KR101421668B1 - Electric motor control board built-in active zero harmonic filter - Google Patents

Abstract

The present invention relates to an electric motor controller having an embedded active image harmonic filter. The electric motor controller having the embedded active image harmonic filter according to an exemplary embodiment of the present invention includes: a zig-zag connection transformer electrically connected with R phase, S phase, T phase, and N phase busbars to remove an image harmonic wave through the internal circulation of the image harmonic wave; switching parts positioned on a line that connects the zig-zag connection transformer with the R, S, and T phase busbars, respectively; and a controller for electrically connecting the zig-zag connection transformer to the R, S, and T phase busbars or disconnecting the zig-zag connection transformer from the R, S, and T phase busbars by turning on or turning off the switching parts.

Description

ELECTRIC MOTOR CONTROL BOARD BUILT-IN ACTIVE ZERO HARMONIC FILTER WITH OPTICAL IMAGE Harmonic Filter

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control panel, and more particularly, to an electric motor control panel having an active image harmonic filter.

When the soft start or the inverter start method is used when the motor is driven, an image harmonic due to the motor drive is generated. Image harmonics are superimposed on the neutral line of the 3-phase 4-wire distribution system, and the size of the image is tripled. Image harmonic current on the neutral line can cause various types of disturbances in the power system. Harmonics of the image may cause tripping of the breaker due to overcurrent, temperature rise and deterioration of the transformer, malfunction of the protective device, overheating of the neutral wire / fire, communication trouble and the like. In order to reduce the image harmonics, an image harmonic filter may be installed between the transformer secondary side and the load end motor control board. In order to maximize the image harmonic reduction rate, it is preferable that the image harmonic filter is installed at the position closest to the motor, that is, the motor control panel. As is well known, the image harmonic filter includes a zigzag wiring transformer, and the image harmonic filter can be removed by circulating the input image from the N phase into the zigzag wiring transformer. Such an image harmonic filter can prevent the image harmonics from flowing into the power source side by removing the image minute from the motor side. However, it can cause problems such as an increase of the electric charge due to the image harmonics and a decrease of the power factor. Specifically, The zigzag connection transformer in the image harmonic can act as a load to increase the electricity rate, and the power factor can be lowered by the reactance component of the zigzag connection transformer.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric motor control panel having an image harmonic filter incorporated therein so that an image harmonic filter can maximally maintain a function of filtering image harmonics, .

It is another object of the present invention to provide an electric motor control board having a temperature monitoring function.

It is another object of the present invention to provide an electric motor control board having an image harmonic filter incorporated therein which can minimize power consumed in an image harmonic filter.

Other objects of the present invention will become readily apparent from the following description of the embodiments.

According to an aspect of the present invention, there is provided an electric motor control board including an image harmonic filter, the motor control board including an R-phase busbar, an S-phase busbar, a T A zigzag wiring transformer electrically connected to the phase busbar and the N phase busbar to remove image harmonics by circulating image harmonics internally; A switching unit located on a line connecting the zigzag wiring transformer and the R phase booth bar, the S phase booth bar and the T phase booth bar, respectively; and switching the zigzag wiring transformer on the R phase And a control section for electrically connecting or disconnecting the busbar, the S phase busbar, and the T phase busbar.

Here, when the temperature of the zigzag wiring transformer is higher than a preset upper limit temperature, when the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase booth bar is lower than a preset lower limit value, The S phase booth bar and the S phase booster bar and the Z phase transformer is turned off by turning off the switching unit when the load is equal to or less than a predetermined load lower limit value, T can be electrically isolated from the top of the booth.

The control unit scans a current image on the N-phase bus bar at a predetermined cycle to calculate a time-averaged image average value, and the zigzag wiring transformer Can be electrically separated from the R-phase bus bar, the S-phase bus bar, and the T-phase bus bar.

The controller calculates a value obtained by subtracting a 3-phase unbalanced current value from a current value on the N-phase bus bar only in a time zone in which the calculated image minute average value is greater than a predetermined image minute lower limit value, A value obtained by subtracting the three-phase unbalanced current value from the current value on the upper bus bar can be used to control the on or off state of the switching unit.

