KR102117869B1 - Wireless power receiver having active rectifier - Google Patents

Abstract

According to various embodiments of the present invention, in an active rectifier, first to fourth MOSFETs performing a switching operation according to an input voltage from a power receiver and connected in a cross-coupled structure, the third MOSFET and the Each of the fourth MOSFETs may include a ZVS&ZCS controller that controls to perform zero voltage switching (ZVC) or zero current switching (ZCS). In addition, various embodiments may be possible.

Description

Wireless power receiver with active rectifier {WIRELESS POWER RECEIVER HAVING ACTIVE RECTIFIER}

The present invention relates to a wireless power receiver, and more particularly, to a wireless power receiver with an active rectifier.

A mobile terminal such as a mobile phone or PDA (Personal Digital Assistants) is driven by a rechargeable battery due to its characteristics, and in order to charge such a battery, a separate charging device is used to supply electric energy to the battery of the mobile terminal. Usually, separate contact terminals are provided on the outside of the charging device and the battery, so that the charging device and the battery are electrically connected by contacting them.

However, in this type of contact charging, since the contact terminal protrudes to the outside, contamination by foreign matter is easy and for this reason, a problem of battery charging is not performed correctly. In addition, charging is not performed properly even when the contact terminals are exposed to moisture.

In order to solve this problem, wireless charging or contactless charging technology has been developed in recent years and has been utilized in many electronic devices.

This wireless charging technology uses wireless power transmission and reception, for example, a system capable of automatically charging a battery by simply placing a mobile phone on a charging pad without connecting a separate charging connector. It is generally known to the public as a cordless electric toothbrush or a cordless electric razor. This wireless charging technology has the advantage of increasing the waterproof function by charging the electronic products wirelessly, and has the advantage of increasing the portability of electronic devices since a wired charger is not required, and related technologies are expected to greatly develop in the coming electric vehicle era. .

The wireless charging technology is largely divided into an electromagnetic induction method using a coil, a resonance method using resonance, and a radio wave (RF/Micro Wave Radiation) method that converts and transmits electrical energy into microwaves.

Until now, the method using electromagnetic induction has become the mainstream, but recently, at home and abroad, it has succeeded in experiments to transmit power wirelessly at a distance of several tens of meters using microwaves. It seems that the world will be opened.

The method of transmitting power by electromagnetic induction is a method of transmitting power between the primary coil and the secondary coil. When a magnet is moved in a coil, an induced current is generated. Using this, a magnetic field is generated at a transmitting end and a current is induced according to a change in a magnetic field at the receiving end to generate energy. This phenomenon is called a magnetic induction phenomenon, and the power transmission method using the phenomenon has excellent energy transmission efficiency.

Resonance method, in 2005, Professor Soljacic of MIT announced a system that transmits electricity wirelessly even when a few meters (m) away from a charging device using the resonance mode power transmission principle as a Coupled Mode Theory. The wireless charging system of the MIT team is based on the concept of physics that when the sound of the resonance is called, the wine glasses next to it sound at the same frequency. Instead of resonating the sound, the researchers resonated electromagnetic waves containing electrical energy. Resonant electric energy is transmitted directly only when a device with a resonance frequency is present, and since unused parts are absorbed into an electric field instead of spreading into the air, unlike other electromagnetic waves, it is not expected to affect surrounding machinery or the body. .

Meanwhile, in the case of a resonance method among wireless power transmission technologies, an AC-DC power conversion circuit may be used in a receiving end, for example, a wireless power receiver. In the wireless power transmission, power is transmitted using an AC signal of several hundreds of kHz to several tens of MHz. The wireless power receiver needs an AC-DC power conversion circuit that converts power to a DC signal by receiving this relatively high analog AC signal. However, in the AC-DC conversion circuit, power conversion loss usually follows. Cost and power transmission efficiency and power consumption are the most important requirements for wireless chargers, so efforts to reduce power conversion losses are required.

In particular, the AC-DC conversion circuit can be composed of a rectifier that converts AC into DC, a DC-DC converter that converts rectified DC into a required voltage, and passive elements that stably adjust the DC waveform of the output stage. Efforts have been made to reduce power conversion loss by using a high efficiency active rectifier.

Therefore, according to embodiments of the present invention, it is intended to provide an active rectifier having a relatively high input voltage and a high frequency operating frequency.

In addition, according to embodiments of the present invention, to provide a wireless power receiver for receiving wireless power using an active rectifier having a high input voltage and a high frequency operating frequency.

In order to achieve the above, the active rectifier according to an embodiment of the present invention performs the switching operation according to the input voltage from the power receiver and the first to fourth MOSFETs connected in a cross-coupled structure, and the Each of the 3 MOSFET and the 4 MOSFET may include a ZVS&ZCS controller that controls to perform zero voltage switching (ZVC) or zero current switching (ZCS).

In addition, the wireless power receiver according to an embodiment of the present invention includes a power receiving unit for receiving wireless power, and switching operations performed according to an input voltage based on the received power and connected in a cross-coupled structure. An active rectifier comprising a fourth MOSFET and a ZVS&ZCS controller that controls each of the third and fourth MOSFETs to perform zero voltage switching (ZVC) or zero current switching (ZCS), and rectifying the received power; It may include a DC converter for DC-DC conversion of the rectified power.

