THE GEM - 500W [Light&heatsource]

Description

This is a PAR( Photosynthetically active radiation) project based on the high-current controller M4SUBDRV (https://github.com/Juanduino/THE-DIMMER_M4SDRV_V1)The CREE XLAMP LED´s is a very advanced light emitter. They have a huge µmol/watt output. The controller inject current into 4 separate channels (40 amp MAX). 108 LED´s total. 54 BLUE or BLUE/WHITE & 54 RED or fully WHITE. It will run of a 12v 500watt PSU (Power supply). The goal of the project is to make a smart plant grow Raydiator, which controls the light intensity based on temperature sensor input. By making the lamp output PWM and temperature controlled, the final capacity of the lamp depends on °C and by using Metal Core - Sinkpad PCB, the heat transfer from the individual LED is optimized. CC-BY-NC

Details

HEAT CIRCULATION vs LIGHT
Case: Imagine a part of your living space, where you can grow greens all year round, and at the same time use the heat-output to warm up your space. This could not only provide food all year, but also expand the outdoor season by starting sprouts indoor, in a controlled environment, before they are ready to be planted out.

Another mayor benefit by utilizing the radiated heat, is the possibility to fully heat your living space with green energy. This means less foresting for wood to burn. Less Co2 emissions from NOT BURNING WOOD or other carbon-based energy sources. Naturally all this requires a solid environmentally friendly energy infrastructure.

By introducing CAN (Controller Area Network) to the "intelligent" GEM/lamps, if several lamps are connected only a "Master" CAN node will need a connection through either USB or wireless. This means a great deal in a greenhouse scenario, where many lamp all need to be monitored and controlled from a central hub. Likewise only one wireless module in the network is necessary, depending on the case.

UPDATE: The process of finding the best pcb for high current LED´s led me to Metal Core PCB with sinkpad´s. Sinkpad connects the cooling surface of the MCPCB and heat pad on the LED. This gives a x100 performance in heat transfer and thereby optimizing cooling. Literally the LED´s will be mounted more or less directly on the heatsink. The PCB´s has been ordered and I am making the final adjustments to the heatsink.

CREE LED´s

https://www.cree.com/led-components/media/documents/CreeXLampHorticultureFeatureSheet.pdf

Design

The design is starting to manifest.

White LED´s use energy to lite up the full visible spectrum. The Red and Blue only one wavelength(area) and is therefore cooler in use. The difference between the red and blue wavelength is another matter.

For office environment the fully white GEM would be more pleasant for the human eye. In a school scenario the lamps would be part of photon to plant growth process.

The Controller for the lamp has 40 amp rated MOSFET´s (Switches). How fast the controller is able to switch the switches depends on several factors. One main factor is the switching resistance Rds(on) and naturally the frequency of switching. Since the controller inside the lamp is actively cooled by the 60mm fan right next to it, a small heatsink directly on the MOSFETS would make a significant difference.

As seen in above image, the positive power line is fortified with a 1.5mm x 1.5mm busbar (square copper wire). This should handle up to 45 amp. with a temperature rise below 10C. The wire-lugs for the wire going to the PSU is rated at 65 amp.

To connect the lamp(s) to a computer or to each other via the CAN bus, a plug/connector breakout-board is needed. I have been inspired by the Duet3 CAN RJ11 connectors, even though they are large. The advantage of these connectors is the readily available wires (ADSL fast speed), with twisted pairs. The twisted wires reduces noise on the bus, but is not essentiel. The Molex Micro Fit 3.0 connectors will connect to external PWM (4 pin) cooler fans. The power for the fans will come directly from the 12V PSU through a Wago 9amp rated SMD connector.

Project Logs

Collapse logs

BREAKOUT
Juan-Antonio Søren E.P. • 16 hours ago • 0 comments

In order to connect the lamp to a wired connection, a breakout is necessary. The USB power will cutoff if there is power on the 12v rail, to protect the computer motherboard.

The RJ11 CAN FD jack are compatible with DUET3.

