JP6332852B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating apparatus.

  As an induction heating apparatus, as shown in Patent Document 1, there is an induction heating apparatus in which a temperature detection element is attached to a heated object and the temperature is directly measured.

  However, the operation of attaching the temperature detection element to the heated body is troublesome, and there is a danger in removing the temperature detection element from the heated heated body. Furthermore, when attaching a temperature detection element to a to-be-heated body, the contact state of a temperature detection element and a to-be-heated body differs separately, and it may become an error of detection temperature.

  In addition, although the method of detecting the temperature of a to-be-heated body using non-contact-type temperature detection means, such as a radiation-type thermometer, can also be considered, detection accuracy is low or it influences the surface emissivity (emissivity) of a to-be-heated body. In many cases, accurate temperature detection is difficult.

JP 2002-79559 A

  Accordingly, the present invention has been made in order to solve the above-described problems, and it is a main object of the present invention to eliminate the need for a temperature detection element for measuring the temperature of the object to be heated in the induction heating apparatus.

  That is, the induction heating device according to the present invention includes a power supply circuit that is connected to a winding of a magnetic flux generation mechanism and is provided with a control element that controls an alternating current or an alternating voltage. An induction heating apparatus for induction heating, which is obtained from an alternating current value obtained from an alternating current detector that detects an alternating current flowing through the winding and an alternating voltage detector that detects an alternating voltage applied to the winding. An impedance calculation unit for calculating the impedance of the winding by an AC voltage value, a relational data storage unit for storing relational data indicating a relationship between the impedance of the winding and the temperature of the heated object, and the impedance calculation unit The temperature to be heated is calculated from the impedance obtained by the above and the relational data stored in the relational data storage unit Characterized in that it comprises a temperature calculating unit.

  If it is such, the to-be-heated body temperature calculation part which calculates the temperature of a to-be-heated body from the impedance obtained by the impedance calculation part and the relationship data which shows the relationship between the impedance of a winding, and the to-be-heated body temperature Therefore, the temperature of the object to be heated can be calculated by calculating the impedance of the winding without providing a temperature detecting element in the object to be heated.

The impedance obtained by the impedance calculation unit shows a constant change characteristic between the winding and the temperature of the heated surface of the heated object facing the winding.
The relationship between the impedance and the temperature of the heated surface of the heated body when the rated voltage of the verified heated body (cylindrical metal kettle having outer diameter Φ × depth L × side wall thickness t) is applied is The following approximate expression is obtained.
^{_{θ 0 = k n Z n +}} k n-1 Z n-1 + k n-2 Z n-2 +, ···, + k 2 Z 2 + k 1 Z + k 0
Here, θ ₀ is the temperature [° C.] of the heated surface, Z is impedance (= E / I), k _n (n = 1, 2,..., N), and k ₀ are coefficients determined by actual measurement values. It is.

The heated surface of the heated object that faces the winding of the magnetic flux generation mechanism becomes a heat generating portion, but correction is required for calculating the temperature at a location away from the heat generating portion.
The object to be heated has a hollow cylindrical shape in which the area of the heat generating part and the area of the part spaced from the heat generating part are different, and a flat plate shape in which those areas can be regarded as substantially the same. Depending on the case and the case where each side wall is in the shape of a hollow polygonal cylinder having a flat plate shape, a correction formula suitable for each is adopted.

When the object to be heated has a hollow cylindrical shape and the magnetic flux generating mechanism heats the object to be heated from the outer peripheral side or the inner peripheral side, the temperature of the heated object temperature calculation unit is as follows: Calculate the temperature of the calculation surface.
That is, when the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], the heated object temperature calculating unit, The temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ obtained using the following equation to calculate the temperature of the temperature calculation surface.
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface, d ₂ is the diameter [m] of the temperature calculating surface, and λ is an average temperature between the heated surface and the temperature calculating surface. The thermal conductivity [W / m · ° C.], P is the heat flow rate [W / m], and k is a correction coefficient calculated from the actual measurement value.

  The thermal conductivity λ varies depending on the material and temperature of the object to be heated. For example, the characteristics of temperature and thermal conductivity of carbon steel are shown in FIG. Further, the current penetration degree of the object to be heated is several μm at a high frequency of several tens to several hundreds kHz, but a current penetration degree of several mm to several tens mm is obtained at a medium frequency of 50 to 1000 Hz. For example, carbon steel has a current penetration of about 10 mm at 60 Hz and 500 ° C. That is, since current penetration is deep in medium frequency induction heating, the difference between the temperature of the heat generating portion (temperature of the heated surface) and the temperature of the temperature calculation surface is smaller than that of the high frequency.

  Measure the temperature rise of the heat generation density and the reached temperature under a certain condition, approximate the relationship between the temperature of the temperature calculation surface of the heated object and the impedance, and calculate the temperature calculation surface of the heated object from the impedance using the approximate expression Find the temperature of If the heat generation density changes, the temperature difference θ in the wall thickness t (distance t between the heated surface and the temperature calculation surface) also changes, and if the temperature reached by the temperature calculation surface of the heated object changes, the average temperature changes. Thermal conductivity also changes. If they are calculated using a conversion formula, the temperature of the temperature calculation surface of the object to be heated can be obtained, and the temperature of the temperature calculation surface of the object to be heated can be calculated by impedance.

It is desirable that a jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed on a side peripheral wall of the object to be heated. The jacket chamber makes the temperature of the heated object uniform by heat transport by the enclosed gas-liquid two-phase heat medium, and the temperature of the temperature calculation surface of the heated object is also made uniform at the same time.
That is, the detection of the temperature of the object to be heated by impedance detects the average temperature of the surface to be heated, so the temperature of the temperature calculation surface of each part of the object to be heated that is made uniform by the jacket chamber depends on the impedance. It can be said that this is equivalent to a value obtained by adding necessary correction to the detected temperature and converting it to the temperature of the temperature calculation surface.
Here, the cross-sectional area between the heated surface and the temperature calculating surface is S [m ² ], and the sum of the cross-sectional areas of the jacket chamber between the heated surface and the temperature calculating surface is S _j [m ^2]. When the distance between the heated surface and the temperature calculation surface is t [m], and the variable indicating the ratio of the function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, The heated body temperature calculation unit _sets the diameter d _{1 of the} heated surface as d _j1 = d ₁ ± t {1−α (1−S _j / S)}, and sets the diameter d ₂ of the temperature calculated surface to , D _j2 = d ₂ ± t {1-α (1-S _j / S)} is preferably used to correct the temperature of the object to be heated.
D _j1 is the virtual diameter of the heated surface considering the distance (thickness) reduction due to the jacket chamber, and d _j2 is the virtual temperature calculation plane considering the distance (thickness) reduction due to the jacket chamber. Diameter. Further, in the formula of d _j1 , the ± part is negative when d ₁ > d ₂ and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ .

