JP5809029B2 - Uninterruptible power system - Google Patents

Description

  The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply having an output switching circuit for switching an AC output supplied to a load from an inverter output to an AC power from a bypass power supply. .

  The uninterruptible power supply is configured to continuously supply power to the load. On the other hand, when a failure occurs in the uninterruptible power supply or when maintenance work is performed on the uninterruptible power supply, the uninterruptible power supply may be stopped. In order to prepare for such a case, a bypass power supply is provided to supply power to the load when the uninterruptible power supply is stopped.

  An uninterruptible power supply generally includes an inverter for converting DC power into AC power having a predetermined voltage and a predetermined frequency and outputting the AC power. When this inverter fails, it is necessary to switch the AC output supplied to the load from the output of the inverter to the AC power from the bypass power supply. The uninterruptible power supply device includes an output switching circuit for controlling switching of the AC output (see, for example, Patent Document 1).

JP-A-8-33236

  However, in the conventional uninterruptible power supply, when a failure occurs in the output switching circuit, it is difficult to normally switch the AC output, and therefore it is not possible to continuously supply power to the load. There was a problem.

  The present invention has been made to solve such problems, and an object of the present invention is to provide an uninterruptible power supply capable of reliably performing switching of AC output.

  According to an aspect of the present invention, the uninterruptible power supply device is inserted and connected to a power conversion unit for supplying power from an AC power supply or a storage battery to a load, and an energization path between the power conversion unit and the load. The first switch is opened when the operation of the first switch, the second switch interposed in the energization path between the bypass power supply and the load, and the power converter is stopped. On the other hand, the first output switching circuit configured to close the second switch and the first output switching circuit are provided independently of each other, and a voltage drop of power supplied to the load is detected. And a second output switching circuit configured to close the second switch.

  According to the present invention, the switching of the AC output is reliably performed by constructing the dual system in which each of the two output switching circuits provided independently of each other is switched the AC output. Can do.

1 is an overall configuration diagram of an uninterruptible power supply according to Embodiment 1 of the present invention. It is a whole block diagram of the uninterruptible power supply by Embodiment 2 of this invention. It is a whole block diagram of the uninterruptible power supply by Embodiment 3 of this invention. It is a wave form diagram for demonstrating operation | movement of the uninterruptible power supply by this Embodiment 3. FIG. It is a whole block diagram of the uninterruptible power supply by Embodiment 4 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

[Embodiment 1]
FIG. 1 is an overall configuration diagram of an uninterruptible power supply according to Embodiment 1 of the present invention.

  Referring to FIG. 1, the uninterruptible power supply is connected to AC input power supply 2, bypass input power supply 3 and load 4.

The AC input power supply 2 and the bypass input power supply 3 are AC power supplies that supply AC power to the uninterruptible power supply. Each of these input power sources is constituted by, for example, a commercial AC power source or a private generator. In FIG. 1 and the drawings described below, a three-phase three-wire (3φ3W) type is shown as an example of an input AC power supply. However, the type of the input AC power supply is not limited to the three-phase three-wire system, and for example, a three-phase four-wire power source or a single-phase three-wire power source may be used.
The uninterruptible power supply includes a housing 1, a main body housed in the housing 1, a storage battery 30 electrically connected to the main body, a bypass input terminal T1 provided in the housing 1, an alternating current An input terminal T2, a storage battery terminal T3, and an output terminal T4 are provided.

  The bypass input terminal T <b> 1 receives AC power from the bypass input power source 3. The AC input terminal T <b> 2 receives AC power from the AC input power source 2.

  The storage battery terminal T3 is connected to the positive electrode 30a of the storage battery 30. The storage battery 30 is housed in a housing 31 different from the housing 1. A load 4 is connected to the output terminal T4.

  The uninterruptible power supply includes, as main parts, electromagnetic contactors (contactors) 5, 10, 15, 17, fuses 6, 9, a reactor 7, a converter 8, an electrolytic capacitor 11, an inverter 12, and a transformer 13. A capacitor 14, a current transformer 16, a thyristor switch 18, and a control device 20. Among these, the contactor 5, the fuse 6, the reactor 7, the converter 8, the inverter 12, the transformer 13, and the contactor 15 are connected in series between the AC input terminal T2 and the output terminal T4.

