KR102350330B1 - Balancing Transformer for minimizing leakage current - Google Patents

Abstract

A balancing transformer (100) for reducing a leakage current according to the present invention is equipped with: a first winding that generates a magnetic field by a current flowing in the same direction as the current flowing in a load direction constituting a balancing transformer; a second winding that generates the magnetic field by the current flowing in the same direction as the current flowing in the direction opposite to the load direction; and a third winding that generates the magnetic field to compensate for a difference between a supply current and a feedback current. Therefore, the present invention is capable of having an effect of reducing other damages from an electric shock.

Description

Balancing Transformer for minimizing leakage current}

According to the present invention, current flows from the charging unit to the earth through the human body when the electric devices are submerged and the leakage current to the earth through the charging unit or the human body comes into contact with the exposed charging unit.

In order to prevent accidents caused by this, the leakage path from the charging part to the ground is

It relates to a safety device for preventing electric shock, which aims to minimize an electric shock accident by minimizing a leakage current that is formed and flows.

In addition, when a leakage current occurs due to submersion of a charging part such as submergence, even though it is an electrical and electronic equipment that must be operated by supplying power, the leakage current breaker is operated due to the leakage current, causing secondary damage.

In order to minimize such secondary damage, it is related to the safety device for preventing electrical accidents that is intended to reduce the leakage current to a size that is not dangerous to the human body and prevents the power of electrical and electronic equipment that must be operated and operated inevitably from being cut off. will be.

Various types of disasters that cause physical loss as well as casualties due to electric leakage and electric shock are occurring.

In particular, as electric lines are underground, frequent electric shock accidents are occurring due to submersion, and furthermore, damage is caused by blocking the electricity supply during submersion. If only the power supply through the line is maintained, the continuous operation of the equipment capable of operating normally is required, and the equipment that enables the continuous operation is being used. This related technology is disclosed in Korean Patent Registration No. 10-2270589, and in addition to

Safety devices for preventing various types of electric disasters such as grounding disconnection detection and power protection device (Korean Patent 10-1705090), an earth leakage prevention device in case of submersion, and an earth leakage and electric shock protection method using the same (Korea Patent 10-2181899) being used or developed.

In particular, Korean Patent Registration No. 10-2181899 states, “In the event of an electric shock accident, an electric shock canceling unit is provided that reduces the amount of current dangerous to the human body by canceling the magnetic field caused by the current by the transformer. Since the operation is not described to the extent that it can be easily performed by a person with ordinary skill in the field, it is not possible to know whether the actual operation is performed or not, and even if it is operated, the charging part is submerged or the human body, etc. It is not suitable for the prevention of electric shock accidents as it is operated after electric shock occurs.

In addition, the magnitude of the leakage current varies depending on the state of the line including the human body that forms between the charging part and the ground, and therefore the current flowing through the coil to which the forward current (load direction) of the balancing transformer is applied and the reverse current (load) The current flowing in the coil to which the current flowing from the line returning to the power source) is applied varies, and thus the magnitude of the magnetic field generated in the coil to which the forward current is applied and the coil to which the reverse current is applied are different, so that the balance of the current is maintained There is a problem that does not work, and the current flowing into the ground through the exposed charging part increases, so that the electric shock accident cannot be properly dealt with.

In addition, although it has been suggested in Korean Patent Registration No. 10-0749837, which is an example of using a balance transformer to equalize the current flowing in the load connected in parallel, the current flowing in the load through the coil connecting the flowing current path in the reverse direction Although the theoretical background of maintaining the balance is suggested, this is for the purpose of maintaining the balance of the current flowing in the parallel load. will be.

Korean Patent No. 10-2181889 (Notice on November 24, 2020) Korean Patent No. 10-1442527 (Announced on September 26, 2014) Korean Patent No. 10-0749837 (Announced on August 21, 2007)

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems described above. When a human body comes into contact with an exposed charging part or when an electrical and electronic device product is submerged, a current leakage circuit in multiple paths between the charging part and the ground, a submersion circuit and a load due to immersion between the charging part and the charging part, are formed in parallel.

As described above, not only various current paths are formed between the charging part and the earth and the load, but also impedance values such as resistance on the path through which the current flows according to the submersion condition, the contact condition between the charging part and the earth, the grounded earth condition, etc. For convenience of explanation, it is referred to as “leakage load”) is changed.

