WO2019053883A1

WO2019053883A1 - Power supply device

Info

Publication number: WO2019053883A1
Application number: PCT/JP2017/033485
Authority: WO
Inventors: 俊秀中野
Original assignee: 東芝三菱電機産業システム株式会社
Priority date: 2017-09-15
Filing date: 2017-09-15
Publication date: 2019-03-21

Abstract

This uninterruptible power supply device: obtains the present capacitor characteristics on the basis of deterioration information indicating the relationship among the characteristics (C, R) of a capacitor (23), the use condition (Tc, VDC) thereof, and the use time (TU) thereof, and on the basis of the detected values of the use conditions and the use time of the capacitor; obtains a target value (VDCT) of the inter-terminal voltage (VDC) of the capacitor on the basis of the characteristics, a load capacity (P), and a rated time (Tr); and charges the capacitor such that the inter-terminal voltage of the capacitor becomes equal to the target value.

Description

Power supply

The present invention relates to a power supply device, and in particular, DC power is stored in a capacitor when AC voltage of a commercial AC power supply is normal, and rated time based on DC power of a capacitor when AC voltage of a commercial AC power supply is not normal. The present invention relates to a power supply that drives only a load.

For example, according to JP 2009-177901 A (Patent Document 1), one terminal is connected to a commercial AC power supply, and the other terminal is connected between a switch connected to a load and the other terminal of the switch and a capacitor. An uninterruptible power supply comprising a power converter is disclosed.

When the AC voltage of the commercial AC power supply is normal, the switch is turned on, AC power is supplied from the commercial AC power supply to the load through the switch, and the load is driven. The power converter converts AC power from a commercial AC power supply into DC power and stores the DC power. The voltage across the terminals of the capacitor is maintained at a constant value.

When the AC voltage of the commercial AC power supply is not normal, the switch is turned off, and the power converter converts DC power of the capacitor into AC power and supplies it to the load. Therefore, even when the AC voltage of the commercial AC power supply is not normal, the operation of the load can be continued based on the DC power of the capacitor.

JP, 2009-177901, A

Such an uninterruptible power supply is required to be able to operate a load with a rated capacity (for example, 1000 kW) for a rated time (for example, 10 seconds) when a power failure occurs after a predetermined time from the start of use. Ru. The predetermined time is an expected life of the uninterruptible power supply (mainly a capacitor), and is set, for example, to 15 years.

However, the characteristics (capacitance value, internal resistance value, etc.) of a capacitor deteriorate depending on its use conditions (temperature, voltage between terminals, etc.) and its use time. For example, the capacitance value of the capacitor gradually decreases with use time.

Therefore, in the conventional uninterruptible power supply, the load of rated capacity (for example, 1000 kW) is rated for time (for example, 10 seconds) in consideration of a decrease in capacitance value of the capacitor accompanying use for a predetermined time (for example, 15 years). A capacitor with a capacitance value (e.g., 1.5 C) sufficiently larger than the capacitance value C required for operation was used. For this reason, there existed a problem that a capacitor enlarged.

Therefore, a main object of the present invention is to provide a power supply device capable of miniaturizing a capacitor.

A power supply device according to the present invention includes a power converter, a storage unit, a first detection unit, and an operation unit. In the first case where the AC voltage of the commercial AC power supply is normal, the power converter converts AC power from the commercial AC power supply into DC power and stores the DC power, and the AC voltage of the commercial AC power supply is not normal. In this case, the load is driven for a predetermined time based on the DC power of the capacitor. The storage unit stores deterioration information indicating the relationship between the characteristics of the capacitor, the use condition thereof, and the use time thereof. The first detection unit detects a use condition and a use time of the capacitor. The calculation unit obtains the characteristic of the capacitor at the present time based on the deterioration information and the detection result of the first detection unit. The calculation unit further obtains a target value of the voltage between the terminals of the capacitor, which is necessary to drive the load for a predetermined time, based on the characteristics of the capacitor and the load capacitance at the present time. In the first case, the power converter charges the capacitor such that the terminal voltage of the capacitor becomes a target value.

In the power supply device according to the present invention, the characteristics of the capacitor at the present time are obtained based on the deterioration information indicating the relationship between the characteristics of the capacitor, the usage conditions thereof, and the usage hours thereof and the usage conditions of the capacitors and the detection values of the usage hours. Based on the characteristics and the load capacitance, a target value of the terminal voltage of the capacitor necessary to drive the load for a predetermined time is determined. In the first case, the power supply device charges the capacitor so that the voltage across the capacitor becomes the target value. Therefore, compared with the case where the voltage between the terminals of the capacitor is maintained at a constant value, the voltage between the terminals of the capacitor can be lowered, the deterioration of the capacitor can be suppressed, and the capacitor can be miniaturized.

