1971 Corvette EV Conversion

[adamj12b]

Originally Posted by watahyahknow

i was wondering about those controllers and how they work is it a solid state version of a row of relays raising the power in stages ? trying to see how its build i seen some drawings that look loke its the same scematic multiplied a couple of times

Hello whatahyaknow,

The controller uses 21 mosfet/diode pairs. A mosfet is basicially an digital on/off switch. These mosfets are rated to 130 Amps, and the diodes are rates to 90 Amps. I have derated to 80 Amps maximum continous current to keep them from being destroyed. The diodes are really the limiting factor.

There is a microcontroller that creats a frequency called PWM (Pulse Width Modulation). This is a high frequency square wave that tells the mosfets to turn on and off. With the PWM you can control the output voltage and current of the controller, Thus controlling the speed.

Here is the latest schematic of pauls controller. My controller uses this schematic as a base. I upgraded the diodes to the higher rated 90 amp ones, but these are twice as expensive Paul calls for 10 mosfet/diode pairs, All I did was increase this to 21 to increase the power of the controller.

Here is the schematic for refference.

-Adam

[watahyahknow]

so if i understand correctly its not like you turn on 1 2 3 4 5 etc banks in line to turn on the power but just divide the switching across more banks/switches(diodes) when youre running a bigger set of batteries (more volts) making the power that one bank gets to deal with lower or the same as whith the lower voltage .
its now starting to dawn on me you can basicly add swiches and banks upto infinity to get the amount of power you want to put intoo it switched , allthough it must be harder to dose the amount of power comming out
the power steps up twice as fast when you double the switches and open the trottle
so finetuning becomes sumting like writing the bible on a grain of rice
it will take some time i bet to make it work in my mind so i can see whats happening with the programming when a switch(diode) stays in the open poition and all that

amplification in this case basicly means being able to switch a bigger current with a small signal

[esoneson]

Originally Posted by adamj12b

I upgraded the diodes to the higher rated 90 amp ones, but these are twice as expensive Paul calls for 10 mosfet/diode pairs, All I did was increase this to 21 to increase the power of the controller.

Adam,

Did you also add more mosfet drivers to the control section to handle the increase number of mosfets? Seems like there was a timing issue when a single driver interfaced to that many mosfets due to wire length differences.

Eric

[adamj12b]

Originally Posted by esoneson

Adam,

Did you also add more mosfet drivers to the control section to handle the increase number of mosfets? Seems like there was a timing issue when a single driver interfaced to that many mosfets due to wire length differences.

Eric

Hi Eric,

Simply, Yes.

I have 3 driver boards that each drive 7 mosfets. These 3 driver boards will be connected by 3 pieces of cable all the same length. All the traces on the 3 driver boards are exactly the same length as well. Thus, allowing the pulses to reach each mosfet in almost unity.

-Adam

A picture of the layout of the driver boards.

[esoneson]

This is looking real pretty Adam. I like this a lot better than incorporating the driver on the controller board. It gives the builder a lot of options for meeting their (amp)power requirements.

Eric

[adamj12b]

If you liked that you might like this as well. Here is a picture of the controller board layout. the board in this layout is 2.0 x 2.6 inchs.

It is almost all surface mount also.

-Adam

[adamj12b]

I almost forgot. Here is the picture of the layout of the power board. The big square in the middle is where the control section goes. It use to be smaller, then I expanded it to fit the current sensor section.




-Adam

[esoneson]

Adam,

You already had my attention, now I am drooling. Gotta clean up my keyboard.

This is fabulous work. I take it you do this for a living when you aren't up to your elbows in grease.

The limitations that I saw in Paul's basic kit seem to be totally solved with your design/implementation. I was worried that I would need more amps with my application and it seems you have solved that in spades. Paul has been saying that his will support 500 amps with no problem and that is with 11 mosfets sharing the load. Can I safely assume that your design will handle more than 1000 amps? I know that the mosfets are designed with a limit of 200 volts and Paul mentioned that he thought that 144 volts was the max safe limit that should be followed. But then again you are looking at 161(?) volts. Is your confidence in that limit based on any other changes that you have made?

