Wireless power transmitter and method for controlling the same

A wireless power transmitter includes a common bridge circuit configured to apply a first alternating current (AC) voltage to a terminal of each of a first resonator and a second resonator of the resonators, a first sub-bridge circuit configured to apply a second alternating current (AC) voltage to another terminal of the first resonator while the first alternating current (AC) voltage is being applied to the terminal of the first resonator, and a second sub-bridge circuit configured to apply a third alternating current (AC) voltage to another terminal of the second resonator while the first alternating current (AC) voltage is being applied to the terminal of the first resonator.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit under 35 USC § 119(a) of priority to Korean Patent Application Nos. 10-2016-0031162 filed on Mar. 15, 2016 and 10-2016-0069301 filed on Jun. 3, 2016 in the Korean Intellectual Property Office, the entire disclosures of which are incorporated herein by reference for all purposes.

BACKGROUND

The following description relates to a wireless power transmitter and a method for controlling the same.

2. Description of Related Art

With the development of wireless technology, various wireless functions, ranging from the transmission of data to the transmission of power, have increased. Wireless power charging technology that is able to charge an electronic device with power, even in a non-contact state has been developed.

In wireless charging, a resonance coil of a wireless power transmitter and a receiving coil of a wireless power receiver are positioned to correspond to each other. Therefore, some wireless power transmitter provides a wider chargeable area by providing a plurality of resonance coils.

SUMMARY

In one general aspect, there is provided a wireless power transmitter capable of removing mutual interference between a plurality of resonance coils, and a method for controlling the same.

In another general aspect, there is provided a wireless power transmitter including resonators transmitting power in a non-contact manner, a common bridge circuit configured to apply a first alternating current (AC) voltage to a terminal of each of a first resonator and a second resonator of the resonators, a first sub-bridge circuit configured to apply a second alternating current (AC) voltage to another terminal of the first resonator while the first alternating current (AC) voltage is being applied to the terminal of the first resonator, and a second sub-bridge circuit configured to apply a third alternating current (AC) voltage to another terminal of the second resonator while the first alternating current (AC) voltage is being applied to the terminal of the first resonator.

The voltage across the second resonator may be maintained to have substantially a same potential while the first alternating current (AC) voltage is applied to the terminal of the first resonator.

The first resonator and the second resonator may include a resonance coil and a resonance capacitor.

The resonance coils of the first resonator and the second resonator may overlap with each other.

The second alternating current (AC) voltage may have a phase difference of 180° with the first alternating current (AC) voltage.

An alternating current (AC) may be provided to the first resonator while the first alternating current (AC) voltage is applied to one terminal of the first resonator.

The first sub-bridge circuit and the common bridge circuit may operate together as a full-bridge circuit.

In another general aspect, there is provided a method for driving a wireless power transmitter wirelessly transmitting power in a non-contact manner, the method including controlling a common bridge circuit to apply a first alternating current (AC) voltage to a terminal of each of a first resonator and a second resonator, controlling a first sub-bridge circuit to apply a second alternating current (AC) voltage to another terminal of the first resonator while the first alternating current (AC) voltage is being applied, and controlling a second sub-bridge circuit to apply a third alternating current (AC) voltage to another terminal of the second resonator by while the first alternating current (AC) voltage is being applied.

The controlling of the second sub-bridge circuit may include controlling a voltage across the second resonator to have substantially a same potential while an alternating current (AC) is provided to the first resonator.

The third alternating current (AC) voltage may have a same phase as the first alternating current (AC) voltage.

The first sub-bridge circuit and the common bridge circuit may be operated together as a full-bridge circuit.

In another general aspect, there is provided a wireless power transmitter including a common bridge circuit including a first switch connected between a terminal of each of a first resonator and a second resonator and a power source, and a second switch connected between the terminal of each of the first resonator and the second resonator and a ground, a first sub-bridge circuit including a third switch connected between another terminal of the first resonator and the power source, and a fourth switch connected between the another terminal of the first resonator and the ground, and a second sub-bridge circuit including a fifth switch connected between another terminal of the second resonator and the power source, and a sixth switch connected between the another terminal of the second resonator and the ground, wherein the first switch and the second switch are alternately operated to apply a first alternating current (AC) voltage to the terminal of each of the first and the second resonators, wherein the third switch and the fourth switch are alternately operated to apply a second alternating current (AC) voltage to the another terminal of the first resonator, and wherein the fifth switch and the sixth switch are alternately operated to be the same as the first switch and the second switch.

