Abstract: Soft startup is essential to the operation of the star-connected cascaded H-bridge (CHB) STATCOM. Conventional CHB STATCOM startup strategy suppresses inrush current by connecting current limiting resistors in series during uncontrolled rectification. However, due to the low DC-side capacitor voltage after the start-up phase, the CHB STATCOM will still generate a large inrush current when it enters the normal operating state. To eliminate this inrush current, a novel startup control is proposed to further charge the DC voltages after the uncontrolled rectifier process. After the uncontrolled rectification stage, the controllable boost stage is introduced, and the current limiting resistors continues to be connected in series, thereby further increasing the DC capacitor voltage. In the controllable boost stage, the relationship between modulation voltages and DC voltages is established, based on which a closed-loop control is proposed. The effectiveness of the proposed control is verified by the experimental results on a 400 V/5 kVar CHB STATCOM.