On Fri, May 9, 2025 at 05:43 PM, <Bouzid.wis@...> wrote:
Upper submodule: When the upper MOSFETs (e.g. S1) are conducting, the positive voltage of the upper capacitor is applied to the output, while the lower MOSFETs (e.g. S2) close the current path or bypass the upper branch.
I am sorry, but that description does not explain to me how it works, not in a way I can understand.? There are many things interacting here, including the fact that the source of pull-up current is through a resistor and an inductor, it is not a voltage source, and there is a capacitor in the current path when M1 switches ON.? Plus there is the reactive input impedance of the output filter.? M1 does not directly switch a positive voltage to the unfiltered output, which I think was what you think would happen.? For that to happen, R1 and L2 and C1 should not be there.
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Do you understand how it is really supposed to work?
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the two submodules must be symmetrical to each other, can you show me where the problem is.
What is the problem?? Is there a problem?
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Are the two submodules not symmetrical to each other?
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I see a sine wave at the filtered output, and it looks like a reasonable replica of the input sine wave.? That suggests that maybe the circuit works.
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yes I have looked at the file, but the output voltage should not look like this.
please have a look at the picture i uploaded in the temp named output.
I think you are mistaken if you think the unfiltered output should alternate between +20 V, 0 V, and -20 V.? I do not see a way for your first circuit to make the unfiltered voltage do that.
i also uploaded another simulation circuit (named M2C single phase SPWM11) where i simulated the circuit with only one carrier signal, but the unfiltered voltage is not stepped with clear voltage levels: +20V, 0V, -20V, but only +20V, -20V. Probably because I only used one carrier signal. But the current at the load and the filtered voltage look good.
How would the unfiltered output voltage go to 0 V?? Is there anything in your circuit that can drive the unfiltered output to 0 V?? I do not see one.
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But I hope you realize I am unfamiliar with this circuit, and that does not help me explain what happens or does not happen.? I am "in the blind".
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Andy
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