Battery system and power transmission method using same

Abstract

The invention relates to a battery system and a power transmission method using the same. A battery system includes a battery pack and a battery management system (BMS) that receives an auxiliary voltage from an AUX-ray, selects a first power path or a second power path from the auxiliary voltage to a plurality of driving elements according to a level of the auxiliary voltage, and supplies power to the plurality of driving elements through the selected one power path, in which the BMS includes: a switching element that switches the auxiliary voltage to the plurality of driving elements; a power source including a first line for forming a first power path, a second line for forming a second power path, a first stage supplied with an auxiliary voltage, a second stage connected to the first line, and a third stage connected to the second line; and a buck-boost element for reducing the voltage supplied through the second line.

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority based on Korean Patent Application No. 10-2022-0177519 filed in the Korean Intellectual Property Office on December 16, 2022, and all contents disclosed in the Korean patent application document are incorporated as a part of this specification.

[0003] The present disclosure relates to a battery system and a power transmission method using the battery system. Background Art

[0004] The voltage provided from the auxiliary (AUX) terminal of the vehicle may be 12 V or 24 V. Conventional battery systems may be divided into a system corresponding to 12 V and a system corresponding to 24 V.

[0005] A separate element may be provided in a path based on each voltage level so as to perform classification on a system corresponding to each voltage level as described above. Therefore, a battery management system (BMS) including elements for each voltage level may have a large number of elements, which may result in insufficient space on a board or require a board for each voltage level. Summary of the invention

[0006] Technical issues

[0007] The present disclosure seeks to provide a battery system for determining a power path through which a voltage is delivered to various elements based on a voltage level input from an auxiliary (AUX) terminal, and a power delivery method using the same.

[0008] Technical Solution

[0009] According to one embodiment, a battery system is provided, which includes: a battery pack; and a battery management system BMS, the BMS receives an auxiliary voltage from an auxiliary AUX line, selects one of a first power path and a second power path from the auxiliary voltage to a plurality of driving elements based on the level of the auxiliary voltage, and provides power to the plurality of driving elements through the selected one power path, wherein the BMS includes: a first line, the first line configures the first power path; a second line, the second line configures the second power path; a switching element, the switching element including a first end provided with the auxiliary voltage, a second end connected to the first line, and a third end connected to the second line; and a buck-boost element, the buck-boost element reduces the voltage provided through the second line.

[0010] The BMS may further include a main control unit MCU generating a switch control signal based on a signal indicating the noise filtered voltage from the auxiliary voltage, and the switch element may connect the first terminal to the second terminal or connect the first terminal to the third terminal based on the switch control signal.

[0011] The BMS may further include an analog-to-digital converter ADC which performs analog-to-digital conversion on the filtered voltage to generate a voltage signal indicating a level of the filtered voltage and transmits the generated signal to the MCU.

[0012] Each of the plurality of driving elements may be driven at a voltage level of a first voltage, and when the filtered voltage has a level corresponding to the first voltage, the MCU may generate a switch control signal of a first level, and the switch element may connect the second end to the first end.

[0013] When the filtered voltage has a level corresponding to the second voltage, the MCU can generate a switching control signal of the second level, the switching element can connect the third end to the first end, and the buck-boost element can output a voltage of a level corresponding to the first voltage by reducing the voltage provided via the second line, and provide the output voltage to multiple driving elements.

[0014] According to another embodiment, a power transmission method is provided, which includes the following steps: a battery management system BMS receives an auxiliary voltage from an auxiliary AUX line of a vehicle; the BMS selects one of a first power path and a second power path from the auxiliary voltage to a plurality of driving elements based on the level of the auxiliary voltage, and the plurality of driving elements are driven at a voltage level of the first voltage; the BMS connects a first end to a second end or connects the first end to a third end based on selection by using a switching element, the switching element including a first end provided with the auxiliary voltage, a second end connected to a first line configuring the first power path, and a third end connected to a second line configuring the second power path; so as to provide power to the plurality of driving elements through the selected one power path.

[0015] The step of selecting one of the first power path and the second power path may include: performing analog-to-digital conversion on a noise filtered voltage from the auxiliary voltage to generate a voltage signal indicating a level of the filtered voltage; and generating a switch control signal based on the voltage signal.

