Power supply device

Abstract

To provide a power supply device that makes it possible to prevent interruption and suppress fluctuation in output voltage to maintain a stable supply of power, even when the connection of a plurality of secondary batteries to a load is switched.SOLUTION: A power supply device according to the present invention comprises a first battery (12a) and a second battery (12b) that charge and discharge, a first switch sequence, a second switch sequence, a parallel connection unit, and a switch control unit (11). The first switch sequence includes a first switch (S1a), a third switch (S1b), and a first diode (D1a), and the second switch sequence includes a second switch (S2a), a fourth switch (S2b), and a second diode (D2a). When the switch control unit (11) shifts from a first connection period to a second connection period, there is an overlap period during which the first switch (S1a) and the second switch (S2a) are in an off state and the third switch (S1b) and the fourth switch (S2b) are in an on state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device, and more particularly to a power supply device that switches between a plurality of secondary batteries to supply power. [Background technology]

[0002] Power supply devices have been proposed for enabling electrical equipment to be used outdoors or in emergencies. These power supply devices typically use gasoline or other gas as fuel to drive an internal combustion engine, converting the engine's kinetic energy into electrical energy. However, power supply devices using internal combustion engines consume oxygen during fuel combustion, making them unsuitable for use indoors or in enclosed spaces. Therefore, power supply devices that supply power from secondary batteries that store electricity have become increasingly popular in recent years.

[0003] In such power supply devices using secondary batteries, the amount of power that can be supplied depends on the charge capacity of the secondary battery, so there is a problem that the secondary battery must be large to continuously supply large amounts of power, resulting in increased weight and higher prices. To avoid such problems, power supply devices have been proposed that are equipped with multiple detachable secondary batteries and switch between power supplies from the multiple secondary batteries (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2006-296109 A Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional power supply devices, when the remaining charge of a secondary battery connected to a load decreases or when the secondary battery is removed, the secondary battery is disconnected and then another secondary battery is selected and connected to the load. With such conventional technology, the voltage at the input of the DC-AC inverter changes before and after switching the connection of the secondary battery, and at the moment of switching, there is a period of time when power is not supplied from the secondary battery, resulting in a sudden drop in voltage.

[0006] Therefore, when switching the connection of secondary batteries in conventional power supply devices, a momentary power interruption occurs, making it difficult to continuously supply power to the load. In particular, in power supply devices that convert direct current (DC) supplied from secondary batteries to alternating current (AC) using a DC-AC inverter, the voltage fluctuations of the output AC current can become large, potentially causing malfunctions in precision instruments and information devices. Furthermore, suppressing output voltage fluctuations requires a fast-response inverter power supply circuit, which increases the size and cost of the power supply device. In particular, when reusing secondary batteries used in electric vehicles, the problem of voltage fluctuations caused by switching the connection of secondary batteries becomes more pronounced due to the low internal impedance of the secondary batteries.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide a power supply device that can continue to supply stable power by preventing momentary power interruptions and suppressing fluctuations in output voltage even when switching the connection of multiple secondary batteries to a load. [Means for solving the problem]

[0008] In order to solve the above problem, a power supply device of the present invention includes a first battery and a second battery for charging and discharging, a first switch string having one end connected to a first output section of the first battery, a second switch string having one end connected to a second output section of the second battery, a parallel connection section to which the other end of the first switch string and the other end of the second switch string are connected, and a switch control section for controlling opening and closing of the first switch string and the second switch string, wherein the first switch string has a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode connected in parallel to the first switch in a forward direction, and the second switch string has one end connected to the second output section. the switch control section includes a second switch connected to the second switch, a fourth switch having one end connected to the other end of the second switch and the other end connected to the parallel connection section, and a second diode forward-connected in parallel to the second switch, and the switch control section includes an overlapping period during which the first switch and the second switch are in the off state and the third switch and the fourth switch are in the on state, while changing from a first connection period during which the first switch and the third switch are in the on state and the second switch and the fourth switch are in the off state to a second connection period during which the first switch and the third switch are in the off state and the second switch and the fourth switch are in the on state, and the first connection period, overlapping period, and second connection period are continuous.

[0009] In such a power supply device of the present invention, when switching the connection from the first battery to the second battery, there is an overlap period during which the first switch and the second switch are in the off state and the third switch and the fourth switch are in the on state. Therefore, even when switching the connection of multiple secondary batteries to the load, it is possible to prevent momentary power interruptions and suppress fluctuations in output voltage, thereby continuing to supply stable power.

