I don't understand why the not logical operator is no more working

Question

Hello,

I would like to obtain two signals in S1 and S2 in opposition but unfortunately, the NOT door is no more working as soon I substrate the PWM to the sinus...

 

Could you help me?

 

Thank you

Answer 1

The root of the problem is your modulator implementation.  You should review relevant PLECS models such as the "Voltage Source Inverter" demo to understand how to build a modulator for this type of circuit.

A few comments:

1. You have the difference between a Sine Wave generator and Pulse Generator as the gate inputs to your MOSFETs.  From the MOSFET component help, "[The MOSFET] conducts a current from drain to source (or vice-versa) only if the gate signal is not zero.".  In this case your gate input is always a non-zero value.  Did you intend to compare the output of difference block with some threshold?
2. You are applying a NOT logic the signal that is never exactly zero. The behavior of the NOT block is to output "0" for any non-zero input.  Therefore the output of the NOT block is always zero.
3. There are several wires that overlap, making it difficult to see where signals are coming from / going to.  Cleaning this up would make your model to debug.  For example, some of your upper switches connect to the output of the difference block, while others connect to the pulse generator. Presumably this is an error.