Power supply system and power storage device

Abstract

A microcomputer of this power supply system controls a switch unit so as to start an on-operation for supplying DC power from a sub-power supply device to a load when the DC power supplied from a main power supply device reduces and a voltage input to the load becomes less than a predetermined threshold value. When the DC power supplied from the main power supply device is restored, the microcomputer starts an off-operation for limiting the DC power supplied from the sub-power supply device to the load, limits the supply of the DC power from the sub-power supply device to the load so that the voltage input to the load does not become less than the predetermined threshold value from the start of the off-operation until a predetermined time has elapsed, and controls the switch unit so that the supply of the DC power from the sub-power supply device to the load becomes zero after the predetermined time has elapsed.

Description

[Technical Field]

[0001] The present invention relates to a power supply system and a power storage device. [Background technology]

[0002] Generally, a power supply system that supplies power to a load, such as that disclosed in Patent Document 1 below, is known. Such a power supply system includes a main power supply line that supplies power to the load and a secondary power supply line that functions as a backup for the main power supply line. The main power supply line converts power input from an external power source into power that can be supplied to the load and supplies the power to the load. Furthermore, when the power supply from the main power supply line to the load decreases (for example, when a power outage occurs in the main power supply line), the secondary power supply line discharges a battery built into the secondary power supply line and supplies power to the load in place of the main power supply line.

[0003] In the above power supply system, when a power outage occurs in the main power supply line, the power supply to the load from the secondary power supply line is stopped and then power is supplied to the load from the main power supply line again (i.e., when a power restoration operation is performed to switch from the secondary power supply line to the main power supply line), the voltage of the power supply line drops sharply. As a result, in the power supply system, the voltage input to the load falls below a predetermined threshold, and the power supply to the load from the secondary power supply line starts again, which is a problem.

[0004] One of the causes of the sudden drop in voltage in the power supply path is the sudden stop of the power supply from the secondary power supply path to the load during the power restoration operation. In the power supply system, the sudden stop of the power supply from the secondary power supply path to the load causes a sudden voltage drop in the power supply path of the power supply system, i.e., a sudden drop in the voltage input to the load. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-251771 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of these circumstances, and its purpose is to provide a power supply system and a power storage device for use in the power supply system that can achieve smooth power recovery operation by taking measures to prevent a sudden voltage drop from occurring in the power supply path of the power supply system. [Means for solving the problem]

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0008] The power supply system according to this aspect includes a main power supply unit that supplies DC power to a load, a secondary power supply unit that is connected in parallel with the main power supply unit and that supplies DC power to the load by discharging a built-in battery, a switch unit that is provided in an electrical path from the secondary power supply unit to the load through which a discharge current of the battery flows and that performs an on-operation and an off-operation, and a microcomputer that controls the on-operation and the off-operation of the switch unit, and when the DC power supplied from the main power supply unit decreases and the voltage input to the load becomes less than a predetermined threshold, the microcomputer switches the secondary power supply unit to the on-operation and the off-operation. and a microcomputer configured to control the secondary power supply device so that the secondary power supply device starts an ON operation to supply the DC power to the load when the DC power supplied from the main power supply device is restored, and starts an OFF operation to limit the DC power supplied from the secondary power supply device to the load when the DC power supplied from the main power supply device is restored, and limits the supply of DC power from the secondary power supply device to the load so that a voltage input to the load does not become less than a predetermined threshold until a predetermined time has elapsed from the start of the OFF operation, and controls the switch unit so that the supply of DC power from the secondary power supply device to the load becomes zero after the predetermined time has elapsed. [Effects of the Invention]

[0009] The power supply system according to this aspect and the power storage device used in the power supply system can achieve a smooth power restoration operation. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a power supply system according to a first embodiment. [Figure 2] 2 is a schematic diagram showing a duty ratio used in the power supply system shown in FIG. 1. FIG. [Figure 3] FIG. 10 is a block diagram showing a power supply system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] A power supply system and a power storage device according to one embodiment will be described below with reference to the drawings. Note that this embodiment is not limited to the content described below, and can be implemented with any modifications within the scope of the gist. Furthermore, the drawings used to describe the embodiment all show components in a schematic manner, and may be partially emphasized, enlarged, reduced, or omitted to facilitate understanding, and may not accurately represent the scale, shape, etc. of the components.

