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Discussion Starter #1
Hi

I am searching for a special kind of controller for 3 phase motors.
The difference between my request and normal BLDC-controller is that I do not need the PWM and sensing.

I have tried to google a hex-program that do not have the PWM included, but all is using PWM to regulate the speed of motors.

The only variable I need is the frequency that the circuit will operate on.

So if I program the microprosessor that the motor will go at 50 hz, the switching is done accordingly a BLDC, but without PWM and any sensing from motor.

Is there anyone that can help me with this?
 

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Hi MR2, Welcome to the forum.
What car are you going to convert?

I think I know what you want to do... May I take a guess?
You want to drive an AC motor with a fixed 50Hz frequency out of a square wave voltage?
 

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Discussion Starter #3
Hi MR2, Welcome to the forum.
What car are you going to convert?

I think I know what you want to do... May I take a guess?
You want to drive an AC motor with a fixed 50Hz frequency out of a square wave voltage?
The car is not yet decided. I have to first find out if it works on 3 phase motors first. It's a new invention I have.
On 1 phase not so good motors I have achieved 59 % decrease of energy needed to do the same amount of work.

Now I need to do a test on 3 phase high voltage asynchronous motors to see if it works there too.

But all BLDC controllers with its ATMEGA controller uses PWM to regulate speed. I am using just the frequency of cycles.

I am making a perfect sinusiodal drive of the motor without EMF.
But PWM destroys the effect.
 

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OK, you have a budget for the donor & conversion? Designing & building your own motor drive/ inverter soon ads up, possibly even more expensive.


Driving AC induction motors as traction drives requires control of the rotor current. This can today only be done by a concept named Field Oriented Control. This is a fancy word for rotor slip control. :rolleyes:

I do not think the stator & rotor would work together very well with square voltages. The current is likely very difficult to get sinus sodial at low rpm's. At Max power point & up where the torque would start to roll off as the maximum applied voltage is being applied may work with square waves. But I cannot imagen it to work for lower RPM's without PRM.

Since when did PWM go out of fashion? :D
What is your background? Have you studied the common existing 3 phase ac drive principles?
 

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Discussion Starter #5
OK, you have a budget for the donor & conversion? Designing & building your own motor drive/ inverter soon ads up, possibly even more expensive.


Driving AC induction motors as traction drives requires control of the rotor current. This can today only be done by a concept named Field Oriented Control. This is a fancy word for rotor slip control. :rolleyes:

I do not think the stator & rotor would work together very well with square voltages. The current is likely very difficult to get sinus sodial at low rpm's. At Max power point & up where the torque would start to roll off as the maximum applied voltage is being applied may work with square waves. But I cannot imagen it to work for lower RPM's without PRM.

Since when did PWM go out of fashion? :D
What is your background? Have you studied the common existing 3 phase ac drive principles?
The motor will ”see” a clean AC made without PWM. But not normal 3 phase, but like a BLDC driven motor. I know the motor will not notice any difference from normal PWM. There is no square voltages. Just perfect sinus.

I have only tried my invention on normal BLDC motors. Thats because I haven’t yet been able to find a program without PWM. I could use money on professionals, but if there is a easy way to remove the lines enabling PWM would be the best way. Then I will find out how effective my invention is.
 

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Quite mystical. :rolleyes:

You are not referring to resonant switched mode supplies/drives are you?
What college/uni background do you have?
 

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Discussion Starter #7
Quite mystical. :rolleyes:

You are not referring to resonant switched mode supplies/drives are you?
What college/uni background do you have?
Nothing like that. Just a new way of using energy.

I have no background. No education in this. But I am tested at Mensa, using 10 minutes to answer the 45 questions and when deliver the formular, asking them if they couldn't do better.. Max score 145.
Envying Sheldon Coopers eidetic memory.. hehe..
 

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I have only tried my invention on normal BLDC motors. Thats because I haven’t yet been able to find a program without PWM. I could use money on professionals, but if there is a easy way to remove the lines enabling PWM would be the best way. Then I will find out how effective my invention is.
If you've been able to test your scheme on BLDC why can't you test it on induction motor? Both are 3ph machines, there is not much difference in the controls.
 

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Well, you could run the switches in a linear mode to get perfect sine waves. However they'll get hot and will need to be grossly oversized. Full on (low resistance) and full off (very high resistance) are low heating states for silicon switches, but 1/2 gives resistance that heats them up.

