Multiple motor operation using solar power

Abstract

A solar powered system controls multiple motors directly from a single solar power source with a single variable frequency drive (VFD). A control system selectively connects and disconnects individual motors as solar power varies so that the available power can be used effectively and some of the motors can be kept operating rather than shutting down the entire system. The control system includes a detection circuit for detecting the solar array voltage, and a selection circuit for providing shutoff control signals to individual motors based on the solar array voltage and preselected motor shutoff priority criteria.

Description

RELATED APPLICATIONS [0001] This application claims priority of Provisional Application Ser. No. 60 / 723,268 filed Oct. 3, 2005.BACKGROUND OF INVENTION [0002] 1. Field of the Invention [0003] The invention relates generally to solar powered systems, and more particularly to the operation of multiple motors using solar power. [0004] 2. Description of Related Art [0005] Solar power is being increasingly used as an alternate energy source. One application is to provide power to operate motors. Most motors are AC motors. The DC output of a solar panel array is converted to AC power by a variable frequency drive (VFD). In many applications, it is desirable to drive an array of multiple motors from a single VFD connected to a solar power source. [0006] Controlling multiple motors from a single variable frequency drive (VFD) has been done but always from an AC grid voltage which is a stable power source capable of supplying the required power. When used with solar power, caution must be tak...

AI Technical Summary

Benefits of technology

[0009] This invention is a solar powered system for controlling multiple motors directly from a single solar power source with a single variable frequency drive (VFD). A control system selectively connects and disconnects individual motors as solar power varies so that the available power can be used effectively. The invention detects overload currents and staggers motor operation in the event of an overload condition. Thus some of the motors can be kept operating rather than shutting down the entire system. The invention also detects solar array voltage and automatically adjusts motor frequency for optimum power performance.

Problems solved by technology

When used with solar power, caution must be taken as the power supply is not stable but a varying power supply.

Multiple motor operation under these conditions can result in starved power to the motors, resulting in motor damage.

An important aspect of these solar powered motor systems is motor inrush which can result in shutdown of the entire VFD drive if not controlled.

The latter is most expensive and dependent on motor inrush currents.

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