Electric propulsion system having integrated electrical and thermal architecture and related methods of operating and implementing same

Abstract

Electric propulsion systems, and methods of operating and implementing same, are disclosed herein. In one example embodiment, an electric propulsion system includes an electric motor, a motor drive coupled to the electric motor, and a thermal management subsystem. The electric motor is a permanent magnet synchronous motor, and the motor drive includes each of an inverter including a plurality of wide bandgap semiconductor field effect transistors (FETs), and a controller coupled at least indirectly to the FETs and configured to control the FETs by way of pulse width modulation (PWM) control. Additionally, at least a first portion of the electric motor and at least a second portion of the motor drive are cooled by the thermal management subsystem.

1 . An electric propulsion system comprising:
 an electric motor, wherein the electric motor is a permanent magnet synchronous motor;   a motor drive coupled to the electric motor, wherein the motor drive includes an annular motor drive housing within which are each of
 an inverter including a plurality of wide bandgap semiconductor field effect transistors (FETs), and 
 a controller coupled at least indirectly to the FETs and configured to control the FETs by way of pulse width modulation (PWM) control; and 
   a thermal management subsystem by which at least a first portion of the electric motor and at least a second portion of the motor drive are cooled.   
     
     
         2 . The electric propulsion system of  claim 1 , wherein the thermal management subsystem includes a first subsystem portion that is part of the electric motor, by which the first portion of the electric motor is cooled, and wherein the thermal management subsystem additionally includes a second subsystem portion that is part of the motor drive, by which the second portion of the motor drive is cooled. 
     
     
         3 . The electric propulsion system of  claim 2 , further comprising coolant, one or more heat pipes, and a plurality of fins,
 wherein the fins are arranged along exterior portions of the motor drive and motor and, during operation of the electric propulsion system, are exposed to air flow,   wherein the second subsystem portion of the thermal management subsystem operates to provide immersion cooling by way of coolant,   wherein the first subsystem portion of the thermal management subsystem provides additional cooling by way of one or more heat pipes, and   wherein each of the immersion cooling and the additional cooling occur by way of heat dissipation via the fins by which heat is extracted from the fins due to the air flow.   
     
     
         4 . The electric propulsion system of  claim 1 , wherein the thermal management subsystem operates to provide immersion two-phase cooling of the motor drive, by way of a fluid, wherein the fluid is a dielectric fluid and is positioned within an internal chamber within a motor housing of the motor drive,
 wherein each of the motor drive, motor housing, and internal chamber is substantially annular, and   wherein a liquid portion of the fluid occupies a first portion of the internal chamber substantially up to a level within the internal chamber, such that a second portion of the internal chamber is occupied by a gaseous material.   
     
     
         5 . The electric propulsion system of  claim 1 , wherein the thermal management subsystem includes a co-packaged heat exchanger, and wherein the thermal management subsystem includes at least one cooling loop and is configured to perform both liquid convection and two-phase cooling. 
     
     
         6 . The electric propulsion system of  claim 1 , wherein the thermal management subsystem includes a heat pipe having a condensing end that is positioned so as to be exposed to an airstream passing by the electric propulsion system during operation. 
     
     
         7 . The electric propulsion system of  claim 1 , wherein the thermal management subsystem includes at least one oscillating heat pipe that connects the inverter and hot regions of the electric motor with at least one condensing end so as to transport heat from the inverter and hot regions to the at least one condensing end, wherein the at least one condensing end is positioned so as to be exposed to an airstream passing by the electric propulsion system during operation. 
     
     
         8 . The electric propulsion system of  claim 1 ,
 wherein the wide bandgap semiconductor FETs of the inverter are high power, high temperature power electronics components,   wherein the controller includes low power, low temperature control electronics components,   wherein the controller is positioned vertically below the FETs,   wherein the control electronics components of the controller are cooled by liquid convection,   wherein the FETs of the inverter are cooled by both the liquid convection and also evaporative heat transfer, and   wherein the liquid convection is performed by way of a low viscosity, high dielectric strength fluid.   
     
     
         9 . The electric propulsion system of  claim 1 , wherein the motor drive is directly mounted to the electric motor, and wherein one or both of a first housing of the motor drive and a second housing of the motor includes a plurality of fins. 
     
     
         10 . The electric propulsion system of  claim 1 ,
 wherein neutrals of each winding phase of the electric motor extend outward from the electric motor separately in an open winding topology including a plurality of open windings,   wherein the motor drive has a modular H-bridge inverter structure and includes a plurality of H-bridge drives,   wherein the respective H-bridge drives govern respective amounts of power applied to respective windings of the motor, and   wherein the electrical propulsion system lacks any differential mode inductors and also lacks any common mode inductor.   
     
