JP6396242B2 - Uninterruptible power system - Google Patents

Description

  Embodiments described herein relate generally to an uninterruptible power supply.

 Conventionally, as an example of an uninterruptible power supply, a power conversion device including a converter that converts power of commercial AC power into DC power, an inverter that converts the converted DC power into AC power and supplies the load, and power conversion It has a bypass circuit that is connected in parallel to the device and that makes use of the power converter when it fails, and a DC power supply that is connected to the DC side of the inverter, supplies DC power to the inverter, converts it to AC power, and supplies it to the load. When the power supply is normal, power is converted by the power conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load. When the AC power supply is abnormal, the DC power of the DC power supply is supplied. Some are converted by an inverter and can be supplied to a load.

JP 2002-171694 A

  In the uninterruptible power supply described above, it is important to continue the operation of the inverter for a long time from the viewpoint of reliability of load power feeding. In the conventional uninterruptible power supply, when the AC current detection signal of the AC power supply becomes excessive, it is considered that a failure has occurred in the uninterruptible power supply main unit, and the operation from the inverter gate control means and the converter gate control means The signal is stopped and the bypass switch is closed by the bypass switch closing signal to continue supplying power to the load.However, if an abnormality such as a voltage drop occurs in the AC power supply, the load is not supplied. There is a danger that becomes impossible.

  A representative embodiment includes a power converter including a converter that converts AC power into DC power, an inverter that converts the converted DC power into AC power, and supplies the AC power to a load. And a bypass circuit connected in parallel, and a DC power supply connected to the DC side of the inverter to supply DC power to the inverter, convert it to AC power and supply it to the load, and power when the AC power supply is normal The power is converted by a conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load. When the AC power source 7 is abnormal, the DC power of the DC power source is supplied by an inverter. In the converter that can be supplied to the load, it is judged whether the failure of the power conversion device is a transient failure or a permanent failure. It is provided with power supply means to enable the supply of power to the load by the power supply to the converter.

 According to a typical embodiment, after an AC overcurrent occurs, an uninterruptible power failure can be determined as a transient failure or a permanent failure by adding a failure determination period using DC voltage and failure determination means. A power supply is obtained.

The figure which shows schematic structure of the uninterruptible power supply of this embodiment. The block diagram for demonstrating the control circuit of FIG. The time chart for demonstrating operation | movement in the case of continuation of an inverter driving | operation in the uninterruptible power supply device of FIG. The time chart for demonstrating operation | movement in the case of the operation stop of an inverter in the uninterruptible power supply of FIG. The schematic block diagram for demonstrating the DC voltage determination means of FIG. The schematic block diagram for demonstrating the failure determination means of FIG. The schematic block diagram for demonstrating an example of the converter of FIG. The schematic block diagram for demonstrating the other example of the converter of FIG. The schematic block diagram for demonstrating one of the inverters of FIG.

  Hereinafter, embodiments will be described with reference to the drawings. In FIG. 1, a typical embodiment is a power converter comprising a converter 2 that converts power from an AC power source 7 into DC power, and an inverter 1 that converts the converted DC power into AC power and supplies it to a load 6. A bypass circuit 12 connected in parallel to the power converter, and a DC power source 4 connected to the DC side of the inverter 1 to supply DC power to the inverter 1 and convert it to AC power and supply it to the load, When the AC power supply 7 is normal, power is converted by the power conversion device to supply power to the load 6. When the power conversion device is abnormal, AC power is supplied from the bypass circuit 12 to the load 6. When the AC power supply 7 is abnormal In the case where the DC power of the DC power supply 4 is converted by the inverter 1 and can be supplied to the load 6, the failure of the power converter is determined to be a transient failure. To the load 6 by the power supply to the inverter 1 are those provided with the power supply means to enable the supply of power.

  Further, it is determined whether the failure of the power conversion device is a transient failure or a permanent failure. If the failure is a transient failure, power can be supplied from the DC power supply 4 to the inverter 1 to supply power to the load 6, and the permanent failure can be detected. In this case, power supply means for stopping operation of the power converter and stopping power supply to the load is provided.

