Power supply device

Abstract

To provide an inexpensive power supply device capable of appropriately performing charging of a low-voltage battery even when the charging is started simultaneously with output of AC power.SOLUTION: The power supply device 1 converts DC power from a driving battery 3 mounted on a vehicle into first DC power composed of a DC voltage of a predetermined first voltage value. The power conversion device includes a converter that converts first DC power into second DC power having a DC voltage of a second voltage value capable of charging a low-voltage battery that outputs an output voltage having a voltage value smaller than a voltage value of an output voltage of a driving battery, an inverter that outputs AC power based on the first DC power, and a capacitor provided between output terminals of the converter that output the first DC power.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power supply device that charges and discharges a battery mounted on a vehicle. [Background technology]

[0002] In recent years, automobiles equipped with a motor as a driving source (such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell electric vehicles (FCEVs)) have become widespread. These automobiles are equipped with a traction battery that is configured to be charged using AC power supplied from an external source. Some of these automobiles are also configured to use AC power by using the power of the traction battery when the traction battery is not being charged (see, for example, Patent Document 1).

[0003] Patent Document 1 describes a vehicle power supply device that can supply AC power (commercial AC power in Patent Document 1) from a driving battery (an on-board power supply in Patent Document 1). This vehicle power supply device is configured to prohibit the supply of AC power from the driving battery when power consumption exceeds a predetermined value in a situation where the state of charge of the driving battery has fallen outside a predetermined range, and to allow the supply of AC power from the driving battery when power consumption is equal to or less than the predetermined value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-282837 Summary of the Invention [Problem to be solved by the invention]

[0005] In the vehicle power supply device described in Patent Document 1, when a request for AC power output is received, an inverter converts DC power from a traction battery into AC power and outputs it. However, some vehicles are configured to use power from the traction battery to charge a low-voltage battery that outputs a DC voltage with a value lower than the output voltage of the traction battery. In such a configuration, for example, if AC power output and charging of the low-voltage battery are started simultaneously, the power supply may not be fast enough, resulting in an inability to output AC power or to charge the low-voltage battery. To avoid this situation, a large-capacity capacitor could be installed, but this would increase costs. Furthermore, installing a large-capacity capacitor increases the inrush current at startup, requiring measures to be taken with components used in the vehicle power supply device, which also increases costs.

[0006] Therefore, there is a need for an inexpensive power supply device that can properly perform the output of AC power and the charging of a low-voltage battery even when the charging starts at the same time. [Means for solving the problem]

[0007] A characteristic configuration of a power supply device according to the present invention is that it includes a converter that converts DC power from a driving battery mounted on a vehicle into first DC power consisting of a DC voltage of a predetermined first voltage value, and that converts, based on the first DC power, into second DC power consisting of a DC voltage of a second voltage value that can charge a low-voltage battery that outputs an output voltage of a voltage value lower than the voltage value of the output voltage of the driving battery; an inverter that outputs AC power based on the first DC power; and a capacitor provided between output terminals of the converter that output the first DC power, and the inverter outputs the AC power in accordance with the output of the second DC power by the converter.

[0008] With this characteristic configuration, when the inverter outputs AC power, the converter outputs second DC power, so the capacitor can be charged with the first DC power (the DC voltage constituting the first DC power). Therefore, even if the output of AC power and the output of second DC power are started simultaneously, the power supply device can be brought into a state where its power supply capacity is increased, making it possible to appropriately output AC power and charge the low-voltage battery. Furthermore, as described above, since the capacitor can be charged in advance when AC power is output, a large-capacity capacitor is not required. Therefore, it is possible to construct a power supply device at low cost. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a configuration of a power supply device. [Figure 2] FIG. 10 is a diagram showing the relationship between the output of a second DC power and the output of an AC power. [Figure 3] FIG. 2 is a diagram showing the relationship between the potential difference between output terminals and the output of AC power. [Figure 4] FIG. 10 is a diagram illustrating an example in which AC power is started up by soft start. [Figure 5] 10 is a flowchart illustrating a process performed by the power supply device. DETAILED DESCRIPTION OF THE INVENTION

[0010] The power supply device according to the present invention is configured to be capable of charging a battery mounted on a vehicle and outputting AC power based on the power of the battery. The power supply device 1 of this embodiment will be described below. However, the power supply device 1 is not limited to the following embodiment and various modifications are possible without departing from the spirit of the invention.

