EP-4738678-A1 - POWER SUPPLY SYSTEM AND CONTROL PROGRAM

EP4738678A1EP 4738678 A1EP4738678 A1EP 4738678A1EP-4738678-A1

Abstract

A power supply system (10) includes a rechargeable battery (31, 61) and a conversion circuit (40, 70) that converts power input from the rechargeable battery to a primary-side terminal pair (41, 42, 71, 72) by drive of a switching element and outputs the converted power from a secondary-side terminal pair (47, 48, 77, 78). A positive electrode and a negative electrode of the rechargeable battery are individually connected to the primary-side terminal pair of the conversion circuit, and the rechargeable battery is connected in series to the secondary-side terminal pair of the conversion circuit. The power supply system includes a connection retaining circuit (49, 79) that retains the secondary-side terminal pair in a state of being connected.

Inventors

ITO, MITSUTAKA
KURACHI, TAISUKE
YAMADA, TETSUYA

Assignees

DENSO CORPORATION

Dates

Publication Date: 20260506
Application Date: 20240613

Claims (12)

A power supply system (10, 210) comprising a rechargeable battery (31, 61, 91) and a conversion circuit (40, 70, 100) that converts power input from the rechargeable battery to a primary-side terminal pair (41, 42, 71, 72) by drive of a switching element (43 to 46, 54, 55, 143 to 146) and outputs the converted power from a secondary-side terminal pair (47, 48, 77, 78), wherein a positive electrode and a negative electrode of the rechargeable battery are individually connected to the primary side terminal pair of the conversion circuit, and the rechargeable battery is connected in series to the secondary-side terminal pair of the conversion circuit, and wherein the power supply system comprises a connection retaining circuit (36, 37, 49, 66, 67, 79, 96, 97) that retains the secondary-side terminal pair in a state of being connected.
The power supply system according to claim 1, wherein the connection retaining circuit is constituted by a secondary-side circuit (49, 79) of the conversion circuit connected to the secondary-side terminal pair and retains the secondary-side terminal pair in a state of being connected by the secondary-side circuit via a secondary-side switching element (54, 55) that is the switching element included in the secondary-side circuit.
The power supply system according to claim 1, wherein the connection retaining circuit includes: a bypass (36, 66, 96) that bypasses the conversion circuit and connects the secondary-side terminal pair, and a bypass switch (37, 67, 97) that interrupts and connects the bypass; and the connection retaining circuit retains the secondary-side terminal pair in a state of being connected by retaining the bypass in a state of being connected by the bypass switch.
The power supply system according to any one of claims 1 to 3, wherein a rechargeable battery module (30, 60, 90) is constituted by the rechargeable battery, the conversion circuit, and the connection retaining circuit, wherein the rechargeable battery module is connected to a power supply bus (11, 12), and wherein the power supply system further comprises a control unit (16b) configured to execute a conduction mode of retaining the secondary-side terminal pair in a state of being connected by the connection retaining circuit of the rechargeable battery module, on condition that a difference between a bus voltage as a voltage of the power supply bus and an output voltage of the rechargeable battery of the rechargeable battery module is smaller than a voltage threshold value.
The power supply system according to claim 4, comprising a plurality of the rechargeable battery modules, wherein the plurality of the rechargeable battery modules are connected in parallel to the power supply bus, and wherein the control unit is configured to select the rechargeable battery module including the rechargeable battery having the highest output voltage as the rechargeable battery module to be put in the conduction mode in the plurality of the rechargeable battery modules.
The power supply system according to claim 4, comprising a plurality of the rechargeable battery modules, wherein the plurality of the rechargeable battery modules are connected in parallel to the power supply bus, and wherein the control unit is configured to sequentially select the rechargeable battery modules in descending order of output voltages of the rechargeable batteries as the rechargeable battery module to be put in the conduction mode in a plurality of the rechargeable battery modules.
The power supply system according to claim 6, wherein the control unit is configured to adjust an output voltage of the conversion circuit such that in a rechargeable battery module in which a difference between the bus voltage and an output voltage of the rechargeable battery of the rechargeable battery module is not smaller than the voltage threshold value, a difference between the bus voltage and an output voltage of the rechargeable battery module is smaller than the voltage threshold value.
The power supply system according to claim 4, comprising a plurality of the rechargeable battery modules, wherein the plurality of the rechargeable battery modules are connected in parallel to the power supply bus, and wherein the control unit is configured to select the rechargeable battery module to be put in the conduction mode and adjust a state of the rechargeable battery of the selected rechargeable battery module so as to retain a state in which a difference between the bus voltage and an output voltage of the rechargeable battery of the selected rechargeable battery module is smaller than the voltage threshold value.
The power supply system according to claim 4, comprising a plurality of the rechargeable battery modules, wherein the plurality of the rechargeable battery modules are connected in parallel to the power supply bus, and wherein the control unit is configured to put the rechargeable battery module not put in the conduction mode into the conduction mode, on condition that a difference between an output voltage of the rechargeable battery of the rechargeable battery module put in the conduction mode and an output voltage of the rechargeable battery of the rechargeable battery module not put in the conduction mode is smaller than the voltage threshold value, while any one of the rechargeable battery modules is put into the conduction mode.
The power supply system according to claim 9, wherein the control unit is configured to charge the rechargeable battery of the rechargeable battery module not put in the conduction mode from the rechargeable battery of the rechargeable battery module put in the conduction mode, when a difference between an output voltage of the rechargeable battery of the rechargeable battery module put in the conduction mode and an output voltage of the rechargeable battery of the rechargeable battery module not put in the conduction mode is not smaller than the voltage threshold value.
The power supply system according to claim 10, wherein the control unit is configured to charge the rechargeable battery of the rechargeable battery module not put in the conduction mode from the rechargeable battery of the rechargeable battery module put in the conduction mode, by lowering an output voltage of the conversion circuit of the rechargeable battery module not put in the conduction mode to lower than a current output voltage.
A control program applied to a power supply system (10, 210) in which a rechargeable battery module (30, 60, 90) including a rechargeable battery (31, 61, 91) and a conversion circuit (40, 70, 100) is connected to a power supply bus (11, 12), the conversion circuit converting power input from the rechargeable battery to a primary-side terminal pair (41, 42, 71, 72) by drive of a switching element (43 to 46, 54, 55, 143 to 146) and outputting the converted power from a secondary-side terminal pair (47, 48, 77, 78), a positive electrode and a negative electrode of the rechargeable battery are individually connected to the primary-side terminal pair of the conversion circuit, the rechargeable battery is connected in series to the secondary-side terminal pair of the conversion circuit, and the power supply system includes a connection retaining circuit (36, 37, 49, 66, 67, 79) that retains the secondary-side terminal pair in a state of being connected, wherein the control program causes a computer (16) to execute a conduction mode of retaining the secondary-side terminal pair in a state of being connected by the connection retaining circuit of the rechargeable battery module, on condition that a difference between a bus voltage as a voltage of the power supply bus and an output voltage of the rechargeable battery of the rechargeable battery module is smaller than a voltage threshold value.

