JP5605084B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that induction-heats a cooking container.

  Conventionally, in this type of induction heating cooker, in order to protect an inverter that supplies a high-frequency current to the induction heating coil, it is generally performed to detect whether the power supply voltage is excessive or small and stop the inverter. (For example, refer to Patent Document 1). The AC power supply is full-wave rectified, divided and compared with a reference voltage to detect an abnormality in the power supply voltage.

  Moreover, the method of detecting the vibration of the load pan heated with the induction heating coil and detecting the resonance sound of the pan from the vibration waveform has been devised (for example, see Patent Document 2).

Japanese Patent Publication No. 05-016153 International Publication No. 2007/132647

  However, in the conventional induction heating cooker, there is a report from the user that an unpleasant sound may be generated when the pan is heated, and the factor in this case is a malfunction inside the induction heating cooker. There is a problem of not knowing whether the cause is the cause or the power source.

  Furthermore, when detecting sound or vibration, it is necessary to place a vibration sensor such as piezoelectric ceramics or a microphone on the plate on which the pan above the induction heating coil is placed, which increases the cost. ing.

  The present invention solves the above-described conventional problems, and by providing a function to determine the distortion of the power source and notify the user, when an unpleasant panning sound is generated during cooking, the serviceman determines the cause. The purpose is to provide an induction heating cooker that helps to investigate and solve, improves maintenance, and is comfortable and easy to use.

In order to solve the above conventional problems, the induction heating cooker of the present invention, the induction heating coil you induction heating the pan to generate a high-frequency magnetic field, power switching element for applying a high frequency current to the induction heating coil, and an inverter circuit composed of the resonance capacitor, and control means for controlling said inverter circuit, a rectifier circuit for converting an AC power source is a commercial power supply into DC, a voltage detecting means for detecting a voltage said rectifying circuit outputs a power supply distortion determination unit that the power distortion seen-size constant from the change amount of the voltage and the sampled voltage detected by the voltage detecting means, input means for the start of the power distortion determination are entered, displays the power distortion determination result comprising a display means for the, if unpleasant Nabeon occurs during cooking, if the input means is operated to start the power distortion determination, the power distortion Constant means, in a state where the control means has a high frequency current to the induction heating coil, the voltage the rectifier circuit obtained by sampling one period of the voltage of the commercial power source at a predetermined period by the voltage detection means outputs The difference between the data and the data of the previously sampled voltage is calculated to determine the amount of change in the voltage, and the occurrence of the peak where the amount of change in the voltage rises and falls is determined to be power supply distortion when the number of occurrences exceeds a predetermined number . In this case , the display means displays that the commercial power source is distorted.

In addition, in the induction heating cooker of the present invention, when the voltage across the rectifier circuit is flattened by the smoothing capacitor and the power supply distortion is not affected at all, the power supply distortion determination means uses the voltage detection means. During the detection of the waveform, the inverter circuit is driven, and the flat voltage waveform is changed to the pulsating waveform so that the power supply distortion can be determined.

This eliminates the need to load a circuit for measuring the waveform of the commercial AC power supply separately from the rectifier circuit that converts AC to DC for the input power to the inverter circuit. Distortion can be detected. When a pot sound is generated, it can be determined whether the cause is in the device or in the commercial power source, and the user can quickly respond to the service.

In the induction heating cooker of the present invention, when the power distortion determination means determines that a pot sound is generated when a high frequency current is applied to the induction heating coil from the waveform sampled at a predetermined period by the voltage detection means, a pot sound is generated. by displaying that the commercial power supply, if the pan sound occurs, the cause, whether inside equipment, it is possible to determine whether there to the commercial power supply, to quickly service correspondence of the user Can do.

