A design method for long-stator linear synchronous motor powered by voltage source

Abstract

The present invention discloses a design method for a long-stator linear synchronous motor powered by a voltage source. The method includes: using sinusoidal currents under two working conditions as stator three-phase winding excitation, obtaining three-phase inductance and rotor excitation flux, then inputting the established three-phase current recursive model for processing and outputting the first steady-state three-phase current as three-phase winding current excitation, obtaining three-phase voltage, and simultaneously obtaining a voltage difference according to the expected value of the three-phase voltage and inputting the model for processing and outputting the second steady-state three-phase current as current source excitation, and obtaining the electromagnetic performance under square wave voltage conditions according to the finite element simulation model, thereby determining the optimal motor structural parameters to design the long-stator linear synchronous motor. The method of the present invention can quickly and accurately obtain the steady-state electromagnetic performance of the motor under voltage source power supply, and then design the long-stator linear synchronous motor, and can be applied to the electromagnetic design of other different types of three-phase synchronous motors under voltage source simulation conditions.

Description

Technical Field

[0001] The invention relates to a motor design method, relates to the field of magnetic levitation train transportation technology, and specifically to a long-stator linear synchronous motor design method under voltage source power supply. Background Art

[0002] The high-speed maglev transportation system of the normally-excited EMS (Electromagnetic Suspension) type is provided with suspension force and traction force by a long-stator linear synchronous motor. The electromagnetic force performance is affected by the power supply condition of the motor stator winding. Since the traction converter of the current maglev system uses a high-power integrated gate-commutated thyristor (IGCT) switching device, its switching frequency does not exceed 1kHz, which is close to the motor electrical frequency during ultra-high-speed operation, making the actual voltage output by the inverter modulated as a square wave. The square wave voltage supply will cause the amplitude of the current harmonics to increase, which will deteriorate the electromagnetic performance of the motor. The existing electromagnetic simulation research of EMS linear motors usually only considers the sinusoidal current source power supply condition, while the research on the simulation technology of EMS motor performance under the square wave voltage power supply condition is relatively lacking. The long-stator linear motor has a high stator segment leakage inductance and a high electromechanical time constant, which makes the motor have a long transient process under the voltage source power supply. Under the high-speed operation condition, it takes dozens of electrical cycles to simulate to reach a steady state. Long simulation time consumes a lot of computing resources, which makes it inconvenient to study the square wave voltage condition, and further causes inconvenience to the design of long-stator linear synchronous motor powered by voltage source. Summary of the invention

[0003] In order to solve the problems existing in the background technology, the present invention provides a design method of a long-stator linear synchronous motor powered by a voltage source.

[0004] The technical solution adopted by the present invention is:

[0005] The method for designing a long-stator linear synchronous motor powered by a voltage source of the present invention comprises:

[0006] Step 1) Construct a finite element simulation model of a long-stator linear synchronous motor, set motor parameters, external power supply circuit parameters and motor reference speed in the finite element simulation model, and the stator winding of the long-stator linear synchronous motor adopts a Y-shaped connection without a neutral point lead.

[0007] Step 2) Obtain a first sinusoidal current generated by a sinusoidal current source under the condition where the d-axis current is zero and a second sinusoidal current having the same effective value as the first sinusoidal current and a phase lag or lead of a small preset angle, and use the first and second sinusoidal currents as the stator three-phase winding excitation of the long-stator linear synchronous motor, thereby obtaining the three-phase inductance and the inductance excluding 3 of the long-stator linear synchronous motor according to the finite element simulation model. n Subharmonic rotor excitation flux.

[0008] Step 3) Write the current derivative and flux derivative in the voltage equation of the long stator linear synchronous motor in the three-phase stationary coordinate system into a backward difference form, establish a three-phase current recursive model of the long stator linear synchronous motor, and convert the three-phase inductance and flux derivative of the long stator linear synchronous motor into a three-phase current recursive model. n The rotor excitation flux of subharmonics and excluding 3 n The expected value of the three-phase voltage of the subharmonic is input into the three-phase current recursive model for processing, and multiple electrical cycles are iterated. After the three-phase current recursive model is processed, the first steady-state three-phase current is output.

