WO2018169223A1 - Wireless power system having self-voltage-controlled rectification apparatus, and communication method thereof - Google Patents

Abstract

Disclosed are a wireless power system having a self-voltage-controlled rectification apparatus, and a communication method thereof. A wireless power system according to one embodiment comprises: a reception resonator for self-resonating with a wireless power transmitter through a reception antenna; a self-voltage-controlled rectification apparatus for rectifying, through a rectifier, an alternating current-type power signal received from the reception resonator into a direct current-type power signal, and self-controlling an output voltage of the rectifier without a separate power converter; and a frequency adjustment unit for changing a resonance frequency of the reception resonator, for in-band communication with the wireless power transmitter, wherein a reception antenna current changes according to a change in the resonance frequency, and the reception resonator transmits a communication signal to the wireless power transmitter through induction of the changed reception antenna current.

Description

Wireless power system with self-voltage controlled stop and its communication method

The present invention relates to wireless power transmission and control technology, and more particularly, to a communication technology between a power transmitter and a power receiver for transmitting and receiving wireless power.

The wireless power system includes a power transmitter (PTU, hereinafter PTU) and a power receiver (PRU, hereinafter PRU) for transmitting and receiving power wirelessly. The PRU receives power using a resonator composed of an inductor L and a capacitor C. At this time, the power of the resonator flows an AC current having the same frequency as that of the power transmitted from the PTU. In general, since a final output signal is generated in the form of a stable DC signal and supplied to a load, a rectifier is required for this purpose. The rectifier converts the AC signal into an unregulated DC signal. This DC signal is converted into a sophisticated DC voltage signal using a power converter and supplied to the load. Whatever type of power converter is located, it has a two-stage structure, and the power transmission efficiency of the receiver is determined by multiplying the efficiency of the rectifier by the efficiency of the power converter. Therefore, the higher the efficiency, the more difficult the multi-stage configuration.

According to an embodiment, there is proposed a wireless power system and a communication method in a wireless power system having a self-voltage controlled stop that can increase power transmission efficiency by generating stable output power using only a rectifier and a resonator without a separate power converter.

According to an embodiment of the present disclosure, a wireless power system may rectify a reception resonator that self-resonates with a wireless power transmitter through a reception antenna, and an AC type power signal received from the reception resonator as a DC power signal through a rectifier. A self-voltage controlled stop for self-controlling the rectifier output voltage without a power converter, and a frequency adjusting unit for changing a resonance frequency of the reception resonator for in-band communication with the wireless power transmitter; The reception resonator includes a reception antenna current that changes according to a change in the resonance frequency and transmits a communication signal to the wireless power transmitter through induction of the changed reception antenna current.

The frequency adjuster may change the resonance frequency of the reception resonator in accordance with the rectifier output voltage and the output current controlled by the self-voltage controlled stop value. The frequency adjusting unit may change the resonance frequency of the reception resonator according to a communication command for exchanging information with the wireless power transmitter.

The communication signal may include information for adjusting the output power of the wireless power transmitter and other information for in-band communication with the wireless power transmitter.

The frequency adjusting unit may include a capacitor connected to the receiving antenna of the receiving resonator to change the resonant frequency of the receiving resonator, and a communication switching element connected to the capacitor in series and receiving a control signal for switching to control the current change of the receiving antenna. have. The communication switching device may have a first output connected with a capacitor, a second output connected with a ground, and an input to receive a control signal for in-band communication. The resonance frequency of the reception antenna and the capacitor of the reception resonator when the communication switching element is on may be different from the resonance frequency of the reception antenna and the resonance capacitor network of the reception resonator when the communication switching element is turned off. .

The wireless power system may further include a communication controller configured to generate a control signal for switching the communication switching device according to at least one of the output voltage of the rectifier, the output current, and the information to be exchanged with the wireless power transmitter, and transmit the control signal to the communication switching device. have.

The self-voltage controlled stop is a rectifier which converts AC power received from the receiving resonator into direct current power and supplies the rectifier output voltage to the load, and the output is connected to the rectifier input terminal and ground, respectively, and the output is generated according to the rectifier output voltage. It may include a low voltage switching device receiving a control signal.

The low voltage switching element receives a control signal that turns on the low voltage switching element when the rectifier output voltage increases, blocks the rectifier from supplying power to the load, thereby reducing the rectifier output voltage and lowering the rectifier output voltage. The rectifier output voltage may be increased by receiving a control signal for turning off the switching element so that the rectifier supplies power to the load.

The wireless power system senses a change in the current of the power supply supplied from the power supply to the power amplifier according to the current fluctuation and the transmitting antenna which magnetically couples with the receiving antenna to induce the current fluctuation of the receiving antenna. The electronic device may further include a current change detector configured to detect a digital communication signal from the controller, and a power controller configured to control the output power of the power amplifier according to the digital communication signal sensed by the current change detector.

