JP2008062149A - High voltage control circuit and dust collector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a frequency of spark can be decreased but the perfect prevention of the spark is difficult in a method for decreasing the frequency of the spark by adjusting a potential difference applied to a dust collecting electrode 1 with a control device. <P>SOLUTION: A high voltage control circuit capable of preventing spark from occurring is obtained by adjusting an applied voltage before generating the spark by catching signs of generating the spark by detecting and comparing a rate of a varied current after relaxing the variation of the current with a coil 4 when detecting a current flowing on the dust collecting electrode 1 with a current detecting resistor 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high voltage control circuit that controls a high voltage applied to an electric dust collector load that collects atmospheric dust, indoor dust, dust, and the like in air conditioning and industrial fields.

  Conventionally, an electrostatic precipitator load that collects dust is configured with two metal electrode plates arranged in parallel, applying a positive or negative voltage to one electrode plate, and the remaining electrode plates Is grounded. When a high voltage is applied between the electrode plates in this state, a corona electric field is formed between the electrode plates, and a corona current flows. When the dust passes through the corona electric field, the dust is charged by the collision of the electrons moving in the corona electric field with the dust. The charged dust receives the force of the electric field between the electrode plates and is attracted and adhered to the electrode plates, and the dust is removed.

  In a state where a high voltage is applied between the electrode plates, a spark discharge (hereinafter referred to as spark) occurs when the insulation between the electrode plates is broken. The reason why dielectric breakdown occurs between the electrode plates is that when conductive dust passes between the electrode plates, the insulation distance between the electrode plates and the conductive dust cannot be secured. For example, the insulating distance between the electrode plates is shortened by volume, and the insulating performance between the electrode plates is lowered by cleaning the dust collecting electrode plates.

  At the moment when the spark is generated, a short-circuited state occurs in the spark generating portion and a large current flows. Therefore, at this moment, the voltage applied between the dust collecting electrode plates is 0V. Since the applied voltage is 0 V, the dust collection function does not work, and the dust collection efficiency is 0%. Therefore, if sparks occur frequently, the time during which dust is not collected increases, resulting in a significant reduction in dust collection efficiency. Further, when a spark occurs, the dust collecting electrode plate itself vibrates due to the impact of the spark. Due to the vibration at that time, a phenomenon occurs in which dust collected by the force of the electric field is scattered again from the dust collecting electrode plate. When the spark is generated, the dust collection efficiency is further lowered due to dust coming out again by re-scattering.

  Conventionally, there is a control method as shown in FIG. 2 and FIG.

The control circuit includes a pulse power supply 101, a spark detection circuit 102, a DC base power supply 103, a controller 104, and a dust collection load 105. The controller 104 counts the number of occurrences of the spark detected by the spark detection circuit 102. If the number of occurrences of spark is less than or equal to the set number in a certain time, it is determined that there is no influence on the dust collection efficiency, and the voltage applied to the dust collection load is controlled to the optimum voltage by controlling the DC base power supply. When the number of occurrences of spark exceeds the set value, switching to spark frequent occurrence control is performed, the pulse voltage supplied from the pulse power supply 101 is set to the lower limit set value, and the output voltage of the DC base power supply is adjusted to resume charging. The lower limit value of the pulse voltage is the minimum value of the voltage at which corona discharge is uniformly generated on the discharge electrode surface when the pulse voltage is applied. Pulse charge control that superimposes DC base voltage and pulse voltage makes it possible to suppress the generation of sparks while maintaining uniform corona discharge on the surface of the discharge electrode, even for high electrical resistivity dust that is prone to sparks. A method for preventing a decrease in the rate (see Patent Document 1), and in the dust collection portion 110 of the dust collection load, any one of the electrodes is replaced with any polymer resin such as polyester, polyacetal, polypropylene, acrylic, or the like. Generation of sparks by forming with a semi-insulating resin to which an appropriate amount of any hydrophilic polymer such as ester amide, polyether amide imide, polyethylene oxide-epichlorohydrin copolymer, polyethylene glycol methacrylate copolymer is added. A method for preventing this problem has been taken (see Patent Document 2).
Japanese Patent Laid-Open No. 11-253837 JP 2000-218193 A

  In the control related to such a conventional spark, the method of Patent Document 1 suppresses the occurrence of a spark but does not completely prevent the occurrence of a spark, so that a spark occurs at a low frequency, As a result, the dust collection efficiency is inevitably lowered. Further, in the method of Patent Document 2, since a corona electric field is not generated between the dust collecting electrode plates by applying the semi-insulating resin to the dust collecting electrode plates, no spark is generated between the dust collecting electrode plates. There is a problem in that the electric field strength between the dust collecting portions is weakened by the insulating insulating action, the charged dust collecting ability depending on the strength of the electric field is lowered, and it is difficult to maintain the dust collecting efficiency.

