Uninterruptible power supply system

Abstract

To provide an uninterruptible power supply system that is capable of suppressing the increase of short-circuit current (transverse current) flowing between uninterruptible power supply devices while preventing momentary power interruptions that interrupt the supply of power to a load.SOLUTION: The uninterruptible power supply system 100 includes a power supply switching device 20 that switches a source of power supply to a load 101 from a system B uninterruptible power supply device 12 to a system A uninterruptible power supply device 11. The uninterruptible power supply system 100 performs an input current control to reduce an input current value input into the power supply switching device 20 from the system B uninterruptible power supply device 12 to a predetermined threshold current or less by controlling the phase of an output voltage of the system B uninterruptible power supply device 12 when switching the supply source of power to the load 101 from the system B uninterruptible power supply device 12 to the system A uninterruptible power supply device 11 by the power supply switching device 20 in an overlap state where both the system A uninterruptible power supply device 11 and the system B uninterruptible power supply device 12 are connected to the load 101.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an uninterruptible power supply system, and more particularly to an uninterruptible power supply system comprising a plurality of uninterruptible power supply units and a power switching device. [Background technology]

[0002] Conventionally, uninterruptible power supply systems comprising multiple uninterruptible power supply units and power switching devices are known (see, for example, Patent Document 1).

[0003] The uninterruptible power supply system described in Patent Document 1 above comprises two uninterruptible power supplies (hereinafter referred to as the first uninterruptible power supply and the second uninterruptible power supply) and a power switching device. The power switching device controls the switching of which of the two uninterruptible power supplies supplies power to the load. Specifically, the switching circuit of the power switching device includes a thyristor (hereinafter referred to as the first thyristor) provided between one of the first uninterruptible power supplies and the load, and a thyristor (hereinafter referred to as the second thyristor) provided between the other of the second uninterruptible power supply and the load. The switching circuit also includes a mechanical switch provided between both the first and second uninterruptible power supplies and the load. The mechanical switch is configured to switch its connection state so that it connects either the first or second uninterruptible power supply to the load.

[0004] In the above-mentioned Patent Document 1, for example, when switching the power supply source to the load from the first uninterruptible power supply (UPS) to the second UPS, the first thyristor conducts, and the mechanical switch connects the load to the first UPS. Then, the second thyristor conducts, resulting in an overlap state where both the first and second UPSs and the load are conductive. Next, the first thyristor is deconducted based on the mechanical switch leaving the contact on the first UPS side and then contacting the contact on the second UPS side. This switches the power supply source to the load from the first UPS to the second UPS. Furthermore, the overlap state described above when switching the power supply source to the load prevents momentary interruptions in the power supply to the load. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 5886732 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, in the above-mentioned Patent Document 1, when switching the power supply source, an overlap state occurs where both the first and second uninterruptible power supplies and the load are conductive. As a result, when the current input from the first uninterruptible power supply supply that supplies power to the load to the power switching device is large, there is a problem in that the short-circuit current (cross-current) flowing between the first and second uninterruptible power supplies becomes large.

[0007] This invention was made to solve the above-mentioned problems, and one of its objectives is to provide an uninterruptible power supply system that can prevent momentary interruptions in the power supply to the load while suppressing an increase in short-circuit current (cross-current) flowing between uninterruptible power supply units. [Means for solving the problem]

[0008] To achieve the above objective, this invention 1 The uninterruptible power supply system in this phase comprises a first uninterruptible power supply unit including a first control unit and a second uninterruptible power supply unit including a second control unit, which supply power to the same load; a power switching device that switches the power supply source to the load from the first uninterruptible power supply unit to the second uninterruptible power supply unit; and an input current detection unit that detects the input current value input from the first uninterruptible power supply unit to the power switching device, and both the first and second uninterruptible power supply units are simultaneously connected to the load. rose In the top state, when the power supply source for the load is switched from the first uninterruptible power supply (UPS) to the second UPS by the power switching device, the first control unit of the first UPS controls the phase of the output voltage of the first UPS, thereby inputting the input current value from the first UPS to the power switching device and detected by the input current detection unit. By performing feedback control on this, The system is configured to perform input current control to reduce the current to below a predetermined threshold, and then disconnect the first uninterruptible power supply (UPS) from the load using a power switching device.

[0009] This invention 1In an uninterruptible power supply (UPS) system in this phase, as described above, when the power supply switching device switches the power source to the load from the first UPS to the second UPS in an overlap state where both the first and second UPS units are connected to the load, input current control is performed by controlling the phase of the output voltage of the first UPS unit to reduce the input current value input from the first UPS unit to the power supply switching device to below a predetermined threshold current. After this, the first UPS unit and the load are disconnected. This prevents momentary power interruptions that would occur if the power supply to the load were interrupted due to the switching control of the power source in an overlap state. Furthermore, by performing the input current control that reduces the input current value to below a predetermined threshold current, it is possible to suppress the increase in short-circuit current (cross-current) flowing between the first and second UPS units due to the input current input from the first UPS unit to the power supply switching device in an overlap state. These measures prevent momentary power interruptions that would cause a loss of power supply to the load, while also suppressing an increase in the short-circuit current (cross-current) flowing between the first and second uninterruptible power supplies.