In a wireless power system according to another exemplary embodiment, a wireless power receiver receives an AC power signal through a reception antenna of a reception resonator, and converts the AC power signal into a DC power signal through a rectifier. Rectifying, but self-controlling the rectifier output voltage without a separate power converter, and the wireless power receiver to change the receiving antenna current of the receiving resonator by changing the resonant frequency of the receiving resonator for in-band communication with the wireless power transmitter And transmitting, by the wireless power receiver, the communication signal to the wireless power transmitter through the induction of the changed antenna current.

The changing of the receiving antenna current of the receiving resonator may include: turning on the communication switching element to receive a control signal for in-band communication, and switching the receiving antenna through a capacitor connected to the turned on communication switching element. Varying the resonant frequency. The control signal for in-band communication may be generated according to at least one of an output voltage of the rectifier, an output current, and information to be exchanged with the wireless power transmitter.

In-band communication method in the wireless power system, the wireless power transmitter, the step of the current variation is induced from the receiving antenna through the transmission antenna magnetically coupled with the receiving antenna, and the wireless power transmitter, according to the current variation induced, Detecting a change in the power supply current supplied from the supply to the power amplifier, sensing a digital communication signal from the detected current change, and controlling, by the wireless power transmitter, the output power of the power amplifier according to the detected digital communication signal It may further include.

According to an embodiment, the PRU may generate a stable output voltage using a self-regulation rectifier (SRR). In this case, as the switching element and the receiving antenna of the SRR are separated, the switching element may be implemented at a low voltage. In addition, as the current flowing when the switching element is turned on is smaller than the antenna current, the efficiency degradation and the heat generation problem of the switching element that occur when the antenna current flows to the switching element absorbing the antenna current can be solved. have. Furthermore, the EMI current is kept constant so that EMI is not affected by the driving frequency of the switching device, thereby facilitating the design of the EMI filter. In addition, in a wireless power system having an SRR, the PRU may control the output power of the PTU by transmitting control information to the PTU through communication, particularly in-band communication.

1 is a structural diagram of a general PRU,

2 is a structural diagram of a PRU receiving power by controlling an active element;

3 is a graph showing the amount of change in the antenna current when the output voltage is controlled using a switching operation in the structure of FIG.

4 is a structural diagram of a receiver using a resonance frequency control method using a clocking signal;

5 is a structural diagram of a PRU having a Self Regulation Rectifier (SRR) to solve the problem in the PRU structure described above with reference to FIGS.

6 and 7 are structural diagrams of a PRU showing a situation in which the switching element M1 of FIG. 5 is turned off to increase the output voltage VOUT (power is supplied to a load);

8 and 9 are structural diagrams of a PRU showing a situation in which the switching element M1 of FIG. 5 is turned on to lower the output voltage VOUT (no power is supplied to the load).

10 is a structural diagram of a PRU further including a controller in the structure of FIG. 5;

FIG. 11 is a simulation waveform diagram showing that the output voltage VOUT is controlled when the load current varies from 0 to 200 mA in the structure of FIG. 10.

12 is a waveform diagram showing a drive waveform of the switching element M1 in the structure of FIG. 10;

13 is a structural diagram of a PRU including an SRR of a parallel structure according to an embodiment of the present invention;

14 is a structural diagram of a wireless power system for transmitting and receiving information using an in-band communication method applied to an existing inductive wireless power transmission system such as a Qi and PMA scheme.

15 is an operation waveform diagram of a wireless power system exchanging information with each other through the in-band communication of FIG. 14;

16 is a structural diagram of a wireless power system for in-band communication when using the SRR according to an embodiment of the present invention,

17 is an operation waveform diagram of a wireless power system having an SRR of FIG. 16 according to an embodiment of the present disclosure;

18 is a flowchart illustrating an in-band communication method of a wireless power system according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments of the present invention make the disclosure of the present invention complete and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present disclosure, when it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present disclosure, the detailed description thereof will be omitted, and the following terms are used in the embodiments of the present disclosure. Terms are defined in consideration of the function of the may vary depending on the user or operator's intention or custom. Therefore, the definition should be made based on the contents throughout the specification. Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a structural diagram of a general PRU.

Referring to FIG. 1, the PRU includes a resonator 10, a rectifier 12, a power converter 14, and a filter 16.

The PRU receives wireless energy from the PTU through a resonator 10 composed of an inductor L and capacitors Cs1 and Cs2. At this time, the resonator 10 flows an alternating current having the same frequency as that sent from the PTU. Rectifier 12 and power converter 14 produce a final output from the AC signal to a stable DC signal to supply power to the load. To this end, the rectifier 12 converts the AC signal into an unregulated DC signal. The power converter 14 converts this DC signal into a sophisticated DC voltage Vout and supplies it to the load. The power converter 14 is not limited to a specific type, and may be, for example, a buck type, a boost type, or a linear type.

