Wireless charging system, wireless charging method, and electric vehicle

Abstract

A wireless charging system according to the present invention includes a first power receiving device connected in parallel with a first battery and including a first sub-resonance circuit having a first resonance frequency, a second power receiving device connected in parallel with a second battery and including a second sub-resonance circuit having a second resonance frequency, and a power transmitting device. The power transmitting device is configured to determine a charging order between the first battery and the second battery. If the first battery is selected according to the charging order, the power transmitting device wirelessly transmits first alternating-current power having the first resonance frequency to the first sub-resonance circuit. If the second battery is selected according to the charging order, the power transmitting device wirelessly transmits second alternating-current power having the second resonance frequency to the second sub-resonance circuit.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a technology of wirelessly charging a battery using magnetic resonance. BACKGROUND

[0002] Recently, the demand for portable electronic products such as laptop computers, camcorders, and mobile phones has rapidly increased, and as electric vehicles, energy storage batteries, robots, and satellites are widely developed, much research has been conducted on high-performance batteries that are repeatedly charged and discharged.

[0003] Currently, commercial batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, and the like, and among them, lithium batteries have little or no memory effect, and thus lithium batteries are gaining more attention than nickel-based batteries because they can be charged at a convenient time, have a very low self-discharge rate, and have a high energy density.

[0004] Generally, a battery pack includes a plurality of batteries connected in series. In order to individually charge the plurality of batteries, a power reception device needs to be provided to each battery.

[0005] Conventionally, in order to wirelessly transmit alternating current (AC) charging power in a one-to-one relationship to a plurality of power reception devices, a plurality of power transmission devices are installed in a wireless charging system. For example, in order to individually charge 10 batteries, 10 power reception devices and 10 power transmission devices are needed.

[0006] In addition, in order to efficiently perform wireless charging of a plurality of batteries, battery information (e.g., voltage, etc.) of each battery needs to be monitored. To this end, a wireless communication circuit of the power reception device transmits the battery information to a wireless communication circuit of the power transmission device, and the power transmission device controls charging of each battery based on the received battery information.

[0007] However, manufacturing a wireless charging system including a plurality of power reception devices and a plurality of power transmission devices each equipped with a wireless communication circuit requires a high cost, and the volume and weight of the entire wireless charging system increase. In addition, when a communication error occurs in the wireless communication circuit provided in the power reception device and / or the power transmission device, battery information cannot be transmitted and received. SUMMARY

[0008] TECHNICAL PROBLEM

[0009] The present disclosure is designed to solve the above problems, and thus the present disclosure aims to provide a wireless charging system, a wireless charging method, and an electric vehicle in which a single power transmission device individually wirelessly transmits an alternating current charging current to a plurality of power reception devices using magnetic resonance.

[0010] The present disclosure also aims to provide a wireless charging system, a wireless charging method, and an electric vehicle in which battery information of a battery connected to a power receiving device is acquired (estimated) based on a voltage and a current of alternating current (AC) power wirelessly transmitted to the power receiving device without wireless communication of a power transmitting device with the power receiving device.

[0011] These and other objects and advantages of the present disclosure can be understood from the following description, and will be apparent from the embodiments of the present disclosure. Also, it will be easily understood that the objects and advantages of the present disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0012] Technical Solution

[0013] A wireless charging system according to one aspect of the present disclosure includes a first power receiving device connected in parallel with a first battery and including a first sub-resonance circuit having a first resonance frequency, a second power receiving device connected in parallel with a second battery and including a second sub-resonance circuit having a second resonance frequency, and a power transmitting device including a main resonance circuit. The power transmitting device is configured to determine a charging order between the first battery and the second battery in an initial charging mode. The power transmitting device is configured to wirelessly transmit, through the main resonance circuit, first alternating current (AC) power having the first resonance frequency to the first sub-resonance circuit when the first battery is selected according to the charging order in the normal charging mode. The power transmitting device is configured to wirelessly transmit, through the main resonance circuit, second AC power having the second resonance frequency to the second sub-resonance circuit when the second battery is selected according to the charging order in the normal charging mode.

[0014] The first sub-resonance circuit can include a first sub-coil and a first sub-capacitor connected in series. The second sub-resonance circuit can include a second sub-coil and a second sub-capacitor connected in series.

[0015] The first power receiving device can further include a first rectification circuit configured to convert the first AC power received by the first sub-resonance circuit into first direct current (DC) power and to supply the first DC power to the first battery.

[0016] The second power receiving device can further include a second rectification circuit configured to convert the second AC power received by the second sub-resonance circuit into second DC power and to supply the second DC power to the second battery.

