Turbo alternator overspeed protection circuit
AssigneeBlue Origin Manufacturing, LLC
InventorJacob Hoxsey Fenton
Life of this patent
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Abstract
Electrical circuits, systems, and methods for protecting a turbo alternator from an overspeed condition are presented. The turbo alternator may be part of a cryocooler. A system may include a brake circuit to provide voltage clamping on a DC link of the turbo alternator in case of a failure of a controller of the system to maintain the DC link voltage. If the turbo alternator speed is left uncontrolled, the DC link voltage may excessively increase. The turbo alternator may then reach an overspeed condition and destroy itself, such as by bearing failure. The brake circuit may prevent the turbo alternator from such an overspeed condition by operating in view of the DC link voltage. The brake circuit need not require any external input for control and it may be powered from the DC link bus.
Claims24
An electrical circuit for protecting a turbo alternator from an overspeed condition, the electrical circuit comprising:
- a first branch including a power converter and a DC link;
- a second branch including the turbo alternator;
- a third branch including a brake circuit;
- a node, wherein the first branch, the second branch, and the third branch are connected together at the node;
- a voltage source inverter in the second branch between the node and the turbo alternator;
- a DC link capacitance in the first branch at the node;
- a comparator in the third branch to provide a comparison between a voltage across the DC link capacitance and a threshold voltage;
- and
- circuitry in the third branch configured to allow current generated by the turbo alternator to enter the third branch, the level of the allowed current based, at least in part, on the comparison, wherein the circuitry is configured, in response to the comparison indicating that the voltage across the DC link capacitance exceeds the threshold voltage after interruption of a current path through the power converter, to divert at least a portion of the current generated by the turbo alternator away from the first branch and into the third branch, thereby imposing a braking load on the turbo alternator.
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An electrical circuit for protecting a turbo alternator from an overspeed condition, the electrical circuit comprising:
- a power converter coupled to a node, the power converter including a DC link having a capacitance;
- a voltage source inverter between the node and the turbo alternator;
- and
- a brake circuit coupled to the node and configured to divert at least a portion of current generated by the turbo alternator away from the power converter when a voltage across the DC link capacitance exceeds a threshold voltage,
- wherein the brake circuit is powered from the DC link and configured to control a level of the diverted current based, at least in part, on a comparison or difference between the voltage across the DC link capacitance and the threshold voltage, thereby imposing a braking load on the turbo alternator to limit overspeed.
Dependencies are inferred from the claim text.