Battery cell balancing device and control method thereof

Abstract

The present invention relates to a battery cell balancing device and a control method thereof. The purpose of the battery cell balancing device and the control method thereof according to the present invention is to efficiently maintain the charge balance of a battery cell, even while using a smaller number of elements than the prior art, by using a circuit structure of a bidirectional buck-boost converter and a bidirectional axis converter.

Description

Battery cell balancing device and control method thereof

[0001] The present invention relates to a battery cell balancing device and a control method thereof, and more particularly, to a battery cell balancing device and a control method thereof capable of maintaining charge balance between adjacent cells by simultaneously utilizing the structures of a buck-boost converter and a chuck converter.

[0002] Recently, lithium-ion batteries have been increasingly installed in electronic devices such as electric vehicles, satellites, electric bicycles, and Energy Storage Systems (ESS). Lithium-ion batteries are installed in a form where multiple battery modules, each composed of multiple lithium-ion battery cells, are connected. These lithium-ion batteries suffer from uneven charge capacity across each battery cell. This uneven charge capacity across cells affects the battery's capacity and lifespan. Therefore, to prevent this charge imbalance between cells, circuits and control methods are being developed to ensure uniform charge capacity across each battery cell.

[0003] To solve this problem, cell balancing devices using a bidirectional buck-boost converter or a bidirectional axial (Cuk) converter have been developed.

[0004] Fig. 1a illustrates a cell balancing circuit using a conventional bidirectional buck-boost converter, and Fig. 1b illustrates a cell balancing circuit using a conventional bidirectional axial converter.

[0005] A conventional cell balancing circuit using a bidirectional buck-boost converter uses six switch elements and three inductors to balance four battery cells, as illustrated in Fig. 1a. That is, when n is a positive integer value greater than or equal to 2, 4n-2 switch elements and 2n-1 inductors are used to balance 2n battery cells.

[0006] In addition, a cell balancing circuit using a conventional bidirectional axial converter uses six switching elements, five inductors, and three capacitors for balancing four battery cells, as illustrated in Fig. 1b. This means that when n has a positive integer value greater than or equal to 2, 4n-2 switching elements, 2n+1 inductors, and 2n-1 capacitors are used for balancing 2n battery cells.

[0007] In this way, in the case of a cell balancing circuit using a conventional bidirectional buck-boost converter and a cell balancing circuit using a conventional bidirectional axial converter, there is a problem in that many components are used to balance four battery cells.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] Patent Publication No. 10-2021-0060208 (Published on May 26, 2021)

[0011] The present invention has been devised to solve the above-mentioned problems, and the purpose of the battery cell balancing device and the control method thereof according to the present invention is to provide a battery cell balancing device and a control method thereof that can efficiently maintain charge balance of battery cells by using a circuit structure of a bidirectional buck-boost converter and a bidirectional axial converter while using a smaller number of components than the prior art.

[0012] In order to solve the above-described problem, a battery cell balancing device and a control method thereof according to the present invention are provided, in a battery cell balancing device sequentially connected to 1 to 2n battery cells (wherein n is an integer greater than or equal to 2) connected in series, comprising a controller for controlling 1 to 2n switch elements, 1 to n inductors, 1 to n-1 capacitors, and 1 to 2n switch elements, each of which has one end and the other end connected in series, wherein one end of the first switch element and the other end of the 2n switch element are respectively connected to the positive terminal of the first battery cell and the negative terminal of the 2n battery cell, and one end and the other end of an i-th inductor (wherein i is a positive integer less than or equal to n) which is one of the 1 to n inductors are respectively connected to a node where the 2i-1-th battery cell and the 2i-th battery cell are connected and a node where the 2i-1 switch element and the 2i-th switch element are connected, and a j-th capacitor (wherein j is n-1) which is one of the 1 to n-1 capacitors One end and the other end of the positive integer below are characterized in that they are connected to the other end of the j-th inductor and the other end of the j+1-th inductor, respectively.

[0013] In addition, when an odd-numbered switch element among the first to 2n switch elements is referred to as an odd-numbered switch element and an even-numbered switch element among the first to 2n switch elements is referred to as an even-numbered switch element, the controller is characterized in that it controls the first to 2n switch elements so that the odd-numbered switch elements and the even-numbered switch elements operate complementarily.

