Power conversion device and fault detection circuit

Abstract

To provide a power conversion device and a failure detection circuit capable of detecting failure of a film capacitor even if a conductor unit is not provided on an end face of the film capacitor.SOLUTION: A power conversion device 100 includes: an inverter 1; a film capacitor 2; a mechanical switch 3 that includes a switching lever 32 moving in accordance with expansion caused by increase in internal pressure of the film capacitor and capable of switching ON and OFF by movement of the switching lever 32; and a control unit 5 that detects failure of the film capacitor 2 based on switching of the mechanical switch 3 from one of ON and OFF to the other.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a power conversion device and a fault detection circuit. [Background technology]

[0002] BACKGROUND ART Conventionally, a power conversion device including an inverter is known (see, for example, Patent Document 1).

[0003] The above-mentioned Patent Document 1 discloses a power supply system (power conversion device) including a power supply device (inverter). The power supply system includes the above-mentioned power supply device, a capacitor, and a capacitor abnormality detection device. The power supply device is configured to convert AC power supplied from a main power supply into DC power. The capacitor has a cylindrical shape. The outer periphery of the capacitor is covered with a cover member. One end surface of the capacitor is a terminal portion. The terminal portion is not covered with the cover member. The other end surface of the capacitor is a conductor portion. The conductor portion is not covered with the cover member. The conductor portion is made of a conductive metal member. The capacitor abnormality detection device is an electric circuit including a pair of electrodes and a power supply.

[0004] In the capacitor abnormality detection device of Patent Document 1, when the capacitor is normal, the electrodes and conductors are separated. In this state, no current flows in the electric circuit due to the power supplied from the power source. On the other hand, if the capacitor expands due to aging or other reasons, the electrodes and conductors come into contact, and current flows in the electric circuit due to the power supplied from the power source. An alarm signal is then output based on the current flowing in the electric circuit. In this way, a capacitor failure is detected in the power supply system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2016-162812 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the power supply system of Patent Document 1, a capacitor failure cannot be detected unless the electrodes and conductors come into contact with each other, causing a current to flow through the electrical circuit via the electrodes and conductors. Therefore, in the case of other types of capacitors in which the end faces of the capacitor are insulated, such as by being covered with a cover member, even if the expanded end face of the capacitor comes into contact with the electrodes, no current flows through the electrical circuit, making it impossible to detect a capacitor failure. Therefore, the power supply system of Patent Document 1 has the problem that a capacitor failure cannot be detected unless the capacitor has a conductor on its end face.

[0007] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to provide a power conversion device and a fault detection circuit that are capable of detecting a fault in a film capacitor even if no conductor portion is provided on the end face of the film capacitor. [Means for solving the problem]

[0008] A power conversion device according to a first aspect of the present invention includes an inverter that converts DC power supplied from an external power generation device into AC power and outputs the AC power to an external AC power system; a film capacitor that is disposed on the output side of the inverter and suppresses noise contained in the AC power output from the inverter; a mechanical switch that includes a switching lever that moves in response to expansion due to an increase in internal pressure of the film capacitor and is switched on and off by the movement of the switching lever; and a control unit that detects a failure of the film capacitor based on the switching of the mechanical switch from one of on and off to the other. The film capacitor has a cylindrical shape, and the mechanical switch is configured to switch the output of the mechanical switch from one of ON and OFF states by switching the tip of the switching lever from one of a state in contact with the one end face to the other of a state in which the tip is separated from the one end face as an arc-shaped expansion occurs at one end of the cylindrical shape of the film capacitor due to an increase in internal pressure of the film capacitor. .

[0010] In the power converter according to the first aspect, the film capacitor preferably has a cylindrical shape, and the mechanical switch is configured to switch the output from one of on and off to the other by moving the switching lever in response to an arc-shaped expansion of the end face of the film capacitor due to an increase in internal pressure. With this configuration, the switching lever is mechanically moved using the arc-shaped expansion of the end face of the cylindrical film capacitor due to the internal pressure, so there is no need to provide a structure for moving the switching lever separately from the expansion of the end face of the film capacitor. This makes it possible to prevent the structure of the power converter from becoming too complicated.

