Semiconductor switch circuit and uninterruptible power supply

Abstract

To provide a semiconductor switch circuit capable of detecting thyristor arc loss even when multiple semiconductor switches are connected in parallel with each other, and an uninterruptible power system.SOLUTION: In an uninterruptible power system, a semiconductor switch circuit 10 includes: multiple semiconductor switch units 11 that are placed between an AC power source and a load, each of which includes a pair of thyristors connected in antiparallel to each other and that are connected in parallel with each other; and inductors 13 that are connected in series to each of multiple semiconductor switch units. The semiconductor switch circuit 10 detects thyristor arc loss such that the thyristor does not go from off-state to on-state based on the voltage across the ends of the inductors connected serially to the semiconductor switch unit.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a semiconductor switch circuit and an uninterruptible power supply, and more particularly to a semiconductor switch circuit and an uninterruptible power supply including a pair of thyristors connected in anti-parallel to each other. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an uninterruptible power supply device including a pair of thyristors connected in anti-parallel to each other is known (see, for example, Patent Document 1).

[0003] In the above-mentioned Patent Document 1, an uninterruptible power supply is provided between a commercial power source and a load. The uninterruptible power supply is also provided with an inverter and a storage battery connected in series to the inverter. The inverter and the load are also connected in parallel to each other. A semiconductor switch is also provided between the commercial power source and the inverter and the load. The semiconductor switch includes a pair of thyristors connected in anti-parallel to each other.

[0004] In addition, in the uninterruptible power supply disclosed in the above-mentioned Patent Document 1, when the commercial power supply is normal, a semiconductor switch is turned on. arc By switching on the inverter, AC power is supplied from the commercial power source to the load. When the commercial power source is normal, the power converted by the inverter is charged into the storage battery. In the event of a power outage, the semiconductor switch is turned off. arc Thus, AC power is supplied from the storage battery to the load via the inverter.

[0005] In addition, the uninterruptible power supply disclosed in the above Patent Document 1 is provided with a transformer for detecting the terminal voltage of the commercial power supply side of the semiconductor switch, and a transformer for detecting the terminal voltage of the load side of the semiconductor switch. arc When the deviation of the terminal voltages between the two ends of the semiconductor switch exceeds a certain set value, the thyristor in the semiconductor switch fails. arc (point arc In other words, the point at which the device does not go from an off state to an on state. arc It is determined that the person is in a state of being unable to

[0006] Although not explicitly stated in Patent Document 1, when a relatively large amount of power is supplied from a commercial power source to a load, a plurality of semiconductor switches are connected in parallel with each other, and power is supplied from the commercial power source to the load via the plurality of semiconductor switches connected in parallel with each other. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 10-126980 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in a conventional configuration in which power is supplied from a commercial power source to a load via multiple semiconductor switches connected in parallel, if one of the multiple semiconductor switches connected in parallel fails (the thyristor fails), arc ), power is supplied to the load via other semiconductor switches. arc The semiconductor switch fails based on the deviation of the terminal voltages in the arc When judging whether a thyristor is broken or not, the voltage across other semiconductor switches that are not broken (the forward voltage of the thyristor) is detected, so the failure of the thyristor can be judged. arc However, there is a problem that it cannot be detected.

[0009] The present invention has been made to solve the above-mentioned problems, and one object of the present invention is to prevent a thyristor failure even when a plurality of semiconductor switch sections are connected in parallel with each other. arc The present invention provides a semiconductor switch circuit and an uninterruptible power supply capable of detecting a voltage difference between the power supply and the semiconductor switch circuit. [Means for solving the problem]

[0010] In order to achieve the above object, a semiconductor switch circuit according to a first aspect of the present invention is provided between an AC power source and a load, each of the thyristors being connected in anti-parallel to each other, and the semiconductor switch circuit includes a plurality of semiconductor switch sections connected in parallel to each other, and an inductor connected in series to each of the plurality of semiconductor switch sections, and based on a voltage across the inductor connected in series to the semiconductor switch section, The signal , If it is above a certain threshold, A failure in which the thyristor does not change from the OFF state to the ON state. arc The device is configured to detect

[0011] In the semiconductor switch circuit according to the first aspect of the present invention, as described above, a failure occurs in which the thyristor does not change from an OFF state to an ON state based on the voltage across the inductor connected in series to the semiconductor switch section. arc This is configured to detect a failure in which the thyristor included in the semiconductor switch does not change from an off state to an on state. arc If this happens, you will lose your arc No current flows through the damaged thyristor, so no failure occurs. arc The voltage across the inductor connected to the semiconductor switch section including the failed thyristor becomes approximately zero, and the current through the thyristor is diverted to other thyristors in parallel, so the voltage across the inductor connected to the semiconductor switch sections other than the failed semiconductor switch section rises. As a result, even if multiple semiconductor switch sections are connected in parallel, the failure of a thyristor arc can be detected.

[0012] A semiconductor switch circuit according to a second aspect of the present invention is provided between an AC power source and a load, each including a pair of thyristors connected in anti-parallel to each other, and comprising a plurality of semiconductor switch units connected in parallel to each other, and an inductor connected in series to each of the plurality of semiconductor switch units, and is configured to detect a misarc in which the thyristor does not change from an off state to an on state, based on a voltage across the inductor connected in series to the semiconductor switch units, and further comprises a voltage detection unit that detects the voltage across the inductor, and is configured to detect a misarc of the thyristor when a signal based on the voltage across the inductor detected by the voltage detection unit is equal to or greater than a predetermined threshold. In the semiconductor switch circuit according to the second aspect of the present invention, The inductor further includes a voltage detection unit that detects a voltage across the inductor, and when a signal based on the voltage across the inductor detected by the voltage detection unit is equal to or greater than a predetermined threshold value, a failure of the thyristor is detected. arc The device is configured to detect This , the thyristor fails. arcWhen a thyristor is turned on, the voltage across the other inductors rises. Therefore, by detecting the voltage across the inductor that is equal to or higher than the threshold value using a voltage detection unit, it is possible to easily detect the failure of the thyristor. arc can be detected.

