Five-degree-of-freedom magnetic suspension switched reluctance motor system and control method thereof

A technology of switched reluctance motors and reluctance motors, which is applied in the direction of AC motor control, control systems, and mechanical energy control, and can solve problems such as unfavorable system simplification and reliability, reduced suspension control accuracy, and increased suspension system control difficulty.

Active Publication Date: 2017-07-14

南京埃克锐特机电科技有限公司

4 Cites 5 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0003] The magnetic levitation switched reluctance motor is usually composed of a five-degree-of-freedom magnetic bearing and a switched reluctance motor. The traditional permanent magnet bias magnetic bearing requires a large thrust plate, which will cause large eddy current loss and temperature rise; while the traditional cone The shape electric excitation magnetic bearing has more control objects, and the axial suspension force is related to the square of the control win...

Method used

In summary, the present invention can realize five-degree-of-freedom suspension operation, mutual decoupling between suspension forces, suspension force and torque decoupling, high-speed suspension performance is good; Bias winding is by only utilizing four diodes, realizes its The current is always a constant positive value, the power converter is highly integrated, and the cost is low; it only needs to control the current of five suspension windings, and does not need to separately control the current of the armature winding or bias winding for suspension operation, and can generate all kinds of currents in five directions. Suspension force is required, and the control is simple; the axial and radial suspension magnetic circuits are isolated, the magnetic bearing magnetic circuit is also isolated from the reluctance motor magnetic circuit, the magnetic circuit coupling is weak, and the fault tolerance performance is good.

[0097] FIG. 2 is a schematic diagram of a power converter according to an embodiment of the present invention. The three-phase armature windings are respectively connected to three asymmetrical half-bridge branches, and the bias winding is connected in series to its DC bus through four diodes. Among them, diodes D7 and D8 provide current branches in the positive direction when the three-phase armature windings are turned on and excited; while diodes D9 and D10 provide freewheeling circuits for the three-phase armature winding ...

Abstract

The invention discloses a five-degree-of-freedom magnetic suspension switched reluctance motor system and a control method thereof. The system comprises a switched reluctance motor, two radial magnetic bearings and two conical magnetic bearings, wherein one of the two radial magnetic bearings and one of the two conical magnetic bearings are arranged at one side of the switched reluctance motor, the other radial magnetic bearing and the other conical magnetic bearing are arranged at the other side of the switched reluctance motor, bias windings of the four magnetic bearings are connected in series to form a set of bias winding, four diodes are connected in series to a DC bus of an armature winding power circuit of the switched reluctance motor, the rotation control is same as a control mode of a traditional switched reluctance motor, suspension forces in five directions are only relevant to a bias current and a current of a suspension winding in each direction and are decoupled to one another, moreover, the current of the bias winding is only relevant to a current of a three-phase armature, no independent control is performed, and torques and the suspension forces can be controlled in a decoupling way. The motor system is high in integration, simple in winding structure, low in control variable and simple in suspension control, and a power converter is low in cost.

Application Domain

AC motor controlMechanical energy handling +1

Technology Topic

Control variableControl mode +14

Image

Examples

Experimental program(1)

Example Embodiment

[0066] The technical scheme of a five-degree-of-freedom magnetic levitation switched reluctance motor system and control method of the present invention will be described in detail below with reference to the accompanying drawings:

[0067] Such as figure 1 Shown is a three-dimensional schematic diagram of an embodiment of a five-degree-of-freedom magnetic levitation switched reluctance motor system of the present invention, where 1 is a reluctance motor stator, 2 is a reluctance motor rotor, 3 is a reluctance motor coil, and 4 is a radial stator , 5 is a radial rotor, 6 is a radial bias coil, 7 is a radial suspension coil, 8 is a cone stator, 9 is a cone rotor, 10 is an axial bias winding, 11 is an axial suspension coil, 12 Is the rotating shaft, 13 is the switched reluctance motor, 14 is the radial magnetic bearing I, 15 is the tapered magnetic bearing I, 16 is the radial magnetic bearing II, 17 is the tapered magnetic bearing II, 18, 19, 20 are x respectively , Y, z axis direction The positive direction of the coordinate axis.

