KR20220092725A - Receiver and method for wireless power transmission with input impedance compensation of rectifier applied - Google Patents

Abstract

According to the present invention, disclosed are a receiver for wireless power transmission to which input impedance compensation of a rectifier is applied and a method thereof. According to the present invention, the receiver for wireless power transmission comprises: a receiving antenna for receiving an RF signal; and an IC for receiving wireless power configured to measure an RF power level of the received RF signal, predict the RF power level of a next cycle by using the measured RF power level, and compensate for input impedance of a variable load by using the predicted RF power level of the next cycle.

Description

Receiver and method for wireless power transmission with input impedance compensation of rectifier applied

The present invention relates to electromagnetic wave radiation type wireless charging technology, and more particularly, to a receiver and method for wireless power transmission to which an input impedance compensation of a rectifier for improving and integrating efficiency of a rectifier is applied.

In general, electronic devices require a power source to charge an internal battery or supply power in real time to operate.

Although wireless communication is progressing in various industrial fields due to the development of wireless communication and semiconductor technology, the power supply wire still has the limitation that it is wired. Inconvenience of having to connect and supplying power to a plurality of electronic devices may cause aesthetic disadvantages and safety problems due to complicatedly connected wires. In order to solve this problem, an approach of supplying power without a wired connection between a power source and an electronic device using a wireless power transmission technology has recently been developed.

Wireless power transmission technology is a technology that supplies power wirelessly by transferring power between the power source and electronic devices without a contact point. If the purpose of a wireless communication technology, such as a radio, wireless telephone, or wireless Internet, is signal transmission, the wireless power transmission technology aims to transmit energy. Electrical energy has amplitude and frequency components, and as the frequency increases, the wavelength becomes shorter and thus has high straightness, so it has strong radiation characteristics in free space. Accordingly, wireless power transmission technology is classified into three major methods by classifying the transmission distance according to the operating frequency used.

First, in the electromagnetic induction method, when an alternating current voltage is applied to the transmitting coil and a time-varying current flows, magnetic lines of force are generated to form a magnetic field, and the magnetic lines of force linkage in the receiving coil close to the magnetic field to generate an induced electromotive force. As a method of transmitting power, it generally uses an operating frequency of several hundred kHz or less and transmits power at a distance of several centimeters or less.

Second, the magnetic resonance method uses an attenuated wave coupling phenomenon that moves from one medium to another through a near magnetic field when two media resonate at the same frequency, and mainly uses an operating frequency of several MHz. According to recent research or standardization trends, the electromagnetic induction method uses the resonance phenomenon to obtain higher efficiency, and the magnetic resonance method uses two resonant coils to reduce the form factor of the coil. The boundary between the method and the magnetic resonance method is blurring. Therefore, except for the radio wave radiation method, which shows a clear difference in the technology method or system configuration, the electromagnetic induction method and the magnetic resonance method, or a technology method with a similar system configuration, which is slightly modified, is called a magnetic coupling method. .

Third, the microwave radiation method uses a signal source and a power amplifier or a high-power microwave oscillator such as a magnetron or klystron to transmit energy having a high frequency of several GHz to a microwave antenna array or a beam antenna. It is a method of transmitting power by radiating into space through a rectenna and receiving it through a rectifying antenna.

1 is a view showing a typical structure of a conventional electromagnetic wave radiation type wireless charging system. As shown in [Fig. 1], the existing wireless charging system is composed of a transmitter and a receiver. The transmitter receives power from a DC power source, forms RF power of a desired frequency through an RF amplifier, and radiates electromagnetic waves into the air through an RF (or microwave) antenna. . The receiver includes an RF (or microwave) antenna for receiving electromagnetic waves and a rectifier for converting the received RF power into DC, and an impedance matching network for matching the impedances between them. do. The rectified DC power is supplied to the application through a DC/DC converter to convert it to a DC level required by the application (Load).

The rectifier of the receiver used for wireless power transmission of the existing electromagnetic wave radiation method is configured using a diode device or a diode connection of a MOSFET. In the case of a diode device, a Schottky diode having a low threshold voltage and ultra-fast characteristics is widely used in accordance with the high frequency characteristics of electromagnetic waves. However, in the case of a Schottky diode, high manufacturing cost and integration are impossible, and rectification efficiency is also not very high. On the other hand, a rectifier structure using MOSFETs can be integrated and has superior characteristics compared to Schottky diodes in terms of mass production. However, the variable characteristics of the input power are not reflected in either of the existing two methods.

