JP2006079833A - Induction heating cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To change over a power voltage detection level by discriminating a power voltage variation time due to singly occurring thunder or instantaneous power failure from a power voltage variation time such as noise causing little influence and nearly periodically generated. <P>SOLUTION: This induction heating cooker is provided with: a voltage comparison means 10 for comparing a voltage detected by a surge detection means 9 with a surge voltage threshold value; a stop number measurement means 11 for measuring a stop number by a drive stop means 12; and a voltage changeover means 13 for changing over a detection voltage level of the surge detection means 9. When the stop number within a predetermined period is not less than a predetermined value, situations where the cooker can not be used because of being unnecessarily stopped heating can be reduced by changing over the detection voltage level of the surge detection means 9 to a level without stopping the drive. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an induction heating cooker that induction-heats a pan or the like with a magnetic flux of a heating coil by an inverter circuit.

  Conventionally, this type of induction heating cooker has a full-wave rectification of the commercial power supply and a surge voltage detection circuit with a differential voltage configuration and resistance voltage detection at both ends, and detects the steady power supply voltage and the voltage caused by the surge. When an abnormal voltage is detected, the driving operation of the switching element is stopped (for example, see Patent Document 1).

FIG. 5 shows a conventional induction heating cooker described in Patent Document 1. As shown in FIG. Hereinafter, a conventional example will be described with reference to FIG. The diode bridge 102 performs full-wave rectification on the commercial power supply 101, and the smoothing capacitor 103 smoothes the commercial power supply 101 rectified by the diode bridge 102 into a DC power supply. The inverter circuit 104 includes a heating coil 105, a resonant capacitor 106, and a switching element 107 made of IGBT or the like. The drive control means 108 drives and controls the switching element 107, passes a high-frequency current through the heating coil 105, and turns the switching element 107 on and off at a high frequency so as to heat a pan or the like (not shown) as an object to be heated. The surge detecting means 109 detects the voltage of the DC power source smoothed from the commercial power source 101 and comprises a differentiation circuit composed of a capacitor and a resistor. When a surge is applied above the steady voltage, a high voltage is generated in the differentiation circuit. Is output. The voltage comparison unit 110 compares the value detected by the surge detection unit 109 with a predetermined value, and outputs a signal to the drive stop unit 112 when a voltage equal to or higher than the predetermined value is input, and the switching element 107 by the drive control unit 108. The drive was stopped.
Japanese Patent No. 3249294

  However, in the above-described conventional configuration, it is not possible to distinguish between a case where the power supply voltage changes only once due to lightning, an instantaneous power failure, or the like, and a substantially periodic harmonic external noise generated by other devices. Such substantially periodic external noise does not have as much energy as a lightning surge, and even when the driving of the switching element 107 is not stopped, the driving stop means 112 works and heating cooking may stop. . At this time, if the external noise at a level where the device stops is periodic, there is a problem that the device cannot be used while the external noise is superimposed on the commercial power source.

  An object of this invention is to provide the induction heating cooking appliance which reduced the situation where heating cannot be used carelessly and it cannot be used by switching the voltage detection level of a commercial power source.

  In order to solve the conventional problem, the induction heating cooker of the present invention compares a surge detection means for detecting a surge or the like superimposed on a commercial power supply, and a voltage detected by the surge detection means and a surge voltage threshold. Voltage comparison means, a drive stop means for stopping the driving of the switching element when the voltage comparison means determines that the detection voltage by the surge detection means is higher than a surge voltage threshold, and the number of stops by the drive stop means. A stop frequency measuring means for measuring and a voltage switching means for switching the detection voltage level of the power supply voltage detecting means. When the number of stop times exceeds a predetermined number within a predetermined time, the detection level of the voltage detecting means is set by the voltage switching means. It is to be switched.

  As a result, when the stop is repeated more than a predetermined number of times, it is different from the sudden fluctuation of the power supply voltage at the time of lightning surge or instantaneous power failure and recovery from power failure, so that the detection voltage level is not stopped by the voltage switching means By changing to, it is possible to reduce that heating cannot be performed due to periodic external noise or the like.

