JP2005065473A - Three-phase power supply phase interruption detection circuit and high-frequency heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase power supply phase interruption detection circuit capable of detecting phase interruption, even when only one phase is interrupted. <P>SOLUTION: If either of R-phase or S-phase of the three-phase power supply 100 is interrupted, a period such that the potential at a M-point is at least the bias potential of a transistor 24 is shorter than in the case electric power is properly supplied from the R-phase and the S-phase, so that the period from the time a capacitor 26 is charged once until it is discharged becomes long and the input voltage to a comparator 21 becomes high. Thus, the comparator 21 outputs a "High" signal when the electric power is properly supplied from the R-phase and the S-shape, and a "Low" signal, if at least one of the R-phase or the S-phase is interrupted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a three-phase power supply phase missing detection circuit and a high-frequency heating device, and in particular, even when power is supplied from a three-phase power supply and at least one of the three-phase power supply lines of the three-phase power supply is missing. The present invention relates to a three-phase power supply phase loss detection circuit and a high-frequency heating device.

  2. Description of the Related Art Conventionally, in order to receive a large amount of power, some microwave generators and the like receive power from a three-phase power source, and various techniques for such devices have been disclosed.

  For example, in Patent Document 1, when microwaves are generated by three magnetrons in a microwave generator, power is supplied to the filaments of each magnetron tube using three filament transformers connected between phases of a three-phase power source. In addition, the anode of each magnetron is transformed by a three-phase AC voltage adjusted by a single three-phase power regulator and transformed by three high-voltage transformers connected between the phases. A technique for enabling microwaves to be output with an inexpensive configuration is disclosed.

  Further, as an example of a conventional apparatus that receives power supply from a three-phase power source, an apparatus having an electrical configuration schematically shown in FIG. 13 can be cited.

In the apparatus shown in FIG. 13, the circuit including the inverter circuit 1 is supplied with power from the three-phase power source 100. Specifically, in the apparatus shown in FIG. 13, the inverter circuit 1 is connected to the three-phase power source 100 via the smoothing circuit including the coil 8 and the capacitor 9 and the rectifier circuit 3. The drive of the inverter circuit 1 is controlled by the control circuit 5 via the drive circuit 2. The rectifier circuit 3 is connected to the R-phase, S-phase, and T-phase of the three-phase power source 100 via the relay switches 11, 12, 13, and the relay switches 11, 12, 13 are opened and closed. Is controlled by the relay drive circuit 4. The relay drive circuit 4 receives power supply from the power supply circuit A6, and the control circuit 5 receives power supply from the power supply circuit B7. The power supply circuit A6 is supplied with power from the three-phase power supply 100 by being connected to the R-phase and S-phase of the three-phase power supply 100. The power supply circuit B7 is supplied with power from the three-phase power supply 100 by being connected to the R phase and the T phase of the three-phase power supply 100.
JP 2001-148284 A

  In the apparatus as shown in FIG. 13, when only one of the R phase, S phase, and T phase of the three-phase power supply 100 is missing, the power supply circuit A6 and the power supply circuit B7 are connected to the missing phase. The circuit that is present is affected by the power supply, but the circuit that is not connected to the missing layer is not affected by the power supply. Therefore, when only one of the R phase, S phase, and T phase of the three-phase power supply 100 is missing, either the relay drive circuit 4 or the control circuit 5 is not affected by the operation, but the other is A situation occurs that is affected by the operation.

  In other words, in the conventional apparatus as shown in FIG. 13 that receives power supply from the three-phase power supply, when only one of the R-phase, S-phase, and T-phase of the three-phase power supply is missing, the apparatus There is a problem in that it is difficult to determine the effect of the lack from the operating state of.

  The present invention has been conceived in view of such a situation, and an object of the present invention is to detect a missing three-phase power supply phase and a high-frequency signal, even when only one phase of the three-phase power supply is missing. It is to provide a heating device.

