Robot servo motor based on magnetism assisting characteristic

Abstract

The invention discloses a robot servo motor based on magnetic assistance characteristics, which comprises a stator core, a rotor core and magnetic steel, the stator core comprises laminated stator punching sheets and windings, the rotor core comprises multiple layers of laminated rotor punching sheets, spoke type magnetic steel grooves and multiple layers of air magnetic barriers are arranged on the rotor punching sheets, and the magnetic steel is arranged in the magnetic steel grooves; the multiple layers of air magnetic barriers comprise a plurality of arc-shaped magnetic barriers symmetrically arranged on the two sides of the magnetic steel grooves, the arc-shaped magnetic barriers comprise a first arc-shaped magnetic barrier, a second arc-shaped magnetic barrier, a third arc-shaped magnetic barrier and an interelectrode arc edge triangular large magnetic barrier, and a rotor excircle magnetic barrier is arranged at the top of each spoke type magnetic steel groove on the rotor punching sheet. The motor has the advantages that the anti-demagnetization performance and the torque output stability of the motor can be improved while the heat dissipation area of the motor is not changed and the cost of the motor is not additionally increased.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a robot servo motor based on magnetic assist characteristics. Background Art

[0002] With the development of science and technology and the progress of the times, industrial robots have gradually begun to replace human work in various fields, especially in some harsh working environments, which are mostly high temperature, strong vibration noise, high corrosion, etc. Among them, the servo motor, as the core component and power output unit of the industrial robot, must have higher stability, accuracy and overload capacity. However, in harsh working environments, the output performance of the servo motor will be seriously affected, especially in high temperature environments, such as next to steelmaking boilers, metal forging and other environments, which will cause the risk of irreversible demagnetization of the magnetic steel of the permanent magnet motor, resulting in reduced motor overload capacity and even motor burnout and other safety issues. In order to reduce the risk of irreversible demagnetization caused by high temperature, the existing main technology is more to improve the heat dissipation capacity of the motor to solve it, but most of the robot's servo motors use IC410 natural cooling, and even more are installed in the robot cavity in a fully enclosed and highly protected form, so for robot-specific motors, the effect of reducing the temperature rise of the motor by improving the external heat dissipation capacity is generally not good. In addition, if a heat dissipation device such as a fan or water cooling is added, the cost of the motor system will inevitably increase significantly, which will reduce the economy of the robot product.

[0003] Chinese patent CN 111799928 B discloses an industrial robot motor housing with heat dissipation function. The invention forms a motor external forced cooling function by adding a housing with a heat dissipation fan to the robot motor, so as to achieve the purpose of reducing the robot motor temperature and preventing high-temperature demagnetization of the magnetic steel. However, this method only considers the effect of forced heat dissipation and cooling of the motor, and does not consider the installation space of the industrial robot and the cost of the robot.

[0004] Chinese patent CN 105680628 B discloses a high power ratio self-circulating liquid-cooled permanent magnet motor. This invention adds a liquid cooling device to the outside and uses the motor rotor to drive the pump impeller. The self-circulating coolant drives the temperature of the motor rotor to reduce the risk of demagnetization of the motor permanent magnet. However, this structure is complex and costly, and the rotor driving the pump impeller will increase the motor loss, especially the stator winding copper loss, thereby increasing the temperature rise of the motor stator winding and reducing the overall efficiency of the motor.

[0005] Chinese patent CN 113364181 B discloses an inverse convex rare earth permanent magnet synchronous motor rotor and its motor. The invention achieves the purpose of the motor's magnetic assist characteristics by setting multiple permanent magnet groups and air slot groups on the rotor, so as to reduce the motor's dependence on rare earth permanent magnets and reduce the demagnetization characteristics of non-rare earth permanent magnets during weak magnetic control of the motor. However, multiple large air slots are opened on the outer circle of the motor rotor, which will inevitably reduce the torque output performance of the motor and reduce the power density of the motor, and is not suitable for robot servo motors. Summary of the invention

[0006] The present application provides a robot servo motor based on magnetic assist characteristics, which has the advantage of improving the motor's anti-demagnetization performance and torque output stability without changing the motor's heat dissipation area or increasing the motor's cost.

