KR102152670B1 - Wireless Power Transfer System and Operating method thereof - Google Patents

Abstract

A transmission coil, a power converter providing transmission power to the transmission coil, a controller for controlling the power converter by receiving the reception allowable power information and a control error value from a receiving device, the controller includes a new transmission power based on the control error value and A transmission device that determines whether to output the new transmission power based on the reception allowable power information.

Description

Wireless power transmission system and its driving method. {Wireless Power Transfer System and Operating method thereof}

The present invention relates to an electroless power transmission system and a driving method thereof.

In general, various electronic devices include batteries and are driven using electric power charged in the battery. At this time, in the electronic device, the battery may be replaced and may be recharged. To this end, the electronic device includes a contact terminal for contacting an external charging device. That is, the electronic device is electrically connected to the charging device through the contact terminal. However, in an electronic device, as the contact terminal is exposed to the outside, it may be contaminated by foreign substances or shorted by moisture. In this case, there is a problem in that the battery is not charged in the electronic device because a contact failure occurs between the contact terminal and the charging device.

In order to solve the above problems, wireless power transfer (WPT) for wirelessly charging electronic devices has been proposed.

The wireless power transmission system is a technology that transmits power through a space without wires, and is a technology that maximizes the convenience of power supply to mobile devices and digital home appliances.

The wireless power transmission system has strengths such as energy saving through real-time power use control, overcoming space constraints of power supply, and reducing waste battery discharge through battery recharging.

As a method of implementing a wireless power transmission system, representatively, there are a magnetic induction method and a magnetic resonance method. The magnetic induction method is a non-contact energy transmission technology in which an electromotive force is generated in the other coil through a magnetic flux generated by passing a current through one coil by bringing two coils close together, and a frequency of several hundred kHz can be used. The magnetic resonance method is a magnetic resonance technology that uses only electric or magnetic fields without using electromagnetic waves or currents. Since power transmission is possible at a distance of several meters or more, a band of several MHz can be used.

The wireless power transmission system includes a transmitting device for wirelessly transmitting power and a receiving device for receiving power and charging a load such as a battery. At this time, a charging method of the receiving device, that is, any one of a magnetic induction method and a magnetic resonance method may be selected, and a transmitting device capable of wirelessly transmitting power in response to the charging method of the receiving device has been developed.

On the other hand, when the receiving device disposed in the charging area of the transmitting device is intentionally shaken, or when the shaking phenomenon of the receiving device frequently appears, such as in a vehicle, a sudden change in the coupling coefficient caused by misalignment between the transmitting and receiving devices is There has been a problem of causing damage to the reception device due to a sudden change in transmission power.

The embodiment can provide a wireless power transmission system and a driving method thereof capable of solving the instability of power transmission due to a sudden change in a coupling coefficient between a transmission device and a reception device due to shaking of a receiving device during wireless charging.

A power transmission method according to an embodiment is a method of wirelessly transmitting power from a transmitter to a receiver, the method comprising: transmitting a signal for detection by the receiver; Receiving an identification signal from the receiver; Transmitting a first power to the receiver; Receiving a power increase request signal from the receiver; Determining a second transmission coil current based on the first transmission coil current of the transmitter and the power increase request signal; Determining the second power based on the second transmission coil current; And determining whether to transmit the second power by comparing the second power with an amount of power allowed for reception of the receiver and a power threshold value. In addition, the power transmission method according to the embodiment may be provided. In the method, the step of determining whether to transmit the second power may provide a power transmission method of determining whether to transmit the second power according to a difference power amount between the allowable reception power and the second power.

In addition, in the power transmission method according to the embodiment, the determining whether to transmit the second power includes determining whether to transmit the second power according to the difference between the amount of power allowed to receive and the overshoot peak value of the second power. It can provide a power transmission method.

In addition, in the power transmission method according to the embodiment, when the difference power amount exceeds the power threshold value, a power transmission method of stopping the wireless power transmission may be provided.

In addition, in the power transmission method according to the embodiment, when the wireless power transmission is stopped, transmitting a signal for detection of the receiver; a power transmission method may be provided.

In addition, in the power transmission method according to the embodiment, when the receiver is detected, transmitting a preset wireless power; a power transmission method may be provided.

In addition, in the power transmission method according to the embodiment, when the difference power amount is less than or equal to the power threshold, controlling a power conversion unit based on proportional control, integral control, and differential control (hereinafter, PID control); It may provide a power transmission method further comprising.

In addition, in the power transmission method according to the embodiment, the controlling of the power conversion unit based on the PID control includes: determining a control amount based on the PID control; Determining a current control variable based on the control amount and a previous control variable; And transmitting the second power by controlling a power converter based on the control variable this time. The power transmission method may be provided.

In addition, in the power transmission method according to the embodiment, the overshoot peak value may be determined based on at least one of an increase amount from the current first power to the second power and the second power value.

In addition, in the power transmission method according to the embodiment, a power transmission method of adjusting at least one of an input voltage, a driving frequency, and a duty cycle of the power conversion unit based on the control variable may be provided.

In addition, the power receiving method according to the embodiment is a method in which a receiver wirelessly receives power from a transmitter, the method comprising: transmitting a response signal to a first detection signal from the transmitter; Transmitting an identification signal to the transmitter; Receiving a first power from the transmitter; Transmitting a power increase request signal to the transmitter; Determining whether power is received from the transmitter; And transmitting a response signal to a second detection signal from the transmitter when the wireless power reception is stopped.

In addition, in the power receiving method according to the embodiment, receiving a preset power from the transmitter that has received the response signal; may provide a power receiving method further comprising.

In addition, in the power reception method according to the embodiment, the identification signal may provide a power reception method including an amount of power allowed to be received by the receiver.

In addition, in the power receiving method according to the embodiment, when receiving the second power corresponding to the power increase request signal, comparing the second power and the required power; Transmitting a control error value to the transmitter according to the comparison result; The control error value is any one of positive, zero, or negative numbers, the power increase request signal corresponds to a positive control error value, the power maintenance request signal corresponds to a zero control error value, and the power reduction request signal is negative. It is possible to provide a power reception method corresponding to the control error value of.

In addition, a transmitter according to an embodiment includes: a transmission coil for wireless power transmission; A power converter outputting power to the transmitting coil; A controller controlling the power converter to control an amount of power output to the transmitting coil; The controller is a transmitter that determines new power based on a power increase request signal from a reception device, and determines whether to generate the new power based on the new power, a reception allowable power amount and a threshold power value from the reception device. Can provide.

In addition, the transmitter according to the embodiment may provide a transmitter that determines whether to generate the new power according to the difference power amount between the allowable reception power and the new power.

In addition, the transmitter according to the embodiment may provide a transmitter that determines whether to generate the new power according to the difference power amount between the allowable reception power amount and the overshoot peak value of the new power.

In addition, in the transmitter according to the embodiment, the overshoot peak value may be set based on at least one of an increase amount from the current output power of the power converter to the new power and the new power value.

In addition, the transmitter according to the embodiment may provide a transmitter in which generation of the new power is stopped when the difference power value exceeds a power threshold value.

In addition, in the transmitter according to the embodiment, the controller may provide a transmitter that controls the amount of power by adjusting any one of a driving frequency, an input voltage, or a duty cycle of the power converter.

In addition, in the transmitter according to the embodiment, the controller includes: a first calculating unit configured to determine a second current based on a power increase request signal from the receiver and a first current of the transmission coil; A PID control unit that determines a control amount based on proportional control, integral control, and differential control (hereinafter referred to as PID control); And a second calculating unit that determines the current control variable based on the control amount and the previous control variable, and controls the power converter based on the current control variable.

In addition, a receiver according to an embodiment includes: a receiving coil for receiving first power from a transmitter; And a controller communicating with the transmitter; wherein the controller transmits a power increase request signal based on an error between the first power and a requested power, and detects a second power or a receiver based on the power increase request signal A receiver for receiving a (Ping) signal may be provided.

In addition, in the receiver according to the embodiment, the controller may provide a receiver that determines an error between the second power and the requested power when the receiving coil receives the second power.

In addition, in the receiver according to the embodiment, the controller may provide a receiver that transmits a response signal to the detection signal.

In addition, the receiver according to the embodiment may provide a receiver that receives a preset power from the transmitter that has received the response signal.

According to the embodiment, instability of power transmission, heat generation, and system damage of the receiving device can be prevented in advance due to a sudden change in a coupling coefficient between a transmitting device and a receiving device due to shaking of a receiving device during wireless charging.

