TWI566641B - Induction heating device - Google Patents

Description

Induction heating device

The present invention relates to a device for inductively heating an object to be heated using a heating coil represented by an induction heating cooker or an IH (Indirect Heating) electronic pan, and more particularly to a controller of the induction heating device.

Conventionally, such an induction heating device has the following (for example, refer to Patent Document 1), that is, for example, each of two heating coils is connected to an inverter circuit to heat the inverter circuit at a fixed cycle and at an arbitrary ratio. The supply of the high frequency current of the coil is subjected to duty control.

In the induction heating device, in order to make the instantaneous input power values to the two inverter circuits equal, when the input power amounts to the two inverter circuits are equal, the heating time of the two inverter circuits is 1 Take a duty control on the ratio of 1. Further, when the amount of input power to one inverter circuit is larger than the amount of input power to the other inverter circuit, the heating time of an inverter circuit is extended. By the above control operation, the heating power of the two heating coils can be arbitrarily set.

Patent Document 1 discloses that a normal soft start for gradually increasing the electric power supplied to the heating coil to a specific electric power is performed at the start of the heating immediately after the start of heating. Further, in Patent Document 1, it is described that when two heating coils are alternately heated by the duty control, when the heating of one heating coil is stopped and then restarted, the two inversions are prevented by shortening the starting time. The decrease in the average input power when the action of the circuit is switched.

Moreover, it is provided as an induction heating device having a soft start function The invention has the following induction heating device, that is, the heating coil of the inductively heated object is connected in series to the switch mechanism, and the switch mechanism is controlled by the drive control mechanism, and has a plurality of specific values at the start of the switch mechanism, and maintains the time constant The change to the desired power value (for example, refer to Patent Document 2).

The induction heating device disclosed in Patent Document 2 controls the operation of the low-output power at which the power conversion efficiency of the inverter circuit is lowered by controlling the power value at the start of the soft-start function as much as possible in accordance with the characteristics of the load. In the induction heating device disclosed in Patent Document 2, the efficiency of the inverter circuit is improved, the output power at the time of startup is increased, the soft start period is shortened, and the efficiency of the inverter circuit is further improved.

Further, the electronic pot as the conventional induction heating device has a configuration in which the first switching mechanism is connected in series to the first heating coil of the induction heating pot, and the metal plate on the inner surface side of the cover of the induction heating cover pot 2 The heating coil is connected in series to the second switching mechanism. In the electronic pot, there is proposed an electronic pot (for example, refer to Patent Document 3), that is, the first switching mechanism and the second switching mechanism are controlled to be turned on and off by the control unit, and the first switching mechanism is activated. When the minimum on-time is different from that at the start of the second switching mechanism, the on-time at the start is set to the initial value.

Further, as an induction heating device of the prior art, an induction heating cooker that controls the ON time of the switching mechanism based on the ON voltage of the switching mechanism has been proposed (for example, see Patent Document 4).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 5-166579

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-204884

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2005-152306

[Patent Document 4] Japanese Patent Laid-Open No. Hei 11-111440

However, in the above-described conventional induction heating device, in order to shorten the start-up time of the soft start, it is necessary to set the variation width of the drive frequency or the on-off ratio of the switching elements constituting the inverter circuit to be large. In the case where such setting is made, there is a problem that when a load variation occurs when the operation of the inverter circuit is switched, the input power to the inverter circuit after detecting the load fluctuation is lowered or While the input power is stopped, that is, during the period before the switching element changes the drive control state, the input power to the inverter circuit is increased and the control switching element is continuously driven, so that the increase in the input power to the inverter circuit during this period becomes large. .

As a result, in the above-described induction heating device, there is a fear that the operating state of the inverter circuit determined by the constant of the load or the like is shifted, for example, a high voltage is applied to the switching element. The problem of a major accident that destroys the switching element.

Moreover, when the start-up time of the soft start is short, the time for detecting the load change is also shortened, and there is a problem that the load variation cannot be detected with high precision.

Further, when the start-up time of the soft start is shortened, the amount of change ΔW per unit time of the input power to the inverter circuit becomes large. When the amount of change ΔW is large In the final stage of the soft start, it is easy to generate a phenomenon that the input power to the inverter circuit exceeds a fixed value after input to the inverter circuit after the soft start, that is, a fixed value, that is, an overshoot. When the power of the fixed value or more is instantaneously input to the inverter circuit, the voltage applied to the switching element or the current flowing through the switching element instantaneously increases, so that it is necessary to set the specification of the switching element for the inverter circuit. The problem is above a fixed value.

Further, when the input power to the inverter circuit is controlled by changing the driving frequency of the switching element, there is a problem that a change in the driving frequency per unit time occurs when the frequency fluctuation during the soft start is imminent. The sound is Δf, and an induction heating device that produces a harsh sound is provided.

The amount of power input during the driving period of the inverter circuit divided by the period of the operation period including the inverter circuit and the period of the non-operation period is the average input power to the inverter circuit. Therefore, when the ratio of the heating time of the two inverter circuits is fixed, if the soft start control period is long, the ratio of the soft start control period during the driving period of the inverter circuit is increased, and the phase is reversed. The problem of the input power of the circuit deviating from the average power. Further, when the time for one cycle is shortened in order to achieve uniform heating, the ratio of the soft start control period is further increased to make the difference between the input power and the average power larger, and the input power at the time of soft start control cannot be ignored.

Further, in the configuration of the conventional induction device, in order to improve the power conversion efficiency of the inverter circuit, it is necessary to lengthen the conduction time at the time of starting the switching mechanism and shorten the operation period of the soft start.

Therefore, there is a problem in that the switching mechanism is rapidly heated to the start of the switching mechanism. The coil flows an excessive current, and the object to be heated, such as a pot magnetically coupled to the heating coil, induces a current to vibrate violently, causing a problem of "beeping" like a pot.

The problem of generating the above-described abnormal sound can be solved by shortening the on-time of the switching mechanism at the start of the switching mechanism, thereby reducing the current flowing to the heating coil at the time of starting, but falling into the power conversion efficiency of the inverter circuit. Dilemma.

Further, when the on-time of the switching mechanism is shortened and the switching mechanism is turned on while a voltage is applied to the switching mechanism, an excessive current flows through the switching mechanism to generate a large electromagnetic noise, and a switch may occur. The increase in heat caused by the loss of the mechanism causes the switching mechanism to be broken.

The present invention is to solve various problems of the above-mentioned prior art induction heating device, and an object thereof is to provide an induction heating device capable of gradually increasing input power control by ensuring a specific time without shortening the start-up time of the soft start control And preventing the destruction of the switching elements of the sensing circuit or the generation of abnormal sounds, and controlling the average input power during the switching of operations to be preset by grasping the amount of decrease in the average input power when the operations of the two inverter circuits are switched. The value.

In the present invention, there is provided an induction heating device which is configured to form a structure which does not generate an abnormal sound at the time of starting, and which can improve power conversion efficiency and suppress generation of electromagnetic noise.

In order to solve the above problem of the induction heating device, the induction plus of the present invention The thermal device includes: a plurality of heating coils for inductively heating the object to be heated; an inverter circuit for supplying power to the plurality of heating coils; and a control unit for driving and controlling the inverter circuit; and the controlling The unit inductively heats the object to be heated by alternately supplying electric power to the respective heating coils from the inverter circuit; and the control unit is configured to supply electric power to the heating coil when power supply to each of the heating coils is started. Soft start control is performed such that the minimum value set in advance increases to a constant power value, and after the electric power supplied to the heating coil reaches the constant electric power value, the supply of the constant electric power value is maintained until the electric power to the heating coil is maintained. The inverter circuit is controlled so as to end the supply, and is set such that the constant power value is larger than the average power value supplied to the heating coil.

The induction heating device of the present invention configured as described above can compensate the amount of power drop during the soft start control by setting the constant power to be equal to or higher than the average power supplied, thereby setting the average power to the target value. Therefore, the induction heating device of the present invention can prevent the destruction of the switch portion or the generation of abnormal sound without shortening the start-up time of the soft start control, and the amount of decrease in the average input power when switching the operation of the plurality of inverter circuits is grasped. The average value of the input power when the action is switched is the set value.

The induction heating device of the present invention can prevent the destruction of the switching portion of the inverter circuit or the production of abnormal sound by controlling the input power to be gradually increased by ensuring a specific time without shortening the startup time of the soft start control. The average value of the input power at the time of switching the operation can be controlled to a set value by grasping the amount of decrease in the average input power at the time of switching the operation of the plurality of inverter circuits. Further, in the present invention, it is possible to configure such that no abnormal sound is generated at the time of starting, and it is possible to improve power conversion efficiency and suppress generation of electromagnetic noise.

An induction heating device according to a first aspect of the present invention includes: a plurality of heating coils for inductively heating an object to be heated; an inverter circuit for supplying electric power to the plurality of heating coils; and a control unit for driving control thereof In the inverter circuit, the control unit inductively heats the object to be heated by alternately supplying electric power to the respective heating coils from the inverter circuit; and the control unit is configured to start power supply to each of the heating coils. Soft start control is performed such that the electric power supplied to the heating coil is gradually increased from a preset minimum value to a constant electric power value, and the constant electric power value is maintained after the electric power supplied to the heating coil reaches the constant electric power value. The supply is controlled such that the inverter circuit is controlled so that the power supply to the heating coil is completed, and the constant power value is set to be larger than the average power value supplied to the heating coil.

The induction heating device according to the first aspect of the present invention configured as described above can compensate the amount of power drop during the soft start control by setting the constant power so that the constant power value becomes equal to or higher than the supplied average power value. The average power can be set to the target value. Moreover, even if a plurality of heating coils are alternately switched on and off to supply electric power, it can be prevented from being made. An abnormal sound (pot sound) is generated for the pot of the object to be heated, so that an induction heating device that does not cause discomfort to the user can be realized.

An induction heating device according to a second aspect of the present invention is characterized in that the control unit that changes the constant power value by the first aspect of the first aspect controls the average power supplied to the heating coil.

Since the induction heating device according to the second aspect of the present invention configured as described above can control the average electric power, the average electric power can be changed to a desired value. Further, since the induction heating device of the second aspect can supply electric power to each of the heating coils and to control the electric power for one round period, the electric heating is not extended even if the high-speed switching is performed to avoid the temperature fluctuation of the object to be heated. Power control can be performed during this period.

The induction heating device according to the third aspect of the present invention is configured to control the supply to the heating when the power supply during the soft start control is completed by the control unit of the first aspect or the second aspect. The average power of the coil.

The induction heating device according to the third aspect of the present invention constructed as described above can control the average electric power, so that the average electric power can be changed to a desired value. Further, since the induction heating device of the third aspect can control the electric power without changing the constant electric power, it is not necessary to increase the rated electric power of the machine, and the electric power can be supplied by extending the end of the electric power supply.

The induction heating device according to a fourth aspect of the present invention is configured such that the control unit of any one of the first aspect to the third aspect is supplied to the heating coil while being grasped during soft start control. The amount of power, the amount of power supplied to the heating coil during the period of supplying constant power, and the amount of power The operation of supplying electric power to each of the heating coils is performed for one round, and the average electric power supplied to the heating coils is calculated.