  Therefore, in order to prevent the occurrence of sparks, pay attention to the fact that the output current rises rapidly in a short period of time when sparks occur. By judging the state of current change with the rate of change, you can catch the sign of sparking as soon as possible, catch the sign and control the high voltage output at the same time, you can prevent the occurrence of spark, A high voltage control circuit capable of maintaining dust collection efficiency is required.

  Further, in order to accurately detect in a short time before a sudden change in current occurs, it is necessary to mitigate the change in current. For this reason, the current change mitigation means is required to have an L component as a characteristic. ing.

  In addition, it is required that the current change mitigating means can be adopted by installing the current change mitigating means on the input side of the high voltage generating means, so that an inexpensive current change mitigating means having low withstand voltage and high versatility can be adopted.

  In addition, it is required that the current change mitigation effect be further enhanced by directly mitigating the high voltage current by installing the current change mitigation unit on the output side of the high voltage generation unit.

  Further, it is required to further improve the current change mitigation effect by installing current change mitigation means on the input side and output side of the high voltage generation means.

  The current change detecting means is required to control the output voltage at an early stage of the current change by applying the differential value as the rate of change of the current value, not the absolute value of the current.

  Further, when the current value change rate exceeds a certain threshold, it is determined that a spark is generated, and the output voltage is lowered by adjusting the input voltage to the high voltage generating means, thereby preventing the occurrence of the spark.

  In addition, once the output voltage is lowered by comparing the current change rate, it is required to maintain the dust collection efficiency by raising the output voltage to a voltage lower than the voltage at which the current change rate changes again.

  Moreover, the use of a semiconductor element for controlling the output voltage at a high speed is required as the input voltage adjusting means.

  In addition, as a threshold value for comparing the current change rate, a high voltage control in which no spark is generated is required by setting a value along a pattern in which spark is generated in advance in the dust collector.

  Further, when the output voltage from the high voltage generating means is increased by the input voltage adjusting means, it is required that the output voltage can be increased smoothly by not comparing with the current change rate until reaching a certain value. .

  Further, it is required that the output voltage can be smoothly increased and decreased by comparing with the current change rate only while the output voltage is within a certain range.

  Moreover, when a spark has occurred, it is required that the spark prevention rate can be improved by lowering the threshold value compared with the current change rate.

  Further, a dust collector equipped with the high voltage control circuit is required.

  The present invention solves such a conventional problem, paying attention to the fact that the output current rises rapidly in a short time when a spark is generated, By determining the state of current change not by the absolute value of the current but by the rate of change of the current, the signs of sparks are detected as soon as possible, and at the same time, the signs of the sparks are controlled by controlling the high-voltage output. It is an object of the present invention to provide a high voltage control circuit that can prevent generation and maintain dust collection efficiency.

  It is another object of the present invention to provide a high voltage control circuit capable of relaxing a change in current in order to accurately detect a change in current in a short time when a sudden change in current occurs.

  It is another object of the present invention to provide a high voltage control circuit that employs an inexpensive current change mitigating means with low withstand voltage and high versatility by installing the current change mitigating means on the input side of the high voltage generating means. .

  Also, a high voltage control circuit is provided that can relax the current change more reliably by directly reducing the high voltage current by installing the current change mitigating means on the output side of the high voltage generating means. The purpose is that.

  It is another object of the present invention to provide a high voltage control circuit in which the current change mitigation effect is further enhanced by installing current change mitigation means on the input side and output side of the high voltage generation means.

  In addition, as a current change detection means, we provide a high voltage control circuit that can control the output voltage at an early stage of the current change by applying the differential value as the rate of change of the current value instead of the absolute value of the current The purpose is to do.

