CN202004611U - Cage rotor of self-starting permanent magnet synchronous motor - Google Patents

Abstract

The self-starting permanent magnet synchronous motor rotor disclosed by the utility model includes an iron core, a squirrel cage guide bar, a permanent magnet and a shaft. For the magnetic poles, an additional squirrel cage bar is provided between the rotor shaft and the squirrel cage bar, and the squirrel cage bar and the additional squirrel cage bar are respectively connected by end rings to form the first set of squirrel cages and the additional squirrel cage of the rotor respectively. The utility model can not only improve the starting performance of the self-starting permanent magnet synchronous motor, but also can effectively restrain the sharp change of the magnetic density inside the permanent magnet by adding the squirrel cage, and improve the reliability and working efficiency of the motor.

Description

A self-starting permanent magnet synchronous motor squirrel cage rotor

technical field

The utility model relates to a rotor of a self-starting permanent magnet synchronous motor.

Background technique

In recent years, self-starting permanent magnet synchronous motors have attracted more and more attention. Compared with asynchronous motors, they have high operational stability, higher efficiency and power factor than asynchronous motors of the same power level, and wide economical operating range. They are widely used in many industrial applications. It is expected to replace asynchronous motors, but the reliability of permanent magnets has become an important factor hindering the widespread application of such motors. As far as the motor body structure is concerned, the existing self-starting permanent magnet synchronous motor rotor structure can be divided into parallel, series and hybrid structures according to the placement of permanent magnets. The V-groove structure is a type of series structure, and the existing V-groove rotor core is shown in Figure 1 (taking a 4-pole motor as an example). The rotor with this structure includes iron core 1, squirrel cage guide bar 2, permanent magnet 4 and shaft 5. The iron core has grooves arranged in a V shape, and every two permanent magnets placed in the V shape groove form a magnetic pole.

Generally speaking, the starting current multiple of a self-starting permanent magnet synchronous motor is slightly larger than that of an asynchronous machine of the same power level. When starting, the stator current and the induced rotor current will generate a large demagnetization magnetic potential. The magnetic potential is evenly borne by the four permanent magnets under a pair of poles. Ideally, the permanent magnets are safe and have no risk of demagnetization. However, the existing V-shaped rotor structure is prone to distortion of the magnetic circuit, resulting in the demagnetization Most of the potential acts on the part of the permanent magnet. During the starting process, the permanent magnet is prone to local demagnetization, and it will gradually deteriorate until the permanent magnet is completely demagnetized.

This V-shaped rotor has the following problems:

1. During the starting process, the internal magnetic circuit of the rotor will be severely distorted, which may easily cause irreversible loss of magnetism locally.

2. The magnetic density in the rotor changes drastically, which increases the eddy current loss in the permanent magnet, squirrel cage and iron core, and affects the performance of the motor.

3. The mechanical stress of the rotor silicon steel sheet is relatively poor, and the radial tension of the rotor is only provided by the magnetic isolation bridge between the permanent magnet and the squirrel cage bars.

Contents of the invention

The purpose of the utility model is to provide a squirrel-cage rotor of a self-starting permanent magnet synchronous motor with high efficiency and high reliability.

The squirrel cage rotor of the self-starting permanent magnet synchronous motor of the utility model includes an iron core, a squirrel cage guide bar, a permanent magnet and a shaft. A magnetic pole, characterized in that: an additional squirrel cage bar is provided between the rotor shaft and the squirrel cage bar, and the squirrel cage bar and the additional squirrel cage bar are respectively connected by end rings to form the first set of squirrel cage and the squirrel cage of the rotor respectively. Attach mouse cage.

The above-mentioned additional squirrel cage guide bars can be square or round copper rods or cast aluminum guide bars.

The end rings of the first set of squirrel cages and the additional squirrel cages in the utility model can also be connected together to share a set of end rings.

During the starting process of the motor, when the motor slip is large, the frequency of the magnetic field in the rotor changes greatly. Due to the influence of the skin effect, no current component providing asynchronous torque is generated in the additional squirrel cage, and only the first set of squirrel cages work. Asynchronous starting torque is generated; when the slip decreases to a certain extent, the two sets of squirrel cages work together until the rotor speed reaches the synchronous speed. The additional squirrel cage produces asynchronous torque only when the rotor slip is small, so it does not affect the starting torque of the motor, but the additional squirrel cage is closer to the permanent magnet. With the change of the magnetic density in the permanent magnet, the additional The current induced in the squirrel cage will suppress the change of the magnetic density of the permanent magnet, thereby improving the reliability of the permanent magnet, and also reducing the eddy current loss of the permanent magnet and iron-zinc in the motor, and improving the performance of the motor as a whole.

The utility model has the advantages of:

1. Good starting performance

During the starting process, when the motor slip is large, the additional squirrel cage does not work, the equivalent resistance of the rotor squirrel cage is large, the starting current is small, and the torque is large. As the motor slip decreases, the additional squirrel cage gradually When it starts to function, the equivalent resistance of the rotor squirrel cage gradually decreases, ensuring the starting performance of the motor during the entire starting process.

2. High reliability and efficiency

With the addition of an additional squirrel cage, the change of magnetic density inside the motor rotor, especially in the permanent magnet, is suppressed, the rotor loss is reduced, and the anti-demagnetization ability of the permanent magnet is enhanced, thereby improving the reliability and efficiency of the motor.

Description of drawings

Fig. 1 is the existing V-shaped groove rotor core;

Fig. 2 is a radial sectional view of the rotor of the motor of the present invention.

Among the figure, 1 is an iron core, 2 is a squirrel cage guide bar, 3 is an additional squirrel cage guide bar, 4 is a permanent magnet, and 5 is an axis.

Detailed ways

Referring to Fig. 2, the rotor of the self-starting permanent magnet synchronous motor includes an iron core 1, a squirrel cage bar 2, a permanent magnet 4 and a shaft 5, and the iron core has grooves arranged in a V shape, and every two permanent magnets are placed in the V shape grooves. The magnets constitute one magnetic pole, the illustrated example has 4 magnetic poles, an additional cage bar 3 is arranged between the rotor shaft 5 and the cage bar 2, the cage bar 2 and the additional cage bar 3 are each connected by an end ring , forming the first and additional cages of the rotor, respectively. The end rings of the first set of squirrel cages and additional squirrel cages can also be connected together to share a set of end rings.

Claims (3)

1. A self-starting permanent magnet synchronous motor squirrel cage rotor, comprising iron core (1), squirrel cage guide bar (2), permanent magnet (4) and axle (5), iron core has the groove that becomes V-shaped arrangement, Every two permanent magnets placed in the V-shaped groove constitute a magnetic pole, which is characterized in that: an additional squirrel cage guide bar (3) is set between the rotor shaft (5) and the squirrel cage guide bar (2), and the squirrel cage guide bar (2) and the additional squirrel cage guide bars (3) are respectively connected by end rings to form the first set of squirrel cages and the additional squirrel cage of the rotor respectively. 2. The self-starting permanent magnet synchronous motor squirrel cage rotor according to claim 1, characterized in that: the additional squirrel cage guide bar (3) is a square or round copper rod or cast aluminum guide bar. 3. The squirrel-cage rotor of a self-starting permanent magnet synchronous motor according to claim 1, characterized in that: the end rings of the first set of squirrel-cage and the additional squirrel-cage are connected together. the

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