Study Of Matrix Converters Based On Sliding Mode Control Technique

Matrix converter is an AC-AC direct conversion circuit without DC part in the middle to store energy. It can realize efficient conversion of AC parameters such as voltage, current and frequency. As a matrix conversion circuit has a complex topology and has numerous switching elements, it is very difficult to work out a satisfying control strategy to achieve those requirements: unit input power factor, adjustable output frequency, adjustable output voltage amplitude, bidirectional power flow and all switches controlled coordinately.Sliding mode control is a discontinuous nonlinear control technique widely applied in variable structure control systems. It contains a time-varying discontinuous state feedback control law which makes controlled system switchovers among several system structures according to the instantaneous position of state variable in state space. As a result, the controlled system will follow the expected state trajectory. There are many advantages of sliding mode control: wide range of stability region, quick dynamic response, low noise sensitivity, strong robustness and easy to implement.Power electronic converters belong to variable structure system in essence. So it is natural to apply sliding mode control in power electronic converter systems. Design hysteresis sliding mode controller based on space vector modulation strategy for three-phase to three-phase matrix conversion circuit can reduce harmonic component in output voltage wave efficiently, make input and output waves approach expected forms and be robust with outside perturbation or inside parameters disturbance. Boost matrix conversion circuit has a three-phase inversion part with RHPZ peculiarity, that is, output wave has hysteresis with input wave. Fixed-frequency PWM sliding mode current controller is a reasonable choice to achieve output voltage step-up and step-down control and output wave tracking expected wave. Those two kinds of matrix conversion circuit systems have simulation to verify their control performance.