[0068] A five-degree-of-freedom magnetic suspension switched reluctance motor system, including tapered magnetic bearing I, radial magnetic bearing I, switched reluctance motor, radial magnetic bearing II and tapered magnetic bearing II; the tapered magnetic bearing I and The radial magnetic bearing I is arranged on one side of the switched reluctance motor, while the radial magnetic bearing II and tapered magnetic bearing II are arranged on the other side of the switched reluctance motor;

[0069] The tapered magnetic bearing I is composed of a tapered stator I, a tapered rotor I, an axial bias coil I and an axial suspension coil I;

[0070] The tapered magnetic bearing II is composed of a tapered stator II, a tapered rotor II, an axial bias coil II and an axial suspension coil II;

[0071] The radial magnetic bearing I is composed of a radial stator I, a radial rotor I, a radial bias coil I and a radial suspension coil I;

[0072] The radial magnetic bearing II is composed of a radial stator II, a radial rotor II, a radial bias coil II and a radial suspension coil II;

[0073] The switched reluctance motor is composed of a reluctance motor stator, a reluctance motor rotor and a reluctance motor coil;

[0074] The cone rotor I is arranged in the cone stator I, the radial rotor I is arranged in the radial stator I, the reluctance motor rotor is arranged in the reluctance motor stator, and the radial rotor II is arranged in the radial stator II. The cone rotor II is arranged in the cone stator II; the cone rotor I, the radial rotor I, the reluctance motor rotor, the radial rotor II and the cone rotor II are sleeved on the rotating shaft; the cone stator I, Radial stator I, reluctance motor stator, radial stator II and tapered stator II are arranged in series, and there is a gap between them;

[0075] The stator of the reluctance motor and the rotor of the reluctance motor are both salient pole structures, and the number of teeth of the reluctance motor stator and the reluctance motor rotor has three combinations of 12/8, 6/4, and 8/6; among them, the reluctance motor stator When the combination of the number of teeth with the reluctance motor rotor is 12/8 and 6/4, the phase number m of the switched reluctance motor is 3, and the combination of the number of teeth of the reluctance motor stator and the reluctance motor rotor is 8/6, the switched reluctance motor The number of motor phases m is 4;

[0076] The number of teeth of the reluctance motor stator and the reluctance motor rotor adopts a 12/8 combination, that is, when the number of stator teeth of the reluctance motor is 12, the number of rotor teeth of the reluctance motor is 8, and the number of motor phases m is 3, every 4 is separated The reluctance motor coils on the stator teeth of the 90° reluctance motor are connected in series, parallel, or series-parallel connection to form an armature winding, forming a total of 3 armature windings;

[0077] The number of teeth of the reluctance motor stator and the reluctance motor rotor adopts a 6/4 combination, that is, when the number of stator teeth of the reluctance motor is 6, the number of rotor teeth of the reluctance motor is 4, and the number of motor phases m is 3, every 2 is separated The coils of the reluctance motor on the stator teeth of the 180° reluctance motor are connected in series or in parallel to form an armature winding, forming a total of 3 armature windings;

[0078] The number of teeth of the stator of the reluctance motor and the rotor of the reluctance motor adopts a combination of 8/6, that is, when the number of stator teeth of the reluctance motor is 8, the number of rotor teeth of the reluctance motor is 6, and the number of motor phases m is 4, every two is separated The reluctance motor coils on the stator teeth of the 180° reluctance motor are connected in series or parallel to form an armature winding, forming a total of 4 armature windings;

[0079] The tapered stator I and the tapered stator II are both tapered salient pole structures, the number of stator teeth of both is 4, the tapered rotor I and the tapered rotor II are both tapered cylindrical structures; the tapered stator I, The cone angles of the cone stator II, cone rotor I and cone rotor II are equal; the cone angle opening direction of cone stator I and cone rotor I are the same, the cone angle of cone stator II and cone rotor II The opening direction is the same; the opening direction of the cone angle of the cone stator I and the cone rotor I is opposite to the cone angle opening direction of the cone stator II and the cone rotor II;

