KR100868141B1 - Dc current detection method and apparatus for high-frequency power source apparatus - Google Patents

Abstract

assignment

Provided are a DC current detection method and apparatus capable of reducing the cost of a high frequency power supply suitable for feeding a high frequency induction heating device constituting a resonance circuit.

Resolution

The high frequency power supply HFP1 includes a smoothing capacitor circuit composed of condensers C ₁₁ to C 1 _n , a high frequency power conversion circuit composed of IGBTs Q ₁₁ to Q ₁₄ , a control circuit 11, and an alternating current detector 12. And a current calculator 14, an AC voltage detector 15, and an AC current detector 16. In this current calculator 14, an AC current detector is based on the output voltage Vo of the high frequency power conversion circuit. DC power supply for supplying DC power to the high frequency power supply from the output current Io of the high frequency power conversion circuit detected by (12) and the current Ic of the smoothing capacitor circuit detected by the AC current detector 16. From the current Idc equivalent current Idc * is obtained.

Description

DC CURRENT DETECTION METHOD AND APPARATUS FOR HIGH-FREQUENCY POWER SOURCE APPARATUS

1 is a circuit configuration diagram of a high frequency power supply showing a first embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the operation of FIG. 1

3 is a partial detailed circuit diagram of FIG.

4 is a circuit configuration diagram of a high frequency power supply showing a second embodiment of the present invention.

FIG. 5 is a waveform diagram illustrating the operation of FIG. 4. FIG.

FIG. 6 is a partial detailed circuit diagram of FIG. 4.

Fig. 7 is a circuit configuration diagram of a high frequency power supply showing a third embodiment of the present invention.

8 is a partial detailed circuit diagram of FIG. 7;

Fig. 9 is a circuit configuration diagram of a high frequency power supply showing a fourth embodiment of the present invention.

10 is a circuit configuration diagram of a high frequency power supply showing a conventional example

(Explanation of symbols for the main parts of the drawing)

11: control circuit 12: alternating current detector

13: DC current detector 14: current calculator

15 AC voltage detector 16 AC current detector

17, 18: current calculator 19: AC current detector

C ₁₁ to C _1n , Cr ₁ , Cr ₁₁ , Cr ₁₂ : condenser Lr ₁ , Lr ₁₁ : reactor

Q ₁₁ to Q ₁₄ : IGBT

Technical field

The present invention provides a method and apparatus for detecting a direct current input current in a high frequency power supply device in which a direct current power supplied from a direct current power source is converted into a high frequency power by a high frequency power conversion circuit to be supplied to a high frequency load. A plurality of sets are provided, and it is related with the optimal direct current input current detection method and apparatus in supplying electric power from one DC power supply which is common to these multiple sets of high frequency power supplies.

Background technology

Fig. 10 is a circuit arrangement drawing showing a conventional example of this kind of high frequency power supply device.

In FIG. 10, HFP1 to HFPk are k high frequency power supplies of the same configuration, and are connected to a DC power supply (DCP) having a power converter that rectifies and converts AC power supplied from a commercial AC power source into DC power. It is connected in parallel in common. The detailed structure of each high frequency power supply device is shown only with respect to the high frequency power supply device HFP1 as a representative. The high frequency power supply devices HFP1 to HFPk each include a smoothing capacitor circuit FC, a high frequency power conversion circuit INV, a control circuit 11 for controlling the power conversion circuit INV, and a high frequency power conversion circuit INV. It is provided with the load L from which the high frequency electric power is supplied.

The smoothing condenser circuit FC is configured by connecting n (n = 1, 2, 3, ...) condensers C ₁₁ to C _1n in parallel and connected in parallel to the DC input of the high frequency power conversion circuit INV. do.

The high frequency power conversion circuit INV is configured by connecting single-phase full bridges of switching circuits constituted by diodes D ₁₁ to D ₁₄ connected to the IGBTs Q ₁₁ to Q _{14 in} anti-parallel, respectively. .

