Wireless power transmission device and foreign object detection coil thereof for detecting metallic foreign object

Patent metadata

Field	Value
Publication number	US-10361594-B2
Application number	US-201615166686-A
Country	US
Kind code	B2
Filing date	Jun 24, 2016
Priority date	Apr 25, 2016
Publication date	Jul 23, 2019
Grant date	Jul 23, 2019

Abstract

A wireless power transmission device radiates electromagnetic waves through a transmission antenna and generates multiple sensed signals by using multiple foreign object detection (FOD) coils for detecting metallic foreign object to sense the electromagnetic waves. Each FOD coil has three coil units connected in series to and spaced apart from one another. The radiation pattern of the transmission antenna overlaps a sensing range of the FOD coils. A controller of the wireless power transmission device determines if any metallic foreign object enters the radiation range of the transmission antenna according to a reference voltage signal and sensed signals of the cells, and stops the generation of electromagnetic waves when determining entry of metallic foreign object into the radiation range to avoid the metallic foreign object to be heated by the electromagnetic waves.

First claim

What is claimed is:

1. A wireless power transmission device, comprising:
an alternating current (AC) to direct current (DC) converter having an input terminal to receive an AC power and convert the AC power into a DC power;
a DC to AC converter having:
an input terminal electrically connected to an output terminal of the AC to DC converter to convert the DC power into an AC output power; and
multiple compensation capacitors electrically connected to a transmission antenna to transmit the AC output power in the form of electromagnetic waves through the transmission antenna;

multiple foreign object detection (FOD) coils for detecting metallic foreign object mounted on an insulating substrate to sense the electromagnetic waves and generate multiple sensed signals, each FOD coil having three coil units connected in series to and spaced apart from one another, wherein a radiation pattern of the transmission antenna overlaps a sensing range of the FOD coils;
a reference voltage generation circuit having an input terminal electrically connected to the multiple compensation capacitors of the DC to AC converter to receive terminal voltages of any one of the multiple compensation capacitors and generate a reference voltage signal according to the terminal voltages of the compensation capacitor;
multiple feedback detection circuits electrically connected to the respective FOD coils, each feedback detection circuit receiving the sensed signal of a corresponding FOD coil; and
a controller electrically connected to the reference voltage generation circuit and the multiple feedback detection circuits to receive the reference voltage signal and the sensed signals corresponding to the multiple FOD coils and determine if any metallic foreign object enter a range of electromagnetic waves generated by the transmission antenna according to the reference voltage signal and the sensed signals.

2. The wireless power transmission device as claimed in claim 1 , wherein the FOD coils are arranged on the insulating substrate in the form of a matrix, and each coil unit of a corresponding FOD coil has a center segment, a first segment, a second segment, a third segment, a fourth segment, a fifth segment and a sixth segment mounted on a surface of the insulating substrate, wherein
the center segment is U-shaped and has two ends, the first segment, the second segment and the third segment are mounted on the surface of the insulating substrate and are sequentially arranged outwards on a side of the center segment;
the third segment is electrically connected to one end of the fifth segment, the other end of the fifth segment is electrically connected to one end of the first segment through a connection segment, the other end of the first segment is electrically connected to one end of the center segment through a bridging segment, the other end of the center segment is electrically connected to one end of the fourth segment through another connection segment, the other end of the fourth segment is electrically connected to one end of the second segment through another bridging segment, and the other end of the second segment is electrically connected to one end of the sixth segment through another connection segment; and
the center segment, the first segment, the second segment, the third segment, the fourth segment, the fifth segment and the sixth segment to form the FOD coil with a winding structure.

3. The wireless power transmission device as claimed in claim 1 , wherein the FOD coils are arranged on the insulating layer in the form of a matrix, and each FOD coil has a first coil unit, a second coil unit and a third coil unit, wherein
the second coil unit is formed by winding a second wire to generate a coiled isosceles triangle with a first leg and a second leg, and has an inner end and an outer end;
the first coil unit is formed by winding a first wire to generate a coiled right triangle with a hypotenuse and has an inner end and an outer end, wherein the hypotenuse of the first coil unit is external and parallel to the first leg of the second coil unit;
the third coil unit is formed by winding a third wire to generate a coiled right triangle with a hypotenuse and has an inner end and an outer end, wherein the hypotenuse of the third coil unit is external and parallel to the second leg of the second coil unit;
the inner end of the first coil unit is connected to an outer end of the second coil unit through a first connection segment, and the inner end of the second coil unit is connected to the inner end of the third coil unit through a second connection segment; and
the first coil unit, the second coil unit and the third coil unit are spaced apart from one another and the first coil unit, the second coil unit and the third coil unit as a whole are rectangular.

4. The wireless power transmission device as claimed in claim 1 , wherein each FOD coil has a first coil unit, a second coil unit and a third coil unit, wherein
the second coil unit is formed by winding a second wire to generate a coiled isosceles triangle with a first leg and a second leg, and has an inner end and an outer end;
the first coil unit is formed by winding a first wire to generate a coiled right triangle with a hypotenuse and has an inner end and an outer end, wherein the hypotenuse of the first coil unit is external and parallel to the first leg of the second coil unit;
the third coil unit is formed by winding a third wire to generate a coiled right triangle with a hypotenuse and has an inner end and an outer end, wherein the hypotenuse of the third coil unit is external and parallel to the second leg of the second coil unit;
the inner end of the first coil unit is connected to an inner end of the third coil unit through a first connection segment, and the outer end of the first coil unit is connected to the inner end of the second coil unit through a second connection segment; and
the first coil unit, the second coil unit and the third coil unit are spaced apart from one another and the first coil unit, the second coil unit and the third coil unit as a whole is sector-shaped.

5. The wireless power transmission device as claimed in claim 4 , wherein the insulating substrate has four FOD coils taking the form of an octagon as a whole.

6. The wireless power transmission device as claimed one of claims 1 to 5 , wherein
when determining if there is any metallic foreign object, the controller initially receives the reference voltage signal indicative of a state of no presence of metallic foreign object and the multiple sensed signals, calculates a gain in association with each FOD coil according to the reference voltage signal and a corresponding sensed signal, and creates a gain table according to values of the gain for the FOD coils, wherein the gain is a ratio of the reference voltage signal to a corresponding FOD coil and the gain table can be stored in the controller; and
after the gain table is created, the controller continuously receives the sensed signals of the FOD coils, obtains an instant monitoring signal by multiplying the sensed signal generated by each FOD coil and a corresponding gain, and shuts down the wireless power transmission device when determining that a difference between the reference voltage signal and the instant monitoring signal corresponding to the FOD coil is greater than or equal to a threshold.

7. A foreign object detection (FOD) coil for detecting metallic foreign object formed with a single conductor on a planar insulating substrate, and comprising:
three coil units directly connected in series to and spaced apart from one another, each of the three coil units having a starting terminal and an ending terminal, wherein the ending terminal of a first one of the three coil units is dire

Assignees

• Automotive Res & Testing Ct

Inventors

• Huang Tzyy-Haw
• Lu Chien-Chih

Classifications

• H02J7/025

  Electricity · mapped topic

• H02J50/10

  using inductive coupling · CPC title

• H01F2027/2809

  on stacked layers · CPC title

• H01F1/00

  Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties · CPC title

• H02J50/60 Primary

  responsive to the presence of foreign objects, e.g. detection of living beings · CPC title