[0007] The above-mentioned object of the present application is achieved through the following technical scheme: a robot servo motor based on magnetic assist characteristics, comprising a stator core, a rotor core and magnetic steel, wherein the stator core comprises stacked stator punchings and windings, and the rotor core comprises multiple layers of stacked rotor punchings, wherein the rotor punchings are provided with spoke-type magnetic steel slots and multiple layers of air magnetic barriers, and the magnetic steel is arranged in the magnetic steel slots;

[0008] The multi-layer air magnetic barrier comprises a plurality of arc-shaped magnetic barriers symmetrically arranged on both sides of the magnetic steel slot.

[0009] Furthermore, the arc-shaped magnetic barrier includes arc-shaped magnetic barrier No. 1, arc-shaped magnetic barrier No. 2 and arc-shaped magnetic barrier No. 3. The three arc-shaped magnetic barriers are concentric arcs. The radii of the three arc-shaped magnetic barriers increase successively, and the lengths of the three arc-shaped magnetic barriers increase successively from the outer circle to the inner circle of the rotor.

[0010] Furthermore, the multi-layer air magnetic barrier also includes a large inter-pole arc-edge triangular magnetic barrier, which is arranged between two adjacent magnetic steel slots, and its two side edges facing the arc magnetic barrier are arc-shaped and concentric with the opposite arc magnetic barrier.

[0011] Furthermore, a rotor outer circle magnetic barrier is provided on the top of each spoke-type magnetic steel slot on the rotor punching sheet, and the rotor outer circle magnetic barrier is a structure in which the rotor outer circle is concave.

[0012] Through the above technical solution, the arc-shaped magnetic barrier can make the main magnetic field lines generated by the magnetomotive force of the magnetic steel smoothly enter the stator through the rotor and the air gap, forming an ideal d-axis magnetic circuit, reducing the magnetic resistance of the d-axis magnetic circuit, and increasing the d-axis inductance.

[0013] Furthermore, the widths of the three arc-shaped magnetic barriers are W1, W2, and W3 respectively, and W1=W2=W3, the depth of the rotor outer magnetic barrier is H1, the minimum width of the end of the triangular large magnetic barrier at the arc edge between poles is W4, the width of the magnetic steel slot is Wpm, and the width dimension between the stator and rotor air gap is Gair. The dimensions of the widths of the three arc-shaped magnetic barriers W1, W2, and W3, the depth of the rotor outer magnetic barrier H1, the minimum width W4 of the end of the triangular large magnetic barrier at the arc edge between poles, the magnetic steel width Wpm and the air gap width Gair are designed to satisfy (2*W1+2*W2+2*W3+W4+2*Gair+H1)>(Wpm+2Gair).

[0014] Through the above technical scheme, the directions of these air magnetic barriers are mainly perpendicular to the q-axis magnetic circuit and parallel to the d-axis magnetic circuit. This design can not only reduce the leakage flux and magnetic resistance of the d-axis magnetic circuit, but also greatly increase the magnetic resistance of the q-axis magnetic circuit, so that the d-axis inductance remains unchanged and the q-axis inductance is greatly reduced, so that Ld>Lq, so that the motor can operate in the magnetic assisting state, that is, the current angle is adjusted to the positive angle range, and its direct-axis current is a positive magnetic-enhancing current. The permanent magnet flux is in the same direction as the direct-axis current, so that the armature reaction has a magnetic flux enhancement effect, which can improve the working point of the permanent magnet, enhance the anti-demagnetization ability of the magnetic steel, and utilize the magnetic resistance torque in the magnetic assisting state to increase the torque output capacity.