  The contactor 5 is inserted and connected to an energization path between the AC input terminal T <b> 2 and the converter 8. The contactor 5 opens (on) and closes (off) in response to a command from the control device 20. The fuse 6 is inserted into the energization path between the AC input terminal T 2 and the converter 8 in order to prevent an overcurrent from flowing from the AC input power supply 2. Reactor 7 is a filter for shaping the waveform of AC power input to converter 8.

  Converter 8 converts AC power supplied from AC input power supply 2 into DC power. The electrolytic capacitor 11 smoothes the output voltage of the converter 8. The inverter 12 converts the DC power smoothed by the electrolytic capacitor 11 into AC power having a predetermined voltage and a predetermined frequency. Each of converter 8 and inverter 12 is controlled by UPS control circuit 200 inside control device 20.

  The transformer 13 is a step-up transformer for boosting the AC power output from the inverter 12. The capacitor 14 is connected between the output node 13 a of the transformer 13 and a reference voltage line. The capacitor 14 is a filter for removing high frequency components output from the inverter 12.

  The contactor 15 is for switching the AC output output from the output terminal T4 to the load 4 between the output of the inverter 12 and the output of the bypass circuit including the thyristor switch 19 and the contactor 17. The thyristor switch 18 and the contactor 17 are connected in parallel between the bypass input terminal T1 and the output terminal T4. The thyristor switch 18 is a switch for switching the AC output output from the output terminal T4 to the load 4 from the output of the inverter 12 to the AC power from the bypass input power supply 3 at high speed. The contactor 17 is inserted and connected to the energization path from the bypass input terminal T1 to the output terminal T4. The contactor 17 is for maintaining the AC power from the bypass input power source 3 as an AC output output from the uninterruptible power supply. The contactor 15, the thyristor switch 18, and the contactor 17 are closed (on) and opened (off) in response to a command from the output switching circuit 250 inside the control device 20.

  The current transformer 16 detects the current value of the AC output output from the output terminal T4. The current value detected by the current transformer 16 is sent to the current detection circuit 220 inside the control device 20.

  Storage battery 30 is a power storage device for supplying DC power to inverter 12 when AC input power supply 2 cannot supply AC power (for example, during a power failure). Fuse 9 and contactor 10 are connected in series between output node 8a of converter 8 and storage battery terminal T3. The contactor 10 is closed (on) and opened (off) in response to a command from the control device 20. The fuse 9 prevents an overcurrent from flowing from the storage battery 30.

  In normal times when AC power is supplied from the AC input power supply 2, DC power generated by the converter 8 is stored in the storage battery 30, converted into AC power by the inverter 12, and supplied to the load 4. On the other hand, at the time of a power failure in which the supply of AC power from the AC input power supply 2 is stopped, the operation of the converter 8 is stopped, and the DC power stored in the storage battery 30 is converted into AC power by the inverter 12 and supplied to the load 4. . Therefore, according to the uninterruptible power supply, the operation of the load 4 can be continued using the electric power stored in the storage battery 30 even during a power failure.

  The control device 20 is a control device for controlling the converter 8 and the inverter 12 in order to generate AC power to be supplied to the load 4 during normal times and power outages. As an example, a CPU (Central Processing Unit) and The microcomputer mainly includes a storage unit such as a ROM (Read Only Memory) and a RAM (Random Access Memory). Then, control device 20 controls converter 8 and inverter 12 by causing the CPU to read and execute a program stored in advance in a ROM or the like into RAM. In addition to control of converter 8 and inverter 12, control device 20 controls contactors 5, 10, 15 and a bypass circuit. Note that at least a part of the control device 20 may be configured to execute predetermined numerical / logical operation processing by hardware such as an electronic circuit.

  Specifically, the control device 20 includes a UPS control circuit 200, a voltage detection circuit 210, a current detection circuit 220, a failure detection circuit 230, a gate stop detection circuit 240, and an output switching circuit 250.

