KR101675018B1 - Power Supply for Micro-pulse type Electrostatic Precipitator - Google Patents

Abstract

Disclosed is a power supply device for a dust collector of a micro pulse charging type. According to embodiments of the present invention, the micropulse charged type dust collector power supply has a simple structure with a single power source. Accordingly, the conventional micro-pulse charging type dust collecting device power supply device has the same performance advantages as the conventional micro pulse charging type dust collecting device power supply device, but has a simple circuit configuration as compared with the conventional micro pulse charging type dust collecting device power supply device, have.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a micro-pulse type electrostatic precipitator,

This embodiment relates to a power source device of an electrostatic precipitator. More particularly, the present invention relates to a power source for an electrostatic precipitator of a micro pulse charging type.

The contents described in this section merely provide background information on the present embodiment and do not constitute the prior art.

Electrostatic precipitators are largely made up of two mechanisms: particle charging and charged particle collection. Here, the charging mechanism is a function for charging (or charging) the dust, and the dust collection mechanism is for collecting the charged dust by the electrostatic force on the electrode (collection). In general, dust collection is well performed even at a voltage of 30 kV or less, so the dust removing ability or dust collection efficiency of the dust collector is determined by how well the dust is charged. In order to charge the dust well, a strong plasma is generated at the electrode of the dust collector, so that a lot of charge is attached to the fine dust.

1 is a diagram showing a basic configuration of a conventional high voltage DC type electrostatic precipitator power supply device. In the high voltage DC type electrostatic precipitator power supply apparatus 100 of FIG. 1, the charge and dust collection of the dust are operated by one power source. Since a dust collector using such a high voltage DC power source can easily generate a spark or an arc between the dust collecting electrodes (EPS), the average operating voltage must be significantly lowered. As a result, the generation of plasma becomes weak, the charge becomes insufficient, and the dust collection rate becomes low.

FIG. 2 is a graph showing plasma generation intensity, plasma, and arc generation region according to a voltage applied to an electrode in the apparatus of FIG. 1; As shown in the graph of FIG. 2, as the voltage increases from the starting point of plasma generation, the generation intensity of the plasma rapidly increases. Even if the voltage is decreased from the point of time when the arc is generated, the arc state continues, There is a risk of damaging the dust collecting system.

Moreover, the fact that the plasma start voltage and arc start point vary with ambient conditions makes it more difficult to cope with the risk of damage from these arcs. That is, the arcing voltage varies greatly depending on the temperature of the gas passing through the dust collector, the concentration of the dust and the constituents of the dust, the flow rate of the gas in the dust collector, and the pressure. Therefore, the minimum voltage, which is a voltage at which no arc is generated in the electrode, must be applied under any circumstances, and thus the plasma generation intensity is weak. As a result, the charge amount of the dust is reduced, and the dust collecting ability is lowered.

In order to significantly improve the disadvantages of such a DC high voltage dust collector, a micropulse charging type dust collector power supply has been used. FIG. 3A is a diagram showing a configuration of a conventional micropulse charging and discharging system power supply device of a pulse transformer type. 3A, a conventional micropulse-charged-type dust collector power supply 300 includes a high voltage direct current (DC) power supply 300 for applying a bias voltage of a direct current high voltage for preliminary charging of a dust collecting electrode A power supply unit 360, an extra high voltage filter reactor 370 for filtering an exceptionally high voltage rectified voltage and a pulse blocking in pulse output, a low voltage pulse power supply unit 310 for generating pulses in the dust collecting electrode, A reactor 315 for smoothing the supplied power, a pulse charge capacitor 316 for charging and holding a voltage for pulse output, a resonant reactor 320 for forming a resonance circuit in pulse operation, a low voltage pulse as an extra high voltage pulse A low voltage semiconductor switch 330 for pulsed switching and a DC voltage blocking filter 330 to maintain the bias voltage charged in the collecting electrode 380 (Having an equivalent capacitance C _ep ) 380 of a dust collector, and a pulse resonance capacitor 350 for constituting a pulse resonance circuit. 3B, the extra high voltage direct current power supply unit 360 of FIG. 3A includes a voltage variable unit 361, an extra high voltage step-up transformer 362, and an extra high voltage rectifier 363 for varying the DC voltage. The low-voltage pulse power supply unit 310 shown in FIG. 3A may be configured as a variable DC low-voltage power supply unit 311 (FIG. 3B) so as to control the magnitude of the pulse voltage, which is a very simple structure.

