I have a few pointers. Your mention of splitting ground planes usually refers to mixed signal circuits, where analog and digital low voltage signals are concerned. Inverters have thier control boards always galvanicly isolated. Instead of those small integrated dc-dc bricks they use a single smps running off the main dc rail with isolated windings powering each isolated subcircuit. Also current measurement is done on 2 sometimes on all 3 phases. One thing missing from your inverter is any brakeing circuit. A brakeing chopper transistor and a braking resistor are used to keep dc rail in check, as when you brake electronically, the energy goes back to the capacitors raising the voltage. If you brake without any resistor connected, the voltage will go well above normal and blow up the module or caps.(ask me how I know) Best of luck with your project. I would love to see how it turns out.
One issue with a charging resistor is that it doesn't solve huge current spikes during normal operation due to a very short conduction angle. Such large capacitance means that the peak current through the rectifier is many times the current draw of the device. This leads to higher losses and, more importantly, a lot of harmonics introduced. High power diode rectifiers like that create a lot of noise on the AC side which may affect other electronics. Even without PFC rectifiers, this can be partially remedied by adding a relatively large inductance after the rectifier. A 10 mH choke would smooth out the current spikes and it may also remove the need for the charging resistor altogether since the current is now limited by how quickly the choke current can raise since there's no longer a dead short between L and N. Cost-wise, the charging resistor circuit is a lot cheaper than appropriately sized choke (which is still cheaper than a 2 kW active rectifier) so it may be fine for a diy solution.
Great video. I am currently making a 115V/400hz power supply and your project is very interesting. I did not know STGIPQ which seems to be the right solution for my projet. I'm gonna read very carefully the AN4043 application note. Thank you very much for this work and sharing your knowledge.
Thank you for sharing all the videos, these are really helpful. However, I observed that u used 125V rated fuses in line with motor output, whereas ur system is designed for 230 V. Can u please explain this difference in the rating. Thank u
Thanks for your reply. Please see this datasheet in the link. It says 125V for 8A. www.lcsc.com/datasheet/lcsc_datasheet_2305151202_Shenzhen-JDT-Fuse-JFC2410-1800FS_C2994765.pdf
@@matanpazi3777 Thanks for the reply. I am referring datasheet from LCSC here. It says so. www.lcsc.com/datasheet/lcsc_datasheet_2305151202_Shenzhen-JDT-Fuse-JFC2410-1800FS_C2994765.pdf
Is it okay to not add lc filter in output? I read induction motor will easily hot and the winding vibrate if running with square wave, but idk with digital sine wave
Not sure for industrial applications. I don't think adding an LC filter would reduce heating or vibrations though. For simple applications I don't think it matters much. Here's a link to an article that goes over the reasons for adding an LC filter: ieeexplore.ieee.org/document/790930 In short: 1. High dv/dt may cause issues with long motor cables. A capacitor would help. 2. High frequency current ripple. An inductor would help. 3. High dv/dt leads to EMI. A capacitor would help. My inputs: 1. Seems like the cable limit length stated in the article is quite generous. A limit of 5[m] of cable for 10,000 V/us seems pretty good. 2. Current ripple depends on the motor inductance and the switching frequency. I suspect this is a non issue for most standard applications (Switching frequencies in the kHz and relatively high inductances, higher than 1 mH). 3. Sure, that could help. There are indeed quite high ripples of voltage on the motor phases, smoothing them out could help.
Thank you Mr. Pazi. This is one of the clearest explanations of VFD operation and design I have seen. I plan to share this with my engineers and technicians to improve their understanding of VFD theory and operation. As a side note, what CAD software do you use? Thanks again. Kind regards, John Stilwell
I also build my own vfd, yours was way much better. The difference is the motor driver ic, the relay and bleeding resistor, 1 phase to 3 phase capabilities, and i just use arduino uno because i was too lazy to build my own atmega 328 circuit. Nice job👍 Add: I do not see a step up transformer, your 2kw motor will only ouput around 1.5k without it.
@@matanpazi3777 did you know constant v/freq? Variable freqyency drive doesn't only control the frequency but the duty cycle. By controlling the duty cycle you control yhe average voltage. If you want to build something that already exist, first learn the current model then make your improvement. I made commercial vfd because i could improve current design, if not i just simply buy one. I mean why the hassle if i could buy one for few $$?
