Cascade PID control of buck-boost-type DC/DC power converters

In order to improve the control performance of DC/DC buck-boost converters, the control problem of the output voltage is transformed to the inductor current control, and a cascade controller is presented. The outer loop of the cascade controller adopts a conventional PI control algorithm and takes the capacitor voltage as the controlled variable; the inner one adopts a particular PI control algorithm and takes the inductor current as the controlled variable. This kind of controller not only can make the controlled system achieve excellent dynamic characteristics, but also has strong robustness to the variations of system parameters, such as inductance, capacitance, input voltage, load resistance. Simulation results of a certain DC/DC buck-boost power converter indicate that the controller presented above is feasible.