[0012] (First embodiment) Fig. 1 is a block diagram showing a power supply system 1 according to a first embodiment. The overall function of the power supply system 1 shown in Fig. 1 is to convert power supplied from an external power supply PS into DC power that can be supplied to a load 2, and supply the DC power to the load 2. Furthermore, when the power supply from the external power supply PS to the load 2 decreases (for example, when the power supply from the external power supply PS to the load 2 is stopped due to a power outage or other cause), the power supply system 1 discharges an internal battery and supplies the DC power stored in the battery to the load 2.

[0013] 1, the power supply system 1 according to this embodiment includes a main power supply device 3 and a power storage device 4. The main power supply device 3 in this embodiment is connected to the load 2 via an electrical path L1. The main power supply device 3 converts power supplied from an external power supply PS into DC power that can be supplied to the load 2, and supplies the DC power to the load 2.

[0014] In this embodiment, the power storage device 4 is connected to the electrical path L1 via the electrical path L2. The power storage device 4 includes a secondary power supply device 5, a switch unit 6, and a microcomputer 7. The secondary power supply device 5 is connected in parallel with the main power supply device 3, and supplies DC power to the load 2 by discharging a battery built in the secondary power supply device 5.

[0015] The switch unit 6 is provided on an electrical path L2 through which the discharge current of the battery flows from the secondary power supply device 5 to the load 2. The switch unit 6 performs an ON / OFF operation under the control of a microcomputer 7. Here, the switch unit 6 in this embodiment includes at least one first switching element SW1 and one second switching element SW2 connected in series. That is, the number of first switching elements SW1 and one second switching element SW2 included in the switch unit 6 in this embodiment can be changed as needed.

[0016] The first switching element SW1 includes a connect / disconnect unit 61 that connects / disconnects the electrical path L2 and a diode unit 62 connected in parallel to the connect / disconnect unit 61. The second switching element SW2 includes a connect / disconnect unit 63 that connects / disconnects the electrical path L2 and a diode unit 64 connected in parallel to the connect / disconnect unit 63. The diode units 62 and 64 allow current to pass in only one direction.

[0017] In addition, in the first switching element SW1, the diode section 62 is oriented in the forward direction so as to pass the battery's discharge current. That is, a forward voltage is applied to the diode section 62 of the first switching element SW1 by the output from the battery. In addition, in the second switching element SW2, the diode section 64 is oriented in the reverse direction so as to cut off the battery's discharge current. That is, a reverse voltage is applied to the diode section 64 of the second switching element SW2 by the output from the battery.

[0018] The microcomputer 7 includes a predetermined processor as a hardware resource. The microcomputer 7 controls the on and off operations of the switch unit 6. Here, the control of the on and off operations of the switch unit 6 executed by the microcomputer 7 in this embodiment will be described. In the following description, "opening the connection / disconnection unit" means interrupting the connection of the connection / disconnection unit to prevent current from flowing, and "closing the connection / disconnection unit" means connecting the connection / disconnection unit to allow current to flow.

[0019] (Microcomputer controls the on-operation of the switch) First, since the main power supply device 3 and the power storage device 4 are connected in parallel, the microcomputer 7 can detect the value of the voltage output from the main power supply device 3 (in other words, the value of the voltage input to the load 2). When the voltage input to the load 2 falls below a predetermined threshold value, the microcomputer 7 controls the switch unit 6 to start an ON operation for supplying DC power from the secondary power supply device 5 to the load 2. Specifically, in the ON operation, the microcomputer 7 controls the switch unit 6 to close each of the make-and-break unit 61 of the first switching element SW1 and the make-and-break unit 63 of the second switching element SW2.

