KR20190047308A - Wireless Power Reception Method and Apparatus - Google Patents

Abstract

The present invention relates to a wireless power transmission device for wireless charging and a variable frequency switching mode power supply mounted on the same. According to an embodiment of the present invention, the wireless power transmission device comprises: a variable frequency switching mode power supply converting alternating current (AC) power into direct current (DC) power; a main controller supplying a reference clock; a gate driver using the reference clock to generate a plurality of switch control signals; an inverter generating an AC power signal based on the DC power and the plurality of switch control signals; and a power transmission device wirelessly transmitting the AC power signal wherein a reference frequency of the variable frequency switching mode power supply can be changed. Therefore, the present invention has an advantage of providing the wireless power transmission device with excellent electromagnetic interference (EMI) performance.

Description

Technical Field [0001] The present invention relates to a wireless power transmission method,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless power transmission technology, and more particularly, to an electromagnetic interference (EMI) performance by varying a switching frequency of a switching mode power supplier (SMPS) The present invention relates to a wireless power transmission apparatus capable of improving power consumption.

Recently, as the information and communication technology rapidly develops, a ubiquitous society based on information and communication technology is being made.

In order for information communication devices to be connected anytime and anywhere, sensors equipped with a computer chip having a communication function must be installed in all facilities of the society. Therefore, power supply problems of these devices and sensors are becoming a new challenge. In addition, mobile devices such as Bluetooth handsets and iPods, as well as mobile phones, have been rapidly increasing in number, and charging the battery has required users time and effort. As a way to solve this problem, wireless power transmission technology has recently attracted attention.

The wireless power transmission technology (wireless power transmission or wireless energy transfer) is a technology to transmit electric energy from the transmitter to the receiver wirelessly using the induction principle of the magnetic field. In the 1800s, electric motor or transformer And thereafter, a method of transmitting electrical energy by radiating electromagnetic waves such as high frequency, microwave, and laser has also been attempted. Our electric toothbrushes and some wireless shavers are actually charged with electromagnetic induction.

Up to the present, energy transmission using radio may be roughly classified into a magnetic induction method, an electromagnetic resonance method, and an RF transmission method using a short wavelength radio frequency.

In the magnetic induction method, when two coils are adjacent to each other and a current is supplied to one coil, a magnetic flux generated at this time causes an electromotive force to the other coils. As a technology, . The magnetic induction method has the disadvantage that it can transmit power of up to several hundred kilowatts (kW) and the efficiency is high, but the maximum transmission distance is 1 centimeter (cm) or less, so it is usually adjacent to the charger or the floor.

The self-resonance method is characterized by using an electric field or a magnetic field instead of using electromagnetic waves or currents. The self-resonance method is advantageous in that it is safe to other electronic devices or human body since it is hardly influenced by the electromagnetic wave problem. On the other hand, it can be used only at a limited distance and space, and has a disadvantage that energy transfer efficiency is somewhat low.

Short wavelength wireless power transmission - simply, RF transmission - takes advantage of the fact that energy can be transmitted and received directly in radio wave form. This technology is a RF power transmission system using a rectenna. Rectena is a combination of an antenna and a rectifier, which means a device that converts RF power directly into direct current power. That is, the RF method is a technique of converting an AC radio wave into DC and using it. Recently, as the efficiency has improved, commercialization has been actively researched.

Wireless power transmission technology can be applied not only to mobile, but also to various industries such as IT, railroad, and household appliance industry.

BACKGROUND ART [0002] As a wireless charging device is mounted on devices of various fields, researches on a method for effectively blocking electromagnetic wave interference caused by a wireless charging device have been actively conducted.

Actually, in a conventional wireless power transmission apparatus for wireless charging, in the case of an SMPS (Switching Mode Power Supplier) that converts an external AC power supply to a DC power supply and supplies the DC power to the transmission coil, a fixed specific reference frequency, for example, 400 KHz Thereby performing a switching operation. However, there has been a problem that electromagnetic interference is generated at a quadruple frequency which is a harmonic component of the fundamental frequency.

It is an object of the present invention to provide a wireless power transmission apparatus with improved EMI performance.

It is another object of the present invention to provide a wireless power transmission apparatus capable of varying an SMPS switching frequency to remove a peak component causing electromagnetic interference.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, unless further departing from the spirit and scope of the invention as defined by the appended claims. It will be possible.

The present invention can provide a wireless power transmitter for wireless charging and a variable frequency switched mode power supply mounted thereto.

A wireless power transmission apparatus according to an exemplary embodiment of the present invention includes a variable frequency switching mode power supply for converting an AC power source to a DC power source, a main controller for supplying a reference clock and a gate for generating a plurality of switch control signals using the reference clock An inverter for generating an AC power signal based on the driver, the DC power source and the plurality of switch control signals, and a power transmitter for wirelessly transmitting the AC power signal, wherein the reference frequency of the variable frequency switching mode power supply is variable .

Here, the variable frequency switching mode power supply may vary the reference frequency according to a predetermined frequency switching signal received from the main controller.

The variable frequency switching mode power supply may include a plurality of resistance elements, a Switching Mode Power Supplier (SMPS) IC, and a resistance control switch for switching controlling the plurality of resistance elements according to the frequency switching signal.

In one embodiment, if the number of resistance elements is two, the resistance control switch may be a two-channel analog switch.

