WO2016195218A1

WO2016195218A1 - Wireless charging system

Info

Publication number: WO2016195218A1
Application number: PCT/KR2016/002646
Authority: WO
Inventors: 정두원
Original assignee: 주식회사 엘트로닉스
Priority date: 2015-06-03
Filing date: 2016-03-16
Publication date: 2016-12-08
Also published as: KR20160142524A

Abstract

Disclosed is a wireless charging system. A wireless charging system according to an exemplary embodiment comprises: a wireless power transmission module for transmitting wireless power; and at least one wireless charger for charging a battery by receiving the wireless power, wherein the wireless power transmission module comprises: a wireless power transmission circuit which generates wireless power and transmits the generated wireless power into the air; a first communication block for checking whether a wireless charger exists within a predetermined distance; and a control block which, when no wireless charger exists within the predetermined distance, generates a sleep signal in the wireless power transmission circuit.

Description

Wireless charging system

Embodiments of the present invention relate to wireless charging technology.

In order to apply the low power RF energy transmission system, various organizations such as A4WP, WPC, and PMA are making wireless charging standards and trying to form a market. In Korea, technology is being prepared to use 6.78MHz, so it is necessary to develop a small, high efficiency product for wireless charging products at this frequency.

An embodiment of the present invention is to provide a wireless charging system that can reduce the power consumption.

An embodiment of the present invention is to provide a wireless charging system that can improve the wireless power transmission efficiency.

The wireless charging system according to an exemplary embodiment includes a wireless power transmission module for transmitting wireless power and at least one wireless charger for receiving the wireless power to charge a battery, wherein the wireless power transmission module is A wireless power transmission circuit generating wireless power and transmitting the same to the air; A first communication block checking whether a wireless charger exists within a preset distance; And a control block for generating a sleep signal to the wireless power transmission circuit when the wireless charger does not exist within the preset distance.

The wireless power transmission module may be configured to wirelessly charge a plurality of wireless chargers simultaneously, each of the plurality of wireless chargers including: a receiving coil configured to receive wireless power transmitted from the wireless power transmission module; A matching circuit electrically connected to the receiving coil; And a control block for checking whether the charging of the battery is completed and controlling the matching circuit so that the resonance frequency band of the receiving coil is out of the frequency band of the wireless power when the charging of the battery is completed. .

The wireless charger may include: a power conversion circuit configured to charge a battery by receiving wireless power transmitted from the wireless power transmission module; A monitoring unit monitoring a change in impedance of the power conversion circuit when the wireless power is received; And a second communication block configured to transmit the information on the impedance change to the wireless power transmission module, wherein the wireless power transmission module is configured to, from the second communication block.

The current and voltage of the amplifier in the wireless power transmission circuit may be adjusted using the received information about the impedance change.

According to an exemplary embodiment, when the mobile device is not charged, the power consumption may be reduced by operating at low power. In addition, by feeding back the power change of the wireless power receiving device to the wireless power transmitting device and accordingly impedance matching through the voltage / current control of the amplifier in the wireless power transmitting side, it is possible to improve the wireless power transmission efficiency. Will be.

1 is a block diagram illustrating a wireless charging system in accordance with an exemplary embodiment.

2 is a circuit diagram illustrating a circuit capable of implementing low power in a standby state according to an exemplary embodiment of the present invention.

3 illustrates a structure of a Class-E amplifier according to an exemplary embodiment.

4 is a circuit diagram of a Class-E power amplifier according to an exemplary embodiment.

5 illustrates a rectifier, an analog digital converter (ADC), a low drop out regulator (LDO), and a monitoring circuit of an RF / DC power conversion circuit according to an exemplary embodiment.

6 illustrates a DC / DC converter circuit of an RF / DC power conversion circuit according to an exemplary embodiment.

7 is a graph illustrating a change in current voltage during battery charging in a wireless charger according to an exemplary embodiment.

8A schematically illustrates a wireless charging system according to an exemplary embodiment.

FIG. 8B is a diagram showing a circuit configuration of the wireless charging system shown in FIG. 8A.

FIG. 9 is a diagram showing an equivalent circuit of the wireless charging system circuit shown in FIG. 8B.

FIG. 10 is a schematic block diagram illustrating a state in which a control block of a wireless power transmission module controls a DC / DC converter to control a voltage current input to an amplifier according to an embodiment of the present invention and a structure of an amplifier.

11 is a diagram showing a transmission block (wireless power transmission module) of a 6.78 MHz wireless charging system according to an exemplary embodiment.

