Battery pack, multi-battery dynamic parallel control circuit and control method

Abstract

The invention relates to a battery pack, a multi-battery dynamic parallel control circuit and a control method, the multi-battery dynamic parallel control circuit comprises at least two battery packs, and each battery pack comprises a battery pack, a current sensor, a relay, a first MOS tube, a second MOS tube and a control unit. And the control unit is connected with a coil of the relay, a grid electrode of the first MOS tube and a grid electrode of the second MOS tube, and is used for controlling the on-off states of the relay, the first MOS tube and the second MOS tube according to a control instruction to realize charging and discharging of the battery pack. The multi-battery dynamic parallel control technology is utilized, even if the voltage difference between the batteries is large, dynamic parallel connection of the batteries can be achieved in the operation process of the electric equipment, the operation efficiency of the batteries is improved, and the matching difficulty of the batteries is reduced.

Description

Technical Field

[0001] The present invention relates to the field of battery technology in the field of new energy, and in particular to a battery pack, a multi-battery dynamic parallel control circuit and a control method. Background Art

[0002] For application scenarios such as electric two-wheelers, electric three-wheelers, electric four-wheelers, and small and medium-sized lithium battery energy storage, multiple small-capacity, lightweight standard battery packs are usually used. Multiple battery packs are connected in parallel, in series, or in a combination of parallel and series to power the electrical equipment. Especially for battery replacement application scenarios, standard battery packs are usually small battery packs that can be quickly replaced. One or more battery packs can be combined in different ways to meet the needs of different electrical equipment.

[0003] When using batteries in parallel, since there are often voltage differences between multiple batteries and the internal resistance of the batteries is relatively small, if they are directly connected in parallel, the high-voltage battery will charge the low-voltage battery with a large current, which will not only affect the battery life and energy efficiency, but may also cause damage to electrical components in the circuit and even lead to safety accidents.

[0004] In the existing technology, multiple batteries can be connected in parallel through power converters, by judging the voltage difference between batteries when the system is powered on, or by controlling the current limiting resistor. The disadvantages of these parallel connection methods are that they are either complex to control and costly; or can only be connected in parallel under specific usage conditions and working conditions; or are only applicable to low-power electrical equipment.

[0005] Therefore, it is necessary to improve the existing multi-batteries, control circuits and control methods. Summary of the invention

[0006] In view of this, it is necessary to provide a battery pack, a multi-battery dynamic parallel control circuit and a control method to solve the problems that the multi-battery parallel control scheme in the prior art is complex, costly, and only applicable to specific scenarios.

[0007] In order to solve the above technical problems, in a first aspect, the present invention provides a battery pack, comprising: A battery pack, comprising a battery pack positive electrode and a battery pack negative electrode, wherein the battery pack positive electrode is connected to a battery pack positive terminal; A current sensor, a first end of which is connected to the negative electrode of the battery pack; A relay, wherein a first contact thereof is connected to the second end of the current sensor, and a second contact thereof is connected to the negative terminal of the battery pack; A first MOS tube, a source of which is connected to the second end of the current sensor; a second MOS transistor, whose source is connected to the second contact of the relay and whose drain is connected to the drain of the first MOS transistor; A control unit is connected to the coil of the relay, the gate of the first MOS tube and the gate of the second MOS tube, and is used to control the on and off states of the relay, the first MOS tube and the second MOS tube according to a control instruction to realize the charging and discharging of the battery pack.

[0008] In a possible implementation, a fuse is further included, and the fuse is arranged between the positive electrode of the battery pack and the positive terminal of the battery pack.

[0009] In a possible implementation, a collection unit is further included, and the collection unit is connected to the battery pack and the current sensor, and is used to collect the voltage value and the current value of the battery pack.

[0010] In a possible implementation, the second MOS transistor is replaced by a first diode, a positive terminal of the first diode is connected to the second contact of the relay, and a negative terminal of the first diode is connected to the drain of the first MOS transistor.

[0011] In a second aspect, the present invention further provides a multi-battery dynamic parallel control circuit, comprising at least two groups of battery packs, wherein the battery packs are the battery packs mentioned above.

[0012] In a possible implementation, the at least two battery packs are combined in parallel, or first in parallel and then in series, or first in series and then in parallel.