According to various embodiments of the present invention, the active rectifier controls switching on and off through ZVS and ZCS control, thereby enabling stable switching even at a high 6.78 MHz frequency, thereby improving rectification efficiency and reducing switching loss.

In addition, according to various embodiments of the present invention, since an active rectifier having a high input voltage and a high frequency operating frequency can be provided, it is possible to develop a one-chip power conversion IC with a simple structure compared to an existing structure. Cost reduction and volume reduction effect can be obtained.

1 is a conceptual diagram for explaining the overall operation of the wireless charging system
2 is a block diagram of a wireless power transmitter and a wireless power receiver according to an embodiment of the present invention
3 is a block diagram of a wireless power receiver according to an embodiment of the present invention
4 is a view for explaining an active rectifier using a comparator according to an embodiment of the present invention
5 is a view for explaining an active rectifier using a ZVC / ZCS controller according to an embodiment of the present invention
6 is an exemplary circuit diagram of a first limiter according to an exemplary embodiment of the present invention
7 is an exemplary circuit diagram of an active rectifier using a ZVC/ZCS controller according to an embodiment of the present invention
7B is a view showing a rectified current waveform according to an active rectifying circuit according to an embodiment of the present invention
8 is a view showing a voltage waveform of an active rectifier using a ZVC/ZCS controller according to an embodiment of the present invention
9 is a view showing a gate driving voltage waveform (Gate Driver Waveform) and a rectified current waveform (Rectified Current) according to an embodiment of the present invention
10 is a view for explaining a method of determining a ZCS point when controlling off of the third and fourth MOSFETs at the top using a ZVS & ZCS controller according to an embodiment of the present invention
11 is a view for explaining a ZCS control circuit according to an embodiment of the present invention
12 is a view for explaining a ZVS control circuit according to an embodiment of the present invention

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail. It should be noted that the same components in the drawings are indicated by the same reference numerals wherever possible. In the following description and accompanying drawings, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention are omitted.

1 is a conceptual diagram for explaining the overall operation of the wireless charging system. As shown in FIG. 1, the wireless charging system includes a wireless power transmitter 100 and at least one wireless power receiver 110-1,110-2,110-n.

The wireless power transmitter 100 may wirelessly transmit power (1-1, 1-2, 1-n) to at least one wireless power receiver (110-1, 110-2, 110-n). More specifically, the wireless power transmitter 100 may transmit power 1-1, 1-2, 1-n wirelessly only to an authenticated wireless power receiver that has performed a predetermined authentication procedure.

The wireless power transmitter 100 may form an electrical connection with the wireless power receivers 110-1,110-2,110-n. For example, the wireless power transmitter 100 may transmit wireless power in the form of electromagnetic waves to the wireless power receivers 110-1, 110-2, and 110-n.

Meanwhile, the wireless power transmitter 100 may perform two-way communication with the wireless power receivers 110-1, 110-2, and 110-n. Here, the wireless power transmitter 100 and the wireless power receivers 110-1, 110-2, 110-n may process or transmit/receive packets 2-1, 2-2, 2-n composed of predetermined frames. The above-described frame will be described in more detail later. In particular, the wireless power receiver may be implemented as a mobile communication terminal, PDA, PMP, smartphone, or the like.

The wireless power transmitter 100 may wirelessly provide power to a plurality of wireless power receivers 110-1, 110-2, and 110-n. For example, the wireless power transmitter 100 may transmit power to a plurality of wireless power receivers 110-1,110-2,110-n through a resonance method. When the wireless power transmitter 100 adopts the resonance method, the distance between the wireless power transmitter 100 and the plurality of wireless power receivers 110-1,110-2,1110-n may be preferably 30 m or less. In addition, when the wireless power transmitter 100 adopts the electromagnetic induction method, the distance between the power providing device 100 and the plurality of wireless power receivers 110-1,110-2,110-n may be preferably 10 cm or less.

The wireless power receivers 110-1, 110-2, and 110-n may receive wireless power from the wireless power transmitter 100 to charge the battery provided therein. In addition, the wireless power receivers 110-1, 110-2, and 110-n may transmit signals for requesting wireless power transmission, information required for wireless power reception, wireless power receiver status information, or wireless power transmitter 100 control information. 100). The transmission signal information will be described later in more detail.

Also, the wireless power receivers 110-1, 110-2, and 110-n may transmit a message indicating each charging state to the wireless power transmitter 100.

The wireless power transmitter 100 may include display means such as a display, and the wireless power receiver 110-1,110-2,110-n based on a message received from each of the wireless power receivers 110-1,110-2,110-n. Each state can be displayed. In addition, the wireless power transmitter 100 may also display the estimated time until charging of each wireless power receiver 110-1,110-2,110-n is completed.

The wireless power transmitter 100 may transmit a control signal for disabling the wireless charging function to each of the wireless power receivers 110-1, 110-2, and 110-n. The wireless power receiver receiving the disable control signal of the wireless charging function from the wireless power transmitter 100 may disable the wireless charging function.

2 is a block diagram of a wireless power transmitter and a wireless power receiver according to an embodiment of the present invention.

As illustrated in FIG. 2, the wireless power transmitter 200 may include a power transmission unit 211, a control unit 212, and a communication unit 213. In addition, the wireless power receiver 250 may include a power receiver 251, a control unit 252, and a communication unit 253.

