Voltage question

[scrambled]

Just a question-

Why was there a dramatic decrease in the voltage between the VSD-A at 200 volts DC, and the VSD-E at 84 VDC?

I made the mistake of ordering my power supplies for 90 volts DC, since this is the max for my servo motors.

IS there any thing I can do, or should I just send the power supplies back? If I need to send then back, what voltage sould I change to 84 volts or 80?


Thanks


Steve

[keebler303]

Just a guess but I would say that most users were using less than 100 volts so the new drives use 100V rated parts, as they are cheaper and have better electrical characteristics. They have a safety factor built in to make them more durable so they are rated down around 80V. If you want to use the higher voltage, do what I am doing and wait until Tero releases the new high voltage version, which will be rated at 160V.

By the way Tero, how is this coming along? Seems there hasn't been much progress on this. Is it due to lack of demand? I have 14 Motors which are rated at or above 100V and I'm waiting to buy a couple. Can't buy 14 though, I'm poor!

Cheers
Matt

[Xerxes]

I'm working hard on 160V prototype to make it available in 2-3 months. Yesterday I accidently fried my 160V prototype so I have to modify a new one (from 80V version).

Steve, you could add few diodes (large ones) in series to PSU before capacitor to drop voltage by few volts. Each diode drops about 0.6-0.7V.

The real maximum usable voltage for VSD-E is ~90V, anything above that will trigger overvoltage shutdown. It is specified to 84V to have more safety margin.

[keebler303]

Thanks for the update.

You gotta tell us how you did it (fried your prototype).

Matt

[scrambled]

Tero-

I talked with the maker of the power supplies (Antek) and he is ok with me returning them for the correct voltage.

What is the max. voltage I can safely use? My servo motors are rated for 90 volts, that is why I was trying for that voltage.


If 84 is it, then that is fine, I want to make sure I don't void my warranty.



Steve

[Xerxes]

I would target it around 80VDC. If you add braking resistor to drive, it will start acting after 85V. At 80V you will not lose motor top speed much.

The prototype mosfet died when I was measuring output peak dV/dt with crappy gate drive circuit and simultaneously asked too way much current (current limits overriden from firmware which normal user can't do). Then I damaged it even more by trying to fix it while power was accidently left on