JP5506966B1 - Isolated DC / DC converter - Google Patents

Abstract

In an isolated DC / DC converter having a plurality of transformers, secondary side circuit elements can be protected from overvoltage by suppressing resonance of a secondary side voltage caused by a difference in excitation inductance of each transformer. An isolated DC / DC converter is obtained.
An inverter circuit (2), a plurality of transformers (3), a plurality of choke coils (5), and a plurality of rectifier circuits (4) are provided, and primary windings (31) of the plurality of transformers are mutually connected. A primary side circuit connected in series, a single choke coil, a plurality of rectifier circuits, and a secondary unit circuit including one secondary side winding (32) of a plurality of transformers are parallel to each other. It is an insulation type DC / DC converter comprised with the connected secondary side circuit, Comprising: The secondary side circuit connection part (8) which electrically connects several secondary side unit circuits mutually is further provided. .
[Selection] Figure 1

Description

  The present invention relates to an isolated DC / DC converter including a plurality of transformers, and in particular, a primary circuit in which primary windings of a plurality of transformers are connected in series, one choke coil, and one rectifier circuit. The present invention relates to an isolated DC / DC converter including a secondary side circuit in which a secondary unit circuit including a secondary winding of one of a plurality of transformers is connected in parallel to each other. .

  The isolated DC / DC converter has features of small size, low noise, and high insulation, and is widely used in industry. However, in an insulated DC / DC converter having a transformer, the transformer assumes most of the voltage conversion function, and therefore when the voltage ratio between the primary side voltage and the secondary side voltage is large, the primary side winding of the transformer And the turn ratio of the secondary winding becomes large.

  As a result, for example, if the primary side of the transformer is the high voltage side, the number of turns of the primary side winding is increased, which makes it difficult to configure the primary side winding.

  As a conventional technique for solving the above problems, a transformer is constituted by a plurality of transformers, and an insulated DC / DC converter is connected to a primary side in which primary windings of the plurality of transformers are connected in series to each other. A circuit and a secondary side circuit in which a secondary unit circuit including one secondary winding of one choke coil, a plurality of rectifier circuits, and a plurality of transformers are connected in parallel to each other By doing so, there is a method of suppressing the number of turns of each primary winding (see, for example, Patent Document 1).

  Further, the method of Patent Document 1 has an advantage that since the secondary unit circuit of the transformer is paralleled, the current of the secondary circuit is dispersed, and the copper loss and the power loss due to the choke coil are suppressed.

JP 2008-178205 A

However, the prior art has the following problems.
In an insulated DC / DC converter having a configuration in which a plurality of secondary unit circuits are connected in parallel to each other as shown in Patent Document 1, when there is a difference in the excitation inductance of each transformer, the excitation of each transformer A current resulting from the difference in inductance flows between the secondary unit circuits arranged in parallel.

  As a result, secondary side voltage resonance occurs due to the inductance of the choke coil and the capacitance on the circuit, and this resonance voltage is superimposed on the voltage during normal operation, thereby increasing the peak amplitude of the secondary side voltage. There was a problem of ending up. Furthermore, there is a problem that the secondary side circuit element such as the rectifying element is destroyed by the overvoltage.

  In order to solve this problem, for example, a rectifying element having a sufficient withstand voltage performance may be used. However, such a rectifying element has a cost problem that it is more expensive than a normal rectifying element.

  The present invention has been made to solve the above-described problems, and suppresses secondary-side voltage resonance caused by a difference in excitation inductance of each transformer, thereby protecting the secondary-side circuit element from overvoltage. It is an object of the present invention to obtain an insulated DC / DC converter that can be used.

  An insulated DC / DC converter according to the present invention includes an inverter circuit, a plurality of transformers, a plurality of choke coils, and a plurality of rectifier circuits, and primary windings of the plurality of transformers are connected to each other with respect to the output of the inverter circuit. It is configured to include a primary side circuit connected in series, one secondary winding of a plurality of transformers, one of a plurality of choke coils, and one of a plurality of rectifier circuits. Secondary side circuits formed by connecting the secondary side unit circuits in parallel with each other, and in each of the secondary side unit circuits, the choke coil has a first signal at the center tap of the secondary side winding. The rectifier circuit is an insulated DC / DC converter that is electrically connected to both ends of the secondary winding via the second signal line and the third signal line. A plurality of secondary unit circuits The secondary side circuit connection part for electrically connecting the respective first signal lines to each other, or for electrically connecting the respective second signal lines and the respective third signal lines to each other. Is further provided.