FIG. 1 is a circuit block diagram showing a configuration of an uninterruptible power supply according to Embodiment 1 of the present invention. It is a block diagram which shows the principal part of the control apparatus shown in FIG. It is a figure which shows the equivalent circuit of the capacitor | condenser shown in FIG. It is a figure which shows a time-dependent change of the characteristic of the capacitor | condenser shown in FIG. It is a figure which shows the equivalent circuit of the uninterruptible power supply at the time of a power failure generation. It is a time chart which shows operation | movement of the uninterruptible power supply shown in FIG. It is a figure for demonstrating an example of how to obtain | require the target value of the voltage between terminals of a capacitor. It is a circuit block diagram which shows the structure of the uninterruptible power supply by Embodiment 2 of this invention. It is a block diagram which shows the principal part of the control apparatus shown in FIG.

First Embodiment
FIG. 1 is a circuit block diagram showing a configuration of an uninterruptible power supply according to Embodiment 1 of the present invention. In FIG. 1, the uninterruptible power supply includes an input terminal 1, an output terminal 2 and a direct current terminal 3. Input terminal 1 receives AC power of a commercial frequency from commercial AC power supply 21. The instantaneous value of the AC voltage VI appearing at the input terminal 1 is detected by the controller 9.

The output terminal 2 is connected to a load 22. The instantaneous value of the AC voltage VO appearing at the output terminal 2 is detected by the controller 9. The load 22 is driven by AC power of commercial frequency supplied from the uninterruptible power supply.

Although the uninterruptible power supply actually receives three-phase AC power from the commercial AC power supply 21 and supplies the three-phase AC power to the load 22, for simplification of the drawings and description, in FIG. Only relevant parts are shown.

The DC terminal 3 is connected to the capacitor 23. The instantaneous value of the DC voltage VDC appearing at the DC terminal 3 is detected by the controller 9. The capacitor 23 stores DC power. As the capacitor 23, for example, an electrolytic capacitor, an electric double layer capacitor, a film capacitor or the like is used.

The uninterruptible power supply further includes a switch 4, an AC line 5, a current detector 6, a temperature detector 7, an AC / DC converter 8, and a controller 9. One terminal of the switch 4 is connected to the input terminal 1, and the other terminal is connected to the output terminal 2 via the AC line 5. The switch 4 is controlled by the controller 9.

When the AC voltage VI from the commercial AC power supply 21 is normal (that is, when the commercial AC power supply 21 is healthy), the switch 4 is turned on. When the AC voltage VI from the commercial AC power supply 21 is not normal (for example, when a power failure of the commercial AC power supply 21 occurs), the switch 4 is turned off.

The current detector 6 detects an instantaneous value of the load current IL flowing through the AC line 5, and provides the control device 9 with a signal ILf indicating the detected value. The temperature detector 7 detects the temperature Tc of the capacitor 23 directly or indirectly, and provides the controller 9 with a signal DT indicating the detected value.

The AC side terminal 8 a of the AC / DC converter 8 is connected to the other terminal of the switch 4, and the DC side terminal 8 b is connected to the DC terminal 3. The AC / DC converter 8 is controlled by a controller 9.

When the AC voltage VI from the commercial AC power supply 21 is normal, the AC / DC converter 8 converts AC power supplied from the commercial AC power supply 21 via the switch 4 into DC power and outputs the DC power to the capacitor 23. store. At that time, the AC / DC converter 23 charges the capacitor 3 so that the voltage VDC across the terminals of the capacitor 23 becomes the target value VDCT.

When the AC voltage VI from the commercial AC power supply 21 is not normal, the AC / DC converter 8 converts the DC power of the capacitor 3 into AC power of a commercial frequency and applies the same to the load 22. At that time, the AC / DC converter 8 maintains the AC output voltage VO at the rated value VOC.

The controller 9 controls the switch 4 and the AC / DC converter 8 based on the AC input voltage VI, the AC output voltage VO, the load current IL, the voltage VDC between the terminals of the capacitor 23, and the temperature Tc of the capacitor 23.

That is, based on the instantaneous value of AC voltage VI appearing at input terminal 1, control device 9 determines whether AC voltage VI is within the normal range. For example, when a power failure of the commercial AC power supply 21 occurs, the level of the AC voltage VI falls below the lower limit value VIL. When the level of AC voltage VI is lower than lower limit value VIL, control device 9 determines that AC voltage VI is not normal.

When the AC input voltage VI is normal, the controller 9 turns on the switch 4 and controls the AC / DC converter 8 to charge the capacitor 23. At this time, the controller 9 controls the AC / DC converter 8 so that the voltage VDC across the terminals of the capacitor 23 becomes the target value V.sub.DCT.

