Method for manufacturing a high-frequency excitation heating device and an iron core for stationary equipment.

Abstract

This invention provides a high-frequency excitation heating device and a method for manufacturing iron cores for stationary equipment that are suitable for the practical application of annealing by high-frequency excitation. [Solution] A high-frequency excitation heating device comprising a first core support member disposed on the inside of the core, a second core support member disposed on the outside of the core, and a fastening member that fastens the first and second core support members together while insulating them, wherein the first and second core support members are non-annular, and a high-frequency induction coil disposed around the first and second core support members and the core, a power supply that supplies AC power, a function generator that generates AC, and a program regulator that generates control signals to command the function generator, a temperature sensor in either the first or second core support member, the measured value of the temperature sensor being input to the program regulator, and the program regulator providing feedback control of the AC power according to the measured value of the temperature sensor.

Description

Technical Field

[0001] The present invention relates to a high-frequency induction heating device and a method for manufacturing a core for stationary equipment.

Background Art

[0002] Static equipment using an amorphous core with excellent conversion efficiency and environmental friendliness, such as an amorphous transformer, has been spreading in recent years. An amorphous core is composed of a laminate of amorphous ribbons (for example, with a thickness of around 0.025 mm) because the loss of amorphous ribbons is 1 / 3 to 1 / 4 lower than that of silicon steel sheets.

[0003] An amorphous core is formed, for example, by bundling and cutting a plurality of roll-shaped amorphous alloy ribbons wound around a hoop, laminating the cut amorphous alloy ribbons in a U-shape on a rectangular core bar, and lap-joining the ends. Then, strain due to bending or cutting is removed, and a direct current magnetic field is applied in the longitudinal direction of the core, followed by heat treatment at 300 to 400 °C. This is because the orientation of the magnetic moments is aligned and the axis is fixed by annealing in a magnetic field, thereby improving the magnetic properties.

[0004] Currently, the annealing treatment of amorphous cores indirectly heats the cores with warm air using an electric furnace. The furnace atmosphere is filled with an inert gas to prevent oxidation of the cores, and heat is transferred with the inert gas. As an example of the furnace structure, it consists of a heater section, a circulation fan section, and a cooling section, which are installed inside the furnace, and the gas whose temperature is adjusted in the heater section and the cooling section circulates inside the furnace by the circulation fan.

[0005] Such a method of indirectly heating the core with warm air using an electric furnace requires a lot of time to reach predetermined heat treatment conditions, and it is required to reduce this energy loss in order to meet the recent demand for power consumption reduction. Patent Document 1 discloses annealing of an amorphous core using a jig for annealing and performing annealing by induction heating. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-217775 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Compared to atmospheric heating, annealing by high-frequency excitation disclosed in Patent Document 1 is a promising technology because it can reduce the amount of power consumed during annealing and shorten the time required for annealing. However, despite being a theoretically promising technology, it has long been unsuccessful in practical application.

[0008] Annealing by high-frequency excitation utilizes the heat generated by losses. Magnetic materials lose their spontaneous magnetization above the Curie temperature. Furthermore, if excitation exceeds the Curie temperature, excitation occurs in the saturation region, leading to the problem of overcurrent making excitation impossible.

[0009] Therefore, the present invention aims to provide a high-frequency excitation heating device and a method for manufacturing an iron core for stationary equipment that are suitable for the practical application of annealing by high-frequency excitation. [Means for solving the problem]

[0010] A high-frequency excitation heating device comprising: a first core support member disposed on the inside of the core; a second core support member disposed on the outside of the core; and a fastening member that fastens the first core support member and the second core support member together while insulating them, wherein the first core support member and the second core support member are non-annular; and a high-frequency induction coil disposed around the first core support member, the second core support member and the core; a power supply that supplies AC power to the high-frequency induction coil; a function generator that generates AC; and a program regulator that generates control signals to command the function generator; wherein either the first core support member or the second core support member has a temperature sensor; the measured value of the temperature sensor is input to the program regulator; and the program regulator provides feedback control of the AC power according to the measured value of the temperature sensor. [Effects of the Invention]

[0011] The present invention provides a high-frequency excitation heating device and a method for manufacturing an iron core for stationary equipment that are suitable for achieving appropriate control of high-frequency excitation and for the practical application of annealing by high-frequency excitation.

