Dc motor ac synchronous motor has outstanding operation function, but the poor start function; Ac induction motor with structure brief, stable operation characteristics, but its regulating function is poor; Dc motor control function and start because of its outstanding function is widely used by industry. For brushless dc motor has, however, because of commutator brush mechanical touch group, lead to high cost, accompanied by commutation spark, electromagnetic interference, short service life and strong sexual problems, and thus limit the scope of its use. Keep the brushless dc motor has outstanding regulating function and start function under the premise of eliminate its shortcomings. Through a long time, completed the electronic commutation,To replace the mechanical commutation)； The change in internal rotation of the motor armature to original under external stop armature; Against placed outside of the motor stop rotating magnetic field, magnetic field changes into motor internal brushless dc motor is the end result will be changed into a brushless dc motor. Brushless direct water magneto brushless dc motor with a comparison of brushless dc motor and brushless dc motor is although the operational principle of the same but there are certain differences in terms of functioning: a brush dc motor armature winding number of elements and commutator commutator segment number more than the number of phase brushless dc motor armature winding; In the process of operation, has a brush dc motor pole magnetic field and the armature magnetic field has been in the orthogonal variable condition, and brushless dc motor pole magnetic field and the armature magnetic field has been a particular view azimuth range change, orthogonal condition is only in an instantaneous azimuth. In other conditions under the same condition, therefore, in the process of operation, the torque ripple of brushless dc motor (BLDCM) is greater than a brush dc motor torque ripple; Brushless dc motor of the electromagnetic torque is smaller than a brush dc motor electromagnetic torque. Ac permanent magnet synchronous motor inside there are two magnetic fields: one is the armature magnetic field, the other one is by the rotor magnetic field of permanent magnet poles. When going into three phase current in three-phase motor winding, and in the air gap of the stator inner cavity in a rotating armature magnetic field. Permanent magnet synchronous motor using the & # 8203; General ac permanent magnet synchronous motor is in microelectronics equipment, power electronics equipment, variable flow technology, computing technology and modern control technology, under the support of complete self synchronous brushless, namely the general ditch ac magnetic synchronous motor change become self-control type permanent magnet synchronous motor. Get the same as the traditional dc motor control function and prominent hair can start; However, motor ontology electromagnetic relationship and operation mechanism of internal basically unchanged. Channel communication, therefore, the general planning concept and calculation method of the synchronous motor is basically suitable for self-control type permanent magnet synchronous motor, according to different technical requirements, only planners must adopt different strategies and plans. Self-control type permanent magnet synchronous motor with brushless dc motor, in terms of motor ontology, basically have the same structure: three-phase armature winding is set on the stator, set up permanent magnet poles on the rotor. Now, various types of permanent magnet motor widely used in various fields of national economy, for example in household appliances, condition, machinery, automobile industry, papermaking industry, textile industry, precision machine tool industry and military industry and other manufacture domain has been widely used, and is in the developing stage.
