So how are micro motors classified? The following is an introduction to the classification of micro motors
1. We can classify according to the working power of micro motors. I believe everyone knows that there are only DC power and AC power, so according to the classification of working power, it can be divided into micro DC motors and AC motors. Like micro DC motors, the voltage is very small, generally below 24V;
2. According to the working principle, micro motors can be divided into asynchronous motors and synchronous motors. Synchronous motors can be divided into permanent magnet synchronous motors, reluctance synchronous motors and hysteresis synchronous motors. Asynchronous motors can be divided into induction motors and AC motors. The induction motor is divided into three-phase asynchronous motor, single-phase asynchronous motor and shaded-pole asynchronous motor, etc. The following is a brief introduction to the above motors.
(1) Synchronous motor
It is an AC motor that rotates at a synchronous speed by interacting with the excitation magnetic field of the DC power supply and the rotating magnetic field of the armature to generate torque.
1. Permanent magnet synchronous motor: It is a synchronous motor that generates a synchronous rotating magnetic field by excitation of a permanent magnet. The permanent magnet acts as a rotor to generate a rotating magnetic field, and the three-phase stator winding reacts through the armature under the action of the rotating magnetic field to induce a three-phase symmetrical current;
2. Reluctance synchronous motor: It is evolved from squirrel-cage asynchronous motor. Its rotor has no cage-type winding resistance, but has a reaction slot corresponding to the number of stator poles (only the role of salient poles, no excitation windings). and permanent magnets) to generate reluctance synchronous torque;
3. Hysteresis synchronous motor: It is a synchronous motor that operates with hysteresis torque generated by the action of hysteresis material rotor and stator rotating magnetic field.
(2) Asynchronous motor
It is an AC motor that generates electromagnetic torque by the interaction of the air-gap rotating magnetic field and the rotor winding induced current, thereby realizing the conversion of electromechanical energy into mechanical energy.
1. Induction motor
It refers to a motor that relies on electromagnetic induction between the stator and the rotor to induce current in the rotor to realize electromechanical energy conversion. The stator of the induction motor is composed of three parts: the stator core, the stator winding and the frame
(1) Three-phase asynchronous motor: It is a type of motor that is powered by 380V three-phase AC power supply (phase difference 120 degrees) at the same time. Because the rotor and stator rotating magnetic field of the three-phase asynchronous motor are formed in the same direction and at different speeds. Rotation, there is a slip rate, so it is called a three-phase asynchronous motor;
(2) Single-phase asynchronous motor: refers to a small-power single-phase asynchronous motor powered by a single-phase AC power supply (AC220V). Its power is designed to be relatively small, generally not greater than 2kW;
(3) Shaded-pole asynchronous motor: It is a single-phase asynchronous motor that uses a short-circuit winding set on a part of the magnetic pole to generate a rotating magnetic field and starting torque.
2. AC commutator motor
It is a three-phase AC motor with an armature winding with a commutator on the rotor. It is a constant torque AC speed regulating motor.
(1) Single-phase series-excited motor: The armature winding and the excitation winding work in series. The single-phase series-excited motor belongs to both AC and DC motors. It can work with either an AC power supply or a DC power supply;
(2) Repulsion motor: It is a single-phase AC commutator motor, which is suitable for occasions where single-phase power supply and speed regulation and steering change are required. The stator winding is powered by a single-phase power supply, and the rotor is an armature winding with a commutator short-circuited by a brush. The brushes can be moved to any desired position relative to the stator windings. By moving this position, the steering, mechanical properties and running speed of the rotor can be changed. When the brushes deviate counterclockwise from the geometric centerline, the rotor turns clockwise; when the brushes deviate clockwise from the geometric centerline, the rotor turns counterclockwise.
(3) Micro DC motor
It refers to a rotating motor whose output or input is DC power, called a micro DC motor.
1. Brushed DC motor
Fixed main magnetic poles and brushes are installed on the stator of the brushed motor, and armature windings and commutators are installed on the rotor. The electric energy of the DC power supply enters the armature winding through the brush and the commutator to generate the armature current. The magnetic field generated by the armature current interacts with the main magnetic field to generate electromagnetic torque, which makes the motor rotate to drive the load.
