No power outage device

Abstract

The uninterruptible power supply (100) comprises a plurality of UPS modules connected in parallel to each other between an AC power source (1) and a load (2). The plurality of UPS modules have equal capacities. The plurality of UPS modules includes a first UPS module group (5A) having N first UPS modules (A) and a second UPS module group (5B) having M second UPS modules (B). A first energy storage device (3) is connected to the first UPS module (A). A second energy storage device (4) is connected to the second UPS module (B). The first energy storage device (3) has a higher energy density than the second energy storage device (4). The second energy storage device (4) has a higher power density than the first energy storage device (3). N + M is equal to the number obtained by dividing the maximum power consumption of the load by the capacity per UPS module. N is equal to the number obtained by dividing the steady-state component of the power consumption of the load by the capacity per UPS module.

Description

Technical Field

[0004] , , , , , , ,

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[0001] The present disclosure relates to an uninterruptible power supply device.

Background Art

[0002] In recent years, with the spread of AI (Artificial Intelligence) and IOT (Internet Of Things) technologies, the demand for data centers that support these technologies has been rapidly expanding. In a data center, due to the synchronized operation of multiple servers, etc., the power consumption of the load may periodically fluctuate. In an uninterruptible power supply device applied to such a data center, the input power required from the power system also periodically fluctuates along with the periodic fluctuation of the power consumption of the load. There is concern that the large-scale expansion of data centers may cause instability in the power system.

[0003] For example, Japanese Unexamined Patent Application Publication No. 2007-60796 (Patent Document 1) discloses a power buffer device system having an uninterruptible power supply function and a load leveling function. The system includes a constant inverter power supply unit that converts commercial power system AC power once and then converts it into desired AC power to supply power to a load, an instantaneous power type power buffer capable of instantaneous charge and discharge, a sustained power type power buffer capable of storing a large amount of power, a first bidirectional DC / DC converter that converts power between the DC bus of the constant inverter power supply unit and the instantaneous power type power buffer, and a second bidirectional DC / DC converter that converts power between the DC bus and the sustained power type power buffer.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above power buffer system, under normal conditions of the commercial power grid, load fluctuations occurring at the load are input and output to the instantaneous power buffer. In the event of a commercial power outage, the commercial power grid is disconnected from the inverter power supply unit, and power is supplied to the load from the sustained power buffer.

[0006] Therefore, the system requires the selection of a power buffer with instantaneous power capacity capable of handling rapid load fluctuations. Furthermore, it requires the selection of a power buffer with sustained power capacity capable of continuously supplying power for a predetermined period after a commercial power outage.

[0007] On the other hand, the power consumption fluctuation patterns of a load vary widely depending on the load. Therefore, for loads with large power consumption fluctuations, a power buffer with instantaneous power may not be able to adequately absorb the load fluctuations. Also, for loads with high power consumption, the power stored in a power buffer with sustained power may be depleted during a power outage in the commercial grid. For this reason, a system that can flexibly respond to various load fluctuation patterns is required.

[0008] This disclosure is made to solve the above-mentioned problems, and the purpose of this disclosure is to provide an uninterruptible power supply that can stabilize the power system by flexibly responding to fluctuations in the power consumption of the load. [Means for solving the problem]

[0009] An uninterruptible power supply according to one aspect of this disclosure comprises a plurality of UPS (Uninterruptible Power Supply) modules connected in parallel to each other between an AC power source and a load. The plurality of UPS modules have equal capacities. The plurality of UPS modules includes a first group of UPS modules having N first UPS modules and a second group of UPS modules having M second UPS modules. A first energy storage device is connected to the first UPS modules. A second energy storage device is connected to the second UPS modules. The first energy storage device has a higher energy density than the second energy storage device. The second energy storage device has a higher power density than the first energy storage device. N + M is equal to the number obtained by dividing the maximum power consumption of the load by the capacity per UPS module. N is equal to the number obtained by dividing the steady-state component of the power consumption of the load by the capacity per UPS module. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide an uninterruptible power supply that can stabilize the power grid by flexibly responding to fluctuations in the power consumption of the load. [Brief explanation of the drawing]

[0011] [Figure 1] This is a circuit block diagram showing the overall configuration of an uninterruptible power supply according to an embodiment of the present disclosure. [Figure 2] This is a circuit block diagram showing the configuration of the first UPS module. [Figure 3] Block diagram showing an example of the hardware configuration of the first control device. [Figure 4] This is a block diagram showing the main components of the first control device. [Figure 5] This block diagram shows the portion of the control circuit shown in Figure 4 that is related to inverter control. [Figure 6] This is a circuit block diagram showing the configuration of the second UPS module. [Figure 7] A block diagram showing an example of the hardware configuration of the second control unit. [Figure 8] It is a block diagram showing the main part of the second control device. [Figure 9] It is a block diagram showing a part related to the control of the inverter in the control circuit shown in FIG. 8. [Figure 10] It is a block diagram showing a part related to the control of the converter in the control circuit shown in FIG. 8. [Figure 11] It is a block diagram showing the configuration of a part related to the control of the bidirectional chopper in the control circuit shown in FIG. 8. [Figure 12] It is a circuit block diagram showing a first configuration example of the uninterruptible power supply device. [Figure 13] It is a time chart showing the operation of the uninterruptible power supply device. [Figure 14] It is a time chart showing the operation of the uninterruptible power supply device. [Figure 15] It is a time chart showing the operation of the second UPS module group. <图00000 [Figure 16] It is a circuit block diagram showing a second configuration example of the uninterruptible power supply device. [Figure 17] It is a time chart showing the operation of the uninterruptible power supply device.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated in principle.

[0013] <Overall Configuration of Uninterruptible Power Supply Device> FIG. 1 is a circuit block diagram showing the overall configuration of an uninterruptible power supply device according to an embodiment of the present disclosure. As shown in FIG. 1, the uninterruptible power supply device 100 according to the present embodiment includes a plurality of UPS (Uninterruptible Power Supply) modules A1 to AN and B1 to BM connected in parallel to each other between an AC power supply 1 and a load 2. N and M are integers of 1 or more. The AC power supply 1 is, for example, a power grid.

[0014] Although the uninterruptible power supply 100 actually receives three-phase AC power from the AC power source 1 and supplies three-phase AC power to the load 2, only a single-phase circuit is shown in Figure 1 for the sake of simplicity in the diagram and explanation.

[0015] Load 2 is driven by AC power supplied from the uninterruptible power supply 100. Load 2 includes, for example, electrical equipment used in data sensors (servers, storage, and air conditioning equipment). In this embodiment, the power consumption PL of Load 2 (hereinafter also referred to as "load power") fluctuates periodically due to the synchronous operation of multiple electrical devices, etc.

[0016] In the following explanation, the maximum power consumption of load 2 will be referred to as PLmax. Furthermore, the steady-state component of the load power PL, which does not change over time, will be referred to as PLst, while the fluctuating component, which changes over time, will be referred to as PLva.