[0013] In a third aspect, the present invention further provides a control method, which is applied to the above-mentioned multi-battery dynamic parallel control circuit, and the control method comprises: Determine whether the voltage difference between batteries in the battery pack is less than or equal to a preset voltage value; If it is less than or equal to, the relays controlling each battery are closed to achieve direct parallel connection; If it is greater than, the high-voltage battery and the low-voltage battery are controlled separately to achieve dynamic parallel connection of multiple batteries.

[0014] In a possible implementation, high-voltage batteries and low-voltage batteries are controlled separately to realize dynamic parallel connection of multiple batteries, including: For high voltage batteries, close the relay to make it the direct main power supply for discharge; For a low-voltage battery, the first MOS tube is closed to make it an indirect auxiliary power supply for discharge.

[0015] In a possible implementation, high-voltage batteries and low-voltage batteries are controlled separately to realize dynamic parallel connection of multiple batteries, and the method further includes: During the discharge process of the high-voltage battery and the low-voltage battery, the voltages of the high-voltage battery and the low-voltage battery gradually approach each other, the low-voltage battery gradually participates in the discharge through the second MOS tube, and the discharge current gradually increases; Determine that the discharge current of the low-voltage battery is greater than or equal to a preset current value and the duration is greater than a preset time; If so, the low-voltage battery closes the relay, and its discharge current no longer passes through the first MOS tube and the second MOS tube, completing the parallel control of multiple batteries.

[0016] In a possible implementation, the second MOS transistor is replaced by the first diode.

[0017] The beneficial effects of the present invention are as follows: the present invention combines the advantages of mechanical switches and electronic switches, and has the advantages of low cost, small size, simple control, high reliability, high safety, high efficiency, and wide application range. In addition, for battery replacement application scenarios, the multi-battery dynamic parallel control technology is used, and even if the voltage difference between the batteries is large, the batteries can be dynamically connected in parallel during the operation of the electrical equipment, which improves the efficiency of battery operation and reduces the difficulty of battery matching. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 A circuit structure diagram of a first embodiment of a battery pack provided by the present invention; Figure 2 A circuit structure diagram of a second embodiment of a battery pack provided by the present invention; Figure 3 A circuit structure diagram of a first embodiment of a multi-battery dynamic parallel control circuit provided by the present invention; Figure 4 A schematic flow chart of an implementation of a control method for a multi-battery dynamic parallel control circuit provided by the present invention. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0021] The descriptions of "first", "second", etc. involved in the embodiments of the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the technical features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0022] The "embodiment" provided herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] In order to solve the above technical problems, the present invention provides a battery pack, see Figure 1 ,include: A battery pack, comprising a battery pack positive electrode and a battery pack negative electrode, wherein the battery pack positive electrode is connected to a battery pack positive terminal; A current sensor, a first end of which is connected to the negative electrode of the battery pack; A relay, wherein a first contact thereof is connected to the second end of the current sensor, and a second contact thereof is connected to the negative terminal of the battery pack. Preferably, the relay may also be placed at the positive terminal of the battery pack; A first MOS transistor (ie, MOS transistor 1), whose source is connected to the second end of the current sensor; A second MOS transistor (ie, MOS transistor 2), whose source is connected to the second contact of the relay, and whose drain is connected to the drain of the first MOS transistor; A control unit is connected to the coil of the relay, the gate of the first MOS tube and the gate of the second MOS tube, and is used to control the on and off states of the relay, the first MOS tube and the second MOS tube according to a control instruction to realize the charging and discharging of the battery pack.

[0024] It should be noted that relays (mechanical switches), MOS tube 1 and MOS tube 2 (electronic switches) are used as control execution elements. MOS tube 1 mainly realizes indirect parallel transition control of battery discharge, and MOS tube 2 mainly realizes indirect parallel transition control of battery charge.

[0025] During the parallel discharge process, MOS tube 1 is closed and MOS tube 2 is opened, and the discharge current flows through the internal diode of MOS tube 2 and MOS tube 1.

[0026] During the parallel charging process, MOS tube 2 is closed and MOS tube 1 is disconnected, and the charging current flows through the internal diode of MOS tube 1 and MOS tube 2.

