STEADY-STATE PERFORMANCE OF DC MOTORS SUPPLIED FROM PHOTOVOLTAIC GENERATORS WITH STEP-UP CONVERTER

Photovoltaic (PV) generators exhibit nonlinear insolation-dependent I-V characteristics with poor voltage regulation. Because of their high cost, the user is interested in operating the generator close to its maximum power. However, maximum-power point varies with solar insolation (during the day and from season to season) which makes it difficult to achieve optimum utilization at all insolation levels. In this paper a dc motor is supplied from a PV generator with a step-up converter having a fixed duty ratio. There exists a unique duty ratio at which optimum utilization efficiency is achieved at all insolation levels. This remarkable property makes this technique attractive since it eliminates the need for continuous adjustments of the duty ratio.