In addition, when the temperature of the zigzag wiring transformer is less than a predetermined upper temperature limit, when the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar exceeds a predetermined lower limit value, Wherein the Z-transformer is connected to the R-phase busbar, the S-phase booster, the S-phase booster, the S-phase booster, the S-phase booster, And the T-phase busbar is electrically connected to the T-phase busbar. When the temperature of the zigzag wiring transformer is equal to or higher than the preset upper limit temperature, a value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase busbar exceeds a predetermined lower limit value , When the average value of the image minute is the time zone exceeding the preset image minute lower limit value, The S-phase busbar and the T-phase busbar can be electrically disconnected from the R-phase busbar, the S-phase busbar and the T-phase busbar.

The control unit may include a control unit for electrically separating the zigzag wiring transformer from the R phase booster bar, the S phase booster bar, and the T phase booster bar only when the zigzag wiring transformer corresponds to a predetermined separation time.

In addition, the controller may control the switching unit to be turned on or off according to the reset separation time when the separation time after the separation time is reset.

In addition, it is preferable that a temperature is received from a temperature sensor provided on the R phase booth bar, the S phase booth bar, the T phase booth bar and the N phase booth bar, and when at least one temperature value of the received temperature values is not less than a predetermined temperature upper limit value And may further include an alarm providing unit for providing an alarm.

As described above, according to the present invention, when the image harmonic filter is separated from the booth bar, the power factor reduction and the electricity rate increase by the image harmonic filter can be minimized.

If the temperature value of the zigzag wiring transformer measured by the temperature sensing unit is equal to or higher than a preset upper limit value even if the connection condition is satisfied, the image harmonic filter is separated from the booth bar in preference to the connection condition, An accident caused by an overload can be prevented.

Further, by scanning the image minute at a predetermined cycle and controlling connection / disconnection of the image harmonic filter using the scanned value up to the next cycle, the life of the control module is lengthened, and power consumption of the control module is minimized .

Further, by operating the current calculating unit, the power amount obtaining unit, and the power amount providing unit only when the image minute average value is less than the preset image minute lower limit value during the scanned time period, power consumption is minimized during control for connecting / disconnecting the image harmonic filter .

Further, by monitoring the temperature of the bus bar on the motor control panel, an accident caused by overheating in the motor control panel can be prevented.

1 is a block diagram of a motor control board according to a preferred embodiment of the present invention.
Fig. 2 is a functional block diagram of the control unit of Fig. 1. Fig.
FIG. 3 is a view for explaining an operation in which the switch opening and closing part opens and closes the switch according to the scanning result of the current scanning part of FIG. 2;

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

Like reference numerals are used for like elements in describing each drawing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, .

On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention.

The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, a motor control panel according to a preferred embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a block diagram of a motor control board according to a preferred embodiment of the present invention. Fig. 2 is a functional block diagram of the control unit of Fig. 1. Fig. FIG. 3 is a view for explaining an operation in which the switch opening and closing part opens and closes the switch according to the scanning result of the current scanning part of FIG. 2; Hereinafter, in order to clarify the gist of the present invention, a general configuration of a conventional motor control panel will be briefly described.

Referring to FIG. 1, the motor control panel 1 may include a main breaker 50, a relay 1000, and an active image harmonic filter 2000.

An R-phase busbar 10, an S-phase busbar 20, a T-phase busbar 30 and an N-phase busbar 40 may be positioned at the output ends of the main breaker 50 and the MCCB. An electric motor (not shown) or a motor (not shown) is connected to the R phase busbar 10, the S phase busbar 20, the T phase busbar 30 and the N phase busbar 40, Can receive. A sub-circuit breaker (not shown) may be installed on the line connecting the motor or motor with the R phase busbar 10, S phase busbar 20, T phase busbar 30 and N phase busbar 40 have. An electromagnetic contactor (not shown) may be installed in series with the sub-circuit breaker. The electromagnetic contactor is capable of interrupting the electric power supplied to the motor or the motor by being turned on / off according to an external control command.

The R phase busbar 10, the S phase busbar 20, the T phase busbar 30 and the N phase busbar 40 are respectively connected to the R phase busbar 10, the S phase busbar 20, Temperature sensors 11, 21, 31 and 41 for detecting the temperatures of the upper booster bar 30 and the N-phase booster bar 40 may be provided. The temperature sensors 11, 21, 31 and 41 control the temperatures of the R phase busbar 10, the S phase busbar 20, the T phase busbar 30 and the N phase busbar 40, respectively, ).

The relay 1000 may include a power calculation unit 1100, a power amount providing unit 1200, and an alarm providing unit 1300.