FIG. 4 is a view showing a main waveform of a conventional micropulse charge type dust collector power supply apparatus. In FIG. 4, a period I represents a DC high voltage and a DC current applied to the electrode of the dust collector when the pulse output is not performed. When the low-voltage semiconductor switch 330 is turned on in a state where the bias DC voltage to be applied to the dust collecting electrode is applied by the high-voltage DC power supply unit 360, the C _ps 316 -L _pr 320- C _pr (350) -C _ep (380) forms a resonant circuit, and the pulse voltage is added to the bias DC voltage as in the period II of FIG. Section II shows the micropulse voltage and current waveform applied to the dust collector at the time of pulse output. In the output voltage waveform of the micropulse charged type dust collector power supply device of FIG. 4, the micropulse voltage is responsible for the charging action of the dust and the DC high voltage performs the dust collecting action.

When a certain voltage or more is applied between the dust collecting electrodes, the plasma starts to be generated, and the plasma state develops into the arc state as time elapses. The larger the applied voltage, the shorter the time required for the arc to develop. Further, although the voltage fluctuates depending on the conditions of the dust collector plant, the shorter the applied voltage holding time (pulse voltage width), the larger the magnitude of the voltage that does not generate the arc state. Accordingly, it can be seen that as the pulse width of the voltage applied to the dust collecting electrode is reduced, a higher voltage can be applied, thereby enabling more powerful plasma generation and ultimately more charging on dust, .

According to the above description, the micro-pulse charge type dust collector uniformly generates a strong plasma because the pulse maximum voltage can be increased to be higher than the voltage of the DC high voltage dust collector. Therefore, it is possible to charge particles to dust very effectively, so that the dust collecting performance can be maximized. In addition, back corona can be suppressed by adjusting the pulse period, thereby preventing redistribution of dust collected by the reverse corona, and preventing burning of the electrode. In addition, since the micropulse charging type dust collector can lower the DC bias voltage for dust collection, the power consumption is greatly reduced.

However, although the conventional micro pulse charging method has a great advantage of improving the dust collecting efficiency and reducing power consumption, the structure of the dust collector power supply system is complicated, the manufacturing cost is rapidly increased, and the economical efficiency is reduced due to its large size and heavy weight.

Disclosure of Invention Technical Problem [6] The present invention is intended to solve the disadvantage that the structure of the conventional micropulse dust collector power supply apparatus is complicated, the manufacturing cost rises sharply, and the size thereof is large and heavy. For this purpose, unlike a conventional micro-pulse charge type dust collector, there is a main purpose of providing a micro-pulse charge type dust collector having a simple structure having a single power source.

According to an aspect of the present embodiment, a power supply device of an electrostatic precipitator includes a variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor, a resonance reactor coupled in series to the smoothing capacitor, A switching element, and a transformer having a primary winding and a secondary winding. Wherein the smoothing capacitor, the resonant reactor and the first switching element are coupled in series with the primary winding of the transformer. The power source device of the electrostatic precipitator further includes a second switching element coupled in series with the secondary winding of the transformer together with the collecting electrode of the electrostatic precipitator. In the above configuration, the power source device of the electrostatic precipitator applies an adjustable pulse voltage to the adjustable DC bias voltage to the dust collecting electrode through switching of the first switching device and the second switching device.

For example, the power supply unit may switch the first switching device to a first predetermined frequency to form the direct-current bias voltage applied to the dust collecting electrode in a state in which the second switching device is turned off. In addition, the power supply unit may form a pulse voltage applied to the dust collecting electrode by performing Zero Current Turn-off Switching between the first switching device and the second switching device.

Embodiments of the system may further include one or more of the following features.

To form the DC bias voltage, the first switching element is turned on for a predetermined time (T _ON ) shorter than a half period of the resonance period (Tr) formed between the dust collecting electrode and the resonance reactor for the predetermined first frequency . The timing of turning on the first switching element can be controlled in association with a resonance period (Tr) formed between the dust collecting electrode and the resonant reactor.

In order to form the pulse voltage, (1) the first switching element is turned on for a time longer than a half period (Tr / 2) of a resonance period formed between the dust collecting electrode and the resonant reactor in a state in which the second switching element is OFF (2) the second switching element in the OFF state is turned on before the half period of the resonance period elapses after the first switching element is turned on, and after the first switching element is turned on, Turn OFF after a long time has elapsed.

The resonant reactor may comprise a saturable reactor and may be coupled to a secondary winding instead of the primary winding of the transformer.

