JP6552841B2 - Induction heating roller system - Google Patents

Description

  The present invention relates to an induction heating roller system using two sets of induction heating roller devices.

  The induction coil of the induction heating roller device supplies a single-phase alternating current because it causes a decrease in power factor and nonuniform heat generation distribution when magnetic fluxes having different phases are mixed in the same magnetic circuit. Is desirable.

  However, since a power source of the induction heating roller device is generally a three-phase AC power supply, usually, a single-phase AC is often extracted from the three-phase AC.

  Here, if the induction coils of two sets of induction heating roller devices of the same specification are directly connected to the U-V terminal and the V-W terminal, the balance of U-phase, V-phase and W-phase phase currents is 1: √ 3: 1 and an unbalance of 1.732 times occurs. This is the definition of the low-voltage and high-voltage power supply extension (JEAC) restrictions on unbalanced loads and “basic equipment unbalance rate of 30% or less calculated from single-phase connection load” in special machinery and equipment. Violated.

  In order to prevent this, as shown in Patent Document 1, there is a method of providing a Scott connection transformer between a three-phase AC power supply and an induction coil and taking out two circuits of a single-phase AC output from the three-phase AC.

  However, a Scott connection transformer is required, and there are great demerits from the viewpoint of cost and space.

JP, 2001-297867, A

  Therefore, the present invention has been made to solve the above problems, and in the case of operating two induction heating roller devices with a three-phase AC power source, it is possible to unbalance phase current without using a Scott connection transformer. Reduction is the main issue.

  That is, the induction heating roller system according to the present invention comprises: a first induction heating roller device provided with a first induction heating mechanism having a first induction coil inside a rotatably supported first roller main body; A second induction heating mechanism provided with a second induction coil inside a rotatably supported second roller main body having a magnetic circuit different from the first induction heating roller device. An induction heating roller system which operates an induction heating roller device with a three-phase AC power supply, wherein the number of turns of at least the second induction coil is even, and the winding start end and the winding end of the first induction coil One end of the end portion is electrically connected to one phase of the three-phase AC power supply, and the other end is electrically connected to the middle point portion of the second induction coil, and winding of the second induction coil is performed. Beginning end and winding End end is characterized by being electrically connected to the remaining two phases of the three-phase AC power supply.

  In such a case, since the first induction coil and the second induction coil, which are induction coils of the two induction heating roller devices, are connected by Scott connection, the phase current is not used without using a Scott connection transformer. Can be reduced. Details will be described later.

It is preferable that the number of turns of each of the induction coils is even, and a connection terminal is provided at a midpoint of each of the induction coils.
With this configuration, the configurations of the first induction coil and the second induction coil can be made the same to be compatible.

The first induction heating roller device and the second induction heating roller device have the same specifications electrically, and the number of induction coil layers having an even number of turns is an even number, and the winding start end portion, the winding Desirably, the end and the midpoint are located at the axial end of the induction coil.
In this configuration, the current of the first induction coil flows from the middle point of the second induction coil into the winding start end and the winding end end in half. Since the current flowing to the winding start end of the second induction coil and the current flowing to the winding end end of the second induction coil have opposite directions, the generated magnetic flux is canceled and disappears.
Here, when at least the number of layers of the second induction coil is an even number and the winding start end, winding end and middle point are positioned at the axial end of the induction coil, the winding start end from the middle point The magnetic coupling between the winding portion up to the portion and the winding portion from the middle point to the winding end is good, and the magnetic flux can be efficiently dissipated.

Preferably, a voltage control device for controlling the voltage applied to each of the induction coils is provided between one end of each of the induction coils and the three-phase alternating current power supply.
With this configuration, individual output control of the first induction heating roller device and the second induction heating roller device is possible.

