RU2499343C1 - Synchronous electric motor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: synchronous electric motor comprises a magnetic conductor of a stator (2) with teeth (3), made of laminated electric steel and resting against a body (1) and has a three-phase winding (4). The rotor (5) is made in the form of a hollow cylinder and comprises ferromagnetic teeth. With the help of the non-magnetic disc (9) the rotor is fixed on the shaft (8). The inner magnetic conductor (7) of the stator (2) is made in the form of a hollow cylinder from laminated electric steel, which is fixed on the body (1) with the help of a non-magnetic bushing (10) and has radially magnetised permanent magnets (6) on the outer surface, which are arranged opposite to the teeth (3) of the stator (2) and having alternating polarity. Due to design of the rotor (5) in the form of a hollow cylinder and introduction of an additional magnetic conductor (7) of the stator with permanent magnets (6), located to the teeth (3) of the stator.

EFFECT: improved energy indices of a synchronous electric motor and its dynamic characteristics.

3 dwg

Description

The invention relates to electrical engineering, namely to synchronous motors with a jet rotor, and can be applied in electromechanical systems.

A synchronous electric motor is known having a lined stator magnetic circuit with a multiphase winding and a reactive ferromagnetic rotor. The stator winding is powered by a frequency inverter that generates a voltage system according to the required rotation speed (GB Onishchenko “Electric drive: a textbook for students of higher educational institutions.” 2nd ed., Erased. - M .: Publishing Center "Academy", 2008. - 288 p.) - [1].

Its disadvantage is the complexity of the power circuit and the large moment of inertia of the rotor.

The closest to the claimed technical solution for the design and the achieved effect is a synchronous inductor motor having a lined stator magnetic circuit with a multiphase winding and a reactive ferromagnetic rotor with pronounced poles (A.B. Vinogradov, Vector control of AC electric drives / Ivanovo State Power Engineering University named after V.I. Lenin. ”- Ivanov, 2008. - 298 p.) - [2].

Its disadvantage is the low energy performance due to the fact that the only source of magnetic field is a winding in which the power of electrical losses is released.

The technical result to which the claimed invention is directed is to increase the energy performance of a synchronous electric motor and its dynamic characteristics.

The technical result is achieved in that a synchronous electric motor containing a stator with a lined gear magnetic circuit and a multiphase winding, a reactive ferromagnetic rotor with pronounced teeth, introduces an internal stator magnetic circuit with permanent magnets located opposite the stator teeth and having alternating polarity, and the rotor is made in the form hollow cylinder with alternating ferromagnetic teeth and non-magnetic elements.

The essence of the technical solution is illustrated by drawings, where

Figure 1 is a cross section of an electric motor;

Figure 2 is a longitudinal section of an electric motor;

Figure 3 - graphs of magnetic induction in the working gap.

Figure 1-2 indicated:

1 - housing;

2 - stator magnetic circuit;

3 - stator teeth;

4 - stator winding;

5 - a rotor with teeth;

6 - permanent magnets;

7 - the internal magnetic circuit of the stator;

8 - shaft;

9 - non-magnetic disk;

10 - non-magnetic sleeve.

The magnetic circuit of the stator 2 with teeth 3 is made of burnt electrical steel. It is mounted on the housing 1 and has a three-phase winding 4.

The rotor 5 is made in the form of a hollow cylinder and has ferromagnetic teeth. Using a non-magnetic disk 9, the rotor is mounted on the shaft 8. The inner magnetic circuit 7 is made in the form of a hollow cylinder of burdened electrical steel. It is mounted on the housing 1 using a non-magnetic sleeve 10 and has on the outer surface permanent magnets 6 magnetized radially and having alternating polarity.

The phases of the stator windings A, B and C are connected to a star without a neutral wire and are powered from a constant voltage source through a pulsed semiconductor inverter made according to a bridge circuit with six power switches.

Synchronous motor operates as follows.

Figure 1 shows the position of the rotor when voltage U is applied to the phase A terminal and phase B and C terminals are connected to zero potential. A current flows through phase A, twice the currents of phases B and C. In this case, phase A turns on according to the permanent magnet opposite it, i.e. their magnetic fluxes add up. At the same time, the currents of phases B and C create magnetic fluxes directed against the fluxes of the corresponding permanent magnets. They weaken each other. Therefore, the rotor occupies a position in which its teeth close the large magnetic fluxes of phase A.