[0020] As a result, the power supply system 1 of this embodiment can supply DC power to the load 2 from the secondary power supply 5 instead of the main power supply 3 when the power supply from the main power supply 3 to the load 2 decreases (for example, when a power outage occurs in the main power supply 3).

[0021] (Switch off operation controlled by a microcomputer) Next, when the DC power supplied from the main power supply 3 to the load 2 is restored, the microcomputer 7 starts an OFF operation to limit the DC power supplied from the secondary power supply 5 to the load 2 (in other words, starts a power restoration operation). At this time, the microcomputer 7 limits the supply of DC power from the secondary power supply 5 to the load 2 so that the voltage input to the load 2 does not become less than a predetermined threshold until a predetermined time has elapsed since the start of the OFF operation.

[0022] Specifically, during the off operation, the microcomputer 7 opens the make-and-break part 61 of at least one first switching element SW1 from the start of the off operation until a predetermined time has elapsed, and also closes the make-and-break part 63 of the second switching element SW2.

[0023] Finally, the microcomputer 7 controls the switch unit 6 so that the supply of DC power from the secondary power supply device 5 to the load 2 becomes zero after the predetermined time has elapsed. Specifically, the microcomputer 7 controls the switch unit 6 so that the make-and-break unit 61 of the first switching element SW1 and the make-and-break unit 63 of the second switching element SW2 are each opened after the predetermined time has elapsed.

[0024] By controlling the turning-off operation of the switch unit 6 by the microcomputer 7, a forward voltage is applied to the diode unit 62 corresponding to the opened connect / disconnect unit 61, thereby reducing the voltage value of the DC power supplied from the secondary power supply device 5 to the load 2. For example, if the first switching element SW1 is configured with a MOSFET, the parasitic diode is used as the diode unit 62, and only one first switching element SW1 is opened, the voltage value of the DC power supplied from the secondary power supply device 5 to the load 2 will reduce by approximately 0.6 V. In other words, the power supply system 1 according to this embodiment reduces the voltage value of the DC power supplied from the secondary power supply device 5 to the load 2, limits the discharge current until a predetermined time has elapsed, and prevents the voltage input to the load 2 from becoming less than a predetermined threshold.

[0025] Furthermore, the power supply system 1 according to this embodiment connects a plurality of first switching elements SW1 in series, and changes the number of first switching elements SW1 whose connecting / disconnecting units 61 are open according to the voltage input to the load 2 of each first switching element SW1. This allows the power supply system 1 according to this embodiment to gradually reduce the discharge current to zero. In other words, the power supply system 1 according to this embodiment can more reliably prevent the voltage input to the load 2 from falling below a predetermined threshold.

[0026] Furthermore, during the off operation, the microcomputer 7 may repeatedly close or open only the make-or-break part 63 of the second switching element SW2, or both the make-or-break part 61 of the first switching element SW1 and the make-or-break part 63 of the second switching element SW2, in accordance with a preset duty ratio from the start of the off operation until a predetermined time has elapsed. Here, the duty ratio in this embodiment indicates the ratio of the on period to the open period of the make-or-break part 61 of the first switching element SW1 and the make-or-break part 63 of the second switching element SW2.

[0027] The closing and opening of the disconnecting unit 61 and the disconnecting unit 63 can be repeated at a constant cycle from the start of the off operation until a predetermined time has elapsed, but can also be done as follows: The microcomputer 7 stores a plurality of duty ratios in advance, as shown in FIG. 2. The microcomputer 7 selects duty ratios from the plurality of duty ratios in order from the duty ratio with the largest proportion of the closed period to the duty ratio with the smallest proportion of the closed period. The microcomputer 7 repeatedly closes and opens the connect / disconnect unit 61 of the first switching element SW1 and the connect / disconnect unit 63 of the second switching element SW2 in accordance with the selected duty ratio.