Let S be the cross-sectional area perpendicular to the central axis of the object to be heated having a hollow cylindrical shape, S _j be the sum of the cross-sectional areas perpendicular to the central axis of the jacket chamber, and the distance between the heated surface and the temperature calculation surface When t, the thermally converted distance t _j is expressed by the following equation.
t _j = α × t (S−S _j ) / S (α> 1)
Here, α is a variable indicating the rate of deterioration of the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop. The α-θ relationship is determined by the type of heat medium and the impurity concentration in the jacket chamber.

The difference between the distance t and the thermal conversion distance t _j is
t−t _j = t−α × t (S−S _j ) / S
= T {1-α (S−S _j ) / S}
= T {1-α (1-S _j / S)}

Therefore, the virtual diameter d _{j1 of the} heated surface and the virtual diameter d _j2 of the temperature calculation surface, which are thermally converted, are as follows.
d _j1 = d ₁ ± t {1-α (1-S _j / S)}
d _j2 = d ₂ ± t {1-α (1-S _j / S)}
In the formula of d _j1 , the ± part is negative when d ₁ > d ₂ , and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ .
That is, the calculated distance between the heated surface and the temperature calculation surface is reduced, and the temperature difference θ is reduced, so that the temperature measurement error is also reduced.

When the object to be heated has a flat plate shape and the magnetic flux generating mechanism heats the object to be heated from one side, the temperature calculation unit of the object to be heated calculates the temperature of the temperature calculation surface as follows. calculate.
That is, when the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], the heated object temperature calculating unit, The temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ obtained using the following equation to calculate the temperature of the temperature calculation surface.
θ = kQ / (λS / t)
Here, t is a distance [m] between the heated surface and the temperature calculating surface, S is a cross-sectional area [m ² ] between the heated surface and the temperature calculating surface, and λ is the above-mentioned It is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface and the temperature calculation surface, and Q is the calorific value [W] of the heated surface, k is a correction coefficient calculated from an actual measurement value.

The to-be-heated body has a hollow n-square cylindrical shape with a height h [m] and n side lengths a ₁ , a ₂ ,..., A _n [m], and the magnetic flux generation mechanism includes: In the case where the object to be heated is induction-heated from the outer peripheral side or the inner peripheral side, the heated object temperature calculation unit calculates the temperature of the temperature calculation surface as follows. The following shows a case where the distance between the heated surface and the temperature calculation surface is the same in each side wall.
That is, the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface which is a surface for calculating the temperature is θ [° C.], and the heated surface on each side of the heated object When the distance between the temperature calculation surfaces is t [m], the heated object temperature calculation unit calculates the temperature of the heated object obtained from the impedance and the relational data as follows: The temperature of the temperature calculation surface is calculated by correcting using the temperature difference θ obtained by using.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, and λ is the thermal conductivity [W / m · ° C.] of the heated object at an average temperature [° C.] between the heated surface and the temperature calculating surface, Q is the calorific value [W] of the surface to be heated, k is a correction coefficient calculated from actual measurement values, and _mn is a constant at n.

In the case where a jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed in the thickness of the heated object having a flat plate shape or a hollow n-square tube shape as described above, the heated surface and the The cross-sectional area between the temperature calculation surfaces is S [m ² ], the sum of the cross-sectional areas of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], and the heat medium accompanying the temperature decrease When the variable indicating the rate of reduction in the function of the jacket chamber due to the pressure drop is α, the heated object temperature calculation unit sets the distance t between the heated surface and the temperature calculation surface to t _j = αt It is desirable to correct the temperature of the object to be heated using the temperature difference θ obtained as (S−S _j ) / S.

On the other hand, in the object to be heated having the above-described hollow n-square tube shape, when the distance between the surface to be heated and the temperature calculation surface of each side wall portion is different, the temperature of the object to be heated is calculated as follows. Calculate the temperature of the calculation surface.
That is, the temperature difference between the heated surface of the heated body facing the winding of each side wall portion of the heated body and the temperature calculation surface that is a surface for calculating the temperature is θ _n [° C.], and When the distance between the heated surface and the temperature calculation surface of each side wall portion of the heated object is t ₁ , t ₂ ,... T _n [m], the heated object temperature calculating unit is Then, the temperature of the object to be heated obtained from the impedance and the relational data is corrected using a temperature difference θ _n obtained using the following equation to calculate the temperature of the temperature calculation surface.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance between the heated surface and the temperature calculated surface at the n-th sidewall part [m], S _n is the heated surface and the temperature calculated surface at the n-th sidewall part the cross-sectional area [m ^2] between, lambda _n is n th said at side wall portions of the heating surface and the thermal conductivity of the object to be heated at an average temperature [℃] between the temperature calculated surface [W / m a · ° C.], Q _n is the heat value of the heated surface of the n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value.

At this time, in the case where a jacket chamber in which a gas-liquid two-phase heat medium is sealed is formed within the thickness of the heated body, the heated surface and the temperature calculating surface of the nth side wall portion. When the sum of the cross-sectional areas of the jacket chamber is S _nj [m ² ], and the variable indicating the rate of decrease in the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the temperature of the heated object The calculation unit calculates a temperature difference θ _n obtained by setting the distance t _n between the heated surface and the temperature calculation surface in the n th side wall as t _nj = αt _n (S _n −S _nj ) / S _n. It is desirable to correct the temperature of the object to be heated.

  An impedance correction unit that corrects the impedance obtained by the impedance calculation unit using a power supply voltage value obtained from a power supply voltage detection unit that detects a power supply voltage of the power supply circuit, and the heated object temperature calculation unit includes It is desirable to calculate the temperature of the object to be heated from the corrected impedance corrected by the impedance correction unit and the relation data.

In general, the power supply voltage varies between product shipment and user use. For example, if the specification is 200V, the induction heating device is required to operate normally in the range of 190V to 210V. In particular, since the entire input voltage is applied when the temperature of the object to be heated is initially raised, it is necessary to correct the impedance value in accordance with the received voltage value.
Here, it is necessary to correct the impedance-temperature characteristic equation (the relational data) calculated with the power supply voltage V1 at the time of shipment in accordance with the power supply voltage V2 at the time of use by the user.
This is because, in the equivalent circuit of the single-phase induction heating device shown in FIG. 6, when the power supply voltage changes, the magnetic flux density in the magnetic circuit changes, so that the excitation impedances r ₀ and l ₀ and the reactance l _{2 of the} heated object are altered, also the resistance r ₂ of the object to be heated is changed in a current penetration is changed by the magnetic permeability of the heated object due to a change in the magnetic flux density changes, in order to change the circuit impedance.