 Hereinafter, a specific embodiment will be described with reference to FIG. The AC power source 7 is connected to an AC switch (AC switch) 5, and the other side of the AC switch 5 is connected to an input of a converter (forward converter) 2 and one of a bypass switch (bypass switch) 3. Converter 2 is connected to DC power supply 4, and the DC output thereof is input to inverter 1. The output of the inverter 1 is connected to one of the bypass switches 3 to be the output of the uninterruptible power supply and connected to the load 6.

 Furthermore, it has the control circuit 80 of the uninterruptible power supply mentioned later, and the inverter 1 and the converter 2 are controlled by the inverter operation signal 21 and the converter operation signal 22. The bypass switch 3 and the AC switch 5 are also operated by a bypass switch operation signal 23 and an AC switch operation signal 27, respectively.

 On the other hand, the AC current detector 8 detects an AC current flowing through the uninterruptible power supply by the AC power supply 7 and outputs an AC current detection signal 24. The AC voltage detector 9a detects an AC voltage supplied to the uninterruptible power supply and outputs an AC voltage detection signal 26. The DC voltage detector 9 b detects the voltage of the DC circuit between the power converter, specifically the converter 2 and the inverter 1, and outputs a DC voltage detection signal 25. The load voltage detector 9c detects an AC voltage supplied to the load 6 of the power converter and outputs a load voltage detection signal 28.

  FIG. 7 is an example of the converter 2, and FIG. 8 is another example of the converter 2. These are composed of a reactor 42, diodes 43, 44, 45, a reactor 46, semiconductor switches 47, 48, 53, 54 such as IGBTs, diodes 49, 50, and capacitors 51, 52.

  FIG. 9 shows an example of the inverter 1, which includes semiconductor switches 55 and 56 and a reactor 57.

 FIG. 2 is a configuration example of the control circuit 80 of the uninterruptible power supply. AC overcurrent detection means 32 composed of a comparator, etc., power failure detection means 33 composed of a comparator, etc., polarity determination means 34 composed of a comparator, etc., failure determination means 35 described later, PWM The inverter gate control means 36 and the converter gate control means 39 comprised of a control circuit, a gate drive circuit, etc., and the bypass switch control means 37 and the AC switch control means 38 comprised of a relay or the like. The terminal voltage of the DC power supply 4 is an arbitrary voltage higher than the voltage across the capacitor 51 (between P and C) and the capacitor 52 (between C and N).

As shown in FIG. 6, the failure determination means 35 outputs an output during a predetermined determination period t1 (FIGS. 3 and 4) when the AC overcurrent detection signal 62 detected by the AC overcurrent detection means 32 is input. The first constant time reference generation circuit (A) 73 that performs the second output that is output during the holding period t2 that is longer than the determination period t1 when the AC overcurrent detection signal 62 detected by the AC overcurrent detection means 32 is input. The first constant time reference generation circuit (B) 74 and the output of the second constant time reference generation circuit (B) 74 and the output 61 of the DC voltage determination means 31 are input, and a signal is output when both outputs are present. For example, an AND circuit, a latch circuit 77 that latches the output of the logic circuit 76, an output from the constant time reference generation circuit (A) 73 and an output from the latch circuit 77 are input, At least one of them exists It provided the Rutoki converter 2 and a second logic circuit 75 for example a logic OR circuit having a gate stop signal, the fault is to determine transient fault or a permanent fault.

  The operation of the converter 2 will be described. When the voltage of the AC power supply 7 is normal, for example, 60% or more of the rated voltage, the AC switch 5 is turned on and the AC power supply 7 is connected to the converter 2. At this time, the polarity determination means 34 determines the polarity of the AC power source 7 using the AC voltage detection signal 26 detected by the AC voltage detector 9a. When the polarity is positive, the semiconductor switch 47 is switched, and when the polarity is negative, the semiconductor switch 48 is switched.

 When the polarity of the AC power supply 7 is positive and the semiconductor switch 47 is turned on by the converter operation signal 22a, a current flows through the path of the AC power supply 7 → the reactor 42 → the diode 43 → the semiconductor switch 47 → the AC power supply 7 and the current flowing through the reactor 42. Increases and is charged as magnetic energy. When the semiconductor switch 47 is turned off, a current flows through the path of the AC power supply 7 → the reactor 42 → the diode 43 → the diode 49 → the capacitor 51 → the AC power supply 7 and the capacitor 51 is charged.