[0011] In the power conversion device according to the first aspect, the control unit is preferably configured to perform control to detect a failure in the film capacitor based on an on signal or an off signal output from the mechanical switch. With this configuration, the control unit can detect a failure in the film capacitor simply by obtaining the on signal or the off signal from the mechanical switch, thereby simplifying the mechanism for detecting a failure in the film capacitor.

[0012] In the power conversion device according to the first aspect, preferably, the film capacitor has a cylindrical shape, and the mechanical switch is configured to rotate the switching lever by moving from the end face of the film capacitor toward the tip of the expanded portion of the film capacitor by an amount equivalent to the expansion of the end face of the film capacitor due to an increase in internal pressure, thereby switching the output from one of on and off to the other. With this configuration, the arc-shaped expansion of the end face of the cylindrical film capacitor caused by the internal pressure is used to move the mechanical switch, thereby rotating the switching lever and switching the mechanical switch on and off, so that the expansion of the end face of the film capacitor can be directly detected by the mechanical switch, and therefore the expansion of the end face of the film capacitor can be reliably detected by the mechanical switch.

[0013] In the power converter according to the first aspect, the film capacitor preferably has a cylindrical shape, and further includes a switch mounting member attached to the film capacitor for mounting the mechanical switch to the film capacitor. With this configuration, the mechanical switch can be disposed near the film capacitor, thereby preventing the power converter from becoming larger in size due to the installation of the mechanical switch.

[0014] In this case, preferably, the film capacitor includes a protrusion provided on an end surface, the switch mounting member is attached to the protrusion, and the mechanical switch is configured to move together with the switch mounting member from the other end surface of the film capacitor toward the tip of the expanded portion of the film capacitor by an amount equivalent to the expansion of the other end surface of the film capacitor due to an increase in internal pressure, thereby rotating the switching lever of the mechanical switch and switching the output from one of on and off to the other. With this configuration, simply by attaching the mechanical switch to the switch mounting member attached to the protrusion of the film capacitor, the switching lever of the mechanical switch can be rotated when the other end surface of the film capacitor expands, thereby preventing the structure for switching the output of the mechanical switch from one of on and off to the other from becoming complicated.

[0015] In the power converter having the switch mounting member attached to the protruding portion, the mechanical switch is preferably attached to the protruding portion of the film capacitor via the switch mounting member, and the tip of the switching lever is positioned near the periphery of the end face of the film capacitor. With this configuration, the tip of the switching lever can be positioned at a position where the expansion of the film capacitor is minimized in a film capacitor whose end face expands in an arc-shaped manner. Furthermore, by attaching the mechanical switch to the protruding portion via the switch mounting member, the mechanical switch can be moved in response to the expansion of the central portion of the film capacitor. Here, the mechanical switch moves in a direction from the other end face of the film capacitor toward the tip of the expanded portion of the film capacitor in response to the expansion of the central portion of the film capacitor. Meanwhile, the tip of the switching lever moves in a direction opposite to the direction toward the tip of the expanded portion. This allows the switching lever to move in the opposite direction by an amount corresponding to the difference in displacement between the expansion of the central portion of the film capacitor and the expansion near the periphery of the end face. As a result, there is no need to provide a structure for moving the switching lever separately from the expansion of the end face of the film capacitor, thereby reducing the complexity of the power converter structure. The vicinity of the periphery of the end face of the film capacitor is a broad concept that includes not only the periphery of the end face of the film capacitor but also the area closer to the inside than the periphery of the end face of the film capacitor.

[0016] In the power conversion device according to the first aspect, the control unit is preferably configured to control the inverter to stop when the mechanical switch detects expansion of the film capacitor due to an increase in internal pressure. With this configuration, noise contained in the AC power output from the inverter due to a failure of the film capacitor can be prevented from being output to an external AC power system, thereby preventing failure of the external AC power system.