[0013] In the semiconductor switch circuit according to the second aspect, Preferably, the predetermined threshold value includes a first threshold value set based on a shared voltage of a plurality of semiconductor switch units, and when a signal based on a voltage across an inductor is equal to or greater than the first threshold value, a failure of the thyristor is detected. arc Here, a shared voltage corresponding to an induced voltage generated in an inductor connected to each of the multiple semiconductor switch units is applied to each of the multiple semiconductor switch units. When it is detected that an induced voltage in an inductor included in the multiple semiconductor switch units exceeds a voltage rise value of an assumed current sharing imbalance of the multiple semiconductor switch units and rises deviating from a normal current range of the thyristor, the thyristor is judged to have failed. arc By setting a predetermined threshold value (first threshold value) so that it is determined that a thyristor has failed, it is possible to easily determine whether a thyristor has failed. arc can be detected.

[0014] the above According to the second aspect In the semiconductor switch circuit, preferably, a voltage detection unit is provided for each of the plurality of semiconductor switch units. With this configuration, a failure of a thyristor is detected for each of the plurality of semiconductor switch units. arc It is possible to detect whether or not the

[0015] the above According to the second aspect In the semiconductor switch circuit, the predetermined threshold value preferably includes a second threshold value set based on a rated voltage of the thyristor, and the voltage detection unit detects a difference between both ends of each of the inductors connected in series to each of the plurality of semiconductor switch units, and detects a failure of the thyristor when a signal based on the difference between both ends of each of the inductors is equal to or greater than the second threshold value. arc With this configuration, the failure of the plurality of semiconductor switch units can be detected by comparing the difference between the voltages across the inductors with a predetermined threshold value (second threshold value). arcTherefore, unlike a case where the voltages across each of the inductors are detected separately and compared with a threshold, a common configuration can be used for comparing the detected signal with the threshold. As a result, by comparing a signal based on the difference between the voltages across each of the inductors with the second threshold, it is possible to detect failures in the multiple semiconductor switch units connected in parallel. arc Therefore, it is possible to suppress the circuit configuration from becoming complicated in order to detect the above.

[0016] In this case, preferably, the plurality of semiconductor switch sections include a first semiconductor switch section and a second semiconductor switch section connected in parallel with each other, the inductor includes a first inductor connected in series to the first semiconductor switch section and a second inductor connected in series to the second semiconductor switch section, and the first inductor and the second inductor have substantially equal inductances. With this configuration, since the inductances of the first inductor and the second inductor are substantially equal, when the thyristors of the semiconductor switch sections are normal, the voltages across the first inductor and the voltages across the second inductor can be substantially equal. Therefore, the difference between the voltages across the first inductor and the voltages across the second inductor can be made substantially zero. On the other hand, when the thyristors of the semiconductor switch sections fail, arc In this case, the difference in the voltages across the first inductor and the second inductor is not 0. Therefore, by determining whether the difference in the voltages across the first inductor and the second inductor is substantially 0, the failure of the thyristor in the semiconductor switch unit can be prevented. arc can be more easily detected. In this specification, "substantially equal" is described as a broad concept including not only perfectly equal magnitudes but also minute differences (errors) due to individual differences and noise, etc. Similarly, "substantially 0" is described as a broad concept including minute values ​​due to individual differences and noise, etc.

[0017] In this case, the voltage detection unit is preferably configured to detect a difference between the voltages across the first inductor and the second inductor when both the first semiconductor switch unit and the second semiconductor switch unit are in an ON state. Here, even when the first semiconductor switch unit and the second semiconductor switch unit are controlled to turn on the switches, a failure may occur. arc Therefore, if either the thyristor in the first semiconductor switch section or the second semiconductor switch section fails, arc When the thyristor is in a normal state, the difference in the voltages across the first inductor and the second inductor when the switch is on is different from when the thyristor is normal. Therefore, when both the first semiconductor switch unit and the second semiconductor switch unit are on, the difference in the voltages across the first inductor and the second inductor is detected to determine whether the thyristor has failed. arc can be detected with high accuracy.

[0018] In the semiconductor switch circuit in which the semiconductor switch section includes a first semiconductor switch section and a second semiconductor switch section, the voltage detection section is preferably configured to detect a difference between the voltages across the first inductor and the second inductor by connecting the first inductor and the second inductor to have opposite polarities. With this configuration, the magnitude of the difference between the voltages across the first inductor and the second inductor can be detected without separately detecting the voltages across the first inductor and the voltages across the second inductor by connecting the first inductor and the second inductor to have opposite polarities. Therefore, the difference between the voltages across the first inductor and the second inductor can be easily detected compared to a case in which a configuration is provided in which the voltages across the first inductor and the voltages across the second inductor are detected separately.

[0019] In this case, preferably, the voltage detection unit includes a transformer, the transformer including a primary winding having two coils and a secondary winding having one coil, and the first inductor and the second inductor are connected to each of the two coils of the primary winding so that the first inductor and the second inductor are respectively in opposite polarity, thereby detecting the difference in voltage between both ends of the first inductor and the second inductor. With this configuration, the difference in voltage between both ends of the first inductor and the second inductor can be obtained by connecting the primary winding in opposite polarity, and the difference in voltage between both ends of the first inductor and the second inductor can be transformed and detected by the output from the secondary winding. Therefore, a detection signal (detection value) obtained by amplifying the difference in voltage between both ends of the first inductor and the second inductor can be obtained by the transformer. As a result, the amplified signal is compared with a predetermined threshold value (second threshold value) to detect the failure of the thyristor. arc Since the failure of the thyristor can be detected, arc In addition, by using a transformer, the primary winding and the secondary winding are insulated, so the inductor side where the voltage is detected and the loss side are arc This makes it possible to insulate the inductor side (semiconductor switch unit side) from affecting the arithmetic circuit side for detecting the abnormality.

[0020] Above No. 1 and the second In the semiconductor switch circuit according to the above aspect, preferably, at least one of the thyristors included in the plurality of semiconductor switch units fails. arc If the state is arc In this way, the failure detection device is configured to output a signal indicating that the failure is in the failure state. arc Based on the signal indicating the state, the device in which the semiconductor switch circuit is installed can be stopped, so that failure arc In this case, it is possible to inhibit the device from being continuously used while the thyristor is in the above-mentioned state.