In the case of electromagnetic wave radiation-based wireless power transmission, since power transfer is carried out in a far-field, the transmitter and receiver operate independently in circuit. The transmitter cannot predict the amount of power the receiver will receive, and the receiver cannot predict the amount of power it will receive. It is a self-evident fact that both diodes and MOSFETs have already proven that the current characteristics according to the forward voltage are non-linear. The ratio of input voltage and input current often follows the technical definition of impedance, and the nonlinear impedance change of the device results in variations in the rectifier input impedance. In fact, this is not a phenomenon that only occurs in high-frequency rectifier circuits, and most of them do not significantly affect the efficiency of the rectifier. However, in the electromagnetic wave transmitted wirelessly, the amount of received power is not constant, and accordingly, the DC power transmitted to the output load is also not constant. The load of the output terminal of the rectifier is not a passive element having a fixed impedance, and has a problem in that the amount of current consumed every time according to the operation of the application has an impedance characteristic that is variable.

Korea Patent Publication No. 10-2018-0074627 (2018.07.03.)

The technical problem to be achieved by the present invention is to compensate the input impedance of the rectifier to improve the efficiency of the rectifier having low RF-DC rectification efficiency with respect to the RF power of the dynamic range transmitted to the receiver for wireless power transmission of the electromagnetic wave radiation method An object of the present invention is to provide a receiver and method for wireless power transmission to which this is applied.

In order to achieve the above object, the receiver for wireless power transmission to which the input impedance compensation of the rectifier according to the present invention is applied measures the RF power level of the receiving antenna for receiving the RF signal and the received RF signal, and the measured RF power and a wireless power receiving IC that predicts the RF power level of the next cycle using the level, and compensates the input impedance of the variable load by using the predicted RF power level of the next cycle.

In addition, it characterized in that it further comprises a preprocessor for impedance matching and coupling of the received RF signal.

In addition, the wireless power reception IC detects an instantaneous value of the forward waveform of the received RF signal, differentiates the sensed instantaneous value, and sets a point at which the rate of change of the differentiated differential value is upward-facing the RF power level It is characterized by measuring with

In addition, the IC for wireless power reception estimates a peak point of the RF power level by integrating the measured RF power level, and using the estimated peak point, the current RF power amount and the RF power of the next period It is characterized by predicting the level.

In addition, the wireless power reception IC, using the predicted RF power level of the next cycle, it is characterized in that the weight for changing the input impedance of the variable load.

In addition, the IC for wireless power reception changes the input impedance of the variable load to a value for changing the input impedance of the rectifier corresponding to the current and future RF power level to be a fixed value to compensate for the change. do it with

A receiving method for wireless power transmission to which input impedance compensation of a rectifier is applied according to the present invention comprises the steps of: a wireless power transmission receiver receiving an RF signal; the wireless power transmission receiver measuring the RF power level of the received RF signal; Predicting, by the wireless power transfer receiver, the RF power level of the next cycle using the measured RF power level, and the wireless power transmission receiver using the predicted RF power level of the next cycle to calculate the input impedance of the variable load compensation step.

In addition, between the step of receiving and the step of measuring, the wireless power transfer reception is characterized in that it further comprises the step of impedance matching and coupling of the received RF signal.

The receiver and method for wireless power transmission to which the input impedance compensation of the rectifier of the present invention is applied through RF power sensing through a coupler disposed between the RF antenna and the rectifier, by applying a weight that predicts and reflects the RF power level input thereafter to the output load. A rectifier capable of maintaining a constant input impedance for variable input RF can be implemented.

Through this, the present invention can obtain high RF-DC rectification efficiency.

1 is a view for explaining a conventional wireless charging system.
2 is a block diagram illustrating a receiver for wireless power transmission according to an embodiment of the present invention.
FIG. 3 is a block diagram illustrating the preprocessor of FIG. 2 .
4 is a block diagram illustrating an IC for wireless power reception of FIG. 2 .
FIG. 5 is a block diagram illustrating the RF sensor unit of FIG. 4 .
6 is a block diagram illustrating the prediction unit of FIG. 4 .
7 is a flowchart for explaining a receiving method for wireless power transmission according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function is obvious to those skilled in the art or may obscure the gist of the present invention, the detailed description thereof will be omitted.

