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I am doing a simulation on LTSpice of a three level ANPC. The ground is connected to the neutral point (i.e in the middle point of the DC input) and the gate drivers are isolated by using a DC DC converter (so the voltage is floating). The thing is that I need to gate the transistors and I have the modulation done with signals that go from 0 to 5V.

I did this signals by using BV sources connected to the common ground: one carrier that goes from 0 to 0.5, another that goes from 0.5 V to 1V and the modulating sine in the middle.

How can I impose the PWM to the input of the gate driver? How should I shift the signals to the source level of the transistors?

Thank you in advance!

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    \$\begingroup\$ I normally cheat with the e-function. Set gain to 1 and it will provide indefinite speed and isolation. \$\endgroup\$ – winny Jun 17 '18 at 21:58
  • \$\begingroup\$ See this answer for a possible solution to your case, and to get an idea on a simplified way to simulate what you want, faster. \$\endgroup\$ – a concerned citizen Jun 18 '18 at 6:10
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With a bv source you can use math equations, so just for simulations take if you want to stimulate a combination of signals you could do something like this:

bv=V(pwm)*V(gatesignal)+V(whatever)

Where pwm, gatesignal and whatever are net names. If you want to reference a current you can use I(netname)

If you want to physically realize this system you'll have to do it with analog multipliers and summing op amps

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