JP4193154B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that supplies a high-frequency voltage to an induction heating coil, heats a cooking pan by electromagnetic induction, and heats an object to be heated in the cooking pan.

  FIG. 4 is a circuit configuration diagram showing a conventional induction heating cooker disclosed in Patent Document 1, for example. In FIG. 4, 1 is a commercial AC power source, 2 is a rectifier circuit for rectifying an AC voltage from the commercial AC power source 1, and 3 is a smoothing circuit comprising a choke coil 4 and a capacitor 5 for smoothing the voltage output from the rectifier circuit 2. , 6 is an inverter circuit composed of switching elements 6a, 6b, 6c, 6d, and 7-10 are diodes connected to both ends of each switching element. 11 is an induction heating coil connected between the connection point of the switching elements 6a and 6b and the connection point of the switching elements 6c and 6d, 12 is a current sensor connected to one of the induction heating coils 11, and 13 is the induction heating coil 11. 14 is a pan material discriminating circuit for discriminating, for example, a magnetic pan made of iron, stainless steel or the like and a nonmagnetic pan made of nonmagnetic metal based on the detection value of the current sensor 12, and 15 is a pan material discriminating circuit. Switching means for switching the circuit system of the inverter drive circuit 16 that controls the drive of the inverter circuit 6 based on the determination result of the material determination circuit 14.

  Next, operation | movement of the induction heating cooking appliance which has such a structure is demonstrated using FIG. 4 together. When the pan is placed on the plate (not shown) of the induction heating cooker and the cooking operation is started, a high-frequency current flows through the induction heating coil 11 by ON / OFF driving of the switching elements 6a and 6b. It is detected by the current sensor 12. And the pan material discrimination | determination circuit 14 discriminate | determines that it is a magnetic pan when the detection current of the current sensor 12 is below a predetermined value, and discriminate | determines that it is a non-magnetic pan when it exceeds a predetermined value. Next, when the pan material discriminating circuit 14 discriminates that it is a magnetic pan, the switching means 15 turns on the switching elements 6a and 6d at the same time, and thereafter turns on the switching elements 6b and 6c at the same time. A circuit is formed, and the circuit system of the inverter drive circuit 16 is switched so that the first high-frequency voltage is supplied to the induction heating coil 11.

  Thereby, the to-be-heated object in a magnetic pan is cooked by the electromagnetic induction effect | action of the induction heating coil 11. FIG. When the pan material discrimination circuit 14 determines that the pan is a non-magnetic pan, the switching means 15 turns on only the switching element 6a and then turns on only the switching element 6b, that is, forms a half bridge circuit. The circuit system of the inverter drive circuit 16 is switched so that the second high-frequency voltage is supplied to the induction heating coil 11. Thereby, the to-be-heated object in a nonmagnetic pan is heat-cooked with the heating mechanism similar to the above-mentioned. At this time, the switching element 6c is always OFF and 6d is always ON. Note that it is assumed that the magnitude of the first high-frequency voltage generated by the full-bridge circuit is equivalent to twice the second high-frequency voltage generated by the half-bridge circuit. Furthermore, since the resistivity is low in the case of a non-magnetic pan, the frequency of the high-frequency voltage applied to the induction heating coil 11 is increased because the power consumption required to sufficiently heat the pan by electromagnetic induction does not occur. To improve power consumption.

JP-A-5-251172 (FIGS. 1 and 2, paragraphs [0027] to [0031])

  A conventional induction heating cooker discriminates between a magnetic pan and a non-magnetic pan by a pan material discrimination circuit, and is provided with a switching means for switching between a full bridge circuit and a half bridge circuit based on the discrimination result, An attempt is made to keep the energizing power constant regardless of the pot material. In the case of a non-magnetic pan, the frequency of the high-frequency voltage applied to the induction heating coil 11 is set high because the power consumption required to sufficiently heat the pan by electromagnetic induction does not occur. However, in the case of a nonmagnetic pan with a low resistivity, by not adopting a method of shifting the resonance frequency of the resonance circuit composed of the induction heating coil and the resonance capacitor to the frequency side of the high frequency current flowing through the induction heating coil, It is impossible to set the power consumption to an appropriate value. Therefore, there is a problem that the object to be heated in the non-magnetic pan cannot be cooked properly.

  The present invention was made to solve the above-described problems, and accurately discriminates between a magnetic pan and a non-magnetic pan, and a high-frequency current having an appropriate frequency for the induction heating coil according to the discrimination result. It is an object of the present invention to obtain an induction heating cooker that appropriately heats an object to be heated.

  The induction heating cooker according to the present invention converts a DC voltage of a commercial power source into a DC voltage via a rectifier circuit, converts a DC voltage from the DC voltage conversion means into a high frequency voltage, In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements applied to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and the cooking pan is a magnetic pot Alternatively, the pan material discriminating means for discriminating whether the pan is a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the switching arm and the second switching arm, and second switching A pair of resonance capacitors, one end of which is connected to the output of each of the second switching arms and the other end of which is connected to one end of the induction heating coil. A series resonance circuit is constituted by a coil, the other end of the induction heating coil is connected to the output of the first switching arm, and the control means is used when the discrimination result of the pan material discrimination means is a nonmagnetic pan of nonmagnetic stainless steel. Selects two second switching arms, always turns on the negative side switching elements of the two selected second switching arms, always turns on the positive side switching elements, and turns off the first arm. ON / OFF drive.

