JP5917921B2 - Uninterruptible power system - Google Patents

Description

  The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply provided with a converter, an inverter, and a bypass switch.

  Conventionally, an uninterruptible power supply device includes a converter, an inverter, and a bypass switch. The converter converts AC power from an AC power source into DC power. The inverter converts the DC power generated by the converter to AC power during normal times when AC power is supplied from the AC power source, and supplies it to the load. In the event of a power failure when the AC power supply from the AC power source is stopped The DC power of the power storage device is converted into AC power and supplied to the load. Therefore, even when a power failure occurs, the operation of the load can be continued during the period in which the DC power is stored in the power storage device.

  The bypass switch is turned on when bypass power is supplied to supply AC power directly from the AC power source to the load. For example, when AC power is supplied from the inverter to the load, if the inverter fails, the bypass switch is turned on instantaneously, and AC power is directly supplied from the AC power source to the load.

  Patent Document 1 discloses an uninterruptible power supply device provided with a circuit for detecting a failure of a bypass switch. In this uninterruptible power supply, a voltage detector that detects a voltage between terminals of the bypass switch and a current detector that detects a current flowing through the bypass switch are provided. When power is supplied from the inverter to the load, it is determined that the bypass switch has failed when the voltage between the terminals of the bypass switch becomes 0 V or when a current flows through the bypass switch.

JP-A-1-222635

  However, in the uninterruptible power supply of Patent Document 1, when the AC voltage from the AC power supply matches the AC voltage generated by the inverter, the voltage between the terminals of the bypass switch becomes 0 V, so an erroneous determination is made. There was a problem that occurred. Further, although a failure that is fixed when the bypass switch is on can be detected, a failure that is fixed when the bypass switch is off cannot be detected.

  Therefore, a main object of the present invention is to provide an uninterruptible power supply capable of accurately detecting a failure of a bypass switch.

  The uninterruptible power supply according to the present invention is normally turned on when one terminal is connected to an AC power supply and AC power is supplied from the AC power supply, and during a power failure when the supply of AC power from the AC power supply is stopped. It is connected to the input switch that is turned off and the other terminal of the input switch, converts the AC power from the AC power source to DC power during normal operation, stops during a power failure, and DC power generated by the converter during normal operation Converted into AC power and supplied to the load, and in the event of a power failure, connected between the inverter that converts the DC power of the power storage device into AC power and supplied to the load, and the other terminal of the input switch and the load. Operates a bypass switch that is turned on when bypass power is supplied to supply AC power directly to the load, a current detector that detects the current flowing through the bypass switch, and a converter that is temporarily stopped during a power failure. It is allowed, in which a determining control circuit whether the bypass switch is normally based on a detection result of the current detector. Therefore, when no current is detected by the current detector, the bypass switch is normally turned off. When a current is detected by the current detector, it can be determined that the bypass switch has failed and is turned on.

  Preferably, the control circuit operates the converter by turning on the bypass switch. In this case, when the current detector detects the current, the bypass switch is normally turned on, and when the current detector does not detect the current, it can be determined that the bypass switch has failed and is turned off. it can.

  Further, the other uninterruptible power supply according to the present invention is normally turned on when one terminal is connected to the AC power supply and AC power is supplied from the AC power supply, and the supply of AC power from the AC power supply is stopped. An input switch that is turned off during a power failure and connected to the other terminal of the input switch.In normal times, AC power from an AC power source is converted to DC power, and in a power failure, it is generated by a converter. DC power is converted to AC power and supplied to the load.In the event of a power failure, the DC power of the power storage device is converted to AC power and supplied to the load, and connected between the other terminal of the input switch and the load. The bypass switch that is turned on when bypass power is supplied directly from the AC power source to the load, the current detector that detects the current flowing through the bypass switch, and the input switch that is normally turned on And a control circuit that causes a pseudo power failure to occur, operates the converter that was temporarily stopped at the time of the pseudo power failure, and determines whether or not the bypass switch is normal based on the detection result of the current detector It is. Therefore, when no current is detected by the current detector, the bypass switch is normally turned off. When a current is detected by the current detector, it can be determined that the bypass switch has failed and is turned on.

  Preferably, the control circuit turns on the bypass switch to operate the converter once stopped at the time of a pseudo power failure. In this case, when the current detector detects the current, the bypass switch is normally turned on, and when the current detector does not detect the current, it can be determined that the bypass switch has failed and is turned off. it can.

