This paper proposes two new Maximum Power Point Tracking (MPPT) methods which improve the conventional Fractional Open Circuit Voltage (FOCV) method. The main novelty is a switched semi-pilot cell that is used for measuring the open-circuit voltage. In the first method this voltage is measured on the semi-pilot cell located at the edge of PV panel. During the measurement the semi-pilot cell is disconnected from the panel by a pair of transistors, and bypassed by a diode. In the second Semi-Pilot Panel method the open circuit voltage is measured on a pilot panel in a large PV system. The proposed methods are validated using simulations and experiments. It is shown that both methods can accurately estimate the maximum power point voltage, and hence improve the system efficiency.
The study proposes a new Generic phase shifted (PS) pulse-width modulation (PWM) approach. Four Generic PS PWM algorithms are proposed. The important advantage of the proposed approach is that it can be easily implemented with multilevel inverters of any topology. The first method produces the 13-level PS PWM signal from six 3-level phase disposition (PD) PWM signals whose carrier signals are PS from each other by the time interval of 1/(6f carrier). The second method produces the 13-level PWM signal also from six 3-level PD PWM signals, whereas their modulation and the carrier signals are both PS by the time interval of T modulation /(6 × 5), where T modulation is the modulation cycle time interval. The third method produces the 13-level PWM signal from three 5-level PD PWM signals, whereas their carrier signals are PS from each other by the time interval of 1/(3f carrier). The fourth method produces the 13-level PS PWM signal from three 5-level PD PWM signals, whereas their modulation and carrier signals are both PS by the time interval of T modulation /(3 × 5). The proposed methods are analysed and compared one to the other and to the conventional PD PWM method. The analysis is validated by extensive simulation results.
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