US-12627176-B2 - Dual-mode multi-coil wireless power transfer system

US12627176B2US 12627176 B2US12627176 B2US 12627176B2US-12627176-B2

Abstract

A dual-mode multi-coil wireless power transfer system includes a control unit and a transmitter unit. The transmitter unit may wirelessly transmit electric power to an external receiver coil. The transmitter unit include a plurality of transmitter modules. Each of the plurality of transmitter modules may operate in at least one of a power transfer mode and a leakage magnetic field shield mode. The control unit controls each of the plurality of transmitter modules to operate in at least one of the power transfer mode and the leakage magnetic field shield mode or to be turned off.

Inventors

Seungyong AHN
Semin CHOI
Sungryul HUH
Haerim KIM
Seongho WOO

Assignees

KOREA ADVANCED INSTITUTE OF SCIENCE AND TECHNOLOGY

Dates

Publication Date: 20260512
Application Date: 20231114
Priority Date: 20221212

Claims (12)

1 . A dual-mode multi-coil wireless power transfer system, comprising: a transmitter unit configured to wirelessly transmit electric power to an external receiver coil and comprising a plurality of transmitter modules, each of the plurality of transmitter modules configured to operate in at least one of a power transfer mode and a leakage magnetic field shield mode; a control unit configured to control each of the plurality of transmitter modules to operate in at least one of the power transfer mode and the leakage magnetic field shield mode or turned off; and an inverter configured to convert direct current power to alternating current power; wherein when a first transmitter module of the plurality of transmitter modules operates in the power transfer mode and a second transmitter module of the plurality of transmitter modules operates in the leakage magnetic field shield mode, the second transmitter module uses an electromotive force induced by a leakage magnetic field generated by the first transmitter module to generate a magnetic field offsetting the leakage magnetic field, wherein each of the plurality of transmitter modules comprises a transmitter coil, and wherein a third transmitter coil of a third transmitter module of the plurality of transmitter modules and a fourth transmitter coil of a fourth transmitter module of the plurality of transmitter modules are disposed to at least partially overlap with each other, wherein each of the plurality of transmitter modules further comprises a first input terminal, a second input terminal and a resonance tank, wherein the first input terminal and the second input terminal are connected to the inverter, and wherein the resonance tank comprises: a series resonance coil, one end of the series resonance coil being connected to the first input terminal; a variable capacitor, one end of the variable capacitor being connected to the other end of the series resonance coil, the other end of the variable capacitor being connected to one end of the transmitter coil; and a parallel resonance capacitor, one end of the parallel resonance capacitor being connected to the other end of the series resonance coil and the one end of the variable capacitor, the other end of the parallel resonance capacitor being connected to the second input terminal, wherein the control unit is configured to compute transmitter-receiver coils coupling coefficients, the transmitter-receiver coils coupling coefficients being coupling coefficients between transmitter coils of the plurality of transmitter modules and the receiver coil, and transmitter-transmitter coils coupling coefficients, the transmitter-transmitter coils coupling coefficients being coupling coefficients between the transmitter coils, and to control each of the plurality of transmitter modules to operate in at least one of the power transfer mode and the leakage magnetic field shield mode or turned off based on the transmitter-receiver coils coupling coefficients and the transmitter-transmitter coils coupling coefficients, wherein a value obtained by multiplying √{square root over (2)}−1 with a largest value of the transmitter-receiver coils coupling coefficients is defined as a first value, and if a coupling coefficient between a fifth transmitter coil of a fifth transmitter module of the plurality of transmitter modules and the receiver coil is greater than or equal to the first value, the fifth transmitter module is operated in the power transfer mode, and if the coupling coefficient between the fifth transmitter coil of the fifth transmitter module of the plurality of transmitter modules and the receiver coil is smaller than the first value, the fifth transmitter module is operated in the leakage magnetic field shield mode or turned off.
2 . The dual-mode multi-coil wireless power transfer system as set forth in claim 1 , wherein the control unit is configured to adjust a capacitance of the variable capacitor, wherein the variable capacitor has a first capacitance when the respective transmitter module operates in the power transfer mode, and wherein the variable capacitor has a second capacitance when the respective transmitter module operates in the leakage magnetic field shield mode, the second capacitance being different from the first capacitance.
3 . The dual-mode multi-coil wireless power transfer system as set forth in claim 2 , wherein the second capacitance is smaller than the first capacitance.
