JP3818117B2 - Induction heating cooker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an induction heating cooker used in general households.
[0002]
[Prior art]
Induction cooking devices are becoming popular in ordinary households because they are understood to be safe, clean, and highly efficient. In particular, in recent years, devices having two or more burners have become widespread as main cooking devices placed in the kitchen.
[0003]
In the induction heating cooker, when two adjacent burners operate at different frequencies, there is a problem that an unpleasant pan sound is generated due to interference from other burners. As a countermeasure against this, there are two or more switching elements that are alternately turned on and off to make the current applied to the heating coil or the operating frequency of the inverter constant even if the pan material or input power changes. Has been proposed.
[0004]
A conventional induction heating cooker will be described below with reference to FIG. In FIG. 12, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. inverter for supplying, 14 denotes a control unit for controlling on and off of switch Jin grayed elements 4a and 4b.
[0005]
Next, the operation will be described with reference to FIG. FIGS. 13A and 13B show ON / OFF patterns of the switching elements 4a and 4b. These two switching elements have an off period for a certain period of time, and control each other to turn on and off in sequence. By changing the on / off ratio, the two switching elements can be adapted to pans of various materials and the input power can be changed. It is common to do.
[0006]
Further, in the steady heating state, as shown in FIGS. 13C and 13D, the inverter unit 5 is operated in a stable state with a constant cycle with respect to the commercial power source.
[0007]
[Problems to be solved by the invention]
On the other hand, in the induction heating cooker, the magnetic flux originally output from the device main body for induction heating of the pan is not absorbed by the 100% pan, but is radiated to a space, though only a part. Since this radiated energy can affect other devices as noise, it needs to be reduced.
[0008]
As described above, in the conventional induction heating cooker, since the operation of the inverter unit is always performed at a constant cycle regardless of the polarity of the commercial power supply, radiation noise in both polarities of the commercial power supply is superimposed. As a result, there is a problem that the structure becomes high and the structure is complicated due to high costs such as providing an aluminum shield member as a countermeasure.
[0009]
This invention is made | formed in view of this point, and aims at reduction of the noise radiated | emitted from an apparatus main body with a simple structure.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention changes the operation period of the inverter unit between one polarity of the commercial power supply and the other polarity, and causes a difference in the frequency of noise radiated in both polarities, resulting in the same The level of radiation noise can be reduced by preventing superposition in frequency.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The invention according to claim 1 is a commercial power source, a rectifier circuit that rectifies the commercial power source, a heating coil, two or more switching elements, and a high-frequency current to the heating coil by turning on and off the switching elements. The inverter section to be supplied and the on / off frequency of the switching element are provided with a difference between one polarity and the other polarity of the commercial power supply, and the same polarity is controlled at a constant frequency, and the input power is substantially reduced in each polarity. is obtained by a configuration consisting of a polar-based control unit for controlling on and off of the switch Jin grayed element so as to be constant, it is possible to change the operating frequency of the inverter unit in the two polarities of the commercial power supply by this arrangement, As a result, there is a difference in the frequency of noise radiated in both polarities, preventing it from being superimposed at the same frequency. More it is obtained by allowing the level reduction of the radiation noise.
[0012]
The invention according to claim 2 is a commercial power source, a rectifier circuit that rectifies the commercial power source, a heating coil, an input current detection unit that detects an input current from the commercial power source for each polarity, and two or more A switching element, an inverter for supplying a high-frequency current to the heating coil by turning on and off the switching element, and a difference in the on / off frequency of the switching element between one polarity and the other polarity of the commercial power supply in the same polarity is obtained by a configuration consisting of a polar-based control unit for controlling on and off of the switch Jin grayed element so that the input current becomes constant control at a constant frequency, and each polarity, the present arrangement Even when driving the inverter by changing the operating frequency in both polarities, the input current can be controlled independently in both polarities. Control is Joka becomes possible.
[0013]
The invention according to claim 3 is a heating coil current detection unit that detects a current applied to the heating coil for each polarity of the commercial power supply, and a heating coil current detected by the heating coil current detection unit is a predetermined value that is determined in advance. Control for each polarity of the commercial power supply so that the heating coil current is constant in each polarity of the commercial power supply, and a control unit for each polarity that controls on / off of the switching element. In addition, since the current applied to the heating coil can be controlled for each polarity of the commercial power supply, it is possible to prevent the heating coil current of one side from becoming excessive, so that highly reliable control is possible.