The power calculation unit 1100 calculates the currents on the R, S, and T phases using the output values of CT (current transformers) 1101, 1102, 1103, and 1104 that detect the respective currents on R, S, and T, (Load) of the entire load connected to the motor control panel 10 can be calculated at a predetermined cycle using the current value.

The power amount providing unit 1200 can provide the total load power consumption calculated by the power amount calculating unit 1100 to the active image harmonic filter 2000 side.

The alarm providing unit 1300 receives the temperature from the temperature sensors 11, 21, 31, and 41, and can provide an alarm when the temperature value of at least one of the received temperature values is equal to or greater than a predetermined temperature upper limit value. Thus, an accident caused by overheating of the bus bar in the electric motor control panel can be prevented in advance.

The active image harmonic filter 2000 may include a zigzag wiring transformer 2100 and a control module 2200.

The zigzag wiring transformer 2100 is connected to the R-phase bus bar 10, the S-phase bus bar 20, the T-phase bus bar 30 and the N-phase bus bar 40, The image harmonics can be removed by circulating the input image harmonics in the zigzag wiring transformer. Since the zigzag wiring transformer 2100 has a resistance component, heat may be generated in the process of removing image harmonics. In the case where the heat is excessive, there is a fear that performance deteriorates due to deterioration of the zigzag wiring transformer 2100 and that a fire occurs in the motor control board 1. Therefore, it is necessary to prevent overheating or overload in the zigzag wiring transformer 2100. To this end, a temperature sensing unit 2110 may be installed on one side of the zigzag wiring transformer 2100. The temperature sensing unit 2110 senses the temperature of the zigzag wiring transformer 2100 and can transmit the sensed temperature value to the control module. When the temperature of the zigzag wiring transformer 2100 is equal to or higher than the predetermined upper limit value, the control module 2200 controls the zigzag wiring transformer 2100 to be connected to the R phase busbar 10, the S phase busbar 20, (30). Thereby, the overload of the zigzag wiring transformer 2100 can be prevented. Of course, when the temperature of the zigzag wiring transformer 2100 is lowered below the predetermined upper limit value in the state where the zigzag wiring transformer 2100 is disconnected, the zigzag wiring transformer 2100 is connected to the R phase busbar 10, And can be connected to the bar 20 and the T-phase bus bar 30.

The control module 2200 may include switching units 2211, 2212, and 2213, a current measurement unit 2220, a control unit 2230, and a storage unit 2240.

The switching units 2211, 2212 and 2213 are located on the line electrically connecting the zigzag wiring transformer 2100 to the R phase busbar 10, the S phase busbar 20 and the T phase busbar 30, can do. The switching units 2211, 2212, and 2213 may be implemented as semiconductor switching devices or relays. The switching units 2211, 2212 and 2213 perform on / off operations according to the control operation of the control unit 2300 to switch the zigzag wiring transformer 2100 from the R phase busbar 10 to the S phase busbar 20 and the T phase bus bar 30 or electrically isolates the zigzag wiring transformer 2100 from the R phase busbar 10, the S phase busbar 20 and the T phase busbar 30 .

The current measuring unit 2220 is connected to the CTs 2221, 2222, 2223, and 2224 located in the R phase busbar 10, the S phase busbar 20, the T phase busbar 30, ) Can be used to measure the currents on the R-phase busbar 10, the S-phase busbar 20, the T-phase busbar 30 and the N-phase busbar 40. The current measuring unit 2220 may convert the measured current value into a digital signal, for example, a signal that can be processed by the controller 2230, and may transmit the digital signal to the controller 2230.

The control unit 2230 controls on / off operations of the switching units 2211, 2212, and 2213 using the current values received from the current measurement unit 2220 and the temperature values received from the temperature sensing unit 2110, The zigzag connection transformer 2100 is electrically connected to the R phase busbar 10, the S phase busbar 20 and the T phase busbar 30 or the zigzag connection transformer 2100 is connected to the R phase busbar 10, S phase booth bar 20 and T phase booth bar 30, respectively.

2, the controller 2230 may include a current calculator 2231, a current scanning unit 2232, a power amount acquiring unit 2233, a timer 2234, and a switch opening and closing unit 2235.

