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EP-3924987-B1 - WIRELESS POWER TRANSFER BASED ON MAGNETIC INDUCTION

EP3924987B1EP 3924987 B1EP3924987 B1EP 3924987B1EP-3924987-B1

Inventors

  • NAWAWI, Arie
  • LIM, Ziyou

Dates

Publication Date
20260506
Application Date
20190215

Claims (11)

  1. A coupler (404, 1200) for wireless power transfer, the coupler comprising: a coil configured for wireless power transfer based on magnetic induction, the coil comprising a plurality of coil portions, the plurality of coil portions comprising a first coil portion (408, 1216) and a second coil portion (412, 1214) wound in opposite directions, wherein the first coil portion (408, 1216) is nested within the second coil portion (412, 1214) and defines a first area, the second coil portion (412, 1214) comprises a plurality of second winding loops and defines a second area; the first coil portion (408, 1216) and the second coil portion (412, 1214) are configured that magnetic flux generated based on the first coil portion (408, 1216) flows through the first area and into the second area; the coil is configured as a continuous winding; the first coil portion (408, 1216) is wound in a clockwise direction and the second coil portion (412, 1214) is wound in an anti-clockwise direction, or the second coil portion (412, 1214) is wound in a clockwise direction and the first coil portion (408, 1216)is wound in an anti-clockwise direction; each of the plurality of second winding loops is a complete winding loop; the first coil portion comprises more than one first winding loops, and the plurality of second winding loops are wound in an opposite direction to more than one the first winding loops; wherein the first coil portion (408, 1216) forms magnetic flux for power transfer, and the second coil portion (412, 1214) forms a closed-loop area for forming magnetic flux containing magnetic leakage; a first anti-directional coil section (416, 1212) is formed by the first coil portion (408, 1216) and the second coil portion (412, 1214); characterised in that the coil further comprises one or more additional anti-directional coil sections; the additional anti-directional coil section (516, 1202) comprising a third coil portion (508, 1206) and a fourth coil portion (512, 1204), wherein the third coil portion is nested within the forth coil portion; the first anti-directional coil section (416, 1212) is nested within one or more of the additional anti-directional coil sections (516, 1202).
  2. The coupler (1000) according to claim 1, wherein the coil is configured to have a planar spiral configuration, wherein preferably, the first coil portion (1008) and the second coil portion (1012) are each configured to have a unipolar coil configuration, and the coil has a multi-polar coil configuration.
  3. The coupler (1000) according to any one of claims 1 to 2, wherein the coil forms a first coil cell, and wherein the coupler further comprises one or more additional coil cells connected to the first coil cell, each the additional coil cell comprising a second coil configured for wireless power transfer based on magnetic induction, the second coil comprising a plurality of coil portions comprising a fifth coil portion and a sixth coil portion wound in opposite directions, wherein the fifth coil portion is nested within the sixth coil portion.
  4. The coupler (1000) according to any one of claims 1 to 3, further comprising a resonance capacitor connected to the coil in series or in parallel to form a resonance circuit configured for resonant inductive power transfer, wherein preferably, the coupler (1000) is a transmitter coupler configured to receive a time-varying current from a power source connected thereto for generating a magnetic field to perform wireless power transfer with a receiver coupler over an air gap based on magnetic induction, or wherein preferably, the coupler (1000) is a receiver coupler configured to couple with a magnetic field generated from a transmitter coupler to induce a current in the receiver coupler for supplying power to an electrical load connected to the receiver couple to perform wireless power transfer with the transmitter coupler over an air gap based on magnetic induction.
  5. A system for wireless power transfer comprising: a wireless power transmitter comprising: a power source configured to generate a time-varying current; and a transmitter coupler connected to the power source, wherein the transmitter coupler is configured to receive the time-varying current from the power source for generating a magnetic field to perform wireless power transfer with a receiver coupler over an air gap based on magnetic induction; and a wireless power receiver comprising: an electrical load; and the receiver coupler connected to the electrical load, wherein the receiver coupler is configured to couple with the magnetic field generated from the transmitter coupler to induce a current in the receiver coupler for supplying power to the electrical load connected to the receiver coupler to perform wireless power transfer with the transmitter coupler over the air gap based on magnetic induction, wherein at least one of the receiver coupler and the transmitter coupler is a coupler (1000) according to any one of claims 1 to 3, and the wireless power transmitter and the wireless power receiver are separated by the air gap.