[0017] Multiple UPS modules A1-AN and B1-BM have equal capacities. If the capacity of one UPS module is X, the total number of UPS modules N+M installed in the uninterruptible power supply 100 is set to be equal to the maximum power consumption PLmax divided by X (N+M = PLmax / X). For example, if the maximum power consumption PLmax is equal to the rated load (100% load factor) of the uninterruptible power supply 100, and the capacity of one UPS module corresponds to a load factor of 10%, then the total number of UPS modules (N+M) is set to 100(%) ÷ 10(%) = 10 modules (see Figures 12 and 16 described later).

[0018] N UPS modules A1 to AN constitute UPS module group 5A. M UPS modules B1 to BM constitute UPS module group 5B. In the following description, UPS modules A1 to AN may be collectively referred to as "UPS module A," and UPS modules B1 to BM may be collectively referred to as "UPS module B." UPS module A corresponds to one embodiment of the "first UPS module," and UPS module group 5A corresponds to one embodiment of the "first UPS module group." UPS module B corresponds to one embodiment of the "second UPS module," and UPS module group 5B corresponds to one embodiment of the "second UPS module group."

[0019] UPS module A includes an input terminal T1A, a DC terminal T2A, and an output terminal T3A. Input terminal T1A receives AC power at a predetermined frequency (e.g., commercial frequency) from an AC power source 1. Output terminal T3A is connected to load 2. DC terminal T2A is connected to battery 3.

[0020] The UPS module group 5A has an input node ND to which the input terminal T1A of UPS modules A1 to AN is commonly connected, and an output node NB to which the output terminal T3A of UPS modules A1 to AN is commonly connected.

[0021] UPS module B includes an input terminal T1B, a DC terminal T2B, and an output terminal T3B. Input terminal T1B receives AC power of a predetermined frequency from AC power supply 1. Output terminal T3B is connected to load 2. DC terminal T2B is connected to electric double layer capacitor (EDLC) 4.

[0022] The UPS module group 5B has an input node NE to which the input terminal T1B of UPS modules B1 to BM is commonly connected, and an output node NC to which the output terminal T3B of UPS modules B1 to BM is commonly connected.

[0023] The uninterruptible power supply 100 has an input node NF to which the input node ND of UPS module group 5A and the input node NE of UPS module group 5B are commonly connected, and an output node NA to which the output node NB of UPS module group 5A and the output node NC of UPS module group 5B are commonly connected.

[0024] UPS module A and UPS module B have the same basic configuration, but the type of energy storage device connected to them is different. In the example in Figure 1, battery 3 is connected to UPS module A, and EDLC 4 is connected to UPS module B.

[0025] The type of energy storage device connected to the UPS module can be selected according to the required output performance of the UPS module. In this embodiment, as will be described later, the UPS module group 5A is configured to output power equivalent to the steady-state component PLst of the load power. In this configuration, if an abnormality occurs in the AC power supply 1, the UPS module A is required to use the power stored in the energy storage device connected to the UPS module A (hereinafter referred to as the "first energy storage device") to stably output power equivalent to the steady-state component PLst for a predetermined power outage compensation time. The power outage compensation time is the time during which power can be continuously supplied from the uninterruptible power supply 100 to the load 2 in the event of a power outage. For this reason, it is preferable to use an energy storage device with a high energy density (amount of energy that can be stored per unit weight or volume) as the first energy storage device. Battery 3 is suitable as the "first energy storage device".

[0026] On the other hand, in this embodiment, the UPS module group 5B is configured to output power corresponding to the fluctuating component PLva of the load power. In this configuration, the power stored in the energy storage device connected to the UPS module B (hereinafter referred to as the "second energy storage device") is used to compensate for fluctuations in the load power PL. For this reason, it is preferable that the second energy storage device is an energy storage device with a high power density (the amount of power that can be instantaneously extracted per unit weight or volume).

[0027] Compared with the battery 3, the EDLC 4 has inferior energy density but superior output density. In addition, the EDLC 4 has the characteristic of less deterioration due to repeated charge and discharge at high current compared with the battery 3. In response to the fluctuation of the load power PL, instantaneous large-current discharge is required for the second power storage device. In addition, it is required that the second power storage device has less deterioration due to repeated charge and discharge even when the load power PL fluctuates periodically. Therefore, the EDLC 4 is suitable as the "second power storage device".

[0028] Note that the first power storage device is not limited to the battery 3 as long as it has higher energy density than the second power storage device. In addition, the second power storage device is not limited to the EDLC 4 as long as it has higher output density than the first power storage device.

[0029] The uninterruptible power supply device 100 further includes a current detector CD1. The current detector CD1 detects the load current IL flowing from the uninterruptible power supply device 100 to the load 2 and gives a signal ILf indicating the detected value to the UPS modules A and B.

[0030] <Configuration of UPS Module A> FIG. 2 is a circuit block diagram showing the configuration of the UPS module A. As shown in FIG. 2, the UPS module A further includes a converter 10, a DC line 11, a capacitor 12, a bidirectional chopper 14, an inverter 16, switches S1 to S3, current detectors CD2A to CD4A, and a control device 18.

[0031] The switch S1 is connected between the input terminal T1A and the AC node of the converter 10 and is controlled by the control device 18. When AC power is normally supplied from the AC power supply 1 (when the AC power supply 1 is healthy), the switch S1 is turned on, and AC power is supplied from the AC power supply 1 to the converter 10 through the switch S1. When AC power is not normally supplied from the AC power supply 1 (when the AC power supply 1 is abnormal), the switch S1 is turned off, and the connection between the AC power supply 1 and the converter 10 is interrupted.

[0032] The instantaneous value of the AC input voltage VIA supplied from the AC power supply 1 is detected by the control device 18. Based on the instantaneous value of the AC input voltage VIA, the control device 18 determines whether the AC power supply 1 is healthy or abnormal. The current detector CD2A detects the AC input current IiA flowing between the AC power supply 1 and the converter 10 and provides the control device 18 with a signal IiAf indicating the detected value.

[0033] The converter 10 is controlled by the control device 18 and, when the AC power supply 1 is healthy, converts the AC power from the AC power supply 1 to DC power and outputs it to the DC line 11. The converter 10 is a well-known one that includes multiple sets of semiconductor switching elements and diodes. The converter 10 corresponds to one embodiment of the "first converter".

[0034] Capacitor 12 is connected to DC line 11 and smooths and stabilizes the DC voltage VDA of DC line 11. The instantaneous value of the DC voltage VDA of DC line 11 is detected by control device 18.

[0035] When AC power supply 1 is functioning correctly, the control device 18 controls the converter 10 so that the DC voltage VDA of DC line 11 becomes the reference DC voltage VDR. When AC power supply 1 malfunctions, the control device 18 stops the operation of the converter 10.

[0036] The DC line 11 is connected to the DC terminal T2A via the bidirectional chopper 14 and switch S2. Switch S2 is controlled by the control device 18. When UPS module A is in use, switch S2 is turned on. When the battery 3 or bidirectional chopper 14 is being maintained, switch S2 is turned off.

[0037] The instantaneous value of the terminal voltage VB of battery 3 (hereinafter referred to as "battery voltage") is detected by the control device 18. The current detector CD3A detects the DC current IB (hereinafter referred to as "battery current") flowing between battery 3 and the bidirectional chopper 14, and provides the control device 18 with a signal IBf indicating the detected value.