An induction heating cooker according to the present invention converts a DC voltage of a commercial power source into a DC voltage via a rectifier circuit, converts a DC voltage from the DC voltage converter to a high frequency voltage, In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements for applying a voltage to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, The pan material discriminating means for discriminating between the magnetic pan and the non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the first switching arm and the second switching arm; A pair of resonant capacitors provided for each switching arm, having one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil. A series resonance circuit is constituted by a coil, the other end of the induction heating coil is connected to the output of the first switching arm, and the control means is when the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan. Selects one second switching arm, always turns on the negative side switching element of the selected second switching arm, always turns off the positive side switching element, and selects the second switching arm that is not selected. The switching element on the negative electrode side and the switching element on the positive electrode side of the switching arm are always OFF-driven, and the first arm is ON / OFF-driven. It is intended.
The induction heating cooker according to the present invention converts a DC voltage from a commercial power source into a DC voltage via a rectifier circuit, and converts the DC voltage from the DC voltage converter into a high-frequency voltage. In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements for applying the high-frequency voltage to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and cooking The pan material discriminating means for discriminating whether the pan is a magnetic pan or a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF drive of each switching element of the first switching arm and the second switching arm, Provided for each second switching arms, one end connected to the respective outputs of the second switching arm comprises a pair of resonant capacitor whose other end is connected to one end of the induction heating coil, and a pair of resonant capacitor form a series resonant circuit with the induction heating coil, the other end of the induction heating coil is connected to the output of the first switching arm, the control means determines the result of the pot material determining means of two in the case of the magnetic pan The second switching arm is selected, the two selected second switching arms and the first arm are simultaneously driven at the first frequency, and the discrimination result of the pan material discrimination means is non-magnetic aluminum / copper. In the case of a pan, one second switching arm is selected, and the switching element on the negative side of the selected one second switching arm is always turned ON, and the positive side The switching element constantly OFF operation, the negative side switching elements of the switching elements and the positive electrode side and OFF-driven, the second frequency different from the first arm first frequency of the second switching arm is not selected ON / OFF drive.

The induction heating cooker according to the present invention converts a DC voltage from a commercial power source into a DC voltage via a rectifier circuit, and converts the DC voltage from the DC voltage converter into a high-frequency voltage. In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements for applying the high-frequency voltage to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and cooking The pan material discriminating means for discriminating whether the pan is a magnetic pan or a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF drive of each switching element of the first switching arm and the second switching arm, A pair of resonant capacitors, one end connected to each output of the second switching arm and the other end connected to one end of the induction heating coil. The induction heating coil constitutes a series resonance circuit, the other end of the induction heating coil is connected to the output of the first switching arm, and the control means is a nonmagnetic stainless steel nonmagnetic pot whose discrimination result is nonmagnetic stainless steel. In this case, two second switching arms are selected, the negative side switching elements of the two selected second switching arms are always ON driven, the positive side switching elements are always OFF driven, and the first When the disc material discriminating means is a non-magnetic pan of aluminum / copper, one second switching is performed. The switching element on the negative side of the selected second switching arm is always ON, the switching element on the positive side is always OFF, and the first arm is set to the first frequency. Is ON / OFF driven at a different second frequency.
The induction heating cooker according to the present invention includes a DC voltage converting means for converting an AC voltage of a commercial power source into a DC voltage via a rectifier circuit, and a plurality of DC voltages from the DC voltage converting means for converting to a high frequency voltage. In an induction heating cooker provided with an inverter circuit composed of switching elements, the inverter circuit is composed of a first switching arm and two second switching arms, and the cooking pan is either a magnetic pan or a non-magnetic pan. Pan material discriminating means for discriminating between the first switching arm and the second switching arm so as to control the magnitude and frequency of the high frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discriminating means Control means for controlling the ON / OFF drive of each switching element, and one end connected to the output of the first switching arm And the oscillation capacitor,
A pair of induction heating coils provided for each second switching arm, having one end connected to the respective output of the second switching arm and the other end connected to the other end of the resonance capacitor , constituting a one-port type heating source A series resonance circuit is constituted by a pair of induction heating coils and a resonance capacitor. When the determination result of the pot material determination means is a magnetic pot , the control means selects a full bridge circuit and determines the pot material If the result of the determination is a nonmagnetic stainless steel nonmagnetic pan or an aluminum / copper nonmagnetic pan , at least one of the two second switching arms to select the half bridge circuit , and the first The arm is driven ON / OFF.

