JP2012238408A - Induction heating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate a material and a shape of a load with high accuracy when discriminating the material and the shape of each of the loads placed on two heating coils, respectively, in a circuit configuration that includes input current detection means for detecting a value of an input current supplied from an AC power source shared among a plurality of inverter circuits.SOLUTION: An induction heating apparatus comprises: a first heating coil 8 and a second heating coil 9; a first inverter circuit 4 and a second inverter circuit 5; a control part 13 performing output control of the first inverter circuit 4 and the second inverter circuit 5 depending on an output from input current detection means 3; and a load discrimination part 12 discriminating a material and a shape of each of loads placed on the first heating coil 8 and the second heating coil 9, respectively. The control part 13 stops, while the load discrimination part 12 is discriminating the material and the shape of the load placed on one of the first heating coil 8 and the second heating coil 9, an output from the inverter circuit supplying a high frequency current to the other heating coil.

Description

  The present invention relates to an induction heating apparatus provided with means for discriminating the material and shape of a load heated by an induction heating method.

  Conventionally, this type of induction heating device discriminates the material and shape of a load placed on a heating coil by detecting the value of an input current from an AC power supply or a voltage generated in an inverter circuit. (See, for example, Patent Document 1).

  In addition, there is also a circuit in which two inverter circuits are connected in parallel to a circuit having one input current detection means for detecting an input current from an AC power source and one rectifier circuit, thereby reducing the size of the circuit. (For example, refer to Patent Document 2).

  The conventional example will be described below with reference to FIGS.

  FIG. 5 is a circuit configuration diagram of a conventional induction heating apparatus described in Patent Document 1. One of the DC power supply circuit 102 that converts the AC power supply 101 into DC, the pair of first switching elements 104 and the second switching element 105, and the pair of first switching elements 104 and second switching element 105 It has a series circuit composed of a heating coil 106 and a resonant capacitor 108 connected in parallel. A pair of first switching element 104 and second switching element 105 are alternately turned on and off to supply a high-frequency current to the heating coil 106. Output proportional to the peak value of the current detected by the supplied inverter circuit 113, the input current detection means 103 for detecting the current input to the DC power supply circuit 102, and the current detection means 107 for detecting the current flowing through the resonant capacitor 108 Voltage generated in the load current detection circuit 112 and the inverter circuit 113 When the inverter voltage detection circuit 109 to detect and any one of a plurality of oscillation frequencies set in advance according to the material of the pan 114 are oscillated, and when a preset time is reached after cooking is started, The presence or absence of abnormality on the heating coil 106 is determined based on the current value input to the DC power supply circuit 102 and the voltage value generated in the inverter circuit 113, and the material of the pan 114 is determined based on the result, and according to the material. The control unit 111 that oscillates by selecting a frequency and outputs a signal having a predetermined rate of increase until a preset time, and then outputs a control signal according to the set power, and is selected by the control unit 111 Based on the frequency and the control signal, the power set for the heating coil 106 can be obtained, and the power of the heating coil 106 of the inverter circuit 113 can be obtained. Gradually generates a drive signal for raising the inverter driving unit 110 for output to the inverter circuit 113, and a.

  In the above configuration, the control unit 111 stops the inverter driving unit 110 when it is determined that the heating coil 106 is abnormal, and determines the material of the pan 114 according to the material when it is determined that the heating coil 106 is not abnormal. The pot 114 is made of different materials by changing the conduction ratio of the drive signal of the inverter drive means 110 so that the frequency is selected and oscillated, and the output of the load current detection circuit 112 is not more than a preset value. However, it is possible to heat efficiently without applying stress to the device.

FIG. 6 is a circuit configuration diagram of a conventional induction heating apparatus described in Patent Document 2. A rectifier circuit 202 that rectifies the AC power supply 201, a first inverter circuit 204 that converts the output of the rectifier circuit 202 into high-frequency power and applies a current to the first heating coil 206, and an output of the rectifier circuit 202 into high-frequency power. A second inverter circuit 205 that converts and applies a current to the second heating coil 207, a current detection unit 203 that detects an input current from the AC power supply 201, and a first inverter according to the output of the current detection unit 203 The circuit 204 and the control means 208 which controls the conduction | electrical_connection time of the some semiconductor switch in the 2nd inverter circuit 205 are comprised.