  Even if the current flowing through the second induction coil is adjusted to zero by the voltage control device provided on one end side of the second induction coil, the first induction coil is connected to the other end side of the second induction coil. Since the flowing current flows, the output of the second induction heating roller device can not be made zero. Therefore, by making the load capacity of the second induction heating roller device larger than the load capacity of the first induction heating roller device, the above phenomenon does not occur, and the first induction heating roller Good individual control of the apparatus and the second induction heat roller apparatus becomes possible.

The voltage control device such that the maximum applied voltage of the second induction coil is 2 / (2√3-1) times the power supply voltage obtained by subtracting the voltage drop of the voltage control device at maximum output. Is desirable to be adjusted.
With this configuration, the phase current imbalance can be further reduced. Details will be described later.

The number of turns of each induction coil is 2N (N is a natural number), and an additional winding of (2 / √3-1) N turns is provided at each of the winding start end and winding end of each induction coil. One of the winding start end and the winding end end of the first induction coil is connected to the middle point of the second induction coil, and the other is connected to one phase of the three-phase AC power source. The additional windings connected to both ends of the second induction coil are connected to the remaining two phases of the three-phase AC power source, so that both ends of the second induction coil are It is desirable to be electrically connected to the remaining two phases of the phase AC power source.
With this configuration, the phase current can be made the same, and unbalance can be eliminated. Details will be described later.

The number of turns of the second induction coil is preferably 2N (N is a natural number), and the number of turns of the first induction coil is preferably で あ る 3N.
With this configuration, when two induction heating roller devices of the same specification are electrically operated, the phase current can be made the same without the need for a tap, and the imbalance can be eliminated. .

  The three-phase AC power source is used as industrial equipment, and the object (roller body) to be induction-heated is basically made of thick metal because it is an industrial equipment. For this reason, by setting the power supply frequency of the three-phase AC power supply to a commercial frequency of 50 Hz or 60 Hz, it is possible to increase the current permeability in the induction heating of thick metal, and efficiently heat the object. it can.

  According to the present invention thus configured, since the induction coils of the two induction heating roller devices are connected by Scott connection, it is possible to reduce the unbalance of the phase current without using a Scott connection transformer.

The figure which shows typically the structure of the induction heating roller system which concerns on 1st Embodiment. The vector diagram in one use example of the embodiment. The figure which shows typically the structure of the induction heating roller system which concerns on 2nd Embodiment. Vector diagram of the second embodiment. The figure which shows typically the structure of the induction heating roller system which concerns on deformation | transformation embodiment. The vector diagram of a modified embodiment.

First Embodiment
A first embodiment of an induction heating roller system according to the present invention will be described below with reference to the drawings.

  The induction heating roller system 100 according to the first embodiment operates two sets of induction heating roller devices 2 and 3 by a single three-phase AC power source 4, and includes a first induction coil 21. An induction heating roller device 2 and a second induction heating roller device 3 provided with a second induction coil 31 are provided. The first induction heating roller device 2 and the second induction heating roller device 3 have independent magnetic circuits different from each other, and the first induction heating roller device 2 is rotatably supported at its first position. The first induction heating mechanism having the first induction coil 21 is provided inside the roller body 20 of the second embodiment, and the second induction heating roller device 3 is a second roller body 30 rotatably supported. A second induction heating mechanism having a second induction coil 31 is provided therein.

  The induction heating roller devices 2 and 3 are configured to have the same specifications electrically, and the induction coils 21 and 31 are wound around the iron cores 22 and 32 to form an induction heating mechanism. doing. The power supply frequency of the three-phase AC power supply is a commercial frequency of 50 Hz or 60 Hz. As a result, it is possible to increase the current permeability in induction heating of the thick roller metal body, and it is possible to efficiently heat the roller body.

