In order to reduce joule loss due to ripple current in multiphase current reversible chopper, an attempt was made to use electromagnetic coupling for an air-core reactor. The relationships among the amplitude of ripple current, duty factor and electromagnetic-coupling coefficient was deduced. It turned out that a specific optimal coefficient of electromagnetic coupling reduces current ripple both on each phase and on total combined. The hypothesis was verified experimentally with newly manufactured reactors, which achieved the optimal electromagnetic coefficient. The weight of the new reactor is 44% lighter than conventional three-phase reactors.