4 . The dual-mode multi-coil wireless power transfer system as set forth in claim 1 , wherein when a sixth transmitter module of the plurality of transmitter modules does not operate in the power transfer mode and the fifth transmitter module is operated in the power transfer mode, the sixth transmitter module is operated in the leakage magnetic field shield mode if a coupling coefficient between the fifth transmitter coil and a sixth transmitter coil of the sixth transmitter module is greater than or equal to a second value, and the sixth transmitter module is turned off if the coupling coefficient between the fifth transmitter coil and the sixth transmitter coil of the sixth transmitter module is smaller than the second value.
5 . The dual-mode multi-coil wireless power transfer system as set forth in claim 4 , wherein the second value is 0.
6 . The dual-mode multi-coil wireless power transfer system as set forth in claim 2 , wherein each of the plurality of transmitter modules is operated in at least one of the power transfer mode and the leakage magnetic field shield mode or turned off, based on distances between centers of the transmitter coils of the plurality of transmitter modules and a center of the receiver coil.
7 . A dual-mode multi-coil wireless power transfer system, comprising: a transmitter unit configured to wirelessly transmit electric power to an external receiver coil and comprising a plurality of transmitter modules, each of the plurality of transmitter modules comprising a transmitter coil and a variable capacitor; a control unit configured to adjust a capacitance value, wherein each of the plurality of transmitter modules is operated in at least one of a power transfer mode and a leakage magnetic field shield mode or turned off, and wherein the power transfer mode and the leakage magnetic field shield mode are determined based on the capacitance value of the variable capacitor; and an inverter configured to convert direct current power to alternating current power, wherein when a first transmitter module of the plurality of transmitter modules operates in the power transfer mode and a second transmitter module of the plurality of transmitter modules operates in the leakage magnetic field shield mode, the second transmitter module uses an electromotive force induced by a leakage magnetic field generated by the first transmitter module to generate a magnetic field offsetting the leakage magnetic field, wherein each of the plurality of transmitter modules comprises a transmitter coil, and wherein a third transmitter coil of a third transmitter module of the plurality of transmitter modules and a fourth transmitter coil of a fourth transmitter module of the plurality of transmitter modules at least partially overlap with each other, wherein each of the plurality of transmitter modules further comprises a first input terminal, a second input terminal, a series resonance coil and a parallel resonance capacitor, and wherein the first input terminal and the second input terminal are connected to the inverter, and one end of the series resonance coil is connected to the first input terminal, and one end of the variable capacitor is connected to the other end of the series resonance coil, and the other end of the variable capacitor is connected to one end of the transmitter coil, and one end of the parallel resonance capacitor is connected to the other end of the series resonance coil and the one end of the variable capacitor, and the other end of the parallel resonance capacitor is connected to the second input terminal, wherein the control unit is configured to compute transmitter-receiver coils coupling coefficients, the transmitter-receiver coils coupling coefficients being coupling coefficients between transmitter coils of the plurality of transmitter modules and the receiver coil, and transmitter-transmitter coils coupling coefficients, the transmitter-transmitter coils coupling coefficients being coupling coefficients between the transmitter coils, and to control each of the plurality of transmitter modules to operate in at least one of the power transfer mode and the leakage magnetic field shield mode or turned off based on the transmitter-receiver coils coupling coefficients and the transmitter-transmitter coils coupling coefficients, wherein a value obtained by multiplying √{square root over (2)}−1 with a largest value of the transmitter-receiver coils coupling coefficients is defined as a first value, and if a coupling coefficient between a fifth transmitter coil of a fifth transmitter module of the plurality of transmitter modules and the receiver coil is greater than or equal to the first value, the fifth transmitter module is operated in the power transfer mode, and if the coupling coefficient between the fifth transmitter coil of the fifth transmitter module of the plurality of transmitter modules and the receiver coil is smaller than the first value, the fifth transmitter module is operated in the leakage magnetic field shield mode or turned off.
8 . The dual-mode multi-coil wireless power transfer system as set forth in claim 7 , wherein the variable capacitor has a first capacitance when the respective transmitter module operates in the power transfer mode, and wherein the variable capacitor has a second capacitance when the respective transmitter module operates in the leakage magnetic field shield mode, the second capacitance being different from the first capacitance.
9 . The dual-mode multi-coil wireless power transfer system as set forth in claim 8 , wherein the second capacitance is smaller than the first capacitance.
10 . The dual-mode multi-coil wireless power transfer system as set forth in claim 7 , wherein when a sixth transmitter module of the plurality of transmitter modules does not operate in the power transfer mode and the fifth transmitter module is operated in the power transfer mode, the sixth transmitter module is operated in the leakage magnetic field shield mode if a coupling coefficient between the fifth transmitter coil and a sixth transmitter coil of the sixth transmitter module is greater than or equal to a second value, and the sixth transmitter module is turned off if the coupling coefficient between the fifth transmitter coil and the sixth transmitter coil of the sixth transmitter module is smaller than the second value.