If the AC input voltage VI is not normal, the control device 9 turns off the switch 4 and controls the AC / DC converter 8 to convert DC power of the capacitor 23 into AC power of commercial frequency, AC power is supplied from the DC converter 8 to the load 22. At that time, the controller 9 controls the AC / DC converter 8 so that the AC output voltage VO becomes the rated voltage VOC.

Further, the control device 9 determines the characteristics (electrostatic capacitance C, internal resistance value R) of the capacitor 23 at the present time based on the use condition (temperature Tc, voltage between terminals VDC) of the capacitor 23 and the use time TU. Based on the AC output voltage VO and the load current IL, the load capacity P at the present time is determined. Then, the control device 9 obtains a target value VDCT of the voltage VDC between the terminals of the capacitor 23 based on the characteristics of the capacitor 23 at the current point in time, the load capacitance P, and the rated time Tr.

FIG. 2 is a block diagram showing a portion of control device 9 related to control of AC / DC converter 8. In FIG. 2, the control device 9 includes a storage unit 11, an operation unit 12, a control unit 13, and a clock unit 14. In the storage unit 11, the relationship between the characteristics (capacitance value C, internal resistance value R) of the capacitor 23, the use conditions (temperature Tc, voltage between terminals VDC) of the capacitor 23, and the use time TU of the capacitor 23 Deterioration information to indicate is stored.

FIG. 3 is a diagram showing an equivalent circuit of the capacitor 23. In FIG. 3, the capacitor 23 includes a resistive element 23a and a capacitive element 23b connected in series. The resistive element 23 a has an internal resistance value R, and the capacitive element 23 b has a capacitance value C.

FIGS. 4A and 4B show time-dependent changes of the characteristics of the capacitor 23. FIG. In particular, FIG. 4A shows the change with time of the capacitance value C of the capacitor 23, and FIG. 4B shows the change with time of the internal resistance value R of the capacitor 23.

In FIGS. 4A and 4B, the characteristics of the capacitor 23 gradually deteriorate with the passage of the operating time TU (h). That is, the capacitance value C gradually decreases with the elapse of the operating time TU of the capacitor 23, and the internal resistance value R of the capacitor 23 gradually increases with the elapse of the operating time TU (h) of the capacitor 23.

Furthermore, the degree of deterioration of the characteristics of the capacitor 23 changes in accordance with the temperature Tc of the capacitor 23 and the voltage VDC across the terminals. That is, as the temperature Tc of the capacitor 23 is higher, the capacitance value C decreases faster, and the internal resistance value R increases faster. Further, the higher the inter-terminal voltage VDC of the capacitor 23, the faster the capacitance value C decreases and the faster the internal resistance value R increases.

In the storage unit 11, characteristics (capacitance value C, internal resistance value R) of the capacitor 23 as shown in FIGS. 4A and 4B, and use conditions of the capacitor 23 (temperature Tc, voltage between terminals) Deterioration information indicating the relationship between VDC) and the usage time TU of the capacitor 23 is stored in the form of a table or a formula. Such degradation information may be obtained from the manufacturer of the capacitor 23 or may be obtained by experiment.

Therefore, if the temperature Tc of the capacitor 23, the voltage VDC between the terminals, and the operating time TU are detected, the capacitance of the capacitor 23 at the present time is obtained based on the detected values and the deterioration information stored in the storage unit 11. The value C and the internal resistance value R can be determined.

Returning to FIG. 2, the operation unit 12 receives the temperature Tc of the capacitor 23 indicated by the output signal DT of the temperature detector 7 (FIG. 1), the voltage VDC across the terminals of the capacitor 23, and the output signal CT of the timing unit 14. Based on the shown use time TU of the capacitor 23 and the deterioration information stored in the storage unit 11, the capacitance value C and the internal resistance value R of the capacitor 23 at the present time are obtained.

Further, the operation unit 12 obtains the load capacitance P based on the AC output voltage VO and the load current IL indicated by the output signal ILf of the current detector 6. Further, operation unit 12 determines target value VDCT of voltage VDC across terminals of capacitor 23 based on load capacitance P, rated time Tr, and electrostatic capacitance value C and internal resistance value R of capacitor 23 at the present time. .

Next, a method of obtaining the target value VDCT will be described. FIG. 5 is a diagram showing an equivalent circuit of the uninterruptible power supply when the power failure of the commercial AC power supply 21 occurs. In FIG. 5, in this equivalent circuit, the switch 25 and the DC load 26 are connected in series between the terminals of the capacitor 23. The switch 25 and the DC load 26 correspond to the AC / DC converter 8 and the load 22. Capacitor 23 includes a resistive element 23a and a capacitive element 23b connected in series. The DC load 26 consumes a constant power P.