[0014]
According to a fourth aspect of the present invention, there is provided a switching element voltage detector for detecting the voltage applied to the switching element for each polarity of the commercial power supply, and the voltage detected by the switching element voltage detector exceeds a predetermined value. In addition to controlling the on / off of the switching element for each polarity of the commercial power supply, and having a control unit for each polarity that controls the switching element voltage to be constant in each polarity of the commercial power supply. In addition, since the voltage applied to the switching element can be controlled for each polarity of the commercial power supply, it is possible to prevent one of the switching element voltages from becoming excessively high, so that highly reliable control is possible.
[0015]
According to a fifth aspect of the present invention, a commercial power source, a rectifier circuit that rectifies the commercial power source, a heating coil, two or more switching elements, and a high-frequency current to the heating coil by turning on and off the switching elements are provided. An inverter unit to supply, a control unit for controlling the switching element at a constant frequency in one polarity, and an on-time addition unit for adding an on-time of the other polarity by a predetermined value to an on-time in the one polarity The on-time of the other polarity adds a predetermined value to the on-time of the one polarity, and the off-time of the other polarity is the same as the off-time of the one polarity. it is thereby possible to vary the frequency of both polarities in an extremely simple structure in since those Rudake changing the frequency with the polarity change in the commercial power source
[0016]
According to a sixth aspect of the present invention, a commercial power source, a rectifying circuit that rectifies the commercial power source, a heating coil, two or more switching elements, and a high-frequency current to the heating coil by turning on and off the switching elements are provided. An inverter unit to supply, a control unit for controlling the switching element at a constant frequency in one polarity, and an off time addition unit for adding an off time of the other polarity by a predetermined value to an off time in the one polarity is obtained by the structure, the other polarity off time adds the Tokoro value to the polarity off time of said one and the other polarity of the on-time is the same as the on-time of the polarity of the one it is thereby possible to vary the frequency of both polarities in an extremely simple structure in since those Rudake changing the frequency with the polarity change in the commercial power source
[0017]
The invention according to claim 7 is a commercial power source, a rectifying circuit for rectifying the commercial power source, a heating coil, two or more switching elements, and turning on and off the switching elements to generate a high-frequency current in the heating coil. An inverter to be supplied, a control unit for controlling the switching element at a certain frequency in one polarity, and an on time and an off time in the other polarity by multiplying the on time and off time in the one polarity by a certain ratio A multiplier for calculating time; the on-time of the other polarity is multiplied by a predetermined value on the on-time of the one polarity; and the off-time of the other polarity is a predetermined value on the off-time of the one polarity by the multiplication Jill, changing the frequencies of both polarities at extremely simple structure since those of Rudake changing the frequency with the polarity change in the commercial power source Door can be.
[0018]
In the induction heating cooker having a plurality of induction heating burners, when the frequency is changed in accordance with the polarity change of the commercial power source, the change is synchronized for all the burners. Even when a plurality of burners have a frequency difference between the polarities according to this configuration, the operation frequency of each of the plurality of burners can always be kept the same, thereby preventing the generation of interference sound due to the frequency difference. it can.
[0019]
【Example】
Example 1
Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. The inverter unit 6 supplies a difference between the on-off frequency of the switching elements 4a and 4b between one polarity and the other polarity of the commercial power supply 1, and controls the same polarity with a constant frequency. switch Jin grayed element 4a so that the input power becomes substantially constant at a polarity based control unit for controlling on and off of 4b.
[0020]
Next, the operation will be described with reference to FIG. 2A shows a voltage waveform diagram of the commercial power source 1, and FIG. 2B shows an operation cycle of the inverter unit 5 at that time. When the commercial power source 1 has a positive polarity, the cycle operates at T1 and has a negative polarity. Sometimes it operates with period T2. As a result, as shown in (c), since the conventional configuration operates at a constant period T0, the radiation noise as the fundamental wave is concentrated on the frequency f0 of 1 / T0 and is superposed to a high level. On the other hand, in the embodiment of the present invention, the period is changed to T1 and T2 depending on the polarity of the commercial power supply 1, so that the radiation noise of the fundamental wave is also distributed to f1 and f2 which are 1 / T1 and 1 / T2, The level can be lowered as shown in the figure. The second and subsequent waves can be reduced for the same reason.
[0021]
(Example 2)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In FIG. 3, 1 is a commercial power source, 2 is a rectifying circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. 7 is an input current detection unit that detects the input current from the commercial power supply 1 for each polarity, and 61 is an on / off frequency of the switching elements 4a and 4b. In addition, control is performed at a constant frequency for the same polarity, and on / off control of the switching elements 4a and 4b is performed so that the input current detected by the input current detector 7 is constant in each polarity. Part.