  The UPS control circuit 200 controls the power conversion operation in the converter 8 and the inverter 12. The UPS control circuit 200 generates a gate signal for driving the converter 8 and outputs the gate signal to the converter 8. The DC power supplied to the inverter 12 and the storage battery 30 is controlled by the power conversion of the converter 8 according to the gate signal. The UPS control circuit 200 generates a gate signal for driving the inverter 12 and outputs the gate signal to the inverter 12. The AC output output from the output terminal T4 is controlled by power conversion of the inverter 12 according to the gate signal.

  The voltage detection circuit 210 is connected to the output node 13a of the transformer 13 and detects the voltage value of the AC output output from the output terminal T4. The voltage value detected by the voltage detection circuit 210 is sent to the UPS control circuit 200. The current detection circuit 220 outputs the AC output current value detected by the current transformer 16 to the UPS control circuit 200.

  The UPS control circuit 200 compares the voltage value of the AC output detected by the voltage detection circuit 210 with the voltage, frequency, and phase of the bypass input power supply 3 so that the uninterruptible power supply and the bypass input power supply 3 operate synchronously. It is determined whether or not it is in a state. When it is determined that the uninterruptible power supply and the bypass input power supply 3 are in the synchronous operation state, the UPS control circuit 200 generates a synchronous operation detection signal and outputs it to the output switching circuit 250.

  The failure detection circuit 230 detects a failure that has occurred inside the uninterruptible power supply. As an example, the failure detection circuit 230 has a failure in the inverter 12 when a power semiconductor switching element (hereinafter simply referred to as “switching element”) constituting the inverter 12 is in an overcurrent state. Is determined. In this case, failure detection circuit 230 outputs a diagnosis result indicating that inverter 12 has a failure to output switching circuit 250. When the failure detection circuit 230 detects a failure of the inverter 12, the UPS control circuit 200 stops outputting the gate signal to the converter 8 and the inverter 12. That is, UPS control circuit 200 stops converter 8 and inverter 12 by executing a process for turning off all switching elements of converter 8 and inverter 12.

  As a method for detecting a failure of inverter 12, for example, an overcurrent detection circuit for detecting an overcurrent of inverter 12 may be provided. In this case, the failure detection circuit 230 can detect a failure of the inverter 12 by transmitting a signal from the overcurrent detection circuit to the failure detection circuit 230. Moreover, it is not limited to detecting the failure of the inverter 12 only by the overcurrent. For example, the failure of the inverter 12 may be detected based on the temperature of the inverter 12.

  The gate stop detection circuit 240 constantly monitors the gate signal output from the UPS control circuit 200 to the inverter 12 and stops the output of the gate signal from the gate signal (processing for turning off all switching elements of the inverter 12). Is detected. When detecting the stop of the output of the gate signal of the inverter 12, the gate stop detection circuit 240 generates a gate stop detection signal and outputs it to the output switching circuit 250.

  The output switching circuit 250 receives a signal indicating a failure diagnosis result from the failure detection circuit 230, receives a gate stop detection signal from the gate stop detection circuit 240, and receives a synchronous operation detection signal from the UPS control circuit 200. The output switching circuit 250 controls on / off of the contactor 15, the thyristor switch 18, and the contactor 17 based on these input signals.

  Specifically, the output switching circuit 250, when a diagnosis result indicating that a failure has occurred in the uninterruptible power supply device is input from the failure detection circuit 230, the AC output output from the output terminal T4, A command for switching from the output of inverter 12 to the output of the bypass circuit (thyristor switch 18 and contactor 17) is output to contactor 15 and the bypass circuit. Specifically, the output switching circuit 250 issues an off command (open command) for setting the contactor 15 to an off state (open state), and also sets the thyristor switch 18 and the contactor 17 to an on state (closed state). An ON command (close command) is issued. Thereby, the alternating current power from the bypass input power source 3 is supplied to the load 4 via the output terminal T4.

  Further, the output switching circuit 250 converts the AC output output from the output terminal T4 from the output of the inverter 12 even when the gate stop detection signal is input on condition that the synchronous operation detection signal is input. A command for switching to the output of the bypass circuit (thyristor switch 18 and contactor 17) is output to the contactor 15 and the bypass circuit.