[0017] In the power conversion device according to the first aspect, the control unit is preferably configured to control the mechanical switch to notify the user of a failure in the film capacitor based on detection of expansion due to an increase in internal pressure of the film capacitor. This configuration allows the user to be reliably informed of the failure in the film capacitor, and can prompt the user to perform work such as replacing the film capacitor.

[0018] A fault detection circuit according to a second aspect of the present invention includes a film capacitor that suppresses disturbances contained in AC power output from an inverter that converts DC power supplied from an external power generation device into AC power and outputs the AC power to an external AC power system; a mechanical switch that includes a switching lever that moves in response to expansion due to an increase in internal pressure of the film capacitor and is switched on and off by movement of the switching lever; and a control unit that detects a fault in the film capacitor based on the mechanical switch being switched from one of on and off to the other. The film capacitor has a cylindrical shape, and the mechanical switch is configured to switch the output of the mechanical switch from one of ON and OFF states by switching the tip of the switching lever from one of a state in contact with the one end face to the other of a state in which the tip is separated from the one end face as an arc-shaped expansion occurs at one end of the cylindrical shape of the film capacitor due to an increase in internal pressure of the film capacitor. .

[0019] A fault detection circuit according to a second aspect of the present invention includes a mechanical switch that is switched on and off by moving a switching lever, as described above, and a control unit that detects a fault in the film capacitor based on the mechanical switch switching from on or off to the other. This allows the mechanical switch to be switched on and off by mechanically moving the switching lever in response to expansion due to an increase in internal pressure of the film capacitor, even if the end face of the film capacitor is covered with a cover member and the conductive metal member is not exposed. As a result, a fault detection circuit can be obtained that can detect a fault in a film capacitor even if no conductor is provided on the end face of the film capacitor. [Effects of the Invention]

[0020] According to the present invention, as described above, it is possible to detect a failure in a film capacitor even if no conductor portion is provided on the end surface of the film capacitor. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram illustrating a power conversion system including a power conversion device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram illustrating a normal state of a film capacitor of the power conversion device according to the embodiment. [Figure 3] FIG. 2 is a schematic diagram illustrating a fault state of a film capacitor of a power conversion device according to an embodiment. [Figure 4] 3A and 3B are schematic diagrams illustrating a conductive state of a mechanical switch of a power conversion device according to an embodiment. [Figure 5] FIG. 2 is a schematic diagram illustrating a disconnection state of a mechanical switch of a power conversion device according to an embodiment. [Figure 6] FIG. 10 is a schematic diagram illustrating a conductive state of a mechanical switch of a power conversion device according to a modified example of the embodiment. [Figure 7] FIG. 10 is a schematic diagram illustrating a disconnection state of a mechanical switch of a power conversion device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

[0023] The configuration of a power conversion device 100 according to one embodiment will be described with reference to FIGS.

[0024] As shown in Fig. 1, the power conversion device 100 is configured to convert DC power supplied from an external power generation device 200 into AC power and supply it to an external AC power system 300. The external power generation device 200 is a solar power generation device. The power conversion device 100 includes an inverter 1, a film capacitor 2, a mechanical switch 3 (see Fig. 4), a switch mounting member 4 (see Fig. 4), and a control unit 5.

[0025] The inverter 1 is configured to convert DC power supplied from an external power generating device 200 into AC power and output the AC power to an external AC power system 300. The inverter 1 includes a first inverter unit 11, a second inverter unit 12, and a third inverter unit 13. In the inverter 1, the DC power supplied from the external power generating device 200 is converted into AC power by at least one of the first inverter unit 11, the second inverter unit 12, and the third inverter unit 13 in accordance with the power generated by the external power generating device 200. Furthermore, in the inverter 1, for example, if the first inverter unit 11 fails, the DC power supplied from the external power generating device 200 is converted into AC power by either the second inverter unit 12 or the third inverter unit 13. The same applies to the second inverter unit 12 and the third inverter unit 13. In this way, the inverter 1 has a redundant configuration.