[0022]
With the above configuration, even when the inverter unit 5 is driven by changing the operating frequency in both polarities of the commercial power source 1, the input current can be controlled independently in both polarities, so that the input current can be controlled stably. Become.
[0023]
Example 3
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In FIG. 4, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. 8 is a heating coil current detection unit that detects the current applied to the heating coil 3 for each polarity of the commercial power supply 1, and 62 is a predetermined heating coil current detected by the heating coil current detection unit 8. In addition, control is performed for each polarity of the commercial power source 1 so as not to exceed the predetermined value, and a control unit for each polarity that controls on / off of the switching elements 4a and 4b so that the heating coil current is constant in each polarity of the commercial power source 1. is there.
[0024]
With the above configuration, since the current applied to the heating coil 3 can be controlled for each polarity of the commercial power supply 1, it is possible to prevent one of the heating coil currents from becoming excessive, so that an excessive current is applied to the switching elements 4 a, 4 b, etc. This makes it possible to perform highly reliable control.
[0025]
Example 4
Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings. In FIG. 5, 1 is a commercial power source, 2 is a rectifying circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. The inverter unit 9 supplies a switching element voltage detection unit 9 for detecting the voltage applied to the switching element 4a for each polarity of the commercial power source 1, and 63 indicates a predetermined voltage detected by the switching element voltage detection unit 9 It is a control unit for each polarity that controls on / off of the switching elements 4 a and 4 b for each polarity of the commercial power source 1 so as not to exceed the value, and controls the switching element voltage to be constant in each polarity of the commercial power source 1.
[0026]
With the above configuration, since the voltage applied to the switching element 4a can be controlled for each polarity of the commercial power source 1, the switching element voltage of one polarity can be prevented from becoming excessive, and therefore an excessive voltage is applied to the switching element 4a and the like. This makes it possible to perform highly reliable control.
[0027]
(Example 5)
A fifth embodiment of the present invention will be described below with reference to the drawings. In FIG. 6, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. 10 is a control unit that controls the switching elements 4a and 4b at a constant frequency in one polarity, and 11 is an on-time addition that adds an on-time of the other polarity by a predetermined value to an on-time in one polarity. Next, the operation will be described with reference to FIG. 7A shows a time chart of the commercial power source 1, FIG. 7B shows an ON time of the switching element 4b at that time, and FIG. 7C shows an OFF time. As shown in (b), a predetermined value t3 is added to the on time T3 in one polarity on the other side. Thus, the bipolar frequency can be changed with a simple configuration.
[0028]
(Example 6)
Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings. In FIG. 8, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. 10 is a control unit that controls the switching elements 4a and 4b at a constant frequency in one polarity, and 12 is an off time addition that adds an off time of the other polarity to the off time in one polarity by a predetermined value. Next, the operation will be described with reference to FIG. 9A shows a time chart of the commercial power source 1, FIG. 9B shows an ON time of the switching element 4b at that time, and FIG. 9C shows an OFF time. As shown in (c), a predetermined value t6 is added to the off time T6 in one polarity on the other side. Thus, the bipolar frequency can be changed with a simple configuration.
[0029]
(Example 7)
A seventh embodiment of the present invention will be described below with reference to the drawings. In FIG. 10, 1 is a commercial power source, 2 is a rectifier circuit for rectifying the commercial power source 1, 3 is a heating coil, 4a and 4b are switching elements, and 5 is a high-frequency current in the heating coil 3 by turning on and off the switching elements 4a and 4b. 10 is a control unit that controls the switching elements 4a and 4b at a constant frequency in one polarity, and 13 is a constant ratio multiplied by the on time and off time in one polarity determined by 10. The multiplication unit calculates the on time and off time of the other polarity.
[0030]
Next, the operation will be described with reference to FIG. 11A shows a time chart of the commercial power source 1, FIG. 11B shows an ON time of the switching element 4b at that time, and FIG. 11C shows an OFF time. As shown in (b) and (c), the on-time T7 in one polarity is obtained by multiplying the other by a predetermined value p, and the off-time of 4b is similarly obtained by multiplying T8 by q. . Thus, the bipolar frequency can be changed with a simple configuration.
