JP7453096B2 - Uninterruptible power system - Google Patents

Description

The present disclosure relates to an uninterruptible power supply.

BACKGROUND ART Conventionally, uninterruptible power supply devices have been known that supply power from a storage battery to a load when a commercial power supply fails, and supply power from the commercial power supply to the load when the power is restored.

Further, an uninterruptible power supply system has been proposed that is configured with a plurality of uninterruptible power supply devices (UPS) that constantly supply power to a load as redundant control.

JP 2017-50933 Publication

On the other hand, even in a configuration in which a plurality of UPSs are provided, the device life cannot be extended because the UPSs are always in operation. Furthermore, the lifespan of storage batteries cannot be extended. Extending the life of the device is an important issue in environments where it is not easy to replace the UPS.

The present disclosure has been made to solve the above problems, and provides an uninterruptible power supply that can extend the life of the device.

An uninterruptible power supply according to a certain aspect includes a power conversion device including an AC/DC converter that converts an AC voltage to a DC voltage, a DC/AC converter that converts the DC voltage to an AC voltage and supplies the AC voltage to an AC load, and a DC/DC converter that converts an AC voltage to a DC voltage. It includes a power storage device connected in parallel with the AC converter to store DC voltage and supply power to the AC load, and a controller to control the power converter and the power storage device. The power storage device includes a plurality of storage battery units each having an internal switch and connected in parallel to each other, and the controller controls the plurality of storage battery units by instructing conduction/non-conduction of the internal switch of each storage battery unit. Some of the storage battery units are connected to the DC/AC converter, the remaining storage battery units of the plurality of storage battery units are disconnected, and the connection state is sequentially switched according to predetermined conditions.

Preferably, the controller controls the power so that, when a predetermined condition is met, the floating voltage of at least one storage battery unit among some of the storage battery units of the plurality of storage battery units becomes a second voltage higher than the first voltage. instructing the converter to set the internal switches of the remaining battery units of the plurality of battery units to conduction when the floating voltage of the at least one battery unit becomes a second voltage; sets the internal switch to non-conducting, and instructs the power converter so that the floating voltage of the remaining storage battery units among the plurality of storage battery units becomes the first voltage.

Preferably, the power conversion device further includes a chopper circuit connected in parallel with the DC/AC converter to step down the DC voltage and supply it to the power storage device, and the controller is configured to control the chopper circuit to reduce the DC voltage to be supplied to the power storage device. to the first voltage or the second voltage.

Preferably, the predetermined condition is every lapse of a predetermined period.

Preferably, a plurality of power converters are provided which are connected in parallel to the AC load and whose connection to the AC load can be switched, and the plurality of power converters are switched according to predetermined conditions.

According to one embodiment, an uninterruptible power supply can extend device life.

FIG. 1 is a diagram illustrating a circuit configuration of an uninterruptible power supply 1 based on an embodiment. FIG. 2 is a diagram illustrating a configuration of a power storage device 6 based on an embodiment. FIG. 6 is a diagram illustrating operation of power storage device 6 based on the embodiment. It is a figure explaining the switching of the storage battery unit according to an embodiment. FIG. 3 is a diagram illustrating a flow of switching processing of the controller 20 according to the embodiment. FIG. 2 is a diagram illustrating switching processing of power conversion devices 10-1 and 10-2 according to the embodiment.

This embodiment will be described in detail with reference to the drawings. Note that the same or corresponding parts in the figures are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a diagram illustrating a circuit configuration of an uninterruptible power supply 1 based on the embodiment.

As shown in FIG. 1, the uninterruptible power supply 1 includes a plurality of power converters 10-1 and 10-2 connected in parallel to each other for an AC load, and a controller 20 that controls the uninterruptible power supply 1. including. The power converters 10-1 and 10-2 are connected to an AC input power source 4 and a bypass input power source 2 on the input side. Further, power conversion devices 10-1 and 10-2 are also connected to power storage device 6.

AC input power source 4 and bypass input power source 2 are AC power sources that supply AC power to power converters 10-1 and 10-2. Each of these input power sources is configured by, for example, a commercial AC power source or a private generator.

A three-phase three-wire (3φ3W) type is shown as an example of an input AC power source. However, the type of input AC power source is not limited to a three-phase, three-wire type, and may be, for example, a three-phase, four-wire type power source, or a single-phase, three-wire type power source.