  In the above configuration, after the input current of the first inverter circuit 204 or the second inverter circuit 205 reaches the target value, the rectifier circuit 202 is connected to the two inverter circuits by performing simultaneous operation with the other inverter circuit. Even if the current detection means 203 is shared, predetermined power can be supplied to each of the first inverter circuit 204 and the second inverter circuit 205.

JP 2002-075623 A JP 2010-212052 A

  However, in the conventional configuration, in the circuit configuration in which the current detection means is shared for the two inverter circuits, the value of the input current supplied from the AC power source is detected, and the result is mounted on the heating coil. When determining the material and shape of the installed load, the detected input current value is the sum of the current values supplied to the two inverter circuits, so one of the two inverter circuits is operated simultaneously. There is a problem that it is difficult to determine the material and shape of the load placed on the heating coil.

  The present invention solves the conventional problems, and in a circuit configuration in which an input current detection means for detecting an input current supplied from an AC power supply is shared for a plurality of inverter circuits, the output of the input current detection means An object of the present invention is to provide an induction heating device that can determine the material and shape of the load placed on the heating coil on the basis of the result with high accuracy.

  In order to solve the conventional problem, an induction heating device of the present invention includes a rectifier circuit that converts an alternating current power source into direct current, first and second heating coils that generate a high frequency magnetic field and heat a load, Corresponding to each of the first and second heating coils, the first and second resonance capacitors constituting the first and second resonance circuits, and each of the first and second heating coils, the rectifier circuit Are connected in parallel to each other, and the first and second inverter circuits for inputting the output voltage of the rectifier circuit and one input current detection for detecting the sum of the input currents supplied to the first and second inverter circuits Means, a control unit that performs output control of the first and second inverter circuits according to the output of the input current detecting means, and materials of loads generated in the first and second inverter circuits, respectively First and second control element detection means for detecting a physical quantity that changes according to the state, and the first and second control element detection means based on the outputs of the input current detection means and the first or second control element detection means. A load discriminating unit for discriminating the material and shape of the load placed on the heating coil, and the control unit is configured to load the load discriminating unit placed on the first or second heating coil. While the material and the shape are determined, the output of the inverter circuit on the side supplying the high-frequency current to the other heating coil is stopped.

  Thus, in a circuit configuration in which the input current detection means for detecting the input current supplied from the AC power supply is shared for a plurality of inverter circuits, the inverter circuit is placed on the heating coil based on the output result of the input current detection means. Even when the material and shape of the applied load are determined, the material and shape can be determined with high accuracy.

  The induction heating apparatus according to the present invention is configured to heat a plurality of inverter circuits based on an output result of the input current detection means in a circuit configuration in which an input current detection means for detecting an input current supplied from an AC power source is shared. Even when determining the material and shape of the load placed on the coil, the material and shape can be determined with high accuracy.

The circuit block diagram of the induction heating control apparatus in Embodiment 1 of this invention Operation flow chart of induction heating apparatus in Embodiment 1 of the present invention Graph of current change supplied to first and second inverter circuits when determining the material and shape of the load of the induction heating device in Embodiment 1 of the present invention Load material determination region diagram of induction heating device in Embodiment 1 of the present invention The circuit block diagram of the conventional induction heating apparatus in patent document 1 The circuit block diagram of the conventional induction heating apparatus in patent document 2

  According to a first aspect of the present invention, there is provided a rectifier circuit that converts an alternating current power source into a direct current, first and second heating coils that generate a high-frequency magnetic field to heat a load, each of the first and second heating coils, Corresponding to each of the first and second resonance capacitors constituting the first and second resonance circuits and the first and second heating coils, and connected in parallel to the rectifier circuit, the output voltage of the rectifier circuit According to the output of the first and second inverter circuits, one input current detecting means for detecting the sum of the input currents supplied to the first and second inverter circuits, and the output of the input current detecting means A control unit that performs output control of the first and second inverter circuits, and a first output that detects a physical quantity that changes according to the material and shape of the load generated in each of the first and second inverter circuits. And a second control element detection means, a material of a load placed on the first and second heating coils based on outputs of the input current detection means and the first or second control element detection means, and A load discriminating unit that discriminates each of the shapes, and the control unit, while the load discriminating unit discriminates the material and shape of the load placed on the first or second heating coil, This is an induction heating device that stops the output of the inverter circuit on the side that supplies high-frequency current to the other heating coil.

