Motor classification and selection
First, the classification of the motor
1. According to the type of working power: can be divided into DC motor and AC motor.
1) DC motors can be divided according to structure and working principle: brushless DC motor and brushed DC motor.
Brushed DC motors can be divided into: permanent magnet DC motors and electromagnetic DC motors.
Electromagnetic DC motor division: series-excited DC motor, shunt DC motor, separately excited DC motor and compound excitation DC motor.
Permanent magnet DC motor division: rare earth permanent magnet DC motor, ferrite permanent magnet DC motor and AlNiCo permanent magnet DC motor.
2) Among them, AC motors can also be divided into: single-phase motors and three-phase motors.
2. According to the structure and working principle can be divided: can be divided into DC motor, asynchronous motor, synchronous motor.
1) Synchronous motors can be divided into: permanent magnet synchronous motors, reluctance synchronous motors and hysteresis synchronous motors.
2) Asynchronous motors can be divided: induction motors and AC commutator motors.
Induction motors can be divided into three-phase asynchronous motors, single-phase asynchronous motors and shaded-pole asynchronous motors.
The AC commutator motor can be divided into: single-phase series-excited motor, AC-DC motor and repulsive motor.
3. According to the starting and running modes, it can be divided into: a capacitor-starting single-phase asynchronous motor, a capacitor-operated single-phase asynchronous motor, a capacitor-starting single-phase asynchronous motor, and a split-phase single-phase asynchronous motor.
4. It can be divided according to the purpose: drive motor and control motor.
1) Drive motor can be divided: electric tools (including drilling, polishing, polishing, grooving, cutting, reaming, etc.) with electric motors, household appliances (including washing machines, electric fans, refrigerators, air conditioners, recorders, video recorders) , motors, vacuum cleaners, cameras, hair dryers, electric razors, etc.) Motors and other general-purpose small mechanical equipment (including various small machine tools, small machinery, medical equipment, electronic equipment, etc.).
2) The control motor is divided into: a stepping motor and a servo motor.
5. According to the structure of the rotor can be divided: cage induction motor (the old standard is called squirrel cage asynchronous motor) and wound rotor induction motor (the old standard is called wound asynchronous motor).
6. According to the operating speed can be divided: high-speed motor, low-speed motor, constant speed motor, speed control motor. Low-speed motors are further classified into gear reduction motors, electromagnetic reduction motors, torque motors, and claw-pole synchronous motors.
The speed regulating motor can be divided into a stepped constant speed motor, a stepless constant speed motor, a stepped variable speed motor and a stepless variable speed motor, and can also be divided into an electromagnetic speed regulating motor, a DC speed regulating motor, a PWM variable frequency speed regulating motor and Switched reluctance motor.
The rotor speed of an asynchronous motor is always slightly lower than the synchronous speed of the rotating magnetic field.
The rotor speed of the synchronous motor is always kept at the synchronous speed regardless of the load size.
Second, how to choose the right motor
The basic requirements for motor selection are: the type of load being driven, rated power, rated voltage, rated speed, and other conditions. Load type is divided into DC motor, asynchronous motor, synchronous motor
1. The production machine with stable load and continuous operation without special requirements for starting and braking should use ordinary squirrel-cage asynchronous motor, which is widely used in machinery, water pump and fan.
2. Starting and braking are frequent, and production machinery with large starting and braking torque is required, such as bridge cranes, mine hoists, air compressors, irreversible rolling mills, etc., and wound-wound asynchronous motors should be used.
3. If there is no speed regulation requirement, if the speed is constant or the power factor is required to be improved, synchronous motors, such as medium and large capacity pumps, air compressors, hoists, mills, etc., should be used.
4. For the production machinery with the speed regulation range of 1:3 or above and continuous stable and smooth speed regulation, it is better to use the separately excited DC motor or the squirrel cage asynchronous motor or synchronous motor with variable frequency speed regulation, such as large precision machine tools and gantry. Planer, rolling mill, hoist, etc.
5. It is required to produce a machine with large starting torque and soft mechanical characteristics, using series or compound excitation DC motors, such as electric cars, electric cars, heavy cranes, etc.
In general, the motor is provided with the type of load that is driven, the rated power of the motor, the rated voltage, and the rated speed to roughly determine the motor. But if you want to optimally meet the load requirements, these basic parameters are far from enough. The parameters that need to be provided include: frequency, working system, overload requirement, insulation level, protection level, moment of inertia, load resistance torque curve, installation method, ambient temperature, altitude, outdoor requirements, etc., according to specific conditions.
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