JPH0626362Y2 - Electric dust collector pulse power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pulse power supply for an electrostatic precipitator (hereinafter abbreviated as EP).

[Conventional technology]

In a conventional (direct connection type) pulse power source as shown in FIG. 2, a high voltage transformer 3 connected to an AC power source 1 via a low voltage AC power controller 2 and a rectifier connected to the high voltage side of the high voltage transformer 3. 4, a capacitor 6 connected to the DC side output of the rectifier 4 via a DC reactor 5, a high voltage switch 7 inserted between a high voltage terminal of the capacitor 6 and a discharge electrode 8 of the EP, and a high voltage transformer. The current transformer 11 for detecting the low-voltage side alternating current i of the device 3, the voltage detector 21 for detecting the voltage V ₁ applied to the capacitor 6, the voltage detector 22 for detecting the EP voltage V ₂ , and The low-voltage AC power controller ₂ for inputting the current i and the voltages V ₁ and V ₂ and displaying them on a meter, or automatically controlling to a predetermined i or V ₁ or V ₂ by their numerical values. Signal α to adjust
It is comprised from the control apparatus 20 which outputs. However, the control device 20 can also arbitrarily set and output the value itself of α.

In the conventional pulse power supply, the voltage applied to the capacitor 6 (hereinafter referred to as capacitor voltage) V _C and the voltage between the discharge electrode and the dust collecting electrode, that is, the EP voltage V _EP, are completely independent while the high voltage switch 7 is not conducting. , V _C , V _EP , in order to know the values of V _C , V _EP , voltage detectors 21, 2 for individually detecting V _C , V _EP
2 and has the following control functions necessary for high-voltage charging control of the EP by inputting the voltage signals V ₁ and V ₂ detected by the voltage detectors 21 and 22 to the control device 20.

(1) Current i constant control (2) Capacitor voltage V _C constant control (3) EP spark discharge detection and spark discharge occurrence frequency constant control (4) EP low voltage detection and low voltage recovery control The decrease is a phenomenon in which the EP voltage becomes a very low voltage due to a short circuit between electrodes or a state close to a short circuit due to a metal short circuit between internal electrodes or abnormal discharge.

[Problems to be solved by the device]

In conventional pulsed power supplies, while the high voltage switch is off,
Since the capacitor voltage V _C and the EP voltage V _EP are completely independent, the capacitor voltage V _C for realizing the control function is
It was necessary to detect the EP voltage V _EP and the EP voltage V _EP individually by using independent voltage detectors.

An object of the present invention is to provide an EP pulse power supply that can solve the above-mentioned conventional problems.

[Means for Solving the Problems]

In the present invention, the capacitor voltage V _C and the EP voltage V _C
The relational expression between the _EP, focuses on the fact that it is possible to calculate the V _EP than V _C, pulsed power EP by the present invention may comprise only the voltage detector for detecting the capacitor voltage V _C, were detected V By providing a means for calculating V _EP by _C, the voltage detector for detecting V _EP is omitted.

[Action]

In the conventional direct-coupling type pulse power supply shown in FIG. 2, it is represented by the equivalent circuit shown in FIG. 3, and therefore the capacitor voltage V _C and the EP voltage V _EP have the following relationship.

Let V _{CB be} the capacitor voltage and V _D be the EP voltage at the moment when the high voltage switch becomes non-conducting after a certain time has passed since conduction. V _CB = V _D (1) The capacitance between the capacitor and EP is Known and C _P and C respectively
When _EP capacitor voltage immediately before the high-voltage switch is conducting _V CP, when the EP voltage and _{V B,} they and V
It has the following relationship with _D.

Therefore, from equations (1) and (2) That is, except for the transient phenomenon while the high voltage switch of the direct connection type pulse power supply represented by the equivalent circuit shown in FIG. 3 is conducting, the corona discharge which occurs between the electrodes of which the conduction time of the high voltage switch is EP When it is sufficiently shorter than the time constant of the attenuation due to, the characteristic values V _D and V _{B of} the EP voltage can be calculated by the capacitor voltages V _CB and V _CP .

