Multiphase induction motors are popular for electric ship propulsion systems because of their superior fault‐tolerant capability. In this paper, a torque regulation method for multiphase induction motors with symmetrical fault is investigated under the precondition of constant current amplitude. On the basis of parameter recalculation, the relationships between the torque, input voltage magnitude, and frequency are analyzed by using the equivalent circuit. The maximum torque and the corresponding input voltage magnitude and frequency are predicted. Finally, the developed torque regulation method is validated by experimental test on a 45‐kW prototype 15‐phase induction machine under a symmetrical 5‐phase open‐circuit condition. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.