  Further, a power supply voltage detecting means for detecting the voltage of the commercial power supply, a surge detecting means for detecting a surge or the like superimposed on the commercial power supply, and a voltage comparison for comparing the voltage detected by the surge detecting means with a surge voltage threshold value And a drive stop means for stopping the driving of the switching element when the voltage comparison means determines that the detection voltage by the surge detection means is higher than a surge voltage threshold, and a stop for measuring the number of stops by the drive stop means A number-of-times measuring means and a voltage switching means for switching the detection voltage level of the power supply voltage detection means, wherein the number of stops within a predetermined time is a predetermined number of times or more and the voltage detected by the power supply voltage detection means is a drive voltage When the value is less than the allowable value, the voltage switching means switches the detection level of the surge detection means.

  As a result, the voltage detection level is switched between power supply voltage fluctuations that occur only once due to lightning, instantaneous power outages, etc., and external noises that occur almost periodically, thus reducing the situation where heating is stopped unnecessarily and cannot be used. Can do. In addition, since the voltage detection level is switched only when the drive voltage is less than or equal to the drive voltage permission value, the breakdown prevention level of the device is not lowered so much.

  Further, surge detection means for detecting a surge or the like superimposed on a commercial power supply, voltage comparison means for comparing a voltage detected by the surge detection means and a surge voltage threshold, and detection by the surge detection means by the voltage comparison means A drive stop means for stopping driving of the switching element when it is determined that the voltage is higher than a surge voltage threshold; a stop count measuring means for measuring the number of stops by the drive stop means; and a surge voltage threshold of the voltage comparison means. Comparison threshold switching means for switching, and when the number of stops within a predetermined time is equal to or greater than a predetermined number, the surge threshold voltage is switched by the comparison threshold switching means.

  As a result, the voltage level to be compared by the comparison threshold value switching means is switched between the fluctuation of the power supply voltage that occurs once due to lightning, instantaneous power failure, etc., and the case of external noise that occurs substantially periodically. It is possible to reduce the situation where it cannot be used because it has stopped. Further, the voltage input to the voltage comparison means is reduced to a small signal, and can be realized with an inexpensive configuration.

  Further, a power supply voltage detecting means for detecting the voltage of the commercial power supply, a surge detecting means for detecting a surge or the like superimposed on the commercial power supply, and a voltage comparison for comparing the voltage detected by the surge detecting means with a surge voltage threshold value And a drive stop means for stopping the driving of the switching element when the voltage comparison means determines that the detection voltage by the surge detection means is higher than a surge voltage threshold, and a stop for measuring the number of stops by the drive stop means A number of times measurement means and a comparison threshold value switching means for switching the surge voltage threshold value of the voltage comparison means, the number of stops within a predetermined time is equal to or greater than a predetermined number, and the voltage detected by the power supply voltage detection means is a drive voltage When the value is equal to or less than the allowable value, the surge voltage threshold is switched by the comparison threshold switching means.

  As a result, the voltage level to be compared by the comparison threshold value switching means is switched between the fluctuation of the power supply voltage that occurs once due to lightning, instantaneous power failure, etc., and the case of external noise that occurs substantially periodically. It is possible to reduce the situation where it cannot be used because it has stopped. Further, the voltage input to the voltage comparison means is reduced to a small signal, and can be realized with an inexpensive configuration. In addition, since the voltage detection level is switched only when the drive voltage is less than or equal to the drive voltage permission value, the breakdown prevention level of the device is not lowered so much.

  The induction heating cooker according to the present invention switches the voltage detection level between a single fluctuation of the power supply voltage caused by lightning, a momentary power failure, etc., and an external noise that occurs almost periodically with little influence. It is possible to reduce the situation where it cannot be used because it has stopped.

  The first invention includes an inverter circuit including a heating coil, a resonant capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, and surge detection means for detecting a surge superimposed on a commercial power source. And a voltage comparison means for comparing the voltage detected by the surge detection means with a surge voltage threshold, and the switching element when the voltage comparison means determines that the detection voltage by the surge detection means is higher than the surge voltage threshold. Drive stop means for stopping the drive, stop number measuring means for measuring the number of stops by the drive stop means, and voltage switching means for switching the detection voltage level of the surge detection means, the number of stops within a predetermined time is If the predetermined number of times or more, the voltage switching means detects the voltage level detected by the surge detection means. By switching, the voltage detection level is switched to a level that does not stop the drive in the case of external noise that occurs almost periodically, and in the case of external noise that occurs almost periodically due to lightning, instantaneous power failure, etc. It is possible to reduce the situation where the heating is stopped and cannot be used.