  Thus, in a circuit configuration in which the input current detection means for detecting the input current supplied from the AC power supply is shared for a plurality of inverter circuits, the inverter circuit is mounted on the heating coil based on the output result of the input current detection means. Even when determining the material and shape of the placed load, it is possible to accurately detect the input current supplied to each inverter circuit during the material determination of the load. The material and shape of the load can be determined.

  In a second aspect of the invention, in particular, in the first aspect of the invention, the load determination unit determines the material and shape of the load placed on the first or second heating coil. When at least one of them is performing the heating operation, the control unit stops the output of the inverter circuit corresponding to the heating coil on the side performing the heating operation, and the input current detected by the input current detection means is a predetermined value. After the value is lowered to the value, the material and shape of the load placed on the first or second heating coil are discriminated.

Thus, in a circuit configuration in which the input current detection means for detecting the input current supplied from the AC power supply is shared for a plurality of inverter circuits, the inverter circuit is mounted on the heating coil based on the output result of the input current detection means. Even when the material and shape of the placed load are discriminated, the material and shape of the load can be discriminated with high accuracy without being affected by residual charges in the circuit of the input current detecting means.

  In particular, according to a third invention, in the first or second invention, the first control element detection means detects the resonance current of the first heating coil, and the second control element detection means. The means is a second resonance current detection means for detecting the resonance current of the second heating coil, and the load determination unit determines the material and shape of the load placed on the first or second heating coil. Sometimes, when the heating coil on the discrimination target side is performing a heating operation, the control unit stops the output of the inverter circuit on the discrimination target side, and the resonance current detected by the resonance current detecting means on the discrimination target side is a predetermined value. The material and shape of the load placed on the first or second heating coil are discriminated after the value is lowered to the value.

  Thus, in a circuit configuration in which the input current detection means for detecting the input current supplied from the AC power supply is shared for a plurality of inverter circuits, the output result of the input current detection means and the first or second resonance Even when determining the material and shape of the load placed on the heating coil based on the output result of the current detection means, the residual charge in the circuit of the first or second resonance current detection means and the first or second The material and shape of the load can be determined with high accuracy without being affected by the residual charge in the resonance circuit 2.

  In particular, according to a fourth invention, in the first or second invention, the first control element detection means detects the resonance voltage of the first resonance capacitor, and the second control element detection means. The means is a second resonance voltage detection means for detecting the resonance voltage of the second resonance capacitor, and the load determination unit determines the material and shape of the load placed on the first or second heating coil. Sometimes, when the heating coil on the discrimination target side is performing a heating operation, the control unit stops the output of the inverter circuit on the discrimination target side, and the resonance voltage detected by the resonance voltage detection means on the discrimination target side is a predetermined value. The material and shape of the load placed on the first or second heating coil are discriminated after the value is lowered to the value.

  Thus, in a circuit configuration in which input current detection means for detecting input current supplied from an AC power supply is shared for a plurality of inverter circuits, the output result of the input current detection means and the output result of the resonance voltage detection means Even when determining the material and shape of the load placed on the heating coil based on the above, the residual charge in the circuit of the first or second resonance voltage detecting means and the residual charge in the first or second resonance circuit The material and shape of the load can be determined with high accuracy without being affected by electric charges.

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

(Embodiment 1)
FIG. 1 is a block diagram showing a circuit configuration of the induction heating apparatus according to the first embodiment of the present invention.

In FIG. 1, an induction heating apparatus according to a first embodiment of the present invention includes a rectifier circuit 2 that converts an AC power source 1 into DC, a first heating coil 8 that generates a high-frequency magnetic field and heats a load, and a first heating coil 8. Two heating coils 9, the first heating coil 8 and the second heating coil 9, the first resonance circuit 10 and the second resonance circuit 11 constituting the first resonance circuit 10 and the second resonance circuit 11, respectively. A first inverter circuit 4 and a second inverter corresponding to the capacitor 7 and each of the first heating coil 8 and the second heating coil 9 are connected in parallel to the rectifier circuit 2 and input the output voltage of the rectifier circuit 2. Inverter circuit 5, one input current detecting means 3 comprising a current transformer or the like for detecting the sum of input currents supplied to the first inverter circuit 4 and the second inverter circuit 5, and an input current detecting means 3 for controlling the output of the first inverter circuit 4 and the second inverter circuit 5 in accordance with the output of the first inverter circuit 4, the material of the load generated in each of the first inverter circuit 4 and the second inverter circuit 5, and First control element detection means 14 and second control element detection means 15 for detecting a physical quantity that changes according to the shape, input current detection means 3 and first control element detection means 14 or second control element detection A load discriminating unit 12 discriminates the material and shape of the load placed on the first heating coil 8 and the second heating coil 9 based on the output of the means 15.