[0010] In one aspect of the present invention, the overlap period is in the range of 5 ms to 60 ms.

[0011] In order to solve the above problem, a power supply device of the present invention includes a first battery and a second battery for charging and discharging, a first switch string having one end connected to a first output section of the first battery, a second switch string having one end connected to a second output section of the second battery, a parallel connection section to which the other end of the first switch string and the other end of the second switch string are connected, and a switch control section for controlling opening and closing of the first switch string and the second switch string, wherein the first switch string has a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode connected in parallel to the first switch in a forward direction, and the second switch string has a second switch having one end connected to the second output section and one end connected to the second switch. the switch control unit includes an overlap period during which the first switch and the second switch are in an off state and the third switch and the fourth switch are in an on state, while changing from a first connection period during which the first switch and the third switch are in an on state and the second switch and the fourth switch are in an off state to a second connection period during which the first switch and the third switch are in an off state and the second switch and the fourth switch are in an on state, the parallel connection unit is connected to a DC-AC inverter, and the overlap period is in a range of 0.5 to 5 cycles of an output waveform from the DC-AC inverter.

[0012] In one aspect of the present invention, the peak fluctuation of the output waveform during the overlap period is 10% or less.

[0013] In order to solve the above problem, a power supply device of the present invention includes a first battery and a second battery for charging and discharging, a first switch string having one end connected to a first output section of the first battery, a second switch string having one end connected to a second output section of the second battery, a parallel connection section to which the other end of the first switch string and the other end of the second switch string are connected, and a switch control section for controlling opening and closing of the first switch string and the second switch string, wherein the first switch string has a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode connected in parallel to the first switch in a forward direction, and the second switch string has a second switch having one end connected to the second output section and one end connected to the other end of the second switch. The battery control unit has a fourth switch whose other end is connected to the parallel connection portion, and a second diode forward-connected in parallel to the second switch, and the switch control unit has an overlap period during which the first switch and the second switch are in an off state and the third switch and the fourth switch are in an on state, during which the first connection period is changed from a first connection period during which the first switch and the third switch are in an on state and the second switch and the fourth switch are in an off state to a second connection period during which the first switch and the third switch are in an off state and the second switch and the fourth switch are in an on state, the output portion of the first battery is at a first potential, the output portion of the second battery is at a second potential, and during the overlap period, the potential of the parallel connection portion is an intermediate potential between the first potential and the second potential.

[0014] In one embodiment of the present invention, the first switch and the second switch are field-effect transistors, The first diode and the second diode are body diodes of the first switch and the second switch. [Effects of the Invention]

[0015] The present invention provides a power supply device and a power supply control method that can prevent momentary power interruptions and suppress fluctuations in output voltage, even when switching the connection of multiple secondary batteries to a load, thereby continuing to supply stable power. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing an example of the configuration of a power supply device 10 according to a first embodiment of the present invention. [Figure 2] 2A and 2B are diagrams showing an example of the configuration of switches and diodes used in the power supply device 10, where FIG. 2A shows an equivalent circuit and FIG. 2B shows a circuit symbol. [Figure 3] 3A and 3B are diagrams showing switching of connections in the power supply device 10, where FIG. 3A shows a first connection period, FIG. 3B shows an overlap period, and FIG. 3C shows a second connection period. [Figure 4] 4(a) and 4(b) are timing charts showing the switching of connections in the power supply device 10, where FIG. 4(a) shows the signal of the first switch S1a, FIG. 4(b) shows the signal of the third switch S1b, FIG. 4(c) shows the signal of the second switch S2a, FIG. 4(d) shows the signal of the fourth switch S2b, and FIG. 4(e) shows the voltage at the input position of the DC-AC inverter 13. [Figure 5] 10 is a graph showing a schematic diagram of a change in output voltage AC_OUT at the output position of the DC-AC inverter 13. [Figure 6] This shows the voltage at the input position of the DC-AC inverter 13 when the connection is switched from the high voltage side to the low voltage side. [Figure 7] FIG. 10 is a diagram showing switching of connections in the power supply device 10 according to the second embodiment, illustrating a third connection period provided before the overlap period. [Figure 8]8(a) and 8(b) are timing charts showing the switching of connections in the power supply device 10, where FIG. 8(a) shows the signal of the first switch S1a, FIG. 8(b) shows the signal of the third switch S1b, FIG. 8(c) shows the signal of the second switch S2a, FIG. 8(d) shows the signal of the fourth switch S2b, and FIG. 8(e) shows the voltage at the input position of the DC-AC inverter 13. DETAILED DESCRIPTION OF THE INVENTION