[0026] The film capacitor 2 is configured to suppress harmonics and the like contained in the AC power output from the inverter 1. In other words, the film capacitor 2 is configured to suppress noise contained in the AC power output from the inverter 1. The film capacitor 2 is arranged on the output side of the inverter 1. A plurality of film capacitors 2 are arranged corresponding to each of the first inverter section 11, the second inverter section 12, and the third inverter section 13.

[0027] As shown in FIG. 2, the film capacitor 2 has a cylindrical shape. The film capacitor 2 includes an outer peripheral cover 21, an end face cover 22, a terminal 23, and a protrusion 24. The outer peripheral cover 21 is a cover that covers the outer peripheral surface of the film capacitor 2. The end face cover 22 is a cover that covers one end face of the film capacitor 2. The terminal 23 is provided on one end face of the film capacitor 2. The terminal 23 protrudes from one end face of the film capacitor 2. The protrusion 24 is a stud and also a terminal. The protrusion 24 is provided on the other end face of the film capacitor 2. The protrusion 24 protrudes from the other end face of the film capacitor 2.

[0028] As shown in Figure 3, failures occur in the film capacitor 2 due to factors such as aging, loads from solar power generation, and severe temperature cycles caused by outdoor installation. Failures in the film capacitor 2 occur when the temperature inside the film capacitor 2 rises due to factors that cause the failure. This temperature rise causes an increase in the internal air pressure of the film capacitor 2, which leads to the expansion of the end faces of the film capacitor 2. In the film capacitor 2 shown in Figure 3, the other end face not covered by the end face cover 22 expands. Because the outer peripheral cover 21 covers the periphery of the end face of the film capacitor 2, the expansion of the end face of the film capacitor 2 is greater at the center than at the end face. Thus, the end face of the film capacitor 2 expands in an arc-like manner in the event of a failure.

[0029] (mechanical switch) 4, the power conversion device 100 of this embodiment is provided with a mechanical switch 3 to detect a failure in the film capacitor 2. The mechanical switch 3 is configured so that an internal detection circuit 31a is turned on and off in response to expansion of the end face of the film capacitor 2.

[0030] As shown in Figures 4 and 5, the mechanical switch 3 includes a main body 31 and a switching lever 32. A detection circuit 31a is provided inside the main body 31. The detection circuit 31a is electrically connected to the control unit 5. The switching lever 32 is configured to switch the detection circuit 31a on and off. The switching lever 32 moves in response to expansion caused by an increase in the internal pressure of the film capacitor 2. The tip 32a of the switching lever 32 is located near the periphery of the end face of the film capacitor 2. Taking manufacturing errors into consideration, the tip 32a of the switching lever 32 is located inside the periphery of the end face of the film capacitor 2.

[0031] Here, the mechanical switch 3 is configured to move in direction D from the end face of the film capacitor 2 toward the tip end of the expanded portion 2a of the film capacitor 2 by an amount corresponding to the expansion of the end face of the film capacitor 2 due to an increase in internal pressure, thereby rotating the switching lever 32 in the direction opposite to direction D, thereby switching the output from on to off. In other words, the mechanical switch 3 is configured by the switch mounting member 4 to move together with the expansion of the end face of the film capacitor 2.

[0032] The switch mounting member 4 is attached to the film capacitor 2 and is used to attach the mechanical switch 3 to the film capacitor 2. The switch mounting member 4 includes an attachment portion 41 and an accommodating portion .

[0033] The tip of the mounting portion 41 is fixed to the protruding portion 24. That is, the switch mounting member 4 is mounted to the protruding portion 24 by the mounting portion 41. Furthermore, the mechanical switch 3 is mounted to the protruding portion 24 of the film capacitor 2 via the switch mounting member 4. The mounting portion 41 extends along the radial direction of the cylindrical film capacitor 2. The radial length of the mounting portion 41 is set by the length of the switching lever 32. The accommodating portion 42 is configured to accommodate the mechanical switch 3. The accommodating portion 42 is provided radially outward of the mounting portion 41. In this way, the switch mounting member 4 mounts the mechanical switch 3 accommodated in the accommodating portion 42 to the protruding portion 24 by the mounting portion 41.

