STEVAL-ISV003V1 #2: 250W Solar Microinverter, MPPT

Summary

The STEVAL-ISV003V1 is a demonstration board which implements the microinverter concept and is designed to optimize the power production of each single solar panel by means of DC/AC conversion. The conversion system is capable of both grid synchronization and Maximum Power Point Tracking (MPPT) thanks to the use of an advanced control algorithm implemented in the 32-bit STM32 microcontroller. The MPPT function is based on the perturb and observe (P & O) concept which seeks the best operating point of the panel, thus maximizing the energy produced under any environmental condition. The grid synchronization algorithm has the advantage over standard solutions of a decoupled control of active and reactive power. The STEVAL-ISV003V1 demonstration board uses a high-frequency (HF) isolated DC/DC converter with interleaved current and an optimized full-bridge DC/AC inverter. The typical solar panel voltage is first stepped up to about 400 V and then converted into AC to create a sinusoidal output.

An LED display provides a user-friendly interface for the end user which allows monitoring and/or modifying some of the main operating parameters. Two modes of operation are available and can be selected to allow either open-loop operation or closed-loop operation in synchronization with the grid.

In open-loop mode the sinusoidal reference is created internally by means of a standard lookup table, while in closed-loop mode, a sinusoidal voltage feedback, proportional to the grid voltage, is used. The system can be connected to either a 50 Hz or 60 Hz network, depending on local requirements. Finally, the RS-232 interface can be used for serial data transfer of specified voltage, current and current signals.

Features:

250 W power capability
Input voltage range from 18 V to 45 V
Output voltage Vout= 230Vac 50Hz -240Vac 60Hz
Grid connection algorithm and MPPT capability
MPPT efficiency (99%)
Decoupled control of active and reactive power
Overcurrent and anti-islanding protection
RS-232 for communication
Galvanic isolation between the panel and the grid

Specifications

Manufacturer	STMicroelectronics
Category	Energy Harvesting
Sub-Category	Solar Inverter
Eval Board Part Number	497-12941-ND
Eval Board Supplier	STMicroelectronics
Eval Board	Board not Stocked
Output Power	250 W
Voltage Out @ Frequency	110 ~ 240 V @ 50/60 Hz
Voltage In	18 ~ 45 V
Features	Anti-Islanding Protection Grid Connectable Over Current Protection
Efficiency @ Conditions	>95%, 20 ~ 40V in, 380V @ 75 ~ 250 W >93%, 380V in, 240 VAC @ 75 ~ 250 W
Component Count + Extras	342 + 16
Design Author	STMicroelectronics
Switching Frequency	17 kHz 35 kHz
Application / Target Market
Main I.C. Base Part	STM32F103ZE
Date Created By Author
Date Added To Library	2013-05