  The first induction heating roller device 2 and the second induction heating roller device 3 and the three-phase AC power supply 4 are in Scott connection. Specifically, the winding start end portion 21x of the first induction coil 21 is electrically connected to the U phase of the three-phase AC power supply 4, and the winding end end portion 22y of the first induction coil 21 is the second induction. It is electrically connected to the midpoint 31z of the coil 31. Further, the winding start end portion 31 x of the second induction coil 31 is electrically connected to the V phase of the three-phase AC power source 4, and the winding end portion 31 y of the second induction coil 31 is W of the three-phase AC power source 4. It is electrically connected to the phase.

  In the present embodiment, connection terminals are provided at both end portions 21x, 21y, 31x, 31y of the induction coils 21, 31, and connection terminals are provided at midpoint portions 21z, 31z of the induction coils 21, 31. . In addition, although the connection terminal provided in the midpoint part 21z of the 1st induction coil 21 is not used in this embodiment, it is provided in order to make the two induction coils 21 and 31 into the same specification and to have compatibility. There is.

  The induction coils 21 and 31 have the same number of turns and an even number {2N (N is a natural number)}. That is, the number of turns from the midpoints 21z and 31z of the induction coils 21 and 31 to the winding start ends 21x and 31x is N, and the number of turns from the midpoints 21z and 31z to the winding end ends 21y and 31y. Is also N.

  In this embodiment, the number of layers of each induction coil having an even number of turns is an even number. Specifically, in FIG. 1, the induction coils 21 and 31 are configured to have two layers. Thereby, in each induction coil 21, 31, the winding start end portions 21x, 31x and the winding end ends 21y, 31y are located on one end side in the axial direction of the induction coils 21, 31, and the midpoint portions 21z, 31z are the induction coils. It becomes a structure located in the axial direction other end side of 21, 31.

  Furthermore, voltage control devices 51, 52 for controlling the voltage applied to each induction coil 21, 31 are provided between one end of each induction coil 21, 31 and the three-phase AC power supply 4. In the present embodiment, the first voltage control device 51 is provided between the winding start end 21 x of the first induction coil 21 and the three-phase AC power supply 4 (U phase), and the second induction coil 31 A second voltage control device 52 is provided between the winding start end portion 31x and the three-phase AC power supply 4 (V phase). The voltage control devices 51 and 52 are semiconductor control elements such as thyristors, for example. The voltage control devices 51 and 52 are controlled by a control unit (not shown).

Next, the current flowing through each phase of the induction heating roller system 100 configured as described above will be described with reference to FIG.
In the following, the power supply voltage of the three-phase AC power source 4 E, the inter-terminal voltage minus the voltage drop e of control devices 51 and 52, the terminals of the first induction coil 21 _U-O a -O _b, the The capacitance of the first induction coil 21 is P _a , the current of the first induction coil 21 is I _a , the terminal of the second induction coil 31 is V-O _b '-W, and the capacitance of the second induction coil 31 is P _b, and the current of the second induction coil 31 and _{i b.} The following calculations are all absolute value calculations.

When a terminal _{U-O b} voltage of the first induction coil 21 and _{e a,} a _{e a} = _√3e / 2.
The capacity P _a of the first induction coil 21 is P _a = i _a √3e / 2.
The current i _a of the first induction coil 21 is i _a = 2P _a / e√3.

Here, since the voltage between the terminals V and W of the second induction coil 31 is e, assuming that the current with respect to the vector e is i _b ′, the number of turns is the same 2N as the first induction coil 21 and the coil impedance is the same. Therefore, the voltage between the terminals V and W is 2 / √3 times that of the first induction coil 21 and the current is also 2 / √3 times.
Therefore, i _b ′ = 2i _a / √3,
The capacitance P _b of the second induction coil 31 is P _b = 2i _a e / √3.

The capacity ratio between the first induction coil 21 and the second induction coil 31 is:
P _b / P _a = (2i _a e / √3) / (i _a √3e / 2)
= 4/3

The current i _b of the second induction coil is
i _b = √ {(i _b ′) ² + (i _a / 2) ² }
= I _a √ (4/3 + 1/4)
= I _a √ (19/12)

  Therefore, the current ratio of each phase current is 1: 1.258: 1.258, and the unbalance is reduced to 1.258 times.