The current calculator 2231 calculates the current value of the N phase bus bar 40 using the current values on the R phase busbar 10, the S phase busbar 20 and the T phase busbar 30 received from the current measuring unit 2220 ) Of the three-phase unbalanced current. Here, the three-phase unbalanced current value may be a peak value of the vector sum of current values on the R-phase bus bar 10, the S-phase bus bar 20 and the T-phase bus bar 30. The current calculation unit 2231 can provide a value obtained by subtracting the 3-phase unbalanced current value from the current value on the N-phase bus bar 40 to the switch open / close unit 2235. At this time, when the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar 40 is equal to or less than a preset lower limit value, the switch opening / closing part 2235 turns off the switching parts 2211, 2212, and 2213, The zigzag wiring transformer 2100 can be separated from the R-phase bus bar 10, the S-phase bus bar 20, and the T-phase bus bar 30. When the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase busbar 40 is equal to or less than the predetermined lower limit value, since the image minute is small, the active image harmonic filter 2000 is connected to the R- It is not necessary to connect it to the bar 20 and the T-phase bus bar 30. Therefore, when the necessity of filtering the active image harmonic filter 2000 is small, the active image harmonic filter 2000 is separated from the R phase busbar 10, the S phase busbar 20 and the T phase busbar 30 The power factor reduction by the active image harmonic filter 2000 and the increase of the electricity rate can be minimized. The current calculator 2231 can calculate a value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar 40 at a predetermined cycle. Alternatively, when the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar 40 exceeds a predetermined lower limit value, the switch open / close unit 2235 turns on the switching units 2211, 2212, and 2213 The zigzag wiring transformer 2100 can be connected to the R phase bus bar 10, the S phase bus bar 20 and the T phase bus bar 30.

The current scanning unit 2232 can scan the image harmonics on the N-phase bus bar 40 according to an external command or a predetermined period. The time interval to be scanned may be one day. Here, the image harmonics to be scanned may be a predetermined band, for example, three harmonics, six harmonics, nine harmonics, and the like. The image harmonics to be scanned may be three harmonics, and the scanned image harmonic bandwidth may be unlimited. The current scanning unit 2232 can convert the magnitude of the scanned image harmonic into an average value in a predetermined time unit. Referring to FIG. 3, in FIG. 3, the horizontal axis indicates time, and the vertical axis indicates image minutes. 3 shows a result of scanning the current scanning unit 2232 for one day. The dotted line may be, for example, a peak value of a sum of three harmonics and six harmonics that the current scanning unit 2232 converts. And, the height of the bar graph can mean the average value of the images in each time zone (for 1 hour). The current scanning unit 2232 may store the image minute average value in each time period during the day as shown in FIG. 3 in the storage unit 2240. Thereafter, the switch open / close unit 2235 switches the zigzag wiring transformer 2100 to the R-phase busbar 10, the S-phase busbar 20, and the T-phase busbar 2030 in a time zone in which a day- Can be separated from the bar (30). The switch open / close unit 2235 switches the zigzag wiring transformer 2100 to the R-phase busbar 10, the S-phase busbar 20, and the T-phase busbar 2030, Can be connected to the bar (30).

 For such a method, a timer 2244 may be provided, and the switch open / close unit 2235 acquires the time information from the timer 2244, and the zigzag wiring transformer 2100 Can be separated from the R-phase bus bar 10, the S-phase bus bar 20 and the T-phase bus bar 30. Image harmonics may be generated after diagnosis of image harmonics in a specific region or a specific motor control panel and image harmonic filters are installed according to the diagnosis results. The image harmonic filter can be selectively connected to or disconnected from the bus bar according to the image harmonic generation rate at the load side installed after the image harmonic filter is installed. Specifically, the present invention scans the image harmonics in units of a predetermined period, for example, one month after the installation, and when the image minute mean value is equal to or lower than a preset image minute lower limit value according to the scanned result, the zigzag wiring transformer 2100 R-phase booth bar 10, S-phase booth bar 20 and T-phase booth bar 30, respectively. Accordingly, when filtering of the image harmonic filter is unnecessary, the active image harmonic filter 2000 is separated from the R-phase bus bar 10, the S-phase bus bar 20 and the T-phase bus bar 30 It is possible to prevent the power factor from being lowered by the video harmonic filter and the electricity rate hike. Of course, it is also possible to monitor the image harmonics of the N phase in real time and to separate the image harmonic filter when the image harmonics are below a predetermined lower limit value. However, such a method may consume excessive power to calculate image harmonics in real time, And the maintenance cost is increased by shortening the lifetime of the switching part through excessive switching when the change is repeated between the predetermined lower limit value. The usage patterns of power consumers can be constant on a monthly basis or in a unit of a change of day. Accordingly, the image portion of the N-th image is scanned on a monthly basis, and the switch open / close unit 2235 switches the zigzag wiring transformer 2100 in the same pattern for one month according to the scanned result, Even if the R-phase busbar 10, the S-phase busbar 20, and the T-phase busbar 30 are separated from each other, a sufficient reduction in the image harmonics can be obtained. At the same time, it is possible to minimize the power factor reduction and the electric charge increase by the image harmonic filter, and to minimize the maintenance cost of the image harmonic filter and the power consumption of the image harmonic filter.

