DC TO AC inverter

you can use the built in PWM generator to generate signals for a full-bridge configuration. It has a 4 pulse configuration is you look at the documentation: https://www.mathworks.com/help/physmod/sps/powersys/ref/pwmgenerator2level.html

For your model, delete the simscape PWM generator (Controlled PWM Voltage 1), it is meant to be connected to a gate driver block when using non-linear transistor models. You are using ideal (piecewise linear) transistor models and don't need it. You can just attatch a standard controlled voltage source and put any voltage you want on the dc bus of the circuit that way.

This is a good document showing the explicit modelling of a 3 phase inverter, so it is very similar to the full-bridge circuit that you are trying to model (3 legs instead of 2). https://www.mathworks.com/help/physmod/sps/ug/three-phase-high-power-converter-design-and-analysis-workflow.html

Also, have you taken the free onramp trainings? Here is one for Simscape. There is also a Simulink one and one for circuits: https://www.mathworks.com/learn/tutorials/simscape-onramp.html

Regards,

Joel