  Normally, the start and stop of the inverter 12 are configured to be switchable by the user of the uninterruptible power supply device operating an inverter operation / stop command unit (not shown) provided on the outer wall of the housing 1. For example, when the inverter 12 is operated, the UPS control circuit 200 outputs a gate signal to the inverter 12 when a switch of the inverter operation / stop command unit is turned on. On the other hand, when the operation of the inverter 12 is stopped, the UPS control circuit 200 stops the output of the gate signal when the switch of the inverter operation / stop command unit is turned off. Therefore, since the output stop of the gate signal itself is not a failure, the output switching circuit 250 does not issue a command for switching the AC output. Therefore, if the UPS control circuit 200 erroneously stops the output of the gate signal due to noise mixing in the inverter operation / stop command unit, it is not determined that there is a failure, and the AC output is converted to an inverter without instantaneous interruption. The output of 12 cannot be switched to the output of the bypass circuit.

  In order to avoid such a problem, when the output of the gate signal of the inverter 12 is stopped while the uninterruptible power supply is operating synchronously with the bypass input power supply 3, the output switching circuit 250 fails in the uninterruptible power supply. Therefore, it is determined that the output of the gate signal is erroneously stopped, and a command for switching the AC output output from the output terminal T4 from the output of the inverter 12 to the output of the bypass circuit is issued. Thereby, even when the output of the inverter 12 is stopped by mistake, the AC output can be switched to the output of the bypass circuit without interruption.

  As described above, when a failure occurs in the uninterruptible power supply or when the output of the gate signal of the inverter 12 is mistakenly stopped, the output switching circuit 250 changes the AC output from the output of the inverter 12 to the bypass circuit. Switch to output.

  However, when a failure occurs in the output switching circuit 250, it is difficult to normally switch such AC output. As a result, there is a possibility that AC power cannot be continuously supplied to the load 4 when a failure occurs in the uninterruptible power supply.

  Therefore, in the uninterruptible power supply according to the first embodiment, output switching circuit 40 is provided independently of output switching circuit 250. That is, in the uninterruptible power supply according to the first embodiment, a duplex system is constructed in which each of output switching circuit 250 and output switching circuit 40 is switched between AC outputs. As a result, even if a failure occurs in the output switching circuit 250, a command for switching the AC output by the output switching circuit 40 is issued to the contactor 15 and the bypass circuit. The AC output to be performed can be switched from the output of the inverter 12 to the AC power from the bypass input power source 3.

  Output switching circuit 40 includes a voltage detection circuit 400, a switching control circuit 410, and a detection level setting circuit 420.

  The voltage detection circuit 400 detects the voltage value of the AC output output from the output terminal T4. The voltage value detected by the voltage detection circuit 400 is sent to the switching control circuit 410.

  The switching control circuit 410 compares the AC output voltage value detected by the voltage detection circuit 400 with the reference value set by the detection level setting circuit 420. Based on the comparison result, switching control circuit 410 determines whether or not there is a voltage drop that reduces the voltage value of the AC power output from inverter 12.

  The detection level setting circuit 420 sets a reference value as a detection level for detecting that a voltage drop has occurred in the output of the inverter 12. This reference value is set to 70% of the rated voltage value, for example. The reference value may be fixed to a preset value, or may be variably set according to the type of load 4 by the user of the uninterruptible power supply.

  The switching control circuit 410 determines that a voltage drop has occurred in the output of the inverter 12 when the voltage value of the AC output is lower than the reference value. In this case, the switching control circuit 410 determines that a failure has occurred in the inverter 12, and gives a command to the bypass circuit to switch the AC output output from the output terminal T4 from the output of the inverter 12 to the output of the bypass circuit. Output. Specifically, the switching control circuit 410 issues an on command (close command) for turning on the thyristor switch 18 and the contactor 17 (closed state). Thereby, the thyristor switch 18 and the contactor 17 are set to an ON state, and the AC power from the bypass input power source 3 is supplied to the load 4 via the output terminal T4.

  The switching control circuit 410 issues an on command for the thyristor switch 18 and the contactor 17, but does not issue an off command for turning the contactor 15 to an off state. This is because the turn-off command of the contactor 15 is issued by the output switching circuit 250.

