Search found 683 matches

by Tritium_James
Fri, 24 Jun 2011, 17:01
Forum: Electric motors and controllers
Topic: My homebuilt VFD progress
Replies: 141
Views: 15293

My homebuilt VFD progress

Yes, we're using a standard A/B quadrature encoder. Of course you need quadrature otherwise the controller has no idea about direction. The only reason you would need a high count encoder is for accurate position feedback. Since this is entirely unnecessary in a traction application (heh: move my ca...
by Tritium_James
Fri, 24 Jun 2011, 14:07
Forum: Electric motors and controllers
Topic: My homebuilt VFD progress
Replies: 141
Views: 15293

My homebuilt VFD progress

Don't forget you get the 4x resolution multiplication with period timing too, so at 60rpm we are updating at 5ms intervals. :) Also don't forget that for induction motor control you only care about speed, not position. And the slip speed (what you're trying to control) is an absolute value, not rati...
by Tritium_James
Thu, 23 Jun 2011, 22:56
Forum: Electric motors and controllers
Topic: My homebuilt VFD progress
Replies: 141
Views: 15293

My homebuilt VFD progress

The issue is actually 'dumb' controllers counting pulses, rather than timing the period between edges with a fast clock. Ours works just fine with a 48ppr encoder...
by Tritium_James
Sun, 19 Jun 2011, 17:33
Forum: Electric motors and controllers
Topic: Kelly Brushless Setup Problems
Replies: 11
Views: 2067

Kelly Brushless Setup Problems

The wire gauge shouldn't be a problem. From the video, it sounds to me like the hall sensors aren't lined up with the phases properly - this is why it is different in forwards vs reverse. Is it possible to adjust the alignment of the hall sensors? eg are they on a slotted PCB that can be rotated rad...
by Tritium_James
Sun, 19 Jun 2011, 03:32
Forum: Technical and conversion discussion
Topic: Convert 1975 Afron Cherrypicker?
Replies: 143
Views: 21255

Convert 1975 Afron Cherrypicker?

Does the motor have position sensors (possibly halls?) or is it running sensorless?
by Tritium_James
Thu, 16 Jun 2011, 20:54
Forum: Electric motors and controllers
Topic: RX400H transaxle
Replies: 169
Views: 22712

RX400H transaxle

Our controller can run at full load at 450V, no problems. We have better power stage layout than most industrial drives, and lower inductance bus caps = less overshoot on switching edges. The main reason we specify 450V max instead of even higher is because we need enough time to react and shut thin...
by Tritium_James
Wed, 01 Jun 2011, 21:32
Forum: Technical and conversion discussion
Topic: AC vs`DC debate
Replies: 25
Views: 4131

AC vs`DC debate

Thanks for the plug Richo!

Coulomb, the mods are removing the shaft fan, machining down the shaft to suit the encoder, balancing for >6000rpm, adding an encoder, adding a 12V fan.
by Tritium_James
Wed, 01 Jun 2011, 17:58
Forum: Technical and conversion discussion
Topic: AC vs`DC debate
Replies: 25
Views: 4131

AC vs`DC debate

We've done a fair amount of testing with our controller driving a slightly modified 132-frame SEW Eurodrive copper-rotor induction motor that we're getting 70-75kW out of at the shaft. It's about 60kg, and a little over 90% efficient in cruise.
by Tritium_James
Tue, 31 May 2011, 13:09
Forum: Technical and conversion discussion
Topic: Convert 1975 Afron Cherrypicker?
Replies: 143
Views: 21255

Convert 1975 Afron Cherrypicker?

Can you turn the gearbox by 90° so that the motor shaft points straight up? You'd then be able to mount the motor directly to it with no universal joints.
by Tritium_James
Thu, 05 May 2011, 16:06
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 349077

Weber and Coulomb's MX-5

I can easily believe different bulbs (even of the same power rating) would have different startup characteristics. One could have more length of thicker wire (a better quality bulb with more vibration tolerance), giving the same resistance, but a completely different startup waveform.
by Tritium_James
Thu, 28 Apr 2011, 01:15
Forum: Members Machines
Topic: seligtype3 1969 Volkswagen Type 3
Replies: 194
Views: 41994

seligtype3 1969 Volkswagen Type 3

I'd just use a lab power supply. Warning: for 160Ah cells it's going to be s..l..o..w... most lab supplies can only put out 2 or 3A.
by Tritium_James
Wed, 27 Apr 2011, 14:01
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

Weber, there was a couple of 1200V 10A IGBTs in there in a half bridge configuration, to switch the resistor either high or low. There's nothing to stop you putting the 2nd contactor in the negative side of the pack (and it's how we have it drawn in our documentation for the BMS, not up on the websi...
by Tritium_James
Wed, 27 Apr 2011, 02:55
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