Description

[Cross Reference to Related Application] The present application is based on Japanese Application No. 2023-108739 filed on June 30, 2023, the contents of which are incorporated herein by reference. [Technical Field] The present disclosure relates to a power supply system. [Background Art] For example, there is a control system for rechargeable batteries which includes a plurality of rechargeable batteries and a converter that controls the charge and discharge currents of each of the rechargeable batteries (see PTL 1). In the control system for rechargeable batteries described in PTL 1, the efficiency of the entire system is enhanced by distributing the total current instruction value for the plurality of rechargeable batteries to the converters depending on the states of charge (SOC) of the rechargeable batteries, the output voltages of the rechargeable batteries, the total charge and discharge electric power amounts of the rechargeable batteries, the temperature properties of the rechargeable batteries, and the like. [Citation List] [Patent Literature] PTL 1: JP 2014-207790 A [Summary of the Invention] In the control system for rechargeable batteries described in PTL 1, converters (conversion circuits) connected to the respective rechargeable batteries must necessarily be driven in a switching manner in order to output power from the rechargeable batteries. Therefore, the switching losses of the converters occur even in a situation where the voltages of the rechargeable batteries do not need to be increased or decreased at the time of outputting power from the rechargeable batteries, and there is yet room for improvement in enhancing the efficiency of the system. The present disclosure has been made to solve the above-described problem, and has as its main object to reduce loss when supplying power in a power supply system including a rechargeable battery and a conversion circuit. A first measure for solving the above-described problem is a power supply system including a rechargeable battery and a conversion circuit that converts power input from the rechargeable battery to a primary-side terminal pair by drive of a switching element and outputs the converted power from a secondary-side terminal pair,in which a positive electrode and a negative electrode of the rechargeable battery are individually connected to the primary-side terminal pair of the conversion circuit, and the rechargeable battery is connected in series to the secondary-side terminal pair of the conversion circuit, andin which the power supply system includes a connection retaining circuit that retains the secondary-side terminal pair in a state of being connected. According to the above-described configuration, a power supply system includes a rechargeable battery and a conversion circuit that converts power input from the rechargeable battery to a primary-side terminal pair by drive of a switching element and outputs the power from a secondary-side terminal pair. Therefore, a power supply system can convert power input from the rechargeable battery to a primary-side terminal pair by driving a switching element in a conversion circuit and output the power from a secondary-side terminal pair. When power is converted by a conversion circuit, switching losses (turn-on and turn-off losses) occur in the switching element. Note that switching losses are losses that occur in connection with the switch driving (turn-on and turn-ff driving) of a switching element. Here, a positive electrode and a negative electrode of the rechargeable battery are individually connected to the primary-side terminal pair of the conversion circuit, and the rechargeable battery is connected in series to the secondary-side terminal pair of the conversion circuit. According to such a configuration, a voltage that is the sum of an output voltage Vb of a rechargeable battery and an output voltage Vo of a conversion circuit is an output voltage Vm of a rechargeable battery module. Therefore, it is possible to reduce an output voltage Vo required of a conversion circuit when a rechargeable battery module is required to have an output voltage Vm, as compared with a rechargeable battery module in which a rechargeable battery is connected in parallel to a secondary-side terminal pair of a conversion circuit. Therefore, a rated voltage of a conversion circuit can be reduced, and a rated capacity of a conversion circuit can be accordingly reduced. This can reduce the size of a conversion circuit. Further, a power supply system includes a connection retaining circuit that retains the secondary-side terminal pair in a state of being connected. Therefore, in a situation where it is unnecessary to increase a voltage to higher than a voltage of a rechargeable battery when outputting power from a rechargeable battery, power can be directly output from a rechargeable battery by retaining a secondary-side terminal pair connected in series to a rechargeable battery in a state of being co