[0028] 2, by controlling the turning-off operation of the switch unit 6 by the microcomputer 7, the discharge current output from the secondary power supply device 5 gradually decreases, and therefore the voltage value of the DC power supplied from the secondary power supply device 5 to the load 2 also gradually decreases. In other words, the power supply system 1 according to this embodiment can more reliably prevent the voltage input to the load 2 from falling below a predetermined threshold.

[0029] As a result, in the off operation, the power supply system 1 according to this embodiment can more reliably prevent a sudden voltage drop in the power supply path of the power supply system 1 (i.e., a sudden drop in the voltage input to the load 2). That is, the power supply system 1 according to this embodiment can prevent the voltage input to the load from falling below a predetermined threshold and restarting power supply to the load from the secondary power supply path.

[0030] Therefore, the power supply system 1 according to this embodiment can achieve a smooth power restoration operation.

[0031] (Second embodiment) 3 is a block diagram showing a power supply system 1a according to the second embodiment. For the sake of convenience, detailed description of each component of the power supply system 1a according to the second embodiment that is substantially the same as each component of the power supply system 1 according to the first embodiment will be omitted, and only a description will be given as needed.

[0032] 1, the power supply system 1a shown in Fig. 3 converts power supplied from an external power supply PS into DC power that can be supplied to a load 2, and supplies the DC power to the load 2. Furthermore, when the power supply from the external power supply PS drops (for example, when the power supply from the external power supply PS to the load 2 is stopped due to a power outage or other cause), the power supply system 1a discharges a built-in battery and supplies the DC power stored in the battery to the load 2.

[0033] A power supply system 1a according to this embodiment includes a main power supply device 3 and a power storage device 4a, as shown in Figure 3. The main power supply device 3 in this embodiment is the same as the main power supply device 3 in the first embodiment.

[0034] In this embodiment, the power storage device 4a is connected to the electrical path L1 via the electrical path L2. The power storage device 4a includes a secondary power supply device 5, a switch unit 6a, and a microcomputer 7a. The secondary power supply device 5 is the same as the secondary power supply device 5 in the first embodiment.

[0035] The switch unit 6a is provided on an electrical path L2 through which the discharge current of the battery flows from the secondary power supply device 5 to the load 2. The switch unit 6a performs an ON / OFF operation under the control of a microcomputer 7a. Here, the switch unit 6a in this embodiment includes one switching element SW. The switching element SW also has a connecting / disconnecting part 65 that connects and disconnects the electrical path L2.

[0036] The microcomputer 7a includes a predetermined processor as a hardware resource. The microcomputer 7a controls the on and off operations of the switch unit 6a. Here, the control of the on and off operations of the switch unit 6a executed by the microcomputer 7a in this embodiment will be described.

[0037] (Microcomputer controls the on-operation of the switch) First, since the main power supply device 3 and the power storage device 4 are connected in parallel, the microcomputer 7a can detect the value of the voltage output from the main power supply device 3 (in other words, the value of the voltage input to the load 2). When the voltage input to the load 2 falls below a predetermined threshold value, the microcomputer 7a controls the switch unit 6a to start an ON operation for supplying DC power from the secondary power supply device 5 to the load 2. Specifically, in the ON operation, the microcomputer 7 controls the switch unit 6a to close the connect / disconnect unit 65 of the switching element SW.

[0038] As a result, in the power supply system 1a of this embodiment, when the power supply from the main power supply device 3 to the load 2 decreases (for example, when a power outage occurs in the main power supply device 3), DC power can be supplied to the load 2 from the secondary power supply device 5 of the storage device 4a instead of the main power supply device 3.

[0039] (Switch off operation controlled by a microcomputer) Next, when the DC power supplied from the main power supply 3 to the load 2 is restored, the microcomputer 7a starts an OFF operation to limit the DC power supplied from the secondary power supply 5 to the load 2 (in other words, starts a power restoration operation). At this time, the microcomputer 7a limits the supply of DC power from the secondary power supply 5 to the load 2 so that the voltage input to the load 2 does not become less than a predetermined threshold until a predetermined time has elapsed since the start of the OFF operation.

