I'm trying to simulate a 3-phase inverter for BLDC(PMSM) in LTSpice. The problem is that drain current is way too high and also phase voltage isn't right.
If I put one source(48V) I get spikes as drain current(green) instead of rectangle signal, blue signal is drain-source voltage:
Here are phase currents:
If I put two sources then I get rectangle but is way too high(3.5kA):
Here are phase currents:
Here are phase to phase voltage(blue) and voltage on one phase(green):
To get SPWM I compare sine wave and triangle wave, for other two phases I change Phi to 120 and 240. Also I have dead time circuit and that works fine.
It works the same even with or without back-EMF. I tried changing Rm and Lm parameters but nothing changes.Rm=1 Ohm, Lm=0.5 mH. I tried adding ground but it doesnt work either.
UPDATE1: Thanks to everyone.
I realized that I need to bootstrap MOSFETs. Now I'm trying to make driver with bootstrap capacitor and pnp and npn as seen in some datasheets/forums but it doesn't work for 3 phases(uploaded new pictures). I don't know what's wrong.
Tried with/without ground but it doesn't help.
Is it better to just include gate driver model?
I just need it for simulation to measure currents, voltages etc.
Best Answer
Here is a basic simulation of a inverter and the U15II kv80 T-motor:
The torque is not modelled so the current is the maximum possible. This does not affect the simulation. The only input of the simulation is the duty. Here is the waveform of the phase A:
The netlist: