Novel three-winding bearingless permanent magnet synchronous motor and control method thereof

Abstract

The invention discloses a novel three-winding bearingless permanent magnet synchronous motor and a control method thereof, the novel three-winding bearingless permanent magnet synchronous motor comprises a rotor and a stator, the stator is provided with 24 slots, the slots are divided into three layers, the outermost layer is provided with two pairs of pole torque windings, the middle layer and the inner layer are alternately provided with one pair of poles and three pairs of pole suspension windings, and the three windings are concentric Y connection three-phase windings; and a torque and displacement closed-loop control system is established, the torque and the suspension force are controlled at the same time, and stable suspension and rotation of the rotor are achieved. The suspension force generated on the rotor in the X or Y direction is synthesized by a plurality of force components, the rotor suspension is more stable, and when one set of suspension winding is damaged, the motor can normally suspend and rotate, and the fault-tolerant capability is strong. Through the arrangement design of the three sets of windings in the stator slots, the purpose of magnetic field decoupling among the three sets of windings is finally achieved. And meanwhile, the multi-phase inverter is adopted, so that current can be accurately controlled, energy loss is reduced, and the overall efficiency of the motor is improved.

Description

Technical Field

[0001] The invention relates to the field of motor structure and control, and in particular to a novel three-winding bearingless permanent magnet synchronous motor and a control method thereof. Background Art

[0002] Bearingless motors use magnetic force to suspend the rotor, reduce or eliminate friction and wear of mechanical bearings, and have the advantages of no friction, high precision, high speed and long life. This technology is suitable for aerospace, high-speed machinery, medical equipment, transportation, industrial automation, energy storage and conversion, scientific research and other fields, and has broad application prospects. With the continuous advancement of technology and the reduction of costs, bearingless motors are expected to be used in more fields, especially in occasions where high-performance motors are needed.

[0003] Since there is cross-coupling between the rotation and the rotor suspension control of the bearingless permanent magnet synchronous motor, the control of the motor is more complicated than that of the motor supported by traditional magnetic bearings. This cross-coupling needs to be compensated and adjusted by a specific control strategy to achieve decoupling control between the suspension force and the torque.

[0004] In the existing bearingless permanent magnet synchronous motor technology, the technologies used for suspension force decoupling mainly include: decoupling control based on fuzzy neural network inverse system and decoupling algorithm based on rotor magnetic field oriented control. Although such methods provide solutions for magnetic field decoupling, on the one hand, they lack decoupling and robustness improvements for the motor itself, and on the other hand, targeted parameter and model training may cause computing power and resource loss. Through small-scale improvements and layout design, the magnetic field coupling problem can be solved and the motor life can be extended at a lower cost, which has a good research prospect. Summary of the invention

[0005] Purpose of the invention: To solve the problems mentioned in the background technology, the present invention proposes a novel three-winding bearingless permanent magnet synchronous motor and a control method thereof, which divides the original two sets of windings into three sets of windings, and divides the suspension force winding into one pair of pole suspension force windings and three pairs of pole suspension force windings, thereby solving a part of the magnetic field coupling problem between the three sets of windings; by dividing the stator slots into three layers, and then by arranging and designing the three sets of windings in the stator slots, the purpose of magnetic field decoupling between the three sets of windings is finally achieved, and in conjunction with a self-designed suspension force control method, the rotor suspension stability is maintained in real time in a low-cost manner, energy loss is reduced, and the overall efficiency of the motor is improved.

[0006] Technical solution:

[0007] The invention discloses a novel three-winding bearingless permanent magnet synchronous motor, comprising a motor rotor, a stator and a permanent magnet.

[0008] The motor rotor comprises a rotor core and a rotating shaft penetrating the rotor core.

[0009] The motor stator comprises a stator core and 24 stator slots evenly distributed circumferentially on the stator core, wherein three layers of windings are embedded in the stator slots, the inner and middle layers are suspension force windings, and the outer layer is torque windings;

[0010] The permanent magnets include N-pole arc-shaped permanent magnets and S-pole arc-shaped permanent magnets, which are alternately circumferentially bonded to the outer surface of the rotor core; an air gap exists between the motor rotor and the motor stator.