(1) Permanent magnet DC motor
It is a DC motor that uses permanent magnets to create a magnetic field
(a) Rare earth permanent magnet DC motor: Rare earth permanent magnet motor is a new type of permanent magnet motor that appeared in the early 1970s. Due to the high magnetic energy product and high coercivity (especially high intrinsic coercivity) of rare earth permanent magnets, The rare earth permanent magnet motor has a series of advantages such as small size, light weight, high efficiency and good characteristics;
(b) Ferrite permanent magnet DC motor: the magnetic pole body made of ferrite material has good performance and is widely used in household appliances, automobiles, toys, power tools and other fields;
(c) AlNiCo permanent magnet DC motor: it needs to consume a lot of precious metals and has a high price, but it has good adaptability to high temperature and is used in situations where the ambient temperature is high or the temperature stability of the motor is required.
(2) Electromagnetic DC Motor
It is mainly composed of stator magnetic pole, rotor (armature), commutator (commonly known as commutator), brush, casing, bearing, etc. The stator magnetic pole (main magnetic pole) is composed of iron core and excitation winding.
(a) Series-excited DC motor: the current is connected in series and divided, and the excitation winding is connected in series with the armature, so the magnetic field in this motor changes significantly with the change of the armature current. In order not to cause large losses and voltage drops in the excitation winding, the smaller the resistance of the excitation winding, the better, so the DC series motor is usually wound with a thicker wire with fewer turns.
(b) shunt DC motor: the excitation winding of the shunt DC motor is connected in parallel with the armature winding. As a shunt generator, the terminal voltage from the motor itself supplies power to the excitation winding; as a shunt motor, The excitation winding and the armature share the same power supply, which is the same as the separately excited DC motor in terms of performance.
(c) Separately excited DC motor: There is no electrical connection between the excitation winding and the armature, and the excitation circuit is supplied by another DC power source. Therefore, the field current is not affected by the armature terminal voltage or armature current.
(d) Compound excitation DC motor: The compound excitation DC motor has two excitation windings, shunt excitation and series excitation. If the magnetomotive force generated by the series excitation winding is in the same direction as the magnetomotive force generated by the shunt excitation winding, it is called product compound excitation. If the two magnetomotive forces are in opposite directions, it is called differential compound excitation.
(3) Brushless DC motor
The brushless DC motor replaces the stator and rotor of the ordinary DC motor. The rotor is a permanent magnet to generate air-gap magnetic flux; the stator is an armature, which is composed of multi-phase windings.
3. According to the starting operation mode, it can be divided into capacitor starting motor, capacitor starting motor, capacitor starting running motor and split-phase motor.
4. Induction motors used in electric fans and ventilating fans change the speed according to the needs of the load
Electric fan geared motor
The electric fan rotates in one direction and the wind is generated by the fan blades. Because the direction of rotation is fixed, the AC motor (single-phase induction motor) is directly connected to the fan blade. The AC motor changes the rotational speed according to the load. Because there are no contact parts such as brushes that become noise sources, it will rotate relatively quietly and at low speed (Note: It belongs to a brushless motor. Features: low noise and long life). AC motors are commonly used in electric fans because of their low production costs.
If you open the inside of the electric fan, you can see a few microfarads of capacitors. In the starting of an induction motor, a capacitor is necessary, which can be understood as a capacitive motor. For larger electric fans, there are ceiling fans that can be installed on the ceiling. This kind of electric fan directly installs the fan blade on the induction motor and drives directly.
Small desk fans use induction motors with shaded pole windings. In portable ultra-compact electric fans, brushed DC motors can be seen, and brushless motors can also be seen in some electric fans. There are also battery-operated electric fans that can even be called toys.
An AC single-phase induction motor is also used for a ventilation fan, a blower, and the like. The principle of air supply The principle of the Menshen fan is exactly the same. The blades rotate like a propeller to generate air flow. The blower for the purpose of cooling people is the electric fan. In addition, although induction motors are mainly used for ventilation fans and blowers, brushless motors are used for cooling fans of precision equipment and computers.
