A high-pulse conversion technique for high voltage and high power applications such as HVDC transmission system is proposed. The proposed technique, based on the DC current reinjection, further decreases the number of components in the auxiliary circuit to achieve the same pulse number. An optimised control strategy over the whole range of phase delay angle is provided along with sophisticated input current and output voltage analysis. With the pulse multiplication strategy the proposed schemes demonstrate 24-pulse, 36-pulse and 48-pulse characteristics both in the input current and in the output voltage. Experimental results from a 3 kVA laboratory prototype verify the proposed concept.