A Novel Fast MPPT Strategy for High Efficiency PV Battery Chargers

Abstract

The paper presents a new maximum power point tracking (MPPT) method for photovoltaic (PV) battery chargers. It consists of adding a low frequency modulation to the duty-cycle and then multiplying the ac components of the panel voltage and power. The obtained parameter, proportional to the conductance error, is used as a gain for the integral action in the charging current control. The resulting maximum power point (MPP) is very still, since the integral gain tends to zero at the MPP, yielding PV efficiencies above 99%. Nevertheless, when the operating point is not the MPP, the integral gain is large enough to provide a fast convergence to the MPP. Furthermore, a fast power regulation on the right side of the MPP is achieved in case the demanded power is lower than the available maximum PV power. In addition, the MPPT is compatible with the control of a parallel arrangement of converters by means of a droop law. The MPPT algorithm gives an averaged duty-cycle, and the droop compensation allows duty-cycles to be distributed to all active converters to control their currents individually. Moreover, the droop strategy allows activation and deactivation of converters without affecting the MPP and battery charging operation. The proposed control has been assayed in a battery charger formed by three step-down converters in parallel using synchronous rectification, and is solved in a microcontroller at a sampling frequency of 4 kHz. Experimental results show that, in the worst case, the MPPT converges in 50 ms against irradiance changes and in 100 ms in case of power reference changes.

High Efficiency Solar Power Generation with Improved Discontinuous Pulse Width Modulation (DPWM) Overmodulation Algorithms

“…Conventionally, MPPT is embedded in a converter to determine the duty cycle that maximizes the PV power yield [22]. A perturbation and observation method (P&O) is used to find the maximum power point [23] by altering the array terminal voltage and then comparing the PV output power with its previous value.…”

Robust Direct Adaptive Controller Design for Photovoltaic Maximum Power Point Tracking Application

“…The amount of the generated power from any PV panel varies based on the resistive load applied across the panels, and this will cause a reduction in the generated power, even at the same solar 2 of 19 irradiance and temperature. The maximum power point (MPP) occurs at a specific load value and changes with the irradiance and temperature variations during the day, making it difficult to locate and determine the MPP [11,12]. To use solar cells with a wider range of load and while minimizing the power losses, maximum power point tracking (MPPT) devices are required to adjust the voltage operating point close to the voltage that gives the maximum power [13].…”

A Control Scheme without Sensors at the PV Source for Cost and Size Reduction in Two-Stage Grid Connected Inverters

“…Moreover, grid-connected PV inverters must comply with several electromagnetic compatibility (EMC) regulations, some of which limit the distortion of the current injected into the grid (THDi), like IEC EN61000 and IEEE519 [1][2][3][4]. Maximum power point tracking (MPPT) algorithms are implemented to optimize the performance of PV systems [5][6][7][8][9]. Conventional MPPT algorithms use current and voltage sensors to calculate the power extracted from the PV source.…”