  Still another uninterruptible power supply according to the present invention includes a converter that converts AC power from an AC power source into DC power, and DC power that is generated by the converter during normal times when AC power is supplied from the AC power source. An alternating current power supply to a load, and in the event of a power failure when the alternating current power supply from the alternating current power supply is stopped, an inverter that converts the direct current power of the power storage device to an alternating current power and supplies the load to the load, an alternating current power supply, A bypass switch that is connected between the loads and is turned on during bypass power supply that directly supplies AC power from the AC power supply to the load, a current detector that detects the current flowing through the bypass switch, and AC power from the AC power supply during normal operation The converter is controlled so that a current having a waveform obtained by superimposing a signal having a second frequency higher than the first frequency on the sine wave having the same first frequency flows from the AC power source to the converter. And, in which a determining control circuit whether the bypass switch is normally based on a detection result of the current detector. Therefore, when the current detector does not detect the second frequency current, the bypass switch is normally turned off. When the current detector detects the second frequency current, the bypass switch fails and is turned on. Can be determined.

  Preferably, the control circuit turns on the bypass switch to control the converter so that a current having a waveform in which the signal of the second frequency is superimposed on the sine wave of the first frequency flows from the AC power supply to the converter. In this case, when the current detector detects the second frequency current, the bypass switch is normally turned on. When the current detector does not detect the second frequency current, the bypass switch fails and is turned off. Can be determined.

  Still another uninterruptible power supply according to the present invention includes a converter that converts AC power from an AC power source into DC power, and DC power that is generated by the converter during normal times when AC power is supplied from the AC power source. An alternating current power supply to a load, and in the event of a power failure when the alternating current power supply from the alternating current power supply is stopped, an inverter that converts the direct current power of the power storage device to an alternating current power and supplies the load to the load, an alternating current power supply, A bypass switch that is connected between the loads and is turned on during bypass power supply that supplies AC power directly from the AC power supply to the load, a current detector that detects the current flowing through the bypass switch, and AC power is supplied to the load from the inverter And a control circuit that varies the output voltage of the inverter when it is in operation and determines whether or not the bypass switch is normal based on the detection result of the current detector Than is. Therefore, when no current fluctuation is detected by the current detector, the bypass switch is normally turned off. When a current fluctuation is detected by the current detector, it is determined that the bypass switch has failed and is turned on. be able to.

  Preferably, the control circuit changes the output voltage of the inverter by turning on the bypass switch. In this case, when the current detector detects a change in current, the bypass switch is normally turned on, and when the current detector does not detect a change in current, the bypass switch is faulty and turned off. Can be determined.

  Preferably, the information processing apparatus further includes a notification device that notifies the user when the control circuit determines that the bypass switch is not normal. In this case, it can be notified that the bypass switch has failed.

  As described above, according to the present invention, the failure of the bypass switch can be accurately detected.

It is a circuit block diagram which shows the structure of the uninterruptible power supply by Embodiment 1 of this invention. It is a time chart which shows operation | movement at the time of normal of the uninterruptible power supply device shown in FIG. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply device shown in FIG. It is a time chart which shows the operation | movement at the time of the normal of the uninterruptible power supply by Embodiment 2 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of the normal of the uninterruptible power supply by Embodiment 3 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of normal of the uninterruptible power supply by Embodiment 4 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of the normal of the uninterruptible power supply by Embodiment 5 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of normal of the uninterruptible power supply by Embodiment 6 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of normal of the uninterruptible power supply by Embodiment 7 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG. It is a time chart which shows the operation | movement at the time of the normal of the uninterruptible power supply by Embodiment 8 of this invention. It is a time chart which shows the operation | movement at the time of failure of the uninterruptible power supply demonstrated in FIG.

[Embodiment 1]
As shown in FIG. 1, the uninterruptible power supply according to Embodiment 1 of the present application includes an input terminal T1, an output terminal T2, switches S1 and S2, capacitors 2, 10, and 14, reactors 3 and 12, a current detector 4, and the like. 13, a bypass switch 5, a converter 6, a DC / DC converter 7, a battery 8, a control circuit 9, an inverter 11, and a notification device 15.

  Input terminal T1 receives AC power of commercial frequency from AC power supply 1, and is connected to an input node of converter 6 via switches S1 and S2 and reactor 3. The terminal on the reactor 3 side of the switch S2 is connected to the capacitor 2. Current detector 4 is provided between reactor 3 and an input node of converter 6.