  According to the present invention, a primary side circuit in which primary windings of a plurality of transformers are connected in series to each other, one choke coil, one rectifier circuit, and one secondary side of the plurality of transformers. In an insulated DC / DC converter including a secondary side circuit in which secondary side unit circuits including windings are connected in parallel to each other, a plurality of secondary side unit circuits are electrically connected to each other. An insulation type DC / DC converter that further suppresses the resonance of the secondary side voltage caused by the difference in the excitation inductance of each transformer and can protect the secondary side circuit element from an overvoltage by further providing the secondary side circuit connection portion. Can be obtained.

It is an illustration figure of the circuit structure of the insulation type DC / DC converter in Embodiment 1 of this invention. It is a simulation waveform of the voltage of the both ends of a rectifier in case there is a difference in the magnetizing inductance of each transformer in Embodiment 1 of the present invention. It is an illustration figure of the circuit structure of the insulation type DC / DC converter in Embodiment 2 of this invention. It is an illustration figure of the secondary side circuit connection part in Embodiment 3 of this invention. It is a 1st illustration figure of the integral member in Embodiment 3 of this invention. It is a 2nd illustration figure of the integral member in Embodiment 3 of this invention. It is a 3rd illustration figure of the integral member in Embodiment 3 of this invention. It is an illustration figure of the secondary side circuit connection part in Embodiment 4 of this invention. It is a 1st illustration figure of the secondary side circuit connection part in Embodiment 5 of this invention. It is a 2nd illustration figure of the secondary side circuit connection part in Embodiment 5 of this invention. It is an illustration figure of the secondary side circuit connection part in Embodiment 6 of this invention.

  Hereinafter, preferred embodiments of an insulated DC / DC converter according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated about the part which is the same or it corresponds in each figure.

Embodiment 1 FIG.
FIG. 1 is an exemplary diagram of a circuit configuration of an insulated DC / DC converter according to Embodiment 1 of the present invention. The isolated DC / DC converter shown in FIG. 1 includes an input terminal 1, an inverter circuit 2, a plurality of transformers 3a and 3b, a plurality of rectifier circuits 4a and 4b, a plurality of choke coils 5a and 5b, a smoothing capacitor 6, and an output terminal 7. , And a secondary circuit connection unit 8.

  Here, the inverter circuit 2 includes a plurality of switching elements 21. The transformer 3a includes a primary side winding 31a and a secondary side winding 32a. Further, the secondary winding 32a includes a center tap 33a. The rectifier circuit 4a includes a plurality of rectifier elements 41. The same applies to other secondary unit circuits.

  Thus, in the isolated DC / DC converter according to the first embodiment, in the primary circuit, the plurality of primary windings 31a and 31b are connected in series to the output of the inverter circuit 2, and In the secondary circuit, the secondary unit circuit including the secondary winding 32a, the choke coil 5a, and the rectifier circuit 4a is replaced with another secondary unit circuit (for example, the secondary winding 32b, The secondary side unit circuit including the choke coil 5b and the rectifier circuit 4b is connected in parallel to each other.

  For the sake of simplicity, FIG. 1 shows an example in which the secondary side circuit is paralleled in two. However, in an isolated DC / DC converter in which the secondary side circuit is parallelized in three or more. Similar effects can be obtained.

  First, the function of each component of the insulated DC / DC converter and the flow of voltage signals will be described with reference to FIG. Since each secondary unit circuit has the same configuration and the same function, the description of the secondary circuit will be made only for the secondary unit circuit including the secondary winding 32a.

  A DC voltage before transformation is input to the input terminal 1. The inverter circuit 2 switches the switching element 21 to convert the DC voltage at the input terminal 1 into an AC voltage whose amplitude is inverted at a constant period, and outputs the AC voltage to the primary windings 31a and 31b of the transformers 3a and 3b. To do.

  The transformer 3a transforms the alternating voltage of the primary side winding 31a and outputs it to the secondary side winding 32a. At this time, the voltage ratio between the primary side voltage and the secondary side voltage is the turn ratio of the primary side winding 31a and the secondary side winding 32a.