Whatever type of power converter 14 is located, it has a two-stage structure, and the efficiency of the PRU is determined by multiplying the efficiency of the rectifier 12 by the efficiency of the power converter 14. For example, as shown in FIG. 1, when the efficiency of the rectifier 12 is at most 90% and the efficiency of the power converter 14 is at most 90%, the cumulative efficiency falls to a maximum of 81%. do. Therefore, as the power converter 14 is configured in a multi-stage, it is more difficult to satisfy high efficiency.

2 is a structural diagram of a PRU that receives power by controlling active elements.

Referring to FIG. 2, the PRU receives energy through a resonator including an inductor 200 and a capacitor 210. Inductor 200 is the equivalent inductance of the antenna. Subsequently, a rectifier composed of diodes 220 and 230 converts the AC signal into a DC signal and supplies energy to the load 260. At this time, the control circuit 240 controls the active element 250 to control the voltage supplied to the load 260. Unlike the method described above with reference to FIG. 1, this method does not require a separate power converter, and the rectifier output voltage can be controlled by a rectifier of one stage. However, if the active device 250 operates as a resistor, the efficiency may not be good. In addition, the voltage of the antenna is proportional to the reception sensitivity and the power of the PTU. In some cases, a voltage close to several hundred volts may occur. Therefore, the active device 250 connected to the antenna must have a high withstand voltage.

3 is a graph showing the amount of change in antenna current when the output voltage is controlled using a switching operation in the structure of FIG. 2.

Referring to FIG. 3, since the circuit of FIG. 2 uses a MOSFET device as a linear device, there are many heat generation problems caused by power consumption. Thus, the gate device is applied as a pulse to operate the MOSFET device as a switching device. Can be controlled. In this case, heat generation of the MOSFET device can be reduced, but a problem arises in that the antenna current is modulated as shown in FIG. 3.

For example, while the load consumes 5W and the output voltage is controlled, the MOSFET is controlled using a gate drive waveform to maintain the output voltage at a constant voltage. When the MOSFET is turned on, the antenna current decreases because the capacitor 210 of FIG. 2 changes the resonance frequency. That is, the antenna current increases when the current is supplied to the load, and the antenna current decreases when the MOSFET is turned on to lower the output voltage. It appears as if the antenna current is modulated to the gate drive waveform. The change in the current waveform means that the output power generated in the PTU is changed. Therefore, the operating conditions of the PTU circuit may change, which may affect stable operation. Since the noise frequency is modulated by the gate driving waveform, the EMI (Electro Magnetic Interference) is influenced by the gate driving waveform to suppress the EMI. It can be hard.

4 is a structural diagram of a receiver using a resonant frequency control method using a clocking signal.

Referring to FIG. 4, the output voltage Vout 400 is adjusted by controlling the N1 410 as a switching element by a separate clocking signal 450 so that the output voltage Vout 400 becomes a desired voltage. 4 is similar to that of FIG. 2, but the switching element N1 410 is positioned at the rear end of the resonator composed of the inductor L2 420 and the capacitor C1 422, and the control method is shown in FIG. It is the same as the method of 2.

When the switching device N1 410 is turned on, the current of the resonator flows through the switching device N1 410, and thus power consumption of the switching device N1 410 may be a problem as in the case of FIG. 2. In addition, the method serves to change the resonant frequency of the capacitors C1 422 and C6 430 when the switching element N1 410 is turned on, and the capacitance of the capacitor C6 430 is the capacitor C1 422. In comparison with this case, the resonance frequency does not change very much. Therefore, the current flowing through the switching element N1 410 may be very large.

If the capacitance of the capacitor C6 430 is reduced, the resonance frequency is increased to reduce the resonance current, but the voltage across the capacitor C6 430 may be increased. In this case, the diode D2 440 of the rectifier may be turned on to supply current to the load. The switching element N1 410 is intended to lower the output voltage by absorbing the antenna current and preventing the diode D2 440 from being turned on. However, this function is performed when the capacitor C6 430 is too small. Since the output voltage cannot be performed, the output voltage cannot be regulated.

As described above with reference to FIGS. 2 to 4, controlling the output with one stage of the rectifier may be advantageous in terms of efficiency, but there are some problems to be solved as follows in order to show performance that can be used in practice.

(1) Use of low voltage devices: In order to reduce the price and manufacture the low voltage semiconductor process, low voltage devices should be available.

(2) Antenna current modulation problem: Even when the output is controlled, the antenna current should be relatively constant to stabilize the operation of the PTU and reduce the problem that the control signal acts on the EMI.

(3) Power Consumption: The power consumption of the devices used to control the output voltage should be lowered to increase efficiency and suppress heat generation.

The present invention proposes a PRU structure for solving the three problems mentioned above.

FIG. 5 is a structural diagram of a PRU having a Self Regulation Rectifier (SRR) to solve the problems in the PRU structure described above with reference to FIGS. 2 to 4.