[0021] Above No. 1 and the second In the semiconductor switch circuit according to the above aspect, the inductor connected in series to each of the plurality of semiconductor switch sections is preferably configured to average the current flowing through each of the semiconductor switch sections. With this configuration, it is possible to prevent the semiconductor switch section (thyristor) from failing due to biased current (energizing current) flowing through the semiconductor switch section.

[0022] The first aspect of this invention 3 The uninterruptible power supply according to the above aspect includes a converter unit that converts AC power from an AC power source into DC power, an inverter unit that converts the DC power from the converter unit into AC power and supplies the converted AC power to a load, a bypass circuit unit that is connected in parallel to the converter unit and the inverter unit between the AC power source and the load and supplies the AC power from the AC power source to the load, and a semiconductor switch circuit provided in the bypass circuit unit, each of the semiconductor switch circuits including a pair of thyristors connected in anti-parallel to each other, a plurality of semiconductor switch units connected in parallel to each other, and an inductor connected in series to each of the plurality of semiconductor switch units, and a switching circuit that switches between the semiconductor switch units based on a voltage across the inductor connected in series to the semiconductor switch units. The signal , If it is above a certain threshold, A failure in which the thyristor does not change from the OFF state to the ON state. arc The device is configured to detect

[0023] The first aspect of this invention 3 In the uninterruptible power supply according to the above aspect, as described above, a failure occurs in which the thyristor does not change from an off state to an on state based on the voltage across the inductor connected in series to the semiconductor switch unit. arc This is configured to detect a failure in which the thyristor included in the semiconductor switch does not change from an off state to an on state. arc If this happens, you will lose your arc No current flows through the damaged thyristor, so no failure occurs. arcThe voltage across the inductor connected to the semiconductor switch unit containing the failed thyristor becomes approximately zero, and the current through the failed thyristor is diverted to other thyristors in parallel, so the voltage across the inductor connected to the semiconductor switch units other than the failed semiconductor switch unit rises. As a result, even if multiple semiconductor switch units are connected in parallel, the failure of a thyristor arc It is possible to provide an uninterruptible power supply capable of detecting the above. Effect of the Invention

[0024] According to the present invention, as described above, even when the semiconductor switch sections are connected in parallel with each other, the failure of the thyristor is prevented. arc can be detected. [Brief description of the drawings]

[0025] [Figure 1] 1 is a block diagram showing the overall configuration of an uninterruptible power supply according to a first embodiment. [Diagram 2] 1 is a block diagram showing a configuration of a semiconductor switch circuit (for one phase) of an uninterruptible power supply according to a first embodiment. FIG. [Diagram 3] 1 is a circuit diagram showing a configuration of a semiconductor switch unit of an uninterruptible power supply according to a first embodiment. [Figure 4] 1 is a block diagram showing a configuration of a semiconductor switch circuit (for three phases) of an uninterruptible power supply according to a first embodiment. FIG. [Diagram 5] FIG. 11 is a block diagram showing the overall configuration of an uninterruptible power supply according to a second embodiment. [Figure 6] FIG. 11 is a block diagram showing the configuration of a semiconductor switch circuit of an uninterruptible power supply according to a second embodiment. [Figure 7] FIG. 13 is a block diagram showing the overall configuration of an uninterruptible power supply system according to a modified example. [Figure 8] 13A and 13B are diagrams for explaining the configuration of a transformer according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0027] [First embodiment] The configuration of an uninterruptible power supply 100 according to a first embodiment will be described with reference to FIGS. 1 to 4.

[0028] (Uninterruptible power supply configuration) As shown in Fig. 1, the uninterruptible power supply 100 includes a converter unit 1. The converter unit 1 is configured to convert AC power from an AC power source 200a into DC power. In addition, a mechanical switch unit 2a is provided between the AC power source 200a and the converter unit 1.

[0029] The uninterruptible power supply 100 also includes an inverter unit 3. The inverter unit 3 is configured to convert the DC power from the converter unit 1 into AC power and supply the converted AC power to the load 210. A mechanical switch unit 2b is provided between the inverter unit 3 and the load 210.

[0030] The uninterruptible power supply 100 also includes a DC power supply 4. The DC power supply 4 is connected between the converter unit 1 and the inverter unit 3, and is configured to supply power to the load 210 when an abnormality occurs in the AC power supply 200a. Specifically, DC power from the DC power supply 4 is converted to AC power by the inverter unit 3 and supplied to the load 210. A mechanical switch unit 2c is also provided between the DC power supply 4 and the converter unit 1 and inverter unit 3.

[0031] The uninterruptible power supply 100 also includes a bypass circuit unit 5. The bypass circuit unit 5 is connected in parallel to the converter unit 1 and the inverter unit 2 between the AC power supply 200b and the load 210, and is configured to supply AC power from the AC power supply 200b to the load 210.

[0032] The uninterruptible power supply 100 also includes a semiconductor switch circuit 10. The semiconductor switch circuit 10 is provided in the bypass circuit section 5. A detailed configuration of the semiconductor switch circuit 10 will be described later. The bypass circuit section 5 also includes a mechanical switch section 6 that is arranged in parallel with the semiconductor switch circuit 10. During bypass power supply (power is being supplied from the AC power supply 200b to the load 210 via the bypass circuit section 5), the switch section 6 mainly closes the switch section 6 to supply power. The semiconductor switch circuit 10 is used auxiliary when the switch section 6 is opened and closed (it is turned on for a predetermined time).

[0033] The uninterruptible power supply 100 also includes a control unit 7. The control unit 7 is configured to control the entire uninterruptible power supply 100. For example, the control unit 7 controls the driving of the converter unit 1 and the inverter unit 3. The control unit 7 also controls the driving (on / off) of the semiconductor switch circuit 10 and the switch unit 6.

[0034] The uninterruptible power supply 100 normally supplies power from the AC power supply 200b to the load 210 via the bypass circuit unit 5. If an abnormality occurs in the bypass circuit unit 5 during power supply via the bypass circuit unit 5, power is supplied to the load 210 from the inverter unit 3. Note that while power is normally supplied to the load 210 from the inverter unit 3, power may also be supplied to the load 210 via the bypass circuit unit 5 when a failure occurs in the inverter unit 3 or the like. The uninterruptible power supply 100 also performs an active filter operation that absorbs harmonic currents and reactive power generated from the load 210.