The current _{i a} of the first induction coil 21 is entered from the terminal _{O b} midpoint portion 31z of the second induction coil 31, flows divided to the terminal V and terminal W by _i a / 2. At this time, since the directions of the current flowing to the terminal V and the current flowing to the terminal W are opposite to each other, the generated magnetic flux is canceled and disappears.

Here, the second induction coil 31 is an even-numbered layer (two layers), and the winding start end portion 31x, the winding end end portion 31y, and the middle point portion 31z are positioned at the axial end portion of the second induction coil 31. Therefore, the magnetic flux generated by the current flowing through the coil portion between the terminals O _b ′ -V and the magnetic flux generated by the current flowing through the coil portion between the terminals O _b ′ -W are well coupled, and the magnetic flux is effectively eliminated. be able to.

Also, as described above, most of the magnetic flux generated by the second induction coil 31 is canceled and disappears, so the heat generation power of the second induction coil 31 is only that by i _b '. Therefore, power control of the second induction heating roller device 3 can be performed only by the second control device 52.

However, since a part of the magnetic flux remains depending on the coupling state between the coil portion between the terminals V-O _b ′ and the coil portion between the terminals O _b ′ -W, the heat generated by the magnetic flux is affected. However, the induction heating roller device 3 basically controls the load temperature, and since the total power including the influence of the residual magnetic flux is controlled, the induction heating temperature can be controlled without any problem.

Furthermore, even if the current i _b ′ by the vector e is adjusted to zero using the second voltage control device 52, the current i _a flows to the terminal side (W phase) to which the second voltage control device 52 is not connected The output of the second induction heat roller device 3 cannot be adjusted to zero. Therefore, if the second induction heating roller device 3 is disposed on the side with a large load capacity, the output of the second induction heating roller device 3 is zeroed in a state where the current i _{a of} the first induction heating roller device 2 flows. Therefore, good individual control of the first induction heating roller device 2 and the second induction heating roller device 3 is possible.

Next, e is the power supply voltage obtained by subtracting the voltage drop of the voltage control device at the maximum output, and the maximum applied voltage applied between the terminals V-W of the second induction coil 31 by the second voltage control device 52. Let e be _b .

_Here, if _{e a = e / √3 + e} c, a _{e c = e a -e / √3} .
Further, since e _c = e _b / 2√3, e _b / 2√3 = e _a −e / √3.
Therefore, e _b = 2 / √3 (e _a −e / √3) = 2 / √3 e _a −2e.

Here, when the condition that e _a = e _b is calculated,
e _b = 2 / √3e _b -2e
(2√3-1) e _b = 2 e
e _b = 2e / (2√3-1).

That is, if e _b = 2e / (2√3-1), the maximum applied voltage e _a applied to the first induction coil 21 is also the same e _a = 2e / (2√3-1) .
The maximum capacity is also the same, and P _a = P _b = 2ei _a / (2√3-1).
Current i _a = (2√3-1) P _a / 2e
Current i _b = √ {i _a ² + (i _a / 2) ² }
= I _a 5 5/2
= 1.118i _a

Therefore, the current ratio of each phase current is 1: 1.118: 1.118, and the unbalance is reduced to 1.118 times. That is, the maximum applied voltage e _b of the second induction coil 31 is 2 / (2√3-1) times the power supply voltage e obtained by subtracting the voltage drop of the voltage control device 52 at the maximum output time. By adjusting to, the phase current imbalance can be further reduced.

