The research for the stability of SPWM inverter affected by digital control

This paper focused on for the stability of SPWM inverter affected by digital control. The stability of analog control inverter system, discrete system with no-step-delay control and discrete system with one-step-delay control are analyzed respectively so as to determine the relation of the inverter´s sampling period vs. controller parameters with critical stability. Then the essential reason was analyzed why the stability of digital control inverter was degraded compared with analog control inverter even if the sample frequency is ten times greater than the closed-loop bandwidth. The conclusion with realistic instructive significance had been drown clearly that one-step-delay control makes stable range of controller parameter larger than no-step-delay control in some low sample frequency.