  The rectifying circuit 4a rectifies the AC voltage transformed by the transformer 3a by using a plurality of rectifying elements 41. The choke coil 5a and the smoothing capacitor 6 smooth the AC voltage rectified by the rectifier circuit 4a and output the smoothed voltage to the output terminal 7.

  In this way, the isolated DC / DC converter includes a primary side circuit in which a plurality of primary windings 31a and 31b are connected in series and a secondary side in which a plurality of secondary unit circuits are connected in parallel to each other. By configuring with a circuit, the number of turns of each primary winding 31a, 31b can be suppressed. Further, the current in the secondary circuit is dispersed, and the copper loss and the power loss due to the choke coils 5a and 5b can be suppressed.

  Further, as shown in FIG. 1, the isolated DC / DC converter according to the first embodiment allows a plurality of secondary unit circuits to be connected to each other at the center taps 33a and 33b of the secondary windings 32a and 32b. A secondary circuit connecting portion 8 for electrical connection is provided.

  Specifically, the secondary side circuit connection portion 8 is a signal line (hereinafter referred to as the signal line) that connects the choke coils 5a, 5b and the center taps 33a, 33b of the secondary side windings 32a, 32b in each secondary unit circuit. The second unit circuits are electrically connected to each other by electrically connecting each other) (referred to as first signal lines).

  As described above, by providing the secondary side circuit connecting portion 8, the current caused by the difference in the excitation inductance of the transformers 3 a and 3 b as described in the above “problem to be solved by the invention” can be reduced. It is possible to cause the secondary circuit connection portion 8 to flow without going through 5a and 5b. As a result, it is possible to suppress the resonance voltage caused by the difference in excitation inductance between the transformers 3a and 3b.

  In addition, by providing the secondary circuit connection portion 8, even if any of the plurality of choke coils 5a and 5b loses its function due to disconnection or the like, the remaining choke coils 5a and 5b Since the function as an isolated DC / DC converter is maintained, fault tolerance is improved.

  FIG. 2 is a simulation waveform of the voltage across the rectifying element 41 when there is a difference in the excitation inductance of the transformers 3a and 3b in the first embodiment of the present invention. In FIG. 2, a waveform V <b> 1 indicates a simulation waveform of the voltage across the rectifying element 41 when the secondary circuit connection unit 8 is not provided. On the other hand, the waveform V2 shows a simulation waveform of the voltage across the rectifying element 41 when the secondary circuit connection unit 8 is provided.

  When the secondary circuit connection portion 8 is not provided, as shown by the waveform V1 in FIG. 2, the resonance voltage caused by the difference in the excitation inductances of the transformers 3a and 3b at both ends of the rectifying element 41 is normal operation. It can be seen that the peak amplitude is increased by being superimposed on the voltage of.

  On the other hand, when the secondary circuit connection portion 8 is provided, it can be seen that the resonance voltage caused by the difference in the excitation inductances of the transformers 3a and 3b is suppressed as indicated by the waveform V2 in FIG.

  As described above, the first embodiment includes the secondary side circuit connecting portion that electrically connects the first signal lines of the plurality of secondary side unit circuits to each other. As a result, it is possible to obtain an insulation type DC / DC converter that can suppress the resonance of the secondary side voltage caused by the difference in the excitation inductance of each transformer and protect the secondary side circuit element from the overvoltage.

  In FIG. 1, the inverter circuit 2 is an example of a full bridge type configured by four switching elements 21, but the inverter circuit 2 is not limited to the full bridge type. Further, the number of switching elements 21 of the inverter circuit 2 is not limited to four. The inverter circuit 2 may be anything as long as it can convert a DC voltage into an AC voltage. For example, the same effect can be obtained even if a half bridge type is used as the inverter circuit 2.

  In FIG. 1, the example in which the rectifier circuits 4a and 4b are configured by two power MOSFETs is shown, but the rectifier element 41 is not limited to the power MOSFET. Further, the number of rectifying elements 41 in the rectifying circuits 4a and 4b is not limited to two. For example, the same effect can be obtained by using a diode or the like as the rectifying element 41.

Embodiment 2. FIG.
In the second embodiment, a plurality of secondary unit circuits can be electrically connected to each other to suppress secondary voltage resonance caused by differences in excitation inductance between the transformers 3a and 3b. A different form of the DC / DC converter from the first embodiment will be introduced.