[0009] Step 4) The first steady-state three-phase current is used as the three-phase winding current excitation of the long stator linear synchronous motor, so as to obtain the three-phase voltage of the long stator linear synchronous motor in one electrical cycle according to the finite element simulation model, and the three-phase voltage and the voltage excluding 3 are obtained. n The voltage difference is obtained from the expected value of the three-phase voltage of the subharmonic and is input into the three-phase current recursive model for processing. After iterating multiple electrical cycles, the three-phase current recursive model outputs the second steady-state three-phase current.

[0010] Step 5) The second steady-state three-phase current is used as the current source excitation of the long stator linear synchronous motor, and the electromagnetic performance under the square wave voltage condition is obtained according to the finite element simulation model, so as to determine the optimal motor structure parameters to realize the design of the long stator linear synchronous motor.

[0011] In the step 2), the first sinusoidal current and the second sinusoidal current are respectively used as the stator three-phase winding excitation of the long stator linear synchronous motor, and then the first three-phase flux and the second three-phase flux containing burrs in one electrical cycle of the long stator linear synchronous motor are respectively obtained by the finite element simulation model, and the first three-phase flux and the second three-phase flux without burrs in one electrical cycle of the long stator linear synchronous motor are respectively obtained by the harmonic analysis method, and then the first three-phase flux without burrs and the second three-phase flux without burrs of the long stator linear synchronous motor are respectively obtained according to the first sinusoidal current and the first three-phase flux without burrs and the second sinusoidal current and the second three-phase flux without burrs. n Subharmonic rotor excitation flux and three-phase inductance.

[0012] When using the harmonic analysis method to calculate the three-phase flux without burrs, the low-order harmonic amplitude and phase average of the three-phase flux with burrs are first taken out to calculate the A-phase flux without burrs, and then the B and C-phase flux without burrs are generated through the phase relationship, and finally the three-phase flux without burrs is obtained.

[0013] The three-phase inductance of the long-stator linear synchronous motor is obtained according to the sinusoidal current and the three-phase flux without burrs. First, the three-phase inductance of the long-stator linear synchronous motor in the dq coordinate system is obtained according to the sinusoidal current and the three-phase flux without burrs. k The inductance of a simulation step is as follows:

[0014] L D,k =( ψ D,k - ψ f,k ) / i d,k

[0015] L Q,k = ψ Q,k / i q,k

[0016] in, L D,k and L Q,k They are respectively the first and second coordinates of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis inductances of the simulation steps; ψ D,k and ψ Q,k They are the three-phase flux without burrs of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis flux linkages of simulation steps; ψ f,k For long stator linear synchronous motor k The excitation flux of the rotor under the simulation step size; i d,k and i q,k They are the sinusoidal current in the dq coordinate system. k The d-axis and q-axis currents for each simulation step.

[0017] In the first working condition, L D,k The result is infinite, so L D,k Only in the second working condition, the solution needs to be based on the rotor excitation flux ψ f,kcalculate L D,k , ψ f,k exist i d =0 working condition; L Q,k It can be solved under both working conditions. In practice, L D,k and L Q,k All the solutions are obtained under the second working condition.

[0018] The long stator linear synchronous motor is placed in the dq coordinate system. k The inductance of each simulation step is transformed by Park transformation and inverse Park transformation in turn to obtain the first inductance of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase inductance under simulation steps L 3s,k .

[0019] The long stator linear synchronous motor does not include 3 n The subharmonic rotor excitation flux is obtained based on the sinusoidal current and the three-phase flux without burrs. First, the three-phase flux without burrs under the condition of zero d-axis current is transformed by Park to obtain the subharmonic of the long stator linear synchronous motor in the dq coordinate system. k Flux linkage of simulation step ψ 2r,k , thus obtaining the long stator linear synchronous motor in the first k The excitation flux of the rotor under the simulation step size ψ f,k , the long stator linear synchronous motor is placed in the k The excitation flux of the rotor under the simulation step size ψ f,k The first coordinate of the long stator linear synchronous motor in the three-phase stationary coordinate system is obtained by inverse Park transformation. k The simulation steps do not include 3 n Subharmonic rotor excitation flux ψ f,3s,k .

