JP2010213480A - Power converter of fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the performance and reliability of a power converter for a fuel cell by reducing common mode noises. <P>SOLUTION: This power converter includes at least: a fuel cell 20; a converter 22, which converts DC electric power output from the fuel cell 20; a transformer 23, which transfers the electric power converted at the converter 22 to an inverter 25 connected to a commercial system 26; and a conductor 27 provided between the primary winding of the transformer 23 connected to the converter 22 and the secondary winding of the transformer 23 connected to the inverter 25. The conductor 27 has a structure of being connected to either one of cathode side bus 28 connected to the cathode side output terminal and anode side bus 29 connected to the anode side output terminal of the fuel cell 20 connected to the converter 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a power conversion device that converts DC power of a fuel cell into AC power having a commercial frequency and supplies power to a household load, and particularly relates to a configuration that reduces high-frequency noise transmitted through a transformer.

  Conventionally, when converting direct current power of a fuel cell into alternating current power, the power conversion device first boosts the output voltage of the fuel cell to a direct current voltage exceeding the voltage of the commercial system by a converter and a transformer. Then, the boosted DC voltage is converted into an AC voltage by an inverter, and power is supplied to a domestic load connected to the commercial system.

  At this time, a switching element for performing power conversion is used for the converter and the inverter. One of the transformers is connected to the primary side of the converter, and the other is connected to the secondary side of an inverter connected to the commercial system.

  Hereinafter, a conventional power conversion device disclosed in Patent Document 1 will be described with reference to the drawings. FIG. 11 is a circuit diagram of a conventional power converter, and FIG. 12 is a cross-sectional view showing a transformer configuration of the conventional power converter.

  In general, in the case of a power conversion device for a fuel cell, the fuel cell is defined as the primary side of the transformer and the commercial system is defined as the secondary side of the transformer. For this reason, FIG. 11 shows the circuit diagram described in Patent Document 1 with the left and right reversed.

  As shown in FIG. 11, the power conversion apparatus first converts the commercial system 1 into a DC voltage by a rectifying / smoothing unit 3 including a filter 2, a bridge diode (DB), and a smoothing capacitor (Cin). And it converts into a high frequency voltage with the half bridge circuit 4 comprised from switching element (Q1), (Q2).

  Thereafter, power is supplied to the load 8 through the transformer 6 and the secondary side rectifying / smoothing unit 7. At this time, the transformer winding has a configuration in which one end of the transformer winding is connected to the stable potential portion (shown as A) of the rectifying and smoothing unit 3 and the other end is unconnected as an additional winding.

  Here, as shown in FIG. 12, the additional winding 11 is provided between the primary winding 9 and the secondary winding 10 wound around the core 12. Thereby, the potential difference applied to the adjacent windings on the secondary side and the primary side can be reduced from 130V to 40V, for example.

As a result, common mode noise transmitted from the secondary side to the primary side can be reduced. That is, noise generated on the load side connected to the secondary winding of the transformer 6 can be reduced from being transmitted to the commercial system side connected to the primary winding 9 via the transformer 6. Is.
JP 2001-352755 A

  However, in the above conventional configuration, when the power conversion device is applied to a fuel cell, a converter for converting DC power generated in the fuel cell is connected to the secondary side of the transformer 6. Therefore, the noise level is higher than the common mode noise level of the conventional configuration in which the secondary side of the transformer 6 is composed of passive elements that only consume power. At this time, the high frequency noise generated in the converter is common mode noise via the stray capacitance between the primary winding 9 and the secondary winding 10 of the transformer 6 and is connected to the primary side of the transformer 6. 1 is transmitted.

  Therefore, a conventional configuration in which the common mode noise blocking means (additional winding) is connected to the primary side (commercial system side) of the transformer will be described with reference to FIG.