[0010] the above 1 In an uninterruptible power supply system in this configuration, preferably, the first control unit of the first uninterruptible power supply is configured to adjust the output voltage of the first uninterruptible power supply to match the phase and amplitude of the input voltage input from the second uninterruptible power supply to the power switching device, and then perform input current control in an overlap state. With this configuration, input current control can be performed while the output voltage of the first uninterruptible power supply is adjusted to match the voltage of the second uninterruptible power supply, thereby further suppressing the increase in short-circuit current (cross-current) flowing between the first uninterruptible power supply and the second uninterruptible power supply.

[0011] the above 1In an uninterruptible power supply system in this configuration, preferably, the first control unit of the first uninterruptible power supply is configured to perform input current control by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value from the first uninterruptible power supply input to the power switching device, thereby reducing the input current value to a predetermined threshold current or lower. With this configuration, feedback control can be performed to control the input current value based on the input current value from the first uninterruptible power supply input to the power switching device, making it easy to perform input current control to reduce the input current value to a predetermined threshold current or lower.

[0012] In the uninterruptible power supply system according to the second aspect of this invention, the system comprises a first uninterruptible power supply unit including a first control unit and a second uninterruptible power supply unit including a second control unit, which supply power to the same load; a power switching device that switches the power supply source to the load from the first uninterruptible power supply unit to the second uninterruptible power supply unit; and an input current detection unit that detects the input current value input from the first uninterruptible power supply unit to the power switching device. In an overlap state where both the first and second uninterruptible power supply units are simultaneously connected to the load, when the power switching device switches the power supply source to the load from the first uninterruptible power supply unit to the second uninterruptible power supply unit, the first uninterruptible power supply unit The first control unit of the power supply device controls the phase of the output voltage of the first uninterruptible power supply, thereby performing input current control to reduce the input current value, which is input from the first uninterruptible power supply to the power switching device and detected by the input current detection unit, to below a predetermined threshold current. After this, the power switching device is configured to disconnect the first uninterruptible power supply from the load. The first control unit of the first uninterruptible power supply is configured to perform input current control to reduce the input current value to below a predetermined threshold current by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value from the first uninterruptible power supply input to the power switching device. The first control unit of the first uninterruptible power supply is configured to perform input current control by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value and the output current detection value of the first uninterruptible power supply, thereby reducing the input current value to a predetermined threshold current or lower. With this configuration, the input current value can be controlled based on the output current command value of the first uninterruptible power supply in addition to the input current value, making it easier to perform input current control to reduce the input current value to a predetermined threshold current or lower.

[0013] In the uninterruptible power supply system described in the second phase above Preferably, the first control unit of the first uninterruptible power supply is configured to perform input current control by controlling the phase of the output voltage of the first uninterruptible power supply based on the difference between the output current detection value and the input current value of the first uninterruptible power supply, thereby reducing the input current value to a predetermined threshold current or less. With this configuration, by performing input current control based on the difference between the output current detection value and the input current value of the first uninterruptible power supply, the output current detection value of the first uninterruptible power supply is reduced by the amount of the input current value, so the output current of the first uninterruptible power supply can be easily reduced. As a result, the input current value output from the first uninterruptible power supply and input to the power switching device can be easily reduced.

[0014] the above First and secondIn an uninterruptible power supply system in this configuration, preferably, the power switching device includes a switching device-side control unit that performs switching control to switch the power supply source to the load from a first uninterruptible power supply to a second uninterruptible power supply, and multiple such devices are provided to accommodate multiple loads. Each switching device-side control unit of the multiple power switching devices is configured to transmit a signal to the other power switching devices to restrict switching control from being performed in the other power switching devices, based on the fact that switching control is being performed in the other power switching devices. With this configuration, it is possible to suppress switching control from being performed in other power switching devices when switching control is being performed in one power switching device, and as a result, it is possible to suppress the input current control in one power switching device from becoming abnormal due to abnormalities such as current (cross-current) flowing between power switching devices.

[0015] the above The first and second In an uninterruptible power supply system in this configuration, preferably, the power switching device includes a first semiconductor switch positioned between a first uninterruptible power supply and a load, a second semiconductor switch positioned between a second uninterruptible power supply and a load, a mechanical changeover switch for switching between connecting the first uninterruptible power supply and the load or connecting the second uninterruptible power supply and the load, and a switching device-side control unit that performs switching control to switch the power supply source to the load from the first uninterruptible power supply to the second uninterruptible power supply. The switching device-side control unit is configured to transmit a signal to the second semiconductor switch to turn on the second semiconductor switch while the first uninterruptible power supply and the load are connected by the changeover switch, and at the same time transmit a switching signal to the changeover switch to connect the second uninterruptible power supply and the load. The first control unit of the first uninterruptible power supply is configured to perform input current control between the time the second semiconductor switch is turned on and the time the second uninterruptible power supply and the load are connected by the changeover switch. As a result, the turn-on time of the semiconductor switch is shorter than the switching time of the mechanical switch, allowing for easy input current control within the time difference between the turn-on time of the second semiconductor switch and the switching time of the mechanical changeover switch. [Effects of the Invention]

[0016] According to the present invention, as described above, it is possible to prevent momentary interruptions in the power supply to the load while suppressing an increase in the short-circuit current (cross-current) flowing between uninterruptible power supply units. [Brief explanation of the drawing]

[0017] [Figure 1] This figure shows an uninterruptible power supply system according to one embodiment. [Figure 2] A flowchart illustrating the control of power switching in an uninterruptible power supply system according to one embodiment. [Figure 3] This diagram shows the configuration of a power switching device according to one embodiment. [Figure 4] This figure shows the configuration of a B-system uninterruptible power supply according to one embodiment. [Figure 5] This diagram shows the configuration of the B-system power supply side control unit according to one embodiment. [Figure 6] This figure shows the current waveform and voltage waveform during switching control according to one embodiment. [Modes for carrying out the invention]

[0018] The following describes embodiments of the present invention based on the drawings.

