The Study Of Acoustic Resonance Phenomenon And Its Suppression For High Pressure Sodium Lamps

Responsing to the call of green energy to promote the green light plan, high-frequencyelectronic ballast technology has become an important means for dirving HID lamps. Highpressure sodium lamps, as the representative of HID lights, continue to play their advantagesto become a new kind of high luminous efficiency and long-life lighting source. However,when dirven by high frequency, high pressure sodium lamp can easily produce acousticresonance, like arc lfashing and distortion and instable intensity, which can extinct the light,and even cause the destruction of the vessel.The structural characteirstics, working pirnciple and the boot process of the high-pressuresodium lamps are descirbed in this paper. The structures and the advantages and disadvantagesof electronic ballasts are analyzed and the requirements for high pressure sodium lampelectronic ballast are also illustrated.Based on the general methods and the latest results to study acoustic resonance at homeand abroad in recent years and combined with the gas discharge theory, the extirnsicrepresentation of plasma is discussed to illustrate the generation mechanism of acousticresonance; acoustic resonance detection and suppression methods are systematicallyexpounded and a novel type of acoustic resonance test circuit is put forward.The feasibility of sweep-rfequency circuit is analyzed to discover acoustic resonance. Asweep-frequency inverter circuit is designed based on the chips of CD4046and IRS21091. Bychanging the important parameters of the expeirmental circuit, the rationality of the PWMoutput is confirmed.An experimental light box for acoustic resonance is designed to acquire orthogonalimages of acoustic resonance; varying degrees of acoustic resonance images were comparedand discussed; abnormal lamp voltage and current parameters are detected when acousticresonance occurs.Key research and analysis of theoretical basis and expeirmental results are made onspread spectrum technique in suppressing acoustic resonance. The harmonics of PWM withinvairable rfequencies and magnitudes are energy sources of acoustic resonance. PWM outputspectrum is analyzed; saber simulation and expeirment are made based on SG3525frequency modulation circuit; expeirment are carried on based on sweep-frequency inverter circuit ofrfequency modulation and low-rfequency voltage amplitude perturbation modulation circuit;using sine, tirangle and square waves as the disturbance signal, the sensitivity of perturbationparameters are compared and analyzed on spread spectrum effect.Through a large number of expeirmental data and test waveforms, it is indicated thatspread spectrum technique can effectively reduce the amplitude of the spectrum of excitationsource, disperse the energy of the harmonic power to be lower than the power threshold valueof acoustic resonance, and finally achieve the purpose of suppressing acoustic resonance.