  FIG. 13 is a configuration diagram illustrating a path through which common mode noise is transmitted in a conventional power converter. As shown in FIG. 13, since common mode noise is transmitted from the secondary side of the transformer to the primary side via the first stray capacitance 13 and the second stray capacitance 14, the circuit loop becomes large. Therefore, there has been a problem that the common mode noise affects the circuit operation of the power converter itself and other electrical equipment connected to the commercial system.

  The present invention solves the above-described conventional problems, and an object thereof is to reduce common mode noise and improve the performance and reliability of a power conversion device for a fuel cell.

  In a fuel cell power conversion device, the fuel cell is mainly considered, and the circuit connected to the fuel cell is usually defined as the primary side of the transformer. Therefore, the primary and secondary definitions of the transformer of Patent Document 1 and the present invention are opposite.

  In order to solve the above conventional problems, a fuel cell power conversion device according to the present invention connects a fuel cell, a converter that converts DC power output from the fuel cell, and power converted by the converter to a commercial system. A transformer for transmitting power to the inverter, and a conductor provided between the primary winding of the transformer connected to the converter and the secondary winding of the transformer connected to the inverter, Has a configuration connected to either the + side bus connected to the + side output terminal of the fuel cell connected to the converter or the − side bus connected to the − side output terminal.

  Thereby, the high frequency noise which generate | occur | produces in the converter which performs the power conversion of a fuel cell can reduce the common mode noise transmitted to the commercial system side via the floating capacity of a transformer. Moreover, the performance and reliability of the power converter of the fuel cell can be improved by reducing the influence of the common mode noise on the fuel cell.

  The fuel cell power conversion device of the present invention can reduce common mode noise in which high-frequency noise generated in a converter that performs power conversion of a fuel cell is transmitted to the commercial system via the stray capacitance of the transformer. Moreover, the performance and reliability of the power converter of the fuel cell can be improved by reducing the influence of the common mode noise on the fuel cell.

  A first invention is connected to a fuel cell, a converter for converting DC power output from the fuel cell, a transformer for transmitting power converted by the converter to an inverter connected to a commercial system, and the converter. A conductor provided between the primary winding of the transformer and the secondary winding of the transformer connected to the inverter, and the conductor is connected to the + side output terminal of the fuel cell connected to the converter. It has the structure connected to any one of the connected + side bus | bath and the-side bus connected to the-side output terminal.

  Thereby, the high frequency noise which generate | occur | produces in the converter which performs the power conversion of a fuel cell can reduce the common mode noise transmitted to the commercial system side via the floating capacity of a transformer.

  According to a second invention, in the first invention, the conductor is composed of at least a first conductor and a second conductor, and the first conductor is connected to the + side bus connected to the + side output terminal of the fuel cell. The second conductor is connected to a negative bus connected to the negative output terminal of the fuel cell. As a result, even when the output voltage of the fuel cell and 0 volt are alternately applied to the primary winding of the transformer by switching of the converter, the common mode noise is effectively reduced, and the performance such as conversion efficiency and A fuel cell power conversion device with further improved reliability can be realized.

  According to a third invention, in the first or second invention, the converter has a smoothing capacitor connected in parallel between the + side output terminal and the − side output terminal of the fuel cell, and the conductor is a smoothing capacitor. Are connected to a negative output terminal and a negative bus.

  As a result, connection to the high-frequency high-current line due to switching of the converter can be avoided. As a result, the electric potential of the conductor can be further stabilized and common mode noise can be effectively reduced.

  A fourth invention is the same as any one of the first to third inventions, further comprising a capacitor, wherein the capacitor has one end connected to one of the positive side bus and the negative side bus. The other end of the capacitor is connected to the housing. Thereby, the common mode noise generated from the converter can flow from the stray capacitance generated in the conductor through the capacitor. As a result, the flow of common mode noise into the fuel cell can be reduced, and the performance and reliability of the power converter of the fuel cell can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the same reference numerals are given to the same configurations as those of the conventional examples or the embodiments described above, and detailed description thereof will be omitted. The present invention is not limited to the embodiments.