After a third of the period, the voltage U is applied to the terminal of phase B, and the terminals of phases A and C are connected to zero potential. A current flows through phase B, twice the currents of phases A and C. In this case, phase B turns on according to the permanent magnet opposite it, i.e. their magnetic fluxes add up. At the same time, the currents of phases A and C create magnetic fluxes directed against the fluxes of the corresponding permanent magnets. They weaken each other. Therefore, the rotor rotates to a position in which its teeth close the large magnetic fluxes of phase B, etc.

To consider the effectiveness of the use of permanent magnets, we assume that the permanent magnet creates a magnetomotive force F _m = 700 A, phase A has MDS F _A = 1000 A, and phases B and C have MDS F _B = F _C = 500 A.

In the gaps on the axis of the phase A, the MDS

F _AΣ = F _A + F _m = 1700 A.

In the gaps on the axes of phases B, C, MDS

F _BΣ = F _B + F _m = 200 A;

F _CΣ = F _C + F _m = 200 A.

The electromagnetic moment is determined by the formula

, $$M=\frac{F_{\mathrm{BUT}\Sigma }^2}{2}\frac{d{\Lambda }_{\mathrm{BUT}}}{d\alpha }+\frac{F_{\mathrm{AT}\Sigma }^2}{2}\frac{d{\Lambda }_{\mathrm{AT}}}{d\alpha }+\frac{F_{\mathrm{FROM}\Sigma }^2}{2}\frac{d{\Lambda }_{\mathrm{FROM}}}{d\alpha }$$

,

where Λ _A , Λ _B , Λ _C are the magnetic conductivities along the corresponding axes.

MDS squares have the meanings:

; $$F_{В\Sigma }^2=40.000{\text{ А}}^{\text{2}}$$

; $$F_{С\Sigma }^2=40.000{\text{ А}}^{\text{2}}$$

. $$F_{\mathrm{BUT}\Sigma }^2=\mathrm{2.890.000}{\text{BUT}}^{\text{2}}$$

; $$F_{\mathrm{AT}\Sigma }^2=\mathrm{40,000}{\text{BUT}}^{\text{2}}$$

; $$F_{\mathrm{FROM}\Sigma }^2=\mathrm{40,000}{\text{BUT}}^{\text{2}}$$

.

Assuming that the teeth of phases B and C act in the opposite direction, we get:

. $$F_{\mathrm{BUT}\Sigma }^2-F_{\mathrm{AT}\Sigma }^2-F_{\mathrm{FROM}\Sigma }^2=\mathrm{2.810.000}{\text{BUT}}^{\text{2}}$$

.

For an induction motor without permanent magnets, with the same winding on the stator and the power loss in it, we have:

; $$F_{В\Sigma }^2=0{\text{ А}}^{\text{2}}$$

; $$F_{С\Sigma }^2=0{\text{ А}}^{\text{2}}$$

. $$F_{\mathrm{BUT}\Sigma }^2=\mathrm{1.500.000}{\text{BUT}}^{\text{2}}$$

; $$F_{\mathrm{AT}\Sigma }^2=0{\text{BUT}}^{\text{2}}$$

; $$F_{\mathrm{FROM}\Sigma }^2=0{\text{BUT}}^{\text{2}}$$

.

The ratio of moments is 1,873, i.e. the introduction of permanent magnets increased the moment by 87.3%.

In Fig.3 shows graphs of MDS created by permanent magnets (Fig.3, a), the stator winding (Fig.3, b) and the resulting MDS (Fig.3, c).

The rotor is a thin-walled hollow cylinder with ferromagnetic teeth and has a small moment of inertia. Therefore, the electric motor allows large angular accelerations.

Thanks to the introduction of an internal stator magnetic circuit with permanent magnets located opposite the stator teeth and having alternating polarity, a synchronous motor with improved energy performance and dynamic characteristics is obtained.

Claims (1)

A synchronous electric motor containing a stator with a lined gear magnetic circuit and a multiphase winding, a reactive ferromagnetic rotor with pronounced teeth, characterized in that an internal stator magnetic circuit with permanent magnets located opposite the stator teeth and having alternating polarity is inserted, and the rotor is made in the form of a hollow cylinder with alternating ferromagnetic teeth and non-magnetic elements.

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