The power transmitter 211 may provide power required by the wireless power transmitter 200 and wirelessly provide power to the wireless power receiver 250. Here, the power transmission unit 211 may supply power in the form of an AC waveform, and while supplying power in the form of an AC waveform, it may be converted into an AC waveform using an inverter and supplied in the form of an AC waveform. The power transmitter 211 may be implemented in the form of a built-in battery, or may be implemented in the form of a power receiving interface to receive power from the outside and supply it to other components. It will be readily understood by those skilled in the art that the power transmitter 211 is not limited as long as it is a means capable of providing power having a constant AC waveform.

In addition, the power transmitter 211 may provide an AC waveform in the form of electromagnetic waves to the wireless power receiver 250. The power transmitter 211 may further include a loop coil, and accordingly, may transmit or receive a predetermined electromagnetic wave. When the power transmitter 211 is implemented as a loop coil, the inductance L of the loop coil may be changeable. Meanwhile, those skilled in the art will readily understand that the power transmitter 211 is not limited as long as it is a means capable of transmitting and receiving electromagnetic waves.

The controller 212 may control the overall operation of the wireless power transmitter 200. The controller 212 may control the overall operation of the wireless power transmitter 200 by using an algorithm, program, or application required for control read from a storage unit (not shown). The control unit 212 may be implemented in the form of a CPU, microprocessor, mini computer. The detailed operation of the control unit 212 will be described later in more detail.

The communication unit 213 may communicate with the wireless power receiver 250 in a predetermined manner. The communication unit 213 communicates with the communication unit 253 of the wireless power receiver 250 using near field communication (NFC), Zigbee communication, infrared communication, visible light communication, Bluetooth method, and Bluetooth low energy method. You can do The communication unit 213 according to an embodiment of the present invention may perform communication using a Bluetooth low energy method. In addition, the communication unit 213 may use a CSMA/CA algorithm. The configuration related to frequency and channel selection used by the communication unit 213 will be described later in more detail. On the other hand, the above-described communication method is merely exemplary, and the present invention is not limited by the specific scope of communication performed by the communication unit 213.

Meanwhile, the communication unit 213 may transmit a signal for information of the wireless power transmitter 200. Here, the communication unit 213 may unicast, multicast or broadcast the signal.

The communication unit 213 may receive power information from the wireless power receiver 250. Here, the power information may include at least one of the capacity of the wireless power receiver 250, the remaining battery capacity, the number of charges, the usage amount, the battery capacity, and the battery ratio. In addition, the communication unit 213 may transmit a charging function control signal that controls the charging function of the wireless power receiver 250. The charging function control signal may be a control signal that controls the wireless power receiver 251 of the specific wireless power receiver 250 to enable or disable the charging function.

The communication unit 213 may receive signals from other wireless power transmitters (not shown) as well as the wireless power receiver 250. For example, the communication unit 213 may receive the notice signal of the frame of Table 1 described above from another wireless power transmitter.

Meanwhile, in FIG. 2, although the power transmission unit 211 and the communication unit 213 are configured with different hardware, the wireless power transmitter 200 is illustrated as being communicated in an out-band format, but this is exemplary. In the present invention, the power transmission unit 211 and the communication unit 213 are implemented with one hardware, so that the wireless power transmitter 200 may perform communication in an in-band format.

The wireless power transmitter 200 and the wireless power receiver 250 can transmit and receive various signals, and accordingly, the wireless power receiver 250 joins and transmits and receives wireless power to the wireless power network managed by the wireless power transmitter 200. The charging process through may be performed, and the above-described process will be described in more detail below.

3 is a block diagram of a wireless power receiver according to an embodiment of the present invention.

3, the wireless power receiver 250 includes a power receiving unit 251, a control unit 252, a communication unit 253, a rectifying unit 254, a DC/DC converter unit 255, a switch unit 256 And a charging unit 257.

Descriptions of the power receiving unit 251, the control unit 252, and the communication unit 253 will be omitted here. The rectifying unit 254 may rectify wireless power received by the power receiving unit 251 in the form of direct current. The DC/DC converter unit 255 may convert the rectified power to a preset gain. For example, the DC/DC converter unit 255 may convert the rectified power so that the voltage of the output terminal 259 becomes 5V.

The switch unit 256 may connect the DC/DC converter unit 255 and the charging unit 257. The switch unit 256 may maintain an on/off state under the control of the control unit 252. The charging unit 257 may store converted power input from the DC/DC converter unit 255 when the switch unit 256 is turned on.

The rectifier 254 included in the wireless power receiver 250 according to an embodiment of the present invention as described above may be implemented in various ways.

For example, the rectifier 254 may use a rectifier composed of a full-bridge rectifier circuit using constant wave rectification or a rectifier composed of a rectifier circuit using a MOSFET.

In the case of a full-bridge type rectifier circuit, it is constructed using a packaged single-piece Schottky Barrier Diode (SBD), and has a small advantage of small difference in forward voltage and small loss, but it is difficult to integrate into a CMOS process. A full-bridge rectifier circuit, for example, a passive rectifier composed of four diodes, can be connected to the AC input stage to simply rectify the current without additional control and output the voltage according to the rectified current. However, a passive element (Discrete element) may have a disadvantage in that efficiency is high in a system in which a relatively high current flows due to a large volume and a large voltage across the diode, which causes a large loss in power transmission. This can be inefficient for wireless power transmission systems.

