KR20200007519A - Wireless power receiving apparatus - Google Patents

Abstract

According to an embodiment, a wireless power receiving device comprises: a resonant circuit unit including a resonant coil generating an induced electromotive force derived from a wireless power signal transmitted from a wireless power transmitting device, and a resonant capacitor connected in series with the resonant coil and outputting an alternating current (AC) corresponding to the induced electromotive force; a rectifying circuit unit including a plurality of diodes for rectifying the AC current to a direct current (DC) to output the same to a load side; and a variable switch unit connected in parallel with at least two of the plurality of diodes while having the resonant capacitor interposed therebetween, wherein a capacitance value of the resonant capacitor is varied to an equivalent capacitance value corresponding to a set resonant frequency. The variable switch unit includes: a first switch element connected in parallel with a first diode of the plurality of diodes and the resonant capacitor; a second switch element connected in parallel with a second diode of the plurality of diodes and the resonant capacitor; and a switch controller configured to adjust an effective duty of the first and second switch elements such that the capacitance value of the resonant capacitor is varied to the equivalent capacitance value.

Description

Wireless power receiving apparatus

The present invention relates to a wireless power receiver.

Traditionally, wireless power receivers can receive electrical energy wirelessly. In addition, the wireless power receiver may be directly driven by the received wireless power. The wireless power receiver may charge the battery using the received wireless power and may be driven by the charged power.

The wireless power transmitter may transmit the wireless power to the wireless power receiver.

The Wireless Power Consortium is a part of the standardization of the technology related to the transmission of wireless power between the wireless power transmitter and the wireless power receiver, and deals with the technology of the magnetic induction wireless power transmission.

In addition, the Wireless Power Consortium, April 12, 2010, discusses "Wireless Power Transfer System Guide, Volume 1, Low Power, Part 1: Interface Definitions, Version 1.00, on interoperability in wireless power transfer." "RC1 (System Description Wireless Power Transfer, Volume 1, Low Power, Part 1: Interface Definition, Version 1.00 Release Candidate 1)" standard document.

Meanwhile, another technical standards body, the Power Matters Alliance, was established in March 2012. The Power Matters Alliance has published standard documents based on inductive coupling technology to advance the family of interface standards and provide inductive resonance power.

Wireless charging using electromagnetic induction is already encountered frequently in our lives. For example, a wireless charging method using electromagnetic induction is commercially available in electric toothbrushes, wireless coffee ports, and the like.

Recently, in addition to the conventional one-to-one wireless power transmission method, a method of transmitting power to a plurality of wireless power receivers by one wireless power transmitter has been developed.

Korean Patent Registration No. 10-1708312 (Registration Date 2017.02.20) which is a prior art discloses a wireless power receiver.

1 is a circuit diagram showing a wireless power receiver according to the prior art.

Referring to FIG. 1, the switch control unit 1 of the wireless power receiver may switch the first and second switches M1 and M2.

In this case, the first and second switches M1 and M2 may vary the capacitance of the second capacitor C2 among the first and second capacitors C1 and C2. Accordingly, the resonance frequency may vary as a whole.

In this case, the wireless power receiver may form an LC parallel resonant circuit to use a wide range of capacitance with respect to the capacitance of the second capacitor C2. However, the LC parallel resonant circuit of the related art has a problem of low reception efficiency with respect to wireless power.

Therefore, a research on a wireless power receiver configured with an LC series resonant circuit in order to increase the variable efficiency with respect to the capacitance than the LC parallel resonant circuit is in progress.

An object of the present invention is to provide a wireless power receiver having an LC series resonant circuit, the capacitance of which can be easily changed.

Another object of the present invention is to provide a wireless power receiver for zero-voltage switching (ZVS) of two switch elements connected in parallel to a capacitor of an LC series resonant circuit in order to electronically vary the capacitance. have.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned above can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The wireless power receiver according to the present invention has an advantage of facilitating selection of a resonant frequency by performing a zero voltage switching (ZVS) control on two switch elements and electronically varying the capacitance of the capacitor of the LC series resonant circuit. have.

In addition, the wireless power receiver according to the present invention can receive only the power set according to the selection of the resonance frequency.

In addition, the wireless power receiver according to the present invention does not have a separate converter has the advantage of lowering the manufacturing process and manufacturing costs.

The wireless power receiver according to the embodiment has an advantage in that the resonance frequency can be easily selected by zero voltage switching (ZVS) of the two switch elements so that the capacitance to the capacitor of the LC series resonant circuit is electronically changed.

