JP2011186858A - Power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply device easily controlable and operable at a high frequency. <P>SOLUTION: The power supply device 1a includes an alternating-current power source 2, and a switching part 3 connected between the alternating-current power source 2 and first to (n)-th loads 14 of the alternating-current power source 2. The switching part 3 includes first to (n)-th switching circuits 3a, 3b...3n, and a control part 6. The first to (n)-th switching circuits 3a, 3b...3n are respectively constituted by a pair of anti-parallel connected semiconductor switching elements 8 and 9, and one end of the pair of the semiconductor switching elements 8 and 9 is connected in series between one end of the alternating-current power source 2 and one end of the respective loads 14, and the other end of the respective loads 14 is connected to the other end of the alternating-current power source 2, and the pair of the semiconductor switching elements 8 and 9 is constituted by series connection of a diode 10 and a transistor 11. The switching part 3 easily controlled at a high speed without requiring maintenance can be achieved by using the insulated gate bipolar transistor 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a power supply device. More specifically, the present invention relates to a power supply apparatus in which a switching unit is inserted between a power supply and a plurality of loads.

In an induction heating apparatus or melting furnace apparatus using a high frequency, a device that controls a plurality of heating coils that are loaded with a single high frequency or low frequency power source, or a device that uses a single high frequency power source in a time-sharing manner The configuration is as follows.
FIG. 8 is a circuit diagram showing a configuration of the switching circuit 51 used in the conventional power supply apparatus 50. As shown in FIG. 8, the switching circuit 51 of the power supply device 50 is inserted between a power source 52 and coils 53 and 54 serving as loads. The normal switching circuit 51 is composed of a switch composed of an electromagnetic contactor (called a magnet) and an air-driven mechanical contact.

  However, the mechanical switch is inexpensive, but the contact point has a long life, so that periodic replacement and maintenance are necessary. In addition, since the mechanical switch cannot operate at high speed, the operation speed is limited, so that power cannot be distributed in a short time.

Patent Document 1 discloses an induction heating device that heats a plurality of induction coils with a single power source.
FIG. 9 attached to this document is a diagram showing the induction heating device disclosed in Patent Document 1. As shown in FIG. 9, the induction heating device 55 includes a single power source 90, a control circuit 100 for the power source 90, and a first switching circuit 101 and a second switching circuit 102 controlled by the control circuit 100. It is configured. The induction heating device 55 heats the induction heating coil 80 including a plurality of sections 81, 82, 83. In each coil section, one terminal is connected to the switching circuit 101. The other terminal of each coil 81, 82, 83 is connected to the second switching circuit 102.

  The switching circuits 101 and 102 include thyristors or SCR antiparallel sets 101a, 101b, 101c, 102a, 102b and 102c. Each coil 81, 82, 83 is connected to one terminal 84, 86, 88 connected to one set of anti-parallel SCRs of the switching circuit 101 and the other connected to a set of anti-parallel SCRs of the switching circuit 102. Terminals 85 and 87. For example, for the terminals 84 and 85 at both ends of the coil 81, the terminal 84 of the coil 81 is connected to the anti-parallel SCR set 101a, and the terminal 85 of the coil 81 is connected to the anti-parallel SCR set 102a. Yes. A power supply 90 is connected to all anti-parallel SCR sets. The control circuit 100 controls the duration time of power supplied from the power supply 90 to the three coils 81, 82, and 83 by switching between the first switching circuit 101 and the second switching circuit 102.

Patent Document 2 discloses an induction heating apparatus that supplies electric power to a plurality of heating coils by a single inverter.
FIG. 10 is a diagram showing the induction heating device disclosed in Patent Document 2. As shown in FIG. In the induction heating apparatus 200, a first heating coil 261 is connected to an inverter inverse conversion unit 204. Further, the second heating coil 262 is connected to the inverter inverse conversion unit 204 via the thyristor pair 271 and 272 connected in reverse parallel, and the flow angle of the thyristor pair 271 and 272 connected in reverse parallel is the second control circuit. 211.

