Outdoor lithium battery ups power supply

Abstract

The application discloses an outdoor lithium battery UPS power supply and relates to the technical field of UPS power supplies.The application comprises a battery pack supporting shell and a plurality of independent battery packs, the battery packs are slidably inserted into the supporting shell, and are stably fixed through limiting pins.Each battery pack is internally provided with a flow guide plate, an intermediate baffle and an aerogel pad, so that efficient heat management and pressure relief control are realized.When an electric core explodes, the limiting mechanism is released by pressure relief gas, so that the damaged battery pack is automatically separated, and the system safety is improved.A redundant switching mechanism of a relay normally closed contact is used to ensure that the subsequent battery can automatically replace power supply when any battery pack fails.The system has the multiple advantages of modularity, quick replacement, efficient heat dissipation, automatic separation and redundant power supply, and is suitable for high-safety power supply scenes in complex outdoor environments.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of UPS power supplies, in particular to an outdoor lithium battery UPS power supply. BACKGROUND

[0002] At present, most outdoor lithium battery UPS power supplies adopt fixed battery pack structures and lack modular design, so that the batteries are difficult to be quickly replaced when damaged, and the overall maintenance cost of the system is high. The battery packs in the prior art are mainly integrally sealed, lack effective internal pressure relief and heat management mechanisms, and once thermal runaway of the battery cells occurs, a chain explosion accident is easily triggered, and damage cannot be effectively limited to a single battery pack. In addition, the existing system lacks automatic switching and isolation mechanisms when the battery pack is damaged, resulting in high risk of power supply interruption, poor safety and continuity. Most UPS systems only rely on electronic control boards to identify faulty batteries, which is complex and has many fault points, and cannot work reliably in harsh outdoor environments. The existing pressure relief channel design is simple, and after pressure relief, it is easy to affect adjacent battery packs, and lacks effective explosion isolation and automatic disengagement design, and the overall protection performance is low. SUMMARY

[0003] In order to overcome the defects of the prior art, the application provides the following technical scheme: an outdoor lithium battery UPS power supply, comprising a battery pack support shell, six mutually independent cavities are arranged in the battery pack support shell, and a battery pack is slidably connected in each cavity; the battery pack comprises a battery pack shell, a reinforcing partition plate and an intermediate baffle plate are fixedly installed on the inner wall of the battery pack shell, a plurality of battery cells are arranged on both sides of the intermediate baffle plate, aerogel pads are arranged between adjacent two battery cells, the pressure relief valves of all the battery cells on both sides of the intermediate baffle plate are arranged towards the intermediate baffle plate, and a flow guide plate is arranged on the surface of the intermediate baffle plate; a tail sealing cover is further fixedly installed on the battery pack shell, the tail sealing cover is used for packaging all the battery cells on the inner wall of the battery pack shell, all the battery cells are fixedly installed on the inner wall of the battery pack shell, a nozzle is fixedly installed in the middle of the tail sealing cover, the nozzle is arranged in alignment with the intermediate baffle plate, and a conductive contact is further arranged on the tail sealing cover; a limiting pin sliding hole is formed on the battery pack support shell at the position of each cavity, and a limiting pin that is in extrusion and frictional engagement with the battery pack shell is slidably installed in each limiting pin sliding hole, and the limiting pin is used for preventing the battery pack shell from sliding out of the cavity.

[0004] Preferably, an insulating sealing back plate is further fixedly installed on the battery pack support shell, a plurality of electric lead contacts are fixedly installed on the insulating sealing back plate, the electric lead contacts are in conductive engagement with the conductive contact, and the electric lead contacts are insulatively and separately arranged through the insulating sealing back plate.

[0005] Preferably, the insulating and sealing back plate has six unlocking exhaust ports, each of which is aligned with a corresponding nozzle, and each unlocking exhaust port is equipped with a one-way baffle that can block the unlocking exhaust port. All unlocking exhaust ports are fitted with a back sealing pressure guide cover on their outer side, and the upper and lower edges of the back sealing pressure guide cover are provided with air guide grooves.

[0006] Preferably, each one-way baffle is fixedly installed with a one-way baffle guide slide rod, which slides in conjunction with the back sealing pressure guide cover. A spring is wrapped around the one-way baffle guide slide rod, and the two ends of the spring are fixed in conjunction with the one-way baffle and the back sealing pressure guide cover.

[0007] Preferably, a drive plate is fixedly installed on both the upper and lower surfaces of the battery pack support shell. The drive plate has three sliding cavities aligned with the sliding holes of the limiting pin. An E-shaped gas pressure guide groove is provided on the side of the drive plate facing the battery pack support shell. The gas pressure guide groove is used to connect the three sliding cavities to the gas guide groove. A sealing piston plate is slidably and sealed inside the sliding cavity. The sealing piston plate is fixedly engaged with the limiting pin. An unlocking pull block is fixedly installed on each sealing piston plate. An elastic rubber pad limiting strip is fixedly installed on the side of the drive plate away from the battery pack support shell. An elastic rubber pad is elastically provided between the elastic rubber pad limiting strip and the limiting pin to squeeze the limiting pin toward the battery pack shell.

[0008] Preferably, a housing buckle plate is fixedly fastened on the drive plate, and a shovel block limiting block is fixedly installed on each drive plate at the position of the sliding cavity. A shovel block is overlapped on the shovel block limiting block and slides with the drive plate. The shovel block is used to shovel up the unlocking pull block. The unlocking pull block is provided with a groove, and the shovel block is provided with an inclined surface that slides with the groove on the unlocking pull block. An unlocking push-pull rod is fixedly installed on each shovel block, and the end of the unlocking push-pull rod away from the shovel block extends to the outside of the housing buckle plate.

[0009] Preferably, the output terminals of the six battery packs are electrically connected to the input terminal of the inverter in parallel (the inverter output terminal is used to connect the electrical load, and each battery pack needs to be charged separately, with each battery pack equipped with an independent charging unit). Diodes are connected in series between the output terminals of battery packs 1-5 and the input terminal of the inverter, and the output terminals of battery packs 1-5 are connected in parallel with the electromagnetic coils of the corresponding relays KM1-KM5.

[0010] Preferably, a normally closed contact of relay KM1 is connected in series between the output terminal of battery pack 2 and relay KM2; normally closed contacts of relay KM2 and relay KM1 are connected in series between the output terminal of battery pack 3 and relay KM3; normally closed contacts of relay KM3, relay KM2 and relay KM1 are connected in series between the output terminal of battery pack 4 and relay KM4; normally closed contacts of relay KM4, relay KM3, relay KM2 and relay KM1 are connected in series between the output terminal of battery pack 5 and relay KM5; normally closed contacts of relay KM5, relay KM4, relay KM3, relay KM2 and relay KM1 are connected in series between the output terminal of battery pack 6 and the input terminal of the inverter.

[0011] Compared with the prior art, the present invention has the following advantages: (1) The present invention sets up multiple independent cavities through the battery pack support shell, allowing the battery pack to be flexibly installed and replaced by sliding plug-in method. The battery pack has strong independence and can flexibly configure the number of batteries according to actual power demand, so as to realize flexible adjustment of power output. The modular structure makes it possible to quickly locate and replace a single battery pack when it fails, which greatly improves the maintainability and reliability of the system and reduces the overall operation and maintenance cost, and is particularly suitable for variable outdoor power supply scenarios; (2) The battery pack of the present invention adopts a structure of limit pin and limit pin sliding hole for physical limit, and is supplemented with elastic rubber pads to provide stable support, ensuring that the battery pack will not fall off in complex environments such as strong vibration and tilt. If a cell explodes, the pressure relief airflow can trigger the limit pin to automatically release, and the exhaust path is sealed by the back sealing pressure guide cover. The air pressure will automatically eject the battery pack, effectively isolating the damaged battery, preventing the accident from spreading, and improving the system's safety assurance capability in harsh environments; (3) The pressure relief valves of the cells in this invention are uniformly arranged facing the middle baffle, and the pressure relief airflow is guided to be concentrated and ejected through the guide plate to avoid the direct impact of the flame on other cells. The one-way discharge of the pressure relief gas at the nozzle forms a local efficient pressure relief channel. Through this mechanism, even if a violent accident occurs inside the battery pack, it can achieve rapid and directional pressure relief, thereby reducing the overall risk of the system; (4) This invention adopts a series relay normally closed contact control mechanism, and the battery packs 1-6 are connected in series for fault protection. When the current first-level battery pack fails, its corresponding relay is de-energized, and the subsequent battery packs are automatically switched to the working power supply to ensure that the UPS system does not interrupt power supply; (5) Aerogel pads are set between the cells in this invention to achieve excellent thermal insulation effect and slow down the rate at which the heat of a single cell spreads to the surrounding cells. Meanwhile, through the guidance of the intermediate baffle and the deflector, efficient airflow management is achieved during the depressurization process, avoiding the accumulation of heat inside the system. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0013] Figure 2 This is a schematic diagram of the structure of the elastic rubber pad limiting strip of the present invention.

[0014] Figure 3 For the present invention Figure 2 Schematic diagram of the structure at point A in the middle.

[0015] Figure 4 This is a schematic diagram of the structure of the drive board of the present invention.

[0016] Figure 5 For the present invention Figure 4 Schematic diagram of the structure at point B.

[0017] Figure 6 This is a schematic diagram of the back sealing pressure guide buckle cover of the present invention.

[0018] Figure 7 For the present invention Figure 6 Schematic diagram of the structure at point C.

[0019] Figure 8 This is a schematic diagram of the gas pressure guiding groove of the present invention.

[0020] Figure 9 This is a schematic diagram of the structure at the sliding hole of the limiting pin in this invention.

[0021] Figure 10 For the present invention Figure 9 Schematic diagram of the structure at point D.

[0022] Figure 11 This is a schematic diagram of the internal structure of the battery pack casing of the present invention.

[0023] Figure 12 This is a schematic diagram of the structure of the guide plate of the present invention.

[0024] Figure 13 This is a schematic diagram of the power supply for the battery pack of the present invention.

[0025] In the diagram: 101-Battery pack support casing; 102-Limit pin sliding hole; 103-Insulating and sealing back plate; 104-Electrical contact; 105-One-way baffle guide slide rod; 106-One-way baffle; 107-Spring; 108-Back sealing pressure guide cover; 109-Gas guide groove; 110-Drive board; 111-Gas pressure guide groove; 112-Sliding cavity; 113-Elastic rubber pad limiting strip; 114-Unlocking pull block ; 115-Elastic rubber pad; 116-Sealing piston plate; 117-Limiting pin; 118-Shovel block; 119-Shovel block limiting block; 120-Unlocking push-pull rod; 121-Outer casing buckle plate; 122-Unlocking exhaust port; 201-Battery pack outer casing; 202-Reinforced separator; 203-Tail sealing cover; 204-Intermediate baffle; 205-Guide plate; 206-Battery cell; 207-Nozzle; 208-Conductive contact. Detailed Implementation

[0026] The following is in conjunction with the appendix Figures 1-13 The technical solution of the present invention will be further illustrated through specific embodiments.

[0027] This invention provides an outdoor lithium-ion battery UPS power supply, including a battery pack support housing 101. The battery pack support housing 101 has six independent cavities, each containing a battery pack that is slidably inserted into it. The battery pack includes a battery pack housing 201. A reinforcing partition 202 and a middle baffle 204 are fixedly installed on the inner wall of the battery pack housing 201. Multiple battery cells 206 are arranged on both sides of the middle baffle 204, with an aerogel pad between adjacent battery cells 206. The pressure relief valves of all battery cells 206 on both sides of the middle baffle 204 face the middle baffle 204, and a flow guide plate 205 is provided on the surface of the middle baffle 204. A tail section is also fixedly installed on the battery pack housing 201. The sealing cover 203 and the tail sealing cover 203 are used to encapsulate all the cells 206 on the inner wall of the battery pack housing 201, and all the cells 206 are fixedly installed on the inner wall of the battery pack housing 201. A nozzle 207 is fixedly installed in the middle of the tail sealing cover 203. The nozzle 207 is aligned with the middle baffle 204. The tail sealing cover 203 is also provided with conductive contacts 208. The battery pack support housing 101 has a limit pin sliding hole 102 at the position of each cavity. A limit pin 117 that is squeezed and frictionally engaged with the battery pack housing 201 is slidably installed in each limit pin sliding hole 102. The limit pin 117 is used to prevent the battery pack housing 201 from sliding out of the cavity.

[0028] An insulating and sealing backplate 103 is also fixedly installed on the battery pack support housing 101. Multiple electrical contacts 104 are fixedly installed on the insulating and sealing backplate 103. The electrical contacts 104 make contact with the conductive contacts 208 and conduct electricity. Each electrical contact 104 is insulated and isolated from the others by the insulating and sealing backplate 103. Six unlocking vents 122 are provided on the insulating and sealing backplate 103. Each unlocking vent 122 is aligned with a corresponding nozzle 207, and each unlocking vent 122 is equipped with a one-way baffle 106 that can block the unlocking vent 122. A back sealing pressure guide cover 108 is fastened to the outside of all unlocking vents 122. Air guide grooves 109 are provided on the upper and lower edges of the back sealing pressure guide cover 108. Each one-way baffle 106 is fixedly installed with a one-way baffle guide slide rod 105. The one-way baffle guide slide rod 105 is slidably engaged with the back sealing pressure guide cover 108. A spring 107 is sleeved around the one-way baffle guide slide rod 105. The two ends of the spring 107 are fixedly engaged with the one-way baffle 106 and the back sealing pressure guide cover 108. A drive plate 110 is fixedly installed on both the upper and lower surfaces of the battery pack support housing 101. The drive plate 110 has three sliding cavities 112 aligned with the sliding holes 102 of the limit pins. An E-shaped gas pressure guide groove 111 is provided on the side of the drive plate 110 facing the battery pack support housing 101. The gas pressure guide groove 111 is used to connect the three sliding cavities 112 with the gas guide groove 109. A sealing piston plate 116 is slidably and sealed in the sliding cavity 112. The sealing piston plate 116 is fixedly engaged with the limit pin 117. An unlocking pull block 114 is fixedly installed on each sealing piston plate 116. An elastic rubber pad limit strip 113 is fixedly installed on the side of the drive plate 110 away from the battery pack support housing 101. An elastic rubber pad 115 is elastically provided between the elastic rubber pad limit strip 113 and the limit pin 117 to squeeze the limit pin 117 toward the battery pack housing 201. A housing buckle plate 121 is fixedly fastened to the drive plate 110. A shovel block limiting block 119 is fixedly installed on each drive plate 110 at the position of the sliding cavity 112. A shovel block 118 is overlapped on the shovel block limiting block 119. The shovel block 118 slides with the drive plate 110. The shovel block 118 is used to shovel up the unlocking pull block 114. The unlocking pull block 114 is provided with a groove. The shovel block 118 is provided with an inclined surface that slides with the groove on the unlocking pull block 114. An unlocking push-pull rod 120 is fixedly installed on each shovel block 118. The end of the unlocking push-pull rod 120 away from the shovel block 118 extends to the outside of the housing buckle plate 121.

[0029] The output terminals of the six battery packs are electrically connected to the input terminal of the inverter in parallel (the inverter output terminal is used to connect to the electrical load, and each battery pack needs to be charged separately, with each battery pack equipped with an independent charging unit). Diodes are installed in series between the output terminals of battery packs 1-5 and the input terminal of the inverter, and the output terminals of battery packs 1-5 are connected in parallel with the electromagnetic coils of the corresponding relays KM1-KM5. A normally closed contact of relay KM1 is connected in series between the output terminal of battery pack 2 and relay KM2; normally closed contacts of relays KM2 and KM1 are connected in series between the output terminal of battery pack 3 and relay KM3; normally closed contacts of relays KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 4 and relay KM4; normally closed contacts of relays KM4, KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 5 and relay KM5; normally closed contacts of relays KM5, KM4, KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 6 and the input terminal of the inverter.

[0030] The working principle of an outdoor lithium-ion UPS power supply disclosed in this invention is as follows: According to the user's needs, the required number of battery packs are inserted into the cavity of the battery pack support housing 101. The insertion process is as follows: First, the battery pack housing 201 is partially inserted into the cavity of the battery pack support housing 101. At this time, the edge of the battery pack housing 201 is held in place by the limiting pin 117. Then, the unlocking push-pull rod 120 at the corresponding position is pressed (the same applies when disassembling). The unlocking push-pull rod 120 pushes the shovel block 118 to squeeze the unlocking pull block 114, causing the unlocking pull block 114 to move away from the battery pack housing 201. This then drives the sealing piston plate 116 and the limiting pin 117 to move synchronously. When the time limit pin 117 retracts into the limit pin sliding hole 102, it continues to be inserted into the battery pack housing 201 until it is fully inserted. At this point, the unlocking push-pull rod 120 can be released. Under the elastic force of the elastic pad 115, the limit pin 117 presses the battery pack housing 201 tightly, preventing relative sliding between the battery pack housing 201 and the battery pack support housing 101 due to vibration. (In addition, a resistance buckle is provided between the outer surface of the battery pack housing 201 and the inner wall of the cavity of the battery pack support housing 101; or a groove is provided on the surface of the battery pack housing 201 to engage with the limit pin 117; or it is fixed by screws, depending on the application scenario.) When the conductive contact 208 contacts the corresponding lead contact 104, the corresponding battery pack is electrically connected to the inverter input terminal. At this point, power output can be realized (under normal circumstances, battery packs 1 to 6 are inserted into the corresponding battery pack support housing 101 cavities in numerical order). If the battery pack is damaged (including by explosion), the battery voltage will drop rapidly (or power will be cut off), causing the input terminal of the resistor group to be unable to supply power to the corresponding relay. At this time, the normally closed contact of the relay will close, such as... Figure 13 First, insert battery pack 1. At this time, relay KM1 is energized, so all normally closed contacts of KM1 will open. Then, insert the subsequent battery packs 2-6 (the output terminals of battery packs 2-6 will all be disconnected by the normally closed contact of relay KM1). If battery pack 1 fails (other battery packs fail randomly in sequence; since battery pack 1 is not failed, it still supplies power normally; this only describes the sequential failure), the normally closed contact of relay KM1 will close, causing the normally closed contact of relay KM2 corresponding to battery pack 2 to open momentarily. Therefore, the subsequent battery packs 3-6 will all be disconnected by the normally closed contact of relay KM2, and so on, until battery pack 6 fails.

[0031] When the battery pack explodes, it indicates damage to cell 206 within the corresponding battery pack. The explosion of cell 206 causes flames to erupt from its pressure relief valve. At this time, the flames are isolated by the intermediate baffle 204, reducing interference to other cells 206. The ejected flame airflow is guided by the guide plate 205 on the intermediate baffle 204, and the pressure is then transmitted to the nozzle 207. After passing through the nozzle 207 and unlocking the exhaust port 122, the one-way baffle 106 is pushed open (compressing the spring 107). The high-temperature, high-pressure gas ejected at this time passes through the back sealing pressure guide cover 108 and the air guide groove. 109. The gas pressure guide groove 111 and the sliding cavity 112 cause the sealing piston plate 116 in the sliding cavity 112 to slide under pressure, which causes the limiting pin 117 to compress the elastic gasket 115, separating the limiting pin 117 from the battery pack casing 201. At this time, the battery pack casing 201 is no longer restricted. Since the back sealing pressure guide cover 108 is in a sealed state, this will cause the battery pack casing 201 to be ejected from the cavity of the battery pack support casing 101 under pressure, causing the damaged and deflated battery pack to separate from the battery pack support casing 101 (other battery packs). The one-way baffle 106, which holds the unlocking exhaust port 122, acts as a one-way valve to prevent pressure from being transmitted to the corresponding cavities of other battery packs.

