Power conversion control device, power conversion device, and protection method

Abstract

This electric power conversion control device comprises: an optical fiber; an optical detection part; and a protection control part. The optical fiber is formed to guide light taken in through the side surface of an extending light guide part in the extension direction and to output the light from an end of the light guide part. The optical detection part detects the light guided to the end of the light guide part. When the optical detection part has detected light resulting from an accident accompanied by arc flash, the protection control part halts electric power conversion carried out by an electric power converter relating to the optical fiber.

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a power conversion control device, a power conversion device, and a protection method. [Background technology]

[0002] Arc flashes can occur due to accidents such as short circuits and insulation breakdowns in the circuits that make up power conversion equipment. Even if a protection circuit (protective device) is installed to detect and cut off the fault current caused by an arc flash accident, it is sometimes unable to prevent secondary failures resulting from this accident. There has been a demand for a power conversion control device that can prevent secondary failures resulting from an accident that generates an arc flash. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2000-065887 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide a power conversion control device, a power conversion device, and a protection method that can prevent the occurrence of secondary failures caused by accidents that cause arc flashes in a simple manner. [Means for solving the problem]

[0005] According to an embodiment, a power conversion control device includes an optical fiber, a light detection unit, and a protection control unit. An optical fiber is arranged in the vicinity of a plurality of semiconductor switches to be detected, and light irradiated from around the optical fiber is directed in the direction of extension of the optical fiber. The light is taken in by the side of the extending light guide section. In the above captureThe light guide is configured to guide the light in the extension direction and output it from the end of the light guide. The light detector detects the light guided to the end of the light guide. The protection controller interrupts power conversion by the power converter related to the optical fiber when the light detector detects light caused by an accident involving an arc flash. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of a power conversion device according to an embodiment; [Figure 2] 1 is a configuration diagram of a power conversion control device according to an embodiment; [Figure 3A] FIG. 2 is a cross-sectional view of an optical fiber according to an embodiment. [Figure 3B] FIG. 2 is a longitudinal cross-sectional view of a linearly arranged section of optical fiber. [Figure 3C] FIG. 1 is a cross-sectional view of optical fibers arranged in an arc. [Figure 3D] FIG. 1 is a cross-sectional view of optical fibers arranged in an arc. [Figure 4A] FIG. 3 is a cross-sectional view showing the arrangement of optical fibers according to the embodiment. [Figure 4B] FIG. 2 is a plan view showing the arrangement of optical fibers according to the embodiment. [Figure 5] 10A and 10B are diagrams for explaining protection control when an arc flash occurs according to an embodiment. [Figure 6A] FIG. 10 is a cross-sectional view showing the arrangement of optical fibers in a first modified example of the embodiment. [Figure 6B] FIG. 10 is a plan view showing the arrangement of optical fibers in a first modified example of the embodiment. [Figure 7] FIG. 2 is a schematic configuration diagram of a power conversion control device according to a first modified example of the embodiment. [Figure 8A] FIG. 10 is a cross-sectional view showing the arrangement of optical fibers in a second modified example of the embodiment. [Figure 8B] FIG. 10 is a plan view showing the arrangement of optical fibers in a second modified example of the embodiment. [Figure 9] FIG. 10 is a schematic configuration diagram of a power conversion control device according to a second modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] The following describes a power conversion control device, a power conversion device, and a protection method according to embodiments. Note that "connection" as used in this specification is not limited to physical connection, but also includes electrical connection. "Based on XX" as used in this specification means "based on at least XX," and includes cases where it is based on other elements in addition to XX. Furthermore, "based on XX" is not limited to cases where XX is directly used, but also includes cases where it is based on XX after calculation or processing. "XX" is any element (for example, any information). Also, the same symbol is used for components having the same or similar functions.

[0008] First, a power conversion device 1 according to an embodiment will be described. FIG. 1 is a schematic configuration diagram of a power conversion device 1 according to an embodiment. 1 includes a rectifier 110, a reactance 120, a first capacitor 130, an inverter 150, and a control device 20. The rectifier 110 and the inverter 150 form a main circuit 190 of the power conversion device 1.