  In addition, it is determined that a spark is generated when the rate of change in current value exceeds a certain threshold value, and a high voltage control circuit is provided that reduces the output voltage by adjusting the input voltage to the high voltage generating means to prevent the occurrence of sparks. It is an object.

  Further, after the output voltage is once lowered by comparing the current change rate, a high voltage control circuit capable of maintaining the dust collection efficiency by increasing the output voltage to a value lower than the value at which the current change rate changes again is provided. The purpose is that.

  Another object of the present invention is to provide a high voltage control circuit using a semiconductor element as an input voltage adjusting means for controlling an output voltage at a high speed.

  In addition, an object of the present invention is to provide a high voltage control circuit in which no spark is generated by setting the threshold value for comparing the current change rate to a value in accordance with a pattern in which spark is generated in advance in the dust collector.

  Also, when the output voltage is raised from the high voltage generating means by the input voltage adjusting means, the output voltage can be raised in a short time by not comparing the current change rate until it reaches a certain value. It aims to provide a circuit.

  It is another object of the present invention to provide a high voltage control circuit capable of increasing and decreasing the output voltage in a short time by comparing with the current change rate only while the output voltage is in a certain range.

  It is another object of the present invention to provide a high voltage control circuit capable of improving the spark prevention rate by lowering the threshold value compared with the current change rate when a spark has occurred.

  Moreover, it aims at providing the dust collector equipped with this high voltage control circuit.

  In order to achieve the above object, the high voltage control circuit of the present invention collects dust, high voltage generating means for generating a high voltage to be applied to the dust collecting means, and the dust collecting means. Current detecting means for detecting the current flowing to the means, current change mitigating means for gradual change of the current flowing to the dust collecting means, and current change rate calculating means for calculating the rate of change of the detected current, The present invention is characterized in that the current change rate calculation means captures a sign of a sudden change in current and controls the high voltage before the current changes suddenly.

  According to the present invention, after the rapid change in current is moderated, the current change state is determined not by the absolute value of the current but by the rate of change of the current, so that the sign of occurrence of the spark can be caught as soon as possible. The high voltage control circuit that can prevent the occurrence of sparks by controlling the output of the high voltage at the same time as capturing the indication and maintaining the dust collection efficiency can be obtained.

  Further, the current change mitigating means has an inductance (L) component characteristic.

  Further, the current change relaxation means is arranged on the input side of the high voltage generation means. According to the present invention, a high voltage control circuit employing an inexpensive current change mitigating means with low withstand voltage and high versatility can be obtained by installing the current change mitigating means on the input side of the high voltage generating means. .

  Further, the current change mitigating means is arranged on the output side of the high voltage generating means. According to the present invention, the current change mitigating means is installed on the output side of the high voltage generating means, so that the high voltage current can be more reliably acted upon by directly mitigating the high voltage current. A circuit is obtained.

  Further, the current change mitigation means is arranged on both the input side and the output side of the high voltage generation means. According to the present invention, a high voltage control circuit can be obtained in which the current change mitigation effect is further enhanced by installing the current change mitigation means on the input side and output side of the high voltage generation means.

  Further, the current change rate calculating means calculates a differential value of the current change within a predetermined time. According to the present invention, by applying the differential value as the rate of change of the current value instead of the absolute value of the current as the current change detecting means, it is possible to capture the change at the initial stage of the current change and control the output voltage. A high voltage control circuit that can be obtained is obtained.

  In addition, an input voltage adjusting means for adjusting a voltage input to the high voltage generating means is provided, and when the current change rate exceeds a certain threshold, the input voltage to the high voltage generating means is adjusted by the input adjusting means. To do. According to the present invention, it is determined that a spark occurs when the current change rate due to the current value change rate exceeds a certain threshold value, and the output voltage is lowered by adjusting the input voltage to the high voltage generating means, thereby preventing the occurrence of the spark. A high voltage control circuit that can be prevented is obtained.

  Further, the present invention is characterized in that after the input voltage to the high voltage generating means is lowered due to the increase in current change rate, the output voltage is gradually increased until just before the current change rate changes. According to the present invention, after the output voltage is once lowered by comparing the current change rate, the output voltage is increased until immediately before the current change rate reaches the set threshold value, thereby maintaining the dust collection efficiency. A circuit is obtained.

