Vehicle power supply unit

Abstract

To provide a technique capable of preventing generation of inrush current upon starting power supply.SOLUTION: Each of a plurality of PCUs 40 comprises a boost converter 41 and a multi-phase inverter 47. The boost converter 41 comprises: a first switching element 43 with one end connected to a second positive-electrode power line 14; a second switching element 44 with one end connected to the first switching element 43 and the other end connected to a second negative-electrode power line 15; and a reactor 42 with one end connected between the first switching element 43 and the second switching element 44 and the other end is opened. An output terminal in at least one PCU 40 among the plurality of PCUs 40 is connected to a first positive electrode power line 12 via a diode 11 connected to the other terminal of the reactor 42.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a power supply device for a vehicle. [Background technology]

[0002] Patent Document 1 discloses a battery system in which a plurality of assembled batteries are connected to a power conversion device (hereinafter referred to as a PCU (Power Control Unit)). In this technology, the voltages of the assembled batteries are equalized based on the voltages of the assembled batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-103804 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when multiple PCUs with different voltage packs are connected in parallel, it is possible that an inrush current will flow from the higher voltage PCU to the lower voltage PCU when the power is turned on. This inrush current could cause system malfunction or failure.

[0005] An object of the present disclosure is to provide a technique capable of preventing the occurrence of inrush current when a power supply is started up. [Means for solving the problem]

[0006] A first aspect relates to a vehicle power supply device. The vehicle power supply device includes a first capacitor, a plurality of PCUs connected in parallel to the first capacitor, and a power storage device provided on the input side of each of the plurality of PCUs via a first relay. An output terminal of each of the plurality of PCUs is connected to a first positive power line connected to one end of the first capacitor and a first negative power line connected to the other end of the first capacitor. Each of the plurality of PCUs includes a boost converter, a multi-phase inverter, second positive power lines and second negative power lines connecting the boost converter and the multi-phase inverter, a second capacitor and a discharge resistor connected in parallel between the second positive power line and the second negative power line, and a second relay connected to the second positive power line and the second negative power line, respectively, and connected to the first positive power line and the first negative power line, respectively. The boost converter includes a first switching element having one end connected to the second positive power line, a second switching element having one end connected to the first switching element and the other end connected to the second negative power line, and a reactor having one end connected between the first switching element and the second switching element and the other end open. An output terminal of at least one PCU among the multiple PCUs is connected to the first positive power line via a diode connected to the other end of the reactor. [Effects of the Invention]

[0007] According to the present disclosure, the vehicle power supply device has a feature in which the output terminal of at least one of the PCUs is connected to the first positive power line via a diode connected to the other end of the reactor, thereby equalizing the voltages of the PCUs and preventing inrush currents at power-on. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating an example of the configuration of a vehicle power supply device according to an embodiment; [Figure 2] 3A and 3B are diagrams illustrating an example of operation of the vehicle power supply device according to the embodiment. [Figure 3] 3A and 3B are diagrams illustrating an example of operation of the vehicle power supply device according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle power supply device according to an embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0010] Embodiment 1. Example of vehicle power supply configuration FIG. 1 is a diagram showing an example of the configuration of a vehicle power supply device 1 according to an embodiment. The vehicle power supply device 1 is mounted on a vehicle. The vehicle on which the vehicle power supply device 1 is mounted is an electric vehicle equipped with a drive motor driven by a battery (i.e., a power storage device 20). The vehicle may be a manually driven vehicle or an automatically driven vehicle.

[0011] As shown in Fig. 1, a vehicle power supply device 1 mounted on a vehicle is connected to, for example, an external device such as a PCS (Power Conditioning System). A PCS is a device that has the function of converting power obtained from a commercial power source or the like into power usable by a vehicle or the like. Vehicle power supply device 1 charges and discharges energy stored in a power storage device 20 via the PCS.

[0012] The vehicle power supply device 1 is configured by connecting multiple power supply units 1A, 1B, ..., 1N in parallel, each of which is made up of a power storage device 20, a first relay 30, and a PCU 40. The vehicle power supply device 1 also includes a first capacitor 10 connected to a first positive power line 12 and a first negative power line 13 on the output side of the branch point of the multiple PCUs 40.

[0013] The power storage device 20 is a device in which a plurality of assembled batteries, each of which is formed by connecting a plurality of cells in series, are connected in parallel.

[0014] The first relay 30 is configured as an SMR (system main relay). The first relay 30 is connected to the power storage device 20 and the PCU 40. The first relay 30 may also be connected to, for example, a control device not shown in FIG. 1 , and the ON / OFF switching of the first relay 30 may be controlled by the control device. This makes it possible to connect or disconnect the power storage device 20 and the PCU 40.

