Search found 683 matches

by Tritium_James
Fri, 21 Dec 2012, 15:28
Forum: General EV Discussion
Topic: EV Conversion Research
Replies: 17
Views: 2563

EV Conversion Research

A decent rule of thumb regarding weight is: by the time you've taken out the petrol engine, exhaust, fuel tank, etc, and then put in your electric motor, electronics, cabling, fuses, empty battery boxes, etc, you'll be back at the original weight of the car. Then add the weight of your batteries. Ye...
by Tritium_James
Thu, 13 Dec 2012, 23:58
Forum: Technical and conversion discussion
Topic: Voltage help
Replies: 11
Views: 1746

Voltage help

If the motor is run from some kind of motor controller (eg it's a BLDC motor) then if the controller can deal with it , just run it from 36V. Save the inefficiency, cost and weight of the DC/DC. The thing that kills motors is either heat (too much current) or speed (too much voltage). But using a hi...
by Tritium_James
Wed, 12 Dec 2012, 22:04
Forum: Electric motors and controllers
Topic: Prius 3 MG2 Wye/Delta and controller
Replies: 17
Views: 5050

Prius 3 MG2 Wye/Delta and controller

Our controller can run an IPM motor just fine (in fact, mathematically provable to be near-optimal) but there's no way to set it up without dyno testing. The torque vs angle data from ORNL's dyno shows the optimal angle *at one speed only*. There is not enough data there to figure out the parameters...
by Tritium_James
Tue, 11 Dec 2012, 18:24
Forum: Electric motors and controllers
Topic: Prius 3 MG2 Wye/Delta and controller
Replies: 17
Views: 5050

Prius 3 MG2 Wye/Delta and controller

The waveform when spun as a generator only shows you the PM component of the motor. IPMs are a hybrid of PM and Switched Reluctance motors, and there's no way to characterise the SR component of the design without dyno testing, ie it's not possible to 'autotune' IPM motors.
by Tritium_James
Fri, 30 Nov 2012, 16:50
Forum: Technical and conversion discussion
Topic: Direct Drive: Do I have enough torque?
Replies: 61
Views: 7672

Direct Drive: Do I have enough torque?

Driving two wheels separately with two motors and two controllers is no problem. Run them both at the same motor current setpoint and you get a perfect diff action, it really is trivial. Coulomb, losing one motor in this case won't cause the car to go sideways on you during normal driving. eg: plent...
by Tritium_James
Sat, 17 Nov 2012, 13:51
Forum: Electric motors and controllers
Topic: 1.5kW Induction motor overclock
Replies: 17
Views: 3956

1.5kW Induction motor overclock

Probably not. Induction motors are rated on continuous power, and very conservatively too. They'll do that power 24/7 for 15-20 years, in 50°C ambient temps. They are absolutely guaranteed to do what it says on the nameplate. So there's lots of possibility to thrash them much harder (10x) for short ...
by Tritium_James
Fri, 16 Nov 2012, 13:50
Forum: Technical and conversion discussion
Topic: Siemens motors and rotary engined donors
Replies: 19
Views: 2876

Siemens motors and rotary engined donors

Coulomb, our client's EV Porsche from a few years ago ran an AC Propulsion drivetrain into the existing gearbox. That spun out to 12000rpm, and he had it fixed in *first* gear = about 120km/h top speed. He did about 50000km on it as far as I'm aware, including a lot of highway driving. I'm amazed it...
by Tritium_James
Tue, 30 Oct 2012, 19:07
Forum: Members Machines
Topic: Ian Hooper's RX7 Conversion
Replies: 102
Views: 23445

Ian Hooper's RX7 Conversion

It's difficult when it's a 600V DC rated fuse!
by Tritium_James
Mon, 27 Aug 2012, 15:33
Forum: Members Machines
Topic: barnard's Toyota MR2 - now Mr240
Replies: 213
Views: 26052

barnard's Toyota MR2 - now Mr240

Barney, I think I can see a problem - not sure if it's 'the' problem though... You appear to have the cable lug terminal *above* the BMS. This means your high currents are flowing through the BMS circuit board and the bolt, rather than directly from the battery terminal to the lug. The way you have ...
by Tritium_James
Thu, 23 Aug 2012, 21:01
Forum: Batteries, charging, management and monitoring
Topic: Split pack battery charging...
Replies: 148
Views: 17113

Split pack battery charging...

Not necessarily - why can't the motor controller, DC/DC, etc be powered up while you're charging? The DC/DC can keep the 12V battery full that way, making sure your BMS, charger controller, etc don't run it flat.
by Tritium_James
Thu, 23 Aug 2012, 17:43
Forum: Batteries, charging, management and monitoring
Topic: Split pack battery charging...
Replies: 148
Views: 17113

Split pack battery charging...