  In addition, a semiconductor element is used as the input voltage adjusting means. And according to this invention, the high voltage control circuit which can control an output voltage at high speed as an input voltage adjustment means is obtained.

  Moreover, as a threshold value compared with a current change rate, the value which does not generate | occur | produce a spark with a dust collection means is set, It is characterized by the above-mentioned. According to the present invention, the threshold value for comparing the current change rate is set to a value along a pattern in which spark is generated in the dust collector, whereby a high voltage control circuit in which no spark is generated can be obtained.

  Further, when the input voltage is raised by the input voltage adjusting means, the comparison with the current change rate is not performed until the output voltage of the high voltage generating means reaches a constant value. According to the present invention, when the output voltage from the high voltage generating means is increased by the input voltage adjusting means, the output voltage is increased in a short time by not comparing with the current change rate until reaching a certain value. A high voltage control circuit can be obtained.

  Further, the comparison with the current change rate is performed only when the output voltage from the high voltage generating means is within a certain range. According to the present invention, it is possible to obtain a high voltage control circuit capable of increasing and decreasing the output voltage in a short time by comparing with the current change rate only while the output voltage is within a certain range.

  In addition, when a spark occurs in comparison with the current change rate, the setting threshold value for the current change rate is lowered. According to the present invention, when a spark has occurred, a high voltage control circuit capable of improving the spark prevention rate is obtained by lowering the set threshold value compared with the current change rate.

  Moreover, the dust collector of this invention is provided with the high voltage control circuit in any one of Claims 1-13 as described in Claim 14.

  According to the present invention, after making a rapid change in current moderate, by judging the state of current change not by the absolute value of the current but by the rate of change of the current, the signs of occurrence of sparks are caught at the initial stage, It is possible to provide a high voltage control circuit that can prevent the occurrence of sparks and maintain the dust collection efficiency by capturing the signs and controlling the high voltage output at the same time.

  In order to achieve the above object, the invention according to claim 1 of the present invention is a dust collecting means for collecting dust, a high voltage generating means for generating a high voltage to be applied to the dust collecting means, Current detecting means for detecting the current flowing to the dust collecting means, current change mitigating means for gradually changing the current flowing to the dust collecting means, and current change rate calculating means for calculating the rate of change of the detected current It is characterized in that the current change rate calculation means captures a sign of a sudden change in current and controls a high voltage before the current suddenly changes, and the rapid change in current is moderated. In the above, by judging the state of current change not by the absolute value of current but by the rate of change of current, it catches the sign of sparking as soon as possible, and catches the sign and controls the output of high voltage at the same time No spark has occurred It can be prevented to have the effect that it is possible to maintain the dust collection efficiency.

  In order to achieve the above object, the invention according to claim 2 of the present invention is characterized in that the current change mitigating means has an inductance (L) component characteristic, and mitigates a rapid current change. Thus, it is possible to reliably detect a change in current.

  According to a third aspect of the present invention, in order to achieve the above object, the current change mitigating means is arranged on the input side of the high voltage generating means, and the current change mitigating means is provided with a high voltage. By installing it on the input side of the generating means, an inexpensive current change mitigating means having a low withstand voltage and high versatility can be employed.

  According to a fourth aspect of the present invention, in order to achieve the above object, the current change mitigating means is arranged on the output side of the high voltage generating means. By installing it on the output side of the generating means, it has the effect that the current change can be more reliably reduced by directly reducing the high voltage current.

  In order to achieve the above object, the invention according to claim 5 of the present invention is characterized in that the current change mitigating means is arranged on both the input side and the output side of the high voltage generating means, By installing the relaxation means on the input side and output side of the high voltage generation means, the effect of reducing the current change can be further enhanced.

  According to a sixth aspect of the present invention, in order to achieve the above-mentioned object, the current change rate calculating means calculates a differential value of the current change within a predetermined time. By applying the differential value as the rate of change of the current value instead of the absolute value of the current as a means, there is an effect that the output voltage can be controlled by capturing the change at the initial stage of the current change.

