phase delay problem in MATLAB simulation for triggering the gate of mosfets

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engr_ams

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I have simulated a circuit consisting of three MOSFETs. I have to tigger the gate of MOSFETs with number of pulses (as a gate signals) generated by using carrier frequency, constant and a relational operator. BUT the problem is that i have to triger the gate of each MOSFET at a particular phase delay. THe first gate should tiger at time t=0, the second gate should tiger at time t= 33% of time period and the third gate should tirger at time t= 66% of time period.

Note: I have already simulate this issue with the help of pulse generator in open loop system but now i need to do so with the help of carrier frequency, constant and a relational operator.

I need to generate the pulses as shown in figu re (01)
 

Please send me some response. It is urgent for me
 

So you want to generate waveforms expressed as what, three vectors of bits (0=gate low, 1=gate high)?

I know some matlab, but have never used it for circuit simulation. Spice is so much easier....
 

Dear All,

Please check the attachment. I have sent you the pictures in which I have tried the method to shift the carrier frequency. But after trying that method I found that the wave forms are still starting from zero point. Although the wave forms must start from the particular time specified to them. You just try the same and see whether it is working or not... and tell me what should I do to shift the carrier frequency? The method I tried can be explained as under.
• For G1 the time should be from 0 to 50e-6 second
• For G2 the time should be from 16.5e-6 to 66.5e-6 second (D2 = 33% of Time Period)
• For G3 the time should be from 33e-6 to 83e-6 second (D3 = 66% of Time Period)
Many thanks for your interest in solving my problem. Awaiting your response
 

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You still haven't really described what form you want the waveforms in, or how to use them, but this code should help... you can play with the parameters to get the waveforms you want.

Code: 
dt=1e-6;    %time step
period=100e-6; %PWM period, must be an integer multiple of dt
time=[0:dt:period-dt]; %create time array ranging from 0 to period-dt
duty=0.5; %duty cycle of each waveform
Von=20; %value during on time
Voff=0; %value during off time
G1phase=0; %phase of G1 as percentage of one period
G2phase=1/3; %phase of G2
G3phase=2/3; %phase of G3


G0=zeros(1,round(period/dt));
G0(:)=Voff;
G0(1:round(period*duty/dt))=Von; %Go is now a prototype gate waveform with 0 phase
G1=circshift(G0,[0,round(period/dt*G1phase)]);  %create all three gate waveforms over one period
G2=circshift(G0,[0,round(period/dt*G2phase)]);
G3=circshift(G0,[0,round(period/dt*G3phase)]);
figure(1); plot(time,G1,time,G2,time,G3)  %plot them
axis([0 period Voff-1 Von+1])
 

Thank you very much for replying me. Yes at the gate of mosfet i need high/low pulses at 120 degrees apart. But to do so i want to shift the carrier frequency 120 degrees. Dear i do not want coding. I am working on m-files. I am simulating the power electronics circuit model. please check the attachement that i habe posted in my pervious post. Please check the problem of mine once again. THe problem can be explained as under:

Problem: I have simulated a circuit consisting of three MOSFETs. I have to trigger the gate of MOSFETs with number of pulses (as a gate signals) generated by using carrier frequency, constant and a relational operator. BUT the problem is that I have to trigger the gate of each MOSFET at a particular phase delay. The first gate should trigger at time t=0, the second gate should trigger at time t= 33% of time period and the third gate should trigger at time t= 66% of time period.


I need to generate the pulses as shown in figure (01)



Please check the attachment. I have sent you the pictures in which I have tried the method to shift the carrier frequency. But after trying that method I found that the wave forms are still starting from zero point. Although the wave forms must start from the particular time specified to them. You just try the same and see whether it is working or not... The method I tried can be explained as under.

· For G1 the time should be from 0 to 50e-6 second

· For G2 the time should be from 16.5e-6 to 66.5e-6 second (D2 = 33% of Time Period)

· For G3 the time should be from 33e-6 to 83e-6 second (D3 = 66% of Time Period)

If you know matlab simulation you might solve this issue.

Note: I have already simulate this issue with the help of pulse generator in open loop system but now I need to do so with the help of carrier frequency, constant and a relational operator.
 

engr_ams said:
Thank you very much for replying me. Yes at the gate of mosfet i need high/low pulses at 120 degrees apart. But to do so i want to shift the carrier frequency 120 degrees. Dear i do not want coding. I am working on m-files.
Click to expand...
Just copy that code into an m-file and run it...
I am simulating the power electronics circuit model. please check the attachement that i habe posted in my pervious post.
Click to expand...
That picture you posted is a window I'm not familiar with, but it just looks like a very, very tedious way to manually draw a waveform and then have it repeat itself. You still haven't defined what form you want the waveforms in, or how it is given to the simulation.
This description seems to contradict the figure you posted (D for each waveform is the same, now you're saying they're different...). The code I posted produces waveforms pretty much identical to the ones in the figure. It will plot them for you. You didn't actually try using the code, did you?
Note: I have already simulate this issue with the help of pulse generator in open loop system but now I need to do so with the help of carrier frequency, constant and a relational operator.
Click to expand...
What constant and relational operators are you talking about?
 

Dear I do not need the code. Please try to understand the problem. Ok i want to make it simple. Dear you can solve my this problem, "I want to simulate the three individual sawtooth wave form with 120 degrees phase shfit. how can I generate them?" Forget about the perivious discussion. I want to design the circuit model in simpower tool.

Please help me

thanks
 

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