[0035] (Detailed configuration of semiconductor switch circuit) A detailed configuration of the semiconductor switch circuit 10 will be described with reference to Fig. 2 to Fig. 4. Although Fig. 2 shows the semiconductor switch circuit 10 for one phase, in reality, as shown in Fig. 4, the semiconductor switch circuit 10 is provided for three phases.

[0036] 3, in the first embodiment, the semiconductor switch circuit 10 includes a plurality of semiconductor switch sections 11 (two for one phase in the first embodiment). The plurality of semiconductor switch sections 11 are provided between an AC power supply 200b and a load 210. Each of the plurality of semiconductor switch sections 11 includes a pair of thyristors 12 connected in anti-parallel to each other. The thyristor 12 is a semiconductor element having three terminals that can establish electrical continuity between the anode and the cathode by passing a gate current from the gate to the cathode.

[0037] The semiconductor switch circuit 10 also includes an inductor 13 (inductors 13a and 13b) connected in series to each of the multiple semiconductor switch sections 11 (semiconductor switch sections 11a and 11b). The inductor 13 is a passive element capable of storing power in a magnetic field formed by a current flowing through the inductor 13. The inductor 13 is formed of, for example, a coil. The inductor 13 is selected to have an inductance L capable of generating an induced voltage at a level that allows the individual differences in the forward voltage of the thyristor 12 to be negligible.

[0038] In the first embodiment, the inductor 13 (inductors 13a and 13b) connected in series to each of the semiconductor switch units 11 (semiconductor switch units 11a and 11b) is configured to average the current flowing through each of the semiconductor switch units 11. Since the thyristors 12 included in the semiconductor switch unit 11 have individual differences (differences in forward voltage), there is a variation between the current (I1) flowing through the semiconductor switch unit 11a and the current (I2) flowing through the semiconductor switch unit 11b. When an AC current flows through the inductor 13, a magnetic field generated by the AC current flowing through the inductor 13 crosses the other windings, and an induced voltage (=ωLI) is generated. The induced voltage acts to prevent a change in the AC current flowing through the inductor 13. The induced voltage is configured to be higher than the forward voltage of the thyristor 12. As a result, the inductor 13 (inductors 13a and 13b) averages the current flowing through each of the semiconductor switch units 11a and 11b. Moreover, since semiconductor switch portion 11a and semiconductor switch portion 11b are connected in parallel, a current I0 (=I1+I2) flows out from the plurality of semiconductor switch portions 11.

[0039] In the first embodiment, as shown in FIG. 2, the semiconductor switch circuit 10 detects a failure state in which the thyristor 12 does not change from an OFF state to an ON state based on the voltage across the inductor 13 connected in series to the semiconductor switch section 11. arc Specifically, the semiconductor switch circuit 10 is configured to detect the failure of the thyristor 12. arc A calculation circuit 14 is provided to detect the above.

[0040] Specifically, the semiconductor switch circuit 10 (arithmetic circuit 14) includes a transformer 15 that detects the voltage across the inductor 13. Specifically, the primary side of the transformer 15 is connected to both ends of the inductor 13. The secondary side of the transformer 15 is connected to a rectifier 16 (diode). The rectifier 16 is configured of a full-wave rectifier circuit. An LPF (Low-pass filter) 17 is connected to the output side of the rectifier 16. The LPF 17 smoothes the pulsation of the voltage output from the rectifier 16. A comparator 18 is connected to the output side of the LPF 17. The use of the transformer 15 insulates the voltage detection point (inductor 13 side) from the arithmetic circuit 14. If the accuracy of the voltage detection can be ensured, the voltage detection point does not need to be insulated from the arithmetic circuit 14 (the transformer 15 may be removed). The transformer 15 is an example of a "voltage detection unit" in the claims.

[0041] In the first embodiment, the semiconductor switch circuit 10 detects a failure of the thyristor 12 when a signal based on the voltage across the inductor 13 detected by the transformer 15 is equal to or greater than a predetermined threshold value (first threshold value). arc Specifically, the voltage across inductor 13 detected by transformer 15 is input to comparator 18 via rectifier 16 and LPF 17. Then, comparator 18 compares the input signal (a signal based on the voltage across inductor 13) with a first threshold value. Then, comparator 18 outputs an H-level signal when the input signal is equal to or greater than the first threshold value. In other words, based on the output of an H-level signal from comparator 18, it is determined that thyristor 12 has failed. arc is detected.

[0042] In detail, an induced voltage V1 (=ωLI1) corresponding to the current (I1) flowing through the semiconductor switch unit 11a is generated in the inductor 13a. Also, an induced voltage V2 (=ωLI2) corresponding to the current (I2) flowing through the semiconductor switch unit 11b is generated in the inductor 13b. Then, when the thyristor 12 fails, arcWhen the switch 11a is turned off, the current stops flowing, and an induced voltage V1+V2 (=ωL(I1+I2)) of the current (I1) that was flowing through the semiconductor switch unit 11a is generated in the inductor 13b. The transformer 15 detects this voltage, and the comparator 18 outputs an H-level signal.

[0043] In the first embodiment, the predetermined threshold (first threshold) is set based on the voltages shared by the plurality of semiconductor switch units 11. arc When the inductors 13a and 13b are not turned on, voltages (shared voltages) corresponding to the shared currents of the semiconductor switch units 11a and 11b are generated across the inductors 13a and 13b, respectively. For example, the first threshold value is 110% of the shared voltages.

[0044] In the first embodiment, a transformer 15 is provided for each semiconductor switch unit 11. That is, in each phase, one transformer 15 is provided for each of the two semiconductor switch units 11a and 11b (two in total). That is, a voltage is detected for each semiconductor switch unit 11. A rectifier 16, an LPF 17, and a comparator 18 are also provided for each semiconductor switch unit 11.

[0045] In the first embodiment, the semiconductor switch circuit 10 is configured such that at least one of the thyristors 12 included in the plurality of semiconductor switch units 11 fails. arc If the state is arc Specifically, an OR circuit 19 is provided on the output side of two comparators 18 provided for each semiconductor switch unit 11. As a result, when any of the thyristors 12 included in the semiconductor switch unit 11a and the semiconductor switch unit 11b fails, an OR circuit 19 is provided on the output side of the comparator 18. arc Even if one of the thyristors 12 included in the semiconductor switch circuit 10 fails, an H-level signal is output from the OR circuit 19. arc Even if you do, you will lose arc It becomes possible to detect.