(Embodiment 1)
Hereinafter, the power converter in Embodiment 1 of this invention is demonstrated using FIGS. 1-3.

  FIG. 1 is a circuit diagram showing a circuit configuration of a power conversion device according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing a transformer configuration of the power conversion device according to Embodiment 1 of the present invention. FIG. 3 is an explanatory diagram for explaining a path through which common mode noise is transmitted in the power conversion device according to Embodiment 1 of the present invention.

  As shown in FIG. 1, the power conversion device for a fuel cell includes at least a fuel cell 20, a smoothing capacitor 21, a converter 22, a transformer 23, a rectifying / smoothing circuit 24, and an inverter 25. The inverter 25 is connected. A conductor 27 is provided between the primary winding and the secondary winding of the transformer 23, and one end of the conductor 27 is connected to, for example, the negative side bus 29 of the converter 22 at a point B shown in the drawing. It is connected. Note that the − side is the anode side of the fuel cell, and the + side corresponds to the cathode side of the fuel cell.

  At this time, the smoothing capacitor 21 and the converter 22 are connected to the + side output terminal and the − side output terminal of the fuel cell 20 via the + side bus 28 and the − side bus 29. At both ends of the smoothing capacitor 21, a converter 22 having a full bridge configuration is connected from the four switching elements Q1, Q2, Q3, and Q4. Furthermore, it is connected to both ends of the primary winding of transformer 23 at the midpoint of switching elements Q1 and Q3 of converter 22 and the midpoint of switching elements Q2 and Q4.

  The secondary winding of the transformer 23 is connected to a rectifying / smoothing circuit 24 including a bridge diode and a smoothing capacitor, and is connected to a domestic load (not shown) via an inverter 25 connected to the rectifying / smoothing circuit 24. Power is supplied. When the fuel cell 20 is not outputting power, power is supplied from the commercial system 26 to the household load.

  Hereinafter, the configuration of the transformer of the present embodiment will be described with reference to FIG. FIG. 2 shows a cross-sectional view of the right half of the transformer 23.

  As shown in FIG. 2, the transformer 23 has a primary winding and a secondary winding wound from the center 30a of the core 30, and a conductor 27 is provided between the primary winding and the secondary winding. . At this time, the conductor 27 is configured in a disk shape, for example, and is configured so as to prevent a loop in which a current flows in a disk shape by providing a notch such as a slit (not shown). This is because, when the loop is formed, the interlinkage magnetic flux decreases in order to cancel the inductances of the primary winding and the secondary winding. And the electric wire (not shown) is connected to the conductor 27, for example, it is connected to B point shown in FIG.

  Hereinafter, how the common mode noise flows in the power conversion device having the above configuration will be described with reference to FIG.

  As shown in FIG. 3, since the fuel cell 20 generally has a configuration in which flat electrodes are laminated, it is easy to form a stray capacitance between the fuel cell 20 and the housing 42 that houses the power conversion device. Then, the common mode noise is transmitted through the formed stray capacitance 40 and the fourth stray capacitance 41, for example, along the path indicated by the dashed arrow in the drawing. At this time, since the conductor 27 is connected to the primary side circuit of the transformer 23, transmission of common mode noise to the secondary side circuit of the transformer 23 can be avoided.

  According to the present embodiment, the power conversion device that reduces the transmission of common mode noise to the commercial system 26 side and suppresses the influence of the circuit operation of the power conversion device itself and other electrical equipment connected to the commercial system. Can be realized.

  In the present embodiment, the example in which one end of the conductor 27 is connected to the negative side bus of the converter 22 has been described. However, the present invention is not limited to this, and may be connected to the positive side bus of the converter 22. Is obtained.

  In this embodiment, the example in which one end of conductor 27 is connected at point B of the negative side bus of converter 22 is not limited to this. For example, one end of the conductor 27 may be connected to a negative side bus or a positive side bus that connects the fuel cell 20 and the smoothing capacitor 21.