[0016] In the method, when the filtered voltage has a level corresponding to the first voltage, the switch control signal has a first level, and the method may further include connecting the second terminal to the first terminal through the switch element based on the switch control signal.

[0017] In the method, when the filtered voltage has a level corresponding to the second voltage, the switch control signal has a second level, and the method may further include connecting the third terminal to the first terminal through the switch element based on the switch control signal.

[0018] The method further includes the steps of: outputting, by the buck-boost element, a voltage of a level corresponding to the first voltage by stepping down a voltage supplied via the second line; and supplying, by the buck-boost element, the output voltage to a plurality of driving elements.

[0019] Beneficial Effects

[0020] According to the present disclosure, a 12V system and a 24V system may be implemented as one battery management system (BMS) mounted on one board, and the 12V system and the 24V system may be flexibly used only by managing a bill of materials (BOM).

[0021] According to the present disclosure, both the 12V system and the 24V system can use one board design, and thus the BMS can be designed independently of the 12V or 24V AUX system provided by the vehicle terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a block diagram schematically showing a battery system according to an embodiment.

[0023] Figure 2 A power path is shown when a first auxiliary voltage is provided from an auxiliary (AUX) line.

[0024] Figure 3 The power path is shown when a second auxiliary voltage is provided from an auxiliary (AUX) line.

[0025] Figure 4 is a flow chart of a method for power delivery using a battery system according to another embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, the embodiments disclosed in the specification will be described in detail with reference to the accompanying drawings, and the same or similar components are represented by the same or similar figure marks, and their repeated descriptions are omitted. The terms "module" and / or "unit" of the components described in the following description are only used to make the specification easy to understand. Therefore, these terms themselves do not have meanings or functions that distinguish one from another. In addition, when describing the embodiments of the present disclosure, when it is determined that the detailed description of the known technology related to the present disclosure may blur the main points, the detailed description is omitted. In addition, it should be understood that the drawings are provided only to make the embodiments of the present disclosure easy to understand, and the spirit of the present disclosure is not limited to the drawings, and includes all modifications, equivalents and substitutions within the spirit and scope of the present disclosure.

[0027] Terms including ordinal numbers (such as "first", "second", etc.) may be used to describe various components. However, these components are not limited by these terms. These terms are only used to distinguish one component from another component.

[0028] It should be understood that the terms "including", "having", etc. used in the present application specify the existence of the features, quantities, steps, operations, components, parts or a combination thereof mentioned in the specification, and do not exclude the existence or possible addition of one or more other features, quantities, steps, operations, components, parts or a combination thereof.

[0029] According to an embodiment, a program implemented as a set of instructions containing a control algorithm necessary for controlling another configuration may be installed in a configuration for controlling another configuration under specific control conditions among a plurality of configurations. The control configuration may process input data and stored data based on the installed program to generate output data. The control configuration may include a non-volatile memory for storing the program and a memory for storing data.

[0030] Figure 1 is a block diagram schematically showing a battery system according to an embodiment.

[0031] Reference Figure 1 , the battery system 1 may include a battery pack 100 , a battery management system (BMS) 200 , a main relay 300 , a pre-charge relay 310 , and a current sensor 400 .

[0032] The battery pack 100 may be implemented as two or more battery cells connected in series to each other, a plurality of battery cells connected in series to each other in which two or more battery cells are connected in parallel to each other, or two or more battery cells connected in parallel to each other.

[0033] One end of the pre-charge relay 310 may be connected to one end of the main relay 300, and the other end of the pre-charge relay 310 may be connected to the other end of the main relay 300. One end of each of the main relay 300 and the pre-charge relay 310 may be connected to the battery pack 100, and the other end of each of the main relay 300 and the pre-charge relay 310 may be connected to at least one component of the external device 2.

[0034] The BMS 200 may include an input filter 201, an analog-to-digital converter (ADC) 202, a switching element 203, a buck-boost element 204, and a plurality of driving elements 205 to 208, and a main control unit (MCU) 209. The plurality of driving elements 205 to 208 are respective examples of elements that operate to control charging and discharging of the battery pack 100.

[0035] The BMS 200 may receive an auxiliary voltage from an auxiliary (AUX) line, determine a power path connecting the auxiliary voltage to the plurality of driving elements 205 to 208 based on a level of the auxiliary voltage, and provide power to the plurality of driving elements 205 to 208 through lines of the power path.