  A three-phase power supply phase loss detection circuit according to an aspect of the present invention is a phase loss detection circuit for a three-phase power supply that supplies power via first, second, and third phases, Including a first circuit portion connected to the first and second phases of a three-phase power source, and a second circuit portion connected to the second and third phases of the three-phase power source, The first circuit portion is applied when a voltage is applied from both the first and second phases and when a voltage is applied from at least one of the first or second phase. The second circuit unit outputs a different signal when the voltage is applied from both the second and third phases, and the voltage from at least one of the second or third phase. It is characterized in that different signals are output when no is applied.

  According to an aspect of the present invention, it is possible to detect that at least one of the first phase and the second phase is missing by detecting a signal output from the first circuit unit. Further, by detecting a signal output from the second circuit unit, it can be detected that at least one of the second phase and the third phase is missing.

  In the three-phase power supply phase loss detection circuit according to the present invention, the first circuit unit includes a first capacitor, a timing of applying a voltage from the first phase, and a voltage from the second phase. First charging means for charging the first capacitor according to the timing of voltage application, and first signal output means for outputting a different signal according to the potential of the first capacitor, The second circuit unit charges the second capacitor in accordance with the timing of applying the voltage from the second capacitor and the voltage from the second phase and the timing of applying the voltage from the third phase. It is preferable to include a second charging unit and a second signal output unit that outputs different signals according to the potential of the second capacitor.

  As a result, when the first or second phase is lost and voltage application from at least one of them is no longer applied, the amount of power charged in the first capacitor compared to the state in which voltage is applied from both sides is reduced. In response, the potential of the first capacitor also changes. Therefore, by detecting the signal output from the first signal output means, it is possible to detect that at least one of the first or second phase is missing. Further, when the second or third phase is missing and voltage application from at least one of these is eliminated, the amount of power charged in the second capacitor changes compared to the state in which voltage is applied from both. In response to this, the potential of the second capacitor also changes. Therefore, by detecting the signal output from the second signal output means, it is possible to detect that at least one of the second or third phase is missing.

  A high-frequency heating device according to another aspect of the present invention is supplied with electric power from a three-phase power source having first, second, and third phases via the first to third phases. A high-frequency heating device, connected between the heating means, the power supply control means for controlling the supply of power from the three-phase power supply to the heating means, the three-phase power supply and the power supply control means, Phase loss detection means for detecting phase loss of the three-phase power supply, wherein the phase loss detection means includes a first circuit unit connected to the first and second phases of the three-phase power supply, And a second circuit portion connected to the second and third phases of a three-phase power source, and the first circuit portion is applied with a voltage from both the first and second phases. And when no voltage is applied from at least one of the first and second phases. And the second circuit unit receives a voltage from both the second and third phases and a voltage from at least one of the second or third phase. Different signals are output when not applied.

  According to another aspect of the present invention, at least one of the first phase and the second phase is detected in a three-phase power supply to which the high-frequency heating device is supplied with power by detecting a signal output from the first circuit unit. It can be detected in the high-frequency heating device that one of them is missing. Further, by detecting a signal output from the second circuit unit, at least one of the second phase or the third phase is missing in the three-phase power source to which the high-frequency heating device is supplied, It can detect in the said high frequency heating apparatus.

  In the high-frequency heating device according to the present invention, the power supply control means is connected to the first and second phases, and the first rectifying the power supplied from the first and second phases. A rectifier circuit, connected to the second and third phases, connected to the second and third phases, a second rectifier circuit for rectifying power supplied from the second and third phases, and the third and first phases A third rectifier circuit that rectifies the power supplied from the third and first phases, and the heating means includes a magnetron connected to each of the first to third rectifier circuits. Is preferred.

  As a result, in the high-frequency heating device, a rectifier circuit is used between each of the three phases of the three-phase power supply, so that the harmonics predicted when the three phases are rectified by a single rectifier circuit with respect to the three-phase power supply Generation of current can be avoided.