[0080] The radial stator I and the radial stator II are both salient pole structures, the number of stator teeth of the two is 4, and the 4 stator teeth of the radial stator I and the 4 stator teeth of the radial stator II are aligned; Both radial rotor I and radial rotor II are cylindrical structures;

[0081] Each stator tooth of the tapered stator I is wound with an axial suspension coil I and an axial bias coil I, a total of 4 axial suspension coils I and 4 axial bias coils I;

[0082] Each stator tooth of the tapered stator II is wound with an axial suspension coil II and an axial bias coil II, a total of 4 axial suspension coils II and 4 axial bias coils II;

[0083] Each stator tooth of the radial stator I is wound with a radial suspension coil I and a radial bias coil I, a total of 4 radial suspension coils I and 4 radial bias coils I;

[0084] Each stator tooth of the radial stator II is wound with a radial suspension coil II and a radial bias coil II, a total of 4 radial suspension coils II and 4 radial bias coils II;

[0085] The connection mode of the radial suspension coil I of the radial stator I is: two radial suspension coils I separated by 180° at the horizontal position are connected in series to form a horizontal radial suspension winding I; at the vertical position Two radial suspension coils I separated by 180° are connected in series to form a vertical radial suspension winding I;

[0086] The connection method of the radial suspension coil II of the radial stator II is: two radial suspension coils II separated by 180° at the horizontal position are connected in series to form a horizontal radial suspension winding II; Two radial suspension coils II separated by 180° are connected in series to form a vertical radial suspension winding II;

[0087] The 4 axial suspension coils I are connected in series to form an axial suspension coil string I; the 4 axial suspension coils II are connected in series to form an axial suspension coil string II; and the 1 axial suspension coil String I and an axial suspension coil string II are connected in series to form an axial suspension winding;

[0088] The four axial bias coils I are connected in series to form an axial bias coil string I, and the four axial bias coils II are connected in series to form an axial bias coil string II; The radial bias coil I is connected in series to form a radial bias coil string I, and the four radial bias coils II are connected in series to form a radial bias coil string II;

[0089] Said one axial bias coil string I, one radial bias coil string I, one axial bias coil string II and one radial bias coil string II are connected in series to form one bias winding.

[0090] Each phase armature winding consists of 4 reluctance motor coils spaced apart by 90° from each other, which are connected in series, or in parallel, or two in parallel; the four-pole symmetrical magnetic field generated by the current of each phase armature winding Pass, NSNS distribution. When the armature winding of one phase is turned on, the magnetic field generated in the reluctance motor is used to generate torque; the composite magnetic field generated in the magnetic bearing of the three-phase armature winding of A, B, and C is used for the bias of the suspension control magnetic field. The armature windings of the B and C phases have the same structure as the A phase armature windings, and differ only by 30° and -30° from the A phase in position.

[0091] For each radial magnetic bearing, the direction of the magnetic flux generated by the suspension winding and the bias winding at the air gap in the positive horizontal direction is the same, and the magnetic flux increases; while at the air gap in the negative horizontal direction, the direction is opposite, and the magnetic flux decreases. In turn, a levitation force in the positive x direction is generated. At the air gap in the vertical positive direction, the levitation winding and the armature winding generate the same magnetic flux direction, and the magnetic flux increases, while at the air gap in the vertical negative direction, the magnetic flux weakens, thereby generating a y-positive levitation force. Similarly, when the levitation winding current is reversed, the levitation force in the opposite direction will be generated.

[0092] For two tapered magnetic bearings, the direction of the axial suspension winding current of one tapered magnetic bearing is the same as the direction of the bias winding current, and the air gap magnetic flux is enhanced; at this time, the axial suspension winding current of the other tapered magnetic bearing The direction is opposite to the direction of the bias winding current, the air gap flux is weakened, and an axial levitation force can be generated.

[0093] Therefore, when the motor operating condition is constant, the current of the three-phase armature winding is constant, and the current of the bias winding in its DC bus is also a constant value. For this reason, the x, y, and z axis suspension winding currents are reasonably controlled. The size and direction can produce a suspension force that can be controlled in size and direction.

