JP4973319B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to heating control of an induction heating cooker.

In a conventional induction heating cooker, for iron pans, SUS pans with magnetism, and SUS pans without magnetism, the characteristics of the pans are judged before heating is started, and they are operated in a heating mode suitable for each pan. (For example, see Patent Documents 1 and 2).
Japanese Patent No. 2816621 Japanese Examined Patent Publication No. 2-55916

  In the conventional configuration, when the pan is heated using the induction heating cooker, the characteristics of the pan are determined before starting the heating for the iron pan, the SUS pan with magnetism, and the SUS pan without magnetism. It had the subject that it was necessary to operate in the heating mode suitable for the pan. Especially for iron pans and SUS pans with magnetism, the characteristics are similar, so it is best to operate SUS pans with magnetism that is harder to enter than iron pans in the same heating mode as iron pans. There was also a problem that input could not be obtained.

In order to solve the conventional problems, an induction heating cooker according to the present invention includes a heating coil that heats a pan on a top plate, an inverter circuit that supplies a high-frequency current to the heating coil, and a power source for the inverter circuit. A DC power supply to be supplied; input current detection means for detecting an input current to the DC power supply; and control means for controlling an output of the inverter circuit, wherein the control means has an operation state of the control means as the inverter. in the case where the circuit of the drive duty is less than the current value of the output corresponding set by the current value output setting means detected by said input current detecting means at the maximum state, the current value detected by said input current detecting means There determines that the time threshold is greater than that set by the control means, the pan being heated is the load of the magnetic system.

This makes it possible to determine the characteristics of the pan during the heating operation.
Optimal heating control can be performed for each pan.

  Since the induction heating cooker of the present invention performs heating control according to the characteristics of the pan after the start of heating, the one that was close to the iron pan at the beginning of heating has a magnetic property due to changes in characteristics due to heating, etc. Even in the case of a pan characteristic, the optimum thermal power can be obtained, and unnecessary thermal power limitation is eliminated, so that the convenience of the user can be improved.

A first invention is a heating coil for heating a pan on a top plate, an inverter circuit for supplying a high-frequency current to the heating coil, a DC power supply for supplying power to the inverter circuit, and an input current to the DC power supply And an input current detection means for controlling the output of the inverter circuit, and the control means is configured to control the input current detection means when the operation state of the control means is the maximum drive duty of the inverter circuit. Heating when the current value detected by the input current detection means is larger than the threshold value set in the control means when the current value detected by the input setting means is less than the current value corresponding to the output set by the output setting means. by the pot in it is determined that the load of the magnetic system, it is possible to determine the characteristics of the pot during the heating operation.

A second invention is, in particular, Oite the first inventions, wherein, when the pan of the control means during heating is determined to be the load of the magnetic system, the driving voltage of the inverter circuit By controlling the drive voltage of the inverter circuit and controlling the current value detected by the input current detection means to a current value corresponding to the output set by the output setting means , In contrast, optimal heating control can be performed.

A third invention is, in particular, Oite the second inventions, the control means, with respect to the current value detected by said input current detecting means has a driving voltage upper limit value of the inverter circuit as a set value, The control means determines that the pan being heated is a magnetic load, raises the drive voltage of the inverter circuit, and controls the drive voltage of the inverter circuit. limits the driving voltage of the inverter circuit in response to the detected current value, the pot during heating can be prevented from entering excessive power.

A fourth invention is, in particular, Oite the second inventions, the control means, the control means is in heat
The pot is determined that the load of the magnetic system, in a state that controls the driving voltage of the inverter circuit, the target value of the driving voltage of the inverter circuit is equal to the inverter circuit drive voltage at the time of duty control or when small, is greater than the set output current equivalent value by the current value detected by said input current detection means said output setting means, a mode for controlling the duty cycle of the inverter circuit from the driving voltage control of the inverter circuit By switching, when the center of the pan deviates from the center of the heating coil, or when the characteristics of the pan change due to heating, it is possible to shift to the optimum heating mode.

A fifth invention is, in particular, Oite the second inventions, the control means, said control means the pot during heating is determined that the load of the magnetic system, increase the driving voltage of the inverter circuit It is, in a state that controls the driving voltage of the inverter circuit, when the current value detected by said input current detecting means, has risen with great inclination than a preset threshold to the control means, wherein with lowering the driving voltage of the inverter circuit to the drive voltage of the inverter circuit during duty control promptly by moving the duty control, it is possible to inverter circuit are prevented from becoming unsafe operating conditions.

