Urban Farming

The topology that provides the utmost flexibility for controlled environmental agriculture (CEA) LED lighting systems is a primary constant voltage followed by a DCDC buck stage.

• Primary stage: 
  For power stages between 20W to 80W a single-stage PFC/Flyback with constant voltage output is commonly used. For power ratings above 80W, a two-stage PFC + LLC topology is the preferred choice.
  
  
• Secondary stage: 
  Depending on the number of channels, several buck stages can be used in parallel on the secondary stage. Alternatively, to the incumbent DCDC buck converters, Infineon is offering a lower-cost alternative based on smart linear controllers that can optimize the system efficiency.

The configurable XDPL8218 single-stage PFC/Flyback controller combines a very high power factor and low THD with low standby power. It enables low system costs due to the high level of integration including the high voltage start-up cell.

The ICL5102 PFC + LLC integrated controller enables dimming levels down to 1%. With a universal input ranging from 70V to 325V, it delivers outstanding power quality and the highest efficiency for LED lighting systems.

High power LEDs that operate close to safe extra-low voltage (SELV) limits need a high safety voltage margin. This is provided by the ILD8150, an 80V DC-DC converter IC with hybrid dimming down to 0.5%. Alternatively to DCDC buck LED driver IC smart linear controllers can be used to reduce system BOM. BCR601 has an active headroom control to minimize the voltage overhead for all LED strings. That feature helps to increase the efficiency of a similar range of a DCDC buck converter. For additional strings BCR602, a very low-cost linear controller can be deployed.

In vertical farming CoolMOS™, high-voltage SJ MOSFETs such as the CoolMOS™ P7 family address LED lighting by offering the highest efficiency and best price-performance.

Once the conditions within the plant are clear, advanced climate control is needed to make the needed adjustments. As both manpower and energy resources within urban areas are costly goods, systems need to run very efficiently and reliably. With a high level of automation of the PFAL, the HVAC ventilation, pumps and valves need to seamlessly integrate into the overall automation system of the farm.

With the Infineon HVAC portfolio, the basis for adjusting different parameters is given. Whether the valves, pumps, or the actual airconditioning unit. Infineon enables the highest efficiency and robustness based on leading system power management. In addition, the highly integrated motor control solutions of the iMOTION™ family enable variable speed adjustment for optimally running parts of the HVAC to adapt to the exact needs of the environment in the urban farm. Protected low and high side switches for hydraulic or pneumatic management of HVAC pumps enable reliable operations.

Indoor farming is a type of agriculture in buildings, containers or greenhouses and is a closed, controlled system that is independent of the seasons and sunlight. A bright and flexible rack lighting solution that maximizes the grow space for higher crop yields and better quality is needed for this use case.

Broad-spectrum LED lighting solutions illuminate all types of vertical racks and grow tables with precise and uniform light on the plant canopy. Multi PPF output levels and built-in dimmability enable the exact and dynamic PPFD control over each of the plant growing stages. LED lighting solutions need to offer a nature-given spectral quality of LED light while saving energy costs. No shadow installation of greenhouse supplemental, indoor high-bay lighting or indoor sole-source lighting is required. Semiconductors need to enable small form factor designs driven by highly integrated LED driver IC solutions.

Detachable power supplies for lighting are used to be remotely mounted on the side of the racks. The power supplies need to meet high-performance requirements, full-cycle top-lighting with the power to scale from vegetative growth to higher light intensities in bloom.

Secure remote control functionalities for dimming via NFC or web applications / IoT is required. Real-time control and scheduling features for individual channels of the LED driver and well as advanced software-over-the air updates to schedule different light treatments.

Urban farming (CEA) is significantly different from traditional agriculture due to its use of innovative technology. It is independent of weather conditions. Urban farms mainly cultivate vegetables, leaf lettuces, herbs, tomatoes and strawberries, and in addition microalgae under controlled or semi-controlled conditions.                                                                                                                             

• Vertical Farming: the space for planting crops is extended by growing plants in kind of multilayer storage systems
• Rooftop Farming: flat roofs are used to install greenhouses. Those operate either with sunlight or with LED lighting.  
• Outdoor Farming: free urban green spaces, brownfield sites and flat roofs as used to grow plants
• Indoor Farming: an indoor space with highly-controlled systems that make use of LED lighting instead of sunlight and hydroponics instead of soil. Alongside hydroponics, its main methods are aquaponics and aeroponics.

Control systems in urban farming include:

• Dynamic, turnable LED plant light for full season light supplementation including variable spectra to be used for e.g. for far-red end-of-day light, UV light supplementation, night-interruption
• Sensor-based HVAC climate control including plant conditions of temperature and humidity
• Automated hydroponic watering system (soilless) with water level indicator
• Automated over-the-air software updates of control systems
• Use of renewable energy sources and energy recovery via heat-exchangers / heat pumps

Challenges in controlled-environmental agriculture:

The high grade of automation results in high initial investment costs. In addition, the implemented technology needs to be maintained and kept up to date which results in a high need for robust and scalable solutions.

Besides that—mainly due to the implemented automation and LED lighting, there is a high operating cost due to high electrical demand. The energy efficiency of all subsystems is key to reduce those operating costs. The use of renewable energy is expected to solve one part of this discussion point. Innovative future technology developments in LED lighting, motor control, automation systems, and energy storage need to be in place to reduce the energy consumption of the overall system.

Due to high investment costs, a stable return on investment is expected by the farmers. UPS systems ensure continuous power supply to lighting systems and well-functioning pumps in the event of problems with the electric power grid.