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Discussion Starter · #41 · (Edited)
Stunt Driver, I just have a few minutes right now, but in short I probably have about $300-$400 in parts invested in the controller, most of that being in the capacitor bank. (thats not including the bread board)

Yes I do plan on posting a systematic soon but it may be a week before I can get the chance to do so.

I have been following MPauls Holmes's progress but this is my design, mind you that power sections are all more or less the same when it comes to the basic circuit, but the component choices, hardware lay out and thermal design are what set them apart.

For the control section, I will eventually be using a micro controller, the same as MPauls Holmes, but I will be writing my own program for it aside from a few possible snippets, and the circuit will also be mostly my own but may borrow a few ideas form MPauls Holmes's project.

I should add here that I have a lot of respect for what MPauls Holmes has done with his project.

If you only want 400A then you should be fine with a half size of my power section, but you most certainly should add some sort of current limiting circuit; raw PWM circuits behave very differently from contactor setups. I am only able to get away with testing without a current limiting circuit, because my voltage is so low that I can not exceed my limit even withe the motor locked dead still. I do not dare go any higher with out a current limiting circuit; you mentioned not going over 250A at 48V with your motor, but I am I am already going much higher ( up to 400A ) at only 36V. Part of that could be differences in our motors, but also PWM circuits amplify current at lower PWM percentages.

Adding in here that the control section I am currently using to test the power section and car, is a very simple analog circuit, and is probably less than $10 in parts, Ill post the schematic hopefully some time this week.
 

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Would appreciate you to share schematics, and good luck testing and setting up!
In my current financial situation it only makes sence to go for cheap controller, probably within $200, so looking for options.
 

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In my current financial situation it only makes sence to go for cheap controller, probably within $200, so looking for options.
If that's all you have budgeted for a controller I hope your EV is a golf cart... Here's a rebuilt Curtis 1207 controller that just slides under your $200 budget:

http://www.golfcarcatalog.com/catalog/index.cfm?fuseaction=product&theParentId=1435&id=4352

Bow down before its awesome power of 24V and up to 300A!!!

EDIT: obviously I was being sarcastic here, but given that you have a functioning SCR-based controller that seems to satisfy you, you will NOT get better performance from a modern controller design if all you are willing to spend is $200, even if you build it yourself from scratch! So, I'd keep what you already have.
 

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I just can't step over not having economical sense in money invested in improving range of my EV which is currently 3 times my daily roundtrip (have two other projects sucking money with much-much greater ROI). Besides, my forklift SCR does great so far, for $0 invested especially. I can source some parts for pennies and possibly build better controller, just need to get my head around it.

And most probably will buy Aptera once it's avialable. You can line up to buy my Fiero and upgrade it as much as you want then:)

EDIT: thank for for your comment in EDIT:) I'll try not to bug everyone to death here, and find a way to keep myself from spending money on already running car now - that one is difficult! Can you elaborate a bit on SCR vs PWM controller differences in adjacent topic?
 

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Discussion Starter · #45 · (Edited)
My simple analog PWM circuit for testing the power section.

This is a raw voltage controlled PWM circuit with no current limiting; current limiting would need to be added for practical use.

The first 555 is a sawtooth modulator operating at about 12KHz and the second 555 compares the throttle output 0-5V to the sawtooth output of the first 555 and outputting a 12KHz pulse stream with it's duty cycle modulated by the throttle output voltage of 0-5V; a hall effect throttle could also be used to replace the throttle pot shown.

The general NPN transistor at the end inverts the output so that the circuit shuts down with the output in an off state. If operating at higher voltages, an optoisolator could achieve the same results while adding isolation protection.




Pin out of the 555



Ill draw out the power section soon.
 

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Discussion Starter · #46 ·
The power section.

The 39 ohm resistors are non inductive 1 watt ceramic composition, part #OX390KE.

The 2 ohm resistors are non inductive 15 watt heat sink mounted in TO-126 cases, part #MP915-2-1%.

Technically an ancillary component and not shown is a precharge resistor, part#MP9100-100-1% which is a 100 watt, heat sink mounted in a TO-247 case.


 
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