The block diagram of the induction heating cooking appliance in Embodiment 1 of this invention External view of display means and input means of induction heating cooker in embodiment 1 of the present invention (A) The figure which shows the normal power supply waveform detected with the voltage detection means of the induction heating cooking appliance in Embodiment 1 of this invention (b) By the voltage detection means of the induction heating cooking appliance in Embodiment 1 of this invention Diagram showing detected power waveform with distortion The flowchart which shows the determination operation | movement of the power supply distortion determination means of the induction heating cooking appliance in Embodiment 1 of this invention. (A) The figure which shows the transition of the voltage change amount in the normal power supply of the induction heating cooking appliance in Embodiment 1 of this invention (b) The voltage change in the distorted power supply of the induction heating cooking appliance in Embodiment 1 of this invention Diagram showing quantity transition (A) The figure which shows the example of a display at the time of determining with the normal power supply of the induction heating cooking appliance in Embodiment 1 of this invention (b) Determination with the distorted power supply of the induction heating cooking appliance in Embodiment 1 of this invention Figure showing a display example when The block diagram of the induction heating cooking appliance in Embodiment 2 of this invention (A) The figure which shows the normal power supply waveform detected by the voltage detection means of the induction heating cooking appliance in Embodiment 2 of this invention (b) The distortion detected by the voltage detection means in Embodiment 2 of this invention Diagram showing a certain power supply waveform

A first aspect of the present invention is an induction heating coil you induction heating the pan to generate a high-frequency magnetic field, the power switching device is a high-frequency current to the induction heating coil, and an inverter circuit comprising the resonance capacitor, wherein Control means for controlling the inverter circuit, a rectifier circuit for converting an alternating current power supply, which is a commercial power supply, into direct current, a voltage detection means for detecting a voltage output from the rectifier circuit, and a voltage detected by the voltage detection means are sampled. includes a power supply distortion determination means for determining the power distortion from variation of the voltage, input means the start of the power supply distortion determination are entered, and a display means for displaying the power distortion determination result, the uncomfortable during cooking If the input means is operated and the power distortion determination is started when a hot pot sound is generated, the control means passes a high-frequency current to the induction heating coil. In state, the power distortion determination unit, the voltage by the detecting means of the commercial power supply for one cycle of the voltage the rectifier circuit outputs a voltage obtained by sampling at a predetermined cycle data and voltage sampled in the previous calculating a difference between the data calculated amount of change in voltage, if the number of occurrences of peaks change amount of the voltage is lowered raised is determined to supply distortion over a predetermined number of times, the commercial power supply by the display means It displays that it is distorted.

  In addition, in the induction heating cooker of the present invention, when the voltage across the rectifier circuit is flattened by the smoothing capacitor and the power supply distortion is not affected at all, the power supply distortion determination means uses the voltage detection means. During the detection of the waveform, the inverter circuit is driven, and the flat voltage waveform is changed to the pulsating waveform so that the power supply distortion can be determined.

This eliminates the need to load a circuit for measuring the waveform of the commercial AC power supply separately from the rectifier circuit that converts AC to DC for the input power to the inverter circuit. Distortion can be detected. When a pot sound is generated, it can be determined whether the cause is in the device or in the commercial power source, and the user can quickly respond to the service.

A second invention is, in particular, the power distortion determination means in the first invention, when the number of occurrences of the peak is less than said predetermined number, a positive phase及of the commercial power source from the output waveform of the voltage detecting means
Further, by calculating the integrated value of the voltages in the negative phase and determining that the power supply distortion is found if the difference between the phases is equal to or greater than a predetermined value , the power supply distortion can be detected by a simple method at a low cost.

  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 of an induction heating cooker according to the first embodiment of the present invention.

  In FIG. 1, a power source 1 is a 200 V commercial power source that is a low-frequency AC power source, and is connected to an input terminal of a rectifier circuit 2 that is a bridge diode. The both-ends output of the rectifier circuit 2 is connected to an inverter circuit 4 configured by a power switching element and a resonance capacitor (not shown) for supplying a high frequency current to a heating coil 3 that is an induction heating coil.

  The control means 5 determines the output level (hereinafter referred to as thermal power) of the heating coil 3 through the inverter circuit 4 according to the current value detected by the current detection means 6 constituted by a current transformer in five stages (0 W, 500 W, 1000 W, 1500W, 2000W, 3000W).

  The power supply distortion determination means 7 determines the presence or absence of power supply distortion from the amount of change in the voltage across the rectifier circuit 2 detected by the voltage detection means 8. The input means 9 is constituted by a key switch, and instructs the control means 5 to start or stop the inverter circuit 4. The display means 10 displays the state set by the input means 9.

