Learn About PM Motor Generators
Permanent magnet (PM) motor generators consist of two basic parts: a stator coil, powered by an alternating current which creates an electric field, and a rotor, made of high permeability magnetic material which rotates within that field. Today’s PM machines employ the latest technology in high strength rare earth magnetic materials to achieve high power density and efficiency. The former leads directly to minimum physical size at all power levels when compared with other motor types; the latter leads to significant improvements in overall system efficiency.
Calnetix Technologies currently uses two primary types of rotor construction to provide high-speed rotating assemblies in mass production. Containment is provided by either a high-strength metal sleeve or a proprietary advanced graphite-composite sleeve for top speeds in excess of 1,200 feet per second. Both offer unique advantages to the system and motor generator performance. Calnetix selects the optimum approach to meet system performance goals and is experienced in utilizing both approaches in development and production.
Other rotor design criteria include operating temperatures, type of bearings employed, stiffness required, operating bending modes and operating gas or liquid medium. Calnetix addresses all these factors when designing PM machines, and thoroughly understands the required characteristics of the rotor for each application or working environment.
Calnetix applies PM motor technology over an expansive speed range to address a broad spectrum of application requirements. Designs that operate over 450,000 rpm have been achieved, with 30,000 to 100,000 rpm being the typical operating range for Calnetix machines. Available in air-cooled or liquid-cooled configurations, these machines offer:
- Robust rotor construction, maximizing rotor stiffness for higher bending mode frequencies
- Fewer rotor poles, reducing stator losses by lowering drive frequency requirements
- The latest technology in stator lamination materials to minimize stator iron losses
The following attributes apply to all Calnetix PM motor generator system designs:
