Электр кыймылдаткыч берүүчүлөрү Йоханнесбург 10hp моторлору
Classification of motors
Motors can be divided into DC motors and AC motors according to the type of working power supply. According to the structure and working principle, DC motor can be divided into brushless DC motor and brushless DC motor. Brushless DC motor can be divided into permanent magnet DC motor and electromagnetic DC motor. Electromagnetic DC motor is divided into series excited DC motor, parallel excited DC motor, separately excited DC motor and compound excited DC motor. Permanent magnet DC motor is divided into rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and aluminum nickel cobalt permanent magnet DC motor. Among them, AC motor can also be divided into synchronous motor and asynchronous motor. Synchronous motor can be divided into permanent magnet synchronous motor, reluctance synchronous motor and hysteresis synchronous motor. Asynchronous motor can be divided into induction motor and AC commutator motor. Induction motor can be divided into three-phase asynchronous motor, single-phase asynchronous motor and shaded pole asynchronous motor. AC commutator motor can be divided into single-phase series excitation motor, AC / DC dual-purpose motor and repulsion motor.
Chapter II characteristics and applications of classified motors
DC мотор
DC motor is a motor that operates on DC working voltage. It is widely used in tape recorders, video recorders, DVD players, electric shavers, hair dryers, electronic watches, toys and so on.
Brushless DC кыймылдаткычы
Brushless DC motor adopts semiconductor switching devices to realize electronic commutation, that is, electronic switching devices are used to replace the traditional contact commutator and brush. It has the advantages of high reliability, no commutation spark and low mechanical noise. It is widely used in high-grade recording stand, video recorder, electronic instrument and automatic office equipment.
Brushless DC motor is composed of permanent magnet rotor, multipole winding stator, position sensor, etc., as shown in figure 18-13. Position sensing converts the current of the stator winding in a certain order according to the change of the rotor position (that is, detect the position of the rotor magnetic pole relative to the stator winding, generate the position sensing signal at the determined position, control the power switch circuit after being processed by the signal conversion circuit, and switch the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by the electronic switch circuit controlled by the output of the position sensor.
There are three types of position sensors: magnetic sensitive, photoelectric and electromagnetic.
For brushless DC motor with magnetic position sensor, its magnetic sensor components (such as hall element, magnetic diode, magnetic sensitive transistor, magnetic resistor or special integrated circuit, etc.) are installed on the stator assembly to detect the change of magnetic field caused by the rotation of permanent magnet and rotor.
For the brushless DC motor with photoelectric position sensor, the photoelectric sensor is configured on the stator assembly according to a certain position, the rotor is equipped with a shading plate, and the light source is light-emitting diode or small bulb. When the rotor rotates, due to the action of the shading plate, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency.
Brushless DC motor with electromagnetic position sensor is equipped with electromagnetic sensor components (such as coupling transformer, proximity switch, LC resonant circuit, etc.) on the stator assembly. When the rotor position of permanent magnet changes, the electromagnetic effect will make the electromagnetic sensor produce high-frequency modulation signal (its amplitude changes with the rotor position).
.jpg)
Электр кыймылдаткыч берүүчүлөрү Йоханнесбург 10hp моторлору
Permanent magnet DC motor
Permanent magnet DC motor is also composed of stator magnetic pole, rotor, brush, shell, etc. the stator magnetic pole adopts permanent magnet (permanent magnetic steel), ferrite, aluminum nickel cobalt, neodymium iron boron and other materials. According to its structural form, it can be divided into cylinder type and tile type. Most of the electric used in the recorder and player are cylindrical magnets, while most of the motors used in electric tools and automotive appliances use special block magnets.
The rotor is generally made of silicon steel sheets, which has less slots than the rotor of electromagnetic DC motor. Most of the low-power motors used in the recorder and player are 3 slots, and the higher grade ones are 5 slots or 7 slots. The enameled wire is wound between two slots of the rotor core (three slots means three windings), and its joints are respectively welded on the metal sheet of the commutator. There are two kinds of conductive parts that connect with the rotor. The brush of permanent magnet motor uses single metal sheet or metal graphite brush and electrochemical graphite brush.
The permanent magnet DC motor used in the recorder and player adopts electronic speed stabilizing circuit or centrifugal speed stabilizing device.
Electromagnetic DC motor
Electromagnetic DC motor electromagnetic DC motor is composed of stator magnetic pole, rotor (armature), commutator (commonly known as commutator), brush, casing, bearing, etc,
The stator magnetic pole (main magnetic pole) of electromagnetic DC motor is composed of iron core and excitation winding. According to the different ways of excitation (called excitation in the old standard), it can be divided into series excitation DC motor, parallel excitation DC motor, separate excitation DC motor and compound excitation DC motor. Due to different excitation modes, the law of stator pole flux (generated after the excitation coil of stator pole is energized) is also different.
