Search found 683 matches

by Tritium_James
Sun, 02 Jan 2011, 19:07
Forum: Electric motors and controllers
Topic: AC drive programming and pedal mapping
Replies: 67
Views: 14542

AC drive programming and pedal mapping

Weber, I reckon that mapping would be quite nice. It gives a similar effect to what the setup with an ACP system is, where the 'zero' point of the pedal moves along the range of travel as speed increases. This means no dead pedal travel when moving off from a stop, but regen controllable by the same...
by Tritium_James
Sun, 26 Dec 2010, 00:50
Forum: Electric motors and controllers
Topic: Jerky running AC motor
Replies: 9
Views: 1909

Jerky running AC motor

I this running sensorless? If so, can you fit an encoder or similar?
by Tritium_James
Fri, 24 Dec 2010, 15:22
Forum: The Lounge
Topic: Ignorance is Bliss / Speakers
Replies: 12
Views: 2577

Ignorance is Bliss / Speakers

The Loud Speaker Kit in Perth have some quite nice kits too, and you'll probably save a heap in freight compared to importing something that heavy from the US!   http://theloudspeakerkit.com/
by Tritium_James
Mon, 20 Dec 2010, 15:11
Forum: Technical and conversion discussion
Topic: BLDC motors and PF factor
Replies: 24
Views: 6891

BLDC motors and PF factor

That 'hybrid' motor looks to me like an IPM = Interior Permanent Magnet. Probably the best of both (induction vs PM) worlds at the moment, I think. Coulomb, regarding the Carbon motor in the Civic, yes, there is no overspeed region for that motor, you can't field weaken an ironless PM motor. Well no...
by Tritium_James
Tue, 14 Dec 2010, 22:27
Forum: Technical and conversion discussion
Topic: NSW certification
Replies: 2
Views: 879

NSW certification

There's a checklist at the back of the NCOP14 document, so maybe the RTA and your engineer are both kind of right?
by Tritium_James
Thu, 09 Dec 2010, 15:23
Forum: Technical and conversion discussion
Topic: BLDC motors and PF factor
Replies: 24
Views: 6891

BLDC motors and PF factor

Sorry Richo, PM motors don't necessarily have a pf of 1. They still have inductance, which limits the current slew rate, which means at higher motor frequencies you don't have time to ramp the current up to 100% before it's time to ramp it down to -100% for the other half of the cycle. Therefore, at...
by Tritium_James
Fri, 03 Dec 2010, 15:38
Forum: Batteries, charging, management and monitoring
Topic: Using an EV to power things.
Replies: 9
Views: 1704

Using an EV to power things.

The real thing you want is a bi-directional charger, that can take power from the mains to charge the pack, and also put it back the other way. But they're a bit of a rare beast at this point in time, though I'd expect them to become more common in the future.
by Tritium_James
Tue, 16 Nov 2010, 14:45
Forum: Members Machines
Topic: gholm's Morris J2 Van- 1966
Replies: 187
Views: 58115

gholm's Morris J2 Van- 1966

You'll want to be a bit careful about replacing indicators and brake lights with random LEDs - they won't be ADR compliant re brightness, emission angles, etc and the inspection people will fail you if they spot them. Having said that, a car this age probably had lousy lighting (lucas - prince of da...
by Tritium_James
Wed, 10 Nov 2010, 18:46
Forum: Members Machines
Topic: gholm's Morris J2 Van- 1966
Replies: 187
Views: 58115

gholm's Morris J2 Van- 1966

You should also allow room inside the battery box for your fuse (they are NOT small!) and your HV contactors. This way when 12V power is cut to the contactors there is no exposed HV outside the battery box. Have something in place to fasten these items to. Think about where your busbars and BMS on t...
by Tritium_James
Wed, 27 Oct 2010, 16:33
Forum: Technical and conversion discussion
Topic: regenerative brakes
Replies: 22
Views: 4000

regenerative brakes

EV2Go, I think you have the energy use thing backwards. If the vehicle had regen, travelling 50% uphill then 50% downhill would be the SAME power as if the car drove that distance on the flat, ie the amount consumed by aero/rolling/efficiency losses.    If you don't have regen, the up/down scenario ...
by Tritium_James
Sun, 24 Oct 2010, 21:30
Forum: Electric motors and controllers
Topic: Ways to reverse Series DC Motor -100% FWD 30% RVRS
Replies: 89
Views: 16139

Ways to reverse Series DC Motor -100% FWD 30% RVRS

I figure 250v - 600A forward and say 50V - 100A in reverse (it's only a trike) so I figured you would use lower rated contactors in reverse. Oh, OK. Yes, that's probably OK then. For a car, I think you'd want to design it for full torque in reverse too, otherwise you might get stuck in a parking sp...
by Tritium_James
Sun, 24 Oct 2010, 16:11
Forum: Electric motors and controllers
Topic: Ways to reverse Series DC Motor -100% FWD 30% RVRS
Replies: 89
Views: 16139

Ways to reverse Series DC Motor -100% FWD 30% RVRS

Maybe I'm confused here, but when you guys talk about 30% in reverse, don't you really mean 30% speed ? I think you're going to still need 100% current because otherwise you won't be able to reverse up hills, gutters, etc. So this would mean any contactors and other bits in the motor connections are...
by Tritium_James
Sat, 23 Oct 2010, 21:40
Forum: Electric motors and controllers
Topic: New AC controller now available
Replies: 46
Views: 10146

