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Intelligent PV Power System with Unbalanced Current Compensation Using CFNN-AMF
摘要： A novel method is proposed to compensate the three-phase unbalanced currents of power grid under three-phase unbalanced load for a two-stage photovoltaic (PV) power system without the augmentation of active power filter (APF). The PV power system is composed of an interleaved DC/DC converter and a three-level neutral-point clamped (NPC) inverter. Moreover, the PV power system possesses the smart inverter function, in which the output active and reactive powers of the PV inverter are predetermined by a power factor according to grid codes of the utilities. In the proposed method, the dq0-axis compensation currents are obtained through low pass filters (LPFs) to compensate the three-phase unbalanced currents of power grid. Furthermore, in order to improve the control performance of the DC bus voltage of the PV power system under unbalanced load variation condition, an online trained compensatory neural fuzzy network with an asymmetric membership function (CFNN-AMF) is proposed to replace the traditional proportional-integral (PI) controller for the DC bus voltage control. In the proposed CFNN-AMF, the compensatory parameter to integrate pessimistic and optimistic operations of fuzzy systems is embedded in the CFNN. In addition, the dimensions of the Gaussian membership functions are directly extended to AMFs. Additionally, the proposed controllers of the PV power system are implemented by two control platforms using floating-point digital signal processor (DSP). Finally, excellent compensation performance for the three-phase currents of power grid under three-phase unbalanced load can be achieved from the experimental results.
关键词： asymmetric membership function,PV power system,compensatory neural fuzzy network,unbalanced current compensation,three-level neutral-point clamped inverter,interleaved DC/DC converter
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - A Voltage-Edge-Rate-Limiting Soft-Switching Inverter for Wide-Bandgap Devices
摘要： Wide-bandgap (WBG) switches can achieve switching times on the order of several nanoseconds. However, faster switches generate larger inverter output dv/dt. Various deleterious effects attributed to large inverter dv/dt have been observed in various applications, especially in motor drive systems. The effects include false turn-on of WBG switches due to cross-talk, transient over-voltages at motor terminals, electromagnetic interference, and motor bearing failures due to micro arcs. A common approach for limiting peak inverter dv/dt involves the insertion of a dv/dt filter. However, the dv/dt filter introduces extra power losses and increases the size/weight of the heat sink. Soft-switching circuits can reduce inverter dv/dt and switching losses, but using soft-switching to accurately control dv/dt has not been fully explored. A new soft-switching circuit, entitled the auxiliary resonant soft-edge pole (ARSEP), is set forth. The ARSEP improves the available soft-switching circuits so that the dv/dt can be accurately controlled through circuit parameter design. An ARSEP inverter prototype based on SiC MOSFETs was designed, simulated, built, and tested to verify its performance and benefits. Compared to a conventional hard-switched inverter with a dv/dt filter, the ARSEP inverter results in a significant reduction in overall power loss, inductor volume, and weight.
关键词： SiC MOSFETs,soft-switching circuits,auxiliary resonant soft-edge pole (ARSEP),inverter output dv/dt,Wide-bandgap (WBG) switches
更新于2025-09-04 15:30:14
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[IEEE 2018 International Power Electronics Conference (IPEC-Niigata 2018-ECCE Asia) - Niigata (2018.5.20-2018.5.24)] 2018 International Power Electronics Conference (IPEC-Niigata 2018 -ECCE Asia) - The Lifetime Assessment of a Micro-Inverter for PV Applications
摘要： Recently, introducing grid-tied PV systems is recommended in many countries. The inverter lifetime in PV applications is affected by their operating conditions. That is affected by the thermal loading of the power devices lifetime of electrolytic capacitors. Especially, the electrolytic capacitors at the DC-link to compensate the power ripple decreases when the ambient temperature increases. To improve the lifetime, a micro-inverter with an active buffer at the DC-link is introduced in this paper. In this micro-inverter, the DC-link electrolytic capacitor is replaced with a ceramic capacitor that has small capacitance. However, the reliability performance of the entire micro-inverter has not been evaluated. This paper thus assesses the lifetime of the micro-inverter considering the operational conditions (i.e., ambient temperature and solar irradiance, also referred to as mission profiles). A comparison between the proposed circuit with an active buffer and the conventional circuit based on a boost chopper is performed in this paper. It is revealed that the lifetime of the micro-inverter is very long. This is due to the over-designed power devices.
关键词： Photovoltaic,Lifetime estimation,Micro inverter
更新于2025-09-04 15:30:14