[0012] Further means and effects of the present invention will become apparent throughout the entire specification below. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram illustrating one embodiment of the present invention. [Figure 2] This is a control flowchart diagram of one embodiment of the present invention. [Figure 3] This is an explanatory diagram of the control in one embodiment of the present invention. [Figure 4] This is a diagram illustrating another embodiment of the present invention. [Figure 5] This is an explanatory diagram of additional control in another embodiment of the present invention. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the present invention will be described with reference to the drawings as necessary.

Embodiment

[0015] FIG. 1 is a diagram showing a configuration for annealing an amorphous core as an example of a core for stationary equipment.

[0016] The amorphous core 1a is sandwiched between a core support member 2a inside the core and a core support member 2b outside the core.

[0017] The core support member 2a inside the core has a discontinuous region in part and is not formed into a loop. In the figure, it has a C-shaped form. It can also be said to have a non-annular shape.

[0018] The core support member 2b outside the core is composed of a plurality of separated members and is not formed into a loop. In the figure, it is composed of three flat plates.

[0019] The core support member 2a inside the core and the core support member 2b outside the core are fastened by bolts 3. The core support member 2b outside the core has a hole larger than the diameter of the bolt 3, and by interposing an insulating washer between the bolt 3 and the core support member 2b outside the core, conduction between the core support member 2a inside the core and the core support member 2b outside the core is avoided. Alternatively, conduction is avoided by making the bolt 3 itself an insulating member. Thereby, a configuration is provided in which a loop surrounding the amorphous core 1a, the core support member 2a inside the core, and the core support member 2b outside the core with metal is not formed, and a configuration for preventing a circulating current is achieved.

[0020] A high-frequency excitation winding 4 for exciting the core at a high frequency is arranged to go around the amorphous core 1a, the core support member 2a inside the core, and the core support member 2b outside the core.

[0021] A temperature sensor 5a is attached to the core support member 2a inside the core. One example is a thermocouple, but other sensors may also be used. In Figure 1, as an example, the temperature sensor 5a is attached near the lap joint 1b of the core. This is because the temperature rise is higher in this area during high-frequency excitation due to the connection resistance at the lap joint.

[0022] The information obtained from the temperature sensor 5a is input to the program controller 6 for feedback control. The program controller 6 controls the function generator 7, which gives commands to the power supply regarding the excitation voltage, and controls the power applied from the power supply 8 to the high-frequency excitation winding 4.

[0023] The temperature sensor 5a is not particularly limited in shape, but it may be attached to the surface of the core support member 2a inside the core as a thin film sensor. Alternatively, a recess may be provided in advance on the surface of the core support member 2a inside the core, and the sensor may be fitted into the recess.

[0024] Furthermore, the instructions from the program controller 6 to the function generator 7 include those for excitation voltage, excitation current, and excitation frequency. Therefore, they can also be called commands related to high-frequency power or power commands. In addition, the above-mentioned commands related to excitation voltage also include cases where the commanded object is excitation voltage, excitation current, excitation frequency, or a combination thereof.

[0025] Annealing by high-frequency excitation utilizes the heat generated by losses. Since the spontaneous magnetization of magnetic materials like amorphous iron cores disappears above the Curie temperature, high-frequency excitation requires controlling the core temperature and performing excitation under temperature control. Exciting above the Curie temperature results in excitation in the saturation region, leading to overcurrent and making excitation impossible.

[0026] Therefore, when applying the method described in Patent Document 1 as is, it is necessary to perform excitation in a way that ensures the temperature does not exceed the Curie temperature, resulting in a lower temperature and a longer time required to complete the annealing process. Furthermore, there is an inherent possibility of incomplete annealing occurring.

[0027] In this embodiment, the temperature is measured by the temperature sensor 5a, and based on this information, the program controller 6 provides feedback control, for example, of the excitation voltage, to prevent overheating and thus prevent excitation failure. At the same time, by controlling the excitation current to raise the temperature as much as possible without exceeding the Curie temperature, it is possible to shorten the time until the annealing process is completed. This makes it possible to provide a high-frequency excitation heating device and a method for manufacturing iron cores for stationary equipment that are suitable for the practical application of annealing by high-frequency excitation.

[0028] Figure 2 is a control flowchart. Control starts in S01. In S02, the voltage is controlled based on the temperature data obtained from the temperature sensor 5a to reach the target temperature (a) at a constant heating rate (v). This also includes cases where the controlled object is current or frequency.

[0029] In S03, it is determined whether the core temperature exceeds the specified temperature (b), which is calculated with a likelihood from the upper limit. If it does, in S04 the set voltage is lowered to prevent overheating. If it is below the specified temperature (b), the set voltage is maintained in S05. Next, in S06, it is determined whether it is above the target temperature (a) required for annealing. If it is below the target temperature, the process returns to before S03 and the cycle described above is repeated. If it is above the target temperature (a), in S07 the time elapsed since the specified temperature was reached is counted, and if the specified time is exceeded, the output voltage is turned OFF in S08 and the annealing process ends in S09.

[0030] Figure 3 is an explanatory diagram and profile of the feedback control. The annealing process starts at time T0. Heating begins at the heating rate (v) to the target temperature (a). After reaching the target temperature (a) at time T1, the time count starts. When the specified temperature (b) is reached at time T2, the program controller 6 lowers the set voltage to prevent it from exceeding that temperature. Alternatively, the set voltage is controlled. After the specified time has elapsed at or above the target temperature (a) and time T3 is reached, the power is turned off, and the temperature returns to room temperature at time T4.

[0031] The core support member 2a on the inside of the core and the core support member 2b on the outside of the core also contribute to uniformizing the temperature of the core. Furthermore, they have a non-annular shape. Moreover, in this embodiment, annealing is performed by feedback control under controlled temperature conditions.

[0032] By applying this configuration to annealing, it becomes possible to maintain the iron core, allow it to move during the work process, and continuously supply a predetermined magnetic flux density to the iron core when a high-frequency voltage is applied, thereby enabling it to be heated to a predetermined temperature.

[0033] Furthermore, when an iron core is annealed by induction heating under a high-frequency voltage, the magnetic flux density tends to increase on the inner circumference side with a shorter magnetic path length, while it tends to decrease on the outer circumference side with a longer magnetic path length. This creates a gradient in the iron loss value between the inner and outer circumference, which is characteristic of annealing performed with high-frequency excitation.

[0034] Furthermore, in wound cores such as amorphous iron cores, there are overlapping sections, and a characteristic feature is that magnetic flux links between the thin bands of these overlapping sections. Therefore, when high-frequency heating is applied, the inner circumference of the overlapping section generates the most heat and becomes the hottest part. The temperature sensor 5a is attached to the inner circumference of the overlapping section in order to evaluate the maximum temperature.

[0035] Furthermore, the presence of areas where the core support members are not in contact with the core creates a localized temperature distribution, causing the iron loss value to change only in the areas excluding the annular inner circumference. Therefore, in a core subjected to high-frequency excitation using the inner core support member 2a and outer core support member 2b as shown in Figure 1, in addition to the inclination between the inner and outer circumferences, localized iron loss changes occur. The transformer in this case will have a wound core in which the magnetic properties of the inner circumference of the wound core are lower in one or more areas in the circumferential direction. [Examples]

[0036] Figure 4 is a configuration diagram of this embodiment, corresponding to Figure 1. Compared to the configuration of Embodiment 1, the number of sensor installation locations has been increased. This makes it possible to control the system to prevent equipment damage due to overheating, for example. Of course, it may also be used to improve the accuracy of the control in Embodiment 1.

[0037] The temperature sensor, for example, has multiple sensors numbered 5a to 5h, and is attached to both the core support member 2a on the inside of the core and the core support member 2b on the outside of the core. Of course, this does not rule out the possibility of installing it on only one of the core support members, but it is more desirable to distribute it on both.

[0038] Temperature values ​​and data from each temperature sensor are input to the program controller 6. The dashed line in the figure represents the input of data from temperature sensors other than 5a.

[0039] Figure 5 is an explanatory diagram of the additional feedback control in this embodiment. The control shown in Figure 5 is executed simultaneously with the feedback control in Figure 2.

[0040] The core support member is normally maintained at a constant clamping pressure, and when high-frequency excitation is performed, the inner circumference of the lapped section reaches the highest temperature. However, if there are deficiencies in the clamping pressure control during manufacturing, parts other than the inner circumference of the lapped section may overheat. Therefore, temperature sensors are installed at the inner and outer circumference of the core, and if the temperature sensor on the inner circumference of the lapped section (5a) shows a lower temperature than the temperature sensors installed at other locations (5b~5h), and other parts show a rapid temperature increase, this is considered an abnormality and the power is turned off.