[0015] Furthermore, the distances between the first arc magnetic barrier, the second arc magnetic barrier, the third arc magnetic barrier and the inter-pole arc edge triangular magnetic barrier are L1, L2, and L3, wherein the relationship between these three distances is L1 <L2<L3。

[0016] Furthermore, a plurality of stator slots are evenly distributed on the stator punching sheet, and the windings are arranged in the stator slots.

[0017] Through the above technical scheme, when the magnetomotive force of the magnet enters the air gap through the d-axis magnetic circuit, the magnetic flux in the middle of the two-pole magnets is large, and the magnetic flux on both sides is small, so that the magnetic density distribution of the air gap magnetic field is closer to sine, which can reduce the amplitude of the high-order harmonics of the air gap magnetic field, increase the fundamental magnetomotive force of the magnetic field, reduce the harmonic loss and vibration noise of the motor air gap, and improve the motor efficiency.

[0018] In summary, the beneficial effects of this application are:

[0019] This application uses the inductance characteristic of the motor structure Ld>Lq to control the motor to operate in the magnetic assist state, that is, the d-axis current id is positive, which can greatly increase the working point of the motor magnet and reduce the risk of demagnetization of the magnet under high temperature and high overload conditions, and has a certain fault tolerance. At the same time, the magnetic assist characteristic structure can enhance the back electromotive force of the motor, which is beneficial to improve the motor overload multiple and power factor.

[0020] The q-axis magnetic circuit of the motor of the present application is designed with multiple layers of air magnetic barriers, which can not only reduce the q-axis inductance, but also reduce the magnetic density saturation of the stator and rotor cores in the q-axis magnetic circuit, thereby reducing the stator and rotor core losses, improving the motor efficiency, and reducing the motor temperature rise.

[0021] The reduction of the quadrature-axis inductance of the motor of the present application can reduce the saturation degree of the cross-coupling of the AC and direct-axis magnetic circuits when the motor is overloaded, thereby improving the overload capacity of the motor and the linearity of the overload torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a traditional spoke rotor motor;

[0023] Figure 2 This is a schematic diagram of the overall structure of a robot servo motor based on magnetic assist characteristics in a specific embodiment of the present application, wherein 01, winding; 02, stator slot; 03, stator punching; 04, stator core; 05, magnetic steel; 06, magnetic steel slot; 07, rotor punching; 08, rotor core; 09, multi-layer air magnetic barrier;

[0024] Figure 3 20 is a schematic diagram of the topological structure of the rotor punching in a specific embodiment of the present application, wherein 20, rotor outer circle magnetic barrier; 21, arc magnetic barrier No. 1; 22, arc magnetic barrier No. 2; 23, arc magnetic barrier No. 3; 24, inter-pole arc edge triangular large magnetic barrier; 06, spoke type magnetic steel slot;

[0025] Figure 4 is a schematic diagram of the d and q axis magnetic circuits in a specific embodiment of the present application;

[0026] Figure 5 It is a motor operation state vector diagram in a specific embodiment of the present application;

[0027] Figure 6 It is a torque characteristic-current angle distribution diagram of a magnetic-assisted motor and a traditional spoke motor provided in a specific embodiment of the present application;

[0028] Figure 7 This is a comparison chart of the core losses of a magnetic-assisted motor and a traditional spoke motor under rated operating conditions provided in a specific embodiment of the present application. DETAILED DESCRIPTION

[0029] The specific implementation of the present application is described in detail below with reference to the accompanying drawings.

[0030] Embodiment: A robot servo motor based on magnetic assist characteristics. The motor in this embodiment is improved on the basis of a traditional spoke rotor motor. The structure of the traditional spoke rotor motor is as follows: Figure 1 shown.

[0031] like Figure 2As shown, the robot servo motor based on magnetic assist characteristics provided in this embodiment includes a stator core 04, a rotor core 08 and a magnetic steel 05. The stator core 04 includes a stacked stator punching sheet 03 and a winding 01, a plurality of stator slots 02 are evenly distributed on the stator punching sheet 03, and the winding 01 is arranged in each stator slot 02.