According to another aspect of the present invention, a power supply device of an electrostatic precipitator includes a variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor, a resonance reactor and a switching unit coupled in series to the smoothing capacitor . Here, the switching unit includes a first switching device and an auxiliary switching device connected in parallel to each other, and an auxiliary reactor is connected in series to the auxiliary switching device. The power source device of the electrostatic precipitator includes a transformer having a primary winding and a secondary winding, and the smoothing capacitor, the resonant reactor and the switching section are coupled in series to the primary winding of the transformer. In addition, the power source device of the electrostatic precipitator includes a second switching element coupled in series with the secondary winding of the transformer together with the collecting electrode of the electrostatic precipitator. In the above configuration, the power source device of the electrostatic precipitator superposes an adjustable pulse voltage on the adjustable DC bias voltage to the dust collecting electrode through switching of the first switching device, the auxiliary switching device, and the second switching device do.

For example, the power supply unit may switch the auxiliary switching element to a predetermined first frequency in a state in which the first switching device and the second switching device are turned off to form the DC bias voltage applied to the dust collecting electrode have. In addition, the power supply apparatus forms a pulse voltage applied to the dust collecting electrode by performing zero current turn-off switching on the first switching element and the second switching element in a state in which the auxiliary switching element is turned off can do.

According to another aspect of the present embodiment, the power supply device of the electrostatic precipitator includes a variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor, a primary winding and a secondary winding And a plurality of resonant reactors coupled in parallel with the smoothing capacitor. Further, the power source device of the electrostatic precipitator may further include a plurality of first switching elements connected in series to the respective resonant reactors, wherein the plurality of resonant reactors and the plurality of first switching elements are connected to the respective windings of the primary windings of the transformer, Respectively. The power source device of the electrostatic precipitator further includes a second switching element coupled in series with the secondary winding of the transformer together with the collecting electrode of the electrostatic precipitator. In the above configuration, the power source device of the electrostatic precipitator applies an adjustable pulse voltage to the adjustable DC bias voltage to the dust collecting electrode through switching of the first switching device and the second switching device.

For example, the power supply unit may switch the one of the plurality of first switching elements to a predetermined first frequency in a state in which the second switching element is turned off to form the DC bias voltage applied to the dust collecting electrode have. In addition, the power source device can generate a pulse voltage applied to the dust collecting electrode by performing zero current turn-off switching on the plurality of first switching devices and the second switching devices.

The micropulse charged type dust collector power supply apparatus according to embodiments of the present invention has a simple structure with a single power source. Particularly, compared with the conventional micro-pulse charging type dust collector power supply device, the components thereof are significantly reduced and the manufacturing cost is greatly reduced, while providing the same performance merits of the conventional micro-pulse charging type dust collector power supply device .

1 is a diagram showing a basic configuration of a conventional high voltage DC type electrostatic precipitator power supply device.
FIG. 2 is a graph showing plasma generation intensity, plasma, and arc generation region according to a voltage applied to an electrode in the apparatus of FIG. 1;
3A and 3B are diagrams showing a configuration of a conventional micropulse charging and discharging system power supply device of a pulse transformer type.
FIG. 4 is a view showing a main waveform of a conventional micropulse charge type dust collector power supply apparatus.
5 is a configuration diagram of a micropulse charging type dust collector power supply apparatus according to an embodiment of the present invention.
6A and 6B are diagrams for explaining the principle of applying a DC bias voltage to the dust collecting electrode.
FIGS. 7A and 7B are diagrams for explaining the principle of forming the extra high voltage pulse voltage to be applied to the dust collecting electrode.
8A is a diagram showing waveforms in the case where the dust collector is raised to the target DC voltage while being activated, and then the pulse voltage is superimposed while being raised to the target DC voltage and held. FIG. 8B is an enlarged view of the waveform after starting in FIG. 8A. FIG.
FIG. 9 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention.
10 is a graph showing an inductance variation characteristic of the saturable reactor 920 according to the magnitude of the current.
11 is a view showing a waveform of a current flowing in the low-voltage semiconductor switching element (S _LV ) 540 when the power supply apparatus of FIG. 9 operates in the DC bias mode.
12 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention.
13 is a diagram showing a waveform of a current flowing in a DC low-voltage semiconductor switching element when the power supply apparatus of FIG. 12 operates in a DC bias mode.
14 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the description of the present invention, the term "voltage increase" means that the negative voltage increases in magnitude. For the sake of convenience, the voltage is not referred to as negative, but is described only by the magnitude of the voltage. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. Throughout the specification, when an element is referred to as being "comprising" or "comprising", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise . In addition, '... Quot ;, " module ", and " module " refer to a unit that processes at least one function or operation, and may be implemented by hardware or software or a combination of hardware and software.