When the relationship between the temperature of the surface to be heated and the impedance is approximated, the impedance changes because the current penetration changes due to the change in magnetic flux density due to the change in input voltage. For this reason, it is necessary to correct the reading of the approximate expression.
The current penetration σ of the object to be heated can be calculated by σ = 5.033√ (ρ / μs × f). In the equation, ρ is specific resistance, μs is relative permeability, and f is frequency. Here, the relative magnetic permeability of the heated body made of a magnetic material changes depending on the magnetic flux density, and shows a characteristic specific to each metal type. The relative permeability-magnetic flux density characteristic of this magnetic material is measured in advance, the current penetration at the magnetic flux density corresponding to the input voltage is calculated, the impedance is inversely proportional to the current penetration, and the temperature is read. It will be. In addition, since the specific resistance also shows a characteristic of change with temperature for each metal species, the current penetration degree σ also changes with the temperature change, and the impedance changes. However, the relational approximate expression between the heat generating part temperature of the heated body (temperature of the heated surface) and the impedance is an expression including a change in the heat generating part temperature of the heated body, and correction for this is not necessary.

  Specifically, if the control element is a voltage variable device such as an induction voltage regulator, the magnetic flux density of the magnetic circuit is changed by changing the input voltage to the winding, and the current or voltage is changed by the semiconductor. When the input voltage changes depending on the conduction angle, the magnetic flux density of the magnetic circuit changes and the temperature of the heated object also changes, so that the current penetration of the heated object is controlled. The degree σ changes.

Due to the change in magnetic flux density due to the change in input voltage, the excitation characteristics of the magnetic circuit also change, and the values of the excitation impedances r ₀ and l ₀ of the equivalent circuit in FIG. 6 also change. This excitation characteristic shows an inherent relationship with the magnetic flux density of the magnetic circuit, depending on the material of the heated object, so that the characteristic is measured in advance and the impedance is corrected.
Further, the reactance l ₂ of the heated body of the equivalent circuit of FIG. 6 also changes due to the change in magnetic flux density due to the change in input voltage. Since the reactance l ₂ of the heated object shows a change related to the specific resistance and magnetic flux density of the heated object, the characteristic is measured in advance and the impedance is corrected. The reactance l ₁ is a value determined by the structure of the heated object, and needs to be calculated in advance.

  Also, when the power supply voltage fluctuates rapidly during the operation of the induction heating device, the magnetic flux density of the magnetic circuit also changes abruptly and the current penetration changes, so the impedance changes, but the temperature change of the heated object A considerable time delay occurs. Since the time delay of temperature varies depending on the structure of the heated body (material, dimensions, weight, etc.), it is necessary to define an individual correction formula for each type of heated body.

In the case of the verified induction heating apparatus, the correction formula is as follows.
Z _n = {1−a (E−V _in ) ^b } Z _on
Here, E is the rated power supply voltage, V _in is the control element input voltage, Z _on is the impedance at time t _n before correction, n is a number indicating the detection order, and a and b are subject to detection. It is a constant for each heating element.
For example a Z _on calculated from the effective voltage and effective current between time divided into about several tens of microseconds t _n, it is substituted into the above correction formula, obtaining the corrected impedance Z _n.
Further, Z _{o (n + 1)} obtained from the effective voltage and effective current at the next divided time t _{(n + 1)} is substituted into the correction equation to obtain the corrected impedance Z _{(n + 1)} . In this way, impedance correction is performed continuously for each of the time intervals.

  Furthermore, when the control element is a semiconductor, the waveform shape of the voltage and current changes depending on the energization angle, but since it changes to a different shape, the voltage of the excitation impedance is changed by changing the shared voltage of each impedance. As the magnetic flux density changes, the excitation impedance and the relative permeability also change. At this time, if the control element, the energization angle, and the load are determined, the voltage and the current each have a fixed shape, and thus the correction coefficient according to the energization angle is determined.

  Here, an impedance correction unit that corrects the impedance obtained by the impedance calculation unit based on an energization angle of the control element is further provided, and the heated object temperature calculation unit includes the corrected impedance corrected by the impedance correction unit and It is desirable to calculate the temperature of the object to be heated from the relation data.

When the control element is a thyristor and the object to be heated (cylindrical metal kettle with outer diameter Φ x depth L x side wall thickness t) is equivalent due to a change in harmonic components due to waveform distortion The voltage applied to the reactance components l ₁ and l ₂ in the circuit will change. Therefore, the voltage applied to the excitation impedance changes and the magnetic flux density also changes. That is, since the excitation impedance and the relative permeability change depending on the magnetic flux density, it is necessary to correct the influence.
The corrected impedance Z that corrects the influence due to the phase angle change of the thyristor is as follows.
Z = a × Z _x
Here, if C = V / V _in ,
^{_{a = a n C n + a}} n-1 C n-1 + a n-2 C n-2 +, ···, + a 2 C 2 + a 1 C + a 0
Here, a _n is a coefficient based on the measured value determined by the induction heating device, a ₀ is a constant.
Further, Z _x is the uncorrected impedance, V _in is the receiving voltage of the thyristor, V is an output voltage of the thyristor.

  It is desirable that the impedance correction unit corrects the impedance obtained by the impedance calculation unit with a winding temperature obtained from a temperature detection unit that detects the temperature of the winding.

When the temperature of the winding that is the primary coil changes due to energization, r ₁ in the equivalent circuit of the single-phase induction heating device shown in FIG. 6 changes, so that the circuit impedance also changes, that is, V / I. Will also change. However, this change is irrelevant to the change in the temperature of the heat generating part of the heated body, and it is necessary to correct the change.

The resistivity and temperature of the winding have a relationship that is approximately proportional to the absolute temperature, but shows inherent change characteristics depending on the material. For example, if the wire material is copper, the following relationship is established. Therefore, if the temperature sensor is embedded in the winding and the winding temperature is detected, r ₁ can be calculated.
r ₁ = kL / 100S [Ω]
k = 2.1 (234.5 + θ _c ) /309.5
Here, L is the wire length [m], S is the wire cross-sectional area [mm ² ], and θ _c is the winding temperature [° C.].