[0032] The rotor core 08 includes multiple layers of stacked rotor punchings 07 , on which are provided spoke-type magnetic steel slots 06 and multiple layers of air magnetic barriers 09 , and the magnetic steel 05 is disposed in the magnetic steel slots 06 .

[0033] The topological structure of rotor punching 07 is as follows Figure 3 As shown, the multi-layer air magnetic barrier 09 includes a plurality of arc-shaped magnetic barriers symmetrically arranged on both sides of the magnetic steel slot 06. The arc-shaped magnetic barriers include arc-shaped magnetic barrier No. 1 21, arc-shaped magnetic barrier No. 22 and arc-shaped magnetic barrier No. 3 23. The three arc-shaped magnetic barriers are concentric arcs and their centers are Q1. The center Q1 is located on the extension line of the center line of the magnetic steel outside the rotor core. The radii of the three arc-shaped magnetic barriers increase successively. The curvature radii of the three arc-shaped magnetic barriers are R1, R2 and R3 respectively. The lengths of the three arc-shaped magnetic barriers are distributed in space and increase successively from the outer circle to the inner circle of the rotor.

[0034] The multi-layer air magnetic barrier also includes an inter-pole arc-edge triangular magnetic barrier 24, which is arranged between two adjacent magnetic steel slots 06, and its two sides facing the arc magnetic barrier are arc-shaped and concentric with the opposite arc magnetic barrier. The arc curvature radius of the inter-pole arc-edge triangular magnetic barrier 24 is R4.

[0035] The arc-shaped magnetic barrier is mainly used to completely form an air magnetic barrier on the q-axis magnetic circuit, increase the q-axis magnetic resistance, and reduce the q-axis inductance. At the same time, the arc-shaped magnetic barrier can force the main magnetic field lines generated by the magnetomotive force of the magnetic steel to smoothly enter the stator through the rotor and the air gap, forming an ideal d-axis magnetic circuit, reducing the magnetic resistance and leakage of the d-axis magnetic circuit, and increasing the d-axis inductance.

[0036] A rotor outer circle magnetic barrier 20 is provided on the top of each spoke-type magnetic steel slot 06 on the rotor punching sheet 07. The rotor outer circle magnetic barrier 20 is a concave structure of the rotor outer circle.

[0037] The widths of the three arc-shaped magnetic barriers are W1, W2, and W3 respectively, and W1 = W2 = W3. The three arc-shaped magnetic barriers are designed as concentric arcs with equal widths. The advantages of being concentric and having the same width are to reduce design variables and lower the design difficulty and workload. The depth of the magnetic barrier on the outer circle of the rotor is H1, and the minimum width of the end of the large triangular magnetic barrier with arc edges between poles is W4. These dimensions are the air magnetic barriers that form the main magnetic resistance on the q-axis magnetic circuit. The width of the permanent magnet slot is Wpm, which is the air magnetic barrier that forms the main magnetic resistance on the d-axis magnetic circuit. The width dimension between the stator and rotor air gaps is Gair. Among them, the dimension designs of the widths W1, W2, and W3 of the three arc-shaped magnetic barriers, the depth H1 of the magnetic barrier on the outer circle of the rotor, the minimum width W4 of the end of the large triangular magnetic barrier with arc edges between poles, the width Wpm of the permanent magnet, and the air gap width Gair satisfy (2*W1 + 2*W2 + 2*W3 + W4 + 2*Gair + H1) > (Wpm + 2*Gair). The directions of these air magnetic barriers are mainly perpendicular to the q-axis magnetic circuit and parallel to the d-axis magnetic circuit. The schematic diagrams of the d-axis and q-axis magnetic circuits are as shown in Figure 4 the schematic diagram of the dq-axis magnetic circuit shown in