[0038] The bidirectional chopper 14 is controlled by the control device 18 and exchanges DC power between the DC line 11 and the battery 3. The bidirectional chopper 14 is a well-known type that includes multiple sets of semiconductor switching elements and diodes, and a reactor. The bidirectional chopper 14 corresponds to one embodiment of the "first bidirectional chopper".

[0039] When AC power supply 1 is functioning correctly, the control device 18 basically controls the bidirectional chopper 14 so that the battery voltage VB becomes the reference DC voltage VBR. The reference DC voltage VBR can be set based on the battery voltage VB when battery 3 is in a predetermined fully charged state. When AC power supply 1 malfunctions, the control device 18 controls the bidirectional chopper 14 so that the DC voltage VDA of DC line 11 becomes the reference DC voltage VDR.

[0040] The DC line 11 is connected to the DC node of the inverter 16, and the AC node of the inverter 16 is connected to output terminal T3A via switch S3. Switch S3 is controlled by the control device 18. When UPS module A is used, switch S3 is turned on. During maintenance of the inverter 16, switch S3 is turned off.

[0041] The current detector CD4A detects the AC output current IOA of the inverter 16 and provides the control device 18 with a signal IOAf indicating the detected value. The instantaneous value of the AC output voltage VOA applied from the UPS module A to the load 2 is detected by the control device 18.

[0042] The inverter 16 is controlled by the control device 18 and converts the DC power supplied from the converter 10 or bidirectional chopper 14 via the DC line 11 into AC power of a predetermined frequency (e.g., commercial frequency) and supplies it to the load 2. The inverter 16 is a well-known one comprising multiple sets of semiconductor switching elements and diodes. The inverter 16 corresponds to one embodiment of the "first inverter".

[0043] When AC power supply 1 is functioning correctly, inverter 16 converts the DC power supplied from converter 10 into AC power and supplies it to load 2. When AC power supply 1 malfunctions, inverter 16 converts the DC power supplied from bidirectional chopper 14 into AC power and supplies it to load 2. At this time, control device 18 controls inverter 16 so that the AC output voltage VOA becomes the reference AC voltage VOR.

[0044] The control device 18 controls switches S1 to S3, converter 10, bidirectional chopper 14, and inverter 16 based on the AC input voltage VIA, AC output voltage VOA, DC voltage VDA, battery voltage VB, AC input current IiA, battery current IB, and AC output current IOA, etc.

[0045] (Example of hardware configuration of control device 18) Figure 3 is a block diagram showing an example of the hardware configuration of the control device 18. Typically, the control device 18 can be configured by a microcomputer with a predetermined program pre-stored in it.

[0046] As shown in Figure 3, the control unit 18 comprises a CPU (Central Processing Unit) 180, a memory 182, and an input / output (I / O) circuit 184. The CPU 180, memory 182, and I / O circuit 184 can exchange data with each other via a bus 186. A program is stored in a portion of the memory 182, and the CPU 180 can execute this program to realize various functions described later. The I / O circuit 184 exchanges signals and data between the control unit 18 and external devices.

[0047] Alternatively, unlike the example in Figure 3, at least a portion of the control device 18 can be configured using circuits such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). Furthermore, at least a portion of the control device 18 can also be configured using analog circuits.

[0048] (Functional configuration of the control device 18) Figure 4 is a block diagram showing the main components of the control device 18. As shown in Figure 4, the control device 18 comprises voltage detectors 30-33, anomaly detector 34, and control circuit 35, and controls the entire UPS module A. Each functional block shown in Figure 4 can be implemented by program, hardware, or a combination thereof.

[0049] The voltage detector 30 detects the instantaneous value of the AC input voltage VIA supplied from the AC power supply 1 and outputs a signal VIAf indicating the detected value to the control circuit 35.

[0050] The voltage detector 31 detects the instantaneous value of the AC output voltage VOA applied to the load 2 and outputs a signal VOAf indicating the detected value to the control circuit 35.

[0051] The voltage detector 32 detects the instantaneous value of the DC voltage VDA on the DC line 11 and outputs a signal VDAf indicating the detected value to the control circuit 35.

[0052] The voltage detector 33 detects the instantaneous value of the terminal voltage (battery voltage) VB of the battery 3 and outputs a signal VBf indicating the detected value to the control circuit 35.

[0053] The abnormality detector 34 detects whether an abnormality has occurred in the AC power supply 1 based on the output signal VIAf of the voltage detector 30, and outputs an abnormality detection signal DET to the control circuit 35 indicating the detection result. If the AC power supply 1 is healthy, the abnormality detection signal DET is set to the deactivation level L. If an abnormality has occurred in the AC power supply 1, the abnormality detection signal DET is set to the activation level H.

[0054] For example, if the AC input voltage VIA is within the normal range, the anomaly detector 34 determines that the AC power supply 1 is healthy and sets the anomaly detection signal DET to a low level. If the AC input voltage VIA is outside the normal range, the anomaly detector 34 determines that an anomaly has occurred in the AC power supply 1 and sets the anomaly detection signal DET to a high level.

[0055] The control circuit 35 controls the UPS module A based on the output signals VIAf, VOAf, VDAf, VBf from voltage detectors 30-33, the output signals ILf, IiAf, IBf, IOAf from current detectors CD1, CD2A-CD4A, and the anomaly detection signal DET, etc.

[0056] Specifically, when AC power supply 1 is healthy (DET=L), control circuit 35 controls converter 10 so that the DC voltage VDA of DC line 11 becomes the reference DC voltage VDR, and controls bidirectional chopper 14 so that the battery voltage VB becomes the reference DC voltage VBR. Control circuit 35 also controls inverter 16 so that the AC output voltage VOA becomes the reference AC voltage VOR.

[0057] If AC power supply 1 is abnormal (DET=H), the control circuit 35 turns off switch S1, stops the operation of converter 10, and controls the bidirectional chopper 14 so that the DC voltage VDA of DC line 11 becomes the reference DC voltage VDR. The control circuit 35 also controls the inverter 16 so that the AC output voltage VOA becomes the reference AC voltage VOR.

[0058] Figure 5 is a block diagram showing the portion of the control circuit 35 related to the control of the inverter 16. As shown in Figure 5, the control circuit 35 is composed of a load power calculation unit 350, an LPF (Low Pass Filter) 352, a power distribution calculation unit 354, a power control unit 356, subtractors 358 and 364, a voltage control unit 360, an adder 362, a current control unit 366, and a PWM (Pulse Width Modulation) circuit 368.

[0059] The load power calculation unit 350 calculates the load power PL based on the load current IL indicated by the output signal ILf of the current detector CD1 and the AC output voltage VOA detected by the voltage detector 31.

[0060] The LPF352 is a circuit for calculating the steady-state component PLst of the load power from the load power PL calculated by the load power calculation unit 350. Specifically, the LPF352 extracts frequency components lower than the cutoff frequency fc from the calculated load power PL. Preferably, the cutoff frequency fc of the LPF352 is set to be sufficiently lower than the fluctuating frequency of the load power PL. In this way, the LPF352 can extract the steady-state component PLst from the periodically fluctuating load power PL. The extracted steady-state component PLst is provided to the power sharing calculation unit 354 as the target output power of the UPS module group 5A.