A sixth invention is particularly, Oite the second inventions, further wherein the control means heating coil current detecting means for detecting a high-frequency current flowing through the heating coil, the control means the pot during heating was determined as the load of the magnetic system, wherein increasing the driving voltage of the inverter circuit, in a state that controls the driving voltage of the inverter circuit, the current value detected by the heating coil current detecting means, the control when elevated with great inclination than a preset threshold means, together with lowering the driving voltage of the inverter circuit to the drive voltage of the inverter circuit during duty control, by moving rapidly to duty control, It is possible to prevent the inverter circuit from entering a dangerous operating state.

A seventh invention is particularly, Oite the second inventions, the control means, said control means the pot during heating is determined that the load of the magnetic system, increase the driving voltage of the inverter circuit is, in a state that controls the driving voltage of the inverter circuit, when the current value detected by said input current detecting means, becomes smaller than a preset threshold to the control means, from the said heating coil By determining that the pan has run out and quickly shifting to duty control, the inverter circuit can be prevented from entering a dangerous operating state due to the pan running out.

An eighth aspect of the invention, particularly, Oite the second inventions, further wherein the control means heating coil current detecting means for detecting a high-frequency current flowing through the heating coil, the control means the pot during heating was determined as the load of the magnetic system, wherein increasing the driving voltage of the inverter circuit, in a state that controls the driving voltage of the inverter circuit, the current value detected by the heating coil current detecting means, the control if it becomes smaller than the preset threshold means, said from the heating coil by the flow proceeds to a determination quickly duty control and the pot is exhausted, the operating state the inverter circuit is dangerous by the pan is gone Can be avoided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a block diagram according to the first embodiment of the present invention.

  In FIG. 1, the top plate 12 is for placing the load pan 11, the heating coil 13 is for heating the load pan 11, and the inverter circuit 14 is for supplying high-frequency current to the heating coil 13, The DC power supply 15 supplies power to the inverter circuit 14 via the booster circuit 19, the input current detection means 16 detects input current from a commercial power supply, and the heating coil current detection means 17 The high-frequency current flowing through 13 is detected. The display means 20 is for displaying the operating state of the equipment, the output setting means 21 is for setting the heating output of the equipment, and the control means 22 is an inverter circuit so that the output set by the output setting means 21 is obtained. 14 outputs are controlled.

  FIG. 2 is a diagram showing an outline of a threshold value for determining a magnetic load in the first embodiment of the present invention.

  In FIG. 2, an area 30 is an area for determining the characteristics of the magnetic SUS, a threshold 31 is a threshold for dividing the characteristics of the magnetic SUS and the small-diameter pan, and a characteristic 32 is a characteristic of a magnetic small-diameter pan, etc. Reference numeral 33 denotes a characteristic such as a magnetic SUS pan, and characteristic 34 denotes a characteristic such as an iron pan.

  FIG. 3 is a diagram showing an outline of the drive voltage maximum value of the inverter circuit with respect to the input current in the first embodiment of the present invention.

  In FIG. 3, a line 42 is a line that limits the inverter circuit drive voltage with respect to the input current.

  The operation | movement is demonstrated about the induction heating cooking appliance comprised as mentioned above.

  When heating is started, the control means 22 operates the inverter circuit 14 to supply a high-frequency current to the heating coil 13, and the load pan 11 placed above the heating coil 13 is heated.

  When the load pan 11 is a magnetic pan, the relationship between the current value detected by the input current detecting means 16 and the duty for driving the inverter circuit 14 has a tendency as shown in FIG. 2, where the duty is the inverter circuit. One cycle of 14 drive frequencies is 100%, and the ratio of the on-time in one cycle is converted in percentage. Therefore, since 50% is off, the duty, which is the maximum on-time, is also 50%. Generally, it is difficult to distinguish the magnetic SUS pan from the iron pan before the start of heating, and the operation is performed in the same operation mode. It is known that when heating is started, the magnetic SUS pan follows a trajectory such as a characteristic 33 such as a magnetic SUS pan, and the iron pan follows a trajectory such as a characteristic 34 such as an iron pan. Further, when the magnetic SUS small-diameter pan or the center of the load pan 11 is deviated from the center of the heating coil 13, the trajectory like the characteristic 32 of the magnetic small-diameter pan is obtained. From this, it is possible to detect the magnetic SUS pan by setting an optimum threshold for the input current at the maximum duty (50%). Specifically, the pan having the characteristics coming to the region 30 to be determined as the characteristics of the magnetic SUS is determined as the magnetic SUS pan. At the same time, it can be distinguished from a magnetic small-diameter pan that does not reach the region 30.

