In this paper, two predictive control methods for dual output multilevel rectifier are compared. The investigated structure is a seven-level PUC rectifier, which was selected based on high reliability and low cost. Increasing the number of input voltage levels helps to
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In this paper, two predictive control methods for dual output multilevel rectifier are compared. The investigated structure is a seven-level PUC rectifier, which was selected based on high reliability and low cost. Increasing the number of input voltage levels helps to reduce the amount of harmonics and consequently reduce the size of power filters. On the other hand, current conduction in this converter is performed continuously and the problems of current discontinuity such as complexity in analysis and the requirement to use large induction filters on the DC side are solved. First, the design is accomplished based on the FCS-MPC method and two different output voltages with ratios of 1 and 3 are obtained. Also, the control of output DC voltages and unity input power factor is well provided. Then, to achieve better stability, the MPC method based on Lyapunov theory has been utilized. In this method, the target variables are defined in the Lyapunov function and the cost function is derived from the same Lyapunov function. The advantages of this approach compared to the conventional MPC method are no need for gain adjustment, easier implementation and fewer sensors (the load current is estimated using the PUC7 rectifier mathematical model). The simulation of both FCS-MPC and predictive control based on Lyapunov method is carried out using Matlab/Simulink and the results of both methods are presented and compared with each other. Finally, it can be seen that in the Lyapunov-based method, the tracking of the reference current is smoother and with less fluctuations, and the seven-level rectifier voltage also has a more regular and sinusoidal waveform.
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