New AC controller now available

7circle, the WaveSculptor switches at 10kHz, with interleaved switching between phases, so the frequency 'seen' by the motor is 20kHz. It's above the audible hearing range (for humans, anyway...) so the issue you're talking about is non-existent with our controller. But yes, we probably could do tha...
by Tritium_James
Sat, 23 Oct 2010, 13:26
Forum: Electric motors and controllers
Topic: New AC controller now available
Replies: 46
Views: 10146

New AC controller now available

The leadtime on the bus caps is 16-20 weeks. This is normal, and not an exceptional circumstance, so we can plan around it. We order well in advance, and our next delivery is due in 2-3 weeks. So our quoted 8 week leadtimes for controllers are valid. Jack wanted a controller *tomorrow*, and seemed u...
by Tritium_James
Fri, 22 Oct 2010, 15:43
Forum: Electric motors and controllers
Topic: Controller Efficiency
Replies: 7
Views: 1476

Controller Efficiency

While Richo's numbers are a good start, they're only covering about half of the losses in the controller - the on resistance (or it's equivalent for an IGBT, the forward voltage drop Vf). The other major loss component in the controller is the switching losses. This is due to the fact that the MOSFE...
by Tritium_James
Sun, 03 Oct 2010, 01:52
Forum: Batteries, charging, management and monitoring
Topic: BMS Module Placement
Replies: 57
Views: 6486

BMS Module Placement

You still want the BMS in the trike while driving, ESPECIALLY if you're using Lithium Ion type cells that catch fire if you abuse them. The reason for this is that the undervoltage shutdown on your controller only shuts down if the total pack voltage goes too low. But this may be far too late for so...
by Tritium_James
Fri, 24 Sep 2010, 16:50
Forum: Electric motors and controllers
Topic: Direct to wheel motors
Replies: 67
Views: 14971

Direct to wheel motors

Coulomb, the thing you're missing is that there's multiple types of PM motors. Ironless types (eg Ultramotive's CARBON) can't do field weakening, and hence can't do overspeed. Motor types with iron in the rotor can do both - but have increased motor losses (iron hysteresis losses) as the tradeoff.
by Tritium_James
Thu, 23 Sep 2010, 18:04
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 402814

Weber and Coulomb's MX-5

The blue motor is mounted to a plate which then mounts to the dyno through a slewing bearing, and the plate is prevented from rotating by a loadcell. So we know torque. We also know motor speed exactly (both motors have position sensors) so power is simply torque x speed. As far as the mechanics of ...
by Tritium_James
Thu, 23 Sep 2010, 15:29
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 402814

Weber and Coulomb's MX-5

The dyno works by running the two motors against each other. One is driving, and one is regenning. There is a motor controller for each motor, and they have their DC links connected together, along with a battery pack and a power supply to top up any losses. This way we can circulate large powers ar...
by Tritium_James
Mon, 13 Sep 2010, 20:53
Forum: Technical and conversion discussion
Topic: Radios, EVs and bad electrical interferenc
Replies: 25
Views: 3974

Radios, EVs and bad electrical interferenc

At EMC frequencies (AM radio and up...) the inductance of the DC bus capacitors means they don't really act much like capacitors. So just about all the high frequency noise you'd see on the motor cables will also be conducted out along the DC battery connection too. Layout makes a massive difference...
by Tritium_James
Mon, 13 Sep 2010, 17:59
Forum: Technical and conversion discussion
Topic: Radios, EVs and bad electrical interferenc
Replies: 25
Views: 3974

Radios, EVs and bad electrical interferenc

Oh, it's not too hard if you're designing the entire car! But for us, trying to explain to random joe in his garage about EMC? I'd be spending the next six months on the phone, talking about why the 1mm gap in his battery box meant that his AM radio had hum in it.
by Tritium_James
Sun, 12 Sep 2010, 17:22
Forum: Technical and conversion discussion
Topic: Radios, EVs and bad electrical interferenc
Replies: 25
Views: 3974

Radios, EVs and bad electrical interferenc

No, we don't recommend shielding. Basically it complicates everything and isn't actually likely to do that much - one gap in it somewhere (like in the battery box) and it won't work properly. Any VFD (including DC motor controllers) generates so much noise at the switching frequency, at at such high...
by Tritium_James
Sat, 11 Sep 2010, 20:11
Forum: Technical and conversion discussion
Topic: Radios, EVs and bad electrical interferenc
Replies: 25
Views: 3974

Radios, EVs and bad electrical interferenc

The Wavesculptor200 is booked in in the next two weeks for final C-Tick EMC testing. We're not expecting any problems, the prototype passed with no trouble, and our Wavesculptor20 for solarcars, which has MUCH faster edge rates (and therefore more emissions) passes with ease. The test only covers th...
by Tritium_James
Wed, 08 Sep 2010, 23:27
Forum: Electric motors and controllers
Topic: AC motors, amping it up. :P
Replies: 58
Views: 10406

AC motors, amping it up. :P

The dV/dt issue is more of a problem on old modified square-wave drive inverters. Modern units operating at 10's of kHz PWM and with interleaved switching patterns have much less of it in the first place. The other thing that makes it a non-issue is that modern induction motors are designed to be dr...
by Tritium_James
Wed, 08 Sep 2010, 13:53
Forum: Batteries, charging, management and monitoring
Topic: BMS and 12V Circuit Load/Charging
Replies: 4
Views: 1224

BMS and 12V Circuit Load/Charging

Yes, it's quite a neat concept. You get an n-way redundant DC/DC converter, where 'n' is the number of cells in your main pack. You get a non-dissipative BMS. For hardly any extra effort you can make the DC/DC on each cell bidirectional, and can also charge weaker cells faster by pulling power from ...