Here, the frequency switching signal may be a rectangular pulse file having two levels.

If the level of the frequency switching signal is HIGH, the two resistive elements can be connected in parallel to the RT port of the Switching Mode Power Supplier (SMPS) IC.

On the other hand, if the level of the frequency switching signal is LOW, one of the two resistance elements can be connected to the RT port of the Switching Mode Power Supplier (SMPS) IC.

In addition, the level of the frequency switching signal may be changed at a predetermined time period.

Also, the frequency switching signal may be transmitted to the variable frequency switching mode power supply using any one of general purpose input output (GPIO) ports equipped with the main controller.

A variable frequency switching mode power supply, which is installed in a wireless power transmission apparatus according to another embodiment of the present invention and supplies power required for wireless power transmission, includes a Switching Mode Power Supplier IC (SMPS) And a switching frequency control circuit for providing the SMPS IC with a resistance value required for changing the reference frequency according to an external frequency switching signal.

Here, the frequency switching signal is received from a main controller provided in the wireless power transmission apparatus, and the reference frequency may be changed at a predetermined time interval according to the frequency switching signal.

The switching frequency control circuit may include a plurality of resistance elements and a resistance control switch for switching-controlling the plurality of resistance elements according to the frequency switching signal.

In one embodiment, if the number of resistance elements is two, the resistance control switch may be a two-channel analog switch.

Also, the frequency switching signal may be a rectangular pulse file having two levels.

If the level of the frequency switching signal is HIGH, the two resistive elements can be connected in parallel to the RT port of the SMPS (Switching Mode Power Supplier) IC.

On the other hand, if the level of the frequency switching signal is LOW, one of the two resistance elements can be connected to the RT port of the Switching Mode Power Supplier (SMPS) IC.

In addition, the level of the frequency switching signal may be changed at a predetermined time period.

Also, the frequency switching signal may be transmitted to the variable frequency switching mode power supply using any one of general purpose input output (GPIO) ports equipped with the main controller.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And can be understood and understood.

Effects of the method, apparatus and system according to the present invention will be described as follows.

The present invention has the advantage of providing a wireless power transmission apparatus with improved EMI performance.

It is another advantage of the present invention to provide a wireless power transmission apparatus capable of varying an SMPS switching frequency to remove a peak component causing electromagnetic interference.

The effects obtained by the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description will be.

1 is a block diagram illustrating a wireless charging system according to an embodiment of the present invention.
2 is a block diagram illustrating a wireless charging system according to another embodiment of the present invention.
3 is a block diagram illustrating a structure of a wireless power transmitter according to an embodiment of the present invention.
4 is a block diagram illustrating a structure of a wireless power receiver interworking with the wireless power transmitter of FIG.
5 is a block diagram illustrating an internal structure of a wireless power transmission apparatus according to an embodiment of the present invention.
6 is a block diagram illustrating a detailed structure of a wireless power transmission apparatus with improved EMI performance according to an embodiment of the present invention.
7 is a diagram for explaining the pin arrangement and circuit configuration of the commercial SMPS IC LM25118.
8 is a diagram for explaining a switching frequency control circuit structure for improving EMI performance of a wireless power transmission apparatus according to an embodiment of the present invention.
FIG. 9 is a diagram for explaining an EMI improvement effect of a wireless power transmission apparatus according to an embodiment of the present invention. Referring to FIG.
10 to 11 show experimental results of a measuring instrument using a variable frequency SMPS according to the present invention.
FIG. 12 is a result of a meter test to explain the effect of the variable frequency SMPS according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and various methods to which embodiments of the present invention are applied will be described in detail with reference to the drawings. The suffix " module " and " part " for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

In the description of the embodiment, in the case where it is described as being formed "above" or "below" each element, the upper or lower (lower) And that at least one further component is formed and arranged between the two components. Also, in the case of "upper (upper) or lower (lower)", it may include not only an upward direction but also a downward direction based on one component.

In the description of the embodiments, an apparatus equipped with a function of transmitting wireless power on a wireless charging system includes a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a wireless power transmitter, a transmitter, a transmitter, , A transmitting side, a wireless power transmission device, a wireless power transmitter, and the like are used in combination. Further, for the sake of convenience of explanation, it is to be understood that a wireless power receiving apparatus, a wireless power receiving apparatus, a wireless power receiving apparatus, a wireless power receiving apparatus, a receiving terminal, a receiving side, A receiver, a receiver, and the like can be used in combination.

The transmitter according to the present invention may be configured as a pad type, a cradle type, an access point (AP) type, a small base type, a stand type, a ceiling embedded type, a wall type, Power can also be transmitted. To this end, the transmitter may comprise at least one radio power transmission means. Here, the radio power transmitting means may be various non-electric power transmission standards based on an electromagnetic induction method in which a magnetic field is generated in a power transmitting terminal coil and charged using an electromagnetic induction principle in which electricity is induced in a receiving terminal coil under the influence of the magnetic field. Here, the wireless power transmission means may include an electromagnetic induction wireless charging technique defined by Wireless Power Consortium (WPC) and Power Matters Alliance (PMA), which are standard wireless charging technologies.

Also, a receiver according to an embodiment of the present invention may include at least one wireless power receiving means, and may receive wireless power from two or more transmitters at the same time. Here, the wireless power receiving means may include an electromagnetic induction wireless charging technique defined by Wireless Power Consortium (WPC) and Power Matters Alliance (PMA), which are standard wireless charging technologies.