  The second invention includes an inverter circuit including a heating coil, a resonant capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, power supply voltage detection means for detecting the voltage of a commercial power supply, A surge detection means for detecting a surge or the like superimposed on a commercial power source, a voltage comparison means for comparing a voltage detected by the surge detection means with a surge voltage threshold, and a voltage detected by the surge detection means by the voltage comparison means. Switching between the drive stop means for stopping the driving of the switching element, the stop count measuring means for measuring the number of stops by the drive stop means, and the detection voltage level of the surge detection means when judged to be higher than the surge voltage threshold Voltage switching means, the number of stops within a predetermined time is equal to or greater than a predetermined number, and the power supply When the voltage detected by the detection means is less than or equal to the drive voltage allowable value, by switching the detection level of the surge detection means by the voltage switching means, the power supply voltage fluctuations that occur one time due to lightning or instantaneous power failure, and Since the voltage detection level is switched in the case of external noise generated approximately periodically, it is possible to reduce the situation where heating is stopped unnecessarily and cannot be used. In addition, since the voltage detection level is switched only when the drive voltage is less than or equal to the drive voltage permission value, the breakdown prevention level of the device is not lowered so much.

  In the third invention, in particular, the voltage level switched by the voltage switching means of the first or second invention works to lower the detection voltage input to the voltage comparison means, and the external level generated more periodically. Heating stop due to noise malfunction can be reduced.

  In the fourth invention, in particular, the switching element is driven by the drive control means in a state where the detection level of the surge detection means is switched by the voltage switching means of any one of the first to third inventions, and the driving is performed for a predetermined time. When the drive is not stopped by the stopping means, the detection level switched by the voltage switching means is returned to the initial level, and when the external noise is reduced, it can be returned to the same destruction prevention level as usual. Protection against a single surge can be maintained.

  According to a fifth aspect of the present invention, there is provided an inverter circuit including a heating coil, a resonance capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, and surge detection means for detecting a surge superimposed on a commercial power source. And a voltage comparison means for comparing the voltage detected by the surge detection means with a surge voltage threshold, and the switching element when the voltage comparison means determines that the detection voltage by the surge detection means is higher than the surge voltage threshold. Drive stop means for stopping the drive, stop number measuring means for measuring the number of stops by the drive stop means, and comparison threshold switching means for switching the surge voltage threshold of the voltage comparison means, and the number of stops within a predetermined time Is switched over the predetermined number of times, the surge voltage threshold is switched by the comparison threshold switching means. Since the voltage level compared by the comparison threshold value switching means is switched between the fluctuation of the power supply voltage that occurs once due to lightning or instantaneous power failure, and the case of external noise that occurs almost periodically, it is heated unnecessarily. It is possible to reduce the situation where it cannot be used because it has stopped. Further, the voltage input to the voltage comparison means is reduced to a small signal, and can be realized with an inexpensive configuration.

  The sixth invention includes an inverter circuit including a heating coil, a resonant capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, power supply voltage detection means for detecting the voltage of a commercial power supply, A surge detection means for detecting a surge or the like superimposed on a commercial power source, a voltage comparison means for comparing a voltage detected by the surge detection means with a surge voltage threshold, and a voltage detected by the surge detection means by the voltage comparison means. Switching between the drive stop means for stopping the driving of the switching element, the stop count measuring means for measuring the stop count by the drive stop means, and the surge voltage threshold of the voltage comparison means when it is determined that the surge voltage threshold is higher than the surge voltage threshold. A comparison threshold value switching means, wherein the number of stops within a predetermined time is a predetermined number of times or more and the power source When the voltage detected by the pressure detection means is less than or equal to the drive voltage permission value, the surge voltage threshold is switched by the comparison threshold switching means, and the power supply voltage fluctuation that occurs once due to lightning or instantaneous power failure, Since the voltage level compared by the comparison threshold value switching means is switched in the case of external noise generated approximately periodically, it is possible to reduce the situation where heating is stopped unnecessarily and cannot be used. Further, the voltage input to the voltage comparison means is reduced to a small signal, and can be realized with an inexpensive configuration. In addition, since the voltage detection level is switched only when the drive voltage is less than or equal to the drive voltage permission value, the breakdown prevention level of the device is not lowered so much.