  The power supply distortion determination means 7 and the control means 5 are realized by a microcomputer, and outputs from the voltage detection means 8 and the current detection means 6 are converted into digital values by an AD converter built in the microcomputer. .

  FIG. 2 is an external view of the display means and input means of the induction heating cooker in the first embodiment of the present invention. In FIG. 2, the input means 9 is composed of four key switches, and the display means 10 is composed of LEDs for displaying a menu, set thermal power, set temperature and remaining time.

About the induction cooking heater comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. First, the operation of the power supply distortion determination means 7 will be described.
FIG. 3 (a) is a diagram showing a normal power supply waveform detected by the voltage detection means of the induction heating cooker in the first embodiment of the present invention, and FIG. 3 (b) is in the first embodiment of the present invention. It is a figure which shows the power supply waveform with a distortion detected by the voltage detection means of an induction heating cooking appliance.
FIG.3 (b) is a figure which shows the power waveform with a distortion detected by the voltage detection means of the induction heating cooking appliance in the 1st Embodiment of this invention. There are various examples of power supply distortion, such as those in which harmonics are superimposed on the power supply, but in FIG.

  FIG. 4 is a flowchart showing the determination operation of the power supply distortion determination means 7 of the induction heating cooker according to the first embodiment of the present invention.

First, in step 31, power distortion determination is started by a key switch operation of the input means 9. In the present embodiment, the power distortion determination is started by simultaneously pressing the down key and the up key among the four switches constituting the input unit 9.

  Next, from step 32 to step 33, the voltage for one cycle of the commercial power source 1 is measured by the voltage detection means 8 at 200 sampling voltages with a sampling period of 100 microseconds. In step 34, the difference between the 200 data acquired in step 32 to step 33 and the previous data is calculated to determine the amount of change, and in step 35, the difference data peak from the previous data is obtained. Find the number of value detections.

  FIG. 5 (a) is a diagram showing the transition of the voltage change amount in the normal power supply of the induction heating cooker according to the first embodiment of the present invention. FIG. 5 (b) is the induction heating cooker according to the first embodiment of the present invention. It is a figure which shows the transition of the amount of voltage changes in the distorted power supply. FIG. 6 (a) is a diagram showing a display example when it is determined that the induction heating cooker is a normal power source in the first embodiment of the present invention. FIG. 6 (b) is an induction heating in the first embodiment of the present invention. It is a figure which shows the example of a display at the time of determining with the distorted power supply of a cooking appliance.

  As shown in FIG. 5B, when the number of detected peak values obtained in step 35 is 5 or more, it is determined that the power source is distorted. In step 37, the display shown in FIG. To indicate that the power supply is abnormal. In step 38, the power supply distortion determination is terminated.

  Further, as shown in FIG. 5A, when the number of detected peak values obtained in step 35 is 4 or less, next, in step 39, an integrated value in each phase of the power source is detected, and in step 40, If the difference between the integrated values is 100 or more, it is determined that the power source is distorted. In step 37, the display unit 10 displays the display shown in FIG. Then, the power distortion determination is finished.

  Furthermore, when the difference between the integrated values in the respective phases of the power source obtained in step 39 is less than 100, the display shown in FIG. 6A is performed in step 41 to indicate that the power source is normal, and in step 38, The power distortion determination is terminated.

  As described above, the voltage detection unit 8 can determine whether the power source generates an unpleasant pot sound by the power source distortion determination unit 7 from the detected power source waveform, thereby improving maintainability. be able to.

  In this embodiment, the voltage across the terminals of the rectifier circuit that supplies the input power of the inverter circuit is measured. However, as long as it is a means that can measure the power supply waveform of one cycle of the commercial power supply, the power supply distortion determination means. Thus, similarly, power supply distortion can be detected.

  Further, in this embodiment, the power supply distortion is determined from the number of times the peak of the difference from the previous data of the power supply voltage is detected. However, the time difference for each phase and the peak value of the voltage for each phase are determined. The power supply distortion can also be determined from the difference between the two.

