WO2016140482A1

WO2016140482A1 - Dual band wireless power reception unit

Info

Publication number: WO2016140482A1
Application number: PCT/KR2016/002001
Authority: WO
Inventors: 황종태; 박성민; 진기웅; 전상오; 송익규; 신현익; 이준
Original assignee: 주식회사 맵스
Priority date: 2015-03-05
Filing date: 2016-02-29
Publication date: 2016-09-09

Abstract

A dual band wireless power reception unit is disclosed. The wireless power reception unit according to one embodiment comprises: a first resonator; a second resonator connected to the first resonator in parallel; a single rectifier having, as an input, a node in which outputs of the first resonator and the second resonator are connected to each other in parallel; at least one switch having a first output, a second output, and an input, wherein the second output is connected to the ground; at least one capacitor connected to the second resonator in parallel, and of which one terminal is connected to the first output of the switch and the other terminal is connected to the rectifier input; and a frequency sensor sensing an input frequency from the rectifier input, and of which an output is connected to the input of the switch.

Description

Dual band wireless power receiver

The present invention relates to a technique for wirelessly transmitting and receiving power.

Recently, the wireless charging system has been implemented in two ways. One of them is a tightly coupled method where the antenna of a wireless power transmitter (PTU) and the antenna of a wireless power receiver (PRU) must be well matched in position and close to each other. . This method has a low operating frequency and the antenna of the power transmitter and the antenna of the power receiver are matched relatively accurately at a short distance, so the efficiency is excellent and the control method is similar to the conventional resonant inverter method. Has Standards adopting these technologies include the Qi method of the Wireless Power Consortium (WPC), and the Power Matters Alliance (PMA).

Qi and PMA methods are highly efficient and can be manufactured at a relatively low cost. However, it is difficult for one power transmitter to supply energy to two or more power receivers at the same time, and if the power transmitter and the power receiver antenna are not matched in position, there is a problem that the charging efficiency is sharply reduced. In addition, the charging efficiency is reduced even if the distance between the power transmitter and the power receiver is a little far away, which is inconvenient for general users to use.

In order to solve this problem, a standard has been proposed that uses magnetic resonance technology and increases the energy transmission frequency so that it can be freely charged at a distance and position compared to the above standard. The Alliance for Wireless Power (A4WP, hereinafter referred to as A4WP) is a representative standard. While the Qi and PMA methods transmit energy at frequencies of about 80 kHz to 200 kHz, the A4WP uses a high frequency of 6.78 MHz so that the antenna size can be small, and the distance between the antennas is increased by matching the resonance frequency of the resonator of the power receiver and the power transmitter. Wireless charging is possible even if you fall. Using the A4WP approach, it is not difficult to supply several Watts to several watts to the load, and it is also possible to transmit energy to multiple power receivers simultaneously. This method is also known as loosely coupled. However, this method is difficult to manufacture due to the high driving frequency and drives the active device at a high frequency, so the efficiency is lower than that of the tightly coupled method.

The Qi, PMA, and A4WP methods introduced so far have advantages and disadvantages, and three methods are used in combination. These standards have a disadvantage in that wireless charging standards are not compatible with each other because of different frequencies. Therefore, there is a need for a power receiver with wireless power reception on a power transmitter that conforms to any standard.

According to one embodiment, a dual band wireless power receiver capable of receiving energy from different resonators with one rectifier is proposed.

According to an embodiment of the present disclosure, a wireless power receiver includes a first rectifier, a second resonator connected in parallel with the first resonator, a single rectifier having a node in which outputs of the first resonator and the second resonator are connected in parallel with each other; A second output having a first output, a second output and an input, the second output being connected in parallel with the second resonator, one terminal connected to the first output of the switch and the other terminal connected to the rectifier input And at least one capacitor, and a frequency detector for sensing an input frequency from the rectifier input and having an output coupled to the input of the switch.

The first resonator may be a high frequency resonator and the second resonator may be a low frequency resonator. The first resonator may be a series resonator in which at least one inductor and at least one capacitor are connected in series. The second resonator may be a series resonator in which at least one inductor and at least one capacitor are connected in series.

If the frequency sensed by the frequency detector is low frequency, the switch is switched on so that the capacitor is connected to the rectifier input. If the frequency sensed by the frequency detector is high frequency, the switch can be switched off to disconnect the capacitor from the rectifier input.