  The switch S1 is turned on during normal times when AC power is supplied from the AC power supply 1, and turned off during a power failure when the supply of AC power from the AC power supply 1 is stopped. The switch S2 is normally turned on, and is turned off when the converter 6 and the bypass switch 5 are disconnected.

  Capacitor 2 and reactor 3 constitute an input filter and allow AC power from AC power supply 1 to pass through converter 6 and prevent high-frequency switching noise generated in converter 6 from leaking to AC power supply 1 side. Current detector 4 detects current I 1 flowing into the input node of converter 6 and provides signal φI 1 indicating the detected value to control circuit 9.

  An output node of converter 6 is connected to battery 8 via DC / DC converter 7 and to each of capacitor 10 and inverter 11. The converter 6 converts the AC power from the AC power source 1 into DC power during normal times when AC power is supplied from the AC power source 1, and power during a power failure when the supply of AC power from the AC power source 1 is stopped. Stop conversion operation.

  The DC / DC converter 7 supplies the DC power generated by the converter 6 to the battery 8 during normal times when AC power is supplied from the AC power supply 1. At this time, the DC / DC converter 7 converts the output voltage of the converter 6 into a predetermined DC voltage and supplies it to the battery 8. Moreover, the DC / DC converter 7 takes out DC power from the battery 8 and supplies it to the inverter 11 at the time of a power failure. At this time, the DC / DC converter 7 converts the voltage between the terminals of the battery 8 into a predetermined DC voltage and supplies it to the inverter 11. The battery 8 stores DC power. Capacitor 10 temporarily stores DC power and smoothes the output voltage of converter 6.

  The inverter 11 converts the DC power generated by the converter 6 into AC power having a commercial frequency during normal times when AC power is supplied from the AC power source 1, and converts the DC / DC converter 7 from the battery 8 during power failure. The direct-current power given through the converter is converted into commercial-frequency alternating-current power.

  The output node of the inverter 11 is connected to the output terminal T2 through the reactor 12. The output terminal T2 is connected to the capacitor 14. Reactor 12 and capacitor 14 constitute an output filter that allows commercial frequency AC power generated by inverter 11 to pass through load 16 and prevents high-frequency switching noise generated by inverter 11 from leaking to load 16 side. To do. The current detector 13 is provided between the reactor 12 and the output terminal T2. The current detector 13 detects a current I2 that is the sum of the current that flows from the inverter 11 to the load 16 and the current that flows from the inverter 11 to the bypass switch 5, and supplies a signal φI2 indicating the detected value to the control circuit 9.

  One terminal of the bypass switch 5 is connected to a node between the switches S1 and S2, and the other terminal of the bypass switch 5 is connected to the output terminal T2 via the current detector 13. The bypass switch 5 includes, for example, two thyristors 5a and 5b connected in antiparallel, and is turned off when the bypass control signal CNT is at the “L” level of the inactivation level, and the bypass control signal CNT is at the activation level. Turns on when the "H" level. The bypass control signal CNT is generated by the control circuit 9.

  The bypass switch 5 is turned on in the bypass power supply mode in which AC power is directly supplied from the AC power source 1 to the load 16, and is turned off in the inverter power supply mode in which the AC power generated by the inverter 11 is supplied to the load 16. Further, when the AC power is supplied from the inverter 11 to the load 16, the bypass switch 5 is turned on instantaneously when the inverter 11 fails and supplies AC power from the AC power supply 1 to the load 16.

  The control circuit 9 controls the entire uninterruptible power supply based on the detection results of the current detectors 4 and 13. In particular, the control circuit 9 determines whether or not the bypass switch 5 is normal based on the detection result of the current detector 13 during a power failure. When the control circuit 9 determines that the bypass switch 5 is not normal, the notification device 15 notifies the user or worker of the uninterruptible power supply. The notification device 15 notifies that the bypass switch 5 has failed by, for example, a buzzer sound, lamp light, an image displayed on the display, or the like.

  Next, the operation of this uninterruptible power supply will be described. 2A to 2F are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is normal. At normal time (time t0 to t1) when AC power is supplied from the AC power source 1, the voltage V1 at the input terminal T1 is an AC voltage that changes in a sine wave shape. An AC voltage having the same phase as the input voltage V1 and the same voltage value is generated by the inverter 11, and the voltage V2 at the output terminal T2 matches the input voltage V1.