The control circuit 11 maintains the AC output voltage output from the high frequency power conversion circuit INV in advance with respect to the AC output current so that the power supplied to the load L becomes the desired power set externally. Control the power conversion circuit INV. As for the load L connected to the AC output of the high frequency power conversion circuit INV, the high frequency induction heating apparatus comprised by the resonant circuit of the capacitor Cr ₁ and the reactor Lr ₁ is optimal.

In addition, in order to detect the current Io supplied to the load L, each of the high frequency power supply devices HFP1 to HFPk includes an AC current detector 12 made of an AC current transformer ACCT and a DC power supply DCP. In order to detect the DC current Idc (= Ii-Ic) supplied to the high frequency power supply HFP1, a DC current detector 13 made of a DC current transformer DCCT is provided. In addition, a DC voltage detector 20 is provided to detect a voltage of the DC power supply DCP.

The structure of such a high frequency power supply device is already well known by patent document 1 etc.

These k set high frequency power supply devices HFP1 to HFPk are connected in parallel to a common DC power supply DCP, and are applied to the DC voltage applied from the DC power supply DCP by the common DC voltage detector 20. (Vdc) is detected, and the DC current (Idc) supplied from the DC power supply (DCP) is individually detected by the DC current detector 13 provided in each high frequency power supply device, and the detected DC voltage (Vdc) is detected. And individually controlling the high frequency power conversion circuit INV by the respective control circuits 11 based on the DC current Idc, so that the power supply to the load L for each high frequency power supply device is desired. I can adjust it.

Patent Document 1: Japanese Patent Application Laid-Open No. 11-54249

According to the circuit configuration of the conventional high frequency power supply device as described above, in order to adjust the power supply to a load of a plurality of sets of high frequency power supply devices individually, the DC current detector 13 which consists of a direct current transformer (DCCT) is provided in each. Therefore, it is necessary to separately detect the direct current Idc supplied to each. However, the DC current detector 13 using this DC current transformer DCCT is very expensive compared with the AC current detector using AC current transformer ACCT. For this reason, especially when the number of sets of the high frequency power supply to be used increases, since the number of use of a DC current detector becomes large, the price of a device becomes high and this DC current detector reduces the price of this kind of high frequency power supply. It is a big factor that hinders.

An object of the present invention is to provide a direct current detection method and apparatus that can solve the above problems and reduce the cost of a high frequency power supply.

In order to solve such a subject, 1st invention provides the high frequency alternating current of the DC power supply, the smoothing capacitor circuit connected in parallel to the output of this DC power supply, and the DC power supplied from the said DC power supply via the said smoothing capacitor circuit. The high frequency power conversion circuit for converting into electric power, the high frequency load supplied with the high frequency power from the high frequency power conversion circuit, and the high frequency power conversion circuit such that the high frequency power supplied from the high frequency power conversion circuit to the high frequency load becomes the desired power. In the high-frequency power supply device configured by a control circuit for controlling the,

The DC current supplied from the DC power supply to the high frequency power supply is calculated by calculation from the polarity and the output current of the output voltage of the high frequency power conversion circuit and the current flowing through the smoothing capacitor circuit.

The second invention is the detection method of the direct current of the high frequency power supply device of the first invention, wherein the polarity of the output voltage is detected from the output of the AC voltage detector of the high frequency power conversion circuit.

A third aspect of the present invention provides a method for detecting a direct current of a high frequency power supply device according to the first aspect of the invention, wherein the polarity of the output voltage of the high frequency power conversion circuit is detected from a switching period of the switching element of the high frequency power conversion circuit. It is done.

4th invention is a detection method of the direct current of the high frequency power supply device of any one of said 1st-3rd invention, WHEREIN: The said smoothing capacitor circuit is comprised by connecting several capacitors in parallel, and this smoothing capacitor A current flowing through one capacitor in the circuit is detected, and a DC current supplied from the DC power supply to the high frequency power supply is calculated by calculation based on the detected current.

