ST 3kW光伏电压转换解决方案

 STEVAL-ISV002V2 是能连接到电网的3kW光伏电压转换器开发板,包括高频绝缘输入功率部分(实现DC/DC转换)和逆变器部分(提供50Hz正弦波电流到电网),输入电压范围从200V到400V,系统输出通过LCL滤波器以230Vrms 50Hz连到电网,正常输出功率3kW.本文介绍了STEVAL-ISV002V2 主要特性,硬件方框图,控制方框图和MPPT算法方框图,以及系统指标,完整电路图和材料清单.

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

图1.STEVAL-ISV002V2外形图

图2.STEVAL-ISV002V2硬件方框图

图3.STEVAL-ISV002V2控制方框图

图4.STEVAL-ISV002V2 MPPT算法方框图

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系统指标:

图5.STEVAL-ISV002V2电路图:功率级

图6.STEVAL-ISV002V2电路图:输出检测和继电器板

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图7.STEVAL-ISV002V2电路图:AC电压测量

图8.STEVAL-ISV002V2电路图:线电流调理电路

图9.STEVAL-ISV002V2电路图:STM32 MCU电路

图10.STEVAL-ISV002V2电路图:DC/DC转换器驱动电路 

图11.STEVAL-ISV002V2电路图:DC/AC转换器驱动电路

图12.STEVAL-ISV002V2电路图:5V 1A反馈转换器和VIPER17HN电路

图13.STEVAL-ISV002V2电路图:多输出反馈转换器和VIPER27HN电路