In addition, the induction heating device controls the DC power supply, applies a DC voltage intermittently to the winding, applies the DC voltage applied by the DC voltage application unit, and the DC voltage. A resistance value calculating unit that calculates a resistance value of the winding from a direct current that sometimes flows through the winding, and the impedance correction unit calculates the impedance obtained by the impedance calculating unit as the resistance value It may be corrected by the resistance value obtained from the part.
The winding resistance value can be calculated by applying a constant DC voltage to the winding in a short time within a few seconds and dividing the DC voltage by the DC current flowing through the winding. Here, since there is no inductive action in the case of a DC voltage, the DC current is not affected by the heated object, and has only a relationship with the winding resistance value. Since the winding temperature does not change abruptly, even if periodic and short-time measurement values are used, no large measurement error is produced.

  Further, intermittent application of the DC voltage means that the application time within a few seconds is performed at a constant period of several seconds to several tens of minutes, for example. With such intermittent application, it is possible to reduce the demagnetizing action received from the DC component and to minimize the influence on the AC circuit for induction heating. Further, the winding of the induction heating device generally has a large thermal inertia, and the change in the temperature of the winding does not become a large value in the operation under a normal constant load condition. Therefore, if temperature detection performed by a short application time within several seconds is performed in units of several seconds to several tens of minutes, preferably in units of several tens of seconds to several minutes, it is sufficient for temperature control of the object to be heated. I can say that.

  The resistance value calculation unit applies a DC voltage to the winding and calculates a winding resistance value in a state where the AC current or the AC voltage is cut off or minimized by a control element provided in the power supply circuit. It is desirable to be a thing.

  In order to detect only the DC component (DC current) from the current in which the AC current and DC current are superimposed by applying DC voltage to the winding to which AC voltage is applied, a complicated detection circuit is required. End up. Here, the normal induction heating apparatus includes a power supply circuit having a control element for controlling an alternating current or an alternating voltage for controlling the temperature of the heated object. For this reason, if the AC current or the AC voltage is cut off or set to a minimum value only during the application time for applying the DC voltage by the control element, the influence of the AC current (AC component) can be suppressed. Component) can be easily detected. Here, the interruption or the minimum value of the AC current or AC voltage is a short time within a few seconds, and is a time interval of several seconds to several tens of minutes, and does not hinder the induction heating action.

  As an embodiment in which the alternating current or the alternating voltage is cut off or set to a minimum value, when the control element has a switch device such as an electromagnetic contactor, the switch device is cut off, or the control circuit unit has, for example, In the case where a semiconductor element (power control element) such as a thyristor is included, a mode in which the energization phase angle of the semiconductor element is minimized can be considered.

  In addition, the induction heating device has a relation data storage section that stores relation data indicating a resistance value-temperature relation between the resistance value of the winding and the temperature of the winding, and the resistance value obtained by the resistance value calculation section. And a winding temperature calculation unit that calculates the temperature of the winding from the resistance value-temperature relationship indicated by the relationship data.

  According to the present invention configured as described above, the temperature of the object to be heated can be calculated by calculating the impedance of the winding without providing the temperature detection element in the object to be heated.

The figure which shows typically the structure of the induction heating apparatus which concerns on 1st Embodiment. Sectional drawing which shows the structure of the induction heating unit of the embodiment typically. The function block diagram of the control apparatus of the embodiment. The figure which shows the temperature calculation flow of the embodiment. The characteristic graph which shows the relationship between the temperature of carbon steel (S45C), and thermal conductivity. The figure which shows the equivalent circuit of a single phase induction heating unit. The characteristic graph which shows the relationship between the magnetic flux density and relative permeability of carbon steel (S45C). Sectional drawing which shows typically the structure of the induction heating unit which concerns on 2nd Embodiment. Sectional drawing which shows typically the structure of the induction heating unit which concerns on 3rd Embodiment. Sectional drawing which shows typically the structure of the induction heating unit which concerns on 4th Embodiment.

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

  As shown in FIG. 1, the induction heating apparatus 100 according to this embodiment includes a heated body 2 that is heated to heat-treat a processing target, an iron core 31 and a winding for induction heating the heated body 2. A magnetic flux generation mechanism 3 composed of a wire 32 and a power supply circuit 5 connected to the winding 32 and provided with a control element 4 for controlling current or voltage are provided.

  As shown in FIG. 2, the heated body 2 of the present embodiment has a housing portion that houses the object to be processed, and has a height of h [m], an outer diameter of φ [m], and a side wall portion. It is a metal pot having a hollow cylindrical shape with a thickness of t [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially cylindrical shape that is wound around the outer peripheral surface of the heated body 2 having a hollow cylindrical shape. Thereby, the outer peripheral surface of the heated body 2 becomes a heated surface 2 h that is heated to face the winding 32.

  Furthermore, the control element 4 of this embodiment controls the conduction angle of an alternating current or an alternating voltage with a semiconductor, and is specifically a thyristor.

  And the control apparatus 6 which controls the induction heating apparatus 100 of this embodiment has a temperature calculation function which calculates the temperature of the temperature calculation surface 2x of the to-be-heated body 2 from the impedance of the winding 32. FIG. The temperature calculation surface 2x of the present embodiment is a surface for calculating a temperature that is separated from the heated surface 2h in the thickness direction in the side wall portion of the heated body 2. The control device 6 of the induction heating device 100 controls the power supply circuit 5 having the control element 4 so that the temperature of the temperature calculation surface 2x becomes a desired temperature.

  Specifically, the control device 6 is a dedicated or general-purpose computer including a CPU, an internal memory, an A / D converter, a D / A converter, an input / output interface, and the like. The control device 6 is configured according to a predetermined program stored in the internal memory. When the CPU and peripheral devices operate, as shown in FIG. 2, functions as an impedance calculation unit 61, an impedance correction unit 62, a relational data storage unit 63, a heated object temperature calculation unit 64, and the like are exhibited.

  Hereinafter, each part will be described with reference to the temperature calculation flowchart of FIG. 4 together with FIG. 3.

The impedance calculation unit 61 is obtained from the AC voltage detection unit 8 that detects the AC current value obtained from the AC current detection unit 7 that detects the AC current I that flows through the winding 32 and the AC voltage V that is applied to the winding 32. Based on the AC voltage value, impedance Z ₁ (= V / I) of winding 32 is calculated ((1) in FIG. 4).

Impedance correction unit 62, the impedance Z ₁ obtained by the impedance calculation unit 61, a power supply voltage that created the related data at the time of product shipment, the difference component of the power supply voltage used by the user (difference between the supply voltage) Correction is performed ((2) in FIG. 4).

The impedance correction unit 62, the impedance _{Z 1,} is corrected by conduction angle control element (thyristor) 4 (phase angle) ((3 in FIG. 4)).