A voltage across the second resonator may be maintained to have substantially the same potential while the first alternating current (AC) voltage is applied to the terminal of the first resonator.

The first resonator and the second resonator may include a resonance coil and a resonance capacitor.

The resonance coils of the first resonator and the second resonator may overlap with each other.

The third switch may perform the same switching operation as the second switch, and the fourth switch may perform the same switching operation as the first switch.

In another general aspect, there is provided a wireless power transmitter including a controller configured to control an inverter, resonators configured to transmit power, the inverter including a common bridge circuit and a plurality of sub-bridge circuits corresponding to a number of the resonators, wherein the common bridge circuit is connected to a first terminal of each of a first resonator and a second resonator among the resonators, a first sub-bridge circuit of the plurality of sub-bridge circuits is connected to a second terminal of the first resonator, a second sub-bridge circuit of the plurality of sub-bridge circuits is connected to a second terminal of the second resonator, and wherein the controller is configured to control the second sub-bridge circuit to perform the same switching operation as the common bridge circuit, in response to the first resonator being operated.

The controller may be configured to operate the first sub-bridge circuit and the common bridge circuit as a full-bridge circuit.

The common bridge circuit may be configured to apply a first alternating current (AC) voltage to the first terminal of each of the first resonator and the second resonator, the first sub-bridge circuit may be configured to apply a second AC voltage to the second terminal of the first resonator while the first AC voltage is being applied, and the second sub-bridge circuit may be configured to apply a third AC voltage to the second terminal of the second resonator while the first AC voltage is being applied.

The resonators may include a resonance coil and a resonance capacitor disposed on a ferrite sheet.

DETAILED DESCRIPTION

FIG. 1is a diagram illustrating an example of a wireless power transmitter included in a wireless power transmission apparatus.

Referring toFIG. 1, a wireless power receiver200is situated adjacent to a wireless power transmitter100. The wireless power receiver200receives wirelessly power by being magnetically coupled (e.g., to magnetically resonate with or to be magnetically induced by) to the wireless power transmitter100.

The wireless power receiver200provides the received power to an electronic device300. In an example, the wireless power receiver200exists as a component within the electronic device300. In another example, the wireless power receiver200is a separate device, connected to the electronic device300.

As a non-exhaustive illustration only, the wireless power receiver200and the wireless power transmitter100described herein may be incorporated in digital devices such as, for example, a mobile phone, a cellular phone, a smart phone, a wearable smart device (such as, for example, a ring, a watch, a pair of glasses, glasses-type device, a bracelet, an ankle bracket, a belt, a necklace, an earring, a headband, a helmet, a device embedded in the cloths), a personal computer (PC), a laptop, a notebook, a subnotebook, a netbook, or an ultra-mobile PC (UMPC), a tablet personal computer (tablet), a phablet, a mobile internet device (MID), a personal digital assistant (PDA), an enterprise digital assistant (EDA), a digital camera, a digital video camera, a portable game console, an MP3 player, a portable/personal multimedia player (PMP), a handheld e-book, an ultra mobile personal computer (UMPC), a portable lab-top PC, a global positioning system (GPS) navigation, a personal navigation device or portable navigation device (PND), a handheld game console, an e-book, and devices such as a high definition television (HDTV), an optical disc player, a DVD player, a Blue-ray player, video game consoles, television set-top boxes, e-book readers, a setup box, television set-top boxes, e-book readers, robot cleaners, a home appliance, content players, communication systems, image processing systems, graphics processing systems, or any other consumer electronics/information technology (CE/IT) device consistent with that disclosed herein. The wireless power receiver200and the wireless power transmitter100may also be implemented in a smart appliance, an intelligent vehicle, or in a smart home system.

In an example, wireless power receiver200and the wireless power transmitter100is implemented in a wearable device, which is worn on a body of a user. In one example, a wearable device may be self-mountable on the body of the user, such as, for example, a watch, a bracelet, or as an eye glass display (EGD), which includes one-eyed glass or two-eyed glasses. In another example, the wearable device may be embedded in one or more apparel or footwear worn by the user.

Although the wireless power receiver200and the wireless power transmitter100are partially spaced apart from each other in the illustrated example, this is merely illustrative. The wireless power receiver200and the wireless power transmitter100may be in contact with each other or may be adjacent to each other without departing from the spirit and scope of the illustrative examples described.

In an example, the wireless power transmitter100includes a plurality of resonance coils. The wireless power receiver200may be magnetically coupled to the wireless power transmitter100in any position on the wireless power transmitter100.