[0014] Additionally, the controller is characterized in that it controls the first to 2n switch elements so that the odd switch elements and the even switch elements have the same on-duty ratio.

[0015] Additionally, the controller is characterized in that it controls the first to 2n switch elements so that the first to 2n switch elements have a predetermined dead time.

[0016] In a control method of a battery cell balancing device according to one embodiment of the present invention, when an odd-numbered switch element among the first to 2n switch elements is referred to as an odd-numbered switch element and an even-numbered switch element among the first to 2n switch elements is referred to as an even-numbered switch element, the controller is characterized in that the odd-numbered switch element and the even-numbered switch element operate complementarily and control the first to 2n switch elements.

[0017] Additionally, the controller is characterized in that it controls the first to 2n switch elements so that the odd switch elements and the even switch elements have the same on-duty ratio.

[0018] Additionally, the controller is characterized in that it controls the first to 2n switch elements so that the first to 2n switch elements have a predetermined dead time.

[0019] According to the battery cell balancing device and control method thereof according to the present invention as described above, when n has a positive integer value of 2 or more, 2n switch elements, n inductors, and n-1 capacitors are used for cell balancing of 2n battery cells, so that 2n-2 fewer switch elements and n-1 fewer inductors can be used than in a cell balancing circuit using a conventional bidirectional buck-boost converter, and there is an effect of using 2n-2 fewer switch elements, n+1 fewer inductors, and n fewer capacitors than in a cell balancing circuit using a conventional bidirectional axial converter.

[0020] That is, there is an effect that battery cell balancing can be performed with fewer components than when using a cell balancing circuit using a conventional bidirectional buck-boost converter or bidirectional axial converter.

[0021] Fig. 1a is a circuit diagram illustrating a battery cell balancing circuit using a conventional buck-boost converter, and Fig. 1b is a circuit diagram illustrating a battery cell balancing circuit using a conventional axial converter.

[0022] Figure 2 is a schematic diagram of a battery cell balancing device according to an embodiment of the present invention having four battery cells.

[0023] Figure 3 is a circuit diagram of a battery cell balancing device according to an embodiment of the present invention having eight battery cells.

[0024] Figures 4a and 4b are timing diagrams for the first to 2n switch elements of the battery cell balancing device of the present invention.

[0025] FIGS. 5A and 5B are circuit diagrams showing a state in which the odd switch elements of a battery cell balancing device having eight battery cells of the present invention are turned on and the even switch elements are turned off.

[0026] FIGS. 6A and 6B are circuit diagrams illustrating a state in which the odd switch elements of a battery cell balancing device having eight battery cells of the present invention are turned off and the even switch elements are turned on.

[0027] The above-described objects, features, and advantages of the present invention will become more apparent through the following examples taken in conjunction with the accompanying drawings. The specific structural and functional descriptions below are merely illustrative for the purpose of explaining embodiments according to the concept of the present invention, and embodiments according to the concept of the present invention may be implemented in various forms and should not be construed as limited to the embodiments described in this specification or application. Since embodiments according to the concept of the present invention may have various modifications and may take various forms, specific embodiments are illustrated in the drawings and described in detail in this specification or application. However, this is not intended to limit embodiments according to the concept of the present invention to specific disclosed forms, but should be understood to include all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention. Terms such as first and / or second may be used to describe various components, but the components are not limited to the terms. Terms are used solely for the purpose of distinguishing one component from another, for example, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component, without departing from the scope of the rights according to the concept of the present invention. When a component is referred to as being connected or coupled to another component, it should be understood that it may be directly connected or coupled to that other component, but there may also be other components in between. Conversely, when a component is referred to as being directly connected or coupled to another component, it should be understood that there are no other components in between. Other expressions used to describe the relationship between components, such as "between" and "directly between" or "adjacent to" and "directly adjacent to", should be interpreted similarly.The terminology used herein is used solely to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. It should be understood that the terms "comprise" and "have" used herein indicate the presence of a described feature, number, step, operation, component, part, or combination thereof, and do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein. Hereinafter, the present invention will be described in detail by describing a preferred embodiment of the present invention with reference to the accompanying drawings. The same reference numerals in each drawing represent the same parts.

[0028] In the drawings attached to this specification, elements drawn with broken lines in the circuit diagram mean that they are OFF, and electrical paths drawn with broken lines in the circuit diagram mean that electricity does not flow through the corresponding path.