In addition, the wireless power receiver according to the embodiment can receive only the power set according to the selection of the resonant frequency, there is an advantage that the manufacturing process and manufacturing cost can be lowered because there is no separate converter.

In addition to the effects described above, the specific effects of the present invention will be described together with the following description of specifics for carrying out the invention.

1 is a circuit diagram showing a wireless power receiver according to the prior art.
2 is a block diagram schematically illustrating a wireless power system according to the present invention.
3 is a control block diagram showing the configuration of the wireless power system shown in FIG.
4 is a circuit diagram schematically showing a wireless power receiver according to the present invention.
FIG. 5 is a timing diagram illustrating switching for power control of the wireless power receiver shown in FIG. 4.
6 is a view briefly showing a resonance point of the wireless power receiver according to the present invention.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

Hereinafter, a wireless power receiver according to an embodiment will be described.

2 is a block diagram schematically illustrating a wireless power system according to the present invention.

2, the wireless power system 100 may include a wireless power transmitter 110 and a wireless power receiver 150.

The wireless power transmitter 110 may be a power transmitter capable of wirelessly transferring power required for the wireless power receiver 150, and the wireless power transmitter 110 may charge a battery of the wireless power receiver 150. It may be a wireless charging device.

The wireless power receiver 150 may be a device capable of operating by wirelessly receiving power from the wireless power transmitter 110. The wireless power receiver 150 may charge a battery based on the wirelessly received power. Can be.

The wireless power receiver 150 may be any portable electronic device. The wireless power receiver 150 is an input / output device such as a keyboard, a mouse, an auxiliary output device for video or audio, a mobile phone, a cellular phone, a smartphone, a personal digital assistant (PDA), a portable multimedia player (PMP), a Bullets and multimedia devices.

In addition, the wireless power receiver 150 may be used in a vehicle capable of charging wireless power, but is not limited thereto.

The wireless power transmitter 110 may use one or more wireless power transfer methods. The wireless power transmitter 110 may transfer power wirelessly without contact with the wireless power receiver 150.

The wireless power transmitter 110 may transmit power in an inductive coupling method and a resonance coupling method.

The inductive coupling method transmits power based on a magnetic induction phenomenon caused by a wireless power signal, and the resonance coupling method may transmit power based on an electromagnetic resonance phenomenon caused by a wireless power signal having a specific frequency.

Here, the wireless power transmission by the inductive coupling method is a technology for wirelessly transmitting power using the primary coil and the secondary coil. In addition, the wireless power transmission using the inductive coupling method may transfer power by inducing a current toward another coil through a magnetic field changing in one coil by a magnetic induction phenomenon.

In addition, the wireless power transmission by the resonance coupling method transmits a wireless power signal from the wireless power transmitter 110 to the wireless power receiver 150, the wireless power receiver 150 is a resonance by the wireless power signal Is generated. In this case, the wireless power receiver 150 may receive power by the resonance phenomenon.

3 is a control block diagram showing the configuration of the wireless power system shown in FIG.

Referring to FIG. 3, the wireless power system 100 may include a wireless power transmitter 110 and a wireless power receiver 150.

The wireless power transmitter 110 may include a rectifier circuit 122, an inverter 124, and a transmitter 126.

The rectifier circuit 122 may rectify AC input power input from an external power source Vin to output DC power. The rectifier circuit unit 122 may include at least one diode, and the rectifier circuit unit 122 may be implemented as one of, for example, a half wave rectifier circuit, a full wave rectifier circuit, a bridge full wave rectifier circuit, and a power factor correction (PFC) circuit. Can be.

The inverter unit 124 may convert the DC power output from the rectifier circuit unit 122 into AC power and output the AC power. The inverter unit 124 may include at least one switching element for converting DC power into AC power. The at least one switching element may include, for example, an IGBT element or an FET element. The at least one switching element may repeatedly perform turn on and turn off operations according to a predetermined driving frequency.

By turning on and off the at least one switching element, the inverter unit 124 may convert DC power into AC power.

The inverter unit 124 may be configured as a half bridge circuit or a full bridge circuit.

Using the AC power output from the inverter unit 124, the transmitter 126 transmits a wireless power signal to the wireless power receiver 150. The transmitter 126 may include a transmission coil L and a capacitor C connected in series with each other.

In this case, the transmitting coil L and the capacitor C may be implemented as any one of a series resonant circuit, a parallel resonant circuit, and a series-parallel resonant circuit.

Here, the transmission coil L may form a magnetic field that is a wireless power signal using the AC power output from the inverter unit 124. The transmission coil L may transmit power so that an AC current is induced by the wireless power signal to the receiving coil L1 included in the wireless power receiver 150.