To reduce mutual influence between the plurality of resonance coils, the wireless power transmitter100may perform a control so that voltages across resonators that are not being operated have substantially the same potential.

The wireless power transmitter100will be described below in more detail with reference toFIGS. 2 through 8.

FIG. 2is a diagram illustrating an example of the wireless power transmitter.

Referring toFIG. 2, the wireless power transmitter100includes an inverter120, a resonance unit130, and a controller140. According to an embodiment, the wireless power transmitter100may further include a power supply unit110.

The power supply unit110generates a predetermined level of direct current (DC) voltage using power input from outside. In an example, the power supply unit110is configured as a device independent of the wireless power transmitter100. For example, the power supply unit110may be an adapter device that receives a commercial alternating current (AC) voltage and outputs a predetermined level of voltage (e.g., a voltage of 5V).

In an example, the inverter120receives the DC voltage and perform a switching operation according to a control of the controller140to provide an alternating current (AC) to the resonance unit130.

According to an embodiment, the inverter120includes one common bridge circuit, and a plurality of sub-bridge circuits each corresponding to a plurality of resonators of the resonance unit130.

In an example, the resonance unit130operates by receiving the alternating current (AC) from the inverter120.

In an example, the resonance unit130includes a plurality of resonators. In an example, each resonator includes a resonance coil and a resonance capacitor.

In an example, the controller140controls the switching operation of the inverter120.

To reduce mutual influence between the plurality of resonance coils, the controller140may perform a control so that voltages across resonators that are not being operated have the same potential.

The controller140may support various switching control methods, such as, for example, adjusting the alternating current (AC) by changing a pulse width, or adjusting the alternating current (AC) by changing a frequency.

In an example, the controller140may include at least one processing unit. According to an embodiment, the controller140may further include a memory, which is described below. The processing unit may have a plurality of cores and may include, for example, a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, an application specific integrated circuit (ASIC), field programmable gate arrays (FPGA), or the hardware components described below.

FIG. 3is a diagram illustrating an example of a resonance coil of the resonance unit.FIG. 3illustrates an example in which the resonance unit includes two resonance coils. The number of resonance coils in the resonance units may be varied without departing from the spirit and scope of the illustrative examples described.

Referring toFIG. 3, in an example, the resonance unit130includes a first resonance coil321and a second resonance coil322. In an example, the resonance unit130includes a ferrite sheet310attached to rear surfaces of the first resonance coil321and the second resonance coil322.

The first resonance coil321and the second resonance coil322may overlap with each other in at least some regions. By disposing the first resonance coil321and the second resonance coil322to be overlapped with each other, a depletion region in which power does not arrive wirelessly is reduced, and a wider wireless chargeable area with the wireless power receiver is provided.

FIG. 4is a diagram illustrating an example of the resonance coil of the resonance unit.FIG. 4illustrates an example in which the resonance unit includes three resonance coils. The number of resonance coils in the resonance units may be varied without departing from the spirit and scope of the illustrative examples described.

Referring toFIG. 4, in an example, the resonance unit131includes a first resonance coil421, a second resonance coil422, and a third resonance coil423. In an example, the resonance unit131includes a ferrite sheet410attached to rear surfaces of the first resonance coil421to the third resonance coil423.

The first resonance coil421to the third resonance coil423may overlap with each other in at least some regions. For example, the first resonance coil421and the second resonance coil422may be overlapped with each other, and the second resonance coil422and the third resonance coil423may be overlapped with each other. By disposing a plurality of coils to be partially overlapped with each other, a depletion region in which the power does not arrive wirelessly is reduced, and a wireless chargeable area using the wireless power receiver is expanded.

FIG. 5is a diagram illustrating an example of an inverter illustrated inFIG. 2. The example illustrated inFIG. 5illustrates an inverter driving the resonance unit including two resonators.

Referring toFIG. 5, the inverter may include a common bridge circuit521, and a plurality of sub-bridge circuits522and523. The controller may control the switches of the inverter.

The common bridge circuit521may be operated even when a resonance coil of the resonance unit is operated. The plurality of sub-bridge circuits522and523may be operated to correspond to the plurality of resonators, respectively.

In an example when a first resonator531is operated to wirelessly transmit power, the common bridge circuit521may be connected to one terminal of each of the first resonator531and a second resonator532to apply an alternating current (AC) voltage.

In an example, the common bridge circuit521and a first sub-bridge circuit522may alternately perform a switching operation. The common bridge circuit521and the first sub-bridge circuit522may be operated as a single full-bridge circuit, and DC power provided from a power supply unit510according to the switching operation may be converted into an alternating current (AC) to be provided to the first resonator531.

