Hello,
The following 2 links will give you clear idea about phasor mode of simulation
2 . https://in.mathworks.com/help/physmod/sps/powersys/ug/introducing-the-phasor-simulation-method.html
Simply, if you are interested only in the changes in magnitude and phase of all voltages and currents when switches are closed or opened, you do not need to solve all differential equations (state-space model) resulting from the interaction of R, L, and C elements. You can instead solve a much simpler set of algebraic equations relating the voltage and current phasors. This is what the phasor solution method does.