Special Table 2002-529906 JP 2009-32495 A

The thyristor used in Patent Documents 1 and 2 is an element that can handle a large current and can have a high breakdown voltage. However, since the thyristor is not a self-extinguishing type semiconductor device, a commutation circuit is required and is difficult to use. Furthermore, in recent years, the production amount of thyristors has greatly decreased, and there is a problem that maintenance becomes difficult when newly used in equipment.
In addition, the thyristor cannot be kept in the ON state unless a certain voltage is applied between the anode and the cathode, a gate signal is added, and a current equal to or higher than the holding current unique to the element is kept flowing. In other words, in order to turn on the thyristor, a voltage is applied in advance between the anode and the cathode, and a holding current flows. For this reason, when power from an AC power supply is supplied to a plurality of coils, there are problems such as a complicated control circuit and a restriction in controlling the flow angle of the thyristor.

  Furthermore, the thyristor can only perform switching from an AC commercial frequency to at most about 10 kHz, and cannot increase the speed. In addition, when controlling with a thyristor, it cannot be turned off until a reverse voltage is applied between the anode and the cathode of the thyristor.

  In view of the above problems, an object of the present invention is to provide a power supply device that can be easily controlled, operates at a higher frequency, and is easy to maintain.

  In order to achieve the above object, the power supply apparatus of the present invention includes one AC power supply and a switching unit connected between the AC power supply and the first to nth loads of the AC power supply, and switches the power supply apparatus. The unit includes first to n-th switching circuits and a control unit, and each of the first to n-th switching circuits includes a pair of semiconductor switching elements connected in reverse parallel, One end of the pair is connected in series between one end of the AC power source and one end of each load, the other end of each load is connected to the other end of the AC power source, and each of the pair of semiconductor switching elements includes a diode and a transistor And is connected in series.

In the above configuration, a switching circuit including a pair of semiconductor switching elements connected in reverse parallel may be further connected between the other end of each load and the other end of the AC power supply.
The transistor is preferably an insulated gate bipolar transistor, a MOSFET, or a bipolar transistor. The load is preferably a coil or a welding electrode.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the electric power supply apparatus which can distribute alternating current power to several load at high speed from one alternating current power supply with a simple switching part.

It is a circuit diagram which shows the structure of the electric power supply apparatus which concerns on the 1st Embodiment of this invention. It is a time chart for demonstrating an example of operation | movement of an electric power supply apparatus, (A) is the voltage of a power supply, (B) is _Vp1 , (C) is _Vn1 , (D) is _Vp2 , (E). V _n2 , (F) shows the voltage of the first coil, and (G) shows the waveform of the voltage of the second coil. It is a circuit diagram which shows the structure of the modification of the electric power supply apparatus of this invention. It is a circuit diagram which shows the structure of another modification of the electric power supply apparatus of this invention. It is a circuit diagram which shows the example which used the load of the electric power supply apparatus as the electrode for welding. It is a circuit diagram which shows another example which used the load of the electric power supply apparatus as the electrode for welding. It is a circuit diagram which shows the structure of the electric power supply apparatus which concerns on the 2nd Embodiment of this invention. It is a circuit diagram which shows the structure of the replacement circuit used with the conventional electric power supply apparatus. It is a figure which shows the induction heating apparatus disclosed by patent document 1. FIG. It is a figure which shows the induction heating apparatus disclosed by patent document 2. FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings based on some embodiments.
(First embodiment)
FIG. 1 is a circuit diagram showing a configuration of a first embodiment according to a power supply device 1 of the present invention. As shown in FIG. 1, the power supply device 1 includes an AC power supply 2 and a switching unit 3 connected to the power supply 2. A first coil 4 and a second coil 5 are connected to the switching unit 3. That is, the first coil 4 and the second coil 5 are loads of the power source 2.

  As the power source 2, a power source that generates alternating current, a high-power oscillator including a so-called voltage source inverter, or the like can be used.

  The switching unit 3 includes a first switching circuit 3 a that drives the first coil 4, a second switching circuit 3 b that drives the second coil 5, and a control unit 6.

