Wireless charging system and foreign metal object detection method for the system

• US 9,614,395 B2
• Filed: 12/30/2014
• Issued: 04/04/2017
• Est. Priority Date: 12/30/2014
• Status: Active Grant

• Current Assignee: Automotive Research & Testing Center
• Original Assignee: Automotive Research & Testing Center
• Inventors: Wang, Yu-Chuan, Chiang, Chao-Wen
• Primary Examiner(s): Fantu, Yalkew
• Assistant Examiner(s): Sharief, Mohammed J
• Application Number:
  US14/586,248
• Publication Number:
  US 20160190852A1
• Time in Patent Office: 826 Days
• Field of Search: 320108
• CPC Class Codes: G01R 25/005 Circuits for comparing several input signals and for indicating the result of this comparison, e.g. equal, different, greater, smaller, or for passing one of the input signals as output signal
• CPC Class Codes: G01V 3/088 operating with electric fields G01V3/082 takes precedence
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection

Abstract

A wireless charging system includes a wireless charging device and a power-consuming device installed in a charging area. The wireless charging device has a signal conversion module connected to a controller, a transmitter antenna and a power input terminal. The power-consuming device has a receiver coil connected to a rectifier and outputting generated power through a power output terminal. Before or when the wireless charging device charges the power-consuming device, the controller of the wireless charging device can detect a power consumption status, voltage and current information and phase difference information of the transmitter antenna to instantly determine if any foreign metal object enters the charging area, thereby preventing high temperature generated by the foreign metal object from causing equipment damage and danger and enhancing wireless charging safety.

Claims

1. A foreign metal object detection method for a wireless charging system performed by a wireless charging device to transmit an electromagnetic signal to a power-consuming device, wherein the wireless charging device is connected to an external power terminal and includes a transmitter controller, a signal conversion module and a transmitter antenna, wherein the signal conversion module is connected to the transmitter antenna, the transmitter controller and the external power terminal;

the method comprising steps of;

receiving at least one set of voltage and current information from the external power terminal with the signal conversion module, wherein each set of voltage and current information of the at least one set of voltage and current information includes voltage information and current information, and phase difference information associated with the at least one set of voltage and current information from the transmitter controller, and driving the transmitter antenna with the signal conversion module to transmit an electromagnetic signal to the power-consuming device, wherein the transmitter controller respectively converts a voltage waveform and a current waveform associated with the voltage information and the current information in each set of voltage and current information into a first square waveform and a second square waveform, wherein a first cycle is defined as a difference between time at a rising edge of the first square waveform and time at a rising edge of the second square waveform adjacent thereto, a second cycle is defined as a complete cycle of the second square waveform, wherein the transmitter controller calculates the phase difference information associated with the set of voltage and current information according to a ratio of the first cycle over the second cycle;

determining if a variation of each of the voltage information and the current information in each set of voltage and current information and the phase difference information associated with the set of voltage and current information fall outside a safe range through the transmitter controller; and

performing an emergency response measure through the transmitter controller by sending a control signal to the signal conversion module for the signal conversion module to stop the transmitter antenna from transmitting electromagnetic signals and sending out an alarm signal when the variation of each of the voltage information and the current information in each set of voltage and current information and the phase difference information fall outside the safe range.

2. The method as claimed in claim 1, wherein after the step of receiving the at least one set of voltage and current information and the phase difference information associated with the at least one set of voltage and current information, the method further comprises a step of acquiring a real impedance value corresponding to each of the voltage information and the current information in each set of voltage and current information.

3. The method as claimed in claim 2, wherein when performing the step of determining if the variation of each of the voltage information and the current information in each set of voltage and current information and the phase difference information fall outside the safe range, the method further comprises steps of:

simultaneously determining if the variation of the real impedance value associated with each of the voltage information and the current information in each set of voltage and current information is greater than a first safety threshold and the phase difference information associated with the set of voltage and current information is greater than a second safety threshold; and

performing the emergency response measure when the variation of the real impedance value associated with each of the voltage information and the current information in each set of voltage and current information is greater than the first safety threshold and the phase difference information associated with the set of voltage and current information is greater than the second safety threshold.

9. The method as claimed in claim 1, wherein the first cycle is defined as a difference between time at a falling edge of the first square waveform and time at a falling edge of the second square waveform adjacent thereto.

