US-20260124924-A1 - POWER SUPPLY SYSTEM AND CONTROL PROGRAM

US20260124924A1US 20260124924 A1US20260124924 A1US 20260124924A1US-20260124924-A1

Abstract

A power supply system includes a plurality of main batteries that are connected in parallel to a power supply bus, and at least a single conversion circuit that converts power input from the main batteries to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair. A positive electrode and a negative electrode of the main battery are respectively connected to the primary-side terminal pair of the conversion circuit. The secondary-side terminal pair of the conversion circuit are connectable in series to the main battery. The secondary-side terminal pair of the conversion circuit are connectable in parallel to a low-voltage load.

Inventors

Taisuke Kurachi
Takumi Shimizu
Takahiro Iwamura
Shunichi Kubo
Mitsutaka Ito

Assignees

DENSO CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251230
Priority Date: 20230630

Claims (19)

1 . A power supply system comprising: a plurality of main batteries that are connected in parallel to a power supply bus; and at least a single conversion circuit that converts power input from the main batteries to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair, wherein: a positive electrode and a negative electrode of the main battery are respectively connected to the primary-side terminal pair of the conversion circuit; the secondary-side terminal pair of the conversion circuit are connectable in series to the main battery; and the secondary-side terminal pair of the conversion circuit are connectable in parallel to a low-voltage load.
2 . The power supply system according to claim 1 , further comprising: a series path that connects the secondary-side terminal pair of the conversion circuit to the main battery in series; a first relay that disconnects and connects the series path; a bus connection path that connects a secondary-side terminal that, of the secondary-side terminal pair of the conversion circuit, is on a side opposite the main battery, to the power supply bus; a second relay that disconnects and connects the bus connection path; a negative-electrode-side path and a positive-electrode-side path that connect the secondary-side terminal pair of the conversion circuit to the low-voltage load in parallel; a third relay that disconnects and connects the negative-electrode-side path; and a fourth relay that disconnects and connects the positive-electrode-side path.
3 . The power supply system according to claim 2 , further comprising: a control unit that connects the first relay and the second relay and disconnects the third relay and the fourth relay in response to executing a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus, and that disconnects the first relay and the second relay and connects the third relay and the fourth relay in response to executing a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load.
4 . The power supply system according to claim 3 , wherein: the control unit disconnects the third relay and the fourth relay and then connects the first relay and the second relay in response to executing the voltage adjustment mode, and disconnects the first relay and the second relay and then connects the third relay and the fourth relay in response to executing the low-voltage power supply mode.
5 . The power supply system according to claim 3 , further comprising: a step-down converter that is connected to the power supply bus, steps down voltage of power input from the power supply bus, and outputs the stepped-down power to the low-voltage load, wherein the control unit performs switching from the low-voltage power supply mode to the voltage adjustment mode after starting the step-down converter, and stops the step-down converter after performing switching from the voltage adjustment mode to the low-voltage power supply mode.
6 . The power supply system according to claim 1 , wherein: the power supply system is mounted in a vehicle and includes a state determination unit that determines a state of the vehicle, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the state determination unit determining that the vehicle is in a mode in which the plurality of main batteries are connected in parallel to the power supply bus and charged or discharged, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the state determination unit determining that the vehicle is in a mode in which the plurality of main batteries are not connected in parallel to the power supply bus or a mode in which the plurality of main batteries are not charged or discharged.
7 . The power supply system according to claim 1 , wherein: a low-voltage power supply is connected to the low-voltage load; and the power supply system includes an abnormality determination unit that determines whether the low-voltage power supply is abnormal, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the abnormality determination unit determining that the low-voltage power supply is not abnormal, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the abnormality determination unit determining that the low-voltage power supply is abnormal.
8 . The power supply system according to claim 1 , wherein: a high-voltage load is connected to the power supply bus; and the power supply system includes a power calculation unit that calculates a high-voltage power request value that is power requested by the high-voltage load, and a low-voltage power request value that is power requested by the low-voltage load, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the high-voltage power request value calculated by the power calculation unit being greater than a first prescribed value or in response to the low-voltage power request value calculated by the power calculation unit being less than a second prescribed value, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the high-voltage power request value calculated by the power calculation unit being less than the first prescribed value or in response to the low-voltage power request value calculated by the power calculation unit being greater than the second prescribed value.
