Design and model-free predictive current control for dual air-gap transverse-flux sensorless permanent magnet brushless direct current motors with low rare earth material

Recently, permanent magnet (PM)-brushless direct current motors (BLDCMs) have been widely used in high-performance motor drive applications, thanks to their many attractive advantages, such as higher power and torque density and efficiency, simpler motor assembly and maintenance, lower cost, acoustic noise, and vibration. However, due to cost increase rapidly and restricted exploitation of rare earth material (REM) in PMs, PM-BLDCM design at the same usage quantity of REM under limited resources become more and more important. Many researchers have presented sensorless axial-flux PM-BLDCMs because they have advantages of light-weight and small-dimension, thus they have been widely adopted in high-level servo drives, electric vehicles, and medical assist devices. In addition, model free predictive current control (MFPCC) method has insensitive to the motor parameters different form model base predictive current control (MBPCC). Current was sampled once before switching state of commutation in motor drivers, and the next state could be obtained by a minimum-cost function. It can avoid current surge when switching state. Therefore, a novel slim sensorless axial-flux PM-BLDCM with dual air-gap transverse-flux stator and low REM has designed and manufactured in this sturdy, and the MFPCC combined with a velocity controller is adopted for the proposed dual air-gap transverse-flux sensorless PM-BLDCM with low REM to improve and to achieve better current track and velocity control capability.