[0040] For example, during the off operation, the microcomputer 7a may repeatedly close or open the make-or-break portion 65 of the switching element SW in accordance with a preset duty ratio from the start of the off operation until a predetermined time has elapsed. Here, the duty ratio in this embodiment indicates the ratio of the closed period to the open period of the make-or-break portion 65 of the switching element SW.

[0041] The closing and opening of the disconnecting unit 65 can be repeated at a fixed cycle from the start of the off operation until a predetermined time has elapsed, but can also be done as follows: The microcomputer 7a stores a plurality of duty ratios in advance, as shown in FIG. 2. The microcomputer 7a selects duty ratios from the plurality of duty ratios in order from the duty ratio with the largest proportion of the closed period to the duty ratio with the smallest proportion of the closed period. The microcomputer 7 repeatedly closes and opens the disconnecting unit 65 of the switching element SW in accordance with the selected duty ratio.

[0042] 2, by controlling the turning-off operation of the switch unit 6a by the microcomputer 7a, the discharge current of the secondary power supply device 5 gradually decreases, and therefore the voltage value of the DC power supplied from the secondary power supply device 5 of the power storage device 4a to the load 2 also gradually decreases. In other words, the power supply system 1a according to this embodiment can more reliably prevent the voltage input to the load 2 from falling below a predetermined threshold.

[0043] As a result, the power supply system 1a according to this embodiment can more reliably prevent a sudden voltage drop in the power supply path of the power supply system 1a (i.e., a sudden drop in the voltage input to the load 2) during the off operation. That is, the power supply system 1a according to this embodiment can prevent the voltage input to the load from falling below a predetermined threshold and restarting power supply to the load from the secondary power supply path.

[0044] Therefore, the power supply system 1 according to this embodiment can achieve a smooth power restoration operation.

[0045] Here, the battery in the above embodiment is a commonly known primary battery such as a manganese battery, an alkaline battery, or a lithium battery, or a commonly known secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The battery may be a single cell or a battery pack.

[0046] Furthermore, the external power supply PS in the above embodiments may be a household power supply or a commercial power supply. Furthermore, the external power supply PS may be a power supply capable of supplying DC power or a power supply capable of supplying AC power. That is, the internal configuration of the power supply system 1 according to the above embodiments can be changed as appropriate depending on the type of external power supply PS and the power available to the load 2. In this case, the main power supply device 3 in the above embodiments can be changed as appropriate depending on the type of external power supply PS and the power available to the load 2. For example, the main power supply device 3 in the above embodiments may include a rectifier, an AC-DC converter, or a DC-DC converter.

[0047] Furthermore, the main power supply device 3 in the above embodiment converts power supplied from the external power supply PS into DC power that can be supplied to the load 2, and supplies the DC power to the load 2. However, the power supply systems 1, 1a according to the above embodiment are not limited to this. For example, the main power supply device 3 in the above embodiment may be equipped with a power generation facility that generates DC power or a power supply facility such as the battery.

[0048] The load 2 in the above embodiment is assumed to be, for example, a train circuit breaker or other device that is required to operate for a certain period of time when the power supply from the external power source PS is stopped.

[0049] Furthermore, the first switching element SW1, the second switching element SW2, and the switching element SW in the above-described embodiments may be generally known semiconductor switching elements such as bipolar transistors, junction FETs, MOSFETs, IGBTs, etc. Furthermore, the first switching element SW1 in the above-described embodiments may have the diode section 62 as a parasitic diode present in the first switching element SW1.

[0050] 1 and 3 show power supply systems 1, 1a including power storage devices 4, 4a that use n-channel MOSFETs and p-channel MOSFETs as the first switching element SW1 and the second switching element SW2. However, the power supply systems 1, 1a according to the above embodiments are not limited to this. For example, the power supply systems 1, 1a according to the above embodiments may include power storage devices 4, 4a that are configured by combining various commonly known switching elements.

