Ballard Power Systems Corporation

Ford Global Technolgoies, LLC

Vijay Bhavaraju

Kerry Eden Grand

Doug D Deng

Duo Deng

Kon-King Mike Wang

Anil Tuladhar

The maximum power point (MPP) of a photovoltaic array that can be coupled to power inverter is determined. A capacitor on a DC-bus side of the inverter is used as a load from which I-V characteristics of the photovoltaic array can be generated. The photovoltaic array is connected to the capacitor, which has been previously discharged by a bleed down resistor. Short circuit current, open circuit voltage, and values of current and voltage as the capacitor charges are determined and used to generate I-V characteristics of the photovoltaic array. From the I-V characteristics, the MPP can be calculated.

Method and apparatus for determining a maximum power point of photovoltaic cells

A power converter system advantageously employs a modular, bi-directionally symmetrical power converter assembly in a readily customizable configuration to interconnect a direct current power source to a three-phase alternating power grid. Connections external to the power converter assembly are selected to optimize the power converter system for a specific application, such as interconnecting a photovoltaic array to the three-phase electrical power grid. The electrical interconnections of various elements including isolation transformers, voltage sensors, and control switches are optimized to improve efficiency and reliability.

Power converter system

An inverter circuit (,) has a plurality of voltage source inverters (VSI) coupled in parallel. Each of the voltage source inverters are coupled to a load (,). A synch signal source (,) generates a square wave from a fundamental operating frequency. The square wave generated by the synch signal source (,) is coupled to each voltage source inverter (VSI). Each voltage source inverter VSI has a timer counter (,), a microprocessor (,), and an inverter (,). The timer counter (,) is preferably a triangle wave generator that corresponds to the time since a rising edge of a synch signal (,) The microprocessor (,) samples the cyclic output signal (,) and determines a phase angle for the voltage source inverter. The phase angle and the voltage magnitude are provided to the inverter (,). The inverter (,) provides an output signal to the load that has the same phase angle as the outputs of the other phase inverters.

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Canton, MI, United States of America

Vijay Bhavaraju