9 . The power supply system according to claim 1 , wherein: the conversion circuit includes a secondary-side voltage sensor that detects a voltage across the secondary-side terminal pair; and the power supply system includes a control unit that controls an output voltage of the conversion circuit based on the voltage detected by the secondary-side voltage sensor during execution of a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus, and controls the output voltage of the conversion circuit based on the voltage detected by the secondary-side voltage sensor during execution of a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load.
10 . The power supply system according to claim 1 , wherein: a high-voltage load is connected to the main battery to which the secondary-side terminal pair of the conversion circuit are connectable in series, or a charging apparatus is connected to the main battery to which the secondary-side terminal pair of the conversion circuit is not able to be connected in series.
11 . The power supply system according to claim 1 , further comprising: a predetermined path that connects a primary-side terminal that, of the primary-side terminal pair of the conversion circuit, is connected between the main battery and the secondary-side terminal pair, to the power supply bus; and a predetermined relay that disconnects and connects the predetermined path.
12 . The power supply system according to claim 4 , further comprising: a step-down converter that is connected to the power supply bus, steps down voltage of power input from the power supply bus, and outputs the stepped-down power to the low-voltage load, wherein the control unit performs switching from the low-voltage power supply mode to the voltage adjustment mode after starting the step-down converter, and stops the step-down converter after performing switching from the voltage adjustment mode to the low-voltage power supply mode.
13 . The power supply system according to claim 2 , wherein: the power supply system is mounted in a vehicle and includes a state determination unit that determines a state of the vehicle, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the state determination unit determining that the vehicle is in a mode in which the plurality of main batteries are connected in parallel to the power supply bus and charged or discharged, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the state determination unit determining that the vehicle is in a mode in which the plurality of main batteries are not connected in parallel to the power supply bus or a mode in which the plurality of main batteries are not charged or discharged.
14 . The power supply system according to claim 2 , wherein: a low-voltage power supply is connected to the low-voltage load; and the power supply system includes an abnormality determination unit that determines whether the low-voltage power supply is abnormal, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the abnormality determination unit determining that the low-voltage power supply is not abnormal, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the abnormality determination unit determining that the low-voltage power supply is abnormal.
15 . The power supply system according to claim 2 , wherein: a high-voltage load is connected to the power supply bus; and the power supply system includes a power calculation unit that calculates a high-voltage power request value that is power requested by the high-voltage load, and a low-voltage power request value that is power requested by the low-voltage load, and a control unit that executes a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus in response to the high-voltage power request value calculated by the power calculation unit being greater than a first prescribed value or in response to the low-voltage power request value calculated by the power calculation unit being less than a second prescribed value, and executes a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load in response to the high-voltage power request value calculated by the power calculation unit being less than the first prescribed value or in response to the low-voltage power request value calculated by the power calculation unit being greater than the second prescribed value.
16 . The power supply system according to claim 2 , wherein: the conversion circuit includes a secondary-side voltage sensor that detects a voltage across the secondary-side terminal pair; and the power supply system includes a control unit that controls an output voltage of the conversion circuit based on the voltage detected by the secondary-side voltage sensor during execution of a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus, and controls the output voltage of the conversion circuit based on the voltage detected by the secondary-side voltage sensor during execution of a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load.
17 . The power supply system according to claim 2 , wherein: a high-voltage load is connected to the main battery to which the secondary-side terminal pair of the conversion circuit are connectable in series, or a charging apparatus is connected to the main battery to which the secondary-side terminal pair of the conversion circuit is not able to be connected in series.
18 . The power supply system according to claim 2 , further comprising: a predetermined path that connects a primary-side terminal that, of the primary-side terminal pair of the conversion circuit, is connected between the main battery and the secondary-side terminal pair, to the power supply bus; and a predetermined relay that disconnects and connects the predetermined path.