The receiver according to the present invention may be used in a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a PDA (Personal Digital Assistants), a PMP (Portable Multimedia Player), a navigation device, A portable electronic device such as a toothbrush, an electronic tag, a lighting device, a remote control, a fishing rod, a smart watch, etc. However, the present invention is not limited thereto. It suffices.

1 is a block diagram illustrating a wireless charging system according to an embodiment of the present invention.

Referring to FIG. 1, the wireless charging system includes a wireless power transmission terminal 10 for wirelessly transmitting power, a wireless power receiving terminal 20 for receiving the transmitted power, and an electronic device 30 Lt; / RTI >

For example, the wireless power transmitting terminal 10 and the wireless power receiving terminal 20 can perform in-band communication in which information is exchanged using the same frequency band as that used for wireless power transmission. In another example, the wireless power transmitting terminal 10 and the wireless power receiving terminal 20 perform out-of-band communication in which information is exchanged using a different frequency band different from the operating frequency used for wireless power transmission .

For example, information exchanged between the wireless power transmitting terminal 10 and the wireless power receiving terminal 20 may include control information as well as status information of each other. Here, the status information and the control information exchanged between the transmitting and receiving end will become more apparent through the description of the embodiments to be described later.

The in-band communication and the out-of-band communication may provide bidirectional communication, but the present invention is not limited thereto. In another embodiment, the in-band communication and the out-of-band communication may be provided.

 For example, the unidirectional communication may be that the wireless power receiving terminal 20 transmits information only to the wireless power transmitting terminal 10, but the present invention is not limited thereto, and the wireless power transmitting terminal 10 may transmit information Lt; / RTI >

In the half duplex communication mode, bidirectional communication is possible between the wireless power receiving terminal 20 and the wireless power transmitting terminal 10, but information can be transmitted only by any one device at any time.

The wireless power receiving terminal 20 according to an embodiment of the present invention may acquire various status information of the electronic device 30. [ For example, the status information of the electronic device 30 may include current power usage information, information for identifying a running application, CPU usage information, battery charge status information, battery output voltage / current information, And is information obtainable from the electronic device 30 and available for wireless power control.

In particular, the wireless power transmitting terminal 10 according to an embodiment of the present invention can transmit a predetermined packet indicating whether or not to support fast charging to the wireless power receiving terminal 20. The wireless power receiving terminal 20 can inform the electronic device 30 of the connected wireless power transmitting terminal 10 when it is confirmed that it supports the fast charging mode. The electronic device 30 may indicate that fast charging is possible through a predetermined display means, which may be, for example, a liquid crystal display.

Also, the user of the electronic device 30 may select the predetermined fast charge request button displayed on the liquid crystal display means to control the wireless power transmitting terminal 10 to operate in the fast charge mode. In this case, the electronic device 30 can transmit a predetermined fast charge request signal to the wireless power receiving terminal 20 when the quick charge request button is selected by the user. The wireless power receiving terminal 20 may generate a charging mode packet corresponding to the received fast charging request signal and transmit the same to the wireless power transmitting terminal 10 to switch the general low power charging mode to the fast charging mode.

2 is a block diagram illustrating a wireless charging system according to another embodiment of the present invention.

For example, as shown in 200a, the wireless power receiving terminal 20 may include a plurality of wireless power receiving devices, and a plurality of wireless power receiving devices may be connected to one wireless power transmitting terminal 10, Charging may also be performed. At this time, the wireless power transmitting terminal 10 can distribute power to a plurality of wireless power receiving apparatuses in a time division manner, but it is not limited thereto. In another example, the wireless power transmitting terminal 10 can distribute power to a plurality of wireless power receiving apparatuses using different frequency bands allocated to the wireless power receiving apparatuses.

At this time, the number of wireless power receiving apparatuses connectable to one wireless power transmitting apparatus 10 is set to at least one of the required power amount for each wireless power receiving apparatus, the battery charging state, the power consumption amount of the electronic apparatus, Can be determined adaptively based on

As another example, as shown in 200b, the wireless power transmitting terminal 10 may be composed of a plurality of wireless power transmitting apparatuses. In this case, the wireless power receiving terminal 20 may be connected to a plurality of wireless power transmission apparatuses at the same time, and may simultaneously receive power from connected wireless power transmission apparatuses to perform charging. At this time, the number of wireless power transmission apparatuses connected to the wireless power receiving terminal 20 is adaptively set based on the required power amount of the wireless power receiving terminal 20, the battery charging status, the power consumption amount of the electronic apparatus, Can be determined.

3 is a block diagram illustrating a structure of a wireless power transmitter according to an embodiment of the present invention.

3, the wireless power transmitter 300 may include a power conversion unit 310, a power transmission unit 320, a communication unit 330, a control unit 340, and a sensing unit 350 . It should be noted that the configuration of the wireless power transmitter 300 described above is not necessarily an essential configuration, but may be configured to include more or less components.

3, when the DC power is supplied from the power supply unit 360, the power converting unit 310 may convert the DC power into AC power of a predetermined intensity.

The power converter 310 may include a DC / DC converter 311, an inverter 312, and a frequency generator 313. Here, the inverter 312 may be a half bridge inverter or a full bridge inverter. However, the present invention is not limited thereto, and a circuit configuration capable of converting DC power into AC power having a specific operating frequency is sufficient.