The first switching circuit 3a and the second switching circuit 3b are each composed of a pair of semiconductor switching elements 8 and 9 that are connected in antiparallel. Each of the semiconductor switching elements 8 and 9 includes a series connection of a diode 10 and a three-terminal switching element 11. In the semiconductor switching element 8, the series connection of the diode 10 and the three-terminal switching element 11 is configured such that the power source 2 composed of alternating current is conducted in a positive half cycle. On the other hand, the series connection of the diode 10 and the three-terminal switching element 11 is such that the power source 2 consisting of alternating current is conducted in a negative half cycle so that the semiconductor switching element 9 is connected in reverse parallel to the semiconductor switching element 8. It is configured as follows. In the semiconductor switching elements 8 and 9, a freewheeling diode 12 is connected in antiparallel to the main electrode and the second main electrode of each switching element 11. For example, when the three-terminal switching element 11 is an n-channel insulated gate bipolar transistor, the first main electrode, the second main electrode, and the control electrode are called a collector, an emitter, and a gate, respectively. In this case, the cathode of the freewheeling diode 12 is connected to the collector of an insulated gate bipolar transistor (also called IGBT). The anode of the freewheeling diode 12 is connected to the emitter of the insulated gate bipolar transistor. The diode 10 is connected so that no current flows through the freewheeling diode 12 when a reverse voltage is applied to the switching element 11.
The freewheeling diode 12 is also called a flywheel diode or a freewheeling diode.

  As the diode 10, a diode having a large current and a high withstand voltage is used. As the three-terminal switching element 11, a transistor which is a so-called self-extinguishing semiconductor element can be used. Examples of such transistors include insulated gate bipolar transistors, field effect transistors such as FETs and MOS FETs (MOSFETs), and bipolar transistors. In the following description, the three-terminal switching element 11 is described as an n-channel insulated gate bipolar transistor.

  The reverse breakdown voltage of the diode 10 and the collector breakdown voltage of the insulated gate bipolar transistor 11 will be described as being at least three times the AC voltage of the power source 2. For example, if the voltage of the power source 2, that is, the effective voltage is 200V or 400V, the breakdown voltage of the transistor needs to be 600V or 1200V or more, respectively.

  In the first switching circuit 3a, one end of the power source 2 is connected to one end of the first switching circuit 3a, the other end of the first switching circuit 3a is connected to one end of the first coil 4, and the first coil The other end of 4 is connected to the other end of the power source 2. Accordingly, the first switching circuit 3 a is connected in series to the first coil 4.

In the upper semiconductor switching element 8 of the first switching circuit 3a, the anode of the diode 10 is connected to one end of the power supply 2, the cathode of the diode 10 is connected to the collector of the insulated gate bipolar transistor 11, and the insulated gate bipolar transistor Eleven emitters are connected to one end of the first coil 4. A control signal V _p1 is applied to the gate of the insulated gate bipolar transistor 11 from the control unit 6 so as to conduct at a predetermined conduction angle θ _p1 every half cycle on the positive side of the power supply 2.

In the lower semiconductor switching element 9 of the first switching circuit 3a, the emitter of the insulated gate bipolar transistor 11 is connected to one end of the power supply 2, the collector of the insulated gate bipolar transistor 11 is connected to the cathode of the diode 10, and the diode Ten anodes are connected to one end of the second coil 5. A control signal V _n1 is applied to the gate of the insulated gate bipolar transistor 11 from the control unit 6 so as to conduct at a predetermined conduction angle θ _n1 every half cycle on the negative side of the power supply 2.

  The second switching circuit 3 b is connected in series to the second coil 5. That is, one end of the power source 2 is connected to one end of the second switching circuit 3b, the other end of the second switching circuit 3b is connected to one end of the second coil 5, and the other end of the second coil 5 is connected to the power source. 2 is connected to the other end.

In the upper semiconductor switching element 8 of the second switching circuit 3b, the connection relationship between the diode 10 and the insulated gate bipolar transistor 11 is the same as that of the first switching circuit 3a, and the emitter of the insulated gate bipolar transistor 11 is the second. The difference is that it is connected to one end of the coil 5. A control signal V _p2 is applied to the gate of the insulated gate bipolar transistor 11 from the control unit 6 so as to conduct at a predetermined conduction angle θ _p2 every half cycle on the positive side of the power supply 2.

In the lower semiconductor switching element 9 of the second switching circuit 3 b, the connection relationship between the diode 10 and the insulated gate bipolar transistor 11 is the same as that of the first switching circuit 3 a, and the anode of the diode 10 is the second coil 5. The difference is that it is connected to one end. A control signal V _n2 is applied to the gate of the insulated gate bipolar transistor 11 from the control unit 6 so as to conduct at a predetermined conduction angle θ _n2 every half cycle on the negative side of the power supply 2.