  Further, the current I1 flowing into the converter 6 is an alternating current that changes in a sine wave shape with the same phase as the input voltage V1. The output current I2 of the inverter 11 is an alternating current that changes in a sine wave shape with the same phase as the output voltage V2. Further, the battery 8 is sufficiently charged, and the DC / DC converter 7 is stopped. Converter 6 is in operation and converts AC power from AC power supply 1 into DC power. Since the inverter power supply mode is set, the bypass control signal CNT is set to the “L” level of the inactivation level and the bypass switch 5 is turned off.

  When a power failure occurs at time t1, the input voltage V1 drops to a voltage sufficiently lower than the rated voltage. In response to this, the switch S1 in FIG. 1 is turned off, and the operation of the converter 6 is stopped. Further, the DC power of the battery 8 is supplied to the inverter 11 via the DC / DC converter 7, converted into AC power by the inverter 11, and supplied to the load 16. For this reason, the output voltage V2 and the output current I2 are maintained at the same value and phase as in normal times. Further, since the switch S1 is turned off and the operation of the converter 6 is stopped, the input current I1 becomes 0A.

  At time t2, control circuit 9 restarts the operation of converter 6. Here, since the bypass switch 5 is normally off, the input current I1 to the converter 6 is maintained at 0 A even if the operation of the converter 6 is resumed. The control circuit 9 detects that the current I1 is equal to or less than a predetermined threshold current, and determines that the bypass switch 5 is normal.

  FIGS. 3A to 3F are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 2A to 2F. When the bypass control signal CNT is set to the “L” level, but the bypass switch 5 is not normally turned off and is broken and turned on, as shown in FIGS. When the converter 6 is operated at time t <b> 2, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. As a result, both currents I1 and I2 increase as shown in FIGS. The control circuit 9 detects that the current I1 has exceeded a predetermined threshold current, and determines that the bypass switch 5 is not normal. The determination result is notified to the user or worker of the uninterruptible power supply by the notification device 15, and the failed bypass switch 5 is replaced with a normal product or repaired.

  In the first embodiment, the converter 6 that is temporarily stopped at the time of a power failure is operated, and when the input current I1 of the converter 6 exceeds a predetermined threshold current, it is determined that the bypass switch 5 is broken and turned on. . Therefore, it can be accurately determined whether or not the bypass switch 5 is normal.

  In the first embodiment, whether or not the bypass switch 5 is normal is determined based on the detection result of the current detector 4. However, the present invention is not limited to this, and the converter 6 that is temporarily stopped at the time of a power failure is operated. The determination may be made based on whether or not a current flows through the bypass switch 5 at the time. For example, the determination may be made based on the detection result of the current detector 13 or based on both the current detectors 4 and 13.

  In the first embodiment, the current I2 which is the sum of the current flowing from the inverter 11 to the load 16 and the current flowing from the inverter 11 to the bypass switch 5 is detected by the current detector 13, but flows from the inverter 11 to the load 16. A current detector that detects current and a current detector that detects current flowing from the inverter 11 to the bypass switch 5 may be provided separately.

[Embodiment 2]
4 (a) to 4 (f) are time charts showing the operation of the uninterruptible power supply according to Embodiment 2 of the present invention, and are compared with FIGS. 2 (a) to 2 (f). Referring to FIGS. 4A to 4F, the second embodiment is different from the first embodiment in that the bypass control signal CNT is raised from the “L” level to the “H” level at time t2. It is. At this time, when the bypass switch 5 is normally turned on, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. As a result, both currents I1 and I2 increase as shown in FIGS. The control circuit 9 detects that the current I1 has exceeded a predetermined threshold current, and determines that the bypass switch 5 is normally turned on.

  FIGS. 5A to 5F are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 4A to 4F. Referring to FIGS. 5A to 5F, even when bypass control signal CNT is raised from “L” level to “H” level at time t2, if bypass switch 5 fails and does not turn on, The input current I1 of the converter 6 remains substantially 0A and does not change. The control circuit 9 detects that the current I1 is less than or equal to a predetermined threshold current, and determines that the bypass switch 5 fails and does not turn on. Since other configurations and operations are the same as those in the first embodiment, description thereof will not be repeated. Also in this second embodiment, the same effect as in the first embodiment can be obtained.

