# US 12,014,857 B2 · Wireless charging system with a switchable magnetic core > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,014,857 B2 - Document ID: US12014857B2 - Status: Granted - Kind: B2 - Application number: 17/179,603 - Filed: 2021-02-19 - Published: 2021-12-23 - Granted: 2024-06-18 - Earliest claimed: 2020-06-19 - Assignees: Apple Inc. - Applicants: Apple Inc. - Inventors: Zaki Moussaoui; Zelin Xu; Matthew J. Chabalko; Nan Liu - Web page: https://patentgrep.com/patent/US12014857B2 ## CPC - H01F 27/24: Magnetic cores - H01F 3/10: Composite arrangements of magnetic circuits - H01F 27/366: {made of ferromagnetic material} - H01F 38/14: Inductive couplings - H02J 7/02: for charging batteries from AC mains by converters - 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} - H02J 50/12: of the resonant type - H02J 50/90: involving detection or optimisation of position, e.g. alignment - H01F 2003/103: {Magnetic circuits with permanent magnets} - H01F 2003/106: {Magnetic circuits using combinations of different magnetic materials} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY ## Abstract An electronic device in a wireless power system may be operable with a removable accessory such as a case. The device may convey wireless power to, from, or through the case while the device is coupled to the case. The device may have coplanar power transmitting and power receiving coils. The removable accessory may have an embedded switchable ferrimagnetic core and a coil that overlaps the switchable ferrimagnetic core. The switchable ferrimagnetic core may be operable in a first state where the switchable ferrimagnetic core is unsaturated. The switchable ferrimagnetic core may be operable in a second state where the switchable ferrimagnetic core is saturated by a magnetic field from a permanent magnet in a wireless power transmitting device. In the second state, the switchable ferrimagnetic core may have a lower magnetic permeability and higher magnetic reluctance than in the first state. ## Claims ### Claim 1 An electronic device comprising: a first planar wireless charging coil having windings wound about a central region, wherein the first planar wireless charging coil is configured to transmit first wireless power signals; a second planar wireless charging coil having windings positioned in the central region, wherein the second planar wireless charging coil is configured to receive second wireless power signals; a first ferrimagnetic core overlapping the first planar wireless charging coil; and a second ferrimagnetic core overlapping the second planar wireless charging coil, the second ferrimagnetic core positioned to direct received magnetic flux towards the second planar wireless charging coil, wherein the second ferrimagnetic core has a different magnetic reluctance than the first ferrimagnetic core. ### Claim 2 (depends on 1) The electronic device of claim 1, wherein the first planar wireless charging coil is configured to operate at a first maximum power level and wherein the second planar wireless charging coil is configured to operate at a second maximum power level that is greater than the first maximum power level. ### Claim 3 (depends on 1) The electronic device of claim 1, wherein the first planar wireless charging coil is configured to cease transmission of the first wireless power signals when the second planar wireless charging coil receives the second wireless power signals. ### Claim 4 (depends on 1) The electronic device of claim 1, wherein the first planar wireless charging coil is configured to transmit the first wireless power signals when the electronic device is coupled to a removable accessory. ### Claim 5 (depends on 1) The electronic device of claim 1, wherein the second planar wireless charging coil is configured to receive the second wireless power signals when the electronic device is coupled to a wireless power transmitting device. ### Claim 6 (depends on 1) The electronic device of claim 1, wherein the second planar wireless charging coil is configured to receive the second wireless power signals when the electronic device is coupled to a removable accessory and a wireless power transmitting device. ### Claim 7 (depends on 1) The electronic device of claim 1, wherein the first planar wireless charging coil and the second planar wireless charging coil are coplanar. ### Claim 8 (depends on 1) The electronic device of claim 1, wherein the first ferrimagnetic core and the second ferrimagnetic core are coplanar. ### Claim 9 (depends on 1) The electronic device of claim 1, wherein the first ferrimagnetic core and the second ferrimagnetic core are formed from different materials. ### Claim 10 (depends on 1) The electronic device of claim 1, wherein the first ferrimagnetic core and the second ferrimagnetic core have different thicknesses. ### Claim 11 An electronic device comprising: a first planar wireless charging coil having windings wound about a central region; a second planar wireless charging coil having windings positioned in the central region; a first ferrimagnetic core overlapping the first planar wireless charging coil; a second ferrimagnetic core overlapping the second planar wireless charging coil, the second ferrimagnetic core positioned to direct received magnetic flux towards the second planar wireless charging coil, wherein the second ferrimagnetic core has a different magnetic reluctance than the first ferrimagnetic core; and a ring-shaped permanent magnet having a central opening, wherein the first planar wireless charging coil and the second planar wireless charging coil are positioned in the central opening of the ring-shaped permanent magnet. ### Claim 12 (depends on 1) The electronic device of claim 1, wherein the second planar wireless charging coil is configured to receive the second wireless power signals from a wireless power transmitting device when the electronic device and a removable accessory are inductively coupled to the wireless power transmitting device and a ferrimagnetic core in the removable accessory is in a first state. ### Claim 13 (depends on 12) The electronic device defined in claim 12, wherein the first planar wireless charging coil is configured to transmit the first wireless power signals to a wireless power receiving coil in the removable accessory when the electronic device and the removable accessory are not inductively coupled to the wireless power transmitting device and the ferrimagnetic core is in a second state that is different than the first state. ### Claim 14 (depends on 11) The electronic device of claim 11, wherein the first planar wireless charging coil is configured to operate at a first maximum power level and wherein the second planar wireless charging coil is configured to operate at a second maximum power level that is greater than the first maximum power level. ### Claim 15 (depends on 11) The electronic device of claim 11, wherein the first planar wireless charging coil is configured to transmit first wireless power signals and wherein the second planar wireless charging coil is configured to receive second wireless power signals. ### Claim 16 (depends on 11) The electronic device of claim 11, wherein the first planar wireless charging coil and the second planar wireless charging coil are coplanar. ### Claim 17 (depends on 11) The electronic device of claim 11, wherein the first ferrimagnetic core and the second ferrimagnetic core are formed from different materials. ### Claim 18 (depends on 11) The electronic device of claim 11, wherein the first ferrimagnetic core and the second ferrimagnetic core have different thicknesses. ### Claim 19 (depends on 11) The electronic device of claim 11, wherein the second planar wireless charging coil is configured to receive the second wireless power signals from a wireless power transmitting device when the electronic device and a removable accessory are inductively coupled to the wireless power transmitting device and a ferrimagnetic core in the removable accessory is in a first state and wherein the first planar wireless charging coil is configured to transmit the first wireless power signals to a wireless power receiving coil in the removable accessory when the electronic device and the removable accessory are not inductively coupled to the wireless power transmitting device and the ferrimagnetic core is in a second state that is different than the first state.