The induction heating device according to the fourth aspect of the present invention configured as described above can grasp the average power supplied to the inverter circuit. Therefore, it is possible to calculate how much the power can be changed when the constant power and power supply are completed.

An induction heating device according to a fifth aspect of the present invention is configured to include a current measuring unit that measures a current supplied from a power source to the inverter circuit in the fourth aspect; and a timing unit that measures a time period in which the inverter circuit is in an operating state; and the control unit calculates the power supplied to the inverter circuit based on the output value of the current measuring unit, and grasps the inversion based on the time measured by the timer unit The amount of electric power supplied by the circuit and the operation of supplying electric power to each of the heating coils are performed for one round.

Since the induction heating device according to the fifth aspect of the present invention configured as described above can perform power control by managing time, the operation time can be controlled in the same state even in regions having different frequencies.

An induction heating device according to a sixth aspect of the present invention includes: a current measuring unit that measures a current supplied from the power source to the inverter circuit in the fourth aspect; and a zero-cross detecting unit that detects the voltage of the power source a zero-point point; and a power calculation unit that calculates power supplied to the inverter circuit; and the power calculation unit and the detection signal from the zero-cross detection unit The frequency of the number is synchronously read from the output signal of the current measuring unit, and the zero-cross signal is output to the control unit. The control unit calculates the generation of the zero-crossing signal to the next zero-cross signal generation. The power value and/or the amount of power input to the inverter circuit during the time period is configured.

The induction heating device according to the sixth aspect of the present invention configured as described above can perform power control in units of detection of zero-crossing signals, so that power control can be performed without providing a timing unit.

An induction heating device according to a seventh aspect of the present invention is configured to include a zero-cross detecting unit that detects a point at which a voltage of a power source in the fifth aspect becomes a zero level, and a power calculation unit. Calculating the power supplied to the inverter circuit; and the power calculation unit reads the output signal from the current measuring unit in synchronization with the frequency of the detection signal from the zero-cross detecting unit, and outputs the zero-cross signal The control unit is configured to calculate the power value and/or the amount of power input to the inverter circuit during the period from the generation of the zero-crossing signal to the generation of the next zero-crossing signal. Composition.

According to the seventh aspect of the present invention, the induction heating device can control the time and perform power control. Therefore, the operation time can be controlled in the same state even in regions having different frequencies.

An induction heating device according to an eighth aspect of the present invention is configured as follows: each of the heating coils in any one of the first aspect to the seventh aspect The control unit is arranged in a substantially concentric shape, and the control unit supplies the electric power supplied to the heating coil having a larger diameter to the electric power supplied to the heating coil having a smaller diameter.

The induction heating device according to the eighth aspect of the present invention configured as described above is capable of uniformly heating the object to be heated by the density of electric power supplied from the plurality of heating coils. Further, when the object to be heated is in the shape of a container, the heat of the object to be heated heated by the heating coil on the outer side having a larger diameter is transmitted to the side surface of the container, so that even if it is the same power density, the outside of the object to be heated The temperature is also easy to drop. Therefore, the heat transfer portion can be compensated by making the density of the power supplied from the heating coil on the outer side of the larger diameter to the object to be heated slightly higher than the density of the power supplied from the heating coil from the inner side of the smaller diameter to the object to be heated. Thereby the object to be heated is uniformly heated.

An induction heating device according to a ninth aspect of the present invention is characterized in that the induction heating device of any one of the first aspect to the seventh aspect is a cooking device, and each of the heating coils is disposed substantially concentrically In the circular shape, the control unit changes the ratio of the electric power supplied to the smaller diameter heating coil to the larger diameter heating coil based on the cooking order.

According to the ninth aspect of the invention, the induction heating device of the present invention controls the power supplied to the two heating coils in combination with the cooking content and the cooking scene to uniformly heat and supply a large amount of electric power to a heating coil. The heating is not uniform, and no power is supplied to a heating coil, and the cooking content and the cooking scene are uniquely obtained. Therefore, in the induction heating device of the ninth aspect of the invention, the heating pattern can be sequentially realized at the ratio of the input electric power.

The induction heating device of the tenth aspect of the present invention further comprises: a minimum on-time setting unit that sets a minimum on-time at which a power value supplied to the heating coil becomes a minimum value in a plurality of on-times that can be used in a switching portion of the inverter circuit in the first aspect; an on-time variable a setting unit that sets a variable of an on-time of the plurality of switch sections; a current detecting unit that detects an input current from the power supply; and a current setting unit that sets a value corresponding to a target value of the input current; The control unit sets the minimum on-time set by the minimum on-time setting unit to an initial value of the on-time when the switch unit is activated, and sets the current set value set by the current setting unit after the start-up. In the method of target power, the on-time of the switch unit is varied by a variable of the on-time set by the on-time variable setting unit, and the plurality of on-times that can be used in the switch unit are classified into at least the minimum conduction. The first on-time group on the power supply side with a lower time, and the first on-time group a second on-time group that includes a longer on-time and includes a second on-time group that is a higher power supply side that is an on-time of the target power; and an on-time of the switch unit is turned on from the first on-time group The variable of the on-time when the time is shifted to the on-time included in the second on-time group is set to be larger than the variable of the on-time in the first on-time group and the on-time in the second on-time group. .

According to the tenth aspect of the invention, in the induction heating device of the tenth aspect of the present invention, it is possible to prevent the occurrence of abnormal sound from the object to be heated, and to reduce the supply time by setting the on-time during startup to the minimum on-time during the soft-start control. Further, the on-time after startup is shifted to the on-time included in the second on-time group by the maximum variable, whereby the reduction in power conversion efficiency can be suppressed.

In the induction heating device according to the eleventh aspect of the present invention, the on-time included in the first on-time group in the tenth aspect is set to be only the minimum on-time.

In the induction heating device according to the eleventh aspect of the present invention, which is configured as described above, the control is performed so that the noise is not generated from the object to be heated, and the power conversion efficiency can be maximized.

An induction heating device according to a twelfth aspect of the present invention is configured to operate at least when the voltage is applied to the switch portion by operating at least the minimum on time of the tenth aspect or the eleventh aspect Disconnect control is on.

In the induction heating device according to the twelfth aspect of the invention constructed as described above, the generation of the abnormal sound from the object to be heated can be suppressed to the limit level. This is achieved by the fact that even when the switch unit is activated, the voltage is applied to the switch unit, and the voltage can be applied directly to the switch unit by the use of the maximum variable. The turn-on operation is performed, so that the reduction in power conversion efficiency can be prevented.

An induction heating device according to a thirteenth aspect of the present invention is configured to set a start timing of the switch portion in the vicinity of a zero crossing point of a power source in any of the aspects of the tenth to twelfth aspects.

Inductive heating device of the thirteenth aspect of the invention constructed in the above manner In the meantime, since the amount of change in the power supply value due to the change in the on-time is small, it is possible to reduce the occurrence of flicker in illumination or the like. Further, since the voltage applied to the switch portion is low and the supplied power is small, the damage at the time of switching the on-time is small, and it is also possible to contribute to prevention of breakage of the switch portion.

The novel features of the invention are intended to be limited only by the scope of the appended claims. Good understanding and evaluation.

Hereinafter, as an embodiment of the induction heating device of the present invention, an induction heating device having a heating coil will be described with reference to the drawings. In addition, the induction heating device of the present invention is not limited to the components of the induction heating device described in the following embodiments, and includes technical ideas and technical fields equivalent to the technical ideas described in the following embodiments. Inductive heating device composed of technical common sense.

(Embodiment 1)

1 is a view showing a circuit configuration of an induction heating device according to Embodiment 1 of the present invention, and shows a state in which a high-frequency current is connected from a power source to a circuit of a heating coil via an inverter circuit. Fig. 2 is a timing chart showing input power to an inverter circuit of the induction heating device according to the first embodiment of the present invention, and shows a controller related to power supply to the object to be heated.

In Fig. 1, a commercially available power source 41 is connected to a rectifying circuit 42 as a rectifying unit for converting an alternating current power source into a direct current power source. The rectifier circuit 42 can also be configured to include a diode for converting an alternating current power source into a direct current power source. In addition to the bridge, a circuit for smoothing the rectified power supply output from the diode bridge and a filter for propagating electromagnetic noise generated by the operation of the induction heating device to the power source 41 are included. Inductor or capacitor.

A first inverter circuit 43 and a second inverter circuit 44 are connected to the output terminal of the current circuit 42. Each of the first inverter circuit 43 and the second inverter circuit 44 includes a switching portion including at least one switching element, and the switching portion is turned on and off to form a higher frequency than the power source 41. The frequency. Further, the frequency of the on/off operation of the switch unit is often tens of kHz from the viewpoint of prevention of generation of audible sound and reduction of switching loss due to repeated switching operation of the switch unit.

The first heating coil 45 and the second heating coil 46 for inductively heating the object 48 are connected to the output ends of the first inverter circuit 43 and the second inverter circuit 44, respectively.

The first inverter circuit 43 and the second inverter circuit 44 generate high-frequency currents for the first heating coil 45 and the second heating coil 46, respectively, and generate the first heating coil 45 and the second heating coil 46. High frequency flux. By supplying the high-frequency magnetic flux to the object 48 to be heated disposed in the vicinity of the first heating coil 45 and the second heating coil 46, eddy current is generated in the object 48 to be heated, and based on the eddy current and the object to be heated 48 The object 48 is inductively heated by the inherent resistance.

Control terminals of the switch unit (switching element) included in the first inverter circuit 43 and the second inverter circuit 44 (for example, an IGBT (Insulated Gate Bipolar Transistor) The gate is connected to a control unit 47 for driving the control switch unit. The control unit 47 outputs an on/off signal accompanying the operating frequency and duty ratio of the control to the control terminal. The driver controls the switch unit.

The operation and action of the induction heating device of the first embodiment configured as described above will be described with reference to Fig. 2 .

In FIG. 2, the timing of the upper portion (a) indicates the input power to the first inverter circuit 43, and the timing of the lower portion (b) indicates the input power to the second inverter circuit 44. Here, the input power to the inverter circuits 43 and 44 is subtracted from the switching loss caused by the switching operation of the switch unit included in the inverter circuit, and the heating coils 45 and 46 are represented by the flow. The value obtained by the loss of the conduction loss due to the current of the components of the induction heating device is the supplied electric power supplied to the object 48 to be heated.

However, in general, the heating efficiency of the induction heating device is high, and the switching loss and the conduction loss with respect to the input power to the inverter circuits 43 and 44 are small, so that the input power to the inverter circuits 43 and 44 can be considered. It is substantially the same as the power supplied to the object 48 to be heated.

The first inverter circuit 43 and the second inverter circuit 44 of the first embodiment are alternately input with electric power. Therefore, according to the configuration of the first embodiment, since it is not necessary to simultaneously input electric power to the first inverter circuit 43 and the second inverter circuit 44, the first inverter circuit 43 and the second inverter circuit 44 can be prevented. The occurrence of a booming noise caused by a difference in the operating frequency provides an induction heating device that does not cause discomfort to the user.

Further, in the input power to the first inverter circuit 43 and the input power to the second inverter circuit 44, the maximum input power (constant power) of each other does not overlap in the same period of time, and thus the induction heating device is Input power, that is, input power to the first inverter circuit 43 and input to the second inverter circuit 44 The sum of the electric powers does not exceed the constant electric power in the case where only one of the first inverter circuit 43 or the second inverter circuit 44 operates.