  The seventh aspect of the invention is particularly the invention of any one of the fifth and sixth aspects, wherein the switching of the surge voltage threshold value of the comparison detection means by the comparison threshold value switching means switches the threshold level to a higher voltage, and is more periodic. It is possible to reduce the heating stop due to the malfunction due to the external noise generated in the.

  In the eighth invention, in particular, the switching element is driven by the drive control means in a state where the surge voltage threshold of the comparison detection means is switched by the comparison threshold switching means of any one of the fifth to seventh inventions, and the predetermined threshold When the drive stop by the time drive stop means is not performed, the threshold level switched by the comparison threshold switching means is returned to the initial value, and when the external noise is reduced, it can be returned to the same destruction prevention level as usual. Therefore, protection against a single surge can be maintained.

  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 configuration diagram of an induction heating cooker according to the first embodiment of the present invention. This will be described below with reference to FIG.

  The diode bridge 2 performs full-wave rectification on the commercial power supply 1, and the smoothing capacitor 3 smoothes the commercial power supply 1 rectified by the diode bridge 2 to obtain a DC power supply. The inverter circuit 4 includes a heating coil 5, a resonant capacitor 6, and a switching element 7 made of IGBT or the like. The drive control means 8 drives and controls the switching element 7, passes a high-frequency current through the heating coil 5, and turns the switching element 7 on and off at a high frequency so as to heat a pan or the like (not shown) as an object to be heated. The surge detection means 9 detects a surge superimposed on the commercial power source 1 and outputs Vs which is a divided voltage of Vin. When the Vin voltage jumps suddenly, such as a surge, a differential circuit composed of C1 and R2 Can capture the change. The voltage comparison means 10 compares the reference Vref voltage with the output voltage Vs from the surge detection means 9, and sends a stop signal to the drive stop means 12 if Vs> Vref. The drive stop means 12 receives the signal from the voltage comparison means 10 and stops the control of the switching element 7 by the drive control means 8. The stop count measuring means 11 measures the number of times the operation is stopped by the drive stop means 12 in a predetermined time, and if it is equal to or greater than the predetermined number of times, the voltage switching means 13 such as a relay switches the connection of C2.

  Normally, the connection of C2 by the voltage switching means 13 is ON, that is, C1 and C2 are connected in parallel, and the differentiation becomes easier to work by increasing the capacity of the capacitor constituting the differentiation circuit of the surge detection means 9. This makes it easy to detect fluctuations in the power source Vin due to a surge that occurs once.

  Here, for example, when the same commercial power source 1 is connected to another switching power source device, a capacitor input device such as an air conditioner, or a phase control device such as a vacuum cleaner or a bag, the input waveform of the commercial power source 1 is displayed. When periodic noise occurs, the differentiation circuit of the surge detection means 9 detects the noise, and Vs periodically increases. As a result, Vref of the voltage comparison means 10 (for example, equivalent to the superimposed voltage 350V). ) As described above, for example, the superimposed voltage may be approximately 360V. In this case, the heating is stopped by the drive stopping means 12 almost in synchronization with the external noise. The stop count measuring means 11 measures the drive stop count for a predetermined time (for example, 1 minute), and if the drive stop count is equal to or greater than the predetermined count (for example, 10 count or more), the voltage switching means 13 disconnects C2. . As a result, the capacitance of the capacitor constituting the differentiating circuit is reduced, so that the action of the differentiation is suppressed. That is, even at the same voltage fluctuation level, the voltage Vs output by the surge detection means 9 is a low voltage. Thereby, the case where heating stops and becomes unusable due to periodic external noise or the like different from surge can be reduced.

