The use of hybrid energy storage systems (HESS) in renewable energy sources (RES) of photovoltaic (PV) power generation provides many advantages. These include increased balance between generation and demand, improvement in power quality, flattening PV intermittence, frequency, and voltage regulation in Microgrid (MG) operation. Ideally, HESS has one storage is dedicated for high energy storage (HES) and another storage for high power storage (HPS) purpose. HES is used to fulfill long-term energy demand, while HPS is used to handle power transients and fast load fluctuations. This paper examines HESS comprehensively for PV power generation and focuses on its ability to combine two storage technologies. The two storage technologies include high energy and high power. This paper also analyzes the important aspects of advance HESS in PV power generation in the context of capacity sizing, power converter topology and strategies management energy. Several capacity sizing methods were critically reviewed and tabulated. Power converter (PC) topologies are classified and briefly discussed regarding their advantages and disadvantages. Furthermore, energy management strategies with various control techniques are critically classified and evaluated for better future direction. In addition, the implementation of HESS on PV power generation in current real projects is presented and evaluated. Finally, this paper can be considered as useful guide for the use of HESS in PV power generation including features, limitations, and real applications.

In this study, the advanced topologies of a DC–DC converter for applications involving the harvesting of solar energy are discussed. This work’s primary contribution is a guide for choosing the most effective topology for a DC–DC converter when developing solar energy collection systems. Several topologies of a DC–DC converter for solar energy harvesting applications are compared in terms of the range of power levels they can oversee, the complexity of the underlying hardware, the cost of implementation, the tracking efficiency and the overall efficiency of the converter. This article explains five innovative approaches for adapting boost converters to function as standard DC–DC converters to capture solar energy, consisting of (i) voltage-multiplier cell, (2) coupled inductor, (3) coupled inductor and switch capacitor, (4) cascaded topology and (5) voltage-lift technique. Because of the boost converter’s restrictions, it is necessary to deliver high performance. The comparison findings demonstrate that the voltage-lift-based boost-converter topology performs more effectively than the alternatives. In conclusion, the information presented in this paper can be utilized when developing solar energy collection systems to determine the sort of direct current to direct current converter that will be most effective.

A dynamic overmodulation strategy for fast dynamic torque control in direct torque control (DTC)-hysteresis-based induction machine is proposed. The fastest dynamic torque response with a six-step mode can be achieved in the proposed method by switching only the most optimized voltage vector that produces the largest tangential component to the circular flux locus. This paper also discusses the performance of dynamic torque control in basic DTC in order to justify on how the proposed selected voltage vector results in excellent dynamic torque performance. The main benefit of the proposed method is its simplicity, since it only requires a minor modification to the conventional DTC-hysteresis-based structure and does not require a space vector modulator. To verify the feasibility of the proposed dynamic overmodulation strategy, simulation and experimentation, as well as comparison with the conventional DTC scheme, are carried out. Results showed a significant improvement in the dynamic torque response when compared to the conventional DTC-hysteresis-based method.

The photovoltaic generation system (PGS) is considered a potential renewable energy harvesting system. However, the low conversion efficiency of PGS and maximum power point tracking (MPPT) technique are the main challenges that must be solved. In addition, the switching frequency of the converters employed also affects the MPPT system performance. A high gain voltage DC-DC converter is proposed to replace conventional power converter and fuzzy logic controller (FLC) is applied in the MPPT for optimizing solar energy harvesting system. Nevertheless, evaluation of suitable fuzzy membership function is needed for optimal MPPT technique of photovoltaic system. In this paper, FLC of MPPT for photovoltaic application system was built using various membership functions in MATLAB/Simulink environment. The switching frequency of the high gain voltage DC-DC converter is varied to test the robustness of the performance of each FLC membership function. The results showed that the FLC-based MPPT technique for high gain voltage DC-DC converter with GBell membership function type has the capability to track the maximum power point (MPP) accurately and to achieve optimum power conversion. Furthermore, GBell membership showed having stable and consistent performance at various switching frequencies.

This paper presents a novel direct torque control (DTC) approach for induction machines, based on an improved torque and stator flux estimator and its implementation using field-programmable gate arrays (FPGA). The DTC performance is significantly improved by the use of FPGA, which can execute the DTC algorithm at higher sampling frequency. This leads to the reduction of the torque ripple and improved flux and torque estimations. The main achievements are: 1) calculating a discrete integration operation of stator flux using backward Euler approach; 2) modifying a so called nonrestoring method in calculating the complicated square root operation in stator flux estimator; 3) introducing a new flux sector determination method; 4) increasing the sampling frequency to 200 kHz such that the digital computation will perform similar to that of the analog operation; and 5) using two's complement fixed-point format approach to minimize calculation errors and the hardware resource usage in all operations. The design was achieved in VHDL, based on a Matlab/Simulink simulation model. The Hardware-in-the-Loop method is used to verify the functionality of the FPGA estimator. The simulation results are validated experimentally. Thus, it is demonstrated that FPGA implementation of DTC drives can achieve excellent performance at high sampling frequency.