Study On Electronic Ballasting Techniques For High Intensity Discharge Lamp

High intensity discharge (HID) lamp , with high luminous flux and high efficiency and long life and small discharge tube , has been the new lighting source with powerful competitiveness .The coil inductance ballast, with the disadvantages of larger size and noises and flicker, can not arrive at the expectation of green-lighting .Along with the development of power electronics and the knowledge of HID lamp , the electronic ballast, based on high frequency conversion , come into research , but HID lamp operating at high frequency gives birth to acoustic resonance easily, like arc shrink and distortion and instable intensity , which can wink the light, and even cause the destruction of the vessel.The scheme of gas discharge and the micro motion and macro characteristics are studied in this paper, and the eigenfunctions of plasma resonance of HID lamp are deduced in detail, so as to find out the exciting mechanism and crucial factor of the acoustic resonance in plasma of HID lamp.The characteristics of arc and acoustic wave and electrics of acoustic resonance ,the extrinsic representation of plasma , are researched , and the general techniques for suppressing acoustic resonance are also concentratively analyzed , the applied chacarteristics of many kinds of frequency modulation and their spectrums are mainly discussed in the paper.Pulse width modulation are used both in two topological stages of HID electronic ballast , the input stage is Boost circuit with active power factor correction , the output stage is the bridge inverter . The harmonics of PWM with invariable frequencies and invariable magnitudes are energy sources of electromagnetic interference and acoustic resonance.The relationship of input current harmonics and power factor is analyzed , the active power factor correction technique is concluded , and then the novel reformation and frequency-varying technique and self-oscillation circuit are proposed for designing the APFC circuit to meet the practical application .Based on the conclusion that the excition of acoustic resonance should have appropriate frequency and enough energy and the electromagnetic interferences are producted by harmonics , the technique of spread spectrum is proposed to spread the harmonic frequencies broader , so as to reduce the total harmonic distortion of input current, and decrease the electromagnetic interference , and to avoid the driving signal for HID lamp to be standing waves in some invarable frequencies , so as to suppress the acoustic resonance.The chaotic phenomena and characteristics in Boost circuit and plasms and their control methods are discussed in this paper, a chaotic control approach , resonant parametric perturbation , is proposed to weaken and even eliminate the chaotic motion , and get continuous and broader spectrums at the same time .Finally , chaotic control techniques are taken for Boost circuit and inverter with different resonant parameters, the real time and online chaotic controls are realized . More frequency components are obtained to spread the PWM harmonic frequencies over a broader band , and decrease their quasi peak values . The driving frequency is maken to take a nonlinear swing about a central frequency , so as to reduce the average amplitude values of the harmonics .The chaotic modulation circuit is very simple , can meet the need of practical application . It is shown by experimental data and testing waves that the chaotic modulation can decrease efficiently the PWM harmonics, reduce the electromagnetic interference, and suppress the acoustic resonance in HID lamp.