  Furthermore, if periodic noise is superimposed due to the influence of other equipment, the use of the other equipment may be terminated, so heating is continued with the capacitor C2 disconnected by the voltage switching means 13. In this case, the voltage switching means 13 connects the capacitor C2 after a predetermined time (approximately 15 minutes, for example, in a range not affecting cooking). As a result, when the external noise that stops the heating is already removed, the operation level of the original differential is obtained, and the device can be protected more safely against a single surge or the like. Further, even when the heating is once stopped by the user, the initial state in which the capacitor C2 is connected is returned. As a result, the surge detection level is lowered only when periodic external noise is superimposed on the commercial power supply 1 and heating is not possible. In other cases, the surge can be detected to keep the device protected. Is possible.

  In the present embodiment, the voltage switching means is the switching of capacitors connected in parallel, but the same effect can be obtained by connecting capacitors in series or switching the voltage dividing ratio of resistors.

  In this embodiment, the inverter circuit is a monolithic voltage resonance inverter. However, in a full-bridge or half-bridge inverter, the same configuration can be used as a protection circuit against a surge superimposed on the commercial power source 1. Similar effects can be obtained.

(Embodiment 2)
FIG. 2 is a configuration diagram of the induction heating cooker according to the second embodiment of the present invention. In addition, the same number is provided about the structure shown in Embodiment 1, and only a different structure is demonstrated.

  A power supply voltage detection means 14 constituted by resistance voltage division, a band-pass filter 15 that passes about 100 Hz, which is approximately twice the frequency of the commercial power supply 1, and a logic comparator 16 are provided to the output. Vin is detected, and further, the voltage Vin of the commercial power source 1 is detected through the band-pass filter 15. Both of the voltage range in which Vin does not cause a problem even if the normal device is operated in the logical comparator 16 and the switching condition that the number of times of driving stop by the stop number measuring means 11 is periodic are satisfied. In such a case, the voltage switching means 13 switches the connection of the capacitor C2.

  As a result, the surge detection level is switched only in the voltage range where there is no problem even if the normal device is operated, so that the breakdown prevention level of the device is not lowered much.

  In the present embodiment, the voltage switching means 13 is switched between capacitors connected in parallel, but the same effect can be obtained by connecting capacitors in series or switching the voltage dividing ratio of resistors.

  In this embodiment, the inverter circuit is a monolithic voltage resonance inverter. However, in a full-bridge or half-bridge inverter, the same configuration can be used as a protection circuit against a surge superimposed on the commercial power source 1. Similar effects can be obtained.

(Embodiment 3)
FIG. 3 is a configuration diagram of an induction heating cooker according to the third embodiment of the present invention. This will be described below with reference to FIG.

  The diode bridge 2 performs full-wave rectification on the commercial power supply 1, and the smoothing capacitor 3 smoothes the commercial power supply 1 rectified by the diode bridge 2 to obtain a DC power supply. The inverter circuit 4 includes a heating coil 5, a resonant capacitor 6, and a switching element 7 made of IGBT or the like. The drive control means 8 drives and controls the switching element 7, passes a high-frequency current through the heating coil 5, and turns the switching element 7 on and off at a high frequency so as to heat a pan or the like (not shown) as an object to be heated. The surge detection means 9 detects a surge superimposed on the commercial power source 1 and outputs Vs which is a divided voltage of Vin. When the Vin voltage jumps suddenly such as a surge, the differential composed of C1 and R2 The change can be caught by the circuit. The voltage comparison means 10 compares the reference Vref voltage with the output voltage Vs from the surge detection means 9, and sends a stop signal to the drive stop means 12 if Vs> Vref. The drive stop means 12 receives the signal from the voltage comparison means 10 and stops the control of the switching element 7 by the drive control means 8. The stop count measuring means 11 measures the number of times the operation is stopped by the drive stop means 12 for a predetermined time, and if it is equal to or greater than the predetermined number, the comparison threshold switching means 17 switches the connection of R6.

  The connection of R6 by the normal comparison threshold switching means 17 is off, that is, Vref is determined only by the partial pressure of R4 and R5. Here, R6 has a smaller resistance value than R4. When R6 is connected by the comparison threshold value switching means 17, the combined resistance of R4 and R6 becomes small.