Alternatively, the designer can set the separation time of the image harmonic filter, and the switch opening / closing part 2235 sets the zigzag wiring transformer 2100 to the R-phase busbar 10, the S-phase busbar 20, , And T-phase bus bar (30). Therefore, the predetermined separation time can be variably set by the designer depending on the installation position. Here, the time outside the separation time may be the connection time. At the connection time, the switch open / close unit 2235 can connect the zigzag wiring transformer 2100 to the R-phase bus bar 10, the S-phase bus bar 20, and the T-phase bus bar 30.

2, the power amount acquisition unit 2233 can acquire the power amount related information provided by the power amount providing unit 1200. [ Here, the electric power amount-related information may be the amount of electricity used by the electric load (hereinafter referred to as " load amount ") connected to the electric motor control board 1. At this time, the switch open / close unit 2235 turns off the switching units 2211, 2212, and 2213 when the load amount is equal to or less than the preset lower limit value, thereby switching the active image harmonic filter 2000 from the R phase busbar 10, Can be separated from the bus bar (20) and the T-phase bus bar (30). The active image harmonic filter 2000 can be connected to the R-phase busbar 10, the S-phase busbar 20, and the T-phase busbar 30 when the post-separation load is greater than a predetermined lower load limit.

The switch open / close unit 2235 switches the switching unit 2235 according to a value obtained by subtracting the three-phase unbalance current from the load amount, the temperature on the zigzag wiring transformer, the image minute average value by the measured time period, The zigzag wiring transformer 2100 is selectively switched from the R-phase busbar 10, the S-phase busbar 20 and the T-phase busbar 30 by controlling on / Separated or connected.

The conditions under which the switch open / close unit 2235 controls ON / OFF of the switching units 2211, 2212, and 2213 can be summarized as shown in Table 1 below.

Separation condition When the temperature value measured by the temperature sensing unit 2110 is equal to or higher than the preset upper temperature limit value
- When the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase busbar 40 is equal to or less than a predetermined lower limit value
- When the average value of the image minute is less than the preset lower limit value (separation time) according to the result of scanning
- When the load is below the lower limit of the preset load
- If it is the preset separation time Connection condition - when the temperature value measured by the temperature sensing unit 2110 is less than the predetermined temperature upper limit value
- When the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar (40) is greater than a predetermined lower limit value
- According to the result of scanning, if the average value of the image minute is the time zone (connection time) exceeding the preset lower limit of image
- When the load exceeds the preset lower load limit
- When the time outside the preset separation time (connection time)

The switch open / close unit 2235 can turn off the switching units 2211, 2212, and 2213 to electrically disconnect the image harmonic filter from the bus bar when any one of the above separation conditions is satisfied. Alternatively, the switch open / close unit 2235 can turn on the switching units 2211, 2212, and 2213 to electrically connect the video harmonic filter to the bus bar when any one of the above connection conditions is satisfied. (1) When the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase busbar (40) is greater than a predetermined lower limit value. 2) (3) a case where the load is over a predetermined lower limit value of the load, and (4) a case where the load is outside the preset separation time, the temperature value measured by the temperature sensing unit 2110 When the upper limit value is equal to or more than the upper limit value, the switch opening / closing unit 2235 turns off the switching units 2211, 2212, and 2213, so that the image harmonic filter can be electrically disconnected from the bus bar in priority to the connection condition. This may be to prevent an accident caused by an overload of the image harmonic filter.