The DC / DC converting unit 311 may convert DC power supplied from the power supply unit 350 into DC power having a specific intensity according to a control signal of the controller 340.

At this time, the sensing unit 350 may measure the voltage / current of the DC-converted power and provide the measured voltage / current to the control unit 340. In addition, the sensing unit 350 may measure the internal temperature of the wireless power transmitter 300 and may provide the measurement result to the controller 340 to determine whether overheating occurs. For example, the control unit 340 may adaptively cut off the power supply from the power supply unit 350 or block the supply of power to the inverter 312 based on the voltage / current value measured by the sensing unit 350 . To this end, a power cutoff circuit for shutting off the power supplied from the power supply unit 350 or cutting off the power supplied to the inverter 312 may be further provided at one side of the power conversion unit 310.

The inverter 312 may convert the DC / DC converted DC power into AC power based on a reference AC signal generated by the frequency generator 313, e.g., a pulse width modulated signal. At this time, the frequency of the reference AC signal may be changed dynamically according to the control signal of the controller 340.

The wireless power transmitter 300 according to an exemplary embodiment of the present invention may adjust the operating frequency to adjust the intensity of the transmitted power. For example, the control unit 340 may receive the power reception state information and / or the power control signal of the wireless power receiver through the communication unit 330 and may receive the power control information based on the received power reception state information or (and) So that the intensity of the transmitted power can be adjusted.

For example, the power reception status information may include, but is not limited to, the intensity information of the rectifier output voltage, the intensity information of the current applied to the reception coil, and the like. The power control signal may include a signal for requesting power increase, a signal for requesting power reduction, and the like.

The power transmitting unit 320 may be configured to include a multiplexer 321 (or a multiplexer), a transmitting coil unit 322, and the like. Here, the transmission coil section 322 may be composed of first to n-th transmission coils.

In addition, the power transmitting unit 320 may further include a carrier generator (not shown) for generating a specific carrier frequency for power transmission. In this case, the carrier generator may generate a specific carrier frequency for mixing with the output AC power of the inverter 312 transmitted via the multiplexer 321.

It should be noted that one embodiment of the present invention may have different frequencies of AC power delivered to each transmit coil.

In another embodiment of the present invention, the resonance frequency of each transmission coil may be set differently by using a predetermined frequency controller having a function of controlling LC resonance characteristics for different transmission coils.

The multiplexer 321 may perform a switch function to transmit AC power to the transmission coil selected by the controller 340. [ The controller 340 may select a transmission coil to be used for power transmission to the corresponding wireless power receiver based on a predetermined signal strength indicator received from the wireless power receiver for each transmission coil.

The controller 340 according to an embodiment of the present invention may transmit power by time division multiplexing for each transmission coil when a plurality of wireless power receivers are connected.

For example, if three wireless power receivers-i. E., The first through third wireless power receivers-are each identified through three different transmit coils-i. E., First through third transmit coils-in the wireless power transmitter 300 , The control unit 340 may control the multiplexer 321 to control the AC power to be transmitted only through a specific transmission coil in a specific time slot. At this time, the amount of power transmitted to the corresponding wireless power receiver can be controlled according to the length of the time slot allocated for each transmission coil, but this is only one embodiment. DC power of the DC / DC converter 311 to control the transmission power of each wireless power receiver.

The control unit 340 may control the multiplexer 321 so that the detection signals may be sequentially transmitted through the first to n-th transmission coils 322 during the first detection signal transmission procedure. At this time, the control unit 340 can identify the time when the detection signal is transmitted using the timer 355. When the detection signal transmission time arrives, the control unit 340 controls the multiplexer 321 to output the detection signal through the corresponding transmission coil It can be controlled to be transmitted.

For example, the timer 350 can transmit a specific event signal to the control unit 340 at predetermined intervals during the step of transmitting the detection signal. The controller 340 controls the multiplexer 321 So that a specific sensing signal can be transmitted through the corresponding transmission coil.

In addition, the control unit 340 may receive a predetermined transmission coil identifier for identifying a signal strength indicator (Signal Strength Indicator) through a transmission coil from the demodulation unit 332 during the first detection signal transmission procedure, Lt; / RTI > received signal strength indicator.

The control unit 340 controls the multiplexer 321 to transmit the detection signal only through the transmission coil (s) on which the signal strength indicator is received during the first detection signal transmission procedure You may. In another example, when there are a plurality of transmit coils in which the signal strength indicator is received during the first differential sense signal transmission procedure, the control unit 340 transmits the transmit coil, which receives the signal strength indicator having the largest value, In the procedure, the detection signal may be determined as a transmission coil to be transmitted first, and the multiplexer 321 may be controlled according to the determination result.

The communication unit 330 may include at least one of a modulation unit 331 and a demodulation unit 332.

The modulator 331 may modulate the control signal generated by the controller 340 and transmit the modulated control signal to the multiplexer 321. Here, the modulation scheme for modulating the control signal includes a frequency shift keying (FSK) modulation scheme, a Manchester coding modulation scheme, a phase shift keying (PSK) modulation scheme, a pulse width modulation scheme, A differential bi-phase modulation method, and the like.