[0020] In the step 3), 3 n The expected value of the three-phase voltage of the subharmonic is obtained according to the given voltage source square wave voltage. First, the given voltage source square wave voltage is transformed by Park to obtain the subharmonic value in the dq coordinate system. k The d-axis and q-axis voltages of the simulation step length are then calculated according to the dq coordinate system. k The d-axis and q-axis voltages of the simulation step are inversely transformed to obtain the k The step length does not include 3 nThe expected values ​​of the three-phase voltage of the subharmonics are as follows:

[0021] u 3s,k = C k -1 [ u d,k u q,k 0] T

[0022] in, u d,k and u q,k They are respectively k The d-axis and q-axis voltages for each simulation step.

[0023] The neutral point of the given voltage source is not short-circuited with the neutral point of the long-stator linear synchronous motor.

[0024] The first k Zero-sequence component voltage at simulation step u 0,k Set it to zero, and then use the inverse Park change to get the k The step length does not include 3 n Expected values ​​of three-phase voltages of subharmonics.

[0025] In the step 3), the three-phase current recursive model is as follows:

[0026] i 3s,k = A k -1 b k

[0027] A k =( R + L / T d ) I 3+ L 3s,k / T d

[0028] b k = u 3s,k +( L 3s,k-1 + LI 3) i 3s,k-1 / Td -( ψ f,3s,k - ψ f,3s,k-1 ) / T d

[0029] in, i 3s,k and u 3s,k They are respectively the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase current matrix of simulation step length and the current matrix without 3 n The expected value matrix of three-phase voltage of subharmonics, i 3s,k-1 The long stator linear synchronous motor is in the three-phase stationary coordinate system. k -Three-phase current matrix of 1 simulation step; A k and b k Respectively k The first and second intermediate variables at simulation steps; R is the phase resistance of the long stator linear synchronous motor; L It is the external circuit leakage inductance of the long stator linear synchronous motor; T d is the simulation step length; I 3 is the third-order unit matrix; L 3s,k and L 3s,k-1 They are respectively the first and second coordinates of the long stator linear synchronous motor in the three-phase stationary coordinate system. k and k -Three-phase inductance at 1 simulation step; ψ f,3s,k and ψ f,3s,k-1 They are the stator linear synchronous motor in the three-phase stationary coordinate system. k and k -1 simulation step does not include 3 n Subharmonic rotor excitation flux.

[0030] When using the three-phase current recursive model to iterate, the three-phase current of the long stator linear synchronous motor is asymmetric in the initial stage. After iterating several electrical cycles, the three-phase current of the long stator linear synchronous motor becomes symmetric. When the three-phase current of the long stator linear synchronous motor is symmetric, the three-phase current matrix of the long stator linear synchronous motor in one electrical cycle in the three-phase stationary coordinate system is the first steady-state three-phase current.

[0031] In the step 4), according to the three-phase voltage and excluding 3 nThe expected value of the three-phase voltage of the subharmonics is used to obtain the voltage difference. First, the three-phase voltage and the voltage without the harmonics are summed. n The expected values ​​of the three-phase voltages without harmonics are subtracted to obtain the intermediate voltage difference, and then the n The final voltage difference is obtained by subtracting the intermediate voltage difference from the expected value of the three-phase voltage of the subharmonic.

[0032] The three-phase voltage will be n The voltage difference obtained by the expected value of the three-phase voltage of the subharmonic replaces the voltage difference of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase voltage matrix of simulation step u 3s,k As the input of the three-phase current recursive model.

[0033] Take the first steady-state current excitation of an electrical cycle as the first result of finite element calculation k The phase voltage of each step is u 3s1,k , the difference between this phase voltage and the expected value of the three-phase voltage is Δ u 1,k = u 3s1,k - u 3s,k , the three-phase current recursive model used in the second iteration to calculate the second steady-state three-phase current u 3s,k Depend on u 3s,k -Δ u 1,k Alternative.

[0034] In the step 5), the electromagnetic performance under the square wave voltage condition includes the three-phase current and electromagnetic force of the long stator linear synchronous motor in a steady state.

[0035] The electronic device of the present invention comprises: a memory and a processor coupled to each other, wherein the memory stores program data, and the processor calls the program data to execute the method as described above.

[0036] The computer-readable storage medium of the present invention stores program data thereon, and is characterized in that the program data implements the method described above when executed by a processor.