  According to the present invention, the DC voltage converting means for converting the AC voltage of the commercial power source into the DC voltage via the rectifier circuit, the DC voltage from the DC voltage converting means is converted into the high frequency voltage, and the high frequency voltage is converted into the induction heating coil. In an induction heating cooker including an inverter circuit composed of a plurality of switching elements to be applied, the inverter circuit is constituted by a first switching arm and two second switching arms, and the cooking pan is a magnetic pan or a non-magnetic pan. Pan material discriminating means for discriminating between the first switching arm and the first switching arm so as to control the magnitude and frequency of the high frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the second switching arm, and provided for each second switching arm. A pair of resonant capacitors having one end connected to the respective outputs of the second switching arm and the other end connected to one end of the induction heating coil. A series resonant circuit is formed by the pair of resonance capacitors and the induction heating coil. And the other end of the induction heating coil is connected to the output of the first switching arm, and the control means has two second ones when the discrimination result of the pan material discrimination means is a non-magnetic stainless steel non-magnetic pan. Since the switching arm is selected, the switching elements on the negative side of the two selected second switching arms are always driven ON, the switching element on the positive side is driven OFF, and the first arm is driven ON / OFF. The same heating power is applied to the pan made of nonmagnetic material of nonmagnetic stainless steel by setting the magnitude of the high frequency current flowing in the induction heating coil to the maximum. An object to be heated of the inner can be properly cooked.

Further, according to the present invention, the DC voltage converting means for converting the AC voltage of the commercial power source into the DC voltage through the rectifier circuit, the DC voltage from the DC voltage converting means is converted into the high frequency voltage, and the high frequency voltage is converted into the high frequency voltage. In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements applied to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and the cooking pan is a magnetic pot Alternatively, the pan material discriminating means for discriminating whether the pan is a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the switching arm and the second switching arm, and a second switch A pair of resonance capacitors provided for each arm, one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil, and the pair of resonance capacitor and induction heating coil The other end of the induction heating coil is connected to the output of the first switching arm, and the control means is a non-magnetic pot of aluminum / copper when the determination result of the pot material determination means is One second switching arm is selected, the switching element on the negative electrode side of the selected second switching arm is always ON-driven, the switching element on the positive electrode side is always OFF-driven, and the second non-selected second switching arm is selected. Since the switching element on the negative electrode side and the switching element on the positive electrode side of the switching arm are always driven OFF and the first arm is driven ON / OFF, For a pan made of non-magnetic material of copper / mi / copper, set the maximum amount of high-frequency current flowing in the induction heating coil to give the same heating power, and cook the heated object in this pan appropriately. Can do.
Further, according to the present invention, the DC voltage converting means for converting the AC voltage of the commercial power source into the DC voltage through the rectifier circuit, the DC voltage from the DC voltage converting means is converted into the high frequency voltage, and the high frequency voltage is converted into the high frequency voltage. In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements applied to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and the cooking pan is a magnetic pot Alternatively, the pan material discriminating means for discriminating whether the pan is a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the switching arm and the second switching arm, and a second switch Provided for each arm, one end connected to the respective outputs of the second switching arm comprises a pair of resonant capacitor whose other end is connected to one end of the induction heating coil, the induction heating coil and a pair of resonant capacitor in form a series resonant circuit, the other end of the induction heating coil is connected to the output of the first switching arm, the control means, the pot material discriminating means discriminating result the second of the two in the case of the magnetic pan When a switching arm is selected, the two selected second switching arms and the first arm are simultaneously driven at the first frequency, and the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan In this case, one second switching arm is selected, and the switching element on the negative electrode side of the selected one second switching arm is always turned on to switch the switching element on the positive electrode side. The constantly OFF driving, constantly OFF drives the switching element on the negative electrode side switching element and the positive side of the second switching arm is not selected, ON at a second frequency different from the first arm first frequency / Since it is driven OFF, the same heating power is applied to the pan made of non-magnetic material of aluminum / copper by setting the magnitude of the high-frequency current flowing through the induction heating coil to the maximum. Can be cooked in the heat.