  In order to achieve the above object, the invention according to claim 7 includes input voltage adjusting means for adjusting the voltage input to the high voltage generating means, and when the current change rate exceeds a certain threshold, the input adjustment is performed. The input voltage to the high voltage generating means is adjusted by the means, and it is determined that a spark occurs when the current change rate due to the current value change rate exceeds a certain threshold, and the input to the high voltage generating means is performed. By adjusting the voltage, the output voltage can be lowered and the occurrence of sparks can be prevented.

  In order to achieve the above object, according to the eighth aspect of the present invention, after the input voltage to the high voltage generating means is lowered by increasing the current change rate, the output voltage is gradually increased until immediately before the current change rate is changed. It is characterized in that the dust collection efficiency can be maintained without generating sparks by raising the output voltage until just before the current change rate reaches the set threshold again. .

  The invention according to claim 9 of the present invention is characterized in that a semiconductor element is used as the input voltage adjusting means in order to achieve the above object, and the semiconductor element is used as the input voltage adjusting means. Thus, the output voltage can be controlled at high speed.

  The invention according to claim 10 of the present invention is characterized in that, in order to achieve the above object, as a threshold value to be compared with the current change rate, a value at which no spark is generated in the dust collecting means is set. The threshold value for comparing the current change rate is set to a value in accordance with a pattern in which a spark is generated in advance, thereby preventing the occurrence of a spark.

  According to the eleventh aspect of the present invention, in order to achieve the above object, when the input voltage is raised by the input voltage adjusting means, the current change rate and the output voltage until the output voltage of the high voltage generating means reaches a constant value. When the output voltage from the high voltage generating means is increased by the input voltage adjusting means, it is not compared with the current change rate until reaching a certain value. The output voltage can be increased in a short time.

  The invention according to claim 12 of the present invention is characterized in that, in order to achieve the above object, the comparison with the current change rate is performed only when the output voltage by the high voltage generating means is within a certain range. Thus, the output voltage can be up and down in a short time by comparing with the current change rate only while the output voltage is within a certain range.

  The invention according to claim 13 of the present invention is characterized in that, in order to achieve the above object, when a spark occurs in comparison with the current change rate, the setting threshold value of the current change rate is lowered. There is an effect that when a spark is generated, the spark prevention rate can be improved by lowering the set threshold value compared with the current change rate.

  Moreover, the dust collector of this invention is provided with the high voltage control circuit in any one of Claims 1-13 as described in Claim 14, For example, a dust collector of this invention is characterized by the above-mentioned. By applying the high voltage control circuit, it is possible to obtain a dust collector that can prevent sparks and maintain dust collection efficiency.

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

(Embodiment 1)
FIG. 1 shows the configuration of a high voltage control circuit according to Embodiment 1 of the present invention. As shown in FIG. 1, a dust collecting electrode plate 1 as dust collecting means for collecting dust, a high voltage power source 2 as high voltage generating means for generating a high voltage to be applied to the dust collecting electrode plate 1, and a dust collecting electrode plate The current detection resistance 3 as a current detection means for detecting the current flowing through 1, the coil 4 as a current change relaxation means for relaxing the change in the current flowing through the current detection resistance 3, and the rate of change of the current detected by the current detection resistance 3 It comprises a controller 5 as a current change rate calculating means for calculating, and a semiconductor element 6 as an input voltage adjusting means for adjusting the input voltage to the high-voltage power supply 2. The dust collecting electrode plate 1 is composed of two metal plates, and a high voltage generated by the high-voltage power source 2 is applied to one side, and the remaining electrode plates are grounded. The positive output and the negative output of the high-voltage power source 2 may be grounded or the negative output may be grounded depending on the characteristics of the discharge generated by the dust collecting electrode plate 1. Regarding the current detection resistor 3 for measuring the value of the current flowing through the dust collecting electrode plate 1, if it is arranged on a line that is not grounded, the potential difference between the current detection resistor 3 and the ground increases, and the current detection resistor 3 and the controller 5 are connected. Because it becomes difficult to connect, it is placed on the grounding line. Therefore, the current detection resistor 3 is inserted between the output of the high voltage power source 2 and the dust collecting electrode plate 1 in the ground line. In addition, the coil 4 is also inserted in series with the current detection resistor 3.

