CN102833928A - Method for solving problem of high-frequency driving acoustic resonance of high voltage sodium lamp - Google Patents

Abstract

The invention provides a simple method for solving the problem of high-frequency drive acoustic resonance of high-pressure sodium lamps, which works at high frequency, improves light efficiency, saves electric energy, prolongs life, and includes an embedded electronic ballast. A frequency hopping program is added to the frequency conversion controller of the ballast. The method for solving the problem of high-frequency drive acoustic resonance of high-pressure sodium lamps includes the following steps: Step 1, detecting the initial symptoms of acoustic resonance; Step 2, using frequency hopping to break away from the current Working frequency, work to another frequency.

Description

A method to solve the problem of high-frequency drive acoustic resonance of high-pressure sodium lamps

technical field

The invention belongs to the technical field of lighting, and in particular relates to the problem that high-pressure sodium lamps generate acoustic resonance when driven at high frequencies .

Background technique

High-pressure sodium lamps are the same as other gas discharge lamps. Increasing the frequency of the external driving power can improve the light efficiency and achieve the purpose of saving electricity; at the same time, it can also reduce the loss of the cathode and increase the life. However, when the high-pressure sodium lamp is driven at high frequency (10KHz~200KHz), acoustic resonance phenomenon will occur. At this time, the arc bends and breaks, and the lamp goes out or even explodes. In order to avoid acoustic resonance, current high-frequency electronic ballast products are unwilling to choose a working frequency above 40KHz, so that they cannot make good use of the advantages of high-frequency sodium lamps driven by high-frequency.

Contents of the invention

The invention provides a simple and feasible method for solving the problem of high-frequency driving acoustic resonance of high-pressure sodium lamps, which works at high frequency, improves light efficiency, saves electric energy, prolongs life.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: provide a method for solving the problem of high-frequency drive acoustic resonance of high-pressure sodium lamps, including embedded electronic ballasts, adding frequency hopping to the frequency conversion controller of the electronic ballasts program, the method for solving the high-frequency drive acoustic resonance problem of high-pressure sodium lamps includes the following steps:

Step 1, detecting the initial symptoms of acoustic resonance;

Step 2, use frequency hopping to break away from the current working frequency and work on another frequency.

Further, the sampling period detected in step 1 is on the order of tens of microseconds.

Further, the new operating frequency in the step 2 is determined by the base frequency Fb and a frequency hopping coefficient k, that is, the new operating frequency is F=Fb(1+k), where the frequency hopping coefficient k is a set of cured integers Percentage, non-uniform arrangement, sequential value, circular link.

Further, the frequency hopping coefficient k is the following set of numbers: 5%, 11%, 20%, 31%, 23%, 14%, 7%, 0%.

Further, the step 1 of detecting the initial symptoms of acoustic resonance includes detecting current, voltage and power values.

Further, the detection data in step 1 is filtered.

High-pressure sodium lamps are driven by electronic ballasts, and their operating frequency is also determined by electronic ballasts. The invention enables the electronic ballast to work at a frequency that does not cause the high-pressure sodium lamp to generate acoustic resonance, and realizes high-frequency (above 100KHz) driving of the high-pressure sodium lamp.

The key technology adopted by the present invention to realize the non-resonant high-frequency drive is the frequency hopping technology, that is, to change the current operating frequency immediately and greatly when the acoustic resonance is detected, so that the high-pressure sodium lamp can operate at another non-resonant high frequency The frequency band works stably. Acoustic resonance has great randomness, even for high-pressure sodium lamp products of the same manufacturer and specification, the frequency of acoustic resonance is not the same. But there is a common law, that is, acoustic resonance is distributed according to the frequency band, and resonance may occur at a frequency close to a certain frequency where acoustic resonance occurs; the second is that the width of the acoustic resonance frequency band (several KHz) of high-pressure sodium lamps is much smaller than that of Non-resonant frequency band, that is, after skipping this narrow resonant frequency band, there will be a relatively wider non-resonant frequency band. The key feature of the present invention is to skip adjacent high-risk frequency bands and find a safe working frequency when acoustic resonance is detected to occur soon.

Since the current, voltage, and power loaded on the high-pressure sodium lamp will change abnormally when the acoustic resonance occurs, it can be judged that an acoustic resonance event may be about to occur by detecting these three or one of them. The action time of acoustic resonance is above tens of milliseconds, as long as the sampling period is in the range of tens of microseconds, every possible acoustic resonance phenomenon will not be missed.

The invention has the beneficial effects of realizing the safe operation of the high-pressure sodium lamp in the high-frequency state within 200Khz, improving light efficiency, saving electric energy, and prolonging the service life of the high-pressure sodium lamp. the

Description of drawings

Figure 1 is a schematic diagram of the electronic ballast structure;

Fig. 2 is a flow chart of frequency hopping;

Fig. 3 is a schematic diagram of frequency hopping program processing.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The present invention needs to be used in an electronic ballast adopting embedded control, and its core components are preferably DSP or single-chip microcomputer with timer, AD converter, PWM output controller and the like. The electronic ballast has conventional rectification, PFC (power factor correction), constant current or constant power control of the load (high pressure sodium lamp), DC/AC frequency conversion control. The present invention is added therein as a link of frequency conversion control.

