JPH0127963B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ozone generator using silent discharge.

Ozone generators using silent discharge are the only means of producing ozone on an industrial scale, and have been used to sterilize and deodorize tap water, as well as decolorize, deodorize, and make wastewater pollution-free. is required.

Silent discharge is a streamer-like discharge obtained by placing an insulator between opposing electrodes with a gap between them and applying a high AC voltage between the two electrodes. Oxygen or oxygen-containing gas is passed through the discharge gap. Ozone is obtained by flowing it.

The power sources that have been put into practical use for this ozone generator include combinations such as an induction voltage regulator, a step-up transformer, an AC power regulator, a step-up transformer, a voltage rectangular inverter, a step-up transformer, a current rectangular inverter, and a step-up transformer. Each is provided with associated circuitry for the application.

Regarding the operation of these power supply units, the single line diagram of the electrical system in Figure 1 and the explanatory diagram of voltage and current waveforms in Figure 2 respectively show (a) induction voltage regulator - step-up transformer, and (b) AC power. The regulator-step-up transformer, (c) voltage rectangular inverter-step-up transformer, and (d) current rectangular inverter-step-up transformer are shown in this order. In FIG. 1, 3 is an ozone generator, 4 is a power factor compensation reactor, and 5 is a series reactor.

In the combination of the inductive voltage regulator 1 and the step-up transformer 2 shown in Fig. 1a and Fig. 2a, the ozone generator 3 is a capacitive load whose value differs between discharge and non-discharge. As shown in the ozone generator applied voltage waveform 9 and ozone generated current waveform 10, the current 10 is distorted and contains many harmonic components, and even the power factor compensation reactor 4 cannot compensate 100%.

In such power supply sections, harmonics of the current cause damage such as flickering in large devices.

Since the amount of ozone generated is controlled by voltage changes, the control width is small.

Since the increase in input power is due to a rise in voltage, it becomes impossible to input a large amount of power due to the withstand voltage of the insulator (glass), leading to an increase in the size of the equipment.

There are drawbacks such as.

In the combination of the AC power regulator 6 and step-up transformer 2 shown in FIGS. 1b and 2b, a protective series reactor 5 is connected between the step-up transformer 2 and the AC power regulator 6, and the AC power The regulator 6 conducts the thyristors connected in antiparallel by varying the firing phase for each half-wave of AC, and the ozone generator applied voltage waveform 9 and the ozone generator current waveform 1 during operation.
0 as shown in FIG. 2b. In such a power supply section, in addition to the problems of flickering, narrow voltage control width, and inability to input large amounts of power as in the case of using the induction voltage regulator 1, there are also problems with the power supply from the ozone generator 3. In order to prevent reverse voltage, it is essential to increase the reverse withstand voltage of the control element (thyristor), that is, to make it 1.5 times that of a normal resistive load, so current circuits are limited to 400V. Moreover, as is clear from FIG. 2b, the effective value shown by the ozone generator current waveform 10 is larger than the peak value of the converter output voltage waveform 11 of the power supply section, and the peak value of the ozone generator applied voltage waveform 9 Since this is small, it is necessary to increase the excitation capacity of the step-up transformer 2, and the apparent capacity becomes large compared to the amount of ozone generated. Furthermore, because a power factor compensation reactor cannot be used due to circuit operation, reactive power is large, and the power supply capacity must be large.

The voltage rectangular inverter 7 in the combination of the voltage rectangular inverter 7 and the step-up transformer 2 shown in FIG. Widely used as an uninterruptible power supply. This ozone generator also has a series reactor 5,
It can be used as a power supply section of the ozone generator 3 by applying a power factor compensation reactor 4 and a protection circuit (not shown). Since it is possible to control the voltage and frequency, it has many advantages such as a wide control range and the ability to input large amounts of power, but it has the disadvantage of being expensive, which is the most difficult to accept as an industrial device, and it does not generate ozone. This will increase the total cost of the device. Furthermore, there is also the problem that the power conversion efficiency decreases with respect to a capacitive load such as an ozone generator.