[0038] The depth of the magnetic barrier on the outer circle of the rotor is H1, the minimum width of the end of the large triangular magnetic barrier with arc edges between poles is W4, the width of the permanent magnet slot is Wpm, and the width dimension between the stator and rotor air gaps is Gair. The dimension designs of the widths W1, W2, and W3 of the three arc-shaped magnetic barriers, the depth H1 of the magnetic barrier on the outer circle of the rotor, the minimum width W4 of the end of the large triangular magnetic barrier with arc edges between poles, the width Wpm of the permanent magnet, and the air gap width Gair satisfy (2*W1 + 2*W2 + 2*W3 + W4 + 2*Gair + H1) > (Wpm + 2*Gair).

[0039] The distances between the first arc-shaped magnetic barrier, the second arc-shaped magnetic barrier, the third arc-shaped magnetic barrier, and the large triangular magnetic barrier with arc edges between poles are L1, L2, and L3 respectively. Among them, the relationship of these three distances is L1 < L2 < L3. In this way, when the magnetomotive force of the permanent magnet enters the air gap through the d-axis magnetic circuit, the magnetic flux in the middle of the two-pole permanent magnet is large, and the magnetic flux on both sides is small, making the magnetic flux density distribution in the air gap magnetic field closer to a sine wave, which can reduce the amplitude of the high-order harmonics of the air gap magnetic field, enhance the fundamental wave magnetomotive force of the magnetic field, reduce the harmonic loss and vibration noise of the motor air gap, and improve the motor efficiency.

[0040] The present invention can not only reduce the magnetic leakage and magnetic resistance of the d-axis magnetic circuit, but also greatly increase the magnetic resistance of the q-axis magnetic circuit, so that the d-axis inductance remains unchanged, and the q-axis inductance is greatly reduced, making Ld > Lq. In this way, the reluctance torque of the motor of the present invention is a positive reluctance torque under the positive direction id current, as shown in Figure 6 the reluctance torque curve of the motor of the present invention in the torque characteristic - current angle distribution diagram of the assisting magnet motor of the present invention and the traditional spoke motor. It can make the motor operate in the assisting magnet state, that is, adjust the current angle to the positive angle range, that is, the direct-axis current i d is a positive-direction magnetizing current, and the direction of the permanent magnet magnetic field ψf The armature reaction generated by the stator winding has the same direction as the direct axis current id, which has the effect of enhancing the rotor magnetic field, such as Figure 5 As shown in the dotted ellipse mark position in the magnetization state vector diagram in Figure b of the motor operation state vector diagram, compared with the traditional motor running in the demagnetization state in the demagnetization state vector diagram in Figure a, this can increase the working point of the permanent magnet and enhance the anti-demagnetization ability of the magnetic steel. As shown in Table 1, the comparison results of the working points of the magnetic steel of the magnetic assist motor of the present invention and the traditional spoke motor under different overload torques, compared with the traditional spoke rotor motor, under 3 times the overload torque, the working point of the magnetic steel is increased by 46.9%, which reduces the demagnetization risk of the magnetic steel under high temperature and high overload conditions, and makes the motor have a strong magnetic steel anti-demagnetization fault tolerance characteristic.

[0041] Table 1 Comparison of magnetic steel working points of the magnetic-assisted motor of the present invention and the traditional spoke motor under different overload torques

[0042]

[0043] The present invention utilizes the magnetic resistance torque in the magnetic assist state to control the current is angle to about 20° in the positive direction. Figure 6 The torque characteristics-current angle distribution diagram of the magnetic assist motor and the traditional spoke motor shows that the torque output capacity of the motor can be increased by 7.7% compared with the traditional spoke rotor motor. At the same time, the magnetic assist characteristic structure can enhance the back electromotive force of the motor, which is beneficial to improve the power factor and overload capacity of the motor.