[0011] The suspension force winding includes a 1-pole suspension force winding and a 3-pole suspension force winding, which are alternately distributed up and down and each occupies 24 stator slots.

[0012] The inner layers of the stator slots 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, 20 are arranged with one pair of pole windings; and the inner layers of the stator slots 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, 24 are arranged with three pairs of pole windings.

[0013] The middle layers of the stator slots 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, and 24 are arranged with one pair of pole windings; and the middle layers of the stator slots 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, and 20 are arranged with three pairs of pole windings.

[0014] The slots 5, 13 and 21 of the inner layer of the stator slots are empty slots and no windings are arranged; the slots 1, 9 and 17 of the middle layer of the stator slots are empty slots and no windings are arranged.

[0015] The torque winding is a 2-pole concentrated winding, occupying the outer layers of 24 stator slots.

[0016] Furthermore, the torque winding and the suspension force winding are both concentric Y-connected three-phase windings.

[0017] Furthermore, the 1-pole suspension force winding and the 3-pole suspension force winding are arranged in a distributed manner, and the 2-pole concentrated windings are isolated from the 1-pole suspension force winding and the 3-pole suspension force winding.

[0018] Further, according to another aspect of the present invention, a novel control method of a three-winding bearingless permanent magnet synchronous motor is disclosed, the method comprising the following steps:

[0019] S1: Current is supplied to the 1-pole suspension force winding and the 3-pole suspension force winding, and the displacement deflection x, y and initial displacement x detected by the displacement sensor are compared. 0 ,y 0 Compare the two radial suspension force signals generated by the PID controller design The initial phase of the current of the 1-pole suspension force winding and the 3-pole suspension force winding and the actual angle signal w are used as input;

[0020] S2: Input F / i conversion module, then output four phase current signals After 4 / 6 transformation, the three-phase current signal is obtained Generate 1-pole suspension force winding and 3-pole suspension force winding control current signal i 1A 、i 1B 、i 1C 、i 3A 、i 3B 、i 3C ;

[0021] S3: Compare the actual angle signal w obtained by angle calculation after the angle signal detected by the rotary encoder with the initial angle w0, and then use it as the input of the PI controller to obtain the control angle q-axis current signal iq*, and compare it with The actual angle signal w and the initial phase of the current of the two-pole concentrated winding are used as input, and the input VR- 1 Module, after calculation, 2 current signals are obtained Then convert it by 2 / 3 to get 3 three-phase control current signals And generate 2 pairs of pole winding control current signal i 2 A.i 2B 、i 2 C.

[0022] Furthermore, the condition for a stable and controllable radial suspension force in a single direction is:

[0023] P B =P M ±1,P B ·w B =P M ·w M =w

[0024] Combining the relationship between the suspension winding current and magnetic field of the bearingless permanent magnet synchronous motor, and the radial force exerted on the motor rotor in the radial magnetic field, the radial suspension force generated by the suspension winding of one pair of poles is:

[0025]

[0026] The radial suspension force generated by the 3-pole suspension winding is:

[0027]

[0028] Among them, P B For 2 pairs of poles suspension winding, P M For 1, 3 pairs of pole suspension windings, w Mis the mechanical angular velocity of the rotor magnetic field, w B is the mechanical angular velocity of the suspension winding magnetic field, w is the mechanical angular velocity of the rotor rotation, F is the resultant external force of the suspension force, θ is the rotor rotation angle, r is the rotor radius, l is the axial length of the rotor, and B 1 When the rotor rotates, the permanent magnetic field of 1 pole pair, B 3 When the rotor rotates, the permanent magnetic field of 3 pole pairs, B 2 When the rotor rotates, the permanent magnetic field of 2 pole pairs, μ 0 is the vacuum permeability, θ 2 is the initial phase of the current in the two-pole concentrated winding, θ 1 is the initial phase of the current in the pole pair winding, θ 3 is the initial phase of the current in the three-pole winding.