[0017] The power transmitting device can be configured to wirelessly transmit the first AC power during a first primary time in the initial charging mode. The power transmitting device can be configured to record first primary sensing information indicating an AC voltage and an AC current of the first AC power. The power transmitting device can be configured to wirelessly transmit a first auxiliary power having a first auxiliary frequency during a first auxiliary time. The power transmitting device can be configured to record first auxiliary sensing information indicating an AC voltage and an AC current of the first auxiliary power. The power transmitting device can be configured to determine a first DC voltage of the first battery based on the first primary sensing information and the first auxiliary sensing information. The power transmitting device can be configured to wirelessly transmit a second DC power during a second primary time. The power transmitting device can be configured to record second primary sensing information indicating an AC voltage and an AC current of the second AC power. The power transmitting device can be configured to wirelessly transmit a second auxiliary power having a second auxiliary frequency during a second auxiliary time. The power transmitting device can be configured to record second auxiliary sensing information indicating an AC voltage and an AC current of the second auxiliary power. The power transmitting device can be configured to determine a second DC voltage of the second battery based on the second primary sensing information and the second auxiliary sensing information. The power transmitting device can be configured to determine a charging order between the first battery and the second battery based on the first DC voltage and the second DC voltage.

[0018] The power transmitting device can further include a power generation circuit configured to selectively provide the first AC power, the first auxiliary power, the second AC power, and the second auxiliary power to a primary resonant circuit, a sensing circuit configured to sense an AC voltage and an AC current of the AC power provided to the primary resonant circuit, and a control circuit operably coupled to the primary resonant circuit, the power generation circuit, and the sensing circuit.

[0019] The primary resonant circuit can include a primary coil and a variable capacitor connected in series. The control circuit can be configured to adjust a capacitance of the variable capacitor to be equal to one of a first primary capacitance, a first auxiliary capacitance, a second primary capacitance, and a second auxiliary capacitance that are different from each other.

[0020] The first resonant frequency can be equal to a resonant frequency of a primary inductance of the primary coil and the first primary capacitance. The first auxiliary frequency can be equal to a resonant frequency of the primary inductance and the first auxiliary capacitance. The second resonant frequency can be equal to a resonant frequency of the primary inductance and the second primary capacitance. The second auxiliary frequency can be equal to a resonant frequency of the primary inductance and the second auxiliary capacitance.

[0021] An electric vehicle according to another aspect of the present disclosure can include a wireless charging system.

[0022] The wireless charging method according to still another aspect of the disclosure is for a first battery connected in parallel with a first sub-resonant circuit having a first resonant frequency and a second battery connected in parallel with a second sub-resonant circuit having a second resonant frequency. The wireless charging method includes the steps of: determining a charging order between the first battery and the second battery in an initial charging mode; in a normal charging mode, when the first battery is selected according to the charging order, wirelessly transmitting first alternating current (AC) power having the first resonant frequency to the first sub-resonant circuit; and in the normal charging mode, when the second battery is selected according to the charging order, wirelessly transmitting second AC power having the second resonant frequency to the second sub-resonant circuit.

[0023] The step of determining the charging order can include the steps of wirelessly transmitting first AC power during a first main time, recording first main sensing information indicating an AC voltage and an AC current of the first AC power, wirelessly transmitting first auxiliary power having a first auxiliary frequency during a first auxiliary time, recording first auxiliary sensing information indicating an AC voltage and an AC current of the first auxiliary power, determining a first DC voltage of the first battery based on the first main sensing information and the first auxiliary sensing information, wirelessly transmitting second AC power during a second main time, recording second main sensing information indicating an AC voltage and an AC current of the second AC power, wirelessly transmitting second auxiliary power having a second auxiliary frequency during a second auxiliary time, recording second auxiliary sensing information indicating an AC voltage and an AC current of the second auxiliary power, determining a second DC voltage of the second battery based on the second main sensing information and the second auxiliary sensing information, and determining the charging order between the first battery and the second battery based on the first DC voltage and the second DC voltage.

[0024] Advantageous Effects

[0025] According to at least one embodiment of the disclosure, a single power transmission device can individually transmit an alternating current charging current to a plurality of power reception devices using magnetic resonance.

[0026] In addition, according to at least one of the embodiments of the disclosure, battery information of a battery connected to a power reception device can be acquired (estimated) based on a voltage and a current of alternating current (AC) power wirelessly transmitted to the power reception device without wireless communication of the power transmission device with each power reception device.