12 is a circuit diagram for current and voltage control of an amplifier of a wireless power transmission module according to an exemplary embodiment.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. The following detailed description is provided to assist in a comprehensive understanding of the methods, devices, and / or systems described herein. However, this is only an example and the present invention is not limited thereto.

In describing the embodiments of the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification. The terminology used in the description is for the purpose of describing embodiments of the invention only and should not be limiting. Unless explicitly used otherwise, the singular forms “a,” “an,” and “the” include plural forms of meaning. In this description, expressions such as "comprises" or "equipment" are intended to indicate certain features, numbers, steps, actions, elements, portions or combinations thereof, and one or more than those described. It should not be construed to exclude the presence or possibility of other features, numbers, steps, actions, elements, portions or combinations thereof.

In the following description, the terms "transfer", "communication", "transmit", "receive" and other similar meanings of signals or information are not only meant to directly convey the signal or information from one component to another. It also includes passing through other components. In particular, "transmitting" or "sending" a signal or information to a component indicates the final destination of the signal or information and does not mean a direct destination. The same is true for the "reception" of a signal or information. In addition, in this specification, that two or more pieces of data or information are "related" means that if one data (or information) is obtained, at least a portion of the other data (or information) can be obtained based thereon.

1 is a block diagram illustrating a wireless charging system according to an exemplary embodiment.

Referring to FIG. 1, the wireless charging system 100 includes a wireless power transmission module 102 and a wireless charger 104. The wireless power transmission module 102 transmits wireless power to the air, and the wireless charger 104 receives the wireless power transmitted from the wireless power transmission module 102 to charge the battery.

In the wireless charging system 100, wireless transmission efficiency depends on the efficiency of the amplifier to amplify by DC / RF conversion. Thus, in the exemplary embodiment of the present invention, the wireless power transmission module 102 may use a Class-E power amplifier that is switchable to an amplifier 111 that converts DC to AC and amplifies it.

In addition, the wireless power transmission module 102 and the wireless charger 104 may include communication blocks 113 and 133 (ie, communication modules) for bidirectional communication. The wireless power transmission module 102 may recognize the charging situation of the wireless charger 104 through the communication block 113. The wireless power transmission module 102 may charge two or more wireless chargers 104 simultaneously. At this time, in order to be able to recognize all the charging status of each wireless charger 104, the 2.4GHz Bluetooth communication module may be used as the communication block 113.

The wireless charger 104 supports the charging of the mobile device using the RF / DC power conversion circuit 131. The RF / DC power conversion circuit 131 may rectify the wireless power (ie, AC power) received from the wireless power transmission module 102 into direct current (DC), convert DC-DC, and charge the battery.

(1) low power system design

In order to reduce power consumption of a user, a circuit design that operates at low power is required when the mobile device (eg, the wireless charger 104) is not charged. The wireless power transmission module 102 may have circuitry that can minimize power consumption when not transmitting power (ie, in a standby state). 2 is a circuit diagram illustrating a circuit capable of implementing low power in a standby state according to an exemplary embodiment of the present invention.

The wireless power transmission module 102 supplies 3.3V to the control block 125 of the wireless power transmission module 102 to sleep in the control block 125 when there is no wireless charger 104 within a predetermined distance. A signal may be generated to turn off the wireless power transmission circuit 127. For example, the control block 125 may generate a sleep signal to a U1 (DC / DC Converter) chip in the circuit shown in FIG. 2 to turn off the U1 chip. In this case, when the resonant circuit is configured using the resistor R201 and the capacitor C22 in the circuit shown in FIG. 2, the U1 DC / DC converter operates every 400 ms. The wireless power transmission module 102 may check whether the wireless charger 104 is within a predetermined distance through the communication block 113.

(2) Class-E Switching Amplifier Design

In order to charge the portable device (ie, the wireless charger 104) in the wireless power transmission module 102, an RF output of about 10 W should be generated. Class-E amplifiers are complex in structure but are energy efficient and can be made small. In the wireless power transmission module 102, the Class-E amplifier, which is the amplifier 111, is designed to sequentially amplify two MOSFETs M1 and M2 by turning them ON / OFF. 3 is a diagram illustrating a structure of a Class-E amplifier according to an exemplary embodiment. The Class-E amplifier shown in FIG. 3 has been proposed for improving intermodulation distortion (IMD). In FIG. 3, the capacitor C0 and the inductor L0 are resonant circuits and may operate as a low pass filter (LPF) in the 6.78 MHz band. The inductor L0 may be implemented to design a corresponding inductance as a resonant antenna of the wireless power transmission module 102 and perform impedance matching only with the capacitor C0.