  In the high-frequency heating device according to the present invention, the first circuit section includes a first capacitor, a timing of voltage application from the first phase, and a voltage application from the second phase. A first charging means for charging the first capacitor according to timing; and a first signal output means for outputting a different signal according to the potential of the first capacitor; A second capacitor that charges the second capacitor in accordance with a voltage application timing from the second phase and a voltage application timing from the third phase. And a second signal output means for outputting different signals according to the potential of the second capacitor.

  Accordingly, when the first or second phase is lost in the three-phase power supply to which the high-frequency heating device is supplied with power and voltage application from at least one of these is eliminated, voltage is applied from both sides in the high-frequency heating device. The amount of power charged in the first capacitor changes compared to the current state, and the potential of the first capacitor also changes accordingly. Accordingly, in the high-frequency heating device, it is possible to detect that at least one of the first or second phase is missing by detecting the signal output from the first signal output means. In addition, when the second or third phase is lost in the three-phase power source to which the high-frequency heating device is supplied and at least one of the voltages is not applied, the high-frequency heating device is applied with the voltage from both sides. The amount of electric power charged in the second capacitor is changed as compared with the current state, and the potential of the second capacitor is also changed accordingly. Therefore, in the high-frequency heating device, it is possible to detect that at least one of the second or third phase is missing by detecting the signal output from the second signal output means.

  According to the present invention, by detecting the signals output from the first circuit unit and the second circuit unit, even if a loss occurs only in any one of the first to third phases, The lack can be detected.

(First embodiment)
FIG. 1 is a diagram schematically showing an electrical configuration of an apparatus including a three-phase power supply phase loss detection circuit according to a first embodiment of the present invention.

  Referring to FIG. 1, the apparatus shown in FIG. 1 includes an inverter circuit 1 and a heating unit 15 that receives power supplied from the inverter circuit 1 and performs a heating operation on food or the like. The apparatus shown in FIG. 1 is a cooking apparatus such as a microwave oven or an electromagnetic cooker in which the heating unit 15 includes a magnetron or a heating coil. In addition, the apparatus including the three-phase power supply phase loss detection circuit according to the present invention is not limited to the cooking device, and any apparatus may be used as long as power is supplied from the three-phase power supply.

  1 is supplied with electric power from the three-phase power source 100, in addition to the device shown in FIG. 13, the driving circuit 2, the rectifier circuit 3, the relay driving circuit 4, the control circuit 5, and the power source Although circuit A6, power supply circuit B7, coil 8, capacitor 9, and relay switches 11-13 are included, these operations are the same as those described with reference to FIG. 13, and therefore description thereof will not be repeated here. The apparatus shown in FIG. 1 further includes a circuit unit 20 and a circuit unit 30.

  The circuit unit 20 includes a diode 22 connected to the R phase of the three-phase power supply 100, a diode 23 connected to the S phase of the three-phase power supply 100, a transistor 24 having a base terminal connected to the output side of the diodes 22 and 23, A power source 25 and a capacitor 26 connected to the collector side of the transistor 24, a comparator 21 connected to the collector side of the transistor 24 with the − side input terminal, and a power source 27 connected to the + side input terminal of the comparator 21 Including. In FIG. 1, a point between the collector-side terminal of the transistor 24 and the power supply 25 is a point P, and a point between the base-side terminal of the transistor 24 and the diodes 22 and 23 is an M point. Yes. The circuit unit 20 includes resistors 20A and 20B connected between the point M and the diodes 22 and 23, and resistors 20C and P connected between the point M and the grounded point, and the power source 25. A resistor 20D connected between the P point and the negative input terminal of the comparator 21, a resistor 20E connected between the positive input terminal of the comparator 21 and the power source 27, and And a resistor 20G connected between the input terminal on the + side of the comparator 21 and the grounded point. The terminal on the emitter side of the transistor 24 is grounded.