In order to minimize the operations of the current calculating unit 2231, the power amount obtaining unit 2233 and the power amount providing unit 1200, only when the image minute average value in the time period scanned by the current scanning unit is lower than the image difference lower limit value, The power amount acquisition unit 2231, the power amount acquisition unit 2233, and the power amount providing unit 1200 can be operated. That is, the current calculator 2231 calculates a value obtained by subtracting the 3-phase unbalance current from the N-phase busbar current only when the image minute average value in the time period scanned by the current scanning unit 2232 is equal to or lower than the image divider lower limit value, The strategy amount providing unit 1200 transfers the load amount to the power amount acquiring unit 2233 only when the image minute average value in the time period scanned by the current scanning unit is equal to or lower than the image difference lower limit value, The power amount acquiring unit 2233 can transmit the acquired amount of power to the switch open / close unit 2235.

The present invention is also applicable to a method of electrically isolating the image harmonic filter from the booth bar when the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar 40 is less than a predetermined lower limit value, A method of electrically isolating the image harmonic filter from the booth bar when the minute average value is lower than a preset lower limit of the image, a method of electrically separating the image harmonic filter from the booth bar when the load is below the predetermined load limit, And a method of electrically separating the image harmonic filter from the booth at the time may be used. At this time, the components corresponding to the unused method can be implemented in an omitted form. For example, when only the method of electrically separating the image harmonic filter from the booth bar is used at a predetermined separation time, the power amount providing unit 1200, the current calculating unit 2231, the current scanning unit 2232, 2233 may be implemented in an abbreviated form. In the case of using only the method of electrically separating the image harmonic filter from the booth bar at a predetermined separation time, the structure of the control module 2200 is very simplified, and the production cost of the image harmonic filter can be very low. At this time, since the time zone in which the amount of image harmonics is small may be changed according to the load state after installation, the control unit 2200 preferably includes a setting unit (not shown) that can reset the separation time by the operator. When the separation time is reset by the operator in operation, the control unit 2200 can control ON / OFF of the switching units 2211, 2212, and 2213 according to the reset separation time. In the above, the method of using the separation time may replace the method of using the image minute average value. At this time, the separation time can be replaced with a time zone in which the average value of the image during the day is less than the predetermined lower limit of the image.

The switch open / close unit 2235 can control ON / OFF of the switching unit in a two-step manner as shown in the following Table 2 when the temperature value measured by the temperature sensing unit 2110 is equal to or higher than a preset upper limit temperature value.

Zigzag wiring transformer temperature (t) Control method t? t1 Switching section ON t1 < t &lt; t2 Repeat ON and OFF states (PWM method) t> t2 Switching part OFF

The switch opening and closing part 2235 can turn on the switching parts 2211, 2212, and 2213 when the temperature of the zigzag wiring transformer 2100 is lower than a predetermined first reference temperature t1. When the temperature of the zigzag connection transformer 2100 exceeds the first reference level t1 and is equal to or lower than the second reference temperature t2, the ON and OFF states of the switching units 2211, 2212, and 2213 can be repeated have. By inserting the OFF state between the ON states of the switching units 2211, 2212, and 2213, the temperature rise of the zigzag wiring transformer 2100 can be suppressed. The off-state time between the on-states can be appropriately selected by the designer. When the temperature of the zigzag wiring transformer 2100 exceeds the predetermined second reference temperature t2, the switching units 2211, 2212, and 2213 can be turned off. When the temperature of the zigzag wiring transformer 2100 exceeds the predetermined first reference t1 and is equal to or lower than the second reference temperature t2 as described above, the ON and OFF states of the switching units 2211, 2212, and 2213 are repeated It is possible to prevent the zigzag wiring transformer 2100 from entering the overheated state and to maintain the filtering function of the zigzag wiring transformer 2100 as much as possible. When the temperature of the zigzag wiring transformer 2100 exceeds the predetermined second reference temperature t2, the zigzag wiring transformer 2100 is turned to an overheated state by turning off the switching units 2211, 2212, and 2213 By separating the zigzag wiring transformer 2100 when exposed, an explosion accident due to overheating of the zigzag wiring transformer 2100 can be prevented.

1, the storage unit 2240 may store algorithms, variables, parameters, and the like necessary for performing the above-described operations.

As described above, according to the present invention, when the image harmonic filter is separated from the booth bar, the power factor reduction and the electricity tariff increase due to the image harmonic filter can be minimized.

In addition, even when the connection condition is satisfied, the image harmonic filter is separated from the booth bar in preference to the connection condition when the temperature value of the zigzag wiring transformer measured by the temperature sensing unit is equal to or higher than a preset upper temperature limit, An accident caused by an overload can be prevented.

Further, by scanning the image minute at a predetermined cycle and controlling connection / disconnection of the image harmonic filter using the scanned value up to the next cycle, the life of the control module is lengthened, and power consumption of the control module is minimized .

