JPH02191558A - Power source device for electrostatic precipitator - Google Patents

Abstract

PURPOSE:To make production cost inexpensive by connecting a commercial power source to the primary side of a transformer via a current controlling element and connecting the discharge pole of an electrostatic precipitator to the secondary side via a full-wave rectifier. CONSTITUTION:The primary side of a transformer is connected to a commercial power source. High voltage generated in the secondary side is rectified by a full-wave rectifier 4 and impressed between a discharge electrode 1a and a dust collecting electrode 1b of a dust collector 1. Primary current allowed to flow to the transformer 3 is controlled by a gate turn-off thyristor 2. Data are written-in to an RAM 12 by a CPU 10 according to a program written in an ROM 11. The CPU 10 receives a signal from the external part via an interface 13 or performs outgoing. Thereby dust collection efficiency is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a power supply device for an electrostatic precipitator, and particularly to a power supply device for an electrostatic precipitator that can reduce power consumption and make it possible to downsize a transformer.

[Conventional technology] Electric collection! ! In the machine, the Coulomb force acting on the dust to be removed is proportional to the electric charge applied to the dust and the electric field between the electrodes, and the electric charge of the dust is approximately equal to the peak voltage Vp applied between the electrodes.
The temporal average value of the electric field between the electrodes is proportional to the average voltage Va applied between the electrodes. Therefore, the dust collection capacity increases in proportion to V p X V a.

Conventionally, in order to increase the above-mentioned VpXVa, a pulse voltage has been superimposed on the DC base voltage applied between the electrodes.

An example of the circuit is shown in FIG.

40 in the diagram is Shu! ! Thyristors 2, 2 . It is constituted by a transformer 3 and an M current device 4 that performs full-wave rectification on the high voltage output on the secondary side of the transformer 3 and applies a base voltage to the discharge electrode 1a.

50 in the figure is a power supply circuit for applying a peak voltage to the dust collector 1, and thyristors 52, 52, . A rectifier 54 and a capacitor 57 which full-wave rectify the high voltage output of the transformer 53 and the secondary side of the transformer 53 and supply charging current to a capacitor 57 connected in series with the electrode of the dust collector via coils 55 and 56. It is composed of a thyristor 58 that periodically discharges the electric charge. Note that 5 is a diode that circulates a resonance current when the thyristor 58 is off.

When the charge in the capacitor 57 is discharged by the thyristor 58 through the coil 56, a high pulse voltage with a resonance frequency determined by the capacitor 57, the coil 56, and the capacitance of the dust collector is applied between the collecting electrode 1b and the discharging electrode 1a. be done.

In this way, a high voltage pulse voltage is superimposed on the base voltage,
The dust collection ability can be increased by increasing the value of V p X V a.

[Problems to be Solved by the Invention] However, the above-mentioned conventional device requires two power supplies, and the frequency of the current flowing through the transformer is low, making it impossible to downsize the transformer, resulting in an expensive device. .

The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a power supply device for an electrostatic precipitator that has high dust collection efficiency, low manufacturing cost, and quick control response.

[Means for Solving the Problems] The power supply device for an electrostatic precipitator of the present invention connects a commercial power source to the primary side of a transformer via a current control element having a turn-off function, and completely switches off the secondary side of the transformer. It is connected to a discharge electrode of an electrostatic precipitator via a wave rectifier, and the current control element is made conductive at least twice in every half cycle of the commercial power supply.

Further, the current control element is turned off when the primary or secondary current of the transformer exceeds a predetermined value.

Furthermore, a commercial power source is connected to the primary side of the transformer via a current control element having a turn-off function, and the secondary side of the transformer is connected to a discharge electrode of an electrostatic precipitator via a full-wave rectifier,
A repetition period in which an on period in which the current control element conducts at least twice during a half cycle of the commercial power supply continues for an even number of half cycles, followed by an even number of half cycles in an off period in which the current control element does not conduct, or the current The current is controlled so that it has a repetition period in which an on period in which conduction occurs two or more times during a half cycle of the control element or the commercial power supply continues for an odd number of half cycles, followed by an even number of half cycles in which an off period in which the current control element does not conduct. The elements are controlled.

In addition, a commercial power source is connected to the primary side of the transformer via a current control element having a turn-off function, and the secondary side of the transformer is connected to the discharge electrode of the electrostatic precipitator via a full-wave rectifier. A conduction section of the current control element is provided in the middle of the half cycle of the conduction section, and by controlling the conduction start angle or section width of the conduction section, the peak voltage applied to the discharge electrode of the electric collector is controlled, and the commercial power supply A section in which the current control element conducts is provided at the end of the half cycle, and the average voltage applied to the discharge electrode of the electric aai is controlled by controlling the conduction start angle of the conduction section.