  In this embodiment, the power distortion determination is started as a service test. However, when cooking is started, the power distortion level is determined by the power distortion determination, and the predetermined level or higher is determined. If it is a distortion, it is possible to stop cooking and inform that the power supply is abnormal.

  In the present embodiment, the voltage of one cycle of the commercial power supply is measured for power supply distortion determination. However, more accurate determination can be made by measuring a plurality of cycles.

(Embodiment 2)
FIG. 7 is a block diagram of the induction heating cooker according to the second embodiment of the present invention, and is a block diagram of the induction heating cooker according to the first embodiment. A smoothing capacitor 11 is added, and the voltage shown in FIG. 3A is smoothed by the smoothing capacitor 11 to become a constant voltage.

  FIG. 8A shows a normal power supply waveform detected by the voltage detection means of the induction heating cooker in the second embodiment of the present invention, and FIG. 8B shows the voltage in the second embodiment of the present invention. It is a figure which shows the power supply waveform with the distortion detected by a detection means.

  FIG. 8B shows a voltage waveform in which the voltage smoothed by the smoothing capacitor 11 is measured by the voltage detecting means 8 while the inverter circuit 4 is controlled by the control means 5 and a high-frequency current is applied to the heating coil 3. Is shown.

  Thus, when the inverter is not driven, the voltage detected by the voltage detecting means 8 is constant due to the function of the smoothing capacitor, but the inverter circuit 4 is driven to heat the current charged in the smoothing capacitor 11. When consumed by the coil 3 and the inverter circuit 4, a pulsating flow is generated, and this pulsating flow is detected by the voltage detecting means 8, and the power supply distortion determining means 7 detects whether or not the power supply is distorted.

  Note that the method of determining power supply distortion is determined by the difference in bottom voltage for each phase as well as the determination of the peak detection frequency of the change amount and the voltage integrated value for each phase shown in the first embodiment. it can.

  In addition, when the pulsating current has a flat waveform by the smoothing capacitor 11, by adding a discharge resistor for discharging the electric charge from the smoothing capacitor 11, the electric charge is forcibly discharged from the smoothing capacitor to make the pulsating flow. Then, power supply distortion can be determined more accurately.

  As described above, since the induction heating cooker according to the present invention can detect the distortion of the power supply voltage waveform, it is possible to improve the maintainability by simply monitoring the power supply state and displaying the distortion. It can also be applied to various inverter devices such as air conditioners and lighting.

2 Rectifier circuit 3 Heating coil (Induction heating coil)
4 Inverter circuit 5 Control means 6 Current detection means 7 Power source distortion determination means 8 Voltage detection means 9 Input means 10 Display means

Claims (2)

Induction heating coil you induction heating the pan to generate a high-frequency magnetic field, the induction heating power switching element to coil is a high-frequency current, and an inverter circuit composed of the resonance capacitor, control means for controlling said inverter circuit A rectifier circuit that converts an AC power source, which is a commercial power source, into a direct current, a voltage detection unit that detects a voltage output from the rectifier circuit, a voltage detected by the voltage detection unit, and a power source distortion based on a change amount of the sampled voltage includes a power supply distortion determination unit that only determine the constant, and the power distortion determination input means for start are entered in a display means for displaying the power distortion determination result, the unpleasant Nabeon occurs during cooking If, when the input means is operated to start the power distortion determination, the power distortion determination unit, said control means the high-frequency electric to the induction heating coil While energized, the difference between the data of the voltage that the rectifier circuit is output to the voltage of one cycle is sampled at a predetermined period of the commercial power supply data and voltage sampled in the previous by the voltage detecting means calculated obtains the amount of change in voltage, if the number of occurrences of peaks change amount of the voltage is lowered raised is determined to supply distortion over a predetermined number of times, indicating that is distorted commercial power by the display means Induction heating cooker. The power supply distortion determination means calculates the integrated value of the voltage in the positive phase and the negative phase of the commercial power supply from the output waveform of the voltage detection means when the number of appearances of the peak is less than the predetermined number of times, for each phase. The induction heating cooker according to claim 1, wherein the power source distortion is determined if the difference is equal to or greater than a predetermined value .

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