[0029] Furthermore, in S1, a six-phase inverter independently adjusts the control current signal of each pole pair winding in the 1-pole suspension force winding and the 3-pole suspension force winding through a space vector pulse width modulation method. In S3, a three-phase inverter independently adjusts the control current signal of each pole pair winding of the 2-pole torque winding through a space vector pulse width modulation method.

[0030] Furthermore, the design steps of the 4 / 6 transformation in S2 are:

[0031] The standard three-phase voltages Ua, Ub, and Uc are 120 degrees apart in space;

[0032] Projecting the voltage vectors of the three axes a, b, and c onto the a and β axes corresponding to a pair of pole windings yields:

[0033] U α =cos45°U a +cos75°U b -cos15°U c

[0034] U β =-cos45°U a +cos15°U b -cos75°U c

[0035] Similarly, projecting the voltage vectors of the three axes a, b, and c onto the γ and δ axes corresponding to the three pairs of pole windings yields:

[0036] U γ =-cos45°U a -cos75°U b +cos15°U c

[0037] U δ =cos45°Ua -cos15°U b +cos75°U c

[0038] Convert it into a matrix as follows:

[0039]

[0040] Among them, U 1a is the voltage component of the A phase voltage vector projected onto a pair of poles, U 1b is the voltage component of the B-phase voltage vector projected onto a pair of windings, U 1c is the voltage component of the C phase voltage vector projected onto a pair of windings, U 3a is the voltage component of the A-phase voltage vector projected onto the three-pole winding, U 3b is the voltage component of the B-phase voltage vector projected onto the three-pole winding, U 3c It is the voltage component of the C phase voltage vector projected onto the three-pole winding.

[0041] Beneficial effects:

[0042] 1. The present invention achieves decoupling of the strong coupling relationship between the 1-pole suspension force winding and the 3-pole suspension force winding and the 2-pole winding by designing the stator slot positions where the 1-pole suspension force winding and the 3-pole suspension force winding are located with the 2-pole winding, thereby solving the magnetic field coupling problem in a low-cost manner, improving the control accuracy of the suspended rotor and extending the service life of the rotor.

[0043] 2. The present invention has its own suspension force control method, which cooperates with a multi-phase inverter to further accurately control the current, reduce energy loss, and improve the overall efficiency of the motor. By independently controlling the current of each pole pair winding, it provides a high degree of flexibility, reduces the risk of fault propagation, and improves the reliability of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the structure of the bearingless motor of the present invention;

[0045] Figure 2 It is a magnetic field distribution diagram of the suspension force winding of the bearingless motor of the present invention;

[0046] Figure 3 This is a control block diagram of a bearingless motor according to the present invention;

[0047] Figure 4 It is a voltage vector projection diagram of the bearingless motor of the present invention; DETAILED DESCRIPTION

[0048] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0049] like Figure 1 As shown: the structure of this embodiment includes a motor rotor, a stator, and a permanent magnet;

[0050] The motor rotor comprises a rotor core 1 and a rotating shaft 2 passing through the rotor core;

[0051] The motor stator includes a stator core 3 and 24 stator slots evenly distributed circumferentially on the stator core. Three layers of windings are embedded in the stator slots. The inner and middle layers are suspension windings, and the outer layer is torque windings.

