Method and apparatus for controlling power drawn from an energy converter

Abstract

Methods, apparatus, media and signals for controlling power drawn from an energy converter to supply a load, where the energy converter is operable to convert energy from a physical source into electrical energy. Power drawn from the energy converter is changed when a supply voltage of the energy converter meets a criterion. The criterion and the change in the amount of power drawn from the energy converter are dependent upon a present amount of power supplied to the load. The methods, apparatus, media and signals described herein may provide improvements to DC to AC maximum power point tracking in an energy conversion system such as a photovoltaic power generation system.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of Invention [0002] This invention relates to energy conversion and more particularly to methods and apparatus for controlling power drawn from an energy converter operable to convert energy from a physical source into electrical energy. [0003] 2. Description of Related Art [0004] Energy conversion devices such as photovoltaic arrays are commonly used to provide power to electrical loads. Often these loads are direct current (DC) loads such as batteries, for example. Recently, efficiencies in power conversion devices are giving rise to solar power systems that supply power to an alternating current (AC) load such as an AC power grid such as may be operated by a public utility company. Such power systems may employ a photovoltaic array and an interface for converting power in a form received from the photovoltaic array into a form operable to be received by the AC power grid. Such an interface may involve a DC to AC inverter. [0005] Interfa...

AI Technical Summary

Benefits of technology

[0014] The method may further involve performing the method periodically, and defining a period for performing the method periodically. Defining the period may include defining the period as a function of the power supplied to the load. The method may involve increasing the period when the power supplied to the load is relatively low and decreasing the period when the power supplied to the load is relatively high.

Problems solved by technology

Consequently, the 100 kHz perturb and observe frequency of most switching mode power supplies used to supply DC loads is too fast for applications where the load is an AC power grid.

However, decreasing the perturb and observe frequency can waste power, especially when changes in insolation occur.

During this period the full available power is not being drawn from the array resulting in inefficient operation.

Images