That's some interesting hard data - thanks! I'm not surprised it's over a kA for the Wavesculptor, the caps in it are very low impedance. Don't try the same experiment at a higher voltage though! The inductance of your cabling, batteries, etc, will cause some fairly high voltage overshoot on the cap...
by Tritium_James
Tue, 26 Apr 2011, 21:40
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

Yeah, it's a bit of a nightmare trying to work out all the interacting factors. But the '50' figure at the worst-case is quite scary, so there's a big incentive to keeping away from whatever causes that. Allowing 4 or even 5 Tau for precharge time is much safer... weber, it's in the datasheet too! ....
by Tritium_James
Tue, 26 Apr 2011, 20:44
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

Oh, and your themal cutout will probably just arc over and die if it opens with a few amps at 400V DC across it... don't count on it doing what you expect it to do with DC through it.
by Tritium_James
Tue, 26 Apr 2011, 20:40
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

The correct solution to precharge is to NOT use a fixed time, it should be under control of a micro which monitors the voltage on both sides of the precharge resistor, and cuts in the contactor when they're within 10% of each other. It should also be keeping track of either time, or resistor tempera...
by Tritium_James
Tue, 26 Apr 2011, 16:28
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

I don't think the capacitors in the input to the DC/DC will cause too much of a problem for the contactors, they're going to be several orders of magnitude less capacitance compared to a motor controller (well, not ours...) We get away with having the DC/DC on the controller side of the contactors i...
by Tritium_James
Mon, 25 Apr 2011, 20:06
Forum: Technical and conversion discussion
Topic: Pre Charge Resistor
Replies: 30
Views: 5239

Pre Charge Resistor

Like coulomb said, you'll need to know the controller capacitance to work out the precharge value. Your contactors should have a datasheet that describes the effect of closing them without precharging. The relevant numbers for the EV200 type HV vacuum contactors are something like 80% precharge = 50...
by Tritium_James
Mon, 25 Apr 2011, 00:41
Forum: Electric motors and controllers
Topic: ADC/Curtis-reduced torque at start up?
Replies: 21
Views: 4937

ADC/Curtis-reduced torque at start up?

No electrolytics that will fit in that size box will be rated any higher, so the best you'll be able to do is get it back to new again, but it will then wear out just as fast. I think the reason there's no people offering upgrades is that the controllers are potted in place - isn't it basically impo...
by Tritium_James
Sun, 24 Apr 2011, 23:53
Forum: Electric motors and controllers
Topic: ADC/Curtis-reduced torque at start up?
Replies: 21
Views: 4937

ADC/Curtis-reduced torque at start up?

It's plausible. The caps in the Curtis aren't rated for anywhere near 500A ripple, so they heat up and wear out. I think they're something like 220u/200V, so probably about 2.5A ripple per part. Something like 30 of them in there? so they're rated for 75A ripple in total. If they're good caps this w...
by Tritium_James
Tue, 19 Apr 2011, 16:19
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 349077

Weber and Coulomb's MX-5

I don't think your extra fuses will help much, especially if you have already designed the pack with the high clearance distances. This is because an arc, and even more so for a long arc, has a reasonably high resistance, probably on the order of a few ohms. So across your 450V pack, the arc is diss...
by Tritium_James
Mon, 18 Apr 2011, 19:07
Forum: Electric motors and controllers
Topic: DYNO RESULTS: Induction motor power curve
Replies: 12
Views: 6594

DYNO RESULTS: Induction motor power curve

There is no way you should have to add external inductors to an induction motor. They're very high inductance. Adding extra will just cause problems with power factor and limit the power you can put through the motor at high speed. What's wrong with the current and voltage waveforms in the photos? I...
by Tritium_James
Sat, 16 Apr 2011, 23:04
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 349077

Weber and Coulomb's MX-5

That is the distance between tracks, on the same layer. Don't forget your 3kV/mm figure for air. The only reason PCB is worse is because of surface contamination, which is the reason conformal/soldermask covered tracks are rated higher than bare ones. If you're looking at mains rated equipment, and ...
by Tritium_James
Sat, 16 Apr 2011, 21:35
Forum: Members Machines
Topic: Weber and Coulomb's MX-5
Replies: 1698
Views: 349077

Weber and Coulomb's MX-5

Completely over the top, guys. Per the IPC-2221 and IPC-2222 PCB layout guidelines, electrical clearance distances should exceed the following: - Internal conductors (inside multi-layer PCBs): 0.25mm for the first 500V, plus 0.0025mm/V above this - External conductors, conformal/soldermask coated: 0...
by Tritium_James
Sat, 16 Apr 2011, 16:24
Forum: Batteries, charging, management and monitoring
Topic: Charging 20 Thunderskys
Replies: 9
Views: 1307

Charging 20 Thunderskys

It also depends on when the cells were manufactured. The datasheet on the cells we put in the Civic 2-3 years ago says 4.25V top of charge, so that would be 85V for your 20 cells.