[0036] BMS200 may include at least one AUX line. For example, the auxiliary voltage of the vehicle may be provided through the AUX line. Hereinafter, for ease of explanation, the specification describes providing one of the first auxiliary voltage V1 and the second auxiliary voltage V2 through the AUX line. The second auxiliary voltage V2 may be higher than the first auxiliary voltage V1. For example, the first auxiliary voltage V1 may be 12V, and the second auxiliary voltage V2 may be 24V.

[0037] The input filter 201 may filter the voltage provided by the AUX line. One end of the input filter 201 may be connected to the AUX line, and the other end of the input filter 201 may be connected to one end of the switch element 203 through the output line LN_FT. The input filter 201 may be implemented as an inductor or a capacitor, and any of various known noise removal filters may be applied to the input filter 201. The voltage passed through the input filter 201 may be delivered to the switch element 203 through the output line LN_FT. The output line LN_FT may be a line providing a power source path from the output end of the input filter 201 to one end of the switch element 203.

[0038] One end of the ADC 202 may be connected to the node N_FT on the output line LN_FT, and the other end of the ADC 202 may be connected to the MCU 209. The ADC 202 may generate a voltage signal VS by analog-to-digital converting a signal indicating a voltage at the node N_FT. The voltage signal VS may be a signal indicating a level of a voltage output from the input filter 201.

[0039] The plurality of driving elements 205 to 208 may include at least one of a main relay driver 205, a precharge relay driver 206, a current sensor regulator 207, and a system basis chip (SBC) 208. A voltage level of power required to operate the plurality of driving elements 205 to 208 may be a voltage level of the first auxiliary voltage V1. Figure 1 The plurality of driving elements are shown as a main relay driver 205, a pre-charge relay driver 206, a current sensor regulator 207, and an SBC 208. However, the present disclosure is not limited thereto. For example, the plurality of driving elements may include a high voltage interlock connector (HVIL).

[0040] The main relay driver 205 may control driving of the main relay 300. Opening and closing of the main relay 300 may be controlled by a main relay control signal CTR_REL provided from the MCU 209. The main relay driver 205 may provide a main relay driving voltage V_REL to the main relay 300, which opens or closes the main relay 300 based on the main relay control signal CTR_REL.

[0041] The precharge relay driver 206 may control the driving of the precharge relay 310. The opening and closing of the precharge relay 310 may be controlled by a precharge relay control signal CTR_PRE provided from the MCU 209. The precharge relay driver 206 may provide the precharge relay 310 with a precharge relay driving voltage V_PRE, which opens or closes the precharge relay 310 based on the precharge relay control signal CTR_PRE.

[0042] The current sensor regulator 207 may provide a driving voltage V_CS to the current sensor 400, which measures the current flowing in the high voltage path to which the battery pack 100 is connected. The current sensor 400 may be provided on a high voltage line connected from the battery pack 100 to both ends P+ and P- of the battery system 1. For example, when an excessive current flows in the high voltage path, a short circuit may occur in the battery pack, and the MCU 209 may detect this phenomenon by monitoring the current information obtained by the current sensor 400. The current sensor 400 may be implemented as a resistance detection type sensor that detects current by using a resistor or a magnetic field detection type sensor that detects a magnetic field.

[0043] The SBC 208 may provide power to the MCU 209. The SBC 208 may generate a driving voltage 5V_PWR of the MCU 209 and provide it to the MCU 209.

[0044] The switch element 203 may include a first terminal N_SW1 , a second terminal N_SW2 , and a third terminal N_SW3 .

[0045] The first terminal N_SW1 of the switch element 203 may be connected to the node N_FT through an output line LN_FT.

[0046] The first line LN1 may be a line providing a power path from the output of the input filter 201 to a node N1 connected to one end of each of the plurality of driving elements 205 to 208. One end of the first line LN1 may be connected to the second end N_SW2 of the switching element 203, and the other end of the first line LN1 may be connected to the node N1.

[0047] The second line LN2 may be a line providing a power path from the output of the input filter 201 to the buck-boost element 204. One end of the second line LN2 may be connected to the third end N_SW3 of the switch element 203, and the other end of the second line LN2 may be connected to one end of the buck-boost element 204.

