h bridge motor circuit on LT specie
There are several issues with your schematic some are listed below.
For U5 and U6 a voltage should be applied to pins Tcase and Tj equal to the temperature in Celsius (typically).
The A1 inverter should have a statement that indicates high and low voltage.
Things like back emf can be modeled with behavioral voltage source.
https://www.precisionmicrodrives.com/content/ab-025-using-spice-to-model-dc-motors/
To sweep parameters like resistor and inductor, add variable name to value and enclose in brackets so &quot;.step&quot; spice command can be used.
Consider the pmos and nmos selected as Vgs threshold and other parameters vary.
Below is incomplete example circuit which shows how to apply some of the syntax in LTspice