In order to overcome this disadvantage, a rectifier composed of a rectifier circuit using a MOSFET may be used in the wireless power receiver 250. A rectifier composed of a rectifier circuit using a MOSFET may be, for example, an active rectifier that rectifies current by using a MOSFET as a switch instead of four diodes.

According to various embodiments of the present invention, an active rectifier may be implemented by various embodiments.

4 is a view for explaining an active rectifier using a comparator according to an embodiment of the present invention. Referring to FIG. 4, an active rectifier using a comparator may include four MOSFETs 410 to 440, an input node 402, and a comparator 450. The four MOSFETs 410 to 440 may include a first MOSFET 410 and a second MOSFET 420 at the bottom, and a third MOSFET 430 and a fourth MOSFET 440 at the top. The gates of the lower first MOSFET 410 and the second MOSFET 420 may be connected to the input node 402 in a cross-coupled structure. The gate of each of the upper third MOSFET 430 and the fourth MOSFET 440 may be connected to the comparator 450.

Since the voltage across both of the first to fourth MOSFETs 410 to 440 of the active rectifier using the comparator is much smaller than a diode, it may be efficient.

However, the current flows in one direction of the diode, but the first to fourth MOSFETs 410 to 440 may flow in both directions, so reverse current may occur if not accurately controlled. If reverse current occurs, the rectification efficiency may be worse. Therefore, in an active rectifier, it may be important to control the MOSFETs to prevent reverse current. In addition, in the case of an active rectifier using a comparator, it is difficult to perform a switching operation at a high frequency, for example, 6.78 MHz, and a more complicated circuit may be required in order to stably perform switching even at a high frequency.

Therefore, in another embodiment of the present invention, it is possible to propose an active rectifier using a ZVC/ZCS controller so that efficiency is high due to low loss during rectification and there is no limit in driving frequency, and it is convenient to directly to a CMOS process.

5 is a view for explaining an active rectifier using a ZVC/ZCS controller according to an embodiment of the present invention.

Referring to FIG. 5, the active rectifier 504 using the ZVC/ZCS controller may receive an AC signal from the power receiver 502. The power receiving unit 502 may be a resonance circuit. The resonant circuit may include a coil (L) and a capacitor (Climit), it is possible to receive an AC signal of, for example, 6.78MHz based on the resonance method for power from the wireless power transmitter.

The active rectifier 504 may rectify and output AC power input from the resonant circuit 502 in the DC form.

The active rectifier 504 includes first to fourth MOSFETs 510 to 540, a first limiter 512, a second limiter 522, a third limiter 532, and a fourth A limiter 542 and a ZVS&ZCS controller 550 may be included.

The first to fourth MOSFETs 510 to 540 may include a first MOSFET 510 and a second MOSFET 520 at the bottom, and a third MOSFET 530 and a fourth MOSFET 540 at the top. The first to fourth MOSFETs 510 to 540 may be, for example, N-channel LDMOS (NLDMOS).

Gates of each of the upper third MOSFET 530 and the fourth MOSFET 540 may be connected to the ZVS&ZCS controller 550. One end of the third limiter 532 may be connected to the drain of the third MOSFET 530, and the other end of the third limiter 532 may be connected to the ZVS&ZCS controller 550. One end of the fourth limiter 542 may be connected to the drain of the fourth MOSFET 540, and the other end of the fourth limiter 542 may be connected to the ZVS&ZCS controller 550.

Each of the third MOSFET 530 and the fourth MOSFET 540 may perform on or off switching through a driving signal according to the control of the ZVS&ZCS controller 550.

The ZVS&ZCS controller 550 may control each of the third MOSFET 530 and the fourth MOSFET 540 to perform zero voltage switching (ZVC) and zero current switching (ZCS). Zero voltage switching refers to switching that turns on when the voltage is zero to reduce switching losses. Zero current switching refers to switching that reduces switching losses by turning off when the current is zero.

The third limiter 532 may limit the input voltage input to the gate of the third MOSFET 530 to be less than a predetermined voltage, and the fourth limiter 542 may include a fourth MOSFET 540 ), the input voltage input to the gate may be limited to a predetermined voltage.

The lower first MOSFET 510 may be connected to the first limiter 512. The second MOSFET 520 may be connected to a second limiter 522. The first MOSFET 510 and the first limiter 512 and the second MOSFET 520 and the second limiter 522 may be connected in a cross-coupled gate structure.

The first limiter 512 may limit the input voltage input to the gate of the first MOSFET 510 to be less than a predetermined voltage, for example, less than 5V, and the second limiter 522 is the second MOSFET The input voltage input to the gate of 520 may be limited to be less than a predetermined voltage, for example, 5V.

In a typical active rectifier circuit, the gates of the first and second MOSFETs at the bottom are connected to the input node in a cross-coupled structure. However, this is because the input voltage of the active rectifier did not rise above 5V, which is a predetermined voltage, for example. However, in the case of wireless power transmission, the input voltage input to the rectifier is often higher than a predetermined voltage, such as 10V or more. Accordingly, if the first limiter 512 and the second limiter 522 are not connected, when the input voltage is equal to or higher than a predetermined voltage, for example, 10V, the first MOSFET 510 and the second MOSFET 520 The gate voltage is 10V, so each gate can be broken down. This is because the gate-source voltages of the first MOSFET 510 and the second MOSFET 520 can be determined up to 5V. Therefore, in an embodiment of the present invention, the first MOSFET 510 at the bottom may be connected to the first limiter 512 to prevent the gate breakdown of the first MOSFET 510 and the second MOSFET 520. The second MOSFET 520 may be connected to a second limiter 522.