 When the polarity of the AC power supply 7 is negative and the semiconductor switch 48 is turned on by the converter operation signal 22 b, a current flows through the path of the AC power supply 7 → the semiconductor switch 48 → the diode 44 → the reactor 42 → the AC power supply 7. When the semiconductor switch 48 is turned off, current flows through the path of the AC power supply 7 → the capacitor 52 → the diode 50 → the diode 44 → the reactor 42 → the AC power supply 7, and the capacitor 52 is charged.

 By changing the switching time ratio of the semiconductor switch 47 and the semiconductor switch 48, each of the capacitor 51 and the capacitor 52 can be controlled to an arbitrary voltage higher than the peak value of the AC power supply 7.

 When a power failure of the AC power supply 7 is detected by the power failure detection means 33 based on the AC voltage detection signal 26 of the AC voltage detector 9a, the AC switch 5 is turned off by the output 27 of the AC switch control means 38, and the AC power supply 7 Disconnect. The converter gate control means 39 is switched to the operation of supplying a DC voltage by the DC power from the DC power supply 4 by the power failure detection signal 63 of the power failure detection means 33. While the AC power supply 7 is out of power, the polarity determination means 34 sets its output 64 to, for example, 1 and 0 every 1/2 cycle of the output voltage frequency supplied from the inverter 1 to the load 6 by an internal timer or the like. To change. When the output 64 of the polarity determining means 34 is 1, the semiconductor switch 48 is switched, and when the output is 0, the semiconductor switch 47 is switched.

 When the semiconductor switch 48 is turned on, current flows through the path of the DC power supply 4 → the reactor 46 → the diode 45 → the diode 49 → the capacitor 51 → the semiconductor switch 48 → the DC power supply 4, and the capacitor 51 is charged.

 When the semiconductor switch 47 is turned on, a current flows through the path of the DC power supply 4 → the reactor 46 → the diode 45 → the semiconductor switch 47 → the capacitor 52 → the diode 50 → the DC power supply 4, and the capacitor 52 is charged.

 By changing the switching time ratio of the semiconductor switch 47 and the semiconductor switch 48, each of the capacitor 51 and the capacitor 52 can be controlled to an arbitrary voltage lower than the voltage of the DC power supply 4.

  If the AC power supply 7 is healthy based on the output of the power failure detection means 33, the inverter 1 that receives DC power supplied mainly from the output of the converter 2 outputs a desired AC voltage, thereby causing a load from the inverter 1. Power is supplied to 6. If the AC power supply 7 is healthy, the AC power from the AC power supply 7 can be directly supplied to the load 6 via the bypass circuit 12. When an abnormality such as an instantaneous power failure or instantaneous voltage drop occurs in the AC power supply 7, the AC switch 5 is turned off to disconnect the AC power supply side circuit, and the DC power supplied from the DC power supply 4 is used as the input of the inverter 1. Thus, the operation of the inverter 1 can be continued, and the power supply to the load 6 can be uninterrupted.

 Furthermore, in the uninterruptible power supply according to this embodiment, after an AC overcurrent has occurred, the fault determination unit 35 determines the output of the DC voltage determination unit 31 during the determination period, thereby allowing a transient or permanent failure. In the case of a transient failure, the power supply reliability of the uninterruptible power supply can be improved by continuing the power supply from the inverter 1.

  The uninterruptible power supply according to this embodiment includes a forward converter (converter) 2 that converts AC power from an AC power source 7 into DC power, and converts the converted DC power into AC power and supplies it to a load 6. A power converter comprising an inverter (inverter) 1 and a bypass switch 3 connected in parallel to the power converter and connected in series to the circuit to supply AC power directly to the load 6 A bypass circuit 12 and a DC power supply 4 connected to the DC circuit side of the inverter 1 and supplying DC power to the inverter 1 to convert to AC power and supplying the AC power to the load 6 are provided. When the power converter converts power to supply power to the load 6, when the power converter is abnormal, AC power is supplied from the bypass circuit 12 to the load 6, and the AC power source 7 is abnormal. In the case where the DC power of the DC power supply 4 is converted to AC power by the inverter 1 and can be supplied to the load 6, it is determined whether the failure of the power converter is a transient failure or a permanent failure. In the case of a failure, the DC power supply to the inverter 1 is supplied from the DC power source 4 instead of the AC power source so that the power can be supplied to the load 6, and the operation of the power converter is stopped only in the case of a permanent failure. 6 is provided with power supply means for stopping the power supply to 6.