Specifically impedance correction unit 62, according to the following equation to correct the impedance Z _1.
Z ₂ = a × Z ₁
Here, if C = V / V _in ,
^{_{a = a n C n + a}} n-1 C n-1 + a n-2 C n-2 +, ···, + a 2 C 2 + a 1 C + a 0
Here, a _n is a coefficient based on the measured value determined by the induction heating device, a ₀ is a constant.
Further, Z ₁ is the uncorrected impedance, V _in is the receiving voltage of the thyristor, V is an output voltage of the thyristor.

In addition, when the power supply voltage fluctuates rapidly during the operation of the induction heating apparatus 100, the magnetic flux density of the magnetic circuit also changes abruptly, and the current penetration degree of the heated object changes, so that the impedance changes. There is a considerable time delay in body temperature changes. For this reason, the impedance correction unit 62 of the present embodiment corrects Z ₂ corrected by the energization angle by the power supply voltage value E obtained from the power supply voltage detection unit 9 that detects the power supply voltage of the power supply circuit 5 (FIG. 4 (4)).

Specifically impedance correction unit 62, according to the following equation to correct the impedance Z _{2.
Z 3 = {1-a (} E-V in) b} Z 2
Here, E is the rated supply voltage, V _in is the control element input voltage, Z ₂ is the impedance of before the correction, a and b are constants for each object to be heated (induction heating unit). This correction is continuously performed at every divided time.

Further, the impedance correction unit 62 corrects the impedance Z ₃ corrected by the energization angle and the power supply voltage E by the winding temperature θ _c [° C.] obtained from the temperature detection unit 10 that detects the temperature of the winding 32. ((5) in FIG. 4). The temperature detection unit 10 is embedded in the winding 32.

Specifically, the impedance correction unit 62 calculates the resistance r ₁ of the winding 32 by the following formula and corrects the impedance Z ₃ .
r ₁ = kL / 100S [Ω]
k = 2.1 (234.5 + θ _c ) /309.5
Here, L is the wire length [m], S is the wire cross-sectional area [mm ² ], and θ _c is the winding temperature [° C.].

  The relationship data storage unit 63 stores relationship data indicating a relationship (V / I-θ characteristic approximation formula) between the impedance of the winding 32 and the temperature of the heated object 2. Specifically, the relationship data is data indicating the relationship between the impedance of the winding 32 and the temperature of the heated surface 2h of the heated body 2. In addition, as described above, the impedance of the winding 32 is obtained by calculating the impedance obtained from the AC current value of the current detection unit 7 and the AC voltage value of the voltage detection unit 8 as described above when obtaining the relational data. It is obtained by correcting with the line temperature ((1) to (5) in FIG. 4). This relational data is obtained using a reference induction heating apparatus. The related data storage unit 63 may be set in a predetermined area of the internal memory, or may be set in a predetermined area of the external memory externally attached to the control device 6. .

  The heated object temperature calculation unit 64 uses the corrected impedance corrected by the impedance correction unit 62 and the relationship data stored in the relationship data storage unit 63, so that the temperature of the heated surface 2h of the heated object 2 is increased. Is calculated ((6) in FIG. 4).

Specifically, the heated body temperature calculation unit 64 calculates the temperature difference between the temperature of the heated surface 2h of the heated body 2 and the temperature calculation surface 2x that is a surface for calculating the temperature separated from the heated surface 2h by θ. When the temperature is [° C.], the temperature of the heated surface 2h is corrected using the temperature difference θ obtained from the following equation to calculate the temperature of the temperature calculation surface 2x ((7) in FIG. 4).
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface 2h, d ₂ is the diameter [m] of the temperature calculating surface 2x, and λ is the average between the heated surface 2h and the temperature calculating surface 2x. It is the thermal conductivity [W / m · ° C.] at temperature, P is the heat flow rate [W / m], and k is a correction coefficient calculated from the measured value. The heat flow rate P [W / m] is a value obtained by dividing the heat generation amount [W] of the inner surface of the heated body 2 by the heat generation inner surface length [m] (equal to the winding width), and the heat flow rate [W / m]. In determining m], the heated object temperature calculation unit 64 uses the power value obtained from the power detection unit 11.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as the cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and cuts the jacket chamber between the heated surface 2h and the temperature calculating surface 2x. The sum of the areas is S _j [m ² ], the distance between the heated surface 2h and the temperature calculation surface 2x is t [m], and the rate of decrease in the function of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is When the variable shown is α, the diameter d ₁ of the heated surface 2h is assumed to be a virtual diameter d _j1 (= d ₁ −t {1−α (1−S _j / S)}) in consideration of the thickness reduction. And the diameter d ₂ of the temperature calculation surface 2x is a virtual diameter d _j2 (= d ₂ + t {1−α (1−S _j / S)}) in consideration of the thickness reduction, The temperature calculation of the heated body 2 is performed by correcting the temperature of the heated surface 2h of the heated body 2 using the temperature difference θ obtained from To calculate the temperature of the surface 2x.

  According to the induction heating apparatus 100 of the present embodiment configured as described above, the object to be heated is obtained from the impedance obtained by the impedance calculating unit 61 and the relational data indicating the relationship between the impedance of the winding 32 and the temperature of the object to be heated 2. Since it has the to-be-heated body temperature calculation part 64 which calculates the temperature of the body 2, the temperature of the to-be-heated body 2 is calculated by calculating the impedance of the winding 32, without providing the temperature detection element in the to-be-heated body 2. can do.

  Moreover, since the impedance obtained by the impedance calculation unit 61 is corrected by the impedance correction unit 62 using the conduction angle of the thyristor 4, the power supply voltage E of the power supply circuit 5, and the temperature of the winding 32, the object to be heated is corrected. The temperature of 2 can be calculated with high accuracy.

  Further, the heated object temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x based on the temperature difference θ between the temperature of the heated surface 2h of the heated object 2 and the temperature of the temperature calculation surface 2x. The temperature of the temperature calculation surface 2x of the heating body 2 can be calculated with high accuracy.

Second Embodiment
Next, a second embodiment according to the present invention will be described. The induction heating apparatus according to the second embodiment is different from the first embodiment in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

  As shown in FIG. 8, the heated object 2 according to the second embodiment has a flat plate shape with a thickness t [m], where one surface (the upper surface in FIG. 8) serves as a working surface for applying heat to the object to be processed. It is a metal heating plate. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed in a lattice shape within the thickness of the heated body 2.

  The winding 32 has a substantially flat plate shape provided on the other surface (the lower surface in FIG. 8) of the heated body 2 so as to be separated from the other surface. Thereby, the other surface of the to-be-heated body 2 becomes the to-be-heated surface 2h heated with the winding 32, and the winding 32 which is a magnetic flux generation mechanism becomes the structure which induction-heats the to-be-heated body 2 from one side.

