10kW 50krmin Switched Reluctance Generator and Demonstration SOW.pdf

10kW, 50kr/min Switched Reluctance Generator and Demonstration SOW

March 16, 2023

Overview:

This project would demonstrate a switched reluctance generator (SRG) sourcing 10kW of dc power at 50kr/min and deliver the generator, controller, and inverter to NASA.

The system is comprised of the following elements:

• The SRG will be a three-phase design, likely with six stator poles and four rotor poles. The magnetic design will not be optimized against any specific objectives.

• A three-phase inverter through which the SRG is excited. This inverter will be based on standard gate drive designs. The inverter design will not be optimized against any specific objectives. The nominal dc bus voltage will be set by a commercial power supply. (The commercial power supply will not be a deliverable.) The generated power will be delivered to a resistive load.

• A basic controller for the inverter that will provide capability for regulating the phase currents at low operating speeds. The SCG will be controlled through phase current amplitude and adjustment of the excitation angles relative to the maximum inductance position of the SRG.

Open loop control of the SRG will be provided. Will show how a closed-loop control for the SRG can be implemented, but we will not carry out that implementation for this demonstration.

While a controller can be developed to make use of self-sensing the SRG magnetization characteristics for purposes of position sensor elimination, no such effort will be included in this demonstration program.

• A prime mover to drive the SRG at the required speed. The prime mover would be purchased to support the demonstration. The prime mover may be a motor or engine, possibly integrated with a gearbox to provide at least 50kr/min speed with adequate power capability. A special-purpose dynamometer will be used to integrate the prime mover with the SRG. The dynamometer will not include torque sensing. Assessment of shaft power will be undertaken through analysis of the phase voltage and current waveforms.

After the system has been designed and fabrication is underway, contractor will work cooperatively with NASA to outline a preliminary path for scaling the SRG up to the megawatt class.

Approach:

The project will be carried out against the following plan:

• SRG design. This will consist of magnetic and mechanical co-design. The magnetic design will address pole shapes and numbers, stator geometry, and rotor geometry. The mechanical design will address rotor dynamics, bearings, housing, and end bells. Co-design will be necessary to keep the rotor design within the structural limits of the rotor lamination materials. Time will not be spent undertaking any significant design refinements that might address acoustic noise or torque ripple. Some features to make the rotor mechanically smooth may be considered.

Outputs from the magnetic design will include phase voltage and current waveforms that can be used to select the inverter power semiconductors. Outputs from the mechanical design will include a solid model from which the mechanical components can be manufactured.

• SRG inverter design. The outputs from the magnetic design will be used to select the power semiconductors to support a standard asymmetric bridge for exciting each SRG phase. The selected power semiconductors will be paired with appropriate gate drives. The inverter design will be reduced to a printed circuit design.

• SRG controller design. A minimum viable controller for the SRG will be designed and reduced to a printed circuit design. The controller will get SRG rotor position information through a resolver to digital converter. A magnetic resolver will be mounted to the SRG shaft for rotor position information.

• Prime mover selection. The prime mover will be selected based on suitability, availability, and cost. The selected prime mover interface to the SRG will be designed.

• Dynamometer design. The selected prime mover and SRG mechanical design will be used to form a basic special-purpose dynamometer. Guards will be added to satisfy Environmental, Health, and Safety guidelines for safe operation.

• System integration. The mechanical and electrical components will be integrated into the dynamometer.

• System test. The system controller will be tested by running the SRG as a motor (SRM) to ensure the hardware functions correctly before trying to generate power. Power will be increased in prudent steps to verify correct operation before advancing to higher power.

• System demonstration. System operation will be documented. NASA will be invited to attend a physical demonstration at contractor location prior to delivery of the system to NASA.

Program Schedule:

The program will be carried out on the following schedule, assuming a start date of mid-March.

Task

SRG Design SRG Inverter Design SRG Controller Design Prime Mover Selection Dynamometer Design Component Fabrication System Integration System Test System Demonstration

August September October November DecemberMarch April May June July