Due to this, the magnitude of the current between the windings flowing through the balancing transformer is different, so that the leakage current increases.

To prevent this, the present invention minimizes the leakage current in response to the environmental change through which the leakage current flows by actively interacting with the magnetic field between the windings of the balancing transformer to suit the situation in which the electric and electronic device product is submerged or the charging part is exposed as described above. An object of the present invention is to provide a balancing transformer for reducing leakage current.

In order to achieve the above object, the balancing transformer 100 for reducing leakage current according to the present invention is a terminal connected to an active terminal that receives an input power AC power (hereinafter referred to as “power”), a terminal PS terminal, and the earth and Power is supplied from the NS terminal, which is a terminal electrically connected to the ground or neutral wire,

The balancing transformer 100 for reducing leakage current that is supplied with power from the PS terminal and the NS terminal, which is the terminal from the power source, is a current direction (IL) flowing in the direction of the load 200 constituting the balancing transformer 10; For convenience, it is referred to as “supply current”.) The first winding N2, which generates a magnetic field by a current flowing in the same direction, and a current direction that flows in the opposite direction to the load direction (IL; hereinafter, for convenience of explanation) The second winding (N3) generates a magnetic field by a current flowing in the same direction as the “return current”), the third winding (N1) generates a magnetic field to compensate for the difference between the supply current and the feedback current, the supply current and A supply current sensing unit (7) for detecting the size, a feedback current sensing unit (8) for sensing the size of the feedback current,

The third winding is calculated so that the magnitude of the current input from the supply current sensing unit 7 and the feedback current sensing unit 8 is equal to the magnitude of the magnetic field generated by the supply current and the feedback current in the balancing transformer 10 Control device 20 for controlling supply of current to (N1);

The direction of the current flowing in the first winding N2 and the second winding N3 is in opposite directions, so that the magnetic fields generated in the first winding N2 and the second winding N3 are magnetically coupled to cancel each other,

The third winding N1 has a structure in which the first winding N2 and the second winding N3 are magnetically coupled, but in the same current direction as the first winding N2, the magnetic field generated in the third winding N1 and the second winding N1 It is characterized in that the magnetic field generated in the winding N2 is composed of a coupling structure that increases mutually.

As described above, according to the balancing transformer for reducing leakage current according to the present invention, even if the charging part is exposed and leakage current to the earth occurs, the load that must be operated can be normally operated. damage can be minimized,

Even if a person comes into contact with an exposed live part, it minimizes leakage through the human body, thereby reducing other damage from electric shock.

In addition, current balancing in the balancing transformer 10 is not achieved due to the difference in impedance on the path through which the leakage current flows in the surrounding environment at the time when the charging part is exposed and the leakage current occurs.

The present invention can respond to changes in impedance on the path through which the leakage current flows by actively balancing the current in the balancing transformer 10 in order to prevent the leakage current reduction function from being deteriorated by sensing the supply current and the feedback current,

If there is a change in the impedance on the path through which the leakage current flows, the number of turns of the third winding (N1), the first winding (N2), and the second winding (N3) is not changed, and it can be installed and used regardless of the installation location. It works.

Fig. 2 An example of an equivalent circuit for simulation of Fig. 1
Fig. 3 Equivalent circuit and load current when there is no balancing transformer (charged part not grounded)
In the equivalent circuit of FIG. 2, the magnitude of the current flowing through the Rbody when the control device of the balancing transformer does not operate
5. Comparison of current flowing in Rbody before and after the control device of the balancing transformer operates in the equivalent circuit of FIG.
6 is an embodiment in which the present invention is applied between a three-phase, four-wire load and a power source;
7 is a view related to an embodiment in which the present invention is applied between a three-phase three-wire load and a power source.

Hereinafter, specific contents for carrying out the present invention will be described with reference to the drawings.

In addition, in demonstrating this invention, the same part is attached|subjected by the same code|symbol, and the repetition description is abbreviate|omitted.

In addition, if the components constituting the invention are known in the art or commercialized components, the description thereof will be omitted.

First, the balancing transformer 100 for reducing leakage current according to the first embodiment of the present invention is in a state in which the charging part is exposed and submerged from the load 200 and the load 200, which are electrical author equipment or devices, and the human body is in contact. R1, R2, R3, Rbody will be described with reference to the state in which the simulated leakage load unit 300 is connected.

