Over voltage protection for electric machines
AssigneePratt & Whitney Canada Corp.
InventorKevin A. Dooley
Life of this patent
Estimating the term…
Abstract
A system and method for protecting an electrical power generation system from an over-voltage. The output voltage of a multi-phase rectifier, operatively connected between the output terminals of an electric machine and a load, is monitored. The input of the multi-phase rectifier is short-circuited upon detection that the output voltage has reached a threshold voltage. Removal of the short-circuiting of the input of the multi-phase rectifier is synchronized with a substantially zero-crossing of phase current flowing through switching devices in the rectifier once the output voltage is no longer above the threshold voltage.
Claims16
An electrical power generation system with over-voltage protection comprising:
- a multi-phase alternating current generating electric machine having output terminals;
- a multi-phase rectifier operatively connected between the output terminals of the electric machine and a load, the rectifier comprising a set of low side switching devices connected between the output terminal and a ground and a set of high side switching devices connected between the output terminals and a positive voltage source;
- a voltage sensing device operatively connected to an output of the rectifier for sensing an output voltage of the rectifier;
- at least one current sensing device operatively connected to the phases of the multi-phase alternating current generating electric machine;
- and
- a power control unit for generating a signal that switches the low side switching devices to an on state when the output voltage of the rectifier reaches a threshold voltage, and for generating independent signals that switch a corresponding one of the low side switching devices back to an off state when the alternating current flowing therethrough is substantially zero and the output voltage of the rectifier is no longer above the threshold voltage.
A method for protecting an electrical power generation system from an over-voltage comprising:
- monitoring an output voltage of a multi-phase rectifier operatively connected between output terminals of an electric machine and a load;
- short-circuiting an input of the multi-phase rectifier upon detection that the output voltage has reached a threshold voltage;
- and
- synchronizing removal of the short-circuiting of the input of the multi-phase rectifier with a substantially zero-crossing of phase current flowing through switching devices in the rectifier once the output voltage is no longer above the threshold voltage.
An apparatus for protecting an electrical power generation system from an over-voltage comprising:
- means for monitoring an output voltage of a multi-phase rectifier operatively connected between output terminals of an electric machine and a load;
- means for short-circuiting an input of the multi-phase rectifier upon detection that the output voltage has reached a threshold voltage;
- and
- means for synchronizing removal of the short-circuiting of the input of the multi-phase rectifier with a substantially zero-crossing of phase current flowing through switching devices in the rectifier once the output voltage is no longer above the threshold voltage.
Dependencies are inferred from the claim text.