[Embodiment 3]
6 (a) to 6 (g) are time charts showing the operation of the uninterruptible power supply according to Embodiment 2 of the present invention, and are compared with FIGS. 2 (a) to 2 (f). With reference to FIGS. 6A to 6G, the second embodiment is different from the first embodiment in that the input switch S1 is turned off at time t1 to cause a power failure in a pseudo manner.

  When the input switch S1 is turned off at time t1, the operation of the converter 6 is temporarily stopped, and the input current I1 of the converter 6 becomes 0A. Further, the discharging operation of the DC / DC converter 7 is started, and the DC power of the battery 8 is supplied to the inverter 11 via the DC / DC converter 7, converted into AC power, and supplied to the load 16. For this reason, the voltage V1 of the input terminal T1, the voltage V2 of the output terminal T2, and the output current I2 of the inverter 11 do not change before and after the occurrence of the pseudo power failure.

  Next, at time t2, the control circuit 9 restarts the operation of the converter 6. Here, since the bypass switch 5 is normally off, the input current I1 to the converter 6 is maintained at 0 A even if the operation of the converter 6 is resumed. The control circuit 9 detects that the current I1 is equal to or less than a predetermined threshold current, and determines that the bypass switch 5 is normal.

  FIGS. 7A to 7G are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 6A to 6G. When the bypass control signal CNT is set to the “L” level and the bypass switch 5 is not normally turned off and is turned on due to failure, as shown in FIGS. When the converter 6 is operated at time t <b> 2, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. As a result, as shown in FIGS. 7B and 7C, both currents I1 and I2 increase. The control circuit 9 detects that the current I1 has exceeded a predetermined threshold current, and determines that the bypass switch 5 is not normal. Since other configurations and operations are the same as those in the first embodiment, description thereof will not be repeated.

  In the third embodiment, the same effect as in the first embodiment can be obtained, and even if a power failure does not actually occur, it is determined whether the bypass switch 5 is normal by generating a power failure in a pseudo manner. Can do.

[Embodiment 4]
8 (a) to 8 (g) are time charts showing the operation of the uninterruptible power supply according to Embodiment 4 of the present invention, and are compared with FIGS. 6 (a) to 6 (g). Referring to FIGS. 8A to 8G, the fourth embodiment is different from the third embodiment in that the bypass control signal CNT is raised from the “L” level to the “H” level at time t1. It is. At this time, when the bypass switch 5 is normally turned on, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. As a result, as shown in FIGS. 8B and 8C, both currents I1 and I2 increase. The control circuit 9 detects that the current I1 has exceeded a predetermined threshold current, and determines that the bypass switch 5 is normally turned on.

  FIGS. 9A to 9G are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 8A to 8G. Referring to FIGS. 9A to 9G, even when bypass control signal CNT is raised from “L” level to “H” level at time t2, if bypass switch 5 fails and does not turn on, The input current I1 of the converter 6 remains substantially 0A and does not change. The control circuit 9 detects that the current I1 is less than or equal to a predetermined threshold current, and determines that the bypass switch 5 fails and does not turn on. Since other configurations and operations are the same as those of the third embodiment, description thereof will not be repeated. In the fourth embodiment, the same effect as in the third embodiment can be obtained.

[Embodiment 5]
FIGS. 10A to 10D are time charts showing the operation of the uninterruptible power supply according to Embodiment 5 of the present invention. FIGS. 10A to 10D show the operation of the uninterruptible power supply when the bypass switch 5 is normal. At time t0 to t1, AC power is normally supplied from the AC power source 1 to the uninterruptible power supply, and the voltage V1 at the input terminal T1 is an AC voltage that changes in a sine wave form. An AC voltage having the same phase as the input voltage V1 and the same voltage value is generated by the inverter 11, and the voltage V2 at the output terminal T2 matches the input voltage V1.

  Further, the current I1 flowing into the converter 6 is an alternating current that changes in a sine wave shape with the same phase as the input voltage V1. The output current I2 of the inverter 11 is an alternating current that changes in a sine wave shape with the same phase as the output voltage V2. Further, the battery 8 is sufficiently charged, and the DC / DC converter 7 is stopped. Converter 6 is in operation and converts AC power from AC power supply 1 into DC power. Since the inverter power supply mode is set, the bypass control signal CNT is set to the “L” level of the inactivation level and the bypass switch 5 is turned off.