  FIG. 3 is an exemplary diagram of a circuit configuration of an insulation type DC / DC converter according to Embodiment 2 of the present invention. The insulated DC / DC converter shown in FIG. 3 includes a secondary circuit connection unit 8 (1) and a secondary circuit connection unit 8 (2) instead of the secondary circuit connection unit 8 in FIG. I have.

  Specifically, the secondary circuit connection unit 8 (1) connects the first end points of the plurality of rectifier circuits 4a and 4b and the first end points of the plurality of secondary windings 32a and 32b. A plurality of secondary unit circuits are electrically connected to each other by electrically connecting signal lines (hereinafter referred to as second signal lines) to each other.

  Further, the secondary side circuit connection portion 8 (2) is a signal line (second line) connecting the second end points of the plurality of rectifier circuits 4a and 4b and the second end points of the plurality of secondary side windings 32a and 32b. Hereinafter, the plurality of secondary unit circuits are electrically connected to each other by electrically connecting each other).

  As described above, in the second embodiment, a plurality of secondary unit circuits are connected to each other at the end points of the secondary windings 32a and 32b instead of the center taps 33a and 33b of the secondary windings 32a and 32b. Are electrically connected to each other. Even with such connection, the same effect as in the first embodiment can be obtained.

  As described above, in the second embodiment, the second signal lines of the plurality of secondary unit circuits are electrically connected to each other and the third signal lines of the plurality of secondary unit circuits are connected to each other. Are provided with secondary circuit connection portions that are electrically connected to each other. As a result, it is possible to obtain an insulation type DC / DC converter that can suppress the resonance of the secondary side voltage caused by the difference in the excitation inductance of each transformer and protect the secondary side circuit element from the overvoltage.

  Also in FIG. 3, as in FIG. 1 in the first embodiment, the number of parallelization of the secondary side circuit is not limited to two. Moreover, the inverter circuit 2 is not limited to a full bridge type, and the number of the switching elements 21 of the inverter circuit 2 is not limited to four. The rectifying elements 41 are not limited to power MOSFETs, and the number of rectifying elements 41 in the rectifying circuits 4a and 4b is not limited to two.

Embodiment 3 FIG.
In the third embodiment, a plurality of specific examples of the secondary circuit connection unit 8 in the first embodiment will be introduced with reference to FIGS.

  FIG. 4 is an exemplary diagram of the secondary circuit connection unit 8 according to Embodiment 3 of the present invention. The transformer 3a shown in FIG. 4 includes a primary side winding 31a, a secondary side winding 32a, and a transformer core 34a which are not shown. Further, the secondary winding 32a includes a center tap 33a. The choke coil 5a includes a choke coil winding 51a and a choke coil core 52a. The same applies to other secondary unit circuits.

  The secondary circuit connection unit 8 shown in FIG. 4 is configured by integrating a plurality of first signal lines 86a and 86b electrically and physically. As a result, the plurality of center taps 33 a and 33 b and the plurality of choke coil windings 51 a and 51 b are electrically and mechanically connected via the screws 84.

  As described above, the secondary side circuit connecting portion 8 is formed by integrating the plurality of first signal lines 86a and 86b electrically and physically, thereby reducing the number of parts and the member cost. A plurality of secondary unit circuits can be electrically connected to each other.

  FIG. 5 is a first exemplary view of the integral member 100 according to Embodiment 3 of the present invention. The integrated member 100 shown in FIG. 5 includes a secondary circuit connection unit 8 including a plurality of first signal lines 86a and 86b, a plurality of secondary windings 32a and 32b, a plurality of center taps 33a and 33b, In addition, the windings 51a and 51b of the plurality of choke coils are configured to be integrated electrically and physically.

  As shown in FIG. 5, in the secondary unit circuit including the secondary winding 32a, the secondary winding 32a and the choke coil 51a are electrically connected to each other by the first signal line 86a. It is connected. The same applies to other secondary unit circuits. Further, the plurality of secondary unit circuits are electrically connected to each other by the secondary circuit connection unit 8.

  Thus, together with the secondary circuit connection portion 8 and the first signal lines 86a and 86b, a plurality of choke coil windings 51a and 51b, a plurality of secondary windings 32a and 32b, and a plurality of center taps. By configuring 33a and 33b as an integral member 100 that is electrically and physically connected, the number of parts and the member cost can be further reduced.

