NON-CONTACT CHARGING METHOD

• US 20130162220A1
• Filed: 12/14/2012
• Published: 06/27/2013
• Est. Priority Date: 12/27/2011
• Status: Active Grant

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Iijima, Yasuhiro, Minami, Sadao, Makita, Yuki
• Granted Patent: US 9,007,019 B2
• Time in Patent Office: Days
• US Class Current: 320/137
• CPC Class Codes: H02J 50/005 Mechanical details of housing or structure aiming to accommodate the power transfer means, e.g. mechanical integration of coils, antennas or transducers into emitting or receiving devices
• 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 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/00304 Overcurrent protection

Abstract

A non-contact charging method, in which a battery-powered device is set down on a charging platform, a power receiving coil in the battery-powered device is electromagnetically coupled to a power transmission coil in the charging platform, power is transmitted from the power transmission coil to the power receiving coil by electromagnetic induction, and a battery (52) in the battery-powered device is charged. The charging current of the battery is detected on the battery-powered device side, the transmission efficiency is detected from the detected charging current, the detected transmission efficiency is compared to an efficiency threshold value, it is determined that a foreign object is on the charging platform when the detected charging efficiency is less than the efficiency threshold value and it is determined that a foreign object is not on the charging platform when the detected charging efficiency is greater than the efficiency threshold value.

Claims

1. A non-contact charging method including setting down a battery-powered device (50) on a charging platform (10), electromagnetically coupling a power receiving coil (51) in the battery-powered device (50) to a power transmission coil (11) in the charging platform (10), transmitting power from the power transmission coil (11) to the power receiving coil (51) by electromagnetic induction, and charging a battery (52) in the battery-powered device (50) using power induced in the power receiving coil (51),

the non-contact charging method characterized by detecting the charging current of the battery (52) on the battery-powered device (50) side, detecting the transmission efficiency from the charging current, comparing the detected transmission efficiency to an efficiency threshold value, determining that a foreign object has been set down on the charging platform (10) when the detected charging efficiency is less than the efficiency threshold value and determining that a foreign object has not been set down on the charging platform (10) when the detected charging efficiency is greater than the efficiency threshold value, and suspending foreign object detection during a time period including a fluctuation in the charging current.

2. A non-contact charging method according to claim 1, wherein, when a fluctuation occurs in the charging current of the battery (52) and the charging current temporarily rises above or falls below the current change detection threshold value, the period of time including the rise or fall in the charging current above or below the current change detection threshold value is determined to be a time period including a fluctuation in the charging current when the period of time is shorter than a set time period, and foreign object detection is suspended during this time period.

3. A non-contact charging method according to claim 2, wherein, when a charging current greater than the current change detection threshold value falls below the current change detection threshold value or a charging current less than the current change detection threshold value rises above the current change detection threshold value, a predetermined time period after the charging current passes the current change detection threshold value is determined to be a time period including a fluctuation in the charging current, and foreign object detection is suspended during this time period.

4. A non-contact charging method according to claim 1, wherein the charging current for the battery (52) is detected on the battery-powered device (50) side, the detected charging current and the efficiency threshold value are transmitted to the charging platform (10), and the charging platform (10) performs foreign object detection from the charging current and the efficiency threshold value.

5. A non-contact charging method according to claim 1, wherein the power supplied to the power transmission coil (11) is controlled when a foreign object is detected on the charging platform (10).

6. A non-contact charging method according to claim 1, wherein the efficiency threshold value used to compare the detected transmission efficiency is set to a lowest threshold value, and foreign object detection is effectively stopped during a time period including a fluctuation in the charging current.

7. A non-contact charging method according to claim 6, wherein the lowest threshold value is level 0.

8. A non-contact charging method according to claim 1, wherein the supply of power to the power transmission coil (11) is stopped and charging of the battery (52) is stopped, or the power introduced to the power transmission coil (11) is reduced below a power setting, and the amount of charging current for the battery (52) is reduced when a foreign object is detected.