Methods, implantable medical devices, and systems that abort a high voltage charge when a transformer is impaired
First Claim
1. A method of aborting a high voltage charge of a capacitor within an implantable medical device when a transformer of the implantable medical device that produces the high voltage charge is impaired, comprising:
- obtaining a substantially unloaded value for a battery of the implantable medical device that provides voltage across a primary coil of the transformer;
computing a dynamic threshold value based on the substantially unloaded value, a value representing a resistance of the battery, and a value representing a threshold impedance of the primary coil;
obtaining a loaded value of the battery when performing a high voltage charge; and
comparing the loaded value to the threshold value, and when the difference between the loaded value and the threshold value indicates that the transformer is impaired, then aborting the high voltage charge.
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Accused Products
Abstract
High voltage charging is aborted when it is detected that a transformer providing the high voltage charge is impaired and is providing an impedance that is too low. In one instance, a voltage for a battery that provides power to the transformer is measured when the battery is substantially unloaded and a voltage is later measured when the battery is loaded during the high voltage charge. A dynamic threshold voltage is computed based on a chosen threshold impedance representing the impedance of the transformer and based the substantially unloaded voltage and on an internal resistance of the battery. When the loaded voltage is less than the threshold voltage, then the high voltage charging is aborted.
43 Citations
20 Claims
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1. A method of aborting a high voltage charge of a capacitor within an implantable medical device when a transformer of the implantable medical device that produces the high voltage charge is impaired, comprising:
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obtaining a substantially unloaded value for a battery of the implantable medical device that provides voltage across a primary coil of the transformer; computing a dynamic threshold value based on the substantially unloaded value, a value representing a resistance of the battery, and a value representing a threshold impedance of the primary coil; obtaining a loaded value of the battery when performing a high voltage charge; and comparing the loaded value to the threshold value, and when the difference between the loaded value and the threshold value indicates that the transformer is impaired, then aborting the high voltage charge. - View Dependent Claims (2, 3, 4, 5)
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6. A method of aborting a high voltage charge of a capacitor within an implantable medical device when a transformer of the implantable medical device that produces the high voltage charge is impaired, comprising:
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obtaining an open circuit voltage of a battery of the implantable medical device that provides voltage across a primary coil of the transformer; computing a dynamic threshold voltage based on the open circuit voltage, a value representing a resistance of the battery, and a value representing a threshold impedance of the primary coil; obtaining a loaded voltage across the primary coil of the transformer when performing a high voltage charge; and comparing the loaded voltage to the threshold voltage, and when the loaded voltage drops below the threshold voltage then aborting the high voltage charge. - View Dependent Claims (7, 8, 9, 10, 11, 12)
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13. An implantable medical device, comprising:
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a battery; a transformer having a primary coil and a secondary coil; an electrical storage element connected across the secondary coil of the transformer; a switch in series between the battery and the primary coil of the transformer; a voltage measurement device that is electrically connected across the battery and that is electrically connected across the primary coil when the switch is closed; and a controller in communication with the voltage measurement device and with the switch, the controller causing the switch to open and close to begin passing current from the battery through the primary coil during a high voltage charge of the electrical storage element, wherein prior to the high voltage charge the controller communicates with the voltage measurement device to obtain an open circuit voltage of the battery and during the high voltage charge the controller communicates with the voltage measurement device to obtain a loaded voltage of the battery, wherein the controller computes a threshold voltage based on the open circuit voltage, a value representing a resistance of the battery, and a value representing a threshold impedance of the primary coil, and wherein the controller compares the loaded voltage to the threshold voltage, and when the loaded voltage drops below the threshold voltage then aborts the high voltage charge by leaving the switch open. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. An implantable medical system, comprising:
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an implantable medical lead; and an implantable medical device, comprising; a battery; a transformer having a primary coil and a secondary coil; an electrical storage element connected across the secondary coil of the transformer; a switch in series between the battery and the primary coil of the transformer; a voltage measurement device that is electrically connected across the battery and that is electrically connected across the primary coil when the switch is closed; and a controller in communication with the voltage measurement device and with the switch, the controller causing the switch to open and close to begin passing current from the battery through the primary coil during a high voltage charge of the electrical storage element, wherein prior to the high voltage charge the controller communicates with the voltage measurement device to obtain an open circuit voltage of the battery and during the high voltage charge the controller communicates with the voltage measurement device to obtain a loaded voltage of the battery, wherein the controller computes a threshold voltage based on the open circuit voltage, a value representing a resistance of the battery, and a value representing a threshold impedance of the primary coil, wherein the controller compares the loaded voltage to the threshold voltage, and when the loaded voltage drops below the threshold voltage then aborts the high voltage charge by leaving the switch open and wherein when the high voltage charge is complete, the controller causes the energy storage element to be coupled to the lead.
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Specification