(Configuration of Example)
FIG. 2 is a block diagram showing the internal configuration of the control circuit 80 shown in FIG. 1. The configuration newly added to the conventional uninterruptible power supply is that an AC overcurrent detection signal 62 is input to the AC switch control means 38. The inverter gate control means 36 uses the DC power supply voltage as the failure determination signal 65, and the DC voltage detection signal 25 is input to the DC determination means 31 as a failure determination signal 65. The input to the bypass switch control means 37 and the converter gate stop signal 66 are input to the converter control means 39.

  The DC voltage determination means 31 outputs a DC voltage drop determination signal 61 when the DC voltage detection signal 25 detected by the DC voltage detector 9b is lower than the DC voltage detection reference signal from the setting device 71 as shown in FIG. Is. Specifically, it comprises a DC voltage detection reference signal setting unit 71 for setting a DC voltage detection reference signal, a subtractor and an operational amplifier, and a parator 72 for comparing the DC voltage detection reference signal and the DC voltage detection signal 25. Yes.

 In the configuration of FIG. 5, the DC voltage detection signal 25 is compared with a predetermined DC voltage detection reference signal 71 by a comparator 72, and when the DC voltage detection signal 25 is lower than the DC voltage detection reference signal 71, the DC voltage drop determination signal 61 is output.

  The failure determination means 35 has the following configuration. Specifically, as shown in FIG. 6, when the AC overcurrent detection signal 62 detected by the AC overcurrent detection means 32 is input, the first constant output is output during a predetermined determination period (constant time reference) t1. Second constant time output during the holding period (second constant time reference) t2 when the time reference generation circuit (A) 73 and the AC overcurrent detection signal 62 detected by the AC overcurrent detection means 32 are input. When both the reference generation circuit (B) 74 and the signal output during the holding period t2 from the fixed time reference generation circuit (B) 74 and the DC voltage drop determination signal 61 from the DC voltage determination means 31 exist, a failure determination is made. There is a signal from one of the second logic circuit 76 that outputs a signal, for example, an AND circuit, a latch circuit 77 that latches the output of the logic circuit 76, the latch circuit 77, and the constant time reference generation circuit (A) 73. When converter It is made of the second logic circuit 75 for example logical sum circuit which outputs the operation stop signal 66 to.

 In FIG. 6, when the AC overcurrent detection signal 62 is input, the converter gate stop signal 66 is output during the determination time t1 set by the first constant time reference generation circuit (A) 73, and the converter 2 Stop. The second constant time reference generation circuit (B) 74 also outputs a signal during the holding period t2. If there is no input of the DC voltage determination signal 61 during this period, the converter gate stop signal 66 is canceled and the converter 2 is operated. Resumed. At this time, the AC switch control means 38 turns off the AC switch 5 and switches to the operation of operating the converter 2 with the DC power from the DC power supply 4 (DC → DC). While the converter 2 is stopped, the direct current power charged in the capacitor 51 and the capacitor 52 is consumed by the inverter 1 and the direct current voltage is lowered. Therefore, this operation is continued until the direct current voltage is charged. . After the charging of the DC voltage is completed, the operation (AC → DC) in which the converter 2 supplies DC power with the power from the AC power supply 7 is switched, and the normal operation is resumed. With this operation, the power supply to the load 6 can be continued without stopping the inverter 1.

 If the DC voltage determination signal 61 is input while the fixed time reference generation circuit (B) 74 is output, it is determined that a failure has occurred in the uninterruptible power supply, and the failure state is latched. While latching in the circuit 77, both the failure determination signal 65 and the converter gate stop signal 66 are output. When the failure determination signal 65 is output, the inverter gate control unit 36 stops the operation of the inverter 1, and the bypass switch 3 is turned on by the bypass switch operation signal 23 output from the bypass switch control unit 37. The converter control means 39 stops the operation of the converter 2 by the converter gate stop signal 66.