  The circuit unit 30 includes a diode 32 connected to the S phase of the three-phase power source 100, a diode 33 connected to the T phase of the three-phase power source 100, and a transistor having a base terminal connected to the output side of the diodes 32 and 33. 34, a power source 35 and a capacitor 36 connected to the collector side of the transistor 34, a comparator 31 having a negative input terminal connected to the collector side of the transistor 34, and a power source connected to a positive input terminal of the comparator 31 37. In FIG. 1, a point between the collector-side terminal of the transistor 34 and the power source 35 is a point Q, and a point between the base-side terminal of the transistor 34 and the diodes 32 and 33 is an N point. Yes. The circuit unit 30 includes resistors 30A and 30B connected between the N point and the diodes 32 and 33, a resistor 30C connected between the N point and the grounded point, and a point between the Q and the power source 35. A resistor 30D connected between the Q point and the negative input terminal of the comparator 31; a resistor 30F connected between the positive input terminal of the comparator 31 and the power source 37; and The resistor 30G is connected between the input terminal on the + side of the comparator 31 and the grounded point. The terminal on the emitter side of the transistor 34 is grounded.

  FIG. 2 is a diagram for explaining the circuit operation in the circuit unit 20 when power is normally supplied from the R phase and the S phase of the three-phase power supply 100.

  2A shows the potential at the point M, FIG. 2B shows the potential at the point P, FIG. 2C shows the input potential to the + side terminal and the − side terminal of the comparator 21, and FIG. D) shows the change of the signal output from the comparator 21 with respect to the change of time t.

  Since AC power supplied from the R phase and S phase of the three-phase power source 100 is rectified by the diodes 22 and 23, the potential at the point M is full-wave rectified as shown in FIG. It has a waveform like this. This is considered that the power supplied from the R phase is half-rectified and the power supplied from the S phase is half-rectified.

  When the potential at the point M reaches the bias potential (VB) of the transistor 24, a current flows through the transistor 24. When a current flows through the transistor 24, the potential at the point P is decreased from the potential V1 to 0 as shown in FIG. As shown in FIGS. 2 (A) and 2 (B), the potential at the point P is repeatedly set to 0 after reaching the potential V1 only for the time T1, in accordance with the change in the potential at the point M. Yes.

  When the transistor 24 does not pass a current, the capacitor 26 is charged, and when a current flows through the transistor 24, the capacitor 26 is discharged. The potential of the capacitor 26 depends on the potential of the power supply 25 and the length of time from when the capacitor 26 starts to be discharged until it is discharged.

  The potential input from the power supply 27 to the + side terminal of the comparator 21 is set to a potential higher by a predetermined value than the potential at which the capacitor 26 is charged for the time T1.

  Thereby, in the comparator 21, when the potential at the point M changes as shown in FIG. 2A, the potential inputted to the + side terminal is always applied as shown in FIG. Becomes higher than the potential input to the negative terminal. In response to this, the comparator 21 always outputs a High (H) signal as shown in FIG.

  FIG. 3 is a diagram for explaining the circuit operation in the circuit unit 20 when either the R phase or the S phase of the three-phase power supply 100 is missing. 3A shows the potential at the M point, FIG. 3B shows the potential at the P point, and FIG. 3C shows the input potential to the + side terminal and the − side terminal of the comparator 21. 3 (D) shows the change of the signal output from the comparator 21 with respect to the change of time t.

  If either the R phase or the S phase of the three-phase power supply 100 is missing, the potential at the point M is obtained by half-rectifying the power supplied from either one as shown in FIG. Become. As a result, the period during which the potential at the point M is equal to or higher than the bias potential VB is shortened, so that the potential at the point P is between the time T2 longer than the time T1 shown in FIG. 2 as shown in FIG. The value of the potential V1 is taken. In this way, by repeating the change in which the potential at the point P becomes 0 after maintaining the potential V1 for the time T2, the time (T2) from when the capacitor 26 is charged once until it is discharged is shown in FIG. The time (T1) in the case of using 2 is increased. For this reason, the potential input from the capacitor 26 to the negative terminal of the comparator 21 is higher than that described with reference to FIG.