[0034] As a result, in the mechanical switch 3, movement of the switching lever 32 causes the tip 32a of the switching lever 32 to move in response to the expansion of the end face of the film capacitor 2, and the switching lever 32 moves away from the contact 33 of the mechanical switch 3, thereby interrupting the detection circuit 31a. As a result, the mechanical switch 3 is switched on and off. In other words, the mechanical switch 3 is configured to switch the output from on to off when the switching lever 32 moves in the direction opposite to direction D as the other end face of the film capacitor 2 expands in an arc shape due to an increase in internal pressure.

[0035] Specifically, the mechanical switch 3 is configured to move together with the switch mounting member 4 in direction D from the other end face of the film capacitor 2 toward the tip side of the expanded portion 2a of the film capacitor 2 by an amount corresponding to the expansion of the other end face of the film capacitor 2 due to the increase in internal pressure, thereby rotating the switching lever 32 of the mechanical switch 3 in the direction opposite to direction D, thereby switching the output from on to off.

[0036] Such a mechanical switch 3 is arranged so as to be fitted between the other end of the film capacitor 2 (the tip of the protrusion 24) and the other end of the outer peripheral cover 21 of the film capacitor 2 in the direction D. In other words, the mechanical switch 3 is arranged so as to be fitted between one end of the film capacitor 2 and the other end of the film capacitor 2 in the direction D.

[0037] (Control unit) The control unit 5 is configured to detect a failure in the film capacitor 2 based on the switching of the mechanical switch 3 from on to off. That is, the control unit 5 is configured to perform control to detect a failure in the film capacitor 2 based on the off signal output from the mechanical switch 3. Specifically, the control unit 5 has a CPU (Central Processing Unit) and a storage unit having memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory).

[0038] The control unit 5 is configured to perform control to stop the inverter 1 based on the detection by the mechanical switch 3 of expansion due to an increase in the internal pressure of the film capacitor 2. That is, the control unit 5 is configured to perform control to stop the inverter corresponding to the film capacitor 2 whose expansion has been detected, among the first inverter unit 11, the second inverter unit 12, and the third inverter unit 13 (plurality of inverter units), based on the detection by the mechanical switch 3 of expansion of the film capacitor 2.

[0039] Furthermore, the control unit 5 is configured to perform control to notify the user of a failure of the film capacitor 2 based on the detection of expansion due to an increase in the internal pressure of the film capacitor 2 by the mechanical switch 3. Specifically, the control unit 5 is configured to perform control to display a message on the display unit 400 (see FIG. 1) based on the detection of expansion due to an increase in the internal pressure of the film capacitor 2. The display unit 400 is configured from a liquid crystal display or the like.

[0040] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0041] As described above, in this embodiment, the power conversion device 100 includes the mechanical switch 3 that is switched on and off by movement of the switching lever 32, and the control unit 5 that detects a failure in the film capacitor 2 based on the mechanical switch 3 being switched from on to off. As a result, even if the end face of the film capacitor 2 is covered with a cover member and no conductive metal member is exposed, the mechanical switch 3 can be switched on and off by mechanically moving the switching lever 32 as the film capacitor 2 expands due to an increase in internal pressure. As a result, a failure in the film capacitor 2 can be detected even if no conductor is provided in the film capacitor 2.

[0042] Furthermore, in this embodiment, as described above, the film capacitor 2 has a cylindrical shape. The mechanical switch 3 is configured to switch the output from on to off by moving the switching lever 32 in response to an arc-shaped expansion of the end face of the film capacitor 2 due to an increase in internal pressure. As a result, the switching lever 32 is moved using the arc-shaped expansion of the end face of the cylindrical film capacitor 2 caused by the internal pressure, so there is no need to provide a structure for moving the switching lever 32 separately from the expansion of the end face of the film capacitor 2. As a result, the structure of the power conversion device 100 can be prevented from becoming complicated.

