KR102515338B1 - A high voltage pulse generation circuit using power switch and electrostatic precipitator including the same - Google Patents

Abstract

A pulse generation circuit according to an embodiment of the present invention includes a first DC power source supplying a first DC voltage; an input capacitor connected in parallel to the first DC power supply and providing a charging voltage; a first power switch having one end connected to the first DC power supply and an input capacitor; an inductor connected to the other end of the first power switch; a second power switch generating a pulse current by controlling a flow of inductor current passing through the inductor; and a pulse transformer converting the pulse current into a pulse voltage.

Description

High voltage pulse generating circuit using power switch and electric precipitator including same

The present invention relates to a high voltage pulse generating circuit using a power switch and an electric precipitator including the same.

In an electrostatic precipitator, corona discharge is generated on a discharge electrode to which a high negative voltage is applied, thereby electrifying the dust and then forming an electric field. As a facility for removing dust particles, it is widely used in industrial plants to collect dust included in exhaust gas.

As the above-mentioned electrostatic precipitator, there are a direct current (DC) type electrostatic precipitator and a pulse type electrostatic precipitator. In the case of the direct current (DC) type, despite low dust collection efficiency, high energy cost is consumed and dust with high resistivity During treatment, there is a problem in that smooth dust removal is not achieved due to a reverse ionization phenomenon or the like.

On the other hand, since the pulse type electric precipitator uses a low DC voltage for dust collection and a high voltage pulse with a short period for charging, energy cost is low and high dust collection efficiency can be expected. In addition, it may have excellent dust removal performance without reverse ionization of dust having high resistivity.

Therefore, domestic and foreign companies related to dust collectors are currently conducting research on various pulse generators and pulse-type electrostatic precipitators using the same. For example, US Patent No. 6362604 discloses an electrostatic precipitator capable of supplying DC and pulses with one DC power source. has been

However, in the case of the above-mentioned literature, the LC resonance condition in front of the pulse transformer is complicated, and since the resonance tank supply voltage is used in common with the high voltage DC supplied to the dust collector, a high voltage switch is required, and DC and pulse voltage control is impossible There is a problem with that.

US registered patent US6362604 ('ELECTROSTATAIC PRECIPITATOR SLOW PULSE GENERATIING UNIT')

According to one embodiment of the present invention, a pulse generating circuit capable of generating a pulse voltage even when using a DC voltage source having a relatively low magnitude and an electric precipitator including the same are provided.

A pulse generating circuit according to an embodiment of the present invention includes a first DC power source supplying a first DC voltage; an input capacitor connected in parallel to the first DC power supply and providing a charging voltage; a first power switch having one end connected to the first DC power supply and an input capacitor; an inductor connected to the other end of the first power switch; a second power switch generating a pulse current by controlling a flow of inductor current passing through the inductor; and a pulse transformer converting the pulse current into a pulse voltage.

In addition, the electric precipitator according to an embodiment of the present invention includes a first DC power supply for supplying a first DC voltage; an input capacitor connected in parallel to the first DC power supply and providing a charging voltage; a first power switch having one end connected to the first DC power supply and an input capacitor; an inductor connected to the other end of the first power switch; a second power switch generating a pulse current by controlling a flow of inductor current passing through the inductor; and a pulse transformer converting the pulse current into a pulse voltage. a second DC power supply adding a second DC voltage to the pulse voltage; and a dust collector configured to collect dust by receiving the pulse voltage and the second DC voltage.

The pulse generation circuit according to the embodiment of the present invention can generate a pulse voltage even when using a DC voltage source having a relatively low magnitude.

In addition, since the pulse generation circuit can be employed in an existing DC electrostatic precipitator, the pulse charging type electrostatic precipitator can be implemented with a simple structure.

