ST 3kW光伏電壓轉換解決方案

STEVAL-ISV002V2 是能連接到電網的3kW光伏電壓轉換器開發板,包括高頻絕緣輸入功率部分(實現DC/DC轉換)和逆變器部分(提供50Hz正弦波電流到電網),輸入電壓范圍從200V到400V,系統輸出通過LCL濾波器以230Vrms 50Hz連到電網,正常輸出功率3kW.本文介紹了STEVAL-ISV002V2 主要特性,硬件方框圖,控制方框圖和MPPT算法方框圖,以及系統指標,完整電路圖和材料清單.

Interest in photovoltaic (PV) applications has grown exponentially in recent years. As PV systems require an electronic interface to be connected to the grid or standalone loads, the PV market is increasingly appealing for many power electronics manufacturers.

The STEVAL-ISV002V2 demonstration board implements a conversion system for PV applications with the aim of achieving high efficiency and significant reduction in production costs. It consists of a high-frequency isolated input power section which performs the DC-DC conversion, and an inverter section capable of delivering sinusoidal current at 50 Hz to the grid.

The system operates with input voltages in the range of 200 V to 400 V, and is tied to the grid at 230 Vrms, 50 Hz, through an LCL filter.

Other unique characteristics of the proposed converter are integration level, decoupled active and reactive power control and flexibility towards the source.

A fully digital control algorithm, including power management for grid-connected operation and MPPT (maximum power point tracking) algorithm, has been implemented on a dedicated control board, equipped with a latest-generation 32-bit (STM32) microcontroller.

STEVAL-ISV002V2 主要特性:

■ DC-DC input voltage: 200 V to 400 V

■ DC-DC output voltage: 450 V

■ DC-AC output voltage: 230 Vac

■ Nominal output power: 3 kW

■ DC-AC switching frequency: 17 kHz

■ DC-DC switching frequency: 35 kHz

■ Transformer turns ratio: 1.2

■ Grid voltage: 230 Vrms +/-20%

■ Grid frequency: 50 Hz

■ Power factor: above 10%; rated power > 0.9

■ THD @ full load: 5%

■ RoHS compliant

圖1.STEVAL-ISV002V2外形圖

圖2.STEVAL-ISV002V2硬件方框圖

圖3.STEVAL-ISV002V2控制方框圖

圖4.STEVAL-ISV002V2 MPPT算法方框圖

STEVAL-ISV002V2包括:

It consists of 5 PCBs electrically connected by means of suitable connectors. The 5 PCBs are listed below and are hereafter referred to with the following nomenclature:

● Main power board

● Multi-output power supply board

● Control and signal conditioning board

● Output sensing and relay board

● Input current sensing board

STEVAL-ISV002V2系統指標:

圖5.STEVAL-ISV002V2電路圖:功率級

圖6.STEVAL-ISV002V2電路圖:輸出檢測和繼電器板