Aiming at such problems as poor dynamic and steady-state performance, and non-ideal anti-interference performance when the traditional sliding mode control is applied in Boost converter, a non-singular terminal sliding mode control (NTSMC) strategy based on finite time convergence is presented in this paper. Taking the inductor's current and output voltage as the state variables of the system, the average state model of Boost converter under continuous conduction mode (CCM) is established, and the differential equations of the inductor's current and output voltage are obtained. According to the above differential equation, a finite-time convergent observer (FCO) is designed to estimate the load resistance and input voltage. By combining these estimated values with the NTSMC method, a novel non-singular terminal sliding surface function and controller are designed, which improves the dynamic, steady-state performance and anti-interference performance of the system. The stability of the system is analyzed according to the Lyapunov stability theory. The simulation and experimental results show that, compared with the traditional sliding mode control, the control algorithm proposed in this paper has stronger anti-interference ability.

In this paper, a novel method for shock-free soft-start is proposed. The novel method can realize the aim of no-overshoot and inrush of current during the entire soft-start process, thus the start process is safe, stable, and reliable. When the uncontrolled rectification stage ends, a sinusoidal signal synchronized with the grid voltage is generated through dq coordinate transformation and D-axis orientation, then the signal is transmitted to the three-phase inverter bridge. The AC voltage output of the inverter bridge is superimposed on both ends of the soft-start resistor along with the grid. The open-loop control method is adopted to gradually reduce the modulation ratio of the sinusoidal PWM wave until the capacitor voltage on the DC side reaches the rated voltage value, then the soft-start resistor is removed, which means the shock-free soft-start process is completed. Experimental results prove the effectiveness and feasibility of the control strategy proposed in this paper.

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