Therefore, the induction heating device of the first embodiment has a configuration in which it is not necessary to set the rated electric power of the induction heating device to be higher than the constant electric power, and the electric heating device 41 having a small electric power capacity can operate the induction heating device.

The first inverter circuit 43 or the second inverter circuit 44 of the induction heating device according to the first embodiment is controlled by the first inverter circuit 43 as shown in the area A and the region D of FIG. When power supply to each of the heating coil 45) or the second inverter circuit 44 (second heating coil 46) is started, the minimum value (minimum) of the power supplied to each of the inverter circuits 43, 44 is set. Power) is gradually increased to a soft start control of a specific value (constant power). Here, the minimum value of the power supplied to the inverter circuits 43, 44 is at least less than a value of 1/2 of the constant power value.

In general, when a state in which power is not input to the inverter circuit is shifted to a state of input power, a large current instantaneously flows through the inverter circuit by the action of charging or the like of the components of the inverter circuit. Inrush current. In the induction heating device of the first embodiment, the soft start control is performed as described above, and the input power to the inverter circuits 43 and 44 at the start of the start of the power supply is reduced, whereby the inrush current can be made small. Therefore, the destruction of the inverter circuits 43 and 44 due to the inrush current and the generation of noise can be suppressed, and the inverter circuits 43 and 44 can be safely operated.

Further, when a large inrush current is generated, the heating coil rapidly generates a strong magnetic flux and magnetically couples with the object to be heated, thereby causing the object to be heated to vibrate to generate an abnormal sound such as a pot sound. Therefore, the induction heating device of the first embodiment In the soft start control as described above, the input power to the inverter circuit at the start of the power supply can be reduced, and the abnormal sound such as the pot sound can be reduced.

Further, in the induction heating device according to the first embodiment, it is possible to determine whether or not the first heating coil 45 and the first heating coil are disposed in a soft start control period in which the power supplied to the inverter circuit is gradually increased from a preset minimum value. 2 The heating coil 46 performs induction heating of the object 48 to be heated. If it is determined that the unheated object 48 is disposed, the input power to the inverter circuits 43 and 44 is stopped before the input power to the inverter circuits 43 and 44 reaches the constant power, thereby preventing the reverse The destruction of the phase circuit circuits 43, 44 allows the inverter circuits 43, 44 to operate stably.

As shown in FIG. 2(a), in the first inverter circuit 43, after the soft start control, when the input power to the first inverter circuit 43 reaches the first constant power PS1, the area A is directed to the area B. The transition is to drive and control the first inverter circuit 43 so that the first constant power PS1 is maintained for a specific period. On the other hand, as shown in FIG. 2(b), when the input power to the second inverter circuit 44 reaches the second constant power PS2, the second inverter circuit 44 shifts from the region D to the region E. The second inverter circuit 44 is driven and controlled to maintain the second constant power PS2 for a specific period.

After the first constant power PS1 is input to the first inverter circuit 43 in the region B as the constant power input period, the first inverter circuit 43 is stopped, thereby shifting to the region C which is the period of the down time. In the same manner, after the second constant power PS2 is input to the second inverter circuit 44 in the region E which is the constant power input period, the second inverter circuit 44 is stopped, thereby Area F transfer during the period of downtime.

When the input power to the first inverter circuit 43 is overlapped with the input timing of the input power to the second inverter circuit 44, the first inverter circuit 43 and the second inverter may be formed. The generation of the audible sound caused by the difference in the operating frequency of the inverter circuit 44 and the induced voltage generated by the magnetic field interference are generated in the components of the induction heating device, thereby damaging the induction heating device. Therefore, in order to prevent the damage caused by such a cause, in the induction heating device of the first embodiment, the region C and the region F which are the periods of the down time are set, and the operation of the two inverter circuits 43 and 44 is stopped. period. Further, if the design can be designed without causing damage to the induction heating device, it is not necessary to provide the regions C and F as described above.

In the induction heating device of the first embodiment, the operation from the region A to the region F as shown in FIG. 2 is set to one cycle, and the heating of the object 48 is supplied by repeating the operations. The first average power PA1 of the input power to the first inverter circuit 43, that is, the first average power PA1 supplied from the first heating coil 45 to the object 48 to be heated, is in the area A as the soft start control period. The sum of the amount of input power to the first inverter circuit 43 and the amount of input power to the first inverter circuit 43 as the region B of the constant power input period is divided by the period from the region A to the region F, that is, the period T And the winner.

Similarly, the second average power PA2 supplied from the second heating coil 46 to the object 48 to be heated is the amount of input power to the second inverter circuit 44 in the region D which is the soft start control period. The sum of the input power amounts of the region E of the power input period to the second inverter circuit 44 is divided by the period T from the region A to the region F.

When the object to be heated 48 that supplies electric power from the first heating coil 45 and the object to be heated 48 that supplies electric power from the second heating coil 46 are the same object 48 to be heated, the first average power PA1 and the second average power PA2 are The sum is supplied to the total power of the object 48 to be heated. In addition, when the object to be heated 48 that supplies electric power from the first heating coil 45 and the object to be heated 48 that supplies electric power from the second heating coil 46 are different heating objects 48 and 48, the first average electric power PA1 and the first 2 The average electric power PA2 is supplied to each of the objects to be heated.

In the case of the heating device, the amount of temperature change of the object to be heated and the amount of temperature change or evaporation of the contents of the container as the object to be heated are determined by the average power supplied to the object to be heated. Therefore, in the induction heating device of the first embodiment in which the heating coil for supplying input electric power is alternately switched, it is necessary to control the first average electric power PA1 and the second average electric power PA2.

As the period of the period T becomes longer, the time during which electric power is supplied from the heating coil to the object to be heated becomes longer, whereas the time during which electric power is not supplied from the other heating coil to the object to be heated becomes longer. Therefore, when power is supplied, the temperature difference of the object to be heated in the vicinity of each heating coil when power is not supplied becomes large. Therefore, in order to uniformly heat the temperature difference of the object to be heated, it is preferable to shorten the period T as much as possible.

The region C and the region F, which are the rest periods of the operation of the two inverter circuits 43, 44, are extremely short compared to the other regions. Therefore, in order to shorten the period T, it is necessary to perform either the shortening of the soft start control period of the area A or the area D and the shortening of the constant power input period of the area B or the area E.

When the first constant power PS1 and the second constant power PS2 are not changed, in order to shorten the area A and the area D which are the soft start control periods, To input constant power to the inverter circuits 43, 44, it is necessary to set the variation width of the drive frequency and/or the on-off ratio of the switching sections constituting the inverter circuits 43, 44 to be large. In the case of such setting, it is judged whether or not the time period in which the object 48 is suitable for the induction heating device is shortened during the soft start control period in which the electric power supplied to the inverter circuits 43 and 44 is gradually increased from the minimum value. Therefore, it is difficult to make a correct judgment.

Further, since the range of change in the driving frequency and/or the on-off ratio of the switch unit is large, when the unsuitable object 48 is placed, the action region in which the inverter circuits 43 and 44 are broken is instantaneously reached, so that it is difficult to reverse The phase circuit circuits 43, 44 operate stably.

Further, when the input power to the converter circuit is controlled by changing the drive frequency of the switch unit, if the frequency fluctuation during the soft start control period is imminent, the amount of change Δf per unit time of the drive frequency may occur. And the abnormal sound caused by the pot sound.

From the above viewpoints, it is not expected to increase the range of change in the drive frequency or the on-off ratio of the switch unit to shorten the area A and the area D which are the soft start control periods.

Therefore, it is preferable to shorten the period T by shortening the constant power input period of the region B or the region E. However, when the constant power input period is shortened, there are problems in that the area where the power supply of the area A and the area D is insufficient, and the area where the power is not supplied to the area C and the area F which are the periods of the downtime are in the period T. The proportion of the first average power PA1 or the second average power PA2 is further reduced as compared with the first constant power PS1 or the second constant power PS2.

For example, when the first heating coil 45 and the second heating coil 46 supply electric power to the same object 48, and the first constant power PS1 and the second constant power PS2 have the same electric power, if the constant electric power is input to the region B or the region E, When the period is too long with respect to the other regions, it can be considered that the electric power supplied to the object 48 to be heated is substantially the same as the first average electric power PA1 (the second average electric power PA2). However, in the configuration of the induction heating device of the first embodiment in which it is necessary to shorten the constant power input period of the region B and the region E (the time of the region B is not too long with respect to the region A), the first to be supplied to the object 48 to be heated The average power PA1 and the second average power PA2 are controlled to be suitable for the heating state, and it is necessary to control the first average power PA1 or the second average power PA2 as a value different from the first constant power PS1 or the second constant power PS2. .

Therefore, in the induction heating device of the first embodiment, the first constant power PS1 and the second constant power PS2 are set so as to exceed the first average power PA1 and the second average power PA2, thereby uniformly heating the object to be heated. 48, the period T is shortened, and the first average power PA1 and the second average power PA2 can be controlled to a necessary power value.

In addition, according to the results of the experiment by the inventors, if the ratio of the period of the region B to the region A is substantially the same number of bits (10 times or less), the difference between the constant power and the average power becomes large, and the use becomes The level of adverse effects of the inconvenience of the induction heating device is felt. Further, the ratio of the period of the period B to the period of the area A is substantially the same number of bits. When the period of the down time of the area C and the area F is set to zero, the period of the area C or the area F is set longer. , the ratio of the period of the region B to the period of the region A is not the same number of bits, even if it is more than 10 times At the time, the difference between the constant power and the average power is also large, and it becomes a level at which the user feels that the ease of use of the induction heating device is poor.

Further, in the induction heating device of the first embodiment, the configuration in which the constant electric power as a constant value is continuously input to the inverter circuits 43, 44 in the region B and the region E as the constant power input period will be described. However, the present invention is not The power of the input inverter circuits 43 and 44 may be limited to the power of the region B and the region E. In short, if the constant electric power equal to or higher than the target average electric power is input to the inverter circuits 43 and 44 in the fixed period of the region B and the region E, the effect of the invention can be obtained.

(Embodiment 2)

Fig. 3 is a timing chart showing the input power to the inverter circuit of the induction heating device according to the second embodiment of the present invention, and shows a control method relating to the supply of electric power to the object to be heated. In the induction heating device of the second embodiment, the method of controlling the input power to the inverter circuit of the induction heating device of the first embodiment is specifically shown. In the description of the second embodiment, the same functions, configurations, and symbols as those of the induction heating device according to the first embodiment are denoted by the same reference numerals, and the description of the first embodiment will be described.

Fig. 3 is a diagram showing the average electric power (PA3) and the electric power input to the first inverter circuit 43 in the induction heating device that supplies electric power to the object to be heated by the control method shown in Fig. 2 in the first embodiment. The control method of the case where the average power (PA4) of the input power of the inverter circuit 44 is further increased.