[0017] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be denoted by the same reference numerals, and redundant description will be omitted where appropriate. FIG. 1 is a block diagram showing an example configuration of a power supply device 10 according to this embodiment. As shown in FIG. 1, the power supply device 10 includes a switch control unit 11, a first battery 12a, a second battery 12b, a first switch S1a, a second switch S2a, a third switch S1b, a fourth switch S2b, a first diode D1a, a second diode D2a, a third diode D1b, a fourth diode D2b, a DC-AC inverter 13, and a load 14.

[0018] Here, the first switch S1a, the third switch S1b, the first diode D1a, and the third diode D1b constitute the first switch array of the present invention. The first switch array is a section that connects and disconnects the first battery 12a and the load 14 by opening and closing operations. The second switch S2a, the fourth switch S2b, the second diode D2a, and the fourth diode D2b constitute the second switch array of the present invention. The second switch array is a section that connects and disconnects the second battery 12b and the load 14 by opening and closing operations. The series connection between the first battery 12a and the first switch array and the series connection between the second battery 12b and the second switch array are each connected in parallel to the DC-AC inverter 13 via a parallel connection section. The voltage of the parallel connection section is DCAC_IN.

[0019] The switch control unit 11 is a part that controls the opening and closing operations of the first switch array and the second switch array (first switch S1a, second switch S2a, third switch S1b, and fourth switch S2b). The specific configuration of the switch control unit 11 is not limited, but it may include a memory, an external storage device, a central processing unit (CPU), an information communication device, etc. (not shown), and may control the first switch array and the second switch array by processing information according to a predetermined program. The switch control unit 11 may also monitor the status of each part of the power supply device 10 and control the opening and closing operations of the first switch array and the second switch array based on the status of each part and the predetermined program.

[0020] The first battery 12a and the second battery 12b are secondary batteries capable of charging and discharging power. Like known secondary batteries, the first battery 12a and the second battery 12b are equipped with terminals used for charging and discharging, a BMS (Battery Management System) that controls charging and discharging, and the like. The output of the first battery 12a is connected to one end of a first switch S1a, and the output of the second battery 12b is connected to one end of a second switch S2a. The voltage at the output of the first battery 12a is VBA1, and the voltage at the output of the second battery 12b is VBA2.

[0021] The specific configuration of the first battery 12a and the second battery 12b is not limited, and known lithium-ion batteries, nickel-metal hydride batteries, all-solid-state batteries, etc. can be used. Furthermore, battery cells contained in secondary batteries used in electric vehicles, hybrid vehicles, etc. may be reused and used as the first battery 12a and the second battery 12b. Recycled battery cells may have different degrees of deterioration and may have different chargeable capacities and output voltages, but they can be used without any problems in the power supply device 10 of this embodiment. The internal impedance of the first battery 12a and the second battery 12b is not limited, and may be less than 10 mΩ.

[0022] The first switch S1a and the second switch S2a have one end connected to the output of the first battery 12a and the second battery 12b, respectively. The other ends of the first switch S1a and the second switch S2a are connected to the third switch S1b and the fourth switch S2b, respectively. The first switch S1a and the second switch S2a are connected in parallel with a first diode D1a and a second diode D2a in the forward direction, respectively.

[0023] The third switch S1b and the fourth switch S2b have one end connected to the first switch S1a and the second switch S2a, respectively. The other ends of the third switch S1b and the fourth switch S2b are connected to the DC-AC inverter 13 via a parallel connection part. The third switch S1b and the fourth switch S2b are connected in parallel to a third diode D1b and a fourth diode D2b in the opposite direction, respectively.

[0024] The specific configurations of the first switch S1a, the second switch S2a, the third switch S1b, and the fourth switch S2b are not limited, and known semiconductor switches or mechanical switches can be used. As will be described later, the opening and closing operations of the first switch S1a, the second switch S2a, the third switch S1b, and the fourth switch S2b are performed on the order of milliseconds, so it is preferable to use semiconductor switches such as field effect transistors (FETs) that are capable of high-speed switching operations.