[0009] The rectifier 110 rectifies AC power. An input terminal of the rectifier 110 is connected to an AC power system PS via a transformer T, and an output terminal of the rectifier 110 is connected to the inverter 150 via a DC link 180. For example, the rectifier 110 is formed as a three-level type. In this case, the rectifier 110 includes a positive bridge circuit 110P and a negative bridge circuit 110N. The DC link 180 includes a positive bus PBL, a neutral conductor N, and a negative bus NBL. The positive bridge circuit 110P and the negative bridge circuit 110N full-wave rectify the power supplied from the AC power system PS via the transformer T and supply the power to the positive bus PBL and the negative bus NBL. The rectifier 110 is an example of a converter (diode converter) that does not have a regenerative circuit. The power supply line connecting the rectifier 110 and the transformer T may be provided with a fuse and a transformer.

[0010] The first capacitor 130 (not shown) is a capacitor for smoothing the voltage of the DC link 180. For example, the first capacitor 130 includes a positive-side first capacitor 130P and a negative-side first capacitor 130N. The positive-side first capacitor 130P is connected to a positive bus PBL and a neutral conductor N of the DC link 180. The negative-side first capacitor 130N is connected to a negative bus NBL and a neutral conductor N of the DC link 180. The set of the rectifier 110 and the first capacitor 130 is an example of a power supply that supplies power to the inverter 150, which will be described later. Note that the positive-side first capacitor 130P is provided with a parallel discharge circuit PCP, and the negative-side regeneration amount adjustment unit 210N is provided with a parallel discharge circuit PCN.

[0011] The inverter 150 is also formed, for example, as a three-level type. The inverter 150 converts the power supplied from the rectifier 110 via the DC link 180 based on the control of the control device 20 to generate AC power. The electric motor 2 is connected to the output terminal of the inverter 150. The inverter 150 supplies the converted AC power to the electric motor 2. The inverter 150 and the electric motor 2 are, for example, a three-phase AC type having a U phase, a V phase, and a W phase, but are not limited to this and may be a single-phase AC type or a polyphase AC type with another number of phases. The electric motor 2 is, for example, an induction motor, but is not limited to this. The electric motor 2 is an example of a load.

[0012] For example, inverter 150 includes a plurality of semiconductor switching elements for each of the U, V, and W phases, forming a full-bridge configuration. Each of the semiconductor switching elements is provided with a flywheel diode. Detailed description of the freewheel diodes will be omitted below for simplicity.

[0013] More specifically, inverter 150 includes switches QU1 to QU4 as U-phase semiconductor switching elements, switches QV1 to QV4 as V-phase semiconductor switching elements, and switches QW1 to QW4 as W-phase semiconductor switching elements. The semiconductor switching elements of each phase are, for example, IGBTs (Insulated Gate Bipolar Transistors), and are cascade-connected as shown in the figure. There are no restrictions on the type of semiconductor switching elements, and they may be power MOSFETs or the like.

[0014] Protection circuits (150UP, 150UN, 150VP, 150VN, 150WP, 150WN) are provided between the semiconductor switching elements of each phase of the inverter 150 and the DC link 180 to protect the circuit from overcurrent. For example, these protection circuits each include a fuse that blows when an overcurrent exceeds a predetermined current capacity, and are configured as "fuses with alarm contacts" that close when the fuse blows. When the fuse blows, each protection circuit closes the alarm contact to externally indicate that an alarm state has occurred.

[0015] The inverter 150 is provided with an optical fiber 26 that is connected to the control device 20. The optical fiber 26 is configured separately from other optical fibers that are used to control the inverter 150. This will be described in detail later.

[0016] The control device 20 of the embodiment will be described with reference to FIG. 2 is a configuration diagram of the control device 20 according to the embodiment. The control device 20 is an example of a power conversion control device. The control device 20 monitors and controls the state of the inverter 150.

