Maximum power point tracking for building integrated photovoltaic ventilation systems

Abstract

The objective of this project was to design a device to optimize the interface of a building integrated photovoltaic (BIPV) array with ventilation fans. The developed device tracks the maximum power point of the BIPV array and limits the output voltage to the level required by the fans. The purpose of maximum power point tracking (MPPT) is to automatically match the current and voltage characteristics of the load to the BlPV array's maximum power point at any given illumination. To accomplish this a unique switch mode buck converter was used. The available power from the PV array is a total of approximately 2.5 kW,. The two PV sub-arrays supply a voltage up to 220 VDC each and have a maximum power point voltage of 169 VDC. The load consists of two sets of six 133 W, 9OVDC ventilation fans. The device also has a soft-start circuit on board to start the motors slowly to avoid excessive current requirements from the array. This unit achieves efficiencies above 93 YO.

Comparison of Photovoltaic Array Maximum Power Point Tracking Techniques

“…In [66] and [67], a hysteresis-based version of RCC is used. A low frequency dithering signal is used to disturb the power in [68]. In [68], a 90…”

“…The difference in [68] is that the injection is an extra, low-frequency signal and not an inherent converter ripple.…”

Dynamic maximum power point tracking of photovoltaic arrays using ripple correlation control

“…In [27], a slow dithering signal is used to disturb the power. The paper discusses a 90 phase shift in the current (or voltage) with respect to power at the MPP-exactly the same effect found in RCC.…”

“…The paper discusses a 90 phase shift in the current (or voltage) with respect to power at the MPP-exactly the same effect found in RCC. The difference in [27] is that the injection is an extra, low frequency signal, and not the naturally occurring power converter ripple. In [28] and [29], the authors present a method that disturbs duty cycle or frequency and observes power.…”

Maximum power point tracking for a photovoltaic power system

“…In [62]- [63], a hysteresis-based version of RCC is used. In [64], a low frequency dithering signal is employed to disturb the power. Then a 90° phase shift in the current (or voltage) with respect to power at the MPP is used just like in RCC.…”