The micropulse charged type dust collector power supply apparatus according to embodiments of the present invention has a simple structure with a single power source. In other words, the embodiments according to the present invention to be described below can be applied to a conventional high-voltage pulse resonance capacitor (hereinafter, referred to as " high voltage pulse resonance capacitor " 350, an extra high voltage pulse rejection reactor 370 for pulse blocking at pulse output, a variable DC voltage source 361 for DC voltage change, an extra high voltage step-up transformer 362 and an extra high voltage rectifier 363 I do not need it. In other words, embodiments of the present invention can significantly reduce manufacturing cost, size, and weight while having all of the performance and advantages of a micropulse charging scheme.

One. First Embodiment

5 is a configuration diagram of a micropulse charging type dust collector power supply apparatus according to an embodiment of the present invention.

5, the dust collector power supply 500 includes a variable DC voltage source V _s 510 for varying the voltage, a smoothing reactor L _ps 515, a smoothing capacitor C _ps 516, ( _Lpr ) 520, an extra high voltage step-up pulse transformer ( _PT ) 530, a low voltage semiconductor switch (S _LV ) 540, a dust collecting electrode (ESP, equivalent capacitance C _ep ) 560 and a semiconductor switch And an extra high voltage semiconductor switch (S _HV ) 550. Here, specific snubber circuits and the like for protecting the semiconductor switches are omitted.

Hereinafter, the operation principle of the dust collector power supply apparatus 500 will be described with reference to FIGS. In order to understand the operation principle of the dust collector power supply apparatus 500, it is noted that the dust collecting electrode 560 of the dust collector operates as a circuit in which an equivalent resistor (R _ep ) is connected in parallel to an electrically equivalent capacitor (C _ep ) shall.

First, the principle of applying a direct-current bias voltage to the dust collecting electrode will be described with reference to Figs. 6A and 6B. FIG. 6A is a graph showing waveforms of a voltage applied to the dust collecting electrode and a current flowing to the dust collecting electrode when the power supply apparatus of FIG. 5 operates in the DC bias mode, and FIG. FIG. 5 is a graph showing a change in voltage applied to the dust collecting electrode. FIG.

; 550)를 OFF한 상태에서 저압 반도체 스위치(S_LV; 540)를 스위칭함으로써 형성되며, 특히 저압 반도체 스위치(S_LV; 540)의 ON 구간과 OFF 구간을 조정함으로써(즉, Duty를 조정함으로써) 상기 직류 바이어스 전압의 레벨을 가변할 수 있다. 다시 말해, 집진 전극(560)에 직류 바이어스 전압을 인가하기 위해, 저압 반도체 스위치(S_LV; 540)는 단속적으로 동작, 예컨대 시간 T_ON 동안은 ON 되는 반면, 이어지는 시간 T_OFF 동안은 OFF 된다. 이러한 ON-OFF 패턴은 주기적으로 반복된다. 저압 반도체 스위치(S_LV; 540)의 스위칭 간격은 C_ps - L_pr - C_ep에 의해 규정되는 직렬 공진회로의 동작 주파수에 매칭되는 것이 바람직하다. 여기서, 각 반도체 스위치(S_LV, S_HV; 540, 550)에 병렬로 연결되어 있는 다이오드는 인위적으로 ON/OFF를 할 수 없으며, 각 다이오드에 인가되는 전압이 순방향이면 ON 되고, 역방향이면 OFF 되는 것은 자명하다. 따라서, 저압 캐패시터(C_ps; 516)의 전압은 가변 직류 전압원(510)에 의해 V_s로 충전되어 있다고 가정하면, 집진 전극(560)에 인가되는 직류 바이어스 전압은 수학식 1로 결정된다.The DC bias voltage for collecting dust is generated by a high-voltage semiconductor switch

; Pressure semiconductor switch (S _LV ) 540 by adjusting the ON and OFF sections of the low-voltage semiconductor switch (S _LV ) 540 (that is, by adjusting the duty) The level of the DC bias voltage can be varied. In other words, in order to apply the DC bias voltage to the dust collecting electrode 560, the low voltage semiconductor switch (S _LV ) 540 is operated intermittently, for example, during the time T _ON, while it is _OFF during the subsequent time T _OFF . This ON-OFF pattern is repeated periodically. The switching interval of the low voltage semiconductor switch (S _LV ; 540) is preferably matched to the operating frequency of the series resonant circuit defined by C _ps - L _pr - C _ep . Here, the diode connected in parallel to each of the semiconductor switches S _LV and S _HV 540 and 550 can not be turned on / off artificially. The diode is turned on when the voltage applied to each diode is forward, It is self-evident. Therefore, assuming that the voltage of the low-voltage capacitor C _ps 516 is charged to V _s by the variable DC voltage source 510, the DC bias voltage applied to the dust collecting electrode 560 is determined by Equation (1).

