In this paper, the chaotic behavior and chaos control in a voltage mode controlled DC drive system are investigated. The dynamical behavior of the system changing from the fundamental state to chaotic regime is obtained by the variation of some parameters. Two kinds of delay feedback controllers are designed to induce and control chaos in the voltage-mode DC drive system that exhibits chaotic behavior under certain conditions. The proposed control scheme is able to suppress chaos on the voltage mode controlled DC drive system operating in continuous conduction mode. With variation of controller parameters, the transition of dynamical behavior in the system has been demonstrated from different possible states to regular state, which may be named as period-1 operation. Unlike the traditional delay feedback control method, not only the feedback gain parameter K but also the delay parameter τ is used as variable parameters of the controller. Moreover, the genetic algorithm is used to simultaneously optimize both the feedback gain parameter K and delay parameter τ to improve the effectiveness of the controller. Numerical results show that the proposed method can control unstable periodic orbits and suppress chaos in the system, and also, optimized controller parameters provide fast response for transition from chaotic operation to normal operation.

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This paper discusses chaos control and synchronization of the four dimensional Lorenz-Stenflo system based on passive control technique. Using passive theory, chaos control and synchronization of a four dimensional Lorenz-Stenflo chaotic system are realized with one input. The designed controllers ensure the stability of the controlled system and error dynamical system between two identical Lorenz-Stenflo systems. Also, the controllers ensure that the controlled system and error dynamical system converge to zero equilibrium. Numerical simulations show that the proposed method is effective for the Lorenz-Stenflo system.

Purpose The purpose of this paper is to develop new four-dimensional (4D) hyperchaotic system by adding another state variable and linear controller to three-dimensional T chaotic dynamical systems. Its dynamical analyses, circuit experiment, control and synchronization applications are presented. Design/methodology/approach A new 4D hyperchaotic attractor is achieved through a simulation, circuit experiment and mathematical analysis by obtaining the Lyapunov exponent spectrum, equilibrium, bifurcation, Poincaré maps and power spectrum. Moreover, hardware experimental measurements are performed and obtained results well validate the numerical simulations. Also, the passive control method is presented to make the new 4D hyperchaotic system stable at the zero equilibrium and synchronize the two identical new 4D hyperchaotic system with different initial conditions. Findings The passive controllers can stabilize the new 4D chaotic system around equilibrium point and provide the synchronization of new 4D chaotic systems with different initial conditions. The findings from Matlab simulations, circuit design simulations in computer and physical circuit experiment are consistent with each other in terms of comparison. Originality/value The 4D hyperchaotic system is presented, and dynamical analysis and numerical simulation of the new hyperchaotic system were firstly carried out. The circuit of new 4D hyperchaotic system is realized, and control and synchronization applications are performed.

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