As shown in Fig. 3, in the induction heating device of the second embodiment, the rate of change in electric power during the soft start control (rate of change of the input power per unit time) is The power change rate during the soft start control period of the first embodiment is the same as that without change. Therefore, in the induction heating device of the second embodiment, the slope of the input power of the soft start control period (area A, D) of Fig. 3 indicating the power change rate is the same as that shown in Fig. 2 . However, in the induction heating device of the second embodiment, the constant power (PS3, PS4) input to the first inverter circuit 43 and the second inverter circuit 44 during the constant power input period (area B, E) is increased.

As shown in FIG. 3, the input power to the first inverter circuit 43 in the constant power input period (area B) is the third constant power PS3 larger than the first constant power PS1 of the first embodiment. Further, the input power to the second inverter circuit 44 in the constant power input period (region E) is the fourth constant power PS4 larger than the second constant power PS2 of the first embodiment.

As described above, in the second embodiment, the third constant power PS3 and the fourth constant power PS4 are set larger than the first constant power PS1 and the second constant power PS2, respectively, and the area A and the area D are soft. The startup control period becomes longer. Further, since the period T of the region A to the region F is the same as the period T of the first embodiment, the constant power input period of the region B and the region E is shortened.

By using the control method of the second embodiment, the amount of electric power input to the first inverter circuit 43 and the second period of the period D and the region E in the two periods of the area A and the area B are reversed to the second. The amount of power input by the circuit 44 is increased. Therefore, the third average power PA3 and the fourth average power PA4, which are obtained by dividing the same period T as the period T shown in FIG. 2, also increase. On the other hand, in the control method of the second embodiment, by supplying constant power smaller than the first constant power PS1 and the second constant power PS2, the average power supplied to the inverter circuits 43 and 44 can be reduced. Therefore, in the control method of the second embodiment, by controlling Constant power is supplied to control the power supplied to the object to be heated.

In the control method according to the second embodiment, even when the period T is shortened by reducing the temperature difference of the object to be heated and uniformly heating the object to be heated, the constant power of the input power to the inverter circuit is set. Larger, the average power can be increased. Therefore, by using the control method of the second embodiment, the object to be heated can be uniformly heated by the different average electric power.

(Embodiment 3)

Fig. 4 is a timing chart showing input power to an inverter circuit of the induction heating device according to Embodiment 3 of the present invention, and shows a controller related to power supply to the object to be heated. The induction heating device of the third embodiment is different from the method of controlling the input power to the inverter circuit of the induction heating device of the second embodiment. In the description of the third embodiment, the same functions, configurations, and symbols as those of the induction heating devices of the first embodiment and the second embodiment are denoted by the same reference numerals, and the descriptions of the first embodiment and the second embodiment will be described. .

Fig. 4 is a diagram showing the average electric power PA3 and the second electric power of the electric power input to the first inverter circuit 43 in the induction heating device of the third embodiment, in which the electric power is supplied to the object to be heated by the control method shown in Fig. 2; The method of controlling the case where the average power PA4 of the input power of the phase circuit 44 is further increased.

As shown in FIG. 4, in the induction heating device of the third embodiment, the conditions of the power change rate during the soft start control and the constant powers PS1 and PS2 of the input power to the inverter circuits 43 and 44 are as shown in FIG. Since the conditional album of the first embodiment is not changed, the soft start control period of the area A or the area D is the same. However, the input power to each of the inverter circuits 43, 44 maintains a constant power. The constant power input period of the area B and the area E is longer than the period shown in FIG. Along with this, the period T from the region A to the region F is also longer than the period T shown in FIG. 2.

As a result, the ratio of the constant power input period of the area B and the area E in the period T1 increases, and the third average power PA3 and the fourth average power PA4 shown in FIG. 4 are also higher than the first average power shown in FIG. PA1 and the second average power PA2 increase.

In other words, even if the constant power of the input power to the inverter circuit, which is the constant power of the induction heating device, is maintained at a fixed value, the period T1 can be set longer to increase the supply to the object to be heated. Electricity.

On the contrary, by shortening the period of the period from the region A to the region F, that is, shortening the region B to the region E as the constant power input period, the average power supplied to the inverter circuit can be reduced. Therefore, in the control method of the induction heating device of the third embodiment, the electric power supplied to the object to be heated can be controlled to a desired state by the control cycle.

Furthermore, the difference is that the control method of the second embodiment controls the constant power, and the control method of the third embodiment controls the cycle, but both are methods for finally controlling the average power. Therefore, it is also possible to construct a control method for controlling the average power by combining the control methods of the second embodiment and the third embodiment and separately using two variables of constant power and period.

(Embodiment 4)

Fig. 5 is a view showing a circuit configuration of an induction heating device according to a fourth embodiment of the present invention, and shows a state of connection from a power source to a circuit for supplying a high-frequency current to a heating coil via an inverter circuit. Induction 4 of Embodiment 4 In the thermal device, the measuring unit, which is a measuring unit for the current flowing from the power source into the inverter circuit, and the timing unit, which is a timing unit for measuring the operating time of each operating mode (operating state) of the inverter circuit, The configurations of the first embodiment to the third embodiment are different. In the description of the fourth embodiment, the functions, configurations, and exemplifications of the elements of the induction heating device of the first embodiment to the third embodiment are denoted by the same reference numerals, and the description of the first embodiment to the third embodiment will be described.

As shown in Fig. 5, in the induction heating device of the fourth embodiment, current measurement is performed as a current measuring means for measuring the current flowing from the commercial power source 41 to the first inverter circuit 43 and the second inverter circuit 44. Department 49. As the current measuring unit 49, for example, a current transformer (CT) that generates a reverse voltage with a current value flowing therethrough can be used.

In the induction heating device of the fourth embodiment, the two inverter circuits 43 and 44 are controlled, but the power source 41 is shared, and the two inverter circuits 43 and 44 are alternately supplied with electric power from the power source 41. Therefore, one input current measuring unit can be provided on the input side of the rectifier circuit 42, and the current flowing through each of the inverter circuits 43, 44 can be measured.

The output signal formed by the current measuring unit 49 is input to the control unit 47, and the control unit 47 grasps the value of the input power to the inverter circuits 43 and 44 that are operating, and based on the value of the input power, The phaser circuits 43, 44 output the next control signal, thereby controlling the input power to the inverter circuits 43, 44. Here, since the voltage of the commercial power source 41 is substantially constant, the input current can be grasped by the current measuring unit 49, and the input power to the inverter circuits 43 and 44 can be grasped.

In the induction heating device of the fourth embodiment, for example, in the case of the control method shown in Fig. 2, the soft start control period of the soft start control region A and the region D, and the constant supply of the constant power region B and the region E are constant. The difference between the power input periods is not large, so the ratio of the input power amount of the area A to the total amount of the input power to the first inverter circuit 43 and the input power amount of the area D are the second inversion. The ratio of the total amount of input power of the circuit 44 is high, and the input power to the inverter circuits 43 and 44 during the soft start control cannot be ignored in terms of grasping the first average power PA1 and the second average power PA2. the amount.

Therefore, in the induction heating device of the fourth embodiment, the time of the area A and the area D is measured by the timer unit 50, whereby the input power to the inverter circuits 43 and 44 during the soft start control period can be grasped to supply The average electric power to the object to be heated 48 is controlled so as to be a value set in an operation unit (not shown) or a predetermined value in the sequence.

Next, a method of controlling the average electric power of the induction heating device of the fourth embodiment will be described.

The current measuring unit 49 measures the current value flowing from the power source 41 to the first inverter circuit 43 when the first inverter circuit 43 performs the soft start control (the area A in FIG. 2), and the signal based on the measured current value is used. It is input to the control unit 47.

The control unit 47 controls the first inverter circuit 43 such that the first constant power PS1 becomes a current value that flows when the first inverter circuit 43 is input. The control unit 47 can grasp the ratio of the area A in the period T by inputting the time of the area A measured by the timer unit 50.

As shown in FIG. 3, the constant power is controlled without changing from the period T shown in FIG. In other cases, in order to increase the first average power PA1 of the input power to the first inverter circuit 43 to the third average power PA3, it is necessary to increase the first constant power PS1 to the third constant power PS3.

When the period of the region A and the region B in the period T defined by the relationship between the input power to the first inverter circuit 43 and the input power to the second inverter circuit 44 is fixed to be fixed, The ratio of the area A and the area B with respect to the period T is grasped by measuring the time of the area A. Further, by grasping the input power of the area A, the third constant power PS3 whose average power value becomes the set value can be obtained. Therefore, the power can be set to be lower at the start of the start of heating, and the power can be made close to The control of the constant power of the average power set in the final stage of the soft start control period is obtained, thereby providing an induction heating device that supplies the set average power.

In the case where the object to be heated such as the pot of the electronic pot is fixed, for example, if the electric power at the start of the heating is set to be close to the value of the third constant electric power PS3 which is the average electric power value of the set value, The loss of time for the average power to gradually approach the set value can be shortened.

Further, as long as the constant electric power of the object to be heated 48 that has been heated for one time is stored, the constant electric power stored in the subsequent control can be directly set as the target value, thereby providing a usable ease of use. Induction heating device.

Further, when the object to be heated 48 is fixed and the operation time of the inverter circuit is determined in advance, the power supplied during the soft start control period can be calculated, and the average circuit and constant power to be input to the inverter circuit can be derived. Relationship, so constant power can be set according to the average power input to the inverter circuit force. Further, the average power input to the inverter circuit can be controlled so that the time at which the addition of the region A and the region B becomes the operation time of the inverter circuit is stopped. The expected value.

Further, in the induction heating device of the fourth embodiment, the two inverter circuits are controlled. However, since the power source 41 is shared and alternately supplied with electric power, it is possible to measure the input power by one current measuring unit and reflect it in the control.

(Embodiment 5)

Fig. 6 is a view showing a circuit configuration of an induction heating device according to a fifth embodiment of the present invention, and showing a state in which a circuit for supplying a high-frequency current to a heating coil from a power source via an inverter circuit is connected. In the induction heating device of the fifth embodiment, the zero-cross detecting unit that detects that the power source voltage is zero level, and the power calculating unit that is the power calculating unit that grasps the power of each moment of the power input induction heating device On the other hand, it is different from the configurations of the first to fourth embodiments described above. In the description of the fifth embodiment, the functions, configurations, and symbols that are the same as those of the induction heating devices of the first to fourth embodiments are denoted by the same reference numerals, and the descriptions thereof refer to the first to fourth embodiments. Description.

As shown in Fig. 6, the induction heating device of the fifth embodiment is provided with a current measuring unit 49 for measuring the current flowing through the inverter circuit 43 and the second inverter circuit 44. As the current measuring unit 49, for example, a current transformer (CT) having a configuration in which a reverse voltage is generated by a current flowing therethrough can be used. The current output signal formed based on the current value measured by the current measuring unit 49 is input to the power calculating unit 52, whereby the power calculating unit 52 grasps the input to each of the inverter circuits 43 and 44. Into electricity.

The control unit 47 that inputs the signal from the power calculation unit 52 controls the input power to the inverter circuits 43 and 44 by outputting the next control signal to the inverter circuits 43 and 44 that are operating. Here, since the voltage of the commercial power source 41 is substantially constant, the input current to the inverter circuits 43 and 44 can be grasped by the current measuring unit 49 measuring the input current.