[0052] The permanent magnets include an N-pole arc-shaped permanent magnet 5 and an S-pole arc-shaped permanent magnet 4, which are alternately circumferentially bonded to the outer surface of the rotor core; an air gap exists between the motor rotor and the motor stator;

[0053] The suspension force winding includes a 1-pole suspension force winding and a 3-pole suspension force winding, which are alternately distributed up and down, each occupying 24 stator slots;

[0054] 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, 20 in the inner layer of the stator slot

[0055] Arrange 1 pair of pole windings; 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, 24

[0056] Arrange 3 pairs of pole windings;

[0057] 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, 24 in the middle layer of the stator slots are arranged with a pair of pole windings; 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, 20

[0058] Arrange 3 pairs of pole windings;

[0059] The slots 5, 13, and 21 in the inner layer of the stator slots are empty slots and no windings are arranged; the slots 1, 9, and 17 in the middle layer of the stator slots are empty slots and no windings are arranged; the 1-pole suspension force winding and the 3-pole suspension force winding are arranged in a distributed manner, and the 2-pole concentrated winding is isolated from the 1-pole and 3-pole suspension force windings.

[0060] The torque winding is a 2-pole concentrated winding that occupies the outer layer of the 24 stator slots.

[0061] The torque winding and the suspension force winding are both concentric Y-connected three-phase windings.

[0062] The suspension force winding is wound by an electromagnetic coil with good conductor.

[0063] Figure 2 This is a magnetic field distribution diagram of the suspension force winding of the bearingless motor of the present invention. The magnetic field distribution of the suspension force winding of the motor can be seen from the figure. From the center to the outside, the magnetic field strength gradually increases and reaches the maximum value in the outermost layer. This distribution helps to ensure that the motor remains stable during operation and reduces wear and noise; multiple coils are arranged along the circumference to form a closed magnetic field loop. The direction of the magnetic field starts from the North Pole and returns to the South Pole downward, left, right, and upward. The distribution of the magnetic field on the circumference is relatively uniform, without obvious distortion or concentration. The magnetic field strength shows a trend of first increasing and then decreasing from the center to the outermost layer, which indicates that the uniformity of the motor magnetic field is good, ensuring that the performance of the motor is stable and reliable.

[0064] like Figure 3 As shown, the control method of the novel three-winding bearingless permanent magnet synchronous motor in this embodiment includes the following steps:

[0065] S1: Current is passed through the 1-pole suspension force winding and the 3-pole suspension force winding. The displacement deflection x and y detected by the displacement sensor are compared with the initial displacement x0 and y0. After the PID controller is designed, two radial suspension force signals are generated. The initial phase of the current of the 1-pole suspension force winding and the 3-pole suspension force winding and the actual angle signal w are used as input;

[0066] S2: Input F / i conversion module, then output four phase current signals After 4 / 6 transformation, the three-phase current signal is obtained Generate 1-pole suspension force winding and 3-pole suspension force winding control current signal i 1A 、i 1B 、i 1C 、i 3A 、i 3B 、i 3C ;

[0067] S3: Compare the actual angle signal w obtained by angle calculation after the angle signal detected by the rotary encoder with the initial angle w0, and then use it as the input of the PI controller to obtain the control angle q-axis current signal iq*, and compare it with The actual angle signal w and the initial phase of the current of the two pairs of concentrated windings are used as inputs to the VR-1 module, and two current signals are obtained after calculation. Then convert it by 2 / 3 to get 3 three-phase control current signals And generate 2 pairs of pole winding control current signal i 2A、i 2B 、i 2C .

[0068] The condition for stable and controllable radial force in a single direction is:

[0069] P B =P M ±1,P B ·w B =P M ·w M =w

[0070] Combining the relationship between the suspension winding current and magnetic field of the bearingless permanent magnet synchronous motor, and the radial force exerted on the motor rotor in the radial magnetic field, the radial suspension force generated by the suspension winding of one pair of poles is:

[0071]

[0072] The radial suspension force generated by the 3-pole suspension winding is:

[0073]

[0074] Among them, P B For 2 pairs of pole suspension windings, P M For 1, 3 pairs of pole suspension windings, W M is the mechanical angular velocity of the rotor magnetic field, w B is the mechanical angular velocity of the suspension winding magnetic field, w is the mechanical angular velocity of the rotor rotation, F is the resultant external force of the suspension force, θ is the rotor rotation angle, r is the rotor radius, l is the axial length of the rotor, and B 1 When the rotor rotates, the permanent magnetic field of 1 pole pair, B 3 When the rotor rotates, the permanent magnetic field of 3 pole pairs, B 2 When the rotor rotates, the permanent magnetic field of 2 pole pairs, μ 0 is the vacuum permeability, θ 2 is the initial phase of the current in the two-pole concentrated winding, θ 1 is the initial phase of the current in the pole pair winding, θ 3 is the initial phase of the current in the three-pole winding.

