Sliding mode control based buck-boost bidirectional converter to drive piezoelectric loads

The present work deals with the development of a converter to drive piezoelectric actuators to be used in automotive and aerospace applications and work under mechanical frequencies up to 2 kHz with rectangular, triangular and sinusoidal reference signals. In order to maximize the field in the piezoelectric ceramic important voltages (up to 2,000 V) are needed. To fulfill such requirements with a limited input voltage a bidirectional buck-boost converter is proposed. Such a converter shows voltage reduction and elevation capability. This advantage overcomes its intrinsic control non-linearity and the drawbacks involved. The converter is controlled by means of a sliding mode control strategy based on two different linked sliding surfaces which are defined as the energy error of the converter for charging and discharging operation modes, so that each surface controls one of the two switches employed. The state-space evolution of the voltage and current is investigated in order to analyze the converter limitations. The proposed converter and control strategy have been simulated and have proved to be appropriate and robust for different voltage references and values of the equivalent capacitance CP.