Referring to FIG. 5, the PRU 5 includes a resonator 50, a rectifier 52, and a switching element M1 54.

Resonator 50 includes inductor LRX 500, capacitor C1 501, C2 502 and Cp 504. The LRX 500 is a model of an antenna that receives power as an inductor, and capacitors C1 501 and C2 502 are capacitors that determine the resonant frequency of the PRU 5. Capacitor C2 502 may be connected in series with inductor LRX 500, and capacitor C1 501 may be connected in series with inductor LRX 500 and in parallel with capacitor C2 502. Capacitor C1 501 is a capacitor that directly returns current to inductor LRX 500, and capacitor C2 502 is a capacitor that returns current through rectifier 52 to supply current to the load. Capacitor Cp 504 is not directly related to wireless power transfer but prevents parasitic oscillation at the ACIN rectifier input terminal.

Rectifier 52 converts the AC input to DC, which may be a half-wave rectifier consisting of diodes D1 521 and D2 522 as shown in FIG. 5.

The switching element M1 54 controls the rectifier output voltage VOUT. Typically, when the control voltage Vcont is applied above the threshold voltage to turn on the switching element M1 54, the output voltage VOUT may be lowered. Therefore, the output can be controlled without a separate power converter can improve the efficiency.

The switching element M1 54 according to an embodiment may include a first output connected to the rectifier input terminal ACIN, a second output connected to ground, and an input connected to a control signal Vcont for self-controlling the rectifier output voltage VOUT. Have When the switching element M1 54 is turned on, the antenna current is dispersed so that the current flowing through the switching element M1 54 flows smaller than the antenna current.

The rectifier output voltage VOUT is kept constant by the switching element M1 54. For example, when the rectifier output voltage VOUT increases, the switching element M1 54 receives a control signal for turning on the switching element M1 54 to block the rectifier 5 from supplying power to the load. Reduce the output voltage VOUT. On the contrary, when the rectifier output voltage VOUT decreases, the control signal for turning off the switching element M1 54 is input to cause the rectifier 5 to supply power to the load, thereby increasing the rectifier output voltage VOUT. As a result, the rectifier output voltage VOUT is kept constant.

According to the proposed SRR structure, the switching element 54 for controlling the rectifier output voltage VOUT can be implemented at a low voltage as it is separated from the receiving antenna. In addition, as the current flowing when the low voltage switching element 54 is turned on is smaller than the antenna current, the efficiency decrease and switching occurring when the entire amount of the antenna current flows through the switching element 54 absorbing the antenna current. It solves the heat generation problem of the device. In addition, the antenna current is kept constant so that EMI is not influenced by the driving frequency of the switching element 54, thereby facilitating the design of the EMI filter. Hereinafter, referring to FIGS. 6 to 9, it is shown that the output voltage VOUT can be constantly adjusted through the magnetic voltage control in the PRU structure of FIG. 5.

6 and 7 are structural diagrams of a PRU in a situation in which the switching element M1 of FIG. 5 is turned off to increase the output voltage VOUT (power is supplied to a load).

When the output voltage VOUT is in the desired voltage state or lower than the desired voltage, turning off the switching element M1 54 causes the diode D1 521 to conduct and transfer power to the load (FIG. 6). . An equivalent circuit of FIG. 6 is shown in FIG. 7.

6 and 7, the current of the antenna is divided into I1 and I2 and flows through the capacitors C1 501 and C2 502, respectively. If the load resistance RL 580 is not large, that is, high power consumption is required, the resonance frequency is determined as in Equation 1.

If a receiver is built for an A4WP PTU using 6.78 MHz, the A4WP receiver determines the inductors LRX 500, capacitors C1 501 and C2 502 so that the resonant frequency is 6.78 MHz.

8 and 9 are structural diagrams of a PRU in a situation in which the switching element M1 of FIG. 5 is turned on to lower the output voltage VOUT (no power is supplied to the load).

If the output voltage VOUT is higher than the desired voltage, the switching element M1 54 is turned on to prevent power from being supplied to the output as shown in FIG. 8. Therefore, since the diode D1 521 is turned off, the load is not visible, and the equivalent circuit at this time is as shown in FIG. 9.

Since the resistance component can be made very small when the switching element M1 54 is turned on, assuming that the equivalent resistance of the switching element M1 54 is very small, the resonance frequency is the same as that of Equation (1). Therefore, in either case, the resonance frequency does not change significantly from the antenna LRX 500 position.

6 and 7 show the resistance RL 580 in series with the capacitor C2 502. However, since the diode D1 521 is turned on, the resistance RL ( 580) is not a state in which the resistance value is very large. When the load does not consume power, it can be said that the resistor RL 580 is very large. In this case, since the output voltage VOUT will increase, the switching element M1 54 will be turned on. Therefore, at this time, it operates as shown in FIGS. 8 and 9 so that in any case, the resistance component connected in series to the capacitor C2 502 is not large. That is, in both cases, the resonator state is almost similar, so that the antenna current remains almost constant. Therefore, it is a condition to operate stably whether the switching element M1 (54) is turned on (on) or off (off) from the standpoint of the PTU, and as shown in FIG. Since the driving frequency of the switching element M1 54 is not greatly affected, the EMI filter design is easy.