[Function] According to the power supply device for an electrostatic precipitator of the present invention, since the current flowing through the transformer has a high frequency, miniaturization is possible, the control response is fast, and the integral value of the voltage applied to the transformer is Since the time average becomes 0, no biased excitation occurs.

In addition, since the peak voltage at which the electrode is charged becomes significantly higher than the average voltage, .rho.XVa increases and the dust collection ability is improved.

Such an effect is particularly optimized and becomes even more effective when Vp and Va are controlled separately.

Furthermore, since the current due to the reverse ionization phenomenon caused by the highly resistive deposited dust does not flow for a long period of time, the dust collection efficiency is increased and power consumption is reduced.

Such an effect becomes more effective when a non-conducting half cycle continues several times or when the current control element is turned off when the primary or secondary current of the transformer exceeds a predetermined value.

[Embodiments] Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram showing the first embodiment of the present invention. 3 in the figure is a transformer whose primary side is connected to a commercial power supply, and the high voltage generated on the secondary side is rectified by a full-wave rectifier 4. A voltage is applied between the discharge electrode la and the collection electrode lb of the dust collector 1.

The primary current flowing through the transformer 3 is controlled by a gate turn-off thyristor (GTO) 2.

A CPU 10 receives or transmits signals from the outside via an interface 13 while writing data to or reading data from the RAM 12 according to a program written in the ROM II.

16 is a manual variable resistor that sends a setting signal to the CPU 10 via the AD converter 17 and the interface 13.

14 is a transformer which converts the voltage of the commercial power supply and sends it to the zero point detector 15. The zero point detector 15 sends a signal to the interface 13 at the zero point where the voltage of the commercial power supply changes from negative to positive.
is sent to the CPU 10 via. A phase control circuit 18 applies a positive trigger pulse or a negative turn-off pulse to the gate turn-off thyristor 2 according to the signal from the interface 13.

FIG. 4 shows voltage and current waveforms at various parts in this embodiment. In the same figure (a> is the waveform of the power supply voltage.

cb> in the same figure is the G TO control output and shows the section in which the gate turn-off thyristor 2 is conductive.

The gate turn-off thyristor 2 receives a positive trigger pulse from one phase control circuit every predetermined period from the 0 point of the power supply voltage and becomes conductive. It turns off when it receives a negative turn-off pulse.

The primary current of the transformer is shown in the same figure (c), and the section width and peak value in which the current flows are approximately proportional to the set conduction period of the gate turn-off thyristor 2.

The transformer secondary current corresponding to this transformer primary current is full-wave rectified and added to the collector 111fi (EP)1, but since the dust collector R1 has a capacity, its charging voltage is
It becomes as shown in .

The peak voltage can be set with a variable resistor 16.

FIG. 2 is a block diagram showing a second embodiment of the invention. Hereinafter, parts having similar functions in each embodiment will be described with the same reference numerals.

The difference from the first embodiment is that the output current of a current transformer 20 that converts the primary current of a transformer 3 is full-wave rectified by a rectifier 21, and the voltage generated is set by a variable resistor 16 and a comparator. 22, and when the value becomes higher than the set value, a signal is sent to the CPU 10 via the interface 13. When the primary current of the transformer 3 becomes higher than a set value, the CPU 10 applies a negative turn-off pulse to the gate turn-off thyristor 2 via the interface 13 and the phase control circuit 18 to stop the gate turn-off thyristor 2 from conducting.

The conduction of the gate turn-off thyristor 2 is started at predetermined intervals from the zero point of the commercial power supply, as in the first embodiment.

The voltage and current waveforms of each part in this embodiment are shown in FIG. 5, and the difference from the first embodiment is the GTO shown in FIG.
The section width of the control output is limited by the primary current of the transformer 3 and changes, and the transformer primary current shown in (c) of the same figure and the EP applied current shown in (d) of the same figure are below a certain value. It is. This prevents back ionization of dust and increases in reverse corona if flow, increasing the efficiency of the dust collector.

Furthermore, even if a spark discharge occurs within a certain half cycle of the commercial power supply voltage, the gate turn-off thyristor can be turned off within that half cycle, so the spark discharge can be extinguished more quickly than in the past.

The third embodiment of the present invention is constructed as shown in FIG. 1, similar to the first embodiment.

In this embodiment, as shown in FIG.
In the cycle, the gate turn-off thyristor 2 is controlled as in the first embodiment, but in the next cycle, the gate turn-off thyristor 2 is not made conductive. In this way, a cycle in which the gate turn-off thyristor 2 is made conductive is followed by a cycle in which it is not made conductive, and the cycle is repeated.