[0017] As shown in Fig. 2, the control device 20 is connected to the inverter 150. The semiconductor switching elements of each phase of the inverter 150 are controlled to be turned on and off by a gate pulse (GP3) supplied from the control device 20. In the configuration shown in Fig. 2, a gate pulse of an optical signal is supplied from the control device 20 via an optical fiber, and an OE unit of the inverter 150 converts the optical signal into the gate pulse GP3. The gate pulse GP3 is supplied to the gate of the semiconductor switching element of each phase via a driver circuit.

[0018] The control device 20 may include a processor such as a CPU. At least a part of the control device 20 may be implemented as a software function unit that functions when a processor such as a CPU executes a program, or the control device 20 may be implemented entirely as a hardware function unit such as an LSI. There is no limit to the number of processors, and the control device 20 may be configured with appropriate divisions.

[0019] The control device 20 includes an inverter control unit 21, a GB unit 22 (protection control unit), an EO unit 23, an analysis unit 24, and an OE unit 25 (light detection unit). An optical fiber 26 used as a sensor is connected to the control device 20. The control device 20 may be provided with the optical fiber 26, or the optical fiber 26 may be provided separately.

[0020] The inverter control unit 21 controls the inverter 150 based on the detection results of the transformer HCT, a protection circuit, and the like provided in the inverter 150. The control method for the inverter 150 may be selected as appropriate from PWM (Pulse Width Modulation) control, vector control, and the like. When a fault is detected based on the detection results of the protection circuit provided in the inverter 150, the inverter control unit 21 may stop power conversion of the inverter 150 for protection purposes.

[0021] For example, the inverter control unit 21 generates a gate pulse GP1 for controlling the on / off of the semiconductor switching elements of each phase of the inverter 150 and supplies the gate pulse GP1 to the GB unit 22 in a normal state.

[0022] In order to put the inverter 150 into a non-operating state, the inverter control unit 21 supplies a gate block signal GB1 for commanding the GB unit 22 to stop operation, thereby restricting the supply of gate pulses to the inverter 150.

[0023] The GB unit 22 receives the gate pulse GP1 and the gate block signals GB1, GB2, and GB3 and generates the gate pulse GP2. For example, the GB unit 22 determines the output of the gate pulse GP2 depending on the signal state of the gate pulse GP1. At this time, the GB unit 22 may limit the supply of gate pulses to the inverter 150 based on the states of the gate block signals GB1, GB2, and GB3. When any of the gate block signals GB1, GB2, and GB3 is in a significant state, the GB unit 22 limits the output of the gate pulse GP2, thereby preventing the output of any pulses, regardless of the signal state of the gate pulse GP1 supplied from the inverter control unit 21. For example, the GB unit 22 is configured to interrupt power conversion by the inverter 150 by controlling the semiconductor switching elements related to power conversion of the inverter 150 to an off state using the light detection result by the OE unit 25 (described later).

[0024] The EO unit 23 generates an optical pulse according to the state of the gate pulse GP2 supplied from the GB unit 22. The EO unit 23 supplies the generated optical pulse to the inverter 150 via a light-shielding optical fiber.

[0025] The analysis unit 24 receives signals indicating the operating state of the inverter 150 and analyzes the operating state of the inverter 150 based on these signals. For example, the analysis unit 24 analyzes the operating state of the inverter 150 including the output currents Iu, Iv, and Iw of the inverter 150, the output voltages Vu, Vv, and Vw of the inverter 150, and the state OC1 of the protection circuit.

[0026] The OE unit 25 (light detection unit) includes a photoelectric conversion unit such as a photodiode or phototransistor, and generates an electrical signal corresponding to the amount of detected light. The OE unit 25 uses the electrical signal to identify the presence of light exceeding a predetermined amount. For example, the OE unit 25 detects light guided to the end 261PA (FIGS. 3A and 3B) of the light guide unit 261 (FIGS. 3A and 3B) of the optical fiber 26, and outputs a gate block signal GB3 when it detects light exceeding a predetermined amount.

[0027] When the OE unit 25 detects light exceeding a predetermined amount as described above and generates a gate block signal GB3, the GB unit 22 (protection control unit) limits the output of the gate pulse GP2 and controls the semiconductor switching element of the inverter 150 to the off state, thereby interrupting power conversion by the inverter 150.