[0019] The uninterruptible power supply system 100 according to this embodiment will be described with reference to Figures 1 to 6.

[0020] (Configuration of an uninterruptible power supply system) As shown in Figure 1, the uninterruptible power supply system 100 includes two uninterruptible power supplies 10 that supply power to the same load 101. The uninterruptible power supplies 10 include a system A uninterruptible power supply 11 and a system B uninterruptible power supply 12, which are different power systems. The system A uninterruptible power supply 11 has a system A inverter 11a and a system A power supply side control unit 11b. The system B uninterruptible power supply 12 has a system B inverter 12a and a system B power supply side control unit 12b. When switching the power supply source to the load 101 from the system B uninterruptible power supply 12 to the system A uninterruptible power supply 11, the system A uninterruptible power supply 11 and the system B uninterruptible power supply 12 are examples of the "second uninterruptible power supply" and the "first uninterruptible power supply" as defined in the claims, respectively, and the system A power supply side control unit 11b and the system B power supply side control unit 12b are examples of the "second control unit" and the "first control unit," respectively. Furthermore, when switching the power supply source to load 101 from system A uninterruptible power supply 11 to system B uninterruptible power supply 12, system A uninterruptible power supply 11 and system B uninterruptible power supply 12 are examples of the "first uninterruptible power supply" and "second uninterruptible power supply" in the claims, respectively, and system A power supply side control unit 11b and system B power supply side control unit 12b are examples of the "first control unit" and "second control unit," respectively.

[0021] The uninterruptible power supply system 100 includes a power switching device 20. The power switching device 20 controls the power supply source for the load 101 to switch between the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12. Multiple power switching devices 20 are provided to accommodate multiple loads 101.

[0022] The power switching device 20 includes a switching circuit 21 and a switching device-side control unit 22. The switching device-side control unit 22 performs switching control to switch the power supply source to the load 101 between the B-system uninterruptible power supply 12 and the A-system uninterruptible power supply 11. In the following example, the power switching device 20 performs control to switch the power supply source to the load 101 from the B-system uninterruptible power supply 12 to the A-system uninterruptible power supply 11 in an overlap state where both the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12 are connected to the load 101. The switching device-side control unit 22 is also configured to control the switching circuit 21.

[0023] Furthermore, the uninterruptible power supply system 100 includes a current sensor 20b that detects the input current value input from the B-system uninterruptible power supply unit 12 to the power switching device 20. Furthermore, the uninterruptible power supply system 100 includes a current sensor 20a that detects the input current value input from the A-system uninterruptible power supply unit 11 to the power switching device 20. Each of the current sensors 20b and 20a is provided in the switching circuit 21 of the power switching device 20. Note that when switching the power supply source to the load 101 from the B-system uninterruptible power supply unit 12 to the A-system uninterruptible power supply unit 11, the current sensor 20b is an example of the "input current detection unit" in the claims. Furthermore, when switching the power supply source to the load 101 from the A-system uninterruptible power supply unit 11 to the B-system uninterruptible power supply unit 12, the current sensor 20a is an example of the "input current detection unit" in the claims.

[0024] The power switching device 20 (switching circuit 21) includes an A-system thyristor 21a positioned between the A-system uninterruptible power supply 11 and the load 101. The power switching device 20 (switching circuit 21) also includes a B-system thyristor 21b positioned between the B-system uninterruptible power supply 12 and the load 101. The power switching device 20 (switching circuit 21) also includes a mechanical changeover switch 21c that switches between connecting the A-system uninterruptible power supply 11 to the load 101 or connecting the B-system uninterruptible power supply 12 to the load 101. When switching the power supply source to the load 101 from the B-system uninterruptible power supply 12 to the A-system uninterruptible power supply 11, the A-system thyristor 21a and the B-system thyristor 21b are examples of the "second semiconductor switch" and "first semiconductor switch" in the claims, respectively. Furthermore, when switching the power supply source to load 101 from system A uninterruptible power supply 11 to system B uninterruptible power supply 12, system A thyristor 21a and system B thyristor 21b are examples of the "first semiconductor switch" and "second semiconductor switch" as defined in the claims, respectively.

[0025] Each of the A-system thyristors 21a and B-system thyristors 21b is composed of thyristors connected in antiparallel to each other. Antiparallel means that the positive terminal of one element is connected to the negative terminal of the other element, and the negative terminal of one element is connected to the positive terminal of the other element.

[0026] The changeover switch 21c is composed of a power changeover switch (DTMC). The changeover switch 21c is configured to switch whether the input terminal side of the B-system thyristor 21b or the input terminal side of the A-system thyristor 21a is conductive (connected) to the load 101.

[0027] (Operation of the uninterruptible power supply system) Next, we will explain the operation of the uninterruptible power supply system 100 when switching the power source for load 101 from system B uninterruptible power supply 12 to system A uninterruptible power supply 11.

