This was completely interesting to me and a refresh course regarding inverters. I think, a fresher in this field will also able to understand easily using your videos. Keep this good work. 👍
It may be interesting to point out the subtle difference between unipolar modulation described here and bipolar modulation. Also, are the phase voltages actually 5 level ? I understand that the pole voltages will be 2 level wrt dc link mid point, and the line voltages will be 2 or 3 level but I am not sure about the phase voltages.
I had initially added the point of unipolar and bipolar modulation - but I thought it might confuse people who are understanding it for the first time and since this was a very basic introduction - I left it out. I understand that most of the texts analyze inverters based on pole voltage with respect to dc-link mid-point but I never understood that idea. It was much easier for me to understand what the phase to neutral voltage will be as that is what the load would see. For the waveforms - check out this link - www.ijrer.org/ijrer/index.php/ijrer/article/download/771/pdf
Hi, after normalization with vdc, how are phase voltages a,b,c translated to pwm outputs? The normalized values can be in the range (-1...1) but the pwm must always be positive (0%-100%) mustn't it?
PWM is created by comparing it with a ramp. The ramp can be either from -1 to 1. Or you can normalize Vabc further between 0 to 1 and compare it with a ramp from 0 to 1.
Generally, in a motor control application - you have current sense only to measure the phase currents. And you can limit this current directly via FOC algorithm. However, there is no direct way to limit the DC current. You can "calculate" the DC current via formulas based on the phase current and modulation in the micro-controller and then try to put a limit on it this way. But this might not help you for the overcurrent protection as micro-controller may or may not be able to act fast. For protection, you can add DC current sensing as well but this is not generally done. It is generally the job of a BMS to do that. Other way to do it is - you put a limit on the torque speed curve of the motor based on some calculations so that the DC current will not exceed your limit in normal operation.
@@thesubcooledmind7910 it was mentioned that we operate motor controllers at a switching freq of 10k-20k, these range of frequencies could actually lead to audible noises right? why do we still prefer exactly those switching frequencies?
Its a trade-off. 10-20kHz does lie in the audible range. But higher the switching frequencies - more is the switching losses. So, you either prioritize the noise or the loss. And in some cases (low inductance motors) - even 20kHz is not sufficient. You will have to go higher than that for better control.
@@thesubcooledmind7910 how do we say pwm switching frequency vary with inductance... I mean high inductance , low pwm frequency and low inductance, high pwm frequency..... Is there any relationship with calculations
This was completely interesting to me and a refresh course regarding inverters. I think, a fresher in this field will also able to understand easily using your videos. Keep this good work. 👍
Super. Good. Thank you for teaching. Keep it up.
Hello! I look forward for your new videos!
I hope you will get back making them again soon!
Beautifully Explained!
So clear explanation 👍
I liked the way you explain. Step by step....
hey , am very very thankful for making such amazing videos in one way to understand... really helpful to me ...
Brilliant explanation!
Simply awesome....
You are amazing! Thanks
Very good video.
Good Content.
Hi, the voltages that are the output of the FOC algorithm, are these the required phase voltages or the pole voltages?
Can we have a common DC link to run both compressor and condenser model?
It may be interesting to point out the subtle difference between unipolar modulation described here and bipolar modulation. Also, are the phase voltages actually 5 level ? I understand that the pole voltages will be 2 level wrt dc link mid point, and the line voltages will be 2 or 3 level but I am not sure about the phase voltages.
I had initially added the point of unipolar and bipolar modulation - but I thought it might confuse people who are understanding it for the first time and since this was a very basic introduction - I left it out.
I understand that most of the texts analyze inverters based on pole voltage with respect to dc-link mid-point but I never understood that idea. It was much easier for me to understand what the phase to neutral voltage will be as that is what the load would see. For the waveforms - check out this link - www.ijrer.org/ijrer/index.php/ijrer/article/download/771/pdf
Hi, after normalization with vdc, how are phase voltages a,b,c translated to pwm outputs? The normalized values can be in the range (-1...1) but the pwm must always be positive (0%-100%) mustn't it?
PWM is created by comparing it with a ramp. The ramp can be either from -1 to 1. Or you can normalize Vabc further between 0 to 1 and compare it with a ramp from 0 to 1.
Hello sir,
I am able to limit phase currents in my foc for pmsm motor. Can you please guide me how can we include battery current limit?
Generally, in a motor control application - you have current sense only to measure the phase currents. And you can limit this current directly via FOC algorithm. However, there is no direct way to limit the DC current.
You can "calculate" the DC current via formulas based on the phase current and modulation in the micro-controller and then try to put a limit on it this way. But this might not help you for the overcurrent protection as micro-controller may or may not be able to act fast.
For protection, you can add DC current sensing as well but this is not generally done. It is generally the job of a BMS to do that.
Other way to do it is - you put a limit on the torque speed curve of the motor based on some calculations so that the DC current will not exceed your limit in normal operation.
Why do we not ignore 10kHz to 20 kHz which is in the audible range for motor control and use a higher or lower frequency?
Hi Joseph, Can you please elaborate your question? - I did not understand it well
@@thesubcooledmind7910 it was mentioned that we operate motor controllers at a switching freq of 10k-20k, these range of frequencies could actually lead to audible noises right? why do we still prefer exactly those switching frequencies?
Its a trade-off. 10-20kHz does lie in the audible range. But higher the switching frequencies - more is the switching losses. So, you either prioritize the noise or the loss.
And in some cases (low inductance motors) - even 20kHz is not sufficient. You will have to go higher than that for better control.
@@thesubcooledmind7910 how do we say pwm switching frequency vary with inductance... I mean high inductance , low pwm frequency and low inductance, high pwm frequency..... Is there any relationship with calculations
You can help in exchange for money