Digital Natural Sampling SPWM based on Inverse Operator Method

It is difficult to apply natural-sampling SPWM (NSPWM) method in digital real-time control because its switch-points are expressed in transcendental equations. In this paper, the inverse operator method was used to solve the NSPWM switch-points. Then the switch-points can be expressed in a series of Adomian polynomials. The precision of NSPWM switch-points is depended on how many Adomian polynomial terms are used in the calculation. More polynomial terms are included in the switch-point expression, higher precision can be obtained. Therefore, by selecting a proper number of Adomian polynomial terms, the proposed analytical expression can be regarded as the real solution of NSPWM switch-point, which is feasible to realize the inverter NSPWM control by digital implementation.