HV Power Supply - Page 1
Forum section: electronics / beginners

author: lacosteaef
author_rank: Newbie
timestamp: April 26, 2012, 08:45:01 pm
content: Hello,I searched a bit on the forum and couldn't find anything relating to my question so I figure I would throw it out to the general audience.I'm a recent grad and i'm taking ownership of one of our HV power supplies at work. It's nothing overtly fancy, AC to DC (320V) with a regen circuit for our motors which is all mostly all orchestrated by a microcontroller.I'm wondering if anyone knows of any books/white papers regarding HV power supply design of this type? I'm looking to improve reliability by incorporating short circuit protection and doing some spice modeling to make sure everything is within limits.Thank you all for your help-J

author: amspire
author_rank: Super Contributor
timestamp: April 26, 2012, 09:22:59 pm
content: We would need more details about the supply to help, but it sounds like it might have a fair bit of available current. There may be some caution here in giving advice as working with 320v DC is extremely dangerous unless you really know what you are doing.320v AC is dangerous, but DC is worse if you do not understand that AC rated fuses and switches are useless. The safe way to work on such a circuit is to make sure any capacitors will be discharged when the power is off, set instruments up only when the supply is unplugged, and do not go near the live circuitry when the power is on.Richard.

author: lacosteaef
author_rank: Newbie
timestamp: April 26, 2012, 09:59:16 pm
content: Hey Richard,Yes there is lots of current in this power supply, I believe the IGBTs can do 60A. Basically the main function of this supply is to dump high current at high voltage either into a motor or out of the motor into a regen resistor.This is a very long term project and i'm just looking to beef up myself on power supply design outside of the normal process at work. I figured an easy way to do this is to review some texts that were written on the subject, be able to see current methods of design and protection. Some of the power supply design books on amazon look promising but I figured the people on this forum would know best which route to take. Maybe even save me some green by referencing free white papers.Thanks,J

author: amspire
author_rank: Super Contributor
timestamp: April 26, 2012, 10:18:57 pm
content: I do not know of any good books off hand, but if you can get your hand on circuits and service manuals for similar gear, it is like gold as you see real solutions. The simplified circuits in text books show the theory, but nothing beats a real working schematic.Back on safety, when I was working with DC power circuits, we had to work behind a safety screen or at least wear goggles. If one of those IGBTs fails, the explosion is spectacular. The shrapnel is dangerous.Richard.

author: lacosteaef
author_rank: Newbie
timestamp: April 27, 2012, 05:20:17 pm
content: I'll keep poking around then. Thanks for your feedback

author: codeboy2k
author_rank: Super Contributor
timestamp: April 28, 2012, 05:31:46 am
content: "The Electronics Power Supply And Battery Charger Circuit Encyclopedia"It has a chapter dedicated to high voltage power supplies, and as an encyclopedia it's full of example circuits that areuseful to look at, like Richard says. But I haven't looked at it, so I can't comment on it's usefulness to your situation.I just saw the index pages in a PDF and I am forwarding that information to you.As far as adding circuit protection, the best advice I can give you is Ohm's law still applies, it's only higher voltages, higher currents and higher power. Foldback current protection is the still done the same way, just make sure your devices can handle the voltage and current overloads you expect, then triple it for safety. If your common mode voltages are too high for some devices, you can float them above ground, just hang a zener off the high-voltage output to power any devices (like high-side current monitoring). You can opto-isolate that output to bring it down to your control loop input.