[0027] Effects of the disclosure are not limited to the above-mentioned effects, and those skilled in the art can clearly understand these and other effects from the attached claims. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the present disclosure given below, serve to provide further understanding of the technical aspects of the present disclosure, and therefore the present disclosure should not be construed as being limited to the accompanying drawings.

[0029] Figure 1 is a diagram exemplarily showing a configuration of an electric vehicle according to an embodiment of the present disclosure.

[0030] Figure 2 is a diagram exemplarily showing a configuration of a power transmitting device and a power receiving device of Figure 1 .

[0031] Figure 3 is a diagram exemplarily showing a configuration of a variable capacitor of Figure 2 .

[0032] Figure 4 is a diagram exemplarily showing an equivalent circuit of a power transmitting device and a power receiving device of Figure 1 in a phasor form.

[0033] Figure 5 is a flowchart exemplarily showing a wireless charging method according to a first embodiment of the present disclosure.

[0034] Figure 6 is a flowchart exemplarily showing a wireless charging method according to a second embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be interpreted as being limited to general and dictionary meanings but interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor defines suitable terms in order to best explain the idea of the present disclosure.

[0036] Therefore, the embodiments described herein and the examples shown in the drawings are merely preferred embodiments of the present disclosure, but are not intended to completely describe the technical aspects of the present disclosure, and thus it should be understood that various other equivalents and modifications can be made thereto at the time of filing the application.

[0037] The terms including ordinal numbers such as "first," "second," or the like are used to distinguish one element from another element among various elements but are not intended to limit the elements by the terms.

[0038] Unless the context clearly indicates otherwise, it will be understood that the term "comprise" as used in the specification, specifies the presence of stated elements but does not preclude the presence or addition of one or more other elements.

[0039] Also, throughout the specification, it will be further understood that when an element is referred to as being "connected to" another element, it can be directly connected to the other element, or intervening elements can be present.

[0040] Figure 1 is a diagram illustrating a configuration of an electric vehicle 1 according to an embodiment of the present disclosure, Figure 2 is a diagram exemplarily illustrating Figure 1 a configuration of a power transmitting device 200 and a power receiving device 300, and Figure 3 is a diagram exemplarily illustrating Figure 2 a configuration of a variable capacitor 212.

[0041] Referring to Figures 1 to 3 , the electric vehicle 1 includes a vehicle controller 2, a relay 10, an inverter 20, a motor 30, a battery pack 40, and a wireless charging system 100.

[0042] The vehicle controller 2 is configured to generate a key-on signal in response to a user switching an ignition button (not shown) provided in the electric vehicle 1 to an ON position. The vehicle controller 2 is configured to generate a key-off signal in response to the user switching the ignition button to an OFF position.

[0043] The relay 10 is installed on a power supply line for the battery pack 40. The on-off of the relay 10 can be controlled by the vehicle controller 2 and / or the wireless charging system 100. When the relay 10 is in an on state, power can be transmitted from any one of the battery pack 40 and the inverter to the other.

[0044] The inverter 20 converts direct current (DC) power provided from the battery pack 40 into alternating current (AC) power and provides it to the motor 30. The motor 30 converts the AC power from the inverter 20 into kinetic energy for the electric vehicle 1. The motor can be, for example, a single-phase induction motor or a three-phase induction motor.

[0045] The battery pack 40 includes a plurality of batteries B1 to B n n is a natural number of 2 or more. The batteries B are not limited to a specific type and include any type of battery capable of repeated charging and discharging (e.g., a lithium-ion battery).

[0046] The wireless charging system 100 includes a power transmitting device 200 and a plurality of power receiving devices 3001 to 300 n .

[0047] The plurality of power receiving devices 3001 to 300 n are connected in parallel with the plurality of batteries B1 to B n in a one-to-one relationship. That is, when i is a natural number of 1 to n, the power receiving device 300i The battery B i is connected in parallel.

[0048] The i-th power receiving device 300 i is configured to wirelessly receive AC power in the i-th range wirelessly transmitted from the power transmitting device 200 through magnetic resonance. The i-th power receiving device 300 i uses the received AC power to charge the i-th battery B i .

[0049] The power transmitting device 200 is configured to wirelessly transmit AC power individually to a plurality of power receiving devices 3001~300 n . That is, in order to charge the i-th battery B i , the power transmitting device 200 can select the i-th resonance frequency from the i-th resonance frequency to the n-th resonance frequency, and generate AC power having the selected i-th resonance frequency.