FIG. 10 is a structural diagram of a PRU further including a controller in the structure of FIG. 5.

Referring to FIG. 10, the controller 56 includes a comparator 560, resistors R1 561, R2 562, and a reference voltage VREF 563 for sensing the output voltage VOUT. If the condition VOUT × R1 / (R1 + R2)> VREF is satisfied, the output Vcont of the comparator 560 becomes high and the switching element M1 54 is turned on to lower the output voltage VOUT. Therefore, the output voltage VOUT is controlled to be (1 + R2 / R1) x VREF.

Since the above-described configuration of the comparator 560 describes only a brief operation, a circuit that causes the switching element M1 54 to be zero-voltage switching or hysteresis is added to the comparator 560 too. You can also put in circuits with additional features, such as not working frequently.

FIG. 11 is a simulation waveform diagram showing that the output voltage VOUT is controlled when the load current varies from 0 to 200 mA in the structure of FIG. 10.

10 and 11, the controller 56 is set to simulate the output voltage VOUT 910 to 5V while the resonator is set to operate at 6.78MHz. As shown in FIG. 11, it can be seen that the output voltage VOUT 910 is well controlled at 5V even when the load current 900 changes to 200mA. The initial output voltage VOUT 910 is low because the rectifier capacitor CVOUT is discharged to charge this capacitor. Looking at the antenna current 920, it can be seen that the load current is maintained almost constant.

12 is a waveform diagram showing a drive waveform of the switching element M1 in the structure of FIG.

10 and 12, when the switching element M1 is turned on by the high level switching control signal 1000, the output voltage VOUT 1010 decreases, and when the output voltage VOUT 1010 decreases, the output voltage VOUT 1010 decreases. The switching element M1 is turned off by the level switching control signal 1000, and the output voltage VOUT 1010 is increased again.

13 is a structural diagram of a PRU including an SRR of a parallel structure according to an embodiment of the present invention.

Referring to FIG. 13, the PRU includes a receiving antenna LRX 1300, a resonant capacitor network 1310, and an SRR unit 1320 having N SRRs, that is, SRR_1 to SRR_N connected in parallel. Since the SRR_1 to SRR_N can be controlled in accordance with the current required by the load, the output voltage VOUT can be more precisely controlled. Vc [1] to Vc [n] are control signals of SRR_1 to SRR_N. SRR_1 to SRR_N may include a rectifier including D1 and D2 as shown in the enlarged picture of FIG. 13 and a switch M1 at the rear end of the rectifier. For control of the output voltage VOUT using the SRR in parallel structure, as shown in FIG. 13, capacitors Cs1 to CsN are required, and the resonance frequency preferably satisfies Equation 2 below.

In Equation 2, f is the resonance frequency of the PRU, and it is preferable to match it with the resonance frequency of the PTU. Since the method of controlling Vc [1] to Vc [n] is not directly related to the present invention, detailed description thereof will be omitted.

14 is a structural diagram of a wireless power system for transmitting and receiving information using an in-band communication method applied to an existing inductive wireless power transmission system such as a Qi or PMA method.

PTUs and PRUs not only transmit and receive wireless power, but also exchange information through communication. For example, a PRU that requires less power may transmit a control signal via communication with the PTU requesting that the PRU draw less power from the PTU. Resonators used for wireless power signal exchange may also be used to exchange information. In order to perform wireless power transmission, various information exchanges are required between the PTU and the PRU. For example, it is necessary to exchange information about whether the PTU currently needs charging, how much if necessary, how to adjust parameters for charging, and whether the charging is completed.

Information can be exchanged by modulating the components in the PTU or PRU and sensing this change. The resonators may communicate with each other by changing the resonator parameters, such as the impedance of the resonators, which may affect other resonators in the system. Allows simultaneous transmission of power and communication signals between resonators in a wireless power system, or the transmission of power and communication signals for different periods or at different frequencies using the same magnetic field used during wireless power signal transmission. have. The communication of information between the resonators may be carried out using in-band or out-of-band communication, provided that the carrier frequency of the information exchange is close to the resonant frequency used in the power exchange. Such communication is referred to as in-band. Hereinafter, a wireless power system for exchanging information between a PTU and a PRU using in-band communication will be described with reference to FIG. 14.