[0028] As shown in Figure 2, in step S1, when manually switching the power supply source to the load 101 from the B-system uninterruptible power supply 12 to the A-system uninterruptible power supply 11, the A-system manual switching signal S is input to the AND circuit 22a (see Figure 3) provided in the switching device side control unit 22 by operating an operation switch (not shown) of the power switching device 20. A This becomes an H signal. At this point, the changeover switch 21c is connected to the B-system uninterruptible power supply 12, so the A-system MC answerback AB, which indicates the connection status of the changeover switch 21c, is input to the AND circuit 22a. A This becomes an L signal. Also, the B-system MC answer back AB, which is input to the AND circuit 22a, indicates the connection status of the changeover switch 21c. B This is an H signal. Also, the input voltage (A-system voltage V) from the A-system uninterruptible power supply 11 is input to the synchronization detection circuit 22b (see Figure 3) provided in the power switching device 20. A ) and the input voltage from the B-system uninterruptible power supply 12 (B-system voltage V) input to the synchronization detection circuit 22b. B If the two are synchronized, the signal output from the synchronization detection circuit 22b and input to the AND circuit 22a becomes an H signal. Also, if the above switching control is not performed in any power switching device 20 other than the power switching device 20 that controls the switching of the power supply source to the load 101, the A system manual switching (other) S' input to the AND circuit 22c (see Figure 3) provided in the power switching device 20 is A , and the B-system manual switching (other) S' input to the AND circuit 22c B Since each of these becomes an L signal, the signal output from AND circuit 22c and input to AND circuit 22a becomes an H signal. In this case, the signal output from AND circuit 22a and input to latch circuit 22d (see Figure 3) becomes an H signal.

[0029] In this embodiment, each of the multiple power switching devices 20 is configured to transmit a signal to the other power switching devices 20 that restricts the other power switching devices 20 from performing the switching control to switch the power supply source for the load 101 from the B-system uninterruptible power supply 12 to the A-system uninterruptible power supply 11.

[0030] Specifically, as shown in FIG. 3, the A-system manual switch S'' output from the latch circuit 22d A is input as the A-system manual switch (other) S' to the AND circuit 22c of the other power supply switching device 20 A As a result, when the A-system manual switch S'' from the latch circuit 22d A is an H signal, the A-system manual switch (other) S' input to the AND circuit 22c A becomes an H signal, so the output of the AND circuit 22c becomes an L signal. As a result, the output of the AND circuit 22a in the other power supply switching device 20 becomes an L signal. As a result, in the other power supply switching device 20, the above switching control is restricted so as not to be performed.

[0031] Next, in step S2, based on the H signal from the latch circuit 22d, the B-system current I B and the A-system voltage V A are transmitted to the B-system uninterruptible power supply 12. Specifically, based on the output of the H signal from the latch circuit 22d, the switch 22e (see FIG. 3) and the switch 22f (see FIG. 3) provided in the power supply switching device 20 are closed. As a result, the information of the A-system voltage V A input from the A-system uninterruptible power supply 11 to the power supply switching device 20 and the information of the B-system current I B input from the B-system uninterruptible power supply 12 to the power supply switching device 20 are input (see FIG. 4) to the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12.

[0032] Also, based on the A-system manual switch S'' from the latch circuit 22d A becoming an H signal, the relay 12c (see FIG. 4) provided in the B-system uninterruptible power supply 12 is switched. As a result, the voltage input to the B-system power supply side control unit 12b (output voltage control unit 42: see FIG. 5) of the B-system uninterruptible power supply 12 is changed from the bypass voltage V BP (voltage input from a bypass power supply not shown to the B-system uninterruptible power supply 12) to the A-system voltage V A from the A-system uninterruptible power supply 11 input to the power supply switching device 20.

[0033] Next, in step S3, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 controls the output voltage (INV voltage V) of the B-system uninterruptible power supply 12. BIN (See Figure 4) The A-system voltage V is input from the A-system uninterruptible power supply 11 to the power switching device 20. A Control is performed to track the phase and amplitude of the A system voltage V A and INV voltage V BIN The system is configured to perform the above tracking control based on the INV voltage V BIN This refers to the voltage output by the B-system inverter 12a of the B-system uninterruptible power supply 12.

[0034] Next, in step S4, after the above tracking control is completed, the B system switching standby signal S of the H signal is transmitted. SB This signal is output from the B-system uninterruptible power supply 12 to the power switching device 20 (see Figures 3 and 4). As a result, the signal input from the latch circuit 22d to the AND circuit 22g, and the B-system switching standby signal S input to the AND circuit 22g are transmitted. SB Since each of these signals becomes a high signal, the output from AND circuit 22g becomes a high signal. That is, A system switching command S AS and A-type thyristor on S AT Each of these will be an H signal. Note that the A system switching command S AS This is an example of a "switching signal" within the scope of the patent claims.

[0035] Next, in step S5, the A-system thyristor S of the H signal is turned on. AT When this is transmitted to the A-system thyristor 21a, the A-system thyristor 21a is turned on. At the same time, the A-system switching command S of the H signal is transmitted. AS (and L signal thyristor B system switching command S BS ) is sent to the changeover switch 21c.

[0036] Here, since semiconductor switches (thyristors) can switch at a higher speed than mechanical switches, when the A-system thyristor 21a is turned on, the changeover switch 21c remains connected to the B-system uninterruptible power supply 12 and the load 101. In other words, when the A-system thyristor 21a is turned on, the A-system thyristor 21a and the changeover switch 21c create an overlap state in which both the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12 are connected to the load 101.