[0029] Hereinafter, with reference to the attached drawings, a preferred embodiment of a battery cell balancing device (1) and a control method thereof according to the present invention will be described in detail.

[0030] Figure 2 is a schematic diagram of a battery cell balancing device (1) according to an embodiment of the present invention having four battery cells.

[0031] The purpose of the battery cell balancing device (1) of the present invention is to balance the charge of first to 2n battery cells (2) that are sequentially connected in series, when n is an integer greater than or equal to 2. This means that the voltages between the first to 2n battery cells (2) become the same. Specifically, the first to 2n battery cells (2) may be battery cells made of lithium ion batteries. In particular, the number of battery cells that are the target of the battery cell balancing device (1) of the present invention is characterized in that it is an even number.

[0032] Next, each component of the battery cell balancing device (1) of the present invention will be described.

[0033] The battery cell balancing device (1) of the present invention includes first to 2n switch elements (110), first to n inductors (120), first to n-1 capacitors (130), and a controller (140) when n is an integer greater than or equal to 2.

[0034] The first to 2n switch elements (110) are sequentially connected in series at one end and the other end. Specifically, the first to 2n switch elements (110) are sequentially connected in series. The first to 2n switch elements (110) connected in this way have one end of the first switch element and the other end of the 2n switch element connected to the positive terminal of the first battery cell and the negative terminal of the 2n battery cell, respectively.

[0035] FIG. 2 illustrates a battery cell balancing device (1) according to an embodiment in which n is 2, i.e., there are 4 battery cells, and includes first to fourth switch elements (S1, S2, S3, S4). As illustrated in FIG. 2, one end of the first switch element (S1) is connected to the positive terminal of the first battery cell (V1), and the other end of the fourth switch element (S4) is connected to the negative terminal of the fourth battery cell (V4). Here, the first to 2n switch elements (110) may be transistors or relays.

[0036] One end and the other end of the i-th inductor (wherein i is a positive integer less than or equal to n) among the first to n inductors (120) are respectively connected to a node where the 2i-1-th battery cell and the 2i-th battery cell are connected and to a node where the 2i-1-th switch element and the 2i-th switch element are connected. That is, one inductor among the first to n inductors (120) is respectively connected to a node where the odd-numbered battery cell and the even-numbered battery cell are connected and to a node where the odd-numbered switch element and the even-numbered switch element are connected.

[0037] As illustrated in FIG. 2, when n is 2, a battery cell balancing circuit according to one embodiment includes first and second inductors (L1, L2). The first inductor (L1) is connected to a node where the first battery cell (V1) and the second battery cell (V2) are connected and to a node where the first switch element (S1) and the second switch element (S2) are connected. In addition, the second inductor (L2) is connected to a node where the third battery cell (V3) and the fourth battery cell (V4) are connected and to a node where the third switch element (S3) and the fourth switch element (S4) are connected.

[0038] When j is a positive integer less than or equal to n-1, one end and the other end of the jth capacitor, which is one of the first to n-1 capacitors (130), are respectively connected to the other end of the jth inductor and the other end of the j+1th inductor. That is, one of the first to n-1 capacitors (130) is connected between the other ends of two adjacent inductors.

[0039] As illustrated in FIG. 2, when n is 2, a battery cell balancing circuit according to one embodiment includes a first capacitor (C1). The first capacitor (C1) is connected to the other terminal of a first inductor (L1) and the other terminal of a second inductor (L2).

[0040] The controller (140) controls the first to 2n switch elements (110). The controller (140) may be a microcontroller unit. Specifically, when the first to 2n switch elements (110) are MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) among transistors, the controller (140) can control the first to 2n switch elements (110) to be turned on or off by applying a voltage to the gates of the first to 2n switch elements (110).

[0041] The controller (140) may be provided with a storage unit (not shown) to store a control method for controlling the first to 2n switch elements (110). That is, the controller (140) may control the first to 2n switch elements (110) using the control method stored in the storage unit (not shown).

