Optimization of the performance of solar powered permanent magnet dc motor drives

While designing large-scale photovoltaic generators (PVGs), due to high initial cost of PVGs, the power mismatch issue has to be addresses to minimize the losses and improve the array performance. Therefore solar powered electric motor drives must be operated at their optimum performance at all solar radiation levels. This present paper describes a very simple and highly efficient MPPT unit for optimizing performance of a PVG powered permanent magnet (PM) DC motor driving a water pump. The unit is composed of a step-up DC-DC converter with two filter capacitors at the two ends. Energy utilization efficiency and the price-performance ratio of the whole system is maximized by fixing the chopping frequency of the DC-DC converter chopper at a pre-determined value (1.2 kHz in this case) and varying the duty cycle of the chopper according to a relation between the duty cycle and the percent solar radiation level, G, which is established in this present investigation. The proposed system is fully modeled in time domain and both the transient and steady-state performance of the system is closely observed. It is shown that with such an arrangement the PVG is forced to operate very close to its maximum power trajectory. Due to its simplicity and high efficiency, the proposed system may be preferred over other more complicated systems available in the market or proposed in the other publications.