[0025] The first diode D1a and the second diode D2a are diodes connected in parallel with the first switch S1a and the second switch S2a, respectively. The anodes of the first diode D1a and the second diode D2a are connected to the outputs of the first battery 12a and the second battery 12b, respectively. The cathodes of the first diode D1a and the second diode D2a are connected to the third switch S1b and the fourth switch S2b, respectively. Therefore, the first diode D1a and the second diode D2a are connected in the forward direction.

[0026] The third diode D1b and the fourth diode D2b are diodes connected in parallel with the third switch S1b and the fourth switch S2b, respectively. The anodes of the third diode D1b and the fourth diode D2b are connected to the other ends of the first diode D1a and the second diode D2a, respectively. The cathodes of the third diode D1b and the fourth diode D2b are connected to the DC-AC inverter 13 via the parallel connection part. Therefore, the third diode D1b and the fourth diode D2b are connected in the opposite directions. Although FIG. 1 shows an example in which the third diode D1b and the fourth diode D2b are provided, the third diode D1b and the fourth diode D2b may be omitted.

[0027] The DC-AC inverter 13 is provided between the parallel connection unit and the load 14, and converts DCAC_IN, a direct current input from the parallel connection unit, into AC_OUT and outputs it to the load 14. There are no particular limitations on the specific circuit configuration of the DC-AC inverter 13, and a known configuration can be used, but it is preferable to output a sine wave in order to broaden the range of targets that can be operated as the load 14. There are no particular limitations on the AC_OUT output from the DC-AC inverter 13, but it is preferable that it be in the voltage range of 100 V to 220 V and the frequency range of 50 to 60 Hz, which are used as commercial power sources in various countries.

[0028] The load 14 is an electronic device that is connected to the output of the DC-AC inverter 13 and is driven by the AC current output from the DC-AC inverter 13. The load 14 is not limited, but examples include computers, network devices, electronic medical devices, and ultra-low temperature freezers. The power supply device 10 of this embodiment does not cause momentary power interruptions when switching between multiple secondary batteries and can suppress fluctuations in output voltage, so that these loads 14 that require a stable power supply can be connected and used continuously.

[0029] 1 shows an example using two batteries and two switch arrays, but the number of batteries and switches is not limited, and three or more batteries and switch arrays may be used. Even when three or more batteries are selectively switched, the battery connected in the first connection period before the switching and the battery connected in the second connection period after the switching operate as a pair. Therefore, even when three or more batteries are provided in the power supply device 10, the operation and control of the connection switching are the same as when two batteries are used.

[0030] 2A and 2B are diagrams showing an example of the configuration of switches and diodes used in the power supply device 10, with Fig. 2A showing an equivalent circuit and Fig. 2B showing circuit symbols. When field-effect transistors are used as the first switch S1a, the second switch S2a, the third switch S1b, and the fourth switch S2b, the body diodes of the field-effect transistors can be used as the first diode D1a, the second diode D2a, the third diode D1b, and the fourth diode D2b, respectively.

[0031] 3 is a diagram showing the switching of connections in the power supply device 10, with FIG. 3(a) showing the first connection period, FIG. 3(b) showing the overlap period, and FIG. 3(c) showing the second connection period. For simplicity, the switch control unit 11 is not shown in FIG. 3, but the first switch S1a, the second switch S2a, the third switch S1b, and the fourth switch S2b are controlled to open and close by control signals sent from the switch control unit 11. The arrows shown in the figure schematically show an example of the direction of current.

[0032] 3(a), the first switch S1a and the third switch S1b are in a closed state (ON), and the second switch S2a and the fourth switch S2b are in an open state (OFF). Therefore, a direct current is supplied from the first battery 12a to the first switch S1a, the third switch S1b, and the parallel connection unit, and is converted into AC_OUT by the DC-AC inverter 13 and supplied to the load 14. When an instruction is issued in the power supply device 10 to stop discharging from the first battery 12a and switch to discharging from the second battery 12b, the period transitions to the overlap period.

[0033] Here, examples of cases in which discharging from the first battery 12a is stopped include when the remaining charge of the first battery 12a decreases and the battery is switched from being a discharge target to being a charge target. Also, examples include when the first battery 12a is removed and a locking mechanism (not shown) is released. Also, examples include when the user inputs an instruction to exclude the first battery 12a from being a discharge target. Also, examples include when the temperature of the first battery 12a rises and a protection instruction to stop discharging is sent by a control unit included in the power supply device 10.

