Unconstant Frequency Dual Integrator Control and its Application to Switch Converters

In this paper, a new large-signal nonlinear control technique, called unconstant frequency dual integrator control - UFDI control, is proposed to control the duty-ratio d_k and cycle T_k of a switch such that in each integration cycle T_k the impulse value of a switched output variable is exactly equal to or proportional to the control reference in the steady-state or in a transient. UFDI control rejects power source perturbations within one integration cycle T_k; the switched output variable exactly follows the dynamic reference in one integration cycle; and there is no steady-state error nor dynamic error between the switched output variable and the reference in one integration cycle. UFDI control appears a very good tracking performance. Simulations with UFDI control of a single-phase bridge inverter have demonstrated the new control method and verified the theoretical predictions. This new control method is general and applicable to all types of pulse-width-modulated, or converters for either voltage or current control in continuous or discontinuous conduction mode