As shown in Fig. 1, the first junction point (1), which is one end of the first winding (N2) of the balancing transformer 10 constituting the balancing transformer 100 for reducing leakage current (hereinafter referred to as “connection point”, the terminal and It may be the same part, but it means the point where it is electrically connected. The same) is connected to the power source PS.

First, in a normal state (meaning the counterpart in which the charging part is submerged or does not leak through the human body, etc.)

The second junction point 2, which is the other end of the first winding N2, is connected to the load 200 through the load power supply point 5, so that the supply current IL connects the first winding N2 from the PS. A magnetic field is generated in proportion to the number of turns of the first winding N2 and the supply current IL.

The supply current IL supplied to the load 200 passes through the hatch return connection point 6 of the load 200 .

Power supply supplied to the second winding N3 through the second winding first connection point 4 of the second winding N3 and grounded through the second winding second connection point 3 which is the other end of the second winding N3. connected to Ns.

The second winding N3 is supplied to the second winding N3 through the hatch return connection point 6 of the load 200 and the second winding first connection point 4 of the second winding N3, which is the second end of the second winding N3. The current flowing through Ns of the grounded power source through the winding second connection point 3 is the feedback current IN and has the same magnitude as the supply current IL.

The first winding N2 and the second winding N3 are reactors having the same number of turns and the same impedance, and flowing currents are the same. However, the first winding N2 and the second winding N3 are magnetically coupled reactors so that the magnetic fields generated in each cancel each other out.

In addition, the control device 20 that functions as an AC-AC converter known in the art is a control device 20 that is operated by receiving power from a power source,

Calculates the difference between the supply current sensing unit 7 for sensing the size of the supply current IL and the feedback current sensing unit 8 for sensing the size of the feedback current,

Supply current to the third winding N3 magnetically coupled to the first winding N2 or the second winding N3 of the balancing transformer 10 so that the supply current and the return current are the same or as much as possible (hereinafter, the invention For convenience, it is referred to as “same”).

Therefore, in a normal state, the magnitude of the current detected by the supply current sensing unit 7 and the feedback current sensing unit 8 is the same, so that the control device 20 does not supply the current to the third winding N3 .

Specific operation of the control device in the present invention utilizes a technique known in the art, so the operation description is omitted.

Hereinafter, the present invention is used, that is, as shown in FIG. 1 , the load 200 is connected to the balancing transformer 100 for reducing leakage current, and the charging part is submerged in the same state as the above-described leakage load part 300 (hereinafter this It is referred to as “abnormal state”).

In the present invention, in order to facilitate understanding of the present invention, the leakage load unit 300 and the load 200 are simulated and specific values are limited, but this is only for convenience of explanation and it is revealed that the present invention is not limited in understanding. put

In the state of FIG. 1 , that is, in the abnormal state, the supply current IL is Rbody, R1, R2, R3, and the current flowing through the load 200 The sum flows, and the feedback current (IN) flows with a difference as much as the current flowing from IL to Rbody. In this case, if it is an ideal balancing transformer, the leakage current can be minimized by balancing the supply current and the feedback current due to sufficient magnetic field cancellation. However, if there is no balancing transformer (see FIG. 3, the balancing transformer 100 for reducing leakage current in FIG. 1 is removed and the power source Vin is the load power supply point 5 and hatch return connection point 6 of the load 300) When comparing the case where there is a balancing transformer but the control device 20 that applies a current to the third winding N1 does not operate (refer to FIG. 4),

It can be seen through the simulation results that a current with a slight difference in magnitude flows in the Rbody, and that the balancing action is not sufficient.

As shown in FIGS. 3 and 4 , the magnitude of the current flowing through the load 200 does not change significantly depending on the presence or absence of the balancing transformer 10 .

The following is a third winding ( Looking at the state of operation to be applied to N1),

It can be seen from FIG. 5 that the magnitude of the current flowing through the load 200 is the same, but the magnitude of the current flowing through the Rbody is significantly reduced.

At this time, the current supplied by the control device 20 to the third winding N1 is applied in the same direction as the first winding N2, and the magnetic fields generated in the first winding N2 and the third winding N1 are mutually Either magnetic field coupling is increased in an increasing direction, or the current supplied to the third winding N1 is applied in the same direction as the second winding N3, and is generated in the second winding N3 and the third winding N1. The magnetic fields may be magnetically coupled in mutually increasing directions.