[0028] An embodiment of the optical fiber 26 will be described with reference to FIGS. 3A to 3D. Fig. 3A is a cross-sectional view of an optical fiber 26 according to an embodiment. Fig. 3B is a cross-sectional view of a linearly arranged section of the optical fiber 26. Figs. 3C and 3D are cross-sectional views of the optical fiber 26 arranged in an arc. The arrows shown in Figs. 3A to 3D indicate an example of the path of external light irradiated from a point light source to the optical fiber 26. The position of the point light source shown in Fig. 3C is outside the arc of the optical fiber 26. The position of the point light source shown in Fig. 3D is inside the arc of the optical fiber 26.

[0029] The optical fiber 26 includes, for example, a light guide portion 261 . The light guide portion 261 extends in the direction in which the optical fiber 26 extends. Light guiding portion 261 includes ends 161PA and 161PB and a side surface 261SS.

[0030] The light guide section 261 is made of either or both of resin (plastic) and quartz glass.

[0031] For example, the light guiding section 261 is formed with a core and a clad separated like an optical fiber for communication. The core and clad are arranged concentrically with a common axis as the reference, as shown in the cross-sectional view. In a first example of the light guiding section 261, both the core and the clad are made of resin. In a second example of the light guiding section 261, the core is made of silica glass and the clad is made of resin. In a third example of the light guiding section 261, both the core and the clad are made of silica glass.

[0032] The first example can be applied if the distance from the detection position of the optical fiber to the end on the OE unit 25 side is relatively short. In this case, the optical fiber may be formed as a multimode step-index type by making the core diameter of the light-guiding section 261 relatively large.

[0033] Optical fiber 26 is formed to guide light taken in by side surface 261SS of light-guiding portion 261 in the extension direction and output it from, for example, end portions 161PA, 161PB of light-guiding portion 261. In this embodiment, for example, it is assumed that light output from one of end portions 161PA, 161PB is detected.

[0034] No shielding member is provided on the side surface 261SS of the light guiding section 261 of the optical fiber 26. At least in the portion where the optical fiber 26 is used as a sensor, no shielding member is provided on the side surface 261SS of the light guiding section 261. This shielding member is, for example, a light-blocking film or a light-blocking cable jacket. The optical fiber 26 takes in light outside the light guiding section 261 in the portion where no shielding member is provided.

[0035] For example, as shown in FIGS. 3A and 3B , when light from a light source (point light source) is irradiated onto optical fiber 26, the light is taken into light guide portion 261 of optical fiber 26. Depending on the angle of incidence on side surface 261SS of light guide portion 261, the light taken into light guide portion 261 is guided along light guide portion 261 in the extension direction of light guide portion 261, or passes through light guide portion 261 and is emitted to the outside from side surface 261SS of optical fiber 26. The above-mentioned angle of incidence when light can be guided in the extension direction of light guide portion 261 may be determined geometrically according to, for example, Snell's law, or may be determined by the characteristics of the surface treatment of side surface 261SS. The surface treatment of side surface 261SS may include a paint film or coating film with a low reflection coefficient, or may have the property of diffusing transmitted light. A larger angle of incidence allows light to be guided in the extension direction of light guide portion 261. Therefore, when the point light source is located outside the arc as shown in FIG. 3C, it is easier to capture light than when the point light source is located inside the arc as shown in FIG. 3D.

[0036] The optical fiber 26 thus formed is an example of an optical fiber formed to capture light caused by an arc flash occurring in its vicinity. By arranging the optical fiber 26 near a semiconductor switching element that forms the inverter 150 (power converter) or a conductor portion for passing current through the semiconductor switching element, the optical fiber 26 can capture light caused by an arc flash occurring in the semiconductor switching element or the conductor portion.