[0011] Fig. 1 is a circuit diagram of a power supply device 1. As shown in Fig. 1, the power supply device 1 has an inverter 10, a converter 20, a capacitor 30, a reactor coil 40, and a control unit 50. Each functional unit is constructed using hardware or software, or both, with a CPU as its core component, in order to perform the processes related to charging the battery and outputting AC power described above.

[0012] The inverter 10 outputs AC power based on first DC power composed of a DC voltage having a predetermined first voltage value. When AC power is input, the inverter 10 of this embodiment converts it into DC power and outputs it, and when DC power is input, it converts it into AC power and outputs it. That is, the inverter 10 of this embodiment may receive either AC power or DC power. The AC power input to the inverter 10 refers to power composed of an AC voltage whose voltage value oscillates at a predetermined cycle. Specifically, the AC voltage oscillates at a commercial frequency (e.g., 50 Hz or 60 Hz) and corresponds to an AC voltage of 200 V (effective value) extracted from a commercial power source supplied by a single-phase three-wire system. The DC power output from the inverter 10 refers to power composed of a DC voltage that has a constant voltage value (excluding ripple voltage) relative to a reference voltage. When AC power composed of the above-mentioned 200 V AC voltage is input, the inverter 10 converts it into DC power composed of a DC voltage and outputs it.

[0013] The DC power input to the inverter 10 corresponds to the first DC power constituted by a DC voltage of the above-mentioned predetermined first voltage value, and refers to power constituted by a DC voltage whose voltage value is a constant voltage value (excluding ripple voltage) relative to a reference voltage. Specifically, it corresponds to power based on the DC voltage output from the driving battery 3 mounted on the vehicle. The AC power output from the inverter 10 refers to power constituted by an AC voltage whose voltage value oscillates at a predetermined cycle. Specifically, it corresponds to AC power constituted by an AC voltage of, for example, 100 V (effective value) that oscillates at the same frequency as the commercial frequency (e.g., 50 Hz or 60 Hz). When DC power from the driving battery 3 is input, the inverter 10 converts it into AC power constituted by an AC voltage of, for example, 100 V and outputs it.

[0014] The inverter 10 is provided with a pair of terminals 10A, 10B. The inverter 10 converts AC power into DC power and outputs the converted DC power to a converter 20 (described later) via the pair of terminals 10A, 10B. DC power from the driving battery 3 is input to the pair of terminals 10A, 10B via the converter 20.

[0015] The inverter 10 has a first leg 11 and a second leg 12. The first leg 11 and the second leg 12 are arranged in parallel with each other with respect to terminals 10A and 10B. As a result, one end 11A of the first leg 11 and one end 12A of the second leg 12 are connected to terminal 10A, and the other end 11B of the first leg 11 and the other end 12B of the second leg 12 are connected to terminal 10B.

[0016] The first leg 11 has a high-side switching element S1 and a low-side switching element S2 connected in series. In this embodiment, n-type MOS-FETs (metal-oxide-semiconductor field-effect transistors) are used for the switching elements S1 and S2. The drain terminal of the switching element S1 is connected to the end 11A, and the source terminal is connected to the drain terminal of the switching element S2. The source terminal of the switching element S2 is connected to the end 11B. The gate terminals of the switching elements S1 and S2 are connected to the control unit 50.

[0017] The second leg 12 also has a high-side switching element S3 and a low-side switching element S4 connected in series. In this embodiment, n-type MOS-FETs are used for the switching elements S3 and S4. The drain terminal of the switching element S3 is connected to the end 12A, and the source terminal is connected to the drain terminal of the switching element S4. The source terminal of the switching element S4 is connected to the end 12B. The gate terminals of the switching elements S3 and S4 are connected to the control unit 50.

[0018] A capacitor 30 is provided across terminals 10A and 10B of the inverter 10. The capacitor 30 smoothes the DC voltage converted by the inverter 10.

[0019] One terminal 40B of the reactor coil 40 is connected to a first node 11N between two switching elements (switching element S1 and switching element S2) in the first leg 11. The first node 11N between the two switching elements in the first leg 11 is a line (for example, a wiring pattern on a circuit board or a cable such as a harness) connecting the source terminal of switching element S1 and the drain terminal of switching element S2. Of course, it may also be the source terminal of switching element S1 or the drain terminal of switching element S2. The reactor coil 40 has two terminals 40A and 40B, and the terminal 40B is connected to the first node 11N.