  The potential input from the power source 27 to the positive terminal of the comparator 21 is higher than the potential at which the capacitor 26 has been charged for the time T1, but is lower than the potential at which the capacitor 26 has been charged for the time T2. It is assumed to be a potential. That is, as shown in FIG. 3C, after the capacitor is charged for the time T2, the potential input to the negative terminal of the comparator 21 becomes higher than the potential input to the positive terminal. Accordingly, as illustrated in FIG. 3D, the comparator 21 outputs a Low (L) signal.

  Note that when both the R phase and the S phase of the three-phase power supply 100 are missing, the transistor 24 does not flow current. Therefore, since the capacitor 26 is continuously charged, a potential higher than the potential shown in FIG. 3C is input to the negative side of the comparator 21. That is, even in this case, the comparator 21 outputs an L signal.

  As described above with reference to FIGS. 2 and 3, in the circuit unit 20, when the R phase and the S phase of the three-phase power supply 100 are normally supplying power, the comparator 21 outputs an H signal. When at least one of the R phase and the S phase of the three-phase power supply 100 is missing, the comparator 21 outputs an L signal.

  Further, as shown in FIG. 1, the circuit unit 30 has the same configuration as the circuit unit 20, including a comparator 31 corresponding to the comparator 21. Specifically, the circuit unit 30 corresponds to the diodes 32 and 33 corresponding to the diodes 22 and 23, the transistor 34 corresponding to the transistor 24, the power sources 35 and 37 corresponding to the power sources 25 and 27, and the capacitor 26. Capacitor 36. The N point corresponds to the M point, and the Q point corresponds to the P point. And by having such a structure, the situation similar to the circuit part 20 arises also in the circuit part 30 according to the state of the three-phase power supply 100. FIG. That is, in the circuit unit 30, the diode 32 and the diode 33 are connected to the S phase and the T phase of the three-phase power source 100, respectively, and the comparator 31 is normally supplied with power from the S phase and the T phase. If it is, an H signal is output, and if at least one of the S phase and the T phase is missing, an L signal is output.

  In the apparatus shown in FIG. 1, the comparator 21 and the comparator 31 are connected to the output detection circuit 10. Further, the output detection circuit 10 is connected to the power supply 41 via the resistor 40 and further connected to the control circuit 5. When the L signal is input from at least one of the comparator 21 or the comparator 31, the output detection circuit 10 loses any one of the R phase, S phase, and T phase of the three-phase power supply 100. It is determined that the control circuit 5 is operating, and the control circuit 5 is notified of abnormality and / or processing such as stopping the operation of the apparatus is executed.

  As described above, the process for detecting the phase loss of the three-phase power supply 100 performed in the apparatus shown in FIG. 1 is summarized as shown in the flowcharts of FIGS. The process will be described below with reference to FIGS. 4 and 5.

  First, in step S1 (hereinafter, step is omitted), the voltage between the R phase and the S phase of the three-phase power supply 100 is read, and in S2, in the comparator 21, the potential of the capacitor 26 and the positive side terminal of the comparator 21 are read. Is compared with the potential input to the. If the potential of the capacitor 26 is higher, in S3, the signal output from the comparator 21 is set to L, and in S4, either the R phase or the S phase of the three-phase power supply 100 or both phases are missing. The output detection circuit 10 sends information to the control circuit 5 to notify the abnormality and / or stop the operation. On the other hand, if the potential input to the + terminal of the comparator 21 is equal to or higher than the potential of the capacitor 26, the process proceeds to S5.

  In S5, the voltage between the R phase and the S phase is read again, and in S6, the comparator 31 compares the potential of the capacitor 36 with the potential input to the + side terminal of the comparator 31. If the potential of the capacitor 36 is higher, the signal output from the comparator 31 is set to L in S7, and in S8, either or both of the S phase and the T phase of the three-phase power source 100 are output in the output detection circuit 10. Is determined to be missing, and the output detection circuit 10 sends information that causes the control circuit 5 to perform abnormality notification and / or stop operation. On the other hand, if the potential input to the + side terminal of the comparator 31 is equal to or higher than the potential of the capacitor 36, the signal output from the comparators 21 and 31 is set to H in S9, and the three phases of the three-phase power source 100 in S10. When it is determined that there is no omission, no information is sent from the output detection circuit 10 to the control circuit 5, or information indicating that there is no omission in the three phases of the three-phase power supply 100 is sent. Thus, a normal operation is performed in the apparatus shown in FIG.

