A Study On The Key Technique Of A Consequent-pole Bearingless Permanent Magnet Motor

The consequent-pole bearingless motor combines the excellence of the magnetic bearing and bearingless motor. The rotational angular position is not necessary in its suspension control, so the coupling of a conventional permanent-magnet-type bearingless motor between the suspension and torque control is weakened. It also avoids the compromise between radial suspension force and drive torque. Thus, it has extensive applied foreground in national defence, industry, agriculture, daily life, and so on.In this paper, a profound theoretical analysis on mechanism of magnetic levitation for a consequent-pole permanent magnet bearingless motor is presented and its mathematical model is also analyzed. In succession, a finite-element analysis model with 24 slots is built using Ansoft software. On this condition, the distribution of the magnetic field inside is simulated and the principle of magnetic levitation has been demonstrated. An in-depth simulation and analysis on the torque and suspension force has been done. The simulation results suggest that torque is in proportion to torque current and radial force is in proportion to suspension current. Meanwhile, rotational angular position is unnecessary in the magnetic suspension control, so the decoupling control of the levitation and torque can be realized. For decreasing the ripple of torque, the second analysis model with fractional slot is built, of which the stator slot number is 21. Its torque and suspension force is also analyzed. Here, by comparing the torque and radial force between the consequent-pole bearingless motor and the surface-mount bearingless motor, it is found that the suspension force of the former is much larger, when their torque is close. Thus, it avoids the compromise between radial suspension force and drive torque.On the basis of theoretical analysis and finite-element analysis, experimental study on a consequent-pole bearingless motor has been done. Construct the load experimental platform for a bearingless motor. Completed and debugged a digital control system based on TMS320F2812, including the program used to control the torque and suspension force of a consequent-pole bearingless motor. On this condition, a series of experiments could be put in process.