Hyperchaotic Lorenz system

This paper presents a four-dimensional hyperchaotic Lorenz system, obtained by adding a nonlinear controller to Lorenz chaotic system. The hyperchaotic Lorenz system is studied by bifurcation diagram, Lyapunov exponent spectrum and phase diagram. Numerical simulations show that the new system's behavior can be convergent, divergent, periodic, chaotic and hyperchaotic as the parameter varies.