The first limiter 512 and the second limiter 522 may operate on the same principle. Taking the circuit structure of the first limiter 512 as an example, FIG. 6 is an exemplary circuit diagram of the first limiter 512 according to an embodiment of the present invention.

Referring to FIG. 6, the first limiter 512 may include a limiter MOSFET 513 connected to the gate of the first MOSFET 510. The input voltage may be applied to the drain of the limiter MOSFET 513, 5 V may be applied to the gate, and the source may be connected to the first MOSFET 510. The limiter MOSFET 513 may enable the gate of the first MOSFET 510 to be gate-drived with a voltage lower than 5V. The first limiter 512 not only allows the gate of the first MOSFET 510 to be driven without an additional voltage controller and gate driver, but also reduces switching loss, thereby increasing the efficiency of the rectifier.

Meanwhile, the first limiter 512 may further include a zener diode 514 connected to the source terminal of the limiter MOSFET 513. The Zener diode 514 may prevent the reverse current from flowing. Since the second limiter 522 operates on the same principle as the first limiter 512, the detailed circuit and description may be understood as the circuit and description of the first limiter 512. .

As described above, the active rectifier 504 using the ZVC/ZCS controller 550 according to the second embodiment of the present invention is a ZVC (Zero Voltage) to prevent reverse currents of the first to fourth MOSFETs 510 to 540. Switching)/ZCS (Zero Current Switching) can be controlled.

Hereinafter, a more specific circuit and operation principle of an active rectifier using a ZVC/ZCS controller according to an embodiment of the present invention as described above will be described.

7 is an exemplary circuit diagram of an active rectifier using a ZVC/ZCS controller according to an embodiment of the present invention.

Referring to FIG. 7, the active rectifier 504 includes first to fourth MOSFETs 710 to 740, a first limiter 712, a second limiter 722, and a third limiter. 732, a fourth limiter 742, and a ZVS&ZCS controller 750.

The first to fourth MOSFETs 710 to 740 may include a first MOSFET 710 and a second MOSFET 720 at the bottom, and a third MOSFET 730 and a fourth MOSFET 740 at the top. The first to fourth MOSFETs 710 to 740 may be, for example, N-channel LDMOS (NLDMOS), respectively.

The gate of each of the upper third MOSFET 730 and the fourth MOSFET 740 may be connected to the ZVS&ZCS controller 750.

The ZVS&ZCS controller 750 includes a first ZVS&ZCS control unit 751-1, a first bootstrap diode 753-1, a first bootstrap capacitance 755-1, and a first diode 757-1. , A second ZVS&ZCS control unit 751-2, a second bootstrap diode 753-2, a second bootstrap capacitance 755-2, and a second diode 757-2. .

Here, the first ZVS&ZCS controller 751-1, the first bootstrap diode 753-1, the first bootstrap capacitance 755-1, and the first diode 757-1 are the third MOSFET ( It can be used to control zero voltage switching (ZVC) and zero current switching (ZCS) for 730).

The first ZVS&ZCS control unit 751-1 may control zero voltage switching (ZVC) and zero current switching (ZCS) for the third MOSFET 730. The first ZVS&ZCS control unit 751-1 may output a gate driving signal to control zero voltage switching (ZVC) and zero current switching (ZCS) for the third MOSFET 730. The first bootstrap diode 753-1 uses a voltage of a gate driving signal for driving the third MOSFET 730 using the first bootstrap capacitance 755-1 to a voltage higher than the input voltage. You can print by jumping. The first diode 757-1 may prevent a gate driving signal for driving the third MOSFET 730 from being input to the gate of the fourth MOSFET 740.

Meanwhile, the second ZVS&ZCS control unit 751-2, the second bootstrap diode 753-2, the second bootstrap capacitance 755-2, and the second diode 757-2 are the fourth MOSFET It can be used to control zero voltage switching (ZVC) and zero current switching (ZCS) for 740.

The second ZVS&ZCS control unit 751-2 may control zero voltage switching (ZVC) and zero current switching (ZCS) for the fourth MOSFET 740. The second ZVS&ZCS control unit 751-2 may output a gate driving signal to control zero voltage switching (ZVC) and zero current switching (ZCS) for the fourth MOSFET 740. The second bootstrap diode 753-2 uses the second bootstrap capacitance 755-2 to convert the voltage of the gate driving signal for driving the fourth MOSFET 740 to a voltage higher than the input voltage. You can print by jumping. The second diode 757-2 may prevent a gate driving signal for driving the fourth MOSFET 740 from being input to the gate of the third MOSFET 730.

The third limiter 732 may limit an input voltage input to the gate of the third MOSFET 730 to be less than a predetermined voltage, and the fourth limiter 742 may include a fourth MOSFET 740 ), the input voltage input to the gate may be limited to a predetermined voltage.

The lower first MOSFET 710 may be connected to the first limiter 712. The second MOSFET 720 may be connected to a second limiter 722. The first MOSFET 710 and the first limiter 712 and the second MOSFET 720 and the second limiter 722 may be connected in a cross-coupled gate structure.

