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All in one advanced Inverter driver (in the planning stage)

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Danielle

Sun Sept 23 2007, 02:06AM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

well I will soon start a new form for my project as soon as I have some things together but I am working probably all this year to finish and buy the PCB of a advanced control curcite and driver including all the protections possible
1) under voltage detection for main VCC un reg and UCC 15V regulated power,
2)over current detection
3)over temp
4) gate drive isolated power check
5) I have a question on the last I was thinking of having a max duty cycle detection so it my interrupter failles or I turn a pot too high I can stop the signal from getting to the IGBT's before the current limiter can catch it. would that work? or is the current limiter enough and would this not work with audio modulation?

6) also this securitie will include pre-synchronization of the signal
7) transient voltage protection on the reg voltage
8) built in oscillator and interrupter for testing
9) status and error indication for all fault types
10) an analog/digital current meter.
11) this will have an auto tunning PLL (actually Steve Connor's PLL and logic)
12) current feed back tuning and phasing
13)18A gate driver to isolated IGBT brick driver (lots of amps+)
14) digital fiber optic interupter

also a question is that can I build the isolated brick IGBT drivers with the other parts and just keep the leads short to the IGBTs, or do I need to mount the driver on the IGBTs/ really near them? I plan to make this a really nice universal PSU driver. If others would want to help I would appreciate it, once I finish the schematic ill post it for review and I am asking for suggestions for more protections now, I am thinking other people would be interested in this, it will be very useful for anyone.

Also witch brick driver would you recommend Steve Connor's or Steve Ward's IGBT brick driver

uzzors2k

Mon Sept 24 2007, 02:57PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

Sounds like a good idea. You might want to call it an "inverter" instead of PSU driver, since the latter implies power supplies, and a universal PSU driver isn't too useful.

I get the impression that it is meant as a generic DRSSTC driver though, is that right?

I have something similar, although far from as advanced. It's a little TL494 based half-bridge driver, with over current detection and variable duty cycle. I'm going to add over temp shutdown, frequency control and maybe a current monitor later on.

Point 5 is somewhat unclear. Max duty cycle is ok, the overcurrent shutdown/limit will take care of that. Audio modulation however requires a CW to be modulated into music, so current limiting and modulation are two functions which cannot be used at the same time. The SSTC has to be able to run CW if it is to be modulated. Remember that DRSSTCs can't be audio modulated, at least not conventionally. Steve Ward did a midi DRSSTC IIRC.

Otherwise it sounds totally awesome, and I can't wait to see it done. It would be nice to just have the "real" Tesla coil to worry about, and not the driver, etc.

Danielle

Mon Sept 24 2007, 03:55PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

I have modulated a DRSSTC by converting the signe wave into a squair wave and then regulating the pulse with with a 555. Yes this is desighned to be a DRSSTC driver but I was thinking the max pulse with controll would be used to prevent the IGBT from switching a large pulse and halting it before the CT over current detection. This is not intended for CW operation I was planning a max of 10% dutycycle.

Danielle

Thu Sept 27 2007, 07:33AM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

well here is what I have so far I have been editing and compiling everyones designs to make one great driver. I would love feedback on what to keep and what to leave out. I will then start on the PCB.

1190878398 632 FT31758 Gate Driverinternal Interupter

1190878398 632 FT31758 Internal Oscilator

1190878398 632 FT31758 Over Current Detection

Steve Conner

Thu Sept 27 2007, 08:58AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Just one thing: If you're using my PLL driver, you don't need to add an oscillator to it. It works as a plain VCO (voltage controlled oscillator) in the absence of any feedback.

If you want to run CW with no feedback, you just need to disable the self-tuning feature, say by opening R34, or whatever. For short bursts, you may get away with just turning the loop gain pot to maximum resistance.

That was one other reason I chose to use a PLL. It makes it easier to debug than the self-oscillating type of circuit, where if any one link in the chain is missing, it won't oscillate, and it may not be obvious why. The PLL will generate gate drive at roughly the right frequency no matter what. When used with my matching gate drive booster cards, you can self-test everything before applying DC bus voltage.

About your point 5, I always wondered whether to use maximum duty cycle detection. What if the maximum duty cycle detection circuit fails?

Danielle

Thu Sept 27 2007, 09:29AM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

about failing max duty cycle I have the over current detection the over dutycycle is to prevent the IGBTs from switching before the CT can catch it.

after what you said and because I dont intend to run anything but a light pipe to my interrupter I may have to teak the design. Thanks for the point on the VOC that will help. I just didnt want to make a too complex gate driver I thought steves was enough, but I will add an opto isolator to send a power ok signal so that if drive power fails it will shut down before the gate goes high.

so to make sure I have it right I will remove the oscillator and make ways to remotely disable the PLL. I may want to keep it for use as a general purpose inverter driver like for a flyback, it wont only be used for my new +10KW coil project.

thanks for the help,

Daniel.

Danielle

Tue Oct 02 2007, 07:36PM

Registered Member #632 Joined: Mon Apr 09 2007, 01:09AM
Location:
Posts: 267

I have been working on this for a while and have decided to make these changes:

1) no PLL
2) most errors will be compared and taken control of by new PWM
3)PWM is UCC2895N PDF:

This should allow a much better control for duty cycle, current limit, SS, disable, and many other over and under volt protections.

One new question I have is (1): should/can I use the SS/disable pin for and interrupter control, or if I caint do that can/should I synchronize the feedback and interrupter before or after the UCC PWM? and question (2): can/should I use the phase shift and delay features for a DRSSTC would it be advantageous? and (3) should I use the duty cycle controls?

I have already built an isolated regulated SPSU with 500W max (1) +5V (2) +15V (4) +30V,-10V for all gate driver and low volt control, ill post schematics later.

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