In the conventional amplifier, the resonant antenna is viewed as a load, and an inductor is complicated by adding an inductor. Substituting the inductance of the resonant antenna eliminates the need for additional inductors. The gate driver 115 may be used to synchronize the gate input signals of the two MOSFETs M1 and M2 of the amplifier 111. In addition, an AND gate and a NAND gate may be used to make the phases of the gate input signals of the two MOSFETs M1 and M2 180 degrees out of phase. 4 shows a circuit diagram of a Class-E power amplifier according to an exemplary embodiment.

(3) RF / DC power conversion circuit design

The wireless charger 104 includes an RF / DC power conversion circuit 131. The RF / DC power conversion circuit 131 includes a monitoring unit 141 for monitoring an input voltage when receiving wireless power, a rectifier 143 for rectifying the received wireless power, and different levels of rectified DC power. It may include a DC-DC converter 145 for converting the DC power of the, and a battery 147 for storing and charging the converted DC power.

When resonance occurs at the 24V 10W transmission output (output transmitted from the wireless power transmission module 102), the input voltage is generated up to 60V in the wireless charger 104 depending on the resonance coil. The monitoring unit 141 may monitor the input voltage. The input voltage of the rectifier 143 of the RF / DC power conversion circuit 131 may be designed to 6.5V ~ 60V. The rectifier 134 may include a bridge circuit.

5 is a diagram illustrating a rectifier, an analog digital converter (ADC), a low drop out regulator (LDO), and a monitoring circuit of the RF / DC power conversion circuit 131 according to an exemplary embodiment. Referring to FIG. 5, the ADC (Analog Digital Converter) used a four-channel ADC IC, of which two channels (battery voltage and DC / DC output voltage monitoring) were used. A circuit using a resistor was designed to reduce the voltage to the ADC input.

The Low Drop Out Regulator (LDO) TPS54160 IC has a 0.5V to 58V output and up to 1.5A current output. Rectifier output is expected to be designed up to 60V input. En pin operates in float setting, RT / CLK ping is set as resistor timing and external clock and 581KHz is applied by applying switching frequency as external resistance value of 200K. The distribution resistor was set to 5V output. The DC / DC output goes through the monitoring circuit to the ADC input. 6 is a diagram illustrating a DC / DC converter circuit of the RF / DC power conversion circuit 131 according to an exemplary embodiment.

(4) communication system and control system design

The wireless charging system 100 may use a Bluetooth low power communication mode between the wireless power transmission module 102 and the wireless charger 104. In this case, a topology of a star structure in which several slaves (for example, the wireless charger 104) exist in one master (for example, the wireless power transmission module 102) may be used. Power transmission is possible only from the master to the slave, and communication may be implemented to enable bidirectional communication between the master and the slave.

Looking at the process of transmitting the wireless power between the wireless power transmission module 102 and the wireless charger 104 as follows. When power is supplied to the wireless power transmission module 102, the wireless power transmission module 102 sends a beacon in a standby state through its own setting step to supply power for communication to the wireless charger 104. The wireless charger 104 enters a boot state when the power for communication is transmitted and transmits a connection signal. When the wireless charger 104 sends a connection signal, the wireless power transmission module 102 is in a low power state to prepare for power transmission. Here, the wireless power transmission module 102 may determine whether the wireless charger 104 exists in the vicinity through the reception of the access signal. Power transmission is started while the wireless power transmission module 102 sends a power transmission control signal, and the wireless charger 104 is in a power receiving state.

The wireless power transmission module 102 and the wireless charger 104 may include monitoring

units

121 and 141 for voltage and current monitoring, respectively. Through the monitoring

units

121 and 141, the wireless power transmission efficiency between the wireless power transmission module 102 and the wireless charger 104 may be calculated in real time to control voltage and current for wireless power transmission.

When simultaneously charging two wireless chargers 104 in the wireless power transmission module 102, when charging is completed in one wireless charger 104, the matching circuit of the fully charged wireless charger 104 is controlled to 6.78MHz. (I.e., it is possible to prevent resonance from occurring in the wireless power frequency band). In detail, the charging completion of the wireless charger 104 may move the resonance frequency band of the receiving coil of the wireless charger 104 out of the wireless power frequency band by adjusting the impedance of the matching circuit electrically connected to the receiving coil. have. Through this, when charging two or more wireless charger 104 at the same time, it is possible to continue the wireless charging for the remaining wireless charger 104 is not completed.

Hereinafter, the efficiency improvement of the wireless charging system 100 through voltage and current control will be described.

In general, wireless charging systems designed using fixed impedance matching circuits vary greatly in efficiency as impedance changes. The coupling coefficient changes according to two situations (a situation where the coupling coefficient changes as the distance between the transmitting antenna and the receiving antenna gets closer and the impedance of the receiver changes due to the control method when the battery is charged). This coupling coefficient changes the input impedance by the reflected impedance.

