Abstract – This work reports the study and hardware implementation of a dimmable electronic ballast for high pressure sodium lamps, and a microprocessor-based system for control and energy measurement for this ballast, which uses a power line communications system to send and receive status and commands from another ballasts plugged in the same mains subcircuit. These ballasts are connected in the topology of a logic network, one of them being defined as the master of the subcircuit, and the others as slaves. The master unit distinguishes from the slaves by the additional communications system, which works through a cell phone, and enables the wireless connection to a PC-based central supervisory system. This way, any locale or town becomes able to control its entire main lighting system, in addiction to the obtainment of more accurate data about energy billing, which together with the ability to control luminosity and the better power factor, will result in financial and energetic economy.

THE ADOPTED INVERTER TOPOLOGYThe power stage of the circuitry is accomplished by one full bridge

inverter and a filter of the type series LC, parallel C. This kind of resonant filter allows to limit the current through the lamp by the series capacitor Cs and the L inductor, at the same time performing the lamp ignition, with the high voltage developed at the Cp capacitor terminals, which is connected in parallel with the lamp.

THE POWER METERThe power meter circuit is used to measure the power absorbed by the

lighting device and to protect the circuit, allowing it to turn off in case of overload. The calculation of the instant power in a circuit is made by the product of instant voltage and current.

THE POWER LINE COMMUNICATIONS SYSTEM In order to accomplish the communication of the various ballasts with

the sub-central, the mains power line was used as physical media for data transmission, hence eliminating the need of an additional physical network. The development of a PLC (Power Line Carrier) was achieved, using only basic components, as passive elements and logical ports. Communication is established by modulation, transmission and demodulation of the concerning data.

THE SUPERVISORY SYSTEMThe purpose of this mobile telephony system is to develop a supervisory

system capable of controlling all the street lighting system of a city. Toward this end, it is necessary to structure the central connection to the master ballasts, and by this means, command the slave ballasts. The figure illustrates the supervisory software developed to coordinate the whole system.

Implemented ballast prototype

Block diagram of the performed operations

Interface of the supervisory system

Block diagram of the electronic ballast (master unit)

Pontifical Catholic University of Rio Grande do Sul - PUCRSINTEGRATED SYSTEM FOR INTELLIGENT

STREET LIGHTINGG. B. Maizonave, R. Tonkoski Jr., A. Bombardieri, G. B. Ceccon, R.R.N. Souza,

R. W. Dos Reis, J. C. M. Lima and F. S. Dos Reis

The developed data reception circuit

EMI Filter Topology.

Sent (above) and decoded (below) signals

The developed data transmission circuit

Full bridge ressonant inverterInput Voltage and Current

The SMS Control Strategy

Tasks accomplilshed by the microcontroller

THE DIGITAL CONTROL CENTRAL

The next illustration displays, as a block diagram, the way by which the electronic ballast’s design is structured, and how the control unit integrates this system. The slave units have similar construction, lacking only the connection to the cell phone.

A conventional SMPS power line filter with differential and common mode mitigation paths was used. The EMI Filter topology used is presented below. Usually a capacitor between the line and the filter is used, in this project the input capacitor was suppressed once it will block the PLC communications between the other units. The experimental results are presented for the FB topology, since for the half bridge topology the results obtained are similar.

CONCLUSION The present paper suggests a very attractive design of electronic ballast for 250 W high pressure sodium lamps. In addition to the achieved high power factor (0.98 at nominal power), the proposed model is based on an extremely simple topology, in which the main concern was providing low cost. A huge communications network was developed in order to allow total control of the system from the supervision central. Using this central it is possible to individually control every street lighting network unit, determinate the timetable of its activations, deactivations and consumption control, as well as measuring and recording the individual and the complete system’s energy consumption.