My Motors got me to Tap into Radiant Energy

[prochiro]

Hi JohnStone
No, I was going to use SPW52N50C3
with the other parts presented on that circuit drawing for starters. Parts are in mail and I have some now. No problem if not correct as I expect changes. I have been reading you too long to not know change is sometimes necessary.
Dana

[JohnStone]

Hi Dana,
Now, I'd like to post an exact circuit some time later. Therefore please answer some questions.

What driver did you order UCC.... from manuacturer TI (Texas Instruments)? Cornboy seems to prefer an Micrel make but it is pin compatible.

Do you intend to build your circuit on bread board PCB?

What generator (output) do you have available? You need one independently what your signal source will be later on.

How many FETs per channel estimated?

What is your power source?

Do you own a scope?

The test circuits from 555 pulser apply to the monster driver as well.



We shall discuss later on some steps like:

• Heat sinks and mounting geometry of FETs
• Connection from FETs to driver
• Driver circuitry
• Opto and signal precondition
• Test procedures and measurements
• I feel it is essential to provide some means for over current protection in order to secure our investments. This circuit will be insertable later on.
• Controlled "misuse" of pulser

@Cornboy: Those questions relate to you as well. I'd like to give you premium support in order to develope a documented tutorial for all others.
Warm regards John

[Cornboy 555]

Hi Dana,
Now, I'd like to post an exact circuit some time later. Therefore please answer some questions.

What driver did you order UCC.... from manuacturer TI (Texas Instruments)? Cornboy seems to prefer an Micrel make but it is pin compatible.

Do you intend to build your circuit on bread board PCB?

What generator (output) do you have available? You need one independently what your signal source will be later on.

How many FETs per channel estimated?

What is your power source?

Do you own a scope?

The test circuits from 555 pulser apply to the monster driver as well.



We shall discuss later on some steps like:

• Heat sinks and mounting geometry of FETs
• Connection from FETs to driver
• Driver circuitry
• Opto and signal precondition
• Test procedures and measurements
• I feel it is essential to provide some means for over current protection in order to secure our investments. This circuit will be insertable later on.
• Controlled "misuse" of pulser

@Cornboy: Those questions relate to you as well. I'd like to give you premium support in order to develope a documented tutorial for all others.
Warm regards John

Hello John, DANA,UFO, and all, we are reaching into the area of high powered Solid State Relays or SSR's, i have done some reserch on these a while back and found them to be very expensive indead.

Also they are invairably potted, which means if they burn it's all over, the reason i mention this is i believe we should , right from start, build something that is not just a ferrari, but also the staying power of a D9 bulldozer, SO WHAT if using the best driver costs $1.50 more, and if the best possible way is to use one driver per fet, well let's do that. Those 12A drivers are only $3.50 ea.

Some SSR's are $350.00 and are low voltage compared to what we are doing, also they still require external transient protection, so lets not skimp on small components that can make all the difference.

www.hellroaring.com/SSR-10300-x.pdf


@John the fets you recomend are the best value for money for type that i can find also, i will go for them.

Shortly i will know the specs of my motor and stator coils and then John i will ask for help if you would be so kind.

Regards Cornboy.

Also, the unit should be designed to easily replace components, eg, a plug in base for DIP8 components etc.

[JohnStone]

Hi Cornboy,
There are other reasons to do it ourselves. We want to design our overvoltage protection much higher than commercial devices provide.

Well, driving two FETs with one of those tiny moster drivers is quite viable. Just for your imagination: If you have a normal 1A driver it is like having a hammer made of hard rubber - quite usable for assisting many tasks.
If you use a hammer of same weight made out of steel you will get much more impact with same effort. In this case you can hit two nails (FET) at same time and they will move.

Referring to bulldozer - not good comparison. We need a racing bulldozers. Different from this mechanic example - current electronics provides us with "racing bulldozers" because it does not suffer on inertia - OK electrons have super ultra tiny inertia though. So imagine a super light weight racing bulldozer assisting your motors.

regarding robustness: Yes we need it like bulldozers and you will see those protection circuits soon.

JohnS

[JohnStone]

Hi Lester,
tinkering in my mind with overcurrent protection I suggest this circuit.

The shunt can be a 2" copper wire.
I'd like to get it much more simpler but I doubt.
This circuit will stop any pulse in premature state if the current exceeds a certain predefiend value. Along that these special gates perform as schmidt triggers (74HC132) in order to condition the signal.

Function:

1. The FF U1 will be set by any active edge of a signal forwarding an enable signal (output Q) to the gate U1 following.
2. Any overcurrent detection will reset the FF forwarding a pulse disable (output Q) to the gate followieng.
3. The FETs will be switched off instantly.
4. Any new enable will be defended as long the overcurrent condition being active.
5. Proceed with #1

The graph below shows (sorry: please read from bottom to top):

• output signal to FET driver (top) - watch the premature pulse end!
• comparator output signal - threshold 5 mV / signal 6 mV max.
• signal from shunt
• signal from generator / opto (bottom) - GND active

Using such a circuit we can put the generator to higher pulse length and let the end of pulse be defined by the time when the coil suffers the max. current being preset.
If we try to find an optimum for our setup we may decrease the power voltage down to the pulse length required.