[0061] The power distribution calculation unit 354 generates the output power command value Pa* for the operating UPS module A by dividing the target output power PLst by the number of operating UPS module A units n. When the number of operating UPS module A units n is equal to the number of UPS module A units N (n=N), the output power command value Pa* for UPS module A = PLst / N.

[0062] The power control unit 356 generates a current command value IOA1 from the output power command value Pa* of the UPS module A. Specifically, the power control unit 356 generates the current command value IOA1 by dividing the output power command value Pa* by the AC output voltage VOA detected by the voltage detector 31. The generated current command value IOA1 corresponds to the current that the UPS module A should supply to the load 2.

[0063] The subtractor 358 calculates the difference ΔVOA = VOR - VOA between the reference AC voltage VOR and the AC output voltage VOA detected by the voltage detector 31.

[0064] The voltage control unit 360 generates a current command value IOA2 so that the deviation ΔVOA disappears. For example, the voltage control unit 360 generates the current command value IOA2 by performing proportional operation or proportional integral operation on the deviation ΔVOA.

[0065] The adder 362 adds the current command value IOA1 from the power control unit 356 and the current command value IOA2 from the voltage control unit 360 to generate a current command value IOA* = IOA1 + IOA2. The current command value IOA* corresponds to the command value of the AC output current IOA of the inverter 16.

[0066] The current command value IOA1 corresponds to the feed-forward component of the current command value IOA*. By introducing the feed-forward component IOA1 corresponding to the shared current of the UPS module A into the current command value IOA*, it is possible to output from the inverter 16 an AC output current IOA including a feedback component IOA2 having a value corresponding to the deviation ΔVOA and the feed-forward component IOA1. According to this, while synchronizing the AC output voltage VOA of the UPS module A and the AC output voltage VOB of the UPS module B with each other, it is possible to supply the shared power Pa* to the load 2.

[0067] The subtracter 364 obtains a deviation ΔIOA = IOA* - IOA between the current command value IOA* and the AC output current IOA indicated by the output signal IOAf of the current detector CD4A.

[0068] The current control unit 366 generates a voltage command value VOA* so that the deviation ΔIOA disappears. For example, the current control unit 366 generates the voltage command value VOA* by performing proportional operation or proportional integral operation on the deviation ΔIOA.

[0069] The PWM circuit 368 generates a PWM signal according to the voltage command value VOA* and controls the inverter 16 with the PWM signal.

[0070] <Configuration of UPS Module B> Figure 6 is a circuit block diagram showing the configuration of UPS module B. As shown in Figure 6, UPS module B further includes a converter 20, a DC line 21, a capacitor 22, a bidirectional chopper 24, an inverter 26, switches S1 to S3, current detectors CD2B to CD4B, and a control device 28.

[0071] Switch S1 is connected between the input terminal T1B and the AC node of the converter 20 and is controlled by the control device 28. When the AC power supply 1 is healthy, switch S1 is turned on, and AC power is supplied from the AC power supply 1 to the converter 20 via switch S1. When the AC power supply 1 is abnormal, switch S1 is turned off, and the connection between the AC power supply 1 and the converter 20 is interrupted.

[0072] The instantaneous value of the AC input voltage VIB supplied from the AC power supply 1 is detected by the control device 28. Based on the instantaneous value of the AC input voltage VIB, the control device 28 determines whether the AC power supply 1 is healthy or abnormal. The current detector CD2B detects the AC input current IiB flowing between the AC power supply 1 and the converter 20, and provides the control device 28 with a signal IiBf indicating the detected value.

[0073] The converter 20 is controlled by the control device 28 and, when the AC power supply 1 is healthy, converts the AC power from the AC power supply 1 into DC power and outputs it to the DC line 21. The converter 20 is a well-known type including multiple sets of semiconductor switching elements and diodes. The converter 20 corresponds to one embodiment of the "second converter".

[0074] Capacitor 22 is connected to DC line 21 and smooths and stabilizes the DC voltage VDB of DC line 21. The instantaneous value of the DC voltage VDB of DC line 21 is detected by control device 28.

[0075] When AC power supply 1 is functioning correctly, the control device 28 controls the converter 20 so that the DC voltage VDB of DC line 21 becomes the reference DC voltage VDR. When AC power supply 1 malfunctions, the control device 28 stops the operation of the converter 20.

[0076] The DC line 21 is connected to the DC terminal T2B via the bidirectional chopper 24 and switch S2. Switch S2 is controlled by the control device 28. When UPS module B is in use, switch S2 is turned on. When the EDLC 4 or bidirectional chopper 24 is being maintained, switch S2 is turned off.

[0077] The instantaneous value of the terminal voltage VC of the EDLC4 (hereinafter referred to as "EDLC voltage") is detected by the control device 28. The current detector CD3B detects the DC current IC flowing between the EDLC4 and the bidirectional chopper 24 (hereinafter referred to as "EDLC current") and provides the control device 28 with a signal ICf indicating the detected value.

[0078] The bidirectional chopper 24 is controlled by the control device 28 and exchanges DC power between the DC line 21 and the EDLC 4. The bidirectional chopper 24 is a well-known one that includes multiple sets of semiconductor switching elements and diodes and a reactor. The bidirectional chopper 24 corresponds to one embodiment of the "second bidirectional chopper". The control device 28 controls the bidirectional chopper 24 so that the DC voltage VDB of the DC line 21 becomes the reference DC voltage VDR.

[0079] The DC line 21 is connected to the DC node of the inverter 26, and the AC node of the inverter 26 is connected to the output terminal T3B via switch S3. Switch S3 is controlled by the control device 28. Switch S3 is turned on when UPS module B is used. Switch S3 is turned off during maintenance of the inverter 26.

[0080] The current detector CD4B detects the AC output current IOB of the inverter 26 and provides the control device 28 with a signal IOBf indicating the detected value. The instantaneous value of the AC output voltage VOB applied to the load 2 from the UPS module B is detected by the control device 28.

[0081] The inverter 26 is controlled by the control device 28 and converts the DC power supplied from the converter 20 or bidirectional chopper 24 via the DC line 21 into AC power of a predetermined frequency (e.g., commercial frequency) and supplies it to the load 2. The inverter 26 is a well-known one comprising multiple sets of semiconductor switching elements and diodes. The inverter 26 corresponds to one embodiment of the "second inverter".

[0082] When AC power supply 1 is functioning correctly, inverter 26 converts the DC power supplied from converter 20 and bidirectional chopper 24 into AC power and supplies it to load 2. When AC power supply 1 malfunctions, inverter 26 converts the DC power supplied from bidirectional chopper 24 into AC power and supplies it to load 2. At this time, control device 28 controls inverter 26 so that the AC output voltage VOB becomes the reference AC voltage VOR.

[0083] The control device 28 controls switches S1 to S3, converter 20, bidirectional chopper 24, and inverter 26 based on the AC input voltage VIB, AC output voltage VOB, DC voltage VDB, EDLC voltage VC, AC input current IiB, EDLC current IC, and AC output current IOB, etc.

[0084] (Example of hardware configuration of control device 28) Figure 7 is a block diagram showing an example of the hardware configuration of the control device 28. Typically, the control device 28 can be configured by a microcomputer with a predetermined program pre-stored in it.