[0050] Referring to Figure 2 , the i-th power receiving device 300 i has an i-th sub-resonance circuit 310 i . The i-th sub-resonance circuit 310 i has an i-th resonance frequency. That is, when the frequency of the AC power transmitted by the power transmitting device 200 matches the i-th resonance frequency, the i-th sub-resonance circuit 310 i is in a state of maximum magnetic resonance. As the difference between the frequency of the AC power transmitted by the power transmitting device 200 and the i-th resonance frequency increases, the magnetic resonance of the i-th sub-resonance circuit 310 i gradually decreases.

[0051] The i-th sub-resonance circuit 310 i includes an i-th sub-coil 311 i and an i-th sub-capacitor 312 i connected in series. When f i is the i-th resonance frequency, L S_i is the inductance of the i-th sub-coil 311 i and C S_i is the capacitance of the i-th sub-capacitor 312 i , f i = 1 / {2π×(C S_i × L S_i ) 0.5}.

[0052] The i-th power receiving device 300 i may further include an i-th rectification circuit 320 i . The i-th rectification circuit 320 imay be a diode bridge circuit including four diodes. The i-th rectifier circuit 320 i includes a pair of input terminals and a pair of output terminals. The i-th rectifier circuit 320 i The pair of input terminals of the i-th rectifier circuit 320 i are connected to the first terminal and the second terminal of the i-th sub-resonant circuit 310 i The pair of output terminals of the i-th rectifier circuit 320 i are connected to the first terminal (e.g., a positive electrode terminal) and the second terminal (e.g., a negative electrode terminal) of the i-th battery B

[0053] The power transmission device 200 includes a main resonant circuit 210. The main resonant circuit 210 includes a main coil 211 and a variable capacitor 212 connected in series. A control circuit 240 is configured to adjust the capacitance of the variable capacitor 212 among a first main capacitance to an n-th main capacitance and a first auxiliary capacitance to an n-th auxiliary capacitance. That is, the capacitance of the variable capacitor 212 can be selected from the first main capacitance to the n-th main capacitance and the first auxiliary capacitance to the n-th auxiliary capacitance.

[0054] The resonance frequency of the main resonant circuit 210 can be adjusted to match the frequency of the AC power supplied to the main resonant circuit 210. Therefore, the AC power generated by the main resonant circuit 210 can be wirelessly received by at least one of a plurality of power receiving devices 3001~300 n with the i-th resonance frequency. For example, when the AC power of the i-th resonance frequency is input to the main resonant circuit 210, the resonance frequency of the main resonant circuit 210 can be adjusted to match the i-th resonance frequency. Therefore, the AC power having the i-th resonance frequency can be transmitted to the i-th sub-resonant circuit 310 i .

[0055] The power transmission device 200 can further include a power generation circuit 220. The power generation circuit 220 is configured to convert input DC power V IN from a DC voltage source (e.g., a lead-acid battery) provided in an electric vehicle 1 or a charging station into AC power having a desired frequency. A well-known single-phase full-bridge inverter and / or an oscillator can be used as the power generation circuit 220.

[0056] The frequency of the AC power generated by the power generation circuit 220 can be selected from a first resonance frequency to an n-th resonance frequency and a first auxiliary frequency to an n-th auxiliary frequency. The AC power having the selected frequency can be wirelessly transmitted to at least one of a plurality of power receiving devices 3001~300 n as a charging signal through the main resonant circuit 210.

[0057] The power transmission device 200 can further include a sensing circuit 230. The sensing circuit 230 includes a voltage sensor 231 and a current sensor 232. The sensing circuit 230 is configured to sense an AC voltage and an AC current of the AC power supplied to the main resonance circuit 210, and transmit a signal indicating the sensed information to the control circuit 240.

[0058] The power transmission device 200 can further include a control circuit 240. The control circuit 240 is operatively coupled to at least one of the main resonance circuit 210, the power generation circuit 220, or the sensing circuit 230. The operative coupling refers to a connection capable of signal transmission and reception in one or both directions.

[0059] The control circuit 240 can be implemented in hardware using at least one of an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions. The control circuit 240 can include an embedded memory. The memory can include at least one type of storage medium such as a flash memory type, a hard disk type, a solid state disk (SSD) type, a silicon disk driver (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read only memory (ROM), an electrically erasable programmable read only memory (EEPROM), or a programmable read only memory (PROM). The memory can store data and programs required for a computing operation of the control circuit 240. The control circuit 240 can store data indicating a result of a computing operation in the memory.

[0060] The control circuit 240 can control the power generation circuit 220 and the main resonance circuit 210 to match the frequency of the AC power generated by the power generation circuit 220 to the frequency of the main resonance circuit 210. For example, when one of the first to nth different resonance frequencies and the first to nth different auxiliary frequencies is selected, the control circuit 240 can match the frequency of the AC power generated by the power generation circuit 220 and the resonance frequency of the main resonance circuit 210 to the selected frequency.