1 is a magnetic induction method equivalent circuit.
2 is a magnetic resonance method equivalent circuit.
3A and 3B are block diagrams showing a transmitter as one of sub-systems constituting a wireless power transmission system.
4A and 4B are block diagrams showing a receiver as one of sub-systems constituting a wireless power transmission system.
5 is a flowchart illustrating an operation of the wireless power transmission system, focusing on the operation state of the transmission device according to the embodiment.
6 is a flowchart illustrating a method of determining a required power of a receiving device.
7 is a flowchart illustrating a method of determining transmission power of a transmission device.
8 is a flow chart of a transmission device determining whether to transmit power.
9 to 11 are diagrams showing a transient state and a steady state of a power signal over time.
12 is a diagram showing in detail a control unit of a transmission device for a power transmission control method.
13 is a timing diagram of a transmission device in a power transmission state.

Hereinafter, a wireless power transmission system including a transmission device having a function for wirelessly transmitting power and a receiving device for wirelessly receiving power according to an embodiment of the present invention will be described in detail with reference to the drawings. The following embodiments are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. In addition, in the drawings, the size and thickness of the device may be exaggerated for convenience. Throughout the specification, the same reference numbers indicate the same elements.

The embodiment selectively uses various types of frequency bands from low frequency (50 kHz) to high frequency (15 MHz) for wireless power transmission, and may include a communication system capable of exchanging data and control signals for system control. .

The embodiments can be applied to various industrial fields such as the portable terminal industry, the smart watch industry, the computer and notebook industry, the home appliance industry, the electric vehicle industry, the medical device industry, the robot industry, etc. .

The embodiment may consider a system capable of transmitting power to one or more multiple devices using one or a plurality of transmission coils.

According to the embodiment, it is possible to solve the problem of battery shortage in mobile devices such as smartphones and laptops. For example, if you place a wireless charging pad on a table and use a smartphone or laptop on it, the battery is automatically charged and can be used for a long time . In addition, if a wireless charging pad is installed in public places such as cafes, airports, taxis, offices, and restaurants, various mobile devices can be charged regardless of different charging terminals for each mobile device manufacturer. In addition, when wireless power transmission technology is applied to household appliances such as vacuum cleaners and fans, there is no need to search for power cables, and as complicated wires disappear in the home, wiring in the building can be reduced and the width of space utilization can be widened. In addition, it takes a lot of time to charge an electric vehicle with the current household power source, but if high power is transmitted through wireless power transmission technology, the charging time can be shortened. You can relieve the inconvenience of having to prepare.

Terms and abbreviations used in the examples are as follows.

Wireless Power Transfer System: A system that provides wireless power transfer within a magnetic field.

Transmitter (Wireless Power Transfer System-Charger; Power Transfer Unit: PTU): A device that provides wireless power transfer to a power receiver within a magnetic field and manages the entire system. It can be referred to as a transmitter or a transmitter.

Receiver (Wireless Power Receiver System-Device; Power Receiver Unit: PRU): A device that receives wireless power transmission from a power transmitter within a magnetic field, and can be referred to as a receiver or receiver.

Charging Area: An area where actual wireless power transmission takes place within the magnetic field area, and may vary depending on the size of the application product, the required power, and the operating frequency.

S parameter (Scattering parameter): The S parameter is the ratio of the input voltage to the output voltage in the frequency distribution. The reflected output value (Reflection; S11, S22).

Quality factor Q (Quality factor): In resonance, the value of Q means the quality of frequency selection, the higher the Q value, the better the resonance characteristic, and the Q value is expressed as the ratio of the energy stored in the resonator and the energy lost.

Looking at the principle of wireless power transmission, there are largely a magnetic induction method and a magnetic resonance method as the principle of wireless power transmission.

The magnetic induction method is a non-contact energy transmission technology in which an electromotive force is generated in the load inductor (Ll) as a medium through the magnetic flux generated when the source inductor (Ls) and the load inductor (Ll) are brought close to each other and current flows through one source inductor (Ls). to be. And the magnetic resonance method combines two resonators, and energy is transmitted wirelessly using a resonance technique that generates an electric field and a magnetic field in the same wavelength range while vibrating at the same frequency by generating magnetic resonance due to the natural frequency between the two resonators. It is a skill to do.

1 is a magnetic induction method equivalent circuit.

Referring to FIG. 1, in the magnetic induction equivalent circuit, the transmitter performs magnetic coupling with the source voltage (Vs), the source resistance (Rs), the source capacitor (Cs) for impedance matching, and the receiver according to the device supplying power. It can be implemented as a source coil (Ls) for the receiver, and the receiver is implemented with a load resistance (Rl) that is an equivalent resistance of the receiver, a load capacitor (Cl) for impedance matching, and a load coil (Ll) for magnetic coupling with the transmitter. The degree of magnetic coupling between the source coil Ls and the load coil Ll can be expressed as mutual inductance Msl.

In Fig. 1, the maximum power transmission condition is obtained by obtaining the ratio of the input voltage to the output voltage (S21) from a self-induction equivalent circuit consisting only of a coil without a source capacitor (Cs) and a load capacitor (Cl) for impedance matching. The power transmission condition satisfies Equation 1 below.

Equation 1

Ls/Rs=Ll/Rl

According to Equation 1, maximum power transmission is possible when the ratio of the inductance of the transmission coil Ls and the source resistance Rs and the inductance of the load coil Ll and the load resistance Rl are the same. In a system with only inductance, since there is no capacitor capable of compensating for reactance, the value of the self-reflection value (S11) of the input/output port at the point where the maximum power transfer is achieved cannot be 0, and the mutual inductance ( Msl) value can greatly change the power transfer efficiency. Thus, the source capacitor Cs may be added to the transmitter as a compensation capacitor for impedance matching, and the load capacitor Cl may be added to the receiver. The compensation capacitors Cs and Cl may be connected in series or parallel to each of the receiving coil Ls and the load coil Ll, for example. In addition, passive elements such as additional capacitors and inductors may be further added to each of the transmitter and receiver for impedance matching.

2 is a magnetic resonance equivalent circuit.

Referring to FIG. 2, in the self-resonant equivalent circuit, the transmitting unit comprises a source coil and a transmitting-side resonance inductor forming a closed circuit by serial connection of a source voltage (Vs), a source resistance (Rs), and a source inductor (Ls). (L1) and the transmitting-side resonance capacitor (C1) are connected in series and implemented as a transmitting-side resonant coil constituting a closed circuit, and the receiving unit establishes a closed circuit by connecting the load resistance (Rl) and the load inductor (Ll) in series. It is implemented as a receiving-side resonance coil constituting a closed circuit by serial connection of a load coil, a receiving-side resonance inductor (L2) and a receiving-side resonance capacitor (C2), and a source inductor (Ls) and a transmitting-side inductor ( L1) is magnetically coupled with the coupling coefficient of K01, the load inductor Ll and the load-side resonance inductor (L2) are magnetically coupled with the coupling coefficient of K23, and the transmission-side resonance inductor (L1) and the receiving-side resonance inductor (L2) is magnetically coupled with the coupling coefficient of K12. In the equivalent circuit of another embodiment, the source coil and/or the load coil may be omitted, and only the transmitting-side resonance coil and the receiving-side resonance coil may be formed.

In the magnetic resonance method, when the resonance frequencies of the two resonators are the same, most of the energy of the resonator of the transmitter is transferred to the resonator of the receiver, so that power transfer efficiency can be improved, and the efficiency in the magnetic resonance method can satisfy Equation 2 below. When it gets better.

Equation 2

k/Γ >> 1 (k is the coupling coefficient, Γ attenuation rate)

In order to increase the efficiency in the magnetic resonance method, an element for impedance matching may be added, and the impedance matching element may be a passive element such as an inductor and a capacitor.

Based on the wireless power transmission principle, a wireless power transmission system for transmitting power using a magnetic induction method or a magnetic resonance method will be described.

<Sending Department>

3A and 3B are block diagrams illustrating a transmitter as one of sub-systems constituting a wireless power transmission system.