(Embodiment 2)
Hereinafter, the power converter in Embodiment 2 of this invention is demonstrated using FIGS. 4-6.

  FIG. 4 is a circuit diagram showing a circuit configuration of the power conversion device according to Embodiment 2 of the present invention. FIG. 5 is a cross-sectional view showing a transformer configuration of the power conversion device according to Embodiment 2 of the present invention.

  That is, as shown in FIG. 4, the power converter according to the present embodiment is provided with the first conductor 57 and the second conductor 58 between the primary winding and the secondary winding of the transformer 53. This is different from the power conversion device of the first embodiment. At this time, the first conductor 57 is connected to the minus side bus 29 of the converter 22 at a point B shown in the drawing, and the second conductor 58 is a plus side bus of the converter 22 at the point C shown in the drawing. 28 is connected. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  Hereinafter, the configuration of the transformer of the present embodiment will be described with reference to FIG. FIG. 5 shows a cross-sectional view of the right half of the transformer 53.

  As shown in FIG. 5, the transformer 53 winds the primary winding and the secondary winding from the center 50 a of the core 50, and the first conductor 57 and the second winding are interposed between the primary winding and the secondary winding. Two conductors 58 are provided. 5 shows an example in which the first conductor 57 is provided on the primary winding side, the second conductor 58 is on the primary winding side, and the first conductor 57 is on the secondary winding side. May be provided.

  At this time, the first conductor 57 and the second conductor 58 are formed in a disk shape, for example, and are configured so as not to form a loop through which a current flows in a disk shape by providing a notch such as a slit (not shown). Is done. This is because, when the loop is formed, the interlinkage magnetic flux decreases in order to cancel the inductances of the primary winding and the secondary winding.

  As a result, the first conductor 57 and the second conductor 58 transmit the common mode noise transmitted through the stray capacitance formed between the housing for housing the power converter and the primary side circuit of the transformer 23. Therefore, transmission of common mode noise to the secondary side circuit of the transformer 23 can be avoided.

  According to the present embodiment, transmission of common mode noise to the commercial system side is reduced, and the power conversion that further suppresses the influence on the circuit operation of the power conversion device itself and other electrical equipment connected to the commercial system. A device can be realized.

  Hereinafter, another example of the transformer configuration of the power conversion device according to the present embodiment will be described with reference to the drawings.

  FIG. 6 is a cross-sectional view showing another example of the transformer configuration of the power conversion device according to Embodiment 2 of the present invention.

  As shown in FIG. 6, the first conductor 57 is provided adjacent to the winding end side of the primary winding of the transformer 53, and the second conductor 58 is adjacent to the winding start side of the primary winding of the transformer 53. It is the structure provided as it does.

  With this configuration, since the potential difference between the primary winding of the transformer 53 and the first conductor 57 and the second conductor 58 can be reduced, the effect of suppressing transmission of common mode noise can be further enhanced.

  In the present embodiment, the example in which the conductor is composed of the first conductor 57 and the second conductor 58 has been described. However, the present invention is not limited to this. For example, a plurality of conductors composed of two or more are provided between the primary winding and the secondary winding of the transformer 53, a part of the plurality of conductors is connected to the + side bus 28, and the remaining The conductor may be connected to the negative side bus 29. Thereby, transmission of common mode noise can be further suppressed.

  In this embodiment, the first conductor 57 is disposed on the primary winding side of the transformer 53 and the second conductor 58 is disposed on the secondary winding side. However, the reverse arrangement is also possible. Well, the same effect can be obtained.

(Embodiment 3)
Hereinafter, the power converter in Embodiment 3 of this invention is demonstrated using FIG. 7 and FIG.

  FIG. 7 is a circuit diagram showing a circuit configuration of the power conversion device according to Embodiment 3 of the present invention. FIG. 8 is an explanatory diagram for explaining a circuit operation of the power conversion device according to the third embodiment of the present invention.