  The first inverter circuit 4 includes first switching means 16, the second inverter circuit 5 includes second switching means 17, and the control unit 13 includes the first switching means 16 and the second switching means 17. By driving, the direct current rectified and smoothed by the rectifier circuit 2 is converted into a high frequency alternating current, and the high frequency alternating current is supplied from the inverter circuit to the first heating coil 8 and the second heating coil 9.

  The control unit 13 increases or decreases the drive frequency or conduction time of the first switching means 16 or the second switching means 17 in order to control the input current detected by the input current detection means 3 to have a desired value. I am letting.

  The operation and action of the induction heating apparatus configured as described above will be described below with reference to FIGS.

  FIG. 2 is a flowchart of the operation of the induction heating apparatus in the first embodiment of the present invention.

  In FIG. 2, first, when the power switch is turned on, the induction heating device enters a standby mode waiting for heating. In step 10 (S10), the standby mode state is continued until heating is started.

  When heating is started by a heating start switch (not shown), the presence / absence of a load determination execution command on the first heating coil 8 is confirmed in step 20 (S20). When there is a load determination execution command on the first heating coil 8, the output of the second inverter circuit 5 is stopped in step 30 (S30), and the first heating coil 8 is mounted in step 40 (S40). The material and shape of the placed load are determined.

  In step 40 (S40), the material and shape of the load placed on the first heating coil 8 are determined using the current supplied to the first inverter circuit 4 and other electrical characteristics. Do.

  Next, in step 50 (S50), the presence / absence of a load determination execution command on the second heating coil 9 is confirmed. If there is a load determination execution command on the second heating coil 9, the output of the first inverter circuit 4 is stopped in step 60 (S60), and the second heating coil 9 is mounted in step 70 (S70). The material and shape of the placed load are determined.

  In step 70 (S70), as in step 40 (S40), the current is supplied to the second inverter circuit 5 and other electrical characteristics are used to place it on the second heating coil 9. The material and shape of the load is determined.

  Next, returning to step 20 (S20), the operations from step 20 (S20) to step 70 (S70) are repeated.

FIG. 3 is a graph showing changes in current supplied to the first inverter circuit 4 and the second inverter circuit 5 when determining the material and shape of the load according to the first embodiment of the present invention. It is a load material determination area | region figure in Embodiment 1 of invention.

  In FIG. 3, the upper graph shows the time change of the current supplied to the first inverter circuit 4, the middle graph shows the time change of the current supplied to the second inverter circuit 5, and the lower graph shows the input current. The time change of the current detected by the detection means 3, that is, the time change of the sum of the currents supplied to the first inverter circuit 4 and the second inverter circuit 5 is shown.

  As an example, FIG. 3 shows a case where the material and shape of the load placed on the second heating coil 9 are determined.

  As shown in FIG. 3, since the input current detection means 3 detects the sum of the currents supplied to the first inverter circuit 4 and the second inverter circuit 5, it is supplied with a high frequency current from the second inverter circuit 5. The output of the first inverter circuit 4 for supplying a high-frequency current to the first heating coil 8 is stopped while the material and shape of the negative caliper placed on the second heating coil 9 is being discriminated. Thus, the output value of the input current detection means 3 takes a value corresponding to the current value supplied to the second inverter circuit 5 and is supplied to the first inverter circuit 4 or the second inverter circuit 5. The material and shape of the load can be determined with high accuracy based on the current value.

  In the discrimination of the material and shape of the load placed on the first heating coil 8 or the second heating coil 9, the material is discriminated such as aluminum, iron / magnetic stainless steel, non-magnetic stainless steel, etc., and the shape is a knife. What is necessary is just to distinguish small items, such as a small diameter pan, no load.

  As a specific determination method, for example, in the present embodiment, the first control element detection means 14 or the second control element detection means 15 is used as the resonance of the first resonance capacitor 6 or the second resonance capacitor 7, respectively. As the voltage detection means, the resonance voltage on the inverter circuit side corresponding to the output of the input current detection means 3 when the driving frequency and conduction time of the first switching means 16 or the second switching means 17 are operated under constant conditions. Based on the output characteristics of the detection means, a discrimination region of material and shape as shown in FIG. 4 is determined and discriminated.

