Aimed at the issues of large filtering inductance on the DC side of traditional midpoint-clamped full-bridge SWISS rectifiers, including the high current harmonics on the input side and low power density, an improved neutral-point-clamped full-bridge SWISS rectifier without DC-side filtering inductance is presented. And a HLHL (High-Low-High-Low) modulation strategy is proposed to achieve the soft switching of high-frequency switches in the rectifier. Detailed analysis was conducted on the operation modes of the high-frequency switches. And the optimization of the isolation transformer is studied. The constraint conditions of the transformer design are analyzed and a standardized design method for the transformer parameters is developed. The feasibility of the rectifier circuit topology and modulation strategy are validated by the experimental results with a 5 kW prototype.