Ac synchronous motor has good performance, but its poor startup performance; Ac induction motor has the characteristics of simple structure, reliable operation, but its poor regulation performance; The regulation of dc motor because of its good performance and startup performance and application of industry widely. For a brush dc motor, however, due to the existence of commutator brush mechanical contact, lead to high cost, accompanied by commutation spark, electromagnetic interference, short service life and reliability problems, which limits the scope of its use. For a long time, people want to be able to maintain a good regulation performance of brushless dc motor and the premise of startup performance, eliminate the disadvantages. After a long time, has realized the electronic steering (Instead of mechanical steering); The original in internal rotation of the motor armature into under external stationary armature; At the same time, the in the static magnetic field of the motor outside into the inside of the motor rotating magnetic field, the end result is there will be a brush dc motor turned into brushless dc permanent magnet motor. Brushless direct water magnetoelectric motive and a brush dc motor brushless dc permanent magnet motor is in a brush dc motor developed on the basis of. Analysis from the macro, brushless dc permanent magnet motor and brushless dc motor with the same operation mechanisms: the voltage on the motor are constant dc voltage, the input of the motor current is dc current, the effect on the armature coil voltage polarity and through the armature coils of alternating current direction, the armature coil in the induction emf waveform is basically similar, alternating direction. As a result, our design ideas and design methods of both hold is basically consistent, just some specific calculation is slightly different. Brushless permanent magnet dc motor and brushless dc motor although has the same running mechanism, but there are certain differences in performance: 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 is always in a state of orthogonal variable, and brushless dc motor pole magnetic field and the armature magnetic field changes within a certain Angle position all the time, orthogonal state is one of the instantaneous position only. So, in other conditions the same situation, in the process of running, the torque ripple of brushless dc motor (BLDCM) 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 is a pole magnetic field produced by permanent magnet rotor. When going into three phase current in three-phase motor winding, and in the air gap of the stator inner cavity inside a rotating armature magnetic field generated. Permanent magnet synchronous motor applied general ac permanent magnet synchronous motor is in microelectronic devices, power electronics, communication technology, computing technology and modern control technology, under the support of realizing brushless synchronous, namely the general ac permanent magnet synchronous motor to control type permanent magnet synchronous motor. Obtain and good regulation performance similar to the traditional dc motor startup performance; However, motor ontology electro-magnetic relations and internal mechanism basically unchanged. General ac permanent magnet synchronous motor, therefore, the design concept and calculation method of basically apply to general control type permanent magnet synchronous motor, but according to the requirements of the different design, designers must take different implementation strategies and plans. Self-control type permanent magnet synchronous motor with brushless dc permanent magnet motor, in terms of motor ontology, basically has the same structure: three-phase armature winding is set on the stator, set up permanent magnet poles on the rotor. At present, various types of permanent magnet motor is widely applied to various fields of national economy, such as household appliances, machinery, automobile industry, papermaking industry, textile industry, precision machine tool industry and military industry and other manufacturing areas has been widely used, and is in the developing stage.