[0094] The three-phase armature winding current can adopt PWM control, pulse control and angular position control, etc., which are the same as the control method of the traditional switched reluctance motor, while the suspension current adopts chopper control. The bias winding current can be detected by the current sensor in real time, the radial displacement of the rotor can be detected by the eddy current sensor in real time, and the given value of the suspension force in two directions can be obtained by PI adjustment. Since the levitation force is related to the bias winding current and the levitation winding current in the five directions, the levitation current in the five directions can be calculated as the given value of the current control in the power converter, and finally the five degrees of freedom levitation operation of the motor is realized. .

[0095] The number of teeth of the reluctance motor stator and the reluctance motor rotor adopts a 6/4 combination, that is, when the number of stator teeth of the reluctance motor is 6, the number of rotor teeth of the reluctance motor is 4, and the number of motor phases m is 3, every 2 is separated The coils of the reluctance motor on the stator teeth of the 180° reluctance motor are connected in series or in parallel to form an armature winding, forming a total of 3 armature windings; in this case, the magnetic suspension of the present invention can be formed Example 2 of the motor system.

[0096] The number of teeth of the stator of the reluctance motor and the rotor of the reluctance motor adopts a combination of 8/6, that is, when the number of stator teeth of the reluctance motor is 8, the number of rotor teeth of the reluctance motor is 6, and the number of motor phases m is 4, every two is separated The reluctance motor coils on the stator teeth of the 180° reluctance motor are connected in series or parallel to form an armature winding, forming a total of 4 armature windings; at this time, it can form the magnetic suspension of the present invention Example 3 of the motor system.

[0097] figure 2 It is a schematic diagram of a power converter according to an embodiment of the present invention. The three-phase armature windings are respectively connected to three asymmetric half-bridge branches, and the bias winding is connected in series to its DC bus through four diodes. Among them, the diode D 7 And D 8 When the three-phase armature winding is energized, it provides a positive current branch; while the diode D 9 And D 10 Then, a freewheeling loop is provided for the three-phase armature winding current, and the direction of the bias winding current is always positive. In addition, the bias winding can be combined with diode D 7 And D 9 Form a loop, and diode D 8 And D 10 Forming another loop will keep the terminal voltage of the bias winding at a constant value regardless of the excitation or freewheeling phase, and finally promote the bias current to be a constant value, which will facilitate the suspension control and reduce the bias winding current. The core loss, thereby improving system efficiency.

[0098] Since four diodes D 7 , D 8 , D 9 And D 10 The voltage stabilizing effect on both ends of the bias winding makes the three-phase armature winding have a closed current loop of the radial bias winding in the excitation and freewheeling phases. Let the three-phase armature winding conduction phase sequence be ABC. When phase A is excited, phase C is freewheeling; when phase B is excited, phase A is freewheeling; when phase C is excited, phase B is continuous. flow.

[0099] Take A-phase excitation conduction as an example. At this time, A-phase excitation and C-phase freewheeling conduction. Part of the excitation current of the A-phase armature winding passes through the voltage source U s , Diode D 7 , Bias winding Bias, diode D 8 , Switch tube S 1 , A-phase armature winding, switch tube S 2 Closed; and the other part is through the A-phase armature winding, switch tube S 2 , Diode D 6 , C-phase armature winding, diode D 5 , Switch tube S 1 Closed; in turn, the current through the bias winding is always constant. It has the same effect when B and C phases are excited. When the phase number m> 3 o'clock, just figure 2 The shown power circuit adds corresponding branches, and the circuit of the bias winding part does not need to be changed.

[0100] Such as image 3 Shown is a simulation diagram of the three-phase armature current and the bias current of the embodiment of the present invention. The simulation results show that based on figure 2 In the power conversion circuit shown, the waveform of the three-phase armature current is the same as that of the conventional switched reluctance motor. figure 2 The power circuit shown has the function of a conventional asymmetric half-bridge circuit. In addition, the bias winding current is basically a constant value, indicating that the four diodes can stabilize the bias winding.