[0043] Furthermore, in this embodiment, as described above, the control unit 5 is configured to perform control to detect a failure in the film capacitor 2 based on the off signal output from the mechanical switch 3. This allows the control unit 5 to detect a failure in the film capacitor 2 simply by obtaining the off signal from the mechanical switch 3, thereby simplifying the mechanism for detecting a failure in the film capacitor 2.

[0044] Furthermore, in this embodiment, as described above, the film capacitor 2 has a cylindrical shape. The mechanical switch 3 is configured to move in direction D from the end face of the film capacitor 2 toward the tip of the expanded portion 2a of the film capacitor 2 by an amount corresponding to the expansion of the end face of the film capacitor 2 due to an increase in internal pressure, thereby rotating the switching lever 32 and switching the output from ON to OFF. In this way, the arc-shaped expansion of the end face of the cylindrical film capacitor 2 caused by the internal pressure is used to move the mechanical switch 3, thereby rotating the switching lever 32 and switching the mechanical switch 3 ON / OFF. Therefore, the expansion of the end face of the film capacitor 2 can be directly detected by the mechanical switch 3, and therefore the expansion of the end face of the film capacitor 2 can be reliably detected by the mechanical switch 3.

[0045] Furthermore, in this embodiment, as described above, the film capacitor 2 has a cylindrical shape. The power conversion device 100 includes a switch mounting member 4 that is attached to the film capacitor 2 and that mounts the mechanical switch 3 to the film capacitor 2. This allows the mechanical switch 3 to be located near the film capacitor 2, thereby preventing the power conversion device 100 from becoming larger in size due to the installation of the mechanical switch 3.

[0046] Furthermore, in this embodiment, as described above, the film capacitor 2 includes a protrusion 24 provided on its end surface. The switch mounting member 4 is attached to the protrusion 24. The mechanical switch 3 is configured to move together with the switch mounting member 4 in direction D from the other end surface of the film capacitor 2 toward the tip of the expanded portion 2a of the film capacitor 2 by an amount equivalent to the expansion of the other end surface of the film capacitor 2 due to an increase in internal pressure, thereby rotating the switching lever 32 of the mechanical switch 3 and switching the output from ON to OFF. Thus, simply by attaching the mechanical switch 3 to the switch mounting member 4 attached to the protrusion 24 of the film capacitor 2, the switching lever 32 of the mechanical switch 3 can be rotated when the other end surface of the film capacitor 2 expands, thereby preventing the structure for switching the output of the mechanical switch 3 from ON to OFF from becoming complicated.

[0047] Furthermore, in this embodiment, as described above, the mechanical switch 3 is attached to the protruding portion 24 of the film capacitor 2 via the switch mounting member 4, and the tip 32a of the switching lever 32 is located near the periphery of the end face of the film capacitor 2. This allows the tip 32a of the switching lever 32 to be located at a position where the expansion of the film capacitor 2, whose end face expands in an arc-like shape, is minimized. Furthermore, by attaching the mechanical switch 3 to the protruding portion 24 via the switch mounting member 4, the mechanical switch 3 can be moved in accordance with the expansion of the central portion of the film capacitor 2. Here, the mechanical switch 3 moves in a direction from the other end face of the film capacitor 2 toward the tip of the expanded portion of the film capacitor 2 in accordance with the expansion of the central portion of the film capacitor 2. Meanwhile, the tip 32a of the switching lever 32 moves in a direction opposite to the direction toward the tip of the expanded portion. As a result, the switching lever 32 can be moved in the opposite direction by an amount corresponding to the difference in displacement between the expansion of the central portion of the film capacitor 2 and the expansion near the periphery of the end face. As a result, there is no need to provide a structure for moving the switching lever 32 separately from the expansion of the end face of the film capacitor 2, which prevents the structure of the power conversion device 100 from becoming complicated. Note that the vicinity of the periphery of the end face of the film capacitor 2 is a broad concept that includes not only the periphery of the end face of the film capacitor 2 but also the vicinity inside the periphery of the end face of the film capacitor 2.

