Japan Proton Accelerator Research Complex (J-PARC) aims at achieving a MW-class proton accelerator facility. One of the promising solutions for increasing the beam power is to fasten the repetition rate of Main Ring (MR) from current rating of 2.5 sec to 1 sec in the future. However, in this scheme, the increase of output voltage and the power variation on the electric system are serious concerns for main magnets. At the same time, current ripple reduction is required in order to increase the beam quality for the hadron experiments. We have been developing power supplies which have potentials to solve these problems and plan to replace the current power supplies with them.