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Considering the spread spectrum problem of finite-control-set model predictive control (FCS-MPC), a fixed switching frequency strategy based on cost function reconstruction is proposed in this paper. It achieves a fixed switching frequency by selecting the optimal voltage vector through the redefined cost function. A frequency coefficient is added to this to change the selecting area of the optimal voltage vector. The proposed strategy reshapes the spectrum of the inductor current and focuses the harmonics near the switching frequency so that the design of the output LC filter is easier. Without adding any modulators or greatly increasing the number of computations, the proposed strategy reserves the excellent dynamic performance of the FCS-MPC and is convenient in terms of implementation. Finally, a 1 kW single-phase inverter is built and experiments are conducted. Experimental results demonstrate that the proposed control strategy realizes a fixed switching frequency. In addition, it has a comparative dynamic response speed and number of calculations when compared to dead-beat-based FCS-MPC. These features are beneficial to its application.

In this study, a novel energy management strategy (EMS) with two degrees of freedom is proposed for hybrid energy storage systems consisting of supercapacitor (SC) and battery in islanded microgrids. The proposal introduces two degrees of freedom including an adaptive high-pass filter cut-off frequency f c and a charge/discharge coefficient kb, according to the SC and battery state of charge (SOC), respectively. The f c regulates SC current in the transient process and the kb controls battery current in the steady-state. Therefore, appropriate power distribution that the SC suppresses the transient power fluctuations while the battery supports average power demand is realised, over-charging, and over-discharging are avoided and the current stress of the battery during the shut-down process is reduced. Moreover, three operation modes for isolated DC microgrids, comprising power-sharing mode, battery-only mode, and extreme mode are demonstrated. Hence, the DC microgrid can remain stable for the whole time, achieve seamless transitions from the power-sharing mode to the two others, and provide faster SOC recovery of the SC. The effectiveness of the proposed EMS is validated by experimental studies with a prototype of the simplified DC microgrid.

In this paper, a hybrid control strategy for power converters, based on improved deadbeat control (DBC) and improved finite control set model predictive control (MPC), is proposed. The presented control strategy employs a switched method to achieve a fixed switching frequency while maintaining a fast transient time. Moreover, the proposal incorporates error correction to achieve superior robustness. A prototype of a single-phase voltage source rectifier is established to verify the performance of the proposal. The comparative results with conventional MPC are given and illustrate the merits of the proposed control method.

Dry-cured bacons were processed using pig bacon belly as material by dry-salting and drying–ripening. Lipolysis and lipid oxidation in intramuscular lipids were studied by evaluating the changes in lipid composition, lipolytic enzymes and lipoxygenase (LOX) activities, peroxide value (POV) and TBARS during processing. Lipid composition showed a significant decrease (p

Crude lipoxygenase (LOX) was extracted from fresh pig bacon belly and studied of partial characteristics. The interactions of temperature, sodium chloride (NaCl) and pH on LOX activity were investigated by response surface methodology (RSM). Kinetic studies indicated that the Michaelis constant (K(m)) and maximum velocity (V(max)) for LOX activity using linoleic acid as substrate were 68 μM and 0.26 U/min at 20°C, respectively. The optimal conditions for this reaction were: substrate concentration 3.47 mM, reaction temperature 39°C and pH ≧9.0. The NaCl critical value for LOX activity was 3.0% (w/w) at 20°C, above which the LOX activity began to decrease. Temperature had significant interactions (p