The wireless power transmitter 110 has a resonance frequency defined by the inductance of the transmission coil L and the capacitance of the capacitor C.

The wireless power receiver 150 may include a receiver (hereinafter, referred to as a “resonance circuit unit”, 152), a variable switch unit 154, and a rectifier circuit unit 156.

The resonant circuit unit 152 may generate an AC power by receiving a wireless power signal transmitted from the transmitter 126. The resonant circuit unit 152 may include a resonant coil L1 and a resonant capacitor C1 connected in series with each other.

The resonance frequency of the wireless power receiver 150 may be defined by the inductance value of the resonance coil L1 and the capacitance value of the resonance capacitor C1.

The variable switch unit 154 may be connected to the resonance capacitor C1 and the rectifier circuit unit 156. The variable switch unit 154 may control the capacitance value of the resonance capacitor C1 to have an equivalent capacitance value corresponding to the set resonance frequency.

The variable switch unit 154 may include first and second switch elements (not shown). The first switch element may switch in the positive period of the AC power input from the rectifier circuit unit 156, and the second switch element may switch in the negative period of the AC power input from the rectifier circuit unit 156. .

In addition, the effective duty may be determined according to the duty of the first and second switch elements and the equivalent capacitance value of the resonant capacitor C1.

A detailed description of the variable switch unit 154 will be described later with reference to FIG. 4.

The rectifier circuit unit 156 may output AC power by converting AC power output from the resonance circuit unit 152. The rectifier circuit unit 156 may include a rectifier circuit composed of a plurality of diodes and one or more capacitor elements. The rectifier circuit unit 156 may be a half-wave rectifier circuit, a full-wave rectifier circuit, a bridge full-wave rectifier circuit, a power factor correction (PFC) circuit, or the like.

The rectifier circuit unit 156 may output the rectified DC power to a load side.

In an embodiment, the receiver 150 may further include a converter (not shown).

That is, the converter unit may be positioned between the rectifier circuit unit 156 and the load side (Load). The converter unit may vary the voltage level of the DC power output from the rectifier circuit unit 156. In this case, the converter may be a DC-DC converter connected to a load side using DC power.

The wireless power receiver 150 may be physically coupled to the load side, or the wireless power receiver 150 may be implemented as some modules in the load side.

4 is a circuit diagram schematically showing a wireless power receiver according to the present invention.

First, FIG. 4 (a) is a circuit diagram applied to a wireless power receiver, and FIG. 4 (b) shows an equivalent circuit diagram with respect to the circuit diagram shown in FIG. 4 (a).

4A and 4B, the wireless power receiver 150 may include a resonant circuit unit 152, a variable switch unit 154, and a rectifier circuit unit 156.

First, the resonant circuit unit 152 may include a resonant coil L1 and a resonant capacitor C1.

The resonant coil L1 may generate an organic electromotive force Iac + Vac corresponding to the wireless power signal transmitted from the wireless power transmitter 150. In addition, the resonant capacitor C1 may be connected in series to one end of the resonant coil L1 and may output AC power Vo to the organic electromotive force Iac + Vac.

At this time, according to the operation of the variable switch unit 154, the capacitance value of the resonant capacitor (C1) may be changed to the equivalent capacitance value.

First, the rectifying circuit unit 156 may be implemented as a bridge full-wave rectifying circuit including the first to fourth diodes D1 to D4.

In this case, the first and fourth diodes D1 to D4 are operated at a position period (both periods) of the AC power Vo output from the resonance circuit unit 152. The second and third diodes D2 and D3 may operate in the negative period (negative period) of the AC power Vo output from the resonance circuit unit 152 to output the full-wave rectified DC power Vd.

Here, the anode of the first diode D1 may be connected to one end of the resonant coil L1, and the cathode of the first diode D1 may be connected to the cathode of the second diode D2.

The cathode of the second diode D2 is connected to the cathode of the first diode D1, and the anode of the second diode D2 has one end of the resonant capacitor C1 and the fourth diode D4 at the first node n1. It can be connected to the cathode of).

The cathode of the third diode D3 is connected to the anode of the first diode D1, the cathode of the third diode D3 is connected to ground, and the cathode of the fourth diode D4 is connected to the first node n1. ), And the anode of the fourth diode D4 may be connected to ground.

Here, the rectifying circuit unit 156 may include a smoothing capacitor C _L smoothing the full-wave rectified DC power (vd).

The variable switch unit 154 may include a first switch element sw1, a second switch element sw2, and a switch controller 155.