When the second resonator532is operated to wirelessly transmit power, the common bridge circuit521and a second sub-bridge circuit523may alternately perform the switching operation. The common bridge circuit521and the second sub-bridge circuit523may be operated as a single full-bridge circuit.

Hereinafter, a resonator radiating a magnetic field to wirelessly transmit the power will be described as an operated resonator.

FIG. 6is a diagram illustrating an operation of the inverter illustrated inFIG. 5.

The circuit diagram illustrated inFIG. 6illustrates an example of a switching operation when an operated resonator is a first resonator631and DC power is provided from a power supply unit610. However, this case is taken for convenience of explanation, and one or more of the plurality of resonators may be selectively or simultaneously operated to wirelessly transmit the power as described above. In a case in which the first resonator631is not operated and a second resonator632is operated, an operation related to the first resonator631described below may be applied based on the second resonator632. This may be equally applied to a case in which some the resonators are operated and the remaining resonators are not operated.

To operate the first resonator631, a common bridge circuit621and a first sub-bridge circuit622may be operated as a full-bridge circuit. A fourth switch Q4and a first switch Q1may be in a turned-on state, and a third switch Q3and a second switch Q2may be in a turned-off state. In this configuration, a current may flows from a first node N1, a right node of the first resonator631, to a second node N2, a left node of the first resonator631.

In another example, in a subsequent alternating switching operation, the fourth switch Q4and the first switch Q1may be changed to the turned-off state, and the third switch Q3and the second switch Q2may be changed to the turned-on state. In this configuration, the current flows from the second node N2, the left node of the first resonator631, to the first node N1, the right node of the first resonator631.

An alternating current (AC) flowing in different directions according to a predetermined period of the first resonator631may be provided to the first resonator631by alternately operating switches of the common bridge circuit621and the first sub-bridge circuit622.

According to an embodiment, the first switch Q1and the second switch Q2may be alternately operated at a duty ratio of 50%, and the third switch Q3and the fourth switch Q4may be alternately operated at a duty ratio of 50%. The duty ratio may be changed to improve wireless transmission efficiency without departing from the spirit and scope of the illustrative examples described.

In an example, the common bridge circuit621applies a first alternating current (AC) voltage V1to one terminal of each of the first resonator631and the second resonator632.

While the first alternating current (AC) voltage V1is applied to one terminal of the first resonator631, the first sub-bridge circuit622connected to the other terminal of the first resonator631may apply a second alternating current (AC) voltage V2to the other terminal of the first resonator631, and the second sub-bridge circuit623connected to the other terminal of the second resonator632may apply a third alternating current (AC) voltage V3to the other terminal of the second resonator632.

In an example, the second alternating current (AC) voltage V2may have the same voltage level as the first alternating current (AC) voltage V1, and may have a phase difference of 180° with the first alternating current (AC) voltage V1.

In an example, the third alternating current (AC) voltage V3may have the same voltage level as the first alternating current (AC) voltage V1, and may have the same phase as the first alternating current (AC) voltage V1.

When the first resonator631is operated, the second sub-bridge circuit623may perform the same switching operation as the common bridge circuit621. A fifth switch Q5of the second sub-bridge circuit623may perform the same switching operation as the first switch Q1of the common bridge circuit621, and a sixth switch Q6of the second sub-bridge circuit623may perform the same switching operation as the second switch Q2of the common bridge circuit621.

When the second sub-bridge circuit623performs the same switching operation as the common bridge circuit621, and the third alternating current (AC) voltage V3has the same voltage level as the first alternating current (AC) voltage V1, a voltage of each of the nodes of the second sub-bridge circuit623may be the same as a voltage of each of the nodes of the common bridge circuit621. Accordingly, voltages across the second resonator632may reach the same potential.

By performing a control so that the second sub-bridge circuit623connected to the other terminal of the second resonator632, which is not being operated, performs the same switching operation as the common bridge circuit621, the voltage across the second resonator632intended to suppress the radiation of the magnetic field may be maintained to be the same. Therefore, when the first resonator631is operated, the current may not flow in the second resonator632.

Even when the resonance coils of two resonators overlap with each other, a phenomenon in which magnetic field causes interference by one of the resonance coils not being operated is avoided, by setting the voltage across the resonator not being operated to the same voltage.

FIG. 7is a diagram illustrating another example of the inverter illustrated inFIG. 2. The example illustrated inFIG. 7illustrates an inverter driving the resonance unit including three resonators.