[0075] In S1, a six-phase inverter uses a space vector pulse width modulation method to independently adjust the control current signal of each pole pair winding in the 1-pole suspension force winding and the 3-pole suspension force winding. In S3, a three-phase inverter uses a space vector pulse width modulation method to independently adjust the control current signal of each pole pair winding of the 2-pole torque winding.

[0076] like Figure 4 As shown, the main design steps of 4 / 6 transformation in the control system are:

[0077] Standard three-phase voltage U a , U b , U c The difference in space is 120 degrees;

[0078] Projecting the voltage vectors of the three axes a, b, and c onto the α and β axes corresponding to a pair of pole windings yields:

[0079] U α =cos45°U a +cos75°U b -cos15°U c

[0080] U β =-cos45°U α +cos15°U b -cos75°U c

[0081] Similarly, projecting the voltage vectors of the three axes a, b, and c onto the γ and δ axes corresponding to the three pairs of pole windings yields:

[0082] U γ =-cos45°U a -cos75°U b +cos15°U c

[0083] U δ =cos45°U α -cos15°U b +cos75°U c

[0084] Convert it into a matrix as follows:

[0085]

[0086] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A novel three-winding bearingless permanent magnet synchronous motor, characterized in that: Including motor rotor, stator, and permanent magnet; The motor rotor comprises a rotor core (1) and a rotating shaft (2) passing through the rotor core; The motor stator comprises a stator core (3) and 24 stator slots evenly distributed in the circumferential direction on the stator core, wherein three layers of windings are embedded in the stator slots, the inner and middle layers are suspension force windings, and the outer layer is a torque winding; The permanent magnets include N-pole arc-shaped permanent magnets (5) and S-pole arc-shaped permanent magnets (4), and the N-pole arc-shaped permanent magnets and S-pole arc-shaped permanent magnets are alternately circumferentially bonded to the outer surface of the rotor core; an air gap exists between the motor rotor and the motor stator; The suspension force winding includes a 1-pole suspension force winding and a 3-pole suspension force winding, which are alternately distributed up and down, each occupying 24 stator slots; The inner layers of the stator slots 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, 20 are arranged with one pair of pole windings; 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, 24 are arranged with three pairs of pole windings; The middle layer of the stator slots 5, 6, 7, 8, 13, 14, 15, 16, 21, 22, 23, 24 are arranged with one pair of pole windings; 1, 2, 3, 4, 9, 10, 11, 12, 17, 18, 19, 20 are arranged with three pairs of pole windings; The slots 5, 13, and 21 of the inner layer of the stator slots are empty slots and no windings are arranged; the slots 1, 9, and 17 of the middle layer of the stator slots are empty slots and no windings are arranged; The torque winding is a 2-pole concentrated winding, occupying the outer layers of 24 stator slots.

2. A novel three-winding bearingless permanent magnet synchronous motor according to claim 1, characterized in that: The torque winding and the suspension force winding are both concentric Y-connected three-phase windings.

3. A novel three-winding bearingless permanent magnet synchronous motor according to claim 1, characterized in that: The 1-pole suspension force winding and the 3-pole suspension force winding are arranged in a distributed manner, and the 2-pole concentrated windings are isolated from the 1-pole suspension force winding and the 3-pole suspension force winding.

