Quark ESC Power Board Comparisons/Mods

[BrianG]

Wow! First of all, let me say you are tackling a complex project here!

When you say PNP/NPN, I assume you are familiar with bipolar transistors. Transistors are "current" driven, have a current gain (beta), and have a set collector to emitter voltage drop even at saturation. MOSFETs are voltage driven (they don't load down driving circuits) and their drain to source v drop is determined by the Rdson value and current flow. Think of them more like a faucet where the source is the water tank, the drain is the output, and the gate is the valve. Rough analogy, but sufficient. There are other differences, but you see what I mean - it's like comparing apples to oranges.

Aside from being N or P channel, are they enhancement or depletion types? I would think you would NEED enhancement types, but I dunno.

Sorry I can't help you any further on this as I've never really dealt too much with FETs at the design level.

The Quark 125 uses the same FET parts, just more of them. IIRC, they are the same on both sides.

[sikeston34m]

Originally Posted by BrianG

Wow! First of all, let me say you are tackling a complex project here!

When you say PNP/NPN, I assume you are familiar with bipolar transistors. Transistors are "current" driven, have a current gain (beta), and have a set collector to emitter voltage drop even at saturation. MOSFETs are voltage driven (they don't load down driving circuits) and their drain to source v drop is determined by the Rdson value and current flow. Think of them more like a faucet where the source is the water tank, the drain is the output, and the gate is the valve. Rough analogy, but sufficient. There are other differences, but you see what I mean - it's like comparing apples to oranges.

Aside from being N or P channel, are they enhancement or depletion types? I would think you would NEED enhancement types, but I dunno.

Sorry I can't help you any further on this as I've never really dealt too much with FETs at the design level.

The Quark 125 uses the same FET parts, just more of them. IIRC, they are the same on both sides.

Thanks for the reply Brian. You're very knowledgeable and I was hoping you would chime in on this.

I like your analogy. It's a good one since DC Current only flows one way. I've often thought like that too.
I find myself switching back and forth between the two sets of data sheets comparing figures and I find no reference on either as being enhancement or depletion types.

I think I'm in the ball park on compatibility. The donor drive unit that gave up these bigger MOSFET's served as a controller for a 36 volt drive motor. The motor is brushless and is a 6.6kw unit. This was not a sensorless setup by any means. It pushed around a 9500 pound Industrial truck at 9mph.
The Controller these came out of has an extensive brain board that uses an encoder bearing in the motor to calculate timing. Based on encoder information, the controller knows motor speed and armature postion. Much like the Novak sensor based setups.

I want a high Amperage Car Controller that will do multipole motors! A HV setup that will do 36 volt reliably would be a dream come true.

[GriffinRU]

I'm sorry but I do not think that this is a good idea, based on your questions...

P.S. But if you willing to try, then shoot me PM and I will try to help you out with design.

[sikeston34m]

Originally Posted by GriffinRU

I'm sorry but I do not think that this is a good idea, based on your questions...

P.S. But if you willing to try, then shoot me PM and I will try to help you out with design.

Hi Griffin,

Thanks for volunteering to lend a hand. I appreciate that. I have followed some of your work and respect you as being one of the most knowledgeable people around here on this.

I look at myself in this, like a student, that has alot to learn. But I like to challenge myself, sometimes things work out for the better, and sometimes they don't. But in the process, along the way, knowledge is gained.

I have spent several hours tonight just reading about principles of operation. There's alot to learn, but this is how we grow.

[GriffinRU]

Originally Posted by sikeston34m

Hi Griffin,

Thanks for volunteering to lend a hand. I appreciate that. I have followed some of your work and respect you as being one of the most knowledgeable people around here on this.

I look at myself in this, like a student, that has alot to learn. But I like to challenge myself, sometimes things work out for the better, and sometimes they don't. But in the process, along the way, knowledge is gained.

I have spent several hours tonight just reading about principles of operation. There's alot to learn, but this is how we grow.

Cool, I was planning to start writing in Brian's thread about "ESC's".
Creating threads on modifying ESC's my goal was to help hobbyists to improve their controllers without knowing too deep how it works. And for any good electrical engineer all my tricks are quite obvious, but to design good ESC will require more then just EE...experience helps allot! :)

[sikeston34m]

Ok, according to the data sheets, here's the resistence values:

Big MOSFETS - RDS(ON)= 0.010 ohms max with 0.0082 ohms typical
No Gate Resistence value listed

Quark 80 amp MOSFETS - RDS(ON)= 2.2 megaohms
Gate Resistence = .6 ohms

The Big Mosfet data sheet doesn't list a Gate resistence value.

I wonder how much current the Gate lead circuit in the Quark 80 Brain board can support?

[GriffinRU]

Originally Posted by sikeston34m

Ok, according to the data sheets, here's the resistence values:

Big MOSFETS - RDS(ON)= 0.010 ohms max with 0.0082 ohms typical
No Gate Resistence value listed

Quark 80 amp MOSFETS - RDS(ON)= 2.2 megaohms
Gate Resistence = .6 ohms

The Big Mosfet data sheet doesn't list a Gate resistence value.

I wonder how much current the Gate lead circuit in the Quark 80 Brain board can support?

They should have Rg mentioned somewhere, maybe on the Graph...
This parameter responsible for FET's frequency response, noise and etc when you run simulation and important in design stage.
"Big" fets are usually slow, bulky and rated for high power plus in most cases have lower RDS(On) then "smaller" ones.

You need to check for fet driver part number in Quark 80 brain and study the circuit around it. To calculate required Voltage and Current check for switching frequency and total gate charge. Then do the same calc with different loads and temps.

[sikeston34m]

Here's the Data sheet on the Big Mosfets that I intend to use for the new powerboard.

http://www.fairchildsemi.com/ds/HU%2FHUF75545P3.pdf

Here's the datasheet for the Quark 80 Power Mosfets.

http://www.ortodoxism.ro/datasheets/...3S_Rev1.11.pdf

Griffin, could you take a look at these and tell me if they are capatible with each other?

I'm going to research the driver fet's in the Quark 80 now.
Thanks.

[lutach]

Keep in mind the higher you go in voltage the higher the resistance will be. You can find 40V MOSFETs that have extreme high AMP ratings, but they will be limited to silicon and/or die ratings. Browse www.irf.com or www.infineon.com and you can find a great selection of MOSFETs. There are also various other brands out there.

[GriffinRU]

Originally Posted by sikeston34m

Here's the Data sheet on the Big Mosfets that I intend to use for the new powerboard.

http://www.fairchildsemi.com/ds/HU%2FHUF75545P3.pdf

Here's the datasheet for the Quark 80 Power Mosfets.

http://www.ortodoxism.ro/datasheets/...3S_Rev1.11.pdf

Griffin, could you take a look at these and tell me if they are capatible with each other?

I'm going to research the driver fet's in the Quark 80 now.
Thanks.

Well, it is hard to give you straight answer, because more info requires about application, like in your case what are the current ratings of fet's driver current and power ratings of system providing power to fets' driver IC's? Do they use bootstrap technique in Quark 80 if yes then what capacity bootstrap cap has and what are diode ratings?
Then what exactly you would like to accomplish, stock configuration or higher voltage/current one. How many Fets you would like to use...

As far Rg for "Big" Fet - check on page 6 inside PSPICE model RGATE value 0.87

And, I tend to agree with lutach there are plenty fets, what so special about this one?
I mean both MGM, Quark, Castle... are using probably the best fets for the price and ease of assembly, when you shooting to do something custom you want to get the best (regardless of price and assembly pain) and deal with tuning and tweaking until "green light".