Transcript Family_ISIE06_VF

Pontifical Catholic University of Rio Grande do Sul - PUCRS
A SINGLE STAGE ELECTRONIC BALLAST FAMILY FOR
HIGH PRESSURE SODIUM LAMPS
R. Tonkoski Jr., G. B. Ceccon, A. Bombardieri, G. B. Maizonave,
R. W. Dos Reis, J. C. M. Lima and F. Dos Reis
Abstract — In the recent years many authors are working to obtain single stage HPF electronic ballast for fluorescent and HID lamps to achieve cost reduction
and to comply with international standard requirements. Usually to obtain HPF in electronic ballast for high pressure sodium lamps a Power Factor Corrector (PFC)
is used between the mains and the electronic ballast. In this paper will be reported the study and implementation of two single stage high power factor (HPF)
electronic ballasts for high pressure sodium (HPS) lamps using a LCC filter, one using a half-bridge inverter (HB) and the second one using a full-bridge inverter
(FB). The main idea in this work is to present two simple electronic ballasts topologies with HPF for HPS lamps working with a 220 VRMS mains voltage. Design
criteria and experimental results will be also presented. These topologies present some drawbacks like moderate THD, lamp power limitation once the converter
works as a Buck inverter and it is not an ideal PFC. PF around 0.95 are easily obtained. This paper intends to warn other researchers about these structures
limitation, but may be an interesting option for some applications.
The lamp turns on and off in each semi cycle
Voltage and Current in the output
of the Bridge Rectifier.
Voltage and Current in the mains.
Current Harmonic Content
Injected into the Mains.
Utility Grid Voltage Harmonic Content.
Voltage and Current in the HPS lamp in
a high frequency period.
Voltage (above) and Current in the lamp.
INTRODUCTION
The purpose of this paper is to report the development of two low cost
single stage HPF electronic ballasts for HPS lamps for a 220 VRMS mains
voltage developed for utilization with a smart public illumination system. Each
ballast was implemented using a different converter topology. The design
criteria are presented in the paper for the proposed circuits.
In order to achieve low cost electronic ballast for HPS lamps with HPF a
single stage converter was conceived. The idea is very simple: Once, in high
frequency, the HPS lamps have a resistive behavior, why the electronic ballast
(inverter and LCC filter) can not be connected directly to the full bridge
rectifier? This idea is discussed in this work.
It was studied the possibility of using this concept applied to a half bridge
(HB) inverter. Unfortunately, in this arrangement the half bridge inverter
reduces the available RMS lamp voltage and therefore, restricts the maximum
output power. The full bridge-inverter was also explored in order to increase
the available RMS lamp voltage.
Half Bridge topology.
EXPERIMENTAL RESULTS
Two prototypes, one using the HB topology and another using the FB
topology for 70 W and 250 W HPS lamps respectively were built.
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.
EMI Filter Topology.
Microcontrolled Full Bridge Electronic Ballast Prototype.
CONCLUSIONS
In this paper it was presented two ballast topologies for HPS lamps. It was
described two single stage high power factor electronic ballast for high pressure
sodium lamps using a half and a full bridge inverter. These ballasts presents a
very low cost because it avoids an external PFP.
It was observed that using the Half Bridge topology the necessary voltage to
achieve the lamp full rated power (250 W) with a 220 VRMS mains will never be
achieved, this problem impossibilities the design of this ballast for 250 W HPS
lamps. The half bridge topology is suitable for lamps less than 250 W once the
main restriction is the available RMS voltage. A prototype for a 70 W HPS lamp
with this topology and a second prototype with the full bridge structure for a 250
W HPS lamp were presented.
The behavior of the full bridge topology and the half bridge topology achieved
was similar. The lamp turns on and off in each semi cycle. These re-ignition
periods are attributed to the nonlinear characteristic of the lamp and to DC bus
voltage, which drops to zero every semi cycle.
The phenomenon of the acoustic resonance was not observed, however it was
not the objective of this study to analyze the impact in acoustic resonance. The
crest factor found was not good enough considering fluorescent lamps, however
for HPS lamps this crest factor is not considered critical.
A simple design criteria is proposed, which permits to determine easily the
LCC parameters, using an abacus. The assumed resistive lamp behavior is not
entirely accurate, but is enough to allow a proper lamp ballast design.
In our laboratory, the mains voltage total harmonic distortion was 2.49%, during
the measurements. For this situation, the obtained power factor and total
harmonic distortion were PF=0.98 and THD=19.93% respectively.