Lester, do you find some flaws or uncertainities? Do you know of a simpler way? Please post your thoughts.

BTW: Thanks again for the hint to Symetrix

@All others: do not be afraight of this discussion. It is advanced and you wil get a verfied circuit as addon to the pulser.
JohnS

[Cornboy 555]

R B D.

Hi Cornboy,
There are other reasons to do it ourselves. We want to design our overvoltage protection much higher than commercial devices provide.

Well, driving two FETs with one of those tiny moster drivers is quite viable. Just for your imagination: If you have a normal 1A driver it is like having a hammer made of hard rubber - quite usable for assisting many tasks.
If you use a hammer of same weight made out of steel you will get much more impact with same effort. In this case you can hit two nails (FET) at same time and they will move.

Referring to bulldozer - not good comparison. We need a racing bulldozers. Different from this mechanic example - current electronics provides us with "racing bulldozers" because it does not suffer on inertia - OK electrons have super ultra tiny inertia though. So imagine a super light weight racing bulldozer assisting your motors.

regarding robustness: Yes we need it like bulldozers and you will see those protection circuits soon.

JohnS

Racing Bull-Dozers it is, then John Stone, Thanks Cornboy.

[Cornboy 555]

Hmmmm, ok, i think.

Hi Lester,
tinkering in my mind with overcurrent protection I suggest this circuit.

The shunt can be a 2" copper wire.
I'd like to get it much more simpler but I doubt.
This circuit will stop any pulse in premature state if the current exceeds a certain predefiend value. Along that these special gates perform as schmidt triggers (74HC132) in order to condition the signal.

Function:

1. The FF U1 will be set by any active edge of a signal forwarding an enable signal (output Q) to the gate U1 following.
2. Any overcurrent detection will reset the FF forwarding a pulse disable (output Q) to the gate followieng.
3. The FETs will be switched off instantly.
4. Any new enable will be defended as long the overcurrent condition being active.
5. Proceed with #1

The graph below shows (sorry: please read from bottom to top):

• output signal to FET driver (top) - watch the premature pulse end!
• comparator output signal - threshold 5 mV / signal 6 mV max.
• signal from shunt
• signal from generator / opto (bottom) - GND active

Using such a circuit we can put the generator to higher pulse length and let the end of pulse be defined by the time when the coil suffers the max. current being preset.
If we try to find an optimum for our setup we may decrease the power voltage down to the pulse length required.

Lester, do you find some flaws or uncertainities? Do you know of a simpler way? Please post your thoughts.

BTW: Thanks again for the hint to Symetrix

@All others: do not be afraight of this discussion. It is advanced and you wil get a verfied circuit as addon to the pulser.
JohnS

Wooosssshh, watts that funny sound?, just the sound of John's post going in one of my ears and then straight back out the other.

Cornboy.

[asollid]

Hello ufo people I am trying to understand the need for a fast rising edge. It is clear that RE enters only at the falling edge so i understand the need for a short fall time. But what enters at the leading edge? Nothing but hot current which we dont care about (except to build up a magnetic field.) So it seems to me we could be real slow on the rise time(on time.) Hope i havent made a fool of myself here. It wouldnt be the first time i had to remove my foot from my mouth.

[JohnStone]

Hello ufo people I am trying to understand the need for a fast rising edge. It is clear that RE enters only at the falling edge so i understand the need for a short fall time. But what enters at the leading edge? Nothing but hot current which we dont care about (except to build up a magnetic field.) So it seems to me we could be real slow on the rise time(on time.) Hope i havent made a fool of myself here. It wouldnt be the first time i had to remove my foot from my mouth.

Welcome asollid!
Anybody who wants to learn is welcome. Foolish can be answers only

There are two sources of heat if operating FETs. ON resistance (RDSon) and switching transition where the FET passes from high to low resistance or vice versa. For low power operation this is less important but as we exceed 10A it is an issue.
We have no influence to RDSon resistance but to switching time and this tool enables us to get FETs cool while operating. If we omit that we produce more heat and heat increases RDSon and this increases heat. Thus we might enter in a spiral of death. BTW: Therefore it is essential to not calculate normal operation with absolute maximum values aut of the datasheet.
So please understrand short switching time is a matter of economy (less FETs and heatsinks) and robust design.
For your imagination: At high power applications it is easy to kill a FET within 10µs if short circuited.
JohnS

[JohnStone]

Wooosssshh, watts that funny sound?, just the sound of John's post going in one of my ears and then straight back out the other.

Cornboy.