[0037] In this embodiment, in step S6, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 controls the output voltage (INV voltage V) of the B-system uninterruptible power supply 12 (B-system inverter 12a) in the overlap state. BIN By controlling the phase of the input current value (B-system current I) from the B-system uninterruptible power supply 12, which is input to the power switching device 20 and detected by the current sensor 20b, the B-system current I B Input current control is performed to reduce the value of to below a predetermined threshold current. Specifically, in the above input current control, the B-system current I from the B-system uninterruptible power supply 12 is reduced. B Control is performed to reduce the current to near zero (for example, to 10% or less of the rated current).

[0038] Furthermore, in this embodiment, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 receives the input current value from the B-system uninterruptible power supply 12 (B-system current I) from the power switching device 20. B Based on this, the output voltage (INV voltage V) of the B-system uninterruptible power supply 12 (B-system inverter 12a) BIN Input current control is performed by controlling the phase of the B system current I B This is a control that reduces [the value]. Note that the above input current control is performed while the above tracking control is in place.

[0039] Specifically, the B-system power supply side control unit 12b of the B-system uninterruptible power supply unit 12 sets the above input current value (B-system current I B ) and the detected output current value of the B-series uninterruptible power supply unit 12 (UPS output current IBU (See Figure 5) Based on this, the output voltage of the B-system uninterruptible power supply 12 (INV voltage V BIN The system is configured to perform input current control by controlling the phase of the input current (UPS output current I) to reduce the input current value to below a predetermined threshold current. Specifically, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 controls the output current detection value of the B-system uninterruptible power supply 12 (UPS output current I) BU Based on the difference between ) and the above input current value, the output voltage of the B-system uninterruptible power supply 12 (INV voltage V BIN The system is configured to perform input current control by controlling the phase of the input current, thereby reducing the input current value to below a predetermined threshold current. This will be explained in more detail below with reference to Figure 5.

[0040] As shown in Figure 5, the B-system power supply side control unit 12b includes a current command calculation unit 40, an output current control unit 41, an output voltage control unit 42, and an inverter voltage command unit 43. The current command calculation unit 40 includes a switch 40a, an adder 40b, a subtractor 40c, a subtractor 40d, a low-pass filter 40e, an adder 40f, and a switch 40g.

[0041] Until the A-system thyristor 21a is turned on, the switch 40a provided in the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 is off. Therefore, the output of the adder 40b, which adds 0 and the secondary current value of the switch 40a, is 0, and the UPS output current I, which is the output current of the B-system uninterruptible power supply 12, is also off. BU The output of subtractor 40c, which subtracts the output of adder 40b from the UPS output current I BU That is the case. Furthermore, the UPS output current I BU This refers to the current flowing through busbar 30 (see Figure 1). Furthermore, when the UPS bypass switching command input to switch 40g is an L signal, switch 40g closes, resulting in the UPS output current I being reduced. BU The following is input. The UPS bypass switching command becomes an H signal when power is supplied to the load 101 from a bypass power supply (not shown), and an L signal when power is supplied to the load 101 from the uninterruptible power supply 10.

[0042] On the other hand, when the A-system thyristor 21a is turned on, the switch 40a is turned on, so the output of the adder 40b is the B-system current I that flows through the switch 40a. B At the same time, the output of subtractor 40c becomes the UPS output current I BU From B system current I B The value after subtraction (I BU -I B )

[0043] Furthermore, the subtractor 40d receives the INV current command I, which is the command value for the current value of the B-system inverter 12a, from the output of the subtractor 40c. * BIN Subtract the output of subtractor 40d (I BU -I B -I * BIN The UPS output current I is input to a low-pass filter 40e with a time constant of approximately 5 to 10 commercial power cycles. Here, when the power switching control is performed by the power switching device 20, BU and INV current command I * BIN This is equal to the value of -I. Therefore, the output of subtractor 40d is a negative value (-I B ) will be the case. Note that the UPS output current I will only be available when the uninterruptible power supply 10 can switch from bypass power supply to inverter power supply. BU and INV current command I * BIN The result will be a different value.

[0044] Furthermore, the output of the low-pass filter 40e and the INV current command I * BIN The two are added by the adder 40f. The output of the adder 40f is then input to the output current control unit 41. Based on the output of the output current control unit 41, the output voltage control unit 42 fine-tunes the phase of the output voltage of the B-system uninterruptible power supply 12, thereby adjusting the B-system current I B Input current control is performed so that the current I decreases. Here, because a low-pass filter 40e is provided, the B system current I BThe value gradually decreases. Eventually, the value input to the output current control unit 41 (the output of the adder 40f) converges to a value near 0.

[0045] Furthermore, as shown in Figure 6, the B system current I B As the A system current I decreases, A As the current I of system A increases, A and B system current I B The load current, which is the sum of the above, does not fluctuate. Therefore, the load voltage applied to load 101 also does not fluctuate. Also, the UPS output current I BU This is the B-system current I input to the power switching device 20, which is performing the switching control. B It decreases by the same amount that decreases.

[0046] Furthermore, the output voltage control unit 42, located in the B-system power supply side control unit 12b of the B-system uninterruptible power supply unit 12, receives signals from the output current control unit 41 and the INV voltage V BIN And the bypass voltage V BP Or A-system voltage V A (When switching control is performed, the A system voltage V A Based on this, control is performed to adjust the phase and peak of the output voltage of the B-series inverter 12a.

[0047] The inverter voltage command unit 43 then outputs a PWM signal (pulse signal) to control the B-system inverter 12a of the B-system uninterruptible power supply unit 12, based on the output from the output voltage control unit 42.