[0015] The PCU 40 is a power conversion device that converts power between the power storage device 20 and an external device (such as a PCS) to which the vehicle power supply device 1 is connected. The PCU 40 includes a boost converter 41, a second capacitor 45, a discharge resistor 46, a polyphase inverter 47, and a second relay 48. The PCU 40 may be a bidirectional device that converts power between the power storage device 20 and the external device.

[0016] The boost converter 41 and the multi-phase inverter 47 are connected to the second positive power line 14 and the second negative power line 15, respectively. The second capacitor 45 and the discharge resistor 46 are connected in parallel between the second positive power line 14 and the second negative power line 15. The second capacitor 45 smoothes the DC voltage and charges and discharges energy, and the discharge resistor 46 discharges the energy stored in the second capacitor 45. The multi-phase inverter 47 converts the voltage of the energy stored in the second capacitor 45 to a desired voltage. The boost converter 41 converts the voltage to a higher voltage than the input voltage.

[0017] The second relay 48 has one end connected to the first positive power line 12 and the first negative power line 13, and the other end connected to the second positive power line 14 and the second negative power line 15. By controlling the ON / OFF switching of the second relay 48, the charging and discharging of the energy stored in the second capacitor 45 is controlled. Like the first relay 30, the second relay 48 may be connected to a control device, and the ON / OFF switching of the second relay 48 may be controlled by the control device.

[0018] Discharge resistor 46 is provided as a safety measure to prevent the energy stored in second capacitor 45 from being discharged to the body even if the power plug on the vehicle power supply device 1 side that connects to the external device is touched after the connection with the external device is cut off. Also, polyphase inverter 47 shown in Fig. 1 is an example of a three-level inverter, and is composed of three inverters: a first single-phase inverter, a second single-phase inverter, and a third single-phase inverter.

[0019] The boost converter 41 further includes a reactor 42, a first switching element 43, and a second switching element 44. The first switching element 43 and the second switching element 44 are connected in parallel, with the end of the first switching element 43 connected to the second positive power line 14 and the end of the second switching element 44 connected to the second negative power line 15. The reactor 42 is connected to a connection point between the first switching element 43 and the second switching element 44, and is connected to the second negative power line 15 via a third capacitor 49.

[0020] The reactor 42 serves to remove at least harmonic components such as the power supply frequency. The first switching element 43 and the second switching element 44 serve to adjust the output voltage of the PCU 40 to a predetermined voltage (i.e., a boosted voltage). Specifically, the output voltage of the PCU 40 is adjusted to the predetermined voltage by controlling the time and number of times that each of the first switching element 43 and the second switching element 44 is switched ON / OFF. The first switching element 43 and the second switching element 44 may be connected to a control device, similar to the first relay 30 and the second relay 48, and the ON / OFF switching of the first switching element 43 and the second switching element 44 may be controlled by the control device.

[0021] The vehicle power supply device 1 further includes at least one diode 11 on the output side of the PCU 40 (the PCS side shown in FIG. 1). Of the multiple PCUs 40, the output terminal of the PCU 40 of the power supply unit 1A is connected to the first positive power line 12 via the diode 11 connected to the other end of the reactor 42. The output terminals of the PCUs 40 of the other power supply units 1B, ..., 1N are open.

[0022] 2. Example of vehicle power supply operation 2 and 3 are diagrams illustrating an example of operation of the vehicle power supply device 1 according to the embodiment. FIG. 2 illustrates the first half of the example of operation of the vehicle power supply device 1, and FIG. 3 illustrates the second half of the example of operation of the vehicle power supply device 1. In STEP 1 shown in FIG. 2, an operation is performed to switch ON the first relay 30 in the power supply unit 1A among the multiple power supply units 1A, 1B, . . . , 1N. In this state, STEP 1 shown in FIG. 2 illustrates the voltage states when energy is stored in each second capacitor 45 and first capacitor 10. The voltage charged in the second capacitor 45 (voltages V1, V2, . . . , Vn shown in FIG. 2) corresponds to the voltage of the power storage device 20 corresponding to each PCU 40. At this point, the voltage Vp of the first capacitor 10 is maintained at 0 V.

[0023] 2, the multi-phase inverter 47 in the power supply unit 1A boosts the voltage of the second capacitor 45 included in the PCU 40 of the power supply unit 1A to a predetermined voltage. In the example of STEP 2 shown in Fig. 2, only the voltage V1 of the second capacitor 45 included in the power supply unit 1A is boosted, and the voltages V2,...,Vn of the second capacitors 45 of the other power supply units 1B,...,1N are maintained at the voltage states in STEP 1. At this point in time, the voltage Vp of the first capacitor 10 is maintained at 0V.