FIG. 2 is a time chart for explaining an example of the operation of the power supply device 1, where (A) is the voltage of the power supply 2, (B) is V _p1 , (C) is V _n1 , and (D) is V _p2 and (E) are V _n2 , (F) is the voltage of the first coil 4, and (G) is the waveform of the voltage of the second coil 5. As shown in FIG. 2, in the positive half cycle of the power supply 2 (see FIG. 2A), the control unit 6 outputs a control signal V _p1 and turns on the upper semiconductor switching element 8 of the first switching circuit 3a. Conduction is performed for a predetermined conduction angle θ _p1 (see FIG. 2B). In the negative half cycle of the power supply 2, the control unit 6 conducts the lower semiconductor switching element 9 of the first switching circuit 3a for a predetermined conduction angle θ _n1 (see FIG. 2C).

As shown in FIG. _2F , the positive voltage of the power supply 2 is applied to the first coil 4 in accordance with the conduction angle θ _p1 in the positive half cycle of the power supply 2, and the negative half of the power supply 2 is applied. In the period, the negative voltage of the power source 2 is applied according to the conduction angle θ _n1 . Thereby, the electric power from the power supply 2 is supplied to the 1st coil 4 via the 1st switching circuit 3a. When an object to be heated (not shown) is arranged in the first coil 4, the object to be heated is induction-heated.

Similarly, in the second coil 5, in the positive half cycle of the power supply 2 (see FIG. 2A), the control unit 6 outputs the control signal _Vp2, and the upper semiconductor of the second switching circuit 3b. The switching element 8 is turned on for a predetermined conduction angle θ _p2 (see FIG. 2D). Then, in the negative half cycle of the power supply 2, the control unit 6 conducts the lower semiconductor switching element 9 of the second switching circuit 3b for a predetermined conduction angle θ _n2 (see FIG. 2E).
Therefore, as shown in FIG. 2 (G), the positive voltage of the power source 2 is applied to the second coil 5 in accordance with the conduction angle θ _p2 in the positive half cycle of the power source 2, In the half cycle, a negative voltage of the power source 2 is applied according to the conduction angle θ _n1 . Thereby, the electric power from the power supply 2 is supplied to the 2nd coil 5 via the 2nd switching circuit 3b. When an object to be heated (not shown) is arranged in the second coil 5, the object to be heated is induction-heated.

According to the power supply device 1, the power generated from the single power source 2 can be supplied to the first and second coils 4 and 5 via the switching unit 3. At this time, the conduction of the gate signal applied to the gates of the insulated gate bipolar transistors 11 of the first and second first switching circuits 3a and 3b comprising a pair of semiconductor switching elements 8 and 9 connected in antiparallel. The power applied to the first coil 4 and the second coil 5 can be adjusted by controlling the angles θ _p1, θ _n1 , θ _p2, θ _n2 . The switching unit 3 of the power supply device 1 according to the present invention is inserted between the power source 2 and the coils 4 and 5 serving as loads, and can be applied to a high-frequency induction heating device and a melting furnace device. The load of the power source 2 is not limited to the coils 4 and 5 and can be applied to various loads.

(Modification 1 of the power supply apparatus 1)
The switching unit 3 of the power supply device 1 according to the present invention is inserted between the power source 2 and the coils 4 and 5 serving as loads, and can be applied to a high-frequency induction heating device and a melting furnace device. The load of the power source 2 is not limited to the coils 4 and 5 and can be applied to various loads. As an example, a modified example of the power supply device 1 in which the load of the power source 2 is n coils will be described.
FIG. 3 is a circuit diagram showing a configuration of a modified example 1a of the power supply apparatus of the present invention. As shown in FIG. 3, the power supply device 1 a includes a power source 2 and a switching unit 3 connected to the power source 2. N coils 14 (14 _{1 to} 14 _n ) are connected to the switching unit 3. That is, the power supply device 1a is configured to supply power to the coils 14 _{1 to} 14 _{n serving} as loads by the switching unit 3.

Switching unit 3 drives the first switching circuit 3a for driving the first coil 14 _1, a second second switching circuit 3b for driving the coil 14 _2, ..., the coil 14 _n of the n The n-th switching circuit 3n and the control unit 6 are included.

  Each of the first to n-th switching circuits 3a to 3n is composed of a pair of semiconductor switching elements 8 and 9 connected in reverse parallel. That is, n pairs of semiconductor switching elements 8 and 9 are used in the first to nth switching circuits 3a to 3n. The upper semiconductor switching element 8 of the first to n-th switching circuits 3 a to 3 n controls the conduction of the positive half of the power supply 2 in the half cycle. On the other hand, the lower semiconductor switching element 9 of the first to n-th switching circuits 3 a to 3 n controls half-cycle conduction on the negative side of the power supply 2.