The external FAN4 and FAN5 Micro Fit 3.0 connectors has 12v directly from PSU. The PWM signals are independently adjustable. A typical 120mm fan uses 0.5 amp at full power. The power connection for the external breakout is 9amp max.
The 4 pin header on the main shield is for wireless module UART (RX/TX) connection.
Temperature Probe
Juan-Antonio Søren E.P. • 6 days ago • 0 comments

To obtain the best possible control of the LED´s, we need to measure the temperature as close as possible to the LED heat pad. This will be done using a classic E3D thermistor in a cartridge (https://e3d-online.com/products/thermistor-cartridge). The sensor is 15mm long with a 50mm cable w. a good secure connector.
Dimensions
Juan-Antonio Søren E.P. • 01/09/2021 at 14:24 • 0 comments

In order to scale the wire connection to the MOSFET 40amp rating, Ive chose to fit 65 amp power lugs.
Heat exchange
Juan-Antonio Søren E.P. • 01/07/2021 at 18:21 • 0 comments

Heating or cooling the heatsink is entirely dependent on current consumption and ambient temperature.

Looking at the heatsink, it is obvious, when pushing cool air across those fins, the air is gonna heat up. The above heatsink is for the small version 254mm long, 80mm wide, 40mm high.
Wire Shielding
Juan-Antonio Søren E.P. • 01/04/2021 at 13:19 • 0 comments

The LED phases must be soldered to the LED side, since the MCPCB is single sided. To shield of the solder points and wires, some sort of shield is is necessary.
Channeling
Juan-Antonio Søren E.P. • 01/03/2021 at 14:29 • 0 comments

To raise the light up into the enclosure, some sort of air channel is needed. This channel will also serve as mounting bracket for the wooden enclosure. On the LED side, the channel/bracket will provide mounting holes for wire shielding.
GROW AREA
Juan-Antonio Søren E.P. • 01/03/2021 at 10:25 • 0 comments

The Cree XP-G3 LED´s have a illumination angle of 125-130. Subtracting the outer 10% the grow area at 50cm height is 2m x 1m = 3m2. At 1 meter the average µmol/sek. naturally becomes lower, but will illuminate approx. 3m x 3m = 9m2. One of the advantages of LED´s for grow lights is the moderate heat radiation, which makes it possible to get close to the plants without heating up the top leaves, to much. Plants like moderate heat when utilizing the photons to produce plant matter. To achieve the best possible growth, the temperature around the leaves should be regulated. Furthermore it is a good thing to have air flowing across the leaves to evaporate moisture and thereby pull the chain of molecules going all the way down to the roots, where nutrition's are dwelling. The optimal man made system for plant growth will therefore take all these variables into account. The exces heat from the lamps, can be used to provide a optimal temperature inside the growth environment. The heat not used to regulate the growth environment can in turn be used to heat up a living space, it could be stored in eg. water or simply discarded. The trick here is to find the right balance.
Xploring Enclosure V2
Juan-Antonio Søren E.P. • 12/27/2020 at 10:41 • 0 comments
MCPCB - METAL CORE PCB
Juan-Antonio Søren E.P. • 12/24/2020 at 07:09 • 0 comments

Since there is no looking back now, there is only moving forward, MCPCB seems like the only logical choice. Will try to find a way to design the files in Kicad.

From what i gather here and there, no vias (or very few) is allowed.

It´s possible to make it with 2 copper layers. Either with aluminium sandwiched in the middle or as a backing plate.

Im thinking to maintain the fan´s.

Now, having come to the conclusion, that the heat-dispersion (cooling) and thereby the mechanical buildup of the finished design, is fundamentally important for a good and lasting design, the inevitable question arises. There are techniques of which the pcb maker connects the aluminium or copper layer of the metal-core pcb directly to the heat-pad of the high-power LED. This technology has different brand names and probably different ways of achieving the same goal. Now back to the question. There is no question about the advantages of such a direct path for heat to flow. The question is how and how much. If a special tool for the process is needed, cost goes up. Especially for prototypes.

So what´s the plan?

My plan is to do prototypes the regular way of doing Metal-core pcb with a layer between the copper and aluminium. The copper thickness will still be 105µm. This way I will validate the design and at the same time learn from the manufactures doing direct heat-transfer MCPCB pads.
Controller design done
Juan-Antonio Søren E.P. • 12/21/2020 at 23:38 • 0 comments

Added 6amp MOSFET next to the TMC2209 stepper pins (A+/-B+/-), tied to ground. X

Added text rCAN next to CAN termination resistor. Note: The two end-nodes in a CAN network must be terminated with 120ohm resistor.
Added AP2161W (active low) to cut USB power when VIN is applied.

Ready for prototypes!