[0024] 3, an operation is performed to switch ON the second relays 48 of the other power supply units 1B, . . . , 1N other than the power supply unit 1A. Furthermore, an operation is repeatedly performed to alternately switch ON and OFF the first switching element 43 of the boost converter 41 in the power supply unit 1A. In this state, STEP 3 shown in FIG. 3 shows the voltage states when energy is stored in each of the second capacitors 45 and the first capacitor 10.

[0025] More specifically, the voltage V1 of the second capacitor 45 is connected to the voltage Vp of the first capacitor 10 and the voltages V2,...,Vn of the second capacitors 45 via the diode 11. At this time, the voltage V1 of the second capacitor 45 is maintained at the voltage boosted in STEP 2 by the multi-phase inverter 47 and the boost converter 41. Furthermore, the voltages V2,...,Vn of the second capacitors 45 are transitioned to the same voltage as the voltage V1. Furthermore, the voltage Vp of the first capacitor 10 is also transitioned to the same voltage as the voltage V1. This makes it possible to make the voltages of all the second capacitors 45 and the first capacitors 10 the same voltage.

[0026] Next, in STEP 4 shown in Fig. 3, an operation is performed to switch OFF the first switching element 43 of the boost converter 41 in the power supply unit 1A, and an operation is performed to stop the boost of the multi-phase inverter 47 in the power supply unit 1A. Furthermore, an operation is performed to switch ON the second relay 48 included in the power supply unit 1A. In this state, STEP 4 shown in Fig. 3 shows the voltage states when energy is stored in the second capacitor 45 and the first capacitor 10.

[0027] More specifically, in STEP 3, the voltage Vp of the first capacitor 10 and the voltages V2, . . . , Vn of the second capacitor 45 were in a charged state due to the voltage V1 of the second capacitor 45. However, in STEP 4, these voltages are discharged, causing all voltages to become slightly lower than the voltage states in STEP 3, and then all voltages are maintained at the same voltage state. This state is known as the completion state of power supply startup. For example, when the control device determines that the power supply has been successfully started, the vehicle power supply device 1 switches from the startup mode to the operating mode.

[0028] As described above, when the vehicle power supply device 1 according to the embodiment is started up, the operations of steps 1 to 4 shown in Figures 2 and 3 are performed. This equalizes the voltages of the multiple PCUs 40, preventing the occurrence of inrush current. Note that the operations of steps 1 to 4 described above may be performed based on commands from a control device.

[0029] Other embodiments In the vehicle power supply device 1 according to the embodiment, the first capacitor 10 is configured to be included in the vehicle power supply device 1, but the first capacitor 10 does not have to be included in the configuration of the vehicle power supply device 1. For example, the first capacitor 10 may be configured to be included in an external device (e.g., a PCS). This provides the same effects as the vehicle power supply device 1 according to the embodiment described above. [Explanation of symbols]

[0030] REFERENCE SIGNS LIST 1...vehicle power supply device, 10...first capacitor, 11...diode, 12...first positive power line, 13...first negative power line, 14...second positive power line, 15...second negative power line, 20...electricity storage device, 30...first relay, 40...PCU, 41...boost converter, 42...reactor, 43...first switching element, 44...second switching element, 45...second capacitor, 46...discharge resistor, 47...multi-phase inverter, 48...second relay, 49...third capacitor

Claims

[Claim 1] A vehicle power supply device having a control device, A first capacitor; a plurality of PCUs connected in parallel to the first capacitor; a plurality of power storage devices provided on the input sides of the plurality of PCUs; a first relay provided between each PCU and each power storage device and controlled to be opened and closed by the control device; Equipped with an output terminal of each of the plurality of PCUs is connected to a first positive power line connected to one end of the first capacitor and a first negative power line connected to the other end of the first capacitor; Each of the plurality of PCUs a boost converter; a multi-phase inverter controlled by the control device; a second positive power line and a second negative power line connecting the boost converter and the multi-phase inverter; a second capacitor and a discharge resistor connected in parallel between the second positive power line and the second negative power line; a second relay connected to the second positive power line and the second negative power line, and connected to the first positive power line and the first negative power line, respectively, and controlled to be opened and closed by the control device; Including, The boost converter is a first switching element having one end connected to the second positive power line and controlled to be opened or closed by the control device; a second switching element having one end connected to the other end of the first switching element and the other end connected to the second negative power line; a reactor having one end connected between the first switching element and the second switching element and the other end open; Including, an output terminal of at least one PCU among the plurality of PCUs is connected to the first positive power line via a diode connected to the other end of the reactor; The control device, when power is turned on, closing the first relay so that the voltage of the second capacitor is charged to the voltage of the power storage device; controlling the multi-phase inverter provided in the at least one PCU so that the voltage of the second capacitor is boosted to a predetermined voltage; and closing the second relay while opening and closing the first switching element of the boost converter provided in the at least one PCU so that the voltages of the first capacitor and the second capacitor become the same voltage. A vehicle power supply device characterized by:

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