     
         11 . The electric propulsion system of  claim 1 , wherein the wide bandgap semiconductor field effect transistors (FETs) are Silicon Carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) and the MOSFETs are directly bonded to electrical terminals of the motor drive. 
     
     
         12 . A vehicle comprising the electric propulsion system of  claim 1 , wherein the vehicle is selected from the group consisting of an airplane, a helicopter, or a boat. 
     
     
         13 . A method of operating an electric propulsion system, the method comprising:
 providing the electric propulsion system, wherein the electric propulsion system includes an electric motor, a motor drive including an annular motor drive housing, and a thermal management subsystem by which at least a first portion of the electric motor and at least a second portion of the motor drive are cooled,   wherein the electric motor is a permanent magnet synchronous motor and wherein the motor drive is coupled to the electric motor and includes each of an inverter including a plurality of wide bandgap semiconductor field effect transistors (FETs), and a controller coupled at least indirectly to the FETs and configured to control the FETs by way of pulse width modulation (PWM) control; and   cooling at least one portion of the electric propulsion system by way of one or both of liquid convection and evaporative heat transfer.   
     
     
         14 . The method of  claim 13 , wherein the electric propulsion system has an architecture in which the electric motor and motor drive are passively cooled, without using any pumps or compressors, by which heat is removed into a surrounding airstream. 
     
     
         15 . The method of  claim 13 , wherein the cooling of the at least one portion of the electric propulsion system is performed at least in part by means for two phase change cooling. 
     
     
         16 . The method of  claim 15 , wherein the means for two phase change cooling includes one or more of (a) means for immersion cooling of the inverter, (b) heat pipes, and (c) oscillating heat pipes. 
     
     
         17 . The method of  claim 13 ,
 wherein the annular motor drive housing has an internal chamber within which are positioned the inverter, the controller, and coolant both partly in a liquid form below a level and a gaseous form above the level, and   wherein the cooling of the at least one portion of the electric propulsion system includes dissipating heat from at least one portion of the motor drive by way of the coolant, wherein the dissipating of the heat includes each of:
 experiencing the liquid convection when a first portion of the coolant that is in the liquid form is heated; 
 experiencing the evaporative heat transfer when either the first portion or a second portion of the coolant that is in the liquid form evaporates to take on the gaseous form; and 
 conducting the heat away from the coolant through the annular motor drive housing to fins arranged along an exterior surface of the annular motor drive housing, wherein the heat is carried away from the fins due to the fins being exposed to air flow. 
   
     
     
         18 . The method of  claim 17 , further comprising:
 filling at least partly the internal chamber of the annular motor drive housing with a first portion of the coolant that is in the liquid form; and   allowing at least a second portion of the coolant that is in the gaseous form to displace air from the internal chamber.   
     
     
         19 . The method of  claim 13 , wherein the motor includes a plurality of heat pipes that extend substantially between laminations of the motor and fins arranged along an exterior surface of a motor housing, and
 wherein the cooling of the at least one portion of the electric propulsion system includes dissipating heat from at least one portion of the motor by way of coolant within the heat pipes experiencing the liquid convection so that the heat is communicated to the fins, wherein the heat is carried away from the fins due to the fins being exposed to air flow.   
     
     
         20 . An electric propulsion system comprising:
 an electric motor including
 an annular motor housing including a plurality of first fins arranged along a first exterior surface of the annular motor housing, 
 a plurality of motor components including a plurality of laminations, and 
 a plurality of heat pipes extending substantially between the laminations and the annular motor housing at or proximate to the first fins; and 
   a motor drive coupled to the electric motor, the motor drive including
 an annular motor drive housing including an internal chamber and a plurality of second fins arranged along a second exterior surface of the annular motor drive housing, 
 a plurality of electronics components positioned within the internal chamber and including one or more control electronics components and one or more power electronics components, and 
 coolant positioned within the internal chamber so as to be in contact with the electronics components and with the annular motor drive housing at or proximate to the second fins, 
   wherein, during operation of the electric propulsion system, first heat is transported by the heat pipes away from the laminations for receipt by the first fins, and second heat is communicated by the coolant away from the electronics components for receipt by the second fins, the first heat being carried away from the first fins and the second heat being carried away from the second fins due to air flow passing along the electric propulsion system.