[0042] Fig. 3 is a schematic diagram of a battery cell balancing device (1) of one embodiment having eight battery cells. When there are eight battery cells, this refers to the case where n is 4, and the device includes first to eighth battery cells (V1 to V8). In this case, the battery cell balancing device (1) includes first to eighth switch elements (S1 to S8), first to fourth inductors (L1, L2, L3, L4), first to third capacitors (C1, C2, C3), and a controller (140). As illustrated in Fig. 3, the battery cell balancing device (1) may have various embodiments depending on the number of battery cells, and is not limited to the circuits illustrated in Figs. 2 and 3. That is, since n is a positive integer greater than or equal to 2, if a total of 2n battery cells are provided, the battery cell balancing device (1) can include 2n switch elements, n inductors, and n-1 capacitors accordingly.

[0043] Next, a method for the controller (140) to control the battery cell balancing device (1) of the present invention will be described. Figures 4a and 4b are timing diagrams for a method for controlling the battery cell balancing device (1) of the present invention.

[0044] When the odd-numbered switch elements among the 1st to 2nth switch elements (110) are referred to as odd-numbered switch elements, and the even-numbered switch elements among the 1st to 2nth switch elements (110) are referred to as even-numbered switch elements, the controller (140) controls the 1st to 2nth switch elements (110) so that the odd-numbered switch elements and the even-numbered switch elements operate complementarily. Specifically, when the controller (140) turns on the odd-numbered switch elements, it turns off the even-numbered switch elements, and conversely, when it turns on the even-numbered switch elements, it turns off the odd-numbered switch elements. That is, the controller (140) does not turn on the odd-numbered and even-numbered switch elements at the same time, but controls only one of the odd-numbered or even-numbered switch elements to be turned on.

[0045] Referring to FIGS. 4a and 4b, when the on / off cycle of the first to 2n switch elements (110) is Ts, the controller (140) can control the odd switch elements to be turned on during the time (Todd) that the odd switch elements are turned on so that the odd switch elements are turned on. In this case, the controller (140) controls the even switch elements to be turned off during the time (Todd) that the odd switch elements are turned on. Conversely, referring to FIG. 4b, when the time (Todd) that the odd switch elements are turned on has elapsed, the controller (140) controls the odd switch elements to be turned off. Thereafter, the controller (140) can control the even switch elements to be turned on during the time (Teven) that the even switch elements are turned on so that the even switch elements are turned on. In this case, the controller (140) controls the odd switch elements to be turned off during the time (Teven) that the even switch elements are turned on.

[0046] In conclusion, the controller (140) can repeatedly control to turn on only one of the odd-numbered switch elements and the even-numbered switch elements.

[0047] The controller (140) controls the first to 2n switch elements (110) so that the odd switch elements and the even switch elements have the same on-duty ratio. Specifically, the controller (140) can control the first to 2n switch elements (110) so that the time at which the odd switch elements are turned on is the same as the time at which the even switch elements are turned on. For example, the odd switch elements and the even switch elements can have an on-duty ratio of 50%.

[0048] Referring to Figures 4a and 4b, the time at which the odd switch element turns on (Todd) and the time at which the even switch element turns on (Teven) can have the same value.

[0049] The controller (140) controls the first to 2n switch elements (110) so that the first to 2n switch elements (110) have a predetermined dead time. Specifically, the controller (140) controls the first to 2n switch elements (110) so that the first to 2n switch elements (110) have a dead time, which is a time during which all of the first to 2n switch elements (110) are turned off, when either the time for which the odd switch elements are turned on (Todd) or the time for which the even switch elements are turned on (Teven) has elapsed. This is because, when the first to 2n switch elements (110) are all turned on, the positive terminals of each odd-numbered battery cell and the negative terminals of each even-numbered battery cell are short-circuited, which generates a large current, which may cause a problem in which the first to 2n switch elements (110) are damaged. Meanwhile, the dead-time, which is the time during which all of the first to 2n switch elements (110) are turned off, may be less than the time during which the odd switch elements are turned on (Todd) or the time during which the even switch elements are turned on (Teven).

[0050] Referring to FIGS. 4a and 4b, as described above, the controller (140) can control the first to 2n switch elements (110) so that the time during which all of the first to 2n switch elements (110) are turned off has a dead time between the time at which the odd switch element is turned on (Todd) and the time at which the even switch element is turned on (Teven). In this case, the on / off cycle (Ts) of the first to 2n switch elements (110) can be a value that adds together the dead time before the odd switch element is turned on, the time at which the odd switch element is turned on (Todd), the dead time before the even switch element is turned on, and the time at which the even switch element is turned on (Teven).