[0037] The beneficial effects of the present invention are:

[0038] The method of the present invention can quickly and accurately complete the simulation research of the steady-state electromagnetic performance of the long-stator linear synchronous motor under the power supply of the voltage source. Compared with the finite element simulation directly using the square wave voltage source excitation, the method of the present invention is based on the combination of numerical calculation and finite element simulation, avoiding the simulation of the complete transient process in the finite element simulation software, and has the advantages of rapidity, accuracy, ease of use, and suitability for square wave voltage power supply conditions under different speed conditions. The recursive model used in the numerical calculation process is based on the conventional three-phase synchronous motor voltage equation, and the principle is simple.

[0039] The method of the present invention can be applied to the electromagnetic design of other different types of long-stator linear synchronous motors under voltage source simulation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a flow chart of the method of the present invention;

[0041] Figure 2 This is the finite element simulation model diagram of the long stator linear synchronous motor of the high-speed magnetic suspension system;

[0042] Figure 3 It is an external circuit connection diagram of the finite element simulation model under the power supply of the current source of the present invention;

[0043] Figure 4 It is a three-phase current diagram of one electrical cycle of the present invention under the working condition of 600 km / h speed;

[0044] Figure 5 It is a transition process diagram of the traction force result from transient state to steady state under the working condition of 600 km / h speed of the present invention;

[0045] Figure 6 It is a graph showing the error convergence of the traction force of the present invention under two speed conditions of 500 km / h and 600 km / h;

[0046] Figure 7 A comparison diagram of steady-state waveforms of traction force under five stator segment lengths of the present invention;

[0047] In the figure: 1. stator core, 2. stator winding, 3. mover excitation winding, 4. mover core, 5. stator air domain, 6. mover air domain. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] The embodiment of the present invention takes the long stator linear synchronous motor of the high-speed maglev transportation system as an example. Figure 1 As shown, the design method of the long stator linear synchronous motor powered by a voltage source of the present invention is specifically as follows:

[0050] Firstly, a finite element electromagnetic field simulation model of a long stator linear synchronous motor for a high-speed maglev transportation system is established. The finite element electromagnetic field simulation model of a long stator linear synchronous motor is as follows: Figure 2 As shown, the simulation model includes stator core 1, stator winding 2, rotor excitation winding 3, rotor core 4, stator air domain 5 and rotor air domain 6. The stator winding 2 of the long stator linear synchronous motor adopts Y-shaped connection without neutral point lead-out. The stator air domain 5 and the rotor air domain 6 are provided with translation periodic boundary conditions, that is, when the rotor translates to the right, the rotor grid moving out of the right boundary of the stator will form a finite element solution area with the grid on the left side of the stator, and the magnetic lines of force on the left and right boundaries are smoothly connected. As a preferred embodiment, the time of finite element simulation of one electrical cycle is T s Simulation step size T d The ratio of is an even number. The external circuit of the simulation model is as follows Figure 3 As shown, the three-phase current source is the power supply for the stator winding, and the resistor R is the phase resistance of the long stator linear synchronous motor, L is the external circuit leakage inductance of the long stator linear synchronous motor, N is the neutral point of the voltage source, N * is the neutral point of the three-phase winding of the motor, i A , i B , i C are the current sources of the three phases A, B, and C, respectively, ψ A 、p ψ B and p ψ C The three phases A, B and C are the three phases of the reverse electromotive force, and the nodes A, B and C are the three phase voltage observation points. For example, by measuring the * The voltage difference can be used to obtain the phase voltage of motor A.

[0051] Then get the d-axis current i d The first sinusoidal current generated by the sinusoidal current source under the condition of zero working condition and the second sinusoidal current with the same effective value as the first sinusoidal current and a phase lag or lead of 1°, the d-axis current i d =0 means that after the three-phase sinusoidal current is transformed by Park, the d-axis current obtained is zero. k Park transformation matrix under simulation step size C k The details are as follows:

[0052]

[0053] in, i k For the k The electrical angle of the simulation step.

