Goal:

The goal of this project was to design a Frequency Controlled LED Lighting System that could control five lighting fixtures using power-line communication techniques. This project was a proof of concept project with the intent to show that multiple control signals could be coupled to a 120 V power line main and be used to control multiple devices connected to that line.


System Design:

Graphic User Interface(GUI): The GUI was designed to allow the user to control the frequency and amplitude of the signals.
Microcontroller: The Arduino MEGA 2560 was used to interface with the AD9850 signal modules. Code was written in C++.
Signal Generators: AD9850 signal generator modules used to generate five sinusoidal signals. Amplitude controlled with DC voltage generated from DAC.
Digital to Analog Converter (DAC): DC voltages were generated using RC low-pass filters to convert PWM signals generated by the Arduino into unregulated DC voltages.
Line Trap: Parallel resonant circuit used to direct signal energy on power line towards the LED lighting fixtures.
Power Supply: Generated ±15V used to operate summing amplifier.
Summing Amplifier: Designed using Texas Instrument’s TLE2081 Operational Amplifier(Op-Amp). Used to sum and amplify the signals generated by AD9850 signal generator modules.
Coupling: Protected sensitive electronics by using 33nF high voltage capacitors to attenuate 60Hz 120V from power line main.
Acrich3 Integrated Circuit (IC): Features a power factor greater than 0.97, an analog input for linear dimming capabilities, and connects directly to AC power line without an AC/DC converter or LED driver.
LED Lighting Fixtures: Each LED lighting fixture was comprised of a coupling capacitor, signal filter, half wave rectifier, and an Acrich3 IC. The rectified signal was used to control the dimming pin on the Acrich3.

 

System Block Diagram

 


LED Lighting Fixture Circuit Design


What We Learned/Future Improvements:

Signal Attenuation: We found that using five signal generators and amplifying each signal before coupling the signal into the 120V power line main caused signal attenuation. We determined this was due to the outputs of the Op-Amps driving each other. We solved this problem by using a single op-amp in the summing amp configuration.  The ±15V limit of the op-amp limited how much we could amplify each signal before the signals would clip.

One future improvement would be to use a single signal generator capable of generating all the signals from a single output. This solution would eliminate many of the problems we encountered using multiple signal generators. This solution would also eliminate the problems encountered using multiple op-amps.

Passive Filters Vs Active Filters:  Simplicity and cost were two main design constraints for this project. We decided to use passive filters on each LED lighting fixture for this reason. This eliminated the need to use op-amps on each LED lighting fixture. This also eliminated the need to have a power supply on each LED lighting fixture. We determined that switching to active filters may have been the most cost-effective way to address the signal attenuation problem we encountered. This solution would allow for amplification of the attenuated signals while eliminating the need to purchase an expensive signal generator.


Project Pictures:

LED Lighting Fixtures and Signal Generators


Testing Acrich3 IC and LEDs


Graphic User Interface


Project Poster