That's the Menekes euro charge plug, but it's for the AC side of things, not DC to your pack.
by Tritium_James
Mon, 20 Aug 2012, 15:46
Forum: EV Motoring
Topic: Tesla Model S Shown Publicly
Replies: 10
Views: 1876

Tesla Model S Shown Publicly

That's probably because they have an 'USA' school of thought on the charger where it draws large current (70-80A) on a single phase - quite normal there. Anywhere else on the planet would have moved to three-phase for that power load. So they will have trouble plugging it into random power points he...
by Tritium_James
Tue, 14 Aug 2012, 23:18
Forum: Electric motors and controllers
Topic: Getting the right windings...
Replies: 77
Views: 9668

Getting the right windings...

This affects the inductance of the motor, which will be much lower, which affects the switching frequency needed in the controller. Yes. But I think modern VFDs are up to the challenge. Tritium_James? Not really a concern. We drive ironless BLDC motors (which do require inductors to even achieve th...
by Tritium_James
Tue, 14 Aug 2012, 21:41
Forum: Members Machines
Topic: Ian Hooper's RX7 Conversion
Replies: 102
Views: 23445

Ian Hooper's RX7 Conversion

Might not need quite that, Woody - if you look at a plot for the series wound motors, the efficiency starts dropping pretty fast once you push them - at 1900A they're probably down to under 50%... I've never seen a manufacturer's curve go out this far, so this is from extrapolating the ones I can fi...
by Tritium_James
Wed, 18 Jul 2012, 14:36
Forum: Electric motors and controllers
Topic: Uploading Tritium Firmware
Replies: 15
Views: 2109

Uploading Tritium Firmware

Hey Ryan, good to see you got it mostly figured out! The hardware version is printed on the PCB.
by Tritium_James
Thu, 12 Jul 2012, 19:37
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

Yeah I think I replied without reading it properly - as Weber said, I had the reply exactly back-to-front re star/delta. You'd have a config for star, and a config for delta, and can switch with a simple CAN command, no problems. The only thing I don't know will work is switching configs with the mo...
by Tritium_James
Wed, 11 Jul 2012, 14:45
Forum: Members Machines
Topic: Richo's AC Handi Sports
Replies: 84
Views: 10581

Richo's AC Handi Sports

Nevilleh, don't forget your boost converter needs to be bidirectional, as you need to handle regen energy too. It's not completely trivial.
by Tritium_James
Fri, 06 Jul 2012, 15:31
Forum: Technical and conversion discussion
Topic: How to convert a hybrid
Replies: 132
Views: 23151

How to convert a hybrid

That looks identical to the original AC Propulsion motors.
by Tritium_James
Wed, 04 Jul 2012, 18:26
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

Which is exactly why we're buying off-the-shelf SEW motors with the lowest available winding voltage option :)
by Tritium_James
Wed, 27 Jun 2012, 19:15
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

Johny wrote: I meant place the Lenco near the diff and the motor in the transmission "hump" not the tunnel - sorry.


This also has the advantage that you get a potentially lighter driveshaft than the motor -> lenco -> driveshaft -> diff option, since the driveshaft is in the lower torque part of the system.
by Tritium_James
Fri, 15 Jun 2012, 15:54
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

T2, yeah you're right, my bad! Motor resistance is 1/4 in the lower voltage case. Losses in all the cabling are 16x higher though, but that's not such a big deal...
by Tritium_James
Wed, 13 Jun 2012, 22:34
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

PlanB, you don't get something for nothing by dropping the voltage :) Yes, switching losses are proportional to voltage, but they're also proportional to current! So designing your system for say 400V/100A the switching losses in the controller are going to be about the same as a system using 100V/4...
by Tritium_James
Wed, 13 Jun 2012, 14:09
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

About 1400kg.
by Tritium_James
Tue, 12 Jun 2012, 22:54
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

Not surprising it's sluggish with that torque. We've got 1750Nm at the wheels in the Civic (500Nm Ultramotive Carbon + 3.5:1 fixed reduction) and it's quite OK but nothing spectacular. A 'normal' car in 1st is probably more like 2500-3000Nm.
by Tritium_James
Tue, 12 Jun 2012, 18:59
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 21767

RX400H transaxle

Supplying variable voltage to the VFD allows you to reduce switching losses in the VFD since switching losses are approximately proportional to voltage. So if you don't need the full DC voltage available, because the motor is only going slow, then you cut your losses by only supplying the voltage ne...