In the induction heating device of the fifth embodiment, for example, in the case of the control method shown in Fig. 2, the soft start control period of the soft start control region A and the region D, and the constant supply of the constant power region B and the region E are constant. The difference between the power input periods is not large, so the ratio of the input power amount of the area A to the total amount of the input power to the first inverter circuit 43 and the input power amount of the area D are the second inversion. The ratio of the total amount of input power of the circuit 44 is relatively high, and the input power to the inverter circuits 43 and 44 during the soft start control cannot be ignored in terms of grasping the first average power PA1 and the second average power PA2. .

Therefore, in the induction heating device of the fifth embodiment, by measuring the time of the area A and the area D by the timer unit 50, the input power to the inverter circuits 43 and 44 during the soft start control period can be grasped and supplied to the The average electric power of the heating material 48 is controlled so as to be a value set in an operation unit (not shown) or a predetermined value in the sequence.

Next, a method of controlling the average electric power of the induction heating device of the fifth embodiment will be described.

When the first inverter circuit 43 performs soft start control (area A in FIG. 2), the current measuring unit 49 measures the flow from the power source 41 to the first inverter circuit 43 at all times. The current value is output to the control unit 47 based on the measured current value.

In the induction heating device of the fifth embodiment, the output signal of the zero-cross detecting unit 51 generated when the AC power source 41 and the zero-level intersection are used as the minimum unit of the trigger, and the power calculating unit 52 detects the zero crossing. The signal output from the current measuring unit 49 is synchronized with the output signal of the detecting unit 51 at a timing at which the AC voltage is not zero. The power calculation unit 52 calculates the electric power input to the inverter circuits 43 and 44 during the period of the zero cross signal based on the detected value. In general, even during the soft start control period, the control signal is not changed during the period from the zero crossing point to the next zero crossing point (half-wave period), so that the current measuring unit 49 is only used at one place during the half-wave period. The power is calculated by detecting the output signal.

In the induction heating device of the fifth embodiment, the calculation of the electric power is repeated as described above until the input electric power to the inverter circuits 43 and 44 becomes a fixed value, and the electric power amounts calculated by adding the electric power are calculated. The amount of power input to the inverter circuits 43, 44 during the soft start control period.

In the case where the power control does not change the constant power as in the case of the third embodiment, as shown in FIG. 4, in order to increase the average power input to the first inverter circuit 43, it is necessary to extend the first constant power PS1 to be inverted. The time of the region B in which the circuit 43 operates.

Since the input power amount of the region B to the first inverter circuit 43 is the input power during the constant power input period, it can be easily calculated. Further, the power supplied from the region C to the region F to the first inverter circuit 43 is zero. Therefore, by grasping the amount of power of the area A in which the input power changes every moment, so that The length of the constant power input period of the region B is calculated in such a manner that the average power becomes the set value.

Furthermore, in the fifth embodiment, by calculating the zero-crossing signal, the power control can be performed in accordance with the ratio of the number of zero crossings included in the period T1 to the number of zero crossings included in the area A and the area B. Therefore, even if the timekeeping unit 50, which is the timekeeping mechanism described in the fourth embodiment, is not provided, the power control can be performed. However, by using the timekeeping unit 50 for power control, more precise control can be performed.

Further, as long as the object to be heated 48 is fixed and constant electric power is determined in advance, the amount of electric power supplied during the soft start control period can be calculated, and the average electric power to be input to the inverter circuit and the operating time of the inverter circuit can be derived. With this relationship, the operating time of the inverter circuit can be set by the average power to be input to the inverter circuit. Further, by controlling the method of stopping the inverter circuit at the time when the addition time of the region A and the region B becomes the operation time of the inverter circuit, the average power input to the inverter circuit can be set to The expected value.

Further, in the induction heating device of the fifth embodiment, the calculation of the electric power is synchronized with the output signal of the zero-cross detecting unit 51, so that the zero-crossing period becomes the minimum calculation unit. For example, the zero-cross detecting unit 51 can also be used. The power calculation is performed every time the signal is changed twice, and the minimum calculation unit is not limited to the zero-crossing period using the zero-cross detecting unit 51 of the fifth embodiment.

(Embodiment 6)

Figure 7 is a layout view of a heating coil of an induction heating device according to a sixth embodiment of the present invention. The induction heating device according to the sixth embodiment is specifically described in the first embodiment to the fifth embodiment in terms of the arrangement of the plurality of heating coils. with. In the description of the sixth embodiment, the functions, configurations, and exemplifications of the elements of the induction heating device according to the first to fifth embodiments are denoted by the same reference numerals, and the description of the first embodiment to the fifth embodiment will be described. .

As shown in Fig. 7, in the induction heating device of the sixth embodiment, the first heating coil 45 and the second heating coil 46 are arranged substantially concentrically. The first heating coil 45 has a small diameter and is disposed inside, and the second heating coil 46 has a larger diameter than the first heating coil 45 and is disposed outside.

In the induction heating device of the sixth embodiment, an induction heating cooker is used as the induction heating device, and a pan as the object 48 to be heated or a pan as the object to be heated 48 in the induction cooker is placed in the induction heating. Most of the heating on the cooker is round. Therefore, as shown in Fig. 7, a plurality of heating coils are arranged concentrically, whereby the entire bottom surface of the pot or pot as the object 48 to be heated can be efficiently heated.

Further, in the induction heating device, when the diameter of the heating coil is small, the distance between the center side portion of the heating coil and the outer peripheral side portion is relatively short, so that the magnetic fluxes of the heating coil are likely to cancel each other. Therefore, for a heating coil having the same level of coil thickness, coil density, and combined diameter as the larger diameter heating coil, even if the same current as the larger diameter heating coil flows, the smaller diameter coil is used. The electric power per unit area supplied to the object to be heated is also small.

Therefore, in the case where the object 48 to be heated is uniformly heated, it is necessary that the inner heating coil flows a current larger than the current flowing through the outer heating coil. In the arrangement diagram of the heating coils 45, 46 shown in Fig. 7, the second heating line on the outer side The area of the ring 46 is larger than the area of the inner first heating coil 45. Therefore, from the viewpoint of performing uniform heating, the ratio of the input power to the inverter circuits 43 and 44 connected to the two heating coils 45 and 46 is substantially proportional to the plan view area of the heating coil, and thus to the inverter circuit. Among the input powers of 43 and 44, the average input power to the second inverter circuit 44 connected to the outer second heating coil 46 is large.

In the induction heating device of the sixth embodiment, since the electric power values supplied to the respective heating coils 45 and 46 are alternately switched, the constant electric power of the outer second heating coil 46 is made larger than the constant electric power of the inner first heating coil 45. The object 48 to be heated can be uniformly heated. And/or the induction heating device according to the sixth embodiment, the constant power input period in which the constant electric power input period of the constant electric power is supplied to the outer second heating coil 46 is longer than the constant electric power input to the first electric heating coil 45 on the inner side. During the period, the object 48 to be heated can be uniformly heated.

Further, according to the control method of the sixth embodiment of the present invention in which the electric power supplied to each of the heating coils 45 and 46 is alternately switched, in order to achieve uniform heating of the object 48, it is necessary to advance the switching period to reduce the number of the heating coil. The range of variation in temperature of the heater 48. In particular, when the content of the pot or the like as the object 48 to be heated is in a boiling state, when the switching cycle is delayed, the rise of the bubble generated at the time of boiling is generated only during heating, and the bubble rises intermittently. It is considered that the user feels uncomfortable during cooking or has an influence on cooking performance.

According to the results of the experiments by the inventors, it is confirmed that the period of the electric power supplied to the heating coils 45 and 46 is alternately switched, and if it is not more than 4 seconds, Users will obviously feel the difference in boiling feeling. Moreover, according to the results of the experiments by the inventors, it is understood that the period in which the user feels that there is no discomfort is desired, and it is preferable that the period is equal to or less than 2 seconds.

In the induction heating device of the sixth embodiment, the input power during the soft start control is added, and the average power is calculated and reflected in the control of the inverter circuit. Therefore, it is frequently switched even when switching a plurality of inverter circuits at high speed. When the soft start control is performed, the configuration of the set average power can be correctly supplied.

Further, since the induction heating device of the sixth embodiment can arbitrarily adjust the electric power of the first heating coil 45 disposed inside and the second heating coil 46 disposed outside, it is not limited to uniform heating of the object 48 to be heated. The electric power supplied to the first heating coil 45 disposed inside is increased, or vice versa, and the electric power supplied to the second heating coil 46 disposed outside is increased.

Further, in the induction heating device of the sixth embodiment, the inverter circuit connected to one heating coil is stopped, and only the first heating coil 45 disposed inside or the second heating coil disposed outside only 46 The composition of electricity supply.

As described above, in the induction heating device of the sixth embodiment, it is possible to form an arbitrary heating pattern and reliably supply electric power suitable for the heating state represented by various cooking scenes.

In the above embodiments of the present invention, the method of controlling the constant power is described as a method of controlling the input power to the inverter circuit. However, the rated power is specified in the electric device, and even if it is instantaneous power, it is not suitable. Exceeds rated power.

Therefore, in the induction heating device of the present invention, even when the constant electric power is increased to the rated electric power and the desired average electric power cannot be obtained, the electric power can be controlled by combining the two control methods of the extended period T.

In the first to sixth embodiments of the present invention, the region C and the region F are also provided so that the input power to the first inverter circuit 43 does not overlap with the input power to the second inverter circuit 44. Control is performed, but if the inverter circuit is not broken and the inverter circuits are driven at the same frequency to prevent the occurrence of the roaring noise, the simultaneous input to the plurality of inverter circuits may be performed. Control method of electricity.

Further, in the above-described first to sixth embodiments of the present invention, independent inverter circuits are connected to the respective heating coils, but it is necessary to adjust the power supplied to the plurality of heating coils by one inverter circuit. The phaser circuit configuration eliminates the need to individually connect separate inverter circuits to the individual heating coils.

Further, in the first to sixth embodiments of the present invention, the state in which the region B and the region E from which the constant power is maintained is shifted to the region C and the region F where the input power to the inverter circuit is stopped is described. However, when the power input to the heating coil is extremely small, there is a case where the power supply to the heating coil is stopped before the input power reaches the value of the constant power, that is, the control mode is started immediately after the area A.

However, if the induction heating device of the present invention can control the input power or time during the soft start control, the input power can be surely grasped even when the control mode of the region C is started immediately after the region A. The average power can be controlled to the desired set value.

Further, in the above-described first to sixth embodiments of the present invention, the same is true. Although the power change rate during the soft start control is described as follows, the power change rate may be adjusted as long as it is configured to be able to reliably prevent the occurrence of sound when abnormal sound such as a pot sound is generated. .

Further, in the first to sixth embodiments of the present invention, the case where two heating coils are used will be described. However, even when three or more heating coils are used, it is possible to switch by the same method. The desired average power is supplied to the object 48 to be heated.

In the induction heating device of the present invention, since the constant value is set to a value exceeding the electric power supply value to be supplied to the object to be heated, it is possible to compensate the electric power drop during the soft start control by supplying electric power of a fixed value exceeding the set value. The power supply during the soft start control is controlled such that the average power supplied to the object to be heated becomes a set value. Further, in the induction heating device of the present invention, even when the electric power is alternately supplied to the plurality of heating coils, the electric power at the time of the soft start control generated at the time of the operation switching can be reduced by the supply exceeding the set value. The power of the value is supplemented by the power reduction at the time of soft start control so that the average power supplied to the object to be heated becomes a set value.