(Effect of embodiment)
When an AC overcurrent occurs in the operation of the uninterruptible power supply device described above, it is possible to determine whether the failure is a transient failure or a permanent failure by the failure determination period and the failure determination means 35. As a result, the inverter 1 can be stopped only when it is determined as a permanent failure. Accordingly, the inverter 1 is not stopped more than necessary, so that the reliability of power supply to the load 6 can be improved.

 In the uninterruptible power supply according to the embodiment described above, when an AC overcurrent is detected by the AC overcurrent detection unit 32, the failure determination unit 35 causes the DC voltage determination unit 31 to execute a DC voltage during a predetermined determination period. A transient failure or a permanent failure is determined using an output indicating whether or not the instantaneous value is within a predetermined range. If the determination result is a transient failure, the power supply to the inverter 1 is switched to the DC power supply 4.

  The concept of this operation will be described with reference to FIG. 3 when the operation of the inverter 1 can be continued, and FIG. 4 when the operation of the inverter 1 is stopped. When the AC overcurrent detection means 32 detects an AC overcurrent failure at point A, the converter gate control means 39 stops the semiconductor switch 47 and the semiconductor switch 48 by the converter gate stop signal 66.

 The failure determination unit 35 determines the output of the DC voltage determination unit 31 during a predetermined determination period t1. The determination period t1 may be about ½ cycle of the AC power supply 7 (10 ms if 50 Hz). If the DC voltage determination means 31 does not detect an abnormality even after the determination period t1 has elapsed, the failure determination means 35 determines that it is a transient failure and does not change the failure determination signal 65, and restarts the operation of the converter 2. (Point B). At this time, the semiconductor switch 47 and the semiconductor switch 48 are switched from the converter gate control means 39 so as to charge the capacitor 51 and the capacitor 52 using the DC power from the DC power supply 4. After the charging of the DC voltage is completed, the operation of the converter 2 is switched so that the uninterruptible power supply operates with the electric power from the AC power supply 7, and the normal operation is resumed (point C). With this operation, even when an input overcurrent is detected, it is possible to supply power to the load 6 without stopping the inverter 1.

 The constant time reference generation circuit (B) 74 holds that the AC overcurrent failure is detected for a predetermined holding period t2 after detecting the AC overcurrent failure. The holding period t2 is determined in consideration of the time for which the inverter 1 consumes the DC power charged in the capacitor 51 and the capacitor 52 before the failure occurs, and may be, for example, about 10 to 30 seconds. If there is no change in the failure determination signal 65 that is the output of the failure determination means 35, and the converter 2 starts operation, the output of the DC voltage determination means 31 shows an abnormality within the holding period t2, a semiconductor switch or the like Therefore, the failure determination means 35 determines that the failure is a permanent failure, and outputs a failure determination signal 65. At this time, the inverter device 1 and the converter 2 are stopped, and the bypass switch 3 is turned on, whereby the AC power of the AC power source 7 is supplied to the load 6 through the bypass circuit 12 (D point). With this operation, the load 6 can be uninterrupted, and a permanent failure of the uninterruptible power supply can be determined.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

 The DC power source 4 may be a DC / DC converter, a storage battery, or the like as long as a DC voltage source can be configured. A circuit from the input branch point 10 to the output connection point 11 through the bypass switch 3 shown in FIG. There is no limitation on the configuration of the bypass switch 3, but there is an example in which the bypass switch 3 is composed of a semiconductor, a mechanical switch, or both of them.

 The aforementioned power supply means mainly includes the aforementioned DC voltage determination means 31, AC overcurrent detection means 32, failure determination means 35, inverter gate control means 36, bypass switch control means 37 and AC switch control means 38. The converter gate control means 39 may be used.