When a power failure of the commercial AC power supply 21 occurs, the switch 25 is turned on, and a direct current i (t) flows from the capacitor 23 to the direct current load 26 via the switch 25. This operation corresponds to an operation in which the AC / DC converter 8 converts DC power of the capacitor 23 into AC power and supplies the AC power to the load 22 when a power failure of the commercial AC power supply 21 occurs.

6A, 6B and 6C show the voltage VDC (t) between the terminals of the capacitor 23, the direct current i (t), and the power consumption P (t) = VDC (t) × i (t), respectively. It is a time chart which shows.

In FIGS. 6A, 6B and 6C, when the AC voltage VI of the commercial AC power supply 21 is normal (time t0), the switch 25 is turned off and the voltage VDC (t) between the terminals of the capacitor 23 is a DC voltage. It is set to V1. In other words, the inter-terminal voltage VDC (t) of the capacitor 23 is adjusted by the AC / DC converter 8 to the target value VDCT = V1.

When a power failure of the commercial AC power supply 21 occurs at a certain time t1, the switch 25 is turned on. In other words, the switch 4 (FIG. 1) is turned off, and the DC power of the capacitor 23 is converted into AC power by the AC / DC converter 8 and supplied to the load 22.

When the switch 25 is turned on, a direct current i (t) flows from the capacitive element 23 b to the direct current load 26 through the resistor 23 a and the switch 25, and a constant power P is consumed in the direct current load 26. Assuming that the direct current i (t1) at time t1 is i1, a voltage drop (R × i1) occurs in the resistive element 23a, and the voltage VDC (t1) between terminals of the capacitor 23 becomes V1-R × i1.

When a direct current i (t) flows from the capacitor 23 to the DC load 26, the voltage VDC (t) between the terminals of the capacitor 23 gradually decreases. Also, since P = VDC (t) × i (t) is constant, the direct current i (t) gradually increases. When a rated time Tr has elapsed from time t1 at which the commercial AC power supply 21 fails, the inter-terminal voltage VDC (t) of the capacitor 23 decreases to V2, and the direct current i (t) increases to i2. . At this time, the voltage drop in the resistive element 23a is R × i2.

At time t2, since the rated time Tr has elapsed, the switch 25 is turned off. When the switch 25 is turned off, the direct current i (t) becomes zero and the power P (t) also becomes zero. When the direct current i (t) becomes 0, the voltage drop across the resistive element 23a becomes 0, and the voltage VDC across the terminals of the capacitor 23 rises from V2 by the voltage drop (R × i2).

Here, in order to continue the operation of the load 22 for only the rated time Tr from the time t1 at which the commercial AC power supply 21 fails, the voltage VDC = V2 across the terminals of the capacitor 23 immediately before the time t2 is AC / DC conversion. It is necessary to be more than the lower limit value VDCL of the voltage VDC between the terminals of the capacitor 23 necessary to drive the converter 8 and the load 22.

In other words, if the inter-terminal voltage VDC of the capacitor 23 at the present time is adjusted so that the inter-terminal voltage VDC of the capacitor 23 becomes the lower limit value VDCL after discharging the DC power P for the rated time Tr, a power failure occurs. Also, it is possible to continue the operation of the load 22 for the rated time Tr. The following equations (1) and (2) hold in a period (time t1 to t2) in which the switch 25 (FIG. 5) is on. However, t1 = 0.

Substituting equation (1) into equation (2), the following equation (3) is obtained.

Using equation (3), the voltage VDC (0) = V1 of the terminals of capacitor 23 is set so that the voltage VDC (Tr) of terminals of capacitor 23 becomes lower limit value VDCL after rated time Tr elapses from the occurrence of a power failure. Ask.

Specifically, the programming process is executed to calculate VDC (t) one sample at a time. For example, when processing at 1 kHz is performed, VDC (t) when t = 1 ms, VDC (t) when t = 2 ms, VDC (t) when t = 3 ms, ... Then, calculate VDC (t) when t = Tr. V1 is determined so that VDC (t) when t = Tr is the lower limit value VDCL, and V1 is set as the target value V DCT.

For example, when VDCL = 500 V, V1 = 530 V, P = 1000 kW, R = 0.01 Ω, Tr = 10 s, VDC (0) at t = t1 (that is, immediately after discharge) is 511.1 V. In this case, VDC (t) = 509.2 V at time t (0.1 s) when 0.1 s has elapsed from time t1, and at time t (0.2 s) when 0.2 s has elapsed from time t1, VDC (t) ) = 507.2V. This calculation is repeated until time t (10 s) at which rated time Tr elapses from time t1. V1 is determined when the condition that VDC (t) at time t (10 s) is equal to or higher than the lower limit VDCL (= 500 V) is obtained, and the minimum value of V1 is determined as the target value VDCT.