Here, Vs is a variable DC voltage source (510), V _{ep _dc} is a direct current voltage applied to the dust collecting electrode (560), T _ON is the ON time of the low-voltage semiconductor switch 540, T _OFF is a low-voltage semiconductor switch 540 OFF time, T represents the switching period (i.e., T _ON + T _OFF ), N _p is the turns ratio of the pulse transformer 530, and R _L is the equivalent resistance of the dust collecting electrode 560.

Figure 6a is a "high-voltage semiconductor switch case where during the;; (540 S _LV) time T _ON is ON and will periodically operate as to OFF patterns during T _OFF, while it is turned OFF (S _HV 550), low-voltage semiconductor switch." there is shown in the waveform of a direct current bias voltage (V _{ep _dc)} and current of the dust collecting electrode _(ep I) to be applied to the dust collecting electrode 560. During the time T _ON , the power is transformed to a high voltage at the pulse transformer 530 to charge the dust collecting electrode 560, thereby raising the voltage of the dust collecting electrode 560. During time T _OFF , the voltage of the collecting electrode 560 is attenuated because the charge on the collecting electrode 560 is discharged in the collecting electrode 560 by the movement of the ionized particles (i.e., dusts).

6B shows a change in the voltage (V _{ep - DC} ) applied to the dust collecting electrode 560 as the low voltage semiconductor switch (S _LV ) 540 is increased from Duty 0. That is, it can be seen that the voltage V _{ep - - DC} applied to the dust collecting electrode 560 is proportional to the square of the duty of the low voltage switch S _LV 540.

FIGS. 7A and 7B are diagrams for explaining the principle of forming the extra high voltage pulse voltage to be applied to the dust collecting electrode.

7A is a diagram showing an operation table for each section of a low-voltage semiconductor switch S _LV 540 and a high-voltage semiconductor switch S _HV 550 for applying an extra-high voltage pulse voltage to the dust collecting electrode 560. The diodes D _LV and D _HV connected in parallel to the semiconductor switches S _LV and S _HV 540 and 550 are turned on when the voltages applied to the respective diodes are in the forward direction and turned off when the voltages applied to the diodes are in the reverse direction. 7B is a pulse voltage waveform of a period of resonance flowing to the dust collecting electrode 560 and a period of resonance period of a resonator applied to the dust collecting electrode 560. Fig.

The low voltage semiconductor switch (S _LV ) 540 and the high voltage semiconductor switch (S _HV ) 550 operate as shown in FIG. 7A in order to apply the special high voltage pulse voltage to the dust collecting electrode 560. First, the high-voltage semiconductor switch with;; (540 S _LV) to ON and the equivalent capacitor (C _ep) of the resonance reactor (520) and the dust collecting electrode (560) (S _HV 550) in the state in which the OFF, low-voltage semiconductor switch, The high voltage semiconductor switch (S _HV ; 550) which is in the OFF state before the half cycle of the resonance period elapses after the low voltage semiconductor switch (S _LV ; 540) is turned ON after the resonance half period ) to ON and, the low pressure semiconductor switch (S _LV; 540) that the resonant period after the ON (T _r) than after a long time of high-pressure semiconductor switch ON state (S _HV; when a 550) OFF, Figure 7b A pulse current of a resonant period flows in +/- one cycle in the dust collecting electrode 560 and a resonant pulse voltage is applied to the dust collecting electrode 560. [ The maximum value V _{ep_pk} of the pulse voltage applied to the resonance half period (T _r / 2), the magnitude of the pulse current (I _{ep - pk} ) and the dust collecting electrode 560 is _{expressed by} Equations 2, 3, do.

로 가정한다.Where L _pr is the resonant reactance of the resonant reactor 520, C _ep is the equivalent capacitance of the dust collecting electrode 560,

.

Fig. 8A is a diagram showing waveforms when the dust collector 560 is raised from zero voltage to raise the voltage up to the target DC voltage, and holding the pulse voltage while keeping it up. When the low-voltage semiconductor switch (S _LV ) 540 is switched to the switching frequency f _dc while the high-voltage semiconductor switch (S _HV ) 550 is turned OFF and gradually increased from 0 duty, as shown in FIG. 8A, The voltage applied to the electrode 560 gradually rises from the zero voltage. When the voltage applied to the dust collecting electrode 560 is raised to the target bias voltage V _dc (about -35 kV in Fig. 8A and Fig. 8B) and pulsed at the switching frequency f _p in the manner illustrated in Fig. 7A, The pulse voltage overlaps the target bias voltage V _dc .