[0034] During the overlap period shown in FIG. 3(b), the third switch S1b and the fourth switch S2b are closed (on), and the first switch S1a and the second switch S2a are open (off). During this overlap period, a direct current is supplied from the first battery 12a to the first diode D1a, the third switch S1b, and the parallel connection portion. A direct current is also supplied from the second battery 12b to the second diode D2a, the fourth switch S2b, and the parallel connection portion. Since the first diode D1a and the second diode D2a are connected in the forward direction from the first battery 12a and the second battery 12b, no reverse current flows from the parallel connection portion to the first battery 12a and the second battery 12b. During this overlap period, a direct current is supplied from the voltages of the first battery 12a and the second battery 12b to the parallel connection portion, where it is converted to AC_OUT by the DC-AC inverter 13 and supplied to the load 14. After an overlap period set to a predetermined length has elapsed, a transition to the second connection period occurs.

[0035] 3(c), the first switch S1a and the third switch S1b are in an open state (off), and the second switch S2a and the fourth switch S2b are in a closed state (on). Therefore, a direct current is supplied from the second battery 12b to the second switch S2a, the fourth switch S2b, and the parallel connection unit, and is converted into AC_OUT by the DC-AC inverter 13 and supplied to the load 14. Thereafter, the load 14 continues to operate using the power supplied from the second battery 12b.

[0036] As described above, in the power supply device 10 of this embodiment, when the switch control unit 11 switches the connection from the first battery 12a to the second battery 12b, an overlap period is provided in which the first switch S1a and the second switch S2a are in the OFF state and the third switch S1b and the fourth switch S2b are in the ON state. Therefore, throughout the first connection period, the overlap period, and the second connection period, the first battery 12a or the second battery 12b is connected to the parallel connection unit, and no momentary interruption occurs during the switching.

[0037] 4 is a timing chart showing the switching of connections in the power supply device 10, where FIG. 4(a) shows the signal of the first switch S1a, FIG. 4(b) shows the signal of the third switch S1b, FIG. 4(c) shows the signal of the second switch S2a, FIG. 4(d) shows the signal of the fourth switch S2b, and FIG. 4(e) shows the voltage at the input position of the DC-AC inverter 13. In the diagram, the horizontal axis represents time t, and the vertical axis represents voltage. Furthermore, up to time t1, the first connection period (period A) is shown, from time t1 to t2, the overlap period (period B) is shown, and from time t2 onwards, the second connection period (period C) is shown.

[0038] As shown in FIG. 4(a), an ON signal is applied to the first switch S1a during the first connection period, and an OFF signal is applied to the overlap period and the second connection period. Also, as shown in FIG. 4(b), an ON signal is applied to the third switch S1b during the first connection period and the overlap period, and an OFF signal is applied to the second connection period. Also, as shown in FIG. 4(c), an OFF signal is applied to the second switch S2a during the first connection period and the overlap period, and an ON signal is applied to the second connection period. Also, as shown in FIG. 4(d), an OFF signal is applied to the fourth switch S2b during the first connection period, and an ON signal is applied to the overlap period and the first connection period.

[0039] 4(e) shows a case where the first battery 12a has a low voltage and the second battery 12b has a high voltage, and the connection is switched from the low voltage side to the high voltage side. As shown in FIG. 4(e), the voltage at the input position (parallel connection portion) of the DC-AC inverter 13 is approximately equal to the voltage VBA1 (corresponding to a first potential) at the output portion of the first battery 12a during the first connection period, and is approximately equal to the voltage VBA2 (corresponding to a second potential) at the output portion of the second battery 12b during the second connection period. During the overlap period, the voltage at the input position (parallel connection portion) of the DC-AC inverter 13 is at an intermediate potential between VBA1 and VBA2.

[0040] While Figure 4(e) shows an example in which the midpoint potential is close to the average value of VBA1 and VBA2, it does not have to be the average value as long as it is between VBA1 and VBA2. Also, while Figure 4(e) shows an example in which the midpoint potential is constant throughout the overlap period, the potential may vary between VBA1 and VBA2. Furthermore, during the overlap period, a voltage drop occurs due to the first diode D1a and the second diode D2a, so the voltage may be higher than the average of VBA1 and VBA2.