Yea! I knew how you feel. I targeted from Germany to Lester and you got the beam es well because you sit in the same direction. Sorry for hitting your ears Please stand 10 feet aside next time.
For your understanding: In high power applications a FET sits there like a queen bee in her hive and is supposed to do just ONE task. In order to perform lots of workers and soldiers are busy supporting this ONE task. These workers are i.e. drivers and PSUs while soldiers are overvoltage protection, overcurrent protection, pulse shapers.... No big deal if you look at the components but lots of sophistication behind.
JohnS

[Lester444]

Hi Lester,
tinkering in my mind with overcurrent protection I suggest this circuit.

The shunt can be a 2" copper wire.
I'd like to get it much more simpler but I doubt.
This circuit will stop any pulse in premature state if the current exceeds a certain predefiend value. Along that these special gates perform as schmidt triggers (74HC132) in order to condition the signal.

Function:

1. The FF U1 will be set by any active edge of a signal forwarding an enable signal (output Q) to the gate U1 following.
2. Any overcurrent detection will reset the FF forwarding a pulse disable (output Q) to the gate followieng.
3. The FETs will be switched off instantly.
4. Any new enable will be defended as long the overcurrent condition being active.
5. Proceed with #1

The graph below shows (sorry: please read from bottom to top):

• output signal to FET driver (top) - watch the premature pulse end!
• comparator output signal - threshold 5 mV / signal 6 mV max.
• signal from shunt
• signal from generator / opto (bottom) - GND active

Using such a circuit we can put the generator to higher pulse length and let the end of pulse be defined by the time when the coil suffers the max. current being preset.
If we try to find an optimum for our setup we may decrease the power voltage down to the pulse length required.

Lester, do you find some flaws or uncertainities? Do you know of a simpler way? Please post your thoughts.

BTW: Thanks again for the hint to Symetrix

@All others: do not be afraight of this discussion. It is advanced and you wil get a verfied circuit as addon to the pulser.
JohnS

Hello JohnS,

I see 6mVp signal from shunt, fed into LM393 comparator. This comparator has maximium Input Offset Voltage (Vos or Vio) of 5mV. That means your input "will look like" +11mV or 1mV or any value in between, to the comparator at say 5 weeks down the road. Which gives you an inaccuracy of roughly +/- 83% at any point in time. That is VERY BAD ACCURACY.

I think you need accuracy of better than +/-1%. Maybe OP-07 is better. Or some other precision comparator or op-amp.

To get the accuracy that you need, you can either
1. Go for high-precision comparators / op-amps
2. Increase the shunt voltage <---- power loss, heat

This is the reason why I do not like shunts so I proposed the current transformer earlier.

Lester

[Lester444]

fo some reason I could not edit my post now.........

JohnS,

The OP-07 will not work because the input signal MUST be more positive than V- pin by some volts. In your diagram the V- pin is connected to GND.

You need to find high-precision comparator or op-amp whose input "INCLUDES GROUND". That's how they say it in the datasheet. Look at "Input Voltage Range".

Lester

Additional info:

It is better to use Schmidtt trigger 74LS132 rather than 74HC00, for noise immunity. I am not sure
if it is available in "HC" high-speed CMOS.

Put 100-ohms to 1k-ohms in series with each input pin of comparator, that's 2x additional resisitors,
for protection and easy debugging. These 2x resistors have no effect on signal.

I think D f/f output is always high after the first pulse. Please correct this. If you want 1/2 of input
frequency you can connect D-input to Q-not output.

[JohnStone]

fo some reason I could not edit my post now.........

JohnS,

The OP-07 will not work because the input signal MUST be more positive than V- pin by some volts. In your diagram the V- pin is connected to GND.

You need to find high-precision comparator or op-amp whose input "INCLUDES GROUND". That's how they say it in the datasheet. Look at "Input Voltage Range".

Lester

Well you are right!
I did not focus on this fact but to the digital function. In fact I ordered this sensor. It is contactless (hall effect), lowest resistance and replaces a shunt directly.
Regarding digital part. Is there a smarter way to perform? Single chip? We approach a complexity where we need PCB.

[Lester444]

Well you are right!
I did not focus on this fact but to the digital function. In fact I ordered this sensor. It is contactless (hall effect), lowest resistance and replaces a shunt directly.
Regarding digital part. Is there a smarter way to perform? Single chip? We approach a complexity where we need PCB.

The link doesn't work.

If you use a linear hall sensor then you have to worry about calibration, maybe once every month or even more often than that!!! Don't trust drift figures in the datasheet, it is not tested 100%. Trust me when I say that!

Passives are superior in this regard because they stay calibrated for a very long time. No worry, stay happy.

[JohnStone]

Hi Lester,
I agree with your concern and experienced it at a scope based current meters. I own such an old pet (Tectronix) and it proves you to be true.
On the other hand we may consider:

• This monolitic all in one component in automotive grade (1.5% accuracy) might be an advance compared with former makes.
• We do not want to measure exactly but to protect and thus it is not important if we stop current at 30A or 35A as long we prevent running FETs at maximum ratings.

Component: ACS714
Breakout board I prchased: here

Consult: this

I will go ahead and test it.
--------------------------------
@ALL not being gurus in electronics! Do not fall into despair! We need to discuss this on this level. You will get solid instructables later on.