Instead of performing the programming process, the equation (3) which is an integral equation may be solved to obtain VDC (t), V1 may be obtained based on the VDC (t), and V1 may be set as the target value V DCT.

Alternatively, as shown in FIG. 7, VDC (t) is obtained using a waveform L1 obtained by linearly approximating the waveform of the linear current i (t) shown in FIG. 6 (B), and V1 is determined based on the VDC (t). It is also possible to obtain V1 as the target value VDCT. In this case, the amount of charge Q discharged by the capacitor 23 when the DC power P is discharged from the time t1 for the rated time Tr can be approximated by the following equation (4).

Here, since the direct current i1 = P / V1 at time t1 and the direct current i2 = P / V2 at time t2, assuming that a drop in the voltage VDC across the capacitor 23 due to the discharge of the charge amount Q is ΔVDC, ΔVDC is given by the following equation (5). Therefore, the voltage VDC = V2 between the terminals of the capacitor 23 immediately before time t2 is given by the following equation (6). By using this equation (6), it is possible to obtain the target value VDCT = V1 for V2 to be equal to or greater than VDCL.

Returning to FIG. 2, the control unit 13 determines whether the AC voltage VI is within the normal range based on the instantaneous value of the AC voltage VI appearing at the input terminal 1 (FIG. 1). For example, when a power failure of the commercial AC power supply 21 occurs, the level of the AC voltage VI falls below the lower limit value VIL. When the level of AC voltage VI is lower than lower limit value VIL, control unit 13 determines that AC voltage VI is not normal.

When the AC input voltage VI is normal, the control unit 13 controls the AC / DC converter 8 to charge the capacitor 23. At this time, the control unit 13 controls the AC / DC converter 8 so that the voltage VDC across the terminals of the capacitor 23 becomes the target value V.sub.DCT. Further, the control unit 13 supplies the clock signal CLK to the clocking unit 14 during a period in which the charge is stored in the capacitor 23.

When the AC input voltage VI is not normal, the control unit 13 controls the AC / DC converter 8 to convert DC power of the capacitor 23 into AC power of commercial frequency, and the AC / DC converter 8 converts the AC power into a load 22. Supply AC power. At this time, the control unit 13 controls the AC / DC converter 8 such that the AC output voltage VO becomes equal to the rated voltage VOC.

The clocking unit 14 obtains the use time TU of the capacitor 23 based on the clock signal CLK from the control unit 13, and provides the signal CT indicating the use time TU to the calculation unit 12.

Next, the operation of this uninterruptible power supply will be described. When the AC voltage VI from the commercial AC power supply 21 is normal, the switch 4 (FIG. 1) is turned on, AC power is supplied from the commercial AC power supply 21 to the load 22 via the switch 4, and the load 22 is driven. Ru.

Further, AC power is supplied from the commercial AC power supply 21 to the AC / DC converter 8 through the switch 4. The AC / DC converter 8 converts AC power from the commercial AC power supply 21 into DC power and stores the DC power in the capacitor 23.

The temperature detector 7 detects the temperature Tc of the capacitor 23, and the timer unit 14 detects the operating time TU of the capacitor 23. Based on the temperature Tc of the capacitor 23, the voltage VDC between the terminals of the capacitor 23, the usage time TU of the capacitor 23, and the deterioration information stored in the storage unit 11, the control device 9 The capacitance value C and the internal resistance value R are determined.

Further, control device 9 determines load capacitance P based on AC output voltage VO and load current IL, and the voltage VDC across terminals of capacitor 23 necessary for driving load 22 of the load capacitance P for the rated time Tr That is, the target value VDCT) is determined. The AC / DC converter 8 charges the capacitor 23 such that the terminal voltage VDC of the capacitor 23 becomes the target value V DCT.

When AC voltage VI of commercial AC power supply 21 is not normal (for example, when a power failure occurs), switch 4 is turned off, and DC power of capacitor 23 is converted to AC power of commercial frequency by AC / DC converter 8. It is converted and supplied to the load 22. The supply of AC power from the AC / DC converter 8 to the load 22 is continued for the rated time Tr. Therefore, even if a power failure occurs, the operation of the load 22 is continued for the rated time Tr.

When the commercial AC power supply 21 returns to normal during the time from the occurrence of the power failure until the rated time Tr elapses, the switch 4 is turned on, and AC power is supplied from the commercial AC power supply 21 to the load 22 via the switch 4 Be done. Further, the capacitor 23 is charged by the AC / DC converter 8 so that the terminal voltage VDC of the capacitor 23 becomes the target value VTCT.

