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JP-2026074534-A - Energy storage system

JP2026074534AJP 2026074534 AJP2026074534 AJP 2026074534AJP-2026074534-A

Abstract

[Problem] In an energy storage system in which a capacitor, a switch for connecting/disconnecting the capacitor and the batteries, and a precharge circuit connected in parallel with the switch are provided on a power line connecting multiple batteries in series, the constraints caused by the resistance value of the precharge circuit are alleviated. [Solution] In the energy storage system 1, the positive and negative sides of a power line PL connecting a plurality of battery modules M1 to Mn in series are connected by a smoothing capacitor C, a system main relay S3 is provided between the smoothing capacitor C of the power line PL and the battery modules M1 to Mn, and the resistance value of the precharge circuit 10, in which a first resistor Rp and a first precharge relay S4 connected in series are connected in parallel with the system main relay S3, is variable by a resistance value variable mechanism 11. [Selection Diagram] Figure 1

Inventors

  • ▲高▼松 寛彰
  • 荘田 隆博
  • 松木 亮磨

Assignees

  • 矢崎総業株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (6)

  1. A power line connecting multiple storage batteries in series, A capacitor connecting the positive and negative sides of the power line, A first switch is provided between the capacitor and the battery in the power line, and which connects or disconnects the capacitor and the battery in the power line. The device comprises a resistor connected in parallel with the first switch to the power line, a second switch that connects or disconnects the resistor and the power line, and a precharge circuit through which a precharge current flows to the capacitor. The pre-charge circuit is an energy storage system that includes a variable resistance unit for varying the resistance value of the resistor.
  2. The energy storage system according to claim 1, further comprising a third switch connected in series with the battery via the power line, and a fourth switch connected in parallel with the battery and the third switch, and further comprising a plurality of bypass sections provided for each battery.
  3. The system comprises the first switch, the second switch, the third switch, the fourth switch, and a control unit that controls the variable resistance unit, The control unit, With the fourth switch corresponding to any of the aforementioned batteries in the open position, the first switch disconnects the connection between the capacitor and the battery in the power line, the second switch connects the resistor and the power line, and the third switch corresponding to any of the aforementioned batteries is operated to perform a first oxide film removal process that removes the oxide film from the contact portion of the third switch. The energy storage system according to claim 2, wherein the resistance variable unit is controlled such that, when the first oxide film removal process is performed, the resistance value of the resistor becomes lower than when the pre-charge process is performed in which the capacitor is charged with the pre-charge current.
  4. The system comprises the first switch, the second switch, the third switch, the fourth switch, and a control unit that controls the variable resistance unit, The control unit, With the third switch corresponding to any of the aforementioned batteries in the open position, the first switch disconnects the connection between the capacitor and the battery in the power line, the second switch connects the resistor and the power line, and the fourth switch corresponding to any of the aforementioned batteries is operated to perform a second oxide film removal process to remove the oxide film from the contact portion of the fourth switch. The energy storage system according to claim 2, wherein the resistance variable unit is controlled such that, when the second oxide film removal process is performed, the resistance value of the resistor becomes lower than when the pre-charge process is performed in which the capacitor is charged with the pre-charge current.
  5. The aforementioned resistor is A first resistor connected in parallel with the first switch to the power line, The device comprises a first switch and a first resistor, a second resistor connected in parallel to the power line, and having a lower resistance value than the first resistor, The aforementioned resistance value variable unit is A pair of the aforementioned second switches are provided, The other second switch is connected in series with the first resistor, The other second switch is connected in series with the second resistor in the energy storage system according to claim 1 or 2.
  6. The aforementioned resistor is A first resistor connected in parallel with the first switch to the power line, The system comprises a second resistor connected in series with the first resistor and in parallel with the first switch to the power line, the second resistor having a lower resistance value than the first resistor, The aforementioned resistance value variable unit is The energy storage system according to claim 1 or 2, further comprising a fifth switch connected in parallel with the first resistor or the second resistor.