[0020] AC power is supplied between the other terminal 40A of the reactor coil 40 and a second node 12N between the two switching elements (switching element S3 and switching element S4) in the second leg 12. The second node 12N between the two switching elements in the second leg 12 is a line (e.g., a wiring pattern on a circuit board or a cable such as a harness) connecting the source terminal of switching element S3 and the drain terminal of switching element S4. Of course, it may also be the source terminal of switching element S3 or the drain terminal of switching element S4. The terminal 40A of the reactor coil 40 is connected to one terminal of a supply unit 2 to which AC power is supplied, and the other terminal of the supply unit 2 is connected to the second node 12N.

[0021] Converter 20 can convert the DC power from inverter 10 into DC power composed of a DC voltage of a predetermined voltage value capable of charging driving battery 3, and can convert the DC power from driving battery 3 into first DC power. The DC power from inverter 10 is DC power output from terminals 10A and 10B of inverter 10. Driving battery 3 is a battery mounted on a vehicle that is charged by power supply device 1, and is charged based on the DC power output from converter 20. Driving battery 3 is charged with a DC voltage of an arbitrary voltage value, but the voltage value of the DC voltage that constitutes the DC power output from inverter 10 is an arbitrary voltage value. Converter 20 converts the voltage value of the DC voltage output from inverter 10 into the arbitrary DC voltage required to charge driving battery 3.

[0022] Furthermore, the DC power from the driving battery 3 is DC power input from the driving battery 3 via terminals 10A and 10B of the inverter 10. The first DC power is DC power configured with a DC voltage of a predetermined first voltage value, and is different from the DC power from the driving battery 3. Therefore, the converter 20 converts the voltage value of the DC voltage input from the driving battery 3 into DC power configured with a DC voltage of the predetermined first voltage value and outputs it.

[0023] The converter 20 of this embodiment includes a first conversion unit 21, a second conversion unit 22, a third conversion unit 23, and a transformer 24. In this embodiment, the transformer 24 is an isolated multi-port transformer having a primary winding 24A, a secondary winding 24B, and a tertiary winding 24C.

[0024] The first conversion unit 21 oscillates the DC power from the inverter 10 at a predetermined period and inputs the power to the primary winding 24A. The first conversion unit 21 has a third leg 211 and a fourth leg 212, which are arranged in parallel with each other with respect to the terminals 10A and 10B. Therefore, one end 211A of the third leg 211 and one end 212A of the fourth leg 212 are connected to the terminal 10A, and the other end 211B of the third leg 211 and the other end 212B of the fourth leg 212 are connected to the terminal 10B.

[0025] The third leg 211 has a high-side switching element S5 and a low-side switching element S6 connected in series. The switching elements S5 and S6 are configured as n-type MOS-FETs. The drain terminal of the switching element S5 is connected to the end 211A, and the source terminal is connected to the drain terminal of the switching element S6. The source terminal of the switching element S6 is connected to the end 211B. The gate terminals of the switching elements S5 and S6 are connected to the control unit 50.

[0026] The fourth leg 212 has a high-side switching element S7 and a low-side switching element S8 connected in series. The switching elements S7 and S8 are configured as n-type MOS-FETs. The drain terminal of the switching element S7 is connected to the end 212A, and the source terminal is connected to the drain terminal of the switching element S8. The source terminal of the switching element S8 is connected to the end 212B. The gate terminals of the switching elements S7 and S8 are connected to the control unit 50.

[0027] The primary winding 24A is provided across a third node 211N between two switching elements (switching element S5 and switching element S6) in the third leg 211 and a fourth node 212N between two switching elements (switching element S7 and switching element S8) in the fourth leg 212. In this embodiment, the winding start end of the primary winding 24A is connected to the third node 211N, and the winding end end of the primary winding 24A is connected to the fourth node 212N.

[0028] A current (alternating current) according to the turn ratio between the primary winding 24A and the secondary winding 24B flows through the secondary winding 24B, and a voltage (alternating voltage) according to the turn ratio between the primary winding 24A and the secondary winding 24B is generated. The second conversion unit 22 rectifies the voltage (alternating voltage) generated in the secondary winding 24B. The second conversion unit 22 has a fifth leg 221 and a sixth leg 222, which are arranged in parallel with each other with respect to terminals 20A and 20B of the converter 20. Therefore, one end 221A of the fifth leg 221 and one end 222A of the sixth leg 222 are connected to the terminal 20A, and the other end 221B of the fifth leg 221 and one end 222B of the sixth leg 222 are connected to the terminal 20B.

