Patent ID: 12231025

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an embodiment of a system in accordance with the disclosure is shown inFIG.1and is designated generally by reference character100. Other embodiments of systems in accordance with the disclosure, or aspects thereof, are provided inFIG.2, as will be described. The systems and methods described herein can be used to provide active control of coolant in generator cooling systems.

The system100includes a control unit102with an input port104for receiving input, an electrically powered output port106, and a controller108operatively connected to receive input from the input port104, and to control output from the electrically powered output port106. The controller108includes machine readable instructions configured to cause the controller to perform methods as disclosed herein.

The control unit102is a generator control unit (GCU) configured to control the generator110, i.e., to control the windings112and rotor114for power production given mechanical rotational input to the input shaft116from a prime mover. The cooling system118is in fluid communication with the generator110to cool the generator110. The pump120of the cooling system118has an inlet122in fluid communication with a source124, e.g. a sump, of coolant and an outlet126in fluid communication to supply pressurized coolant to the cooling system118. The pump120is connected to a main shaft, i.e. input shaft116, of the generator110to mechanically drive the pump120at variable speed based on varying shaft speed of the generator110. A gear set128mechanically connects between the input shaft116and the pump120, the connection is indicated by the dashed line inFIG.1between the gear box128and the pump120, to provide a speed range for input to the pump120that is a fraction of speed range of the input shaft116. For example, the speed range can vary in a ratio of 2:1 or 10:1, where the pump spins slower than the input shaft116.

A main coolant line130connects the outlet126of the pump120to the generator110. A bypass line132is connected in fluid communication between the main coolant line130and the inlet122of the pump120. The pressure relief valve134is operatively connected to regulate flow through the bypass line132. The pressure relief valve134is operatively connected to the output port106of the control unit102for control of coolant flow through the bypass line132. The bypass line132recirculates coolant back to the inlet122of the pump120. Controlling flow through the bypass line132in turn controls how much coolant flows out of the main coolant line130to cool the generator110.

The main coolant line130includes a heat exchange output133and a heat exchange input136configured to connect the main coolant line130in fluid communication with an external heat exchanger138, which cools the coolant upstream of where the coolant is distributed to cool the generator110. The main coolant line130also includes a filter140and a delta pressure switch142at the positions indicated inFIG.1for determining when the filter140needs to be changed. An external circuit bypass line144connects in fluid communication between the main coolant line130and the sump124. An external circuit bypass valve146is included in the external circuit bypass line144so that if the oil filter140and/or heat exchanger138are plugged, the external circuit bypass valve146can relieve pump discharge pressure and avoid over pressure that could otherwise occur. The external circuit bypass line144connects to the main coolant line130at a position upstream of the heat exchange output133and downstream of the pump120. The main coolant line130includes one or more spray outlets148positioned to spray coolant onto at least one of a permanent magnet generator150of the generator110, an exciter152of the generator110, bearings154of the generator110, and/or end windings156of the generator110. The coolant sprayed from the spray outlets148returns to the source124of coolant, i.e. the sump.

Various sensors in the system100can provide input to the control unit102for controlling the pressure relief valve134. A temperature sensor158in the inlet122of the pump120can be connected to the input port104of the control unit for temperature input for controlling the pressure relief valve134. Similarly, a pressure sensor160in the main coolant line130can be connected to the input port104for pressure input to control the pressure relief valve134. It is also contemplated that inputs from the generator110can be used for control of the pressure relief valve134, such as temperature of a component of the generator110(from a temperature sensor in the generator110), frequency of rotation or speed of the generator (from a speed sensor in the generator110), and or from a current, voltage, or power sensor connected to sense electrical output of the generator110. WhileFIG.1does not depict each of the sensors for sake of clarity, the sense line162can be used to connect sensors in the generator110to the input port104of the control unit. Those skilled in the art will readily appreciate that any suitable sensors or sensor locations can be used for input to control the pressure relief valve134without departing from the scope of this disclosure.

With reference now toFIG.2, the pressure relief valve134includes a piston164slidably engaged in a housing166. An actuator168, such as a linear motor, solenoid, or the like, is connected to actuate the piston164relative to the housing166to control occlusion of an inlet172of the housing and/or of an outlet170of the housing166. Changing the position of the piston164changes how much coolant flow passes through the housing166and thus through the bypass line132ofFIG.1. The actuator168is configured to receive power from the output port106of the control unit102ofFIG.1to control position of the piston164.

A method includes pumping coolant into a cooling system, e.g. cooling system118, of a generator, e.g. generator110, while the generator is generating electrical power. The method includes regulating flow into the cooling system using a pressure relief valve, e.g. pressure relief valve134, to recirculate a portion of the coolant back to an inlet of the pump, e.g. pump120. Using the pressure relief valve includes actuating the pressure relief valve based on input from the cooling system and/or from the generator.

Actuating the pressure relief valve based on input from the cooling system and/or from the generator can includes obtaining input, e.g. from the sensors described above, based on pressure of coolant in the cooling system, temperature of coolant in the cooling system and/or on temperature of a component of the generator, based on frequency of rotation or speed of the generator, and/or based on power, current, and/or voltage generated by the generator. Actuating the pressure relief valve based on input from the cooling system and/or from the generator can include determining an output of the pressure relief valve from a look up table (LUT) correlating input from the cooling system and/or from the generator to the output of the pressure relief valve. The LUT can be in machine readable format, e.g. in a memory the controller108ofFIG.1. Pumping coolant and regulating flow can include controlling both the generator and the pressure relief valve with a generator control unit (GCU).

The following lists potential advantages of systems and methods as disclosed herein. Coolant flow can be optimized for efficiency through the speed range of the generator. By using speed, current, and temperature feedback, the flow of coolant can be controlled. This control can allow the rotor cooling to be increased or reduced for operating conditions which allows for tighter control of the oil spray in the unit. The tighter control of the oil spray in the unit can reduce windage losses in the generator and allow for higher current densities with more optimized cooling. The system can work with all speed ranges without the need for additional complexity in the oil system to limit pressure. This concept can eliminate pressure pulsations from the spring-mass effect of passive valves as a design issue in the system. The bypass valve, e.g. external circuit bypass valve146inFIG.1, can be eliminated, e.g. if a generator control unit (GCU) monitors pump discharge pressure, it could sense pressure increasing as a filter or heat exchanger plug and bypass oil back to the pump inlet using the pressure regulating valve134ofFIG.1.

The methods and systems of the present disclosure, as described above and shown in the drawings, provide for active control of coolant in generator cooling systems. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.