The combination of the current rectangular inverter 8 and the step-up transformer 2 shown in FIG. 1d and FIG. is not necessary either. Therefore, the circuit configuration is also simple. Like the voltage rectangular inverter 7, this current rectangular inverter 8 is also most commonly used for driving a motor, and has the same effect as the voltage rectangular inverter 7 as a power supply section of an ozone generator. However, since it is inherently unstable as a power source, it is necessary to give sufficient consideration to the configuration of the protection circuit and control circuit for actual operation. That is, there are drawbacks such as the need for special circuits for the generation of abnormal voltages, abnormal frequencies, disconnection of damaged ozone generator tubes, restart conditions, etc.

The present invention eliminates the drawbacks of the conventional power supply section of an ozone generator, provides stability as a power supply section, can input a large amount of power, and provides an inexpensive power supply section of an ozone generator. With the goal.

According to the present invention, this object is achieved by configuring the power supply section of the ozone generator with a pulse width controlled transistor inverter and a matching circuit having at least an inductance.

Next, the power supply section of the embodiment of the ozone generator according to the present invention will be explained with reference to FIGS. 3 to 5. In FIGS. 3 to 5, parts corresponding to those in FIGS. 1 and 2 are given the same reference numerals.

FIG. 3 shows a single line diagram of the electrical system of the ozone generator, and FIG. 4 shows a circuit configuration diagram of the transistor inverter in FIG. 3. In FIG. 3, a pulse width controlled transistor inverter 12 is connected in series with a matching circuit 13, a step-up transformer 2, and a grounded ozone generator 3. Input from a commercial power source is converted into a pulse voltage by a transistor inverter 12, and this output is boosted by a step-up transformer 2 through a matching circuit 13 that mainly uses a reactor to improve current limiting and power factor. is applied to the discharge gap between the high voltage electrode (not shown) and the ground electrode (not shown) of the ozone generator 3. The series reactor of the matching circuit prevents inrush current to the capacitive load of the ozone generator, and at the same time supplies current to the ozone generator using the electromagnetic energy of the reactor during the period when the inverter output pulse is stopped, and the parallel reactor supplies current to the ozone generator. Compensates for the leading phase current. The transistor inverter 12 of the pulse width control type has a rectifier circuit 14 and an inverter circuit 15 configured from diodes from the power supply side, as shown in the schematic circuit configuration in FIG.
The main circuit, which reaches the load side via the main circuit, includes a protection circuit 16, an amplifier circuit 17, an arithmetic circuit 18, a current detector 19, and a smoothing capacitor 20 connected in parallel to the main circuit. In this transistor inverter 12, when the power is turned on, a stable DC voltage is obtained by the rectifier circuit 14 and the smoothing capacitor 20. On the other hand, if the input settings shown by the dashed-dotted line arrows are made to the arithmetic circuit 18, the arithmetic circuit 18 will be able to
The pulse width is determined, and the output thereof is supplied as a base current of a transistor via an amplifier circuit 17 to an inverter circuit 15 connected in a bridge as shown by the diagonal arrow. As a result, an inverter output voltage waveform 11 is generated, as is clear from FIG. 5, which shows the voltage and current waveforms of the transistor inverter 12 in FIGS. 3 and 4.
Whether the output voltage waveform 11 is as set is fed back to the arithmetic circuit 18 via the protection circuit 16. In addition, the protection circuit 16 monitors whether the so-called arm current detected by the current detector 19 is within the capacity of the transistor or whether the relationship between the output voltage and frequency is normal, and in the case of an abnormality, a stop signal is issued. It will be done. Note that, in the input setting indicated by the dashed-dotted line arrow, the frequency and pulse width (voltage) are determined by the arithmetic circuit 18 so that the power becomes linear.

