V² controlled buck converter with ramp compensation is studied, its two border voltages are derived and one-dimensional discrete-time model is established, upon which the dynamical effect of V² control technique on stability control and mode shift of V² controlled buck converter with ramp compensation is studied by using the bifurcation diagram, Lyapunov exponent spectrum, and parameter space map. The research results verified by simulation and experimental measurements indicate that by utilizing ramp compensation, V² controlled buck converter can not only shift its operation mode from discontinuous conduction mode to continuous conduction mode, but also effectively stabilize its operation state from unstable subharmonic oscillation to stable periodic state.