  At this time, the coil 4 is inserted either between the high voltage power source 2 and the current detection resistor 3 or between the current detection resistor 3 and the dust collecting electrode plate 1, but is inserted on the output side of the high voltage power source 2 which is not grounded. Even so, there is no difference in the effect. The coil 4 can also be inserted on the low-voltage side of the high-voltage power supply 2, and in this case, the withstand voltage of the coil 4 itself can be low, so that an inexpensive and versatile coil can be selected. The high-voltage power supply 2 is generally a method in which an AC high voltage is changed to a DC high voltage by combining a high-voltage transformer and a rectifier circuit. The controller 5 may be anything such as a general-purpose controller, a microcomputer, etc. as long as it has a calculation function by software. As the semiconductor element, any element such as a thyristor or triac can be used as long as it can control the phase angle of the AC power supply voltage.

  When a discharge phenomenon or spark occurs in the dust collection electrode plate 1, a current several times the rated value flows through the dust collection electrode plate 1 for a very short time. As a normal spark control, the application of a high voltage to the dust collecting electrode plate 1 is stopped once the absolute value of a large current flowing during this very short time is detected. In general, the fixed time is set to about 1 second. After the time has elapsed, the output voltage is changed from 0 V to a constant rate, for example, 10% of the rated output voltage is set to a span of a fixed time, for example, 1 second. To increase the output voltage to the set voltage. Conditions when sparks are generated when the output voltage is increased to a set voltage, such as the condition that conductive dust adheres between the electrodes of the dust collecting electrode plate 1 and the insulation performance between the electrode plates deteriorates due to water wetting, etc. If they are aligned, a spark may occur again when the output voltage rises, the output voltage may be stopped after the spark is detected, and the output voltage may be raised again. In such a case, since the sparks are repeated at a constant period until the factor causing the sparks is removed, the dust collection efficiency is significantly lowered.

  The spark is generated for a very short time (about several nsec), and a current several times to several tens of times the rated value flows during this short time. An object of the present invention is to prevent a spark by capturing a sign of a change in which a spark occurs and controlling an output voltage before the spark occurs. However, in the very short time that this spark occurs, even if the sign of the change is caught in the early stage of the current change due to the spark occurrence, the time from when the current changes until the spark ends is very short. For this reason, a spark is almost generated at the moment of capturing. Therefore, a steep current change is moderated by inserting a coil having an inductance (L) component into a line through which a current flows. By slowing the change in current, a time delay can be made between the occurrence of a spark after the sign of the current change is detected. Next, in order to make the best use of the time delay obtained by relaxing the current change, let us consider capturing the current change as early as possible. In the conventional spark control, the presence / absence of a spark is all judged by the instantaneous absolute value of the current. If you want to capture the sign of spark occurrence with the instantaneous absolute value of current, it is necessary to set a threshold value lower than the threshold value that was previously determined to be spark occurrence. It becomes difficult to distinguish from current changes, and the possibility of false detection remains. Even if the threshold value is lowered, the time from the occurrence of spark to the end itself is short, so there is a possibility that the output voltage control cannot follow within that time. Therefore, change rate = differential value is applied to capture the initial stage of current change. The change in current when a spark occurs depends on the state of the spark, but is almost the same over time. Therefore, by determining the threshold value of the differential value from the transition of the spark, it is possible to detect the sign of the current change at the initial stage where the spark is generated.

  Regarding the relaxation of the current change, although it depends on the value of the inductance component of the coil 4 to be used, it is necessary to extend the time of the current change until the change of the current value can be detected and the adjustment of the output voltage becomes effective. However, if the inductance component is too large, there is a possibility that even if an attempt is made to control the output voltage, an attempt to lower the output voltage itself due to energy stored in the coil may not be achieved. In this case, since the output voltage does not decrease, there is a possibility that sparks may occur. Therefore, it is necessary to consider the selection of the coil 4. Judging by the rate of change of the current, not by the instantaneous absolute value of the current, the current change can be caught quickly at the initial stage of the current change, and immediately after that, the output voltage is controlled at high speed by the semiconductor element. It is possible to realize high voltage control that prevents generation.

  Regarding the insertion of the coil 4 as the current change mitigation means on the input side or output side of the high-voltage power supply 2 or on the input side and output side at the same time, it is necessary to make a judgment based on the cost and reliability required for high voltage control at that time. . When the coil 4 is inserted on the input side, a low price and high versatility can be selected for the coil 4 because the voltage is low. When inserted on the output side of the high-voltage power supply 2, since the current flowing through the high voltage portion can be directly relaxed, a high current change mitigating effect can be expected. However, since it becomes a high voltage component, the versatility is low and the cost is high. When it is inserted into the input side and output side of the high-voltage power supply 2, a higher and more reliable current change mitigation effect can be expected.