  FIG. 6 is a second exemplary view of the integral member 100 according to Embodiment 3 of the present invention. The integrated member 100 shown in FIG. 6 includes a plurality of integrated members 100a and 100b.

  Here, in the secondary unit circuit including the secondary winding 32a, the integral member 100a includes the first signal line 86a, the secondary winding 32a, the center tap 33a, and the choke coil winding 51a. Are integrated electrically and physically. The same applies to other secondary unit circuits.

  Further, the plurality of integrated members 100a and 100b are electrically and mechanically connected to each other by being fixed by screws 88 so that the holes provided on the first signal lines 86a and 86b overlap. The

  At this time, at least one of the plurality of integrated members 100a and 100b has an extension portion 87 on the first signal lines 86a and 86b for easily overlapping the holes with the other integrated members 100a and 100b. Have.

  Thus, by constructing the integrated member 100 by mechanically connecting the members formed integrally with each secondary side unit circuit, it is excellent in assembling and reducing the part discarding cost. The member cost can be reduced.

  In FIG. 6, for the sake of simplicity, an example in which the integrated member 100 includes two integrated members 100 a and 100 b is shown, but the number of integrated members 100 a and 100 b is not limited to two. The same effect can be obtained when the integrated member 100 is composed of three or more integrated members 100a and 100b.

  6 shows an example in which the integrated member 100a has the extension portion 87 among the plurality of integrated members 100a and 100b, but the same effect can be obtained even when the other integrated member 100b has the extension portion 87. .

  FIG. 7 is a third exemplary view of the integral member 100 according to Embodiment 3 of the present invention. The secondary circuit connection portion 8 shown in FIG. 7 includes two integrated members 100a and 100b having the same shape.

  The integral member 100a and the integral member 100b have the same shape, and both have an extension 87. As shown in FIG. 7, one side is turned over so that it becomes the object of the other mirror surface, and is fixed with screws 88 so that the hole portion of one extension portion 87 overlaps the hole portion of the other extension portion 87. Thus, they are electrically and mechanically connected to each other.

  In this way, by configuring the integrated member 100 from the two integrated members 100a and 100b having the same shape, it is possible to further simplify the configuration with reduced member costs.

  As described above, according to the third embodiment, the number of parts and the member cost are reduced by forming the secondary circuit connection portion by electrically and physically integrating the plurality of first signal lines. With this simple configuration, a plurality of secondary unit circuits can be electrically connected to each other.

  In addition, together with each of the secondary circuit connection portion and the first signal line, the windings of the plurality of choke coils and the plurality of secondary windings are configured as an integral member that is electrically and physically connected. This further reduces the number of parts and the member cost.

  In addition, by constructing the integrated member by mechanically connecting the members formed by integrating each unit circuit on the secondary side to each other, it is excellent in assemblability and reduces the part discarding cost. Can be reduced.

  Further, by configuring the integral member from two members having the same shape, it is possible to further simplify the configuration with reduced member costs.

  Although FIGS. 4, 5 and 6 show examples in which the winding directions of the choke coil windings 51a and 51b are opposite to each other, they may be the same. In particular, in FIG. 4, when the winding direction is the same direction, a step is generated between the windings 51 a and 51 b of the choke coil. This step is just the step at the secondary side circuit connection portion 8. This problem can be solved by providing the opposite step to cancel

  4, 5, and 6, for the sake of simplicity, an example in which the secondary side circuit is paralleled to two is shown, but an insulation type in which the secondary side circuit is paralleled to three or more is shown. The same effect can be obtained in the DC / DC converter.

Embodiment 4 FIG.
FIG. 8 is an exemplary diagram of the secondary circuit connection unit 8 according to the fourth embodiment of the present invention. The secondary circuit connection unit 8 shown in FIG. 8 is in contact with a heat sink (not shown) through an insulator (not shown) at the heat sink contact part 89 of the secondary circuit connection unit 8.

  As described in the first embodiment, as shown in FIG. 8, the isolated DC / DC having a configuration in which the secondary windings 32a and 32b of the plurality of secondary unit circuits are electrically connected to each other. In the DC converter, even if one of the plurality of choke coils 5a and 5b loses its function due to disconnection or the like, the remaining choke coils 5a and 5b can be used as an isolated DC / DC converter as a whole. Function is maintained.