Referring to FIG. 3A, the wireless power transmission system according to the embodiment may include a transmission unit 1000 and a reception unit 2000 that receives power wirelessly from the transmission unit 1000. The transmission unit 1000 generates a magnetic field based on an AC signal output from the transmission side power conversion unit 101 and the transmission side power conversion unit 101 that converts the power of the input AC signal and outputs the AC signal to be charged. Controls the power conversion of the transmission-side resonant circuit unit 102 and the transmission-side power conversion unit 101 providing power to the receiving unit 2000 in the region, and the amplitude of the output signal of the transmission-side power conversion unit 101 Adjusts the frequency, performs impedance matching of the transmission-side resonance circuit unit 102, senses impedance, voltage, and current information from the transmission-side power conversion unit 101 and the transmission-side resonance circuit unit 102, and the It may include a transmitting-side control unit 103 capable of wireless communication with the receiving unit 2000. The transmission-side power conversion unit 101 may include at least one of a power conversion unit for converting an AC signal to DC, a power conversion unit for outputting DC by varying a level of DC, and a power conversion unit for converting DC to AC. I can. In addition, the transmission-side resonance circuit unit 102 may include a coil and an impedance matching unit capable of resonating with the coil. In addition, the transmission-side control unit 103 may include a sensing unit and a wireless communication unit for sensing impedance, voltage, and current information.

Also, referring to FIG. 3B, the transmission unit 1000 includes a transmission-side AC/DC converter 1100, a transmission-side DC/AC conversion unit 1200, a transmission-side impedance matching unit 1300, and a transmission coil unit 1400. And it may include a transmission side communication and control unit 1500.

The transmission side AC/DC conversion unit 1100 is a power conversion unit that converts an AC signal provided from the outside into a DC signal under the control of the transmission side communication and the control unit 1500, and the transmission side AC/DC conversion unit 1100 May include a rectifier 1110 and a transmission-side DC/DC converter 1120 as a subsystem. The rectifier 1110 is a system that converts a provided AC signal into a DC signal, and is an embodiment that implements this. A diode rectifier having a relatively high efficiency during high frequency operation, a one-chip synchronous rectifier or cost And it is possible to save space and can be a hybrid rectifier having a high degree of freedom in dead time. However, it is not limited thereto, and can be applied to a system that converts AC to DC. In addition, the transmission-side DC/DC converter 1120 controls the level of the DC signal provided from the rectifier 1110 under the control of the transmission-side communication and control unit 1500. For example, the level of the input signal is lowered. It may be a buck converter, a boost converter that increases the level of an input signal, a buck boost converter that can lower or increase the level of an input signal, or a Cuk converter. In addition, the transmission-side DC/DC converter 1120 includes a switch element serving as a power conversion control function, an inductor and a capacitor serving as a power conversion medium or output voltage smoothing function, and a voltage gain control or electrical separation function (insulation function). A transformer or the like may be included, and may function to remove a ripple component or a pulsation component (AC component included in the DC signal) included in the input DC signal. In addition, an error between the command value of the output signal of the transmitting DC/DC converter 1120 and the actual output value may be adjusted through a feedback method, which may be achieved by the transmitting communication and the control unit 1500. .

The transmission-side DC/AC converter 1200 converts the DC signal output from the transmission-side AC/DC converter 1100 into an AC signal under the control of the transmission-side communication and control unit 1500, and converts the frequency of the converted AC signal. An example of implementing this as a system that can control the system is a half bridge inverter or a full bridge inverter. In addition, various amplifiers that convert DC into AC can be applied to the wireless power transmission system, for example, A class, B class, AB class, C class, E class F class amplifier. In addition, the transmission-side DC/AC converter 1200 may include an oscillator generating a frequency of an output signal and a power amplifier amplifying an output signal.

The configurations of the AC/DC converter 1100 and the transmission-side DC/AC converter 1200 may be replaced with an AC power supply, or may be omitted or replaced with another configuration.

The transmission-side impedance matching unit 1300 minimizes reflected waves at points having different impedances to improve signal flow. Since the two coils of the transmitting unit 1000 and the receiving unit 2000 are spatially separated, there is a lot of leakage of the magnetic field, so the difference in impedance between the two connecting terminals of the transmitting unit 1000 and the receiving unit 2000 is corrected to improve power transfer efficiency. I can make it. The transmission-side impedance matching unit 1300 may be composed of at least one of an inductor, a capacitor, and a resistance element, and under the control of the communication and control unit 1500, the inductance of the inductor, the capacitance of the capacitor, and the resistance value of the resistor are varied You can adjust the impedance value for matching. And when the wireless power transmission system transmits power in a magnetic induction method, the transmission-side impedance matching unit 1300 may have a series resonance structure or a parallel resonance structure, and an inductive coupling between the transmission unit 1000 and the reception unit 2000 Energy loss can be minimized by increasing the coefficient. In addition, when the wireless power transmission system transmits power in a self-resonant manner, the transmission-side impedance matching unit 1300 may change the separation distance between the transmission unit 1000 and the reception unit 2000, or a metallic foreign object (FO), It is possible to perform real-time correction of impedance matching according to the change of matching impedance on the energy transmission line due to the change of the characteristics of the coil according to the mutual influence of the device. It may be a matching method, a method using a multi-loop, or the like.

The transmitting-side coil 1400 may be implemented as a plurality of coils or a singular number of coils, and when a plurality of transmitting-side coils 1400 are provided, they may be spaced apart from each other or disposed to overlap each other, and they may be disposed to overlap. In this case, the overlapping area can be determined in consideration of variations in magnetic flux density. In addition, when manufacturing the transmitting-side coil 1400, it may be manufactured in consideration of internal resistance and radiation resistance. In this case, when the resistance component is small, a quality factor may increase and transmission efficiency may increase.

The communication and control unit 1500 may include a transmission-side control unit 1510 and a transmission-side communication unit 1520. The transmission-side control unit 1510 considers at least one of a power request amount of the receiving unit 2000, a current charge amount, a voltage (Vrect) of the rectifier output terminal of the receiving unit, each charging efficiency of a plurality of receiving units, and a wireless power method. It may play a role of adjusting the output voltage of the /DC converter 1100 (or the current flowing through the transmission coil (Itx_coil). And driving the transmission side DC/AC converter 1200 in consideration of maximum power transmission efficiency) The power to be transmitted can be controlled by generating frequency and switching waveforms for the reception unit 2000. Also, the operation of the reception unit 2000 using an algorithm, program, or application required for control read from the storage unit (not shown) of the reception unit 2000 Meanwhile, the transmission-side control unit 1510 may be referred to as a microprocessor, a microcontroller unit, or a Micom, and the transmission-side communication unit 1520 is a receiving-side communication unit. 2620), and as an example of a communication method, a short-range communication method such as Bluetooth, NFC, Zigbee, etc. may be used. The transmitting-side communication unit 1520 and the receiving-side communication unit 2620 provide charging status information between each other. And transmission and reception of a charge control command, etc. And the charging status information includes the number of receivers 2000, remaining battery capacity, number of times of charging, usage, battery capacity, battery ratio, and transmission power amount of the transmitter 1000. In addition, the transmission-side communication unit 1520 may transmit a charging function control signal that controls the charging function of the receiving unit 2000, and the charging function control signal controls the receiving unit 2000 to enable the charging function. It may be a control signal to enable (enabled) or disable (disabled).

In this way, the transmitting-side communication unit 1520 may communicate in an out-of-band format configured as a separate module, but is not limited thereto, and the receiving unit uses the power signal transmitted by the transmitting unit. Communication can also be performed in an in-band format in which the transmitter transmits a signal to the receiver by using a feedback signal transmitted to the transmitter and by shifting the frequency of the power signal transmitted by the transmitter. have. For example, the receiver may modulate the feedback signal to transmit information such as charging start, charging end, and battery status to the transmitter through the feedback signal. In addition, the transmitting-side communication unit 1520 may be configured separately from the transmitting-side control unit 1510, and the receiving unit 2000 and the receiving-side communication unit 2620 may be included in or separately configured in the control unit 2610 of the receiving device. have.

In addition, the transmission unit 1000 of the wireless power transmission system according to the embodiment may further include a detection unit 1600.