[0041] FIG. 5 is a graph showing a schematic diagram of the change in the output voltage AC_OUT at the output of the DC-AC inverter 13. As shown in FIG. 5, the output voltage AC_OUT at the output of the DC-AC inverter 13 is output as a sinusoidal AC. In FIG. 5, the waveform of AC_OUT after time t1 is indicated by circled numbers. Since the peak and trough constitute one cycle, each number indicates the order of a half cycle of the output waveform. During the first connection period, the peak voltage of AC_OUT is stable. However, at time t1, the overlap period begins, and the peak voltage fluctuates after DCAC_IN changes from VBA1 to the intermediate potential. Furthermore, when the overlap period ends and the second connection period begins at time t2, the peak voltage fluctuates after DCAC_IN changes from the intermediate potential to VBA2. In this embodiment, as shown in FIG. 5, the parallel connection section is at the intermediate potential during the overlap period, thereby suppressing fluctuations in the peak voltage of the output voltage AC_OUT.

[0042] The fluctuation in the peak voltage of AC_OUT increases at t1, when the overlap period begins, and at t2, when the second connection period begins, and then attenuates as the sine wave cycle progresses. This is because even if the input voltage to DC-AC inverter 13 changes, it is converted to the target output voltage value depending on the performance and time constant of DC-AC inverter 13. However, if the fluctuation in the peak voltage of output voltage AC_OUT is large and it takes a long time for it to attenuate and stabilize, there is a possibility that load 14 will not operate normally.

[0043] Therefore, in the power supply device 10 of this embodiment, the overlap period is preferably set in the range of 5 ms to 60 ms, and more preferably in the range of 5 ms to 20 ms. If the overlap period is shorter than this range, it becomes difficult to sufficiently suppress fluctuations in the peak voltage. Furthermore, if the overlap period is longer than this range, there is a greater possibility that the body diodes used for the first diode D1a and the second diode D2a will be damaged, which is undesirable.

[0044] Furthermore, by setting the overlap period within the response time of the DC-AC inverter 13, it is possible to suppress the second increase in peak fluctuation amount by bringing the end time t2 of the overlap period within the response time of the DC-AC inverter 13. Therefore, it is preferable that the overlap period be in the range of 0.5 to 5 periods of the output waveform of AC_OUT from the DC-AC inverter 13.

[0045] Furthermore, by setting the overlap period within the time constant of the DC-AC inverter 13, the end time t2 of the overlap period is within the time constant of the DC-AC inverter 13, thereby making it possible to suppress a second increase in the amount of peak fluctuation. Therefore, it is more preferable that the overlap period be in the range of 0.5 to 2 periods of the output waveform of AC_OUT from the DC-AC inverter 13. Furthermore, it is preferable that the peak fluctuation of the output waveform from the DC-AC inverter 13 during the overlap period be 10% or less.

[0046] FIG. 6 shows the voltage at the input of the DC-AC inverter 13 when the connection is switched from the high-voltage side to the low-voltage side. FIG. 6 illustrates a case in which the first battery 12a has a high voltage, the second battery 12b has a low voltage, and the connection is switched from the high-voltage side to the low-voltage side. In the example illustrated in FIG. 6, the voltage at the input (parallel connection) of the DC-AC inverter 13 is approximately equal to the voltage VBA1 (corresponding to a first potential) at the output of the first battery 12a during the first connection period, and is approximately equal to the voltage VBA2 (corresponding to a second potential) at the output of the second battery 12b during the second connection period. During the overlap period, the voltage at the input (parallel connection) of the DC-AC inverter 13 is at an intermediate potential between VBA1 and VBA2. In this case, too, the intermediate potential is generated at the parallel connection during the overlap period, thereby suppressing fluctuations in the peak voltage of the output voltage AC_OUT.

[0047] As described above, in the power supply device 10 of this embodiment, when switching the connection from the first battery 12a to the second battery 12b, there is an overlap period during which the first switch S1a and the second switch S2a are in the OFF state and the third switch S1b and the fourth switch S2b are in the ON state. Therefore, even when switching the connection of multiple secondary batteries to the load 14, it is possible to prevent momentary power interruptions and suppress fluctuations in the output voltage, thereby continuing to supply stable power.

[0048] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to Figures 7 and 8. Descriptions of content overlapping with the first embodiment will be omitted. This embodiment differs from the first embodiment in that a third connection period is provided between the first connection period and the overlap period. Figure 7 is a diagram showing connection switching in the power supply device 10 according to this embodiment, illustrating the third connection period provided before the overlap period. In this embodiment, the first connection period, overlap period, and second connection period are the same as those shown in Figure 3. The third connection period is provided between Figures 3(a) and 3(b), and transition occurs after the first connection period to the third connection period shown in Figure 7.