The PRU rectifies the AC signal received at the receiving antenna 1520 through the rectifier 1523 and converts the DC signal into a DC form, and converts the converted DC voltage through the DC-DC converter 1524 to apply the load to the load. Output voltage Vout. If there is enough energy transferred from the PTU, the load can provide the desired voltage / current, but if the power supply of the PTU is small, it will not supply enough power to the load. Conversely, if the PTU power transmits more power than the load of the RPU's load requires, it becomes an inefficient system. Thus, in order to control the power of the PRU, the PRU attempts to communicate based on a protocol defined with the PTU. In this case, the communication signal may be exchanged wirelessly by using the transmit antenna 1510 of the PTU and the receive antenna 1520 of the PRU. This approach is called in-band communication. The Qi and PMA methods mainly use this method, and the two methods use a kind of amplitude modulation method.

For communication between the PTU and the PRU, a switch M2 1527 and a capacitor Cd 1528 are needed in the PRU. When the switch M2 1527 is turned on, the capacitor Cd 1528 is connected to a reception resonator including the reception antenna 1520 and the resonant capacitor network 1522, and thus the resonance frequency changes to change the received power. . Then, the current of the reception antenna 1520 fluctuates, the current fluctuation is induced in the transmission antenna 1510 of the PTU which is magnetically coupled with the reception antenna 1520, and the communication signal is transmitted to the transmission antenna 1510. Is passed. The PTU detects the current variation using an amplitude variation detector 1514 and detects a communication signal to be transmitted by the RPU from the detected change. The output power of the power amplifier 1518 is controlled through the power controller 1516 according to the detected communication signal.

FIG. 15 is an operation waveform diagram of a wireless power system exchanging information with each other through the in-band communication of FIG. 14.

Referring to FIGS. 14 and 15, when the gate input of the switch M2 1527 is turned high and the switch M2 1527 is turned on, the rectifier input ACIN is shown by FIG. 15 by the capacitor Cd 1528. Changes together. This change also appears in the receive antenna 1520 of the PRU, and similarly in the transmit antenna 1510 of the PTU. In this way, the PRU can digitally transmit and receive binary signals with the PTU, and the PRU can transmit desired control signals via serial digital communication. Digital information can be transmitted serially by serial digital communication.

16 is a structural diagram of a wireless power system for in-band communication when using the SRR according to an embodiment of the present invention.

Unfortunately, wireless power systems with SRR cannot use the scheme of FIG. Because the SRR controls the rectifier input ACIN to control the rectifier output voltage VOUT, when the SRR switch is turned on and the rectifier input ACIN is near the ground potential, the resonator will still be on. It will not react at all. Therefore, a method of inducing receive antenna current fluctuations by attaching a capacitor and a communication switch to the rectifier input ACIN to attempt switching cannot be used. To solve this problem, the present invention proposes a scheme as shown in FIG.

Referring to FIG. 16, the PRU 2 connects the communication switch M2 1629 and the capacitor Cd 1628 to the receiving antenna 1620 unlike the conventional method. In this case, the resonant frequencies of the receiving antenna 1620 and the capacitor Cd 1628 may be set to be different from the resonant frequency of Equation 1 (resonant frequencies of the receiving antenna 1620 and the resonant capacitor network 1622). For example, the resonant frequencies of the receiving antenna 1620 and the capacitor Cd 1628 may be set lower than the resonant frequency of Equation (1). In this case, when the communication switch M2 (1629) is turned on (on), the resonance frequency is significantly lowered so that the resonance with the PTU (1) is turned off, so that the peak of the receiving antenna current is lowered as shown in FIG. . As a result, since the power supplied from the PTU 1 becomes small, the current supplied from the power supply of the PTU 1 to the power amplifier 1618 becomes small.

In the PTU 1, a current variation detector 1614 detects a change in the power supply current Isup and detects a communication signal transmitted by the RPU 2 in binary form from the detected current change. . The output power of the power amplifier 1618 is controlled through the power controller 1616 by the detected communication signal. Using this scheme, like the existing Qi or PMA, the PRU 2 may control the power of the PTU 1 by transmitting a communication signal to the PTU 1 through serial digital communication.

Hereinafter, the components of the wireless power system according to an embodiment will be described in detail with reference to FIG. 16.

Referring to FIG. 16, a PRU 2 of a wireless power system having in-band communication with an SRR 1623 includes a reception resonator including a reception antenna 1620 and a resonator capacitor network 1622, an SRR 1623, A frequency adjusting unit 1627 and a communication control unit 1626 may be included, and the frequency adjusting unit 1627 may include a capacitor Cd 1628 and a switch M2 1629. Note that by the SRR 1623 configuration, there is no power converter of FIG.