In the control unit 6, in the half cycle on the positive side of the power supply 2, the upper semiconductor switching elements 8 of the first to n-th switching circuits 3 a to 3 n are conducted at predetermined conduction angles θ _p1, θ _{p2, and} θ _pn . Thus, the control signals V _p1, V _p2, ... _, V _pn are output to the upper semiconductor switching element 8.

In the negative half cycle of the power supply 2, the control unit 6 conducts the lower semiconductor switching elements 9 of the first to n-th switching circuits 3 a to 3 n at predetermined conduction angles θ _n1, θ _{n2, and} θ _nn . Thus, the control signals V _n1, V _n2, ... _, V _nn are output to the lower semiconductor switching element 9.

In a variation 1a of the power supply device of the present invention, the first to nth switching circuits 3a to 3n are connected in series to the corresponding first to nth coils 14 _{1 to} 14 _n , respectively. Semiconductor switching element 8, the control signal _{V p1,} V p2 sent from the control unit 6, a predetermined conduction angle theta _p1 by _{~V pn,} theta _p2, conductive for through? _Pn, the semiconductor switching element 9, the control unit control signal _{V n1,} V n2 sent from 6, a predetermined conduction angle theta _n1 by _{~V nn,} theta _n2, conduct in through? _nn. Thereby, the electric power supplied from the power supply 2 is distributed to the _first to nth coils 14 _{1 to} 14 _n .

(Modification 2 of the power supply device 1)
A modification of the power supply device 1 having two frequencies with different frequencies of the power source 2 will be described.
FIG. 4 is a circuit diagram showing a configuration of another modification 1b of the power supply apparatus of the present invention. The power supply device 1b shown in FIG. 4 is different from the power supply device 1 shown in FIG. 1 in that the single-frequency power source 2 of the power supply device 1 shown in FIG. 1 outputs the first frequency and the second frequency. It is the point made into the structure replaced with the 2 frequency power supply 20 to do. The dual frequency power supply 20 includes a low frequency power supply 21 that outputs a first frequency, a high frequency power supply 22 that outputs a second frequency, an inductance 23, a capacitor 24, and the like. The dual frequency power source 20 is a power source in which a low frequency power source 21 and a high frequency power source 22 are superimposed. Each output of the low frequency power source 21 and the high frequency power source 22 is controlled by the energization control unit 25. One end of the low frequency power source 21 is connected to one end of the switching unit 3 via an inductance 23, and one end of the high frequency power source 22 is connected to one end of the switching unit 3 via a capacitor 24. The other end of the low frequency power supply 21 and the other end of the high frequency power supply 22 are connected to the other ends of the first and second coils 4 and 5. The other configuration is the same as that of the power supply device 1 shown in FIG.

  The first frequency of the low-frequency power source 21 is, for example, a frequency of about 1 kHz from a commercial AC frequency of 50 to 60 Hz. The second frequency of the high frequency power supply 22 is a frequency of about 1 kHz to 400 kHz, for example.

  According to the power supply device 1b, the first and second coils 4 and 5 can be induction-heated by one two-frequency power source 20, and low-frequency power and high-frequency power are further supplied from the two-frequency power source 20. Since it is output, the inside of the object to be heated can be induction heated by the low frequency power source 21, and the surface of the object to be heated can be induction heated by the high frequency power source 22.

  As described above, according to the power supply device 1 of the present invention, the switching unit 3 includes the first and second coils 4 and 5 in which the pair of the diode 10 and the insulated gate bipolar transistor 11 connected in reverse parallel is connected. Circuit configuration connected in series. Power supplied from a single power source 2 is supplied to the first and second coils 4 and 5 by a gate signal applied to each gate electrode of the insulated gate bipolar transistor 11 connected in reverse parallel.

  As a result, according to the power supply device 1 of the present invention, the power supplied from the single power source 2 is not mechanically switched, but the semiconductor switching element formed by connecting the diode 10 and the insulated gate bipolar transistor 11 in series is reversed. A pair of semiconductor switching elements 8 and 9 connected in parallel can be used. For this reason, size reduction of the switching part 3 can be achieved. The switching unit 3 eliminates the need for wear parts and the like necessary for a switching circuit using a mechanical switch, and as a result, does not require maintenance, that is, is maintenance-free.