[0054] The first sinusoidal current and the second sinusoidal current are respectively used as the stator three-phase winding excitation of the long stator linear synchronous motor, and then the first three-phase flux and the second three-phase flux containing burrs of the long stator linear synchronous motor in one electrical cycle are obtained respectively through the finite element simulation model, and the first three-phase flux and the second three-phase flux without burrs of the long stator linear synchronous motor in one electrical cycle are obtained respectively by using the harmonic analysis method. When the three-phase flux without burrs is calculated by the harmonic analysis method, the low-order harmonic amplitude and phase average value of the three-phase flux containing burrs are firstly taken out to calculate the A-phase flux without burrs, and then the B and C-phase flux without burrs are generated through the phase relationship, and finally the three-phase flux without burrs is obtained.

[0055] In the specific implementation, firstly, the effective values ​​of the sinusoidal currents of the two groups of working conditions are I A , first through i d =0 working condition, the finite element simulation calculates the three-phase flux linkage of 0.5 electrical cycle, at this time the current phase is f 1, and then the phase is f 2 sinusoidal current excitation, the three-phase flux linkage of 0.5 electrical cycle is calculated by the finite element simulation model. f 2 should be with f 1 is not much different, as a preferred embodiment, f 2 is taken as f 1-1°. Then, each group of flux is symmetrically calculated to obtain the three-phase flux of one electrical cycle. ψ 3s,k As a preferred embodiment, this embodiment uses fast Fourier decomposition to obtain the 1st, 3rd, 5th, 7th, 9th, 11th, and 13th harmonics in the three-phase flux results, and takes the amplitude and phase averages of the harmonics to calculate the A-phase flux without burrs, and finally generates the B and C-phase fluxes through the phase relationship. k Three-phase flux linkage under simulation step ψ 3s,k The details are as follows:

[0056] ψ 3s,k = ψ 3s,k , k ≤1+ T s / T d / 2

[0057] ψ3s,k =- ψ 3s,k-(1+Ts / Td) , k >1+ T s / T d / 2

[0058] in, ψ 3s,k-(1+Ts / Td) For the k -(1+ T s / T d ) simulation steps.

[0059] Then, the three-phase flux without burrs of the long stator linear synchronous motor are obtained according to the first sinusoidal current and the first three-phase flux without burrs and the second sinusoidal current and the second three-phase flux without burrs. n Subharmonic rotor excitation flux and three-phase inductance, n is a positive integer. i d =0 condition, the three-phase flux without burrs is obtained, and the d-axis component of the flux is obtained by Park transformation ψ D , which is the rotor excitation flux ψ f . Take the excitation flux k Results at simulation steps ψ f,k , by inverse Park transform C k -1 The three-phase stationary coordinate system does not contain 3 n The excitation flux of the subharmonic. f The three-phase flux without burrs obtained under 2 working conditions is transformed using Park C k Get the component of the flux in the dq coordinate system, and then find the first k The three-phase inductance of the long-stator linear synchronous motor is obtained based on the sinusoidal current and the three-phase flux without burrs. First, the three-phase inductance of the long-stator linear synchronous motor in the dq coordinate system is obtained based on the sinusoidal current and the three-phase flux without burrs. k The inductance of a simulation step is as follows:

[0060] L D,k =( ψ D,k - ψ f,k ) / i d,k

[0061] L Q,k = ψ Q,k / i q,k

[0062] in, L D,k and L Q,k They are respectively the first and second coordinates of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis inductances of the simulation steps; ψ D,k and ψ Q,k They are the three-phase flux without burrs of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis flux linkages of simulation steps; ψ f,k For long stator linear synchronous motor k The excitation flux of the rotor under the simulation step size; i d,k and i q,k They are the sinusoidal current in the dq coordinate system. k The d-axis and q-axis currents for each simulation step.

[0063] In the first working condition, L D,k The result is infinite, so L D,k Only in the second working condition, the solution needs to be based on the rotor excitation flux ψ f,k calculate L D,k , ψ f,k exist i d =0 working condition; L Q,k It can be solved under both working conditions. In practice, L D,k and L Q,k All the solutions are obtained under the second working condition.