The power conversion devices 10-1 and 10-2 have the same configuration, and include electromagnetic contactors (contactors) 14, 15, 17, 18, 19, a converter (CNV) 11, an inverter (INV) 12, and a chopper. (CHP) 13 and a thyristor switch 16.

Contactor 14 is inserted and connected to a current-carrying path between AC input power source 4 and converter 11 . Contactor 14 opens (turns on) and closes (turns off) in response to commands from controller 20 . Converter 11 converts AC power supplied from AC input power source 4 into DC power. The inverter 12 converts DC power into AC power of a predetermined voltage and a predetermined frequency. Chopper 13 converts the voltage level of the DC voltage output from converter 11 and supplies it to power storage device 6 . Note that each of the converter 11, inverter 12, and chopper 13 is controlled by a controller 20.

Contactors 17 and 19 are inserted and connected to a current-carrying path between the output terminal and inverter 12. Contactors 17 and 19 open (turn on) and close (turn off) in response to commands from controller 20 .

The contactor 15 is used to switch the AC output output from the output terminal to the AC load between the output of the inverter 12 and the output of a bypass circuit including the thyristor switch 16 and the contactor 15.

Thyristor switch 16 and contactor 15 are connected in parallel between the bypass input terminal and the output terminal. The thyristor switch 16 is a switch for quickly switching the AC output output from the output terminal to the AC load from the output of the inverter 12 to the AC power from the bypass input power source 2. The contactor 15 is inserted and connected to the current-carrying path from the bypass input terminal to the output terminal. The contactor 15 is for maintaining the AC power from the bypass input power supply 2 as an AC output output from the uninterruptible power supply. Contactor 15, thyristor switch 16, and contactors 17 and 19 close (turn on) and open (turn off) in response to commands from controller 20.

Contactor 18 is provided between power storage device 6 and chopper 13 . Contactor 18 closes (turns on) and opens (turns off) in response to commands from controller 20 .

Power storage device 6 is a device for supplying DC power to inverter 12 when AC input power source 4 cannot supply AC power (for example, during a power outage).

In this example, as an example, power storage device 6 is provided commonly to power conversion devices 10-1 and 10-2. Note that the power storage devices 6 may be provided independently.

During normal times when AC power is supplied from AC input power source 4, DC power generated by converter 11 is stored in power storage device 6, and is converted to AC power by inverter 12 and supplied to an AC load. On the other hand, during a power outage when the supply of AC power from the AC input power source 4 is stopped, the operation of the converter 11 is stopped, and the DC power stored in the power storage device 6 is converted to AC power by the inverter 12 and supplied to the AC load. Ru. Therefore, according to the uninterruptible power supply, even in the event of a power outage, the operation of the AC load can be continued using the power stored in the power storage device 6.

Controller 20 controls converter 11 and inverter 12 in order to generate AC power to be supplied to AC loads during normal times and during power outages. As an example, the computer is mainly composed of a microcomputer including a CPU (Central Processing Unit) and a storage section such as a ROM (Read Only Memory) or a RAM (Random Access Memory). The controller 20 controls the converter 11, the inverter 12, etc. by having the CPU read out a program stored in a ROM or the like in advance into the RAM and execute it. In addition to controlling the converter 11 and inverter 12, the controller 20 also controls the contactors 14, 15, 17, and 19, the thyristor switch 16, and the bypass circuit. Furthermore, controller 20 controls power storage device 6 . Note that at least a portion of the controller 20 may be configured to execute predetermined numerical/logical calculation processing using hardware such as an electronic circuit.

FIG. 2 is a diagram illustrating the configuration of power storage device 6 based on the embodiment. As shown in FIG. 2, power storage device 6 includes a plurality of storage battery units 6-1 to 6-5. Each of storage battery units 6-1 to 6-5 has the same configuration. The storage battery unit 6 is, for example, a lithium ion battery.

Each storage battery unit 6-1 includes a storage cell 8-1, an internal switch 7-1, and an internal controller 9-1. The internal controller 9-1 monitors the charging state of the storage battery unit 6-1 and controls conduction/non-conduction of the internal switch 7-1. Internal controller 9-1 notifies controller 20 of the charging state of storage battery unit 6-1.