The SRR 1623 rectifies the AC power signal received from the reception resonator into a DC power signal, but self-controls its output voltage without a separate power converter. SRR (1623) is a rectifier for converting the AC power received from the receiving resonator into direct current power to supply the rectifier output voltage Vout to the load, the output is connected to the rectifier input terminal and ground, respectively, the output is generated in accordance with the rectifier output voltage Vout It may include a low voltage switching element to which the control signal is applied. When the rectifier output voltage Vout increases, the low voltage switching element receives a control signal for turning on the low voltage switching element to block the rectifier from supplying power to the load, thereby reducing the rectifier output voltage Vout. On the contrary, when the rectifier output voltage Vout decreases, the control signal for turning off the low voltage switching element is input to allow the rectifier to supply power to the load, thereby increasing the rectifier output voltage Vout. The low voltage switching element may be a MOSFET transistor. However, the switching device may perform the same function even if it is replaced with an active device capable of switching operation, for example, a BJT, SiC FET, GaN FET, or the like.

The frequency adjuster 1627 changes the resonance frequency of the reception resonator for in-band communication. The frequency adjuster 1627 may change the resonant frequency of the reception resonator according to the rectifier output voltage and the output current controlled by the SRR 1623. As another example, the frequency adjusting unit 1627 may change the resonance frequency of the reception resonator according to a communication command for exchanging information with the PTU 1. The frequency adjusting unit 1627 may change the resonance frequency of the reception resonator according to a control signal transmitted from the communication control unit 1626 that manages in-band communication.

When the resonant frequency of the reception resonator is changed by the frequency adjusting unit 1627, the reception resonator changes the reception antenna current and transmits a communication signal to the PTU 1 through induction of the changed reception antenna current. The communication signal may include information for adjusting the output power of the PTU 1 for the purpose of optimal wireless power transmission, and other information for in-band communication with the PTU 1, for example, information related to communication performance. It may also include.

The frequency adjusting unit 1627 according to an embodiment is connected to a receiving antenna 1620 of the receiving resonator to change a resonance frequency of the receiving resonator, and is connected in series with the capacitor Cd 1628 and inputs a control signal. It includes a communication switch M2 (1629) to receive and switch to control the current change of the receiving antenna (1620). The communication switch M2 1629 has a first output connected to the capacitor Cd 1628, a second output connected to the ground, and an input receiving a control signal generated according to the rectifier output voltage Vout. The resonant frequency of the receive antenna 1620 and the capacitor Cd 1628 of the receive resonator is preferably lower than the resonant frequency of the receive antenna 1620 and the resonant capacitor network 1622 of the receive resonator. The communication switch M2 1629 may be a MOSFET transistor. However, the communication switch M2 1629 may perform the same function even if it is replaced by an active device capable of switching operation, for example, a BJT, SiC FET, GaN FET, or the like.

The communication controller 1626 generates a control signal for switching the communication switch M2 1629 according to at least one of the rectifier output voltage and the output current and other information, and transmits the control signal to the communication switch M2 1629. The communication control unit 1626 may transmit a control signal for turning on the communication switch M2 1629 to the communication switch M2 1629 to change the reception current through a resonance frequency change by the capacitor Cd 1628. The information may be information for adjusting the output power of the wireless power transmitter or other information for in-band communication with the wireless power transmitter. The information may be in accordance with a communication command for information transfer.

The PTU 1 includes a transmit antenna 1610, a current change detector 1614, a power controller 1616, and a power amplifier 1618. The transmit antenna 1610 is magnetically coupled with the receive antenna 1620 to induce current variations in the receive antenna 1620. The current change detector 1614 detects a change in the power supply current Isup supplied from the power supply to the power amplifier 1618 in response to the current variation, and detects the digital communication signal from the detected current change. The current change detector 1614 controls the output power of the power amplifier 1618 in accordance with the digital communication signal sensed by the current change detector 1614.

17 is an operational waveform diagram of the wireless power system with the SRR of FIG. 16 according to an embodiment of the present invention.

16 and 17, when the communication switch M2 1629 is turned on, the peak of the current of the reception antenna 1620 is sharply lowered and the power supply current Isup of the PTU 1 is lowered. .

18 is a flowchart illustrating an in-band communication method of a wireless power system according to an embodiment of the present invention.

Referring to FIG. 18, the PRU 2 receives an AC-type power signal through a receiving antenna of a reception resonator 1800 and rectifies the AC-type power signal into a DC-type power signal through a rectifier. Self-controlling the rectifier output voltage without a separate power converter (1810). Subsequently, the reception antenna current of the reception resonator is changed by changing the resonance frequency of the reception resonator for in-band communication (1820). According to an embodiment of the present disclosure, the PRU 2 receives a control signal for in-band communication by the communication switching device, and adjusts the resonance frequency of the reception antenna through a capacitor connected to the communication switching device that is turned on. Can change. The control signal for in-band communication may be generated according to at least one of an output voltage of the rectifier, an output current, and information to be exchanged with the PTU 1.

A communication signal for adjusting the output power of the PTU 1 is transmitted to the PTU 1 through induction of the changed antenna current (1830). Then, the PTU 1 detects a change in the power supply current Isup supplied from the power supply to the power amplifier according to the change in current, and the current fluctuation is induced from the receiving antenna through the transmit antenna magnetically coupled with the receiving antenna. A digital communication signal is detected from the sensed current change (1840). Subsequently, the output power of the power amplifier is controlled according to the sensed digital communication signal (1850).