  However, if any one of the choke coils 5a and 5b is disconnected, for example, if there are two secondary unit circuits and the choke coil 5a is disconnected, the remaining choke coil 5b has a normal state. When a current twice as much flows, the copper loss due to the choke coil 5b becomes four times the square of the current.

  As a result, there is a problem that the remaining choke coil winding 51b may generate heat and burn out.

  Therefore, in the insulated DC / DC converter according to the fourth embodiment, the secondary side circuit connection portion 8 is brought into contact with the heat sink via an insulator, thereby suppressing the temperature rise of the choke coils 5a and 5b and heating. The tolerance is increased, and operation in a larger current value region is possible.

  As described above, in the fourth embodiment, the secondary circuit connection portion is brought into contact with the heat sink through the insulator, thereby suppressing the temperature rise of the choke coil and increasing the heat resistance, thereby increasing the current value region. Is possible. As a result, even if any one of the plurality of choke coils loses its function, the remaining choke coil can maintain the function as an isolated DC / DC converter.

  8 shows an example in which the heat sink contact portion 89 is provided in the insulation type DC / DC converter shown in FIG. 4, the target for providing the heat sink contact portion 89 is that a plurality of secondary unit circuits are electrically connected to each other. Any device may be used as long as it is connected.

  For example, it can also be provided in the insulation type DC / DC converter shown in FIGS. 1, 3 to 7, and FIGS. 9 to 11 described later. Moreover, the member which connects secondary side unit circuits which do not have the function to connect center tap 33a, 33b and choke coil 5a, 5b may be sufficient.

  FIG. 8 shows an example in which the heat sink contact portion 89 is provided on the first signal lines 86 a and 86 b, but the heat sink contact portion 89 may be provided anywhere on the secondary side circuit connection portion 8.

Embodiment 5 FIG.
FIG. 9 is a first exemplary diagram of the secondary circuit connection unit 8 according to the fifth embodiment of the present invention. The secondary circuit connection portion 8 shown in FIG. 9 has a pattern on the printed circuit board 35.

  The secondary circuit connection portion 8 which is a pattern on the printed circuit board 35 shown in FIG. 9 has a plurality of secondary windings 32a and 32b connected to each other at the center taps 33a and 33b of the secondary windings 32a and 32b. Are electrically connected to each other.

  FIG. 10 is a second example of the secondary circuit connection unit 8 according to the fifth embodiment of the present invention. The secondary side circuit connection portion 8 (1) and the secondary side circuit connection portion 8 (2) shown in FIG. 10 have a pattern on the printed circuit board 35.

  The secondary circuit connection portion 8 (1) and the secondary circuit connection portion 8 (2), which are patterns on the printed circuit board 35 shown in FIG. 10, are provided at the end points of the secondary windings 32a and 32b. Secondary windings 32a and 32b are electrically connected to each other.

  As described above, according to the fifth embodiment, by providing the secondary circuit connection portion as a pattern on the printed circuit board, it is possible to obtain a secondary side circuit connection portion that further reduces the number of components and the member cost. Can do.

  9 and 10 show an example in which two secondary circuits are arranged in parallel for the sake of simplicity, but an isolated DC / DC in which three or more secondary circuits are arranged in parallel is shown. The same effect can be obtained in the converter.

Embodiment 6 FIG.
FIG. 11 is an exemplary diagram of the secondary circuit connection unit 8 according to the sixth embodiment of the present invention. The secondary circuit connection unit 8 illustrated in FIG. 11 further includes an abnormality detection unit 9.

  Here, the abnormality detection unit 9 includes a temperature sensor 91, a printed circuit board 92, and an output terminal connection unit 93.

  As described in the fourth embodiment above, the isolated DC / DC having a configuration in which the secondary windings 32a and 32b of the plurality of secondary unit circuits are electrically connected to each other as shown in FIG. In the DC converter, when any function of the plurality of choke coils 5a and 5b is lost, the remaining choke coils 5a and 5b may be excessively heated and burnt.

  Therefore, in the insulated DC / DC converter according to the sixth embodiment, the abnormality detection unit 9 includes the temperature sensor 91. The temperature sensor 91 is installed on the printed circuit board 92 and detects an abnormality of the choke coils 5a and 5b by measuring a temperature change of the output terminal connection portion 93 that follows the temperature of the windings 51a and 51b of the choke coil. be able to.