[0049] 7, the third switch S1b is closed (ON), and the first switch S1a, the second switch S2a, and the fourth switch S2b are open (OFF). Therefore, a direct current is supplied from the first battery 12a to the first diode D1a, the third switch S1b, and the parallel connection unit, and is converted into AC_OUT by the DC-AC inverter 13 and supplied to the load 14. After the third connection period, which is set to a predetermined length, has elapsed, the period transitions to the overlap period.

[0050] 8 is a timing chart showing the switching of connections in the power supply device 10, where FIG. 8(a) shows the signal of the first switch S1a, FIG. 8(b) shows the signal of the third switch S1b, FIG. 8(c) shows the signal of the second switch S2a, FIG. 8(d) shows the signal of the fourth switch S2b, and FIG. 8(e) shows the voltage at the input position of the DC-AC inverter 13. The horizontal axis in the diagram represents time t, and the vertical axis represents voltage. Furthermore, up to time t3 represents the first connection period (period A), from time t3 to t1 represents the third connection period (period D), from time t1 to t2 represents the overlap period (period B), and from time t2 onwards represents the second connection period (period C).

[0051] As shown in FIG. 8(a), an ON signal is applied to the first switch S1a during the first connection period, and an OFF signal is applied during the third connection period, overlap period, and second connection period. Also, as shown in FIG. 8(b), an ON signal is applied to the third switch S1b during the first connection period, third connection period, and overlap period, and an OFF signal is applied during the second connection period. Also, as shown in FIG. 8(c), an OFF signal is applied to the second switch S2a during the first connection period, third connection period, and overlap period, and an ON signal is applied during the second connection period. Also, as shown in FIG. 8(d), an OFF signal is applied to the fourth switch S2b during the first connection period and third connection period, and an ON signal is applied during the overlap period and first connection period.

[0052] 8(e) shows a case where the first battery 12a has a low voltage and the second battery 12b has a high voltage, and the connection is switched from the low voltage side to the high voltage side. As shown in FIG. 8(e), the voltage at the input position (parallel connection portion) of the DC-AC inverter 13 is approximately equal to the voltage VBA1 (corresponding to a first potential) at the output portion of the first battery 12a during the first connection period, and is approximately equal to the voltage VBA2 (corresponding to a second potential) at the output portion of the second battery 12b during the second connection period. During the overlap period, the voltage at the input position (parallel connection portion) of the DC-AC inverter 13 is at an intermediate potential between VBA1 and VBA2. Furthermore, during the third connection period, the voltage is at an intermediate potential between VBA1 during the first connection period and the intermediate potential during the overlap period.

[0053] While FIG. 8(e) illustrates an example in which the potential during the third connection period is near the average value of VBA1 and the midpoint potential, it need not be the average value as long as it is between VBA1 and the midpoint potential. Also, while FIG. 8(e) illustrates an example in which the potential is constant throughout the third connection period, the potential may vary. Furthermore, during the third connection period, a voltage drop occurs due to the first diode D1a, so the potential may be higher than the average of VBA1 and the midpoint potential. Also, while FIG. 8(e) illustrates an example in which the potential during the third connection period is midpoint between the first connection period and the overlap period, it may be the same as the midpoint potential during the overlap period.

[0054] In the power supply device 10 of this embodiment, when switching the connection from the first battery 12a to the second battery 12b, there is an overlap period during which the first switch S1a and the second switch S2a are in the off state and the third switch S1b and the fourth switch S2b are in the on state. Therefore, even when switching the connection of multiple secondary batteries to the load 14, it is possible to prevent momentary power interruptions and suppress fluctuations in the output voltage, thereby continuing to supply stable power.

[0055] (Third embodiment) Next, a third embodiment of the present invention will be described. Description of content that overlaps with the first embodiment will be omitted. In the first embodiment, a DC-AC inverter 13 is provided between the parallel connection section of the first switch array and the second switch array and the load 14 to convert direct current to alternating current, but a DC-DC converter may be provided instead of the DC-AC inverter 13. When a DC-DC converter is used, an electronic device driven by direct current is used as the load 14.

[0056] Even when a DC-DC converter is used, the first switch array and second switch array are connected in a parallel connection section, and the connection is switched in the order of the first connection period, the overlap period, and the second connection period. This prevents momentary interruptions in the voltage DCAC_IN input to the DC-DC converter and keeps it at an intermediate potential during the overlap period.

