Aimed as 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 5kW prototype.