[0051] In the case of the control method of the battery cell balancing device (1) of the present invention, since the controller (140) has substantially the same characteristics as controlling the first to 2n switch elements (110), the specific control method of the cell balancing device is omitted.

[0052] Next, the process of making the charges of the first to 2n battery cells (110) uniform according to the battery cell balancing device (1) and its control method will be described.

[0053] FIGS. 5a and 5b are circuit diagrams showing a state in which the odd switch elements of a battery cell balancing device (1) having eight battery cells of the present invention are turned on and the even switch elements are turned off.

[0054] First, a description will be given of a case where the controller (140) turns on odd switch elements and turns off even switch elements.

[0055] When the controller (140) turns on the odd-numbered switch elements, it turns off the even-numbered switch elements. Accordingly, the odd-numbered battery cells form a closed circuit with the inductor connected to the negative terminal via the odd-numbered switch elements. This closed circuit has the circuit structure of a buck-boost converter and operates as a buck-boost converter.

[0056] As illustrated in FIG. 5a, when N is 4, the first battery cell (V1) forms a closed circuit with the first inductor (L1) via the first switch element (S1), the third battery cell (V3) forms a closed circuit with the second inductor (L2) via the third switch element (S3), the fifth battery cell (V5) forms a closed circuit with the third inductor (L3) via the fifth switch element (S5), and the seventh battery cell (V7) forms a closed circuit with the fourth inductor (L4) via the seventh switch element (S7).

[0057] At the same time, the even-numbered battery cells, excluding the 2nth battery cell, form a closed circuit with the capacitor and the inductor connected to the positive terminal via the odd-numbered switch element connected to the negative terminal. This closed circuit has the circuit structure of an axial converter and operates as an axial converter.

[0058] As shown in FIG. 5b, when n is 4, the second battery cell (V2) forms a closed circuit with the third switch element (S3), the first capacitor (C1), and the first inductor (L1), the fourth battery cell (V4) forms a closed circuit with the fifth switch element (S5), the second capacitor (C2), and the second inductor (L2), and the sixth battery cell (V6) forms a closed circuit with the seventh switch element (S7), the third capacitor (C3), and the third inductor (L3).

[0059] In conclusion, when the controller (140) turns on the odd switch elements and turns off the even switch elements, the odd battery cells perform battery cell balancing using the circuit structure of the buck-boost converter, and the even battery cells, excluding the 2nth battery cell, perform battery cell balancing using the circuit structure of the axial converter.

[0060] A description will be given of a case where the controller (140) turns off odd switch elements and turns on even switch elements.

[0061] FIGS. 6A and 6B are circuit diagrams showing a state in which the odd switch elements of a battery cell balancing device (1) having eight battery cells of the present invention are turned off and the even switch elements are turned on.

[0062] When the controller (140) turns on the even-numbered switch elements, it turns off the odd-numbered switch elements. Accordingly, the even-numbered battery cells form a closed circuit with the inductor connected to the positive terminals via the even-numbered switch elements. This closed circuit has the circuit structure of a buck-boost converter and operates as a buck-boost converter.

[0063] As illustrated in FIG. 6a, when n is 4, the second battery cell (V2) forms a closed circuit with the first inductor (L1) via the second switch element (S2), the fourth battery cell (V4) forms a closed circuit with the second inductor (L2) via the fourth switch element (S4), the sixth battery cell (V6) forms a closed circuit with the third inductor (L3) via the sixth switch element (S6), and the eighth battery cell (V8) forms a closed circuit with the fourth inductor (L4) via the eighth switch element (S8).

[0064] At the same time, odd-numbered battery cells, excluding the first battery cell (V1), form a closed circuit with the capacitor and the inductor connected to the negative terminal via the even-numbered switch element connected to the positive terminal. This closed circuit has the circuit structure of an axial converter and operates as an axial converter.

[0065] As shown in FIG. 6b, when n is 4, the third battery cell (V3) forms a closed circuit with the second switch element (S2), the first capacitor (C1), and the second inductor (L2), the fifth battery cell (V5) forms a closed circuit with the fourth switch element (S4), the second capacitor (C2), and the third inductor (L3), and the seventh battery cell (V7) forms a closed circuit with the sixth switch element (S6), the third capacitor (C3), and the fourth inductor (L4).