[0051] Furthermore, the term "predetermined processor" used in the above description refers to, for example, a dedicated or general-purpose processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit), or an Application Specific Integrated Circuit (ASIC), a programmable logic device (for example, a Simple Programmable Logic Device (SPLD) or a Complex Programmable Logic Device (CPLD)), or a Field Programmable Gate Array (FPGA). Furthermore, each component (each processing unit) of this embodiment is not limited to being realized by a single processor, but may be realized by multiple processors. Furthermore, multiple components (multiple processing units) may be realized by a single processor.

[0052] Although the embodiment has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0053] 1,1a power system 2. Load 3 Main power supply 4,4a Energy storage device 5 Sub-power supply 6,6a Switch section 61,63,65 Disconnection part 62,64 Diode section 7,7a Microcomputer L1, L2 electrical pathway SW Switching element SW1 First switching element SW2 Second switching element

Claims

1. a main power supply that supplies DC power to a load; a secondary power supply device connected in parallel to the main power supply device and discharging a built-in battery to supply DC power to the load; a switch unit that is provided in an electrical path through which a discharge current of the battery flows from the secondary power supply device to the load and that performs an on-operation and an off-operation; a microcomputer that controls the on and off operations of the switch unit; Equipped with The microcomputer controlling the switch unit to start an ON operation for supplying the DC power from the secondary power supply device to the load when the DC power supplied from the main power supply device decreases and the voltage input to the load becomes less than a predetermined threshold; when the DC power supplied from the main power supply device is restored, an off operation is initiated to limit the DC power supplied from the secondary power supply device to the load, and the supply of DC power from the secondary power supply device to the load is limited until a predetermined time has elapsed since the start of the off operation so that a voltage input to the load does not become less than a predetermined threshold, and after the predetermined time has elapsed, the switch unit is controlled so that the supply of DC power from the secondary power supply device to the load becomes zero; the switch unit includes at least one first switching element and one second switching element connected in series, the first switching element and the second switching element each having a connect / disconnect portion that connects / disconnects the electrical path, and a diode portion that is connected in parallel with the connect / disconnect portion and that passes current in only one direction, the first switching element is oriented in a forward direction so that the diode portion of the first switching element passes a discharge current of the battery, and the second switching element is oriented in a reverse direction so that the diode portion of the second switching element blocks the discharge current of the battery, The microcomputer In the on-operation, the switch unit is controlled so as to close each of the make-and-break portion of the first switching element and the make-and-break portion of the second switching element; In the off operation, From the start of the off operation until the predetermined time has elapsed, a make-and-break portion of the at least one first switching element is opened and a make-and-break portion of the second switching element is closed, After the predetermined time has elapsed, the switch unit is controlled so as to open each of the make-and-break portion of the first switching element and the make-and-break portion of the second switching element. Power supply system.

2. In the off operation, the microcomputer from the start of the off operation until the predetermined time has elapsed, repeating an operation of closing or opening the make-and-break portion of the first switching element and the make-and-break portion of the second switching element in accordance with a preset duty ratio indicating a ratio of a closing period to an opening period of each of the make-and-break portion of the first switching element and the make-and-break portion of the second switching element; After the predetermined time has elapsed, the switch unit is controlled so as to open each of the make-and-break portion of the first switching element and the make-and-break portion of the second switching element. The power supply system of claim 1 .

3. 3. The power supply system according to claim 2, wherein the microcomputer selects the duty ratios from a plurality of preset duty ratios in order from the duty ratio with the largest proportion of the closed period to the duty ratio with the smallest proportion of the closed period, and performs an operation of closing or opening each of the make-and-break portion of the first switching element and the make-and-break portion of the second switching element in accordance with the selected duty ratio.

4. The power supply system according to claim 1 , wherein the first switching element has a parasitic diode as the diode portion.

5. 5. A power storage device used in the power supply system according to claim 1, comprising: the secondary power supply device; the switch section; and the microcomputer.

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