The other storage battery units 6-2 to 6-5 are also similar to the storage battery unit 6-1, so detailed description thereof will not be repeated.

FIG. 3 is a diagram illustrating the operation of power storage device 6 based on the embodiment.

As shown in FIG. 3, in this example, instead of operating all of the plurality of storage battery units 6-1 to 6-5 of the power storage device 6 at the same time, some of the storage battery units are operated and the remaining battery units are operated. Stop the storage battery unit. Then, the storage battery units to be operated are sequentially switched according to predetermined conditions. Specifically, by instructing the internal switches 7-1 to 7-5 of the storage battery units 6-1 to 6-5 to be conductive/non-conductive, some of the plurality of storage battery units 6-1 to 6-5 are turned off. The storage battery unit is connected to the converter 11, the remaining storage battery units of the plurality of storage battery units 6-1 to 6-5 are disconnected, and the connection state is sequentially switched according to predetermined conditions.

In this example, a case where the predetermined condition is sequentially switched every month is shown.

As an example, for the first month, the storage battery unit 6-1 is stopped and the other storage battery units 6-2 to 6-5 are operated. For the next month, the storage battery unit 6-2 is stopped and the other storage battery units 6-1, 6-3 to 6-5 are operated. For the next month, the storage battery unit 6-3 is stopped and the other storage battery units 6-1, 6-2, 6-4, and 6-5 are operated. For the next month, the storage battery unit 6-4 is stopped and the other storage battery units 6-1 to 6-3 and 6-5 are operated. For the next month, the storage battery unit 6-5 is stopped and the other storage battery units 6-1 to 6-4 are operated.

As a result, instead of all the storage battery units 6-1 to 6-5 operating, some of the storage battery units are stopped (paused) and switched sequentially, so that each storage battery unit 6-1 to 6-5 is activated during a predetermined period. This makes it possible to shorten the operating time. That is, when the operating time is defined as the device life, it is possible to extend the life of the power storage device 6 having the storage battery unit compared to the conventional method.

FIG. 4 is a diagram illustrating switching of storage battery units based on the embodiment. As shown in FIG. 4, predetermined control is executed when switching the storage battery units.

Specifically, the controller 20 selects one of the plurality of storage battery units 6-1 to 6-5 when a predetermined condition is satisfied. Here, the selected storage battery unit is later set to a non-conductive state. In this example, the case where the storage battery unit 6-1 is selected is shown as an example. Further, the controller 20 sets all storage battery units 6-1 to 6-5 to a conductive state. Specifically, the storage battery unit 6-5, which has been in a non-conductive state, is set to a conductive state.

Next, in this example, an instruction to increase the floating voltage by +5V is output. The controller 20 instructs the chopper 13 to increase the floating voltage by +5V. In this example, the chopper 13 sets the floating voltage to a second voltage that is 5V higher than the first voltage during normal operation.

The voltages of the storage battery units 6-1 to 6-5 are stored while being set to a second voltage that is 5V higher than the first voltage.

Next, the controller 20 instructs the chopper 13 to return the floating voltage to the original voltage. Specifically, the floating voltage is returned from the second voltage to the first voltage.

Next, the controller 20 sets the storage battery unit 6-1 to a non-conductive state. As a result, the storage battery unit 6-1 stops.

Therefore, when the storage battery unit 6-1 is switched from the operating state to the stopped state, the charging state of the storage battery unit 6-1 is set to a second voltage that is +5V higher than the normal floating voltage (first voltage). It will be stopped in a state where it is stopped. The charging state of the storage battery unit 6-1 is such that when it is stopped, its voltage level gradually decreases due to discharge. In this example, the switching process is executed again at the timing when the charging state of the storage battery unit 6-1 is set to the second voltage and then lowered to the first voltage due to discharge. In this example, it is estimated that the state of charge will drop from the second voltage to the first voltage after one month due to discharge.

Next, the controller 20 executes the storage battery unit switching process at the timing when one month has passed as a predetermined condition. Specifically, the controller 20 selects the storage battery unit 6-2 from the storage battery units 6-1 to 6-5. Further, the controller 20 sets all storage battery units 6-1 to 6-5 to a conductive state. Specifically, the storage battery unit 6-1, which has been in a non-conductive state, is set to a conductive state.