5th invention is a detection method of the direct current of the high frequency power supply device of any one of said 1st-4th invention,

The period in which the detected output voltage of the high frequency power conversion circuit is positive is the current in phase with the output current of the high frequency power conversion circuit, and the period is negative is the output current of the output current. The reverse phase current is calculated by calculation, and the direct current supplied from the direct current power source to the high frequency power supply is obtained by subtracting the alternating current flowing through the smoothing capacitor circuit from the current obtained by this calculation.

In the sixth invention, in the method for detecting the direct current of the high frequency power supply device according to any one of the first to fifth inventions, a plurality of sets of the high frequency power supply devices are provided, It is characterized by having a DC power supply common to each group.

The seventh invention is a high frequency power conversion for converting a DC power supply, a smoothing capacitor circuit connected in parallel to an output of the DC power supply, and a DC power supplied from the DC power supply through the smoothing capacitor circuit to high frequency AC power. A circuit, a high frequency load supplied with high frequency power from the high frequency power conversion circuit, and a control circuit controlling the high frequency power conversion circuit so that the high frequency power supplied from the high frequency power conversion circuit to the high frequency load becomes a desired power. In the configured high frequency power supply,

A first AC current detector for detecting an AC output current output from the high frequency power conversion circuit, a second AC current detector for detecting a capacitor current flowing in the smoothing condenser circuit, and an output voltage of the high frequency power conversion circuit. Polarity detecting means for detecting polarity, AC output current and in-phase current detected by said first AC current detector when this polarity detecting means shows positive polarity, and said first when it shows negative polarity. Current calculating means for obtaining an alternating current output and a reverse phase current detected by the AC current detector, and subtracting means for subtracting the capacitor current detected by the second AC current detector from the current obtained by the current calculating means. It is characterized by comprising a direct current detection means constituted by the.

In the eighth invention, in the DC current detection device of the high frequency power supply device according to the seventh invention, a plurality of sets of the high frequency power devices are provided, and the DC power supply of the plurality of sets of high frequency power devices is common to each set. do.

Implement the invention  Best form for

FIG. 1 is a circuit configuration diagram of a high frequency power supply device showing a first embodiment of the present invention, in which the same reference numerals are given to those having the same functions as the conventional configuration shown in FIG.

That is, k (k = 1, 2, 3, ...) sets of high frequency power supplies (HFP1 to HFPk), as shown in the block of the high frequency power supply (HFP1), respectively, a plurality of capacitors (C ₁₁ to C _1n ) AC current detector (CT) consisting of a high frequency power conversion circuit (INV), a control circuit (11), and an AC current transformer (ACCT) including a smoothing condenser circuit (FC), an IGBT (Q ₁₁ to Q ₁₄ ), and the like, connected in parallel. In addition to (12), an AC voltage detector 15 including a current calculator 14 to be described later, a voltage transformer PT for detecting an AC output voltage Vo of the high frequency power conversion circuit INV, and a smoothing capacitor circuit ( An AC current detector 16 using an AC current transformer ACCT that detects the current Ic flowing through FC is provided.

2 is a waveform diagram illustrating the operation of the DC current detection method of the high frequency power supply device HFP1.

As illustrated in FIG. 2A, the control circuit 11 constituting the high frequency power supply device HFP1 converts the AC output voltage Vo of the high frequency power conversion circuit INV to the output current Io. When the phase is in the preceding phase, the input current Ii to the high frequency power conversion circuit INV becomes a waveform as shown in Fig. 2B, and at this time, the current of the smoothing condenser circuit FC (Ic) has a waveform as shown in Fig. 2D.

As is apparent from the waveform diagram shown in FIG. 2, when the output frequency of the high frequency power supply device HFP1 is several tens of Hz or more, the input current Ii of the high frequency power conversion circuit INV includes an AC current component and a DC component. The AC component is supplied from the smoothing capacitor circuit FC as the current Ic, and the DC current component is supplied from the DC power supply DCP as the current Idc.