The first switch element sw1 may be connected in parallel with the resonant coil L1 and the resonant capacitor C1. In addition, the first switch element sw1 may be connected in parallel with the second diode D2 and the resonant capacitor C1.

Here, the first switch element sw1 may be a P-channel field effect transistor (MOSFET). The first switch control signal V _gh output from the switch controller 155 is input to the gate terminal of the first switch element sw1, and the source terminals of the first switch element sw1 are the first and second diodes ( The drain terminal of the first switch element sw1 may be connected to the resonant capacitor C1 and the second node n2.

The variable switch unit 154 may further include a first switch diode (not shown). The first switch diode may be connected to the drain terminal of the first switch element sw1 and the second node n2.

The second switch element sw2 may be an N-channel metal oxide semiconductor field effect transistor (MOSFET). The second switch control signal V _gl output from the switch controller 155 is input to the gate terminal of the second switch element sw2, and the source terminal of the second switch element sw2 is connected to the second node n2. The drain terminal of the second switch element sw2 may be connected to ground.

In addition, the variable switch unit 154 may further include a second switch diode (not shown). The second switch diode may be connected to the source terminal second node n2 of the second switch element sw2.

The switch controller 155 may output the first and second switch control signals V _gh and V _gl to the first and second switch elements sw1 and sw2, respectively.

Here, the first and second switch control signals V _gh and V _gl may be control signals for varying the capacitance value of the resonant capacitor C1 to an equivalent capacitance value corresponding to the set resonance frequency.

That is, the switch control unit 155 may output the first switch control signal V _gh for soft switching of the first switch element sw1 in the positive period (both period) of the AC power Vo.

In addition, the switch control unit 155 may output the second switch control signal V _gl for soft switching of the second switch element sw2 in the negative period (negative period) of the AC power Vo.

At this time, in a period in which the voltage between both ends of the resonant capacitor C1, that is, the voltage between the first and second nodes n1 and n2, decreases during the positive period of the AC power Vo, the switch controller 155 may switch the first switch. The control signal V _gh may be output to the first switch element sw1.

In addition, the switch control unit 155 outputs the second switch control signal V _gl to the second switch element sw2 in a period in which the voltage between both ends of the resonance capacitor C1 increases during the negative period of the AC power Vo. can do.

That is, the switch controller 155 controls the effective duty of the first and second switch elements sw1 and sw2 so that the capacitance value of the resonant capacitor C1 is changed to an equivalent capacitance value corresponding to the resonance frequency. I can regulate it.

The switch controller 155 may output the first and second switch control signals V _gh and V _gl such that the capacitance value of the resonant capacitor C1 is changed to the equivalent capacitance value according to the resonance frequency. That is, when the voltage between both ends of the resonant capacitor C1, that is, the voltage between the first and second nodes n1 and n2 is 0 voltage, the switch controller 155 may control the first and second switch control signals V _gh,. V _gl ) may be output to allow the first and second switch elements sw1 and sw2 to turn on during an effective duty.

Here, the switch controller 155 may measure the voltage between the first and second nodes n1 and n2 in a set time or in real time.

Equation 1 below shows that the capacitance value of the resonant capacitor C1 is changed to an equivalent capacitance value.

Here, C _v may be an equivalent capacitance value, C _p may be a capacitance value of the resonant capacitor C1, and d may be a duty cycle.

Therefore, according to Equation 1 described above, the switch controller 155 may electronically change the capacitance value of the resonant capacitor C1 to the equivalent capacitance value.

In this case, the effective duty is smaller than the duty and may be greater than zero (zero).

FIG. 5 is a timing diagram illustrating switching for power control of the wireless power receiver shown in FIG. 4. 6 is a view showing briefly the resonance point of the wireless power receiver according to the present invention.

Referring to FIG. 5, the switch controller 155 may include the first and second switch elements sw1 and sw1 based on the AC power Vo output from the resonant circuit unit 152 and the voltage V12 of both ends of the resonant capacitor C1. The duty of sw2) can be varied. In this case, by varying the duty of the first and second switch elements sw1 and sw2, the switch controller 155 may vary the capacitance value of the resonant capacitor C1 to an equivalent capacitance value.

FIG. 5A is a diagram showing AC power Vo, and FIG. 5B is a diagram showing voltages at both ends of the resonant capacitor C1, that is, voltage V12. FIG. The first and second switch control signals V _gh and V _gl supplied to the second switch elements sw1 and sw2 are shown.

Each of the first and second switch control signals V _gh and V _gl shown in FIG. 5C are turned on and complementarily complemented to each other in the positive and negative periods of the AC power Vo shown in FIG. 5A. It may indicate a signal that is turned off.