You could also do a scheme with many batteries, and switch the voltage up and down via various combos of batteries. It's going to be a challenge to keep the batteries balanced, but at least you can have your voltage jumps as 2 or 3 Volt steps rather than 0 to full pack voltage.

A typical system has inductance and capacitance, this tends to smooth the PWM waves.

Something you might want to look at is switched reluctance. You just switch them coarsely, not the fine fast switching of typical PWM. The shape of the poles helps give you some sine-like behavior.
 

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Discussion Starter #11
Well, you could run the switches in a linear mode to get perfect sine waves. However they'll get hot and will need to be grossly oversized. Full on (low resistance) and full off (very high resistance) are low heating states for silicon switches, but 1/2 gives resistance that heats them up.

You could also do a scheme with many batteries, and switch the voltage up and down via various combos of batteries. It's going to be a challenge to keep the batteries balanced, but at least you can have your voltage jumps as 2 or 3 Volt steps rather than 0 to full pack voltage.

A typical system has inductance and capacitance, this tends to smooth the PWM waves.

Something you might want to look at is switched reluctance. You just switch them coarsely, not the fine fast switching of typical PWM. The shape of the poles helps give you some sine-like behavior.

It is not done in any of those ways. I have a power source, my invention, the switching and then the motor. Nothing more, nothing less. The perfect sine is selfachieved. Should not be there, but it sure happens. No spikes at all when switching on-off. No BEMF.

I am just looking for a hex-file for ATMEGA processor without PWM and any normal sensing (Hall or EMF) from typical 3 phase BLDC motors.
 

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But I am tested at Mensa, using 10 minutes to answer the 45 questions and when deliver the formular, asking them if they couldn't do better.. Max score 145.
You know, even if you spiked the Mensa-test it doesn't give you the rights to break the laws of physics.
 

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Discussion Starter #14 (Edited)
You know, even if you spiked the Mensa-test it doesn't give you the rights to break the laws of physics.
No, and I don't.

But it is not the question why and how it works or not, but if anyone know how or can help me out with a hex-file without PWM and trigging by sensing either by Hall or EMF.

Just the switching like BLDC 3 phase motors by a frequency set in a variable.


I made these lines in C

#include<avr/io.h>
#include<util/delay.h>

int main()
{
unsigned char i;
DDRA = 0xFF; // all a-ports as output

while(1)
{
for(i=0;i<6;i++)
{
PORTA=0; // open all outputs that gives break before make

// _delay_ms(1); (optional delay 1 ms before make)

switch(i){
case 0:
PORTA=162; // step 1
break;
case 1:
PORTA=97; // step 2
break;
case 2:
PORTA=145; // step 3
break;
case 3:
PORTA=84; // step 4
break;
case 4:
PORTA=140; // step 5
break;
case 5:
PORTA=74; // step 6
break;
}
_delay_ms(150); // length of pulse
}
}
return(1);
}



Would this work?


Maybe use 1 b port as input for sensing if the motor is running...
 

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Are saying single phase is DC? If so you're incorrect. 120V motors are single phase as are 208V and 480V motors that have only TWO WIRES. That's single phase. There also is no such thing as two phase. It's either single phase or three phase and of course there's DC.:D
That motor is listed on their website as DC, PWM control.
 

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Actually there are 2 phase motors. The second phase is driven by a capacitor, causes a delay for that phase, just to get the motor started. Then it is primarily a single phase motor once running.

You wouldn't do a 2 phase motor in an EV because it would take 8 switches. Doing 3 phases takes just 6, because you can hook the field coils together in a star or delta arrangement. There might be some esoteric math thing with the phases, too, any comments on that Major?
Are saying single phase is DC? If so you're incorrect. 120V motors are single phase as are 208V and 480V motors that have only TWO WIRES. That's single phase. There also is no such thing as two phase. It's either single phase or three phase and of course there's DC.:D
 

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Actually there are 2 phase motors. The second phase is driven by a capacitor, causes a delay for that phase, just to get the motor started. Then it is primarily a single phase motor once running.

You wouldn't do a 2 phase motor in an EV because it would take 8 switches. Doing 3 phases takes just 6, because you can hook the field coils together in a star or delta arrangement. There might be some esoteric math thing with the phases, too, any comments on that Major?
Correct.

To All:
But as i said, that motor is a 24v DC according to the manufacturer. I know more about motors than most people, and i am NOT saying that DC = Single Phase, just to clarify. That motor is DC, NOT Single Phase. At least that's what the maker says.
 
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