The detection unit 1600 includes an input signal of the transmitting AC/DC converter 1100, an output signal of the transmitting AC/DC converter 1100, an input signal of the transmitting DC/AC converter 1200, and The output signal of the DC/AC converter 1200, the input signal of the transmission-side impedance matching unit 1300, the output signal of the transmission-side impedance matching unit 1300, the input signal of the transmission-side coil 1400, or a transmission-side coil ( At least one of the signals on 1400) may be detected. As an example, the signal may include at least one of information on current, information on voltage, and information on impedance. The detected signal is fed back to the communication and control unit 1500, and based on this, the communication and control unit 1500 uses the transmission side AC/DC conversion unit 1100, the transmission side DC/AC conversion unit 1200, and the transmission side impedance matching. The unit 1300 can be controlled. Also, the communication and control unit 1500 may perform foreign object detection (FOD) based on the detection result of the detection unit 1600. In addition, the detected signal may be at least one of voltage and current. Meanwhile, the detection unit 1600 may be configured with hardware different from the communication and control unit 1500 or may be implemented as one piece of hardware.

<Receiver>

4A and 4B are block diagrams illustrating a receiving unit (or receiving device) as one of sub-systems constituting a wireless power transmission system. Referring to FIG. 4A, the wireless power transmission system according to the embodiment may include a transmission unit 1000 and a reception unit 2000 that receives power wirelessly from the transmission unit 1000. The reception device 2000 converts AC power from the reception side resonance circuit unit 201 and the reception side resonance circuit unit 201 to receive the AC signal transmitted from the transmission device 1000 and outputs a DC signal. A load 2500 charged by receiving the DC signal output from the receiving-side power conversion unit 202 and the receiving-side power conversion unit 202 and sensing the current voltage of the receiving-side resonance circuit unit 201, or Performs impedance matching of the side resonance circuit unit 201, controls power conversion of the receiving side power conversion unit 202, adjusts the level of the output signal of the receiving side power conversion unit 202, or Sensing the input or output voltage or current of the power conversion unit 202, controlling whether the output signal of the receiving-side power conversion unit 202 is supplied to the load 2500, or communicating with the transmitting device 1000 It may include a receiving-side control unit 203 capable of. In addition, the receiving-side power conversion unit 202 may include a power conversion unit for converting an AC signal to DC, a power conversion unit for outputting DC by varying a level of DC, and a power conversion unit for converting DC to AC. In addition, referring to FIG. 4B, the wireless power transmission system according to the embodiment includes a transmission unit (or transmission device) 1000 and a reception unit (or reception device) 2000 that receives power wirelessly from the transmission unit 1000. The receiving unit 2000 may include a receiving-side resonant circuit unit 2120 comprising a receiving-side coil unit 2100 and a receiving-side impedance matching unit 2200, a receiving-side AC/DC conversion unit 2300, and DC/ It may include a DC converter 2400, a load 2500, and a communication and control unit 2600 on the receiving side. In addition, the receiving-side AC/DC converter 2300 may be referred to as a rectifier that rectifies an AC signal into a DC signal.

The receiving-side coil unit 2100 may receive power through a magnetic induction method or a magnetic resonance method. In this way, at least one or more of an induction coil or a resonance coil may be included according to the power reception method.

In one embodiment, the receiving-side coil unit 2100 may be disposed in a mobile terminal together with an antenna for near field communication (NFC). In addition, the receiving coil unit 2100 may be the same as the transmitting coil unit 1400, and the size of the receiving antenna may vary according to the electrical characteristics of the receiving unit 200.

The receiving-side impedance matching unit 2200 performs impedance matching between the transmitter 1000 and the receiver 2000.

The receiving-side AC/DC converter 2300 rectifies the AC signal output from the receiving-side coil unit 2100 to generate a DC signal. And the output voltage of the receiving-side AC/DC converter 2300 may be referred to as a rectified voltage, and the receiving-side communication and control unit 2600 is an output voltage of the receiving-side AC/DC converter 2300 May be detected or changed, the minimum rectified voltage Vrect_min (or referred to as the minimum output voltage Vrect_min), which is the minimum value of the output voltage of the receiving AC/DC converter 2300, and the maximum rectified voltage Vrect_max. ) (Or referred to as the maximum output voltage (Vrect_max)), information on the optimum rectified voltage (Vrect_set) (or referred to as the optimum output voltage (Vrect_set)) having one of the voltage values between the minimum and maximum values, and The same state parameter information may be transmitted to the transmitter 1000.

The receiving-side DC/DC converter 2400 may adjust the level of the DC signal output from the receiving-side AC/DC converter 2300 according to the capacity of the load 2500.

The load 2500 may include a battery, a display, an audio output circuit, a main processor, a battery manager, and various sensors. In addition, the load 2500 may include at least a battery 2510 and a battery management unit 2520 as shown in FIG. 4A. The battery manager 2520 may detect a state of charge of the battery 2510 and adjust a voltage and a current applied to the battery 2510.

The receiving-side communication and control unit 2600 may be activated by a wake-up power from the transmitting-side communication and control unit 1500, and perform communication with the transmitting-side communication and control unit 1500, and serve as a sub of the receiving unit 2000. You can control the operation of the system.

The receiving unit 2000 may be composed of a single number or a plurality of units, and simultaneously receive energy wirelessly from the transmitting unit 1000. That is, in the self-resonant wireless power transmission system, a plurality of target receivers 2000 may receive power from one transmitter 1000. In this case, the transmission-side matching unit 1300 of the transmission unit 1000 may adaptively perform impedance matching between the plurality of receiving units 2000. This can be applied equally to a case in which a plurality of mutually independent receiving coil units are provided in the magnetic induction method.

In addition, when the receiving unit 2000 is configured in a plurality, the power reception method may be the same system or different types of systems. In this case, the transmitter 1000 may be a system that transmits power in a magnetic induction method or a magnetic resonance method, or a system in which both methods are mixed.

On the other hand, looking at the relationship between the signal size and frequency of the wireless power transmission system, in the case of the magnetic induction type wireless power transmission, the transmission side AC/DC converter 1100 in the transmission unit 1000 has several tens or hundreds of V units (for example, 110V~220V) of dozens or hundreds of Hz (for example, 60Hz) of AC signal is applied and converted into a DC signal of several to tens of V, hundreds of V (for example, 10V to 20V) and output. The side DC/AC converter 1200 may receive a DC signal and output an AC signal in the KHz band (for example, 125 KHz). In addition, the reception side AC/DC converter 2300 of the reception unit 2000 receives an AC signal in the KHz range (for example, 125KHz), and receives a DC signal in the range of several V to tens and hundreds of V (for example, 10V to 20V). It may be converted into a signal and output, and the receiving-side DC/DC converter 2400 may output a DC signal suitable for the load 2500, for example, 5V, and transmit it to the load 2500. And, in the case of wireless power transmission of the self-resonant method, the transmission-side AC/DC converter 1100 in the transmission unit 1000 is in the tens or hundreds of V bands (for example, 110V to 220V) of tens or hundreds of Hz (for example, 60Hz) of AC signal can be applied and converted into a DC signal of several V to tens of V and hundreds of V (for example, 10 V to 20 V) and output, and the DC/AC converter 1200 on the transmitting side applies a DC signal. It can receive and output an AC signal in the MHz band (for example, 6.78 MHz). In addition, the receiving side AC/DC converter 2300 of the receiving unit 2000 receives an AC signal of MHz (for example, 6.78 MHz) and receives an AC signal of several V to tens of V and hundreds of V (for example, 10 V to 20 V). The DC signal may be converted and output, and the DC/DC converter 2400 may output a DC signal suitable for the load 2500, for example, 5V, and transmit it to the load 2500.

<Operation status of transmitting device>

5 is a flowchart illustrating an operation of the wireless power transmission system, focusing on the operation state of the transmission device according to the embodiment.

Referring to FIG. 5, the transmitter according to the embodiment may have at least 1) a selection state, 2) a detection state, 3) an identification and setting state, 4) a power transfer state, and 5) a charging end state.

[Selection Phase]

(1) In the selected state, the transmitting device 1000 may perform a detection process to select the receiving device 200 existing in the sensing area or the charging area.

(2) The sensing area or the charging area, as described above, may refer to an area in which an object in the corresponding area can affect the power characteristic of the transmission-side power conversion unit 101. Compared with the detection state, the detection process for selection of the reception device 2000 in the selection state is performed by the transmission device 1000 side instead of receiving a response from the reception device 2000 using a power control message. This is a process of checking whether an object exists within a certain range by detecting a change in the amount of power for forming a wireless power signal in the power converter of. The detection process in the selected state may be referred to as an analog detection process (analog ping) in that an object is detected using a wireless power signal instead of using a digital packet in a detection state to be described later.