[0037] 4A, 4B, and 5, an example of the arrangement of the optical fiber 26 in the inverter 150 and the detection of an arc flash will be described. Fig. 4A is a cross-sectional view showing the arrangement of optical fibers 26 according to an embodiment. Fig. 4B is a plan view showing the arrangement of optical fibers according to an embodiment. Fig. 5 is a diagram for explaining protection control when an arc flash occurs according to an embodiment. Hatching of the cross section is omitted.

[0038] 4A and 4B show examples of the arrangement of semiconductor switching elements for each phase of inverter 150. Switches QU1 to QU4 for the U phase are arranged at an appropriate distance on the plane of a heat sink. Switches QU1 to QU4 are each configured as a module. The modules are electrically connected using a bus bar (not shown). For example, terminals provided on the top of switches QU1 to QU4 are connected by a bus bar. The same applies to switches QV1 to QV4 for the V phase and switches QW1 to QW4 for the W phase as to switches QU1 to QU4 for the U phase.

[0039] The optical fiber 26 is disposed near the positions where the above-mentioned modules are disposed. For example, the optical fiber 26 is held near the semiconductor switching elements of each phase so as to extend in an arc. For example, the optical fiber 26 may be gathered into a bundle by winding it multiple times, and the gathered portion may be disposed near each module. Instead of being gathered into a bundle, the optical fiber may be formed in a meandering arc, or may be formed into a U-shape by combining straight sections and this section.

[0040] The optical fiber 26 arranged as described above is positioned so that light generated in the event of a fault inside the inverter 150 can be captured by its side surface 261SS. When arranged in this manner, the light that the optical fiber 26 can capture includes light from the switches QU1 to QU4 of the inverter 150. The switches QU1 to QU4 of the inverter 150 are an example of semiconductor switching elements of a power converter. The V-phase and W-phase may be configured in the same manner as the U-phase. In this case, bundles of optical fibers 26 are provided separately for each phase, but each bundle is composed of a common optical fiber 26.

[0041] For example, the semiconductor switching elements of the power converter and the conductor portion of the power converter are arranged in a housing surrounded by a light-blocking member together with the optical fiber 26. For example, the housing 150B houses the area indicated by the reference numeral 150. More specifically, the switches QU1 to QU4 of the inverter 150 and the conductor portion of the inverter 150 are arranged together with the optical fiber 26 in a housing surrounded by a light-blocking member. In this case, it is desirable not to provide any light-blocking member between the switches QU1 to QU4 of the inverter 150 and the optical fiber 26, or between the conductor portion of the inverter 150 and the optical fiber 26. If the brightness around the optical fiber is relatively low under normal circumstances, more specifically, if there is no light caused by an arc flash or the like, the amount of light detected by the OE unit 25 will be significantly less than the amount of light when an arc flash occurs. This lack of influence from other light makes it easier to detect the occurrence of an arc flash.

[0042] The optical fiber 26 arranged as described above extends in an arc with a curvature larger than a predetermined curvature. The predetermined curvature is defined using, for example, the "minimum radius of curvature" in terms of the strength, transmission loss, etc. of the optical fiber 26.

[0043] The optical fiber 26 is preferably arranged so as to receive light from outside the arc. The relationship of this arrangement position may be defined as follows.

[0044] For example, when optical fiber 26 is arranged as shown in Figures 4A and 4B described above, the position of the arc and the positions of each semiconductor switching element such as switches QU1 to QU4 of inverter 150 are projected in the normal direction of plane F corresponding to the arc, and the images projected from each semiconductor switching element are arranged on plane F outside the arc. The above-described arrangement is merely an example of an arrangement that makes it easier to detect light caused by an arc flash, and is not limited to this and can be changed as appropriate.

[0045] With reference to FIG. 5, the protection control when an arc flash occurs according to the embodiment will be described. 5 is a diagram for explaining the protective control when an arc flash occurs according to the embodiment. For example, the protective control is performed when the following situations occur.