4. A control method for a novel three-winding bearingless permanent magnet synchronous motor according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: S1: Current is passed through the 1-pole suspension force winding and the 3-pole suspension force winding. The displacement deflection x and y detected by the displacement sensor are compared with the initial displacement x0 and y0. After the PID controller is designed, two radial suspension force signals are generated. The initial phase of the current of the 1-pole suspension force winding and the 3-pole suspension force winding and the actual angle signal w are used as input; S2: Input F / i conversion module, then output four phase current signals After 4 / 6 transformation, the three-phase current signal is obtained Generate 1-pole suspension force winding and 3-pole suspension force winding control current signal i 1A 、i 1B 、i 1C 、i 3A 、i 3B 、i 3C ; S3: Compare the actual angle signal w obtained by angle calculation after the angle signal detected by the rotary encoder with the initial angle w0, and then use it as the input of the PI controller to obtain the control angle q-axis current signal i q * , and The actual angle signal w and the initial phase of the current of the two-pole concentrated winding are used as input, and the input VR -1 Module, after calculation, 2 current signals are obtained Then convert it by 2 / 3 to get 3 three-phase control current signals And generate 2 pairs of pole winding control current signal i 2A 、i 2B 、i 2C .

5. The control method of a novel three-winding bearingless permanent magnet synchronous motor according to claim 4 is characterized in that: The condition of stable and controllable radial suspension force in a single direction is: P B =P M ±1,P B ·w B =P M ·w M =w Combining the relationship between the suspension winding current and magnetic field of the bearingless permanent magnet synchronous motor, and the radial force exerted on the motor rotor in the radial magnetic field, the radial suspension force generated by the suspension winding of one pair of poles is: The radial suspension force generated by the 3-pole suspension winding is: Among them, P B For 2 pairs of pole suspension windings, P M For 1, 3 pairs of pole suspension windings, w M is the mechanical angular velocity of the rotor magnetic field, w B is the mechanical angular velocity of the suspension winding magnetic field, w is the mechanical angular velocity of the rotor rotation, F is the resultant external force of the suspension force, θ is the rotor rotation angle, r is the rotor radius, l is the axial length of the rotor, B1 is the permanent magnetic field of 1 pole pair when the rotor rotates, B3 is the permanent magnetic field of 3 pole pairs when the rotor rotates, B2 is the permanent magnetic field of 2 pole pairs when the rotor rotates, μ0 is the vacuum permeability, θ2 is the initial current phase of the 2-pole concentrated winding, θ1 is the initial current phase of the 1-pole winding, and θ3 is the initial current phase of the 3-pole winding.

6. The control method of a novel three-winding bearingless permanent magnet synchronous motor according to claim 4 is characterized in that: In S1, a six-phase inverter uses a space vector pulse width modulation method to independently adjust the control current signal of each pole pair winding in the 1-pole suspension force winding and the 3-pole suspension force winding. In S3, a three-phase inverter uses a space vector pulse width modulation method to independently adjust the control current signal of each pole pair winding of the 2-pole torque winding.

7. The control method of a novel three-winding bearingless permanent magnet synchronous motor according to claim 4 is characterized in that: The design steps of the 4 / 6 transformation described in S2 are: Standard three-phase voltage U a , U b , U c The difference in space is 120 degrees; Projecting the voltage vectors of the three axes a, b, and c onto the α and β axes corresponding to a pair of pole windings yields: The α =cos45°U a +cos75°U b -cos15°N c The β =-cos45°U a +cos15°U b -cos75°U c Similarly, projecting the voltage vectors of the three axes a, b, and c onto the γ and δ axes corresponding to the three pairs of pole windings yields: The γ =-cos45°U a -cos75°U b +cos15°U c The δ =cos45°U a -cos15°N b +cos75°U c Convert it into a matrix as follows: Among them, U 1a is the voltage component of the A phase voltage vector projected onto a pair of poles, U 1b is the voltage component of the B-phase voltage vector projected onto a pair of windings, U 1c is the voltage component of the C phase voltage vector projected onto a pair of windings, U 3a is the voltage component of the A-phase voltage vector projected onto the three-pole winding, U 3b is the voltage component of the B-phase voltage vector projected onto the three-pole winding, U 3c It is the voltage component of the C phase voltage vector projected onto the three-pole winding.

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