help me in LTSpice

Alec_t

Joined Sep 17, 2013
14,409
Welcome to AAC!
Many members here use LTspice.
Have you studied the LTspice 'Help' ?
What feature do you want help with?
 

Thread Starter

Homa.zarei

Joined May 28, 2024
9
Welcome to AAC!
Many members here use LTspice.
Have you studied the LTspice 'Help' ?
What feature do you want help with?
Hello ,
Many thanks for your attention, my background is chemistry, I have a course regarding micro grids, which one of the modules is related to Lt spice. I studied hard again and again, and just have 4 hours remaining to answer the assignment otherwise I will fail. Can you help me in sloving it ?
 

Thread Starter

Homa.zarei

Joined May 28, 2024
9
Lots of users here. Ask your question.
Hello ,
Many thanks for your attention, my background is chemistry, I have a course regarding micro grids, which one of the modules is related to Lt spice. I studied hard again and again, and just have 4 hours remaining to answer the assignment otherwise I will fail. Can you help me in sloving it ?
 

djsfantasi

Joined Apr 11, 2010
9,188
Hello ,
Many thanks for your attention, my background is chemistry, I have a course regarding micro grids, which one of the modules is related to Lt spice. I studied hard again and again, and just have 4 hours remaining to answer the assignment otherwise I will fail. Can you help me in sloving it ?
Ok, no more wasted time. You need to tell us everything you can about your problem and its relationship to LTSpice!
  • Is your problem a circuit’s LTSpice simulation not working? Send us the circuit.
  • You need help building a circuit in LTSpice? Send us the schematic and screenshot of how far you’ve gotten.
  • If there are any errors in LTSpice, screenshot them.
  • If you don’t have a circuit? Send us the requirements.
 

Thread Starter

Homa.zarei

Joined May 28, 2024
9
LTspice: (unaltered file) What is the switching frequency being used? Prepare a plot if simulation voltage traces which shows how the switching frequency (1/Ts) is set. (Double click on the trace title of interest an move the cursors to get the measurement). Upload your answer as an image or pdf.

LTspice: (Unaltered file) In sine PWM, the ratio of sine wave maximum to triangular wave maximum is known as the modulation index (ma) or ratio. What value do you observe? Is this over or under modulation? What is the function of the modulation index ma?


LTspice: (unaltered file) What is the fundamental output frequency of the converter? Upload a plot of waveforms showing the output of the converter, using cursors (double click on the trace title) to identify a period of the converter's fundamental output.

LTspice: Change the switching (Carrier) frequency (PULSE period) in order to get a modulation frequency ratio to the nearest odd integer multiple of three. What switching frequency did you choose and why?
Comment on your new current waveform results. (Use the partner file upload question, attach a plot of the current waveforms and carrier waveform to show that the modulation frequency has been correctly set)
Write down how you set it in LTspice (PULSE command)?

LTspice: (For power in a component, press Alt when clicking on a component). Chose one of the three grid phase voltages. Why is the power flow in/out of the grid phase voltage at twice the frequency of the grid?
What does the DC offset value mean.
If you add all three powers associated with the three grid voltages, what do you notice?

Unaltered LTspice: Consider the connection between the inverter and the 'grid'. Write down the grid current magnitudes and total power in the grid (Hover over the grid sources A, B and C and press alt to get each power).
Set the angle theta until the inverter voltages and grid voltages are approximately 'in- phase'. What happens to the current and power? Write down your new values. (Note that theta is not brilliantly defined in this simulation, as I used sine voltage sources for the references, and their start angle is not clearly defined. In a real system, theta=0 would be found from measurement as it is here! )
How else may the current be controlled?


LTspice: Starting with an unaltered file, reverse the power flow between the grid and the inverter and state where the power is now going. Explain how you achieved reversing the power flow. Comment on the resulting grid current waveforms.

LTspice or otherwise: (unaltered file) Decrease the modulation index (ma) in one phase. What happens to the inverter output voltage and current of that phase?
Explain very briefly what happens to the power in the grid system.

File upload for the modulation frequency ration as an odd integer multiple of three LTspice Question
 

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Thread Starter

Homa.zarei

Joined May 28, 2024
9
Ok, no more wasted time. You need to tell us everything you can about your problem and its relationship to LTSpice!
  • Is your problem a circuit’s LTSpice simulation not working? Send us the circuit.
  • You need help building a circuit in LTSpice? Send us the schematic and screenshot of how far you’ve gotten.
  • If there are any errors in LTSpice, screenshot them.
  • If you don’t have a circuit? Send us the requirements.
Dear ,
Sorry that my questions are too long. This is the last chance that I have . Around 2 weeks I tried to solve the assignment.
 

WBahn

Joined Mar 31, 2012
30,303
We will NOT do your work for you -- and if this is an exam, it is unlikely that you are allowed to get ANY external assistance. But, ignoring that, you need to show YOUR best attempt to solve YOUR assignment. We are then in a position to point out where you might be going wrong and offer hints and suggestions to move you in the right direction.
 

Thread Starter

Homa.zarei

Joined May 28, 2024
9
We will NOT do your work for you -- and if this is an exam, it is unlikely that you are allowed to get ANY external assistance. But, ignoring that, you need to show YOUR best attempt to solve YOUR assignment. We are then in a position to point out where you might be going wrong and offer hints and suggestions to move you in the right direction.
Kindly I didn’t want you to do my homework!!!!!!!!!! I am a responsible student, and this exam like all of those exams before was important for me!!!!!!! My experience is in chemistry and this course is completely different from others, last night I came here for the first time for help!!!!!!! I was too unfamiliar with this course even to recognize which questions were simple and which were not!!!
Anyway gooooooooddd luck !!!!!
 

Thread Starter

Homa.zarei

Joined May 28, 2024
9
We will NOT do your work for you -- and if this is an exam, it is unlikely that you are allowed to get ANY external assistance. But, ignoring that, you need to show YOUR best attempt to solve YOUR assignment. We are then in a position to point out where you might be going wrong and offer hints and suggestions to move you in the right direction.
Your answering bothered me and of course I learned how can help a person in a bad situation!!!
 
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