And the to-be-heated body temperature calculation part is the temperature calculation surface 2x which is a surface which calculates the temperature of the to-be-heated surface 2h of the to-be-heated body 2 calculated | required similarly to the said embodiment, and the temperature away from the said to-be-heated surface 2h. When the temperature difference from (for example, the temperature of the working surface that is the upper surface) is θ [° C.], the temperature difference 2 θ is obtained from the following equation to correct the temperature of the heated surface 2 h and the temperature calculation surface 2 x The temperature of is calculated.
θ = kQ / (λS / t)
Here, t is the distance [m] between the heated surface 2h and the temperature calculating surface 2x, S is the cross-sectional area [m ² ] between the heated surface 2h and the temperature calculating surface 2x, and λ is the covered surface. The thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heating surface 2h and the temperature calculation surface 2x, and Q is the calorific value [W] of the heated surface 2h. Yes, k is a correction coefficient calculated from actual measurement values.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as a cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and a jacket between the heated surface 2h and the temperature calculating surface 2x. When the sum of the cross-sectional areas of the chamber is S _j [m ² ], and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the heated surface 2h and the temperature calculation surface The distance t between 2x is defined as a virtual distance t _j (= αt (S−S _j ) / S) in consideration of the thickness reduction, using the temperature difference θ obtained from the above temperature difference θ formula, By correcting the temperature of the heated surface 2h of the heated body 2, the temperature of the temperature calculating surface 2x of the heated body 2 is calculated.

<Third Embodiment>
Next, a third embodiment according to the present invention will be described. The induction heating apparatus according to the third embodiment is different from the first and second embodiments in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

As shown in FIG. 9, the heated object 2 according to the third embodiment has a housing part that houses the processing object or a passage part through which the processing object passes, and the height is h [m], the length of the n sides respectively _{a 1,} a 2, a metallic cylindrical body forming the (hollow square tubular shape in FIG. 9) hollow n rectangular tube shape ··· _a n [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially hollow n-square tube shape that is wound around the outer peripheral surface of the heated body 2 having a hollow n-square tube shape. Thereby, the outer peripheral surface of the heated body 2 becomes the heated surface 2h heated by the winding 32.

And the to-be-heated body temperature calculation part is the temperature calculation surface 2x which is a surface which calculates the temperature of the to-be-heated surface 2h of the to-be-heated body 2 calculated | required similarly to the said embodiment, and the temperature away from the said to-be-heated surface 2h. And the temperature difference of the temperature calculation surface 2x is calculated by correcting the temperature of the heated surface 2h using the temperature difference θ obtained from the following equation. In the third embodiment, the distance between the heated surface 2h and the temperature calculation surface 2x is the same in each side wall portion.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, λ is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface 2h and the temperature calculation surface 2x, and Q Is the calorific value [W] of the heated surface 2h, k is a correction coefficient calculated from the actual measurement value, and _mn is a constant at n. For example, when n = 4, m ₄ = 0.54.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2.

Specifically, the to-be-heated body temperature calculation unit 64 sets S [m ² ] as a cross-sectional area between the heated surface 2h and the temperature calculating surface 2x, and a jacket between the heated surface 2h and the temperature calculating surface 2x. When the sum of the cross-sectional areas of the chamber is S _j [m ² ], and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α, the heated surface 2h and the temperature calculation surface The distance t between 2x is defined as a virtual distance t _j (= αt (S−S _j ) / S) in consideration of the thickness reduction, using the temperature difference θ obtained from the above temperature difference θ formula, By correcting the temperature of the heated surface 2h of the heated body 2, the temperature of the temperature calculating surface 2x of the heated body 2 is calculated.

<Fourth embodiment>
Next, a fourth embodiment according to the present invention will be described. The induction heating apparatus according to the fourth embodiment is different from the first to third embodiments in the configuration of the heated body 2 and the function of the heated body temperature calculation unit 64.

As shown in FIG. 10, the heated object 2 according to the fourth embodiment has a housing part that houses the processing object or a passage part through which the processing object passes, and the height is h [m], _a 1 length of n sides, _{respectively,} a 2, a metallic cylindrical body forming the (hollow square tubular shape in FIG. 10) hollow n rectangular tube shape ··· _a n [m]. A plurality of jacket chambers 2S in which a gas-liquid two-phase heat medium is enclosed are formed at equal intervals in the circumferential direction along the central axis in the wall thickness of the side peripheral wall of the body 2 to be heated.

  In addition, the winding wire 32 of the present embodiment has a substantially hollow n-square tube shape that is wound around the outer peripheral surface of the heated body 2 having a hollow n-square tube shape. Thereby, the outer peripheral surface of the heated body 2 becomes the heated surface 2h heated by the winding 32.

And the to-be-heated body temperature calculation part calculates the temperature of the to-be-heated surface 2h of the to-be-heated body 2, and the temperature away from the to-be-heated surface 2h in each side wall part calculated | required similarly to the said 1st Embodiment. The temperature difference from the temperature calculation surface 2x that is the surface to be heated is θ _n [° C.], and the distance between the heated surface 2h and the temperature calculation surface 2x of each side wall portion of the heated body is t ₁ , t ₂ , ..., T _n [m], the temperature difference θ _n obtained from the following equation is used to correct the temperature of the heated surface 2h of each side wall, and the temperature calculation surface 2x of each side wall The temperature of is calculated.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance [m] between the n-th sidewall heated surface 2h and temperature calculation surfaces in section 2x, S _n is the n th side wall heated surface 2h and temperature calculation surfaces in section 2x the cross-sectional area [m ^2] between, lambda _n is the average temperature thermal conductivity of the heated object at [℃] between the n-th sidewall heated surface 2h and temperature calculation surfaces in section 2x [W / m · ℃] a and, Q _n is the heat value of the heated surface 2h at n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value.

  The heated body temperature calculation unit 64 calculates the temperature of the temperature calculation surface 2x of each side wall portion of the heated body 2 in consideration of the thickness reduction due to the jacket chamber 2S formed in the heated body 2. .

Specifically, the to-be-heated body temperature calculation unit 64 sets S _n [m ² ] as the cross-sectional area between the heated surface 2h and the temperature calculation surface 2x in the nth side wall, and the nth side wall in the nth side wall. The sum of the cross-sectional areas of the jacket chamber between the heated surface 2h and the temperature calculation surface 2x is S _nj [m ² ], and a variable indicating the rate of decrease in the function of the jacket chamber due to the decrease in the pressure of the heat medium accompanying the temperature decrease. When α is α, the distance t _n between the heated surface 2h and the temperature calculation surface 2x in the nth side wall portion is assumed to be a virtual distance t _nj (= αt _n (S _n −S _nj) in consideration of the thickness reduction. ) / S _n ), by using the temperature difference θ obtained from the equation of temperature difference θ, the temperature of the heated surface 2h of each side wall portion of the heated body 2 is corrected, thereby The temperature of the temperature calculation surface 2x of the side wall is calculated.