The first limiter 712 may limit the input voltage input to the gate of the first MOSFET 710 to be less than a predetermined voltage, for example, less than 5V, and the second limiter 722 is the second MOSFET The input voltage input to the gate of 720 may be limited to be less than a predetermined voltage, for example, 5V.

If the operation principle of the active rectifier 704 using the ZVC/ZCS controller configured as described above is described, the active rectifier 704 has the following table 1 when the voltage of the input node from the power receiver 702 is Vc1>Vc2. Can work together.

state action When Vc1 is lower than the threshold voltage (Vth) of the first to fourth MOSFETs 710 to 740 The first to fourth MOSFETs 710 to 740 are turned off When Vc1 is higher than the first to fourth MOSFET voltage Vth Second MOSFET 720 is on, Vc2 node is shorted to GND When Vc1 reaches about 5V The gate voltage of each of the first MOSFET 710 and the second MOSFET 720 is driven by Vout-Vgs instead of Vc1 by the first limiter 712 and the second limiter 714.
(Where Vout is 5V, Vgs is the voltage between the gate and the source of each of the first MOSFET 710 and the second MOSFET 720) For example, when Vc1 increases to 5V or more, the first MOSFET 710 and The gate voltage of each of the second MOSFETs 720 may be kept constant at about 4V (Vout-Vgs). When Vc1 is increased by Vrec
The third MOSFET 730 is turned on by ZVS control of the ZVS & ZCS controller 750. Since the second MOSFET 720 and the third MOSFET 730 are turned on, the resonance current received through the power receiver 702 flows to Vrec.

Meanwhile, the active rectifier 704 includes the second MOSFET 720 and the third MOSFET 730 and the first MOSFET 710 in Table 1 when the voltage of the input node from the power receiver 702 is Vc1<Vc2. The fourth MOSFETs 740 may operate opposite to each other.

According to an embodiment of the present invention, in the operation of the active rectifier 704, the current directions of the first to fourth MOSFETs 710 to 740 may flow bidirectionally, so that the ZVS & ZCS controller 750 More accurately, the first to fourth MOSFETs 710 to 740 can be controlled on/off.

8 is a diagram showing a voltage waveform of an active rectifier 705 using a ZVC/ZCS controller according to an embodiment of the present invention. 8 shows a voltage waveform when the active rectifier 705 is in a steady-state.

Referring to (a) of FIG. 8, even if the voltage of Vc1 rises by 5 V or more, the voltage applied to the gate of the second MOSFET 720 is limited by the second limiter 722 and is maintained constant at about 4 V. Can be confirmed.

Also, referring to (b) of FIG. 8, when the voltage of Vc1 increases, it can be confirmed that the gate voltage of the third MOSFET 730 is driven to 5V according to the ZVS control of the ZVS & ZCS controller 750. Accordingly, energy from the power receiving unit 702 may flow to Vrec. Meanwhile, when Vc1 is lower than Vrec, the third MOSFET 730 may be turned off according to ZCS control of the ZVS & ZCS controller 750.

According to an embodiment of the present invention, the ZVS & ZCS controller 750 may perform ZVS control and ZCS control for on/off of each of the third and fourth MOSFETs 730 to 740, and the third and fourth Rather than controlling the on/off of each of the fourth MOSFETs 730 to 740, power loss can be reduced by using the ZVS & ZCS controller 750.

9 is a view showing a gate driving voltage waveform (Gate Driver Waveform) and a rectified current waveform (Rectified Current) according to an embodiment of the present invention. 9(a) is a diagram illustrating a case in which on/off of the upper third and fourth MOSFETs 730 to 740 is controlled using a comparator, and FIG. 9(b) is a ZVS & ZCS controller 750 A diagram showing a case of controlling on/off of the upper third and fourth MOSFETs 730 to 740 by using.

Referring to (a) of FIG. 9, when controlling on/off of the upper third and fourth MOSFETs 730 to 740 using a comparator, each of the comparator and the third and fourth MOSFETs 730 to 740 respectively Reverse current may be generated due to a delay between gate drivers. Reverse current can lower rectifier efficiency.

In contrast, referring to (b) of FIG. 9, when controlling on/off of the upper third and fourth MOSFETs 730 to 740 using the ZVS & ZCS controller 750, the ZVS & ZCS controller 750 ) Can minimize the reverse current by turning on and off the third and fourth MOSFETs 730 to 740 at the optimal moment (ZCS point or ZVS point) by performing ZCS control or ZVS control.

10 is a view for explaining a ZCS point determination method when controlling off of the third and fourth MOSFETs 730 to 740 at the top using the ZVS & ZCS controller 750 according to an embodiment of the present invention.

Referring to FIG. 10, off of the upper third and fourth MOSFETs 730 to 740 is performed by a comparator, and the ZVS & ZCS controller 750 is included in the ZVS & ZCS controller 750 through ZCS control. By adjusting the offset of the comparator, the reverse current can be minimized by turning off the upper third and fourth MOSFETs 730 to 740 at an optimal moment (ZCS Point).

For example, if there is no offset in the comparator as shown in (a) of FIG. 10, the comparator and the third and fourth MOSFETs 730 to 740 each have a third delay due to a delay of a gate driver. And the fourth MOSFETs 730 to 740 may be turned off late.