Throughout the specification, when a part is "connected" with another part, this includes not only the case of being "directly connected" but also the case of being "electrically connected" with another element interposed therebetween. . Also, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Hereinafter, "wireless power" is used to mean any form of energy associated with a magnetic field, electromagnetic field, or otherwise transmitted from a transmitter to a receiver without the use of physical electromagnetic conductors. In addition, “wireless charging system” or “system” refers to a system designed and operated to perform the technology based on the technology of “wireless power transmission” and includes components such as hardware and software. In addition, although the name “wireless charging system” was used, it refers to a system based on the technology of “wireless power transmission”, which not only transmits wireless power to charge the battery, but also supplies power in real time to operate electronic devices. This means that it may also include

Figure 2 is a block diagram for explaining a receiver for wireless power transmission according to an embodiment of the present invention, Figure 3 is a block diagram for explaining the preprocessor of Figure 2, Figure 4 is the wireless power receiving IC of Figure 2 It is a block diagram for explaining, FIG. 5 is a block diagram for explaining the RF sensor unit of FIG. 4 , and FIG. 6 is a block diagram for explaining the prediction unit of FIG. 4 .

2 to 6 , the receiver 100 for wireless power transmission improves the efficiency of a rectifier having low RF-DC rectification efficiency with respect to the transmitted RF power of a dynamic range. The receiver 100 for wireless power transmission includes a reception antenna 10 and an IC 50 for wireless power reception, and may further include a preprocessor 30 .

The reception antenna 10 receives the wireless power electromagnetic wave transmitted from the transmission antenna of the wireless power transmission transmitter (not shown). Here, the wireless power electromagnetic wave may be an RF signal or a microwave signal, and an embodiment of the RF signal will be described in the following description.

The preprocessor 30 performs a preprocessing process so that the RF signal input from the receiving antenna 10 performs a process to be performed later. The preprocessor 30 includes an impedance matching network 31 and an RF coupler 33 . The impedance matching network 31 matches the impedance of the input RF signal with the impedance of the IC for wireless power reception, and the RF coupler 33 performs RF coupling to combine the power of the RF signal. At this time, since the measurement of the RF power level can be performed at a very small power level, the RF coupler 33 sets the ratio of the RF power delivered to the IC 50 for wireless power reception in a ratio of 8:2 to 9:1. satisfied with

The wireless power receiving IC 50 measures the RF power level of the preprocessed RF signal, predicts the RF power level of the next cycle using the measured RF power level, and uses the predicted RF power level of the next cycle It compensates the input impedance of the variable load. The wireless power receiving IC 50 includes a rectifier 51 , an RF sensor unit 53 , a prediction unit 55 , and a variable load unit 57 .

The rectifier 51 converts the RF signal input from the preprocessor 30 into a DC signal. That is, the rectifier 51 performs a rectification operation to obtain DC power from AC power.

The RF sensor unit 53 measures the RF power level of the RF signal input from the preprocessor 30 . The RF sensor unit 53 includes a half-wave detector 61 , a differential 63 and a switch 65 . The half-wave detector 61 detects and outputs an instantaneous value of the forward waveform of the RF signal. The differentiator 63 differentiates the instantaneous value output from the half-wave detector 61 . The switch 65 is switched on at a point where the rate of change of the differential value differentiated from the differentiator 63 is upward, and the corresponding point is measured as an RF power level.

The prediction unit 55 predicts the RF power level of the next period by using the RF power level measured by the RF sensor unit 53 . The prediction unit 55 includes an integrator 71 and a multiplier 73 . The integrator 71 integrates the measured RF power level to estimate a peak point of the RF power level. That is, the integrator 71 may find the start point of the forward region of the RF power and infer the instantaneous peak value of the RF power through the integration of a half cycle from the point. The multiplier 73 predicts the current RF power amount and the RF power level of the next period using the estimated peak point. In this case, the multiplier 73 may assign a weight for changing the input impedance of the variable load using the predicted RF power level of the next cycle.

The variable load unit 57 compensates the input impedance of the variable load by using the predicted RF power level of the next cycle. That is, the variable load unit 57 maintains the input impedance of the rectifier 51 in a fixed impedance range through its input impedance change, and outputs according to the DC operation mode of the application (load) to be applied. decide how For example, the variable load unit 57 may compensate by changing the input impedance of the variable load to a value for changing the input impedance of the rectifier 51 corresponding to the current and future RF power levels to be a fixed value. can

7 is a flowchart for explaining a receiving method for wireless power transmission according to an embodiment of the present invention.

2 and 7, the receiving method for wireless power transmission applies a weight that predicts and reflects the RF power level input later through the RF power sensing through a coupler disposed between the RF antenna and the rectifier to the output load, variable input A rectifier capable of maintaining a constant input impedance to RF can be implemented. Through this, the reception method for wireless power transmission can obtain high RF-DC rectification efficiency.