  For example, in this embodiment, the driving frequency and the conduction time of the first switching means 16 or the second switching means 17 are 23 kHz and the conduction time is 4 μsec.

  If it is determined that the load is a heating incompatible load, the heating by the corresponding heating coil is stopped.If the load is determined to be a heating compatible load, the output of the corresponding inverter circuit is adjusted based on the determined load material and shape. , Reduce the stress on the circuit.

  Further, the load discriminating unit 12 determines whether the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 is the first heating coil 8 or the second heating coil 9. When at least one of the heating operations is performed, the control unit 13 stops the output of the inverter circuit corresponding to the heating coil on the heating operation side, and the input current detected by the input current detection means 3 is the load The material and shape of the load placed on the first heating coil 8 or the second heating coil 9 are discriminated after the value is lowered to a predetermined value that does not hinder the discrimination of the material and shape.

Accordingly, even when the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 are determined based on the output result of the input current detection means 3, the input current detection means 3 is used. The material and shape of the load can be determined with high accuracy without being affected by the residual charge in the circuit.

  This is because the input current detection means 3 composed of a current transformer or the like employs a method called peak hold which estimates the timing of the maximum amplitude in each cycle of the current supplied by the AC power supply 1 and detects the current value at that time. In order to be able to detect a value close to the current value at the maximum amplitude even if the estimated maximum amplitude timing is slightly different from the actual maximum amplitude timing, a capacitor or the like is used for the circuit of the input current detection means 3. Therefore, the time constant of the electronic circuit is increased to maintain the current value at the maximum amplitude.

  Therefore, even when the output of the first inverter circuit 4 or the second inverter circuit 5 is stopped, the current value detected by the input current detecting means 3 does not instantaneously drop to zero due to the influence of the residual charge of the circuit, but slowly. Therefore, when determining the material and shape of the load immediately after stopping, there is a possibility that an unintended current value is detected and the material and shape of the load are erroneously determined. However, the current value by the input current detecting means 3 is This can be avoided by waiting until it falls to a predetermined value.

  An example of the predetermined value that does not hinder the determination of the material and shape of the load includes an initial value when the inverter circuit of the target detection circuit is not operating. Further, if it takes a long time for the value to decrease to the initial value when the circuit is not operating, the output element of the input current detecting means 3 in the predetermined region for determining the material and shape as shown in FIG. A value of 25% of the maximum value may be determined according to the circuit configuration, such as a predetermined value that does not hinder the determination of the material and shape of the load.

  Further, the first control element detection means 14 detects first resonance current detection means (not shown) for detecting the resonance current of the first heating coil 8, and the second control element detection means 15 indicates the second heating coil. 9 is a second resonance current detection means (not shown) for detecting the resonance current, and the first resonance current detection means and the second resonance current detection means comprise a current transformer or the like. When the heating coil on the discrimination target side performs the heating operation when the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 is discriminated, the control unit 13 After the output of the inverter circuit on the side is stopped and the resonance current detected by the resonance current detection means on the discrimination target side falls to a predetermined value that does not hinder the discrimination of the material and shape of the load, the first heating is performed Coil 8 or second Doing the material of the placement of the heating coil 9 load and pattern discrimination.

  Thereby, even when the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 are determined, the residual charge of the first resonance circuit 10 or the second resonance circuit 11 is determined. The material and shape of the load can be determined with high accuracy without being affected by the above.

  This is because the first and second resonance current detection means including a current transformer detect the resonance current by the above-described method of peak hold, and therefore, similar to the circuit of the input current detection means 3, The current value at the maximum amplitude is maintained by increasing the time constant, and even if the output of the first inverter circuit 4 or the second inverter circuit 5 is stopped, the first resonance current detecting means or the first The current value detected by the resonance current detecting means 2 does not instantaneously decrease to zero due to the influence of the residual charge of the circuit but slowly decreases.

  Therefore, when determining the material and shape of the load immediately after stopping, there is a possibility that an unintended current value is detected and the material and shape of the load are erroneously determined. This can be avoided by waiting until the current value by the resonance current detecting means decreases to a predetermined value.

  Further, since the resonance current flows in the first resonance circuit 10 or the second resonance circuit 11 in the circuit for a short time even when the current supplied to the circuit is stopped, it is not intended when determining the material and shape of the load. The load material and shape may be misidentified, but wait until the current value by the resonance current detection means on the target side where the load material and shape are identified falls to a predetermined value. This can be avoided.

