Recently, the permanent magnet vernier machine (PMVM) is studied extensively because of its merits such as the high torque density. Similar to the magnetic gears, the PMVM operates on the principle of flux modulation. However, there is a distinct difference in between the two as unlike the magnetic gear, in case of PMVM, the winding MMF harmonics rotates with different speed as that of the fundamental. As a result, these harmonics are capable of making a working magnetic field by interacting with different permeance harmonics. Therefore, this paper aims to provide an analytical explanation of this whole process, which is helpful to understand the effect of the flux modulation on the output torque. Furthermore, using the analytical formulation, this work finds the optimal geometric parameters which maximize the working magnetic field and hence the torque. A detailed analysis of the PMVM with the doubly salient structure is studied and the performance is analyzed using the finite element method (FEM) and the experimental setup. The FEM and experimental results verify the maximum torque production by using the optimal geometric parameters in the PMVM modeling, obtained using the analytical formulation.