(3) In the selected state, the transmission device 1000 may detect that an object enters or leaves the sensing area or the charging area. In addition, the transmission device 1000 may distinguish between the receiving device 2000 capable of wirelessly transmitting power among objects in the sensing area or the charging area and other objects (eg, keys, coins, etc.). .

As described above, since the distance at which power can be transmitted wirelessly is different according to the inductive coupling method and the resonance coupling method, the sensing regions in which an object is detected in the selected state may be different from each other.

(4) First, when power is transmitted according to the inductive coupling method, the transmission device 1000 in the selected state may monitor the interface surface (not shown) to detect the placement and removal of objects.

In addition, the transmission device 1000 may detect the position of the wireless power receiver 2000 placed on the interface surface.

(5) When the transmission device 1000 includes one or more transmission coils, the selection state enters the detection state, and in the detection state, a response to the detection signal is transmitted from the object using each coil. It can be checked whether or not, or after entering the identification state, a method of checking whether identification information is transmitted from the object may be performed.

The transmission device 1000 may determine a coil to be used for wireless power transmission based on the sensed position of the reception device 2000 obtained through such a process.

(6) In addition, when power is transmitted according to the resonance coupling method, the transmission device 1000 in the selected state changes one or more of the frequency, current, and voltage of the power converter due to an object in the sensing area or the charging area. The object can be detected by detecting what is being done.

(7) Meanwhile, the transmission device 1000 in the selected state may detect an object by at least one of a detection method according to the inductive coupling method and the resonance coupling method.

(8) The transmission device 1000 may perform an object detection process according to each power transmission method, and then select a method for detecting the object from a combination method for wireless power transmission in order to proceed to other states. .

(9) On the other hand, the transmission device 1000 in the selected state includes a wireless power signal formed to detect an object and a wireless power signal formed for digital detection, identification, setting and power transmission in subsequent states. And strength may be different. This is because the selection state of the transmission device 1000 corresponds to an idle phase for detecting an object, and the transmission device 1000 reduces power consumption in standby or generates a specialized signal for efficient object detection. This is to make it possible to do it.

[Detection Status (Ping Phase)]

(1) In the detection state, the transmission device 1000 may perform a process of detecting the reception device 2000 existing in the sensing area or the charging area through a power control message. Compared with the detection process of the receiving device 2000 using the characteristics of the wireless power signal in the selected state, the detection process in the detection state may be referred to as a digital ping process.

(2) The transmission device 1000 forms a wireless power signal for detecting the reception device 2000, demodulates the wireless power signal modulated by the reception device 2000, and uses the demodulated wireless power signal. A power control message in the form of digital data corresponding to a response to the detection signal may be obtained.

(3) The transmitting device 1000 may recognize the receiving device 2000 to be a target of power transmission by receiving a power control message corresponding to a response to the detection signal.

(4) The detection signal formed by the transmission device 1000 in the detection state to perform the digital detection process may be a wireless power signal formed by applying a power signal of a specific operating point for a predetermined time.

The operating point here may mean a frequency, a duty cycle, and an amplitude of a voltage applied to the transmission coil unit 1400.

The transmission device 1000 may generate the detection signal generated by applying the power signal of the specific operation point for a predetermined period of time, and attempt to receive a power control message from the reception device 2000.

(5) On the other hand, the power control message corresponding to the response to the detection signal may be a message indicating the strength of the wireless power signal received by the receiver 2000. For example, the receiving device 2000 may transmit a signal strength packet including a message indicating the strength of the received wireless power signal as a response to the detection signal. The packet may be configured to include a header indicating that the packet is a packet indicating signal strength and a message indicating the strength of the power signal received by the receiving apparatus 2000. The strength of the power signal in the message may be a value indicating a degree of coupling for power transmission between the transmitting device 1000 and the receiving device 2000.

(6) After receiving the response message to the detection signal and discovering the reception device 2000, the transmission device 1000 may extend the digital detection process to enter the identification and detection state. That is, after discovering the receiving device 2000, the transmission device 1000 may maintain the power signal of the specific operation point and receive a power control message required in the identification and detection state.

However, when the transmission device 1000 does not find the reception device 2000 capable of transmitting power, the operating state of the transmission device 1000 may return to the selected state.

[Identification and Configuration Phase]

(1) In the identification and setting state, the transmitting device 1000 may receive identification information and/or setting information transmitted from the receiving device 2000 and control the power to be efficiently delivered.

(2) In the identification and setting state, the receiving device 2000 may transmit a power control message including its identification information. To this end, the receiving device 2000 may transmit, for example, an identification packet including a message indicating identification information of the receiving device 2000. The packet may be configured to include a header indicating that it is a packet indicating identification information and a message including identification information of the receiving device 2000. The message may be configured to include information indicating a version of a protocol for wireless power transmission, information identifying a manufacturer of the receiving device 2000, information indicating the presence or absence of an extended device identifier, and a basic device identifier. In addition, when the information indicating the presence or absence of the extended device identifier indicates that the extended device identifier exists, an extended identification packet including the extended device identifier may be separately transmitted. The packet may be configured to include a header indicating that it is a packet indicating the extended device identifier and a message including the extended device identifier. When the extended device identifier is used as described above, information based on the manufacturer's identification information, the basic device identifier, and the extended device identifier may be used to identify the receiving device 2000.

(3) In the identification and setting state, the receiving device 2000 may transmit a power control message including information on the expected maximum power. To this end, the receiving device 2000 may transmit, for example, a configuration packet. The packet may be configured to include a header indicating that it is a configuration packet and a message including information on the expected maximum power.

In addition, the receiving device 2000 may transmit a power control message including information on its own allowable amount of allowable reception power. However, the information on the allowable reception power amount of the reception device 2000 may be provided to the transmission device 1000 even in a power delivery state other than the identification and setting state.

The message may be configured to include a power class, information on an expected maximum power, an indicator indicating a method of determining a current of a main cell of the wireless power transmitter 1000, and the number of optional configuration packets. The indicator may indicate whether the current of the main cell of the transmission device 1000 is to be determined as specified in the protocol for wireless power transmission.

(4) On the other hand, the transmission device 1000 may generate a power transfer contract used for power charging with the reception device 2000 based on the identification information and/or setting information. The power transfer protocol may include limits of parameters that determine power transfer characteristics in the power transfer state.

(5) The transmission device 1000 may terminate the identification and setting state before entering the power delivery state and return to the selected state. For example, the transmitting device 1000 may end the identification and setting state in order to find another receiving device 2000 capable of wirelessly receiving power.

[Power Transfer Phase]

(1) The transmission device 1000 in the power transmission state transmits power to the reception device 2000.

(2) The transmitting device 1000 receives a power control message from the receiving device 2000 while transmitting power, and the characteristics of the power applied to the transmitting coil unit 1400 in response to the received power control message Can be adjusted. For example, a power control message used to adjust the power characteristics of the transmission coil may be included in a control error packet. The packet may be configured to include a header indicating that the packet is a control error packet and a message including a control error value. The transmission device 1000 may adjust the power applied to the transmission coil according to the control error value. That is, when the control error value is 0, the desired control point required by the receiving device 2000 and the actual control point of the receiving device 2000 are substantially the same. The applied current is maintained and can be adjusted to decrease in the case of a negative value and increase in the case of a positive value.

(3) In the power transmission state, the transmission device 1000 may monitor parameters in a power transfer contract generated based on the identification information and/or setting information. As a result of monitoring the parameters, when power transmission with the receiving device 2000 violates the limitations included in the power transfer protocol, the transmitting device 1000 cancels the power transmission and returns to the selected state. I can go.

(4) On the other hand, the power transfer protocol is the boundary conditions regarding the maximum amount of power that the receiving device 2000 can receive (receivable power) and the characteristics of the power transmitted from the transmitting device 1000 to the receiving device 2000. ) Can be included. In addition, the power transfer contract includes an over shoot that occurs in a transient state before reaching a normal state of a target power signal due to an increase in transmission power, and the allowable reception power or a target new power signal and the It may include information on a power threshold set based on the allowable reception power.

(5) The transmission device 1000 may terminate the power transmission state based on the power control message transmitted from the reception device 2000.

For example, when the charging of the battery is completed while the receiving device 2000 is charging the battery using the transmitted power, a power control message requesting to stop the wireless power transmission to the transmitting device 1000 is sent. I can deliver. In this case, after receiving a message requesting to stop the power transmission, the transmission device 1000 may terminate wireless power transmission and return to the selected state.