According to the present invention, there is proposed a dual band wireless power receiver that wirelessly receives power by connecting two resonators having different resonant frequencies using one rectifier. When energy is transferred to one resonator, energy is transferred to another resonator, and energy is not smoothly transferred to the rectifier. Therefore, the conventional technology uses two rectifiers. However, the present invention uses an additional switch to solve this problem. The solution is to receive energy from different resonators with one rectifier. It is possible to build a wireless power receiver that supports both high frequency charging such as A4WP and low frequency charging such as Qi and PMA.

1 is a circuit diagram of a wireless power receiver having two resonators and two rectifiers to simultaneously accommodate the Qi and A4WP schemes;

2 is a series resonant circuit diagram

3 is a circuit diagram showing a series resonant circuit and a parallel capacitor;

4 is a circuit diagram of a wireless power receiver for receiving energy at a Qi frequency;

5 is a circuit diagram of a wireless power receiver for receiving energy at an A4WP frequency;

6 is a circuit diagram of a dual band wireless power receiver having a single rectifier according to an embodiment of the present invention;

7 and 8 are experimental results of the case of receiving power at the A4WP frequency (no parallel capacitor in the Qi resonator) and a circuit diagram of the wireless power receiver thereof;

9 and 10 are experimental results of receiving power at the Qi frequency (no parallel capacitor in the Qi resonator) and a circuit diagram of the wireless power receiver thereof;

11 and 12 show an experimental result when a parallel capacitor is attached to a Qi resonator and a circuit diagram of the wireless power receiver;

FIG. 13 and FIG. 14 show an experimental result when the parallel capacitor of the Qi resonator is connected to the ground direction when the Qi resonator is operated and a circuit diagram of the wireless power receiver according to the method proposed by the present invention.

15 is a circuit diagram of a dual band wireless power receiver using a half-wave rectifier according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; In the following description of the present invention, if it is determined that detailed descriptions of related well-known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to intention or custom of a user or an operator. Therefore, the definition should be made based on the contents throughout the specification.

1 is a circuit diagram of a wireless power receiver having two resonators and two rectifiers to simultaneously accommodate the Qi and A4WP schemes.

Referring to FIG. 1, a general dual band wireless power receiver includes a resonator and a rectifier suitable for a high frequency, and a resonator and a rectifier suitable for a low frequency, respectively. The high frequency method may use the A4WP method. Hereinafter, the high frequency resonator and the rectifier will be described based on the A4WP resonator 10-1 and the A4WP rectifier 20-1. The low frequency method may use a Qi or PMA method. The Qi and PMA methods have similar frequency bands and similar methods. Hereinafter, the low frequency resonator and the rectifier will be described based on the Qi resonator 10-2 and the Qi rectifier 20-2. However, this is for convenience of description, and if the Qi and A4WP schemes can be used at the same time, the PMA and A4WP schemes can be easily used simultaneously.

The A4WP resonator 10-1 includes an inductor L 1 100-1, a capacitor Cs 1 102-1, and Cp 1 104-1. The Qi resonator 10-2 includes an inductor L2 100-2, a capacitor Cs2 102-2, and Cp2 104-2. In Fig. 1, the values of L1 (100-1), Cs1 (102-1), Cp1 (104-1), L2 (100-2), Cs2 (102-2), and Cp2 (104-2) are stable circuits. Values assumed for implementation are not limited to this.

Each resonator 10-1, 10-2 is an input voltage of the A4WP rectifier 20-1 and the Qi rectifier 20-2, VACP 200-1, VACN 202-1, and VACP 2-200-2. And VACN2 202-2, respectively, and a capacitor CRECT 222 is connected to the rectifier output voltage VRECT 220 to convert the received AC power into DC. The buck converter 30 converts the rectifier output voltage VRECT 220 into a sophisticated voltage required for the load, thereby supplying a stable voltage to the load. In FIG. 1, it is assumed that the buck converter 30 outputs 5V.

The wireless power receiver described above with reference to FIG. 1 processes the A4WP and Qi frequency inputs using separate rectifiers 20-1 and 20-2, and thus can be used in both methods. However, the wireless power receiver of FIG. 1 requires both rectifiers 20-1 and 20-2, which adds cost and hinders the implementation of small wireless power receivers suitable for portable devices. Prior to solving this problem, the resonator will be analyzed with reference to FIGS. 2 and 3.

2 is a circuit diagram illustrating a series resonant circuit.

