SolarMagic SM3320-RF-EV主要特性:

• Wireless shutdown for SM3320-1A1

• Wireless Panel-Mode operation for SM3320-1A1

• MPPT for Photovoltaic Panel

• 2.4 GHz ISM band operation

• Enhanced 8 bit 8051 compatible microcontroller

• Power line antenna

参考设计指标:


图.SolarMagic SM3320-RF-EV方框图
 
图.PV系统中的SolarMagic SM3320-RF-EV板应用框图

图.SolarMagic SM3320-RF-EV电路图(1)

图.SolarMagic SM3320-RF-EV电路图(2)NS公司的SolarMagic SM3320-RF-EV参考设计集成了功率优化器SM3320-1A1和低成本2.4GHz无线发送器Nordic nRF24LE1,在光伏(PV)系统中增加遥控关断特性.该RF系统是双向的,可用作监视,安全和识别等通信应用.而功率优化器具有最好的功率优化特性,峰值效率99.5%.
图.SolarMagic SM3320-RF-EV
The SolarMagic™ SM3320-RF-EV reference design integrates a power optimizer and a low-cost 2.4GHz radio to add a remote shutdown feature to a PV system. The remote shutdown feature can be used during installation, maintenance, or emergency situations to de-energize the PV system.

Although its principal purpose is to communicate shutdown intent, this RF system is 2-way and can be used for a wide variety of communication applications, including monitoring, security and identification.

The SolarMagic™ SM3320-RF-EV is based off of the SM3320-1A1 power optimizer, and shares all of its best-inclass power optimization features. This includes its ability to mitigate real-world mismatch, its 99.5% peak efficiency, and its Panel-Mode operation. In addition, the same ultra-low profile form factor of the original SM3320-1A1 is maintained so that it can be integrated into the same junction box designs.

This evaluation board should work as a power optimizer even without a transmitter

The wireless RF communications in the SM3320-RF-EV is implemented using a low-cost Nordic nRF24LE1 chip. This is a low-cost, 2.4GHz radio and 8051 microcontroller on a single chip. The 2.4GHz radio uses narrow band modulation (as opposed to direct sequence spread spectrum), which can be used either with or without frequency hopping. Example software is provided that implements the remote shutdown feature on the 8051 microcontroller in the nRF24LE1.

One of the unique features of the SM3320-RF-EV is its use of the DC power lines as an RF antenna and transmission line. This enables the SM3320-RF-EV to maintain radio communication even when it is mounted in the junction box of the module. This antenna design can be used with other 2.4GHz radio chipsets besides the nRF24LE1 by straightforward modification of the provided design files.

The SM3320-RF-EV reference design provides a flexible platform for developing value added features in firmware with no additional hardware development. Examples of these features include module-level monitoring, security (theft-detection and theft-deterrence), and identification. Similarly, firmware development on this platform can be used to customize the SM3320-RF-EV to be compatible with an existing monitoring system or inverter communication protocol if a customer desires.

SolarMagic™ technology is an overall solution that works in existing and new installations, residential, commercial, and utility scale projects. National Semiconductor’s 50 years of experience in the electronics industry delivers unsurpassed manufacturing, design, and development technology.

The Sirius RF evaluation board shares the same power specifications as the SolarMagic SM3320-1A1 Power Optimizer. The controller for the power optimizer consists of an SM72442 programmable MPPT controller for PV panels and a Nordic nRF24LE1 low power system-on-chip wireless solution. The nRF24LE1 has a built in 2.4GHz transceiver (250kbps, 1Mbps and 2Mbps air data rates) and an 8051 compatible microcontroller. Operation at 250kbps is recommended.

接收器

The nRF24LE1 IC will be located in the SM3320-RF-EV board and used as a receiver that controls the forced shutdown and Panel-Mode operation.

By utilizing these two ICs (SM72442 and nRF24LE1),the evaluation board is capable of tracking the maximum power point of PV panels during normal operation as well as controlling a shutdown during emergency conditions. Two of the GPIO outputs (P0.0 and P0.1) from the microcontroller are used to send a shutdown or Panel-Mode signal into the SM72442. The shutdown signal will pull the RESET pin low in order to deactivate the PWM signals that are coming out from SM72442. Panel-Mode operation can be forced on the SM72442 by pulling the PM pin of the SM72442 low.

Included in the SM3320-RF-EV are the following items:

1. SM3320-RF-EV PCB

2. Software for the Receiver (SM3320-RF-EV) – compiled and source code

3. Software for the Central Transmitter (nRF6310) - compiled and source code

4. Design files – Schematic, BOM and Gerbers