Referring toFIG. 7, the inverter may include a common bridge circuit721, and a plurality of sub-bridge circuits722,723, and724. The controller may control the respective switches of the inverter.

The common bridge circuit721is operated even in a case in which a resonance coil of the resonance unit is operated. The plurality of sub-bridge circuits722,723, and724may be operated to correspond to the plurality of resonators.

When a first resonator731is operated to wirelessly transmit power, the common bridge circuit721and a first sub-bridge circuit722may alternately perform a switching operation. The common bridge circuit721and the first sub-bridge circuit722may be operated as a single full-bridge circuit.

When the second resonator732is operated, the common bridge circuit721and a second sub-bridge circuit723may alternately perform the switching operation. The common bridge circuit721and the second sub-bridge circuit723may be operated as a single full-bridge circuit.

When a third resonator733is operated, the common bridge circuit721and a third sub-bridge circuit724may alternately perform the switching operation. That is, the common bridge circuit721and the third sub-bridge circuit724may be operated as a single full-bridge circuit.

FIG. 8is a diagram illustrating an operation of the inverter illustrated inFIG. 7.

The circuit diagram illustrated inFIG. 8illustrates an example of a switching operation when a resonator operated to radiate a magnetic field to wirelessly transmit power is a second resonator832. However, this case is taken for convenience of explanation, and one or more of the plurality of resonators may be selectively or simultaneously operated to wirelessly transmit the power as described above.

To operate the second resonator832, a common bridge circuit821and a second sub-bridge circuit823may be operated as a full-bridge circuit.

In the illustrated example ofFIG. 8, a first switch Q1and a sixth switch Q6may be in a turned-on state, and a second switch Q2and a fifth switch Q5may be a turned-off state. When the common bridge circuit821and the second sub-bridge circuit823are operated as described above, a current may flow from a first node N1, a left node of the second resonator832, to a third node N3, a right node of the second resonator832.

When the second resonator832is operated, sub-switch circuits which are not associated with the second resonator832, i.e., the first sub-bridge circuit822and a third sub-bridge circuit824may perform the same switching operation as the common bridge circuit821.

As described above, by performing the same switching operation as the common bridge circuit821for the first sub-bridge circuit822and the third sub-bridge circuit824, voltages across the first resonator831and the third resonator833may reach the same potential.

Even when resonance coils of three resonators overlap with each other, a phenomenon in which magnetic field causes interference by the resonance coils Coil1and Coil3, which are not operated, is avoided by setting the voltages across the resonators831and833, which are not operated, to the same voltage.

Hereinafter, the numerical values measured in the example illustrated inFIG. 6will be described with reference toFIGS. 9 through 11.

FIG. 9is a diagram illustrating an example of voltage detected across a first resonator in the example of an operation illustrated inFIG. 6.

Referring toFIGS. 6 and 9, reference numeral910illustrates a voltage of the first node N1, reference numeral920illustrates a voltage of the second node N2, and reference numeral930illustrates a voltage across the first resonator631.

As illustrated, a waveform in which the first resonator631is operated by the full-bridge circuit is illustrated.

FIG. 10is a diagram illustrating an example of voltage detected across a second resonator in the example of an operation illustrated inFIG. 6.

Referring toFIGS. 6 and 10, reference numeral1010illustrates the first alternating current (AC) voltage V1and the third alternating current (AC) voltage V3, which are node voltages across the second resonator632, not being operated. As illustrated, the third alternating current (AC) voltage V3has the same voltage level as the first alternating current (AC) voltage V1, and it may be understood that a voltage across the second resonator632is barely detected, except for some edges, as in reference numeral1020.

Since the voltage across the second resonator632, not being operated, has the same potential, the current may not flow in the second resonator632, not being operated.

FIG. 11is a diagram illustrating an example of a voltage detected across the third resonator detected according to a switching control method of a general full-bridge circuit.

An example illustrated inFIG. 11, a result of a switching topology of the general full-bridge circuit, which does not perform the switching control for the resonator not being operated, is a diagram illustrating a voltage across the resonator not being operated.

Reference numeral1110illustrates a node voltage of a node connected to one terminal of the resonator not being operated, and reference numeral1120illustrates a node voltage of a node connected to the other terminal of the resonator not being operated. Reference numeral1130illustrates a voltage across the resonator not being operated.

As illustrated, when switching is not performed for the resonator not being operated, a low voltage is induced to the resonator not being operated. Accordingly, an influence may occur by the resonator not being operated.

The wireless power transmitter disclosed above may remove the mutual interference between the plurality of resonance coils.