Also, by operating the current calculating unit 2231, the power amount obtaining unit 2233, and the power amount providing unit 1200 only when the image minute average value in the scanned time zone is less than the preset image minute lower limit value, Power consumption can be minimized in the control for separation.

When the alarm providing unit 1300 receives the temperature from the temperature sensors 11, 21, 31 and 41 and the temperature value of at least one of the received temperature values is equal to or higher than a preset upper temperature limit value, , It is possible to prevent an accident caused by overheating of the bus bar in the motor control panel.

It will be apparent to those skilled in the relevant art that various modifications, additions and substitutions are possible, without departing from the spirit and scope of the invention as defined by the appended claims. The appended claims are to be considered as falling within the scope of the following claims.

10: R phase booth bar
20: S phase booth bar
30: T booth bar
40: N phase booth bar
50: main breaker
111, 21, 31, 41: temperature sensor
1000: Relay
1100:
1101, 1102, 1103: CT
1200: Supply of electricity
1300: Offering alarm
2000: Active image harmonic filter
2100: Zigzag wiring transformer
2110: Temperature sensing unit
2200: Control module
2211, 2212, and 2213:
2220: current measuring unit
2221, 2222, 2223, 2224: CT
2230:
2231:
2232: current scanning unit
2233:
2234: Timer
2235: Switch opening /
2240:

Claims (8)

In an electric motor control board having an active image harmonic filter,
A zigzag wiring transformer electrically connected to the R phase booth bar, the S phase booth bar, the T phase booth bar and the N phase buss bar to eliminate image harmonics by circulating image harmonics internally;
A switching unit located on a line connecting the zigzag connection transformer with the R phase busbar, the S phase busbar and the T phase busbar, respectively;
And a control unit electrically connecting or disconnecting the zigzag wiring transformer to the R phase busbar, the S phase busbar, and the T phase busbar by turning the switching unit on or off,
Wherein,
And the zigzag wiring transformer is connected to the R phase bus bar in a time zone where the calculated image minute average value is equal to or lower than a predetermined lower limit of the video image by scanning the image of the current on the N phase bus bar at a predetermined cycle, , The S-phase busbar and the T-phase busbar. The method according to claim 1,
Wherein,
When the temperature of the zigzag wiring transformer is equal to or higher than a preset upper limit value and the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase booth bar is less than a preset lower limit value, , The switching unit is turned off so that the zigzag wiring transformer is electrically connected to the R-phase busbar, the S-phase busbar, and the T-phase busbar by electrically turning off the switching unit when the load corresponds to at least any one of the cases To the motor control panel. delete The method according to claim 1,
Wherein,
Calculating a value obtained by subtracting a 3-phase unbalance current value from a current value on the N-phase bus bar only in a time zone in which the calculated image minute average value exceeds a preset image division lower limit value, And the on / off state of the switching unit is controlled by using a value obtained by subtracting the three-phase unbalanced current value from the three-phase unbalanced current value. The method according to claim 1,
Wherein,
When the temperature of the zigzag wiring transformer is less than a preset upper limit value and the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar exceeds a predetermined lower limit value, Phase busbar, the S-phase busbar, and the T-phase busbar by turning on the switching unit when the load corresponds to at least one of a case where the load is greater than a predetermined lower limit of the load, Electrically connected,
When the temperature of the zigzag-connected transformer is equal to or higher than a preset upper limit temperature,
When the value obtained by subtracting the 3-phase unbalance current value from the current value on the N-phase bus bar is greater than a predetermined lower limit value, the image minute average value is in a time zone exceeding a preset video minute lower limit value, The S-phase busbar, the S-phase busbar, and the T-phase busbar are electrically isolated from each other. The method according to claim 1,
Wherein,
Only when it corresponds to the predetermined separation time,
And a control unit electrically separating the zigzag wiring transformer from the R phase booster bar, the S phase booster bar, and the T phase booster bar. The method according to claim 6,
Wherein,
Wherein the control unit controls the switching unit to be turned on or off according to the reset separation time when the separation time is reset after the setting of the separation time. The method according to claim 1,
And a temperature sensor (11, 21, 31, 41) provided on the R phase booth bar, the S phase booth bar, the T phase booth bar and the N phase booth bar, Further comprising an alarm providing unit for providing an alarm when the value is equal to or greater than a preset upper temperature limit value.

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