Vehicle and wireless power transmission system

• US 10,703,209 B2
• Filed: 12/20/2017
• Issued: 07/07/2020
• Est. Priority Date: 12/22/2016
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Intellectual Property Management Co., Ltd. (Panasonic Holdings Corporation)
• Inventors: Yamamoto, Hiroshi, Kikuchi, Satoru
• Primary Examiner(s): Amrany, Adi
• Application Number:
  US15/847,929
• Publication Number:
  US 20180178660A1
• Time in Patent Office: 930 Days
• Field of Search: 307 91, 307 101
• CPC Class Codes: B60L 2200/44 Industrial trucks or floor conveyors
• CPC Class Codes: B60L 5/005 without mechanical contact between the collector and the power supply line
• CPC Class Codes: B60L 50/53 in combination with an external power supply, e.g. from overhead contact lines
• CPC Class Codes: B60L 53/00 Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
• CPC Class Codes: B60L 53/22 Constructional details or arrangements of charging converters specially adapted for charging electric vehicles
• CPC Class Codes: B60L 9/00 Electric propulsion with power supply external to the vehicle electric propulsion for monorail vehicles, suspension vehicles or rack railways B60L13/00; in combination with batteries or fuel cells within the vehicle B60L50/53
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 50/05 using capacitive coupling
• CPC Class Codes: H02P 1/16 for starting dynamo-electric motors or dynamo-electric converters
• CPC Class Codes: H02P 3/06 for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter
• CPC Class Codes: H03H 7/38 Impedance-matching networks
• CPC Class Codes: Y02P 90/60 Electric or hybrid propulsion means for production processes
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A vehicle to be driven by electric power which is wirelessly transmitted from a power transmitter having two transmission electrodes includes: two reception electrodes to receive AC power from the two transmission electrodes through capacitive coupling respectively with the two transmission electrodes; a power receiving circuit which is connected to the two reception electrodes to convert AC power received by the two reception electrodes into DC power or another form of AC power, and supply the DC power or other form of AC power to an electric motor which drives the vehicle; and a control circuit which, while the vehicle is traveling over the two transmission electrodes, increases an impedance of the vehicle as viewed from the power transmitter when a value of at least one of power, voltage and current in the power receiving circuit, or a change rate over time thereof, exceeds a threshold value.

Claims

1. A vehicle for use in a wireless power transmission system including a power transmitter having two transmission electrodes and two or more vehicles to be driven by electric power which is wirelessly transmitted from the power transmitter, the vehicle comprising:

two reception electrodes to receive AC power from the two transmission electrodes through capacitive coupling respectively with the two transmission electrodes;

a power receiving circuit which is connected to the two reception electrodes to convert AC power received by the two reception electrodes into DC power or another form of AC power, and supply the DC power or other form of AC power to an electric motor which drives the vehicle or to a secondary battery which stores electric power for driving the vehicle; and

a control circuit which, while the vehicle is moving, detects another vehicle that is receiving power from the power transmitter by detecting that a value of at least one of power, voltage and current in the power receiving circuit, or a change rate over time thereof, exceeds a threshold value, and performs a control process to increase an impedance of the vehicle as viewed from the power transmitter to suppress decrease in efficiency of power transmission to the other vehicle.

2. The vehicle of claim 1, wherein,

the value of at least one of power, voltage and current in the power receiving circuit, or the change rate over time thereof, is greater than the threshold value when the power transmitter is transmitting power to the another vehicle distinct from the vehicle;

and

the value of at least one of power, voltage and current in the power receiving circuit, or the change rate over time thereof, is not greater than the threshold value when the power transmitter is not transmitting power to the another vehicle distinct from the vehicle.

3. The vehicle of claim 1, wherein, while the two reception electrodes are opposed respectively to the two transmission electrodes, if a predetermined amount of time has elapsed before the value of at least one of power, voltage and current in the power receiving circuit, or the change rate over time thereof, exceeds the threshold value, the control circuit requests the power transmitter for power transmission.

4. The vehicle of claim 1, wherein the control circuit includes a motor control circuit which controls the electric motor, and the motor control circuit increases the impedance of the vehicle as viewed from the power transmitter by sending the electric motor a command to stop.