  At time t1, a test for determining whether or not the bypass switch 5 is normal is started. At time t <b> 1, control circuit 9 superimposes a test signal having a frequency higher than the AC power from AC power supply 1 on the current command value of converter 6. In other words, the control circuit 9 generates a current I1 having a waveform obtained by superimposing a test signal having a second frequency higher than the commercial frequency on a sine wave having the same commercial frequency (first frequency) as the AC power from the AC power source 1. The converter 6 is controlled to flow from 1 to the converter 6. The time for superimposing the test signal is limited to a short time necessary for determining whether or not the bypass switch 5 is normal.

  Here, since the bypass switch 5 is normally off, even if the waveform of the input current I1 of the converter 6 is a waveform in which a test signal is superimposed on a sine wave, the output current I2 of the inverter 11 does not change, Maintained as a commercial frequency sine wave. The control circuit 9 detects that the test signal is not superimposed on the current I2, and determines that the bypass switch 5 is normal.

  FIGS. 11A to 11D are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 10A to 10D. When the bypass control signal CNT is set to the “L” level, but the bypass switch 5 is not normally turned off and is broken and turned on, as shown in FIGS. When the waveform of the input current I1 of the converter 6 becomes a waveform in which a test signal is superimposed on a sine wave at time t1, the output current I2 of the inverter 11 also changes in the same manner as the current I1. In other words, the second frequency current is supplied from the inverter 11 to the converter 6 via the bypass switch 5. The control circuit 9 detects that the test signal is superimposed on the current I2, and determines that the bypass switch 5 is not normal. Since other configurations and operations are the same as those in the first embodiment, description thereof will not be repeated.

  In the fifth embodiment, the same effect as in the first embodiment can be obtained, and whether or not the bypass switch 5 is normal can be determined even when a power failure has not occurred.

[Embodiment 6]
12 (a) to 12 (d) are time charts showing the operation of the uninterruptible power supply according to Embodiment 6 of the present invention, and are compared with FIGS. 11 (a) to 11 (d). Referring to FIGS. 12A to 12D, the sixth embodiment differs from the fifth embodiment in that the bypass control signal CNT is raised from the “L” level to the “H” level at time t1. It is. At this time, when the bypass switch 5 is normally turned on, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. As a result, as shown in FIGS. 12B and 12C, test signal components having frequencies higher than the commercial frequency appear in each of the currents I1 and I2. The control circuit 9 detects that the test signal is superimposed on the current I2, and determines that the bypass switch 5 is normal.

  FIGS. 13A to 13D are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 12A to 12D. Referring to FIGS. 13A to 13D, even when bypass control signal CNT is raised from “L” level to “H” level at time t2, if bypass switch 5 fails and does not turn on, The output current I2 of the inverter 11 remains unchanged as a sine wave. The control circuit 9 detects that the test signal is not superimposed on the current I2, and determines that the bypass switch 5 does not turn on due to failure. Since other configurations and operations are the same as those of the fifth embodiment, description thereof will not be repeated. In the sixth embodiment, the same effect as in the fifth embodiment can be obtained.

[Embodiment 7]
FIGS. 14A to 14C are time charts showing the operation of the uninterruptible power supply according to Embodiment 7 of the present invention. FIGS. 14A to 14C show the operation of the uninterruptible power supply when the bypass switch 5 is normal. At time t0 to t1, AC power is normally supplied from the AC power source 1 to the uninterruptible power supply, and the voltage V1 at the input terminal T1 is an AC voltage that changes in a sine wave form. An AC voltage having the same phase as the input voltage V1 and the same voltage value is generated by the inverter 11, and the voltage V2 at the output terminal T2 matches the input voltage V1.

  The output current I2 of the inverter 11 is an alternating current that changes in a sine wave shape with the same phase as the output voltage V2. Further, the battery 8 is sufficiently charged, and the DC / DC converter 7 is stopped. Converter 6 is in operation and converts AC power from AC power supply 1 into DC power. Since the inverter power supply mode is set, the bypass control signal CNT is set to the “L” level of the inactivation level and the bypass switch 5 is turned off.

  At time t1, a test for determining whether or not the bypass switch 5 is normal is started. From time t1 to t2, the control circuit 9 increases the output voltage V2 of the inverter 11. Here, since the bypass switch 5 is normally turned off, even if the output voltage V2 of the inverter 11 is increased, the output current I2 of the inverter 11 hardly changes. The control circuit 9 detects that the current I2 hardly changes before and after the time t1, and determines that the bypass switch 5 is normal.