[0085] As shown in Figure 7, the control unit 28 comprises a CPU 280, a memory 282, and an I / O circuit 284. The CPU 280, memory 282, and I / O circuit 284 can exchange data with each other via a bus 286. A program is stored in a portion of the memory 282, and the CPU 280 can execute this program to realize various functions described later. The I / O circuit 284 exchanges signals and data between the control unit 28 and external devices.

[0086] Alternatively, unlike the example in Figure 7, at least a portion of the control device 28 can be configured using circuits such as FPGAs or ASICs. Furthermore, at least a portion of the control device 28 can also be configured using analog circuits.

[0087] (Functional configuration of control device 28) Figure 8 is a block diagram showing the main components of the control device 28. As shown in Figure 8, the control device 28 comprises voltage detectors 40-43, an anomaly detector 44, and a control circuit 45, and controls the entire UPS module B. Each functional block shown in Figure 8 can be implemented by program, hardware, or a combination thereof.

[0088] The voltage detector 40 detects the instantaneous value of the AC input voltage VIB supplied from the AC power supply 1 and outputs a signal VIBf indicating the detected value to the control circuit 45.

[0089] The voltage detector 41 detects the instantaneous value of the AC output voltage VOB applied to the load 2 and outputs a signal VOBf indicating the detected value to the control circuit 45.

[0090] The voltage detector 42 detects the instantaneous value of the DC voltage VDB on the DC line 21 and outputs a signal VDBf indicating the detected value to the control circuit 45.

[0091] The voltage detector 43 detects the instantaneous value of the terminal voltage (EDLC voltage) VC of the EDLC 4 and outputs a signal VCf indicating the detected value to the control circuit 45.

[0092] The abnormality detector 44 detects whether or not an abnormality has occurred in the AC power supply 1 based on the output signal VIBf of the voltage detector 40, and outputs an abnormality detection signal DET to the control circuit 45 indicating the detection result. If the AC power supply 1 is healthy, the abnormality detection signal DET is set to the L level. If an abnormality has occurred in the AC power supply 1, the abnormality detection signal DET is set to the H level.

[0093] The control circuit 45 controls the UPS module B based on the output signals VIBf, VOBf, VDBf, VCf from voltage detectors 40-43, the output signals ILf, IiBf, ICf, IOBf from current detectors CD1, CD2B-CD4B, and the anomaly detection signal DET.

[0094] Specifically, when AC power supply 1 is healthy (DET=L), control circuit 45 controls converter 20 so that the AC power supplied from AC power supply 1 reaches the input power limit value Pe*. The input power limit value Pe* will be explained in detail later. Control circuit 45 also controls bidirectional chopper 24 so that the DC voltage VDB of DC line 21 reaches the reference DC voltage VDR. Control circuit 45 also controls inverter 26 so that the AC output voltage VOB reaches the reference AC voltage VOR.

[0095] If AC power supply 1 is abnormal (DET=H), the control circuit 45 turns off switch S1, stops the operation of converter 20, and controls the bidirectional chopper 24 so that the DC voltage VDB of DC line 21 becomes the reference DC voltage VDR. The control circuit 45 also controls the inverter 26 so that the AC output voltage VOB becomes the reference AC voltage VOR.

[0096] Figure 9 is a block diagram showing the portion of the control circuit 45 related to the control of the inverter 26. As shown in Figure 9, the control circuit 45 is composed of a load power calculation unit 450, an HPF (High Pass Filter) 452, a power distribution calculation unit 454, a power control unit 456, subtractors 458 and 464, a voltage control unit 460, an adder 462, a current control unit 466, and a PWM circuit 468.

[0097] The load power calculation unit 450 calculates the load power PL based on the load current IL indicated by the output signal ILf of the current detector CD1 and the AC output voltage VOB detected by the voltage detector 41.

[0098] HPF452 is a circuit for calculating the fluctuating component Plva of load power from the load power PL calculated by the load power calculation unit 350. Specifically, HPF452 extracts frequency components higher than the cutoff frequency fc from the calculated load power PL. Preferably, the cutoff frequency fc of HPF452 is set to be equal to the cutoff frequency fc of LPF352. In this way, HPF452 can remove the steady-state component PLst of load power from the periodically fluctuating load power PL and extract the fluctuating component PLva of load power PL. The extracted fluctuating component Plva is provided to the power sharing calculation unit 454 as the target output power of the UPS module group 5B.

[0099] The power distribution calculation unit 454 generates the output power command value Pb* for the operating UPS module B by dividing the target output power PLva by the number of operating UPS module B units m. When the number of operating UPS module B units m is equal to the number of UPS module B units M (m=M), the output power command value Pb* for the UPS module B becomes Pb* = PLva / M.

[0100] The power control unit 456 generates a current command value IOB1 from the output power command value Pb* of the UPS module B. Specifically, the power control unit 456 generates the current command value IOB1 by dividing the output power command value Pb* by the AC output voltage VOB detected by the voltage detector 41. The generated current command value IOB1 corresponds to the current that the UPS module B should supply to the load 2.

[0101] The subtractor 458 calculates the difference ΔVOB = VOR - VOB between the reference AC voltage VOR and the AC output voltage VOB detected by the voltage detector 41.

[0102] The voltage control unit 460 generates a current command value IOB2 such that the deviation ΔVOB is eliminated. The voltage control unit 360 generates a current command value IOB2 by, for example, performing a proportional or proportional-integral operation on the deviation ΔVOB.

[0103] The adder 462 adds the current command value IOB1 from the power control unit 456 and the current command value IOB2 from the voltage control unit 460 to generate the current command value IOB* = IOB1 + IOB2. The current command value IOB* corresponds to the command value of the AC output current IOB of the inverter 26.

[0104] The current command value IOB1 corresponds to the feedforward component of the current command value IOB*. By introducing the feedforward component IOB1, which corresponds to the current shared by UPS module B, into the current command value IOB*, the inverter 26 can output an AC output current IOB that includes a feedback component IOB2 with a value corresponding to the deviation ΔVOB, and the feedforward component IOB1.

[0105] The subtractor 464 calculates the difference ΔIOB = IOB* - IOB between the current command value IOB* and the AC output current IOB indicated by the output signal IOBf of the current detector CD4B.

[0106] The current control unit 466 generates a voltage command value VOB* such that the deviation ΔIOB is eliminated. The current control unit 466 generates the voltage command value VOB* by, for example, performing a proportional or proportional-integral operation on the deviation ΔIOB.

[0107] The PWM circuit 468 generates a PWM signal according to the voltage command value VOB* and controls the inverter 26 with that PWM signal.

[0108] Figure 10 is a block diagram showing the portion of the control circuit 45 related to the control of the converter 20. As shown in Figure 10, the control circuit 45 comprises an input power limiting unit 500, a divider 502, a subtractor 504, a current control unit 506, an adder 507, and a PWM circuit 508.

[0109] The input power limiting unit 500 generates an input power limit value Pe* for the UPS module B based on the output power command value Pb* generated by the power distribution calculation unit 454 (Figure 9). The input power limit value Pe* is intended to limit the AC power supplied from the AC power source 1 to the UPS module B to a constant value.

