here is a link for the one I'm potentially interested in.
http://www.trademe.co.nz/Trade-Me-Motor ... 892180.htm

It's the turbo version, and its sort of a hybrid car/van with the back seats seated on sliders and a flat deck (like a van). I wanted to mount the batteries in the centre to rear of the vehicle so its nicely balanced, but may have to cut into the floor to do this - some issues may arise come inspection though.

From what imformation I can acquire so far, it's got a GVM of about 1750kgs and weighs in at 1500kgs. There is a non-turbo version that has a GVM of 1500kgs and 1350kgs kerb. The turbo one may be heavier because the turbo engine may need more metal in it? If that is the case I may be ok for weight - whatever it is, I'm going to find it difficult to hide 360kgs of GS batteries. My calcs place me at:

Motor: 150kgs (with flange fitted)
Controller: 40kgs (for the higher performance one, the one I have now is 30kgs)
Batteries: 360kgs
Misc: 50kgs
----
Total main parts: 600kgs (ouch!)

Estimated engine weight: 200 kgs (optimistic)
Estimated other weights: 80 kgs (optimistic?)

Total parts removed: 280 kgs
Net gain to vehicle: 320 kgs

Neither of the RVR types have a GVM to kerb difference in that region. So I don't think this is a suitable vehicle to convert unless I:
- change to a 4-pole and direct drive the drive/tail shaft only, throw the engine and gearbox out as you clever folks have done
- get a much lighter motor
- get lighter batteries! (even EVPST 12AHr cells are too dear at NZD$10K for 220 cells at the moment, :( --- oh why can't these be cheaper!), this really is the crux of the weight issue.

I think ideally I need something like a 7 seater and remove two seats - a chariot for instance has a GVM-kerb of 500kgs, this should be ample for 4 people and the conversion as long as I get a lighter motor.
coulomb wrote:
That's some 12 kWh nominal, but with lead, that will translate to a lot less than 12 kWh usable at EV discharge rates. So range won't be fantastic, but I agree it's a good starter pack, and more in keeping with the cost of the other components.
Actually after peukert corrections, its more like 12AHr cells at 7-8kw average power requirements to push a 1500 kgs vehicle at 50-60km/hr. So at 80% DOD I'm looking at really only a 5.8kwh pack, which really is quite measly - even for one of the better rated AGMs out there. There certainly are huge advantages to getting LiFePO4 cells.


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Post by Hemonster » Wed, 22 Apr 2009, 02:43

coulomb wrote:
I'll actually consider a PWM-analogue solution with shift registers to implement a crude "addressing mechanism".
Hmm ... interesting, can you expand on this idea for my clarity, or point me to the thread?
coulomb wrote:
Edit: oops, factor of 4 out. Each charger is about 300 W output, so up to 500 VA input; even 11 of these would be over 5 kVA, more than a 15A outlet.


Can I ask how you arrive to 500VA?
coulomb wrote:
I'm not so sure any more that this is the best way. I'm liking acmotor's multipin connector idea (but beware of voltage ratings), so each 48 V group can be essentially independent and floating. It probably depends most on what you do for leakage detection.


It certainly reduces wiring :) But yes I do see your point about floating each 48V module, fewer paths for runaway electrons to take.

Another thing I thought was using a DPDT (or DPST) for each of the charger's two terminals, the coils get energised by the charger voltage itself (via some voltage reduction). These only need to be 60V 8-10A rated and should be relatively cheap?


QUOTE=coulomb]
Beware: 250 V x sqrt(2) ~= 350 VDC. If you have 13 12 V nominal batteries in
series, that's 780 V at 15 V each (heavy regen or just after equalisation), or an average of 390 V. Even 265 VAC is only 375 V, so if that's the DC-DC's limit, you may have to do something (brake resistor? Controller limit parameter?) to limit the DC bus voltage.
[/quote]

I think you mean 26x 12V nominal cells in series?


coulomb wrote:
Ok, or you could use a 10" thermatic fan or two, to save power when the motor isn't hot, and really cool it when it is.


Is a thermatic fan a thermally activated fan?




[/quote]

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Post by Hemonster » Wed, 22 Apr 2009, 02:45

acmotor wrote: ( I have also removed the VDR out of the DC-DC input stage as this could have a problem with the higher voltage.) Image


What is a VDR?


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Post by Hemonster » Wed, 22 Apr 2009, 02:53

weber wrote:
Hemonster,
You did an awesome job of summarising that huge thread on AC motors. Now here's another one for you (not quite so long) on "To chassis-earth or not to chassis-earth?".


You've now committed me to more reading ... Image, oh well I had to do it anyway, will be reading it soon then.
weber wrote:
As a relatively low cost learning experience I think your plan is a good one. But I have briefly driven an EV (a LiteAce van) limited to 15 kW and it was not a good experience. You can feel the annoyance of drivers behind you as a palpable radiation, particularly starting off from traffic lights or going up the merest slope. However this was a 4-pole motor with no gearbox, so you may be a little ahead.