(Second Embodiment)
FIG. 6 is a diagram schematically showing an electrical configuration of an electromagnetic induction heating device to which electric power is supplied from the three-phase power source 100 according to the second embodiment of the present invention.

  The electromagnetic induction heating device shown in FIG. 6 heats the pan 101 with the heating coil 50.

  The electromagnetic induction heating device includes single-phase bridges 51 and 52, a choke coil 53, a smoothing capacitor 54, a resonance capacitor 55, and a switching element 56. The single-phase bridge 51 is composed of four diodes 51A to 51D, and the single-phase bridge 52 is composed of four diodes 52A to 52D.

  In the electromagnetic induction heating device shown in FIG. 6, two phases of the three-phase power source 100 are connected to the single-phase bridge 51, and the remaining one phase is connected to the single-phase bridge 52. Note that the connection terminal 52X of the single-phase bridge 52 is open.

  FIG. 7 schematically shows an electrical configuration of a conventional electromagnetic induction heating apparatus supplied with power from a three-phase power source as a comparison. The electromagnetic induction heating apparatus shown in FIG. 7 includes a heating coil 50, a choke coil 53, a smoothing capacitor 54, a resonance capacitor 55, and a switching element 56, similarly to the one shown in FIG. The electromagnetic induction heating device shown in FIG. 7 includes a three-phase bridge 500, and the three phases of the three-phase power source 100 are connected to the three-phase bridge 500.

  In the electromagnetic induction heating apparatus of the present embodiment, instead of using the three-phase bridge 500 as shown in FIG. 7, the single-phase bridges 51 and 52 are used, so that the single-phase bridge as shown in FIG. A cooling structure similar to that of an electromagnetic induction heating device supplied with power from a power source can be used. FIG. 8 is a diagram schematically and partially showing a structure for cooling the switching element 56 and the like in the electromagnetic induction heating apparatus of the present embodiment.

  Referring to FIG. 8, the electromagnetic induction heating device includes a cooling fan 58 and heat radiating fins 57. Single-phase bridges 51 and 52 and switching element 56 are attached to radiating fins 57 and cooled by wind sent from cooling fan 58. Note that it is difficult to attach the three-phase bridge 500 to the heat radiating fins 57.

  In other words, in the electromagnetic induction heating apparatus that is supplied with power to the three-phase power source as in the present embodiment, the single-phase bridges 51 and 52 are used instead of the three-phase bridge 500, thereby reducing the cooling structure. Since it can be made the same as that for supplying power to the single-phase power supply, it is not necessary to consider a new cooling structure, and it can be manufactured easily.

  In addition, since the single-phase bridge is more versatile in each stage than the three-phase bridge, the cost of the electromagnetic induction heating device can be increased by using the single-phase bridges 51 and 52 instead of using the three-phase bridge 500. Can be reduced.

  As shown in FIG. 6, the single-phase bridge 51 is connected to two phases of the three-phase power supply 100, and the single-phase bridge 52 is connected to the remaining one phase of the three-phase power supply 100. For this reason, as shown in FIG. 8, it is preferable that the single-phase bridge 51 is arranged closer to the cooling fan 58 than the single-phase bridge 52 so as to be easily cooled.

  In this embodiment, an electromagnetic induction heating device has been described as an example of a device that uses two single-phase bridges for a three-phase power source. However, the present invention is not limited to this, and other examples of such devices include electronic devices. A high-frequency heating device such as a range can be cited, and any other device that receives power supply from a three-phase power source can be cited.

(Third embodiment)
FIG. 9 is a diagram schematically showing an electrical configuration of the high-frequency heating device according to the third embodiment of the present invention. The high-frequency heating device according to the present embodiment is supplied with electric power from the three-phase power source 100 and includes three magnetrons, magnetrons 201, 301, and 401, and the single-phase bridge 200, 300, 400, choke coils 202, 302, 402, smoothing capacitors 203, 303, 403, resonance capacitors 204, 304, 404, switching elements 205, 305, 405, and high-voltage transformers 206, 306, 406 are provided. Yes.

