Abstract：Under digital control，the inner current loop of the LC-type inverter is affected by the control delay，

which leads to the weakening of its active damping effect. Increasing the sampling control frequency can effectively

reduce the negative influence of digital control delay. Furthermore，in order to suppress the high order harmonic

disturbance caused by strongly nonlinear load，multiple resonant controllers are needed in the outer voltage loop.

For reducing the time complexity of the outer voltage loop and increasing the quantity of the controlled harmonics，an optimal sampling digital control strategy was proposed for the current and voltage double loop control of the LCtype inverter. Specifically，the inner current loop was set to the double sampling control frequency and the outer voltage loop was set to the single sampling control frequency. The optimal sampling digital control strategy enhance the suppression ability of nonlinear load disturbance and reduce the total harmonic distortion of the output voltage while maintaining the stability margin of the inner current loop. Finally，the feasibility and effectiveness of the proposed optimal sampling digital control strategy were verified by experiments.

      Key words：LC-type inverter；active damping；nonlinear loads；multiple resonant controllers；sampling control