[0048] Next, as shown in Figure 2, in step S7, after the input current control described above, the power changeover device 20 disconnects the B-system uninterruptible power supply 12 and the load 101. Specifically, as shown in Figure 6, after the input current control described above, with the A-system thyristor 21a connecting the A-system uninterruptible power supply 11 and the load 101, the contact of the changeover switch 21c switches from the B-system main contact 20d (see Figure 1) to the A-system main contact 20c (see Figure 1). The overlap state is released when the changeover switch 21c moves away from the B-system main contact 20d.

[0049] In detail, in step S5, a switching signal (A system switching command S) is sent to the changeover switch 21c. AS After the transmission of the switching signal (i.e., after the A-system thyristor 21a is turned on), the changeover switch 21c switches after a predetermined switching time T (see Figure 6) (for example, 0.1 s), thereby connecting the A-system uninterruptible power supply 11 and the load 101 via the changeover switch 21c. The predetermined switching time is the time required from when the switching signal is transmitted to the changeover switch 21c until the switching is completed.

[0050] Furthermore, in this embodiment, the input current control is performed between the time the A-system thyristor 21a is turned on and the time the A-system uninterruptible power supply 11 and the load 101 are connected by the changeover switch 21c. In other words, in the uninterruptible power supply system 100, the input current control is completed within the time difference between the turn-on time of the A-system thyristor 21a and the switching time T of the changeover switch 21c, which is a mechanical switch.

[0051] Then, based on the switching performed by the changeover switch 21c, the A-system MC answer back AB is input to the AND circuit 22a. A (See Figure 3) The B-type MC answer back AB is an H signal and is input to the AND circuit 22a. B (See Figure 3) becomes an L signal. This resets the latch circuit 22d. As a result, the signal output from the latch circuit 22d (A-system manual switching) becomes an L signal. This results in the A-system manual switching S'' being an L signal. A (See Figure 3) This is the A system manual switching S' of the AND circuit 22c of the other power switching device 20. A As the input is set as shown in Figure 3, the state in which the output of the AND circuit 22c is restricted (locked) to an L signal is released. In other words, manual switching control of the power supply in the other power switching device 20 becomes possible.

[0052] Furthermore, the latch circuit 22d sends an L signal to the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12, which is the A-system manual switching S''. AWhen this is input, the relay 12c (see FIG. 4) is switched, and the target to be followed of the output voltage (INV voltage V of the B system uninterruptible power supply device 12) BIN is switched from the A system voltage V A to the bypass voltage V BP . As a result, the B system switching standby signal S SB transmitted from the B system power supply side control unit 12b to the switching device side control unit 22 becomes an L signal.

[0053] Also, since the signal output from the latch circuit 22d becomes an L signal, the output of the AND circuit 22g also becomes an L signal. As a result, the A system switching command S AS input to the changeover switch 21c and the A system thyristor on S AT input to the A system thyristor 21a are each set to an L signal. Thereby, the gate signal of the A system thyristor 21a is turned off (see FIG. 6).

[0054] The same applies when changing the power supply source to the load 101 from the A system uninterruptible power supply device 11 to the B system uninterruptible power supply device 12. Briefly explained, as shown in FIG. 3, the B system manual switching signal S B , the A system MC answer back AB A , and the B system MC answer back AB B become an H signal, an H signal, and an L signal, respectively. Thereby, the B system switching command S BS and the B system thyristor on S BT each become an H signal. Thereby, the information of the B system voltage V B and the information of the A system current I A input from the A system uninterruptible power supply device 11 to the power supply switching device 20 are input to the A system power supply side control unit 11b of the A system uninterruptible power supply device 11. Also, when the B system manual switching S’’ B becomes an H signal, the B system manual switching (other) S’ B becomes an H signal. Also, after the above follow-up control is completed, the A system switching standby signal S SA of the H signal is output from the A system uninterruptible power supply device 11 to the power supply switching device 20. And in the A system power supply side control unit 11b of the A system uninterruptible power supply device 11, the A system current I AThe above current control is performed to converge to 0. Note that the B system switching command S BS This is an example of a "switching signal" within the scope of the patent claims.

[0055] (Effects of this embodiment) In this embodiment, the following effects can be obtained.

[0056] In this embodiment, as described above, when both the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12 are connected to the load 101 in an overlap state, and the power switching device 20 switches the power supply source to the load 101 from the B-system uninterruptible power supply 12 to the A-system uninterruptible power supply 11, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 controls the output voltage (INV voltage V) of the B-system uninterruptible power supply 12. BIN By controlling the phase of the B-system uninterruptible power supply 12, the input current value (B-system current I) input from the B-system uninterruptible power supply 12 to the power switching device 20 is controlled. B The uninterruptible power supply system 100 is configured such that, after performing input current control to reduce the input current value to below a predetermined threshold current, the power switching device 20 disconnects the B-system uninterruptible power supply 12 and the load 101. This prevents momentary power interruptions that would occur if the power supply to the load 101 were interrupted due to switching control of the power supply source in an overlap state. Furthermore, by performing input current control to reduce the above input current value to below a predetermined threshold current, it is possible to suppress an increase in the short-circuit current (cross-current) flowing between the B-system uninterruptible power supply 12 and the A-system uninterruptible power supply 11 caused by the input current input from the B-system uninterruptible power supply 12 to the power switching device 20 in an overlap state. In this way, it is possible to prevent momentary power interruptions that would occur if the power supply to the load 101 were interrupted while suppressing an increase in the short-circuit current (cross-current) flowing between the B-system uninterruptible power supply 12 and the A-system uninterruptible power supply 11. As a result, even when the distances (impedances) between each of the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12 and the power switching device 20 are different, it is possible to suppress an increase in short-circuit current (cross-current).