For another example, the receiving device 2000 may transmit a power control message requesting renegotiation or reconfigure in order to update an already generated power transfer protocol. The receiving device 2000 may transmit a message requesting renegotiation of the power transfer protocol when more or less power than the amount of power currently transmitted is required. In this case, after receiving a message requesting renegotiation of the power transfer protocol, the transmission device 1000 may terminate wireless power transmission and return to the identification and setting state.

To this end, the message transmitted by the receiving device 2000 may be, for example, an End Power Transfer Packet as shown in FIG. 18. The packet may be configured to include a message including a header indicating that the packet is a power transmission stop packet and a power transmission stop code indicating the reason for the stop. The power transmission interruption code includes: Charge Complete, Internal Fault, Over Temperature, Over Voltage, Over Current, Battery Failure, Reconfigure, It may represent either No Response or Unknown Error.

Meanwhile, the transmission device 1000 may stop power transmission when the amount of power calculated from the current transmission power, the new transmission power that is the target power to be transmitted, and the allowable reception power during transmission exceed the power threshold.

6 is a flowchart illustrating a method of determining a required power of a receiving device, and FIG. 7 is a flowchart illustrating a method of determining a transmission power of a transmitting device.

<Power transmission control>

-How to determine the required power of the receiving device.

Referring to FIG. 6, the receiving apparatus 2000 includes 1) determining a desired control point (S210), 2) detecting an actual control point (S230), and 3 ) The power to be received, that is, the required power, may be determined by performing a control error value generating step S250.

In step S210 of determining a specific desired control point (S210), the receiving device 2000 may determine a required control point for voltage, current, temperature, and the like. In addition, in the step S230 of detecting an actual control point, the receiving device 2000 may determine an actual control point regarding an actual voltage, current, temperature, and the like. When the receiving device 2000 determines the actual control point, various methods such as voltage or current detection and temperature sensing may be applied, and such a process may be performed at any time in the power transmission state. In addition, in the control error value generating step S250, the reception device 2000 may generate a control error value based on, for example, a difference between a required control voltage value and an actual control voltage value. In addition, the control error value may be a parameter indicating a positive value and a negative value, and when the actual amount of power is smaller than the required amount of power, the control error value may refer to a positive value. In many cases, the control error value may refer to a negative value, and may have a value of 0 (zero) when the required amount of power and the actual amount of power are the same.

Meanwhile, the control error value may be transmitted to the transmission device 1000 in the form of a control error packet.

When new transmission power is received from the transmission device receiving the control error value, it may be determined whether the new transmission power satisfies the requested power through the above-described steps.

Meanwhile, when new transmission power is not received from the transmission device that has received the control error value, it may be determined that power transmission is stopped. In addition, when a detection signal (Ping Phase) is received from the transmission device, a power control message may be transmitted in response thereto. In addition, the transmitting device 1000 receiving the power control message may transmit wireless power in response to the power control message, and the receiving device 2000 may receive the wireless power. That is, after the Ping Phase, the identification and configuration phase may not be entered, but the power transfer phase may be immediately entered.

-How to determine the transmission power of the transmitting device.

Referring to FIG. 7, the transmission device 1000 includes 1) a control error packet reception step (S110), 2) a new transmission coil current determination step (S120), 3) a new transmission power determination step (S130), and 4) a power threshold. A value and comparison step (S140), 5) a new power generation step (S150), and 6) a power transmission stop step (S160) may be included.

The transmission device 1000 may receive a control error packet from the reception device 2000 in the control error packet receiving step (S110) and read a control error value included in the control error packet. In addition, in step S120 of determining a new transmission coil current, a new transmission coil current may be determined based on the control error value and the current of the current transmission coil unit 1400. In addition, a new transmission power corresponding to the new transmission coil current may be determined in step S130 of determining a new transmission power. The information on the new transmission power corresponding to the new transmission coil current may be stored as a lookup table in a memory provided in the control unit 103 or separately provided from the control unit 130, and the control unit 103 From, information on new transmission power corresponding to the new transmission coil current may be read. And in the power threshold and comparison step (S140), the reception allowed power amount, the current transmit power amount, and the new transmit power of the receiving device 2000 are compared with the power threshold value, and a new power generation step (S150) or power transmission is stopped. It is possible to enter any one of steps S160.

When the transmitter 1000 enters the new power generation step (S150), proportional, integral, differential control (Proportional Integral Differential Control; hereinafter, PID control), that is, a PID control step (S151) is performed, and the PID control is performed. A control variable may be determined based on the control variable (S152), and new power may be transmitted (S154) by controlling the power converter 101 based on the control variable (S153). In addition, after receiving the new power, the receiving device 1000 may transmit the next control error packet.

On the other hand, in response to the power increase request signal from the reception device 2000 within a time period from the time when the reception device 2000 transmits the current control error packet to the time when the next control error packet is transmitted, the current transmission power The amount can be increased to a new amount of electricity. In addition, the PID control of the feedback method may be repeatedly performed during the time period. That is, as the PID control is repeatedly performed, an error between the new power actually generated by the transmitting coil unit 1400 and the new target power may be reduced.

When the transmission device 1000 enters the power transmission stopping step (S160), the power transmission may be stopped (S161) and a detection (Ping) signal may be transmitted (S162). In addition, when a response signal to the detection signal is received from the receiving device 2000, a preset power may be transmitted (S163). The preset power may be the power transmitted at the time of receiving step S110, or may be less than the new transmit power determined in step S130. In addition, the next control error packet may be received from the receiving device 2000 that has received the preset power.

As described above, after determining the new transmission power, the transmission device 1000 may prevent the overpower from being transmitted to the reception device 2000 by determining whether to generate and transmit the new transmission power.

Whether to output the new transmission power determined as described above may be determined based on a process to be described later.

<How to determine whether to transmit power from the transmitting device>

8 is a flow chart of a transmission device determining whether to transmit power. 9 to 11 are diagrams showing a transient state and a normal state of a power signal over time.

(1) Since power efficiency is generally not 100%, only a part of the power output from the transmission device 1000 can be received by the reception device 2000. Accordingly, in order to transmit the power required by the reception device 2000, the transmission device 1000 needs to output a new transmission power higher than the required power.

However, depending on the power efficiency, the transmission device 1000 may generate new transmission power that greatly exceeds the required power of the reception device 2000. In this case, the power of the transmission device excluding the power received by the Depending on the amount, the receiving device 2000 may be damaged. Therefore, in order to prevent this, the transmission device 1000 needs to stop transmitting power without generating new transmission power if necessary. This will be described in detail.

(If the overshoot of the third power is not considered, Fig. 9)

(2) In the identification and setting state or the power transmission step, the transmission device 1000 may receive a message including information on the amount of power allowed for reception of the reception device 2000 from the reception device 2000. In the power transmission step, the transmission device 1000 may output first power, and the reception device 2000 may receive second power, which is some of the first power, according to power efficiency. And, when the amount of power required by the reception device 2000 is higher than the second power, the reception device 2000 includes a transmission power increase request signal (control error value is a positive value). The control error packet may be transmitted to the transmission device 1000.

Upon receiving the control error packet, the transmitter 1000 may determine a third amount of power higher than the first power based on the power increase request signal of the control error packet.

Thereafter, the transmission device 1000 may determine whether to generate and transmit the third power based on the third power amount and the reception allowable power amount.

As a method of determining whether to generate and transmit the third power, it may be determined whether a power difference value between the third power amount and the allowable reception power exceeds a power threshold.

-When the power difference value exceeds the power threshold (power transmission is interrupted)

When the power difference value exceeds a power threshold value, the transmission device 1000 may stop power transmission without finally generating the third power, which is a new transmission power.

In this way, when the power difference value exceeds the power threshold, the reason for stopping power transmission is that, even if the third power, which is the new transmission power, is output, the receiving device 2000 receives power as much as its own requested power amount or reception allowable power amount. However, this is because the amount of power other than this affects the receiving coil unit 2100 of the receiving apparatus 2000, thereby damaging the receiving apparatus 2000 and shutting down the system of the receiving apparatus 2000.

-Power difference value Below the power threshold (keep power transmission)

If the power difference value does not exceed the power threshold value, the transmission device 1000 may generate and transmit the third power. In addition, the receiving device 2000 may receive fourth power, which is a part of the third power, according to transmission efficiency. In this case, the fourth power may be the power requested by the receiving device 2000. However, when the received fourth power is different from the required power, the next control error packet may be requested to the transmission apparatus 1000 to adjust the amount of transmission power by including such error information.