[0057] In the power supply device 10 of this embodiment, when switching the connection from the first battery 12a to the second battery 12b, there is an overlap period during which the first switch S1a and the second switch S2a are in the off state and the third switch S1b and the fourth switch S2b are in the on state. Therefore, even when switching the connection of multiple secondary batteries to the load 14, it is possible to prevent momentary power interruptions and suppress fluctuations in the output voltage, thereby continuing to supply stable power.

[0058] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0059] 10…Power supply device 11...Switch control section 12a…1st battery 12b...Second battery 13...DC-AC inverter 14...Load S1a...First switch S2a...Second switch S1b...Third switch S2b...4th switch D1a...First diode D2a: Second diode D1b...Third diode D2b: Fourth diode

Claims

1. a first battery and a second battery that are charged and discharged; a first switch array having one end connected to a first output of the first battery; a second switch array having one end connected to a second output port of the second battery; a parallel connection section to which the other end of the first switch row and the other end of the second switch row are connected; a switch control unit that controls opening and closing of the first switch row and the second switch row; the first switch array includes a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode forward-connected in parallel to the first switch, the second switch array includes a second switch having one end connected to the second output section, a fourth switch having one end connected to the other end of the second switch and the other end connected to the parallel connection section, and a second diode connected in parallel to the second switch in a forward direction, During a change from a first connection period in which the first switch and the third switch are in an on state and the second switch and the fourth switch are in an off state to a second connection period in which the first switch and the third switch are in an off state and the second switch and the fourth switch are in an on state, the switch control unit: an overlap period in which the first switch and the second switch are in an OFF state and the third switch and the fourth switch are in an ON state; The power supply device, wherein the first connection period, the overlap period, and the second connection period are continuous.

2. 2. The power supply device according to claim 1, The power supply device is characterized in that the overlap period is in the range of 5 ms to 60 ms.

3. a first battery and a second battery that are charged and discharged; a first switch array having one end connected to a first output of the first battery; a second switch array having one end connected to a second output port of the second battery; a parallel connection section to which the other end of the first switch row and the other end of the second switch row are connected; a switch control unit that controls opening and closing of the first switch row and the second switch row; the first switch array includes a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode forward-connected in parallel to the first switch, the second switch array includes a second switch having one end connected to the second output section, a fourth switch having one end connected to the other end of the second switch and the other end connected to the parallel connection section, and a second diode connected in parallel to the second switch in a forward direction, During a change from a first connection period in which the first switch and the third switch are in an on state and the second switch and the fourth switch are in an off state to a second connection period in which the first switch and the third switch are in an off state and the second switch and the fourth switch are in an on state, the switch control unit: an overlap period in which the first switch and the second switch are in an OFF state and the third switch and the fourth switch are in an ON state; the parallel connection unit is connected to a DC-AC inverter; The power supply device is characterized in that the overlap period is in the range of 0.5 to 5 periods of the output waveform from the DC-AC inverter.

4. 4. The power supply device according to claim 3, A power supply device characterized in that the peak fluctuation of the output waveform during the overlap period is 10% or less.

5. a first battery and a second battery that are charged and discharged; a first switch array having one end connected to a first output of the first battery; a second switch array having one end connected to a second output port of the second battery; a parallel connection section to which the other end of the first switch row and the other end of the second switch row are connected; a switch control unit that controls opening and closing of the first switch row and the second switch row; the first switch array includes a first switch having one end connected to the first output section, a third switch having one end connected to the other end of the first switch and the other end connected to the parallel connection section, and a first diode forward-connected in parallel to the first switch, the second switch array includes a second switch having one end connected to the second output section, a fourth switch having one end connected to the other end of the second switch and the other end connected to the parallel connection section, and a second diode connected in parallel to the second switch in a forward direction, During a change from a first connection period in which the first switch and the third switch are in an on state and the second switch and the fourth switch are in an off state to a second connection period in which the first switch and the third switch are in an off state and the second switch and the fourth switch are in an on state, the switch control unit: an overlap period in which the first switch and the second switch are in an OFF state and the third switch and the fourth switch are in an ON state; the output of the first battery is at a first potential; the output of the second battery is at a second potential; The power supply device according to claim 1, wherein the potential of the parallel connection part is an intermediate potential between the first potential and the second potential during the overlap period.

6. 6. The power supply device according to claim 1, the first switch and the second switch are field effect transistors; The power supply device, wherein the first diode and the second diode are body diodes of the first switch and the second switch.

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