  Here, the output terminal connection portion 93 is originally for electrically and mechanically connecting the windings 51a and 51b of the choke coil and the output terminal 7 (not shown). 6 is further connected to the printed circuit board 92 through screws 94 in a thermal and mechanical manner.

  In this way, by measuring the temperature change of the output terminal connection portion 93 following the temperature of the windings 51a and 51b of the choke coil using the temperature sensor 91, the abnormality of the choke coils 5a and 5b can be detected. it can.

  Further, by using the output terminal connecting portion 93 which is an existing member as a member for connecting the windings 51a and 51b of the choke coil and the printed circuit board 92 thermally and mechanically, the number of parts and the member cost can be suppressed. Yes.

  As described above, according to the sixth embodiment, the temperature sensor is provided on the printed circuit board, and the temperature of the output terminal connection portion that connects the winding of the choke coil and the output terminal is measured using the temperature sensor. Thus, the abnormality of the choke coil can be detected.

  FIG. 11 shows an example in which the abnormality detection unit 9 is applied to the isolated DC / DC converter shown in FIG. 4. However, the target to which the abnormality detection unit 9 is applied is that a plurality of secondary unit circuits are mutually connected. Any device that is electrically connected may be used. For example, the present invention can be applied to the isolated DC / DC converter shown in FIGS. 1 and 3 to 10.

  DESCRIPTION OF SYMBOLS 1 Input terminal, 2 Inverter circuit, 3a, 3b Transformer, 4a, 4b Rectifier circuit, 5a, 5b Choke coil, 6 Smoothing capacitor, 7 Output terminal, 8 Secondary side circuit connection part, 8a, 8b Secondary side circuit connection part , 9 Abnormality detection part, 21 Switching element, 31a, 31b Primary side winding, 32a, 32b Secondary side winding, 33a, 33b Center tap, 34a, 34b Transformer core, 35 Printed circuit board, 41 Rectifier element, 51a 51b Choke coil winding, 52a, 52b Choke coil core, 84 screw, 86a, 86b First signal line, 87 extension, 88 screw, 89 heat sink contact, 91 temperature sensor, 92 printed circuit board, 93 output Terminal connection part, 94 screw, 100 integral member, 100a, 100b integral member.

Claims (7)

A primary side circuit comprising an inverter circuit, a plurality of transformers, a plurality of choke coils, and a plurality of rectifier circuits, wherein primary side windings of the plurality of transformers are connected in series to the output of the inverter circuit; A secondary unit circuit including one secondary winding of the plurality of transformers, one of the plurality of choke coils, and one of the plurality of rectifier circuits. It is composed of secondary circuits connected in parallel to each other,
In each of the secondary unit circuits,
The choke coil is electrically connected to a center tap of the secondary winding via a first signal line,
The rectifier circuit is an isolated DC / DC converter electrically connected to both ends of the secondary winding via a second signal line and a third signal line,
The plurality of secondary-side unit circuits are configured to electrically connect the first signal lines to each other, or to electrically connect the second signal lines to each other and the third signal lines to each other. An insulation type DC / DC converter further comprising a secondary side circuit connection portion connected to the. The insulated DC / DC converter according to claim 1,
The secondary circuit connection part is configured to electrically connect the first signal lines to each other,
Each of the secondary circuit connection portion and the first signal line is formed electrically and physically as an integrated DC / DC converter. The insulated DC / DC converter according to claim 2,
An integral member in which the windings of the plurality of choke coils and the plurality of secondary windings are electrically and physically connected together with each of the secondary circuit connection portion and the first signal line. An isolated DC / DC converter. The insulated DC / DC converter according to claim 3,
The said integral member is comprised by mutually connecting the member formed integrally for every said secondary side unit circuit mutually, The insulation type DC / DC converter. In the insulated DC / DC converter according to any one of claims 1 to 4,
The secondary side circuit connection portion is in contact with a heat sink via an insulating member. Insulated DC / DC converter. The insulated DC / DC converter according to claim 1 or 2,
The secondary side circuit connection portion is a pattern on a printed circuit board. An insulated DC / DC converter. The insulated DC / DC converter according to any one of claims 1 to 6,
An insulated DC / DC converter, further comprising a temperature sensor that detects an abnormality of the choke coil by measuring a temperature of the winding of the choke coil.

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