1 is a configuration diagram of a pulse generating circuit according to an embodiment of the present invention.
2a to 2d are diagrams illustrating the principle of operation of the pulse generating circuit of FIG. 1 according to an embodiment of the present invention.
3A is an example of an electric precipitator in which a pulse generating circuit and a second DC voltage providing unit are connected in series.
3B is an example of an electric precipitator in which a pulse generating circuit and a second DC voltage providing unit are connected in parallel.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

However, the embodiments of the present invention can be modified in many different forms, and the scope of the present invention is not limited to the embodiments described below.

In addition, 'including' a certain component means that other components may be further included, rather than excluding other components unless otherwise stated.

In the drawings referred to in the present invention, the same reference numerals will be used for components having substantially the same configuration and function, and the shapes and sizes of elements in the drawings may be exaggerated for clearer explanation.

1 is a configuration diagram of a pulse generating circuit according to an embodiment of the present invention.

Referring to FIG. 1 , the pulse generation circuit includes a first DC power source S1, an input capacitor C1, an inductor L1, a power switch SW, and a pulse transformer Tr. In addition, protection circuits SN and SG connected in parallel to the power switch SW may be further included. In addition, an input diode D1 and a charge path diode D2 may be further included.

The first DC power source S1 is a power source that provides a DC voltage, and may have a low voltage of 4 kV or less.

The input capacitor (C) is connected in parallel to the first DC power supply (S1). The input capacitor C may be charged by reverse current from the pulse transformer Tr, and a charged voltage may be applied to the inductor L1 via the first power switch SW1.

One end of the first power switch SW1 is connected to one end of the first DC power supply S1 and the input capacitor C connected in parallel, and the other end of the first power switch SW1 is connected to the inductor L1. An ON signal is applied to the gate terminal of the first power switch (SW1) so that the charged power of the first DC power supply (S1) and the input capacitor (C) flows in the direction of the inductor, or an OFF signal is applied to the gate terminal. It can block the flow of power.

The inductor L1 is connected to the first DC power source S1 and the input capacitor C1, and may receive a DC voltage from the first DC power source S1 and a charging voltage from the input capacitor C1. That is, the DC voltage and the charging voltage may be added and applied to the inductor L1.

The second power switch SW2 may provide pulse current to the input terminal of the pulse transformer Tr by intermittent current flowing through the inductor L1. That is, the second power switch SW2 may generate a pulse current by controlling the current flowing through the inductor through a turn on/off operation.

Finally, the pulse transformer Tr may convert the pulse current provided from the inductor L1 into a pulse voltage and output the converted pulse voltage. The pulse voltage may have a sine wave shape. The pulse voltage output from the pulse transformer Tr is added to the high voltage of the second DC power supply (refer to reference numeral S2 in FIGS. 3A and 3B) to obtain a dust collector (refer to reference numerals 130 and 230 in FIGS. 3A and 3B). ) can be provided.

Meanwhile, the first and second power switches SW include a thyristor, an insulated gate bipolar transistor (IGBT), a field-effect transistor (FET), and a bipolar junction transistor. It may include at least one selected from among semiconductor switches including transistors and BJTs.

The protection circuits SN and SG may include at least one of a snubber circuit SN and a spark gap SG.

The snubber circuit (SN) can protect the second power switch (SW2) by mitigating it when the inductor current is excessive and the voltage applied to the second power switch (SW2) is higher than the first threshold value, and the spark gap ( SG) may protect the second power switch SW2 by forming a current conduction path when the voltage applied to the second power switch SW2 is equal to or greater than the second threshold.

Hereinafter, the operating principle of the pulse generation circuit shown in FIG. 1 will be described with reference to FIGS. 2A to 2D. In FIGS. 2A to 2D , activated elements are marked with thick lines and inactive elements are marked with dotted lines, and the symbols in FIGS. 2A to 2D are marked based on the circuit of FIG. 1 .

2A shows an initial operation, and the input capacitor C1 is charged with the same voltage as the first DC power supply S1 in a state in which the first power switch SW1 is not operated.