  That is, as shown in FIG. 7, in the power conversion device of the present embodiment, the first conductor 57 is connected between the smoothing capacitor 21 connected in parallel to the converter 22 and the fuel cell 20. The connection point D is different from that of the second embodiment in that the second conductor 58 is connected at the connection point E of the negative side bus 29. Since other configurations are the same as those of the second embodiment, description thereof is omitted.

  That is, as shown in FIG. 8, the first conductor 57 and the second conductor 58 are connected to the high-frequency high-current line by switching of the converter 22 flowing between the primary wiring of the transformer 53, the converter 22 and the smoothing capacitor 21. It is the structure which does not connect.

  This avoids the connection of the first conductor 57 and the second conductor 58 to the high-frequency high-current line where the voltage fluctuation due to the high-frequency large current is large, and the first conductor 57 and the second conductor 57 are located at a position where the potential fluctuation is small and the potential is stable. Two conductors 58 can be connected. As a result, it is possible to effectively realize a power converter that further reduces common mode noise.

  In the present embodiment, the example in which the conductor is composed of the first conductor 57 and the second conductor 58 has been described. However, the present invention is not limited to this. For example, a plurality of conductors composed of two or more are provided between the primary winding and the secondary winding of the transformer, a part of the plurality of conductors is connected to the + side bus 28, and the remaining conductive A configuration in which the body is connected to the negative side bus bar 29 may be adopted. Thereby, transmission of common mode noise can be further suppressed. Similarly to the first embodiment, one conductor may be connected to at least one of the connection point D of the + side bus bar 28 and the connection point E of the − side bus line 29. Thereby, common mode noise can be effectively reduced with a simple configuration.

  In this embodiment, the first conductor 57 is disposed on the primary winding side of the transformer 53 and the second conductor 58 is disposed on the secondary winding side. However, the reverse arrangement is also possible. Well, the same effect can be obtained.

(Embodiment 4)
Hereinafter, the power converter in Embodiment 4 of this invention is demonstrated using FIG. 9 and FIG.

  FIG. 9 is a circuit diagram showing a circuit configuration of the power conversion device according to Embodiment 4 of the present invention.

  That is, as shown in FIG. 9, the first capacitor 70 connected to the same location as the connection point D of the minus side bus 29 to which the first conductor 57 is connected, and the + side to which the second conductor 58 is connected. And a second capacitor 71 connected to the same point as the connection point E of the bus 28. Further, one terminal of the first capacitor 70 and the second capacitor 71 that are not connected is connected to a metal casing (not shown) that houses the power conversion device, so that it is different from the third embodiment. Is different.

  That is, as shown in FIG. 9, one end of the first capacitor 70 is connected to the same location as the connection point D of the negative side bus 29 to which the first conductor 57 is connected, and the other end of the first capacitor 70 is connected to the power It is connected to a housing that houses the conversion device. Further, one end of the second capacitor 71 is connected to the same location as the connection point E of the + side bus 28 to which the second conductor 58 is connected, and the other end of the second capacitor 71 is connected to the housing. .

  A state in which common mode noise flows in the power conversion device configured as described above will be described with reference to FIG.

  FIG. 10 is an explanatory diagram for explaining a path through which common mode noise is transmitted in the power conversion device according to Embodiment 4 of the present invention.

  As shown in FIG. 10, common mode noise generated from the converter 22 passes through the third stray capacitance 40 generated between the converter 22 and the housing 72, the first capacitor 70, and the second capacitor 71, for example. Flows along the dashed arrows in the drawing. Therefore, the flow of common mode noise to the fourth stray capacitance 41 generated between the fuel cell 20 and the casing 72 is reduced. Thereby, the influence of the high frequency noise which flows into the fuel cell 20 can be reduced. As a result, the performance and reliability of the power conversion device are improved.

  In this embodiment, the example in which the conductor is composed of the first conductor 57 and the second conductor 58 has been described. However, the present invention is not limited to this. For example, a plurality of conductors composed of two or more are provided between the primary winding and the secondary winding of the transformer 53, a part of the plurality of conductors is connected to the + side bus 28, and the remaining The conductor may be connected to the negative side bus 29. Thereby, transmission of common mode noise can be further suppressed.