[0029] The fifth leg 221 has a high-side switching element S9 and a low-side switching element S10 connected in series. The switching elements S9 and S10 are configured as n-type MOS-FETs. The drain terminal of the switching element S9 is connected to the end 221A, and the source terminal is connected to the drain terminal of the switching element S10. The source terminal of the switching element S10 is connected to the end 221B. The gate terminals of the switching elements S9 and S10 are connected to the control unit 50.

[0030] The sixth leg 222 has a high-side switching element S11 and a low-side switching element S12 connected in series. The switching elements S11 and S12 are formed by n-type MOS-FETs. The drain terminal of the switching element S11 is connected to the end 222A, and the source terminal is connected to the drain terminal of the switching element S12. The source terminal of the switching element S12 is connected to the end 222B. The gate terminals of the switching elements S11 and S12 are connected to the control unit 50.

[0031] The secondary winding 24B described above is provided across a fifth node 221N between two switching elements (switching element S9 and switching element S10) in the fifth leg 221 and a sixth node 222N between two switching elements (switching element S11 and switching element S12) in the sixth leg 222. In this embodiment, the winding start end of the secondary winding 24B is connected to the fifth node 221N, and the winding end end of the secondary winding 24B is connected to the sixth node 222N.

[0032] A capacitor 25 is provided across terminals 20A and 20B of converter 20. Capacitor 25 smoothes the DC voltage converted by second conversion unit 22.

[0033] A current (alternating current) according to the turn ratio between the primary winding 24A and the tertiary winding 24C flows through the tertiary winding 24C, and a voltage (alternating voltage) according to the turn ratio between the primary winding 24A and the tertiary winding 24C is generated. The third conversion unit 23 converts the AC power generated in the tertiary winding 24C into second DC power composed of a DC voltage having a second voltage value (e.g., 12 V) smaller than the voltage value of the output voltage of the driving battery 3, and capable of charging a low-voltage battery 5 different from the driving battery 3. The low-voltage battery 5 is a battery mounted on the vehicle and charged by the power supply device 1, and is charged based on the DC power output from the third conversion unit 23. The low-voltage battery 5 is charged with a DC voltage of a predetermined voltage value, but the voltage value of the DC voltage constituting the DC power output from the inverter 10 is approximately the voltage value (200 V) of the AC voltage input to the inverter 10. The third conversion unit 23 steps down the voltage value of the DC voltage output from the inverter 10 to a DC voltage of a voltage value (e.g., 12 V, corresponding to the "second voltage value") required to charge the low-voltage battery 5. Therefore, the converter 20 converts the first DC power into second DC power constituted by a DC voltage of the second voltage value, based on the first DC power.

[0034] As described above, the capacitor 30 is provided across the terminals 10A and 10B of the inverter 10. The first DC power converted by the converter 20 is output to the terminals 10A and 10B of the inverter 10. Therefore, the capacitor 30 is provided across the output terminals of the converter 20 that output the first DC power.

[0035] In this embodiment, the tertiary winding 24C includes a first tertiary winding 24CA and a second tertiary winding 24CB. The first tertiary winding 24CA and the second tertiary winding 24CB are provided such that the winding end of the first tertiary winding 24CA is connected to the winding start of the second tertiary winding 24CB. A switching element S13 is provided with a drain terminal connected to the winding start of the first tertiary winding 24CA, and a switching element S14 is provided with a drain terminal connected to the winding end of the second tertiary winding 24CB. The source terminals of the switching elements S13 and S14 are connected to the terminal 20D. The gate terminals of the switching elements S13 and S14 are connected to the control unit 50. Between the source terminal and drain terminal of each of the switching elements S13 and S14, diodes D13 and D14 are provided, each having an anode terminal connected to the source terminal and a cathode terminal connected to the drain terminal.

[0036] The winding end of the first tertiary winding 24CA and the winding start of the second tertiary winding 24CB are connected to one terminal of the third reactor coil 23L. The other terminal of the third reactor coil 23L is connected to the terminal 20C. A capacitor 23C is provided across the terminals 20C and 20D. The third conversion unit 23 converts the AC power generated in the tertiary winding 24C into DC power composed of a DC voltage of a second voltage value by synchronous rectification using the switching elements S13 and S14.