Accordingly, according to an embodiment of the present invention, offsets may be sequentially added to the comparator so that the third and fourth MOSFETs 730 to 740 are turned off quickly.

As the offset is added to the comparator, the third and fourth MOSFETs 730 to 740 may be gradually turned off, as shown in FIGS. 10(b), 10(c), and 10(d). However, if the third and fourth MOSFETs 730 to 740 are turned off before the ZCS point as shown in FIG. 10(d), the input voltage may be increased instantaneously because the resonance current has no place to flow.

Accordingly, the third and fourth MOSFETs 730 to 740 may be turned on and off twice by a comparator in one cycle. If the offset is determined before the third and fourth MOSFETs 730 to 740 are turned off using the resonance current characteristic, the ZCS point can be determined.

According to an embodiment of the present invention, the first ZVS & ZCS control unit 751-1 and the second ZVS & ZCS control unit 751-2 each include a ZVS control circuit and a ZCS control circuit, and ZVS through the ZVS control circuit. Control may be performed, and ZCS control may be performed through the ZCS control circuit.

11 is a view for explaining a ZCS control circuit according to an embodiment of the present invention. 11 shows a ZCS control circuit included in the second ZVS & ZCS control unit 751-2 for controlling the off of the fourth MOSFET 740.

Referring to FIG. 11, the ZCS control circuit 1100 may include a comparator 1110, a Slow Turn off Detector block 1120, and a CMP (Comparator) Rising Detector Block 1130.

The comparator 1110 may output a driving signal for turning off the fourth MOSFET 740. The Slow Turn off Detector block 1120 may detect that the off of the fourth MOSFET 740 is delayed. The CMP (Comparator) Rising Detector Block 1130 may determine whether the comparator 1110 is turned on and off twice in one cycle.

Using the information that the off of the fourth MOSFET 740 is delayed from the Slow Turn off Detector block 1120 and the Comparator (CMP) Rising Detector Block 1130 and whether the comparator 1110 is turned on and off twice per cycle. The offset of the comparator 1110 can be adjusted. The offset of the comparator 1110 may be adjusted by a charge pump.

For example, when the off of the fourth MOSFET 740 is delayed, a voltage may be applied to the offset capacitor using a charge pump. When voltage is applied to the offset capacitor, the comparator 1110 may gradually turn off the fourth MOSFET 740. However, if the fourth MOSFET 740 is turned off before the ZCS point, the fourth MOSFET 740 is turned off again by the comparator 1110 and the fourth MOSFET 740 is turned on twice in one cycle. Comparator) This is detected by the Rising Detector Block 1130 to reduce the voltage on the offset capacitor so that the comparator 1110 operates at the ZCS point.

In the above description, the ZCS control circuit included in the second ZVS & ZCS control unit 751-2 for controlling the off of the fourth MOSFET 740 was described, but the ZCS control circuit for controlling the off of the third MOSFET 730 is described. It is obvious that the ZCS control circuit included in the 1 ZVS & ZCS control unit 751-1 can operate on the same principle.

Meanwhile, when the ZVS control circuit is described, FIG. 12 is a view for explaining the ZVS control circuit according to an embodiment of the present invention. FIG. 12 shows a ZVS control circuit included in the second ZVS & ZCS control unit 751-2 for controlling the on of the fourth MOSFET 740.

Referring to FIG. 12, the ZVS control circuit 1200 is connected between the second bootstrap diode 753-2 and the fourth limiter 742 and uses a difference between the bootstrap voltage and the fourth limiter 742 voltage. A signal for turning on the fourth MOSFET 740 may be output.

For example, when the resonant current is input, the bootstrap voltage may rise together with the input voltage. At this time, a difference between the fourth limiter 742 voltage and the bootstrap voltage may occur instantaneously. Accordingly, the fourth MOSFET 740 can be turned on more quickly than the comparator 1110 through the ZVS control circuit 1200 as shown in FIG. 12, so that the probability of turning on the fourth MOSFET 740 at the ZVS point Can increase.

In the above description, the ZVS control circuit included in the second ZVS & ZCS control unit 751-2 for controlling the off of the fourth MOSFET 740 was described, but the ZVS control circuit included in the third MOSFET 730 is controlled. It is obvious that the ZVS control circuit included in the 1 ZVS & ZCS control unit 751-1 can operate on the same principle.

According to the embodiments of the present invention as described above, the active rectifier controls the switch on and off through ZVS and ZCS control, thereby enabling stable switching even at a high 6.78 MHz frequency, thereby improving rectification efficiency and reducing switching loss. It works. In addition, according to various embodiments of the present invention, since an active rectifier having a high input voltage and a high frequency operating frequency can be provided, it is possible to develop a one-chip power conversion IC with a simple structure compared to an existing structure. Cost reduction and volume reduction effect can be obtained.

In the above, preferred embodiments of the present invention have been illustrated and described, but any person having ordinary knowledge in the technical field to which the present invention belongs, preferred embodiments of the present invention within the scope not departing from the technical spirit and scope of the present invention It goes without saying that the examples can be varied. Therefore, the present invention may be implemented in various modifications without departing from the gist of the present invention as claimed in the claims, and these modifications should not be individually understood from the technical spirit or prospect of the present invention.