When a specific signal is detected through the transmission coil, the demodulation unit 332 can demodulate the detected signal and transmit the demodulated signal to the control unit 340. Here, the demodulated signal may include a signal strength indicator, an error correction (EC) indicator for power control during wireless power transmission, an end of charge indicator (EOC), an overvoltage / overcurrent / overheat indicator, But is not limited to, various status information for identifying the status of the wireless power receiver.

In addition, the demodulator 332 can identify which of the transmit coils the demodulated signal is received, and provide the controller 340 with a predetermined transmit coil identifier corresponding to the identified transmit coil.

 The demodulation unit 332 can demodulate the signal received through the transmission coil 323 and transmit the demodulated signal to the control unit 340. In one example, the demodulated signal may include, but is not limited to, a signal strength indicator, and the demodulated signal may include various status information of the wireless power receiver.

In one example, the wireless power transmitter 300 may acquire the signal strength indicator via in-band communication that uses the same frequency used for wireless power transmission to communicate with the wireless power receiver.

In addition, the wireless power transmitter 300 may transmit wireless power using the transmit coil portion 322, as well as exchange various control signals and status information with the wireless power receiver through the transmit coil portion 322 . As another example, a separate coil corresponding to each of the first to n-th transmission coils of the transmission coil part 322 may be additionally provided in the wireless power transmitter 300, and wireless power It should be noted that it may also perform in-band communication with the receiver.

In the description of FIG. 3, the wireless power transmitter 300 and the wireless power receiver perform in-band communication. However, the wireless power transmitter 300 is only one embodiment, Directional communication through different frequency bands. For example, the near-end bi-directional communication may be any one of low-power Bluetooth communication, RFID communication, UWB communication, and Zigbee communication.

3, the power transmission unit 320 of the wireless power transmitter 300 includes a multiplexer 321 and a plurality of transmission coils 322, but this is merely one embodiment, It should be noted that the power transmission unit 320 according to the embodiment may be composed of one transmission coil.

4 is a block diagram illustrating a structure of a wireless power receiver interworking with the wireless power transmitter of FIG.

4, the wireless power receiver 400 includes a receiving coil 410, a rectifier 420, a DC / DC converter 430, a load 440, a sensing unit 450, 460, and a main control unit 470. Here, the communication unit 460 may include at least one of a demodulation unit 461 and a modulation unit 462.

Although the wireless power receiver 400 shown in the example of FIG. 4 is shown as being capable of exchanging information with the wireless power transmitter 300 through in-band communication, this is only one embodiment, The communication unit 460 according to another embodiment of the present invention may provide short-range bidirectional communication through a frequency band different from the frequency band used for wireless power signal transmission.

The AC power received through the receive coil 410 may be delivered to the rectifier 420. The rectifier 420 may convert the AC power to DC power and transmit it to the DC / DC converter 430. The DC / DC converter 430 may convert the intensity of the rectifier output DC power to a specific intensity required by the load 440 and then forward it to the load 440.

The sensing unit 450 may measure the intensity of the DC power output from the rectifier 420 and may provide the measured DC power to the main control unit 470. In addition, the sensing unit 450 may measure the intensity of the current applied to the reception coil 410 according to the wireless power reception, and may transmit the measurement result to the main control unit 470. The sensing unit 450 may measure the internal temperature of the wireless power receiver 400 and provide the measured temperature value to the main control unit 470.

For example, the main control unit 470 may compare the measured rectifier output DC power with a predetermined reference value to determine whether an overvoltage is generated. As a result of the determination, if an overvoltage is generated, a predetermined packet indicating that an overvoltage has occurred can be generated and transmitted to the modulator 462. Here, the signal modulated by the modulator 462 may be transmitted to the wireless power transmitter 300 through the receiving coil 410 or a separate coil (not shown). The main control unit 470 can determine that the detection signal has been received when the intensity of the rectifier output DC power is equal to or greater than a predetermined reference value and when the signal strength indicator corresponding to the detection signal is received by the modulation unit 462 To be transmitted to the wireless power transmitter 300 via the wireless network. The demodulation unit 761 demodulates the AC power signal between the reception coil 410 and the rectifier 420 or the DC power signal output from the rectifier 420 to identify whether or not the detection signal is received, (470). ≪ / RTI > At this time, the main control unit 470 may control the signal intensity indicator corresponding to the detection signal to be transmitted through the modulation unit 462. [

5 is a block diagram illustrating an internal structure of a wireless power transmission apparatus according to an embodiment of the present invention.

5, the wireless power transmission apparatus 500 includes a main controller 510, a gate driver 520, an inverter (Invertor) 530, a power transmitter 540, an AC power source 550, and a variable frequency switching mode power (Variable Frequency Switching Mode Power Supply (VF SMPS), 560).

The AC voltage signal V_in supplied from the AC power source 550 may be converted to a DC voltage signal V_rail by the VF SMPS 560 and then supplied to the inverter 530.

In general, a switching mode power supply (SMPS) is a power supply, and uses a switch control method for converting an AC power to a DC power using a switching transistor, a filter, and a rectifier. Here, the rectifier and the filter may be independently configured and disposed between the AC power source and the SMPS.

SMPS is a power supply device that supplies a DC power source with stable output power by controlling the on / off time ratio of a semiconductor switch device. It is possible to achieve high efficiency, small size and weight, Equipment and equipment.

Depending on the quality of the power supply, stability and precision of electronic circuit operation are often influenced.