[0037] The switching unit 60 switches the operation of the power supply device 1. The operation of the power supply device 1 corresponds to an operation in which the power supply device 1 charges the driving battery 3 and an operation in which the power supply device 1 outputs AC power based on the power from the driving battery 3.

[0038] In this embodiment, the power supply device 1 is switched from one of a first state and a second state to the other by the switching unit 60. The first state is a state in which the power supply device 1 charges the driving battery 3. The second state is a state in which AC power is output based on power from the driving battery 3.

[0039] 1, when switching unit 60 is operated to connect terminal 60A and terminal 60B, AC power supplied from supply unit 2 is input to inverter 10 via reactor coil 40. Although not shown, when switching unit 60 is operated to connect terminal 60A and terminal 60C, AC power generated based on DC power from driving battery 3 can be extracted from outlet 4 via reactor coil 40.

[0040] Therefore, when there is a charge request to charge the driving battery 3, the switching unit 60 switches the power supply device 1 to the first state, and when there is an output request to output AC power based on power from the driving battery 3 (when there is an output request to output DC power composed of a DC voltage of a second voltage value from the inverter 10), the switching unit 60 switches the power supply device 1 to the second state. In other words, when an operation is performed to connect terminals 60A and 60B as a charge request to charge the driving battery 3, the switching unit 60 switches the power supply device 1 to the first state, and when an operation is performed to connect terminals 60A and 60C as an output request to output DC power from the inverter 10, the switching unit 60 switches the power supply device 1 to the second state.

[0041] The control unit 50 alternately drives the switching elements S1 and S2 of the first leg 11 and the switching elements S3 and S4 of the second leg 12. This drives the switching elements of the first leg 11 and the second leg 12 of the inverter 10, converting AC power into DC power.

[0042] Furthermore, the control unit 50 alternately drives the switching element S5 of the third leg 211 and the switching element S8 of the fourth leg 212, and the switching element S6 of the third leg 211 and the switching element S7 of the fourth leg 212. This allows the DC power from the inverter 10 to be amplified and input to the primary winding 24A, and makes it possible to generate AC power in the secondary winding 24B according to the turns ratio between the primary winding 24A and the secondary winding 24B.

[0043] Furthermore, the control unit 50 alternately drives the switching element S9 of the fifth leg 221 and the switching element S12 of the sixth leg 222, and the switching element S10 of the fifth leg 221 and the switching element S11 of the sixth leg 222. This converts the AC voltage generated in the secondary winding 24B into a DC voltage. The driving battery 3 is charged by this DC voltage.

[0044] Furthermore, when AC power is output from the outlet 4 using the power charged in the driving battery 3, the control unit 50 alternately drives the switching element S9 of the fifth leg 221 and the switching element S12 of the sixth leg 222, and the switching element S10 of the fifth leg 221 and the switching element S11 of the sixth leg 222. This causes the DC power from the driving battery 3 to be amplified and input to the secondary winding 24B, making it possible to generate AC power in the primary winding 24A according to the turns ratio between the primary winding 24A and the secondary winding 24B.

[0045] The control unit 50 alternately drives the switching element S5 of the third leg 211 and the switching element S8 of the fourth leg 212, and the switching element S6 of the third leg 211 and the switching element S7 of the fourth leg 212. This converts the AC voltage generated in the primary winding 24A into a DC voltage. This DC voltage is a voltage obtained by transforming the output voltage of the driving battery 3 in accordance with the turns ratio between the primary winding 24A and the secondary winding 24B.

[0046] Furthermore, the control unit 50 alternately drives the switching elements S1 and S2 of the first leg 11 and the switching elements S3 and S4 of the second leg 12. This drives the switching elements of the first leg 11 and the second leg 12, converting the DC voltage from the driving battery 3 into AC power that is different from the AC power input to the inverter 10. That is, when charging the driving battery 3, an AC voltage of 200 V is applied to the inverter 10, but it is possible to output an AC voltage of 100 V, for example, from the power (DC power) charged in the driving battery 3.