[0027] Preferably, the MOS tube 1 and the MOS tube 2 are respectively a single MOS tube or multiple MOS tubes of the same type connected in parallel.

[0028] Preferably, MOS transistor 1 and MOS transistor 2 may also be a parallel combination of a mechanical switch and a diode respectively.

[0029] Similarly, the combination of relay and MOS tube can also be placed at the positive electrode of the battery pack. It needs to be explained that the use of relays (mechanical switches) as control actuators is suitable for high-power batteries. Generally, mechanical switches have higher voltage and current tolerance than electronic switches, but they are larger in size, heavier in weight, have higher driving power, and can be switched less frequently. The use of MOS tubes (electronic switches) as control actuators is suitable for low-power batteries. Compared with mechanical switches, electronic switches have weaker voltage and current tolerance, but they are smaller in size, lighter in weight, have lower driving power, faster control response speed, and can be switched more frequently.

[0030] In an embodiment of the present invention, a fuse and a collection unit are further included, wherein the fuse is arranged between the positive electrode of the battery pack and the positive terminal of the battery pack. The collection unit is connected to the battery pack and the current sensor to collect the voltage value and current value of the battery pack.

[0031] In the embodiments of the present invention, please refer to Figure 2 , the second MOS tube is replaced by a first diode, the positive terminal of the first diode is connected to the second contact of the relay, and the negative terminal of the first diode is connected to the drain of the first MOS tube.

[0032] Specifically, a relay (mechanical switch), MOS tube 1 (electronic switch) and diode 1 are used as control actuators. For application scenarios like battery replacement, a single battery pack is usually placed in a charging cabinet for charging, and then a single or multiple batteries are taken out and combined to power the electrical equipment. In this case, the battery parallel connection only needs to consider the discharge parallel connection. At this time, Figure 1 The MOS tube 2 can be in the disconnected state all the time, and only the unidirectional conductivity of its internal diode is used. Since the forward conduction voltage drop of the internal diode of the MOS tube is usually large, the loss when the current flows is large, and the temperature rises, so Figure 2 A diode 1 with a lower forward voltage drop is used to replace Figure 1 MOS tube 2 in the circuit to reduce its loss and temperature rise.

[0033] The MOS tube 1 is a single one, or multiple MOS tubes of the same type are connected in parallel. Optionally, the MOS tube 1 can also be a mechanical switch with the same function. The diode 1 is a single one, or multiple diodes of the same type are connected in parallel. Similarly, the combination of the relay, MOS tube and diode can also be placed at the positive pole of the battery pack.

[0034] In order to realize multi-battery parallel control, the present invention also provides a multi-battery dynamic parallel control circuit, please refer to Figure 3 , which includes at least two groups of battery packs, and the battery packs are the battery packs mentioned above.

[0035] Specifically, the charging and discharging of the battery pack is achieved by connecting the at least two battery packs mentioned above using a reasonable positive and negative pole connection method, and controlling the on and off states of the relay, the first MOS tube and the second MOS tube (the first diode) according to control instructions.

[0036] In a possible implementation manner, the at least two battery packs are combined in parallel, or first in parallel and then in series, or first in series and then in parallel.

[0037] Furthermore, the present invention also provides a control method, which is applied to the above-mentioned multi-battery dynamic parallel control circuit, please refer to Figure 4 , the control method comprises: Determine whether the voltage difference between batteries in the battery pack is less than or equal to a preset voltage value; If it is less than or equal to, the relays controlling each battery are closed to achieve direct parallel connection; If it is greater, the high-voltage battery and the low-voltage battery are controlled separately to achieve dynamic parallel connection of multiple batteries.

[0038] In a possible implementation, high-voltage batteries and low-voltage batteries are controlled separately to realize dynamic parallel connection of multiple batteries, including: For high voltage batteries, close the relay to make it the direct main power supply for discharge; For a low-voltage battery, the first MOS tube is closed to make it an indirect auxiliary power supply for discharge.