Further, according to the present invention, the DC voltage converting means for converting the AC voltage of the commercial power source into the DC voltage through the rectifier circuit, the DC voltage from the DC voltage converting means is converted into the high frequency voltage, and the high frequency voltage is converted into the high frequency voltage. In an induction heating cooker comprising an inverter circuit composed of a plurality of switching elements applied to an induction heating coil, the inverter circuit is composed of a first switching arm and two second switching arms, and the cooking pan is a magnetic pot Alternatively, the pan material discriminating means for discriminating whether the pan is a non-magnetic pan, and the magnitude and frequency of the high frequency voltage applied to the induction heating coil are controlled based on the discrimination result of the pan material discriminating means. Control means for controlling ON / OFF driving of each switching element of the switching arm and the second switching arm, and a second switch A pair of resonance capacitors provided for each arm, one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil, and the pair of resonance capacitor and induction heating coil The other end of the induction heating coil is connected to the output of the first switching arm, and the control means is a nonmagnetic stainless steel nonmagnetic pan when the discrimination result of the pan material discrimination means is Two second switching arms are selected, the switching elements on the negative side of the two selected second switching arms are always turned on, the switching elements on the positive side are always turned off, and the first arm is turned on. ON / OFF drive at the first frequency, if the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan, select one second switching arm, The switching element on the negative electrode side of one selected second switching arm is always ON-driven, the switching element on the positive electrode side is always OFF-driven, and the first arm has a second frequency different from the first frequency. Because it is ON / OFF driven, the same heating power is applied to the pan made of non-magnetic material of aluminum / copper by setting the magnitude of the high-frequency current flowing in the induction heating coil to the maximum. Things can be cooked properly.
In addition, according to the present invention, it comprises a DC voltage converting means for converting an AC voltage of a commercial power source into a DC voltage via a rectifier circuit, and a plurality of switching elements for converting the DC voltage from the DC voltage converting means into a high frequency voltage. In an induction heating cooker provided with an inverter circuit, the inverter circuit is composed of a first switching arm and two second switching arms, and determines whether the cooking pan is a magnetic pan or a non-magnetic pan. Each of the switching elements of the first switching arm and the second switching arm so as to control the magnitude and frequency of the high frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discrimination means and the pan material discrimination means A control means for controlling ON / OFF driving of the power supply, a resonance capacitor having one end connected to the output of the first switching arm, Provided for each second switching arms, one end connected to the respective outputs of the second switching arm, the other end is connected to the other end of the resonance capacitor, a pair of induction heating coils which constitute the heat source bite type A series resonance circuit is constituted by a pair of induction heating coils and a resonance capacitor. When the determination result of the pot material determination means is a magnetic pot , the control means selects a full bridge circuit and determines the pot material If the result of the determination is a nonmagnetic stainless steel nonmagnetic pan or an aluminum / copper nonmagnetic pan , at least one of the two second switching arms to select the half bridge circuit , and the first Since the arm is driven ON / OFF, induction heating coils are used for pans made of magnetic materials such as iron and stainless steel and pans made of nonmagnetic materials such as aluminum and copper. Flows give the same heating power is set to the maximum magnitude of the high frequency current, an object to be heated in their pots can be appropriately cooked.

Embodiment 1 FIG.
1 shows a circuit configuration diagram according to Embodiment 1 of an induction heating cooker. In FIG. 1, the same reference numerals as in the conventional example indicate the same or corresponding parts. Reference numeral 17 denotes a first switching arm composed of the switching elements 17a and 17b, 18 denotes a second switching arm composed of the switching elements 18a and 18b, and 19 denotes a third switching arm composed of the switching elements 19a and 19b. Reference numeral 20 denotes a first resonance capacitor connected via the induction heating coil 11 between the connection point of the switching elements 17a and 17b and the connection point of the switching elements 18a and 18b, and 21 denotes the induction heating coil 11 and the first resonance capacitor. The second resonance capacitor is connected between the connection point of 20 and the connection point of the switching elements 19a and 19b.

  22 is a current sensor (A) for detecting an input current, 23 is a current sensor (B) for detecting a high-frequency current flowing through the induction heating coil 11, and 24 is a detection of the current sensor (A) 22 and the current sensor (B) 23. A pan material discriminating circuit for discriminating between a magnetic pan and a non-magnetic pan based on the current, and 25, each switching element constituting the first switching arm 17 to the third switching arm 19 based on the discrimination result of the pan material discriminating circuit 24. It is a control circuit which controls the drive circuit 26 which determines the drive frequency of.

  Next, operation | movement of the induction heating cooking appliance which has such a structure is demonstrated using FIG. 1 together. When a pan for storing an object to be heated is placed on a plate (not shown) of an induction heating cooker and an operation operation is started, a high frequency current having a frequency of, for example, 30 kHz flows through the induction heating coil 11. At this time, the pot material discriminating circuit 24 discriminates the material of the pot based on the magnitude of the detected current of the current sensor (A) 22 and the current sensor (B) 23. For example, when the induction heating coil current is IL0 to IL1 (A) and the input current is Iin2 to Iin4 (A) as shown in the pan material discrimination characteristic diagram of FIG. / It is determined that it is a magnetic pan of magnetic stainless steel. Further, when the induction heating coil current is IL1 to IL2 (A) and the input current is Iin3 to Iin5 (A), it is determined that the nonmagnetic pan is made of nonmagnetic stainless steel. Further, when the induction heating coil current is IL2 to IL3 (A) and the input current is Iin1 to Iin3 (A), it is determined that the nonmagnetic pan of aluminum / copper. When the pan material discriminating circuit 24 discriminates the magnetic pan, the control circuit 25 sets the switching elements 17a, 18b, 19b as a set via the switching element drive circuit 26, and the switching elements 17b, 18a, The full bridge circuit which makes 19a a set and turns them on / off alternately is formed.

  By such ON / OFF driving of each switching element, the induction heating coil 11 is energized with a large high-frequency voltage V1 having a frequency component of about 20 kHz, for example. Here, the reason why the frequency component of the high frequency voltage is set to 20 kHz and the large high frequency voltage V1 is supplied to the induction heating coil 11 is that the equivalent impedance of the magnetic pan is taken into consideration. The first resonance capacitor 20 and the second resonance capacitor 21 are connected in series with the induction heating coil 11 in parallel.