Understood. The controller I have in variable torque mode can take up to 46A for 60s maximum, 600V bus is 27.6kw - but even this I think will still be very sluggish for direct drive, perhaps ok with gearbox. Weight is the key issue with acceleration, and I have real weight issues ... my conversion needs an atkins diet Image




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Post by weber » Wed, 22 Apr 2009, 03:24

Hemonster wrote:What is a VDR?

Voltage Dependent Resistor, more often known as a MOV or Metal Oxide Varistor.
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Post by woody » Wed, 22 Apr 2009, 03:47

for reference, the 1200cc, 800kg cortina ICE is 90Nm / 36kW, it is OK in traffic, but only sounds fast because of the noise 0-100 in 26s. A 1600kg bus will be more leisurely.
Your Motor should be ~150Nm peak, probably close to original, but you'll hit your 15kW mark at around 1000 rpm, 26 at 1600, so a flat power curve from 1600 to 4000. Gear change to keep inside that range.
The cheapest lithium I've seen is Optimum (see other thread) which squeak in under AU$5k for 224 x 8 Ah cells and will do 75kW according to specs.

For a vehicle, can you get something like a datsun 1200 ute - lots of load capacity but not much weight?

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Post by coulomb » Wed, 22 Apr 2009, 04:30

Hemonster wrote: Can I ask how you arrive to 500VA?
Yes, you can.

Oh, more? Image

48 V nominal battery, charges to 58.something, call it 60 V. Five amps times 60 V is 300 W. About 80% efficient at full load, so that's 300/0.8 ~= 375 W going in. It probably won't be "power factor corrected", so the input current waveform will be far from a sine wave, call it an effective power factor of 0.75. So 375W / 0.75 = 500 VA.

I'm a bit hazy as to why the current rating goes up due to the shape of the current waveform; I guess the breaker might respond to average current, whereas power comes from RMS current. Feel free to shoot me down here, guys, or at least educate me. I realise it's not actually power factor, since the current is about in phase with the voltage (there is a spike of current every peak of the voltage waveform).

So that 500VA calculation is really rough, and as has been pointed out, it probably won't supply maximum current for too long... but it might.

Have a look at the specs for some cheap chargers; you may be surprised at how much current they are rated at drawing from the mains.
Another thing I thought was using a DPDT (or DPST) for each of the charger's two terminals, the coils get energised by the charger voltage itself (via some voltage reduction). These only need to be 60V 8-10A rated and should be relatively cheap?
Err, not if I understand you correctly. If the other end of the relay has pack voltage, then although it won't have to break pack voltage, it will have to withstand pack voltage while the vehicle is running, and not flash over.
I think you mean 26x 12V nominal cells in series?
Yeah, another factor of 4 again, I think. Hopefully you get the idea: you'll probably get away with it, but it's pretty close with 13 groups of 48 V.
Is a thermatic fan a thermally activated fan?
Yes, that's what I meant.
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Post by woody » Wed, 22 Apr 2009, 04:37

OK, hemonster, I plugged your motor and a lenze 9327 (16kW drive with 50% boost) into my spreadsheet with Mal's Hilux as a base (1520kg).
0-60kph in 18s using the gearbox is way better than 26 seconds direct drive.

400m in 29 seconds (Gearbox) 35 (direct drive)

A 15kW controller can probably only give 48A which is only 98Nm with your motor.

Scratch what I said about the flat power curve, you don't get to 26kW with this motor.

A bigger controller will get direct drive close (1-2 secs) to the gearbox times, but not improve the gearbox times.

In a light car (Cortina) with lithium (920kg) all up, 0-60 in 12 seconds (direct drive), 8 seconds (gearbox) is looking better for the not so patient.

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Hemonster's ACIM conversion

Post by acmotor » Wed, 22 Apr 2009, 04:55

The store of energy and the cutting force. Makes sense ! Image

Yep, a MOV is a type of VDR that clamps voltage spikes.
The one on my DC-DCs was spec'd to clamp at 275VAC (380VDC).
If these devices turn on then they don't let go until voltage drops well down. Bad news on DC ! Fine on AC. I considered it tempting fate to leave it in.

Hemonster, I would not underestimate the 0-40kmph acceleration of your proposed setup. I would predict it to be quite satisfactory. It will be the higher speeds where performance will fall short. By then you will have the EV bug and a good stepping stone.