  When the load pan 11 is a pan having characteristics that come to the region 30 to be determined as the characteristics of the magnetic SUS, the control means 22 boosts the DC voltage supplied from the DC power source 15 by the boost circuit 19 having the inverter circuit. By controlling the drive voltage of the inverter circuit 14 by increasing the drive voltage of the inverter circuit 14, the current value detected by the input current detection means 16 is controlled to a current value corresponding to the output set by the output setting means 21. Thus, optimal heating control can be performed on the magnetic pan. At this time, when the current value detected by the input current detection means 16 is determined, by setting a voltage value that limits the drive voltage of the inverter circuit, it is limited so that excessive power does not enter the load pan 11 being heated. Can do.

Control means 22, the load pan 11 during heating is determined that the load of the magnetic system, in a state that controls the drive voltage of the inverter circuit 14, when the target value is de Yuti control of the drive voltage of the inverter circuit 14 when equal to or smaller than the driving voltage of the inverter circuit, is greater than the set output current equivalent value by the current value output setting means 21 detects the input current detector 16, from the drive voltage control of the inverter circuit 14 By switching to a mode that controls the duty (ON time) of the inverter circuit 14, when the center of the pan deviates from the center of the heating coil or when the characteristics of the pan change due to heating, the input current value is reduced. It is possible to shift to the optimum heating mode.

  The control means 22 determines that the load pan 11 being heated is a magnetic load, raises the drive voltage of the inverter circuit 14, and controls the drive voltage of the inverter circuit 14. When the current value detected by 16 increases with a slope larger than a threshold preset in the control means 22, the drive voltage of the inverter circuit 14 is lowered to the drive voltage of the inverter circuit 14 during duty control, By quickly shifting to duty control, the input current value can be adjusted so that the inverter circuit 14 does not enter a dangerous operating state.

  The control means 22 determines that the load pan 11 being heated is a magnetic load, raises the drive voltage of the inverter circuit 14, and controls the drive voltage of the inverter circuit 14 while detecting the heating coil current. When the current value detected by the means 17 rises with a larger slope than the threshold preset in the control means 22, the drive voltage of the inverter circuit 14 is lowered to the drive voltage of the inverter circuit 14 during duty control. By quickly shifting to duty control, the heating coil current value can be adjusted so that the inverter circuit 14 does not enter a dangerous operating state.

  The control means 22 determines that the load pan 11 being heated is a magnetic load, boosts the DC voltage supplied from the DC power supply 15 with a booster circuit 19 and increases the drive voltage of the inverter circuit 14, In the state where the drive voltage of the inverter circuit 14 is being controlled, when the current value detected by the input current detection means 16 is smaller than the threshold value preset in the control means 22, the pan from the heating coil 13 is removed. By determining that it has run out and quickly shifting to duty control, it is possible to adjust the input current value so that the inverter circuit 14 does not enter a dangerous operating state due to running out of the pan.

  The control means 22 determines that the load pan 11 being heated is a magnetic load, boosts the DC voltage supplied from the DC power supply 15 with a booster circuit 19 and increases the drive voltage of the inverter circuit 14, In a state where the drive voltage of the inverter circuit 14 is controlled, when the current value detected by the heating coil current detection means 17 becomes smaller than the threshold value preset in the control means 22, the pan from the heating coil 13 is used. It is possible to adjust the heating coil current value so that the inverter circuit 14 does not enter a dangerous operating state due to the absence of the pan.

  As described above, the induction heating cooker according to the present invention performs heating control according to the characteristics of the pan after the start of heating. Even when it becomes the characteristics of a SUS pan with magnetism, the optimum input can be obtained, and unnecessary input restrictions are eliminated, so it is suitable for applications such as equipment that heats magnetic loads by induction heating. Is also applicable.