5. The vehicle of claim 4, wherein, after sending the electric motor the command to stop, at the lapse of a predetermined amount of time, the control circuit sends the electric motor a command to start again.

6. The vehicle of claim 4, wherein, after sending the electric motor the command to stop, if the value of at least one of power, voltage and current in the power receiving circuit, or the change rate over time thereof, becomes lower than a threshold value, the control circuit sends the electric motor a command to start again.

7. The vehicle of claim 1, wherein,

the power receiving circuit includes a switch to turn ON or OFF electrical connection between the two reception electrodes and the electric motor;

and

the control circuit increases the impedance of the vehicle as viewed from the power transmitter by sending the switch a command to turn OFF the electrical connection.

8. The vehicle of claim 7, wherein, after sending the command to the switch, at the lapse of a predetermined amount of time, the control circuit sends the switch a command to turn ON the electrical connection.

9. The vehicle of claim 7, wherein,

the power receiving circuit includes

a rectifier circuit, and

a switch circuit which is connected between the two reception electrodes and the rectifier circuit, the switch circuit including the switch.

10. The vehicle of claim 7, wherein,

the power receiving circuit includes

a rectifier circuit, and

a switch circuit which is connected between the rectifier circuit and the electric motor, the switch circuit including the switch.

11. The vehicle of claim 7, wherein,

the power receiving circuit includes

a rectifier circuit,

an impedance matching circuit which is connected between the two reception electrodes and the rectifier circuit, and

a switch circuit which is connected between the two reception electrodes and the impedance matching circuit, or between the impedance matching circuit and the rectifier circuit, the switch circuit including the switch.

12. The vehicle of claim 1, wherein the control circuit increases the impedance of the vehicle as viewed from the power transmitter by sending the power receiving circuit a command to change a value of at least one of resistance, inductance and capacitance of the power receiving circuit.

13. The vehicle of claim 1, further comprising the electric motor.

14. The vehicle of claim 1, further comprising a detector to detect the at least one of power, voltage and current in the power receiving circuit.

15. The vehicle of claim 1, wherein the vehicle is an automated guided vehicle.

16. A wireless power transmission system comprising:

the vehicle of claim 1; and

the power transmitter.

17. A method of controlling a-vehicles in a wireless power transmission system including a power transmitter having two transmission electrodes and at least a first vehicle and a second vehicle driven by electric power which is wirelessly transmitted from the power transmitter, the first vehicle and the second vehicle each comprising two reception electrodes for receiving AC power from the two transmission electrodes through capacitive coupling respectively with the two transmission electrodes,

the method comprising the steps of:

the first vehicle determining, while the first vehicle is moving with the two reception electrodes being opposed to the two transmission electrodes and the second vehicle is receiving power from the power transmitter, that the second vehicle is receiving power from the power transmitter by detecting that a value of at least one of power, voltage and current in a power receiving circuit connected to the two reception electrodes, or a change rate over time thereof, exceeds a threshold value; and

as a result of the determination that the second vehicle is receiving power from the power transmitter, the first vehicle performing a control process to increase an impedance of the vehicle as viewed from the power transmitter to suppress decrease in efficiency of power transmission to the second vehicle; and

further comprising the steps of;

the first vehicle determining, while the first vehicle is moving with the two reception electrodes being opposed to the two transmission electrodes and the second vehicle not receiving power from the power transmitter, that the second vehicle is not receiving power from the power transmitter by detecting that the value of at least one of power, voltage and current in a power receiving circuit connected to the two reception electrodes, or a change rate over time thereof, does not exceed a threshold value, and as a result of the determination that the second vehicle is not receiving power from the power transmitter, the first vehicle determining whether the first vehicle needs to receive AC power from the power transmitter and requesting the transmitter to transmit AC power if the first vehicle needs to receive the AC power from the power transmitter; and

if the first vehicle needs to receive the AC power, receiving the AC power from the power transmitter by the two reception electrodes, and converting, in the power receiving circuit, the AC power received by the two reception electrodes into DC power or another form of AC power to supply the DC power or other form of AC power to an electric motor which drives the first vehicle or to a secondary battery which stores electric power for driving the first vehicle.