@@wiradharma7030 Can you please give a link to source explaining the need for step-up transformers in normal operation VFDs? Only found this: mb-drive-services.com/vfd-output-transformers-where-do-we-need-them/ And the most relevant reason was this: "VFD can certainly adjust the inverter voltage, but at lower voltages the power is reduced. If the customer wants the same power at each voltage level or relatively high power at lower voltages, the output transformer is beneficial." This really isn't an issue for my application.
i wondered if you could use a FET to discharge the caps, after switch-off...or a tiny relay off the AC input, to switch on the bleed resistors...or an optoisolator, from the AC input, which pulls down the gate of the discharge FET (a bit of RC, too) until the AC goes away, at which point the FET gets biased on, and pulls down the capacitors to some lower voltage...
There are definitely better ways to implement the bleeding of the capacitors. Not sure what relays/opto isolators can be fed by AC voltage, but there's probably some solution to this problem.
@@matanpazi3777 I figured out a circuit that could use an optocoupler, with a single diode from AS into a small R/C, so that the optocoupler holds down the gate of a FET, when AS is present, then allows the High Voltage DC to bias the FET on, as soon as the AC is gone for a second or two, which allows the FET to pull down the high voltage caps, through a fairly fat resistor, quickly, but without having the bleed resistor active when running... might be able to use this for soft start, too... Anyway, just an idea
@@matanpazi3777 V*I*(Power Factor) for AC circuits. As the frequency increases the impedance in the stator windings increases which lowers the power factor.
@@matanpazi3777 When I do a thought experiment I predict that the input current will remain constant as V/Hz increases, as long as the load remains the same.
@@matanpazi3777 If power factor correction was done on the motor, so a capacitor was added in the circuit to match the motors inductive reactance, the only impedance would be the resistance in the stator winding. I think the voltage needed to run the motor would be much less 🤷🏾♂️
Hi,bro✋ I want make a vfd for single phase motor Of course my English is not good and I didn't fully understand what you said in the video Can you help me ?
Sir, how did you calculate for the bus capacitors. Your calculated value is 26665 micro farad but you use less than that on the capacitor bus. Can you clarify pls. Thanks
Awesome project to begin with! I am also designing my own VFD and use your videos as a reference design guide. However, I do have a question about the DC-bus capacitors. As shown in the video you used the following formula: Farad = Ampere*second/Volt. The formula itself is clear, but in the sidenotes of the schematics you used 8[A] as current for the capacitors. How did you determine this? Since it is DC I thought it could be done with I=P/U, but then I don't get the same value.
This is a really good video. Sad you have not gotten more views. TH-cam's algorithm is not optimal. I have videos that I do not think are great but they have more views than others which explain more.
your work is marvelous but i face some difficulty with your program which have (ISR (TIMER0_OVF_vect); { ) This error..could you help me if you have some free time.
Hi, it's me again 😁I know you are tired of me already but I need to know the best programing language to use when programing an Arduino, thanks in advance.
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Man, I watched all 3 vfd videos and the level of presentation you provide is off the scale. I am speechless. 👌👍
I have a few pointers. Your mention of splitting ground planes usually refers to mixed signal circuits, where analog and digital low voltage signals are concerned. Inverters have thier control boards always galvanicly isolated. Instead of those small integrated dc-dc bricks they use a single smps running off the main dc rail with isolated windings powering each isolated subcircuit. Also current measurement is done on 2 sometimes on all 3 phases. One thing missing from your inverter is any brakeing circuit. A brakeing chopper transistor and a braking resistor are used to keep dc rail in check, as when you brake electronically, the energy goes back to the capacitors raising the voltage. If you brake without any resistor connected, the voltage will go well above normal and blow up the module or caps.(ask me how I know) Best of luck with your project. I would love to see how it turns out.
Great work. Recently, I have been fixing a VFD board. Your video has lifted my understanding to another level. Thanks heaps.
Thank you for Video.
I was looking for video about hardware used in vfd drives. that was good.
Super informative!
Thanks for sharing the process and the knowledge you gained while working in it 💪🏼
One issue with a charging resistor is that it doesn't solve huge current spikes during normal operation due to a very short conduction angle. Such large capacitance means that the peak current through the rectifier is many times the current draw of the device. This leads to higher losses and, more importantly, a lot of harmonics introduced. High power diode rectifiers like that create a lot of noise on the AC side which may affect other electronics.
Even without PFC rectifiers, this can be partially remedied by adding a relatively large inductance after the rectifier. A 10 mH choke would smooth out the current spikes and it may also remove the need for the charging resistor altogether since the current is now limited by how quickly the choke current can raise since there's no longer a dead short between L and N.
Cost-wise, the charging resistor circuit is a lot cheaper than appropriately sized choke (which is still cheaper than a 2 kW active rectifier) so it may be fine for a diy solution.