When the Cp1 104-1 and the Cp2 104-2 are removed from the two resonators 10-1 and 10-2 of FIG. 1, the resonators are formed as shown in FIG. 2. Since the inductor L 100 and the capacitor Cs 102 are connected in series, they become a series resonator. At this time, the resonance frequency of the inductor L 100 and the capacitor Cs 102 should be set to be approximately the same as or similar to the power transmission frequency of the power transmitter to enable high efficiency reception. Therefore, in FIG. 1, the resonant frequencies of the inductor L1 100-1 and the capacitor Cs1 102-1 are higher than the resonant frequencies of the inductor L2 100-2 and the capacitor Cs2 102-2.

In the series resonator of FIG. 2, the impedance Ztank is theoretically zero at the resonance frequency, so that the received current is maximized. In contrast, when the frequency of the power supplied from the power transmitter is lower or higher than the resonant frequency, the impedance Ztank increases, so that the output current of the resonator decreases rapidly. In other words, it can be seen that the impedance Ztank is in a very high state when the resonance frequency is not.

3 is a circuit diagram showing a series resonant circuit and a parallel capacitor.

Referring to FIG. 3, the capacitor Cp 104 is a capacitor connected in parallel with the resonator, and is a kind of energy circulation path made to circulate energy when energy of the resonator is not transferred to the rectifier. Without the capacitor Cp 104, when the rectifier of FIG. 1 does not operate, parasitic capacitors generated in the VACP 200-1 and the VACN 202-1 and the series resonant circuit react to generate high frequency noise. . This affects the stability of the operation of the power receiver and increases the EMI, thus adding a capacitor Cp 104 to suppress this phenomenon. It is common to set capacitor Cp 104 to a value that is moderately smaller than capacitor Cs 102. If the value is much smaller than the capacitor Cs 102, the noise canceling effect disappears. If the value is too large, the large current is returned to the resonator through the capacitor Cp 104, so that the current supplied to the rectifier becomes small, and thus smooth to the load. The power supply will not work. Accordingly, as illustrated in FIG. 1, capacitors Cs1 102-1 and Cp1 104-1 are in the pF region, and capacitors Cs2 102-2 and Cp2 104-2 are similar in size to nF. It is preferable to set.

Capacitor Cp1 104-1 of A4WP resonator 10-1 of FIG. 1 is a very small value and may be at a level similar to the parasitic capacitor seen at the input of A4WP rectifier 20-1. Without this, there can be no problem with operation. That is, in the high frequency resonator, the capacitor Cp1 104-1 may be removed.

4 is a circuit diagram of a wireless power receiver for receiving energy at the Qi frequency.

Referring to FIG. 4, when the wireless power receiver operates at the Qi frequency, the impedances of the L2 100-2 and the Cs2 102-2 of the Qi resonator 10-2 become very small, and conversely, the L1 (100-1). ), The resonant frequency of the A4WP resonator 10-1 composed of Cs1 102-1 is very different from the resonant frequency of the Qi resonator 10-2. Therefore, the impedances of the L1 100-1 and the Cs1 102-1 of the A4WP resonator 10-1 become very large, and the A4WP resonator 10-1 is negligible from the Qi resonator 10-2 standpoint. .

On the contrary, when energy is transmitted at the A4WP frequency, the impedances of L1 (100-1) and Cs1 (102-1) of the A4WP resonator 10-1 become very small, and L2 of the Qi resonator 10-2. Since the resonant frequencies of (100-2) and Cs2 (102-2) are very low, the impedance of the Qi resonator 10-2 is greatly increased, and it can be considered that there is no Qi series resonant circuit. Therefore, as shown in FIG. 4, even if two resonators 10-1 and 10-2 are connected in parallel and only one rectifier 20 is used, there is no problem in operation, and each resonator 10-1 and 10 is not limited. -2) may operate exclusively according to the received frequency.

However, a problem may occur when Cp1 104-1 and Cp2 104-2 are connected to remove noise. 4 is an example of a case where the power receiver receives energy at the Qi frequency. As described above, the impedance by L1 (100-1) and Cs1 (102-1) of the A4WP resonator (10-1) is very large and the value of Cp1 (104-1) is very small. The impedance is also so large that the current of the Qi resonator 10-2 is mostly supplied to the rectifier 20 to be used to supply power to the load. Therefore, there is no problem in this case.

5 is a circuit diagram of a wireless power receiver for receiving energy at the A4WP frequency.

Unlike FIG. 4, the problem occurs in FIG. 5. When energy is received at a frequency of A4WP, the A4WP resonator 10-1 reacts to generate a current. If this current is transmitted to the rectifier 20, there is no problem, but since the impedance of Cp2 104-2 of the Qi resonator 10-2 is low, many currents circulate through the Cp2 104-2, so that the rectifier 20 The amount of current delivered to the device becomes smaller, which causes problems in powering the load. Of course, also in this case, it is true that the resonator impedances of L2 (100-2) and Cs2 (102-2) of the Qi resonator (10-2) become very large.