Further, by using the power control method of the induction heating device of the present invention, the desired average electric power can be supplied to the object to be heated, and the object to be heated can be uniformly heated, and electric power can be alternately supplied to the plurality of heating coils. In this case, the object to be heated may be unevenly heated by increasing the ratio of the power supplied to a heating coil.

As described above, in the above-described first to sixth embodiments of the present invention, a plurality of heating coils are alternately supplied with electric power, and three characteristics can be realized: the desired average electric power is supplied to the object to be heated; and the heating is uniformly performed. heating And increasing the ratio of the power supplied to a heating coil without uniformly heating.

(Embodiment 7)

Hereinafter, an induction heating device according to a seventh embodiment of the present invention will be described with reference to the drawings. The induction heating device according to the seventh embodiment to the ninth embodiment of the present invention described below is a configuration of the following induction heating device, that is, in the induction heating device of the present invention described in the first to sixth embodiments. In particular, the composition of the switching mechanism does not generate an abnormal sound, and the power conversion efficiency can be improved, and the generation of electromagnetic noise can be suppressed. Further, in the seventh embodiment and the eighth embodiment, the induction heating device having one heating coil will be described, but the induction heating device having a plurality of heating coils may be applied.

In the description of the seventh embodiment of the present invention, functions, configurations, and exemplifications that are the same as those of the first embodiment to the sixth embodiment are denoted by the same reference numerals, and the description of the first embodiment to the sixth embodiment will be described. .

Fig. 8 is a circuit diagram showing a part of the induction heating device according to the seventh embodiment of the present invention. 8 is a block diagram showing a circuit configuration in which a high-frequency current is supplied from a power source to a heating coil via an inverter circuit, and a switching portion including a switching element such as a switching mechanism included in an inverter circuit. The component of the on/off control signal.

As shown in Fig. 8, the induction heating device according to the seventh embodiment is configured such that the heating object 48 such as a pan is disposed in the vicinity of (be directly above) the heating coil 45, and is heated by the heating coil 45 and the object 48 to be heated. Coupling 48 induction heating.

The resonant capacitor 63 is connected in parallel to the heating coil 45, and constitutes a resonant circuit together with the heating coil 45. Further, the inverter circuit 43 is connected in series to the heating coil 45, and includes a switching portion such as an IGBT and a reverse conducting diode connected in parallel to the switching portion.

The power source 41 as an AC power source supplies power to the induction heating device. In the case where a commercial power source is used as the power source 41, the frequency is 50 Hz or 60 Hz.

The rectifier circuit 42 that rectifies the commercial power source from the power source 41 and supplies the power to the heating coil 45 via the inverter circuit 43 includes a diode bridge 60, a choke coil 61, and a smoothing capacitor 62.

The current detecting unit 67 as the current detecting means detects the input current supplied from the power source 41, and is configured by using a current transformer or a shunt resistor.

The current setting unit 68 sets a value corresponding to the target value of the input current, and the plurality of current setting values are stored in a ROM (Read-Only Memory) (not shown) inside the microcomputer.

The minimum on-time setting unit 69 as the minimum on-time setting means sets the minimum value (minimum on-time) of the on-time of the switching portion of the inverter circuit 43. The minimum value set by the on-time of the switch unit is stored in the ROM inside the microcomputer. The minimum value (the minimum on-time) of the on-time of the switching portion of the inverter circuit 43 means that the power value supplied to the heating coil 45 in the plurality of on-times which can be used in the switching portion of the inverter circuit 43 becomes the minimum value. On time.

The on-time variable setting unit 70 as the on-time variable setting means is The state in which the state of the switch portion of the inverter circuit 43 is controlled from a certain on-time is set to a variable in the on-time when the on-time is longer than the on-time. The plurality of variable values set in this way are stored in the ROM inside the microcomputer. Here, the on-time variable setting unit 70 sets a variable of the on-time of the plurality of switching sections.

The control unit 47 controls the on/off of the switch unit of the inverter circuit 43, and includes all output signals based on the current detecting unit 67, the current setting unit 68, the minimum on-time setting unit 69, and the on-time variable setting unit 70. The on-time arithmetic unit 65 that sets the on-time of the switching portion of the inverter circuit 43 and the pulse generator 66 that outputs the high-on-pulse of the on-time set by the on-time arithmetic unit 65 are provided. Further, the configuration of the control unit 47 of the seventh embodiment is an example, and the present invention is not limited to the constituents.

Fig. 9 is a timing chart showing input power in the induction heating device of the seventh embodiment shown in Fig. 8, and showing a timing chart of input power (supply power) supplied from the power source 41. When the power target value (constant power) PS is supplied from the start of power supply (area a), the relationship between the on-time of the switch unit and the power supply cannot be grasped when the switch unit of the inverter circuit 43 is activated. . Therefore, it is necessary to activate the switch portion based on the pre-estimated on-time, which has a problem that feedback control is difficult and power control becomes unstable.

Therefore, in the induction heating device of the seventh embodiment, when the switching portion of the inverter circuit 43 is activated, the minimum conduction time t (min) which does not become the supply power target value PS in any state is turned on. The initial value of time, while supplying the minimum power to the inverter at startup. The minimum power of the minimum conduction time t(min) is the minimum necessary for driving the heating coil 45. electric power. After starting in this manner, the on-time is gradually increased by the addition of the variable of the on-time, and soft-start control is performed in which the supplied electric power becomes the final electric power target value PS.

Fig. 10 is a waveform chart showing the on-time of the switch portion in each region (region a, region b, and region c) of the input power during the soft start control of the induction heating device according to the seventh embodiment. Fig. 10 is a view showing the on-times of the switching sections in the region a, the region b, and the region c of the input power during the soft start control in the timing chart shown in Fig. 9. Fig. 10(a) shows a control signal for the switch unit in the area a, Fig. 10(b) shows a control signal for the switch unit in the area b, and Fig. 10(c) shows the switch unit for the area c. Control signal.

As shown in FIG. 10, the on-time of the area a, the on-time of the area b, and the on-time of the area c are representatively shown, and the relationship is that the on-time t2 of the area b is longer than the on-time t1 of the area a, and the area The conduction time t3 of c is longer than the conduction time t2 of the region b.

The power supply is increased by extending the on-time of the switching portion of the inverter circuit 43. Therefore, by gradually increasing the on-time, the supplied electric power can be made the final electric power target value PS as shown in FIG.

The operation and action of the induction heating device of the seventh embodiment configured as described above will be described.

When the supply of electric power is started in a state where power is not supplied to the object 48 to be heated, the switching portion of the inverter circuit 43 is turned on by the minimum on-time t(min) set by the minimum on-time setting unit 69.

Since the on-time at this time is the minimum value of the time when the switch portion of the inverter circuit 43 is in the on state, the power supply can be supplied to the heating coil 45. The minimum value of force. Therefore, the supplied electric power p1 at the time of starting the inverter circuit 43 becomes the minimum value (refer to FIG. 9).

The minimum on-time t(min) is set so as not to be the final power target value PS regardless of the state. Therefore, the inverter circuit 43 can be activated with the minimum on-time t(min) as described above without supplying the heating coil 45 with power of a target value or more, thereby not heating the object 48 to cause cooking performance. deterioration.

In particular, when the constant power PS as the target power value is the rated power value of the induction heating device, since the input power value is not allowed to exceed the rated power value, the target power value PS is not exceeded in any state. The mode setting time at startup is an indispensable condition in product specifications.

When the minimum on-time t(min) is long, when the switching portion of the inverter circuit 43 is activated, there is a possibility that an excessive current flows into the switching portion, and the rated current or rated voltage of the switching portion is exceeded. Unstable operation destroys the switch unit. Therefore, the minimum on-time t(min) can be shortened by considering the specifications of the rated current and the rated voltage of the switch unit to prevent breakage of the switch unit.

Further, regarding the length of the minimum on-time t(min), an excessive current flows into the heating coil 45 at the start of the switching portion, and the object 48 such as a pot magnetically coupled to the heating coil 45 is also impatiently Inductive current vibrates, resulting in a "beep" of the beat-like sound. Therefore, it is possible to prevent an excessive current from flowing into the heating coil 45 by shortening the minimum on-time t(min), thereby suppressing generation of abnormal sound. Due to minimum conduction time The shorter the t(min) is, the larger the suppression state becomes. Therefore, it is preferable to set the minimum on-time t(min) as short as possible.

After the switching unit of the inverter circuit 43 is turned on and off by the minimum on-time t(min) which is the first on-time t1, the on-time variable setting unit 70 is set based on the minimum on-time t(min). The second on-time t2 obtained by the on-time variable Δt1 turns on and off the switch unit, whereby the supplied electric power p2 is supplied from the power source 41 to the heating coil 45.

In the induction heating device of the seventh embodiment, the control unit 47 can control the on/off time of the switch portion of the inverter circuit 43 by the minimum on-time t(min), and grasp the minimum on-time t(min) and supply of the switch portion. The relationship of electricity p1. Therefore, the control unit 47 can perform comparison of the final target power value PS with the supply power p1 of the minimum on-time t(min), and based on the comparison result with respect to the target power value PS at the minimum on-time t(min) When the supply electric power p1 is low, the on-time t2 obtained by adding the on-time variable Δt1 is turned on and off, and the supply electric power is controlled so as not to exceed the target electric power PS.

As described above, in the same manner as the switching method of the on-time, after the switching-on/off control is performed at the second on-time t2 (region b), the on-time variable setting unit 70 is added to the second on-time t2. The third on-time t3 obtained by turning on the time variable Δt2 controls the on/off of the switch unit. As a result, the power supply p3 is supplied from the power source 41 to the heating coil 45 (region c) at the third ON time t3. The soft start control is supplied to the heating coil 45 at the fourth conduction time t4 after the third conduction time t3, and the conduction time variable Δt3 is added to the third conduction time t3. 4 The same action is repeated after the on time t4. By changing the setting of the on-time in this way, the power supplied to the heating coil 45 can be gradually increased from the minimum supply electric power p1 and finally set as the target electric power value PS.

In the timing chart shown in FIG. 9, the case where the supply period (each area) of the input power of the soft start control is set to be long is described. However, the timing chart of FIG. 9 is an example. For example, in the induction heating device of the seventh embodiment, by shortening the supply time of each region during the soft start control period, the supplied electric power can be quickly brought to the target electric power value PS, and the controllability of the input electric power can be further improved. .

In the induction heating device of the present invention, the plurality of on-time variables are present, and the maximum on-time variable Δt(max) of the on-time variable is set to be the minimum on-time t(min) from the start-up to the target power value PS. Any area during the period. In the seventh embodiment, as shown in FIG. 9, the minimum on-time t(min) of the region a is added to the maximum on-time variable Δt(max), and is set as the on-time of the region b (supply electric power p2). Here, the supply power value at the minimum on-time t(min) is at least less than 1/2 of the target power value PS, and the maximum on-time variable Δt(max) is added to at least the minimum on-time t(min). The supplied power value of the obtained time is set so as not to exceed the target power value PS.