  When the pan material discriminating circuit 24 discriminates the nonmagnetic stainless steel nonmagnetic pan, the control circuit 25 is connected to the switching element 17a constituting the first switching arm 17 via the switching element drive circuit 26. A half bridge circuit for alternately turning on and off 17b is formed. At this time, the switching elements 18a and 19a are turned off, and the switching elements 18b and 19b are turned on. By such ON / OFF driving of each switching element, the induction heating coil 11 is energized with a high-frequency voltage V2 that is about ½ of the high-frequency voltage V1 having a frequency component of about 20 kHz, for example. Here, the reason why the frequency component of the high frequency voltage is set to 20 kHz and the high frequency voltage V2 is applied to the induction heating coil 11 is that the equivalent impedance of the nonmagnetic pan of nonmagnetic stainless steel is lower than that of the magnetic pan. is there. The first resonance capacitor 20 and the second resonance capacitor 21 are connected in series with the induction heating coil 11 in parallel.

  Further, when the pan material discriminating circuit 24 discriminates that it is an aluminum / copper non-magnetic pan, the control circuit 25 alternately turns on / off the switching elements 17a and 17b via the switching element drive circuit 26. A half-bridge circuit is formed. At this time, only the switching element 18b is turned on, and the switching elements 18a, 19a, and 19b are turned off. By such ON / OFF driving of each switching element, the induction heating coil 11 is energized with a high-frequency voltage V2 that is about ½ of the high-frequency voltage V1 having a frequency component of, for example, about 100 kHz. Here, the reason why the frequency component of the high frequency voltage is set to 100 kHz and the high frequency voltage V2 is supplied to the induction heating coil 11 is that the equivalent impedance of the nonmagnetic pan of aluminum / copper is more than that of the nonmagnetic pan of nonmagnetic stainless steel. This is because it is low. A first resonance capacitor 20 is connected in series to the induction heating coil 11.

  Next, the reason why the control circuit 25 is connected in series in the state where the first resonance capacitor 20 and the second resonance capacitor 21 are connected in parallel to the induction heating coil 11 in the case of the magnetic pot is as follows. . In setting the resonance frequency of the series resonance circuit including the induction heating coil 11, the first resonance capacitor 20, and the second resonance capacitor 21 to 18 kHz, for example, with respect to the frequency 20 kHz of the high frequency voltage supplied to the induction heating coil 11. This is to increase the capacity of the resonant capacitor. Here, when the inductance of the induction heating coil 11 is set to 13 μH, for example, the capacitance of the first resonance capacitor 20 is calculated based on the calculation formula f = 1 / 2π · (L · C) ½ of the resonance frequency of the resonance circuit. Is set to 0.4 μF, the capacitance of the second resonant capacitor 21 is set to 5.0 μF, and the combined capacitance is determined to be 5.4 μF. As a result, the resonance frequency of the resonance circuit can be brought close to the drive frequency of each switching element, and a resonant current can be passed through the induction heating coil 11. Therefore, a large eddy current can be passed through the magnetic pan magnetically coupled to the induction heating coil 11 to contribute a desired heating power, and the pan is appropriately induction heated by electromagnetic induction.

  The reason why the control circuit 25 is connected in series to the induction heating coil 11 in a nonmagnetic stainless steel nonmagnetic pan in a state where the first resonance capacitor 20 and the second resonance capacitor 21 are connected in parallel is the same as described above. It is. The reason why the control circuit 25 connects only the first resonant capacitor 20 in series to the induction heating coil 11 in the aluminum / copper non-magnetic pan is as follows. When the resonance frequency of the series resonance circuit composed of the induction heating coil 11 and the first resonance capacitor 20 is set to 90 kHz, for example, with respect to the frequency 100 kHz of the high frequency voltage supplied to the induction heating coil 11, the capacity of the resonance capacitor is reduced. Because. Here, when the inductance of the induction heating coil 11 is set to 13 μH, for example, the capacitance of the first resonance capacitor 20 is calculated based on the calculation formula f = 1 / 2π · (L · C) ½ of the resonance frequency of the resonance circuit. Is determined to be 0.8 μF. As a result, the resonance frequency of the resonance circuit can be brought close to the drive frequency of each switching element, and a resonant current can be passed through the induction heating coil 11. Therefore, as described above, a large eddy current is caused to flow through the non-magnetic pan of aluminum / copper to contribute a desired heating power, and the pan is appropriately induction-heated by electromagnetic induction.

  As described above, the control circuit 25 performs ON / OFF driving of each switching element constituting the first switching arm 17 to the third switching arm 19 via the switching element drive circuit 26 with the magnetic pot and the nonmagnetic pot. By adopting a configuration in which the first resonant capacitor 20 and the second resonant capacitor 21 are switched and connected to the induction heating coil 11 according to the pan material, induction is performed regardless of the pan material. A desired heating power can be applied to the heating coil 11. Therefore, the induction heating cooking appliance which heat-cooks the to-be-heated material in a pan appropriately can be obtained.

Embodiment 2. FIG.
FIG. 3: shows the circuit block diagram which concerns on Embodiment 2 of an induction heating cooking appliance. In FIG. 3, the same reference numerals as those in Embodiment 1 denote the same or corresponding parts. 27 is connected via a resonant capacitor 28 between a connection point of the switching elements 17a and 17b constituting the first switching arm 17 and a connection point of the switching elements 18a and 18b constituting the second switching arm 18. A first induction heating coil 29 is a second induction heating coil connected between the connection point of the first induction heating coil 27 and the resonant capacitor 28 and the connection point of the switching elements 19a and 19b.