19 . A non-transitory computer-readable storage medium storing therein a control program applicable to a power supply system that includes: a plurality of main batteries connected in parallel to a power supply bus; at least a single conversion circuit that converts power input from the main batteries to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair; a series path that connects the secondary-side terminal pair of the conversion circuit to the main battery in series; a first relay that disconnects and connects the series path; a bus connection path that connects a secondary-side terminal that, of the secondary-side terminal pair of the conversion circuit, is on a side opposite the main battery, to the power supply bus; a second relay that disconnects and connects the bus connection path; a negative-electrode-side path and a positive-electrode-side path that connect the secondary-side terminal pair of the conversion circuit to a low-voltage load in parallel; a third relay that disconnects and connects the negative-electrode-side path; and a fourth relay that disconnects and connects the positive-electrode-side path, in which a positive electrode and a negative electrode of the main battery are respectively connected to the primary-side terminal pair of the conversion circuit, the secondary-side terminal pair of the conversion circuit are connectable in series to the main battery, and the secondary-side terminal pair of the conversion circuit are connectable in parallel to the low-voltage load, the control program causing a computer to perform: a process in which the first relay and the second relay are connected and the third relay and the fourth relay are disconnected in response to a voltage adjustment mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the power supply bus being executed, and the first relay and the second relay are disconnected and the third relay and the fourth relay are connected in response to a low-voltage power supply mode in which power is supplied from the secondary-side terminal pair of the conversion circuit to the low-voltage load being executed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation application of International Application No. PCT/JP2024/021431, filed on Jun. 13, 2024, which claims priority to Japanese Patent Application No. 2023-108740, filed on Jun. 30, 2023. The contents of these applications are incorporated herein by reference in their entirety. BACKGROUND The present disclosure relates to a power supply system. There is a power supply system that includes a first converter and a second converter that receive power supply from a high-voltage battery, and a low-voltage load that receives power supply from at least one of the first converter and the second converter. SUMMARY One aspect of the present disclosure provides a power supply system including a plurality of main batteries connected in parallel to a power supply bus, and at least a single conversion circuit that converts power input from the main batteries to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair, in which: a positive electrode and a negative electrode of the main battery are respectively connected to the primary-side terminal pair of the conversion circuit; the secondary-side terminal pair of the conversion circuit are connectable in series to the main battery; and the secondary-side terminal pair of the conversion circuit are connectable in parallel to a low-voltage load. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a circuit diagram illustrating a power supply system; FIG. 2 is a circuit diagram illustrating an example of a conversion circuit; FIG. 3 is a circuit diagram illustrating relay states and currents in a voltage adjustment mode; FIG. 4 is a circuit diagram illustrating relay states and currents in a 12V-DCDC mode; FIG. 5 is a flowchart illustrating steps for mode switching according to a first embodiment; FIG. 6 is a flowchart illustrating steps for mode switching according to a second embodiment; FIG. 7 is a flowchart illustrating steps for mode switching according to a third embodiment; FIG. 8 is a flowchart illustrating steps for mode switching according to a fourth embodiment; FIG. 9 is a circuit diagram illustrating a modification of the power supply system; FIG. 10 is a circuit diagram illustrating another modification of the power supply system; FIG. 11 is a circuit diagram illustrating another modification of the power supply system; FIG. 12 is a circuit diagram illustrating another modification of the power supply system; FIG. 13 is a circuit diagram illustrating another modification of the power supply system; FIG. 14 is a circuit diagram illustrating a modification of the conversion circuit; FIG. 15 is a circuit diagram illustrating another modification of the conversion circuit; FIG. 16 is a circuit diagram illustrating another modification of the conversion circuit; and FIG. 17 is a circuit diagram illustrating a modification of a storage battery module. DESCRIPTION OF THE EMBODIMENTS For example, there is a power supply system that includes a first converter and a second converter that receive power supply from a high-voltage battery, and a low-voltage load that receives power supply from at least one of the first converter and the second converter (see JP 7198606 B2). In the power supply system described in JP 7198606 B2, power can be supplied to the low-voltage load from the second converter if the first converter fails. The power supply for the low-voltage load can be provided with redundancy. Incidentally, a power supply system in which a plurality of high-voltage batteries (main batteries) are connected in parallel to a power supply bus requires a partial step-up converter (partial power converter (PPC)) that adjusts voltage difference between the high-voltage batteries. The discloser of the present application has focused on a possibility of reducing the number of redundant power supplies if the PPC is able to be used as a power supply for the low-voltage load. It is thus desired to enable a PPC to be used as a power supply for a low-voltage load in a power supply system in which a plurality of main batteries are connected in parallel to a power supply bus. A first exemplary embodiment of the present disclosure provides a power supply system including a plurality of main batteries connected in parallel to a power supply bus, and at least a single conversion circuit that converts power input from the main batteries to a primary-side terminal pair and outputs the converted power from a secondary-side terminal pair, in which: a positive electrode and a negative electrode of the main battery are respectively connected to the primary-side terminal pair of the conversion circuit; the secondary-side terminal pair of the conversion circuit are connectable in series to the main battery; and the secondary-side terminal pair of the conversion circuit are connectable in parallel to a low-voltage load. As a result of the above-described c