A flyback inverter using voltage sensorless maximum power point tracking (MPPT) for photovoltaic (PV) AC modules is presented. PV AC modules for a power rating from 150 W to 300 W are generally required for their small size and low price because of the installation on the back side of PV modules. In the conventional MPPT technique for PV AC modules, sensors for detecting PV voltage and PV current are required to calculate the PV output power. However, system size and cost increase when the voltage sensor and current sensor are used because of the addition of the auxiliary circuit for the sensors. The proposed method uses only the current sensor to track the MPP point. Therefore, the proposed control method overcomes drawbacks of the conventional control method. Theoretical analysis, simulation, and experiment are performed to verify the proposed control method.

In this paper, energy storage system(ESS) operation algorithm for economics considering battery degradation properties is proposed. Hourly electricity charge according to real-time pricing (RTP) and battery properties are analyzed for high profit through ESS operation. Especially, hourly electricity charge of Illinois State is analyzed. Characteristics of battery accounts for a high percentage of ESS configuration. Thus, degradation properties of the battery for the price considering the loss of battery usage is considered. The algorithm is proposed for the highest profit through analysis of the battery degradation properties and electricity charge, and the proposed algorithm is verified by mathematical analysis.

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This paper proposes a novel dual integrated LLC resonant converter (DI-LRC) with a wide output voltage range using various switching patterns. The primary side of the proposed DI-LLC converter consists of two resonant tanks and six switches, while the secondary side consists of a six-pulse diode rectifier. Depending on the switching pattern of the primary switch, the DI-LRC converter is performed by single full-bridge operation with a voltage gain of 1, series-connected full-bridge operation with a voltage gain of 0.5, series-connected half bridge operation with a voltage gain of 0.25, and parallel-connected full-bridge operation with a voltage gain of 2. Accordingly, the proposed DI-LRC converter has four voltage gain curves with different variations and achieves a wider output voltage range than the conventional single voltage gain curve in a given operating frequency range. In this paper, the equivalent circuits derived for each switching pattern are proposed to analyze the operating characteristics of the proposed converter according to each switching pattern, and each Q factor and voltage gain are calculated based on the analyzed equivalent circuit. The performance of the proposed converter and switching pattern is verified using the simulation and experimental results of the prototype battery charger, which is designed to be 4-kW class.