How do multiple coils make the output voltage of a practical DC generator more nearly constant?

In a practical direct-current (DC) generator, the output voltage of a single rotor coil is pulsating because the induced voltage is inherently alternating and reversed by the commutator. To make the output voltage more nearly constant, the rotor is designed with many coils symmetrically arranged in slots around the periphery.1

These coils are connected in series, and each junction is linked to a segment on a multi-bar commutator. By using multiple coils displaced around half the periphery, the total output voltage becomes the sum of the induced voltages from these individual coils. This configuration ensures that the magnitude of the output voltage is approximately constant, containing only a small ripple rather than the significant pulsations seen in a single-coil machine.1