  Next, the operation of such an induction heating cooker will be described with reference to FIG. When a pan for storing the object to be heated is placed on the plate (not shown) of the induction heating cooker and the operation operation is started, the pan material discriminating circuit 24 uses the magnetic pan and the non-magnetic pan as in the first embodiment. Is determined. And when it is discriminated as a magnetic pan by the pan material discriminating circuit 24, the control circuit 25 makes a pair of switching elements 17a and 18b and a pair of switching elements 17b and 18a through a drive circuit 26 of the switching element, A full bridge circuit for alternately turning them on and off is formed. At this time, the switching elements 19a and 19b constituting the third switching arm 19 are turned off. By such ON / OFF driving of each switching element, a large high-frequency voltage V1 having a frequency component of, for example, about 20 kHz is supplied to the first induction heating coil 27. Here, the reason why the frequency component of the high frequency voltage is set to 20 kHz and the large high frequency voltage V1 is supplied to the induction heating coil 11 is the same as in the first embodiment. A first induction heating coil 27 is connected in series with the resonant capacitor 28.

  When the pan material discrimination circuit 24 determines that the nonmagnetic stainless steel nonmagnetic pan is used, the control circuit 25 alternately turns on / off the switching elements 17a and 17b via the switching element drive circuit 26. A half-bridge circuit is formed. At this time, only the switching element 18b is turned on, and the switching elements 18a, 19a, and 19b are turned off. By such ON / OFF driving of each switching element, the first induction heating coil 27 is energized with a high-frequency voltage V2 that is about ½ of the high-frequency voltage V1 having a frequency component of, for example, about 20 kHz. Here, the reason for setting the frequency component of the high frequency voltage to 20 kHz and energizing the first induction heating coil 27 with the high frequency voltage V2 is the same as in the first embodiment. A first induction heating coil 27 is connected in series with the resonant capacitor 28.

  Further, when the pan material discriminating circuit 24 discriminates that it is an aluminum / copper non-magnetic pan, the control circuit 25 alternately turns on / off the switching elements 17a and 17b via the switching element drive circuit 26. A half-bridge circuit is formed. At this time, the switching elements 18b and 19b are turned on, and the switching elements 18a and 19a are turned off. By such ON / OFF driving of each switching element, the first induction heating coil 27 and the second induction heating coil 29 are connected in series to the resonance capacitor 28 in parallel. Then, the first induction heating coil 27 and the second induction heating coil 29 are energized with a high-frequency voltage V2 that is about ½ of the high-frequency voltage V1 having a frequency component of about 100 kHz, for example. Here, the reason why the frequency component of the high-frequency voltage is set to 100 kHz and the high-frequency voltage V2 is supplied to both induction heating coils is the same as in the first embodiment.

  Next, the reason why the control circuit 25 connects the first induction heating coil 27 in series to the resonance capacitor 28 in the case of a magnetic pan is as follows. In setting the resonance frequency of the series resonance circuit including the resonance capacitor 28 and the first induction heating coil 27 to 18 kHz, for example, with respect to the frequency 20 kHz of the high frequency voltage supplied to the first induction heating coil 27, the first This is for increasing the inductance of the induction heating coil 27. Here, when the capacitance of the resonance capacitor 28 is set to 5 μF, for example, the inductance of the first induction heating coil 27 is calculated based on the calculation formula f = 1 / 2π · (L · C) ½ of the resonance frequency of the resonance circuit. Must be determined to be 15 μH. As a result, the resonance frequency of the resonance circuit can be brought close to the drive frequency of each switching element, and a resonant current can be passed through the first induction heating coil 27. Accordingly, a large eddy current can be passed through the magnetic pan magnetically coupled to the first induction heating coil 27 to contribute a desired heating power, and the pan is appropriately induction heated by electromagnetic induction.

  The reason why the control circuit 25 connects the first induction heating coil 27 in series to the resonance capacitor 28 in the nonmagnetic pan of nonmagnetic stainless steel is the same as described above. The reason why the control circuit 25 is connected in series with the first induction heating coil 27 and the second induction heating coil 29 in parallel with respect to the resonance capacitor 28 in the non-magnetic pan of aluminum / copper is as follows. Street. A series resonance consisting of a resonant capacitor 28, a first induction heating coil 27, and a second induction heating coil 29 with respect to a frequency of 100 kHz of a high frequency voltage applied to the first induction heating coil 27 and the second induction heating coil 29. This is to reduce the combined inductance of the first induction heating coil 27 and the second induction heating coil 29 when setting the resonant frequency of the circuit to 90 kHz, for example. Here, when the capacitance of the resonance capacitor 28 is set to 5 μF, for example, the inductance of the first induction heating coil 27 is calculated based on the calculation formula f = 1 / 2π · (L · C) ½ of the resonance frequency of the resonance circuit. 15 μH and the inductance of the second induction heating coil 29 must be determined to be 0.6 μH.