  The present invention is not limited to the above embodiment.

For example, in the above-described embodiment, the impedance correction unit corrects the impedance using the temperature of the winding 32. However, the heated object temperature calculation unit 64 calculates the temperature of the heated object 2 calculated from the impedance and related data. The temperature may be corrected using the temperature of the winding 32. In this case, the correction value Δt is, for example, m × θ _c + n (where m and n are coefficients calculated from actual measurement values).

  Moreover, in the said embodiment, based on the approximate expression which is the predetermined relationship of the temperature and the impedance of the to-be-heated surface 2h of a to-be-heated body, correction is added to the approximate expression, and the temperature calculation surface 2x of a to-be-heated body is corrected. Although the temperature was obtained, various conditions of the induction heating device and their changes are based on the approximate expression which is a predetermined relationship between the temperature and the impedance of the temperature calculation surface 2x of the object to be heated. Based on the influence on the temperature of 2x, the approximate expression may be corrected to obtain the temperature of the temperature calculation surface 2x of the heated object. For example, when obtaining an approximate expression that is a predetermined relationship between the temperature of the temperature calculation surface 2x of the heated object and the impedance, the temperature of the temperature calculation surface 2x of the heated object can be measured from the outside using a radiation thermometer. Conceivable. Further, in correcting the approximate expression, it is conceivable to perform correction similar to (2) to (4) in FIG.

  Further, in the first, third, and fourth embodiments, the winding 32 is disposed around the outer peripheral surface of the heated body 2 and the heated body 2 is induction-heated from the outer peripheral side. 32 may be disposed in the hollow of the heated body 2 and the heated body 2 may be induction heated from the inner peripheral side. In this case, the inner peripheral surface of the heated body 2 becomes the heated surface.

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

DESCRIPTION OF SYMBOLS 100 ... Induction heating apparatus 2 ... Heated object 2h ... Heated surface 2x ... Temperature calculation surface 2S ... Jacket chamber 3 ... Winding 4 ... Control element 5 ... Power supply circuit 6... Control device 61... Impedance calculation unit 62... Impedance correction unit 63... Relation data storage unit 64. ..AC voltage detector 9 ... Power supply voltage detector 10 ... Temperature detector 11 ... Power detector

Claims (12)