The equivalent circuit shown in FIG. 3 will be described below.

C _P represents the capacitor 6 in FIG. 2, SW represents the high voltage switch 7, C _EP represents the electrode space composed of the discharge electrode 8 and the dust collecting electrode 9, and L and R represent the electrodes of the capacitor 6 and EP, respectively. Indicates the inductance and resistance floating in the electric path that connects the spaces. Further, the R _EP fact is represents a corona discharge resistance of the electrode space is unknown.

SW in FIG. 3 represents the high-voltage switch 7 in FIG. 2, and this circuit shows the transient phenomenon of the LCR series resonance circuit while the high-voltage switch 7 is conducting, that is, while SW is ON. It becomes a state.

However, in the present invention, it is not necessary to deal with the transient phenomenon of the LCR series resonant circuit, and only the states immediately before and after the start of the transient phenomenon will be discussed, so the details thereof will be omitted.

〔Example〕

FIG. 1 is a diagram showing a configuration of a pulse power source as an embodiment according to the present invention. In FIG. 1, a high voltage transformer 3 connected to an AC power source 1 via a low voltage AC power controller 2 and the high voltage transformer. Rectifier 4 connected to the high voltage side of the rectifier 3, and the rectifier 4
Between the high-voltage terminal of the capacitor 6 and the discharge electrode 8 of the EP, which is connected to the DC side output of the capacitor 6 via the DC reactor 5 for suppressing the inrush current at the time of short-circuiting the load side and protecting the rectifier. High-voltage switch 7 to be inserted into the high-voltage transformer 3 and a current transformer 11 for detecting the low-voltage side alternating current i of the high-voltage transformer 3.
And a voltage detector 12 for detecting a voltage (capacitor voltage V _C ) V _C applied to the capacitor 6, and signals i and V _C are input, and these are displayed as an instrument, arithmetic processing is performed, and
The control device 20 outputs a signal α for adjusting the low-voltage AC power controller 2 according to i, V _C.

The EP provided by the present invention in the conventional example shown in FIG.
Although the voltage detector 22 for detecting the voltage V _EP is omitted, of the various control functions described in the above-mentioned “Prior Art”, it is realized by inputting the EP voltage V _EP as a signal.
The "EP spark discharge detection" and the "EP low voltage detection" required for the control of (3) and (4) can be realized as follows only by the signal of the capacitor voltage V _C.

(1) First, "EP spark discharge detection" focuses on the phenomenon that the EP voltage suddenly disappears (becomes 0) when a spark discharge occurs not only with a pulse power supply but also with a normal EP DC high voltage power supply.
The occurrence of spark discharge is detected when the level of the voltage V _EP is below a certain value (Fig. 4), and the sharp decrease of V _{EP is} the rate of change, that is, the differential value. To detect spark discharges (Fig. 5)
Is generally adopted, but as described in the above “Operation”, the high voltage switch 7 is used in the pulse power supply of the present invention.
Since the EP voltage V _D and the capacitor voltage V _CB at the moment when the switch becomes non-conducting have a relationship of V _D = V _CB , when spark discharge occurs at the EP, immediately after the non-conduction of the high voltage switch 7, V _D , V _CB are both 0, so even if the above-mentioned ordinary spark detection method is applied by the signal v _c of the capacitor voltage V _c , EP spark discharge is EP
It can be detected as in the case of using the voltage V _EP (6th
Figure).

(2) Next, "EP low voltage detection" is usually detected by the EP voltage continuing to fall below a predetermined voltage for a certain period of time. In the pulse power supply of the present invention, in this state, the V
_{Both D} and the EP voltage V _B immediately before the high voltage switch 7 is turned on are equal to or lower than the predetermined voltage.

Therefore, as described in the above "action", The relationship between the relationship and _V D _{= V CB} made, by calculating the _V B, _{V D} from the signal _{v c} of the capacitor voltage _{V c,} it can be easily detected EP low voltage condition from that number. (7th
Figure).