So far, the present invention has been described with reference to the embodiments. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

Claims (15)

A reception resonator which self-resonates with the wireless power transmitter through the reception antenna; A self-voltage controlled stop value for rectifying the AC-type power signal received from the reception resonator into a DC-type power signal through a rectifier, and self-controlling the rectifier output voltage without a separate power converter; And A frequency adjuster for changing a resonance frequency of the reception resonator for in-band communication with a wireless power transmitter; Including; The receiving resonator is a wireless power system, characterized in that the receiving antenna current changes in accordance with the change in the resonant frequency and transmits a communication signal to the wireless power transmitter through the induction of the changed receiving antenna current. The method of claim 1, wherein the frequency adjusting unit And a resonance frequency of the reception resonator in accordance with the rectifier output voltage and the output current controlled by the self-voltage controlled stop. The method of claim 1, wherein the frequency adjusting unit And a resonance frequency of the reception resonator in accordance with a communication command for exchanging information with the wireless power transmitter. The method of claim 1, wherein the communication signal A wireless power system comprising information for adjusting the output power of the wireless power transmitter and other information for in-band communication with the wireless power transmitter. The method of claim 1, wherein the frequency adjusting unit A capacitor connected to a receiving antenna of the receiving resonator to change a resonance frequency of the receiving resonator; And A communication switching device connected in series with the capacitor and configured to receive and switch a control signal to control a current change of the receiving antenna; Wireless power system comprising a. The method of claim 5, wherein the communication switching device And a first output connected to the capacitor, a second output connected to ground, and an input receiving a control signal for in-band communication. The method of claim 5, wherein The resonance frequency of the reception antenna and the capacitor of the reception resonator when the communication switching element is on is different from the resonance frequency of the reception antenna and the resonance capacitor network of the reception resonator when the communication switching element is turned off. Wireless power system characterized by. The system of claim 5, wherein the wireless power system A communication control unit for generating a control signal for switching the communication switching element according to at least one of information to be exchanged with the wireless power transmitter and an output voltage of the rectifier and transmitting the generated control signal to the communication switching element; Wireless power system comprising a further. The magnetic voltage controlled stop of claim 1, wherein A rectifier for converting AC power received from the reception resonator into DC power and supplying a rectifier output voltage to the load; And A low voltage switching element having an output connected to a rectifier input terminal and a ground, respectively, and receiving a control signal generated according to the rectifier output voltage; Wireless power system comprising a. The method of claim 9, wherein the low voltage switching device When the rectifier output voltage increases, the control signal for turning on the low voltage switching element is input to block the rectifier from supplying power to the load, thereby reducing the rectifier output voltage. When the rectifier output voltage decreases, the low voltage switching element Receiving a control signal to turn off (off) to allow the rectifier to supply power to the wireless power system characterized in that to increase the rectifier output voltage. The method of claim 1, wherein the wireless power system A transmission antenna magnetically coupled with the reception antenna to induce a current variation of the reception antenna; A current change detector for detecting a change in the power supply current supplied from the power supply to the power amplifier according to the current variation and detecting a digital communication signal from the detected current change; And A power controller controlling the output power of the power amplifier according to the digital communication signal sensed by the current change detector; Wireless power system comprising a further. The wireless power receiver receives the AC power signal through the receiving antenna of the reception resonator, rectifies the AC power signal into the DC power signal through the rectifier, but controls the rectifier output voltage without a separate power converter. Doing; Changing, by the wireless power receiver, a reception antenna current of the reception resonator by changing a resonance frequency of the reception resonator for in-band communication with the wireless power transmitter; And Transmitting, by the wireless power receiver, the communication signal to the wireless power transmitter through the induction of the changed antenna current; Communication method in a wireless power system comprising a. 13. The method of claim 12, wherein varying the receive antenna current of the receive resonator The communication switching device being turned on to receive a control signal for in-band communication; And Changing a resonant frequency of the receiving antenna through a capacitor connected to the on-line communication switching element; Communication method in a wireless power system comprising a. The method of claim 13, The control signal for the in-band communication is generated in accordance with at least one of the output voltage of the rectifier, the output current and information to be exchanged with the wireless power transmitter in a wireless power system. The method of claim 12, wherein the in-band communication method in the wireless power system, In the wireless power transmitter, the current variation is induced from the receiving antenna through the transmitting antenna magnetically coupled to the receiving antenna; Detecting, by the wireless power transmitter, a change in power supply current supplied from the power supply to the power amplifier in accordance with the current fluctuation, and detecting a digital communication signal from the detected current change; And Controlling, by the wireless power transmitter, the output power of the power amplifier according to the sensed digital communication signal; Communication method in a wireless power system characterized in that it further comprises.

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