  Further, in the present embodiment, an example in which the conductor is composed of the first conductor 57 and the second conductor 58 and each conductor 57, 58 is connected to the first capacitor 70 and the second capacitor 71 will be described. However, it is not limited to this. For example, as in the first embodiment, one conductor is connected to at least one of the connection point D of the positive side bus 28 and the connection point E of the negative side bus 29, and one end of the capacitor is connected to the connection point. The other end may be connected to the housing. Thereby, a structure can be simplified.

  In this embodiment, the first conductor 57 is disposed on the primary winding side of the transformer 53 and the second conductor 58 is disposed on the secondary winding side. However, the reverse arrangement is also possible. Well, the same effect can be obtained.

  The power conversion device for a fuel cell according to the present invention can reduce common mode noise by providing a conductor between the primary winding and the secondary winding of the transformer. It is useful in the technical field of power conversion devices such as automobile batteries that output a large current.

The circuit diagram which shows the circuit structure of the power converter device in Embodiment 1 of this invention. Sectional drawing which shows the trans | transformer structure of the power converter device in Embodiment 1 of this invention Explanatory drawing for demonstrating the path | route which the common mode noise of the power converter device in Embodiment 1 of this invention transmits The circuit diagram which shows the circuit structure of the power converter device in Embodiment 2 of this invention. Sectional drawing which shows the trans | transformer structure of the power converter device in Embodiment 2 of this invention. Sectional drawing which shows another example of the trans | transformer structure of the power converter device in Embodiment 2 of this invention. The circuit diagram which shows the circuit structure of the power converter device in Embodiment 3 of this invention. Explanatory drawing for demonstrating the circuit operation | movement of the power converter device in Embodiment 3 of this invention. The circuit diagram which shows the circuit structure of the power converter device in Embodiment 4 of this invention. Explanatory drawing for demonstrating the path | route which the common mode noise of the power converter device in Embodiment 4 of this invention transmits. Circuit diagram of conventional power converter Sectional drawing which shows the transformer structure of the conventional power converter Explanatory drawing for demonstrating the path | route which the common mode noise of the conventional power converter device transmits

20 Fuel Cell 21 Smoothing Capacitor 22 Converter 23, 53 Transformer 24 Rectifier Smoothing Circuit 25 Inverter 26 Commercial System 27 Conductor 28 + Side Bus 29-Side Bus 42, 72 Housing 57 First Conductor 58 Second Conductor 70 First Capacitor 71 Second capacitor

Claims (4)

A fuel cell, a converter for converting DC power output from the fuel cell, a transformer for transmitting power converted by the converter to an inverter connected to a commercial system, and a transformer connected to the converter At least a conductor provided between a primary winding and a secondary winding of the transformer connected to the inverter, the conductor being connected to the converter on the + side A fuel cell power conversion device, characterized in that it is connected to either a positive side bus connected to an output terminal or a negative side bus connected to a negative side output terminal. The conductor is composed of at least a first conductor and a second conductor, the first conductor is connected to the + side bus connected to the + side output terminal of the fuel cell, and the second conductor 2. The fuel cell power converter according to claim 1, wherein a body is connected to the -side bus connected to the -side output terminal of the fuel cell. The converter includes a smoothing capacitor connected in parallel between the + side output terminal and the − side output terminal of the fuel cell, and the conductor connects between the smoothing capacitor and the fuel cell. The fuel cell power conversion device according to claim 1, wherein the power conversion device is connected to the − side output terminal and the − side bus. A capacitor is further provided, and one end of the capacitor is connected to the same connection point of the conductor connected to one of the + side bus and the − side bus, and the other end of the capacitor is connected to the housing. 4. The fuel cell power converter according to claim 1, wherein the fuel cell power converter is connected. 5.

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