Next, the controller 20 instructs the chopper 13 to increase the floating voltage by +5V. In this example, the chopper 13 sets the floating voltage to a second voltage that is 5V higher than the first voltage during normal operation. In this example, a method will be described in which the controller 20 instructs the chopper 13 to increase the floating voltage by +5V. In the case of a configuration in which the converter 11 is connected to the converter 11, the converter 11 may be instructed to increase the output voltage of the converter 11 by 5V.

The voltages of the storage battery units 6-1 to 6-5 are stored while being set to a second voltage that is 5V higher than the first voltage.

Next, the controller 20 instructs the chopper 13 to return the floating voltage to the original voltage. Specifically, the floating voltage is returned from the second voltage to the first voltage.

Next, the controller 20 sets the storage battery unit 6-2 to a non-conductive state. As a result, the storage battery unit 6-2 stops.

Therefore, when the storage battery unit 6-2 is switched from the operating state to the stopped state, the charging state of the storage battery unit 6-2 is set to a second voltage that is +5V higher than the normal floating voltage (first voltage). It will be stopped in a state where it is stopped. The charging state of the storage battery unit 6-2 is such that when it is stopped, its voltage level gradually decreases due to discharge. In this example, the switching process is executed again at the timing when the charging state of the storage battery unit 6-2 is set to the second voltage and then lowered to the first voltage due to discharge. In this example, it is estimated that the state of charge will drop from the second voltage to the first voltage after one month due to discharge. Therefore, when switching from the stopped state to the operating state, there is no voltage difference between other storage battery units, so it is possible to suppress excessive flow of charging current.

The same applies when switching other storage battery units.

By performing the switching process in this manner, it becomes possible to perform the switching process while always maintaining the storage battery units 6-1 to 6-5 at a floating voltage.

In this example, we have explained a case in which the 5V voltage is increased and after one month, the increased voltage drops to the voltage level of the floating voltage, but the voltage level of the floating voltage is not limited to one month. The switching timing may be changed depending on the period of time. Furthermore, the switching timing may be changed by setting a higher voltage instead of 5V.

Furthermore, the switching timing may be changed by monitoring the voltage level of the rechargeable battery unit in the stopped state. Specifically, the charge level of the rechargeable battery unit is monitored, and it is determined whether the voltage level of the rechargeable battery unit in the stopped state has decreased to a first voltage, and the voltage level of the rechargeable battery unit in the stopped state is determined. It may be determined that the predetermined condition is satisfied when it is determined that the voltage has decreased to the first voltage. Then, the above switching process may be executed.

FIG. 5 is a diagram illustrating a flow of switching processing of the controller 20 based on the embodiment.

As shown in FIG. 5, the controller 20 determines whether a predetermined condition is satisfied (step S2). An example of the predetermined condition is whether one month has passed.

In step S20, when the controller 20 determines that the predetermined condition is satisfied (YES in step S20), it selects one storage battery unit from among the plurality of storage battery units in a conductive state (step S4). Next, the controller 20 sets the non-conducting storage battery unit to a conducting state (step S6). Next, the controller 20 instructs to increase the floating voltage from the first voltage to the second voltage (step S8). Specifically, the controller 20 instructs the chopper 13 to increase the floating voltage by +5V. Next, the controller 20 determines whether the floating voltage is equal to or higher than the second voltage (step S10). In step S10, if the controller 20 determines that the floating voltage is not equal to or higher than the second voltage (NO in step S10), the process returns to step S8 and repeats the above processing.

On the other hand, in step S10, if the controller 20 determines that the floating voltage is equal to or higher than the second voltage (YES in step S10), the controller 20 causes the floating voltage to decrease from the second voltage to the first voltage. (Step S12). Next, the controller 20 sets the selected storage battery unit to a non-conductive state (step S16). Next, the controller 20 returns to step S2 and repeats the above process. Specifically, when the predetermined condition is satisfied, the controller 20 selects another storage battery unit from among the plurality of storage battery units in the conducting state, increases the floating voltage as described above, and then sets the non-conducting battery unit. Set to conductive state. Repeat the process.