[0048] The MCU 209 may generate a switch control signal CTR_SW based on a voltage signal VS received from a node N_FT through the ADC 202. The MCU 209 may select a power path from the first auxiliary voltage V1 or the second auxiliary voltage V2 to the plurality of driving elements 205 to 208 through the switch control signal CTR_SW. The MCU 209 may select one of a first power path configured by the first line LN1 and a second power path configured by the second line LN2. When the voltage signal VS has a level corresponding to the first auxiliary voltage V1, the MCU 209 may generate a switch control signal CTR_SW of a first level. When the voltage signal VS has a level corresponding to the second auxiliary voltage V2, the MCU 209 may generate a switch control signal CTR_SW of a second level.

[0049] When the switch control signal CTR_SW has a first level, the switch element 203 may connect the output line LN_FT of the input filter 201 to the first line LN1. When the switch control signal CTR_SW has a second level, the switch element 203 may connect the output line LN_FT of the input filter 201 to the second line LN2. The BMS 200 may supply power to the plurality of driving elements 205 to 208 through one power path selected from a first power path configured by the first line LN1 and a second power path configured by the second line LN2.

[0050] The configuration of the buck-boost element 204 and the boost method and the buck method of the buck-boost element 204 are not particularly limited. When a voltage corresponding to the second auxiliary voltage V2 is provided to the buck-boost element 204 through the second line, the buck-boost element 204 can be operated. The buck-boost element 204 can output a voltage of a level corresponding to the first auxiliary voltage by reducing the voltage input through the second line LN2. The other end of the buck-boost element 204 can be connected to a line connected to the plurality of driving elements 205 to 208 through a node N1.

[0051] Power may be supplied to the plurality of driving elements 205 to 208 through the first line LN1 or the buck-boost element 204 .

[0052] The main relay driver 205 can use the power voltage provided through the node N1 as its driving voltage. When the main relay control signal CTR_REL provided by the MCU 209 is an on-level signal, the main relay driver can generate a main relay driving voltage V_REL by using the power voltage provided via the node N1, and close the main relay 300 by providing the main relay driving voltage V_REL to the main relay 300.

[0053] The pre-charge relay driver 206 can use the power provided through the node N1 as its driving voltage. When the pre-charge relay control signal CTR_PRE provided by the MCU 209 is an on-level signal, the pre-charge relay driver can generate a pre-charge relay driving voltage V_PRE by using the power source voltage provided via the node N1, and close the pre-charge relay 310 by providing the pre-charge relay driving voltage V_PRE to the pre-charge relay 310.

[0054] The current sensor regulator 207 may provide a driving voltage V_CS required to operate the current sensor 400 by converting a power voltage provided through the node N1 into a voltage of a level suitable for the current sensor 400 .

[0055] The SBC 208 may generate a voltage of 5V_PWR based on power supplied through the node N1 and supply it to the MCU 209 .

[0056] Figure 1 One node N1 is shown. However, the present disclosure is not limited thereto. The BMS 200 may include two or more nodes connected to the first line LN1 and the other end of the buck-boost element 204, and the plurality of driving elements 205 to 208 may be connected to the first line or the other end of the buck-boost element 204 through the two or more nodes.

[0057] The battery system 1 can be connected to an external device 2. The external device 2 may include a load or a charging device such as an inverter or a converter. When the external device 2 is a charger, both ends P+ and P- of the battery system 1 can be connected to the charger, and the charger provides power for charging. When the external device 2 is a load, both ends P+ and P- of the battery system 1 can be connected to the load, so that the power provided by the battery pack 100 can be discharged through the load.

[0058] In the following, the description refers to Figure 2 and Figure 3 Describes the power path of the voltage supplied from the AUX line.

[0059] Figure 2A power path is shown when a first auxiliary voltage is provided from an auxiliary (AUX) line.

[0060] Reference Figure 2 , when the first auxiliary voltage V1 is provided to the AUX line, the input filter 201 can deliver the noise filtered voltage from the first auxiliary voltage V1 to the switching element 203 through the output line LN_FT. The ADC 202 can send a voltage signal VS to the MCU 209, which is a digital conversion of the voltage at the node N_FT on the output line LN_FT.

[0061] The voltage signal VS may have a level corresponding to the first auxiliary voltage V1 , and the MCU 209 may thus generate a switch control signal CTR_SW of a first level and transmit it to the switch element 203 .