[0061] Referring to Figure 3 The variable capacitor 212 includes a selection switch 213 and a capacitor circuit 214 connected in series. The capacitor circuit 214 can include first to nth main capacitors 215 n and first to nth auxiliary capacitors 216 n In the present specification, the capacitance of the ith main capacitor 215 i is referred to as an "ith main capacitance", and the capacitance of the ith auxiliary capacitor 216i The capacitor is called the "i-th auxiliary capacitor".

[0062] Assume L M It is the inductance of the main coil 211, C M_i It is the i-th main capacitor, C A_i It is the i-th auxiliary capacitor. When selector switch 213 selects the i-th main capacitor 215 i At that time, the frequency of the AC power wirelessly transmitted from the main resonant circuit 210 is 1 / {2π×(C M_i ×L M ) 0.5}, and equal to the i-th resonant frequency. When selector switch 213 selects the i-th auxiliary capacitor 216 i At that time, the frequency of the AC power wirelessly transmitted from the main resonant circuit 210 is 1 / {2π×(C A_i ×L M ) 0.5}, and equal to the i-th auxiliary frequency.

[0063] Among the first resonant frequency to the nth resonant frequency, the i-th auxiliary frequency and the i-th resonant frequency can have a minimum difference. For example, the difference between any two of the first resonant frequency to the nth resonant frequency can be greater than a predetermined value, and the difference between the i-th auxiliary frequency and the i-th resonant frequency can be less than a predetermined value. Therefore, in the first sub-resonant circuit 3101 to the nth sub-resonant circuit 310 n Among them, the magnetic resonance of the i-th auxiliary electric field is in the i-th resonant circuit 310 i The largest in the middle.

[0064] In response to multiple batteries B1 to B n Before entering the normal charging mode, multiple batteries B1 to B can be used to determine the charging mode. n The initial charging mode of the charging sequence uses the first auxiliary capacitor 2161 to the nth auxiliary capacitor 216. n .

[0065] Figure 4 It is shown Figure 1 A schematic diagram of the equivalent circuits of the power transmitting device 200 and the power receiving device 300.

[0066] Reference Figures 1 to 4 V1 represents the voltage phasor indicating the AC voltage of the main resonant circuit 210, I1 represents the current phasor indicating the AC current of the main resonant circuit 210, Z1 represents the equivalent impedance of the main resonant circuit 210, and Z... R This indicates the main coil 211 and the i-th sub-coil 311. i The combined impedance of the inductive coupling between them, V2 indicates the i-th sub-resonant circuit 310 iV1 represents a voltage phasor indicating an AC voltage of the main resonance circuit 210, I2 represents a current phasor indicating an AC current of the main resonance circuit 210, Zi represents an equivalent impedance of the ith sub resonance circuit 310i, and R L represents an equivalent impedance of the ith rectifier circuit 320 i and the ith battery B i In this case, Zi, Z2, and Z R may be respectively expressed as the following equations 1 to 3.

[0067] <equation 1>

[0068] Z1 = R1 + j2πfL M + 1 / (j2πfC V )

[0069] In the above equation 1, R1 = an equivalent resistance of the main resonance circuit 210, L M = an inductance (main inductance) of the main coil 211, C V = a capacitance of the variable capacitor 212, and f = (L M × C V ) 0.5 .

[0070] <equation 2>

[0071] Z2 = jωL S_i + 1 / (j2πfC S_i ) + R2

[0072] In the above equation 2, L S_i = an inductance of the ith sub coil 311 i , C S_i = a capacitance of the ith sub capacitor 312 i , and R2 = an equivalent resistance of the ith sub resonance circuit 310 i .

[0073] <equation 3>

[0074] Z R = (2πfM i ) 2 / (Z2 + R L )

[0075] In the above equation 3, M i = an inductance between the main coil 211 and the ith sub coil 311 i .

[0076] Accordingly, V1, I1, V2, and I2 satisfy the relationships of equations 4 to 6.

[0077] <equation 4>

[0078]

[0079] <Formula 5>

[0080]

[0081] <Formula 6>

[0082] V2 = R L I2

[0083] In the above Formula 1 to Formula 6, R1, L M and C V are values indicating unique characteristics of the main resonance circuit 210, and are pre-stored in the control circuit 240. R2, L S_i and C S_i are values indicating unique characteristics of the i-th sub resonance circuit 310 i and are pre-stored in the control circuit 240. f is a value selected from among the first resonance frequency to the n-th resonance frequency and the first auxiliary frequency to the n-th auxiliary frequency, each of which is pre-set. That is, among the parameters of Formula 4, only two parameters R L and M i are unknown.