3 is a detailed circuit configuration diagram of the current calculator 14 shown in FIG. In FIG. 3, 14a is an inverting amplifier for inverting the polarity of the AC output current Io of the high frequency power conversion circuit INV detected by the AC current detector 12, 14b is a switching switch, and 14c is an AC voltage detector 15 14d is a comparator for detecting the polarity of the output voltage Vo of the high frequency power conversion circuit INV detected by the "

The comparator 14c in the current calculator 14 detects the polarity of the output voltage Vo, connects the contact of the changeover switch 14b to a on the Io side when the polarity is positive, and the changeover switch when the polarity is negative. A switching signal for switching and connecting the contacts of 14b to b on the inverting amplifier 14a side is issued. As a result, the output current Io is inverted by the in-phase when the output voltage Vo is positive from the output c of the selector switch 14b and reversed by the inverting amplifier 14a when the output voltage Vo is negative. Since the output c of the conversion switch 14b can be obtained, the operation input current Iis obtained from the output current Io of the waveform as shown in Fig. 2C can be obtained.

The waveform of this operational input current Iis becomes the same as the waveform of the input current Ii shown to FIG. 2 (b). That is, the current calculator 14 calculates the in-phase value when the output voltage Vo is positive with respect to the output current Io and calculates the inverse phase value when the output voltage Vo is negative. By performing the above, the calculation input current Iis equivalent to the input current Ii can be obtained.

Then, the subtractor 14d subtracts the condenser current Ic of the smoothing condenser circuit FC detected by the alternating current detector 16 from the calculated input current Iis obtained by this calculation. The direct current (Idc *) equivalent to the actual direct current (Idc) as shown in (e) is obtained, and can be used for control instead of the actual direct current (Idc).

Therefore, in the circuit configuration of the high frequency power supply device of the first embodiment shown in FIG. 1, the DC current detector 13 using a DC current transformer DCCT or the like which detects the DC current IDC supplied from the DC power supply DCP. The DC current Idc can be detected equivalently by the current calculator 14 and the AC voltage detectors 15 and 16 provided in place of (see FIG. 10).

The control circuit 11 together with the DC voltage Vdc detected by the DC voltage detector 20 to detect the DC current Idc equivalent to the actual DC current Idc supplied to each of the high frequency power supplies thus detected. And supplying to the load L by calculating the supply power to the load L connected to each high frequency power supply device by calculation, and controlling the high frequency power conversion circuit INV so that this power becomes a desired value. Power can be adjusted.

FIG. 4 is a circuit configuration diagram of a high frequency power supply device showing a second embodiment of the present invention, in which the same reference numerals are given to those having the same function as the configuration of the embodiment shown in FIG.

In the high frequency power supply HFP1 in the second embodiment shown in FIG. 4, a current calculator 17 to be described later is provided in place of the current calculator 14 shown in FIG. 1, respectively. Instead of the detection voltage of the AC voltage detector 15 shown in FIG. 1, a gate signal applied to the switching circuit of the high frequency power conversion circuit INV is applied to the current calculator 17.

The other high frequency power supply devices HFP2 to HFPk are shown in blocks only, but are configured similarly to this high frequency power supply device HFP1.

Fig. 5 is a waveform diagram illustrating the operation of the DC current detection method of the high frequency power supply HFP1 in the second embodiment.

As shown in FIG. 5A, the control circuit 11 constituting the high frequency power supply device HFP1 converts the AC output voltage Vo of the high frequency power conversion circuit INV to the output current Io. When operating in a phase with respect to the phase, the gate signal to the IGBT ((Q ₁₁ ) to (Q ₁₄ )) of the switching circuit constituting the high frequency power conversion circuit INV is shown in Fig. 2B. As described above, a square wave shape is changed at timings at which the respective IGBTs are turned on and off near the zero cross point of the output voltage Vo.

6 is a detailed circuit configuration diagram of the current calculator 17 shown in FIG. In this figure, 17a is an inverting amplifier inverting the polarity of the output current Io of the high frequency power conversion circuit INV detected by the alternating current detector 12, 17b is a switching switch, and 17c is an IGBT (Q ₁₁ (Q _14). And flip-flop circuit 17d operating by the gate signal to Q ₁₂ (Q ₁₃ )) is a subtractor.

