Gate Drive Transformer - Page 1
Forum section: electronics / projects

author: IanBerry
author_rank: Contributor
timestamp: November 07, 2017, 06:46:55 pm
content: I'm trying to build an SSTC and I was thinking of using gate drive transformers to drive my half-bridge MOSFETs (Both N-channel). I was wondering where I can buy some high-efficiency toroidal cores for winding the transformer. I'm also wondering if there are any tips or tricks in using gate drive transformers.

author: Benta
author_rank: Super Contributor
timestamp: November 07, 2017, 08:12:21 pm
content: http://www.abbreviations.com/SSTCUnclear abbreviations are for marketing dorks who want to sound smart. Like saying "puffs" instead of picofarads. Don't do it.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 07, 2017, 08:16:12 pm
content: Well, within the coiling community, "SSTC" and various other TCs are well known.Domain specific knowledge, it happens.Anyway, not sure what you need by "high efficiency cores". There are plenty of tips and tricks using them, though. There are many references to search for; the Unitrode (now TI) power switching design articles are good. Middle-aged references (80s and 90s) are perfectly suitable here -- GDTs are less common these days (as there are ICs for some of the jobs), but were a necessity back then.As for off-the-shelf parts, there are a few, probably the best being VAC transformers (search at Mouser).Tim

author: CM800
author_rank: Frequent Contributor
timestamp: November 07, 2017, 08:16:47 pm
content: Quote from: Benta on November 07, 2017, 08:12:21 pmMost people just refer to it as an SSTC, just like you call an FPGA an FPGA, not a Field Programmable Gate Array.SSTC stands for Solid State Tesla Coil.

author: Benta
author_rank: Super Contributor
timestamp: November 07, 2017, 08:29:53 pm
content: Quote from: CM800 on November 07, 2017, 08:16:47 pmThanks. I worked SSTC out eventually. And FPGA is not an unclear abbreviation.But on the link I posted, "Super Secret Troll Club" gets four stars (for relevance) and "Solid State Tesla Coil" gets three. Talk about unclear - or rather, secterian.

author: tautech
author_rank: Super Contributor
timestamp: November 07, 2017, 08:37:49 pm
content: GDTWe've always called them pulse transformers.....search for that and you'll find plenty of hits.

author: cat87
author_rank: Regular Contributor
timestamp: November 08, 2017, 07:20:00 am
content: There are no "high efficiency cores" out there. You buy the appropriate core you need the you take care of the "high efficiency" part. I.e. you design it to have low leakage inductance, low inter-winding capacitance, etc.A very nice and helpful link might be this:http://imajeenyus.com/electronics/20141006_gdt_testing/index.shtmlIt and the links in the article covers almost every aspect you need to design a proper GDTNow, having recently gone through the process of designing a GDT myself, on thing to watch out for: the GDT can saturate due to the volt*seconds product. It's a pain and can't really be identified other than building an inductor saturation tester. Except from putting it in the actual circuit and blowing up your FETs / BJTsHave fun

author: T3sl4co1l
author_rank: Super Contributor
timestamp: November 08, 2017, 08:36:22 am
content: Quote from: cat87 on November 08, 2017, 07:20:00 amSaturation is easily calculated from the core parameters and winding. The core also heats proportionally* to flux density, so the practical limit is often well below saturation. Which gives a nice headroom for startup conditions, in case your oscillator does not have a soft start feature (i.e., the first pulse that fires is full width, consuming twice the peak flux of steady state).*Not actually proportional, but greater than proportional, closer to square-law. A proportional reduction in Bpk gives roughly a double reduction in core loss. Also check the core datasheet for loss curves (or if not the core, then the material it's made of).Leakage and capacitance are also easily calculated when you use a transmission line transformer type windup. This can be a twisted cable, single layer windings, bifilar, interleave, etc. Indeed, for a given application, you can calculate the maximum wire length and characteristic impedance, and from that determine how big of a core you need (or indeed if your application is possible at all).Tim

author: oldway
author_rank: Super Contributor
timestamp: November 08, 2017, 10:18:30 am
content: You could buy the gate driver transformers from PULSE ....https://www.power.pulseelectronics.com/transformers/gate-drive