[0041] The additional feedback control shown in Figure 5 starts in S11. In S12, temperature data from temperature sensors 5a to 5h is acquired. In S13, it is determined whether the temperature of temperature sensor 5a is higher than that of the other temperature sensors. If YES, feedback control continues in S14 and returns to the point before S13. If NO, an abnormality is detected, the output voltage is turned OFF in S15, and the process terminates in S16.

[0042] This makes it possible to prevent damage to high-frequency excitation heating devices due to abnormal overheating. It also enables early detection of fastening errors during manufacturing, allowing for feedback to workers and revision of work procedures. Furthermore, it can prevent annealing defects when manufacturing iron cores for stationary equipment.

[0043] Within the scope of the technical concept described above, various modifications are also within the scope of this disclosure. For example, this includes applications not only to amorphous cores but also to wound cores that require annealing. Furthermore, although the above description focuses on controlling the core temperature, other examples include observing and controlling, for example, the magnetic flux or excitation current at various parts of the core.

[0044] Therefore, as long as the ideas and concepts disclosed above are used, their modifications and similar examples are also included within the scope of the present invention.

[0045] Furthermore, an example of the present invention described using the above embodiments can also be expressed as follows.

[0046] <Part 1> It comprises a first core support member positioned on the inside of the core, a second core support member positioned on the outside of the core, and a fastening member that fastens the first core support member and the second core support member together while insulating them from each other. The first core support member and the second core support member are non-annular, The device comprises the first core support member, the second core support member, and a high-frequency induction coil arranged around the core. The system comprises a power supply that supplies AC power to the high-frequency induction coil, a function generator that generates AC power, and a program regulator that generates control signals to command the function generator. A high-frequency excitation heating device having a temperature sensor in either the first core support member or the second core support member, wherein the measured value of the temperature sensor is input to the program controller, and the program controller provides feedback control of the AC power according to the measured value of the temperature sensor. <Part 2> The high-frequency excitation heating device described in <Part 1>, wherein the temperature sensor is provided in correspondence with the lap portion of the iron core. <Part 3> The temperature sensor is located on the first core support member, as described in part 2 of the high-frequency excitation heating device. <Part 4> The high-frequency excitation heating apparatus described in <Part 3>, wherein, based on the measurement value from the temperature sensor, the program controller continues to instruct the supply of AC power to the high-frequency induction coil until a specified time has elapsed since the target temperature was reached. <Part 5> The high-frequency excitation heating device described in <Part 4> issues an instruction to the function generator to adjust the AC current it generates to reduce the output power when the measured value from the temperature sensor reaches the indicated temperature. <Part 6> The high-frequency excitation heating device according to <5>, which has a temperature sensor other than the aforementioned temperature sensor. <Part 7> The high-frequency excitation heating device described in <6> performs additional feedback control according to the measurement values ​​of the other temperature sensors. <Part 8> <7> A high-frequency excitation heating device that determines that there is a device malfunction and stops the output voltage when the measurement value of the other temperature sensor exceeds the measurement value of the aforementioned temperature sensor. <Part 9> A first core support member is placed inside the core, a second core support member is placed outside the core, and the first core support member and the second core support member are fastened together while insulating them from each other. The first core support member and the second core support member are non-annular, A high-frequency induction coil is arranged around the first core support member, the second core support member, and the core. A method for manufacturing an iron core for stationary equipment, comprising supplying alternating current power to the aforementioned high-frequency induction coil to anneal the iron core, A method for manufacturing an iron core for stationary equipment, comprising placing a temperature sensor on either the first iron core support member or the second iron core support member, and feedback-controlling the AC power according to the measurement value of the temperature sensor. <Part 10> The method for manufacturing an iron core for stationary equipment according to <9>, wherein the temperature sensor is provided corresponding to the overlap portion of the iron core. <Part 11> A method for manufacturing a core for stationary equipment according to <10>, wherein the temperature sensor is arranged in the first core support member. <Part 12> A method for manufacturing an iron core for stationary equipment as described in <Part 11>, which supplies AC power to the high-frequency induction coil until a specified time has elapsed since the target temperature was reached, based on the measurement value from the temperature sensor. <Part 13> A method for manufacturing an iron core for stationary equipment according to <12>, wherein the AC power is reduced when the measured value from the temperature sensor reaches the indicated temperature. <Part 14> A method for manufacturing an iron core for stationary equipment according to <13>, which uses the measured value of a temperature sensor other than the aforementioned temperature sensor for control. <Part 15> A method for manufacturing an iron core for stationary equipment as described in <14>, wherein if the measured value of the other temperature sensor exceeds the measured value of the temperature sensor, the device is deemed to be malfunctioning and the output voltage is stopped. <Part 16> A method for manufacturing a core for stationary equipment according to any one of items <9> to <15>, wherein the core for stationary equipment is an amorphous core. [Explanation of Symbols]