[0046] As described above, FIG. 2 shows the semiconductor switch section 11 of one phase, but as shown in FIG. 4, in reality, a plurality of semiconductor switch sections 11 are provided for each phase. Specifically, the semiconductor switch circuit 10 includes a U-phase semiconductor switch section 11a (#1 U-phase in FIG. 4) and a semiconductor switch section 11b (#2 U-phase), a V-phase semiconductor switch section 11a (#1 V-phase) and a semiconductor switch section 11b (#2 V-phase), and a W-phase semiconductor switch section 11a (#1 W-phase) and a semiconductor switch section 11b (#2 W-phase). One OR circuit 19 is provided in common for all the semiconductor switch sections 11. As a result, when any of the thyristors 12 included in the plurality of semiconductor switch sections 11 fails, the OR circuit 19 is automatically set to the ON state. arc Even if you do, you will lose arc It becomes possible to detect.

[0047] (Effects of the first embodiment) In the first embodiment, the following effects can be obtained.

[0048] In the first embodiment, as described above, the semiconductor switch circuit 10 detects a failure in which the thyristor 12 does not change from an OFF state to an ON state based on the voltage across the inductor 13 connected in series to the semiconductor switch section 11. arc This detects a failure in which the thyristor 12 included in the semiconductor switch unit 11 does not change from an off state to an on state. arc If this happens, you will lose your arc Since no current flows through the failed thyristor 12, and the current flowing through the failed thyristor 12 is diverted to the other thyristors 12 in parallel, the voltage across the inductor 13 connected to the semiconductor switch unit 11 other than the failed semiconductor switch unit 11 rises. As a result, even when multiple semiconductor switch units 11 are connected in parallel with each other, the failure of a thyristor 12 arc can be detected.

[0049] In the first embodiment, as described above, the semiconductor switch circuit 10 detects a failure of the thyristor 12 when a signal based on the voltage across the inductor 13 detected by the transformer 15 is equal to or greater than a predetermined threshold value (first threshold value). arc This detects the failure of the thyristor 12. arc When the thyristor 12 is turned off, the voltage across the other inductor 13 rises. Therefore, the voltage across the inductor 13 that is equal to or higher than the first threshold value can be detected by the transformer 15 to easily detect the failure of the thyristor 12. arc can be detected.

[0050] In the first embodiment, as described above, the predetermined threshold value includes a first threshold value set based on the voltages shared by the multiple semiconductor switch units 11, and when the signal based on the voltage across the inductor 13 is equal to or greater than the first threshold value, a failure of the thyristor 12 is detected. arc Here, a voltage is applied to each of the plurality of semiconductor switch sections 11 according to an induced voltage generated in the inductor 13 connected thereto. arc When a voltage that deviates from the normal state is detected, thyristor 12 fails. arc By setting a predetermined threshold value (first threshold value) so that it is determined that the thyristor 12 has failed, it is possible to easily determine whether the thyristor 12 has failed. arc can be detected.

[0051] In the first embodiment, as described above, the transformer 15 is provided for each of the plurality of semiconductor switch units 11. This allows the thyristor 12 to be prevented from failing for each of the plurality of semiconductor switch units 11. arc It is possible to detect whether or not the

[0052] In the first embodiment, as described above, the semiconductor switch circuit 10 is configured to operate when at least one of the thyristors 12 included in the plurality of semiconductor switch units 11 fails. arc If the state is arc The device is configured to output a signal indicating that the device is in a failure state. arc Based on the signal indicating the above state, the uninterruptible power supply 100 in which the semiconductor switch circuit 10 is provided can be stopped. arc In this case, it is possible to prevent the uninterruptible power supply 100 from being used continuously while the thyristor 12 in this state is included.

[0053] In the first embodiment, as described above, the inductor 13 connected in series to each of the semiconductor switch units 11 is configured to average the current flowing through each of the semiconductor switch units 11. This makes it possible to prevent the semiconductor switch unit 11 (thyristor 12) from failing due to bias in the current (energization current) flowing through the semiconductor switch unit 11.

[0054] [Second embodiment] Next, an uninterruptible power supply 400 according to a second embodiment will be described with reference to Figures 5 and 6. Unlike the first embodiment in which a transformer 15 is provided for each of two semiconductor switch units 11, the second embodiment provides one common transformer 415 for two semiconductor switch units 411. The transformer 415 is an example of a "voltage detection unit" in the claims.

[0055] 5, an uninterruptible power supply 400 according to the second embodiment includes a semiconductor switch circuit 410. The semiconductor switch circuit 410 is used auxiliary when opening and closing the switch section 6, similar to the semiconductor switch circuit 10 according to the first embodiment.

[0056] As shown in FIG. 6, the semiconductor switch circuit 410 includes a plurality of (two) semiconductor switch units 411, similar to the first embodiment. Specifically, the semiconductor switch unit 411 includes a semiconductor switch unit 411a and a semiconductor switch unit 411b that are connected in parallel to each other. Also, each of the semiconductor switch units 411 (the semiconductor switch unit 411a and the semiconductor switch unit 411b) includes a pair of thyristors 12 that are connected in anti-parallel to each other, similar to the first embodiment. The semiconductor switch unit 411a is an example of a "first semiconductor switch unit" in the claims. Also, the semiconductor switch unit 411b is an example of a "second semiconductor switch unit" in the claims.

[0057] Similarly to the first embodiment, the semiconductor switch circuit 410 includes an inductor 413 connected in series to each of the semiconductor switch units 411. In the second embodiment, the inductor 413 includes an inductor 413a connected in series to the load 210 side of the semiconductor switch unit 411a, and an inductor 413b connected in series to the load 210 side of the semiconductor switch unit 411b. The inductor 413a and the inductor 413b may be connected in series to the AC power source 200b side of the semiconductor switch unit 411a and the semiconductor switch unit 411b, respectively. The inductor 413a is an example of a "first inductor" in the claims. The inductor 413b is an example of a "second inductor" in the claims.