  Specifically, the contactor 17 has a main contact that is inserted and connected to the energization path from the bypass input terminal T1 to the output terminal T4, and an auxiliary contact that is linked to the main contact. In the first embodiment, when the contactor 17 is set to the on state, the main contact is closed and the auxiliary contact is closed. The auxiliary contact is used to output a signal indicating the state (on or off state) of the contactor 17. The failure detection circuit 230 detects whether the contactor 17 is set to an on state or an off state based on a signal output from the auxiliary contact. The failure detection circuit 230 has a failure in the uninterruptible power supply when the contactor 17 is set to the ON state even though the contact switching device 17 is not turned off from the output switching circuit 250. Judge. In this case, failure detection circuit 230 outputs a diagnosis result indicating that a failure has occurred in the uninterruptible power supply to output switching circuit 250. Based on the diagnosis result, the output switching circuit 250 issues an OFF command for the contactor 15 and issues an ON command for the thyristor switch 18 and the contactor 17. As a result, the contactor 15 is set to an off state in response to the off command.

  As described above, the output switching circuit 250 issues the OFF command for the contactor 15 based on the fact that the contactor 17 is set to the ON state in response to the OFF command issued from the output switching circuit 40. Even though 17 is not set to the on state, it is possible to prevent the problem that the contactor 15 is set to the off state. That is, when the output switching circuit 40 is configured to issue an ON command for the contactor 17 and an OFF command for the contactor 15, if a failure occurs in which one of the contactors 15 and 17 cannot be driven as commanded, an AC output is generated. There is a risk of being unable to switch. In addition, either the output switching circuit 40 or the bypass circuit may operate unnecessarily. On the other hand, in the first embodiment, since the contactor 15 is set to the off state based on the contactor 17 being set to the on state, the AC output can be switched reliably. As a result, the reliability of the uninterruptible power supply can be improved.

  As described above, according to the uninterruptible power supply according to the first embodiment, the output switching circuit for executing the switching of the AC output is duplexed so that the load is supplied when the uninterruptible power supply is stopped. The AC output to be performed can be reliably switched from the output of the inverter to the AC power from the bypass input power source. Thereby, the reliability of the uninterruptible power supply can be improved.

[Embodiment 2]
FIG. 2 is an overall configuration diagram of the uninterruptible power supply according to Embodiment 2 of the present invention.

  Referring to FIG. 2, the uninterruptible power supply according to the second embodiment is different from the uninterruptible power supply according to the first embodiment shown in FIG. It differs in the point to prepare. The configuration for supplying load power in the uninterruptible power supply according to the second embodiment is the same as that in FIG.

  In the output switching circuit 42, the switching control circuit 410 bypasses a command for switching the AC output output from the output terminal T4 from the output of the inverter 12 to the output of the bypass circuit (ON command for the thyristor switch 18 and the contactor 17). Output to the circuit and also to the UPS control circuit 200. The UPS control circuit 200 notifies the output switching circuit 250 that the bypass switching ON command has been input from the output switching circuit 42.

  As described in the first embodiment, the output switching circuit 250 is output to the output terminal T4 when a failure occurs in the uninterruptible power supply device or when the output of the gate signal of the inverter 12 is erroneously stopped. A command for switching the AC output from the output of the inverter 12 to the output of the bypass circuit (an OFF command for the contactor 15 and an ON command for the thyristor switch 18 and the contactor 17) is issued. The output switching circuit 250 also issues a command for switching the AC output even when the failure detection circuit 230 detects that the contactor 17 is set to the on state.

  Furthermore, in the second embodiment, output switching circuit 250 issues a command for switching the AC output even when UPS control circuit 200 is given a bypass circuit ON command from output switching circuit 42.

  Since the first embodiment is configured to detect the state of the contactor 17 based on a signal output from the auxiliary contact of the contactor 17, the contactor 17 has an abnormality that the auxiliary contact is not interlocked with the main contact. In this case, there is a possibility that the output switching circuit 40 cannot detect that the contactor 17 is set to the on state. When such an abnormality occurs, the output switching circuit 250 does not issue an OFF command for the contactor 15, and therefore the contactor 15 cannot be set to the OFF state.