  As a result, the resonance frequency of the resonance circuit can be brought close to the drive frequency of each switching element, and a resonant current can flow through the first induction heating coil 27 and the second induction heating coil 29. Therefore, as described above, a large eddy current is caused to flow through the aluminum / copper non-magnetic pan to contribute a desired heating power, and the pan is appropriately induction-heated by electromagnetic induction.

  In the second embodiment, in the case of an aluminum / copper non-magnetic pan, the first induction heating coil 27 and the second induction heating coil 29 are connected in parallel to form a one-port type heating source. Therefore, the induction heating coils are arranged as a stacked type. Therefore, it is important to set the heating power corresponding to one induction heating coil by reducing the heating power of each induction heating coil. In order to realize this, means for reducing the high-frequency current flowing in each induction heating coil, for example, the switching element drive circuit 26 does not change the driving frequency of each switching element, and only the ON duty ratio is smaller than that of the magnetic pan. It is necessary to add a means for setting to be. As another example, the driving frequency and the ON duty ratio of each switching element are made constant, and the high frequency voltage that is passed through each switching element to the first induction heating coil 27 and the second induction heating coil 29 is It is necessary to provide a step-down converter at the rear of the rectifier circuit 2 so as to step down the voltage.

  As described above, the control circuit 25 controls the ON / OFF drive of each switching element via the switching element drive circuit 26 according to the magnetic pan and the non-magnetic pan, and the resonance capacitor 28 according to the pan material. On the other hand, by adopting a configuration in which the first induction heating coil 27 and the second induction heating coil 29 are switched and connected, a desired heating power can be applied to each induction heating coil regardless of the pan material. Therefore, the induction heating cooking appliance which heat-cooks the to-be-heated material in a pan appropriately can be obtained.

The circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 1 is shown. The discrimination characteristic figure of the magnetic / nonmagnetic material based on the magnitude | size of an input current and an induction heating coil current is shown. The circuit block diagram of the induction heating cooking appliance which concerns on Embodiment 2 is shown. The circuit block diagram of the conventional induction heating cooking appliance is shown.

Explanation of symbols

  1 commercial AC power supply, 2 rectifier circuit, 3 smoothing circuit, 4 choke coil, 5 smoothing capacitor, 6 inverter circuit, 7 diode, 8 diode, 9 diode, 10 diode, 11 induction heating coil, 12 current sensor, 13 resonance capacitor, 14 Pan material discrimination circuit, 15 switching means, 16 inverter drive circuit, 17 first switching arm, 18 second switching arm, 19 third switching arm, 20 first resonance capacitor, 21 second resonance capacitor, 22 current sensor, 23 current sensor, 24 pan material discriminating circuit, 25 control circuit, 26 switching element drive circuit, 27 first induction heating coil, 28 resonance capacitor, 29 second induction heating coil.

Claims (8)