Great video. I am currently making a 115V/400hz power supply and your project is very interesting. I did not know STGIPQ which seems to be the right solution for my projet. I'm gonna read very carefully the AN4043 application note. Thank you very much for this work and sharing your knowledge.
Thanks a lot! Happy to hear it helped.
Good luck on your project!
Very informatic. good luck
Very good explained. Looking forward for the software section as I am doing something similar, except I am using STM32.
Thanks!
Good luck with your project.
SW video will probably be uploaded within a month.
I learn it more and more.
Thank you for sharing all the videos, these are really helpful.
However, I observed that u used 125V rated fuses in line with motor output, whereas ur system is designed for 230 V.
Can u please explain this difference in the rating.
Thank u
My pleasure.
How so?
The JFC2410-1800FS is rated for 250 AC voltage according to the datasheet.
@@matanpazi3777Here it shows it
to be 125V.
www.lcsc.com/datasheet/lcsc_datasheet_2305151202_Shenzhen-JDT-Fuse-JFC2410-1800FS_C2994765.pdf
Thanks for your reply. Please see this datasheet in the link. It says 125V for 8A.
www.lcsc.com/datasheet/lcsc_datasheet_2305151202_Shenzhen-JDT-Fuse-JFC2410-1800FS_C2994765.pdf
@@matanpazi3777 Thanks for the reply. I am referring datasheet from LCSC here. It says so.
www.lcsc.com/datasheet/lcsc_datasheet_2305151202_Shenzhen-JDT-Fuse-JFC2410-1800FS_C2994765.pdf
Is it okay to not add lc filter in output? I read induction motor will easily hot and the winding vibrate if running with square wave, but idk with digital sine wave
Not sure for industrial applications.
I don't think adding an LC filter would reduce heating or vibrations though.
For simple applications I don't think it matters much.
Here's a link to an article that goes over the reasons for adding an LC filter:
ieeexplore.ieee.org/document/790930
In short:
1. High dv/dt may cause issues with long motor cables. A capacitor would help.
2. High frequency current ripple. An inductor would help.
3. High dv/dt leads to EMI. A capacitor would help.
My inputs:
1. Seems like the cable limit length stated in the article is quite generous. A limit of 5[m] of cable for 10,000 V/us seems pretty good.
2. Current ripple depends on the motor inductance and the switching frequency. I suspect this is a non issue for most standard applications (Switching frequencies in the kHz and relatively high inductances, higher than 1 mH).
3. Sure, that could help. There are indeed quite high ripples of voltage on the motor phases, smoothing them out could help.
@matanpazi3777 i see... Can this atmega328 increase carrier frequency of this setup? so adding lc fillter can be smaller
Very interesting. 😎 Thank you.
What ripple voltage did you allow after the rectifier and before the power stage?
Sir, As per the circuit diagram. We can supply the single phase input right?
Why didn't you try to use STM8S, it has 1 advanced control timer with 3 complementary PWM pairs?!
Thank you Mr. Pazi. This is one of the clearest explanations of VFD operation and design I have seen. I plan to share this with my engineers and technicians to improve their understanding of VFD theory and operation. As a side note, what CAD software do you use? Thanks again. Kind regards, John Stilwell
Wow, really appreciate it, thanks!
For the schematics and PCB layout I use EasyEDA, a very intuitive and free to use software.
@@matanpazi3777 Thanks for the info - IU will try it out. Cheers!
I also build my own vfd, yours was way much better. The difference is the motor driver ic, the relay and bleeding resistor, 1 phase to 3 phase capabilities, and i just use arduino uno because i was too lazy to build my own atmega 328 circuit. Nice job👍
Add: I do not see a step up transformer, your 2kw motor will only ouput around 1.5k without it.
Thanks!
And nice for creating your own VFD.
Can you please elaborate regarding the step up transformer?
@@matanpazi3777 no step up, most commercial vfd only use voltage doubler.
@@wiradharma7030 oh, but my VFD's output voltage is the motor's rated voltage, why would I need to step up the voltage?
@@matanpazi3777 did you know constant v/freq? Variable freqyency drive doesn't only control the frequency but the duty cycle. By controlling the duty cycle you control yhe average voltage.
If you want to build something that already exist, first learn the current model then make your improvement. I made commercial vfd because i could improve current design, if not i just simply buy one. I mean why the hassle if i could buy one for few $$?
@@wiradharma7030 Can you please give a link to source explaining the need for step-up transformers in normal operation VFDs?