[0031]
(Example 8)
The eighth embodiment of the present invention will be described below. The present invention is an induction heating cooker having a plurality of induction heating burners, and when the frequency is changed in accordance with the polarity change of the commercial power source described in Example 1, Example 5, Example 6 and Example 7, In this configuration, even when a difference in frequency is provided between the polarities in the plurality of burners, the operating frequency of each of the plurality of burners can always be kept the same. Generation of interference sound due to frequency difference can be prevented.
[0032]
In this embodiment, the control unit by polarity, the input current detection unit, the heating coil current detection unit, the switching element voltage detection unit, the on-time addition unit, the off-time addition unit, the multiplication unit, etc. are shown in the block diagram. The same applies when software processing is performed by microcomputer programming.
[0033]
In addition, the inverter is shown as using two switching elements, but the same applies to those using three or more switching elements.
[0034]
【The invention's effect】
As described above, according to the first aspect of the invention, the on / off frequency of the switching element is made different between one polarity and the other polarity of the commercial power supply, and at the same polarity, it is controlled at a constant frequency regardless of the input power. Therefore, it is possible to change the operating frequency of the inverter unit in the two polarities of the commercial power supply. As a result, a difference is generated in the frequency of noise radiated in both polarities, thereby preventing superposition at the same frequency. Thus, the level of radiation noise can be reduced .
[0035]
According to the second aspect of the invention, the polarity-based control unit which controls the on-off of switch Jin grayed element so that the input current is constant in each polarity, when driving the inverter by changing the operating frequency in bipolar However, since the input current can be controlled independently in both polarities, it is possible to control with the input current stabilized.
[0036]
According to invention of Claim 3, it has a heating coil current detection part which detects the electric current applied to a heating coil for every polarity of commercial power, and controls the current applied to a heating coil for every polarity of commercial power Therefore, it is possible to prevent the heating coil current of one side from becoming excessive and to perform highly reliable control.
[0037]
According to invention of Claim 4, it has a switching element voltage detection part which detects the voltage applied to a switching element for every polarity of commercial power, and controls the voltage applied to a switching element for every polarity of commercial power Therefore, it is possible to prevent one of the switching element voltages from becoming excessively high and to perform highly reliable control.
[0038]
According to the fifth aspect of the invention, only the other polarity of the on-time by adding a predetermined value to the one polarity of the on time and the other polarity off time is the same as the off time of one polarity Therefore, the bipolar frequency can be changed with a very simple configuration.
[0039]
According to the invention of claim 6, wherein said other polarity off time adds the Tokoro value to the polarity off time of said one and the other polarity of the on-time and on-time of the polarity of the one Since they are just the same, the frequency of both polarities can be changed with a very simple configuration.
[0040]
According to the invention of claim 7, wherein the other polarity of the on-time Flip multiply a predetermined value in one polarity on-time, and the other polarity off time is multiplied by a predetermined value to off-time of one polarity Therefore, the bipolar frequency can be changed with a very simple configuration.
[0041]
According to the invention described in claim 8, in the induction heating cooker having a plurality of induction heating burners, when the frequency is changed with the polarity change of the commercial power source, the change is synchronized for all the burners. Therefore, even when a difference in frequency is provided between the polarities of a plurality of burners, the operation frequency of each of the plurality of burners can always be kept the same, so that the generation of interference sound due to the frequency difference can be prevented.