In FIG. 5a, transistor inverter 1
2, that is, the inverter output current waveform 21 for the converter output voltage waveform 11 representing the inverter output voltage at time T _p , the output current waveform 21 for the output voltage waveform 11 is The period indicated by t ₁ is determined by the current supplied from the power supply, and the periods indicated by t ₂ and t ₃ are determined by the current flowing from the series reactor of the matching circuit 13 to the ozone generator 3 and the feedback current from the ozone generator 3. . In other words, when the relationship between T ₀ , t ₁ , t ₂ , and t ₃ is changed, the voltage waveform applied to the ozone generator 3 changes in a complicated manner, and the relationship between the series reactor of the matching circuit 13 and the capacitance of the ozone generator 3 changes in a complicated manner. Even if the relationship is changed, the voltage waveform applied to the ozone generator 3 changes.
That is, the former is the determining factor of the voltage-frequency characteristic curve at no-load, and the latter is the determining factor for the optimum waveform after determining the voltage-frequency characteristic curve. FIG. 5b is an explanatory diagram of the voltage waveform applied to the ozone generator 3, and the output from the transistor inverter 12 in FIGS. The device is configured to obtain an applied voltage. The applied voltage waveform is preferably a sawtooth waveform connected by straight lines. This means that when looking microscopically at the streamer-shaped discharge in an ozone generator, the discharge duration is several microseconds or less, and if the power supply frequency is up to several kilohertz, the applied voltage waveform will affect the ozone generation efficiency. If the influence can be ignored and the peak voltage value is stable, it is sufficient to choose a waveform that allows the equipment to operate efficiently. In other words, if the applied voltage waveform of the ozone generator is applied voltage waveform 9 as shown in Fig. 5b, the crest factor is large, and the amount of ozone generated can be large compared to the capacity of the equipment, reducing the capacity of the equipment. becomes easier.

According to the present invention, since voltage control in the power supply section of the ozone generator is performed by a pulse width controlled transistor inverter, only a diode is required as a rectifier circuit, and the power supply section can be constructed at an extremely low cost. Additionally, since transistors with high operating speeds are used, they can respond extremely quickly to load fluctuations and input signals. In addition, since the arithmetic circuit and the protection circuit are configured taking into consideration the characteristics of the ozone generator, the reliability of the ozone generator can be improved. In addition, the matching circuit can be made inexpensive by using a reactor as its main component, and the sawtooth output waveform increases the crest factor, improving the power factor and greatly increasing the capacity of the step-up transformer and inverter. To provide a low-cost, high-performance ozone generator that reduces the power loss of the equipment, significantly reduces equipment equipment and operating costs, and expands the field of ozone use. be able to.

[Brief explanation of drawings]

Fig. 1 is a single line diagram of the electrical system of the conventional ozone generator, Fig. 2 is an explanatory diagram showing voltage and current waveforms in the electrical system of the ozone generator shown in Fig. 1, and Fig. 3 is a single line diagram of the electrical system of the embodiment of the ozone generator according to the present invention, No. 4
5A is an explanatory diagram showing voltage and current waveforms in the power supply section of the device shown in FIGS. 3 and 4; FIG. FIG. b is an explanatory diagram showing the waveform of the voltage applied to the ozone generator by the apparatus shown in FIGS. 3 and 4. FIG. 2...Step-up transformer, 3...Ozone generator, 9
... Ozone generator applied voltage waveform, 11 ... Inverter output voltage waveform, 12 ... Transistor inverter, 13 ... Matching circuit, 14 ... Rectifier circuit, 15 ... Inverter circuit, 16 ... Protection circuit, 17 ... Amplification circuit, 18...Arithmetic circuit, 19
... Current detector, 20 ... Smoothing capacitor, 21
...Inverter output current waveform.

Claims (1)

[Claims] 1. A device that has a main circuit in which a power supply section, a step-up transformer, and an ozone generator are connected in series, and that generates ozone by silent discharge by passing oxygen or a gas containing oxygen through the discharge gap of the ozone generator. . An ozone generator, characterized in that the power supply section is constituted by a transistor inverter and a matching circuit having at least a reactor.