[0110] Specifically, the input power limiting unit 500 generates an input power limit value Pe* by smoothing the output power command value Pb*. As explained in Figure 9, the output power command value Pb* is obtained by dividing the target output power PLva of the UPS module group 5B by the number of operating UPS modules B m. In certain situations, the input power limiting unit 500 generates the input power limit value Pe* by performing a smoothing process on the output power command value Pb* using a moving average filter or LPF.

[0111] The divider 502 generates a current command value IiB* by dividing the input power limit value Pe* by the AC input voltage VIB detected by the voltage detector 40. This generates a current command value IiB* that is in phase with the AC input voltage VIB supplied from the AC power supply 1.

[0112] The subtractor 504 calculates the difference ΔIiB = IiB* - IiB between the current command value IiB* and the AC input current IiB indicated by the output signal IiBf of the current detector CD2B.

[0113] The current control unit 506 generates a voltage command value VIB1 such that the deviation ΔIiB becomes 0. The current control unit 506 generates the voltage command value VIB1 by, for example, proportional control or proportional-integral control of the deviation ΔIiB.

[0114] The adder 507 adds the voltage command value VIB1 and the AC input voltage VIB detected by the voltage detector 40 to generate the voltage command value VIB*.

[0115] The PWM circuit 508 controls the converter 20 based on a sinusoidal voltage command value VIB* when the detection signal DET from the abnormality detector is at a low level (when AC power supply 1 is healthy). The PWM circuit 508 also stops the operation of the converter 20 when the detection signal DET is at a high level (when AC power supply 1 is abnormal).

[0116] Figure 11 is a block diagram showing the configuration of the part of the control circuit 45 related to the control of the bidirectional chopper 24. As shown in Figure 11, the control circuit 45 is composed of subtractors 510, 514, a voltage control unit 512, a current control unit 516, and a PWM circuit 518.

[0117] The subtractor 510 calculates the difference ΔVDB = VDR - VDB between the reference DC voltage VDR and the DC voltage VDB detected by the voltage detector 42.

[0118] The voltage control unit 512 determines a current command value IC* corresponding to the deviation ΔVDB based on the EDLC voltage VC detected by the voltage detector 42. The voltage control unit 512 determines the current command value IC* by, for example, performing a proportional or proportional-integral operation on the deviation ΔVDB.

[0119] The subtractor 514 calculates the difference ΔIC = IC* - IC between the current command value IC* generated by the voltage control unit 512 and the EDLC current IC indicated by the output signal ICf of the current detector CD3B.

[0120] The current control unit 516 generates a voltage command value VD* based on the deviation ΔIC. The current control unit 516 determines the voltage command value VD* by, for example, performing a proportional or proportional-integral operation on the deviation ΔIC. The PWM circuit 518 controls the bidirectional chopper 24 based on the voltage command value VD*. The bidirectional chopper 24 exchanges DC power between the DC line 21 and the EDLC 4, with a value corresponding to the deviation ΔVDB between the reference DC voltage VDR and the DC voltage VDB.

[0121] <Example of Uninterruptible Power Supply (UPS) Configuration> Next, an example of the configuration and operation of the uninterruptible power supply 100 according to this embodiment will be described.

[0122] (Example configuration 1) Figure 12 is a circuit block diagram showing a first configuration example of an uninterruptible power supply 100 according to this embodiment. As shown in Figure 12, the uninterruptible power supply 100A according to the first configuration example is equipped with 10 UPS modules. UPS module group 5A is composed of 5 UPS modules A1 to A5. UPS module group 5B is composed of 5 UPS modules B1 to B5. That is, N=5, M=5, N+M=10.

[0123] In the following explanation, the AC power input from AC power source 1 to input node NF of uninterruptible power supply 100A will be referred to as "input power PF," and the AC power supplied from output node NA of uninterruptible power supply 100A to load 2 will be referred to as "load power PL." Furthermore, the AC power input to input node ND of UPS module group 5A will be referred to as "input power PD," and the AC power output from output node NB of UPS module group 5A will be referred to as "output power PB." The AC power input to input node NE of UPS module group 5B will be referred to as "input power PE," the AC power output from output node NC of UPS module group 5B will be referred to as "output power PC," and the charge / discharge power for the M EDLCs 4 connected to UPS module group 5B will be referred to as "charge / discharge power PH."

[0124] First, we will explain the specific methods for determining N and M, referring to Figure 13. Figure 13 is a time chart showing the operation of the 100A uninterruptible power supply. Figure 13(A) shows the waveform of the load power PL, Figure 13(B) shows the waveform of the output power PB of the UPS module group 5A, and Figure 13(C) shows the waveform of the output power PC of the UPS module group 5B. The vertical axis of each waveform represents the load factor. The load factor is the percentage of the load power PL, with 100% representing the load when the load power PL is the rated load of the 100A uninterruptible power supply.

[0125] As shown in Figure 13(A), the load power PL fluctuates periodically between the maximum power consumption PLmax = 100% and the minimum power consumption PLmin = 50%. Specifically, in each fluctuation period, the load power PL temporarily increases to the maximum power consumption PLmax, and then remains at the minimum power consumption PLmin.

[0126] As shown in Figure 5, each UPS module A in the UPS module group 5A controls the inverter 16 to output power corresponding to the steady-state component PLst of the load power. As shown in Figure 9, each UPS module B in the UPS module group 5B controls the inverter 26 to output power corresponding to the fluctuating component PLva of the load power.

[0127] As shown in Figure 13(B), when the steady-state component PLst of the load power is equal to the minimum power consumption PLmin = 50%, the UPS module group 5A steadily outputs power PB corresponding to a load factor of 50% in each fluctuation period.

[0128] On the other hand, as shown in Figure 13(C), the UPS module group 5B outputs power PC corresponding to the remaining fluctuating component PLva, which is obtained by subtracting the steady-state component PLst from the load power PL, during each fluctuation cycle. The output power PC temporarily increases to 50% during each fluctuation cycle, and then remains at 0%.

[0129] The total number of UPS modules N+M installed in a 100A uninterruptible power supply is set to be equal to the number obtained by dividing the maximum power consumption PLmax by the capacity X per UPS module (N+M = PLmax / X). If the capacity per UPS module corresponds to a load of 10%, then PLmax = 100% and X = 10%, so the total number of UPS modules (N+M) is set to 100(%) ÷ 10(%) = 10 modules.

[0130] The number of UPS modules A that make up UPS module group 5A, N, is set to be equal to the number obtained by dividing the steady-state component PLst of the load power PL by the capacity X per UPS module (N = PLst / X). Since PLst = 50% and X = 10%, the number of UPS modules A N is set to 50 (%) ÷ 10 (%) = 5 units.

[0131] Since N+M=10 and N=5, the number of UPS modules B that make up UPS module group 5B, M, is set to 10-5=5 units.

[0132] In this configuration, the uninterruptible power supply 100A is configured such that power PB, which corresponds to the steady-state component PLst of the load power, is output by N UPS modules A1 to AN that make up UPS module group 5A, and power PC, which corresponds to the fluctuating component PLva of the load power, is output by M UPS modules B1 to BM that make up UPS module group 5B.

[0133] In this way, the power PD input from AC power supply 1 to UPS module group 5A can be kept constant regardless of fluctuations in load power PL. On the other hand, the power PE input from AC power supply 1 to UPS module group 5B may fluctuate with the same fluctuation period as load power PL, in response to fluctuations in output power PC. As a result, there is a concern that the input power PF from AC power supply 1 to uninterruptible power supply 100A may fluctuate in accordance with fluctuations in load power PL.

