Motor

Motor

The Motor represents the performance of a generic motor. The motor is intended to run with an efficiency map subelement, plugged into its S_map socket.

Usage

• The input design parameters that must be specified by the modeler when creating an instance of this Motor component are mass specific power (SpecificPower) and design efficiency (effDes). This component will produce mechanical power at its shaft port equal to the input electrical power at the specified voltage and frequency times its operating efficiency.

• When running ONDESIGN, this component will determine its design speed and design torque by saving off the values at the shaft port. The operating efficiency will be effDes. When running OFFDESIGN, the model will call its S_map subelement (if it exists), to look up the efficiency at the current operating point. It will then run with that efficiency.

• This component transforms power, from electrical power at its input port, to useful output (load) power. Because this component represents a transformation of power, it includes a node. Being a component including a node, its voltage is an indepedent variable. Note, there is no dependent to match with this independent within this component. Depending on the application, users may want to add a dependent on their own, that ensures that the output shaft power is equal to a demand value. Or there may be a dependent on a gas turbine component connected to the output shaft (a thrust, a shaft speed, or something else) that will balance the solver variables.

• As a component that contains a node and has its voltage known at the beginning of the solverSequence[], it uses its prePass() method to call the electrical port update function to pass this voltage information to electrical components that it is connected to. Note that in the current implementation of the NPSS Power System Library, these components containing nodes do not know what currents are going through their ports at the beginning of an iteration. Because of this, they must be connected to power transmission components (cables and breakers), and these transmission components must be run before node-bearing transformation components like this one, as the transmission components will calculate and populate these current values. Note that this design is intended to be analogous to a common approach taken in fluid networks within NPSS rocket models.

• The motor block contains variables intended to be used in a multi-design-point (MDP) simulation. This MDP logic is intended to consist of several different assemblies containing systems including this motor block; each one of these assemblies represents the same system but running at a different design point (e.g. cruise, climb, and takeoff for a fixed wing concept). To enable the solver variables that this component uses for MDP, set Option multiDes to true. Then select a mission segment that represents the most important segment of the mission to the design and give it initial guess values for design speed and torque. You will also need to disable autoSetup in ind_NDes and dep_NDesSet or otherwise remove them from all assemblies other than the main MDP one. Finally, then set up logic that copies design speed and torque from the main assembly to the other MDP assemblies before each of them run, and set up a solver pair at the top level that varies one or more of the design values in the main design assembly until conditions for that variable are met in another MDP assembly where that variable must meet a constraint. This logic is intended to allow for cases where a motor must be designed to support a maximum speed at one flight condition, but maximum torque at another. For an example on setting up this MDP logic, see baseline_turboelectricMDP.run.

• This component, like other power system components in the NPSS Power System Library, can optionally include thermal models. An optional thermal model is enabled by setting switchThermPort to TRUE, and plugging an EThermalMass subelement into the S_eThermMass socket. Doing these will add a temperature state (existing within EThermalMass) and a thermal port to the model. The thermal port is intended to connect this component to a second component that represents the mechanism by which heat is extracted from this component. This second component could represent a heat exchanger, cold plate, or just model heat transfer from the first component to the surrounding environment. For more information see EThermalMass.

• The Motor component includes sizing logic in the form of its performance map. this logic calculates mass as well as calculates the design torque and speed values. These values are used by a performance map (if one is plugged into the S_map socket) to calculate efficiency at the current operating point. For more information about performance maps for this component, see MotorGeneratorMap.int.