[0084] Since there are two unknowns, each unknown can be determined (estimated) by acquiring two sensing information indicating V1 and I1 of Formula 4. Specifically, in the initial charging mode, when the i-th resonance frequency is selected as f of Formula 4, the control circuit 240 can record V1 and I1 sensed by the sensing circuit 230 as i-th main sensing information, and when the i-th auxiliary frequency is selected as f of Formula 4, the control circuit 240 can record V1 and I1 sensed by the sensing circuit 230 as i-th auxiliary sensing information. Subsequently, the control circuit 240 can calculate R L and M i based on the i-th main sensing information, the i-th auxiliary sensing information, and Formula 4. That is, when f of Formula 4 is equal to the i-th resonance frequency, the i-th main sensing information indicates V1 and I1 of Formula 4, and when f of Formula 4 is equal to the i-th auxiliary frequency, the i-th auxiliary sensing information indicates V1 and I1 of Formula 4. Accordingly, R L and M i can be determined as a solution of a simultaneous equation obtained from Formula 4.

[0085] The control circuit 240 can calculate I2 of Formula 5 based on R L , M i and I1. The control circuit 240 can calculate V2 of Formula 6 based on R L and I2. That is, the control circuit 240 can calculate (estimate) the AC voltage and the AC current of the i-th sub resonance circuit 310 iamplitude and phase of each of the AC voltage and the AC current. The i-th AC power received by the i-th sub-resonance circuit 310 i is converted into the i-th DC power by the i-th rectification circuit 320 i , and is supplied to the i-th battery B i . The control circuit 240 can determine that the i-th DC voltage, which is a voltage across the i-th battery, is equal to a voltage amplitude of V2 of Equation 6. The i-th DC voltage corresponds to a state of charge (SOC) of the i-th battery B i .

[0086] The power transmission device 200 can determine the first DC voltage to the n-th DC voltage by performing the above process once for each of the plurality of sub-resonance circuits. It is assumed that n > a > b > 1. The a-th DC voltage, which is smaller than the b-th DC voltage, indicates that the SOC of the a-th battery B a is smaller than the SOC of the b-th battery B b . The a-th DC voltage, which is larger than the b-th DC voltage, indicates that the SOC of the a-th battery B a is larger than the SOC of the b-th battery B b . Accordingly, the control circuit 240 can determine a charging order among the first battery B1 to the n-th battery B n by arranging the first DC voltage to the n-th DC voltage in an amplitude order.

[0087] Figure 5 is a flowchart illustrating a wireless charging method according to the first embodiment of the disclosure. The method of Figure 5 may be performed to determine a charging order among the plurality of batteries B1 ~ B n in an initial charging mode.

[0088] Referring to Figure 5 , in step S500, the control circuit 240 of the power transmission device 200 sets the first index k to be equal to 1.

[0089] In step S510, the power transmission device 200 wirelessly transmits the k-th AC power during a k-th main time. Specifically, the control circuit 240 sets a resonance frequency of the main resonance circuit 210 to be equal to a k-th resonance frequency during the k-th main time. When the k-th resonance frequency = f k , the k-th main time can be preset to be equal to or greater than 1 / f k . The k-th AC power is an AC power having the k-th resonance frequency. For example, when the first index is 1, a first AC power having a first resonance frequency is wirelessly transmitted by the main resonance circuit 210 during a first main time.

[0090] In step S520, the power transmitting device 200 records the kth master sensing information. The kth master sensing information may include the amplitude of each of the AC voltage and AC current of the kth AC power wirelessly transmitted from the power transmitting device 200 in step S510.

[0091] In step S530, the power transmitting device 200 wirelessly transmits the kth auxiliary power with the kth auxiliary frequency during the kth auxiliary time period. Specifically, the control circuit 240 sets the resonant frequency of the main resonant circuit 210 to be equal to the kth auxiliary frequency during the kth auxiliary time period. The kth auxiliary time can be preset to be equal to or greater than 1 / (kth auxiliary frequency).

[0092] In step S540, the power transmitting device 200 records the kth auxiliary sensing information. The kth auxiliary sensing information may include the AC current voltage and AC current amplitude of the kth auxiliary power wirelessly transmitted from the power transmitting device 200 in step S530.

[0093] In step S550, the power transmitting device 200 determines the k-th DC voltage based on the k-th primary sensing information and the k-th secondary sensing information (see Equations 4 to 6).

