AC PWM control in LTspice with 2 grounds

[reyntjensm]

Hello everyone,

I'm trying to make a AC PWM control. I've already got it working in LTspice but as soon as i start to use an optocoupler LTspice does strange things. I've been searching for the solution for several hours but i can't make it to work. It surely has to do something with the GND/COM nets but i don't know what i'm doing wrong. I hope somebody can help me further with this. Thank you all!

" alt="" class="bbc_img" />