11 . The dual-mode multi-coil wireless power transfer system as set forth in claim 10 , wherein the second value is 0.
12 . The dual-mode multi-coil wireless power transfer system as set forth in claim 8 , wherein each of the plurality of transmitter modules is operated in at least one of the power transfer mode and the leakage magnetic field shield mode or turned off, based on distances between centers of the transmitter coils of the plurality of transmitter modules and a center of the receiver coil.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Korean Patent Application No. 10-2022-0172961, filed with the Korean Intellectual Property Office on Dec. 12, 2022, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a wireless power transfer system that is capable of transmitting electric power wirelessly. Specifically, the present disclosure relates to a wireless power transfer system in which a single transmitter module can simultaneously operate in dual modes (i.e., power transfer mode and leakage magnetic field shield mode). BACKGROUND Wireless power transfer (WPT) is widely used in a variety of fields including, for example, small electronic devices, such as smartphones and smart watches, and medical apparatuses. Particularly, studies are underway to apply the wireless power transfer technologies to drones, electric vehicles, railroads, etc., where large electric powers are required. Generally, electric power is wirelessly transferred via electromagnetic induction between transmitter coils and receiver coils, and the efficiency of power transfer is determined by mutual inductance between the transmitter coils and the receiver coils. The mutual inductance is determined by relative arrangement between the transmitter coils and the receiver coils. Accordingly, the power transfer efficiency has been compromised when there is a misalignment between the transmitter coils and the receiver coils. To address this issue, the multi coil wireless power transfer system has been introduced to attain a sufficient mutual inductance by providing multiple transmitter coils on a 2-dimensional plane. Despite the multi coil wireless power transfer system, some of the magnetic field generated by the transmitter coils have still been leaked. The leakage magnetic field have adverse effects on humans and surrounding electric devices. As such, there have been increased demands for possible solutions for removing the leakage magnetic field generated by the multi coil wireless power transfer system. SUMMARY To address the above-mentioned issues, the present disclosure enables a single transmitter coil to operate in dual modes (i.e., power transfer mode and leakage magnetic field shield mode), thereby providing a dual-mode multi-coil wireless power transfer system that can reduce the leakage magnetic field without introducing a separate shield coil. The present disclosure also enables the transmitter coil operating in the leakage magnetic field shield mode to use an electromotive force induced by the leakage magnetic field, thereby providing a dual-mode multi-coil wireless power transfer system that can reduce the leakage magnetic field without introducing a separate power source. The present disclosure provides a dual-mode multi-coil wireless power transfer system in which the operating mode of the transmitter coil is flexibly determined based on the coefficient of coupling with other transmitter coils. The dual-mode multi-coil wireless power transfer system in accordance with an embodiment of the present disclosure may include a transmitter unit and a control unit. The transmitter unit may wirelessly transmit electric power to an external receiver coil. The transmitter unit may include a plurality of transmitter modules, each of the plurality of transmitter modules being operable in at least one of a power transfer mode and a leakage magnetic field shield mode. The control unit may control each of the plurality of transmitter modules to operate in at least one of the power transfer mode and the leakage magnetic field shield mode or to be turned off. When a first transmitter module of the plurality of transmitter modules operates in the power transfer mode and a second transmitter module of the plurality of transmitter modules operates in the leakage magnetic field shield mode, the second transmitter module may use an electromotive force induced by the leakage magnetic field generated by the first transmitter module to generate a magnetic field that offsets the leakage magnetic field. In the dual-mode multi-coil wireless power transfer system in accordance with an embodiment of the present disclosure, each of the plurality of transmitter modules may include a transmitter coil. A third transmitter coil of a third transmitter module of the plurality of transmitter modules and a fourth transmitter coil of a fourth transmitter module of the plurality of transmitter modules may at least partially overlap with each other. The dual-mode multi-coil wireless power transfer system in accordance with an embodiment of the present disclosure may further include an inverter. The inverter may convert direct current power source to alternating current power source. Each of the plurality of transmitter modules may further include a first input terminal, a second input terminal and a resonance tank. The first input terminal and the second inpu