Description

This invention relates to an energy storage system. A known energy storage system is one in which multiple batteries are connected in series, and a bypass section is provided for each battery to switch between a connected state and a bypass state (see, for example, Patent Document 1). In the energy storage system described in Patent Document 1, a cutoff switch connected in series with the battery and a bypass switch connected in parallel with the battery and cutoff switch are provided in the bypass section. In this energy storage system, if there is a battery that cannot discharge the required current, bypass control is performed in which the cutoff switch corresponding to that battery is opened and the bypass switch corresponding to that battery is closed, and discharge occurs from the other connected batteries. Japanese Patent Publication No. 2013-31247 Figure 1 is a schematic circuit diagram showing an energy storage system according to one embodiment of the present invention.Figure 2 is a circuit diagram illustrating the first oxide film removal process.Figure 3 is a circuit diagram illustrating the process of removing the second oxide film.Figure 4 is a circuit diagram illustrating the pre-charge process.Figure 5 is a flowchart illustrating the process of switching the battery module targeted by the bypass control request from the connected state to the bypass state.Figure 6 is a schematic circuit diagram showing another embodiment of the present invention of an energy storage system. The present invention will be described below in accordance with preferred embodiments. However, the present invention is not limited to the embodiments shown below, and the embodiments can be modified as appropriate without departing from the spirit of the invention. Furthermore, in the embodiments shown below, some illustrations and descriptions of certain components are omitted. For details of the omitted technologies, publicly known or well-known technologies can be applied as appropriate, to the extent that they do not contradict the content described below. Figure 1 is a schematic circuit diagram of a power storage system 1 according to one embodiment of the present invention. As shown in this figure, the power storage system 1 comprises a power storage string STR, a power converter PCS, a string bus 2, and a battery control device 100. Although not shown, the power storage system 1 comprises a plurality of power storage strings STR, which are connected in parallel to each other via the string bus 2 and are also connected to an external system (not shown). The power storage system 1 is a power source for stationary or vehicle-mounted use. The energy storage string STR comprises n battery modules M1 to Mn (where n is an integer of 2 or more) connected in series by a power line PL. While not particularly limited, the battery modules M1 to Mn in this embodiment are refurbished used batteries, and there are differences in the degree of degradation among them. Each battery module M1 to Mn is, for example, a secondary battery such as a lithium-ion battery, lithium-ion capacitor, or nickel-metal hydride battery, with multiple cells connected together. Battery modules M1 to Mn are charged by power supplied from the external grid via the string bus 2 and the power converter PCS. Furthermore, battery modules M1 to Mn supply power to the external grid via the power converter PCS and the string bus 2. The external system includes loads and generators. If the energy storage system 1 is stationary, the commercial power grid and power-consuming facilities become the loads, while solar power generation systems become the generators. On the other hand, if the energy storage system 1 is vehicle-mounted, the drive motor, air conditioner, and various vehicle-mounted electrical components become the loads. Note that the drive motor can function as both a load and a generator. Furthermore, the energy storage string STR may comprise n battery cells or battery packs connected in series, instead of n battery modules M1 to Mn connected in series. In this case, the energy storage string STR may include bypass sections that bypass each battery cell or battery pack. The power converter PCS is a DC/DC converter or DC/AC converter and is connected to the string bus 2. The power converter PCS is also connected to the positive terminal of the starting battery module M1 (hereinafter referred to as the total + of the energy storage string STR) and the negative terminal of the ending battery module Mn (hereinafter referred to as the total - of the energy storage string STR). The power converter PCS, during the charging of the energy storage string STR, converts the voltage input from the string bus 2 according to the indicated charging power (or current) value and outputs it to multiple battery modules M1 to Mn. Here, the voltage on the energy storage string STR side changes depending on the bypass state of battery modules M1 to Mn (the number of bypa