Company Introduction
Stator Manufacturing Process
Rotor Manufacturing process
Magnetism Testing
Equipments
Testing Ability
Here is a detailed description of a new - energy motor, taking the permanent - magnet synchronous motor (PMSM) as an example:
Basic Introduction
The PMSM is a type of synchronous motor that generates a synchronous rotating magnetic field through a permanent - magnet excitation system. It has the advantages of high efficiency, high power density, wide high - efficiency range, and high torque density. It can be applied to various variable - frequency and variable - speed fields through field - weakening control, featuring a wide speed - regulation range and fast - response capabilities.
Working Principle
The starting and operation of a PMSM are achieved through the interaction of the magnetic fields generated by the stator winding, the rotor cage winding, and the permanent magnets. When the motor is at rest, three - phase symmetrical current is supplied to the stator winding to generate a stator rotating magnetic field. The relative rotation of the stator rotating magnetic field with respect to the rotor induces a current in the cage winding, forming a rotor rotating magnetic field. The asynchronous torque generated by the interaction of the stator and rotor rotating magnetic fields causes the rotor to accelerate from rest. During this process, the rotor permanent - magnet magnetic field and the stator rotating magnetic field have different speeds, resulting in an alternating torque. When the rotor accelerates to a speed close to the synchronous speed, the speeds of the rotor permanent - magnet magnetic field and the stator rotating magnetic field become nearly equal. The stator rotating magnetic field is slightly faster than the rotor permanent - magnet magnetic field, and the torque generated by their interaction pulls the rotor into a synchronous running state. In the synchronous running state, no current is generated in the rotor winding. At this time, only the magnetic field generated by the permanent magnets on the rotor interacts with the stator rotating magnetic field to produce a driving torque. Therefore, a PMSM starts by relying on the asynchronous torque of the rotor winding. After starting, the rotor winding no longer functions, and the driving torque is generated by the interaction of the magnetic fields produced by the permanent magnets and the stator winding.
Basic Structure
- Stator: It includes the stator core and the stator winding. The stator winding is embedded in the stator core. The function of the winding is to generate a magnetic field when energized, and the core helps improve the magnetic permeability. The stator structure and working principle of a PMSM are the same as those of an AC asynchronous motor, usually in a 4 - pole configuration. The three - phase windings are arranged according to a 3 - phase 4 - pole layout, and when energized, they produce a 4 - pole rotating magnetic field.
- Rotor: The rotor is equipped with permanent - magnet poles. The permanent - magnet poles are convexly embedded on the outer side of the rotor core to form several pairs of poles. Each permanent magnet has an N - pole and an S - pole. Multiple permanent magnets and the core together form several magnetic circuits, and the direction of the magnetic force lines is from the N - pole to the S - pole. The rotor and the shaft are integrated, and both ends are installed on the casing using bearings. A cooling fan is installed at the front end of the rotor and rotates with the shaft.
Classification
According to the position of the permanent magnets in the rotor, PMSMs can be divided into surface - mounted, inset - type, and buried - type.
- Surface - Mounted PMSM: The rotor of a surface - mounted PMSM is simply formed by combining permanent magnets on the surface of the rotating shaft. Therefore, this structure has limited mechanical strength. However, from a magnetic perspective, this structure has certain advantages. Mainly because air and magnets have nearly the same magnetic permeability, the direct - axis and quadrature - axis inductances of the PMSM are equal, so there is no reluctance torque generated by the interaction between the rotor magnetic field and the stator magnetic field.
- Inset - Type and Buried - Type PMSMs: In inset - type and buried - type motors, the magnets are embedded in the rotor. This structure enhances the mechanical strength of the rotor and makes it easier to achieve field - weakening control, which is more suitable for high - speed operation. However, the main disadvantages of this structure are the existence of reluctance torque, which increases the complexity of motor torque control, and the complex installation and manufacturing process.
Advantages
Compared with induction motors, PMSMs have many advantages:
- High Power Density: They can provide a higher power - to - volume ratio. Compared with induction motors of the same power, PMSMs are smaller in size and lighter in weight.
- Good Dynamic Response: PMSMs have a smaller moment of inertia, which makes them easy to apply in fields where high - dynamic - response requirements are imposed on motor - drive systems.
- High Reliability: Without slip rings and brushes, the robustness and reliability of PMSMs are enhanced, making them more suitable for high - speed and ultra - high - speed applications.
- High Efficiency: The rotor magnetic field and the stator magnetic field of a PMSM are synchronous, and the rotor magnetic field is formed by permanent magnets without direct electrical - energy consumption. Therefore, the efficiency of PMSMs is significantly higher than that of induction motors.
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