[0048] Furthermore, in this embodiment, as described above, the control unit 5 is configured to perform control to stop the inverter 1 based on the detection by the mechanical switch 3 of expansion due to an increase in the internal pressure of the film capacitor 2. This makes it possible to prevent noise contained in the AC power output from the inverter 1 due to a failure of the film capacitor 2 from being output to the external AC power system 300, thereby preventing a failure of the external AC power system 300.

[0049] Furthermore, in this embodiment, as described above, the control unit 5 is configured to perform control to notify the user of a failure in the film capacitor 2 based on the detection by the mechanical switch 3 of expansion due to an increase in the internal pressure of the film capacitor 2. This allows the user to be reliably informed of the failure in the film capacitor 2, and can prompt the user to perform work such as replacing the film capacitor 2.

[0050] Furthermore, in this embodiment, as described above, the fault detection circuit includes a film capacitor 2 that suppresses disturbances contained in AC power output from an inverter 1 that converts DC power supplied from an external power generation device 200 into AC power and outputs the AC power to an external AC power grid 300. The fault detection circuit includes a switching lever 32 that moves in response to expansion due to an increase in internal pressure of the film capacitor 2, and a mechanical switch 3 that is switched on and off by the movement of the switching lever 32. The fault detection circuit also includes a control unit 5 that detects a fault in the film capacitor 2 based on the mechanical switch 3 being switched from on to off. As a result, even if the end face of the film capacitor 2 is covered with a cover member and the conductive metal member is not exposed, the mechanical switch 3 can be switched on and off by the mechanical action of the switching lever 32 in response to expansion due to an increase in internal pressure of the film capacitor 2. As a result, a fault detection circuit that can detect a fault in the film capacitor 2 can be obtained, even if a conductor portion is not provided on the end face of the film capacitor 2.

[0051] Furthermore, in this embodiment, as described above, the mechanical switch 3 is configured to switch the output from ON to OFF by moving the switching lever 32 in response to the arc-shaped expansion of the end face of the film capacitor 2 due to an increase in internal pressure. This differs from when the mechanical switch 3 switches from OFF to ON. Instead of power flowing to the detection circuit 31a only once when a failure occurs, power can be supplied to the detection circuit 31a until the failure is detected, preventing an unexpected power supply to the detection circuit 31a. This prevents a failure of the detection circuit 31a caused by an unexpected power supply to the detection circuit 31a.

[0052] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications (variations) within the meaning and scope of the claims.

[0053] For example, in the above embodiment, the mechanical switch 3 is configured to switch the output from ON to OFF by moving the switching lever 32 in response to arc-shaped expansion of the other end surface of the film capacitor 2 due to an increase in internal pressure, but the present invention is not limited to this. In the present invention, as in the modified examples shown in Figures 6 and 7, the mechanical switch 3 may be configured to switch the output from OFF to ON by moving the switching lever 32 in response to arc-shaped expansion of the other end surface of the film capacitor 2 due to an increase in internal pressure, while the mechanical switch 3 is fixed near the film capacitor 2 by a switch mounting member 204. In this case, the control unit 5 is configured to perform control to detect a failure of the film capacitor 2 based on the ON signal output from the mechanical switch 3.

[0054] In the above embodiment, the tip 32a of the switching lever 32 is disposed near the periphery of the end face of the film capacitor 2, but the present invention is not limited to this. In the present invention, the tip of the switching lever may be disposed in the center of the end face of the film capacitor 2.