[0047] By setting the turns ratio between the primary winding 24A and the secondary winding 24B in accordance with the ratio between the voltage value of the AC voltage applied to the primary winding 24A and the voltage value of the DC voltage used to charge the driving battery 3, DC power suitable for charging the driving battery 3 can be generated at terminals 20A and 20B, making it possible to charge the driving battery 3.

[0048] As described above, the third conversion unit 23 is driven by synchronous rectification. For example, the switching elements S13 and S14 are controlled so that one cycle of the synchronous rectification control sequentially includes a period in which the switching elements S13 and S14 are in a closed state, a period in which one of the switching elements S13 and S14 is in a closed state, a period in which the switching elements S13 and S14 are in a closed state, and a period in which the other of the switching elements S13 and S14 is in a closed state. This converts the AC voltage generated in the tertiary winding 24C into a DC voltage. The low-voltage battery 5 is charged by this DC voltage.

[0049] When AC power is output from the outlet 4, the control unit 50 alternately drives the switching elements S1 and S2 of the first leg 11 at a predetermined frequency (a frequency higher than the grid frequency) and alternately drives the switching elements S3 and S4 of the second leg 12 at the same frequency (e.g., 50 Hz or 60 Hz) as the frequency of the AC power output from the outlet 4. That is, the switching elements S3 and S4 of the second leg 12 are driven at a frequency lower than the frequency at which the switching elements S1 and S2 of the first leg 11 are driven, depending on the frequency of the AC power output from the outlet 4. This allows the power supply device 1 to convert DC power to AC power based on the switching elements S1 and S2 of the first leg 11 and the switching elements S3 and S4 of the second leg 12, and to output an AC voltage of, for example, 100 V from the outlet 4.

[0050] As described above, the converter 20 converts the DC power from the driving battery 3 into first DC power, and the inverter 10 outputs AC power based on the first DC power. Furthermore, when the converter 20 converts the DC power into the first DC power, the capacitor 30 is charged by the DC voltage that constitutes the first DC power. For example, if AC power is output from the outlet 4 and the low-voltage battery 5 is charged simultaneously before charging of the capacitor 30 is completed, the voltage across the terminals of the capacitor 30 (DC link voltage) may suddenly drop, which may prevent AC power from being output from the outlet 4 or the low-voltage battery 5 from being charged.

[0051] Therefore, inverter 10 is configured to output AC power in response to the output of the second DC power by converter 20. That is, as shown in Fig. 2, charging of capacitor 30 is started in response to startup of power supply device 1 (#1), and even when power supply device 1 is requested to output AC power from outlet 4 (#2), inverter 10 does not immediately output AC power from outlet 4, but rather, converter 20 outputs second DC power composed of a DC voltage of a second voltage value capable of charging low-voltage battery 5 (#3), and then outputs AC power from outlet 4 (#4). This allows AC power to be output after capacitor 30 is sufficiently charged (after sufficient charge is stored in capacitor 30), making it possible to avoid situations where AC power cannot be output from outlet 4 or where low-voltage battery 5 cannot be charged.

[0052] Alternatively, the converter 20 may be configured to output second DC power consisting of a DC voltage of a second voltage value sufficient to charge the low-voltage battery 5, and then output AC power from the outlet 4. Alternatively, the converter 20 may be configured to have the detector 65 detect a potential difference between the output terminals of the converter 20, and the inverter 10 may output AC power when the potential difference detected by the detector 65 is equal to or greater than a predetermined value. That is, as shown in FIG. 3 , when charging of the capacitor 30 is started in response to startup of the power supply device 1 (#5), and a request is made to the power supply device 1 to output AC power from the outlet 4 (#6), even if the converter 20 has not yet output second DC power consisting of a DC voltage of a second voltage value sufficient to charge the low-voltage battery 5 (#7), if the voltage across the terminals of the capacitor 30 detected by the detector 65 is equal to or greater than a predetermined value (#8), AC power may be output from the outlet 4 (#9). This allows AC power to be output after the capacitor 30 is sufficiently charged (after a sufficient charge has been stored in the capacitor 30), making it possible to avoid situations where AC power cannot be output from the outlet 4 or the low-voltage battery 5 cannot be charged.