In the induction heating device according to the seventh embodiment of the present invention, the control unit 47 activates the switch unit of the inverter circuit 43 by setting the minimum on-time t(min) set by the minimum on-time setting unit 69 to the initial value of the on-time. . Further, after the startup, the control unit 47 performs control such that the electric power supplied to the heating coil 45 becomes the current setting value set by the current setting unit 68. In the mode of the target power (constant power) PS, the on-time of the switch unit is changed in accordance with the variable of the on-time set by the on-time variable setting unit 69.

In the present invention described with reference to the induction heating device of the seventh embodiment, a plurality of on-times that can be used in the switch unit of the inverter circuit 43 are set, and the first on-time group on the low-supply power side is classified. And including at least a minimum on-time t(min); and a second on-time group on the high-supply power side, including an on-time longer than an on-time included in the first on-time group, and including the target power (constant power) ) PS conduction time.

In the induction heating device of the present invention, the on-time of the switching portion is set to be larger than (longer than) the on-time from the on-time included in the first on-time group to the on-time included in the second on-time group. a variable of the on-time variable in the first on-time group and the on-time in the second on-time group. For example, in the seventh embodiment, as shown in FIG. 9, the first on-time group on the low-supply power side includes only the on-time of the area a (the minimum on-time t(min) at the time of startup) as the high-supply side. The second on-time group includes the on-time of all regions below the region b. Therefore, when the on-time of the switch unit is shifted from the minimum on-time t(min) of the region a of the first on-time group to the on-time (t2) of the region b of the second on-time group, the maximum on-time variable is set. The on time (t2) obtained by Δt(max).

In the induction heating device of the seventh embodiment, the minimum on-time t(min) is controlled from the viewpoint of suppressing the generation of the abnormal sound from the object 48 to be heated and the destruction of the switch portion of the inverter circuit 43. The upper setting is as short as possible, and the on-time is switched at least once with the maximum on-time variable, thereby When the minimum on-time t(min) is short, the operation period in the soft-start control before reaching the target power value PS can be shortened, thereby improving the power conversion efficiency of the inverter circuit.

In the induction heating device of the seventh embodiment, the minimum conduction of the first conduction time t1 is considered from the viewpoint of suppression of generation of abnormal sound from the object 48 to be heated and prevention of breakage of the switch portion of the inverter circuit 43 or the like. The time t (min) is set to be short, but the power conversion efficiency of the inverter circuit 43 is lowered in the operation of supplying power with low power.

Therefore, from the viewpoint of the power conversion efficiency and the easiness of power control, it is preferable to shorten the power supply period under low power as much as possible, and to quickly supply the supplied power to the target power value PS. Therefore, in the operation of supplying electric power with low electric power, after the on/off control is performed on the switch unit with the minimum on time t(min), the maximum set time by the on-time variable setting unit 70 is added with the minimum on-time t(min). The second on-time t2 obtained by the on-time variable controls the on/off of the switch unit, whereby the power p2 supplied at the on-time t2 can be quickly brought close to the target power value PS. In the induction heating device of the seventh embodiment thus controlled, it is possible to improve the power conversion efficiency and the ease of power control.

When the on-time of the switching portion of the inverter circuit 43 is short and the current flowing through the heating coil 45 is small, since the resonance current is insufficient, there is a fear that the voltage is applied to the switching portion. The control of the inverter circuit 43 is the same.

When the soft start control is continued in a state where the on-time is short, if the control inverter circuit 43 is turned on, it is accumulated in the resonance capacitor 63. The charge is short-circuited, thereby significantly reducing the power conversion efficiency of the inverter circuit 43. Therefore, in the case where the soft start control is continued in a state where the on-time is short, it is necessary to set the minimum in a state in which the ON operation can be performed without applying a voltage to the switch portion during the minimum on-time t(min). On time t (min).

However, in the induction heating device according to Embodiment 7 of the present invention, the on-time variable is different, for example, the on-time driving control is reversed by adding the maximum on-time variable immediately after the operation is performed with the minimum on-time t(min). Since the phase circuit 43 is controlled so as to have a problem of turning on in a state where a voltage is applied to the switch unit when operating at the minimum on time t (min), the period can be minimized. Therefore, the induction heating device of the seventh embodiment is configured to set the minimum on-time t(min) without paying attention to the power conversion efficiency.

Further, as shown in FIG. 9, when the power supply to the target power value PS is once again, the supply of the power is once stopped, and then the soft start control such as the supply of the target power is resumed, the previous induction heating device There is a problem that an abnormal sound is generated from the object to be heated 48 at the start of each start. However, the induction heating device according to the seventh embodiment of the present invention has an effect of suppressing the abnormal sound generated by the object 48 to be heated during the soft start control, so that the induction heating of the start of the supply power (soft start control) is repeated. Those who play better in the device.

In the case where the switching operation of the inverter circuit 43 is frequently performed in the case where the switching operation of the inverter circuit 43 is frequently performed, the period during which the power supply is small in one cycle of the switching operation (area a, etc.) is performed. And no switching of power supply The proportion of the period (region f) becomes larger. As a result, it is impossible to supply the desired electric power set as the average electric power in the induction heating device.

Therefore, in the configuration of the induction heating device according to the seventh embodiment, when the abnormal sound such as a pot sound is generated, the minimum on-time t (min) is started, and then the maximum on-time variable is quickly added to extend the on-time. To increase the supply of electricity. As a result, the induction heating device of the seventh embodiment is configured to supply a higher average electric power even if the switching operation is frequently performed.

(Embodiment 8)

Hereinafter, the induction heating device according to the eighth embodiment of the present invention will be described with reference to the drawings. In the description of the eighth embodiment of the present invention, the same functions, configurations, and symbols as those of the induction heating devices of the first to seventh embodiments are denoted by the same reference numerals, and the description of the first embodiment to the seventh embodiment will be described. .

Fig. 11 is a timing chart showing the input power of the induction heating device according to the eighth embodiment of the present invention, and is a timing chart of the voltage waveform of the power source 41 and the input power (supply power) supplied from the power source 41. The case where the supplied electric power has fluctuations (pulsation) is different from the case of the above-described seventh embodiment.

The capacity of the smoothing capacitor 62 (see FIG. 8) is as small as several μF, and fluctuation occurs when a current flows through the heating coil 45. In the induction heating device of the eighth embodiment, the fluctuation voltage waveform is substantially the same as the voltage waveform of the power source 41. In the timing chart shown in Fig. 11, the supply power fluctuates in synchronization with the frequency of the power source 41 because the voltage of the smoothing capacitor 62 fluctuates.

In the induction heating device according to the eighth embodiment of the present invention, the zero crossing point of the power source 41 is detected, and the detection point is used as a trigger to control the change of the on-time. Timing. In the induction heating device of the eighth embodiment, the small-capacity smoothing capacitor 62 is used. Therefore, the supplied electric power fluctuates in synchronization with the power supply voltage. However, similarly to the effects described in the seventh embodiment, the switching unit can be activated. An induction heating device that does not generate an abnormal sound and can improve power conversion efficiency and suppress generation of electromagnetic noise.

Further, in the induction heating device according to the eighth embodiment, since the ON time is changed in the vicinity of the zero crossing point, the amount of change in the supplied electric power immediately before the ON time is changed and immediately after the change, and the amount of change can be reduced, for example, The effect of flicker in lighting, etc.

Further, in the switch portion of the inverter circuit 43, when the voltage applied to the switch portion is low and the supplied power is small, the damage during the switching of the on-time is also small, so that the on-time is changed near the zero-crossing point. It can also help prevent damage of the switch.

Before the switch portion of the inverter circuit 43 is activated, the switch portion is kept in the off state, so that the charge to the smoothing capacitor 62 is not discharged, and even if the voltage of the power source 41 is zero, the smoothing capacitor 62 is present. A state in which a voltage equal to or lower than the peak voltage of the power source 41 is applied.

Therefore, even if the inverter circuit 43 is activated at the zero-crossing point of the power source 41, the current accompanying the voltage applied to the smoothing capacitor 62 at the time of startup flows through the switch portion or the like to cause destruction of the switch portion or the like. The problem of the abnormal sound of the heater 48.

However, the induction heating device according to the eighth embodiment of the present invention is configured to suppress the destruction of the switch portion or the like or the generation of the abnormal sound from the object 48 to be heated, regardless of the voltage of the smoothing capacitor 62. Soft The start-up control period is started with a minimum on-time t(min), and a current that is charged to the voltage of the smoothing capacitor 62 flows through the switch portion, so that an induction heating device that is safe and easy to use can be realized.

Further, in the induction heating device of the eighth embodiment, the voltage value of the smoothing capacitor 62 at the zero crossing point of the power source 41 is higher as the capacity of the smoothing capacitor 62 is larger, and the detection circuit and / or the noise response circuit is connected to various circuits such as circuits, and the discharge conditions are different, and the voltage value is determined according to the connection state.

(Embodiment 9)

Hereinafter, the induction heating device according to the ninth embodiment of the present invention will be described with reference to the drawings. In the description of the ninth embodiment of the present invention, the same functions, configurations, and symbols as those of the induction heating devices of the first to eighth embodiments are denoted by the same reference numerals, and the descriptions of the first embodiment to the eighth embodiment are given. Description.

Fig. 12 is a circuit diagram showing a part of the induction heating device according to the ninth embodiment of the present invention. In the induction heating device according to the ninth embodiment, the heating coil is formed in a substantially concentric shape by two heating coils of the first heating coil 45 on the inner side and the second heating coil 46 on the outer side, and is connected in reverse to each of the heating coils 45 and 46. The aspects of the circuit circuits 43, 44 are different from those of the above-described seventh embodiment and eighth embodiment.

Fig. 13 is a timing chart showing input power of the induction heating device of the ninth embodiment, Fig. 13(a) is a timing chart of input power supplied to the first heating coil 45 (inner heating coil), and 13(b) is supplied to the first 2 Timing diagram of the input power of the heating coil 46 (outer heating coil).

The operation, action, function, and effect of each element of the soft start control of the induction heating device according to the ninth embodiment are the same as those of the seventh embodiment. Therefore, the description of the ninth embodiment is omitted.

In the induction heating device of the ninth embodiment, the heating element 48 for inductively heating and arranging the two heating coils 45 and 46 may be arranged, and the heating coils 45 and 46 are connected to the inverter circuit 43, 44, the independent electric power is supplied to the first heating coil 45 as the inner heating coil and the second heating coil 46 as the outer heating coil.

In the circuit configuration of the induction heating device of the ninth embodiment, the two inverter circuits 43 and 44 cannot be simultaneously operated from the viewpoint of the detection of the supplied electric power and the magnetic field interference.

Therefore, for example, in order to uniformly heat the object to be heated 48, as shown in FIG. 13, the operation of supplying power to the first heating coil 45 (inner heating coil) is stopped, and the second heating coil 46 is stopped (outside heating) After the power supply of the coil) is performed, the second heating coil 46 is supplied with electric power and the supply of electric power to the first heating coil 45 is stopped. In this manner, since the control of the power supply and the stop is repeated for each fixed period, it is necessary to perform the power control so that the amount of heat generated by the heating target 48 of the first heating coil 45 and the second heating coil 46 is made uniform.