[0055] In the above embodiment, the mechanical switch 3 is configured to switch the output from on to off by moving in direction D from the end face of the film capacitor 2 toward the tip end of the expanded portion 2a of the film capacitor 2 by an amount corresponding to the expansion of the end face of the film capacitor 2 due to an increase in internal pressure, but the present invention is not limited to this. In the present invention, the mechanical switch may be configured to switch the output from on to off without moving. [Explanation of symbols]

[0056] 1 inverter 2. Film capacitors 3 Mechanical Switches 4, 204 Switch mounting member 5. Control section 24 Protrusion 32 Switching lever 100 Power conversion device 200 External power generation equipment 300 External AC power system

Claims

1. an inverter that converts DC power supplied from an external power generation device into AC power and outputs the AC power to an external AC power system; a film capacitor disposed on the output side of the inverter to suppress noise contained in the AC power output from the inverter; a mechanical switch including a switching lever that moves in accordance with expansion due to an increase in internal pressure of the film capacitor, and is switched on and off by the movement of the switching lever; a control unit that detects a failure of the film capacitor based on the mechanical switch being switched from one of on and off to the other, The film capacitor has a cylindrical shape, The mechanical switch is A power conversion device configured to switch the output of the mechanical switch from one of on and off states to the other as the tip of the switching lever switches from one state of contact with the one end face to the other state of separation in response to an arc-shaped expansion of one end face at one end of the cylindrical shape of the film capacitor due to an increase in internal pressure of the film capacitor.

2. The power conversion device according to claim 1 , wherein the control unit is configured to perform control to detect a failure of the film capacitor based on an ON signal or an OFF signal output from the mechanical switch.

3. The film capacitor has a cylindrical shape, 3. The power conversion device according to claim 1, wherein the mechanical switch is configured to rotate the switching lever by moving in a direction from the end face of the film capacitor toward the tip of the expanded portion of the film capacitor by an amount corresponding to the expansion of the end face of the film capacitor due to an increase in internal pressure, thereby switching the output from one of on and off to the other.

4. The film capacitor has a cylindrical shape, The power conversion device according to any one of claims 1 to 3, further comprising a switch mounting member attached to the film capacitor for mounting the mechanical switch to the film capacitor.

5. the film capacitor includes a protrusion provided on an end surface, The switch mounting member is attached to the protrusion, 5. The power conversion device of claim 4, wherein the mechanical switch is configured to move together with the switch mounting member in a direction from the other end surface of the film capacitor toward the tip of the expanded portion of the film capacitor by an amount corresponding to the expansion of the other end surface of the film capacitor due to an increase in internal pressure, thereby rotating the switching lever of the mechanical switch and switching the output from one of on and off to the other.

6. the mechanical switch is attached to the protruding portion of the film capacitor via the switch mounting member, The power conversion device according to claim 5 , wherein a tip end of the switching lever is disposed near a peripheral edge of an end face of the film capacitor.

7. The power conversion device according to any one of claims 1 to 6, wherein the control unit is configured to control the inverter to stop based on detection by the mechanical switch of expansion due to an increase in internal pressure of the film capacitor.

8. The power conversion device according to any one of claims 1 to 7, wherein the control unit is configured to control the mechanical switch to notify a user of a failure of the film capacitor based on the detection of expansion due to an increase in internal pressure of the film capacitor.

9. a film capacitor that suppresses disturbances contained in AC power output from an inverter that converts DC power supplied from an external power generation device into AC power and outputs the AC power to an external AC power system; a mechanical switch including a switching lever that moves in accordance with expansion due to an increase in internal pressure of the film capacitor, and is switched on and off by the movement of the switching lever; a control unit that detects a failure of the film capacitor based on the mechanical switch being switched from one of on and off to the other, The film capacitor has a cylindrical shape, The mechanical switch is A fault detection circuit configured to switch the output of the mechanical switch from one of on and off to the other by causing the tip of the switching lever to switch from one state of contact with the one end face to the other state of separation in response to an arcuate expansion of one end face at one end of the cylindrical shape of the film capacitor due to an increase in internal pressure of the film capacitor.

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