[0044] The q-axis magnetic circuit of the motor of the present invention is designed with multiple layers of air magnetic barriers, which can not only reduce the q-axis inductance, but also reduce the magnetic density saturation of the stator and rotor cores in the q-axis magnetic circuit, thereby reducing the stator and rotor core losses and improving the motor efficiency. Compared with the traditional spoke motor, the iron loss is reduced by 8.6%. Figure 7 The iron core loss comparison diagram of the magnetic assist motor of the present invention and the traditional spoke motor under rated working conditions is shown in the figure, which can further reduce the temperature rise of the motor. At the same time, the quadrature axis inductance is reduced, and the saturation degree of the cross-coupling of the quadrature and direct axis magnetic circuits can be reduced when the motor is overloaded, thereby improving the overload capacity of the motor and the linearity of the overload torque.

[0045] The above is only a preferred implementation of the present application. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present application, and these all fall within the scope of protection of the present application.

Claims

1. A robot servo motor based on magnetic assist characteristics, characterized in that: It includes a stator core, a rotor core and magnetic steel, wherein the stator core includes laminated stator punching sheets and windings, and the rotor core includes laminated rotor punching sheets with multiple layers, wherein the rotor punching sheets are provided with spoke-type magnetic steel slots and multiple layers of air magnetic barriers, and the magnetic steel is arranged in the magnetic steel slots; The multi-layer air magnetic barrier comprises a plurality of arc-shaped magnetic barriers symmetrically arranged on both sides of the magnetic steel slot.

2. The robot servo motor based on magnetic assist characteristics according to claim 1, characterized in that: The arc magnetic barriers include arc magnetic barrier No. 1, arc magnetic barrier No. 2 and arc magnetic barrier No.

3. The three arc magnetic barriers are concentric arcs. The radii of the three arc magnetic barriers increase successively. The lengths of the three arc magnetic barriers increase successively from the outer circle to the inner circle of the rotor.

3. The robot servo motor based on magnetic assist characteristics according to claim 2, characterized in that: The multi-layer air magnetic barrier also includes a large inter-pole arc-edge triangular magnetic barrier, which is arranged between two adjacent magnetic steel slots, and its two side edges facing the arc magnetic barrier are arc-shaped and concentric with the opposite arc magnetic barrier.

4. The robot servo motor based on magnetic assist characteristics according to claim 3 is characterized in that: A rotor outer circle magnetic barrier is provided on the top of each spoke-type magnetic steel slot on the rotor punching sheet, and the rotor outer circle magnetic barrier is a structure in which the rotor outer circle is concave.

5. The robot servo motor based on magnetic assist characteristics according to claim 4, characterized in that: The widths of the three arc-shaped magnetic barriers are W1, W2, and W3, and W1=W2=W3, the depth of the rotor outer magnetic barrier is H1, the minimum width of the end of the triangular large magnetic barrier at the arc edge between poles is W4, the width of the magnetic steel slot is Wpm, and the width dimension between the stator and rotor air gap is Gair. The dimensions of the widths of the three arc-shaped magnetic barriers W1, W2, and W3, the depth of the rotor outer magnetic barrier H1, the minimum width W4 of the end of the triangular large magnetic barrier at the arc edge between poles, the magnetic steel width Wpm and the air gap width Gair are designed to satisfy (2*W1+2*W2+2*W3+W4+2*Gair+H1)>(Wpm+2Gair).

6. The robot servo motor based on magnetic assist characteristics according to claim 2, characterized in that: The distances between arc magnetic barrier No. 1, arc magnetic barrier No. 2, arc magnetic barrier No. 3 and the inter-pole arc edge triangular magnetic barrier are L1, L2, and L3, and the relationship between these three distances is L1 <L2<L3。 7. The robot servo motor based on magnetic assist characteristics according to any one of claims 1 to 6, characterized in that: A number of stator slots are evenly distributed on the stator punching sheets, and the windings are arranged in the stator slots.

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