An induction heating device that is connected to a winding of a magnetic flux generation mechanism and includes a power supply circuit provided with a control element that controls an alternating current or an alternating voltage, and induction-heats an object to be heated by the magnetic flux generation mechanism,
The impedance of the winding by the alternating current value obtained from the alternating current detection unit for detecting the alternating current flowing through the winding and the alternating voltage value obtained from the alternating voltage detection unit for detecting the alternating voltage applied to the winding. An impedance calculation unit for calculating
A relational data storage unit that stores relational data indicating the relation between the impedance of the winding and the temperature of the object to be heated;
A to-be-heated body temperature calculating section for calculating the temperature of the to-be-heated body from the impedance obtained by the impedance calculating section and the relation data stored in the relation data storage section ;
The heated body has a hollow cylindrical shape,
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
When the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface, which is a surface for calculating the temperature, is θ [° C.], the heated object temperature calculating unit includes the impedance And an induction heating device that calculates the temperature of the temperature calculation surface by correcting the temperature of the object to be heated obtained from the relationship data using a temperature difference θ obtained using the following equation .
θ = kP / [2π / {ln (d ₂ / d ₁ ) / λ}]
Here, d ₁ is the diameter [m] of the heated surface, d ₂ is the diameter [m] of the temperature calculating surface, and λ is an average temperature between the heated surface and the temperature calculating surface. The thermal conductivity [W / m · ° C.], P is the heat flow rate [W / m], and k is a correction coefficient calculated from the actual measurement value. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed is formed on the side peripheral wall of the heated body,
The cross-sectional area between the heated surface and the temperature calculation surface is S [m ² ], and the total cross-sectional area of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], When the distance between the surface to be heated and the temperature calculation surface is t [m], and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated body temperature calculation unit _sets the diameter d _{1 of the} heated surface as d _j1 = d ₁ ± t {1−α (1−S _j / S)}, and sets the diameter d ₂ of the temperature calculated surface to , _d j2 = _{d 2} with _{± t {1-α (1} -S j / S)} is obtained as temperature difference theta, the induction heating apparatus according to claim 1, wherein correcting the temperature of the object to be heated.
In the formula of d _j1 , the ± part is negative when d ₁ > d ₂ , and is positive when d ₁ <d ₂ . On the other hand, in the formula of d _j2 , the ± part is positive when d ₁ > d ₂ , and is negative when d ₁ <d ₂ . An induction heating device that is connected to a winding of a magnetic flux generation mechanism and includes a power supply circuit provided with a control element that controls an alternating current or an alternating voltage, and induction-heats an object to be heated by the magnetic flux generation mechanism,
The impedance of the winding by the alternating current value obtained from the alternating current detection unit for detecting the alternating current flowing through the winding and the alternating voltage value obtained from the alternating voltage detection unit for detecting the alternating voltage applied to the winding. An impedance calculation unit for calculating
A relational data storage unit that stores relational data indicating the relation between the impedance of the winding and the temperature of the object to be heated;
A to-be-heated body temperature calculating section for calculating the temperature of the to-be-heated body from the impedance obtained by the impedance calculating section and the relation data stored in the relation data storage section;
The heated object has a flat plate shape,
The magnetic flux generation mechanism is to induction-heat the object to be heated from one side,
When the temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface, which is a surface for calculating the temperature, is θ [° C.], the heated object temperature calculating unit includes the impedance And an induction heating device that calculates the temperature of the temperature calculation surface by correcting the temperature of the object to be heated obtained from the relationship data using a temperature difference θ obtained using the following equation.
θ = kQ / (λS / t)
Here, t is a distance [m] between the heated surface and the temperature calculating surface, S is a cross-sectional area [m ² ] between the heated surface and the temperature calculating surface, and λ is the above-mentioned It is the thermal conductivity [W / m · ° C.] of the heated body at the average temperature [° C.] between the heated surface and the temperature calculation surface, and Q is the calorific value [W] of the heated surface, k is a correction coefficient calculated from an actual measurement value. An induction heating device that is connected to a winding of a magnetic flux generation mechanism and includes a power supply circuit provided with a control element that controls an alternating current or an alternating voltage, and induction-heats an object to be heated by the magnetic flux generation mechanism,
The impedance of the winding by the alternating current value obtained from the alternating current detection unit for detecting the alternating current flowing through the winding and the alternating voltage value obtained from the alternating voltage detection unit for detecting the alternating voltage applied to the winding. An impedance calculation unit for calculating
A relational data storage unit that stores relational data indicating the relation between the impedance of the winding and the temperature of the object to be heated;
A to-be-heated body temperature calculating section for calculating the temperature of the to-be-heated body from the impedance obtained by the impedance calculating section and the relation data stored in the relation data storage section;
The heated body has a hollow n-square tube shape with a height of h [m] and n side lengths of a ₁ , a ₂ ,... A _n [m], respectively.
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
The temperature difference between the heated surface of the heated object facing the winding and the temperature calculating surface that is a surface for calculating the temperature is θ [° C.], and the heated surface on each side of the heated object and the temperature When the distance between the temperature calculation surfaces is t [m], the heated object temperature calculation unit uses the following equation for the temperature of the heated object obtained from the impedance and the relational data. An induction heating apparatus that calculates the temperature of the temperature calculation surface by correcting using the temperature difference θ obtained in this way.
θ = kQ / λ [{(a ₁ + a ₂ +... + a _n ) h / t} + m _n × n × h]
Here, n is a natural number starting from 1, and λ is the thermal conductivity [W / m · ° C.] of the heated object at an average temperature [° C.] between the heated surface and the temperature calculating surface, Q is the calorific value [W] of the surface to be heated, k is a correction coefficient calculated from actual measurement values, and _mn is a constant at n. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed in the thickness of the heated object is formed,
The cross-sectional area between the heated surface and the temperature calculation surface is S [m ² ], and the total cross-sectional area of the jacket chamber between the heated surface and the temperature calculation surface is S _j [m ² ], When the variable indicating the ratio of the function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated body temperature calculation unit uses the temperature difference θ obtained by setting the distance t between the heated surface and the temperature calculating surface as t _j = αt (S−S _j ) / S, and The induction heating apparatus according to claim 3 or 4, wherein the body temperature is corrected. An induction heating device that is connected to a winding of a magnetic flux generation mechanism and includes a power supply circuit provided with a control element that controls an alternating current or an alternating voltage, and induction-heats an object to be heated by the magnetic flux generation mechanism,
The impedance of the winding by the alternating current value obtained from the alternating current detection unit for detecting the alternating current flowing through the winding and the alternating voltage value obtained from the alternating voltage detection unit for detecting the alternating voltage applied to the winding. An impedance calculation unit for calculating
A relational data storage unit that stores relational data indicating the relation between the impedance of the winding and the temperature of the object to be heated;
A to-be-heated body temperature calculating section for calculating the temperature of the to-be-heated body from the impedance obtained by the impedance calculating section and the relation data stored in the relation data storage section;
The heated body has a hollow n-square tube shape with a height of h [m] and n side lengths of a ₁ , a ₂ ,... A _n [m], respectively.
The magnetic flux generation mechanism is to induction heat the object to be heated from the outer peripheral side or the inner peripheral side,
A temperature difference between the heated surface of the heated body facing the winding of each side wall portion of the heated body and a temperature calculation surface which is a surface for calculating the temperature is θ _n [° C.], and the heated When the distance between the heated surface and the temperature calculation surface of each side wall portion of the body is t ₁ , t ₂ ,... T _n [m], the heated body temperature calculation unit An induction heating apparatus that calculates the temperature of the temperature calculation surface by correcting the temperature of the heated object obtained from the impedance and the relational data using a temperature difference θ _n obtained using the following equation.
_{θ n = k n Q n /} (λ n S n / t n)
Here, t _n is the distance between the heated surface and the temperature calculated surface at the n-th sidewall part [m], S _n is the heated surface and the temperature calculated surface at the n-th sidewall part the cross-sectional area [m ^2] between, lambda _n is n th said at side wall portions of the heated surface and thermal conductivity of the object to be heated at an average temperature [℃] between the temperature calculated surface [W / m a · ° C.], Q _n is the heat value of the heated surface of the n-th sidewall part [W], k _n is a correction coefficient calculated from the measured value. A jacket chamber in which a gas-liquid two-phase heat medium is enclosed in the thickness of the heated object is formed,
Let S _n [m ² ] be the cross-sectional area between the heated surface and the temperature calculation surface in the nth side wall portion, and the jacket chamber between the heated surface and the temperature calculation surface in the nth side wall portion. When the sum of the cross-sectional areas is S _nj [m ² ] and the variable indicating the rate of function deterioration of the jacket chamber due to the pressure drop of the heat medium accompanying the temperature drop is α,
The heated object temperature calculation unit obtains the distance t _n between the heated surface and the temperature calculation surface in the nth side wall part as t _nj = αt _n (S _n −S _nj ) / S _n. The induction heating apparatus according to claim 6 , wherein the temperature of the object to be heated is corrected using a temperature difference θ _n . An impedance correction unit that corrects the impedance obtained by the impedance calculation unit by a power supply voltage value obtained from a power supply voltage detection unit that detects a power supply voltage of the power supply circuit;
The induction heating apparatus according to any one of claims 1 to 7 , wherein the heated object temperature calculating unit calculates the temperature of the heated object from the corrected impedance corrected by the impedance correcting unit and the relation data. The control element controls a conduction angle of an alternating current or an alternating voltage with a semiconductor,
An impedance correction unit that corrects the impedance obtained by the impedance calculation unit based on a conduction angle of the control element;
The induction heating apparatus according to any one of claims 1 to 8 , wherein the heated object temperature calculating unit calculates the temperature of the heated object from the corrected impedance corrected by the impedance correcting unit and the relation data. The induction heating device according to claim 8 or 9 , wherein the impedance correction unit corrects the impedance obtained by the impedance calculation unit by a winding temperature obtained from a temperature detection unit that detects a temperature of the winding. . A DC voltage application unit that controls a DC power supply and intermittently applies a DC voltage to the winding;
A resistance value calculation unit that calculates a resistance value of the winding from a DC voltage applied by the DC voltage application unit and a DC current that flows through the winding when the DC voltage is applied;
The induction heating apparatus according to claim 8 or 9 , wherein the impedance correction unit corrects the impedance obtained by the impedance calculation unit with a resistance value obtained from the resistance value calculation unit. A relational data storage unit for storing relational data indicating a resistance value-temperature relation between the resistance value of the winding and the temperature of the winding;
The induction heating device according to claim 11 , further comprising a winding temperature calculation unit that calculates a temperature of the winding from a resistance value obtained by the resistance value calculation unit and a resistance value-temperature relationship indicated by the relationship data.