[0094] In step S560, the power transmitting device 200 determines whether the first index k is equal to the target index n. The target index n is the total number of batteries B included in the wireless charging system 100. If the value of step S560 is "no", step S562 is executed. If the value of step S560 is "yes", step S570 is executed.

[0095] In step S562, the power transmitting device 200 increments the first index k by 1. After step S562, Figure 5 The method can be moved to step S510.

[0096] In step S570, the power transmitting device 200 determines the first battery B1 to the nth battery B based on the first DC voltage to the nth DC voltage. n The control circuit 240 can arrange the first DC voltage to the nth DC voltage in ascending order and assign a higher charging order to the battery corresponding to the lower DC voltage. For example, when the first DC voltage is less than the second DC voltage, the control circuit 240 assigns a higher charging order to the first battery B1 than to the second battery B2, such that the first battery B1 takes precedence over the second battery B2, and in other cases, assigns a higher charging order to the second battery B2 than to the first battery B1. The control circuit 240 can store instructions in its memory for the first battery B1 to the nth battery B2. n A marker indicating the charging sequence for each item.

[0097] Figure 6This is a flowchart of a wireless charging method according to a second embodiment of the present disclosure. It can be understood through... Figure 5 The charging sequence determined by the method is executed. Figure 6 The method involves sequentially charging multiple batteries B1 to B1 in normal charging mode. n Charge it.

[0098] In step S600, the power transmitting device 200 sets the second index x to 1. The second index x indicates the charging sequence.

[0099] In step S610, the power transmitting device 200 selects the j-th battery B according to the x-th charging sequence. j (First battery B1 to nth battery B) n One of them) is the target to be charged. Battery j, B j First cell B1 to nth cell B n It is assigned the xth highest charging level.

[0100] In step S620, the power transmitting device 200 wirelessly transmits power to the battery B selected in step S610. j The associated j-th resonant frequency of the j-th AC power. In step S620, the j-th AC power with the j-th resonant frequency is wirelessly transmitted. Therefore, the j-th AC power is wirelessly received through the j-th sub-resonant circuit.

[0101] In step S630, the power transmitting device 200 determines the j-th battery B. j Whether the charging is complete. Specifically, the control circuit 240 determines whether the charging of battery B is complete at the j-th battery. j The charging period of battery B is determined at predetermined time intervals. j The DC voltage (see Equations 4 to 6), and when the j-th battery B j When the DC voltage reaches the preset upper limit, charging is considered complete. If the value of step S630 is "No", step S630 can be repeated. If the value of step S630 is "Yes", step S640 is executed.

[0102] In step S640, the power transmitting device 200 determines whether the second index x is equal to the target index n. The target index n is the total number of batteries B included in the wireless charging system 100. When the value of step S640 is "No", step S642 is executed. The value of step S640 is "Yes", indicating that all first batteries B1 to nth batteries B have been completed. n Charging.

[0103] In step S642, the power transmitting device 200 increments the second index x by 1. After step S642, Figure 6 The method can be moved to step S610.

[0104] The above-described embodiments of the disclosure are implemented not only by the apparatus and the method, and can be implemented by a program for executing functions corresponding to the configuration of the embodiments of the disclosure or a recording medium having the program recorded thereon, and those skilled in the art can easily implement such embodiments according to the disclosure of the previously described embodiments.

[0105] Although the disclosure has been described above with respect to a limited number of embodiments and drawings, the disclosure is not limited thereto, and it will be obvious to those skilled in the art that various modifications and changes can be made thereto within the technical aspects of the disclosure and the equivalent scope of the appended claims.

[0106] In addition, modifications and changes can be made to the disclosure described above by those skilled in the art without departing from the technical aspects of the disclosure, the disclosure is not limited by the above-described embodiments and drawings, and some or all of the embodiments can be selectively combined to allow various modifications.

[0107] This application claims priority to Korean Patent Application No. 10-2020-0067106, filed on June 3, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