Incidentally, by substituting the i _a in the above equation for i _b, it becomes the seek ib and below.
I _b = i _a 5 5/2
= √5 (2√3-1) P _a / (2 × 2e)
= (2 / √15−√5) P _a / 4e

<Effect of First Embodiment>
According to the induction heating roller system 100 configured as described above, in the case of supplying electric power to the first induction coil 21 and the second induction coil 31 by the single single-phase AC power supply 4, the first induction heating roller Since the induction coil 21 of the device 2 and the induction coil 31 of the second induction heating roller device 3 are connected by Scott connection, it is possible to reduce the unbalance of the phase current without using a Scott connection transformer.

Second Embodiment
Next, a second embodiment of the induction heating roller system according to the present invention will be described with reference to the drawings.

  The induction heating roller system 100 according to the second embodiment differs from the first embodiment in the coil configuration and the aspect of Scott connection.

  The number of turns of the first induction coil 21 and the second induction coil 31 of this embodiment is 2N (N is a natural number), and the winding start end portions 21x and 31x and the winding end end portion 21y of each induction coil 21 and 31. , 31y are connected to additional windings 23, 33 having a winding number (2 / √3-1) N. The total number of turns of the first induction coil 21 and the additional winding 23 and the total number of turns of the second induction coil 31 and the additional winding 33 are both 2N + 2 × (2 / √3-1) N = N ( 2 + 4 / 43-2) = 4 N / √3.

  Then, the winding start end portion 21x of the first induction coil 21 is electrically connected to the U phase of the three-phase AC power supply 4, and the winding end portion 22y of the first induction coil 21 is in the second induction coil 31. The point portion 31z is electrically connected. Further, the additional winding 33 connected to the winding start end portion 31x of the second induction coil 31 is electrically connected to the U phase of the three-phase AC power source 4, and the winding end end portion of the second induction coil 31 is connected. An additional winding 33 connected to 31y is electrically connected to the W phase of the three-phase AC power supply 4.

Next, the current flowing through each phase of the induction heating roller system 100 configured as described above will be described with reference to FIGS.
Each voltage, current and capacity are as follows.
e _a = e√3 / 2
i _a = P _a / (e√3 / 2)
P _a = i _a e√3 / 2
e _b = e
i _b '= P _b / e
Here, if P _a = P _b , then
i _b '= i _a 3 3/2
i _b = √ {(i _a √3 / 2) ² + (i _a / 2) ² }
= I _a
Accordingly, the first induction coil 21 and the second induction coil 31 is the same volume, balance becomes all the phase currents are i _a.

<Effect of Second Embodiment>
According to the induction heating roller system 100 configured in this way, by adding the additional windings 23 and 33 to the induction coils 21 and 31 of the embodiment and performing Scott connection, two induction heatings of the same specification are electrically conducted. When the roller devices 2 and 3 are operated, the phase current can be equalized without the need for a tap, and the imbalance can be eliminated.

<Modified embodiment of the present invention>
The present invention is not limited to the above embodiments.
Regarding the configuration of the induction coil, the configurations of the first induction coil 21 and the second induction coil 31 may be different.
Specifically, in the first embodiment, the connection terminal may not be provided at the midpoint portion 21z of the first induction coil 21, and the number of turns of the first induction coil 21 may not be an even number. good.
In the second embodiment, the additional winding 23 may not be connected to the winding start end 21x and the winding end 21y of the first induction coil 21.

  Furthermore, as shown in FIGS. 5 and 6, the number of turns of the second induction coil 31 may be 2N (N is a natural number), and the number of turns of the first induction coil 21 may be √3N. In this case, electrically, it becomes the same as the second embodiment, and when operating two induction heating roller devices 2 and 3 of the same specification electrically, the phase current is identical without the need for a tap. And unbalance can be eliminated.