By performing the switching process in this manner, it is possible to always maintain the storage battery units 6-1 to 6-5 at a floating voltage. Furthermore, it is possible to sequentially stop one of the storage battery units 6-1 to 6-5. As a result, instead of all the storage battery units 6-1 to 6-5 operating, some of the storage battery units are stopped (paused) and switched sequentially, so that each storage battery unit 6-1 to 6-5 is activated during a predetermined period. This makes it possible to shorten the operating time. That is, when the operating time is defined as the device life, it is possible to extend the life of the power storage device 6 having the storage battery unit compared to the conventional method.

In this example, a method has been described in which five storage battery units 6-1 to 6-5 are sequentially switched, but the number is not limited to five and any number can be selected as appropriate. Further, the number of storage battery units whose operation is to be stopped is not limited to one, and a plurality of storage battery units may be stopped at the same time, and the number can be selected as appropriate.

FIG. 6 is a diagram illustrating switching processing of power converters 10-1 and 10-2 based on the embodiment. As shown in FIG. 6, as an example, the operation of power converter 10-1 and power converter 10-2 is switched. Specifically, in this example, a case is shown in which switching is performed every year.

As a result, instead of all power converters 10-1 and 10-2 always operating, some power converters 10-2 are stopped (paused) and switched sequentially, so that each power converter during a predetermined period of time is It becomes possible to shorten the operation time of 10-1 and 10-2. That is, when the operating time is defined as the device life, it is possible to extend the life of the uninterruptible power supply having the voltage conversion circuit compared to the conventional system.

In addition, in this example, the case where switching is performed every year is shown, but it may be made to be switched every month similarly to the storage battery unit.

In addition, although the above describes a method for sequentially switching the two power converters 10-1 and 10-2, it is of course also possible to connect a plurality of power converters 10 in parallel and sequentially switch them. It is.

The above method is particularly effective in an environment where it is not easy to replace a UPS, for example. For example, when a UPS is installed on a ship, and long-term replacement work is not easy, extending the life of the device makes it possible to safely secure a power source for a long period of time, which is useful.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Uninterruptible power supply, 2 Bypass input power supply, 4 AC input power supply, 6 Power storage device, 6-1 to 6-5 Storage battery unit, 7-1 to 7-5 Internal switch, 8-1 to 8-5 Energy storage cell, 9-1 to 9-5 internal controller, 10 power converter, 11 converter, 12 inverter, 13 chopper, 14, 15, 17, 19 contactor, 16 thyristor switch, 20 controller.

Claims (4)

a power conversion device including an AC-DC converter that converts AC voltage to DC voltage; and a DC-AC converter that converts DC voltage to AC voltage and supplies it to an AC load;
a power storage device connected in parallel with the DC/AC converter to store the DC voltage and supply power to the AC load;
A controller that controls the power conversion device and the power storage device,
The power storage device includes a plurality of storage battery units each having an internal switch and connected in parallel to each other,
The controller connects some of the plurality of storage battery units to the DC/AC converter by instructing conduction/non-conduction of the internal switch of each of the storage battery units, and connects some of the plurality of storage battery units to the DC/AC converter. The remaining storage battery units are disconnected, and the connected status is sequentially switched according to predetermined conditions.
The controller includes:
selecting at least one storage battery unit to be set to a non-conducting state from among the plurality of storage battery units when the predetermined condition is met;
setting the internal switch of a storage battery unit in a non-conductive state among the plurality of storage battery units to conductive;
instructing the power converter so that the floating voltage of the plurality of storage battery units becomes a second voltage higher than the first voltage;
instructing the power converter so that when the floating voltage of the plurality of storage battery units becomes the second voltage, the floating voltage of the plurality of storage battery units becomes the first voltage;
An uninterruptible power supply device that sets the internal switch of at least one storage battery unit selected from the plurality of storage battery units to be non-conductive . The power conversion device further includes a chopper circuit that is connected in parallel with the DC-AC converter and steps down the DC voltage and supplies the DC voltage to the power storage device,
The uninterruptible power supply according to claim 1, wherein the controller instructs the chopper circuit so that the DC voltage supplied to the power storage device becomes the first voltage or the second voltage . The uninterruptible power supply according to claim 1 or 2, wherein the predetermined condition is every lapse of a predetermined period . A plurality of power conversion devices are provided that are connected in parallel to the AC load and are provided so that connection with the AC load can be switched,
The uninterruptible power supply according to claim 1, wherein the plurality of power converters are switched according to the predetermined condition .

Images