General Turns Ratio Design Method for Passive Pulse <i>x</i>-Multiplication Circuits of Parallel-Connected Multipulse Rectifiers

A general turns ratio design method is proposed to simplify the complex and non-general calculation process of the auxiliary transformer optimal turns ratio in parallel-connected multipulse rectifiers (MPRs). Based on the pulse multiplication mechanism of passive pulse <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>-multiplication circuits (PPXC), the condition for minimum output voltage ripple is obtained, and a novel PP5C is proposed. Based on the condition, the general expression for auxiliary transformer optimal turns ratio of PPXC (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> = 2, 3, 4, 5) is derived. This method can obtain the optimal turns ratio only through simple calculation. The test results show that when employing the optimal turns ratio calculated by the proposed method, the output voltage ripple and input current total harmonic distortion (THD) of MPRs both reach the minimum. The proposed design method applies to all topologies (including various main circuits with PPXC), and the novel PP5C shows superior harmonic suppression ability.