  In addition, it goes without saying that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

100 ··· Induction heating roller system 2 ··· First induction heating roller device 21 ··· First induction coil 21 x ··· First end of winding end of first induction coil 21 y ··· First induction End of winding end of coil 3 ··· Second induction heating roller device 31 ··· Second induction coil 31 x ··· Starting end of second induction coil 31 y ··· Second induction coil End of winding end 31z ··· Mid point of second induction coil 4 · · · Three-phase AC power supply 51 · · · First voltage control device 52 · · · Second voltage control device

Claims (11)

A first induction heating roller device provided with a first induction heating mechanism having a first induction coil inside a rotatably supported first roller main body, and different from the first induction heating roller device A second induction heating roller device provided with a second induction heating mechanism having a second induction coil inside a rotatably supported second roller body having a magnetic circuit and a three-phase AC power supply An induction heating roller system that operates
At least the number of turns of the second induction coil is an even number;
One of the winding start end and winding end of the first induction coil is electrically connected to one phase of the three-phase AC power supply, and the other is electrically connected to the midpoint of the second induction coil. As well as being connected to
The winding start end and the winding end of the second induction coil are electrically connected to the remaining two phases of the three-phase AC power supply,
The number of layers of the induction coil with an even number of turns is an even number,
An induction heating roller system in which the winding start end, the winding end and the midpoint are located at axial ends of the induction coil. The number of turns of each induction coil is an even number;
The induction heating roller system according to claim 1, wherein a connection terminal is provided at a midpoint of each of the induction coils.   The induction heat roller system according to claim 1 or 2, wherein a load capacity of the second induction heat roller device is larger than a load capacity of the first induction heat roller device.   The voltage control apparatus which controls the applied voltage of each said induction coil is provided between the one end side of each said induction coil, and said three-phase alternating current power supply, The induction as described in any one of the Claims 1 thru | or 3 Heating roller system.   The voltage control device so that the maximum applied voltage of the second induction coil is 2 / (2√3-1) times the power supply voltage obtained by subtracting the voltage drop of the voltage control device at the maximum output. The induction heating roller system according to claim 4, wherein is adjusted. The number of turns of each induction coil is 2N (N is a natural number),
An additional winding having a number of turns of (2 // 3-1) N is connected to each of the winding start end and the winding end of each of the induction coils,
One of the winding start end and the winding end end of the first induction coil is connected to the middle point of the second induction coil, and the other is connected to one phase of the three-phase AC power source,
By connecting additional windings connected to both ends of the second induction coil to the remaining two phases of the three-phase AC power supply, both ends of the second induction coil are the rest of the three-phase AC power supply. The induction heating roller system according to any one of claims 1 to 5, wherein the induction heating roller system is electrically connected to two phases. A first induction heating roller device provided with a first induction heating mechanism having a first induction coil inside a rotatably supported first roller main body, and different from the first induction heating roller device A second induction heating roller device provided with a second induction heating mechanism having a second induction coil inside a rotatably supported second roller body having a magnetic circuit and a three-phase AC power supply An induction heating roller system that operates
At least the number of turns of the second induction coil is an even number;
One of the winding start end and winding end of the first induction coil is electrically connected to one phase of the three-phase AC power supply, and the other is electrically connected to the midpoint of the second induction coil. As well as being connected to
The winding start end and the winding end of the second induction coil are electrically connected to the remaining two phases of the three-phase AC power supply,
The number of turns of the second induction coil is 2N (N is a natural number);
Induction heating roller system the number of turns of the first induction coil Ru √3N der. The number of layers of the induction coil with an even number of turns is an even number,
The induction heating roller system according to claim 7, wherein the winding start end, the winding end and the middle point are located at axial ends of the induction coil.   The induction heat roller system according to claim 7 or 8, wherein a load capacity of the second induction heat roller device is larger than a load capacity of the first induction heat roller device.   10. The induction according to any one of claims 7 to 9, wherein a voltage control device for controlling a voltage applied to each induction coil is provided between one end side of each induction coil and the three-phase alternating current power supply. Heating roller system.   The induction heating roller system according to any one of claims 1 to 10, wherein a power supply frequency of the three-phase alternating current power supply is 50 Hz or 60 Hz.