  Further, at time t2 to t3, the control circuit 9 reduces the output voltage V2 of the inverter 11. Here, since the bypass switch 5 is normally off, even if the output voltage V2 of the inverter 11 is reduced, the output current I2 of the inverter 11 hardly changes. The control circuit 9 detects that the current I2 hardly changes before and after the time t2, and determines that the bypass switch 5 is normal.

  FIGS. 15A to 15C are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 14A to 14C. When the bypass control signal CNT is set to the “L” level, but the bypass switch 5 is not normally turned off and is broken and turned on, as shown in FIGS. 15A to 15C, When the output voltage V2 of the inverter 11 is increased at time t1, a current flows from the inverter 11 to the AC power supply 1 via the bypass switch 5, and the output current I2 of the inverter 11 increases. The control circuit 9 detects that the output current I2 of the inverter 11 has increased before and after the time t1, and determines that the bypass switch 5 is not normal.

  Further, at time t2 to t3, the control circuit 9 reduces the output voltage V2 of the inverter 11. Here, since the bypass switch 5 is not normally turned off and is turned on due to failure, when the output voltage V2 of the inverter 11 is reduced, a current flows from the inverter 11 to the load 16, and the bypass switch from the AC power source 1 is used. A current flows through the load 16 via 5. The current detector 13 shown in FIG. 1 detects the current difference between the current from the inverter 11 to the load 16 and the current from the AC power source 1 to the load 16 via the bypass switch 5, so that the detected value of the current I2 is Obviously decrease. The control circuit 9 detects that the current I2 has greatly decreased before and after time t2, and determines that the bypass switch 5 is not normal. Since other configurations and operations are the same as those in the first embodiment, description thereof will not be repeated.

  In the seventh embodiment, the same effect as in the first embodiment can be obtained, and whether or not the bypass switch 5 is normal can be determined even when a power failure has not occurred.

[Embodiment 8]
16 (a) to 16 (c) are time charts showing the operation of the uninterruptible power supply according to Embodiment 8 of the present invention, and are compared with FIGS. 14 (a) to 14 (c). Referring to FIGS. 16A to 16C, the eighth embodiment is different from the seventh embodiment in that the bypass control signal CNT is raised from the “L” level to the “H” level at time t1. It is.

  Here, since the bypass switch 5 is normally turned on, a part of the output current of the inverter 11 flows into the converter 6 via the bypass switch 5. Thus, as shown in FIGS. 16A and 16B, when the output voltage V2 of the inverter 11 is increased at time t1, a current flows from the inverter 11 to the AC power supply 1 via the bypass switch 5, and the inverter 11 The output current I2 increases. The control circuit 9 detects that the output current I2 of the inverter 11 has increased before and after the time t1, and determines that the bypass switch 5 is normal.

  Further, at time t2 to t3, the control circuit 9 reduces the output voltage V2 of the inverter 11. Here, since the bypass switch 5 is normally turned on, when the output voltage V2 of the inverter 11 is reduced, a current flows from the inverter 11 to the load 16 and also from the AC power source 1 to the load 16 via the bypass switch 5. Current flows. The current detector 13 shown in FIG. 1 detects the current difference between the current from the inverter 11 to the load 16 and the current from the AC power source 1 to the load 16 via the bypass switch 5, so that the detected value of the current I2 is Obviously decrease. The control circuit 9 detects that the current I2 has greatly decreased before and after time t2, and determines that the bypass switch 5 is normal.

  FIGS. 17A to 17C are time charts showing the operation of the uninterruptible power supply when the bypass switch 5 is not normal, and are compared with FIGS. 16A to 16C. Referring to FIGS. 17A to 17C, even if the output voltage V2 of the inverter 11 is increased at time t1, the output current I2 of the inverter 11 does not change if the bypass switch 5 fails and does not turn on. . The control circuit 9 detects that the output current I2 of the inverter 11 does not change before and after the time t1, and determines that the bypass switch 5 is not normal.

  Further, at time t2 to t3, the control circuit 9 reduces the output voltage V2 of the inverter 11. Here, since the bypass switch 5 is not normally turned on, even if the output voltage V2 of the inverter 11 is reduced, the output current I2 of the inverter 11 hardly changes. The control circuit 9 detects that the current I2 does not change before and after the time t2, and determines that the bypass switch 5 fails and does not turn on. Since other configurations and operations are the same as those in the seventh embodiment, description thereof will not be repeated. In the eighth embodiment, the same effect as in the seventh embodiment can be obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 AC power source, 2, 10, 14 capacitor, 3, 12 reactor, 3 reactor, 4, 13 current detector, 5 bypass switch, 5a, 5b thyristor, 6 converter, 7 DC / DC converter, 8 battery, 9 control circuit , 11 inverter, 15 alarm device, 16 load, S1 input switch, S2 switch, T1 input terminal, T2 output terminal.