  Single-phase bridge 200 is connected to the R-phase and S-phase of three-phase power supply 100, single-phase bridge 300 is connected to the R-phase and T-phase of three-phase power supply 100, and single-phase bridge 400 is S-phase of three-phase power supply 100. And connected to the T phase.

  That is, conventionally, when power is supplied from a three-phase power source to oscillate a high frequency from the magnetron, as shown in FIG. In this embodiment, power is supplied to the magnetron 601 through the smoothing capacitor 603, the resonance capacitor 604, the switching element 605, the high-voltage transformer 606, and the like. Power is supplied to three magnetrons using three single-phase bridges connected to two phases of each. Thereby, in this Embodiment, generation | occurrence | production of the harmonic which can be considered by using a three-phase bridge can be suppressed. The suppression of the generation of such harmonics will be described in detail below.

  FIG. 11 shows the phase of the voltage of each phase in the three-phase power source 100, and FIG. 12 shows the phase of the current flowing in each phase. In FIG. 11, the solid line indicates the phase of the R-phase voltage, the dotted line indicates the phase of the S-phase voltage, the broken line indicates the phase of the T-phase voltage, and the bold solid line indicates that these three phases are three-phase bridges. The phase of the rectified voltage when full-wave rectified is shown in FIG. 12A shows the phase of the R-phase current, FIG. 12B shows the phase of the S-phase current, and FIG. 12C shows the phase of the T-phase current.

  Referring to FIGS. 11 and 12, the phase of the voltage that is full-wave rectified by the three-phase bridge does not match the phase of the current of any phase. Thus, if there is a portion where the phase of voltage and current does not match, a harmonic current is generated based on that. Therefore, when the power supplied from the three-phase power source is rectified and used by the three-phase bridge, a filter for matching the phase of the harmonic current with the phase of the rectified voltage is required. However, among the filters for matching the harmonic current with the phase of the voltage for a high-frequency heating device that is actually used at home or the like, existing filters are too large to be mounted on such a device.

  On the other hand, in the high-frequency heating device of the present embodiment, three single-phase bridges 200, 300, and 400 are used instead of using a three-phase bridge. Thereby, for each phase of the three-phase power supply 100, a current having no phase difference with respect to the voltage can be supplied without using the filter as described above. Thereby, in the high frequency heating apparatus of this Embodiment, generation | occurrence | production of a harmonic current can be suppressed.

  Each embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. Moreover, it is thought that each embodiment can be implemented even if it is individual or combined as much as possible.

It is a figure which shows typically the electric constitution of the apparatus containing the three-phase power supply phase missing detection circuit which is the 1st Embodiment of this invention. In the apparatus of FIG. 1, it is a figure for demonstrating the circuit operation | movement in a circuit part when electric power is normally supplied from the R phase and S phase of a three-phase power supply. FIG. 2 is a diagram for explaining a circuit operation in the circuit unit when either the R phase or the S phase of the three-phase power supply is missing in the apparatus of FIG. 1. It is a flowchart of the process for detecting the missing phase of a three-phase power supply performed in the apparatus of FIG. It is a flowchart of the process for detecting the missing phase of a three-phase power supply performed in the apparatus of FIG. It is a figure which shows typically the electric constitution of the electromagnetic induction heating apparatus which is the 2nd Embodiment of this invention and which is supplied with electric power from a three-phase power supply. It is a figure which shows typically the electric structure of the conventional electromagnetic induction heating apparatus supplied with electric power from a three-phase power supply. It is a figure which shows typically and partially the structure for cooling the switching element etc. in the electromagnetic induction heating apparatus of FIG. It is a figure which shows typically the electric constitution of the high frequency heating apparatus which is the 3rd Embodiment of this invention. It is a figure which shows typically the electrical structure of the conventional high frequency heating apparatus supplied with electric power from a three-phase power supply. It is a figure which shows the phase of the voltage of each phase in a three-phase power supply. It is a figure which shows the phase of the electric current which flows into each phase in a three-phase power supply. It is a figure which shows typically the electric structure of the apparatus which receives supply of electric power from the conventional three-phase power supply.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Inverter circuit, 2 Drive circuit, 3 Rectifier circuit, 4 Relay drive circuit, 5 Control circuit, 6 Power supply circuit A, 7 Power supply circuit B, 8 Coil, 9, 26, 36 Capacitor, 11-13 Relay switch, 15 Heating part 20, 30 Circuit part, 21, 31 Comparator, 22, 23, 32, 33 Diode, 24, 34 Transistor, 25, 27, 35, 37 Power supply, 50 Heating coil, 51, 52, 200, 300, 400 Single phase Bridge, 53, 202, 302, 402 Choke coil, 54, 203, 303, 403 Smoothing capacitor, 55, 204, 304, 404 Resonance capacitor, 56, 205, 305, 405 Switching element, 57 Radiation fin, 58 Cooling Fan, 100 Three-phase power supply, 201, 301, 401 Magnetron.

