Methods and apparatus for providing a sufficiently stable power to a load in an energy transfer system

An energy transfer system for transferring power from a power supply located on a first side of a physical boundary to a variable load located on a second side of the physical boundary, the energy transfer system comprising:

• a variable load comprising an implantable medical device;
• a primary winding electrically coupled to the power supply to generate a magnetic field based on input power provided by the power supply, the magnetic field permeating the physical boundary;
• a secondary winding magnetically coupled to the primary winding via the magnetic field to form a power channel between the windings through which at least a portion of the magnetic field is received by the secondary winding the secondary winding electrically coupled to the variable load to provide output power to the variable load based on the received magnetic field;
• a first control circuit electrically coupled to the primary winding to regulate a primary voltage across the primary winding such that a sufficiently stable output power is provided to the variable load notwithstanding at least one of changes in the variable load and changes in a relative position of the primary winding and the secondary winding;
• and
• a second control circuit electrically coupled to the secondary winding to provide a detectable indication on the power channel that indicates that a load voltage across the variable load exceeds a predetermined threshold load voltage the detectable indication including at least one surge in primary amplitude and the second control circuit including a comparator to make a comparison of the load voltage to the predetermined threshold load voltage and a surge generator coupled to the comparator to generate the at least one surge based on the comparison;
• wherein the first control circuit includes a detector circuit coupled to the primary winding, to detect the detectable indication on the power channel, the detector circuit includes a surge detector, and the first control circuit regulates the primary voltage based on the detectable indication provided on the power channel.

In an energy transfer system that includes a primary winding electrically coupled to a power supply located on a first side of a physical boundary, the energy transfer system further including a secondary winding electrically coupled to a variable load located on a second side of the physical boundary, wherein power is transferred from the power supply to the variable load via a power channel and a magnetic field that couples the primary and secondary windings forms a portion of the power channel, a method of transferring power from the power supply to the variable load comprising:

• providing a variable load comprising an implantable medical device;
• comparing a characteristic of the variable load to a predetermined threshold for that characteristic on the second side of the physical boundary;
• generating a detectable indication based on the comparison for transmission across the physical boundary on the power channel by the secondary winding;
• detecting the detectable indication on the first side of the physical boundary;
• and
• regulating a primary voltage across the primary winding based on the detected indication so as to provide a sufficiently stable output power to the variable load not withstanding at least one of changes in the variable load and changes in a relative position of the primary winding and the secondary winding.

In an energy transfer system that includes a primary winding electrically coupled to a power supply located on a first side of a physical boundary, the energy transfer system further including a secondary winding electrically coupled to a variable load located on a second side of the physical boundary, wherein power is transferred from the power supply to the variable load via a power channel and a magnetic field that couples the primary and secondary windings forms a portion of the power channel, a method of transferring power from the power supply to the variable load comprising:

• providing a variable load comprising an implantable medical device;
• making a comparison of a load voltage across the variable load to a predetermined threshold load voltage on the second side of the physical boundary;
• generating a detectable indication based on the comparison for transmission across the physical boundary on the power channel by the secondary winding, generating a detectable indication including generating at least one surge in a primary amplitude of a primary voltage based on the comparison;
• detecting the detectable indication on the first side of the physical boundary, detecting, the detectable indication including detecting the at least one surge in the primary amplitude;
• and
• regulating the primary voltage across the primary winding based on the detected indication so as to provide a sufficiently stable output power to the variable load notwithstanding at least one of changes in the variable load and changes in a relative position of the primary winding and the secondary winding wherein the regulating includes increasing the primary amplitude of the primary voltage if a detector circuit does not detect the detectable indication and decreasing the primary amplitude if the detector circuit detects the detectable indication.