[0057] Furthermore, in this embodiment, as described above, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 controls the output voltage (INV voltage V) of the B-system uninterruptible power supply 12. BIN ) is input voltage (A-system voltage V) from the A-system uninterruptible power supply 11 to the power switching device 20. A The uninterruptible power supply system 100 is configured to track the phase and amplitude of the two systems and then perform input current control in an overlap state. This allows input current control to be performed while the output voltage of the B-system uninterruptible power supply 12 tracks the voltage of the A-system uninterruptible power supply 11, thereby further suppressing the increase in short-circuit current (cross-current) flowing between the A-system uninterruptible power supply 11 and the B-system uninterruptible power supply 12.

[0058] Furthermore, in this embodiment, as described above, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 inputs the input current value from the B-system uninterruptible power supply 12 (B-system current I) to the power switching device 20. B Based on this, the output voltage of the B-system uninterruptible power supply 12 (INV voltage V BIN The uninterruptible power supply system 100 is configured to perform input current control, which reduces the input current value to below a predetermined threshold current by controlling the phase of the current. This allows for feedback control, which controls the input current value based on the input current value from the B-system uninterruptible power supply 12 input to the power switching device 20, making it easy to perform input current control to reduce the input current value to below a predetermined threshold current.

[0059] Furthermore, in this embodiment, as described above, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 sets the input current value (B-system current I B ) and the detected output current value of the B-series uninterruptible power supply unit 12 (UPS output current I BU Based on this, the output voltage of the B-system uninterruptible power supply 12 (INV voltage V BINThe uninterruptible power supply system 100 is configured to perform input current control, which reduces the input current value to below a predetermined threshold current by controlling the phase of the input current. This makes it possible to control the input current value based on the output current detection value of the B-system uninterruptible power supply unit 12 in addition to the input current value, thus making it easier to perform input current control to reduce the input current value to below a predetermined threshold current.

[0060] Furthermore, in this embodiment, as described above, the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 detects the output current value of the B-system uninterruptible power supply 12 (UPS output current I BU ) and input current value (B system current I B Based on the difference with ), the output voltage of the B-system uninterruptible power supply 12 (INV voltage V BIN The uninterruptible power supply system 100 is configured to perform input current control, which reduces the input current value to below a predetermined threshold current by controlling the phase of the input current. As a result, by performing input current control based on the difference between the output current detection value of the B-system uninterruptible power supply 12 and the input current value, the output current detection value of the B-system uninterruptible power supply 12 is reduced by the amount of the input current value, making it easy to reduce the output current of the B-system uninterruptible power supply 12. Consequently, the input current value output from the B-system uninterruptible power supply 12 and input to the power switching device 20 can be easily reduced.

[0061] Furthermore, in this embodiment, as described above, the uninterruptible power supply system 100 is configured such that each switching device side control unit 22 of the multiple power switching devices 20 transmits a signal to the other power switching devices 20 to restrict switching control from being performed in the other power switching devices 20, based on the fact that switching control is being performed in the other power switching devices 20. This makes it possible to suppress switching control from being performed in other power switching devices 20 when switching control is being performed in one power switching device 20, and as a result, it is possible to suppress the input current control in one power switching device 20 from becoming abnormal due to abnormalities such as current (cross-current) flowing between power switching devices 20.

[0062] Furthermore, in this embodiment, as described above, the uninterruptible power supply system 100 is configured such that the B-system power supply side control unit 12b of the B-system uninterruptible power supply 12 performs the input current control between the time the A-system thyristor 21a is turned on and the A-system uninterruptible power supply 11 and the load 101 are connected by the changeover switch 21c. As a result, the turn-on time of the semiconductor switch is shorter than the switching time of the mechanical switch, so the input current control can be easily performed within the time difference between the turn-on time of the A-system thyristor 21a and the switching time of the changeover switch 21c, which is a mechanical switch.

[0063] (modified version) It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than by the description of the embodiments above, and further includes all modifications (exceptions) within the meaning and scope equivalent to the claims.

[0064] For example, in the above embodiment, an example was shown in which the output voltage of the B-system uninterruptible power supply 12 was made to track the phase and amplitude of the input voltage input from the A-system uninterruptible power supply 11 to the power switching device 20, and then input current control was performed. However, the present invention is not limited to this. Input current control may be performed without performing the above tracking control.

[0065] Furthermore, although the above embodiment shows an example in which the input current value input from the B-system uninterruptible power supply 12 to the power switching device 20 is reduced to 10% or less of the rated current by input current control, the present invention is not limited to this. The input current value may be reduced to 0.

[0066] Furthermore, in the above embodiment, a signal to turn on the A-system thyristor 21a (second semiconductor switch) is transmitted to the A-system thyristor 21a, and at the same time, an A-system switching command S is sent to the changeover switch 21c to connect the A-system uninterruptible power supply 11 and the load 101. ASAn example of transmitting a (switching signal) has been shown, but the present invention is not limited to this. The timing of transmitting a signal to turn on the A-system thyristor 21a to the A-system thyristor 21a and the A-system switching command S to the changeover switch 21c. AS It's okay if there's a delay in the timing of sending it.