[0066] In conclusion, when the controller (140) turns off the odd-numbered switch elements and turns on the even-numbered switch elements, the odd-numbered battery cells, excluding the first battery cell (V1), perform battery cell balancing using the circuit structure of the axial converter, and the even-numbered battery cells perform battery cell balancing using the circuit structure of the buck-boost converter.

[0067] The controller (140) can maintain charge balance between the first to 2n battery cells (2) by repeating the aforementioned process several times.

[0068] In conclusion, when using the battery cell balancing device (1) of the present invention and its control method, there is an effect of being able to effectively perform cell balancing using a smaller number of elements than conventional cell balancing devices.

[0069] The technical concept of the present invention should not be construed solely based on the above-described embodiments. The scope of application is diverse, and various modifications and variations are possible within the scope of those skilled in the art without departing from the spirit of the invention as claimed in the claims. Therefore, such improvements and modifications, as long as they are obvious to those skilled in the art, fall within the scope of protection of the present invention.

[0070] [Explanation of symbols]

[0071] 1: Battery cell balancing device

[0072] 110: 1st to 2nth switch elements

[0073] 120: 1st to nth inductors

[0074] 130: 1st to n-1st capacitors

[0075] 140: Controller

[0076] 2: 1st to 2n battery cells

[0077] Ts: On-off cycle of the 1st to 2nth switch elements

[0078] Todd: The time it takes for an odd switch element to turn on

[0079] Teven: The time at which an even switch element turns on.

[0080] V1 ~ V8: 1st battery cell ~ 8th battery cell

[0081] S1 ~ S8: 1st switch element ~ 8th switch element

[0082] C1 ~ C3: 1st capacitor ~ 3rd capacitor

[0083] L1 ~ L4: 1st inductor ~ 4th inductor

Claims

1. In a battery cell balancing device connected to 1 to 2n battery cells (wherein n is an integer greater than or equal to 2) connected in series in sequence, 1 to 2n switch elements, each connected in series at one end and the other end in sequence; 1st to nth inductor; 1st to n-1st capacitors; and A controller for controlling the first to 2n switch elements; One end of the first switch element and the other end of the second n switch element are respectively connected to the positive terminal of the first battery cell and the negative terminal of the second n battery cell, One end and the other end of the i-th inductor (wherein, i is a positive integer less than or equal to n) among the first to n inductors are respectively connected to the node where the 2i-1-th battery cell and the 2i-th battery cell are connected and to the node where the 2i-1-th switch element and the 2i-th switch element are connected. One end and the other end of the jth capacitor (wherein j is a positive integer less than or equal to n-1) among the first to n-1 capacitors are connected to the other end of the jth inductor and the other end of the j+1th inductor, respectively. A battery cell balancing device featuring:

2. In paragraph 1, Among the above 1st to 2n switch elements, the odd-numbered switch elements are called odd-numbered switch elements. When the even-numbered switch elements among the above 1st to 2n switch elements are called even-numbered switch elements, The above controller Controlling the first to 2n switch elements so that the odd switch elements and the even switch elements operate complementarily. A battery cell balancing device featuring:

3. In paragraph 2, The above controller Controlling the first to 2n switch elements so that the odd switch elements and the even switch elements have the same on-duty ratio. A battery cell balancing device featuring:

4. In paragraph 2, The above controller Controlling the first to 2n switch elements so that the first to 2n switch elements have a predetermined dead time. A battery cell balancing device featuring:

5. A method for controlling a battery cell balancing device including the features of paragraph 1, Among the above 1st to 2n switch elements, the odd-numbered switch elements are called odd-numbered switch elements. When the even-numbered switch elements among the above 1st to 2n switch elements are called even-numbered switch elements, The above controller, The above odd switch elements and the above even switch elements operate complementarily and control the first to 2n switch elements. A method for controlling a battery cell balancing device, characterized by:

6. In paragraph 5, The above controller, Controlling the first to 2n switch elements so that the odd switch elements and the even switch elements have the same on-duty ratio. A method for controlling a battery cell balancing device, characterized by:

7. In paragraph 5, The above controller, Controlling the first to 2n switch elements so that the first to 2n switch elements have a predetermined dead time. A method for controlling a battery cell balancing device, characterized by:

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