Abstract: In order to improve the reliability of LCL-filtered grid-connected three-phase inverter when using a

sliding mode controller，a novel sliding mode control strategy with less sensors in the abc natural frame was designed.Firstly，the sliding surface functions of phase a and phase b in the abc natural frame were established，and then the sliding surface function of phase c was derived directly from them，which eliminates the need to detect the capacitor voltage and grid current of phase c，and reduces the number for sensors. At the same time，the capacitor reference voltage was generated by the proportional resonant controller，which can achieve zero steady-state error of the gridconnected current. Steady state and dynamic experiments were carried out with a grid connected three-phase inverter with a rated power of 10 kW，as well as the tests under grid imbalance and disturbance. The experimental results verified the effectiveness of the novel sliding mode control strategy with reduced number of sensors in the abc natural frame.

       Key words: grid-connected inverter；damping；proportional resonant control；sliding mode control