  In the second embodiment, even in such a case, it is determined that the contactor 17 is set to the ON state based on the ON command of the contactor 17 transmitted from the output switching circuit 40, and the OFF command is issued to the contactor 15. Can do. Therefore, according to the second embodiment, in addition to the effect of the first embodiment, an effect that the reliability of the uninterruptible power supply can be further improved can be obtained.

[Embodiment 3]
FIG. 3 is an overall configuration diagram of an uninterruptible power supply according to Embodiment 3 of the present invention.

  Referring to FIG. 3, the uninterruptible power supply according to the third embodiment has an output switching circuit 44 instead of output switching circuit 40, as compared with the uninterruptible power supply according to the first embodiment shown in FIG. Prepare. The output switching circuit 44 further includes a time setting circuit 430 as compared with the output switching circuit 40.

  In the third embodiment, when the switching control circuit 410 detects that a voltage drop has occurred in the output of the inverter 12 by comparing the voltage value of the AC output with the reference value, a predetermined time after the detection of the voltage drop is detected. When the time elapses, an ON command for the thyristor switch 18 and the contactor 17 is output to the bypass circuit.

  The predetermined time is set by the time setting circuit 430 and given to the switching control circuit 410. Time setting circuit 430 sets the predetermined time to, for example, one AC cycle (for example, 1/50 second or 1/60 second).

FIG. 4 is a waveform diagram for explaining the operation of the uninterruptible power supply according to the third embodiment.
Referring to FIG. 4, a voltage drop occurs at the output of inverter 12 at time t1. The switching control circuit 410 issues an on command for turning on the bypass circuit (thyristor switch 18 and contactor 17) at time t2 when one cycle of alternating current, which is a predetermined time, has elapsed from time t1.

  By adopting such a configuration, when the phase of the AC output voltage when the switching control circuit 410 detects a voltage drop coincides with the phase of the AC power voltage from the bypass input power supply 3, the bypass circuit (Thyristor switch 18 and contactor 17) are set to the ON state.

  Thus, according to the uninterruptible power supply according to Embodiment 3, the voltage of the AC output before and after the AC output output from the output terminal T4 is switched from the output of the inverter 12 to the AC power from the bypass input power supply 3. The phase of changes continuously. When the output voltage of the inverter 12 and the voltage of the bypass input power supply 3 are not synchronized, a large magnetizing inrush current may flow to the load 4 and the load transformer (not shown) when the AC output is switched. According to the third embodiment, the phase of the AC output voltage can be maintained when the AC output is switched. As a result, the magnetizing inrush current flowing through the load 4 and the load transformer can be suppressed.

  Moreover, in this Embodiment 3, the period when the supply of electric power to the load 3 is stopped can be shortened by setting the predetermined time to one cycle of alternating current. Note that the predetermined time is set in the time setting circuit 430 so that the load 4 does not exceed the time during which the operation of the load 4 is guaranteed not to stop even if the power supply to the load 4 is temporarily stopped. It can be variably set accordingly. According to this, it is possible to suppress the magnetizing inrush current to the load 4 without stopping the operation of the load 4.

[Embodiment 4]
FIG. 5 is an overall configuration diagram of an uninterruptible power supply according to Embodiment 4 of the present invention.

  Referring to FIG. 5, the uninterruptible power supply according to the fourth embodiment is different from the uninterruptible power supply according to the first embodiment shown in FIG. 1 in that the bypass circuit further includes a thyristor switch 19.

  The bypass circuit includes thyristor switches 18 and 19 and a contactor 17 connected in parallel between a bypass input terminal T1 and an output terminal T4. Similar to the thyristor switch 18, the thyristor switch 19 is a switch for switching the AC output output from the output terminal T 4 to the load 4 from the output of the inverter 12 to the AC power from the bypass input power supply 3 at a high speed. The thyristor switch 19 is closed (on) and opened (off) in response to commands from the output switching circuits 250 and 40.