[0046] (1) Multiple semiconductor switching elements are cascaded for each phase. For example, as shown in Figure 1 above, in the U phase, switches QU1 and QU2 form a positive arm, and switches QU3 and QU4 form a negative arm. In the V phase, switches QV1 and QV2 form a positive arm, and switches QV3 and QV4 form a negative arm. In the W phase, switches QW1 and QW2 form a positive arm, and switches QW3 and QW4 form a negative arm. For example, if a short circuit occurs in one of the semiconductor switching elements of the U-phase switches QU1 to QU4, there is a risk that the positive and negative arms of the U-phase will be short-circuited, resulting in short-circuit damage to the U-phase. Below, we will explain the case where the U-phase is the fault phase.

[0047] (2) A short circuit fault in the U phase causes a fault current to flow through the positive and negative arms of the U phase, which may cause the U phase conductor (bus) or any of the switches QU1 to QU4 to melt, resulting in an arc flash. At this stage, the V and W phases are healthy phases. For example, until one of the fuses 150UP and 150UN shown in FIG. 2 responds to the fault current and stops it, the fault current continues to flow, potentially causing an arc flash in the U phase.

[0048] (3) In the above situation, if an arc flash occurs in the U phase, the amount of light taken in by the optical fiber 26 increases. As a result, the amount of light reaching the OE unit 25 via the optical fiber 26 also increases. The OE unit 25 detects this and outputs a gate block signal GB3.

[0049] (4) The GB unit 22 (FIG. 2) detects the gate block signal GB3 and limits the output of the gate pulses GP2 of all phases, thereby eliminating the gate pulses (GP3) supplied to the inverter 150.

[0050] (5) The semiconductor switching elements of all phases of the inverter 150 are controlled to be turned off. As a result, the current flowing through each semiconductor switching element is cut off by each semiconductor switching element not only in the faulty phase U but also in the healthy phases V and W.

[0051] It should be noted that the protection circuit may interrupt the fault current before the above state (5) is reached. In this case, the fault point has already been isolated, so the risk of the fault spreading is low. If the protection circuit responds and interrupts the fault current, the analysis unit 24 detects that the fuse has been blown from the state OC1 of the protection circuit and outputs a gate block signal GB2.

[0052] Even if the protection circuit of the faulty phase is unable to cut off the fault current due to a response delay or the like, if the state (5) above occurs, it is possible to stop the operation related to power conversion in the inverter 150. This prevents the semiconductor switching elements of at least healthy phases from being controlled to be on, thereby preventing abnormal current from flowing through the healthy phases.

[0053] According to the above procedure, the gate block signal GB3 is generated before the gate block signal GB2. The GB unit 22 detects the gate block signal GB2, but continues the output limitation of the gate pulses of all phases that was already set based on the gate block signal GB3.

[0054] In this embodiment, by using the gate block signal GB3, it is possible to limit the output of gate pulses of all phases at an earlier stage than when limiting the output of gate pulses of all phases is started in accordance with the state OC1 of the protection circuit.

[0055] According to the above embodiment, optical fiber 26 of control device 20 is configured to guide light taken in by side surface 261SS of extending light-guiding portion 261 in the extension direction and output the light from ends 261PA, 261PB of light-guiding portion 261. OE unit 25 detects light guided to either end 261PA, 261PB of light-guiding portion 261. GB unit 22 interrupts power conversion by inverter 150 when OE unit 25 detects light caused by an accident involving an arc flash. This makes it possible to simply prevent secondary failures caused by an accident that causes an arc flash.

[0056] Moreover, the power conversion device 1 including the inverter 150 includes the control device 20 and the inverter 150. The GB unit 22 may use the light detection result by the OE unit 25 to control the semiconductor switching elements related to the power conversion of the inverter 150 to an OFF state, thereby suspending the power conversion by the inverter 150.

[0057] (First Modification of the Embodiment) A first modified example will be described with reference to Figures 6A, 6B, and 7. In the above embodiment, a case has been described in which three phases are collectively monitored and controlled using one optical fiber 26. In this modified example, a case will be described in which three phases are collectively monitored and controlled using a pair of optical fibers 26A1 and 26A2.

[0058] FIG. 7 is a configuration diagram of a control device 20A according to a first modified example of the embodiment. The control device 20A includes a GB unit 22A (protection control unit) and an OE unit 25A (light detection unit) instead of the GB unit 22 and the OE unit 25 of the control device 20.