Only found this:
mb-drive-services.com/vfd-output-transformers-where-do-we-need-them/
And the most relevant reason was this:
"VFD can certainly adjust the inverter voltage, but at lower voltages the power is reduced. If the customer wants the same power at each voltage level or relatively high power at lower voltages, the output transformer is beneficial."
This really isn't an issue for my application.
Kindly show wiring connections for single phase motor!
i wondered if you could use a FET to discharge the caps, after switch-off...or a tiny relay off the AC input, to switch on the bleed resistors...or an optoisolator, from the AC input, which pulls down the gate of the discharge FET (a bit of RC, too) until the AC goes away, at which point the FET gets biased on, and pulls down the capacitors to some lower voltage...
There are definitely better ways to implement the bleeding of the capacitors.
Not sure what relays/opto isolators can be fed by AC voltage, but there's probably some solution to this problem.
@@matanpazi3777 I figured out a circuit that could use an optocoupler, with a single diode from AS into a small R/C, so that the optocoupler holds down the gate of a FET, when AS is present, then allows the High Voltage DC to bias the FET on, as soon as the AC is gone for a second or two, which allows the FET to pull down the high voltage caps, through a fairly fat resistor, quickly, but without having the bleed resistor active when running... might be able to use this for soft start, too...
Anyway, just an idea
Hi sir, after rectifier ac 220v ac, it become 310v dc right, how to reduce?? Because my motor only acept 200v@@matanpazi3777
Hello Sir. When you increase the speed while keeping v/f constant and keep the load constant, does the input current increase?
Certo, as the output power increases (~torque*speed) so does the input power (V*I)
@@matanpazi3777 V*I*(Power Factor) for AC circuits.
As the frequency increases the impedance in the stator windings increases which lowers the power factor.
@@matanpazi3777 When I do a thought experiment I predict that the input current will remain constant as V/Hz increases, as long as the load remains the same.
@@matanpazi3777 If power factor correction was done on the motor, so a capacitor was added in the circuit to match the motors inductive reactance, the only impedance would be the resistance in the stator winding. I think the voltage needed to run the motor would be much less 🤷🏾♂️
Very interesting, informative video 💥
Thanks!
Beautiful Work!!!😀
Hi Matan very interesting project :))) Is the schematic of your project published anywhere ?
Hey, thanks :)
I'll upload it to my VFD Github repository (Will add a link to the description) in a week or so, on vacation ATM
Uploaded schematics to GitHub. See link in the description.
Hi,bro✋
I want make a vfd for single phase motor
Of course my English is not good and I didn't fully understand what you said in the video
Can you help me ?
Sir, how did you calculate for the bus capacitors. Your calculated value is 26665 micro farad but you use less than that on the capacitor bus. Can you clarify pls. Thanks
*2666[uF]
You are correct, I explain my decision here 5:58
Pretty much due to cost and space + hoping it'll work OK.
Awesome project to begin with! I am also designing my own VFD and use your videos as a reference design guide. However, I do have a question about the DC-bus capacitors. As shown in the video you used the following formula: Farad = Ampere*second/Volt. The formula itself is clear, but in the sidenotes of the schematics you used 8[A] as current for the capacitors. How did you determine this? Since it is DC I thought it could be done with I=P/U, but then I don't get the same value.
Check this video out by Schematix:
th-cam.com/video/CAYKno16weE/w-d-xo.html
Good work, thanks 👍!
Nice work by the way 👍
Excellent ❤
This is a really good video. Sad you have not gotten more views.
TH-cam's algorithm is not optimal. I have videos that I do not think are great but they have more views than others which explain more.
Thanks.
Hard to tell what will interest people.
your work is marvelous but i face some difficulty with your program which have (ISR (TIMER0_OVF_vect);
{ ) This error..could you help me if you have some free time.
Thanks :)
Look at the comments in lines 54, 55.
I assume that's the reason for the error you're getting.
Can you give me a complete wiring diagram please?
Hello sir, I want to talk to you can you provide anything where we can connect
Hi, it's me again 😁I know you are tired of me already but I need to know the best programing language to use when programing an Arduino, thanks in advance.
I wrote the code in the Arduino programming language which is pretty much C++.
You can find the code here:
github.com/MatanPazi/VFD
Thanks a lot!
You can't have 2 grounds ,,,, if you lost ground on the HV side for some reason the gap in the ground plane will be dangerous ....
thnks im from algeria
Can it run 0.75 kw motor?
Up to 2[kW]
2:03 who made that name plate with "RATTING"? LOL
Cod?
sir please send me the gerber file
It's quite dangerous. I'd rather only people who designed this themselves built it..
Good luck
Please provide me Arduino code