The normal and abnormal states as described above and the control device 20 were operated to supply a current to the third winding N1 to compare the magnitude of the Rbody current, and the circuit used in the simulation for the comparison is shown in FIG. 1 2 is used as an equivalent circuit, where the number of turns of the first winding (N2), the second winding (N3), and the third winding (N1) of the balancing transformer is 100 turns, respectively, and the first winding (N2) The internal resistance Rs of , and the internal resistance Rt of the second winding N3 are each 0.1Ω, and the internal resistance Rp of the third winding N1 is also 0.1Ω.

In addition, the leakage inductance Ls of the first winding N2, the leakage inductance Lt of the second winding N3, and the leakage inductance Lp of the third winding N1 are 0.0001 [H], at this time the magnetizing inductance ( Lm) is 0.2 [H].

The simulation tool is PSIM 64-bit Version 9.0, AC220: peak voltage 311[V] (= RMS 220V), the size of the power supplied to the third winding from the control unit is 60Hz power source AC44: peak voltage 62.2[V] (= RMS 44V), 60Hz power source),

In addition, the load 200 has a reactance of 10 [mH] and a resistance of 100 Ω connected in series, and R1 constituting the leakage load unit 300 is 80 Ω, R2 is 20 Ω, R3 is 20 Ω, and Rbody is 500 Ω.

Balancing transformer and parameters are as follows in Table 1.

In addition, the capacity of each winding of the balancing transformer 10 shown in the present invention is suitable for an allowable capacity larger than the load current, and it is not limited to the parameters of the balancing transformer set for convenience of explanation of the present invention, the present invention is not limited to If the operating principle of the transformer for reducing leakage of the present invention is used suitable for the load capacity and the usage environment, it can be changed and implemented,

It will be apparent that such changes are also included in the scope of the present invention.

In addition, the present invention provides a balancing transformer for reducing leakage current between a load and a power source connected to a three-phase three-wire system and between a three-phase four-wire load and a power source as shown in FIGS. 6 and 7 according to the power distribution method in which the load is used. (100) can be placed and utilized.

Although the balancing transformer 100 for reducing leakage current is abbreviated in FIGS. 6 and 7 , it is the same as the balancing transformer 100 for reducing leakage current shown in FIG. 1 .

7: supply current sensing unit, 8: feedback current sensing unit,
10: balancing transformer, 20: control device,
100: balancing transformer for reducing leakage current,
200: load, 300: leakage load part,
N1: 3rd winding, N2: 1st winding N2 2nd winding

Claims (5)

The first winding N2 that generates a magnetic field by a current flowing in the same direction as the current direction IL flowing in the direction of the load 200 constituting the balancing transformer 10, the current direction IN flowing in the opposite direction to the load direction ), the second winding N3 that generates a magnetic field by the current flowing in the same direction,
Balancing transformer 100 for reducing leakage current, characterized in that the third winding (N1) for generating a magnetic field to compensate for the difference between the supply current and the feedback current is provided. The method according to claim 1,
The balancing transformer 100 for reducing the leakage current,
The supply current sensing unit 7 for detecting the size of the supply current, the feedback current sensing unit 8 for sensing the size of the feedback current, the current input from the supply current sensing unit 7 and the feedback current sensing unit 8 Balancing transformer 100 for reducing leakage current, characterized in that the control device 20 for controlling the magnitude of the magnetic field generated by the supply current and the feedback current in the balancing transformer 10 by calculating the magnitude is provided. 3. The method according to claim 2,
The control device 20
Balancing transformer (100) for reducing leakage current, characterized in that the control device (20) for controlling the supply of current to the third winding (N1) so that the magnitude of the magnetic field due to the supply current and the feedback current is the same. 4. The method according to claim 3,
The control device 20 is a balancing transformer 100 for reducing leakage current, characterized in that the control device controls to match the direction of the current supplied to the third winding (N1) and the direction of the current of the first winding (N2). 4. The method according to claim 3,
The control device 20 is a balancing transformer 100 for reducing leakage current, characterized in that the control device controls to match the direction of the current supplied to the third winding (N1) and the direction of the current of the second winding (N2).

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