[Brief description of the drawings]
FIG. 1 is a block diagram of an induction heating cooker in a first embodiment of the present invention. FIG. 2 (a) is a voltage waveform diagram of a commercial power supply in the first embodiment of the present invention. (C) Same as above, (c) A diagram showing the radiation noise levels of the fundamental wave and the second wave. FIG. 3 is a block diagram of an induction heating cooker according to the second embodiment of the present invention. FIG. 5 is a block diagram of the induction heating cooker according to the fourth embodiment of the present invention. FIG. 6 is a block diagram of the induction heating cooker according to the fifth embodiment of the present invention. FIG. 7A is a voltage waveform diagram of a commercial power source in a fifth embodiment of the present invention. FIG. 7B is a time chart of the ON time of the switching element 4b. FIG. 7C is the same time of the OFF time of the switching element 4b. Chart [Fig. 8] Sixth embodiment of the present invention Block diagram of induction heating cooker in FIG. 9 (a) Voltage waveform diagram of commercial power source in the sixth embodiment of the present invention (b) Time chart of ON time of switching element 4b (c) Same as above, switching FIG. 10 is a block diagram of an induction heating cooker according to a seventh embodiment of the present invention. FIG. 11A is a voltage waveform diagram of a commercial power source according to the seventh embodiment of the present invention. (B) Same time chart of switching element 4b ON time (c) Same time chart of switching element 4b OFF time [FIG. 12] Block diagram of induction heating cooker of conventional example [FIG. 13] (a) Conventional Time chart of ON / OFF pattern of switching element 4a in example (b) Time chart of ON / OFF pattern of switching element 4b (c) Commercial power supply (D) Same as above, (d) Same as the operation cycle of the inverter section
DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Rectification circuit 3 Heating coil 4a, 4b Switching element 5 Inverter part 6 Control part according to polarity 7 Input current detection part 8 Heating coil current detection part 9 Switching element voltage detection part 10 Control part 11 On time addition part 12 Off time Adder 13 Multiplier

Claims (8)

A commercial power source, a rectifying circuit for rectifying the commercial power source, a heating coil, two or more switching elements, an inverter unit for supplying a high-frequency current to the heating coil by turning on and off the switching element, and the switching element the on-off frequency is provided with the difference between one polarity and the other polarity of the commercial power supply, in the same polarity controlled by a constant frequency, and so the input power at each polarity is substantially constant said switch Jin grayed element An induction heating cooker comprising a polarity-specific control unit that controls the on / off of the gas. A commercial power source, a rectifier circuit for rectifying the commercial power source, a heating coil, an input current detection unit for detecting an input current from the commercial power source for each polarity, two or more switching elements, and the switching element. The inverter unit that supplies a high-frequency current to the heating coil by turning on and off, and the on / off frequency of the switching element provides a difference between one polarity and the other polarity of the commercial power supply, and at the same polarity, the frequency is constant. controlled, and induction heating cooker the input current in each polarity consisting of a polar-based control unit for controlling on and off of the switch Jin grayed element so as to be constant.   A heating coil current detection unit that detects the current applied to the heating coil for each polarity of the commercial power source, and a heating power source detected by the heating coil current detection unit so that the heating coil current does not exceed a predetermined value. 2. The induction heating cooker according to claim 1, further comprising a control unit for each polarity that controls each polarity and controls on / off of the switching element so that the heating coil current is constant in each polarity of the commercial power source.   A switching element voltage detection unit that detects the voltage applied to the switching element for each polarity of the commercial power supply, and for each polarity of the commercial power supply so that the voltage detected by the switching element voltage detection unit does not exceed a predetermined value. The induction heating cooker according to claim 1, further comprising: a polarity-specific control unit that controls on / off of the switching element and controls the switching element voltage to be constant in each polarity of the commercial power source. A commercial power source, a rectifying circuit that rectifies the commercial power source, a heating coil, two or more switching elements, an inverter unit that supplies a high-frequency current to the heating coil by turning on and off the switching element, and one polarity A control unit that controls the switching element at a constant frequency, and an on-time addition unit that adds a predetermined value to the on-time of the other polarity with respect to the on-time of the one polarity, and the on-time of the other polarity is A predetermined value is added to the ON time of one polarity, and the OFF time of the other polarity is the same as the OFF time of the one polarity, so that the frequency is changed in accordance with the polarity change of the commercial power supply. Cooking cooker. A commercial power source, a rectifying circuit that rectifies the commercial power source, a heating coil, two or more switching elements, an inverter unit that supplies a high-frequency current to the heating coil by turning on and off the switching element, and one polarity A control unit that controls the switching element at a constant frequency, and an off-time addition unit that adds a predetermined value to the off-time of the other polarity with respect to the off-time of the one polarity, and the off-time of the other polarity is A predetermined value is added to the off time of one polarity, and the on time of the other polarity is made the same as the on time of the one polarity, so that the frequency is changed in accordance with the polarity change of the commercial power supply. Cooking cooker. A commercial power source, a rectifying circuit that rectifies the commercial power source, a heating coil, two or more switching elements, an inverter unit that supplies a high-frequency current to the heating coil by turning on and off the switching element, and one polarity A control unit for controlling the switching element at a constant frequency, and a multiplication unit for calculating the on time and off time of the other polarity by multiplying the on time and off time of the one polarity by a constant ratio , The on-time of the other polarity multiplies the on-time of the one polarity by a predetermined value, and the off-time of the other polarity multiplies the off-time of the one polarity by a predetermined value. Induction heating cooker that changes frequency with change .   The induction heating cooker having a plurality of induction heating burners, wherein when changing the frequency in accordance with the polarity change of the commercial power source, the change is synchronized for all the burners. Induction heating cooker.

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