[0064] The long stator linear synchronous motor is placed in the dq coordinate system. k The inductance of each simulation step is transformed by Park transformation and inverse Park transformation in turn to obtain the first inductance of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase inductance under simulation steps L 3s,k,as follows:

[0065]

[0066] Long stator linear synchronous motor does not include 3 n The subharmonic rotor excitation flux is obtained based on the sinusoidal current and the three-phase flux without burrs. First, the three-phase flux without burrs under the condition of zero d-axis current is transformed by Park to obtain the subharmonic of the long stator linear synchronous motor in the dq coordinate system. k Flux linkage of simulation step ψ 2r,k ,as follows:

[0067] ψ 2r,k = C k [ ψ D,k ψ Q,k ψ 0,k ] T

[0068] in, ψ 0,k To include 3 n The zero-sequence component of the flux of the subharmonic.

[0069] Thus, the long stator linear synchronous motor is obtained in the first k The excitation flux of the rotor under the simulation step size ψ f,k , the long stator linear synchronous motor is placed in the k The excitation flux of the rotor under the simulation step size ψ f,k The first coordinate of the long stator linear synchronous motor in the three-phase stationary coordinate system is obtained by inverse Park transformation. k The simulation steps do not include 3 n Subharmonic rotor excitation flux ψ f,3s,k ,as follows:

[0070] ψ f,3s,k = C k -1 [ ψ f,k 0 0] T

[0071] exist i d =0, the d-axis component of the three-phase flux ψ D,k With the rotor excitation flux ψf,k same.

[0072] Write the current derivative and flux derivative in the voltage equation of the long stator linear synchronous motor in the three-phase stationary coordinate system into backward difference form, and then the three-phase voltage of the long stator linear synchronous motor can be obtained u 3s,k , as follows:

[0073] u 3s,k = Ri 3s,k + L ( i 3s,k - i 3s,k-1 ) / T d +( ψ 3s,k - ψ 3s,k-1 ) / T d

[0074] Long stator linear synchronous motor k Three-phase stator flux results at simulation steps ψ 3s,k It can be decomposed into the following form:

[0075] ψ 3s,k = L 3s,k i 3s,k + ψ f,3s,k

[0076] Then the three-phase current recursive model of the long stator linear synchronous motor is established, as follows:

[0077] i 3s,k = A k -1 b k

[0078] A k =( R + L / T d ) I 3+ L 3s,k / T d

[0079] b k = u 3s,k +( L 3s,k-1 + LI 3) i 3s,k-1 / T d -( ψ f,3s,k - ψ f,3s,k-1 ) / T d

[0080] in, i 3s,k and u 3s,k They are respectively the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase current matrix of simulation step length and the current matrix without 3 n The expected value matrix of three-phase voltage of subharmonics, i 3s,k-1 The long stator linear synchronous motor is in the three-phase stationary coordinate system. k -Three-phase current matrix of 1 simulation step; A k and b k Respectively k The first and second intermediate variables at simulation steps; R is the phase resistance of the long stator linear synchronous motor; L It is the external circuit leakage inductance of the long stator linear synchronous motor; T d is the simulation step length; I 3 is the third-order unit matrix; L 3s,k and L 3s,k-1 They are respectively the first and second coordinates of the long stator linear synchronous motor in the three-phase stationary coordinate system. k and k -Three-phase inductance at 1 simulation step; ψ f,3s,k and ψ f,3s,k-1 They are the stator linear synchronous motor in the three-phase stationary coordinate system. k and k -1 simulation step does not include 3 n Subharmonic rotor excitation flux.

[0081] The three-phase inductance of the long stator linear synchronous motor and the n The rotor excitation flux of subharmonics and excluding 3n The expected value of the three-phase voltage of the subharmonic is input into the three-phase current recursive model for processing, and multiple electrical cycles are iterated. After the three-phase current recursive model is processed, the first steady-state three-phase current is output.

[0082] Calculation does not include 3 n When the expected value of the three-phase voltage of the harmonic is k A given three-phase square wave voltage with a step size u AN,k , u BN,k , u CN,k Through Park Transform C k Get the voltage matrix in the d,q coordinate system, and convert the zero-sequence component u 0,k Set to zero, then pass the inverse Park transform C k -1 Calculate the k The step length does not include 3 n The expected value of the three-phase voltage of the subharmonic. n The expected value of the three-phase voltage of the subharmonic is obtained according to the given voltage source square wave voltage. First, the given voltage source square wave voltage is transformed by Park to obtain the subharmonic value in the dq coordinate system. k The d-axis and q-axis voltages of the simulation step length are then calculated according to the dq coordinate system. k The d-axis and q-axis voltages of the simulation step are inversely transformed to obtain the k The step length does not include 3 n The expected values ​​of the three-phase voltage of the subharmonics are as follows:

[0083] u 3s,k = C k -1 [ u d,k u q,k 0] T

[0084] in, u d,k and u q,k They are respectively k The d-axis and q-axis voltages for each simulation step.