2B is a case in which ON signals are simultaneously applied to the gates of the first power switch SW1 and the second power switch SW2. Accordingly, when the first power switch SW1 and the second power switch SW2 are turned on, the charging power of the first DC power supply S1 and the input capacitor C1 passes through the first power switch SW1 to the inductor L1. ) direction, and the current flowing through the inductor L1 gradually increases. In this case, the first DC power source S1, the first power switch SW1, the inductor L1, and the second power switch SW2 may form a closed current path.

At this time, with the second power switch SW2 turned on, power is not injected into the pulse transformer Tr. That is, the minimum voltage applied to the second power switch SW2 is applied to the pulse transformer Tr, and this state is regarded as that the pulse transformer Tr is inactive.

FIG. 2C shows that in the state of FIG. 2B , off signals are applied to the gates of the first power switch SW1 and the second power switch SW2 so that the first power switch SW1 and the second power switch SW2 are turned off. indicates the operation of the section.

When the first power switch SW1 and the second power switch SW2 are turned off, the path of the inductor current flowing through the inductor L1 is switched. The current flowing through the inductor L1 is converted into a current source having continuity and induces an overshoot voltage as a transient characteristic at the input terminal of the pulse transformer Tr, and thus power is injected into the pulse transformer Tr. At this time, the magnitude of the voltage of the power injected into the pulse transformer Tr is the same as the voltage generated by the inductor L1, and a current path is formed through the input diode D1.

Here, the input diode D1 provides a bypass path for the pulse current flowing through the primary side of the pulse transformer Tr. The input diode D1 may have a cathode connected to the (+) terminal of the first DC power supply and an anode connected to the (-) terminal.

In addition, a boosted pulse voltage Vo according to the winding ratio is formed on the secondary side of the pulse transformer Tr, and the pulse voltage Vo is applied to the capacitive load Lc. The output of the pulse transformer Tr has a boosted voltage output according to the primary/secondary winding ratio, and the pulse width is determined according to the capacitance of the pulse transformer Tr and the capacitive load Lc. For reference, the capacitive load (Lc) is expressed on behalf of the dust collector chamber.

FIG. 2D shows an operation when the current flowing through the inductor L1 decreases to a certain value (eg, 0A) after the operation of FIG. 2C.

When the current flowing through the inductor L1 decreases and reaches a certain value (for example, 0A), the voltage across the capacitive load Lc becomes maximum, and the power charged in the capacitive load Lc decreases to a certain level. go through a discharging process. As shown in FIG. 2D, the discharge path flows in a reverse direction compared to the conventional flow direction and passes through the pulse transformer Tr, and then the diode D2 connected in parallel with the inductor L1 and the first power switch ( The input capacitor C connected in parallel with the first DC power supply S1 is charged by passing through the reverse diode of SW1).

As the capacitance of the capacitive load Lc increases, the reverse current increases and the input capacitor can be charged by the reverse current. As described with reference to FIG. 2A, since the input capacitor C provides a charging voltage for generating the pulse voltage, the capacitance of the capacitive load Lc is one factor determining the amplitude of the pulse voltage Vo. This can be.

After that, the process shown in FIGS. 2a, 2b, 2c and 2d is repeated and operated.

2A to 2D, a high-voltage pulse voltage is generated on the secondary side of the pulse transformer Tr, but the voltage provided by the first DC power supply S1 connected to the primary side of the pulse transformer Tr is It may be a lower voltage than the pulse voltage. Accordingly, the pulse generating circuit has the advantage of being able to be miniaturized and lightweight.

In addition, since the power switch SW can determine the cycle and amplitude of the pulse voltage according to the turn-on/off cycle, it is easy to adjust the pulse voltage.

FIG. 3A is a view showing an electric precipitator to which the pulse generating circuit described with reference to FIG. 1 is applied, and is an example of the electric precipitator in which the pulse generating circuit 110 and the second DC voltage providing unit 120 are connected in series.