In step S110, the receiver 100 for wireless power transmission receives the RF signal. The receiver 100 for wireless power transmission receives the wireless power electromagnetic wave transmitted from the transmission antenna of the wireless power transmission transmitter. Here, the wireless power electromagnetic wave may be an RF signal or a microwave signal.

In step S120, the receiver 100 for wireless power transmission measures the RF power level. The receiver 100 for wireless power transmission detects an instantaneous value for a forward waveform of the received RF signal, and differentiates the sensed instantaneous value. The receiver 100 for wireless power transmission measures the point at which the rate of change of the differentiated differential value is upward sloping as the RF power level.

In step S130, the receiver 100 for wireless power transmission predicts the RF power level of the next cycle. The receiver 100 for wireless power transmission estimates the peak point of the RF power level by integrating the measured RF power level, and predicts the current amount of RF power and the RF power level of the next period using the estimated peak point. At this time, the receiver 100 for wireless power transmission may assign a weight for changing the input impedance of the variable load using the predicted RF power level of the next cycle.

In step S140, the receiver 100 for wireless power transmission compensates the input impedance. The receiver 100 for wireless power transmission may compensate by changing the input impedance of the variable load to a value for changing the input impedance of the rectifier corresponding to the current and future RF power levels to be a fixed value.

Although the above has been described and illustrated in relation to the preferred embodiment for illustrating the technical idea of the present invention, the present invention is not limited to the configuration and operation as shown and described as such, and without departing from the scope of the technical idea. It will be apparent to those skilled in the art that many changes and modifications to the present invention are possible. Accordingly, all such suitable alterations and modifications and equivalents are to be considered as being within the scope of the present invention.

10: receiving antenna
30: preprocessor
31: impedance matching network
33: RF coupler
50: IC for wireless power reception
51: RF-DC rectifier
53: RF sensor unit
55: prediction unit
57: variable load unit
61: half wave detector
63: differentiator
65: switch
71: integrator
73: multiplier
100: Receiver for wireless power transmission

Claims (8)

a receiving antenna for receiving an RF signal; and
The RF power level of the received RF signal is measured, the RF power level of the next cycle is predicted using the measured RF power level, and the input impedance of the variable load is calculated using the predicted RF power level of the next cycle. Compensating wireless power receiving IC;
A receiver for wireless power transmission to which input impedance compensation of a rectifier comprising a. The method of claim 1,
a preprocessor for impedance matching and coupling of the received RF signal;
A receiver for wireless power transmission to which input impedance compensation of a rectifier is applied, characterized in that it further comprises a. The method of claim 1,
The wireless power receiving IC,
Detecting an instantaneous value of the forward waveform of the received RF signal, differentiating the sensed instantaneous value, and measuring a point at which the rate of change of the differentiated differential value is upward as the RF power level. Receiver for wireless power transmission with input impedance compensation applied. The method of claim 1,
The wireless power receiving IC,
Rectifier, characterized in that by integrating the measured RF power level to estimate a peak point (peak point) of the RF power level, and predicting the current amount of RF power and the RF power level of the next period using the estimated peak point Receiver for wireless power transmission with input impedance compensation of 5. The method of claim 4,
The wireless power receiving IC,
A receiver for wireless power transmission to which input impedance compensation of a rectifier is applied, characterized in that weight is given to change the input impedance of the variable load using the predicted RF power level of the next cycle. The method of claim 1,
The wireless power receiving IC,
Input impedance compensation of a rectifier, characterized in that the compensation is applied by changing the input impedance of the variable load to a value for changing the input impedance value of the rectifier corresponding to the current and future RF power level to be a fixed value Receiver for wireless power transmission. Receiving the RF signal by the wireless power transfer receiver;
measuring, by the wireless power transfer receiver, an RF power level of the received RF signal;
predicting, by the wireless power transfer receiver, an RF power level of a next period using the measured RF power level; and
compensating, by the wireless power transfer receiver, an input impedance of a variable load using the predicted next-period RF power level;
A receiving method for wireless power transmission to which input impedance compensation of a rectifier comprising a. 8. The method of claim 7,
between the receiving step and the measuring step,
performing impedance matching and coupling of the received RF signal by the wireless power transfer reception;
A receiving method for wireless power transmission to which input impedance compensation of a rectifier is applied, characterized in that it further comprises.

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