  Here, for example, when another switching power supply device, a capacitor input device, a phase control device, etc. are connected to the same commercial power source 1, if periodic noise occurs in the input waveform of the commercial power source 1, the differential circuit of the surge detection means 9. However, there are cases where the noise is detected and Vs increases periodically, resulting in Vref of the voltage comparison means 11 or more. In this case, the heating is stopped by the drive stopping means 12 almost in synchronization with the external noise. The stop number measuring means 11 measures the number of times of driving stop for a predetermined time (for example, 1 minute), and if the number of times of driving stop is equal to or larger than the predetermined number of times (for example, 10 times or more), the comparison threshold switching means 17 sets R6. Connecting. As a result, the reference voltage Vref of the voltage comparison unit 13 becomes high and it is difficult to satisfy Vs> Vref, and the voltage comparison unit 10 can suppress sending a stop signal to the drive stop unit 12. Thereby, the case where heating stops and becomes unusable due to periodic external noise or the like different from surge can be reduced. Further, since the switching of R6 is a small signal, it can be performed with an inexpensive transistor or the like.

  Further, when periodic noise is superimposed due to the influence of other equipment, the use of the other equipment may be terminated after that, and the influence of the periodic noise may be eliminated. When heating is continued with the resistor R6 connected at 17, the comparison threshold switching means 17 disconnects the resistor R6 after a predetermined time (approximately 15 minutes in a range that does not affect cooking, for example). As a result, when the external noise that stops the heating is already removed, the operation level of the original differential is obtained, and the device can be protected more safely against a single surge or the like. Moreover, even if heating is once stopped by the user, the initial state in which the resistor R6 is not connected is returned. As a result, the surge detection level is lowered only when periodic external noise is superimposed on the commercial power supply 1 and heating is not possible. In other cases, the surge can be detected to keep the device protected. Is possible.

  Note that the switching of the surge threshold is for switching the reference voltage Vref of the voltage comparison means 10, and there is no change even in the configuration of connection of resistors or connection switching on the R5 side.

  In this embodiment, the inverter circuit is a monolithic voltage resonance inverter. However, in a full-bridge or half-bridge inverter, the same configuration can be used as a protection circuit against a surge superimposed on the commercial power source 1. Similar effects can be obtained.

(Embodiment 4)
FIG. 4 is a configuration diagram of an induction heating cooker according to the fourth embodiment of the present invention. In addition, the same number is given about the structure shown in Embodiment 3, and only a different structure is demonstrated.

  A power supply voltage detection means 14 constituted by resistance voltage division, a band-pass filter 15 that passes about 100 Hz, which is approximately twice the frequency of the commercial power supply 1, and a logic comparator 16 are provided to the output. Vin is detected, and further, the voltage Vin of the commercial power source 1 is detected through the band-pass filter 15. Both of the voltage range in which Vin does not cause a problem even if a normal device is operated in the logical comparator 16 and the switching condition that the number of drive stops for a predetermined time by the stop number measurement cut-off means 11 is periodic are satisfied. In this case, the connection of the resistor R6 is switched by the comparison threshold switching means 17.

  As a result, the surge detection level is switched only in the voltage range where there is no problem even if the normal device is operated, so that the breakdown prevention level of the device is not lowered much.

  Note that the switching of the surge threshold is for switching the reference voltage Vref of the voltage comparison means 10, and there is no change even if it is a resistor connection or a connection switching configuration on the R5 side.

  In this embodiment, the inverter circuit is a monolithic voltage resonance inverter. However, in a full-bridge or half-bridge inverter, the same configuration can be used as a protection circuit against a surge superimposed on the commercial power source 1. Similar effects can be obtained.

  As described above, the induction heating cooker according to the present invention switches the voltage detection level between the fluctuation of the power supply voltage caused by lightning, a momentary power failure, etc., and the external noise that occurs almost periodically. It is possible to reduce the situation where the heating is stopped and cannot be used.