In general, there are a series regulator method and a switched mode method in which a stable power source is converted from a battery and a commercial AC power source.

The linear control method used in a TV set or a CRT monitor has a drawback in that the surrounding circuit is simple and the price is low, but the heat generation is large, the power efficiency is low, and the bulky is large.

On the other hand, the switching mode method has a merit that there is little heat generation, high power efficiency, and small volume, but it is expensive, has a complicated circuit, and can generate output noise and electromagnetic interference due to high frequency switching.

A variable SMPS (Variable Switching Mode Power Supply) applied to a wireless charging system generates a DC voltage by switching and rectifying an AC voltage of several tens Hz range output from an AC power supply.

The variable SMPS may output a constant level of DC voltage or adjust the output level of the DC voltage according to a predetermined control of the transmission controller (Tx Controller). The variable SMPS controls the supply voltage according to the output power level of the power amplifier - that is, the inverter 530 - so that the power amplifier of the wireless power transmitter can always operate in a highly efficient saturation region, Can be maintained.

Variable DC / DC converters (Variable DC / DC) can be used in addition to the commonly used commercial SMPS instead of the variable SMPS.

Commercial SMPS and variable DC / DC converters can control the supply voltage according to the output power level of the power amplifier so that the power amplifier can operate in a highly efficient saturation region, maintaining maximum efficiency at all output levels.

In one embodiment, the power amplifier may be of the Class E type, but is not limited thereto.

The inverter 530 converts a DC voltage V_rail of a certain level into an AC voltage V_Rail by a switching pulse signal of a several MHz to several tens MHz band received through a gate driver 520, that is, a pulse width modulation So that AC power to be transmitted wirelessly can be generated.

At this time, the gate driver 520 may generate a plurality of PWM signals for controlling the plurality of switches included in the inverter 530 using the reference clock Ref_CLK signal supplied from the main controller 510.

5, it is shown that four PWM signals SC1, SC2, SC3 and SC4 for controlling each of the four switches provided with the inverter 530 are received from the gate driver 520 However, this is only one embodiment, and when the inverter according to another embodiment is configured as a half bridge, it may receive two PWM signals for controlling the two switches, respectively, from the gate driver 520.

The VF SMPS 560 may dynamically adjust the DC voltage V_rail output according to the control signal of the main controller 510. [

In one example, the main controller 510 may dynamically control the output DC voltage of the VF SMPS 560 according to the intensity of the power required by the charging target receiver.

The main controller 510 may dynamically cut off the AC power source 550 or reduce the output DC voltage V_rail of the VF SMPS 560 when an overvoltage, Or shut down.

The main controller 510 can control the overall operation of the wireless power transmitting apparatus 500. [

The power transmitter 540 includes at least one power transmission antenna (not shown), for example an LC resonant circuit, and a matching circuit for impedance matching (not shown) for wirelessly transmitting the AC power signal output from the inverter 530 Time).

Further, when the power transmitter 540 is provided with a plurality of transmission coils, the power transmitter 540 may further include a selection switching circuit for selecting a transmission coil to be used for transmission of radio power among a plurality of transmission coils.

The power transmitter 540 may further include various sensing circuits for measuring the intensity of power input from the inverter 530 or the intensity and temperature of power transmitted through the transmission coil. Here, the sensing result may be transmitted to the main controller 510.

In particular, the internal oscillator frequency of the VF SMPS 560 according to the present invention can be dynamically changed according to the frequency switching control signal supplied from the main controller 510, hereinafter referred to as FREQ_SW for convenience of explanation.

Accordingly, the wireless power transmission apparatus according to the present invention can lower the overall noise level by varying the reference frequency at regular intervals without fixing the switching frequency of the SMPS, thereby improving EMI (electromagnetic interference) performance.

Commercial SMPSs in conventional wireless charge transfer systems have a fixed internal oscillator frequency (typically 400 kHz). Therefore, there has been a problem that electromagnetic interference is generated at a fourfold frequency of the fundamental frequency.

A method of changing the internal oscillator frequency in the VF SMPS 560 according to the present invention and a circuit configuration therefor will become more apparent from the description of FIG. 6 to FIG. 10 to be described later.

6 is a block diagram illustrating a detailed structure of a wireless power transmission apparatus with improved EMI performance according to an embodiment of the present invention.

Referring to FIG. 6, the VF SMPS 560 of FIG. 5 may include an SMPS IC 561 and a switch frequency control circuit 561.

Here, the switching frequency control circuit 561 may be controlled by the main controller 510. For example, the main controller 510 may generate a predetermined frequency switching signal FREQ_SW in the form of a pulse and supply it to the switching frequency control circuit 561. The switching frequency control circuit 561 may be provided with a resistance control switch. Here, the resistance control switch can be driven in accordance with FREQ_SW. For example, the resistance control switch may be a 2-channel analog switch, but this is only one embodiment, and an analog switch having three or more channels depending on the number of resistors provided in the switching frequency control circuit 561 .

7 is a diagram for explaining the pin arrangement and circuit configuration of the commercial SMPS IC LM25118.

Referring to reference numeral 560 in FIG. 7, the internal oscillator frequency of the commercial SMPS 700 is determined by the resistance component connected to the RT port.

For example, in the case of the commercial SMPS LM25118, the relation between the reference frequency f and the resistance value R _T of the resistance element connected to the RT port can be determined by the following equation (1).

