To alleviate the power losses caused by the fluctuation of the output current of the photovoltaic (PV) array, a DC/DC converter with high-voltage gain is proposed for PV generation systems. The input current ripples of the proposed converter can be greatly reduced by making use of coupled inductors. Then the electrolytic capacitor on the input side could be replaced by polypropylene capacitor with smaller capacity and size. In addition, the snubber and the energy recovery circuits constructed by diodes and storage capacitors can be operated to reduce the voltage spikes of the switch tubes and losses caused by the leakage inductance. Based on analysing the inherent five operating modes of the proposed converter, high-voltage gain and the zero input current ripples characteristics of the proposed converter is manifested. The theoretical analysis is then verified by a 150 W-rated experimental prototype, and the results show that the proposed converter can quickly and accurately trace the maximum power point of PV array based on the modified incremental conductance method with high-voltage gain and low current ripples.

The Switched Reluctance generator (SRG) has been widely used as a constant voltage source due to its advantages of simple structure, low cost and high control flexibility. However, the output voltage ripples cannot be ignored due to its unique operating principle with phase commutation. In this paper, the influence of the control parameters on the output voltage ripples are analyzed, and a fly-wheeling pulse train (FW-PT) control strategy is proposed to suppress the voltage ripple. The output voltage can be regulated by the FW-PT control strategy by using two or more sets of preset control pulse combinations, therefore it has the advantages of simple circuit implementation, no Network compensation and fast response speed. The characteristics of steady-state and dynamic behaviors of the switched reluctance power generation system by using different control strategies are simulated and compared, and a platform of 200W 8/6 SRG is built for experimental verification. Simulation and experimental results confirm that compared with the traditional PID control strategy, the FW-PT control strategy can be used to not only suppress the output voltage ripple, but also achieve faster response and dynamic characteristics.INDEX TERMS SR power generation system, pulse train, fly-wheeling current, voltage ripple, dynamic characteristics.

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In order to improve the performance of switched reluctance motor (SRM) systems for photovoltaic (PV) pumps, this paper introduces a new converter topology for SRM with controllable multiple power sources. Only simple switching components need to be added at the front end of the asymmetric half-bridge converter in this topology, which enables the control of multiple power sources. The new PV pump system has four operating modes, which are the PV panel driven mode, battery bank driven mode, dual-source driven mode, and battery charging mode. By adjusting the state of the front-end converter switch, the voltage tracking of PV panel can be achieved, providing a stable bus voltage for the SRM system. By controlling the battery bypass switch, the bus voltage of SRM system can be increased, thereby increasing the system power level. Simulations and experiments based on a four-phase 8/6 SRM demonstrate the effect of the novel converter proposed in this paper.

Abstract:The Switched Reluctance Generator (SRG) is suitable for wind power generation due to its good reliability and robustness. However, The SRG system adopting the conventional control algorithm with Pulse Width Modulation (PWM) method has a drawback, low response speed. The pulse train (PT) control has been widely used in dc/dc power converters operating in the discontinuous conduction mode due to its advantages of simple implementation and fast response. In this paper, for the first time, the PT control method is modified and adopted for controlling the output voltage of SRG system in order to achieve fast response. The capacitor current on the output side is sampled and combined with the output voltage to select the pulse trains and the low frequency oscillation cased by PT can be suppressed by tuning the feedback coefficient of the capacitor current. Also, good performance can be guaranteed with a wide range of voltage regulations, fast response, and no overshoot. The experimental platform of an 8/6 SRG system is built, and the experimental results show that the PT control can be used for SRG system with good practicability.