6 is a circuit diagram of a dual band wireless power receiver having a single rectifier according to an embodiment of the present invention.

In order to solve the problem described above with reference to FIG. 5, a circuit as shown in FIG. 6 is proposed. Referring to FIG. 6, a dual band wireless power receiver includes an A4WP resonator 10-1, a Qi resonator 10-2, one rectifier 20, a buck converter 30, and a frequency detector 40. , Two capacitors Cp2 104-2 separated from the Qi resonator 10-2, and two switches M1, M2 (50-1, 50-2).

The A4WP resonator 10-1 and the Qi resonator 10-2 are connected in parallel. The rectifier 20 is a single unit, and receives as a input a node in which the outputs of the A4WP resonator 10-1 and the Qi resonator 10-2 are connected in parallel to each other. The switches M1 and M2 50-1 and 50-2 have a first output and a second output and an input, respectively. The first output is connected to capacitor Cp2 104-2 and the second output is connected to ground. Capacitor Cp2 104-2 is connected in parallel with Qi resonator 10-2, respectively, with one terminal connected in series with the first output of switches M1 and M2 50-1 and 50-2. It is connected to the rectifier inputs (VACP, VACN) 200-1, 202-1. The frequency detector 40 senses the input frequency from the rectifier inputs VACP, VACN, and the output is connected to the inputs of the switches M1, M2 50-1, 50-2. In the A4WP resonator 10-1, the inductor L1 100-1, the capacitor Cs1 102-1 may be connected in series, and the capacitor Cp1 104-1 may be connected in parallel. In the Qi resonator 10-2, an inductor L2 100-2 and a capacitor Cs2 102-2 are connected in series.

Hereinafter, an operation process of the wireless power receiver having the above-described configuration will be described below. The frequency detector 40 detects the input frequency from the voltage variations of the input voltages VACP 200-1 and VACN 202-1 of the rectifier 20. The capacitors Cp2 1047-2 are connected in series to the switches M1 and M2 (50-1 and 50-2), respectively, and are connected to the rectifier input voltages VACP and VACN. If the frequency detected by the frequency detector 40 is a low frequency in the Qi region, the output of the frequency detector 40 becomes high so that the switches M1 and M2 50-1 and 50-2 are switched on. Therefore, the capacitor Cp2 104-2 is connected to the rectifier input voltage VACP 200-1 and VACN 202-1, respectively. That is, the capacitor Cp2 104-2, which was connected in parallel, is varied in the form of being connected in the ground direction. At this time, even if connected in the ground direction, the capacitance can be increased to a large, for example, twice, so as to have the same electrical characteristics as when connected in parallel.

On the other hand, if the frequency detected by the frequency detector 40 is a high frequency, the switches M1 and M2 50-1 and 50-2 are switched off, so that the capacitor Cp2 104-2 is not visible. Accordingly, the capacitor Cp2 104-2 is separated from the rectifier input voltages VACP 200-1 and VACN 202-1, respectively.

When the circuit is configured as described above, when the A4WP resonator 10-1 operates, the capacitor Cp2 104-2 is not visible, and the L2 (100-2) and the Cs2 (102) of the Qi resonator 10-2 are not shown. Since the impedance of -2) becomes very large, the output current of the A4WP resonator 10-1 is mostly supplied to the rectifier 20 so that there is no problem in supplying power to the load. Therefore, since the resonators 10-1 and 10-2 having two different frequencies can be positioned in parallel while using one rectifier 20 in the proposed method, dual band wireless power transmission is possible. .

In FIG. 6, the rectifier 20 is composed of a diode, but an active rectifier using an active element may be used. The rectifier 20 may be a full-wave current as shown in FIG. 6, but may be a half-wave rectifier. An example of using a half-wave rectifier will be described later with reference to FIG. 15. The buck converter 30 behind the rectifier 20 is an example of a power converter, and various types of power converters may be located. For example, a boost converter, a buck-boost converter, a low drop-out regulator (LDO), and the like are possible. Thus, the shape of the rectifier 20 and the power converter in the back stage do not limit this invention.