[0058] In the second embodiment, the inductors 413a and 413b have substantially equal inductances L (impedances). As in the first embodiment, the inductors 413a and 413b have an inductance L that can generate an induced voltage such that the individual difference in the forward voltage of the thyristor 12 can be ignored. For example, the inductance L of the inductors 413a and 413b generates an induced voltage that is five times the forward voltage generated in the thyristor 12. Therefore, as in the first embodiment, the inductors 413a and 413b average (balance) the currents flowing through the semiconductor switch unit 411a and the semiconductor switch unit 411b. That is, the current I1 flowing through the semiconductor switch unit 411a and the inductor 413a and the current I2 flowing through the semiconductor switch unit 411b and the inductor 413b are substantially equal in magnitude. Therefore, the induced voltage V1 generated in the inductor 413a and the induced voltage V2 generated in the inductor 413b are substantially equal in magnitude. In other words, the voltages across the inductors 413a and 413b are approximately equal to each other.

[0059] Here, in the second embodiment, unlike the first embodiment, the semiconductor switch circuit 410 determines whether the thyristor 12 is turned off based on the difference between the voltages across the inductor 413a and the inductor 413b. arc If all the thyristors 12 are normal, the voltages across the inductors 413a and 413b are approximately equal. Therefore, the difference between the voltages across the inductors 413a and 413b is approximately zero. On the other hand, if any one of the thyristors 12 is abnormal (failed), arc ), the difference between the voltages across the inductors 413a and 413b is not 0. Therefore, in the second embodiment, the semiconductor switch circuit 410 detects the failure of the thyristor 12 when the signal based on the difference between the voltages across the inductors 413a and 413b is equal to or greater than a predetermined threshold (second threshold). arc The device is configured to detect

[0060] Specifically, the semiconductor switch circuit 410 includes a thyristor 12 failure detection circuit. arc In the second embodiment, the semiconductor switch circuit 410 (arithmetic circuit 414) includes a transformer 415 that detects a difference between the voltages across the inductors 413a and 413b. The transformer 415 includes a primary winding 415a having two coils and a secondary winding 415b having one coil. The transformer 415 is configured to detect a difference between the voltages across the inductors 413a and 413b by connecting the inductors 413a and 413b to the two coils of the primary winding 415a so that the polarities of the inductors 413a and 413b are opposite to each other.

[0061] For example, primary winding 415a of transformer 415 includes two coils with different polarities (winding directions). Inductor 413a and inductor 413b are connected in parallel to each of the two coils with different polarities. That is, induced voltage V1 of inductor 413a and induced voltage V2 of inductor 413a are applied to primary winding 415a of transformer 415 so as to have opposite polarities. Inductive voltage V1 and induced voltage V2 applied so as to have opposite polarities cancel each other out, so that a voltage that is the difference between the voltages across inductor 413a and inductor 413b is applied to primary winding 415a of transformer 415. Then, transformer 415 outputs a signal obtained by amplifying (transforming) the difference between the voltages across inductor 413a and inductor 413b from secondary winding 415b.

[0062] The arithmetic circuit 414 also includes a rectifier 416 (diode), an LPF 417, and a comparator 418. The rectifier 416 (diode), the LPF 417, and the comparator 418 operate in the same manner as the rectifier 16, the LPF 17, and the comparator 18 according to the first embodiment. Specifically, the secondary winding 415b of the transformer 415 is connected to the rectifier 416 (diode). A signal from the secondary winding 415b is rectified by the rectifier 416 and smoothed by the LPF 417. The comparator 418 is connected to the output side of the LPF 417. The comparator 418 compares the signal input from the LPF 417 (a signal based on the difference between the voltages across the inductors 413a and 413b) with a predetermined threshold (second threshold). When the input signal is equal to or greater than the second threshold, the thyristor 12 is turned off. arc is detected.

[0063] In the second embodiment, the predetermined threshold (second threshold) is set based on the rated voltage of the thyristor 12. For example, the second threshold is set to a value corresponding to 25% of the rated voltage of the thyristor 12. In other words, when the difference between the voltages across the inductors 413a and 413b becomes equal to or greater than 25% of the rated voltage of the thyristor 12, the comparator 418 detects that the thyristor 12 has failed. arc The second threshold is set so that a signal indicating that the first threshold has been detected is output.

[0064] In the second embodiment, the transformer 415 is configured to detect the difference between the voltages across the inductors 413a and 413b when both the semiconductor switch units 411a and 411b are in an on state. That is, the control unit 7 turns on the semiconductor switch units 411a and 411b (turns on the thyristor 12). arc When a command to turn on the thyristor is output, the thyristor 12 that detects the difference in voltage between both ends fails. arc Inspection is carried out.

[0065] Other configurations of the uninterruptible power supply 400 are similar to those of the uninterruptible power supply 100 according to the first embodiment.

[0066] (Effects of the second embodiment) In the second embodiment, the following effects can be obtained.

[0067] In the second embodiment, as described above, the predetermined threshold value includes a second threshold value set based on the rated voltage of the thyristor 12, and the transformer 415 (voltage detection unit) detects a difference between the voltages across each of the inductors 413 connected in series to each of the multiple semiconductor switch units 411, and detects a failure of the thyristor 12 when a signal based on the difference between the voltages across each of the inductors 413 is equal to or greater than the second threshold value. arc With this configuration, the failure of the plurality of semiconductor switch units 411 can be detected by comparing the difference between the voltages across each of the inductors 413 with a predetermined threshold value (second threshold value). arc Therefore, unlike the case where the voltages across each of the inductors 413 are detected separately and compared with the threshold, the configuration for comparing the detected signal with the threshold can be a common configuration. As a result, by comparing the signal based on the difference between the voltages across each of the inductors 413 with the second threshold, the failure of the multiple semiconductor switch units 411 connected in parallel can be detected. arc Therefore, it is possible to suppress the circuit configuration from becoming complicated in order to detect the above.

