JPH06233540A - Ozonizer power source - Google Patents

Abstract

PURPOSE:To enable elongation of the lifetime of an ozonizer tube by keeping power supplied to an ozonization part connected to a boosting transformer constant. CONSTITUTION:AC power is supplied to an ozonization part 3 from converters 1, 2 by turning gate-turn-off thyristors S1, S4 and S2, S3 on alternately. At this time, current controllers 4, 5 control the converters 1,2 so that current flowing through the ozonization part 3 may be reversely proportional to time square root by semicycles in forward and reverse directions each. Since impressed voltage onto the ozonization part 3 is proportional to time square root, instantaneous power that is the product of voltage and current becomes almost constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power source (electric power converter) for an ozone generator utilizing silent discharge.

[0002]

2. Description of the Related Art Power supplies for ozone generators using silent discharge can be classified into two types: a method using a commercial AC power supply and a method using an inverter.

The former applies a boosted 50/60 Hz sinusoidal voltage to an ozone generator tube, while the latter applies 500 to 2 KHz.
It operates as a current source.

The ozone generator using the silent discharge has the following features.

(1) It is a capacitive load when viewed from the power supply side. Therefore, a current flows due to the time change (dv / dt) of the applied voltage.

(2) There is a period in which discharge does not occur from the voltage peak in the voltage decreasing direction.

FIG. 3 shows the voltage and current waveforms when the ozone generator is driven by a sine wave voltage, and FIG. 4 shows the voltage and current waveforms when it is driven by a square wave current. In the figure, Cd is the capacitance per unit area of the dielectric of the ozone generator,
Cg is the capacitance per unit area of the gap, Vs is the discharge start voltage of the gap, and Ve is the discharge stop voltage of the gap.

[0008]

Comparing FIG. 3 and FIG. 4, it can be seen that the square wave (trapezoidal) current drive is shorter in the non-discharge period. Therefore, when it is attempted to input the same average active power with the same frequency and peak voltage to the ozone generator tube, it is clear that the pulsation of the instantaneous power is smaller in the square wave current drive. Generally, in order to prolong the life of the dielectric, it is desirable that the pulsation of electric power applied to the generating tube is small. In the case of square wave current drive, since it is a capacitive load, the voltage rises at a constant slope even in the constant current region because the voltage is an integral of the current. Therefore, the input voltage increases in the constant current region due to the slope of the voltage, and is not always ideal.

The present invention has been made in view of the above points, and an object thereof is to make electric power supplied to an ozone generating tube constant,
An object of the present invention is to provide a power source for an ozone generator that can extend the life of the ozone generator tube.

[0010]

According to the present invention, there is provided a power conversion unit for converting AC power into DC, and an electric path connecting a primary side of a step-up transformer whose secondary side is connected to an ozone generation unit and the power conversion unit. It is characterized in that it is provided with a switch circuit which is inserted and which alternately switches the direction of the current flowing through the transformer, and a current control section which controls the output current of the power conversion section so as to be inversely proportional to the square root of time. .

[0011]

When the switch circuit is ON / OFF controlled at a predetermined frequency and the direction of the output current of the power converter is switched alternately, a predetermined AC power is supplied to the step-up transformer, and the ozone generator (ozone generator tube) operates. To drive. At this time, the current flowing through the ozone generator is controlled so as to be inversely proportional to the square root of time in each of the forward and reverse half cycles, so that the voltage applied to the ozone generator is proportional to the square root of time. Therefore, the voltage,
The instantaneous power, which is the product of currents, is almost constant. This can extend the life of the ozone generating tube.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numerals 1 and 2 denote converters that convert the AC power introduced from the transformer T ₁ into DC, and are configured by connecting thyristors in a bridge connection, for example.
Converters 1 and 2 are connected in series, the positive output end of converter 1 is connected to one end of DC reactor DCL ₁ , and the negative output end of converter 2 is connected to one end of DC reactor DCL ₂ .

Between the other end of the DC reactor DCL _{1 and} the other end of the DC reactor DCL ₂ , a semiconductor switch, for example, a series circuit composed of gate turn-off thyristors S ₁ and S ₂ and gate turn-off thyristors S ₃ and S _{4 are formed.} Series circuits are connected in parallel. The primary winding of the step-up transformer T ₂ is connected between the common connection point of the gate turn-off thyristors S ₁ and S _{2 and} the common connection point of the gate turn-off thyristors S ₃ and S ₄ . The ozone generator 3 is connected to the secondary winding of the step-up transformer T ₂ . The common connection point of the gate turn-off thyristors S ₁ and S ₂ is the converters 1 and 2 described above.
Connected to the common connection point of.

Numerals 4 and 5 control the phase angle of each thyristor of the converters 1 and 2 based on the detected currents of the DC current transformers DCCT ₁ and DCCT ₂ for detecting the output currents of the converters 1 and 2 and output currents. Is a current control unit for controlling so as to be inversely proportional to the parallel root of time.

The current waveform of each part of the device constructed as described above and the on / off timings of the gate turn-off thyristors S _{1 to} S ₄ are shown in FIG. In FIG. 2, I ₁ is a current waveform flowing on the DC reactor DCL ₁ side,
I ₂ is a current waveform flowing through the DC reactor DCL ₂ side, I is a current waveform flowing through the primary winding of the step-up transformer T ₂ , and FIG.
(B) shows the current waveform of I ₁ or I ₂ , respectively.

Gate turn-off thyristors S ₁ , S ₄ and S
₂ and S ₃ are alternately turned on at a predetermined frequency (for example, any one of 500 to ₃ KHz), the step-up transformer T ₂
AC power is supplied to the ozone generating unit 3 via the, and the ozone generating unit 3 is driven. At this time, the current control units 4 and 5
The converters 1 and 2 are controlled so that the current flowing through the ozone generating unit 3 is in inverse proportion to the square root of time in half cycles in the forward and reverse directions as indicated by I. As a result, the ozone generator 3
The voltage applied to is proportional to the square root of time, and the instantaneous power, which is the product of voltage and current, is almost constant regardless of time,
The life of the ozone generating tube can be extended.

The current i, voltage v, and power P are expressed by the following equations. In addition, t = 0 at the start of the half cycle.

[0018]

[Equation 1]

[0019]

[Equation 2]

[0020]

[Equation 3]

The power P becomes almost constant by selecting each constant from the above equation as follows.

[0022]

[Equation 4]

The current control is not limited to the phase angle control of the thyristors of the converters 1 and 2, but PWM control by a self-extinguishing semiconductor element may be performed.

[0024]

As described above, according to the present invention, the electric current supplied to the ozone generator is controlled so that it is inversely proportional to the square root of the time in each of the positive and reverse half cycles. Can be made substantially constant, which can extend the life of the ozone generating tube.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

2A is a time chart for explaining the operation of the embodiment, and FIG. 2B is a current waveform diagram.

FIG. 3 is a voltage and current waveform diagram when a sine wave voltage is applied.

FIG. 4 is a voltage / current waveform diagram when a constant current source is connected.

[Explanation of symbols]

1, 2, converter 3 ...... ozone generator 4,5 ... current controller T ₂ ... step-up transformer S ₁ to S ₄ ... gate turn-off thyristor

Claims (1)

[Claims] 1. A power conversion unit for converting AC power into DC, and a secondary side is inserted in an electric path connecting the primary side of the step-up transformer whose ozone side is connected to an ozone generation unit and the power conversion unit to the transformer. A power supply for an ozone generator, comprising: a switch circuit that alternately switches the direction of flowing current; and a current control unit that controls the output current of the power conversion unit so as to be inversely proportional to the square root of time.