JPS6125646B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that is driven by an AC power source and generates ozone through silent discharge, and particularly to a device that narrows the discharge gap and makes the discharge period longer than the non-discharge period to increase the power factor of the device. It's a diagram.

Fig. 1 is a diagram showing the basic structure of a conventional ozone generator using silent discharge, and Fig. 2 is a plan view of the electrode part. 1 is a ground electrode, 2 is in close contact with a high voltage electrode 3, and 4 is a discharge gap through which oxygen-containing gas flows, and 1 to 4 constitute a silent discharge electrode system 5. Reference numeral 6 denotes an AC power supply, which generates silent discharge in the discharge gap 4 whose transition to arc discharge is suppressed due to the presence of the dielectric 2, and efficiently converts oxygen-containing gas into ozone.

Figure 3 is an equivalent circuit diagram of a conventional ozone generator, where C _a is the capacitance of the discharge gap 4, 7 is the anti-series Zener diode, C _g is the capacitance due to the dielectric 2, and the silent discharge electrode The discharge voltage characteristics of the system 5 are as follows: Zener voltage V _Z of an anti-series Zener diode (hereinafter simply referred to as diode) 7 is expressed as follows: V _Z =V _s +V _e /2, where V _S is the start of discharge in the discharge gap 4. Voltage V _e : Can be replaced by selecting the discharge extinction voltage of the discharge gap 4.

In addition, in the device to which this invention is applied, C _g is C _a
The discharge period is configured to be several times the value of , and the discharge period is configured to be longer than the non-discharge period.

FIG. 4 is a waveform diagram showing the relationship between the power supply voltage V and the current I, where a shows the sine wave voltage V, and b shows the load current I. During period A, the diode 7 is non-conducting;
That is, it indicates a non-discharge period, and period RO is the period when the diode 7
indicates conduction, ie, discharge period.

As is clear from this figure, when the power supply voltage V reaches its peak value, the diode 7 becomes non-conducting, and when the applied voltage reaches approximately 2V _Z , a reverse voltage V _Z is applied to the diode 7, making it conductive. . Therefore, the load current I is determined by the series impedance of capacitance C _a and C _g during period A, and by the capacitance C _g during period B.
Since it is determined by the impedance of , the waveform changes in two stages as shown in FIG. 4b. However, in either case, the phase of the current is ahead of that of the voltage, and there is a drawback that the power factor is low.

FIG. 5 is an equivalent circuit diagram of a conventional device designed to improve the power factor. 8 is a reactor with an inductance L _P connected in parallel to the silent discharge electrode system 5, and the load current I is the same as that of the silent discharge electrode system 5. It is the sum of the current I _DZ flowing through the reactor 8 and the current I _L flowing through the reactor 8.

6a to 6c show V, I, and
This is a waveform diagram showing the relationship between I _DZ and I _L. Since the load current I is smaller than I _DZ (corresponding to I in FIG. 4b), the power factor is improved.

Figure 7 shows the measured characteristics of the change in power factor when the reactor 8 is connected to the silent discharge electrode system 5, which has a power factor of 30% when the reactor 8 is not connected, and the value of the inductance L _P is changed. In the figure, the power factor is 70
It can be improved to an extent exceeding %. Note that in this actual measurement example, reactance 8 has a resistance component, so the 6th
This is different from the value calculated from the equivalent circuit shown in the figure.

This invention was made for the purpose of further improving the power factor, and instead of parallel reactors, reactors were inserted in series.

FIG. 8 is an equivalent circuit diagram of an embodiment of this invention.
9 is a series reactor with an inductance L _S .

When a reactor 9 is connected in series to the silent discharge electrode system 5, voltage to the load is supplied from the reactor,
Since the voltage is compensated (a voltage higher than the power supply voltage V is applied), the power factor increases. In this case, the voltage V _DZ applied to the silent discharge electrode system 5 and the voltage V _L applied to the series reactor 9 are larger than the power supply voltage V, so from the standpoint of insulation design, these values must be accurately grasped. However, since the equivalent circuit of the silent discharge electrode system 5 is a circuit that includes a Zener diode, which is a nonlinear resistance, it is not possible to analytically determine the voltage and current of each part when a reactor is inserted in series. Therefore, no attempt has been made to use a series reactor.

As a result of experimentally determining the effect of power factor compensation by the series reactor 9, the inventors found that the inductance L _S
The present invention was completed based on the discovery that the power factor could be significantly improved by setting the power factor within an appropriate range.

9a to 9c show the inductance L _S of the series reactor 9 as L _S =1/(2πf) ² C _g (however, f
: Power supply frequency) is a waveform diagram showing the relationship between V, V _L , V _DZ , and I. The specifications of the silent discharge electrode system 5 are C _a :C _g =1:6, V _DZ peak voltage
1.5×2V _Z was selected, the discharge gap 4 was narrowed, and the discharge period B was made longer than the non-discharge period A.
The power factor without reactor compensation is extremely low at around 30%.

It is extremely effective to perform compensation using the series reactor according to the present invention in a device having such a silent discharge electrode system 5. That is, as shown in FIG. 9c,
This is because the load current I deviates from the sine wave only during the non-discharge period A, and the phase shift with the power supply voltage V can also be eliminated.

Figure 10 is a characteristic diagram showing the change in power factor when the value of the inductance L _S of the series reactor 9 is changed. When the value of L _S is slightly larger than the value calculated using the previous equation, the maximum power factor However, in practice, there is not much difference when setting the above calculated value, and on the other hand, the smaller the value of the series reactor, the cheaper it is, so in practice, it is appropriate to set it within the range of -20 to +30% of the above calculated value. It is.

This invention is configured to generate ozone by silent discharge with a short non-discharge period, and the power factor is greatly improved by inserting a series reactor between the AC power source and the silent discharge electrode system. , which has a great practical effect.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of a conventional ozone generator using silent discharge, Figure 2 is a plan view of its electrode section, Figure 3 is its equivalent circuit diagram, and Figures 4 a and b are its power supply voltage. Figure 5 is an equivalent circuit diagram of an ozone generator equipped with a conventional parallel reactor, Figure 6 a, b, and c are waveform diagrams showing the power supply voltage, load current, and current of each part. Fig. 7 is a characteristic diagram showing the change in power factor when the impedance of the parallel reactor is changed, Fig. 8 is an equivalent circuit diagram of an embodiment of the present invention, and Fig. 9 a, b, and c are its power supply. FIG. 10 is a waveform diagram showing the voltage, voltage at each part, and load current. FIG. 10 is a characteristic diagram showing the change in power factor when the inductance of the series reactor is changed. In the figure, 1 is a ground electrode, 2 is a dielectric, 3 is a high voltage electrode, 4 is a discharge gap, 5 is a silent discharge electrode system, 6 is an AC power supply, 7 is an inverse series Zener diode,
9 is a series reactor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A sinusoidal AC voltage is applied between electrodes facing each other through a dielectric and a narrow gap to generate a silent discharge in which the discharge period is longer than the non-discharge period, and oxygen flowing in the space is generated. In a device configured to generate ozone in a contained gas, a reactor is connected in series between the AC source and the electrode, and the inductance L _s of this reactor is 0.8/(2πf) ² C _g <L _S <1.3/(2π
f) ² C _g However, an ozone generator characterized in that f; power frequency C _g ; selected within the range of the capacitance of the dielectric.