Publication: Model predictive control of single-phase split-source inverter
Date
2022-05-01
Authors
Adrian Tan, Soon Theam
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Abstract
Single-phase split-source inverter (SSI) is an emerging and attractive topology for a boost DC–AC power conversion system. Existing SSI suffers from high frequency commutations across the diodes and the implementation of conventional sinusoidal pulse-width modulation (PWM) control result in variable inductor charging duty cycle which produces undesirable low-frequency harmonics. In order to overcome aforementioned drawbacks, hybrid modulation of quasi-sinusoidal and constant PWM is adopted but harmonics in the output voltage are obliged to concentrate around the switching frequency and its multiples. Addressing the aforementioned concerns, this thesis proposes a simplified SSI (S3I) topology which retains the attractive features of existing SSI with the added benefits of reduced switch count, enhanced voltage-boosting gain, reduced output filter requirement, and enhanced power efficiency. For the proposed S3I, a new PWM strategy is derived and implemented which ensures the inductor is being charged with constant duty cycle
while the harmonics in the output voltage is concentrated around twice the switching frequency and its multiples. In addition, model predictive control is developed and
implemented for the proposed S3I as an alternative control that offers easy inclusion of nonlinearities and constraints such as output current and DC-link voltage. Comprehensive steady-state analysis is discussed while simulation and experimental results are presented to validate of the proposed topology and both of the control strategies. Experimental results of proposed S3I with new PWM strategy achieved good output voltage gain of 1.66 to 5.89 and DC-link voltage gain of 1.85 to 2.82 for modulation index of 0.5 to 0.7. The proposed S3I are able to achieve 88% to 92% efficiency for full range of input voltage. Meanwhile, experimental results for proposed S3I controlled with MPC strategy shows good tracking of measured DC-link voltage of 58V and measured peak output current of 0.61A was obtained with the predetermined reference value of 60V and 0.5A respectively.