[0053] As described above, a current (alternating current) corresponding to the turns ratio between the primary winding 24A and the secondary winding 24B flows through the secondary winding 24B, and a voltage (alternating voltage) corresponding to the turns ratio between the primary winding 24A and the secondary winding 24B is generated. The second conversion unit 22 rectifies the voltage (alternating voltage) generated in the secondary winding 24B, thereby enabling charging of the driving battery 3. Meanwhile, the primary winding 24A and the secondary winding 24B are also used to convert the first DC power. Therefore, the inverter 10 can be configured to output AC power when the potential difference between the output terminals of the converter 20 reaches a voltage value corresponding to the turns ratio between the primary winding 24A and the secondary winding 24B. When the potential difference between the output terminals of the converter 20 reaches a voltage value corresponding to the turns ratio between the primary winding 24A and the secondary winding 24B, the voltage between the terminals of the capacitor 30 increases and the capacitor 30 is fully charged. Therefore, it is possible to avoid situations where AC power cannot be output from the outlet 4 or the low-voltage battery 5 cannot be charged.

[0054] Furthermore, it is also preferable to configure the inverter 10 so that the AC voltage constituting the AC power is started up using a soft start. Starting up the AC voltage using a soft start means, for example, outputting the AC voltage so that the amplitude value gradually reaches a desired value over tens to hundreds of milliseconds. As shown in FIG. 4, by configuring the output of AC power so that the amplitude value gradually increases, fluctuations in the voltage between the terminals of the capacitor 30 can be suppressed, thereby making it possible to avoid situations such as being unable to output AC power from the outlet 4 or being unable to charge the low-voltage battery 5.

[0055] Next, the process performed by the power supply device 1 when it outputs AC power will be described with reference to the flowchart in Figure 5. Before AC power is output from the outlet 4, charging of the capacitor 30 with a DC voltage of a first voltage value begins (step #10). The process is suspended until an output request is received from the outlet 4 (step #11: No).

[0056] If there is an output request from the outlet 4 (step #11: Yes), and the converter 20 has started charging the low-voltage battery 5 (step #12: Yes), the output of AC power from the outlet 4 begins (step #13).

[0057] In step #12, even if the converter 20 has not started charging the low-voltage battery 5 (step #12: No), if the terminal voltage of the capacitor 30 is equal to or greater than a predetermined value (step #14: Yes), the converter 20 starts outputting AC power from the outlet 4 (step #13).

[0058] In step #12, if the converter 20 has not started charging the low-voltage battery 5 (step #12: No) and the terminal voltage of the capacitor 30 is not equal to or greater than a predetermined value (step #14: No), the process returns to step #12 and continues. The power supply device 1 is driven based on this flowchart. Of course, the flowchart in FIG. 5 is an example and can be modified as appropriate.

[0059] Other Embodiments Next, other embodiments of the power supply device 1 will be described.

[0060] In the above embodiment, the switching elements of the inverter 10 and the converter 20 are described as n-type MOS-FETs, but the switching elements may be p-type MOS-FETs or may be switching elements other than FETs (for example, IGBTs or bipolar transistors).

[0061] In the above embodiment, the power supply device 1 is described as being capable of charging the driving battery 3 with AC power supplied from the supply unit 2, but the power supply device 1 can also be configured not to charge the driving battery 3.

[0062] In the above embodiment, the inverter 10 has been described as outputting an AC voltage constituting AC power in a soft start so that the amplitude value gradually reaches a desired value over a period of tens to hundreds of milliseconds. However, when the AC voltage constituting AC power is started up in a soft start, it is also possible to configure the AC voltage to start up in less than tens of milliseconds or over a period of time longer than hundreds of milliseconds.

[0063] In the above embodiment, the inverter 10 is described as outputting AC power in response to the output of the second DC power by the converter 20. Whether the converter 20 is outputting the second DC power can also be determined based on the result of detecting the voltage across the terminals of the capacitor 23C. Furthermore, it can also be determined based on the current flowing through the load connected to the low-voltage battery 5.

[0064] In the above embodiment, the third conversion unit 23 has been described as converting the AC power generated in the tertiary winding 24C into DC power constituted by a DC voltage of the second voltage value using switching elements S13 and S14. However, the configuration of the third conversion unit 23 is not limited to the configuration shown in Fig. 1. For example, the AC power generated in the tertiary winding 24C may be rectified and the rectified DC power may be converted into DC power of a desired voltage value using a switching regulator (e.g., a step-down DC / DC converter). Alternatively, the AC power generated in the tertiary winding 24C may be rectified and the rectified DC power may be converted into DC power of a desired voltage value using a so-called three-terminal regulator. Of course, the third conversion unit 23 may also be configured using circuit configurations other than these.