10. The method as claimed in claim 9, wherein after the step of receiving the at least one set of voltage and current information and the phase difference information associated with the at least one set of voltage and current information, the method further comprises a step of acquiring a real impedance value corresponding to each of the voltage information and the current information in each set of voltage and current information.

11. The method as claimed in claim 10, wherein when performing the step of determining if the variation of each of the voltage information and the current information in each set of voltage and current information and the phase difference information falls outside the safe range, the method further comprises steps of:

simultaneously determining if the variation of each of the real impedance value associated with the voltage information and the current information in each set of voltage and current information is greater than a first safety threshold and the phase difference information associated with the set of voltage and current information is greater than a second safety threshold; and

performing the emergency response measure when the variation of each of the real impedance value associated with the voltage information and the current information in each set of voltage and current information is greater than the first safety threshold and the phase difference information associated with the set of voltage and current information is greater than the second safety threshold.

4. A wireless charging system, comprising:

a wireless charging device adapted to be connected to an external power terminal and having;

a transmitter controller;

a transmitter antenna; and

a signal conversion module connected to the external power terminal, the transmitter controller and the transmitter antenna, receiving at least one set of voltage and current information from the external power terminal, wherein each set of voltage and current information of the at least one set of voltage and current information includes voltage information and current information, and driving the transmitter antenna to transmit electromagnetic signals; and

a power-consuming device having;

a rectifier;

a receiver controller connected to the rectifier;

a receiver coil connected to the rectifier, sensing the electromagnetic signals transmitted from the transmitter antenna of the wireless charging device in generation of a current, and outputting the current to a power output terminal through the rectifier;

wherein the transmitter controller respectively converts a voltage waveform and a current waveform associated with the voltage information and the current information in each set of voltage and current information of the at least one voltage and current information into a first square waveform and a second square waveform, defines a first cycle as a difference between time at a rising edge of the first square waveform and time at a rising edge of the second waveform adjacent thereto and a second cycle as a complete cycle of the second square waveform, and calculates phase difference information associated with the set of voltage and current information according to a ratio of the first cycle over the second cycle, when determining that a variation of each of the voltage information and the current information in the set of voltage and current information and the phase difference information associated with the set of voltage and current information fall outside a safe range, the transmitter controller of the wireless charging device transmits a control signal to the signal conversion module to stop the transmitter antenna from transmitting the electromagnetic signals and sends out an alarm signal.

5. The wireless charging system as claimed in claim 4, wherein the signal conversion module has:

a first signal converter connected to the transmitter antenna and the transmitter controller; and

a second signal converter connected between the first signal converter and a power source.

6. The wireless charging system as claimed in claim 5, wherein

the wireless charging device further has a first communication module connected to the transmitter controller;

the power-consuming device further has a second communication module connected to the receiver controller and establishing a link with the first communication module of the wireless charging device using a communication protocol.

7. The wireless charging system as claimed in claim 6, wherein the first signal converter pertains to a DC (Direct Current) to AC (Alternating Current) converter, and the second signal converter pertains to an AC to DC converter.

8. The wireless charging system as claimed in claim 7, wherein the transmitter controller of the wireless charging device is connected to an emergency stop module, and the receiver controller of the power-consuming device is connected to another emergency stop module, a man machine interface, an energy management system or a vehicle control unit.

12. The system as claimed in claim 4, wherein the first cycle is defined as a difference between time at a falling edge of the first square waveform and time at a falling edge of the second square waveform adjacent thereto.

13. The wireless charging system as claimed in claim 12, wherein the signal conversion module has:

a first signal converter connected to the transmitter antenna and the transmitter controller; and

a second signal converter connected between the first signal converter and a power source.

14. The wireless charging system as claimed in claim 13, wherein

the wireless charging device further has a first communication module connected to the transmitter controller;

the power-consuming device further has a second communication module connected to the receiver controller and establishing a link with the first communication module of the wireless charging device using a communication protocol.

15. The wireless charging system as claimed in claim 14, wherein the first signal converter pertains to a DC (Direct Current) to AC (Alternating Current) converter, and the second signal converter pertains to an AC to DC converter.

16. The wireless charging system as claimed in claim 15, wherein the transmitter controller of the wireless charging device is connected to an emergency stop module, and the receiver controller of the power-consuming device is connected to another emergency stop module, a man machine interface, an energy management system or a vehicle control unit.