Nonlinear Variable Structure Control of CCM Buck Switching Converter

Aiming at the problems of the traditional sliding mode controllers for DC-DC switching Converters, a fixed frequency PWM sliding-mode controller for DC-DC switching Converters is proposed by employing the nonlinear differential geometry theory and impulse integral model in this paper. Design of this controller combines the nonlinear differential geometry theory with the variable structure controlling theory, which overcomes disadvantage of hysteresis modulation, carries out fixed frequency control, and reduces the design complexity of the existing fixed-frequency sliding-mode controllers. Static and dynamic performance of the proposed nonlinear variable structure controller for CCM buck type switching converter is simulated. The responses of system with the proposed controller are compared with PI control scheme. Simulation results show that the controller is superior to the customer PI control method in steady-state error, dynamic response performance and robustness.