FIG. 8B is an enlarged view of the waveform after starting in FIG. 8A, showing in detail the relationship between the DC operation mode for maintaining the bias DC voltage and the pulse operation mode for superimposing the pulse on the bias DC voltage.

In this embodiment, since the on period of the low voltage semiconductor switch (S _LV ) 540 in the direct current operation mode is very short and the current increasing rate is very large, the large current is forced off (hard switching) The switch S _LV 540 may be stressed. On the other hand, in the pulse operation mode, the low pressure semiconductor switch; current flowing through the (S _LV 540) is much greater one, a zero current switching (Zero Current Turn-off switching) of a low-pressure semiconductor switch (S _LV so than in the DC mode; 540 ) Is rather reduced.

Second Embodiment

FIG. 9 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention. In the embodiment shown in FIG. 9A, in order to reduce the stress of the low-voltage semiconductor switch in the DC bias operation mode, the resonator reactor in the dust collector power supply apparatus of FIG. 5 is replaced by a saturable reactor _{pr _sat;} it was composed of 920).

10 is a graph showing an inductance variation characteristic of the saturable reactor 920 according to the magnitude of the current. As shown in Fig. 10, the saturable reactor 920 has a large inductance below a predetermined constant current (i.e., a saturation current) determined by a design, but the reactor 920 increases when a constant current (saturation current) The core is saturated and the inductance is greatly reduced.

11 is a view showing a waveform of a current flowing in the low-voltage semiconductor switch (S _LV ) 540 when the power supply apparatus of FIG. 9 operates in the DC bias mode. Due to the characteristics of the saturating reactor 920, the current in the DC bias operation mode gradually rises as shown in Fig. 11, so that the current at the time of Off of the low voltage semiconductor switch (S _LV ) 540 is greatly lowered . As a result, the stress of the low voltage semiconductor switch (S _LV ) 540 can be relaxed, reliability can be increased, and switching loss can be reduced. Here, the magnetic saturation inductance value of the saturable reactor 920 is designed in accordance with the resonance conditions of Equations (2) and (3), and the inductance value in the unsaturated state is determined within several to several tens times of saturation inductance , And the saturation current is preferably determined to be 40% or less of the maximum value (peak current) of the maximum pulse current.

Third Embodiment

12 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention. The dust collector power supply 1200 according to the present embodiment is configured separately from a low-voltage semiconductor switch for generating a pulse voltage and a low-voltage semiconductor switch for controlling a direct-current bias voltage. That is, the, low pressure semiconductor switch shown in Figure 5. As shown in Figure 12, replaced with _{a; (1245 S LV _b) (} S LV;; 540) is pulsed low-voltage semiconductor switch (S _{LV _a} 1240) and direct current low-voltage semiconductor switch, . Further, the direct current low-voltage semiconductor switch (S _{LV _b;} 1245), the resonance of the secondary reactor in a number of orders of magnitude times the reactance value; is an (L _pa 1246) coupled in series. Thus, the pulse low-voltage semiconductor switch (S _{LV _a;} 1240) is a low-voltage semiconductor switch of Figure 5 (S _LV; 540) that is the same operation as those operating in the pulse mode of operation, direct-current low-voltage semiconductor switch (S _{LV _b;} 1245) Is operated in the same manner as the low-voltage semiconductor switch (S _LV ; 540) of FIG. 5 is operated in the DC bias mode.

According to such a configuration, the degree of freedom in selecting the pulse low-voltage semiconductor switch (S _{LV _a} ) 1240, which has to cope with a very large pulse current, is increased. That is, the pulse current is always decreased by one cycle (ie, "zero current → magnitude increase → magnitude decrease → magnitude decrease → zero current → magnitude increase → magnitude decrease in current magnitude" The pulse low voltage semiconductor switch (S _{LV _a} ; 1240) does not need to have a forced OFF capability, and as a result, the pulse low voltage semiconductor switch (S _{LV _a} ) A semiconductor switch can be used.

