In this paper, a nonlinear dynamic of permanent magnet synchronous machine scalar drive systems (PMSMSDS) is investigated thoroughly. At first, the mathematical dynamic model of the PMSMSDS is developed and formulated for open-and close-loop cases. Then, constant and periodic load torque are considered for the analysis of the system. The Jacobian matrix and the Poincaré mapping of the system are calculated analytically to study the feasibility of nonlinear phenomena at each point of equilibrium for constant and periodic loads, respectively. Computer simulation is used to obtain bifurcation diagram, time response, and phase plane of the state variables to investigate the complex behavior of the system by changing some parameters. It is shown that by changing the parameters of reference speed command, supply voltage range, and speed controller gain, the response of PMSMSDS state variables will be routed to limit cycle, bifurcated, and chaotic. Numerical analysis is provided to confirm the simulation results.