[Equation 1]

The number of resistors connected to the RT port of the commercial SMPS 700 is one. Thus, the commercial SMPS 700 uses a fixed internal oscillator frequency (hereinafter, used in combination with the fundamental frequency). However, when a fixed fundamental frequency is used, there is a problem that a specific multiplied frequency component of the fundamental frequency generates electromagnetic interference.

That is, the harmonic component of the fundamental frequency can act as an electromagnetic interference component of another predefined frequency band - for example, the lyoth frequency band. In particular, when only one fixed fundamental frequency is used, a specific frequency with a power density peak is generated, and thus an EMI noise component can be generated.

Therefore, it is important that a variable fundamental frequency is supplied so that the EMI noise due to the harmonic component of the fundamental frequency is distributed in the frequency axis.

The wireless power transmission apparatus according to an embodiment of the present invention can reduce the overall noise level by dispersing EMI noise bouncing from one specific fundamental frequency to the peak through frequency switching.

8 is a diagram for explaining a switching frequency control circuit structure for improving EMI performance of a wireless power transmission apparatus according to an embodiment of the present invention.

8, the switching frequency control circuit 820 of the wireless power transmission apparatus 800 for improving EMI performance may be connected to the main controller 810 and the SMPS IC 830.

The switching frequency control circuit 820 according to an embodiment may include a first resistance element 821, a second resistance element 822, and a resistance control switch 823. [ Here, the resistance control switch 823 can be controlled according to the FREQ_SW received from the main controller 810. [

When the resistance control switch 823 is connected to the first terminal 823-1 in accordance with FREQ_SW, the fundamental frequency is determined by the first resistance element 821. [ On the other hand, if the resistance control switch 823 is connected to the second terminal 823-2 in accordance with FREQ_SW, the fundamental frequency is determined by the first resistive element 821 and the second storage element 822 connected in parallel. Thus, the fundamental frequency is determined by the combined resistance of the first resistive element 821 and the second storage element 822 connected in parallel.

For example, the main controller 810 may be a microprocessor chip, and the main controller 810 may supply the FREQ_SW to the switching frequency control circuit 820 through any one of the GPIO (general purpose input output) ports.

In addition, the switching frequency control circuit 820 may be connected to the RT port provided in the SMPS IC 830. [

Although the switching frequency control circuit 820 according to the embodiment of FIG. 8 is shown as being a two-channel analog switch including two resistive elements, this is only one embodiment, and the number of analog channels and corresponding It should be noted that increasing the number of resistive elements may provide a switching frequency control circuit that variably provides three or more fundamental frequencies.

Of course, it should be noted that, when the number of analog channels is increased, the signal level of FREQ_SW can also be increased corresponding to the number of analog channels.

In the above description, the switching frequency control circuit 820 includes a multichannel analog switch. However, the switching frequency control circuit 820 is only one embodiment, and a multichannel digital switch may be used in another embodiment. To this end, the main controller 810 may generate a specific digital signal for controlling the multi-channel digital switch and supply it to the switching frequency control circuit 820.

FIG. 9 is a diagram for explaining an EMI improvement effect of a wireless power transmission apparatus according to an embodiment of the present invention. Referring to FIG.

Referring to FIG. 9, the frequency switch signal FREQ_SW may be a two-level rectangular pulse file having either 0 (Low) or 1 (High), but this is only one example and signals of other waveforms may be used Be careful.

9, the reference numeral 910 in FIG. 9 indicates a switching frequency-changing frequency depending on the FREQ_SW when the first resistive elements R1 and 821 are 12.7 K? In the embodiment of FIG. 8 and the second resistive elements R2 and 822 are 39 K? That is, the fundamental frequency -.

Referring to reference numeral 910, if the level of FREQ_SW is HIGH, the switching frequency is determined to be 500 KHz by the combined resistance of R1 and R2.

On the other hand, if the level of FREQ_SW is LOW, the switching frequency is determined as 400 KHz by R1.

Reference numeral 920 is a diagram for comparing the radiation energy distribution on the frequency axis according to the related art and the present invention.

Reference numeral 921 shows an energy pattern radiated in a conventional SMPS using one fixed reference frequency. The radiation energy of the conventional SMPS has a peak component exceeding the EMI reference value.

However, as shown in reference numeral 922, it can be seen that the energy pattern radiated by the SMPS using the variable reference frequency according to an embodiment of the present invention is maintained below the EMI reference value in the entire frequency band.

Therefore, the variable frequency SMPS according to the present invention has an advantage that the EMI performance of the wireless power transmission apparatus can be improved because the peak component 923 causing the electromagnetic interference can be effectively removed by lowering the overall radiation energy level.

10 to 11 show experimental results of a measuring instrument using a variable frequency SMPS according to the present invention.

10 shows that only the first resistive elements R1 and 821 of the switching frequency control circuit 820 are connected to the RT port of the SMPS IC 830 according to the FREQ_SW signal in the embodiments of FIGS. , The reference frequency measured by the instrument is 401.7045 Khz-that is, about 400 Khz- and the peak voltage value is 11.691 V.

11, the first resistive elements R1 and 821 and the second resistive elements R2 and 822 of the switching frequency control circuit 820 are connected in parallel according to the FREQ_SW signal in the embodiments of FIGS. When connected to the RT port of the SMPS IC 830, the reference frequency measured at the meter is 499.2481 KHz - i.e., about 500 KHz - and the peak voltage value is 11.692 V.