[0101] Such as Figure 4 Shown is a system block diagram of the control method of an embodiment of the five-degree-of-freedom magnetically levitation switched reluctance motor system of the present invention. Torque control can use traditional switched reluctance motor control methods such as PWM control, pulse control and angular position control, while levitation control uses current chopping control.

[0102] Torque control is: detecting the position information of the motor rotor, and calculating the actual speed ω and the opening angle θ of each phase. on And turn-off angle θ off , The speed error signal is adjusted by PI to obtain the armature winding current reference value Reuse current chopping control to track the actual armature winding current And use the opening angle θ on And turn-off angle θ off The conduction state of the power circuit of the armature winding is controlled to realize the rotation of the motor.

[0103] The suspension control is: PID adjustment of the displacement error signal to obtain a given suspension force Combined with the measured bias winding current i bias , Can be calculated by the suspension winding current controller: the reference value of the suspension winding current in the x direction of the radial magnetic bearing I And y-axis direction suspension winding current reference value Reference Value of X-direction Suspended Winding Current of Radial Magnetic Bearing Ⅱ And y-axis direction suspension winding current reference value Reference value of suspension winding current in z-axis direction

[0104] Using the current chopping control method, the actual current i of the suspension winding in the x-axis direction of the radial magnetic bearing I x1 Track the reference value of the suspension winding current in this direction Use the actual current i of the suspension winding in the y-axis direction y1 Track the reference value of the suspension winding current in this direction

[0105] The actual current i of the suspension winding in the x-axis direction using the radial magnetic bearing Ⅱ x2 Track the reference value of the suspension winding current in this direction Use the actual current i of the suspension winding in the y-axis direction y2 Track the reference value of the suspension winding current in this direction

[0106] Use the actual current i of the suspension winding in the z-axis direction z Track the reference value of the suspension winding current in this direction Thus, the levitation force is adjusted in real time, and the five-degree-of-freedom levitation of the magnetic levitation rotor system is realized.

[0107] Such as Figure 5 Shown is a block diagram of the calculation method of the suspension winding current in the control method of the embodiment of the five-degree-of-freedom magnetic levitation switched reluctance motor system of the present invention. In the figure, k f1 , K f2 Is the suspension force coefficient, and its expression is:

[0108]

[0109]

[0110] In the formula, μ 0 Is the vacuum permeability, l 1 Is the axial length of the radial magnetic bearing, r 1 Is the radius of the radial magnetic bearing rotor, α s1 Is the pole arc angle of the radial stator teeth, δ 1 Is the unilateral air gap length of the radial magnetic bearing, l 2 Is the axial length of the tapered magnetic bearing, r 2 Is the average radius of the tapered magnetic bearing rotor, δ 2 Is the unilateral air gap length of the tapered magnetic bearing, α s2 Is the pole arc angle of the tapered stator teeth, and ε is the cone angle.

[0111] Levitation force in the x and y axis of radial magnetic bearing I with The expression is:

[0112]

[0113]

[0114] Where i bias Is the current of the bias winding, which is determined by the operating conditions of the switched reluctance motor, and is checked by the current sensor, Are the suspension winding currents in the x and y directions of the radial magnetic bearing I, N b , N s The number of turns of the bias winding and the radial suspension winding respectively.

[0115] Levitation force in the x and y axis of radial magnetic bearing Ⅱ with The expression is:

[0116]

[0117]

[0118] Where These are the currents of the suspension windings in the x and y directions of the radial magnetic bearing II.

[0119] Suspension force in z-axis direction generated by two tapered magnetic bearings The expression is:

[0120]

[0121] Where N z Is the number of turns of the axial suspension winding, Is the current of the axial suspension winding.

[0122] From expressions (3) to (7), it can be seen that the radial and axial levitation forces of the magnetic levitation switched reluctance motor system of the present invention have nothing to do with the rotor position angle θ, and are only related to the motor structure parameters, one bias winding current and five levitation The winding current is related. Among them, the four radial levitation forces are only related to the radial levitation current and the bias winding current in this direction. The axial levitation force is also only related to the axial levitation current and the bias winding current, and the bias winding current can be obtained by inspection. It has nothing to do with the suspension control, so the five suspension forces are decoupled from each other, and the torque and the suspension force can also be decoupled.