  6. The system according to claim 5, wherein the receiver coupler and the transmitter coupler are each a coupler (1000) according to any one of claims 1 to 3, or wherein one of the receiver coupler and the transmitter coupler is a coupler (1000) according to any one of claims 1 to 3, and the other of the receiver coupler and the transmitter coupler is a coupler configured to have a unipolar configuration.
  7. A method of manufacturing a coupler (404, 1200) for wireless power transfer, the method comprising a plurality of coil portions, the plurality of coil portions comprising a first coil portion and a second coil portion wound in opposite directions, wherein the first coil portion is nested within the second coil portion and defines a first area, the second coil portion comprises a plurality of second winding loops and defines a second area; the first coil portion and the second coil portion are configured that magnetic flux generated based on the first coil portion flows through the first area and into the second area; characterized in that each of the plurality of second winding loops is a complete winding loop; the first coil portion comprises more than one first winding loops, and the plurality of second winding loops are wound in an opposite direction to more than one the first winding loops; wherein the first coil portion forms magnetic flux for power transfer, and the second coil portion forms a closed-loop area for forming magnetic flux containing magnetic leakage; a first anti-directional coil section (416, 1212) is formed by the first coil portion (408, 1216) and the second coil portion (412, 1214); and the coil further comprises one or more additional anti-directional coil sections; the additional anti-directional coil section (516, 1202) comprising a third coil portion (508, 1206) and a fourth coil portion (512, 1204), wherein the third coil portion is nested within the forth coil portion; the first anti-directional coil section (416, 1212) is nested within one or more the additional anti-directional coil section (516, 1202); the coil is configured as a continuous winding; the first coil portion is wound in a clockwise direction and the second coil portion is wound in an anti-clockwise direction, or the second coil portion is wound in a clockwise direction and the first coil portion is wound in an anti-clockwise direction.
  8. The method according to claim 7, wherein the coil is configured to have a planar spiral configuration, wherein preferably, the first coil portion (1008) and the second coil portion (1012) are each configured to have a unipolar coil configuration, and the coil has a multi-polar coil configuration.
  9. The method according to any one of claims 7 to 8, wherein the coil forms a first coil cell, and the method further comprises configuring one or more additional coil cells connected to the first coil cell, each the additional coil cell comprising a second coil configured for wireless power transfer based on magnetic induction, the second coil comprising a plurality of coil portions comprising a fifth coil portion and a sixth coil portion wound in opposite directions, wherein the fifth coil portion is nested within the sixth coil portion.
  10. The method according to any one of claims 7 to 9, further comprising providing a resonance capacitor connected to the coil in series or in parallel to form a resonance circuit configured for resonant inductive power transfer, wherein preferably, the coupler (1000) is a transmitter coupler configured to receive a time-varying current from a power source connected thereto for generating a magnetic field to perform wireless power transfer with a receiver coupler over an air gap based on magnetic induction, or wherein preferably, the coupler (1000) is a receiver coupler configured to couple with a magnetic field generated from a transmitter coupler to induce a current in the receiver coupler for supplying power to an electrical load connected to the receiver couple to perform wireless power transfer with the transmitter coupler over an air gap based on magnetic induction.
  11. A method of wireless power transfer comprising: generating, by a power source at a wireless power transmitter, a time-varying current; and receiving, by a transmitter coupler at the wireless power transmitter connected to the power source, the time-varying current from the power source for generating a magnetic field to perform wireless power transfer with a receiver coupler over an air gap based on magnetic induction; coupling, by the receiver coupler at a wireless power receiver connected to an electrical load, with a magnetic field generated from the transmitter coupler to induce a current in the receiver coupler to perform wireless power transfer with the transmitter coupler over the air gap based on magnetic induction; and supplying, by the receiver coupler at the wireless power receiver, power to the electrical load connected thereto based on the current induced therein, wherein at least one of the receiver coupler and the transmitter coupler is a coupler (1000) according to any one of claims 1 to 4, and the wireless power transmitter and the wireless power receiver are separated by the air gap.