Claims (14)

In the active rectifier,
Switching operation according to the input voltage from the power receiver and the first to fourth MOSFETs connected in a cross-coupled structure,
And a ZVS&ZCS controller that controls each of the third and fourth MOSFETs to perform zero voltage switching (ZVC) or zero current switching (ZCS),
The ZVS & ZCS controller,
First and second ZVS&ZCS control units for controlling zero voltage switching (ZVC) and zero current switching (ZCS) for each of the third and fourth MOSFETs;
And first and second bootstrap diodes that jump and output a voltage of a gate driving signal for driving each of the third MOSFET and the fourth MOSFET to a voltage higher than an input voltage by using bootstrap capacitance. Active rectifier.
According to claim 1,
The first to fourth MOSFETs are active rectifiers, characterized in that N-channel LDMOS.
According to claim 1,
And first and second limiters for limiting the gate voltages of the first MOSFET and the second MOSFET, respectively.
According to claim 1,
And a third and fourth limiter for limiting the gate voltage of each of the third MOSFET and the fourth MOSFET.
delete According to claim 1,
The first ZVS&ZCS control unit includes a ZVC circuit that performs the zero voltage switching (ZVC) and a ZCS circuit that controls the zero current switching (ZCS),
The ZVC circuit is connected between the first bootstrap diode and the third limiter, and outputs a signal for turning on the third MOSFET using a difference between the bootstrap voltage and the limiter voltage,
The ZCS circuit is a comparator that outputs a driving signal for turning off the third MOSFET,
Slow Turn off Detector block for detecting that the off of the third MOSFET is delayed,
Comparator (CMP) Rising Detector block to determine whether the third MOSFET is turned on and off twice in one cycle,
And a charge pump that adjusts the offset of the comparator using information from the Slow Turn off Detector block and the CMP (Comparator) Rising Detector block.
According to claim 1,
The second ZVS&ZCS control unit includes a ZVC circuit that performs the zero voltage switching (ZVC) and a ZCS circuit that controls the zero current switching (ZCS),
The ZVC circuit is connected between the second bootstrap diode and the fourth limiter, and outputs a signal for turning on the fourth MOSFET using a difference between the bootstrap voltage and the limiter voltage,
The ZCS circuit is a comparator outputting a driving signal for turning off the fourth MOSFET,
Slow Turn off Detector block for detecting that the off of the fourth MOSFET is delayed,
Comparator (CMP) Rising Detector block to determine whether the fourth MOSFET is turned on and off twice in one cycle,
And a charge pump that adjusts the offset of the comparator using information from the Slow Turn off Detector block and the CMP (Comparator) Rising Detector block.
In the wireless power receiver,
Power receiving unit for receiving wireless power,
Switching operation is performed according to the input voltage by the received power and each of the first to fourth MOSFETs connected in a cross-coupled structure, and the third MOSFET and the fourth MOSFET is zero voltage switching (ZVC) Or an active rectifier comprising a ZVS&ZCS controller for controlling to perform zero current switching (ZCS) and rectifying the received power,
It includes a DC converter for DC-DC conversion of the rectified power,
The ZVS & ZCS controller,
First and second ZVS&ZCS control units for controlling zero voltage switching (ZVC) and zero current switching (ZCS) for each of the third and fourth MOSFETs;
And first and second bootstrap diodes that jump and output a voltage of a gate driving signal for driving each of the third MOSFET and the fourth MOSFET to a voltage higher than an input voltage by using bootstrap capacitance. Wireless power receiver.
The method of claim 8,
The first to fourth MOSFET is a wireless power receiver, characterized in that the N-channel LDMOS.
The method of claim 8,
And first and second limiters for limiting the gate voltage of each of the first MOSFET and the second MOSFET.
The method of claim 8,
And a third and a fourth limiter for limiting the gate voltage of each of the third MOSFET and the fourth MOSFET.
delete The method of claim 8,
The first ZVS&ZCS control unit includes a ZVC circuit that performs the zero voltage switching (ZVC) and a ZCS circuit that controls the zero current switching (ZCS),
The ZVC circuit is connected between the first bootstrap diode and the third limiter, and outputs a signal for turning on the third MOSFET using a difference between the bootstrap voltage and the limiter voltage,
The ZCS circuit is a comparator outputting a driving signal for turning off the third MOSFET,
Slow Turn off Detector block for detecting that the off of the third MOSFET is delayed,
Comparator (CMP) Rising Detector block to determine whether the third MOSFET is turned on and off twice in one cycle,
And a charge pump for adjusting the offset of the comparator using information from the Slow Turn off Detector block and the CMP (Comparator) Rising Detector block.
The method of claim 8,
The second ZVS&ZCS control unit includes a ZVC circuit that performs the zero voltage switching (ZVC) and a ZCS circuit that controls the zero current switching (ZCS),
The ZVC circuit is connected between the second bootstrap diode and the fourth limiter, and outputs a signal for turning on the fourth MOSFET using a difference between the bootstrap voltage and the limiter voltage,
The ZCS circuit is a comparator that outputs a driving signal for turning off the fourth MOSFET,
Slow Turn off Detector block for detecting that the off of the fourth MOSFET is delayed,
Comparator (CMP) Rising Detector block to determine whether the fourth MOSFET is turned on and off twice in one cycle,
And a charge pump for adjusting the offset of the comparator using information from the Slow Turn off Detector block and the CMP (Comparator) Rising Detector block.

Images