Abstract
To reduce the loss due to the ripple current in a multiphase current-reversible chopper, we attempt electromagnetic coupling of an air-core reactor. We deduce the relationships among the amplitude of the ripple current, the duty factor, and the electromagnetic coupling coefficient. We estimate the effect of the electromagnetic coupling when we design a train's energy storage system by using the results of the deduction. We manufacture reactors whose electromagnetic coupling coefficients are 0.93 and 0.60. The manufactured reactors employ a new winding structure that provides an optimal electromagnetic coupling coefficient. The mass of the former type of reactor increases by 4.4%, and that of the latter type of reactor decreases by 17%. Finally, we test the new reactors. When the chopper employs the former type of reactor and operates with equal-phase switching and cumulative coupling, the loss due to the ripple current decreases to 11%. When the chopper employs the latter type of reactor and operates with shift-phase switching and differential coupling, the loss decreases to 31%. From the test, it is found that the deduced relationships agree with the measured values.
