1. Matrix Converter Circuit Fig.1 GPU layout using a Matrix converter REPETITIVE CONTROL FOR A FOUR LEG MATRIX CONVERTER Wesam M. Rohouma, Saul Lopez Arevalo, Pericle Zanchetta, Patrick W Wheeler Electrical Systems and Optics Research Division University Park, NG7 2RD, United Kingdom eexwr1@nottingham.ac.uk Abstract: The technology of direct AC/AC power conversion (Matrix converters) is gaining increasing interest in the scientific community, particularly for aerospace applications. In this poster the simulation of a digital repetitive control system is proposed to regulate the output voltage of a four-leg matrix converter using an ABC reference frame. The application is a Ground Power Supply unit (GPU) for aircraft servicing where a filtered, stable output voltage is required. The proposed control structure reduces the tracking error between the output and reference as well as increasing the stability of the converter under balanced and unbalanced load conditions. SABER and MATLAB simulation packages are used to verify the operation of the proposed controller. Abstract: The technology of direct AC/AC power conversion (Matrix converters) is gaining increasing interest in the scientific community, particularly for aerospace applications. In this poster the simulation of a digital repetitive control system is proposed to regulate the output voltage of a four-leg matrix converter using an ABC reference frame. The application is a Ground Power Supply unit (GPU) for aircraft servicing where a filtered, stable output voltage is required. The proposed control structure reduces the tracking error between the output and reference as well as increasing the stability of the converter under balanced and unbalanced load conditions. SABER and MATLAB simulation packages are used to verify the operation of the proposed controller. Introduction: o A matrix converter (MC) is a direct power converter used to convert AC supply voltages into variable magnitude and frequency output voltages. o Ground power units (GPU) are designed to provide quality supply of 115V-200V, three phase, 400Hz to aircrafts. The standard ratings are from 40 kVA to 120kVA, fig.1. o Using MC in a GPU has many advantages over rectifier/inverter systems such as a sinusoidal input and output waveforms, controllable power factor. o There is no energy storage capacitors or DC link., and this will reduced size and the weight of the converter. o There are a number of different modulation methods for MCs, such as Venturini, space vector and scalar methods. Cyclic Venturini method is used in the simulation, fig.2. o Simulation results of a lower scale prototype with 6KVA power is shown using SABER and MATLAB simulation packages in this poster using a digital repetitive controller. Introduction: o A matrix converter (MC) is a direct power converter used to convert AC supply voltages into variable magnitude and frequency output voltages. o Ground power units (GPU) are designed to provide quality supply of 115V-200V, three phase, 400Hz to aircrafts. The standard ratings are from 40 kVA to 120kVA, fig.1. o Using MC in a GPU has many advantages over rectifier/inverter systems such as a sinusoidal input and output waveforms, controllable power factor. o There is no energy storage capacitors or DC link., and this will reduced size and the weight of the converter. o There are a number of different modulation methods for MCs, such as Venturini, space vector and scalar methods. Cyclic Venturini method is used in the simulation, fig.2. o Simulation results of a lower scale prototype with 6KVA power is shown using SABER and MATLAB simulation packages in this poster using a digital repetitive controller. Conclusion and future work: In this poster, a digital repetitive controller is used to control a 4-Legs matrix converter. Results have showed that there is a good tracking of the reference input during both balanced and unbalanced load conditions. Next step is to build the prototype of a 6KVA to validate the simulation results. Conclusion and future work: In this poster, a digital repetitive controller is used to control a 4-Legs matrix converter. Results have showed that there is a good tracking of the reference input during both balanced and unbalanced load conditions. Next step is to build the prototype of a 6KVA to validate the simulation results. Repetitive controller: o Repetitive control is a smart controller intends to track any repeated signal and reduce the tracking error. o The proposed controller is used in the ABC reference frame, where each phase has its controller. o This will overcome any instability during unbalanced load condition, fig 3. o The tracking controller is Used to compensate the steady state errors that could not altered by the classical controllers. Repetitive controller: o Repetitive control is a smart controller intends to track any repeated signal and reduce the tracking error. o The proposed controller is used in the ABC reference frame, where each phase has its controller. o This will overcome any instability during unbalanced load condition, fig 3. o The tracking controller is Used to compensate the steady state errors that could not altered by the classical controllers. Fig.3 proposed controller structure Modulation Method: o The switching sequences changes cyclically according to input voltage vector position Modulation Method: o The switching sequences changes cyclically according to input voltage vector position Fig.2 Cyclic Vemturini modulation Results and discussion: The system stability and robustness were tested for balanced and unbalanced load conditions. It can be seen from fig.4 and fig.5, that the controller is working and tracking the reference input, voltage during the balanced and unbalanced load conditions. Results and discussion: The system stability and robustness were tested for balanced and unbalanced load conditions. It can be seen from fig.4 and fig.5, that the controller is working and tracking the reference input, voltage during the balanced and unbalanced load conditions. D. Input current in phase A. C. Output voltage spectrum Fig.4 Un-Balanced Load. A. Phase voltage compared with reference voltage B-Input Currents during the Balanced loads. Fig.5 Balanced Load. A. Phase voltage compared with reference voltage B-Input Currents during the Un-Balanced loads. D. Input current in phase A. C. Output voltage spectrum