In the current computing unit 17, a flip-flop circuit (17c), said Q ₁₁ (Q ₁₄₎ when the to the gate signal is turned on to the switching signal for connecting the contacts of the change-over switch (17b) on the Io side a When the gate signal to Q ₁₂ (Q ₁₃ ) is turned on, the switching signal 17b is operated to emit a switching signal for connecting the contact point of the switching switch 17b to b on the inverting amplifier 17a side. As shown in the figure, the switching signal CS is generated in synchronization with the gate signals Q ₁₁ and Q ₁₂ . The change in the switching signal CS is synchronized with the change in the polarity of the output voltage Vo. Therefore, this flip-flop circuit 17c has a function of discriminating the polarity of the output voltage Vo of the high frequency power conversion circuit INV, similar to the comparator 14c in the first embodiment.

From the output c of the switching switch 17b which performs the switching operation according to the switching signal CS from the flip-flop circuit 17c, the period in which the output voltage Vo is also positive is in phase with the output current Io. The output period of the negative phase is inverted by the inverting amplifier 17a so that the output of the reverse phase with the output current Io is taken out, and the operational input current Iis of the waveform as shown in Fig. 5D. ) Can be obtained. The waveform of the operation input current Iis becomes the waveform similar to the waveform of the input current Ii (see FIG. 2B). Then, the subtractor 17d subtracts the current Ic of the smoothing capacitor circuit FC detected by the AC current detector 16 from the operational input current Iis, similarly to the case of the first embodiment. The current Idc * (see FIG. 2E) equivalent to the current Idc supplied to the high frequency power conversion circuit INV from the DC power supply can be obtained.

Therefore, in the high frequency power supply device of the second embodiment, the current calculator 17 and the AC current detector 16 are replaced with the DC current detector 13 (see Fig. 10) which detects the DC current from the DC power supply. By providing it, the DC current supplied to the high frequency power conversion circuit can be detected equivalently. According to this second embodiment, the AC voltage detector 15 in the first embodiment shown in FIG. 1 can also be omitted.

FIG. 7 is a circuit configuration diagram of a high frequency power supply device showing a third embodiment of the present invention, in which the same reference numerals are given to those having the same function as the first embodiment shown in FIG. .

The high frequency power supply HFP1 in the third embodiment shown in FIG. 7 is smoothed with the current calculator 18 described later in place of the current calculator 14 and the AC current detector 16 shown in FIG. An alternating current detector (CT) 19 including an alternating current transformer (ACCT) for detecting the current (Ic ₁ ) of one capacitor (C ₁₁ ) in the condenser circuit (FC) is provided. The gate signal supplied to the switching circuit of the high frequency power conversion circuit INV from the control circuit 11 is applied to the current calculator 18 instead of the detected voltage of the AC voltage detector 15 in FIG. 1.

Moreover, the high frequency power supply devices HFP2 to HFPk other than the high frequency power supply device HFP1 are also comprised similarly to this high frequency power supply device HFP1.

FIG. 8 shows a detailed circuit configuration diagram of the current calculator 18 used in this third embodiment. In FIG. 8, 18a is an inverting amplifier for inverting the polarity of the AC output current Io of the high frequency power conversion circuit INV detected by the AC current detector 12, 18b is a switching switch, and 18c is an IGBT (Q ₁₁ ( The flip-flop circuit operated by the gate signal to Q ₁₄ ) and Q ₁₂ (Q ₁₃ )), 18d is the smoothing capacitor circuit with n times the current Ic ₁ of the capacitor C ₁₁ of the smoothing capacitor circuit FC. The amplifier 18e is a subtractor so as to be almost equal to the entire current Ic of.