  In the case where the spark cannot be prevented with the threshold determined by the transition of the spark, the next spark can be prevented from being generated by lowering the setting threshold by the controller 5 slightly, for example, about 3 to 5%.

  When the current change rate exceeds the threshold value, the output voltage is lowered by the semiconductor element 6 to prevent the occurrence of sparks. However, 5 to 10% is sufficient as the width of the voltage drop. Although it is necessary to increase the output voltage once lowered, it is gradually increased to a set value at a rate of about 1% per second, for example. At this time, since the rate of change of the current is monitored, there is a case where the threshold value of the current tactics set in advance in the process of increasing the current is exceeded. As a countermeasure in this case, the current change rate is not compared with the threshold value until the output voltage is a constant value, for example, up to 95% of the set value, or the current change only when the output voltage is within a certain range, for example, 98% or more. By comparing the rate and the threshold value, the output voltage can be increased smoothly.

  When the high voltage control circuit according to the first embodiment of the present invention is mounted on a dust collector, a dust collector capable of preventing sparks and maintaining dust collection efficiency can be obtained.

  In particular, the present invention relates to a dust collector that must prevent a reduction in dust collection efficiency due to sparks, and a high voltage to be mounted on a dust collector that collects oil mist, for example. Applicable to control circuit.

1 is a configuration diagram of a high voltage control circuit according to an embodiment of the present invention. The figure which shows the control circuit which prevents the spark of a prior art example The figure which shows the method of preventing the spark generation of another prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dust collection electrode plate 2 High voltage power supply 3 Current detection resistance 4 Coil 5 Controller 6 Semiconductor element

Claims (14)

Dust collecting means for collecting dust, high voltage generating means for generating a high voltage to be applied to the dust collecting means, current detecting means for detecting a current flowing to the dust collecting means, and the dust collecting A current change relaxation means for gradual change of the current flowing through the means, and a current change rate calculation means for calculating the rate of change of the detected current, and the current change rate calculation means captures an indication of a sudden change in current, A high voltage control circuit that controls a high voltage before an electric current rapidly changes. 2. The high voltage control circuit according to claim 1, wherein the current change relaxation means has an inductance (L) component characteristic. 3. The high voltage control circuit according to claim 1, wherein the current change relaxation means is arranged on an input side of the high voltage generation means. 3. The high voltage control circuit according to claim 1, wherein the current change relaxation means is arranged on the output side of the high voltage generation means. 3. The high voltage control circuit according to claim 1, wherein the current change relaxation means is arranged on both the input side and the output side of the high voltage generation means. 6. The high voltage control circuit according to claim 1, wherein the current change rate calculating means calculates a differential value of a current change within a predetermined time. An input voltage adjusting means for adjusting a voltage input to the high voltage generating means is provided, and when the current change rate exceeds a certain threshold value, the input voltage to the high voltage generating means is adjusted by the input adjusting means. Item 7. The high voltage control circuit according to any one of Items 1 to 6. 8. The output voltage is gradually increased until the current change rate changes immediately after the input voltage to the high voltage generating means is lowered due to the increase in current change rate. High voltage control circuit. 9. The high voltage control circuit according to claim 1, wherein a semiconductor element is used as the input voltage adjusting means. 10. The high voltage control circuit according to claim 1, wherein the threshold value to be compared with the current change rate is set to a value along a pattern in which sparks are generated by the dust collecting means. 11. When the input voltage is raised by the input voltage adjusting means, the comparison with the current change rate is not performed until the output voltage of the high voltage generating means reaches a constant value. The high voltage control circuit described. The high voltage control circuit according to any one of claims 1 to 11, wherein the comparison with the current change rate is performed only when the output voltage of the voltage generating means is within a certain range. The high voltage control circuit according to any one of claims 1 to 12, wherein when a spark has occurred in comparison with the current change rate, a threshold value for setting the current change rate is lowered. A dust collector equipped with the high voltage control circuit according to claim 1.

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