[0067] Furthermore, although the above embodiment shows an example in which A-type thyristor 21a (second semiconductor switch) and B-type thyristor 21b (first semiconductor switch) are used, the present invention is not limited thereto. Other semiconductor switches (for example, IGBT elements and MOSFETs) may be used instead of thyristors. [Explanation of Symbols]

[0068] 11 A-system uninterruptible power supply (1st uninterruptible power supply) (2nd uninterruptible power supply) 11b A-system power supply side control unit (first control unit) (second control unit) 12 B-system uninterruptible power supply (1st uninterruptible power supply) (2nd uninterruptible power supply) 12b B-system power supply side control unit (first control unit) (second control unit) 20 Power switching device 20a, 20b Current sensor (input current detection unit) 21a A-type thyristor (first semiconductor switch) (second semiconductor switch) 21b B-series thyristor (first semiconductor switch) (second semiconductor switch) 21c changeover switch 22 Switching device side control unit 100 Uninterruptible Power Supply Systems 101 load

Claims

1. A first uninterruptible power supply (UPS) including a first control unit and a second uninterruptible power supply (UPS) including a second control unit, which supply power to the same load, A power switching device that switches the power supply source for the load from the first uninterruptible power supply to the second uninterruptible power supply, The system includes an input current detection unit that detects the input current value input from the first uninterruptible power supply to the power switching device, An uninterruptible power supply system configured such that, in an overlap state where both the first uninterruptible power supply and the second uninterruptible power supply are simultaneously connected to the load, when the power switching device switches the power supply source to the load from the first uninterruptible power supply to the second uninterruptible power supply, the first control unit of the first uninterruptible power supply controls the phase of the output voltage of the first uninterruptible power supply, thereby performing input current control by feedback control on the input current value input from the first uninterruptible power supply to the power switching device and detected by the input current detection unit, thereby reducing the input current to below a predetermined threshold current, and then the power switching device disconnects the first uninterruptible power supply from the load.

2. The uninterruptible power supply system according to claim 1, wherein the first control unit of the first uninterruptible power supply is configured to track the output voltage of the first uninterruptible power supply so as to match the phase and amplitude of the input voltage input from the second uninterruptible power supply to the power switching device, and then perform the input current control in the overlap state.

3. The uninterruptible power supply system according to claim 1 or 2, wherein the first control unit of the first uninterruptible power supply is configured to perform input current control, which reduces the input current value to a predetermined threshold current or less by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value from the first uninterruptible power supply input to the power switching device.

4. A first uninterruptible power supply including a first control unit and a second uninterruptible power supply including a second control unit, which supply power to the same load, A power switching device that switches the power supply source for the load from the first uninterruptible power supply to the second uninterruptible power supply, The system includes an input current detection unit that detects the input current value input from the first uninterruptible power supply to the power switching device, In an overlap state where both the first and second uninterruptible power supplies are simultaneously connected to the load, when the power switching device switches the power supply source to the load from the first uninterruptible power supply to the second uninterruptible power supply, the first control unit of the first uninterruptible power supply controls the phase of the output voltage of the first uninterruptible power supply, thereby performing input current control to reduce the input current value input from the first uninterruptible power supply to the power switching device and detected by the input current detection unit to below a predetermined threshold current. After this, the power switching device is configured to disconnect the first uninterruptible power supply from the load. The first control unit of the first uninterruptible power supply is configured to perform input current control, which reduces the input current value to below a predetermined threshold current by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value from the first uninterruptible power supply input to the power switching device, An uninterruptible power supply system in which the first control unit of the first uninterruptible power supply is configured to perform input current control, thereby reducing the input current value to below a predetermined threshold current by controlling the phase of the output voltage of the first uninterruptible power supply based on the input current value and the output current detection value of the first uninterruptible power supply.

5. The uninterruptible power supply system according to claim 4, wherein the first control unit of the first uninterruptible power supply is configured to perform input current control, which reduces the input current value to a predetermined threshold current or less by controlling the phase of the output voltage of the first uninterruptible power supply based on the difference between the output current detection value and the input current value of the first uninterruptible power supply.

6. The power switching device includes a switching device-side control unit that performs switching control to switch the power supply source to the load from the first uninterruptible power supply to the second uninterruptible power supply, and multiple such devices are provided to correspond to multiple loads. The uninterruptible power supply system according to any one of claims 1 to 5, wherein the control unit on the switching device side of each of the plurality of power switching devices is configured to transmit a signal to the other power switching devices to restrict the other power switching devices from performing the switching control based on the fact that the switching control is being performed.

7. The power switching device includes a first semiconductor switch disposed between the first uninterruptible power supply and the load, a second semiconductor switch disposed between the second uninterruptible power supply and the load, a mechanical changeover switch for switching between connecting the first uninterruptible power supply and the load or connecting the second uninterruptible power supply and the load, and a switching device side control unit that performs switching control to switch the power supply source to the load from the first uninterruptible power supply to the second uninterruptible power supply. The control unit on the switching device side is configured to transmit a signal to the second semiconductor switch to turn on the second semiconductor switch when the first uninterruptible power supply and the load are connected by the switching switch, and at the same time transmit a switching signal to the switching switch to connect the second uninterruptible power supply and the load. The uninterruptible power supply system according to any one of claims 1 to 6, wherein the first control unit of the first uninterruptible power supply is configured to perform input current control between the time the second semiconductor switch is turned on and the second uninterruptible power supply and the load are connected by the changeover switch.

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