  Since the switching unit 3 of the power supply device 1 of the present invention uses the insulated gate bipolar transistor 11 as a switching element, it can be operated at a frequency up to 100 kHz. That is, the switching unit 3 operates at high speed. This is 10 times faster than 10 kHz which is the operating frequency of the switching circuit using the conventional thyristor.

(Application example 1 of the power supply device 1)
FIG. 5 is a circuit diagram showing an example in which the load of the power supply device 1 is a welding electrode. The power supply device 1 shown in FIG. 5 shows a case where the load coils 4 and 5 shown in FIG. 1 are used as the first and second welding electrodes 15 and 16. The first switching circuit 3 a is connected in series to the first welding electrode 15, and the second switching circuit 3 b is connected in series to the second welding electrode 16. Accordingly, the power of the power source 2 is supplied to the first welding electrode 15 and the second welding electrode 16 by the switching unit 3. Accordingly, resistance welding of the workpiece sandwiched between the first welding electrodes 15 can be performed, and resistance welding of the workpiece sandwiched between the second welding electrodes 16 can be performed.

(Application example of power supply device 1b)
FIG. 6 is a circuit diagram showing an example in which the load of the power supply device 1b is a welding electrode. The power supply device 1 shown in FIG. 6 shows a case where the coils 4 and 5 of the load shown in FIG. 4 are replaced with first and second welding electrodes 15 and 16. The first switching circuit 3 a is connected in series to the first welding electrode 15, and the second switching circuit 3 b is connected in series to the second welding electrode 16. Accordingly, the power of the power source 2 is supplied to the first welding electrode 15 and the second welding electrode 16 by the switching unit 3. This allows resistance welding of the workpiece sandwiched between the first welding electrodes 15 and resistance welding of the workpiece sandwiched between the second welding electrodes 16. Since the frequency power and the high frequency power are output, the surface of the welded portion of the workpiece can be induction heated with the high frequency power.

(Second Embodiment)
Next, a power supply apparatus according to the second embodiment of the present invention will be described.
FIG. 7 is a circuit diagram showing a configuration of a power supply device 30 according to the second embodiment of the present invention. The power supply device 30 shown in FIG. 7 is different from the power supply device 1 shown in FIG. 1 in that the above-described antiparallel connection is made between the other ends of the coils 4 and 5 and the other end of the AC power supply 2. The switching circuits 3a2 and 3b2 including pairs of semiconductor switching elements 8 and 9 are further connected.
Specifically, the first switching circuit 3 a connected to the coil 4 includes a first switching circuit 3 a 1 connected between one end of the power source 2 made of alternating current and one end of the coil 4, and the other of the coil 4. And a first switching circuit 3a2 connected between the one end and the other end of the AC power supply 2.
On the other hand, the second switching circuit 3b connected to the coil 5 is connected to the second switching circuit 3b1 connected between one end of the power source 2 and one end of the coil 5, and the other end of the coil 5 is connected to the AC. And a second switching circuit 3b2 connected between the other end of the power source 2.

  The first and second switching circuits 3a2 and 3b2 further added to the power supply device 1 shown in FIG. 1 have the same configuration as the first switching circuit 3a shown in FIG. It consists of a pair of switching elements 8 and 9.

As shown in FIG. 7, the semiconductor switching element 8 on the upper side of the first switching circuits 3a1 and 3a2 is connected so that the power supply 2 is conducted in a positive cycle. In the upper semiconductor switching element 8 of the first switching circuit 3a1 and 3a2, the control signal _{V p1} from the controller 6 to the gate of the transistor 11 is applied. Thus, the upper semiconductor switching element 8 of the first switching circuit 3a1,3a2, the power supply 2 is electrically connected to the positive cycle at a predetermined conduction angle theta _p1.

On the other hand, the lower semiconductor switching elements 9 of the first switching circuits 3a1 and 3a2 are connected so that the power supply 2 is conducted in a negative cycle. In the semiconductor switching element 9 on the lower side of the first switching circuits 3a1 and 3a2, a control signal V _n1 is applied from the control unit 6 to the gate of the transistor 11. As a result, the semiconductor switching element 9 below the first switching circuits 3a1 and 3a2 conducts the power supply 2 at a predetermined conduction angle θ _n1 in a negative cycle.