Claims (5)

A phase loss detection circuit for a three-phase power supply that supplies power through first, second, and third phases,
A first circuit portion connected to the first and second phases of the three-phase power source;
A second circuit portion connected to the second and third phases of the three-phase power source,
The first circuit unit is applied with a voltage from both the first and second phases, and is not applied with a voltage from at least one of the first or second phase. And output a different signal,
The second circuit unit is applied with a voltage from both the second and third phases, and is not applied with a voltage from at least one of the second or third phases. And a three-phase power phase loss detection circuit that outputs different signals. The first circuit unit charges the first capacitor and the first capacitor in accordance with the timing of voltage application from the first phase and the timing of voltage application from the second phase. First charging means for performing, and first signal output means for outputting different signals according to the potential of the first capacitor,
The second circuit unit charges the second capacitor and the second capacitor in accordance with the voltage application timing from the second phase and the voltage application timing from the third phase. The three-phase power supply phase loss detection circuit according to claim 1, further comprising: a second charging unit that performs and a second signal output unit that outputs a different signal according to a potential of the second capacitor. A high-frequency heating device to which electric power is supplied from a three-phase power source having first, second, and third phases through the first to third phases,
Heating means;
Power supply control means for controlling the supply of power from the three-phase power source to the heating means;
Connected between the three-phase power supply and the power supply control means, and includes a phase loss detection means for detecting a phase loss of the three-phase power supply,
The phase missing detection means includes a first circuit unit connected to the first and second phases of the three-phase power supply, and a second circuit connected to the second and third phases of the three-phase power supply. With the circuit part of
The first circuit unit is applied with a voltage from both the first and second phases, and is not applied with a voltage from at least one of the first or second phase. And output a different signal,
The second circuit section is applied with a voltage from both the second and third phases, and is not applied with a voltage from at least one of the second or third phases. A high-frequency heating device that outputs different signals. The power supply control means includes
A first rectifier circuit connected to the first and second phases and rectifying power supplied from the first and second phases;
A second rectifier circuit connected to the second and third phases and rectifying power supplied from the second and third phases;
A third rectifier circuit connected to the third and first phases and rectifying power supplied from the third and first phases;
The high-frequency heating apparatus according to claim 3, wherein the heating unit includes a magnetron connected to each of the first to third rectifier circuits. The first circuit unit charges the first capacitor and the first capacitor in accordance with the timing of voltage application from the first phase and the timing of voltage application from the second phase. First charging means for performing, and first signal output means for outputting different signals according to the potential of the first capacitor,
The second circuit unit charges the second capacitor and the second capacitor in accordance with the voltage application timing from the second phase and the voltage application timing from the third phase. 5. The high-frequency heating device according to claim 3, further comprising: a second charging unit that performs and a second signal output unit that outputs a different signal according to a potential of the second capacitor.

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