Abstract: [Objective] Aiming at the problem of non-dominant pole harmonics generated by double rotor asynchronous motors with fractional-slot concentrated winding (FSCW) structure, this study aims at proposing an efficient harmonic suppression method to reduce the harmonic-induced efficiency loss of the motor and to improve the operational stability and overall performance of the motor. [Methods] Firstly, based on the phase band division and arrangement of the FSCW, the distribution coefficients of even-slot and odd-slot were derived by the definition method and the harmonic synthesis method, respectively, and the peaks and valleys of the harmonic magnetic potentials at the axial position under the different pole-pair numbers were clarified. Secondly, combined with the theoretical analysis of the distribution coefficients, two compensation winding configurations were proposed: the direct compensation method by adjusting the phase relationship between the compensation windings and the main winding, so that the peaks and valleys of the magnetic potentials of the harmonics to be suppressed were superimposed with the main harmonics in reverse direction; and the phase-shifting compensation method by the phase-shifting design of multiple sets of compensation windings, so as to achieve the active offset of the specific subharmonics. In addition, a three-dimensional motor model based on finite element simulation was established to verify the effectiveness of the compensation method. [Results] The theoretical calculation and finite element simulation verified that the proposed methods can effectively suppress specific harmonic components and enhance the operating harmonics in small amounts, which improves the operation stability and efficiency of the motor. [Conclusion] This study shows that the direct compensation method and the phase-shift compensation method can be flexibly applied to the suppression of non-dominant pole harmonics based on the characteristics of harmonic peaks and valleys distribution. The former is suitable for the scenario where the peaks and valleys of the proposed harmonic suppression and the operating harmonics are reversed, while the latter solves the harmonic cancellation problem when the peaks and valleys of the two are in the same direction. Both methods can moderately enhance the working harmonics while suppressing the target harmonics, providing a theoretical basis and technical support for high-precision motor design and harmonic management.