The block diagram which shows the induction heating cooking appliance in the 1st Embodiment of this invention The figure which showed the outline of the threshold value for determining the load of the magnetic type | system | group in the 1st Embodiment of this invention The figure which showed the outline of the drive voltage maximum value of the inverter circuit with respect to the input current in the 1st Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Load pan 12 Top plate 13 Heating coil 14 Inverter circuit 15 DC power supply 16 Input current detection means 17 Heating coil current detection means 20 Display means 21 Output setting means 22 Control means 30 The area | region judged with the characteristic of magnetic system SUS 31 Magnetic system SUS Threshold that separates the characteristics of the small-diameter pan 42 Line that limits the inverter drive voltage against the input current

Claims (8)

A heating coil that heats the pan on the top plate, an inverter circuit that supplies high-frequency current to the heating coil, a DC power source that supplies power to the inverter circuit, and an input current detection that detects input current to the DC power source And a control means for controlling the output of the inverter circuit, wherein the control means is a current value detected by the input current detection means when the operation state of the control means is a state in which the drive duty of the inverter circuit is maximum. If but less than the current value of the output corresponding set by the output setting means, when greater than a threshold that has been set current value detected by said control means by said input current detecting means, the pan being heated An induction heating cooker that determines that the load is magnetic. Wherein when said control means has the pan during heating is determined that the load of the magnetic system, increase the driving voltage of the inverter circuit, by controlling the driving voltage of the inverter circuit, wherein The induction heating cooker according to claim 1, wherein the current value detected by the input current detection means is controlled to a current value corresponding to the output set by the output setting means. Wherein, with respect to the current value detected by said input current detecting means has a driving voltage upper limit value of the inverter circuit as a set value, when the control means is a load of the magnetic system of the pan during heating determined, the increasing the driving voltage of the inverter circuit, in a state that controls the driving voltage of the inverter circuit, to limit the driving voltage of the inverter circuit in accordance with a current value detected by said input current detecting means, The induction heating cooker according to claim 2, wherein excessive electric power is prevented from entering the cooking pot. It said control means, said control means the pot during heating is determined that the load of the magnetic system, in a state that controls the driving voltage of the inverter circuit, the target value is de driving voltage of the inverter circuit when Yuti control the inverter circuit is equal to or smaller than the driving voltage of the time, it is greater than the set output current equivalent value by the current value detected by said input current detection means said output setting means, said inverter circuit The induction heating cooker according to claim 2, wherein the mode is switched from driving voltage control to a mode for controlling a duty of the inverter circuit. It said control means, said control means the pot during heating is determined that the load of the magnetic system, wherein increasing the driving voltage of the Yi <br/> inverter circuit, controls the driving voltage of the inverter circuit in a state where there, current value detected by said input current detecting means, when raised with great inclination than a preset threshold to the control means, said inverter when duty control the driving voltage of the inverter circuit The induction heating cooker according to claim 2, wherein the induction heating cooker immediately shifts to duty control while lowering to the drive voltage of the circuit. Further comprising a heating coil current detecting means for detecting a high-frequency current flowing through the heating coil, the control means, said control means the pot during heating is determined that the load of the magnetic system, the driving voltage of the inverter circuit When the drive voltage of the inverter circuit is controlled and the current value detected by the heating coil current detection means rises with a larger slope than the threshold value preset in the control means The induction heating cooker according to claim 2, wherein the drive voltage of the inverter circuit is lowered to the drive voltage of the inverter circuit at the time of duty control, and the duty control is promptly shifted to duty control. Wherein, in a state in which said control means the pot during heating is determined that the load of the magnetic system, increase the driving voltage of the inverter circuit, and controls the driving voltage of the inverter circuit, wherein current value detected by the input current detecting means, when it becomes smaller than the preset threshold to the control means, the transition from the said heating coil to determine quickly duty control and the pot is exhausted claim 2 The induction heating cooker described in 1. Further comprising a heating coil current detecting means for detecting a high-frequency current flowing through the heating coil, the control means, said control means the pot during heating is determined that the load of the magnetic system, the driving voltage of the inverter circuit It was elevated to a state which is controlling the driving voltage of the inverter circuit, the current value detected by the heating coil current detection unit, if it becomes smaller than the preset threshold to the control means, the heating The induction heating cooker according to claim 2, wherein it is determined that the pan has run out of the coil, and the duty control is immediately performed.

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