Power transfer disablement switch in a wireless power reception apparatus
This disclosure provides systems, methods and apparatuses for preventing power transfer in a secondary coil of a wireless power reception apparatus. Some implementations relate generally to the use of one or more switches. In some implementations, the one or more switches may be coupled in series to one or both ends of the secondary coil. The one or more switches may be controlled based on a handshake communication between the wireless power reception apparatus and a compatible wireless power transmission apparatus. The one or more switches may be controlled using bias power from a wireless communication interface that is separate from a power reception circuitry that includes the secondary coil. The one or more switches may disable power transfer in the secondary coil to protect one or more components of the wireless power reception apparatus or to enable measurement of a coupling factor during measurement periods.
1 . A wireless power reception apparatus, comprising:
a secondary coil configured to receive wireless power from a wireless power signal of a wireless power transmission apparatus;
a power reception circuit configured to utilize the wireless power; and
one or more switches positioned between the secondary coil and the power reception circuit, the one or more switches configured to:
disconnect the secondary coil from the power reception circuit during a coupling factor (k-factor) measurement period, and
connect the secondary coil to the power reception circuit during a power transfer period.
2 . The wireless power reception apparatus of claim 1 , further comprising:
a receiver controller configured to control the one or more switches based, at least in part, on the k-factor measurement period and the power transfer period.
3 . The wireless power reception apparatus of claim 2 , wherein the k-factor measurement period precedes the power transfer period, and wherein an operating point of the wireless power signal is based, at least in part, on a coupling factor determined during the k-factor measurement period.
4 . The wireless power reception apparatus of claim 2 ,
wherein the secondary coil is further configured to receive a k-factor measurement signal from the wireless power transmission apparatus, and
wherein the k-factor measurement period enables measurement of a voltage of the secondary coil based on the k-factor measurement signal while the secondary coil is disconnected from the power reception circuit.
5 . The wireless power reception apparatus of claim 1 , further comprising:
a wireless communication interface configured to receive a communication from the wireless power transmission apparatus, wherein the communication includes at least one member of a group consisting of:
an indication of a start or duration of the k-factor measurement period,
an instruction to begin the k-factor measurement period,
a communication that is inferred by the wireless power reception apparatus to initiate the k-factor measurement period, and
an indication that the wireless power transmission apparatus supports a wireless power transfer protocol that specifies the k-factor measurement period.
6 . A method of a wireless power reception apparatus, comprising:
operating a secondary coil and a power reception circuit of a wireless power reception apparatus, the secondary coil to receive wireless power from a wireless power transmission apparatus, the power reception circuit to utilize the received wireless power, wherein one or more switches are positioned between the secondary coil and the power reception circuit; and
controlling the one or more switches, wherein controlling the one or more switches includes:
disconnecting the secondary coil from the power reception circuit using the one or more switches during a coupling factor (k-factor) measurement period; and
connecting the secondary coil to the power reception circuit using the one or more switches during a power transfer period.
7 . The method of claim 6 , further comprising:
harvesting a bias power via a communication coil of a wireless communication interface of the wireless power reception apparatus;
controlling the one or more switches at least initially using the bias power; and
subsequently controlling the one or more switches using the received wireless power after the one or more switches connect the secondary coil and the power reception circuit.
8 . The method of claim 7 , wherein the wireless communication interface is a short range radio frequency interface configured to receive and process a communication from a corresponding wireless communication interface of the wireless power transmission apparatus.
9 . The method of claim 6 , wherein controlling the one or more switches includes:
controlling the one or more switches based, at least in part, on the k-factor measurement period and the power transfer period.
10 . The method of claim 6 , further comprising:
receiving, by the secondary coil, a k-factor measurement signal from the wireless power transmission apparatus during the k-factor measurement period; and
measuring a voltage of the secondary coil based on the k-factor measurement signal while the secondary coil is disconnected from the power reception circuit during the k-factor measurement period.
11 . The method of claim 6 , further comprising:
receiving, via a wireless communication interface, a control communication from the wireless power transmission apparatus, wherein the communication includes at least one member of a group consisting of:
an indication of a start or duration of the k-factor measurement period,
an instruction to begin the k-factor measurement period,
a communication that is inferred by the wireless power reception apparatus to initiate the k-factor measurement period, and
an indication that the wireless power transmission apparatus supports a wireless power transfer protocol that specifies the k-factor measurement period.
12 . The method of claim 10 , further comprising:
providing feedback to the wireless power transmission apparatus based on the voltage of the secondary coil that is measured during the k-factor measurement period.