13 is the operation when a DC low-voltage power semiconductor switch device is a direct current bias mode of Fig. 12; a diagram showing the waveform of the current flowing through the (S _{LV _b} 1245). DC bias direct-current low-voltage semiconductor switch for controlling the voltage (S _{LV _b;} 1245) has ten times the secondary reactor in the number of times the resonance reactance value; because it is coupled to (L _pa 1246) in series, shown in Figure 13 Thus, the DC bias current mode, and gradually increases, the direct current low-voltage semiconductor switch (S _{LV _b;} 1245) at the time of OFF current is also significantly lower. Therefore, according to this embodiment, direct-current low-voltage semiconductor switch; by mitigating the bunch (Stress) of (S _{LV _b} 1245), it is possible to increase the reliability, it is possible to reduce switching loss. This is similar to the description of the second embodiment employing the supersaturation reactor (in particular, Fig. 11).

Fourth Embodiment

14 is a configuration diagram of a micropulse charge type dust collector power supply apparatus according to another embodiment of the present invention.

As shown in Fig. 14, in order to reduce the current burden at the time of forced OFF of the low-voltage semiconductor switch (S _LV ), the present embodiment includes the primary-side resonant circuit section ( _Lpr- T _PT -S _LV ) To a plurality of connected resonance circuits. To this end, a pulse transformer 1430 having a plurality of taps on the primary side is employed. Here, the values of the respective resonant reactors 1420_1 to 1420 to N are larger by N (the number of parallel circuits) than when they are made into a single circuit. In other words, the resonance reactors 1420_1 to 1420_N of Fig. 14 have N times reactance, respectively, as compared with the resonance reactor 520 of Fig.

In order to obtain a bias DC voltage to be applied to the electrode 560 of the dust collector while distributing a very large pulse current to the plurality of semiconductor switches S _{LV -1} to S _{LV N} ; 1440 _{_ 1} to _{1440_N} , Any of the N parallel circuits is operated as described in FIGS. 6A and 6B. In this case, since the resonance inductance of one circuit is N times, the current at the time of forced OFF of the low-voltage semiconductor switch can be reduced to 1 / N, and the stress and switching loss of the semiconductor switch can be reduced.

In order to effectively operate the embodiments of the present invention described above, it is important to control by considering the relationship between the pulse voltage magnitude V _p , the bias DC voltage magnitude V _dc , and the magnitude V _s of the variable DC voltage source .

Since the winding ratio N _p of the transformer is fixed as shown in Equation (5), the maximum value (V _{ep - pk} ) of the pulse voltage of the dust collecting electrode is directly proportional to the variable DC voltage source size (V _s ) I do not have. On the other hand, the magnitude (V _{ep - dc} ) of the bias DC voltage can be determined by Duty (T _on / T). Accordingly, after determining the pulse voltage to be applied to the dust collecting electrode according to Equation (5) and controlling the variable DC voltage source accordingly, the duty (T _on / T of the low voltage semiconductor switch. It is obvious that Equation (6) can be changed according to the embodiment of the present invention. For example, in the case of using a saturable reactor as a resonance reactor, the bias DC voltage (V _{ep _dc)} it does not correspond to formula (6), still proportional to the size and Duty (T _on / T) of the variable DC voltage source (V _s) .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Various embodiments can be envisaged within the framework of the present invention, for example, by changing the location of the components, such as by placing the resonant reactor on the secondary side of the pulse transformer, or by having the components in series or in parallel. Therefore, the above-described embodiments are intended to illustrate rather than limit the technical spirit of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

500: Dust collector power supply
510: Variable DC voltage source (V _s ) 515: Smooth reactor (L _ps )
516 Smoothing capacitor (C _ps ) 520 Low-voltage resonant reactor (L _pr )
530: extra high voltage step-up pulse transformer (T _PT ) 540: low voltage semiconductor switch (S _LV )
550: Special high-voltage semiconductor switch (S _HV ) 560: Collecting electrode (ESP)
920: saturable reactor (L _{pr _sat)} 1240: low-voltage semiconductor switch pulse
1245: DC low-voltage semiconductor switches 1420_1 to 1420_N: resonant reactor
1430: Transformers 1440_1 to 1440_N:

Claims (15)