[0039] In a possible implementation, high-voltage batteries and low-voltage batteries are controlled separately to realize dynamic parallel connection of multiple batteries, and the method further includes: During the discharge process of the high-voltage battery and the low-voltage battery, the voltages of the high-voltage battery and the low-voltage battery gradually approach each other, the low-voltage battery gradually participates in the discharge through the second MOS tube, and the discharge current gradually increases; Determine that the discharge current of the low-voltage battery is greater than or equal to a preset current value and the duration is greater than a preset time; If so, the low-voltage battery closes the relay, and its discharge current no longer passes through the first MOS tube and the second MOS tube, completing the parallel control of multiple batteries.

[0040] In a possible implementation, the second MOS transistor is replaced by the first diode.

[0041] In summary, the beneficial effects of the present invention are as follows: the present invention combines the advantages of mechanical switches and electronic switches, and has the advantages of low cost, small size, simple control, high reliability, high safety, high efficiency, and wide application range. In addition, for battery replacement application scenarios, the multi-battery dynamic parallel control technology is used, and even if the voltage difference between the batteries is large, the batteries can be dynamically connected in parallel during the operation of the electrical equipment, which improves the efficiency of battery operation and reduces the difficulty of battery matching.

[0042] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A battery pack, characterized in that: include: A battery pack, comprising a battery pack positive electrode and a battery pack negative electrode, wherein the battery pack positive electrode is connected to a battery pack positive terminal; A current sensor, a first end of which is connected to the negative electrode of the battery pack; A relay, wherein a first contact thereof is connected to the second end of the current sensor, and a second contact thereof is connected to the negative terminal of the battery pack; A first MOS tube, a source of which is connected to the second end of the current sensor; a second MOS transistor, whose source is connected to the second contact of the relay and whose drain is connected to the drain of the first MOS transistor; A control unit is connected to the coil of the relay, the gate of the first MOS tube and the gate of the second MOS tube, and is used to control the on and off states of the relay, the first MOS tube and the second MOS tube according to a control instruction to realize the charging and discharging of the battery pack.

2. The battery pack according to claim 1, characterized in that: A fuse is also included, and the fuse is arranged between the positive electrode of the battery group and the positive terminal of the battery pack.

3. The battery pack according to claim 1, characterized in that: It also includes a collection unit, which is connected to the battery pack and the current sensor and is used to collect the voltage value and current value of the battery pack.

4. The battery pack according to any one of claims 1 to 3, characterized in that: The second MOS tube is replaced by a first diode, the positive terminal of the first diode is connected to the second contact of the relay, and the negative terminal of the first diode is connected to the drain of the first MOS tube.

5. A multi-battery dynamic parallel control circuit, characterized in that: It comprises at least two groups of battery packs, and the battery pack is the battery pack as described in any one of claims 1-4.

6. The multi-battery dynamic parallel control circuit according to claim 5, characterized in that: The at least two battery packs are combined in parallel, or first in parallel and then in series, or first in series and then in parallel.

7. A control method, characterized in that: Applied to the multi-battery dynamic parallel control circuit according to any one of claims 5 to 6, the control method comprises: Determine whether the voltage difference between batteries in the battery pack is less than or equal to a preset voltage value; If it is less than or equal to, the relays controlling each battery are closed to achieve direct parallel connection; If it is greater than, the high-voltage battery and the low-voltage battery are controlled separately to achieve dynamic parallel connection of multiple batteries.

8. The control method according to claim 7, characterized in that: Control high-voltage batteries and low-voltage batteries separately to achieve dynamic parallel connection of multiple batteries, including: For high voltage batteries, close the relay to make it the direct main power supply for discharge; For a low-voltage battery, the first MOS tube is closed to make it an indirect auxiliary power supply for discharge.

9. The control method according to claim 8, characterized in that: According to the high voltage battery and low voltage battery, the battery can be controlled separately to realize dynamic parallel connection of multiple batteries, and also includes: During the discharge process of the high-voltage battery and the low-voltage battery, the voltages of the high-voltage battery and the low-voltage battery gradually approach each other, the low-voltage battery gradually participates in the discharge through the second MOS tube, and the discharge current gradually increases; Determine that the discharge current of the low-voltage battery is greater than or equal to a preset current value and the duration is greater than a preset time; If so, the low-voltage battery closes the relay, and its discharge current no longer passes through the first MOS tube and the second MOS tube, completing the parallel control of multiple batteries.

10. The control method according to claim 9, characterized in that: The second MOS tube is replaced by the first diode.

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