High-intensity gas discharge lamp acoustic resonance inhibition method
Technical field
The invention belongs to technical field of electricity, relate to a kind of high-intensity gas discharge lamp acoustic resonance inhibition method.
Background technology
High-intensity gas discharge lamp (also High Intensity Discharge lamp is called for short the HID lamp) comprises that high-pressure sodium lamp, mercury lamp and metal halide lamp, its luminous efficiency and useful life are more than five times of incandescent lamp; Compare with fluorescent lamp, its volume is little, power is big, distribution controls is easy in lighting, so be widely used in lighting fields such as square, megastore, stadiums, process photography, also is widely used in lighting fields such as automobile lamp, projector lamp, rear-projection TV lamp.
Are inductance type ballasts with the matching used ballast great majority of HID lamp in the market, its shortcoming is that volume is big, heavy, power factor is low, loss is big.
Electric ballast has been widely used in field of fluorescent lamps, owing to adopted high-frequency power electronic devices, makes that the ballast volume reduces, weight saving, power factor improve, loss reduces greatly, and the fluorescent lamp luminous efficiency improves, and the life-span is elongated.
Electric ballast makes people expect the electric ballast technology is applied to HID lamp field in the successful Application of field of fluorescent lamps naturally.Yet high-frequency electronic ballast " acoustic resonance " phenomenon occurred when using on the HID lamp, promptly the electric arc wild effect has taken place when high-frequency work the HID lamp.When the HID lamp was operated in the 5kHz-200kHz frequency range, rising and falling tangible light output pulsation can appear and accompany by current/voltage in a lot of frequency ranges.Electric arc may extinguish under some frequency, even causes electric arc tube to burst.The electric arc wild effect of low power metal halide lamp is the most serious.
In order to make the electric ballast successful Application in HID lamp field, the researcher has done a large amount of work, as to adopt ellipse or two ends be the electric arc pipe shell of taper, and the electric ballast operating frequency is carried out frequency modulation(FM), select can steady running frequency window etc.But in the frequency range of 200kHz, still be difficult to overcome the obstacle that " acoustic resonance " brought from number kHz in frequency range.Its reason is that " acoustic resonance " frequency is very responsive to arc tube dimensions, even deviation is arranged slightly, " acoustic resonance " frequency also can produce significant change.Even to same lamp, difference also can produce appreciable impact to " acoustic resonance " frequency during the life-span.
The method of Recent study person's reply " acoustic resonance " can be divided three classes on the electric ballast operating frequency: the firstth, and operating frequency is far below " acoustic resonance " frequency, as low-frequency electronic rectifier with squre wave and dc electronic ballast such as 170Hz, 270Hz, 400Hz; The secondth, operating frequency is far above the frequency of " acoustic resonance ", as the high-frequency electronic ballast of 2.5MHz; The 3rd be operating frequency in the frequency range of " acoustic resonance ", adopt frequency modulation method to avoid " acoustic resonance ".Advantage when when the electric ballast underfrequency, being difficult to give full play to high frequency, the power consumption of power electronic device is big when the electric ballast frequency is too high, heating is serious, efficient reduces, and need adopt devices such as FM circuit even microprocessor that cost is improved when the electric ballast frequency is in the frequency range of " acoustic resonance ".
Summary of the invention
Order of the present invention is, a kind of high-intensity gas discharge lamp acoustic resonance inhibition method is provided, and adopts the method for longitudinal magnetic field to suppress " acoustic resonance " phenomenon.
The technical scheme that realizes the foregoing invention purpose is, add coil at the high-intensity gas discharge lamp two ends and pass through certain electric current, produce the longitudinal magnetic field consistent with lamp arc post axial direction, regulate longitudinal magnetic field intensity by size of current in the change coil, make the magnetic flux density value of electric arc longitudinal magnetic field at an arbitrary position be not less than Bmin (T)=4 * 10
-6* Iarc; Wherein, Iarc is a HID lamp arc current, and unit is A.
Coil can be positioned over the outside or the inside of lamp electric arc tube.Coil can be a permanent magnet, and the magnetic line of force direction that permanent magnet produces is consistent with lamp electric arc arc column axis direction, i.e. longitudinal magnetic field.
Can make lamp electric arc become stable when longitudinal magnetic field intensity reaches certain value, not occur " acoustic resonance " phenomenon when at this moment controlling with high-frequency electronic ballast, thereby make electric ballast simple in structure, cost reduces, and volume reduces, and efficient improves.
Description of drawings
Fig. 1 is a high-intensity gas discharge lamp acoustic resonance inhibition method schematic diagram of the present invention;
Fig. 2 is the magnetic field schematic diagram that method of the present invention produces.
Embodiment
The present invention is described in further detail below in conjunction with drawings and Examples.
At first introduce principle of the present invention:
HID lamp electric arc is plasma.Can know that from the orbit theory of plasma physics charged particle charged particle exists Larmor to circle round magnetic field.In the electric arc arc column of longitudinal magnetic field, the charged particle that is come out by cathode emission will make the shape of arc column be parallel to the magnetic line of force around magnetic line of force rotation.When particle density is very big, can regard the electric arc arc column as fluid, use the magnetohydrodynamics theoretical description.After applying longitudinal magnetic field, electric current line in the electric arc tries hard to remain parallel to the magnetic line of force, when longitudinal magnetic field intensity reaches certain value, electric arc arc column shape remains unchanged, thereby the wild effect of electric arc can suppress with longitudinal magnetic field, even eliminate, this is that the present invention adopts the method for longitudinal magnetic field to suppress the principle of " acoustic resonance " phenomenon.
Suppressing HID lamp " acoustic resonance " phenomenon with the method for longitudinal magnetic field is a kind of new method, does not all have in document at home and abroad and the patent to occur.The schematic diagram of this method as shown in Figure 1.1-HID lamp electrode among the figure, 2-HID lamp electric arc, 3-HID lamp electric arc pipe shell, 4-coil.By certain alternating current or direct current, the sense of current is identical in the last lower coil, can produce magnetic field shown in Figure 2 in coil 4, because the magnetic line of force is axially consistent with electric arc arc column 2, so be called longitudinal magnetic field.When the longitudinal flux field intensity that produces when big by electric current in the coil 4, therefore can regulate longitudinal magnetic field intensity by changing in the coil 4 size of current.When reaching certain value, longitudinal magnetic field intensity can make lamp electric arc become stable.Magnetic flux density value in this recommendation is as follows: electric arc is not less than Bmin (T)=4e-6*Iarc at an arbitrary position.Iarc is a HID lamp arc current in the formula, and unit is A.