In a power supply device of an electrostatic precipitator,
A variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor;
A resonance reactor and a first switching device coupled in series to the smoothing capacitor;
A transformer having a primary winding and a secondary winding, wherein the smoothing capacitor, the resonant reactor and the first switching element are coupled in series to the primary winding of the transformer; And
A second switching element coupled in series with a secondary winding of the transformer together with a collecting electrode of the electrostatic precipitator,
And configured to apply an adjustable DC bias voltage to the dust collecting electrode in an overlapping manner with an adjustable pulse voltage,
The first switching element is switched to a first predetermined frequency in a state in which the second switching element is turned off to form the DC bias voltage,
The first switching element is turned on for a time longer than a half period (Tr / 2) of a resonance period formed between the dust collecting electrode and the resonant reactor in a state where the second switching element is OFF, The device is turned on before the half period of the resonance period elapses after the first switching device is turned on and is turned off after a lapse of a time longer than the resonance period after the first switching device is turned on to form the pulse voltage , A power source of the electrostatic precipitator. delete The method according to claim 1,
Characterized in that the first switching element is turned ON for a predetermined time (T _ON ) shorter than a half period of a resonance period (Tr) formed between the dust collecting electrode and the resonance reactor for every predetermined first frequency Power supply. The method of claim 3,
The timing at which the first switching element is turned on,
Characterized in that said resonant reactor is associated with a resonant pulse period formed between said collector electrode and said resonant reactor. The method according to claim 1,
Wherein a level of the direct-current bias voltage is adjustable by adjusting a duty of the first switching device. The method according to claim 1,
And a pulse voltage to be applied to the dust collecting electrode is formed by performing zero current turn-off switching on the first switching device and the second switching device. delete The method according to claim 1,
Characterized in that the resonant reactor comprises a saturable reactor. The method according to claim 1,
Wherein the resonant reactor comprises:
Wherein the secondary winding is coupled to the secondary winding instead of the primary winding of the transformer. In a power supply device of an electrostatic precipitator,
A variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor;
A resonant reactor and a switching unit coupled in series to the smoothing capacitor, wherein the switching unit includes a first switching device and an auxiliary switching device connected in parallel to each other, and an auxiliary reactor is serially connected to the auxiliary switching device;
A transformer having a primary winding and a secondary winding;
The smoothing capacitor, the resonant reactor and the switching unit being coupled in series to the primary winding of the transformer; And
A second switching element coupled in series with a secondary winding of the transformer together with a collecting electrode of the electrostatic precipitator,
And configured to apply an adjustable DC bias voltage to the dust collecting electrode in an overlapping manner with an adjustable pulse voltage,
The auxiliary switching element is switched to a predetermined first frequency in a state in which the first switching element and the second switching element are turned off to form the DC bias voltage,
The first switching element is turned on for a time longer than a half period (Tr / 2) of a resonance period formed between the dust collecting electrode and the resonant reactor in a state where the auxiliary switching element and the second switching element are OFF, The second switching element is turned on after the first switching element is turned on, before the half period of the resonance period elapses, and after the first switching element is turned on, a time longer than the resonance period has elapsed, A power supply for an electrostatic precipitator, forming a voltage. 11. The method of claim 10,
And the DC bias voltage applied to the dust collecting electrode is formed by switching the auxiliary switching element to a predetermined first frequency in a state in which the first switching element and the second switching element are turned off, Power supply. 11. The method of claim 10,
In a state in which the auxiliary switching element is turned off,
And a pulse voltage to be applied to the dust collecting electrode is formed by performing zero current turn-off switching on the first switching device and the second switching device. In a power supply device of an electrostatic precipitator,
A variable DC supply source composed of a converter circuit for converting an AC voltage to a DC voltage, a smoothing reactor and a smoothing capacitor;
A transformer having a primary winding and a secondary winding with a plurality of taps;
A plurality of resonant reactors coupled in parallel to the smoothing capacitor;
A plurality of first switching elements connected in series to each resonant reactor, wherein said plurality of resonant reactors and said plurality of first switching elements are coupled in series to respective taps of the primary winding of said transformer; And
A second switching element coupled in series with a secondary winding of the transformer together with a collecting electrode of the electrostatic precipitator,
And configured to apply an adjustable DC bias voltage to the dust collecting electrode in an overlapping manner with an adjustable pulse voltage,
Switching one of the plurality of first switching elements to a predetermined first frequency in a state in which the second switching element is turned off to form the DC bias voltage applied to the dust collecting electrode,
(Tr / 2) of a resonance period formed between the dust collecting electrode and the resonant reactor for a time longer than a half period (Tr / 2) of the resonance period in which the second switching element is OFF, The second switching element is turned on after the first switching element is turned on and before the half period of the resonance period elapses, and after the first switching element is turned on, a time longer than the resonance period has elapsed, A power supply device of an electrostatic precipitator for forming a pulse voltage. delete 14. The method of claim 13,
Wherein a pulse voltage to be applied to the dust collecting electrode is formed by performing zero current turn-off switching on the plurality of first switching elements and the second switching element.

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