The realization method of the present invention is to continuously detect the acoustic resonance phenomenon during normal operation, once the initial symptom of the acoustic resonance is detected, it immediately jumps to work at another frequency. The specific method is that the embedded controller continuously reads the output (that is, the voltage and current loaded on the sodium lamp) with a sampling period of tens of microseconds. In order to prevent accidental errors caused by interference from causing wrong judgments, the sampling data must be filtered. . If the detected voltage or current or power deviates a lot from the normal value (more than or less than 30% of the rated value), it is considered that it has entered the initial stage of acoustic resonance, and immediately adopts the frequency hopping method to leave the current operating frequency and work to on another frequency that is farther away. The new working frequency is determined by the base frequency Fb (initial working frequency, such as 120KHz) and a frequency hopping coefficient k: F=Fb(1+k). The frequency hopping coefficient k is a set of solidified integer percentages, arranged non-uniformly, taking values sequentially, and linking circularly. The operating frequency can jump at different intervals, up to 1.5 times the base frequency, and finally return to the base frequency.

Figure 1 shows a schematic diagram of the structure and principle of an electronic ballast that can solve the problem of high-frequency acoustic resonance. The whole circuit is controlled by DSP, and of course other single-chip microcomputers or embedded processors can also be used. DSP controls the APFC (Active Power Factor Correction) circuit to achieve a power factor close to 1; controls the BUCK circuit to provide a higher voltage during the ignition phase, and realizes constant power drive for high-pressure sodium lamps during normal operation. The DC/AC conversion is realized by controlling the full-bridge circuit (half-bridge circuit is also effective), and the change of a wide range of arbitrary frequencies (such as within 400KHz) is realized by software, which is also the basic condition for realizing frequency hopping. By detecting the voltage and current loaded on the high-pressure sodium lamp, the ignition process monitoring, constant current regulation in normal operation, and acoustic resonance symptom detection are realized.

Figure 3 shows the specific processing flow of acoustic resonance detection and frequency hopping. This program can be inserted into any position of the main loop program. "Frequency conversion delay flag = 1" in the figure indicates that the frequency hopping process has just been performed, and it is still waiting for a stable stage, and no new acoustic resonance diagnosis is performed at this time. This delay is several seconds, set "frequency conversion delay time = n" at the beginning of frequency conversion, and count down this value in the timer interrupt processing program. When the frequency conversion delay time = 0, it indicates that the delay is over, and at this time, the frequency conversion delay flag = 0.

In the case of "frequency conversion delay flag = 0", the acoustic resonance detection is carried out continuously. In the acoustic resonance detection process, the current voltage and current are read from the memory storing the latest voltage and current, and the value is stored by the AD interrupt service program and processed by filtering. Judging by the voltage, current, and calculated power whether there is an abnormality, that is, the acoustic resonance phenomenon. If any of these three data is detected to be abnormal (filtering is required), it means that the symptoms of acoustic resonance have occurred and the frequency conversion process should be performed immediately.

When frequency hopping control is performed again, the new frequency is determined through a circular table, which stores a set of non-uniform percentage coefficient values, and the value increases from small to large, and then from large to small, and returns to the base frequency. The calculation formula is: F=Fb(1+Ki%), Fb is the fundamental frequency, such as 120KHz. The length of the array is 8 or 16, and a pointer i modulo 8 or modulo 16 points to the position of the current coefficient Ki. Take 8 coefficients as an example: 5, 11, 20, 31, 23, 14, 7, 0, which are a set of verified data. It should be noted that it is not necessary to use the method of obtaining values from the table to realize frequency hopping control, and the method of formula calculation can also be used; the method of using the table to obtain values is not limited to the array of modulo 8 or modulo 16.

The above is only an example of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or process transformation made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technical fields, All are included in the scope of patent protection of the present invention in the same way.

Claims (6)

1. method that solves high-pressure sodium lamp high-frequency drive acoustic resonance problem; Comprise the embedded electronic ballast; It is characterized in that in the frequency-variable controller of electric ballast, add the frequency hopping program, the method for said solution high-pressure sodium lamp high-frequency drive acoustic resonance problem may further comprise the steps:

Step 1, the initial stage symptom of detection acoustic resonance;

Step 2 adopts the frequency hopping mode to break away from current operating frequency, on another frequency of working.

2. the method for solution high-pressure sodium lamp high-frequency drive acoustic resonance problem according to claim 1 is characterized in that, the sampling period of detecting in the said step 1 is tens of microsecond levels.

3. the method for solution high-pressure sodium lamp high-frequency drive acoustic resonance problem according to claim 1; It is characterized in that operating frequency new in the said step 2 confirms that by fundamental frequency Fb and a frequency hopping coefficient k promptly new operating frequency is F=Fb (1+k); Wherein the frequency hopping coefficient k is one group of whole percentage that solidifies; Non-homogeneous arrangement, order value, circular linkage.

4. the method for solution high-pressure sodium lamp high-frequency drive acoustic resonance problem according to claim 3 is characterized in that, said frequency hopping coefficient k is with next group number: 5%, 11%, 20%, 31%, 23%, 14%, 7%, 0%.

5. the method for solution high-pressure sodium lamp high-frequency drive acoustic resonance problem according to claim 1 is characterized in that, the initial stage symptom that said step 1 detects acoustic resonance comprises detection electric current, voltage and performance number.

6. the method for solution high-pressure sodium lamp high-frequency drive acoustic resonance problem according to claim 1 is characterized in that, the detection data in the said step 1 are through Filtering Processing.

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