Meanwhile, the power threshold is a power threshold that may damage the receiving coil or system of the receiving apparatus 2000 and may be experimentally determined in advance according to the characteristics of the receiving apparatus 2000.

On the other hand, the transmission device 1000 receives characteristic information of the reception device 2000 including information on the amount of power allowed to receive, etc., determines a power threshold value from the characteristic information of the reception device 2000, and allows the reception Whether to generate and transmit the third power may be determined based on the amount of power and the information on the third power.

(In the case of considering the overshoot of the third power, FIGS. 10 and 11)

(3) In addition, the transmission device 1000 receives a message including information on the allowable power of the reception device 2000 from the reception device 2000 in the identification and setting state or power transmission stage. can do. In the power transmission step, the transmission device 1000 may output first power, and the reception device 2000 may receive second power, which is some of the first power, according to power efficiency. In addition, when the amount of power requested by the reception device 2000 is higher than the second power, the reception device 2000 may transmit a control error packet including a transmission power increase request signal to the transmission device 1000.

Upon receiving the control error packet, the transmission device 1000 may determine a third power to satisfy the required amount of power based on the transmission power increase request signal.

Thereafter, the transmission device 1000 may determine whether to generate and transmit the third power based on the first amount of power, the third amount of power, and the amount of allowable reception power.

As a method of determining whether to generate and transmit the third power, an overshoot peak value in the transient state of the third power may be determined, and a power difference between the overshoot peak value and the allowable reception power amount It can be determined whether the value exceeds the power threshold.

When the power difference value exceeds the power threshold value, the transmission device 1000 may stop power transmission without finally generating the third power.

The overshoot is a magnitude of a signal that exceeds the magnitude of the third power in a transient state of the power signal before reaching a target magnitude of the third power. And the first overshoot can be referred to as a maximum overshoot.

The overshoot peak value may vary depending on the magnitude of the power signal of the third power, and may vary according to the amount of power increase from the first power to the third power. In addition, the new transmission power information to be generated, information on the currently output transmission power, and data experimentally determined from the current output transmission power and the increase amount of the new transmission power and the overshoot peak value are stored in advance, and the transmission device 1000 transmits the new transmission power. When generating power, the overshoot peak value can be determined by referring to this.

As described above, in the embodiment, when the output power of the transmission device 1000 is controlled based on the power control information fed back from the reception device 2000, the power output from the transmission device 1000 is instantaneously increased, and the reception device ( It is possible to prevent the system of the receiving apparatus 2000 from being down before receiving a feedback message indicating that excessive power is currently being received from (2000).

Meanwhile, the allowable received power amount of the receiving device 2000 is a value determined in consideration of the type of the receiving device 2000 or the allowable capacity of the receiving coil unit 2100 and the receiving power converting unit 202, which is It can be the information contained in the power transfer contract.

(4-1) When the third power is higher than the reception allowable power, Figs. 9 and 10.

When the third power to be generated by the transmission device 1000 is higher than the reception allowable power of the reception device 2000, 1) the difference between the reception allowable power and the third power of the reception device 2000 as shown in FIG. Determines at least one of whether or not the threshold value is exceeded or 2) whether the power difference value between the reception allowable power of the receiving device 2000 and the overshoot peak value of the power signal of the third power exceeds the power threshold, as shown in FIG. can do. When determining the overshoot peak value, the amount of power increase may be considered together as shown in the figure.

(4-2) When the third power is lower than the reception allowable power, Fig. 10.

As shown in FIG. 11, it may be determined whether a power difference value between the reception allowable power of the receiving apparatus 2000 and the overshoot peak value of the power signal of the third power is equal to or greater than the power threshold value, and in this case, the amount of power increase may be considered.

In this way, by calculating a power difference value, it is determined whether the power threshold is exceeded, and the power transmission may be stopped without generating the third power.

On the other hand, when the power transmission is stopped, the transmission device 1000 enters the detection state to perform detection of the reception device 2000, and when the reception device 2000 is detected, the identification and setting state does not enter, You can immediately enter the power transfer phase. In this case, power smaller than the third power, for example, the first power may be transmitted.

Hereinafter, a method of generating and transmitting new power will be described in detail.

<Power transmission control method>

12 is a diagram showing in detail a control unit of a transmission apparatus for a method of controlling power transmission. And Figure 13 is a timing diagram of the transmission device in the power transmission state.

Referring to FIG. 12, as a power transmission control method, the control unit 103 of the transmission device 1000 may control the current of the transmission coil unit 1400 to become a new transmission coil current. This power transfer control can be implemented based on a proportional integral differential (PID) algorithm.

In order to execute the PDI algorithm, the transmission device 1000 may include a first operator 11 and a second operator 15 and a proportional controller 12a, an integral controller 12b, and a derivative controller 12c. The first to fifth amplifiers 13a, 13b, 13c, 13d, 13e, and first and second summers 14a and 14b may be included, and the power conversion unit 101 is converted by performing the following process. Can be controlled.

The following j=1, 2, 3, ... may refer to the sequence number of the control error packet received by the transmission device 1000. In addition, each of the first to fifth amplifiers 13a, 13b, 13c, 13d, and 13e may have at least one function of an amplifier, a buffer, and a delay.

(1) New transmit coil current calculation step.

1) When the first operator 11 of the transmission device 1000 receives a j(th) control error packet, a new transmission coil current td(j) may be calculated according to Equation 3.

Equation 3

2) Here, ta(j-1) refers to the actual (current) transmission coil current determined according to the previous control error packet c(j-1), and c(j) is j(th) It may refer to a control error value included in a control error packet. In addition, ta(0) may mean the current of the transmission coil unit 1400 at the start of the power transmission state.

Output power may be generated by generating a magnetic field in the transmitting coil unit 1400 based on the transmitting coil current.

3) The first operator 11 receives the actual transmission coil current ta(j-1) through the j-th control error packet and the first amplifier 13a, and the operation process according to Equation 3 After passing through, the new transmission coil current td(j) can be calculated and output.

4) If the control error value c(j) is non-zero (non-zero), the transmitting device 1000 may adjust the transmission coil current for a preset time (t_active in FIG. 13). . To this end, the transmission device 1000 may execute a loop including steps to be described later.

Here, i=1, 2, 3, ..max may refer to the number of repetitions of the loop.

(2) Determining whether to stop power transmission.

The new transmission power may be determined based on the calculated new transmission coil current ta(j). The new transmission power is not generated according to the comparison result of the current transmission power amount according to the new transmission power and the current transmission coil current ta(j-1), the reception allowable power amount of the receiver 2000, and a power threshold value. Power transmission may be stopped, or the new transmission power may be generated and transmitted according to a step to be described later.

(3) Error calculation step.

1) The transmission device 1000 is i according to the difference between the new transmission coil current (td(j)) and the actual transmission coil current (ta(j,i-1)) according to the i-1th loop according to Equation 4 The error in the second loop can be calculated.

Equation 4

Here, ta(j, i-1) may refer to the transmission coil current determined by the i-1 th loop. Here, ta(j,0) may refer to the actual transmission coil current at the start of the loop.

2) The first summing unit 14a sums the new transmission coil current td(j) and the actual transmission coil current ta(j, i-1) determined by the i-1th loop from the second amplifier 13a. Thus, an error can be calculated and the calculated error can be output to the PID controller 12.

(4) Control amount calculation step.

1) The PID controller 12 of the transmission device 1000 determines the control amount through the proportional control (P) for changing the control amount in proportion to the error, the integral control (I) for integrating and controlling the error, and the change amount of the error. Differential control (D) can be executed.

The PID controller 12 may calculate a proportional term, an integral term, and a derivative term as expressed in Equation (5). Specifically, the proportional controller 12a calculates the proportional factor P(j,i) based on the error, and the integral controller 12b calculates the integral factor I(j,i) based on the accumulated value of the error, and The controller 12c can calculate the differential factor D(j,i) based on the amount of change in the error.

Equation 5

2) Here, Kp is the proportional gain, Ki is the integral gain, and Kd is the differential gain. And t_inner is the time required to repeat one loop. And the integral term I(j,0)=0, and the error e(j,0)=0. In addition, the transmission device 1000 may limit the integral term I(j,i) within the range of M_I..+M_I, and may change the calculated integral element I(j,i) to an appropriate boundary value as necessary. Here, M_I is an integral term limit parameter.

