Double loop control of buck-boost converters for wide range of load resistance and reference voltage

A double-loop control mechanism is developed for an inverting buck-boost converter. The robust converter is capable of operating in a wide range of reference voltage and load resistance with unmodelled parameters. The cause of the non-minimum phase behaviour is analysed. The boundary layer width of the output voltage in sliding mode is found to be dependent on the circuit and control parameters. The speeds of the inner and outer loop are quantitatively determined and compared. The transient responses of the circuit are forecastable. The controller is validated on a simulation circuit.