Hereinafter, in order to verify the proposed scheme with reference to FIG. 6, an actual circuit was verified with reference to FIGS. 7 to 14. In the experiment circuit, the resonator composed of L1 (1.7uH) and Cs1 (600pF) is an A4WP resonator, and the resonator composed of L2 (12uH) and Cs2 (470nF) is a Qi resonator. A 6.78 MHz frequency was used to power the A4WP resonator and 100 kHz frequency to the Qi resonator. Therefore, the resonant frequency of each resonator is also located near 6.78 MHz and 100 kHz.

7 and 8 show the results of experiments when power is received at the A4WP frequency (no parallel capacitor in the Qi resonator) and a circuit diagram of the wireless power receiver.

The frequency is 6.78MHz and 1W is supplied to the load. In this experiment, the parallel capacitor was removed and tested in the Qi resonator 10-2. At this time, the current I _QI flowing through the Qi resonator 10-2 is approximately 30 mA peak, which is a very small value. That is, since the signal is very high compared to the resonant frequency of the Qi resonator 10-2, the impedance of the series resonator increases, so that the current does not flow much and most of the current is supplied to the rectifier 20. Since the rectifier output voltage VRECT is about 10V and the load is 100 kW, 1W is supplied.

9 and 10 show the results of experiments in the case of receiving power at the Qi frequency (no parallel capacitor in the Qi resonator) and a circuit diagram of the wireless power receiver.

When the wireless power is received at the Qi frequency as in the circuit of FIG. 10, the waveform is as shown in FIG. 9. Since there is no parallel capacitor in the Qi resonator 10-2, it can be seen that the rectifier input voltage VAC generates high frequency noise due to resonance caused by a parasitic capacitor.

11 and 12 show an experimental result when a parallel capacitor is attached to a Qi resonator and a circuit diagram of the wireless power receiver.

In order to remove noise when receiving wireless power at the Qi frequency, two 47 nF capacitors Cp2 104-2 are connected in parallel to the Qi resonator 10-2 as shown in FIG. 12. In this circuit, when energy is transferred to A4WP, the current flowing into the Qi resonator 10-2 is greatly increased to a 500 mA peak. That is, since most of the output current of the A4WP resonator 10-1 circulates through the Qi resonator 10-2, the power supplied to the rectifier 20 is weakened so that the rectifier output voltage VRECT is reduced to 4 V and the power supplied to the load is also reduced. 60% reduction.

13 and 14 are circuit diagrams of an experimental result and a wireless power receiver when the parallel capacitor of the Qi resonator is connected in the ground direction when the Qi resonator operates in the method proposed by the present invention.

In this case, the rectifier input voltage VAC is very stable and high frequency noise disappeared compared to FIG. 7, and the current flowing into the A4WP resonator 10-1 is also 4 mA peak, which is very small, so that most of the current is supplied to the load. The rectifier output voltage VRECT is 10V and normally 1W is supplied to the load.

It can be seen that the dual band frequency wireless power transmission is possible by using a resonator having two different frequencies and a common rectifier in the proposed method. The proposed method seems to increase the burden due to the addition of switches M1 and M2, but it is easier to implement the switches M1 and M2 than the components of the rectifier when implementing the integrated circuit. The proposed structure has many advantages.

In FIG. 6, a full wave rectifier has been described. However, as shown in FIG. 15, a half wave rectifier may be used.

Referring to FIG. 15, the number of capacitors Cp1 104-1 and Cp2 104-2 connected in parallel with the resonators 10-1, 10-2 of FIG. 6, the number of switches M1 50, and Since the circuit structure of FIG. 6 is the same as that of the diode of the rectifier 20 is changed, detailed description thereof will be omitted.

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

A first resonator;

A second resonator connected in parallel with the first resonator;

A single rectifier having an input of a node whose outputs of the first and second resonators are connected in parallel with each other;

At least one switch having a first output and a second output and an input, the second output being connected to ground;

At least one capacitor connected in parallel with the second resonator, one terminal connected to a first output of the switch and the other terminal connected to a rectifier input; And

A frequency detector for sensing an input frequency from a rectifier input and having an output coupled to the input of the switch;

Wireless power receiver comprising a.
The method of claim 1,

And wherein the first resonator is a high frequency resonator and the second resonator is a low frequency resonator.
The method of claim 1, wherein the first resonator

And a series resonator in which at least one inductor and at least one capacitor are connected in series.
The method of claim 1, wherein the second resonator

And a series resonator in which at least one inductor and at least one capacitor are connected in series.
The method of claim 1,

If the frequency detected by the frequency detector is a low frequency, the switch is switched on so that the capacitor is connected to the rectifier input,

And the switch is switched off when the frequency detected by the frequency detector is a high frequency so that the capacitor is separated from the rectifier input.