[0134] To address these concerns, in this embodiment, an input power limit value Pe* is set in UPS module B. As explained in Figure 10, the input power limit value Pe* is used to limit the AC power supplied from AC power source 1 to UPS module B to a constant value. In this way, the input power PE to the UPS module group 5B can be kept at a constant power equivalent to the input power limit value Pe* × M.

[0135] Furthermore, by setting the input power limit value Pde* for UPS module B, a discrepancy will occur between the input power limit value Pe* and the allocated power Pb* that should be output to load 2 in UPS module B. In the example in Figure 13(C), the allocated power Pb* of each UPS module B will fluctuate between 10% (=50% ÷ 5) and 0%. Therefore, if the allocated power Pb* is greater than the input power limit value Pe*, there will be insufficient power supply from AC power source 1, and if the allocated power Pb* is less than the input power limit value Pe*, there will be an oversupply of power from AC power source 1.

[0136] Therefore, UPS module B is configured to compensate for the difference between the input power limit Pe* and the allocated power Pb* by charging and discharging the EDLC4. Specifically, if the allocated power Pb* is greater than the input power limit Pe*, the power equivalent to the deficit is compensated for by the discharge power from the EDLC4. Conversely, if the allocated power Pb* is less than the input power limit Pe*, the power equivalent to the surplus is charged to the EDLC4.

[0137] The charging and discharging of the EDLC4 is performed by a bidirectional chopper 24. Specifically, as described in Figure 11, the bidirectional chopper 24 is configured to exchange DC power between the DC line 21 and the EDLC4, which includes a feedback component whose value corresponds to the deviation ΔVDR between the reference DC voltage VDR and the DC voltage VDB detected by the voltage detector 42.

[0138] Figure 14 is a time chart showing the operation of the 100A uninterruptible power supply. Figure 14(F) shows the waveform of the input power PF of the 100A, Figure 14(D) shows the waveform of the input power PD of the UPS module group 5A, and Figure 14(E) shows the waveform of the input power PE of the UPS module group 5B. The vertical axis of each waveform represents the load factor.

[0139] As shown in Figure 14(D), similar to the output power PB of the UPS module group 5A shown in Figure 13(B), a power PD corresponding to the steady-state component PLst = 50% of the load power is steadily input to the UPS module group 5A during each fluctuation period. Furthermore, if charging of battery 3 is necessary to maintain it in a predetermined fully charged state, the input power PD becomes equal to the sum of the output power PB and the charging power of battery 3.

[0140] As shown in Figure 14(E), power PE is steadily input to the UPS module group 5B during each fluctuation period. This input power PE corresponds to the value obtained by multiplying the input power limit value Pe* of UPS module B by the number of UPS modules B M. If the input power limit value Pe* = 2%, then the input power PE = 2(%) × 5(units) = 10%.

[0141] The power PF input from AC power source 1 to the uninterruptible power supply 100A is equal to the sum of input power PD and input power PE, as shown in Figure 14(D). Since PD=50% and PE=10%, PD=60%. In contrast to the waveform of load power PL shown in Figure 13(A), there is no fluctuation in the waveform of input power PF. That is, the input power PF is kept constant regardless of fluctuations in load power PL. This makes it possible to stabilize the power system without being affected by fluctuations in load power PL.

[0142] Figure 15 is a time chart showing the operation of UPS module group 5B. Figure 15(E) shows the waveform of the input power PE of UPS module group 5B, similar to Figure 14(E). Figure 15(C) shows the waveform of the output power PC of UPS module group 5B, similar to Figure 13(C). Figure 15(H) shows the waveform of the charge / discharge power PH of the M units of EDLC4 connected to UPS module group 5B. Note that in Figure 15(H), the discharge power of EDLC4 is represented by a positive value and the charge power by a negative value.

[0143] As shown in Fig. 15(E), the input power PE maintains a value obtained by multiplying the input power limit value Pe* of the UPS module B by the number M of the UPS modules B in each fluctuation cycle. On the other hand, as shown in Fig. 15(C), the output power PC is the fluctuating component PLva of the load power, which fluctuates between 50% and 0% in each fluctuation cycle.

[0144] As shown in Fig. 15(H), when PC > PE, the power PC - PF corresponding to the difference between the output power PC and the input power PE is discharged from the EDLC4. Therefore, the output power PC becomes equal to the sum of the input power PE and the discharge power PH.

[0145] When PC < PE, the power PC - PE corresponding to the difference between the output power PC and the input power PE is charged to the EDLC4. In this case, the input power PE becomes equal to the sum of the output power PC and the charge power PH.

[0146] Note that if the amount of power discharged from the EDLC4 and the amount of power charged to the EDLC4 can be made equal in each fluctuation cycle, the stored power of the EDLC4 can be maintained within a certain range during the operation of the load 2. For this, for example, it is conceivable to set the power corresponding to the average value of the shared power Pb* per fluctuation cycle to the input power limit value Pe*.

[0147] In the present embodiment, as described in Fig. 10, the input power limit value Pe* can be appropriately changed according to the shared power Pb* of the UPS module B. By doing so, it is possible to appropriately set the input power limit value Pe* that can maintain the stored power of the EDLC4 within a certain range in flexible response to the fluctuation pattern of the load power PL.

[0148] In the event of an abnormality in AC power supply 1, the UPS module A stops the operation of converter 10, and power equivalent to the shared power Pa* is supplied from battery 3 to DC line 11 via bidirectional chopper 14. Since battery 3 is kept in a predetermined fully charged state when AC power supply 1 is healthy, the UPS module group 5A can stably supply the steady-state component PLst of the load power.

[0149] Furthermore, in UPS module B, the converter 20 is shut down, and power equivalent to the shared power Pb* is supplied from EDLC4 to the DC line 21 via the bidirectional chopper 24. At this time, since the M EDLC4s equally share the fluctuating component PLva of the load power, the UPS module group 5B can stably supply the fluctuating component PLva of the load power.

[0150] (Second configuration example) Figure 16 is a circuit block diagram showing a second configuration example of the uninterruptible power supply 100 according to this embodiment. As shown in Figure 16, the uninterruptible power supply 100B according to the second configuration example is equipped with 10 UPS modules, just like the first configuration example in Figure 12. However, in the second configuration example, UPS module group 5A is composed of one UPS module A1, and UPS module group 5B is composed of nine UPS modules B1 to B9. That is, N=1, M=9, and N+M=10. The configuration and operation of UPS modules A and B are the same as in the first configuration example.

[0151] Figure 17 is a time chart showing the operation of the uninterruptible power supply (UPS) 100B. Figure 17(A) shows the waveform of the load power PL, Figure 17(B) shows the waveform of the output power PB of UPS module group 5A, and Figure 17(C) shows the waveform of the output power PC of UPS module group 5B. The vertical axis of each waveform represents the load factor.

[0152] As shown in Figure 17(A), the load power PL fluctuates periodically between the maximum power consumption PLmax = 100% and the minimum power consumption PLmin = 10%. The waveform in Figure 17(A) is the same as the waveform in Figure 13(A) at the maximum power consumption PLmax = 100%, but the fluctuation pattern of the load power PL is different. Note that the steady-state component PLst of the load power PL in Figure 17(A) corresponds to a load factor of 10%.