The block diagram of the induction heating cooking appliance in Embodiment 1 of this invention The block diagram of the induction heating cooking appliance in Embodiment 2 of this invention The block diagram of the induction heating cooking appliance in Embodiment 3 of this invention The block diagram of the induction heating cooking appliance in Embodiment 4 of this invention Configuration diagram of a conventional induction heating cooker

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Commercial power supply 4 Inverter circuit 5 Heating coil 6 Resonance capacitor 7 Switching element 8 Drive control means 9 Surge detection means 10 Voltage comparison means 11 Stop frequency measurement means 12 Drive stop means 13 Voltage switching means 14 Power supply voltage detection means 17 Comparison threshold value switching means 17

Claims (8)

An inverter circuit including a heating coil, a resonance capacitor, and a switching element; drive control means for driving and controlling the switching element of the inverter circuit; surge detection means for detecting a surge superimposed on a commercial power supply; and the surge detection means Voltage comparing means for comparing the voltage detected by the surge voltage threshold and a drive for stopping the driving of the switching element when the voltage comparing means determines that the detected voltage by the surge detecting means is higher than the surge voltage threshold A stop means, a stop count measuring means for measuring the number of stops by the drive stop means, and a voltage switching means for switching the detection voltage level of the surge detection means, and when the number of stops within a predetermined time is equal to or greater than a predetermined number Induction for switching the detection voltage level of the surge detection means by the voltage switching means Heat cooker. An inverter circuit including a heating coil, a resonant capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, power supply voltage detection means for detecting the voltage of a commercial power supply, and superimposed on the commercial power supply A surge detection means for detecting a surge or the like; a voltage comparison means for comparing a voltage detected by the surge detection means with a surge voltage threshold; and a voltage detected by the surge detection means by the voltage comparison means is higher than the surge voltage threshold. Drive stop means for stopping the driving of the switching element when it is determined, stop number measurement means for measuring the number of stops by the drive stop means, and voltage switching means for switching the detection voltage level of the surge detection means. The number of stops within a predetermined time is a predetermined number of times or more and the power supply voltage detecting means If knowledge the voltage is less than the driving voltage allowed value, the induction heating cooker to switch the detection level of said surge detecting means by the voltage switching means. The induction heating cooker according to claim 1 or 2, wherein the voltage level switched by the voltage switching means acts to lower the detection voltage input to the voltage comparison means. When the switching element is driven by the drive control means while the detection level of the surge detection means is switched by the voltage switching means, and the drive stop by the drive stop means is not performed for a predetermined time, the detection switched by the voltage switching means The induction heating cooker according to any one of claims 1 to 3, wherein the level is returned to the initial level. An inverter circuit including a heating coil, a resonance capacitor, and a switching element; drive control means for driving and controlling the switching element of the inverter circuit; surge detection means for detecting a surge superimposed on a commercial power supply; and the surge detection means Voltage comparing means for comparing the voltage detected by the surge voltage threshold and a drive for stopping the driving of the switching element when the voltage comparing means determines that the detected voltage by the surge detecting means is higher than the surge voltage threshold A stop means, a stop count measuring means for measuring the number of stops by the drive stop means, and a comparison threshold switching means for switching a surge voltage threshold of the voltage comparison means, wherein the number of stops within a predetermined time is greater than or equal to a predetermined number Is an induction heating cooker that switches the surge voltage threshold by the comparison threshold switching means An inverter circuit including a heating coil, a resonant capacitor, and a switching element, drive control means for driving and controlling the switching element of the inverter circuit, power supply voltage detection means for detecting the voltage of a commercial power supply, and superimposed on the commercial power supply A surge detection means for detecting a surge or the like; a voltage comparison means for comparing a voltage detected by the surge detection means with a surge voltage threshold; and a voltage detected by the surge detection means by the voltage comparison means is higher than the surge voltage threshold. Drive stop means for stopping the driving of the switching element when it is determined, stop number measuring means for measuring the number of stops by the drive stop means, and comparison threshold switching means for switching the surge voltage threshold of the voltage comparison means Provided, the number of stops within a predetermined time is equal to or greater than a predetermined number, and the power supply voltage detecting means If the detected voltage is less than the driving voltage allowed value, the induction heating cooker to switch the surge voltage threshold by the comparison threshold value switching means. The induction heating cooker according to claim 5 or 6, wherein switching of the surge voltage threshold of the comparison detection means by the comparison threshold switching means switches the threshold level to a high voltage. When the switching element is driven by the drive control means while the surge voltage threshold value of the comparison detection means is switched by the comparison threshold switching means and the drive stop means is not stopped for a predetermined time, the comparison threshold switching means The induction heating cooker according to any one of claims 5 to 7, wherein the switched threshold level is returned to the initial value.

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