In the embodiments of FIGS. 8 to 9 described above, the first resistive element (R1, 821) of the switching frequency control circuit 820 according to the FREQ_SW signal is connected to the SMPS IC When connected to the RT port of the controller 830, the reference frequency measured by the meter is about 400 KHz.

FIG. 12 is a result of a meter test to explain the effect of the variable frequency SMPS according to the present invention.

12, only the first resistive elements R1 and 821 of the switching frequency control circuit 820 according to the FREQ_SW signal in the embodiments of FIGS. 8 to 9 described above are connected to the RT of the SMPS IC 830 When connected to the port, the reference frequency measured by the instrument is 400.04840 KHz - that is, about 400 KHz - and the peak voltage value is 11.800 V.

8 to 9, the first resistive element Rl 821 and the second resistive element Rl 822 of the switching frequency control circuit 820 are connected to each other in the embodiment of FIGS. ) Is connected to the RT port of the SMPS IC 830 in parallel according to the FREQ_SW signal, the reference frequency measured by the meter is 505.81954Khz, i.e., about 500Khz-, and the peak voltage value is 11.768V.

In particular, when the reference numerals 1210 to 1220 are compared, the peak noise level at 400 KHz and 500 KHz are almost the same, but the average noise level is 500 KHz lower than that of 400 KHz by an average of 10 dB have.

That is, by applying a variable frequency SMPS using a variable frequency switching scheme using a plurality of resistors according to the present invention to a wireless power transmitter rather than a conventional fixed frequency switching scheme using a single resistor, an effect of reducing the overall noise level can be expected. The EMI performance can be improved.

The methods according to the above-described embodiments may be implemented as a program for execution in a computer and stored in a computer-readable recording medium. Examples of the computer-readable recording medium include ROM, RAM, CD- , A floppy disk, an optical data storage device, and the like.

The computer readable recording medium may be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner. And, functional program, code, and code segments for implementing the above-described method can be easily inferred by programmers in the technical field to which the embodiment belongs.

It will be apparent to those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.

Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention.

Claims (18)

A variable frequency switching mode power supply for converting AC power to DC power;
Main controller supplying reference clock;
A gate driver for generating a plurality of switch control signals using the reference clock;
An inverter for generating an AC power signal based on the DC power source and the plurality of switch control signals; And
A power transmitter for wirelessly transmitting the AC power signal;
Wherein the reference frequency of the variable frequency switched mode power supply is variable. The method according to claim 1,
Wherein the variable frequency switched mode power supply varies the reference frequency according to a predetermined frequency switching signal received from the main controller. 3. The method of claim 2,
The variable frequency switched mode power supply
A plurality of resistive elements;
Switching Mode Power Supplier (SMPS) IC; And
And a resistance control switch for switching-controlling the plurality of resistance elements according to the frequency switching signal
And a second power supply. The method of claim 3,
And the resistance control switch is a two-channel analog switch when the number of the resistance elements is two. 5. The method of claim 4,
Wherein the frequency switching signal is a rectangular pulse having two levels. 6. The method of claim 5,
And the two resistive elements are connected in parallel to the RT port of the Switching Mode Power Supplier (SMPS) IC if the level of the frequency switching signal is HIGH. The method according to claim 6,
And one of the two resistive elements is connected to the RT port of the Switching Mode Power Supplier (SMPS) IC when the level of the frequency switching signal is LOW. 8. The method of claim 7,
And the level of the frequency switching signal is changed at a predetermined time period. 3. The method of claim 2,
And transmits the frequency switching signal to the variable frequency switching mode power supply using any one of general purpose input output (GPIO) ports equipped with the main controller. CLAIMS 1. A variable frequency switched mode power supply mounted on a wireless power transmission device for supplying power required for wireless power transmission to a power amplifier,
A Switching Mode Power Supplier IC (SMPS) for controlling the external AC power supply to supply DC power; And
A switching frequency control circuit for providing a resistance value necessary for changing the reference frequency to the SMPS IC according to an external frequency switching signal;
And a variable frequency switching mode power supply. 11. The method of claim 10,
Wherein the frequency switching signal is received from a main controller provided in the wireless power transmitter and the reference frequency is varied at regular time intervals according to the frequency switching signal. 12. The method of claim 11,
The switching frequency control circuit
A plurality of resistive elements; And
And a resistance control switch for switching-controlling the plurality of resistance elements according to the frequency switching signal
And a variable frequency switching mode power supply. 13. The method of claim 12,
Wherein the resistance control switch is a two-channel analog switch if the number of resistance elements is two. 14. The method of claim 13,
Wherein the frequency switching signal is a rectangular pulse having two levels. 15. The method of claim 14,
Wherein the two resistive elements are connected in parallel to the RT port of the Switching Mode Power Supplier (SMPS) IC if the level of the frequency switching signal is HIGH. 16. The method of claim 15,
Wherein one of the two resistive elements is coupled to the RT port of the Switching Mode Power Supplier (SMPS) IC if the level of the frequency switching signal is LOW. 17. The method of claim 16,
Wherein the level of the frequency switching signal is changed at a constant time period. 12. The method of claim 11,
And the frequency switching signal is transmitted to the variable frequency switching mode power supply using any one of general purpose input output (GPIO) ports equipped with the main controller.

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