[0059] The GB unit 22A further acquires a gate block signal GB4 and uses it in the same way as the gate block signal GB3. For example, when any of the gate block signals GB1, GB2, GB3, and GB4 is in a significant state, the GB unit 22A limits the output of the gate pulse GP2, regardless of the signal state of the gate pulse GP1 supplied from the inverter control unit 21, so that no pulse is output.

[0060] The OE unit 25A corresponds to a configuration equipped with two systems of OE units 25. The OE unit 25A detects light guided from the first system of optical fiber 26A1, and outputs a gate pulse GP3 indicating significance when it detects light exceeding a predetermined light intensity. The OE unit 25B detects light guided from the second system of optical fiber 26A2, and outputs a gate pulse GP4 indicating significance when it detects light exceeding a predetermined light intensity.

[0061] Fig. 6A is a cross-sectional view showing the arrangement of optical fibers 26A1 and 26A2 in a first modified example of the embodiment, and Fig. 6B is a plan view showing the arrangement of optical fibers 26A1 and 26A2 in a first modified example of the embodiment. As shown in Figure 6A, optical fibers 26A1 and 26A2 are positioned so that their projection images onto plane FS overlap, offset from each other in the normal direction of plane FS. This allows optical fibers 26A1 and 26A2 to capture the light of the arc flash.

[0062] This not only achieves the same effects as the embodiment, but also makes it possible to make the arc flash detection system redundant with a simple configuration.

[0063] (Second Modification of the Embodiment) A second modified example will be described with reference to Figures 8A, 8B, and 9. In the above embodiment, a case has been described in which three phases are collectively monitored and controlled using one optical fiber 26. In this modified example, a case will be described in which three phases are monitored individually and controlled collectively using optical fibers 26B1, 26B2, and 26B3.

[0064] FIG. 9 is a configuration diagram of a control device 20B according to a second modified example of the embodiment. The control device 20B includes a GB unit 22B (protection control unit) and an OE unit 25B (light detection unit) instead of the GB unit 22 and the OE unit 25 of the control device 20.

[0065] The GB unit 22B further acquires gate block signals GB4 and GB5 and uses them in the same way as the gate block signal GB3. For example, when any of the gate block signals GB1, GB2, GB3, GB4, and GB5 is in a significant state, the GB unit 22B limits the output of the gate pulse GP2, regardless of the signal state of the gate pulse GP1 supplied from the inverter control unit 21, so that no pulse is output.

[0066] The OE unit 25B corresponds to a configuration including three OE units 25. The OE unit 25B detects light guided from a first optical fiber 26B1 corresponding to the U phase, and outputs a gate pulse GP3 indicating significance when it detects light exceeding a predetermined light intensity. The OE unit 25B detects light guided from a second optical fiber 26B2 corresponding to the V phase, and outputs a gate pulse GP4 indicating significance when it detects light exceeding a predetermined light intensity. The OE unit 25B detects light guided from a third optical fiber 26B3 corresponding to the W phase, and outputs a gate pulse GP5 indicating significance when it detects light exceeding a predetermined light intensity.

[0067] Fig. 8A is a cross-sectional view showing the arrangement of optical fibers 26B1, 26B2, and 26B3 in a second modified example of the embodiment, and Fig. 8B is a plan view showing the arrangement of optical fibers 26B1, 26B2, and 26B3 in a second modified example of the embodiment. As shown in Fig. 9, optical fibers 26B1, 26B2, and 26B3 are arranged in each phase, respectively, so that the optical fibers 26B1, 26B2, and 26B3 can capture the light of an arc flash that occurs in each phase.

[0068] This not only achieves the same effects as the embodiment, but also allows the arc flash detection system to be configured separately for each phase with a simple configuration.