 DESCRIPTION OF SYMBOLS 1 ... Inverter, 2 ... Converter, 3 ... Bypass switch, 4 ... DC power supply, 5 ... AC switch, 6 ... Load, 7 ... AC power supply, 8 ... AC current detector, 9a ... AC voltage detector, 9b ... DC voltage Detector: 9c ... Load voltage detector, 10 ... Input branch point, 11 ... Output branch point, 12 ... Bypass circuit, 21 ... Inverter operation signal, 22 ... Converter operation signal, 23 ... Bypass switch operation signal, 24 ... AC current Detection signal 25 ... DC voltage detection signal 26 ... AC voltage detection signal 27 ... AC switch operation signal 28 ... Load voltage detection signal 31 ... DC voltage determination means 32 ... AC overcurrent detection means 33 ... Power failure detection Means 34... Polarity determination means 35. Failure determination means 36 36 inverter gate control means 37 37 bypass switch control means 38 38 AC switch control means 39 Converter gate control means, 41 ... capacitor, 42 ... reactor, 43 ... diode, 44 ... diode, 45 ... diode, 46 ... reactor, 47 ... semiconductor switch, 48 ... semiconductor switch, 49 ... diode, 50 ... diode, 51 ... capacitor , 52 ... capacitor, 53 ... semiconductor switch, 54 ... semiconductor switch, 55 ... semiconductor switch, 56 ... semiconductor switch, 57 ... reactor, 58 ... capacitor, 61 ... DC voltage drop determination signal, 62 ... AC overcurrent detection signal, 63 ... blackout detection signal, 64 ... polarity judgment signal, 65 ... failure judgment signal, 66 ... converter gate stop signal, 71 ... DC voltage detection reference signal setter, 72 ... comparator, 73 ... constant time reference generation circuit (A), 74 ... fixed time reference generation circuit (B), 75 ... logical sum circuit, 76 ... theory AND circuit, 77 ... latch circuit, 80 ... control circuit.

Claims (6)