The excitation winding and rotor winding of series excited DC motor are connected in series through brush and commutator. The excitation current is directly proportional to the armature current. The magnetic flux of stator increases with the increase of excitation current, the torque is approximately proportional to the square of armature current, and the speed decreases rapidly with the increase of torque or current. The starting torque can reach more than 5 times of the rated torque, the short-term overload torque can reach more than 4 times of the rated torque, the speed change rate is large, and the no-load speed is very high (it is generally not allowed to operate under no-load). The speed regulation can be realized by connecting the external resistor in series (or in parallel) with the series excitation winding or connecting the series excitation winding in parallel.
The excitation winding of Shunt DC motor is connected in parallel with the rotor winding, the excitation current is relatively constant, the starting torque is directly proportional to the armature current, and the starting current is about times of the rated current. The speed decreases slightly with the increase of current and torque, and the short-time overload torque is times of the rated torque. The speed change rate is small, which is 5% ~ 15%. The speed can be adjusted by weakening the constant power of the magnetic field.
The excitation winding of separately excited DC motor is powered by independent excitation power supply, its excitation current is also relatively constant, and the starting torque is directly proportional to the armature current. The speed change is also 5% ~ 15%. The speed can be increased by weakening the constant power of the magnetic field or reduced by reducing the voltage of the rotor winding.
In addition to the shunt winding, the stator pole of the compound excitation DC motor is also equipped with a series excitation winding connected in series with the rotor winding (the number of turns is less). The direction of magnetic flux generated by the series winding is the same as that of the main winding. The starting torque is about 4 times of the rated torque, and the short-time overload torque is about times of the rated torque. The speed change rate is 25% ~ 30% (related to series winding). The speed can be adjusted by weakening the magnetic field strength.
.jpg)
Электр кыймылдаткыч берүүчүлөрү Йоханнесбург 10hp моторлору
AC синхрондуу мотору
AC synchronous motor is a constant speed drive motor. Its rotor speed maintains a constant proportional relationship with the power frequency. It is widely used in electronic instruments, modern office equipment, textile machinery and so on.
. permanent magnet synchronous motor
Permanent magnet synchronous motor belongs to asynchronous starting permanent magnet synchronous motor. Its magnetic field system is composed of one or more permanent magnets. Usually, the magnetic poles embedded with permanent magnets are installed in the cage rotor welded with cast aluminum or copper bars according to the required number of poles. The stator structure is similar to that of asynchronous motor.
When the stator winding is powered on, the motor starts to rotate according to the principle of asynchronous motor and accelerates to the synchronous speed, the synchronous electromagnetic torque generated by the rotor permanent magnetic field and the stator magnetic field (the electromagnetic torque generated by the rotor permanent magnetic field and the reluctance torque generated by the stator magnetic field) pulls the rotor into synchronization, and the motor enters synchronous operation.
Reluctance synchronous motor reluctance synchronous motor, also known as reactive synchronous motor, is a synchronous motor that generates reluctance torque by using the unequal cross axis and direct axis reluctance of the rotor. Its stator structure is similar to that of asynchronous motor, but the rotor structure is different.
. reluctance synchronous motor
Evolved from the same cage asynchronous motor, in order to enable the motor to produce asynchronous starting torque, the rotor is also equipped with cage cast aluminum winding resistance. The rotor is provided with a reaction tank corresponding to the number of stator poles (only the function of salient pole part, no excitation winding and permanent magnet) to generate reluctance synchronous torque. According to the different structure of the reaction tank on the rotor, it can be divided into internal reaction rotor, external reaction rotor and internal and external reaction rotor. Among them, the external reaction rotor reaction tank is opened to the outer circle of the rotor, so that the air gap in the direction of straight axis and quadrature axis is unequal. There are grooves inside the internal reaction rotor, so that the magnetic flux in the quadrature axis direction is blocked and the magnetic resistance is increased. The internal and external reactive rotor combines the structural characteristics of the above two rotors, and the difference between the direct axis and the quadrature axis is large, so that the force energy of the motor is large. Reluctance synchronous motors are also divided into single-phase capacitor operation type, single-phase capacitor starting type, single-phase double value capacitor type and other types.
.jpg)
Электр кыймылдаткыч берүүчүлөрү Йоханнесбург 10hp моторлору
. hysteresis synchronous motor
Hysteresis synchronous motor is a synchronous motor that uses hysteresis materials to produce hysteresis torque. It is divided into inner rotor hysteresis synchronous motor, outer rotor hysteresis synchronous motor and single-phase shaded pole hysteresis synchronous motor.