  An example of the predetermined value that does not hinder the determination of the material and shape of the load includes an initial value when the inverter circuit of the target detection circuit is not operating. Also, if it takes a long time for the value to decrease to the initial value when the circuit is not operating, the output element of the resonant voltage detecting means in the predetermined region for determining the material and shape as shown in FIG. In the discrimination area replaced with the output of the current detection means, the circuit configuration is such that the value of 25% of the maximum value of the output element of the resonance current detection means is a predetermined value that does not interfere with the discrimination of the load material and shape. It may be determined accordingly.

  Further, the first control element detection means 14 detects first resonance voltage detection means (not shown) for detecting the resonance voltage of the first resonance capacitor 6, and the second control element detection means 15 indicates second resonance capacitor. 7 is a second resonance voltage detection means (not shown) for detecting the resonance voltage, and the first and second resonance voltage detection means are composed of a voltage dividing circuit by a plurality of resistors, etc. When the heating coil on the discrimination target side performs the heating operation when the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 is discriminated, the control unit 13 After the output of the inverter circuit on the side is stopped and the resonance voltage detected by the resonance voltage detecting means on the discrimination target side has dropped to a predetermined value that does not hinder the discrimination of the material and shape of the load, the first heating is performed Coil 8 or second Doing material and shape determination of the placed load heating coil 9.

  Thereby, based on the output result of the input current detection means 3 and the output result of the resonance voltage output means on the target side where the load material and shape are determined, the material of the load placed on the heating coil on the determination target side Even when the shape is determined, the material and shape of the load can be determined with high accuracy without being affected by the residual charge of the first resonance circuit 10 or the second resonance circuit 11.

  This is because the first resonance voltage detection means and the second resonance voltage detection means including a voltage dividing circuit using a resistor detect the resonance voltage by the above-described method of peak hold, so that the input current detection is performed. Similar to the circuit of means 3, the time constant of the electronic circuit is increased to maintain the voltage value at the maximum amplitude.

  Therefore, even if the output of the first inverter circuit 4 or the second inverter circuit 5 is stopped, the voltage value detected by the first or second resonance voltage detecting means is instantaneously zero due to the influence of the residual charge of the circuit. When the load material and shape are determined immediately after stopping, there is a possibility that an unintended voltage value is detected and the load material and shape are misidentified. This can be avoided by waiting until the current value by the resonance voltage detecting means on the target side where the shape determination is performed falls to a predetermined value.

  In addition, the first resonant circuit 10 or the second resonant circuit 11 generates a resonant voltage in the circuit for a short time even when the voltage supplied to the circuit is stopped. There is a possibility of detecting an unexpected voltage value and misidentifying the material and shape of the load, but wait until the voltage value by the resonance voltage detecting means on the target side where the material and shape of the load are determined falls to a predetermined value. This can be avoided.

  An example of the predetermined value that does not hinder the determination of the material and shape of the load includes an initial value when the inverter circuit of the target detection circuit is not operating. If it takes a long time for the value to decrease to the initial value when the circuit is not operating, the maximum output element of the resonance voltage detection means in the predetermined material and shape discrimination region as shown in FIG. A value of 25% of the value may be determined according to the circuit configuration, such as a predetermined value that does not hinder the determination of the material and shape of the load.

  Here, the input current supplied from the AC power supply 1 to the first inverter circuit 4 and the second inverter circuit 5 is detected for the two inverter circuits of the first inverter circuit 4 and the second inverter circuit 5. In the circuit configuration in which the input current detection means 3 is shared, the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 based on the output result of the input current detection means 3 Although the example in the case of performing the determination has been shown, it is sufficient that the number of inverter circuits similar to the first inverter circuit 4 or the second inverter circuit 5 is two or more for one input current detection means 3. The number is not limited to two.

  It should be noted that the number of rectifier circuits 2 may be one or more as compared with a circuit configuration including one input current detecting means 3 and the first inverter circuit 4 and the second inverter circuit 5, and is limited to one. Not what you want.

  In addition, although the induction heating apparatus in this invention points out induction heating cooking appliances etc., it should just be an apparatus which heats a load using the principle of electromagnetic induction, and it does not specifically limit it.