As described above, in the first embodiment, the characteristic of the capacitor 23 at the present time is obtained based on the deterioration information of the capacitor 23 stored in the storage unit 11, the use condition of the capacitor 23, and the use time TU. Then, based on the determined characteristics of the capacitor 23 and the load capacitance P, a target value V DCT required to drive the load 22 for the rated time Tr is determined, and the inter-terminal voltage VDC of the capacitor 23 becomes the target value V DCT To charge the capacitor 23. Therefore, as compared with the case where the voltage VDC across the terminals of the capacitor 23 is maintained at a constant value, the voltage VDC across the terminals of the capacitor 23 can be lowered, and deterioration of the capacitor 23 can be suppressed. Can be

When the capacity P of the load 22 is a constant value and is known in advance, it is not necessary to obtain the capacity P based on the AC output voltage VO and the load current IL. Therefore, in this case, the current detector 6 is unnecessary.

Second Embodiment
8 is a circuit block diagram showing a configuration of an uninterruptible power supply according to a second embodiment of the present invention. In FIG. 7, the uninterruptible power supply includes an input terminal 31, an output terminal 32, and a direct current terminal 33.

Input terminal 31 receives AC power of a commercial frequency from commercial AC power supply 21. The instantaneous value of the AC voltage VI appearing at the input terminal 31 is detected by the controller 37. Although the uninterruptible power supply receives three-phase AC power from the commercial AC power supply 21 in practice, only a portion related to one phase is shown in FIG. 7 for the sake of simplification of the drawings and the description.

The output terminal 32 is connected to the DC load 40. The instantaneous value of the DC voltage VO appearing at the output terminal 32 is detected by the controller 37. The DC load 40 is driven by DC power supplied from the uninterruptible power supply.

The direct current terminal 33 is connected to the capacitor 23. The instantaneous value of DC voltage VDC appearing at DC terminal 33 is detected by controller 37. The capacitor 23 stores DC power. As the capacitor 23, for example, an electrolytic capacitor, an electric double layer capacitor, a film capacitor or the like is used.

The uninterruptible power supply further includes an AC / DC converter 34, a DC line 35, a current detector 6, a temperature detector 7, a DC / DC converter 36, and a controller 37. The AC side terminal 34 a of the AC / DC converter 34 is connected to the input terminal 31, and the DC side terminal 34 b is connected to the output terminal 32 via the DC line 35. The AC / DC converter 34 is controlled by the controller 37.

When the AC voltage VI from the commercial AC power supply 21 is normal (that is, when the commercial AC power supply 21 is healthy), the AC / DC converter 34 converts the AC power from the commercial AC power supply 21 into DC power. Convert to load 40. When the AC voltage VI from the commercial AC power supply 21 is not normal (for example, when a power failure of the commercial AC power supply 21 occurs), the operation of the AC / DC converter 34 is stopped.

The current detector 6 detects an instantaneous value of the load current IL flowing through the DC line 35, and provides the controller 9 with a signal ILf indicating the detected value. The temperature detector 7 detects the temperature Tc of the capacitor 23 directly or indirectly, and provides the controller 37 with a signal DT indicating the detected value.

One terminal 36 a of the DC / DC converter 36 is connected to the DC side terminal 34 b of the AC / DC converter 34, and the other terminal 36 b is connected to the DC terminal 33. The DC / DC converter 36 is controlled by the controller 37.

When the AC voltage VI from the commercial AC power supply 21 is normal, the DC / DC converter 36 stores DC power supplied from the commercial AC power supply 21 via the AC / DC converter 34 in the capacitor 23. At this time, the DC / DC converter 36 charges the capacitor 3 so that the voltage VDC across the terminals of the capacitor 23 becomes the target value VDCT.

If the AC voltage VI from the commercial AC power supply 21 is not normal, the DC / DC converter 36 applies DC power of the capacitor 3 to the DC load 40. At this time, the DC / DC converter 36 maintains the DC output voltage VO at the rated value VOC.

Controller 37 controls AC / DC converter 34 and DC / DC converter 36 based on AC input voltage VI, DC output voltage VO, load current IL, terminal voltage VDC of capacitor 23, and temperature Tc of capacitor 23. Control.

That is, based on the instantaneous value of AC voltage VI appearing at input terminal 31, control device 37 determines whether AC voltage VI is within the normal range. For example, when a power failure of the commercial AC power supply 21 occurs, the level of the AC voltage VI falls below the lower limit value VIL. When the level of AC voltage VI is lower than lower limit value VIL, control device 37 determines that AC voltage VI is not normal.

When the AC input voltage VI is normal, the control device 37 controls the AC / DC converter 34 to convert AC power from the commercial AC power supply 21 into DC power to be supplied to the DC load 40, The DC / DC converter 36 is controlled to store DC power from the AC / DC converter 34 in the capacitor 23.

