Date
05/01/2014
PDF
In this episode of PSDtv - Applications like aerospace, automotive and robotics require high torque to volume/weight ratio machines. Over a decade, the Permanent Magnet Machine has been considered to be the sole candidate, however, the limitation of the operational temperature, relatively high price, and unstable oversea supply of permanent magnet material limits its massive applications. There arises the need for a high torque density machine which is free of permanent magnets.
Conventional Reluctance machine benefits from a relatively simple and rugged structure which make it a conveniently manufactured low cost machine. It has an extend speed range, fault tolerant and modular configuration and the capability of operation in harsh ambient condition. The limited torque density and the acoustic noise during operation are the main obstacles against its replacement for both induction machines and permanent magnetic machines.
Technology
The invented motor has a novel, optimized pattern of magnetic flux paths within the electrical machine which yields a superior performance. It has at least twice the torque density of conventional switched reluctance machines. Two stators inside machine cancel the radial force which is the main reason for noise during operation. The shell type rotor results in dramatically smaller inertia. The motor maintains the fault tolerance and the extended speed range capability. In addition, the machine can operate without a position sensor in a wide speed range unlike the permanent magnet machines.
In this episode of PSDtv is showing a thermal test of the water cooled Double Stator Switched Reluctance Machine (in silver) running with 30 N.m of load at 700 rpm. Water is injected into the inner and outer stator with a flow speed of 3 liters/minute. In this video, we reached 9 A/mm^2 of the current density for continuous operation.