Therefore, in the induction heating device of the ninth embodiment, as described in the induction heating device of the above-described sixth embodiment, the constant electric power supplied to the heating coils 45, 46 is controlled to a desired value, and/or by The constant power input period in which the constant electric power is supplied to the heating coils 45, 46 is controlled to a desired time, and the object 48 to be heated can be uniformly heated.

In the induction heating device which is required to switch the switching operation of the plurality of inverter circuits as described above, it is possible to use the soft start control described in the ninth embodiment without generating an abnormal sound such as a pot sound (discomfort), thereby not An induction heating device that gives the user an uncomfortable feeling.

In the induction heating device shown in FIG. 12, the configuration of an inverter circuit for connecting one switching unit for controlling the supplied electric power to one heating coil has been described. However, the present invention is not limited to such a constructor. . For example, as shown in FIG. 14, even if each of the inverter circuits 70 and 71 includes a switching arm in which two switching units are connected in series to control the electric power supplied to each of the heating coils 45 and 46, the present invention can also be used. The effect of the invention.

As described above, the induction heating device of the present invention can be configured such that the minimum on-time t(min) at which the power conversion efficiency is low but no abnormal noise is generated is set as an initial value with respect to the inverter circuit, and the reverse is started. In the phase circuit, the on-time is changed to a large value, and the state in which the power conversion efficiency is low is released, and the power conversion efficiency can be improved by performing on-off control of the switch unit.

The induction heating device of the present invention described in the seventh embodiment to the ninth embodiment includes: a heating coil that inductively heats the object to be heated; a resonance capacitor that constitutes the heating coil and the resonance circuit; and a switch unit that is connected in series to the heating a coil; a rectifying unit that rectifies an alternating current power supply and supplies electric power to the heating coil; a minimum on-time setting unit that sets a minimum value of an on-time of the switch unit; and an on-time variable setting unit that sets a plurality of the switch units a variable of the on-time; a current detecting unit that detects an input current from an AC power supply; and a current setting unit that sets a value corresponding to the target value of the input current; and a control unit that performs on-off control of the switch unit.

In the induction heating device of the present invention, the control unit sets the minimum on-time set by the minimum on-time setting unit as an initial value of the on-time when the switch unit is activated, and after the start-up, The mode of the target power of the current set value set by the current setting unit varies the on-time of the switch unit based on the variable of the on-time set by the on-time variable setting unit. The plurality of on-times that can be used by the switch unit are classified into: a first on-time group on the low-supply power side, including at least the minimum on-time; and a second on-time group on the high-supply side, including the first one The on-time of the on-time included in the on-time group includes the on-time of the target power. In the control unit, the on-time of the switch unit is set to be larger than the on-time from the on-time included in the first on-time group to the on-time in the second on-time group. 1 a variable of the on-time in the on-time group and a variable in the on-time in the second on-time group.

In the induction heating device of the present invention configured as described above, it is possible to prevent abnormal noise from being generated when the switch unit is activated by setting the minimum on time as the minimum on time when the switch unit is activated. Further, the induction heating device of the present invention has a configuration in which the on-time of the switch portion is sharply increased at a timing close to the start-up other than the start-up, and an operation state in which an excessive current flows through the switch portion at the time of turning on is prevented. Therefore, it is possible to improve the power conversion efficiency and to suppress electromagnetic noise.

As described above, the induction heating device of the present invention sets a plurality of on-times for different supply powers in the soft-start control of the switch portion of the inverter circuit, and the voltage applied to the switch portion when the switch portion is turned on is applied to the switch portion. In the action state, the variable of the maximum on-time is set, and the abnormal sound generated at the start of the switch portion can be prevented, and the power conversion efficiency can be improved, and the generation of electromagnetic noise can be suppressed.

The present invention has been described with respect to the preferred embodiments of the present invention. The present invention may be modified by the details of the present invention without departing from the scope and spirit of the invention. In the case of a change in the combination or order of the various elements.

[Industrial availability]

As described above, the induction heating device of the present invention can provide a highly versatile heating device which can supply a desired power to the object to be heated to heat the object to be heated to a desired state during the soft start control, and User's ease of use is good.

41‧‧‧Power supply

42‧‧‧Rectifier circuit

43‧‧‧1st inverter circuit

44‧‧‧2nd inverter circuit

45‧‧‧1st heating coil

46‧‧‧2nd heating coil

47‧‧‧Control Department

48‧‧‧heated objects

49‧‧‧ Current Measurement Department

50‧‧‧Timekeeping Department

51‧‧‧Zero Intersection Detection Department

52‧‧‧Power Computing Department

60‧‧‧ diode bridge

61‧‧‧ Choke coil

62‧‧‧Smoothing capacitors

65‧‧‧ On-Time Operator

66‧‧‧Pulse generator

67‧‧‧ Current Detection Department

68‧‧‧ Current setting department

69‧‧‧Minimum on-time setting unit

70‧‧‧ On-time variable setting unit

Fig. 1 is a circuit configuration diagram of an induction heating device according to a first embodiment of the present invention.

2(a) and 2(b) are timing charts showing input power to an inverter circuit of the induction heating device according to the first embodiment of the present invention.

3(a) and 3(b) are timing charts showing input power to an inverter circuit of the induction heating device according to the second embodiment of the present invention.

4(a) and 4(b) are timing charts showing input power to an inverter circuit of the induction heating device according to the third embodiment of the present invention.

Fig. 5 is a view showing a circuit configuration of an induction heating device according to a fourth embodiment of the present invention.

Fig. 6 is a view showing the circuit configuration of the induction heating device according to the fifth embodiment of the present invention.

Figure 7 is a layout view of a heating coil of an induction heating device according to a sixth embodiment of the present invention.

Fig. 8 is a circuit diagram showing a part of the induction heating device according to the seventh embodiment of the present invention.

Fig. 9 is a timing chart showing input power of the induction heating device of the seventh embodiment of the present invention shown in Fig. 8.

Figs. 10(a) to 10(c) are diagrams showing the on-time of the switching sections of the respective regions (area a, region b, and region c) of the input power during the soft-start control of the induction heating device according to the seventh embodiment of the present invention. Waveform diagram.

Fig. 11 (a) and (b) are timing charts showing input power of the induction heating device of the eighth embodiment of the present invention.

Fig. 12 is a circuit diagram showing a part of the induction heating device according to the ninth embodiment of the present invention.

Fig. 13 (a) and (b) are timing charts showing input power of the induction heating device of the ninth embodiment of the present invention.

Fig. 14 is a circuit diagram showing another configuration of a part of the induction heating device according to the ninth embodiment of the present invention.

41‧‧‧Power supply

42‧‧‧Rectifier circuit

43‧‧‧1st inverter circuit

44‧‧‧2nd inverter circuit

45‧‧‧1st heating coil

46‧‧‧2nd heating coil

47‧‧‧Control Department

48‧‧‧heated objects

Claims (9)

An induction heating device comprising: a plurality of heating coils for inductively heating an object to be heated; an inverter circuit for supplying power to the plurality of heating coils; and a control unit for driving and controlling the inverter circuit And the control unit inductively supplies electric power to each of the heating coils in accordance with each cycle from the inverter circuit, thereby heating the object to be heated; and each of the plurality of heating coils is arranged substantially concentrically The control unit performs soft start control so that the power supplied to the heating coil is gradually increased from a preset minimum value to a constant power value when the power supply to the respective heating coils is started. After the electric power of the heating coil reaches the constant electric power value, the inverter circuit is controlled to maintain the supply of the constant electric power value until the supply of electric power to the heating coil is completed, and the constant electric power value is greater than the supply to the above Setting the average power value of the heating coil; the above control unit is for the above plural In the soft start control of the heating coil, the constant power value and/or the constant power value is changed from the minimum value smaller than 1/2 of the constant power value to the power change rate during the soft start control period that becomes the constant power value. Or the cycle, thereby controlling the average power supplied to the heating coil, and the control unit is configured to supply the constant power value to the heating coil having a larger diameter than the heating coil having a smaller diameter and/or Or the above-mentioned cycle is long. The induction heating device according to claim 1, wherein the control unit is configured to receive electric power supplied to the heating coil during soft start control and electric power supplied to the heating coil during supply of constant electric power. The amount and the operation of supplying electric power to each of the heating coils are performed for one round, and the average electric power supplied to the heating coil is calculated. The induction heating device of claim 2, comprising: a current measuring unit that measures a current supplied from the power source to the inverter circuit; and a timing unit that measures an operation state of the inverter circuit; and the control The system is configured to calculate the amount of electric power supplied to the inverter circuit based on the output value of the current measuring unit, and to grasp the amount of electric power supplied to the inverter circuit based on the time measured by the time measuring unit, and It takes a round of time to perform an operation of supplying electric power to each of the above heating coils. The induction heating device of claim 2, comprising: a current measuring unit that measures a current supplied from the power source to the inverter circuit; and a zero-cross detecting unit that detects a point at which the voltage of the power source becomes a zero level; and the power a calculation unit that calculates power supplied to the inverter circuit; and The power calculation unit is configured to read an output signal from the current measuring unit in synchronization with a frequency of a detection signal from the zero-cross detecting unit, and output a zero-cross signal to the control unit. The control unit is configured to It is configured to calculate the power value and/or the amount of power input to the inverter circuit during the period from the generation of the zero-crossing signal to the generation of the next zero-crossing signal. The induction heating device of claim 3, comprising: a zero-cross detecting unit that detects a point at which the voltage of the power source becomes a zero level; and a power calculating unit that calculates the power supplied to the inverter circuit; and the power The calculation unit is configured to read an output signal from the current measurement unit in synchronization with a frequency of a detection signal from the zero-cross detection unit, and output a zero-cross signal to the control unit; the control unit calculates The power value and/or the amount of power input to the inverter circuit during the period from the generation of the zero-crossing signal to the time when the next zero-crossing signal is generated is formed. The induction heating device of claim 1, further comprising: a minimum on-time setting unit that sets a power value supplied to the heating coil to a minimum value in a plurality of on-times that can be used in a switching portion of the inverter circuit a minimum on-time; an on-time variable setting unit that sets a variable of an on-time of the plurality of switch sections; a current detecting section that detects an input current from the power supply; and a current setting section that sets the input current Target value corresponding to And the control unit sets the minimum on-time set by the minimum on-time setting unit to an initial value of the on-time when the switching unit is activated, and is set by the current setting unit after the starting. In the method of the target power of the current set value, the on-time of the switch unit is varied by a variable of the on-time set by the on-time variable setting unit, and the plurality of on-times that can be used by the switch unit are classified into: at least a first on-time group on the low power supply side of the minimum on-time, and an on-time including a longer on-time included in the first on-time group, and including a high-supply power that is an on-time of the target power a second on-time group on the side; a variable of an on-time of the switch portion from an on-time included in the first on-time group to an on-time in transition in an on-time included in the second on-time group is set to a variable larger than the on-time in the first on-time group and a change in the on-time in the second on-time group the amount. The induction heating device of claim 6, wherein the on-time included in the first on-time group is set only as a minimum on-time. The induction heating device according to claim 6 or 7, wherein the operation is performed by the self-disconnection control in a state where a voltage is applied to the switch portion when operating at least with a minimum on-time. An induction heating device according to claim 6 or 7, wherein It is configured to set the start timing of the switch unit in the vicinity of the zero crossing point of the power source.