[0047] 1a: Amorphous iron core 1b: Lap joint of the iron core 2a: Core support member on the inside of the core 2b: Core support member on the outside of the core 3: Bolt 4: High-frequency excitation winding 5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h: Temperature sensor 6: Programmable Controller 7: Function Generator 8: Power supply

Claims

1. It comprises a first core support member positioned on the inside of the core, a second core support member positioned on the outside of the core, and a fastening member that fastens the first core support member and the second core support member together while insulating them from each other. The first core support member and the second core support member are non-annular, The device comprises the first core support member, the second core support member, and a high-frequency induction coil arranged around the core. The system comprises a power supply that supplies AC power to the high-frequency induction coil, a function generator that generates AC power, and a program regulator that generates control signals to command the function generator. A high-frequency excitation heating device having a temperature sensor in either the first core support member or the second core support member, wherein the measured value of the temperature sensor is input to the program controller, and the program controller provides feedback control of the AC power according to the measured value of the temperature sensor.

2. The high-frequency excitation heating device according to claim 1, wherein the temperature sensor is provided corresponding to the lap portion of the iron core.

3. The high-frequency excitation heating device according to claim 2, wherein the temperature sensor is disposed on the first iron core support member.

4. The high-frequency excitation heating apparatus according to claim 3, wherein, based on the measurement value from the temperature sensor, the program controller continues to instruct the supply of AC power to the high-frequency induction coil until a specified time has elapsed since the target temperature was reached.

5. The high-frequency excitation heating device according to claim 4, wherein when the measured value from the temperature sensor reaches the indicated temperature, an instruction is given to the function generator to adjust the AC that it generates to reduce the output power.

6. The high-frequency excitation heating apparatus according to claim 5, further comprising a temperature sensor other than the aforementioned temperature sensor.

7. The high-frequency excitation heating device according to claim 6, which performs additional feedback control according to the measurement value of the other temperature sensor.

8. The high-frequency excitation heating device according to claim 7, wherein if the measured value of the other temperature sensor exceeds the measured value of the temperature sensor, the device is deemed to be malfunctioning and the output voltage is stopped.

9. A first core support member is placed inside the core, a second core support member is placed outside the core, and the first core support member and the second core support member are fastened together while insulating them from each other. The first core support member and the second core support member are non-annular, A high-frequency induction coil is arranged around the first core support member, the second core support member, and the core. A method for manufacturing an iron core for stationary equipment, comprising supplying alternating current power to the aforementioned high-frequency induction coil to anneal the iron core, A method for manufacturing an iron core for stationary equipment, comprising placing a temperature sensor on either the first iron core support member or the second iron core support member, and feedback-controlling the AC power according to the measurement value of the temperature sensor.

10. The method for manufacturing a core for stationary equipment according to claim 9, wherein the temperature sensor is provided corresponding to the overlapping portion of the core.

11. The method for manufacturing a core for stationary equipment according to claim 10, wherein the temperature sensor is arranged in the first core support member.

12. A method for manufacturing an iron core for stationary equipment according to claim 11, which supplies AC power to the high-frequency induction coil until a specified time has elapsed since the target temperature was reached, based on the measurement value from the temperature sensor.

13. A method for manufacturing an iron core for stationary equipment according to claim 12, wherein the AC power is reduced when the measured value from the temperature sensor reaches the indicated temperature.

14. A method for manufacturing an iron core for stationary equipment according to claim 13, wherein the measured value of a temperature sensor other than the aforementioned temperature sensor is used for control.

15. A method for manufacturing an iron core for stationary equipment according to claim 14, wherein if the measured value of the other temperature sensor exceeds the measured value of the temperature sensor, the device is deemed to be malfunctioning and the output voltage is stopped.

16. The method for manufacturing a core for stationary equipment according to any one of claims 9 to 15, wherein the core for stationary equipment is an amorphous core.

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