A converter that converts AC power of an AC power source into DC power, and a power converter that includes an inverter that converts the converted DC power into AC power and supplies the load to a load; and
A bypass circuit connected in parallel to the power converter;
A DC power source connected to the DC side of the inverter and supplying DC power to the inverter to convert it to AC power and supplying the load;
When the AC power supply is normal, power is converted by the power conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load, and the AC power supply is abnormal. When the DC power of the DC power source is converted by the inverter and can be supplied to the load,
A power supply means for determining that the failure of the power converter is a transient failure, and in the case of the transient failure, supplying power to the inverter by supplying power from the DC power supply to the inverter; An uninterruptible power supply. A converter that converts AC power of an AC power source into DC power, and a power converter that includes an inverter that converts the converted DC power into AC power and supplies the load to a load; and
A bypass circuit connected in parallel to the power converter;
A DC power source connected to the DC side of the inverter and supplying DC power to the inverter to convert it to AC power and supplying the load;
When the AC power supply is normal, power is converted by the power conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load, and the AC power supply is abnormal. When the DC power of the DC power source is converted by the inverter and can be supplied to the load,
It is determined whether a failure of the power conversion device is a transient failure or a permanent failure. In the case of the transient failure, power is supplied from the DC power source to the inverter so that power can be supplied to the load. An uninterruptible power supply comprising an electric power supply means for stopping the operation of the power converter and stopping the supply of electric power to the load only when a permanent failure occurs. A converter that converts AC power of an AC power source into DC power, and a power converter that includes an inverter that converts the converted DC power into AC power and supplies the load to a load; and
A bypass circuit connected in parallel to the power converter;
A DC power source connected to the DC side of the inverter and supplying DC power to the inverter to convert it to AC power and supplying the load;
When the AC power supply is normal, power is converted by the power conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load, and the AC power supply is abnormal. In the uninterruptible power supply device, in which the DC power of the DC power supply is converted by the inverter and can be supplied to the load.
When said AC overcurrent from the AC power source is detected, a predetermined judgment period, stops the operation of the converter, the converter and the instantaneous value of the DC voltage between the inverter is preset at the constant It is determined whether it is within the range, and when it is determined that it is within the predetermined range, it is determined as a transient failure, the operation of the converter is restarted, and the power supply to the inverter is switched to the DC power supply side. An uninterruptible power supply comprising the means. A converter that converts AC power of an AC power source into DC power, and a power converter that includes an inverter that converts the converted DC power into AC power and supplies the load to a load; and
A bypass circuit connected in parallel to the power converter;
A DC power source connected to the DC side of the inverter and supplying DC power to the inverter to convert it to AC power and supplying the load;
When the AC power supply is normal, power is converted by the power conversion device to supply power to the load. When the power conversion device is abnormal, AC power is supplied from the bypass circuit to the load, and the AC power supply is abnormal. In the uninterruptible power supply device, in which the DC power of the DC power supply is converted by the inverter and can be supplied to the load.
When an AC overcurrent from the AC power supply is detected, the converter is stopped during a predetermined determination period, and the instantaneous value of the DC voltage between the converter and the inverter is within a predetermined range. A means for determining whether or not the inverter and the converter are stopped when it is not within the predetermined range and when this continues for a holding period longer than the determination period. An uninterruptible power supply. A converter that converts AC power from an AC power source into DC power;
An inverter that converts the DC power converted by the converter into AC power and supplies the load to the load;
A DC power supply for supplying DC power to the inverter when the AC power supply is abnormal;
An AC switch that opens and closes an electrical circuit between the AC power source and the converter;
A bypass circuit connected in parallel to the converter and the inverter;
A bypass switch for opening and closing the circuit of the bypass circuit;
An AC voltage detector for detecting an AC voltage of the AC power supply;
An alternating current detector for detecting an alternating current input to the converter;
A DC voltage detector for detecting the DC voltage of the converter;
A load voltage detector for detecting a voltage supplied to the load;
A power failure detection means for detecting a power failure of the AC power source based on an AC voltage detection signal detected by the AC voltage detector;
AC overcurrent detection means for outputting an AC overcurrent detection signal when the AC current detection signal detected by the AC current detector is overcurrent during a predetermined determination period;
DC voltage determination means for outputting a DC voltage drop determination signal when the DC voltage detection signal detected by the DC voltage detector is lower than the DC voltage detection reference signal;
Between the AC overcurrent is detected by the detection means that said AC overcurrent predetermined determination period when inputting the detection signal, it stops the operation of the converter, to determine the output of the DC voltage determining means, the determination If the continued period did not determine an abnormality of the output of the DC voltage determining means, and failure determination means and a latch circuit which judges a transient fault, to latch the fault determination signal,
Inverter control means for continuing operation with respect to the inverter by the output of the latch circuit;
Converter control means for restarting operation of the converter by the output of the latch circuit;
An uninterruptible power supply characterized by comprising: A converter that converts AC power from an AC power source into DC power;
An inverter that converts the DC power converted by the converter into AC power and supplies the load to the load;
A DC power supply for supplying DC power to the inverter when the AC power supply is abnormal;
An AC switch that opens and closes an electrical circuit between the AC power source and the converter;
A bypass circuit connected in parallel to the converter and the inverter;
A bypass switch for opening and closing the circuit of the bypass circuit;
An AC voltage detector for detecting an AC voltage of the AC power supply;
An alternating current detector for detecting an alternating current input to the converter;
A DC voltage detector for detecting the DC voltage of the converter;
A load voltage detector for detecting a voltage supplied to the load;
A power failure detection means for detecting a power failure of the AC power source based on an AC voltage detection signal detected by the AC voltage detector;
AC overcurrent detection means for outputting an AC overcurrent detection signal when the AC current detection signal detected by the AC current detector is an overcurrent;
DC voltage determination means for outputting a DC voltage drop determination signal when the DC voltage detection signal detected by the DC voltage detector is lower than the DC voltage detection reference signal;
Between the AC overcurrent is detected by the detection means is said AC when entering the overcurrent detection signal a predetermined determination period, first a constant time reference generating circuit for outputting, detected by the AC overcurrent detecting means A second constant-time reference generation circuit that outputs during a holding period longer than the determination period when the AC overcurrent detection signal is input, an output of the second constant-time reference generation circuit, and the DC voltage determination means A first logic circuit that inputs an output and outputs a signal when both outputs are present; a latch circuit that latches an output of the first logic circuit; an output from the first constant-time reference generation circuit; inputs the output from the latch circuit, at least one of a second logic circuit that to output the gate stop signal to the converter when the present, the fault is transient fault or a permanent fault of the output Or And failure determining means for constant,
An uninterruptible power supply comprising:

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