[0123] It should be pointed out that since the levitation force changes with the positive and negative changes of the levitation winding current, the current directions of the five levitation windings will change during control, and a power converter with adjustable current directions is required.

[0124] The five-degree-of-freedom magnetic levitation switched reluctance motor system includes a switched reluctance reluctance motor, two radial magnetic bearings, and two tapered magnetic bearings. The switched reluctance motor generates rotational torque and two radial magnetic bearings. Generate 4 radial levitation forces, and two tapered magnetic bearings generate axial levitation forces to realize the levitation operation of the rotor in five directions; the windings of the magnetic levitation system are composed of m-phase armature windings, 1 bias winding, 4 It consists of two radial suspension windings and one axial suspension winding. The one bias winding is connected in series to the DC bus of the asymmetric half-bridge power converter of the m-phase armature winding, and the bias winding is made by four diodes. The current direction of the set winding is always the same as the current direction of the m-phase armature winding; the m-phase armature winding current is independently controlled to adjust the torque and generate the bias magnetic flux; the 5 suspension winding currents are independently controlled to achieve five degrees of freedom levitation Adjustment; includes the following steps:

[0125] Step A, obtain the given armature winding current, turn-on angle and turn-off angle; the specific steps are as follows:

[0126] Step A-1, collect the real-time speed of the rotor to obtain the rotor angular speed ω;

[0127] Step A-2, compare the rotor angular velocity ω with the set reference angular velocity ω * Subtract to get the speed difference Δω;

[0128] Step A-3, when ω≤ω 0 时,ω 0 Is the critical speed setting value, which is determined by the actual working conditions of the motor; the speed difference Δω, through the proportional integral controller, obtains the armature winding current reference value i m *;Opening angle θ on And turn-off angle θ off Fixed, θ on And θ off The value is determined by the structure of the motor;

[0129] Step A-4, when ω>ω 0 When the speed difference Δω, the opening angle θ is obtained through the proportional integral controller on And turn-off angle θ off , The armature winding current is not controlled;

[0130] Step B: Obtain the given levitation force in the x-axis and y-axis directions of the radial magnetic bearing I; the specific steps are as follows:

[0131] Step B-1, obtain the real-time displacement signal α in the x-axis and y-axis directions of the radial rotor Ⅰ 1 And β 1 , Where the x-axis is the horizontal direction and the y-axis is the vertical direction;

[0132] Step B-2, the real-time displacement signal α 1 And β 1 Respectively with the given reference displacement signal α 1 * And β 1 * Subtract, get the real-time displacement signal difference Δα in the x-axis direction and the y-axis direction respectively 1 And Δβ 1 , The real-time displacement signal difference Δα 1 And Δβ 1 After the proportional integral derivative controller, the levitation force in the x-axis direction of the radial magnetic bearing I is obtained And y-axis levitation force

[0133] Step C: Obtain the given levitation force in the x-axis and y-axis directions of the radial magnetic bearing II; the specific steps are as follows:

[0134] Step C-1, obtain the real-time displacement signal α in the x-axis and y-axis directions of the radial rotor II 2 And β 2;

[0135] Step C-2, the real-time displacement signal α 2 And β 2 Respectively with the given reference displacement signal α 2 * And β 2 * Subtract, get the real-time displacement signal difference Δα in the x-axis direction and the y-axis direction respectively 2 And Δβ 2 , The real-time displacement signal difference Δα 2 And Δβ 2 After the proportional integral derivative controller, the x-axis levitation force of the radial magnetic bearing II is obtained And y-axis levitation force

[0136] Step D: Obtain the given levitation force in the z-axis direction; the specific steps are as follows:

[0137] Step D-1, obtain the real-time displacement signal z in the z-axis direction of the rotor z , Where the z-axis is perpendicular to the x-axis and y-axis directions;

[0138] Step D-2, the real-time displacement signal z z With the given reference displacement signal z z * Subtract to get the real-time displacement signal difference Δz in the z-axis direction z , The real-time displacement signal difference Δz z The suspension force in the z-axis direction obtained by the proportional integral derivative controller