  In the fourth embodiment, the thyristor switch 19 is provided independently of the thyristor switch 18, and is turned on in response to an on command issued from the output switching circuit 250 or the switching control circuit 410 of the output switching circuit 40. Is set. That is, in the uninterruptible power supply according to the fourth embodiment, a duplex system is constructed in which each of thyristor switches 18 and 19 is switched with an AC output. As a result, even if one of the thyristor switches 18 and 19 fails, the other thyristor switch is set to the ON state, so that the AC output output to the load 4 is output from the inverter 12. To AC power from the bypass input power source 3 can be switched. Therefore, according to the fourth embodiment, in addition to the effect of the first embodiment, an effect that the reliability of the uninterruptible power supply can be further improved can be obtained.

  In the configuration illustrated in the first to fourth embodiments, the contactor 15 corresponds to the “first switch” in the present invention, and the bypass circuit including the thyristor switch 18 and the contactor 17 is the “second switch” in the present invention. Corresponds to "switch". The output switching circuit 250 corresponds to the “first output switching circuit” in the present invention, and the output switching circuit 40 corresponds to the “second output switching circuit” in the present invention.

  In the first to fourth embodiments, the output switching circuits 40 and 250 switch the AC output from the output of the inverter 12 to the AC power from the bypass input power source 3 when a failure occurs in the uninterruptible power supply. As described above, the present invention can be applied to a configuration in which the bypass input power supply 3 supplies power to the load 4 when the operation of the inverter 12 is stopped. Therefore, the reason why the operation of the inverter 12 is stopped is not limited to the failure of the uninterruptible power supply, and may include, for example, maintenance of the uninterruptible power supply.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The application of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

  1 housing, 2 AC input power supply, 3 bypass input power supply, 4 load, 5, 10, 15, 17 contactor, 6, 9 fuse, 7 reactor, 8 converter, 11 electrolytic capacitor, 12 inverter, 13 transformer, 14 capacitor, 16 Current transformer, 18, 19 Thyristor switch, 20 Control device, 30 Storage battery, 31 Housing, 40, 42, 44, 250 Output switching circuit, 200 UPS control circuit, 210, 400 Voltage detection circuit, 220 Current detection circuit, 230 failure detection circuit, 240 gate stop detection circuit, 410 switching control circuit, 420 detection level setting circuit, 430 time setting circuit.

Claims (5)

An uninterruptible power supply,
A power conversion unit for supplying power from an AC power source or a storage battery to a load;
A first switch inserted and connected to an energization path between the power converter and the load;
A second switch inserted and connected to the energization path between the bypass power supply and the load;
A first output switching circuit configured to open the first switch while closing the second switch when stopping the operation of the power converter;
A second output switching circuit provided independently of the first output switching circuit and configured to close the second switch when a voltage drop in the power supplied to the load is detected. Circuit,
A failure detection circuit for detecting a failure of the uninterruptible power supply ,
The second output switching circuit includes:
A voltage detection circuit for detecting a voltage of power supplied to the load;
A switching control circuit for comparing a detection value of the voltage detection circuit with a reference value and outputting a closing command for the second switch when the detection value is lower than the reference value;
The first output switching circuit outputs an opening command for the first switch and a closing command for the second switch when a failure of the uninterruptible power supply is detected by the failure detection circuit. Configured to
The failure detection circuit, when the second switch is closed by the second output switching circuit during the output of the opening command of the second switch of the first output switching circuit, An uninterruptible power supply that determines that the uninterruptible power supply is faulty . The second output switching circuit is configured to output a closing command for the second switch to the second switch and to be able to transmit to the first output switching circuit.
When the failure detection circuit detects a failure of the uninterruptible power supply, or when the first output switching circuit receives a closing command for the second switch, the first switch and outputs the opening command, the uninterruptible power supply of claim 1. The switching control circuit closes the second switch when the phase of the voltage of the bypass power supply becomes equal to the phase of the voltage of the power supplied to the load when the voltage drop is detected. It outputs a command, the uninterruptible power supply of claim 1. The switching control circuit is configured to output a closing command for the second switch when a predetermined time has elapsed after detecting the voltage drop,
The uninterruptible power supply according to claim 3 , wherein the second output switching circuit further includes a time setting circuit for setting the predetermined time. The second switch includes a semiconductor switch and an electromagnetic contactor connected in parallel between the bypass power supply and the load;
The uninterruptible power supply according to claim 1, wherein the semiconductor switch is configured by connecting in parallel a plurality of thyristors each receiving a closing command.

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