Claims (9)

On the other hand, the terminal is connected to an AC power supply, and is turned on at the normal time when AC power is supplied from the AC power supply, and turned off at the time of power failure when the supply of AC power from the AC power supply is stopped,
A converter that is connected to the other terminal of the input switch, converts AC power from the AC power source to DC power during the normal time, and stops during the power failure;
An inverter that converts the DC power generated by the converter into AC power and supplies it to the load during the normal time, and converts the DC power of the power storage device into AC power and supplies it to the load during the power outage;
A bypass switch that is connected between the other terminal of the input switch and the load, and is turned on during bypass power feeding that directly supplies AC power from the AC power source to the load;
A current detector for detecting a current flowing through the bypass switch;
An uninterruptible power supply comprising: a control circuit that operates the converter that is temporarily stopped at the time of the power failure and determines whether or not the bypass switch is normal based on a detection result of the current detector.   The uninterruptible power supply according to claim 1, wherein the control circuit turns on the bypass switch to operate the converter. On the other hand, the terminal is connected to an AC power supply, and is turned on at the normal time when AC power is supplied from the AC power supply, and turned off at the time of power failure when the supply of AC power from the AC power supply is stopped,
A converter that is connected to the other terminal of the input switch, converts AC power from the AC power source to DC power during the normal time, and stops during the power failure;
An inverter that converts the DC power generated by the converter into AC power and supplies it to the load during the normal time, and converts the DC power of the power storage device into AC power and supplies it to the load during the power outage;
A bypass switch that is connected between the other terminal of the input switch and the load, and is turned on during bypass power feeding that directly supplies AC power from the AC power source to the load;
A current detector for detecting a current flowing through the bypass switch;
The input switch is turned off at the normal time to cause a pseudo power failure, the converter that is temporarily stopped at the pseudo power failure is operated, and the bypass switch is normal based on the detection result of the current detector. An uninterruptible power supply comprising a control circuit for determining whether or not.   The uninterruptible power supply according to claim 3, wherein the control circuit turns on the bypass switch to operate the converter once stopped. A converter that converts AC power from an AC power source into DC power;
During normal times when AC power is supplied from the AC power source, the DC power generated by the converter is converted to AC power and supplied to the load, and during a power failure when the supply of AC power from the AC power source is stopped. An inverter that converts the DC power of the power storage device into AC power and supplies the AC power to the load;
A bypass switch connected between the AC power source and the load, and turned on during bypass power feeding to directly supply AC power from the AC power source to the load;
A current detector for detecting a current flowing through the bypass switch;
At the normal time, a current having a waveform in which a signal having a second frequency higher than the first frequency is superimposed on a sine wave having the same first frequency as the AC power from the AC power supply flows from the AC power supply to the converter. An uninterruptible power supply comprising: a control circuit that controls the converter and determines whether or not the bypass switch is normal based on a detection result of the current detector.   The control circuit turns on the bypass switch and controls the converter so that a current having a waveform in which the signal of the second frequency is superimposed on the sine wave of the first frequency flows from the AC power source to the converter. The uninterruptible power supply according to claim 5. A converter that converts AC power from an AC power source into DC power;
During normal times when AC power is supplied from the AC power source, the DC power generated by the converter is converted to AC power and supplied to the load, and during a power failure when the supply of AC power from the AC power source is stopped. An inverter that converts the DC power of the power storage device into AC power and supplies the AC power to the load;
A bypass switch connected between the AC power source and the load, and turned on during bypass power feeding to directly supply AC power from the AC power source to the load;
A current detector for detecting a current flowing through the bypass switch;
A control circuit that varies the output voltage of the inverter when AC power is supplied from the inverter to the load, and determines whether the bypass switch is normal based on a detection result of the current detector. ,Uninterruptible power system. The uninterruptible power supply according to claim 7 , wherein the control circuit changes the output voltage of the inverter by turning on the bypass switch.   The uninterruptible power supply according to any one of claims 1 to 8, further comprising: a notification device that notifies the fact when the control circuit determines that the bypass switch is not normal.

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