[0139] Step E, adjust the suspension force, the specific steps are as follows:

[0140] Step E-1, collect the real-time bias winding current i bias , According to the suspension force with And the current calculation formula with The reference value of the suspension winding current in the x direction of the radial magnetic bearing I is obtained by calculation And y-axis direction suspension winding current reference value Where k f1 Is the suspension force coefficient, μ 0 Is the vacuum permeability, l 1 Is the axial length of the radial magnetic bearing, r 1 Is the radius of the radial magnetic bearing rotor, α s1 Is the pole arc angle of the radial stator teeth, δ 1 Is the unilateral air gap length of the radial magnetic bearing, N b , N s The number of turns of the bias winding and radial suspension winding respectively, the bias winding current i bias Determined by the operating conditions of the switched reluctance motor, and obtained through current sensor inspection;

[0141] Step E-2, according to the suspension force with And the current calculation formula with The reference value of the suspension winding current in the x direction of the radial magnetic bearing Ⅱ is obtained by calculation And y-axis direction suspension winding current reference value

[0142] Step E-3, according to the suspension force And the current calculation formula Solve to obtain the reference value of the suspension winding current in the z-axis direction Where k f2 Is the suspension force coefficient, l 2 Is the axial length of the tapered magnetic bearing, r 2 Is the average radius of the tapered magnetic bearing rotor, δ 2 Is the unilateral air gap length of the tapered magnetic bearing, α s2 Is the pole arc angle of the cone stator tooth, ε is the cone angle, N z Is the number of turns of the axial suspension winding;

[0143] Step E-4, using the current chopping control method, using the actual current i of the suspension winding in the x-axis direction of the radial magnetic bearing I x1 Track the reference value of the suspension winding current in this direction Use the actual current i of the suspension winding in the y-axis direction y1 Track the reference value of the suspension winding current in this direction

[0144] The actual current i of the suspension winding in the x-axis direction using the radial magnetic bearing Ⅱ x2 Track the reference value of the suspension winding current in this direction Use the actual current i of the suspension winding in the y-axis direction y2 Track the reference value of the suspension winding current in this direction

[0145] Use the actual current i of the suspension winding in the z-axis direction z Track the reference value of the suspension winding current in this direction So as to adjust the suspension force in real time;

[0146] Step F, adjust the torque; the specific steps are as follows:

[0147] Step F-1, when ω≤ω 0 When using the current chopping control method, the actual current i m Tracking armature winding current reference value i m * , And then adjust the armature winding current i in real time m , And then achieve the purpose of adjusting the torque;

[0148] Step F-2, when ω>ω 0 When using the angle position control method, adjust the opening angle θ on And turn-off angle θ off To adjust the torque in real time.

[0149] It should be pointed out that the structure of the present invention has good scalability and has no limitation on the structure of the switched reluctance motor, as long as it is applicable to switched reluctance motors with a two-phase operation system and above.

[0150] In summary, the present invention can achieve five-degree-of-freedom levitation operation, decoupling of levitation forces, decoupling of levitation forces and torque, and good high-speed levitation performance; the bias winding uses only four diodes to achieve a constant current Constant positive value, high integration of the power converter, low cost; only need to control the current of five suspension windings, do not need to control the armature winding or bias winding current separately for the suspension operation, can generate the required suspension force in five directions , The control is simple; the axial and radial levitation magnetic circuits are isolated, and the magnetic circuit of the magnetic bearing is also isolated from the magnetic circuit of the reluctance motor. The magnetic circuit coupling is weak and the fault tolerance is good.

[0151] For those of ordinary skill in the technical field, it is easy to associate other advantages and modifications based on the above implementation types. Therefore, the present invention is not limited to the above-mentioned specific examples, and it is only used as an example to describe a form of the present invention in detail and exemplarily. Without departing from the scope of the present invention, technical solutions obtained by those of ordinary skill in the art through various equivalent substitutions based on the above specific examples should be included in the scope of the claims of the present invention and its equivalent scope.

PUM

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.