3) The output signal of the integral controller 12b can be fed back to its own input via the fourth amplifier 13d, and the fed back output signal is the integral term (I) of the previous (i-1th) loop. (j,i-1)). In addition, the input signal of the differential controller 12c may be input to the differential controller 12c via the third amplifier 13c, and at this time, the input signal is the error of the previous (i-1th) loop (e(j)). ,i-1))..

4) The second summer 14b of the transmission device 1000 is a proportional element P(j,i) output from the proportional controller 12a and an integral element I output from the integral controller 12b, as shown in Equation 6 By summing (j,i) and the differential element D(j,i) output from the differential controller 12c, the control amount PID(j,i) can be calculated this time (i).

Equation 6

5) According to this calculation, the transmission device 1000 can output the current (i) control amount PID(j,i), and the current (i) control amount PID (j,i) is within the range of -M_PID..+M_PID. Can be limited. Here, M_PID is a PID output limit parameter.

(5) New control variable value calculation step.

1) The transmission device 1000 may calculate a new controlled variable value based on Equation 7.

Equation 7

2) Here, Sv may refer to a scaling factor based on a control variable. Also, the control variable v(i,0)=v(j-1, i_max), and v(0,0) refers to the actual value of the controlled variable at the start of the power transmission state. can do. In addition, the control variable may be any one of an operating frequency, a duty cycle of the DC/AC converter 1200, or an input voltage of the DC/AC converter 1200. If the calculated v(j,i) exceeds a preset range, the transmission device 1000 may change the calculated v(j,i) to an appropriate limit value.

3) The second operator 15 is a control variable of the previous (i-1th) loop in which the input current (i) control amount PID (j, i) and its output are fed back via the fifth amplifier 13e. Based on the value, a new control variable value v(j,i) may be calculated according to Equation 7.

(6) controlling the power converter based on the new control variable.

1) The transmission device 1000 may apply a control variable v(j,i) of a new value to the DC/AC converter 1200. In addition, the control variable may be an output voltage of the AC/DC converter 1100, and in this case, the transmission device 1000 converts the control variable v(j,i) of the new value to the AC/DC conversion The input voltage input to the DC/AC converter 1200 may be adjusted by applying it to the output voltage of the unit 1100.

2) The transmission device 1000 may generate new power according to the transmission coil current ta(j,i) determined by the first operation unit 11 based on the control variable v(j,i) of the new value. have.

(7) Meanwhile, referring to FIG. 10, the transmission device 1000 may determine the transmission coil current ta(j) during the time t_delay+t_active+t_settle after the reception of the j(th) control error packet ends.

Here, t_delay may mean a time delay in performing power control according to the previous control error packet after receiving the previous control error packet, and t_active is performing power control according to the previous control error packet (transmitted as an example according to the drawing). Power increase) may mean a time taken, and t_settle may mean a settling time of a target power value.

On the other hand, the case where the gains (Ki, Ki, Kd) of the PID controller 12, the integral term limit parameter (M_I), the PID output limit parameter (M_PID), and v(j,i) exceed the preset range. When determining, the preset range and the scaling factor (Sv) take into account the transmission power characteristics of the power transfer contract, the specifications of the transmission device 1000, the specifications and the capacity of the transmission coil unit 1400, etc. Can be determined.

In addition, the power transfer contract may include information on a power threshold.

In this way, the transmission apparatus 1000 for receiving the control error packet may determine a new transmission coil current and determine a new transmission power based on the new transmission coil current. Further, according to the amount of new transmission power, wireless power transmission may be stopped without generating the new transmission power, or the new transmission power may be generated to continue wireless power transmission.

According to an embodiment, when the coupling coefficient is low due to misalignment between the transmission device 1000 and the reception device 2000, the reception power of the reception device 2000 is lower than the power output from the transmission device 1000. , Since the receiving device 2000 may request more power, the amount of transmission power of the transmitting device 1000 may be increased. At this time, before generating the increased transmission power, by comparing the transmission power with the power threshold to determine whether it is suitable for transmission, and determining whether to generate and transmit the power accordingly, heat generation due to excessive transmission power and excessive transmission power It is possible to solve a problem in which the receiving apparatus 2000 is damaged due to this.

In particular, as in the vehicle wireless charging system, when the transmission device 1000 and the reception device 2000 are instantaneous and repetitively misaligned due to a vehicle shaking or the like, the transmission power of the transmission device 1000 changes instantly. However, since the generation of transmission power itself can be determined in consideration of the stability of the reception device 2000, damage to the reception device 2000 can be prevented in advance.

In the detailed description of the present invention described above, it has been described with reference to preferred embodiments of the present invention, but those skilled in the art or those of ordinary skill in the relevant technical field of the present invention described in the claims to be described later It will be understood that various modifications and changes can be made to the present invention without departing from the spirit and technical scope. Therefore, the technical scope of the present invention should not be limited to the content described in the detailed description of the specification, but should be determined by the claims.

11 first operator
12 PID controller
12a proportional controller
12b integral controller
12c differential controller
13a first amplifier
13b second amplifier
13c third amplifier
13d fourth amplifier
13e fifth amplifier
14a first summing section
14b second summing section
15 second operator
101 Power conversion unit
102 Transmission side resonance circuit
103 control unit
1100 Transmission side AC/DC converter (1600
1110 rectifier
1120 Transmission side DC/DC converter
1200 Transmission side DC/AC converter
1300 Transmitter impedance matching unit
1400 transmitting coil part
1500 Transmission side communication and control unit
1510 Sending side control
1520 Transmission side communication unit
1600 detector
2000 receiver
2100 receiving side coil part
201, 2120 receiver side resonance circuit
2200 receiver impedance matching unit
202 Power conversion unit on the receiving side
2300 AC/DC converter on the receiving side
2400 DC/DC converter on the receiving side
2500 load
2510 battery
2520 battery management
2600 Receiver communication and control unit
203, 2610 receiver control
2620 receiving side communication unit

Claims (25)

A method of wirelessly transmitting power from a transmitter to a receiver, comprising:
Transmitting a signal for detection by the receiver;
Receiving an identification signal from the receiver;
Transmitting a first power to the receiver;
Receiving a power increase request signal from the receiver;
Determining a second transmission coil current based on the first transmission coil current of the transmitter and the power increase request signal;
Determining a second power based on the second transmission coil current; And
Comprising: determining whether to transmit the second power by comparing a power threshold value and a difference between the allowed reception power and the overshoot peak value of the second power. delete delete In paragraph 1,
When the difference exceeds the power threshold, the wireless power transmission is terminated. In paragraph 4,
When the wireless power transmission is terminated, the power transmission method further comprising the step of transmitting a signal for detecting the receiver. In paragraph 5,
When the receiver is detected, the power transmission method further comprising the step of transmitting a predetermined wireless power. In paragraph 1,
When the difference is less than or equal to the power threshold, controlling a power converter based on proportional integral and differential control (PID) control. In claim 7,
Controlling the power converter based on the PID control,
Determining a control value based on the PID control;
Determining a current control variable based on the control value and a previously controlled variable; And
Controlling the power converter based on the current control variable to transmit the second power. In claim 1,
The overshoot peak value is determined based on at least one of the second power and an increase from the first power to the second power. In clause 8,
At least one of an input voltage, a driving frequency, and a duty cycle of the power converter is adjusted based on the current control variable. delete delete delete delete A transmission coil for wirelessly transmitting power;
A power converter for outputting power to the transmission coil; And
A controller for controlling the power converter to control the amount of power output to the transmission coil,
The controller,
Determine new power based on the power increase request signal from the receiver,
A transmitter configured to determine whether to generate the new power based on a power threshold and a difference between the reception allowable power from the receiver and an overshoot peak value of the second power. delete delete In paragraph 15,
The overshoot peak value of the second power is set based on at least one of the new power and an increase from the current output power of the power converter to the new power. In paragraph 15,
The generation of the new power is terminated when the difference exceeds the power threshold. In paragraph 15,
The controller controls the amount of power by adjusting any one of a driving frequency, an input voltage, or a duty cycle of the power converter. In paragraph 15,
The controller,
A first calculator configured to determine a second current based on the power increase request signal from the receiver and the first current of the transmission coil;
A PID controller that determines a control value based on the PID control; And
And a second calculator for determining a current control variable based on the control value and the previously controlled variable,
The power converter,
Transmitter controlled based on the current control variable. delete delete delete delete

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