Why did Nicolaus Copernicus retain epicycles in his Sun-centered model?

Nicolaus Copernicus retained epicycles in his heliocentric model primarily because of his commitment to the philosophical principle that planetary motion must be composed of uniform circular motions.12

While Copernicus successfully placed the Sun at the center of the solar system, he still operated under the ancient assumption that celestial bodies move in perfect circles at constant speeds. Because the actual orbits of the planets are not circular, he was forced to include a series of epicycles—small circles revolving on larger ones—to match observed planetary positions with his theoretical model. In this context, these epicycles functioned similarly to terms in a Fourier series, serving as mathematical tools to approximate noncircular motion using combinations of uniform circular paths.13

Additionally, Copernicus objected to the Ptolemaic system for its use of the equant, which he felt violated the requirement for uniform motion. By using epicycles, he sought to achieve the same predictive accuracy as his predecessors while adhering to his own strict standards for uniform circular motion.432