System and method for inductive charging of portable devices
A system and method for variable power transfer in an inductive charging or power system. In accordance with an embodiment the system comprises a pad or similar base unit that contains a primary, which creates an alternating magnetic field. A receiver comprises a means for receiving the energy from the alternating magnetic field from the pad and transferring it to a mobile device, battery, or other device. In accordance with various embodiments, additional features can be incorporated into the system to provide greater power transfer efficiency, and to allow the system to be easily modified for applications that have different power requirements. These include variations in the material used to manufacture the primary and/or the receiver coils; modified circuit designs to be used on the primary and/or receiver side; and additional circuits and components that perform specialized tasks, such as mobile device or battery identification, and automatic voltage or power-setting for different devices or batteries.
1 . A system for inductive powering and charging of portable devices or batteries, comprising:
a base unit, including one or more primary coils composed of a metallic material and shaped as planar spiral coils, which are capable of generating an inductive energy for use in powering or charging of portable devices or batteries;
a receiver unit, including a secondary coil also composed of a metallic material and shaped as a planar spiral coil, which is coupled to or incorporated into a portable device or battery, wherein the secondary coil receives energy inductively from one or more of the primary coils and uses it to charge or power the portable device or battery; and
means within the base unit for allowing a degree of position independence of the devices or batteries on the base unit and selectively activating one or more of the primary coils;
wherein the base unit can simultaneously charge or power additional portable devices or batteries with additional secondary coils;
wherein the base unit includes a microcontroller unit; and
wherein the one or more primary coils include a switch component, and wherein the microcontroller unit in the base unit periodically starts the switch component, monitors the current therein, and uses the current to sense the proximity of the receiver unit to one or more of the primary coils, and activate switching in one or more of the primary coils.
2 . The system of claim 1 , wherein the base unit includes a plurality of coils, and wherein the means for selectively activating one or more of the primary coils is used to control the on/off operation of the plurality of coils in the vicinity of the portable device or battery.
3 . The system of claim 1 , wherein the portable device or battery includes a microcontroller unit, wherein the microcontroller unit in the base unit monitors current flow, and wherein the microcontroller unit in the portable device or battery uses the current flow to provide communication between the base unit and the receiver unit for use in controlling charging.
4 . The system of claim 1 , wherein the base unit includes an additional verification step prior to activating the switching in one or more of the primary coils, to verify the identity of the portable device or battery.
5 . The system of claim 2 , wherein a plurality of coils are integrated into a pad-like charging surface and wherein the plurality of coils are used to form a coil mosaic and an effective area of charging or power that does not cover more than approximately 90% of the pad-like charging surface.
6 . The system of claim 1 , wherein a plurality of layers of coils are layered upon one another to create an effective area, and so that powering any one or a selection of the coils allows a receiver whose center is within the effective area to be charged.
7 . A system for use with a mobile device or battery for charging or powering the mobile device or battery inductively, comprising:
a base unit including:
one or more primary coils therein, the one or more primary coils having a generally planar shape so that when a current is passed through the one or more primary coils a magnetic field is generated in a direction substantially perpendicular to the plane of the one or more primary coils;
a switch means that includes a MOSFET, wherein the MOSFET automatically starts alternating switching in the one or more primary coils when the base unit detects a mobile device or battery placed close to and aligned with the one or more primary coils; and
a capacitor connected to a source or drain terminal of the MOSFET;
wherein the magnetic field inductively generates a current in a matching receiver coil or coils within the mobile device or battery placed close to and aligned with the base unit, to charge or power the mobile device or battery, and wherein the mobile device or battery includes a charging circuit having a Zener diode that clamps voltage to the mobile device or battery to a predetermined maximum voltage.
8 . The system of claim 7 wherein one or more of the primary coils are manufactured on printed circuit boards and are manufactured to have a low resistance.
9 . The system of claim 7 further comprising a battery coupled to and powering the base unit, wherein the battery can be occasionally charged by an external power supply to maintain a charge sufficient to power the base unit for a period of time.
10 . The system of claim 7 further comprising a solar cell coupled to a battery in the base unit, for charging the battery in the base unit, wherein the battery in the base unit is used to power the base unit.
11 . The system of claim 7 , wherein a plurality of base units can be interconnected to form a single unit.
12 . The system of claim 7 , further comprising means within the base unit for providing regulation, and/or verification of the charging and/or powering, including an additional switch means for adjusting and/or controlling the power into the one or more primary coils under different load conditions based on messages received by the base unit from the mobile device or battery through modulation of current in the base unit by the charging circuit of the mobile device or battery during the powering or different stages during the charging, to maintain high efficiency during the different load conditions or charging stages.
13 . The system of claim 12 , wherein the additional switch means is a zero voltage crossing or zero current crossing switch geometry, and wherein controlling of output power is achieved by changing a frequency of operation.
14 . A system for inductive powering and charging of portable devices or batteries, comprising:
a base unit, including one or more primary coils composed of a metallic material and shaped as planar spiral coils, which are capable of generating an inductive energy for use in powering or charging of portable devices or batteries;
a receiver unit, including a secondary coil also composed of a metallic material and shaped as a planar spiral coil, which is coupled to or incorporated into a portable device or battery, wherein the secondary coil receives energy inductively from one or more of the primary coils and uses it to charge or power the portable device or battery; and
means within the base unit for selectively activating one or more of the primary coils;
wherein the base unit includes a microcontroller unit; and
wherein the one or more primary coils include a switch component, and wherein the microcontroller unit in the base unit periodically starts the switch component, monitors the current therein, and uses the current to sense the proximity of the receiver unit to one or more of the primary coils, and activate switching in one or more of the primary coils.
15 . The system of claim 14 , wherein the base unit includes a plurality of coils, and wherein the means for selectively activating one or more of the primary coils is used to control the on/off operation of the plurality of coils in the vicinity of the portable device or battery.
16 . The system of claim 14 , wherein the portable device or battery includes a microcontroller unit, wherein the microcontroller unit in the base unit monitors current flow, and wherein the microcontroller unit in the portable device or battery uses the current flow to provide communication between the base unit and the receiver unit for use in controlling charging.
17 . The system of claim 14 , wherein the base unit includes an additional verification step prior to activating the switching in one or more of the primary coils, to verify the identity of the portable device or battery.
18 . The system of claim 15 , wherein a plurality of coils are integrated into a pad-like charging surface and wherein the plurality of coils are used to form a coil mosaic and an effective area of charging or power that does not cover more than approximately 90% of the pad-like charging surface.
19 . The system of claim 14 , wherein a plurality of layers of coils are layered upon one another to create an effective area, and so that powering any one or a selection of the coils allows a receiver whose center is within the effective area to be charged.