[0069] According to at least one embodiment described above, the power conversion control device includes an optical fiber, a light detection unit, and a protection control unit. The optical fiber is configured to guide light taken in by a side surface of an extending light guide in the extension direction and output it from an end of the light guide. The light detection unit detects the light guided to the end of the light guide. The protection control unit uses a protection method that interrupts power conversion by a power converter related to the optical fiber when the light detection unit detects light caused by an accident involving an arc flash, allowing the power conversion control device to simply prevent the occurrence of secondary failures caused by an accident that causes an arc flash.

[0070] According to at least one embodiment, a power conversion apparatus includes a power conversion control device and a power converter. The protection control unit uses the light detection result to control semiconductor switching elements related to power conversion in the power converter to an off state, thereby suspending power conversion by the power converter related to the optical fiber. This allows the power conversion apparatus to easily prevent secondary failures caused by accidents that cause arc flashes.

[0071] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other.

[0072] According to the above embodiment, the optical fiber for supplying the gate pulse to the inverter 150 may have a light-shielding side surface. [Explanation of symbols]

[0073] 1 power conversion device, 20 control device (power conversion control device), 21 inverter control unit, 22 GB unit (protection control unit), 23 EO unit, 24 analysis unit, 25 OE unit (light detection unit), 26 optical fiber, 150 inverter

Claims

1. an optical fiber arranged near a plurality of semiconductor switches to be detected, the optical fiber being configured to take in light irradiated from around the optical fiber at a side surface of a light guide extending in the extension direction of the optical fiber, guide the taken-in light in the extension direction, and output it from an end of the light guide; a light detection unit that detects light guided to an end of the light guide unit; a protection control unit that interrupts power conversion by a power converter related to the optical fiber when light caused by an accident involving an arc flash is detected by the light detection unit; Equipped with A plurality of semiconductor switches are arranged along the extension direction of the optical fiber, and the plurality of semiconductor switches are included in the detection target. Power conversion control device.

2. The optical fiber is a portion of the side surface of the light guide portion where no shielding member is provided takes in light outside the light guide portion; The power conversion control device according to claim 1 .

3. The optical fiber is The light guiding unit is disposed at a position where light generated due to a fault in the power converter is irradiated, with a side surface of the light guiding unit facing the irradiation direction. The power conversion control device according to claim 1 .

4. The optical fiber is The extension is in an arc with a curvature greater than a predetermined curvature, a projection image of the position of the arc and the position of the semiconductor switching element of the power converter projected onto a plane corresponding to the arc in a normal direction of the plane, and an image projected from the semiconductor switching element is disposed outside the arc on the plane; The power conversion control device according to claim 3 .

5. The optical fiber is The power converter is formed to capture light caused by an arc flash generated from a semiconductor switching element of the power converter or a conductor portion for passing a current to the semiconductor switching element. The power conversion control device according to claim 1 .

6. The power conversion control device according to claim 4 or 5; a power converter associated with the optical fiber; Equipped with The protection control unit using the light detection result, a semiconductor switching element related to power conversion of the power converter is controlled to an off state, thereby suspending power conversion by the power converter. Power conversion device.

7. The protection control unit and interrupting the power conversion by the power converter based on the result of the light detection, with priority given to control of the on / off state of the semiconductor switching elements of the power converter, which is related to continuation of operation. The power conversion device according to claim 6.

8. a housing for accommodating a semiconductor switching element of the power converter, a conductor portion of the power converter, and the optical fiber; Equipped with The housing is made of a light-blocking material. The power conversion device according to claim 6.

9. A method for protecting a power conversion device, comprising: an optical fiber that is arranged in a state where it is extended near a plurality of semiconductor switches to be detected so that light caused by faults in the plurality of semiconductor switches reaches the periphery of a cross section that intersects with the extension direction, the optical fiber being configured to take in light irradiated from the periphery of the optical fiber to the periphery of the cross section at a side surface of a light guiding section that extends in the extension direction of the optical fiber, guide the taken-in light in the extension direction, and output it from an end of the light guiding section; a light detection unit that detects light guided to an end of the light guide unit; detecting light around the optical fiber using When the light detection unit detects light caused by an accident involving an arc flash, interrupting power conversion by a power converter related to the optical fiber; Protection methods including:

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