Referring to FIG. 5 , the electrostatic precipitator may further include a second DC voltage providing unit 120 and a dust collecting unit 130 in addition to the pulse generating circuit 110 .

The second DC voltage providing unit 120 may include a second DC power source S2 providing a second DC voltage and L-C filters L2 and C2, and is connected in series with the pulse transformer Tr to be a pulse transformer. It is configured to add a second DC voltage to the pulse voltage Vo converted by (Tr).

That is, the pulse transformer Tr and the second DC power source S2 constitute one integrated high voltage tank 101 .

The magnitude of the second DC voltage may be approximately between 50 kV and 70 kV, and may be larger than the first DC voltage having a value of 4 kV or less. Meanwhile, reference numeral L2 denotes an inductor, reference numeral C2 denotes a capacitor, and the inductor L2 and the capacitor C2 may be an L-C filter for smoothing the voltage by the second DC power source S2.

In addition, the dust collecting unit 130 may include a discharge electrode 131 for charging dust by applying a negative voltage to generate discharge, and a dust collecting plate 132 for collecting charged dust by receiving a positive voltage. there is.

As described with reference to FIGS. 1 and 2A to 2D , the pulse generating circuit 110 generates a pulse current by turning on/off the power switch SW and pulses the pulse current by a pulse transformer Tr. It can be converted to voltage (Vo). Separately, the second DC power supply S2 provides a second DC voltage greater than the voltage of the first DC power supply S1, and the provided second DC voltage is converted by the pulse transformer Tr to provide a pulse voltage (Vo ) can be added.

Here, the negative voltage is provided to the discharge electrode 231 of the dust collecting unit 230, and the positive voltage is provided to the dust collecting plate 232 of the dust collecting unit 230. is charged, and dust charged by the discharge of the discharge electrode 231 can be collected.

3B is a diagram illustrating an electric precipitator according to another embodiment, and is an example of an electric precipitator in which a pulse generating circuit and a second DC voltage providing unit are connected in parallel. That is, since the electric precipitator of FIG. 3B has a difference in that the second DC voltage providing unit 220 is connected in parallel to the pulse generating circuit 210 compared to the electric precipitator of FIG. 3A, overlapping descriptions are omitted. .

Specifically, the second capacitor C4 is connected in series to one end of the pulse transformer Tr and connected in parallel to the output terminal of the second DC voltage providing unit 220 .

In addition, when the pulse generating circuit 210 generating the pulse voltage and the second DC voltage providing unit 220 are connected in parallel, the inductor L3 may be connected to the output terminal of the second DC power supply unit 220, , The second capacitor C4 may be connected to the output terminal of the pulse generating circuit 210 .

With this configuration, in the section where the DC voltage is maintained by the second DC voltage providing unit 220, the second DC voltage is applied to the chamber of the dust collecting unit 230, and at the same time, the second capacitor connected to the pulse transformer Tr ( C4) may also be charged with a DC voltage having the same magnitude as the second DC voltage. At this time, the charging voltage of the second capacitor C4 may have a polarity opposite to that of the pulse output. When a pulse is generated in the pulse generating circuit 210 at a time when a pulse is required, the voltage of the opposite polarity charged in the second capacitor C4 is discharged, thereby increasing the voltage of the chamber of the dust collector 230.

Here, the inductor L3 of the second DC voltage providing unit 220 may serve to remove the influence of the pulse voltage of the pulse generating circuit 210 while maintaining the output current.

That is, the pulse transformer Tr and the second capacitor C4 constitute the pulse high voltage tank 201, and the circuit including the second DC power source S2 constitutes the DC high voltage tank 202.