[0062] The switch element 203 receiving the first level switch control signal CTR_SW may connect the first terminal N_SW1 to the second terminal N_SW2, thereby connecting the output line LN_FT of the input filter 201 to the first line LN1. The first line LN1 may be connected to lines connected to the plurality of driving elements 205 to 208 through the node N1.

[0063] Therefore, the first auxiliary voltage V1 supplied to the AUX line may be supplied to the plurality of driving elements 205 to 208 through the output line LN_FT of the input filter 201 , the first line LN1 , and the node N1 .

[0064] Figure 3 The power path when the second auxiliary voltage is supplied from the AUX line is shown.

[0065] Reference Figure 3 When the second auxiliary voltage V2 is provided to the AUX line, the input filter 201 can deliver the noise filtered voltage from the second auxiliary voltage V2 to the switch element 203 through the output line LN_FT. The ADC 202 can send a voltage signal VS to the MCU 209, which is a digital conversion of the voltage at the node N_FT on the output line LN_FT.

[0066] The voltage signal VS may have a level corresponding to the second auxiliary voltage V2 , and the MCU 209 may thus generate a switch control signal CTR_SW of a second level and transmit it to the switch element 203 .

[0067] The switch element 203 receiving the switch control signal CTR_SW of the second level may connect the first terminal N_SW1 to the third terminal N_SW3 , thereby connecting the output line LN_FT of the input filter 201 to the second line LN2 . The second line LN2 may be connected to the buck-boost element 204 .

[0068] The buck-boost element 204 can be operated by the voltage input through the second line LN2, and can increase or decrease the input voltage to output a voltage of a level corresponding to the first auxiliary voltage. The output terminal of the buck-boost element 204 can be connected to the line connected to the plurality of driving elements 205 to 208 through the node N1. For example, when the first auxiliary voltage V1 is 12V and the second auxiliary voltage V2 is 24V, the buck-boost element 204 can decrease the input voltage corresponding to 24V and output a voltage of 12V.

[0069] Therefore, the second auxiliary voltage V2 supplied to the AUX line may be supplied to the plurality of driving elements 205 to 208 through the output line LN_FT of the input filter 201 , the second line LN2 , the buck-boost element 204 , and the node N1 .

[0070] Figure 4 is a flow chart of a method for power delivery using a battery system according to another embodiment.

[0071] Hereinafter, in the description of the various components of the battery management system (BMS) 200 , descriptions of components overlapping with the description provided above may be omitted.

[0072] Reference Figure 4 , the BMS 200 may receive an auxiliary voltage provided from an auxiliary (AUX) line ( S100 ).

[0073] The input filter 201 may filter the input auxiliary voltage ( S200 ).

[0074] The analog-to-digital converter (ADC) 202 may generate a voltage signal VS by analog-to-digital converting a signal indicating a voltage at a node N_FT on an output line LN_FT of the input filter 201 ( S300 ).

[0075] The main control unit (MCU) 209 can select a path from the first auxiliary voltage V1 to multiple driving elements 205 to 208 or a path from the second auxiliary voltage V2 to multiple driving elements 205 to 208 as one of the first power path and the second power path through a switching control signal CTR_SW, and provide power to the multiple driving elements 205 to 208 through the selected power path.

[0076] The MCU 209 may receive the voltage signal VS from the ADC 202 to determine whether the voltage signal VS has a level corresponding to the first auxiliary voltage V1 or a level corresponding to the second auxiliary voltage V2 ( S400 ).

[0077] When the voltage signal VS has a level corresponding to the first auxiliary voltage V1 in step S400 , the MCU 209 may generate a switch control signal of a first level and transmit it to the switch element 203 ( S500 ).

[0078] The switch element 203 receiving the switch control signal of the first level may connect the first terminal N_SW1 with the second terminal N_SW2 and deliver power to the plurality of driving elements 205 to 208 through the first line LN1 ( S600 ).

[0079] When the voltage signal VS has a level corresponding to the second auxiliary voltage V2 in step S400 , the MCU 209 may generate a switch control signal of a second level and transmit it to the switch element 203 ( S700 ).

[0080] The switch element 203 receiving the switch control signal of the second level may connect the first terminal N_SW1 with the third terminal N_SW3 and transmit power to the buck-boost element 204 through the second line LN2 ( S800 ).