[0065] [Summary of the above embodiment] The power supply device 1 described above will now be outlined.

[0066] (1) The power supply device 1 includes a converter 20 that converts DC power from a driving battery 3 mounted on a vehicle into first DC power consisting of a DC voltage of a predetermined first voltage value, and also converts the first DC power into second DC power consisting of a DC voltage of a second voltage value that can charge a low-voltage battery 5 that outputs an output voltage of a voltage value smaller than the voltage value of the output voltage of the driving battery 3, an inverter 10 that outputs AC power based on the first DC power, and a capacitor 30 that is provided between output terminals of the converter 20 that output the first DC power, and the inverter 10 outputs AC power in accordance with the output of the second DC power by the converter 20.

[0067] According to this configuration, when the inverter 10 outputs AC power, the converter 20 outputs the second DC power, so that the capacitor 30 can be charged by the first DC power (the DC voltage constituting the first DC power). Therefore, even if the output of the second DC power starts simultaneously with the output of the AC power, the power supply device 1 can be brought into a state where its power supply capacity is increased, so that it is possible to appropriately output AC power and charge the low-voltage battery 5. Furthermore, as described above, since the capacitor 30 can be charged in advance when AC power is output, a large-capacity capacitor is not required. Therefore, the power supply device 1 can be constructed inexpensively.

[0068] (2) In the power supply device 1 described in (1), it is preferable to further include a detection unit 65 that detects a potential difference between the output terminals, and the inverter 10 outputs AC power when the potential difference is equal to or greater than a predetermined value that has been set in advance.

[0069] According to this configuration, when AC power is output, the potential difference between both terminals of the capacitor 30 is set to a predetermined value or more, thereby increasing the power supply capacity of the power supply device 1, thereby making it possible to appropriately output AC power and charge the low-voltage battery 5.

[0070] (3) In the power supply device 1 described in (1) or (2), the converter 20 preferably has a transformer 24 including a primary winding 24A and a secondary winding 24B used for converting the first DC power, and the inverter 10 preferably outputs AC power when the potential difference between the output terminals reaches a voltage value corresponding to the turns ratio of the primary winding 24A and the secondary winding 24B.

[0071] According to this configuration, the potential difference between the terminals of the capacitor 30 has a voltage value according to the turn ratio between the primary winding 24A and the secondary winding 24B, thereby enhancing the power supply capacity of the power supply device 1. Therefore, it becomes possible to appropriately output AC power and charge the low-voltage battery 5.

[0072] (4) In the power supply device 1 described in (1) or (2), it is preferable that the inverter 10 starts up the AC voltage constituting the AC power by soft start.

[0073] According to this configuration, the current consumption related to the AC power can be gradually increased, which prevents excessive current consumption and allows the AC power to be output appropriately and the low-voltage battery 5 to be charged appropriately. [Industrial Applicability]

[0074] The technology disclosed herein can be used in a power supply device that charges and discharges a battery mounted on a vehicle. [Explanation of symbols]

[0075] 1: Power supply unit, 3: Running battery, 5: Low voltage battery, 10: Inverter, 20: Converter, 24: Transformer, 24A: Primary winding, 24B: Secondary winding, 30: Capacitor, 65: Detector

Claims

1. a converter that converts DC power from a driving battery mounted on the vehicle into first DC power composed of a DC voltage of a predetermined first voltage value, and also converts, based on the first DC power, into second DC power composed of a DC voltage of a second voltage value that can charge a low-voltage battery that outputs an output voltage of a voltage value lower than the output voltage of the driving battery; an inverter that outputs AC power based on the first DC power; a capacitor provided between output terminals of the converter that output the first DC power, The inverter is a power supply device that outputs the AC power in response to the output of the second DC power by the converter.

2. a detection unit that detects a potential difference between the output terminals, The power supply device according to claim 1 , wherein the inverter outputs the AC power when the potential difference is equal to or greater than a predetermined value.

3. the converter has a transformer including a primary winding and a secondary winding used for converting the first DC power, 3. The power supply device according to claim 1, wherein the inverter outputs the AC power when a potential difference between the output terminals reaches a voltage value according to a turns ratio between the primary winding and the secondary winding.

4. 3. The power supply device according to claim 1, wherein the inverter starts up the AC voltage constituting the AC power in a soft start.

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