[0153] Therefore, the total number of UPS modules N+M installed in the uninterruptible power supply unit 100B is set to 10 units, with PLmax=100% and X=10%, resulting in 100(%) ÷ 10(%) = 10 units.

[0154] Furthermore, the number of UPS modules A that make up UPS module group 5A, N, is set to 10(%) ÷ 10(%) = 1 unit, since PLst = 10% and X = 10%. Then, since N + M = 10 and N = 1, the number of UPS modules B that make up UPS module group 5B, M, is set to 10 - 1 = 9 units.

[0155] In the uninterruptible power supply 100B, one UPS module A1, which constitutes UPS module group 5A, outputs power PB, which corresponds to the steady-state component PLst of the load power, while nine UPS modules B1 to BM, which constitute UPS module group 5B, output power PC, which corresponds to the fluctuating component PLva of the load power.

[0156] <Effects> As described above, according to this embodiment, the steady-state component PLst and the fluctuating component PLva of the load power change in a wide variety of ways depending on the fluctuation pattern of the load power PL. The number of UPS modules A that supply power corresponding to the steady-state component PLst to load 2, N, and the number of UPS modules B that supply power corresponding to the fluctuating component PLva to load 2, M can be freely set. This makes it possible to stabilize the power system by flexibly responding to fluctuations in the load power PL.

[0157] Furthermore, in this embodiment, the UPS module B is equipped with an input power limiting function. The UPS module B is configured to compensate for the difference between the input power limit value Pe* and the shared power Pb* by charging and discharging the EDLC4. By appropriately changing the input power limit value Pe* according to the shared power Pb*, the amount of stored energy in the EDLC4 can be maintained while flexibly responding to the fluctuation pattern of the load power PL. As a result, the UPS module B can compensate for fluctuations in the load power PL while leveling the input power from the AC power source 1.

[0158] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. This disclosure is indicated by the claims rather than the foregoing description and is intended to include all modifications in the meaning and scope of the claims equivalents. [Explanation of symbols]

[0159] 1 AC power supply, 2 Load, 3 Battery, 5A, 5B UPS module group, 10, 20 Converter, 11, 21 DC line, 12, 22 Capacitor, 14, 24 Bidirectional chopper, 16, 26 Inverter, 18, 28 Control device, 30~33, 40~43 Voltage detector, 34, 44 Anomaly detector, 35, 45 Control circuit, 100, 100A, 100B Uninterruptible power supply, 180, 280 CPU, 182, 282 Memory, 184, 284 I / O circuit, 186, 286 Bus, 350, 450 Load power calculation unit, 352 LPF, 354, 454 Shared power calculation unit, 356, 456 Power control unit, 358, 364, 458, 464, 504, 510, 514 Subtractors: 360, 460, 512 Voltage control units: 362, 462, 507 Adders: 366, 466, 506, 516 Current control units: 368, 468, 508, 518 PWM circuit: 452 HPF: 500 Input power limiter: 502 Dividers: A, A1~AN, B, B1~BM UPS modules: CD1, CD2A~CD4A, CD2B~CD4B Current detectors: S1~S3 Switches: T1A, T1B Input terminals: T2A, T2B DC terminals: T3A, T3B Output terminals.

Claims

1. An uninterruptible power supply (UPS) device comprising multiple UPS modules connected in parallel to each other between an AC power source and a load, The aforementioned plurality of UPS modules have equal capacities to each other. A first UPS module group having N first UPS modules, It includes a second group of UPS modules having M units of second UPS modules, The first UPS module is connected to the first energy storage device. The second UPS module is connected to a second energy storage device. The first energy storage device has a higher energy density than the second energy storage device. The second energy storage device has a higher power density compared to the first energy storage device. N+M is equal to the number obtained by dividing the maximum power consumption of the load by the capacity per UPS module. N is an uninterruptible power supply (UPS) whose number is equal to the number obtained by dividing the steady-state component of the power consumption of the load by the capacity per UPS module.

2. The first group of UPS modules outputs power corresponding to the steady-state component of the power consumption of the load, The uninterruptible power supply according to claim 1, wherein the second group of UPS modules outputs power corresponding to the fluctuating component of the power consumption of the load.

3. The aforementioned first UPS module is A first converter that converts AC power supplied from the aforementioned AC power source into DC power, A first inverter that converts DC power supplied from the first converter or the first energy storage device into AC power and supplies it to the load, Including a first control device, The first control device is The steady-state component is calculated by applying a low-pass filter to the power consumption of the load. The power share of the first UPS module is calculated by dividing the steady-state component by the number of operating first UPS modules. The uninterruptible power supply according to claim 2, wherein the first inverter is controlled to output the aforementioned shared power.

4. The uninterruptible power supply according to claim 3, wherein the first control device controls the first inverter to supply to the load an AC output current that includes a feedback component corresponding to the deviation between a reference AC voltage and the AC output voltage of the first inverter, and a feedforward component corresponding to the shared power.

5. The first UPS module further includes a first bidirectional chopper that converts DC power bidirectionally between the first energy storage device and the first inverter. The first control device, when the AC power supply is healthy, The first converter is controlled so that the DC input voltage of the first inverter becomes the reference DC voltage. The uninterruptible power supply according to claim 3, wherein the first bidirectional chopper is controlled so that the first energy storage device reaches a predetermined fully charged state.

6. The second UPS module described above is A second converter that converts AC power supplied from the aforementioned AC power source into DC power, A second inverter that converts the DC power supplied from the second converter or the second energy storage device into AC power and supplies it to the load, Including a second control device, The second control device is, The fluctuating component is calculated by applying a high-pass filter to the power consumption of the load. The power share of the second UPS module is calculated by dividing the aforementioned fluctuating component by the number of operating second UPS modules. The uninterruptible power supply according to claim 2, wherein the second inverter is controlled to output the aforementioned shared power.

7. The uninterruptible power supply according to claim 6, wherein the second control device controls the second inverter to supply to the load an AC output current that includes a feedback component corresponding to the deviation between a reference AC voltage and the AC output voltage of the second inverter, and a feedforward component corresponding to the shared power.

8. The second control device is, Based on the power shared by the second UPS module, the input power limit value for the second UPS module is set. If the shared power exceeds the input power limit, power equivalent to the excess of the shared power relative to the input power limit is supplied from the second energy storage device to the second inverter. The uninterruptible power supply according to claim 6, wherein if the shared power falls below the input power limit, power equivalent to the surplus of the shared power relative to the input power limit is stored in the second energy storage device.

9. The second UPS module further includes a second bidirectional chopper that converts DC power bidirectionally between the second energy storage device and the second inverter. The second control device is, The second converter is controlled so that the AC power supplied from the AC power source reaches the input power limit value. The uninterruptible power supply according to claim 8, wherein the second bidirectional chopper is controlled so that the DC input voltage of the second inverter becomes a reference DC voltage.

10. The first energy storage device is a secondary battery, The uninterruptible power supply according to any one of claims 1 to 9, wherein the second energy storage device is an electric double-layer capacitor.

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