DC voltage converting means for converting the AC voltage of the commercial power supply into DC voltage via a rectifier circuit, and a plurality of DC voltages from the DC voltage converting means are converted to high frequency voltage, and the high frequency voltage is applied to the induction heating coil. In an induction heating cooker equipped with an inverter circuit composed of switching elements,
The inverter circuit comprises a first switching arm and two second switching arms,
Pan material discrimination means for discriminating whether the cooking pan is a magnetic pan or a non-magnetic pan;
On / off of each switching element of the first switching arm and the second switching arm so as to control the magnitude and frequency of the high-frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discrimination means. Control means for controlling the OFF drive;
A pair of resonant capacitors provided for each of the second switching arms, having one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil;
A series resonant circuit is constituted by the pair of resonant capacitors and the induction heating coil,
The other end of the induction heating coil is connected to the output of the first switching arm,
The control means selects the two second switching arms when the result of discrimination by the pan material discrimination means is a non-magnetic stainless steel non-magnetic pot, and the negative electrodes of the two selected second switching arms. An induction heating cooker characterized in that the switching element on the side is always ON-driven, the switching element on the positive electrode side is always OFF-driven, and the first arm is ON / OFF-driven.   DC voltage converting means for converting the AC voltage of the commercial power supply into DC voltage via a rectifier circuit, and a plurality of DC voltages from the DC voltage converting means are converted to high frequency voltage, and the high frequency voltage is applied to the induction heating coil. In an induction heating cooker equipped with an inverter circuit composed of switching elements,
  The inverter circuit comprises a first switching arm and two second switching arms,
  Pan material discrimination means for discriminating whether the cooking pan is a magnetic pan or a non-magnetic pan;
  On / off of each switching element of the first switching arm and the second switching arm so as to control the magnitude and frequency of the high-frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discrimination means. Control means for controlling the OFF drive;
  A pair of resonant capacitors provided for each of the second switching arms, having one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil;
  A series resonant circuit is constituted by the pair of resonant capacitors and the induction heating coil,
  The other end of the induction heating coil is connected to the output of the first switching arm,
  The control means selects one second switching arm when the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan, and the negative electrode of the selected one second switching arm. The switching element on the side is always turned on, the switching element on the positive side is always turned off, the switching element on the negative side of the second switching arm that is not selected and the switching element on the positive side are always turned off, and the first switching element An induction heating cooker characterized by driving an arm ON / OFF. The control means controls the ON / OFF drive of each switching element constituting the first switching arm and the two second switching arms , and the impedance of the pot material determined by the pot material determination means claims based estimates the driving frequency, the resonance frequency of the series resonant circuit is characterized in that there was Unishi by Ru varying the capacitance of the resonant capacitor connected to the induction heating coil so as to approach the drive frequency and the estimated Item 1. An induction heating cooker according to item 1. DC voltage converting means for converting the AC voltage of the commercial power supply into DC voltage via a rectifier circuit, and a plurality of DC voltages from the DC voltage converting means are converted to high frequency voltage, and the high frequency voltage is applied to the induction heating coil. In an induction heating cooker equipped with an inverter circuit composed of switching elements,
The inverter circuit comprises a first switching arm and two second switching arms,
Pan material discrimination means for discriminating whether the cooking pan is a magnetic pan or a non-magnetic pan;
On / off of each switching element of the first switching arm and the second switching arm so as to control the magnitude and frequency of the high-frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discrimination means. Control means for controlling the OFF drive;
A pair of resonant capacitors provided for each of the second switching arms, having one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil ;
Form a series resonant circuit with the induction heating coil and the pair of resonant capacitor,
The other end of the induction heating coil is connected to the output of the first switching arm,
The control means selects two second switching arms when the determination result of the pot material determination means is a magnetic pot, and the selected two second switching arms, the first arm, Are simultaneously driven at a first frequency,
When the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan, one of the second switching arms is selected, and the switching element on the negative side of the selected second switching arm is selected. always ON driving, constantly OFF drives the switching element of the positive side, always OFF drives the switching element on the negative electrode side switching element and the positive side of the second switching arm is not selected, the said first arm first the induction heating cooker wherein the turning ON / OFF driven by a second frequency different from the frequency. The induction heating cooker according to claim 3, wherein the second frequency is higher than the first frequency .   DC voltage converting means for converting the AC voltage of the commercial power supply into DC voltage via a rectifier circuit, and a plurality of DC voltages from the DC voltage converting means are converted to high frequency voltage, and the high frequency voltage is applied to the induction heating coil. In an induction heating cooker equipped with an inverter circuit composed of switching elements,
  The inverter circuit comprises a first switching arm and two second switching arms,
  Pan material discrimination means for discriminating whether the cooking pan is a magnetic pan or a non-magnetic pan;
  On / off of each switching element of the first switching arm and the second switching arm so as to control the magnitude and frequency of the high-frequency voltage applied to the induction heating coil based on the discrimination result of the pan material discrimination means. Control means for controlling the OFF drive;
  A pair of resonant capacitors provided for each of the second switching arms, having one end connected to the respective output of the second switching arm and the other end connected to one end of the induction heating coil;
  A series resonant circuit is constituted by the pair of resonant capacitors and the induction heating coil,
  The other end of the induction heating coil is connected to the output of the first switching arm,
  The control means selects the two second switching arms when the result of discrimination by the pan material discrimination means is a non-magnetic stainless steel non-magnetic pot, and the negative electrodes of the two selected second switching arms. The first switching element is always ON driven, the positive switching element is always OFF driven, and the first arm is ON / OFF driven at the first frequency,
  When the discrimination result of the pan material discrimination means is an aluminum / copper non-magnetic pan, one of the second switching arms is selected, and the switching element on the negative side of the selected second switching arm is selected. An induction heating cooker, wherein the induction heating cooker is always ON-driven, the positive-side switching element is always OFF-driven, and the first arm is ON / OFF-driven at a second frequency different from the first frequency. 6. The induction heating cooker according to claim 5, wherein the second frequency is higher than the first frequency . Induction comprising a DC voltage converting means for converting an AC voltage of a commercial power source into a DC voltage via a rectifier circuit, and an inverter circuit comprising a plurality of switching elements for converting the DC voltage from the DC voltage converting means into a high frequency voltage In a heating cooker,
The inverter circuit comprises a first switching arm and two second switching arms,
Pan material discrimination means for discriminating whether the cooking pan is a magnetic pan or a non-magnetic pan;
ON of the first switching arm and second switching elements of the switching arm so as to control the magnitude and frequency of the RF voltage applied on the basis of the determination result of the pan material determination means induction heating coil / Control means for controlling the OFF drive;
A resonant capacitor having one end connected to the output of the first switching arm;
Provided for each of the second switching arms, one end is connected to the respective output of the second switching arm, the other end is connected to the other end of the resonant capacitor, and constitutes a pair of heating sources An induction heating coil,
A series resonance circuit is constituted by the pair of induction heating coils and the resonance capacitor,
The control means selects a full bridge circuit when the discrimination result of the pan material discrimination means is a magnetic pan, and the discrimination result of the pan material discrimination means is a nonmagnetic pan of nonmagnetic stainless steel or non-aluminum / copper. In the case of a magnetic pan, induction heating cooking is characterized in that at least one of the second switching arms and the first arm are turned ON / OFF so as to select a half-bridge circuit. vessel.

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