Claims

1. A wireless charging system, the wireless charging system comprising: A first power receiving device, which is connected in parallel with a first battery, and includes a first sub-resonant circuit having a first resonant frequency; The second power receiving device is connected in parallel with the second battery and includes a second sub-resonant circuit having a second resonant frequency. as well as A power transmission device, comprising a main resonant circuit, The power transmission device is configured as follows: In the initial charging mode, the charging sequence between the first battery and the second battery is determined. In normal charging mode, when the first battery is selected according to the charging sequence, the first AC power with the first resonant frequency is wirelessly transmitted to the first sub-resonant circuit through the main resonant circuit, and In the normal charging mode, when the second battery is selected according to the charging sequence, the second AC power with the second resonant frequency is wirelessly transmitted to the second sub-resonant circuit through the main resonant circuit. In the initial charging mode, the power transmitting device is configured as follows: The first AC power is transmitted wirelessly during the first master time period. Record the first master sensing information indicating the AC voltage and AC current of the first AC power. During the first auxiliary time period, a first auxiliary power with a first auxiliary frequency is wirelessly transmitted. Record the first auxiliary sensing information indicating the AC voltage and AC current of the first auxiliary power supply. The first DC voltage of the first battery is determined based on the first main sensing information and the first auxiliary sensing information. During the second master time, the second AC power is transmitted wirelessly. Record the second master sensing information indicating the AC voltage and AC current of the second AC power. During the second auxiliary time period, a second auxiliary power with a second auxiliary frequency is wirelessly transmitted. Record the second auxiliary sensing information indicating the AC voltage and AC current of the second auxiliary power. The second DC voltage of the second battery is determined based on the second main sensing information and the second auxiliary sensing information, and The charging sequence between the first battery and the second battery is determined based on the first DC voltage and the second DC voltage.

2. The wireless charging system according to claim 1, wherein, The first sub-resonant circuit includes a first sub-coil and a first sub-capacitor connected in series, and The second sub-resonant circuit includes a second sub-coil and a second sub-capacitor connected in series.

3. The wireless charging system according to claim 1, wherein, The first power receiving device further includes a first rectifier circuit configured to convert the first AC power received by the first sub-resonant circuit into first DC power, and to supply the first DC power to the first battery. The second power receiving device further includes a second rectifier circuit configured to convert the second AC power received by the second sub-resonant circuit into second DC power and to supply the second DC power to the second battery.

4. The wireless charging system according to claim 1, wherein, The power transmission device further includes: A power generation circuit configured to selectively provide the main resonant circuit with the first AC power, the first auxiliary power, the second AC power, and the second auxiliary power; A sensing circuit configured to sense the AC voltage and AC current of the first AC power and the second AC power supplied to the main resonant circuit; and A control circuit that is operatively connected to the main resonant circuit, the power generation circuit, and the sensing circuit.

5. The wireless charging system according to claim 4, wherein, The main resonant circuit includes a main coil and a variable capacitor connected in series, and The control circuit is configured to adjust the capacitance of the variable capacitor to be equal to one of a first main capacitor, a first auxiliary capacitor, a second main capacitor, and a second auxiliary capacitor, which are different from each other.

6. The wireless charging system according to claim 5, wherein, The first resonant frequency is equal to the resonant frequency of the main inductance of the main coil and the first main capacitor. The first auxiliary frequency is equal to the resonant frequency of the main inductor and the first auxiliary capacitor. The second resonant frequency is equal to the resonant frequencies of the main inductor and the second main capacitor, and The second auxiliary frequency is equal to the resonant frequency of the main inductor and the second auxiliary capacitor.

7. An electric vehicle comprising a wireless charging system according to any one of claims 1 to 6.

8. A wireless charging method for a first battery and a second battery, wherein the first battery is connected in parallel with a first sub-resonant circuit having a first resonant frequency, and the second battery is connected in parallel with a second sub-resonant circuit having a second resonant frequency, the wireless charging method comprising the following steps: In the initial charging mode, the charging order between the first battery and the second battery is determined; In normal charging mode, when the first battery is selected according to the charging sequence, the first AC power with the first resonant frequency is wirelessly transmitted to the first sub-resonant circuit. as well as In the normal charging mode, when the second battery is selected according to the charging sequence, second AC power with the second resonant frequency is wirelessly transmitted to the second sub-resonant circuit. The step of determining the charging sequence includes the following steps: The first AC power is transmitted wirelessly during the first master time period; Record the first master sensing information indicating the AC voltage and AC current of the first AC power; During the first auxiliary time period, a first auxiliary power with a first auxiliary frequency is wirelessly transmitted. Record the first auxiliary sensing information indicating the AC voltage and AC current of the first auxiliary power; The first DC voltage of the first battery is determined based on the first main sensing information and the first auxiliary sensing information; The second AC power is transmitted wirelessly during the second master time. Record the second master sensing information indicating the AC voltage and AC current of the second AC power; During the second auxiliary time period, a second auxiliary power with a second auxiliary frequency is wirelessly transmitted; Record the second auxiliary sensing information indicating the AC voltage and AC current of the second auxiliary power; The second DC voltage of the second battery is determined based on the second main sensing information and the second auxiliary sensing information; and The charging sequence between the first battery and the second battery is determined based on the first DC voltage and the second DC voltage.

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