Nowadays, High-Temperature Superconducting (HTS) electric machines are widely used in industry due to the unique properties of HTS materials. Besides, the effect of space harmonics is a very serious challenge that must be considered in the design of HTS electric machines. In this paper, a high-temperature superconductor- induction/synchronous machine (HTS-ISM) with 20 kW power is provided to reduce air-gap flux density distortion. For a precise comparison, the main parameters of the machine are studied under the same conditions such as frequency, core material, pole number, critical current density, and voltage by the Finite Element Method. In addition to winding arrangement, the geometrical parameters of the machine also affect the space harmonics, so by modifying each of these parameters, the amount of Total Harmonic Distortion (THD) is obtained in each case. In the proposed model, the amount of THD is significantly reduced, which makes the air-gap flux density more sinusoidal. Torque ripple has also been improved in the proposed machine.