Dc motor major Shared today about dc motor of the three aspects: basic structure and operation principle of the dc motor and classified information. Dc motor depend on dc operating voltage of motor operation, widely used in the tape recorder, video recorder, VCD, electric shavers, hair dryer, digital watches, toys, etc. The basic principle of dc motor based on electromagnetic induction, the same as the asynchronous motor is consisting of stator and rotor. The basic structure of the dc motor, dc motor consists of two parts, the stator and rotor, which has a certain air gap. Dc motor stator is made up of frame, main pole, reversing the poles, front and back end cover and brush holder and other parts. In the main pole is a major part of the dc motor air-gap magnetic field, by permanent magnets or laminated core with dc excitation winding. Dc motor rotor is composed of the armature, commutator,Also known as the commutator)And shaft parts. Meanwhile the armature consists of two parts, the armature iron core and the armature winding. Armature iron core is made of silicon steel sheet pile in its external circular uniformly distributed at the tooth, the armature winding is put in the tank. Commutator is a mechanical rectifier unit. After the commutator segment lay in cylindrical, with metal clip or plastic molding as a whole. The insulating riser interdependence. Quality has a great influence on the operation reliability of commutator. Second, the work principle of the dc motor dc from brush the semicircle commutator segment into the coil (BThe armature winding)c -d -b -A, based on the left hand rule, coil CD section and the stress of the ab section as shown in figure of F, clockwise torque T occur, the speed of the coil to n clockwise rolling, no matter how coil rolling, always S extremely useful side into the direction of current, n very useful to the edge of the current direction. After the motor armature winding current continue to rotate clockwise. When the coil rotates unceasingly, although with two coil side brush touch changing, brush has always been A positive potential, brush B is always negative potential. When ab section in the N pole coil, coil current direction is c -d -b -A, when ab section in the S pole coil current direction is a -b -d -C, that is, the current in the coil the abcd direction alternating. The two pieces of copper is called the reversing semicircle, they together is called the commutator. Three, the classification of the dc motor rotor dc motor consists of stator poles, (The armature), commutator and brush, chassis, bearing, magnetic dc motor stator poles (Main pole)Made up of core and field winding. According to the field (The old specification called excitation)Methods and can be divided into different series dc motor, shunt dc motor, separately excited dc motor and dc motor in the compound. On the basis of different excitation method, the stator magnetic flux (By the excitation coil of the stator pole) in the aftermath of the electricityThe rules are different. Series dc motor excitation winding and rotor winding in series between the brush and commutator, excitation current is proportional to the armature current, the stator flux increases with the increase of excitation current and torque is proportional to the square of the approximation and the armature current, rotate speed along with the adding of torque or current agile. The starting torque can reach more than 5 times of additional torque, short time overload torque can reach more than four times that of additional torque and rotational speed change ratio is larger, high no-load speed,Generally does not allow its under no-load running)。 Can be used after topical series resistor and series winding (Or parallel), or in parallel and series winding to achieve speed control. Shunt dc motor excitation winding and rotor winding are parallel, the exciting current is stable, starting torque is proportional to the armature current, the starting current is about 2 additional current. About five times. Speed increases with the increase of current and torque and slightly down, short-time overload torque for 1 additional torque. 5 times. Speed change rate is small, 5% ~ 15%. But after the constant power to speed control of magnetic field. Separately excited dc motor excitation winding of receiving independent of the excitation power supply, the exciting current is stable, the starting torque is proportional to the armature current. Speed change is 5% ~ 15%. Able to progress after diluted magnetic field constant power speed or decrease voltage to make the speed of the rotor winding. Compound on dc motor stator pole except a shunt winding, also equipped with series winding and rotor winding in series (The number of turns less)。 Series winding in the direction of the magnetic flux and the main winding magnetic flux in the same direction, the starting torque is about 4 times the left and right sides of additional torque, short time overload torque for 3 additional torque. About five times. The speed change rate was 25% ~ 30% (Related to the series winding)。 Speed can be adjust after diluted magnetic field strength.