The rotor structure of internal rotor hysteresis synchronous motor is hidden pole type, the appearance is a smooth cylinder, there is no winding on the rotor, but there is an annular effective layer made of hysteresis material on the outer circle of the iron core.
After the stator winding is powered on, the generated rotating magnetic field causes the hysteresis rotor to produce asynchronous torque and start rotation, and then it is pulled into the synchronous operation state by itself. When the motor operates asynchronously, the stator rotating magnetic field magnetizes the rotor repeatedly with slip frequency; During synchronous operation, the hysteresis material on the rotor is magnetized and permanent magnetic poles appear, resulting in synchronous torque.
AC асинхрондуу мотор
AC asynchronous motor is a leading AC voltage motor, which is widely used in electric fans, refrigerators, washing machines, air conditioners, hair dryers, vacuum cleaners, range hoods, dishwashers, electric sewing machines, food processing machines and other household appliances, as well as all kinds of electric tools and small-scale electrical equipment.
The speed of the motor (rotor speed) is less than the speed of the rotating magnetic field, so it is called asynchronous motor. It is basically the same as induction motor. s=(ns-n)/ns。 S is the slip rate, NS is the magnetic field speed, and N is the rotor speed.
Basic principle: (1) when the three-phase asynchronous motor is connected to the three-phase AC power supply, the three-phase stator winding flows through the three-phase magnetomotive force (stator rotating magnetomotive force) generated by the three-phase symmetrical current and generates a rotating magnetic field.
(2) The rotating magnetic field has relative cutting motion with the rotor conductor. According to the principle of electromagnetic induction, the rotor conductor generates induced electromotive force and induced current.
(3) According to the law of electromagnetic force, the current carrying rotor conductor is affected by electromagnetic force in the magnetic field to form electromagnetic torque and drive the rotor to rotate. When there is a mechanical load on the motor shaft, it will output mechanical energy outward.
Single phase asynchronous motor
Single phase asynchronous motor is composed of stator, rotor, bearing, casing, end cover, etc.
.jpg)
Электр кыймылдаткыч берүүчүлөрү Йоханнесбург 10hp моторлору
The stator is composed of base and iron core with winding. The iron core is formed by punching and laminating silicon steel sheets. Two sets of main windings (also known as running windings) and auxiliary windings (also known as starting windings) with an electrical angle of 90 ° are embedded in the slot. The main winding is connected to AC power supply, and the auxiliary winding is connected to centrifugal switch s or starting capacitor, running capacitor, etc. in series, and then connected to power supply.
The rotor is a cage cast aluminum rotor. After the iron core is laminated, aluminum is cast into the groove of the iron core, and the end ring is cast together to short circuit the rotor guide bar into a squirrel cage.
Single phase asynchronous motor is divided into single-phase resistance starting asynchronous motor, single-phase capacitor starting asynchronous motor, single-phase capacitor running asynchronous motor and single-phase double value capacitor asynchronous motor.
2 three phase asynchronous motor
The structure of three-phase asynchronous motor is similar to that of single-phase asynchronous motor. Three-phase windings (single-layer chain type, single-layer concentric type and single-layer cross type) are embedded in the stator core slot. After the stator winding is connected to the three-phase AC power supply, the rotating magnetic field generated by the winding current generates induced current in the rotor conductor. Under the interaction of induced current and air gap rotating magnetic field, the rotor generates electromagnetic rotating cabinet (i.e. asynchronous rotating cabinet) to rotate the motor.
Көлөкөлүү түркүк мотор
Shaded pole motor is the simplest one of unidirectional AC motors. Cage type inclined slot cast aluminum rotor is usually used. According to the different shape and structure of stator, it is divided into salient pole covered pole motor and hidden pole covered pole motor.
The stator core of salient pole shaded pole motor is a square, rectangular or circular magnetic field frame, the magnetic poles are protruding, and each magnetic pole is provided with one or more short-circuit copper rings that play an auxiliary role, namely shaded pole winding. The concentrated winding on the salient pole is used as the main winding.
The stator core of hidden pole shaded pole motor is the same as that of ordinary single-phase motor. Its stator winding adopts distributed winding, and the main winding is distributed in the stator slot. The shaded pole winding does not need short-circuit copper ring, but is wound into distributed winding with thick enamelled wire (self short circuit after series). It is embedded in the stator slot (about 2 / 3 of the total number of slots) and plays the role of auxiliary group. The space between the main winding and the cover pole winding is at a certain angle.
When the main winding of the shaded pole motor is energized, the shaded pole winding will also generate induced current, so that the magnetic flux of the stator pole covered by the shaded pole winding and the uncovered part rotate in the direction of the covered part.
.jpg)