[0068] In the second embodiment, as described above, the semiconductor switch units 411 include the semiconductor switch unit 411a (first semiconductor switch unit) and the semiconductor switch unit 411b (second semiconductor switch unit) connected in parallel to each other, the inductor 413 includes the inductor 413a (first inductor) connected in series to the semiconductor switch unit 411a and the inductor 413b (second inductor) connected in series to the semiconductor switch unit 411b, and the inductors 413a and 413b have substantially equal inductances L. With this configuration, the inductors 413a and 413b have substantially equal inductances L. Therefore, when the thyristor 12 of the semiconductor switch unit 411 is normal, the voltage across the inductor 413a and the voltage across the inductor 413b can be substantially equal. Therefore, the difference between the voltage across the inductor 413a and the voltage across the inductor 413b can be made substantially zero. On the other hand, when the thyristor 12 of the semiconductor switch unit 411 fails, arc In this case, the difference in the voltages across the inductors 413a and 413b is not 0. Therefore, by determining whether the difference in the voltages across the inductors 413a and 413b is approximately 0, the failure of the thyristor 12 in the semiconductor switch unit 411 can be detected. arc can be more easily detected.

[0069] In the second embodiment, as described above, the transformer 415 (voltage detection unit) is configured to detect the difference in voltage across the inductor 413a (first inductor) and the inductor 413b (second inductor) when both the semiconductor switch unit 411a (first semiconductor switch unit) and the semiconductor switch unit 411b (second semiconductor switch unit) are in an on state. Here, even when the semiconductor switch unit 411a and the semiconductor switch unit 411b are controlled to turn on the switches, there is no loss. arc Therefore, the thyristor 12 in either the semiconductor switch unit 411a or the semiconductor switch unit 411b fails. arcWhen the thyristor 12 is in a normal state, the difference in the voltages across the inductors 413a and 413b when the switch is on is different from when the thyristor 12 is normal. Therefore, when the semiconductor switch unit 411a and the semiconductor switch unit 411b are both in an on state, the difference in the voltages across the inductors 413a and 413b is detected to determine whether the thyristor 12 has failed. arc can be detected with high accuracy.

[0070] In the second embodiment, as described above, the transformer 415 (voltage detection unit) is configured to detect the difference between the voltages across the inductors 413a and 413b by connecting the inductors 413a (first inductor) and 413b (second inductor) to have opposite polarities. With this configuration, the magnitude of the difference between the voltages across the inductors 413a and 413b can be detected without separately detecting the voltages across the inductors 413a and 413b by connecting the inductors 413a and 413b to have opposite polarities. Therefore, the difference between the voltages across the inductors 413a and 413b can be easily detected compared to a case where a configuration is provided to separately detect the voltages across the inductors 413a and 413b.

[0071] In the second embodiment, as described above, the transformer 415 (voltage detection unit) includes the primary winding 415a having two coils and the secondary winding 415b having one coil, and is configured to detect the difference in voltage between the two ends of the inductors 413a and 413b by connecting the inductors 413a (first inductor) and 413b (second inductor) to the two coils of the primary winding 415a so that the inductors 413a and 413b have opposite polarities. With this configuration, the difference in voltage between the two ends of the inductors 413a and 413b can be obtained by connecting the primary winding 415a with opposite polarities, and the difference in voltage between the two ends of the inductors 413a and 413b can be transformed and detected by the output from the secondary winding 415b. Therefore, the transformer 415 can obtain a detection signal (detection value) in which the difference in voltage between the two ends of the inductors 413a and 413b is amplified. As a result, the failure of the thyristor 12 is detected by comparing the amplified signal with a predetermined threshold (second threshold). arc Therefore, the failure of the thyristor 12 can be detected. arc In addition, by using the transformer 415, the primary winding 415a and the secondary winding 415b are insulated from each other, so that the inductor 413 side for detecting the voltage and the loss arc Therefore, it is possible to prevent an abnormality on the inductor 413 side (semiconductor switch section 411 side) from affecting the arithmetic circuit 414 side.

[0072] Other effects of the second embodiment are similar to those of the first embodiment.

[0073] [Variations] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims, not by the description of the embodiments above, and further includes all modifications (variations) within the meaning and scope of the claims.

[0074] For example, in the above first and second embodiments, two semiconductor switch units 11 (411) are provided for each phase, but the present invention is not limited to this. In the present invention, three or more semiconductor switch units 11 (411) may be provided for each phase.

[0075] In the above first and second embodiments, the transformer 15 (415) is used as the "voltage detector" of the present invention, but the present invention is not limited to this. In the present invention, a voltage detector other than the transformer 15 (415) may be provided.

[0076] In the first embodiment, the OR circuit 19 is provided in common for the plurality of semiconductor switch sections 11, but the present invention is not limited to this. arc For example, the signals output from each of the plurality of semiconductor switch sections 11 (comparators 18) may be input to the control section 7 as a serial signal. In this way, the control section 7 can determine whether any of the thyristors 12 of the semiconductor switch sections 11 has failed. arc It will be possible to determine whether

[0077] In the above first and second embodiments, an example has been shown in which the semiconductor switch circuit 10 (410) is provided in the bypass circuit unit 5, but the present invention is not limited to this. In the present invention, the semiconductor switch circuit 10 (410) may be provided in a portion other than the bypass circuit unit 5. For example, as in an uninterruptible power supply system 300 shown in FIG. 7, the semiconductor switch circuit 10 (410) may be provided between a plurality of uninterruptible power supplies 310 connected in parallel with each other and a load 210. Note that in FIG. 7, the semiconductor switch circuit 410 is not shown, and only the semiconductor switch circuit 10 is shown.

[0078] In the above first and second embodiments, the semiconductor switch circuit 10 (410) is provided in the uninterruptible power supply 100 (400), but the present invention is not limited to this. In the present invention, the semiconductor switch circuit 10 (410) may be provided in a device (such as a data center) other than the uninterruptible power supply 100 (400).

[0079] In the second embodiment, the inductance L of the inductor 413a (first inductor) and the inductor 413b (second inductor) are approximately equal, but the present invention is not limited to this. For example, the inductance L of the inductor 413a (first inductor) and the inductor 413b (second inductor) may be configured to have different values. In this case, the failure of the thyristor 12 is determined depending on whether the voltages across the inductor 413a (first inductor) and the inductor 413b (second inductor) are within a predetermined range. arc Detect.

