Flatpack2 Control

One of the purposes of use of the Flatpack2 rectifiers family in HAM radio is a power source for MOSFET-based HF Power Amps, where voltage source of 48-53V (combined with from 5 to 20A) is needed.


Here are some Flatpack2 pro and contra, found by myself as the user of product, combined with MOSFET-based HF PA for more than 8 years:

Pro:
- Robust design. Flatpack2 HE2000 survived numerous IOTA DXpeditions and that is saying something :)
- Low EMI. It definitely is. However common care should be taken. Setting up Flatpack2 in same box with PA may require extra EMI protection needed. I personally found it easier to keep rectifier in separate enclosure box.
- Fair enough size/weight combined with value for money.
- CAN bus capability
Contra:
- Limited variation of output voltage. Generally, most of Flatpack2 models can vary between 48V-54V output
- Extra work needed to connect Flatpack2.

However, taking considerations is all above (and assuming there are alternatives on rectifiers market), the Flatpack2 capability of CAN bus comminication is very useful for SDR-based projects and own programms/controls and applications.

There are many sources of the Flatpack CAN protocol (Example). And there are a lot of examples of Arduino and ESP32 CAN communication basics (Example, Example). We have designed our own project, based on captured and reverse-engineered CAN data.

There are few designs of the PCB, which can be found at Ebay and AliExpress. And, surely, you can create your own, matching your applications. One of the considerations found while making PCB design to my own application was the size and PCB capacity, handling required power rating. Brief calculation gives the following theoretical results regarding using 1oz or 2oz layer copper for PCB, which may help you to understand what type of PCB you may need to consider dependent on you application max current:
- 1oz PCB can handle max 15A with temperature variation of +25+30°C on full continuous load
- 1oz PCB with max load up to 25A, temperature +50°C
- 2oz PCB with max load up to 30A, temperature +25°C
- 2oz PCB with max load up to 40A, temperature +40°C

Application rationale:
Originally I was used PCB purchased from Ebay few year ago, made by "xygax". I belive this was the one. Generally speaking there were only few considerations regarding PCB sizes, otherwise it was good. However, with new PA and moving to unified control for SDR, PA and ATU I was desided to make custom 2oz/40A design for the rectifier PCB and connect it to ATUcontrol with MQTT.

In addition to the PBC connector board, there is PCB which suits either ESP32D or ESP32U and very common CAN bus module CJMCU-1051 TJA1051.


ESP32 source code:
The Github-based source code remains closed source. This is due to compliance reasons of using propriatary protocols.
Gerber files:
Connector PCB
Control PCB

Please note, that the above files may not be the latest design, specifically for Control board. If you need latest one, please contact me. There are no any restrictions of reusing those files for you own purposes. Additionally, please keep in mind that published design was built for HAM radio purposes. You will need to modify, potentially both - PCB and code - to make it suitable for other applications, like LiFePo4 battery charger. This project assumes self-soldering, self-wiring, self-calculation of current/voltage limits, self-modification of the code and basic knowledge of C++ programming and VSC/PlatformIO framework.

Application:
There are two different and actual designs of the final application:
1. Control with MQTT. This version is more for use in SDR world and it works with ATUconnect.



2. Web-based Control. This version does not support MQTT, however it has the flexibility of web-based confiruration. User manual can be found here.. This application version is recommended for users outside SDR world.

Both versions are ESP32-based and loaded with closed-source software. If you would like to join the SW development team and get access to the SW sources, please contact me.


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