Accordingly, in the embodiment of the present invention, by feeding back the power change of the receiver side (that is, the wireless charger 104) to the transmitter side (that is, the wireless power transmission module 102) through the communication blocks 113 and 133, The present invention proposes a method for solving impedance matching by adjusting the current and voltage of the amplifier 111 of the wireless power transmission module 102.

(1) change in impedance during battery charging

7 is a graph illustrating a change in current voltage when charging a battery in a wireless charger according to an exemplary embodiment. Referring to FIG. 8, as the charging time elapses, the charging current decreases, so that the change of the impedance increases on the receiver side (that is, V (voltage) = I (current) R ( Resistance)). This not only affects the resonance frequency at the receiver side, but also affects the impedance at the transmitter side.

(2) Impedance change on transmitter side according to impedance change on receiver side

8A is a diagram schematically illustrating a wireless charging system according to an exemplary embodiment, and FIG. 8B is a diagram illustrating a circuit configuration of the wireless charging system illustrated in FIG. 8A. 9 is a figure which shows the equivalent circuit of the wireless charging system circuit shown to FIG. 8 (b).

8 and 9, the input impedance Zin seen by the amplifier 111 of the wireless power transmission module 102 is expressed by Equation 1 below. Where Zpm is the impedance seen from the transmitter coil to the receiver side.

According to Equation 1, it can be seen that the input impedance is changed by the load resistance Z0 on the receiver side.

(3) current voltage sensing and communication system

Thus, in the embodiment of the present invention, after the control block 135 of the wireless charger 104 detects the voltage and current of the RF / DC power conversion circuit 131, the communication block 133 ( That is, the voltage current detection information may be transmitted to the wireless power transmission module 113 through the communication module. Then, the control block of the wireless power transmission module 113 may calculate the impedance of the wireless charger 104 using the received voltage current detection information.

(4) voltage and current control method

FIG. 10 is a schematic block diagram illustrating a state in which the control block 125 of the wireless power transmission module 113 controls the DC / DC converter to control the voltage current input to the amplifier 111 according to an embodiment of the present invention. And a diagram showing the structure of the recorder.

Referring to FIG. 10, the control block 125 may control a change in the impedance of the amplifier 111 facing the receiver according to the change in the impedance of the wireless charger 104 calculated based on the voltage current detection information. In this case, a change in the voltage current at the receiver side occurs and reflects the change again to detect the optimum transmission efficiency by performing the voltage current.

11 is a diagram illustrating a transmission block (wireless power transmission module) of a 6.78 MHz wireless charging system according to an exemplary embodiment. 12 is a circuit diagram for controlling current and voltage of an amplifier of a wireless power transmission module according to an exemplary embodiment.

While the exemplary embodiments of the present invention have been described in detail above, those skilled in the art will appreciate that various modifications can be made to the above-described embodiments without departing from the scope of the present invention. . Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

[Description of the code]

100: wireless charging system

102: wireless power transmission module

104: wireless charger

111: amplifier

113,133: Communication Block

115: gate driver

121, 141: monitoring unit

125, 135: control block

127: wireless power transmission circuit

131: power conversion circuit

143: Rectifier

145: DC / DC converter

147: Battery

Claims

A wireless charging system comprising a wireless power transmission module for transmitting wireless power and at least one wireless charger for receiving the wireless power to charge a battery,

The wireless power transmission module,

A wireless power transmission circuit generating wireless power and transmitting the same to the air;

A first communication block checking whether a wireless charger exists within a preset distance; And

And a control block for generating a sleep signal to the wireless power transmission circuit when the wireless charger does not exist within the predetermined distance.
The method according to claim 1,

The wireless power transmission module is provided to wirelessly charge a plurality of wireless chargers at the same time,

Each of the plurality of wireless chargers,

A receiving coil receiving wireless power transmitted from the wireless power transmission module;

A matching circuit electrically connected to the receiving coil; And

And a control block to check whether the charging of the battery is completed and to control the matching circuit so that the resonance frequency band of the receiving coil is out of the frequency band of the wireless power when the charging of the battery is completed. system.
The method according to claim 1,

The wireless charger,

A power conversion circuit that receives the wireless power transmitted from the wireless power transmission module and charges the battery;

A monitoring unit monitoring a change in impedance of the power conversion circuit when the wireless power is received; And

A second communication block for transmitting the information on the impedance change to the wireless power transmission module,

The wireless power transmission module,

And controlling the current and voltage of the amplifier in the wireless power transmission circuit using the information on the impedance change received from the second communication block.