[0081] The buck-boost element 204 may step down power and output a voltage of a level corresponding to the first auxiliary voltage ( S900 ).

[0082] The output voltage of the buck-boost element 204 may be delivered to the plurality of driving elements 205 to 208 ( S1000 ). The plurality of driving elements 205 to 208 may be driven using the output voltage of the buck-boost element 204 as a driving voltage.

[0083] In this way, based on the switch control signal received from the MCU 209 , the switch element 203 can supply power to the plurality of driving elements 205 to 208 through the line of the power path determined by the MCU 209 among the first line LN1 and the second line LN2 .

[0084] Although the embodiments of the present disclosure are described in detail above, the scope of the present disclosure is not limited thereto. Various modifications and improvements made by those skilled in the art to which the present disclosure belongs also belong to the scope of the present disclosure.

Claims

1. A battery system, comprising: Battery pack; as well as a battery management system BMS, the BMS receiving an auxiliary voltage from an auxiliary AUX line, selecting one of a first power path and a second power path from the auxiliary voltage to a plurality of driving elements based on a level of the auxiliary voltage, and providing power to the plurality of driving elements through the selected one power path, Wherein, the BMS comprises: a first circuit, the first circuit configuring the first power path; a second circuit, the second circuit configuring the second power path; a switching element including a first terminal supplied with the auxiliary voltage, a second terminal connected to the first line, and a third terminal connected to the second line; and A buck-boost element is provided to reduce a voltage provided through the second line.

2. The battery system according to claim 1, wherein: The BMS further includes a main control unit MCU that generates a switch control signal based on a signal indicating a noise filtered voltage from the auxiliary voltage, and The switch element connects the first end to the second end or connects the first end to the third end based on the switch control signal.

3. The battery system according to claim 2, wherein: The BMS further includes an analog-to-digital converter ADC which performs analog-to-digital conversion on the filtered voltage to generate a voltage signal indicating a level of the filtered voltage and transmits the generated signal to the MCU.

4. The battery system according to claim 2, wherein: Each of the plurality of driving elements is driven at a voltage level of a first voltage, When the filtered voltage has a level corresponding to the first voltage, the MCU generates a switch control signal of a first level, and The switching element connects the second end to the first end.

5. The battery system according to claim 4, wherein: When the filtered voltage has a level corresponding to the second voltage, the MCU generates a switch control signal of a second level, The switch element connects the third terminal to the first terminal, and The buck-boost element outputs a voltage of a level corresponding to the first voltage by stepping down a voltage supplied via the second line, and supplies the output voltage to the plurality of driving elements.

6. A method for transmitting electric power, the method comprising the following steps: The battery management system BMS receives the auxiliary voltage from the auxiliary AUX line of the vehicle; selecting, by the BMS, one of a first power path and a second power path from the auxiliary voltage to a plurality of driving elements based on the level of the auxiliary voltage, the plurality of driving elements being driven at a voltage level of the first voltage; by the BMS, connecting the first end to the second end or connecting the first end to the third end based on the selection by using a switching element, the switching element including the first end supplied with the auxiliary voltage, the second end connected to the first line configuring the first power path, and the third end connected to the second line configuring the second power path; as well as Power is supplied to the plurality of driving elements through the selected one power path.

7. The power transmission method according to claim 6, wherein: The step of selecting one of the first power path and the second power path comprises the following steps: performing analog-to-digital conversion on a noise filtered voltage from the auxiliary voltage to generate a voltage signal indicative of a level of the filtered voltage; and A switch control signal is generated based on the voltage signal.

8. The power transmission method according to claim 7, wherein: When the filtered voltage has a level corresponding to the first voltage, the switch control signal has a first level, The power transmission method further includes the step of connecting the second end to the first end by the switching element based on the switch control signal.

9. The power transmission method according to claim 7, wherein: When the filtered voltage has a level corresponding to the second voltage, the switch control signal has a second level, The power transmission method further includes the step of connecting the third end to the first end by the switching element based on the switch control signal.

10. The power transmission method according to claim 9, further comprising the following steps: outputting a voltage of a level corresponding to the first voltage by reducing the voltage provided via the second line through the buck-boost element; as well as The output voltage is provided by the buck-boost element to the plurality of driving elements.

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