Claims

1. An outdoor lithium-ion UPS power supply, characterized in that: Includes a battery pack support housing (101), which has six independent cavities, each of which is slidably inserted into a battery pack. The battery pack includes a battery pack casing (201), and a reinforcing partition (202) and a middle baffle (204) are fixedly installed on the inner wall of the battery pack casing (201). Multiple cells (206) are provided on both sides of the middle baffle (204), and an aerogel pad is provided between two adjacent cells (206). The pressure relief valves of all cells (206) on both sides of the middle baffle (204) are all facing the middle baffle (204), and a guide plate (205) is provided on the surface of the middle baffle (204). A tail sealing cap (203) is also fixedly installed on the battery pack housing (201). The tail sealing cap (203) is used to encapsulate all the cells (206) on the inner wall of the battery pack housing (201), and all the cells (206) are fixedly installed on the inner wall of the battery pack housing (201). A nozzle (207) is fixedly installed in the middle of the tail sealing cap (203). The nozzle (207) is aligned with the middle baffle (204). A conductive contact (208) is also provided on the tail sealing cap (203). A limit pin sliding hole (102) is opened at the position of each cavity on the battery pack support housing (101). A limit pin (117) that is squeezed and rubbed against the battery pack housing (201) is slidably installed inside each limit pin sliding hole (102). The limit pin (117) is used to prevent the battery pack housing (201) from sliding out of the cavity. An insulating sealing backplate (103) is also fixedly installed on the battery pack support housing (101). The insulating sealing backplate (103) has six unlocking vent ports (122). Each unlocking vent port (122) is aligned with a corresponding nozzle (207). Each unlocking vent port (122) is equipped with a one-way baffle (106). The one-way baffle (106) can block the unlocking vent port (122). A back sealing pressure guide cover (108) is fastened to the outside of all unlocking vent ports (122). Air guide grooves (109) are opened on the upper and lower edges of the back sealing pressure guide cover (108). A drive plate (110) is fixedly installed on the upper and lower surfaces of the battery pack support housing (101). The drive plate (110) has three sliding cavities aligned with the sliding holes (102) of the limit pins. (112) An E-shaped gas pressure groove (111) is provided on the side of the drive plate (110) facing the battery pack support shell (101). The gas pressure groove (111) is used to connect the three sliding chambers (112) with the gas guide groove (109). A sealing piston plate (116) is slidably and sealed in the sliding chamber (112). The sealing piston plate (116) is fixedly engaged with the limiting pin (117). An unlocking pull block (114) is fixedly installed on each sealing piston plate (116). An elastic rubber pad limiting strip (113) is fixedly installed on the side of the drive plate (110) away from the battery pack support shell (101). An elastic rubber pad (115) is elastically provided between the elastic rubber pad limiting strip (113) and the limiting pin (117) for squeezing the limiting pin (117) to move toward the battery pack shell (201).

2. The outdoor lithium-ion UPS power supply according to claim 1, characterized in that: Multiple lead contacts (104) are fixedly installed on the insulating sealing back plate (103). The lead contacts (104) and the conductive contacts (208) are in contact and conductively connected. Each lead contact (104) is insulated and isolated from each other by the insulating sealing back plate (103).

3. An outdoor lithium-ion UPS power supply according to claim 2, characterized in that: Each one-way baffle (106) is fixedly installed with a one-way baffle guide slide (105). The one-way baffle guide slide (105) is slidably engaged with the back sealing pressure guide cover (108). A spring (107) is wrapped around the one-way baffle guide slide (105). The two ends of the spring (107) are fixedly engaged with the one-way baffle (106) and the back sealing pressure guide cover (108).

4. An outdoor lithium-ion UPS power supply according to claim 3, characterized in that: A housing buckle plate (121) is fixedly fastened on the drive plate (110). A shovel block limiting block (119) is fixedly installed on each drive plate (110) at the position of the sliding cavity (112). A shovel block (118) is overlapped on the shovel block limiting block (119). The shovel block (118) slides with the drive plate (110). The shovel block (118) is used to shovel up the unlocking pull block (114). The unlocking pull block (114) is provided with a groove. The shovel block (118) is provided with an inclined surface that slides with the groove on the unlocking pull block (114). An unlocking push-pull rod (120) is fixedly installed on each shovel block (118). The end of the unlocking push-pull rod (120) away from the shovel block (118) extends to the outside of the housing buckle plate (121).

5. An outdoor lithium-ion UPS power supply according to claim 4, characterized in that: The output terminals of the six battery packs are electrically connected to the input terminal of the inverter in parallel. A diode is installed in series between the output terminals of battery packs 1-5 and the input terminal of the inverter. The output terminals of battery packs 1-5 are all connected in parallel with the electromagnetic coils of the corresponding relays KM1-KM5.

6. An outdoor lithium-ion battery UPS power supply according to claim 5, characterized in that: A normally closed contact of relay KM1 is connected in series between the output terminal of battery pack 2 and relay KM2; normally closed contacts of relays KM2 and KM1 are connected in series between the output terminal of battery pack 3 and relay KM3; normally closed contacts of relays KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 4 and relay KM4; normally closed contacts of relays KM4, KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 5 and relay KM5; normally closed contacts of relays KM5, KM4, KM3, KM2, and KM1 are connected in series between the output terminal of battery pack 6 and the input terminal of the inverter.

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