The pulse voltage provided from the pulse generating circuit 210 may increase the voltage of the chamber of the dust collector 230 , and the increased voltage may charge a capacitive load in the chamber of the dust collector 230 . Here, the voltage of the second capacitor C4 may be the same as the voltage of the chamber of the dust collecting unit 230, and the output of the second DC voltage providing unit 220 may be maintained by the inductor L3. In addition, the electric power charged in the chamber of the dust collector 230 and the second capacitor C4 may be discharged again and absorbed into the pulse generating circuit 210 .

In this way, by employing the pulse generating circuit 210 in a simple structure in the conventional electric precipitator (consisting of the second DC voltage providing unit 220 and the dust collecting unit 230), the maintenance of the electric precipitator is easy, and the conventional It is possible to improve the dust collection performance of the DC electrostatic precipitator and has an effect of lowering power consumption.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, but is limited by the claims to be described later, and the configuration of the present invention can be varied within a range that does not deviate from the technical spirit of the present invention. Those skilled in the art can easily know that the present invention can be changed and modified accordingly.

110, 210: pulse generating circuit
S1: 1st DC power supply
C1: input capacitor
L1: inductor
SW1: first power switch
SW2: second power switch
120, 220: second DC voltage providing unit
S2: 2nd DC power supply
130, 230: dust collecting unit
131, 231: discharge electrode
132, 232: discharge plate

Claims (12)

a first DC power supply supplying a first DC voltage;
an input capacitor connected in parallel to the first DC power supply and providing a charging voltage;
a first power switch having one end connected to the first DC power supply and an input capacitor;
an inductor connected to the other end of the first power switch;
a second power switch generating a pulse current by controlling a flow of inductor current passing through the inductor; and
And a pulse transformer for converting the pulse current into a pulse voltage,
wherein the second power switch is connected in parallel to the pulse transformer.
According to claim 1,
The inductor current gradually increases when the first power switch and the second power switch are turned on, and is supplied to the pulse transformer when the first power switch and the second power switch are turned off to generate pulses to the pulse transformer. Pulse generating circuit provided as current.
According to claim 1,
The pulse generating circuit further comprises an input diode having a cathode connected to a (+) terminal of the first DC power supply and an anode connected to a (-) terminal.
According to claim 1,
the pulse transformer is coupled to a capacitive load;
A pulse generating circuit in which the input capacitor is charged by discharging the capacitive load.
According to claim 4,
further comprising a charge path diode connected in parallel to the inductor;
A pulse generating circuit in which a reverse current due to discharge of the capacitive load charges the input capacitor through the charge path diode.
According to claim 1,
The power switch is an insulated gate bipolar transistor (IGBT) pulse generating circuit.
According to claim 1,
Further comprising a protection circuit connected in parallel to the power switch,
The protection circuit comprises at least one of a snubber circuit and a spark gap.
a first DC power supply supplying a first DC voltage;
an input capacitor connected in parallel to the first DC power supply and providing a charging voltage;
a first power switch having one end connected to the first DC power supply and an input capacitor;
an inductor connected to the other end of the first power switch;
a second power switch generating a pulse current by controlling a flow of inductor current passing through the inductor;
a pulse transformer that converts the pulse current into a pulse voltage;
a second DC power supply adding a second DC voltage to the pulse voltage; and
And a dust collection unit for receiving the pulse voltage and the second DC voltage to collect dust,
wherein the second power switch is connected in parallel to the pulse transformer.
According to claim 8,
The inductor current gradually increases when the first power switch and the second power switch are turned on, and is supplied to the pulse transformer when the first power switch and the second power switch are turned off to generate pulses to the pulse transformer. Electrostatic precipitator provided as electric current.
According to claim 8,
The dust collector,
a discharge electrode that generates a discharge by receiving a negative voltage; and
A dust collection plate that receives positive voltage and collects charged dust.
Electrostatic precipitator containing
According to claim 8,
The second DC power source is connected in series to the secondary side of the pulse transformer to apply a second DC voltage.
According to claim 8,
The second DC power source is connected in parallel to the secondary side of the pulse transformer to apply a second DC voltage.

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