At that time, the control device 37 controls the AC / DC converter 8 so that the DC output voltage VO becomes the rated value VOT, and the DC / DC converter so that the voltage VDC between the terminals of the capacitor 23 becomes the target value VDCT. Control 36

When the AC input voltage VI is not normal, the controller 37 stops the operation of the AC / DC converter 34 and controls the DC / DC converter 36 to supply DC power of the capacitor 23 to the DC load 40. Let At that time, the controller 37 controls the DC / DC converter 36 such that the DC output voltage VO becomes the rated value VOT.

Further, the control device 37 determines the characteristics (electrostatic capacitance value C, internal resistance value R) of the capacitor 23 at the present time based on the use condition (temperature Tc, voltage between terminals VDC) of the capacitor 23 and the use time TU. Based on the DC output voltage VO and the load current IL, the load capacity P at the present time is determined. Then, the control device 37 obtains a target value VDCT of the voltage VDC between the terminals of the capacitor 23 based on the characteristics of the capacitor 23 at the current point in time, the load capacitance P, and the rated time Tr.

FIG. 9 is a block diagram showing a portion of control device 37 related to control of DC / DC converter 36. Referring to FIG. In FIG. 9, the control device 37 includes a storage unit 11, an operation unit 41, a control unit 42, and a clock unit 14. As described in the first embodiment, the storage unit 11 has the characteristics (capacitance value C, internal resistance value R) of the capacitor 23, use conditions (temperature Tc, voltage between terminals VDC) of the capacitor 23, and the capacitor Deterioration information indicating the relationship with the usage time TU of 23 is stored. The equivalent circuit of the capacitor 23 is as described in FIG. The change with time of the characteristics of the capacitor 23 is as described in FIGS. 4 (A) and 4 (B).

The calculation unit 41 uses the temperature Tc of the capacitor 23 indicated by the output signal DT of the temperature detector 7 (FIG. 7), the voltage VDC between the terminals of the capacitor 23, and the use of the capacitor 23 indicated by the output signal CT of the timing unit 14 Based on the time TU and the deterioration information stored in the storage unit 11, the capacitance value C and the internal resistance value R of the capacitor 23 at the present time are obtained.

Further, the arithmetic unit 41 obtains the load capacitance P based on the DC output voltage VO and the load current IL indicated by the output signal ILf of the current detector 6. Further, the calculation unit 41 obtains a target value V DCT of the inter-terminal voltage VDC of the capacitor 23 necessary to drive the DC load 40 (FIG. 8) of the load capacity P for the rated time Tr.

The method of obtaining the target value V.sub.DCT is as described in FIG. 5 and FIGS. 6 (A), (B) and (C). However, the switch 25 and the DC load 26 in FIG. 5 correspond to the DC / DC converter 36 and the DC load 40.

Control unit 42 determines whether or not AC voltage VI is within the normal range based on the instantaneous value of AC voltage VI appearing at input terminal 31 (FIG. 8). For example, when a power failure of the commercial AC power supply 21 occurs, the level of the AC voltage VI falls below the lower limit value VIL. When the level of AC voltage VI is lower than lower limit value VIL, control unit 42 determines that AC voltage VI is not normal.

When the AC input voltage VI is normal, the control unit 42 controls the DC / DC converter 36 to charge the capacitor 23. At this time, the control unit 42 controls the DC / DC converter 36 such that the voltage VDC across the terminals of the capacitor 23 becomes the target value V.sub.DCT. The control unit 42 also supplies the clock signal CLK to the clock unit 14 during a period in which the charge is stored in the capacitor 23.

When the AC input voltage VI is not normal, the control unit 42 controls the DC / DC converter 36 to convert DC power of the capacitor 23 into AC power of commercial frequency, and the DC load from the DC / DC converter 36 Supply 40 AC power. At this time, the control unit 42 controls the DC / DC converter 36 such that the DC output voltage VO becomes equal to the rated voltage VOC.

The clock unit 14 obtains the use time TU of the capacitor 23 based on the clock signal CLK from the control unit 42, and gives the signal CT indicating the use time TU to the calculation unit 41.

Next, the operation of this uninterruptible power supply will be described. When the AC voltage VI from the commercial AC power supply 21 is normal, the AC / DC converter 34 is operated, AC power from the commercial AC power supply 21 is converted to DC power, and is supplied to the DC load 40, DC load 40 are driven. Also, DC power generated by the AC / DC converter 34 is supplied to the DC / DC converter 36. The DC / DC converter 36 stores DC power from the AC / DC converter 34 in the capacitor 23.

The temperature detector 7 detects the temperature Tc of the capacitor 23, and the timer unit 14 detects the operating time TU of the capacitor 23. Based on temperature Tc of capacitor 23, voltage VDC across terminals of capacitor 23, usage time TU of capacitor 23, and deterioration information stored in storage unit 11, controller 37 determines the static condition of capacitor 23 at the present time. The capacitance value C and the internal resistance value R are determined.