Description

TECHNICAL FIELD The present invention generally relates to wireless power transfer based on magnetic induction, and more particularly, a coupler for wireless power transfer and a method of manufacturing thereof, a wireless power transmitter including the coupler, a wireless power receiver including the coupler, a system for wireless power transfer including the wireless power transmitter and/or the wireless power receiver, and a method of wireless power transfer using the coupler. BACKGROUND Wireless power transfer (WPT) based on magnetic induction (which may also be referred to as inductive power transfer (IPT)) has been widely used in charging or powering numerous applications, such as electronic devices, automatic guided vehicles, robots, electric transportations and so on, where safety and/or convenience are concerned. For example, in a WPT system for charging applications, the coil is the core element of the charging pad for both the primary side (transmitter) and the secondary side (receiver). Electrical power can be transferred wirelessly through the mutual magnetic coupling between the primary (transmitter) and secondary (receiver) coils in a similar working principle as a transformer. With electrical isolation capability, charging power can thus take place safely even in wet and dirty environments. Hence, the design/configuration of coils plays an important role as it affects the WPT system efficiency. The magnetic coupling coefficients (k) of the primary and secondary coils in a WPT system may typically be less than 0.5 due to the relatively large air gap therebetween, while transformers may have magnetic coupling coefficients of over 0.95. WPT system varies in size and capacity, depending on the power transfer levels (e.g., between about 0.5 W to about 50 kW or even more) and the air gap between the primary and secondary coils (e.g., from about 1 mm to about 100 mm or even more depending on the applications). The transferred power and the WPT system efficiency may be maximized in a practical manner when (i) the impedance matching condition is satisfied (e.g., when the output impedance matches with the load resistance) and (ii) the primary and secondary coils are axially aligned. For example, when the primary and secondary coils are axially misaligned and/or the distance between the primary and secondary coils is increased, the magnetic coupling coefficient k may decrease and affect the wireless power transfer efficiency. A need therefore exists to provide a coupler and a method for wireless power transfer, that seek to overcome, or at least ameliorate, one or more of the deficiencies in conventional couplers and methods for wireless power transfer, such as but not limited to, improving wireless power transfer efficiency and/or reducing magnetic flux leakage. It is against this background that the present invention has been developed. US 2017/092420 and JP H11 32452 disclose couplers with one anti-directional coil section, several full loops per coil portion, and continuous winding. SUMMARY According to a first aspect of the present invention, there is provided a coupler for wireless power transfer, as specified in claim 1, the coupler comprising: a coil configured for wireless power transfer based on magnetic induction, the coil comprising a plurality of coil portions, the plurality of coil portions comprising a first coil portion and a second coil portion wound in opposite directions, wherein the first coil portion is nested within the second coil portion. According to the invention, the first coil portion comprises one or more first loops and the second coil portion comprises one or more second loops wound in an opposite direction to the one or more first loops. According to the invention, the first coil portion is wound in a clockwise direction and the second coil portion is wound in an anti-clockwise direction, or the second coil portion is wound in a clockwise direction and the first coil portion is wound in an anti-clockwise direction. In various embodiments, the coil is configured to have a planar spiral configuration. In various embodiments, the first coil portion and the second coil portion are each configured to have a unipolar coil configuration, and the coil has a multi-polar coil configuration. According to the invention, the first coil portion and the second coil portion together form a first anti-directional coil section, and the coil further comprises one or more additional anti-directional coil sections, each additional anti-directional coil section comprising a third coil portion and a fourth coil portion wound in opposite directions, wherein the third coil portion is nested within the fourth coil portion. According to the invention, the first anti-directional coil section is nested within the one or more additional anti-directional coil section. According to the invention, the coil is configured as one continuous winding. In various embodiments, the coil forms a first coil cell