In addition to the functions of "EP spark discharge detection" and "EP low voltage detection" described above, in order to know the charging state of EP, it is required to display the EP charging voltage with a meter or the like. If V _D and V _B according to the above relational expressions are displayed as EP voltage data, the same requirement is satisfied.

Above, "EP spark discharge detection" from the detection signal v _c of the capacitor voltage V _c, V _D as "EP Low Voltage Detection" or EP voltage _data, in FIG. 8 a specific circuit block for displaying V _B Show. In manufacturing a circuit, it is necessary to know the electrostatic capacitances of the capacitor and EP, but since both can be treated as constants, there is no particular problem.

Further, as a matter of course, as means for calculating V _D and V _B , in addition to the analog arithmetic circuit as shown in FIG. 8, arithmetic by a software program using a microcomputer can be adopted.

A synchronous motor that rotates in synchronization with the frequency of the AC power source as the high-voltage switch, or a mechanical rotary spark gap driven by an induction motor that is directly connected to the AC power source via a frequency conversion device (inverter), or Alternatively, a semiconductor high voltage control element such as a spark gap with a trigger mechanism such as a three-point trigger gap or a laser trigger gap, or a high voltage thyristor can be used.

As the voltage detector, a resistance voltage divider, a capacitance voltage divider,
A resistive capacitance voltage divider can be used.

[Effect of device]

According to the present invention, in the direct connection type pulse power source of EP, E
By providing a means for obtaining P spark discharge detection, EP low voltage detection, and EP voltage data by a capacitor voltage, it is possible to omit the voltage detector which directly detects the EP voltage, which was indispensable in the past.

Further, by doing so, it is possible to obtain the effects of reducing the number of components of the pulse power supply, reducing the cost, and making the device compact.

[Brief description of drawings]

FIG. 1 is a block diagram of a pulse power source as one embodiment of the present invention, FIG. 2 is a block diagram of a pulse power source as a conventional example, and FIG.
Figure is equivalent circuit diagram of pulse power supply. Figure 4 is EP at level.
Fig. 5 is a principle diagram for detecting spark discharge, Fig. 5 is a principle diagram for detecting EP spark discharge by differential value, and Fig. 6 is E of capacitor voltage.
FIG. 7 is an explanatory diagram when P spark discharge occurs, FIG. 7 is a principle diagram for detecting an EP low voltage from a capacitor voltage, and FIG. 8 is a diagram showing a specific example of a circuit block provided by the present invention. 1 ... AC power supply, 2 ... Low-voltage AC power controller, 3 ... High-voltage transformer, 4 ... Rectifier, 5 ... DC reactor, 6 ...
... condenser, 7 ... high voltage switch, 8 ... discharge electrode, 9 ... dust collecting electrode, 12 ... voltage detector.

Claims (1)

[Scope of utility model registration request] 1. A high voltage transformer connected to an AC power source via a low voltage AC power controller comprising a power control element such as a thyristor or a transistor as a DC high voltage power source for an electrostatic precipitator, and a high voltage of the high voltage transformer. Between the high-voltage terminal (ungrounded terminal) of the capacitor and the discharge electrode of the electrostatic precipitator, a rectifier connected to the rectifier, a capacitor whose one end is connected to the DC output of the rectifier via a DC reactor The capacitor is inserted to electrically connect the high-voltage terminal of the capacitor and the discharge electrode electrically at regular or arbitrary timing, and the accumulated charge of the capacitor is sharply changed to the capacitance between the discharge electrode and the dust-collection electrode of the electrostatic precipitator. A high pulse voltage with a steep rise is applied between the discharge electrode and the dust collecting electrode by discharging into a neutral space, and becomes non-conductive after an arbitrary or uncertain time elapses. In a pulse power supply of an electrostatic precipitator including a pressure switch, a voltage detector that detects a voltage applied to the capacitor, and a discharge electrode of the electrostatic precipitator based on a voltage value detected by the voltage detector. A pulse power supply for an electrostatic precipitator, comprising a calculator for calculating a voltage between the precipitator electrodes.