I am still in the design stage of what I want to do. And what you have here seems to fit quite nicely for me. Any chance that you are going to offer a kit or at least pcb's and bom to aid the ambitious folks lacking in EE skills like myself? I'm sure that I am not the only one thinking along these lines.

Nice work and I appreciate you sharing those purdy images.

Thanks again.

Eric

[adamj12b]

Originally Posted by esoneson

Adam,
This is fabulous work. I take it you do this for a living when you aren't up to your elbows in grease.

HA, I wish this was my job. I am a shipping and inventory manager for an energy management company thats part my father-in-laws. I just do this stuff as a hobby. I do a small amount of electronics stuff for work, Like right now im working on a custom wireless monitoring system to get some signals across a very large mall. Its very interesting.

Originally Posted by esoneson

The limitations that I saw in Paul's basic kit seem to be totally solved with your design/implementation. I was worried that I would need more amps with my application and it seems you have solved that in spades. Paul has been saying that his will support 500 amps with no problem and that is with 11 mosfets sharing the load. Can I safely assume that your design will handle more than 1000 amps? I know that the mosfets are designed with a limit of 200 volts and Paul mentioned that he thought that 144 volts was the max safe limit that should be followed. But then again you are looking at 161(?) volts. Is your confidence in that limit based on any other changes that you have made?

Well, First off I would have not come this far with the controller if it wasn't for Paul, he has come up with a terrific design. My budget was just above what he had planed for. Thats how this became. Paul says 50A per mosfet/diode pair. That is with the regular diodes that hold the controller back. The ones I am using are good for 90A each up from 60A. So even at the low end of 50A per pair, that 1050A total for the controller. If you bump it up to 80A for my upgraded parts, thats 1680A total.

As for the voltage, Right now, I'm setting the limit at 144V like Paul's controller. We are working together to raise the voltage hopefully above the 162V goal of mine. I have drawn up a simple test circuit board with 2 mosfet/diode pairs and 4 capacitors. I will be using this with a 14.4khz PWM generator circuit. I have up to 20 SLA batteries I will be hooking up to the small power circuit to measure the voltage spikes. I have a 2HP treadmill motor on the way for a load as well. I will start with 11 batteries fully charged at 12.74V each, yielding 140.14V. I will take a measurement on the O-Scope, then add a battery and repeat. I will be charting open voltage, load voltage, current, and temperature in an excel table. Depending on how bat the voltage spikes are at the certain measurements, I will keep adding batteries. 16 Batteries fully charged will be 199.04V, So I dont think I will be going that high. I do hope to be able to make it to 14 batteries for an open circuit voltage of 178.36V.

Originally Posted by esoneson

I am still in the design stage of what I want to do. And what you have here seems to fit quite nicely for me. Any chance that you are going to offer a kit or at least pcb's and bom to aid the ambitious folks lacking in EE skills like myself? I'm sure that I am not the only one thinking along these lines.

Nice work and I appreciate you sharing those purdy images.

Thanks again.

Eric

I can say I will offer at the least the BOM, but there is almost nothing different from Paul's, just a few components. I would like to offer a kit, but i don't know if that will happen. If I can find a supplier in the states for some form of heat sinked case, I will purchase one and modify the design to fit it.

-Adam

[MPaulHolmes]

Eric, you are right that there should be a separate driver board. I want to make that change too. As adam has demonstrated, there is basically no limit to the power when you have the flexibility of changing the driver board. It really doesn't belong on the control section.

It will also make assembly and disassembly much much much easier too (if you ever wanted to do that). I can't wait for Adam's controller. He thinks big!

Also, those surface mount control boards are tiny! I bet that would be way cheaper in bulk.