In the current calculator 18, the flip-flop circuit 18c, like the flip-flop circuit 17c in the second embodiment, turns on the switch when the gate signal to the IGBT Q ₁₁ (Q ₁₄ ) is turned on. A switching signal for connecting the contact of 18b) to the Io side is issued, and when the gate signal to the IGBT Q ₁₂ (Q ₁₃ ) is turned on, the contact of the switching switch 18b is connected to the inverting amplifier 18a side. To generate a switching signal for the operation. When the switching switch 18b receives the switching signal from the flip-flop circuit 18c and performs the switching operation, the operational input current Iis of the waveform as shown in Fig. 5D is taken out from the output terminal thereof. do. This operational current Iis becomes a waveform of the input current Ii of the high frequency power conversion circuit INV shown in FIG. 2B as in the case of the above-described embodiment.

The current Ic1 of one condenser C ₁₁ is the current of the entire smoothing condenser circuit FC when all capacitors connected in parallel with n condensers C ₁₁ to C _1n are selected to have the same capacitance. Since it becomes 1 / n of (Ic), by amplifying by n times by the amplifier 18d, the electric current Ic of the whole smoothing capacitor circuit FC can be calculated | required equivalently.

The subtractor 18e is supplied with the above-mentioned operational input current Iis and the entire capacitor current Ic of the equivalent smoothing capacitor circuit FC obtained by the above-described amplifier 18d, where subtracting Ic from Iis. By performing the calculation, it is possible to obtain the current Idc * equivalent to the current Idc supplied from the DC power supply DCP.

Therefore, in the circuit configuration of the high frequency power supply device of the third embodiment shown in Fig. 7, the DC current detector 13 using the DC transformer DCCT for detecting the DC current IDC supplied from the DC power supply DCP ( Instead of FIG. 10, by providing the current calculator 18 and the AC current detector 19, the above-described direct current Idc can be detected equivalently.

In this third embodiment, since the current flowing through one capacitor of the smoothing capacitor circuit formed by connecting n capacitors in parallel is detected, the current flowing through the smoothing capacitor circuit FC is determined. In the current detector 19, the current to be detected is lowered to 1 / n than the AC current detector 16 used in the first and second embodiments shown in FIGS. 1 and 4. For this reason, according to this third embodiment, a small-capacity one can be used as the AC current detector 19, and the cost of the device can be reduced by that.

In addition, in this third embodiment, the case where the AC current detector 19 is provided in place of the AC current detector 16 of the second embodiment is shown. However, the AC current detector 16 of the first embodiment is shown. Alternatively, the AC current detector 19 may be provided. That is, as in the case of the first embodiment, the AC voltage detector 15 is provided, and the detected voltage is applied to the current calculator 18 in place of the gate signal to the switching circuit of the high frequency power converter INV to supply the current. It is also possible to perform calculations.

9 is a circuit configuration diagram of a high frequency power supply device showing a fourth embodiment of the present invention. In this figure, those having the same functions as those in the embodiment shown in Fig. 4 are given the same reference numerals.

The high frequency power supply HFP1 in the fourth embodiment shown in FIG. 9 has a smoothing capacitor circuit composed of condensers C ₁₁ to C 1 _n , and a single phase half bridge type composed of IGBTs Q ₁₁ and Q ₁₂ . To detect the current Io of the load L composed of a resonant circuit consisting of a high frequency power conversion circuit INV, a control circuit 11a, a capacitor Cr ₁₁ , Cr ₁₂ , and a reactor Lr ₁₁ . It consists of an alternating current detector 12, an alternating current detector 16 which detects the current Ic of the smoothing capacitor circuit, and a current calculator 17.

The other high frequency power supply devices HFP2 to HFPk are also configured similarly to this high frequency power supply device HFP1.

The control circuit 11a of the high frequency power supply device HFP1 desires a high frequency power conversion circuit by keeping the output voltage of the high frequency power conversion circuit of the single-phase half bridge type in a prephase with respect to the output current by a known technique. The current calculator 17 operates in the same manner as the current calculator 17 shown in FIG. 6 in the second embodiment described above, and performs the operation of controlling the output state. Is based on the AC output current Io of the high frequency power converter INV and the current Ic of the smoothing capacitor circuit FC detected by the AC current detector 16, respectively. The DC current Idc * equivalent to the DC current Idc supplied to the power supply device HFP1 can be calculated by calculation.