Further, control device 37 determines load capacitance P based on AC output voltage VO and load current IL, and the voltage VDC across terminals of capacitor 23 necessary to drive DC load 40 of load capacitance P for the rated time Tr. (Ie, a target value VDCT) is determined. The DC / DC converter 36 charges the capacitor 23 such that the terminal voltage VDC of the capacitor 23 becomes the target value VDCT.

When the AC voltage VI of the commercial AC power supply 21 is not normal (for example, when a power failure occurs), the operation of the AC / DC converter 34 is stopped, and the DC power of the capacitor 23 is reduced by the DC / DC converter 36. The DC load 40 is supplied. The supply of DC power from the DC / DC converter 36 to the DC load 40 is continued for the rated time Tr. Therefore, even when a power failure occurs, the operation of the DC load 40 is continued for the rated time Tr.

If the commercial AC power supply 21 becomes normal before the rated time Tr passes from the occurrence of the power failure, the operation of the AC / DC converter 34 is resumed, and the AC power from the commercial AC power supply 21 is DC power. And is supplied to the DC load 40 and the DC / DC converter 36. Further, the capacitor 23 is charged by the DC / DC converter 36 such that the terminal voltage VDC of the capacitor 23 becomes the target value V DCT.

Also in the second embodiment, the same effect as the first embodiment can be obtained.
When the capacity P of the DC load 40 is a fixed value and is known in advance, it is not necessary to obtain the capacity P based on the DC output voltage VO and the load current IL. Therefore, in this case, the current detector 6 is unnecessary.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The present invention is shown not by the above description but by the claims, and is intended to include all modifications within the scope and meaning equivalent to the claims.

1, 31 input terminals, 2, 32 output terminals, 3, 33 DC terminals, 4, 25 switches, 5 AC lines, 6 current detectors, 7 temperature detectors, 8, 34 AC / DC converters, 9, 37 controls Device, 11 storage unit, 12, 41 operation unit, 13, 42 control unit, 14 clock unit, 21 commercial AC power source, 22 load, 23 capacitor, 23a resistance element, 23b capacity element, 26, 40 DC load, 36 DC / DC converter.

Claims

In the first case where the AC voltage of the commercial AC power supply is normal, AC power from the commercial AC power supply is converted to DC power and stored in a capacitor, and in the second case where the AC voltage of the commercial AC power supply is not normal A power converter for driving a load for a predetermined time based on DC power of the capacitor;
A storage unit in which deterioration information indicating the relationship between the characteristics of the capacitor, the use condition thereof, and the use time thereof is stored;
A first detection unit that detects a use condition and a use time of the capacitor;
The characteristic of the capacitor at the present time is determined based on the deterioration information and the detection result of the first detection unit, and only the predetermined time is determined based on the characteristic of the capacitor at the current time and the load capacity. And a calculation unit for obtaining a target value of the voltage between the terminals of the capacitor, which is necessary to drive the load.
In the first case, the power converter charges the capacitor such that a voltage across terminals of the capacitor becomes the target value.
The power supply device according to claim 1, wherein the characteristics of the capacitor include a capacitance value and an internal resistance value of the capacitor.
The power supply device according to claim 1, wherein a use condition of the capacitor includes a temperature of the capacitor and a voltage between terminals.
Furthermore, a second detection unit for detecting a load capacity is provided,
The power supply according to any one of claims 1 to 3, wherein the calculation unit obtains the target value based on a characteristic of the capacitor at a current time point and a load capacitance detected by the second detection unit. apparatus.
The load is driven by AC power,
The power converter
A switch in which one terminal receives alternating current power from the commercial alternating current power supply, the other terminal is connected to the load, the first case is conductive, and the second case is nonconductive;
It is provided between the other terminal of the switch and the capacitor, and in the first case, AC power supplied from the commercial AC power supply through the switch is converted into DC power and stored in the capacitor; The second case includes an AC / DC converter which converts DC power of the capacitor into AC power and supplies the AC power to the load.
The power supply according to any one of claims 1 to 4, wherein the AC / DC converter charges the capacitor such that a voltage across terminals of the capacitor becomes the target value in the first case. apparatus.
The load is driven by DC power,
The power converter
One terminal receives AC power from the commercial AC power supply, the other terminal is connected to the load, and in the first case, AC power from the commercial AC power supply is converted to DC power and supplied to the load; In the second case, an AC / DC converter whose operation is stopped;
The capacitor is provided between the other terminal of the AC / DC converter and the capacitor, and in the first case, DC power generated by the AC / DC converter is stored in the capacitor; A DC / DC converter for supplying DC power of the capacitor to the load;
The power supply according to any one of claims 1 to 4, wherein the DC / DC converter charges the capacitor such that a voltage across terminals of the capacitor becomes the target value in the first case. apparatus.