In this embodiment, since the period in which the m collector is not charged becomes longer, the power saving effect is enhanced.

FIG. 3 is a block diagram showing a third embodiment of the present invention.

In this embodiment, the BP charging voltage is divided by resistors 3o and 31, and the resulting voltage is applied to a peak value detector 32 and an average value detector 33.

The peak value detector 32 sends a digital signal proportional to the peak value of the EP charging voltage to the CPU via the interface 13.
The average value detector 33 sends a digital signal proportional to the average value of the EP charging voltage to the CPU 10 via the interface 13.

As shown in FIG. 7(b), CPtJlo makes the gate turn-off thyristor 2 conductive for a predetermined period @P in the middle of a half cycle of the commercial power supply, and controls the conduction start angle and conduction width to achieve the peak of the EP charging voltage. At the same time, the average value of the EP charging voltage is made to be a predetermined value by making the gate turn-off thyristor 2 conductive for a period at the end of a half cycle of the commercial power supply and controlling the conduction start angle. do.

By optimizing the peak value and average value of the BP charging voltage in this manner, reverse ionization is prevented, dust collection efficiency is increased, and power saving is achieved.

Although the embodiment of the present invention is constructed as described above, the invention is not limited thereto; for example, a MoS transistor or a GBT may be used instead of the gate turn-off thyristor.

[Effects of the Invention] As explained above, according to the electric concentrator rock power supply device of the present invention, since the current flowing through the transformer has a high frequency, miniaturization is possible, and the control response can be fast, so sparks can be generated quickly. Since the discharge can be erased and the peak voltage at which the electrode is charged is significantly higher than the average voltage, V p
a becomes larger and the dust collection ability is enhanced.

Such an effect is particularly optimized and becomes even more effective when Vp and Va are controlled separately.

Furthermore, since the current due to the reverse S Ai phenomenon caused by the high-resistance deposition task does not flow for a long period of time, the dust collection efficiency is increased and power is saved.

Such an effect becomes more effective when a non-conducting half cycle continues several times or when the current control element is turned off when the primary current of the transformer exceeds a predetermined value. 6

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the first and third embodiments of the present invention. FIGS.
and a block diagram showing the configuration of the fourth embodiment, FIG.
5, 6, and 7 are voltage and current waveform diagrams of various parts of the first to fourth embodiments of the present invention, respectively, and FIG. 8 is a circuit diagram showing the prior art. 1... Dust collector, 1a... Discharge electrode, 1b... Collection m
Electrode, 2... Gate turn-off thyristor, 3...
Transformer, 4... Rectifier, 10... CPU, 11...
・ROM, 12...RAM, 13...Interface, 14...Transformer, 15...0 point detector, 16
... Variable resistor, 17... AD converter, 18.
...Phase control circuit, 20... Current transformer, 21... Rectifier, 22... Comparator, 30.31...
-Resistor, 32...Peak value detector, 33...Average value detector.

Claims (1)

[Claims] 1. A commercial power supply is connected to the primary side of the transformer via a current control element having a turn-off function, and the secondary side of the transformer is connected to the discharge electrode of an electrostatic precipitator via a full-wave rectifier. the current control element is connected to at least two
A power supply device for an electrostatic precipitator, characterized in that it conducts at least once. 2. The power supply device for an electrostatic precipitator according to claim 1, wherein the current control element is turned off when the primary or secondary current of the transformer exceeds a predetermined value. 3. Connect a commercial power source to the primary side of the transformer via a current control element with a turn-off function, connect the secondary side of the transformer to the discharge electrode of the electrostatic precipitator via a full-wave rectifier, and A repetition period in which an on period in which the control element conducts at least twice during a half cycle of the commercial power supply continues for an even number of half cycles, followed by an even number of half cycles in an off period in which the current control element does not conduct, or the current control element The current control element has a repetition period such that an on period in which the current control element conducts at least twice during a half cycle of the commercial power supply continues for an odd number of half cycles, and then an off period in which the current control element does not conduct continues for an even number of half cycles. Controlled electric precipitator power supply. 4. Connect a commercial power source to the primary side of the transformer via a current control element with a turn-off function, connect the secondary side of the transformer to the discharge electrode of the electrostatic precipitator via a full-wave rectifier, and connect the commercial power source to the A section in which the current control element conducts is provided in the middle of the half cycle, and by controlling the conduction start angle or section width of the conduction section, the peak voltage applied to the discharge electrode of the electrostatic precipitator is controlled, and the half cycle of the commercial power supply is controlled. A power supply device for an electrostatic precipitator, wherein a conduction section of the current control element is provided at the end of a cycle, and the average voltage applied to the discharge electrode of the electrostatic precipitator is controlled by controlling the conduction start angle of the conduction section.