In the high frequency power supply device for supplying a high frequency load such as a high frequency induction heating apparatus, the present invention has an output frequency of several tens of kHz or more, and the AC current component of the input current to the high frequency power conversion circuit is described above. It is made from the fact that it is supplied from a smoothing capacitor circuit, and a DC current component is supplied from a DC power supply. In other words, by performing an operation of inverting the output current of the high frequency power conversion circuit only during the non-period period of the AC output voltage of the high frequency power conversion circuit, the input current of the high frequency power converter is obtained, and the smoothing capacitor circuit is obtained from the input current obtained by this calculation. The DC current supplied to this high frequency power supply device can be obtained by subtracting the current flowing in the. Thereby, using a relatively inexpensive AC current detector that detects the current to the smoothing capacitor circuit, instead of a relatively expensive DC current detector to detect the DC current from the DC power source, equivalently high frequency power from the DC power source. Since the DC current supplied to the conversion circuit can be detected, the cost of the high frequency power supply device can be reduced.

Claims (8)

A direct current power source, a smoothing capacitor circuit connected in parallel to the output of the direct current power source, a high frequency power conversion circuit for converting the direct current power supplied from the direct current power source through the smoothing capacitor circuit into high frequency AC power, and the high frequency power conversion A high frequency power supply device comprising a high frequency load supplied with a high frequency power from a circuit and a control circuit for controlling the high frequency power conversion circuit such that the high frequency power supplied from the high frequency power conversion circuit to the high frequency load is a desired power. The period in which the polarity of the output voltage of the high frequency power conversion circuit is positive is the current in phase with the output current of the high frequency power conversion circuit, and the negative period is the current in the reverse phase of the output current. And a DC current supplied from the DC power supply to the high frequency power supply by subtracting an AC current flowing through the smoothing capacitor circuit from the obtained current. The method of claim 1, And detecting the polarity of the output voltage from the output of the alternating voltage detector of the high frequency power conversion circuit. The method of claim 1, And detecting the polarity of the output voltage of the high frequency power conversion circuit from the switching period of the switching element of the high frequency power conversion circuit. The method according to any one of claims 1 to 3, The smoothing condenser circuit is constituted by connecting a plurality of condensers in parallel, detecting current flowing through one of the smoothing condenser circuits, and supplied to the high frequency power supply from the DC power supply by calculation based on the detected current. A direct current detection method of a high frequency power supply, characterized by obtaining a direct current. delete The method according to any one of claims 1 to 3, A plurality of sets of the high frequency power supply units are provided, and the DC power supply of the plurality of sets of the high frequency power supply units is common to each group. A direct current power source, a smoothing capacitor circuit connected in parallel to the output of the direct current power source, a high frequency power conversion circuit for converting the direct current power supplied from the direct current power source through the smoothing capacitor circuit into high frequency AC power, and the high frequency power conversion A high frequency power supply device comprising a high frequency load supplied with a high frequency power from a circuit and a control circuit for controlling the high frequency power conversion circuit such that the high frequency power supplied from the high frequency power conversion circuit to the high frequency load is a desired power. A first AC current detector for detecting an AC output current output from the high frequency power conversion circuit, a second AC current detector for detecting a capacitor current flowing in the smoothing condenser circuit, and an output voltage of the high frequency power conversion circuit. Polarity detecting means for detecting polarity, AC output current and in-phase current detected by said first AC current detector when this polarity detecting means shows positive polarity, and said first when it shows negative polarity. Current calculating means for obtaining an alternating current output and a reverse phase current detected by the AC current detector, and subtracting means for subtracting the capacitor current detected by the second AC current detector from the current obtained by the current calculating means. Of a high frequency power supply, characterized by comprising a direct current detection means configured by DC current detection device. The method of claim 7, wherein A plurality of sets of the high frequency power supply devices are provided, and the DC power supply of the plurality of sets of the high frequency power supply devices is common to each set. The DC current detection device of the high frequency power supply device.

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