  The material and shape of the load are determined by the current supplied from the AC power source 1 to the first inverter circuit 4 and the second inverter circuit 5 and the resonance current of the first heating coil 8 or the second heating coil 9. It is possible to combine the characteristics such as the resonance voltage of the first resonance capacitor 6 or the second resonance capacitor 7, and here, the characteristics are supplied to the first inverter circuit 4 and the second inverter circuit 5. However, it is not particularly limited as long as it is a means capable of discriminating the material and shape of the load.

  As described above, in the circuit configuration in which the input current detection means 3 for detecting the input current supplied from the AC power supply 1 to the first inverter circuit 4 or the second inverter circuit 5 is shared, the input current detection means Even when the material and shape of the load placed on the first heating coil 8 or the second heating coil 9 are determined based on the output result 3, the first while the load material is being determined. Since the input current supplied to each of the inverter circuit 4 or the second inverter circuit 5 can be accurately detected, the material and shape of the load can be determined with high accuracy.

  As described above, the induction heating device according to the present invention has an output of the input current detection means in a circuit configuration in which the input current detection means for detecting the input current supplied from the AC power supply is shared for a plurality of inverter circuits. Even when determining the material and shape of the load placed on the heating coil based on the result, the material and shape can be determined with high accuracy. This is effective for an induction heating apparatus having a circuit configuration in which an input current detecting means for detecting an input current supplied to the circuit is shared.

1, 101, 201 AC power source 2, 202 Rectifier circuit 3, 103 Input current detection means 4, 204 First inverter circuit 5, 205 Second inverter circuit 6 First resonant capacitor 7 Second resonant capacitor 8, 206 1st heating coil 9, 207 2nd heating coil 10 1st resonance circuit 11 2nd resonance circuit 12 Load discriminating part 13 Control part 14 1st control element detection means 15 2nd control element detection means

Claims (4)

A rectifier circuit that converts an alternating current power source into a direct current, first and second heating coils that generate a high-frequency magnetic field and heat a load, and each of the first and second heating coils and first and second resonances The first and second resonant capacitors constituting the circuit and the first and second heating coils respectively correspond to the first and second heating coils, connected in parallel to the rectifier circuit, and input with the output voltage of the rectifier circuit A second inverter circuit; one input current detection means for detecting a sum of input currents supplied to the first and second inverter circuits; and the first and second outputs according to the output of the input current detection means. A control unit that performs output control of the two inverter circuits, and first and second controls that detect physical quantities that change according to the material and shape of the load generated in each of the first and second inverter circuits. Based on the outputs of the element detection means, the input current detection means and the first or second control element detection means, the material and shape of the load placed on the first and second heating coils are respectively determined. A load discriminating unit, and the control unit controls the other heating coil while the load discriminating unit discriminates the material and shape of the load placed on the first or second heating coil. An induction heating apparatus that stops the output of the inverter circuit on the high-frequency current supply side. The load discriminating unit controls when at least one of the first or second heating coils is performing a heating operation when discriminating the material and shape of the load placed on the first or second heating coil. The output of the inverter circuit corresponding to the heating coil on the side where the heating operation is performed is stopped, and after the input current detected by the input current detecting means falls to a predetermined value, the first or second heating The induction heating apparatus according to claim 1, wherein the material and shape of the load placed on the coil are discriminated. The first control element detection means detects first resonance current detection means for detecting the resonance current of the first heating coil, and the second control element detection means detects second resonance current of the second heating coil. The current detection means, and the load determination unit controls when the heating coil on the determination target side performs a heating operation when determining the material and shape of the load placed on the first or second heating coil. The unit stops the output of the inverter circuit on the discrimination target side and is placed on the first or second heating coil after the resonance current detected by the resonance current detection means on the discrimination target side has dropped to a predetermined value. The induction heating device according to claim 1 or 2, wherein the material and shape of the applied load are determined. The first control element detection means detects first resonance voltage detection means for detecting the resonance voltage of the first resonance capacitor, and the second control element detection means detects second resonance voltage of the second resonance capacitor. The voltage detection means, and the load determination unit controls when the heating coil on the determination target side is performing a heating operation when determining the material and shape of the load placed on the first or second heating coil. The unit stops the output of the inverter circuit on the discrimination target side and is placed on the first or second heating coil after the resonance voltage detected by the resonance voltage detection means on the discrimination target side drops to a predetermined value. The induction heating device according to claim 1 or 2, wherein the material and shape of the applied load are determined.