In this case, referring to FIG. 5B, the first switch element sw1 may receive a first switch control signal V _gh from the switch controller 155. The first switch element sw1 may be turned on in the negative period of the AC power Vo.

Here, the first switch element sw1 does not turn on at the time when the first switch control signal V _gh is input and does not turn on when the voltage V12 of the resonant capacitor C1 reaches zero voltage. Can be.

That is, the first switch element sw1 does not turn on when the first switch control signal V _gh is input by the drain-source voltage Vds. Thereafter, the first switch element sw1 may perform a soft switching operation by turning on when the voltage V12 of both ends becomes zero. In addition, the second switch element sw2 may perform a soft switching operation in the same manner as the first switch element sw1.

6A illustrates an electronic resonance point and a load side when the first and second switch elements sw1 and sw2 are varied according to the duty change of the first and second switch control signals V _gh and V _gl . The output power supplied to the figure.

That is, the resonant circuit unit 152 compares the series resonant circuit composed of the resonant coil L1 and the resonant capacitor C1 and the parallel resonant circuit composed of the resonant coil L1 and the resonant capacitor C1.

6 (b) shows the efficiency according to the duty change when the series resonance and the parallel resonance circuit are formed as described above.

6 (a) and 6 (b), the series resonant circuit including the resonant coil L1 and the resonant capacitor C1 shows better efficiency at the duty change, that is, the duty increase, than the parallel resonant circuit. .

The above-described embodiments are limited by the above-described embodiments and the accompanying drawings because various substitutions, modifications, and changes can be made without departing from the technical spirit for those skilled in the art. It is not.

Claims (9)

A resonant circuit unit including a resonant coil generating an induced electromotive force derived from a wireless power signal transmitted from a wireless power transmitter and a resonant capacitor connected in series with the resonant coil and outputting an alternating current corresponding to the induced electromotive force;
A rectifier circuit unit including a plurality of diodes rectifying the AC current into a DC current and outputting the same to a load side; And
A variable switch unit connected in parallel with at least two of the plurality of diodes and the resonant capacitor therebetween, the variable switch having a capacitance value of the resonant capacitor variable to an equivalent capacitance value corresponding to a set resonant frequency;
The variable switch unit,
A first switch element connected in parallel with a first diode of the resonant capacitor and the plurality of diodes;
A second switch element connected in parallel with a second diode of the resonant capacitor and the plurality of diodes; And
And a switch controller configured to adjust effective duty of the first and second switch elements such that the capacitance value of the resonant capacitor is changed to the equivalent capacitance value.
Wireless power receiver.
The method of claim 1,
The resonant capacitor,
The equivalent capacitance value increases when the effective duty of the first and second switch elements increases, and the equivalent capacitance value decreases when the effective duty of the first and second switch elements decreases.
Wireless power receiver.
The method of claim 1,
The switch control unit,
Transmitting a first switch control signal to the first switch in a period in which the voltage across the resonance capacitor decreases during the positive period of the alternating current;
Transmitting a second switch control signal to the second switch in a period in which the voltage across the resonance capacitor increases during the negative period of the AC current;
Wireless power receiver.
The method of claim 3, wherein
The first switch element,
A gate terminal to which the first switch control signal is input, a source terminal connected to an output terminal of the rectifier circuit unit, and a drain terminal connected to the resonance capacitor,
The first switch element,
The first switch control signal is transmitted, and turned on when the voltage across the resonance capacitor becomes zero voltage,
Wireless power receiver.
The method of claim 3, wherein
The second switch element,
A gate terminal to which the second switch control signal is input, a drain terminal connected to a ground terminal of the rectifier circuit unit, and a source terminal connected to the resonance capacitor;
The second switch element,
The second switch control signal is transmitted, and turned on when the voltage across the resonance capacitor becomes zero voltage,
Wireless power receiver.
The method of claim 3, wherein
The switch control unit,
Varying the duty of each of the first and second switch control signals according to the resonance frequency;
Wireless power receiver.
The method of claim 6,
The effective duty is,
Less than the duty,
Wireless power receiver.
The method of claim 1,
The first switch element,
P-channel field effect transistor (MOSFET)
The second switch element,
N-channel field effect transistor (MOSFET, Metal Oxide Semiconductor field dffect transistor)
Wireless power receiver.
The method of claim 8,
The variable switch unit,
A first switch diode connected between the first switch element and the resonant capacitor; And
Further comprising a second switch diode connected between the second switch element and the resonant capacitor,
Wireless power receiver.

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