[0080] In the second embodiment, the inductor 413a (first inductor) and the inductor 413b (second inductor) are connected to the two coils of the primary winding 415a of the transformer 415 so that they have opposite polarities, but the present invention is not limited to this. For example, two transformers may be used to transform (detect) the voltages across each of the two inductors, and then a signal based on the magnitude of the difference between the voltages across the two inductors may be acquired (measured). In other words, the difference between the voltages across the two inductors may be detected without being connected in opposite polarities.

[0081] In the second embodiment, the inductor 413a and the inductor 413b are connected to two coils having different polarities in the primary winding 415a of the transformer 415, respectively, to detect the difference in the voltages across the inductors 413a and 413b. However, the present invention is not limited to this. For example, as in the transformer 515 (voltage detection unit) shown in FIG. 8, the inductor 413a and the inductor 413b may be connected to two transformers having the same polarity on the primary side and the secondary side, respectively, and the secondary side outputs of the two transformers may be connected to have opposite polarities, thereby detecting the difference in the voltages across the inductors 413a and 413b. Also, the inductor 413a and the inductor 413b may be connected to the primary sides of the two transformers to have opposite polarities, thereby detecting the difference in the voltages across the inductors 413a and 413b. Also, the inductor 413a and the inductor 413b may be connected to the primary sides of the two transformers to have opposite polarities, thereby detecting the difference in the voltages across the two transformers. Also, a threshold may be set for the output of two inductors 413 directly connected to each other with opposite polarities, without using a transformer. arc may be detected. [Explanation of symbols]

[0082] 1 Converter section 3. Inverter section 5. Bypass circuit section 10, 410 Semiconductor switch circuit 11, 11a, 11b, 411 Semiconductor switch section 12 Thyristor 13, 13a, 13b, 413 Inductors 15, 415, 515 Transformer (Voltage detection section) 200a, 200b AC power supply 210 Load 100, 310, 400 uninterruptible power supplies 411a Semiconductor switch section (first semiconductor switch section) 411b Semiconductor switch section (second semiconductor switch section) 413a Inductor (first inductor) 413b Inductor (second inductor) 415a Primary Winding 415b Secondary Winding

Claims

1. a plurality of semiconductor switch units each including a pair of thyristors connected in anti-parallel to each other and connected in parallel to each other, the semiconductor switch units being provided between an AC power source and a load; an inductor connected in series to each of the plurality of semiconductor switch units; A semiconductor switch circuit configured to detect a misfire in which the thyristor does not change from an off state to an on state when a signal based on the voltage across the inductor connected in series to the semiconductor switch unit is equal to or greater than a predetermined threshold.

2. A plurality of semiconductor switch units each including a pair of thyristors connected in anti-parallel to each other and connected in parallel to each other, the semiconductor switch units being provided between an AC power source and a load; an inductor connected in series to each of the plurality of semiconductor switch units; A failure of the thyristor from changing from an off state to an on state is detected based on a voltage across the inductor connected in series to the semiconductor switch unit, A voltage detection unit that detects a voltage between both ends of the inductor is further provided. a semiconductor switch circuit configured to detect a misfire of the thyristor when a signal based on a voltage across the inductor detected by the voltage detection unit is equal to or greater than a predetermined threshold value.

3. the predetermined threshold value includes a first threshold value that is set based on a shared voltage of the plurality of semiconductor switch units, 3. The semiconductor switch circuit according to claim 2, further comprising a step of detecting a misfire of the thyristor when a signal based on a voltage across the inductor is equal to or greater than the first threshold value.

4. 4. The semiconductor switch circuit according to claim 2, wherein the voltage detection section is provided for each of the plurality of semiconductor switch sections.

5. the predetermined threshold value includes a second threshold value set based on a rated voltage of the thyristor; the voltage detection unit detects a difference between both ends of each of the inductors connected in series to each of the plurality of semiconductor switch units; 3. The semiconductor switch circuit according to claim 2, further configured to detect a misfire of the thyristor when a signal based on a difference between the voltages across the inductors is equal to or greater than the second threshold value.

6. the plurality of semiconductor switch units include a first semiconductor switch unit and a second semiconductor switch unit connected in parallel to each other, the inductor includes a first inductor connected in series to the first semiconductor switch unit and a second inductor connected in series to the second semiconductor switch unit; 6. The semiconductor switch circuit according to claim 5, wherein the first inductor and the second inductor have substantially equal inductances.

7. 7. The semiconductor switch circuit according to claim 6, wherein the voltage detection unit is configured to detect a difference in voltage across the first inductor and the second inductor when both the first semiconductor switch unit and the second semiconductor switch unit are on.

8. 8. The semiconductor switch circuit according to claim 6, wherein the voltage detection unit is configured to detect a difference in voltage across the first inductor and the second inductor by connecting the first inductor and the second inductor to have opposite polarities.

9. The voltage detection unit includes a transformer.

9. The semiconductor switch circuit according to claim 8, wherein the transformer includes a primary winding having two coils and a secondary winding having one coil, and the first inductor and the second inductor are connected to each of the two coils of the primary winding so as to have opposite polarities, thereby detecting a difference in voltage across each of the first inductor and the second inductor.

10. The semiconductor switch circuit according to any one of claims 1 to 9, configured to output a signal indicating a state of a missing arc when at least one of the thyristors included in the plurality of semiconductor switch units is in a state of a missing arc.

11. 11. The semiconductor switch circuit according to claim 1, wherein the inductor connected in series to each of the plurality of semiconductor switch sections is configured to average a current flowing through each of the semiconductor switch sections.

12. A converter unit that converts AC power from an AC power source into DC power; an inverter unit that converts the DC power from the converter unit into AC power and supplies the converted AC power to a load; a bypass circuit section connected in parallel to the converter section and the inverter section between the AC power supply and the load, the bypass circuit section supplying the AC power from the AC power supply to the load; a semiconductor switch circuit provided in the bypass circuit section, The semiconductor switch circuit includes: a plurality of semiconductor switch units each including a pair of thyristors connected in anti-parallel to each other and connected in parallel to each other; an inductor connected in series to each of the plurality of semiconductor switch units; An uninterruptible power supply configured to detect a misfire in which the thyristor does not change from an off state to an on state when a signal based on the voltage across the inductor connected in series to the semiconductor switch unit is equal to or greater than a predetermined threshold.

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