Keep the weight under control though. Image

Hey, thermally cued air mass flow turbine if you don't mind ! Image

Re DC-DC (SMPS) power factor.
It's all about the harmonics of the load i.e. not simple 50Hz sine wave. There is power in the odd harmonics 1,3,5 etc and these are seen by the circuit breaker or fuse as more than the basic kW. A good SMPS input circuit can improve (reduce) the harmonics and improve power factor (closer to 1) so VA is closer to Watts. Input inductors in the SMPS being the simplest (passive) way.
Sorry, that probably makes it less clear ! Image
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Hemonster's ACIM conversion

Post by weber » Wed, 22 Apr 2009, 17:04

acmotor wrote: The store of energy and the cutting force. Makes sense ! Image
Very clever. Actually the relationship between coulomb and weber is fairly symmetrical. Image For a capacitor, voltage is force-like (called electro-motive force EMF) and stored energy is volts times coulombs. For an inductor, current is force-like (called magneto-motive force MMF) and stored energy is amps times webers.

[Edit: Tried to make it clearer that I was playing along with acmotor's double meaning. Sigh.]
Last edited by weber on Wed, 22 Apr 2009, 18:13, edited 1 time in total.
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Hemonster's ACIM conversion

Post by acmotor » Wed, 22 Apr 2009, 18:22

Image I was summing up the MX5 duo !

The symmetry is in the electrons. However the magnetism remains unexplained, like gravity. We have formulas that's all.
As I ask people, what is the speed of a gravity wave ? Think carefully now.   Image
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Hemonster's ACIM conversion

Post by coulomb » Wed, 22 Apr 2009, 19:00

Hemonster wrote: [coulomb] I'll actually consider a PWM-analogue solution with shift registers to implement a crude "addressing mechanism".

Hmm ... interesting, can you expand on this idea for my clarity, or point me to the thread?
Not yet. It's still all in my head. But I have some basic ideas which I'll post in the homemade BMS thread.
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Post by Hemonster » Wed, 22 Apr 2009, 19:57

Do you mean like a VCO that transmits at a different freq for each 48V module unto a single wire bus? ie. Each 48V module transmits using a different carrier frequency - using tuned LC filters on the receive side you can then decode what each of the modules is saying, even if they are all transmitting simultaneously?


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Post by coulomb » Wed, 22 Apr 2009, 20:44

Intriguing idea. But no, per Weber's idea started about here:

viewtopic.php?t=900&p=11259#p11259
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Hemonster's ACIM conversion

Post by Nutz » Thu, 23 Apr 2009, 03:42

Hi there I found a couple of similar vehicles on EV Album
http://www.evalbum.com/1949
http://www.evalbum.com/1864
http://www.evalbum.com/1166
The eagle summit is a strange creature, not quite RVR not Quite Chariot(Nimbus in AUS. Spacewagon some countries)
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Hemonster's ACIM conversion

Post by Hemonster » Fri, 24 Apr 2009, 15:58

Hi Nuts,

Thanks for the links, these do indeed appear to be the same cars ... but as I suspected they are HEAVY beasts! averaging >1700kgs and losing the back seats ... :( not really my style - I've got kids after all and I want us to enjoy the car as a family.

I have since found that the Mitsi Chariot is likely a better candidate if considering AGM SLAs. This is because kerb to GVM difference is 670kgs, compared to the RVR which is 520kgs (comparing 1999 space runner/wagon equivalant UK models in the workshop manual). That's a whopping extra 150kgs it can carry, but it is a bigger vehicle and weighs in at 1500kgs (instead of the 1300 kgs the space runner weighs, non-turbo).

Being a 7 seater, you just have to remove the back seats and now you have a large station wagon, with a flat deck at the back ... the way I wanted to do it was to cut holes in the floor and sink the battery box in, externally vent it, which means it is not considered "inside" the passenger compartment (higher holding force required for certification). However cutting into the floor of the vehicle needs to be done carefully and with full blessing of the certifier - so it may complicate things. Here is an example of this car.

I'm starting to lean towards EVPST 12AHr cells like Woody, it will cost the bulk of my conversion budget, and then some :( But I think it is the better choice because I am then much more free to choose what vehicle I want using a cheaper/heavier motor and controller and not be too fussed. This is provided the cells don't die prematurely - that would be baaad! Optimum is cheaper but C discharge rating/AHr is less also, though only slightly. Their 10AHr cyclindrical comes close, but doesn't have nice and easy bolt on screw terminals. :(

Woody (or anybody), did you get some of these EVPST cells for testing?

Has anybody tried the BMI cells?




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Hemonster's ACIM conversion

Post by Hemonster » Fri, 24 Apr 2009, 18:08

Hi Coulomb,

Thanks for the reply.
coulomb wrote:
Another thing I thought was using a DPDT (or DPST) for each of the charger's two terminals, the coils get energised by the charger voltage itself (via some voltage reduction). These only need to be 60V 8-10A rated and should be relatively cheap?
Err, not if I understand you correctly. If the other end of the relay has pack voltage, then although it won't have to break pack voltage, it will have to withstand pack voltage while the vehicle is running, and not flash over.
I'm not sure I understand. As the suggested charger relay terminals will go across each 48V battery module terminals, why does it need to be rated for the entire pack voltage? Would not an 60-80V rated relay do the job? I was thinking these would be cheaper because their current rating can be much lower, say 5A DC.


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