The second switching circuit 3b operates in the same manner as the first switching circuit 3a. That is, in the semiconductor switching element 8 on the upper side of the second switching circuits 3b1 and 3b2, the control signal V _p2 is applied from the control unit 6 to the gate of the transistor 11. Thereby, the semiconductor switching element 8 on the upper side of the second switching circuits 3b1 and 3b2 conducts the power supply 2 at a predetermined conduction angle _θp2 in a positive cycle.

On the other hand, the control signal V _n1 is applied from the control unit 6 to the gate of the transistor 11 in the semiconductor switching element 9 on the lower side of the second switching circuits 3b1 and 3b2. Thereby, the semiconductor switching element 9 on the lower side of the second switching circuits 3b1 and 3b2 conducts the power supply 2 at a predetermined conduction angle θ _n1 in a negative cycle.

The control device 6 used in the power supply device 30 of the present invention may have the same configuration as the control device 6 of the power supply device 1. Thus, the power supply device 30, by _{V p1, V n1, V p2} , V n2 indicated in the time chart of FIG. _2, power applied to the first coil 4 to the second coil 5 is controlled. Therefore, the power supply device 30 controls the power of the power source 2 to control V _p1 , V _n1 , V _p2 , V _n2 , that is, to control the predetermined conduction angles θ _p1 , θ _n1 , θ _p2 , θ _n2 , The power applied to the first coil 4 and the second coil 5 can be controlled.

According to the power supply device 30 of the present invention, the first and second switching circuits 3 a 2 and 3 b 2 are further connected between the other ends of the coils 4 and 5 and the power supply 2. For this reason, there is an advantage that both ends of the coils 4 and 5 serving as loads can be electrically insulated except when they are connected to the power source 2.
Furthermore, according to the power supply device 30 of the present invention, four pairs of semiconductor switching elements 8 and 9 connected in reverse parallel are required. That is, in the power supply device 1, two pairs of semiconductor switching elements 8 and 9 connected in anti-parallel are required, but two pairs are required. Further, according to the power supply device 30, in the first switching circuit 3 a, the pair 3 a 1 of the semiconductor switching elements 8 and 9 connected to one end of the coil 4 and the semiconductor switching element 8 connected to the other end of the coil 4. , 9 pair 3a2 is connected in series to the power source 2, so that the breakdown voltage of the transistor 11 is about ½ that of the transistor 11 used in the power supply device 1 of the present invention. The advantage that you can do it.

  The configuration of the power supply device 30 of the present invention can be applied not only to the power supply device 1 but also to the power supply devices 1a and 1b.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. Absent. In the embodiment described above, the configuration of the switching unit 3, the power source 2, the frequency of the power source 2, the loads such as the coils 4 and 5 and the like can be appropriately designed according to the purpose.

1, 1a, 1b, 30: Power supply device 2: Power supply 3: Switching unit 3a, 3a1, 3a2: First switching circuit 3b, 3b1, 3b2: Second switching circuit 4: First coil 5: Second Coil 6: control unit 8, 9: semiconductor switching element 10: diode 11: three-terminal switching element 12: freewheeling diode 14: n coils (14 _{1 to} 14 _n )
15: First welding electrode 16: Second welding electrode 20: Dual frequency power source 21: Low frequency power source 22: High frequency power source 23: Inductance 24: Capacitor 25: Energization control unit

Claims (5)

One AC power source, and a switching unit connected between the AC power source and the first to nth loads of the AC power source,
The switching unit includes first to n-th switching circuits and a control unit,
Each of the first to n-th switching circuits is composed of a pair of semiconductor switching elements connected in antiparallel,
A pair of one ends of the semiconductor switching element are connected in series between one end of the AC power supply and one end of each load, and the other end of each load is connected to the other end of the AC power supply,
Each of the pair of semiconductor switching elements comprises a series connection of a diode and a transistor.   2. The electric power according to claim 1, wherein a switching circuit including a pair of anti-parallel connected semiconductor switching elements is further connected between the other end of each load and the other end of the AC power supply. Feeding device.   The power supply device according to claim 1, wherein the transistor is one of an insulated gate bipolar transistor, a MOSFET, and a bipolar transistor.   The power supply apparatus according to claim 1, wherein the load is a coil.   The power supply device according to claim 1, wherein the load is a welding electrode.

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