[0085] The neutral point of the given voltage source is not short-circuited with the neutral point of the long-stator linear synchronous motor.

[0086] In the dq coordinate system kThe d-axis and q-axis voltages for each simulation step are as follows:

[0087] [ u d,k u q,k u 0,k ] T = C k [ u AN,k u BN,k u CN,k ] T

[0088] in, u AN,k , u BN,k and u CN,k The voltage source is given in the k Square wave voltages of phases A, B and C at simulation steps; u 0,k For the k The zero-sequence component voltage at simulation steps.

[0089] The first k Zero-sequence component voltage at simulation step u 0,k Set it to zero, and then use the inverse Park change to get the k The step length does not include 3 n Expected values ​​of three-phase voltages of subharmonics.

[0090] When using the three-phase current recursive model to iterate, the three-phase current of the long stator linear synchronous motor is asymmetric in the initial stage. After iterating several electrical cycles, the three-phase current of the long stator linear synchronous motor becomes symmetric. When the three-phase current of the long stator linear synchronous motor is symmetric, the three-phase current matrix of the long stator linear synchronous motor in one electrical cycle in the three-phase stationary coordinate system is the first steady-state three-phase current.

[0091] The first steady-state three-phase current is used as the three-phase winding current excitation of the long stator linear synchronous motor, so as to obtain the phase voltage of the long stator linear synchronous motor in 0.5 electrical cycle according to the finite element simulation model, and then the three-phase voltage of one electrical cycle is calculated by the symmetric method. n The expected value of the three-phase voltage of the subharmonics is used to obtain the voltage difference. First, the three-phase voltage and the voltage without the harmonics are summed. n The expected values ​​of the three-phase voltages without harmonics are subtracted to obtain the intermediate voltage difference, and then the nThe final voltage difference is obtained by subtracting the intermediate voltage difference from the expected value of the three-phase voltage of the subharmonic. The voltage difference is used to replace the first harmonic of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase voltage matrix of simulation step u 3s,k As the input of the three-phase current recursive model, the first steady-state current excitation of an electrical cycle is calculated by finite element method. k The phase voltage of each step is u 3s1,k , the difference between this phase voltage and the expected value of the three-phase voltage is Δ u 1,k = u 3s1,k - u 3s,k , the three-phase current recursive model used in the second iteration to calculate the second steady-state three-phase current u 3s,k Depend on u 3s,k -Δ u 1,k After iterating multiple electrical cycles, the three-phase current recursive model is processed to output the second steady-state three-phase current. The current result of one electrical cycle under the speed condition of 600km / h is as follows: Figure 4 shown.

[0092] Finally, the second steady-state three-phase current is used as the current source excitation of the long-stator linear synchronous motor, and the electromagnetic performance under the square wave voltage condition is obtained according to the finite element simulation model, including the three-phase current and electromagnetic force of the long-stator linear synchronous motor in the steady state, so as to determine the optimal motor structure parameters to realize the design of the long-stator linear synchronous motor. In the specific implementation, the present invention uses the finite element model to simulate and calculate 0.5 electrical cycles, and takes the traction force results for the analysis of the method of the present invention.

[0093] This embodiment calculates the traction force under two groups of speed conditions as shown in Table 1 below. Table 1 is the external circuit parameter configuration of the finite element model. Figure 3 The current source in the external circuit shown is replaced by a voltage source, and the voltage source parameters are set according to the square wave voltage amplitude and square wave voltage conduction angle in Table 1. The finite element model is used to simulate 40 electrical cycles to obtain the traction results. f x The transient to steady state transition process of the traction simulation at 600 km / h is as follows: Figure 5 As shown. Taking the electromagnetic force of the 40th cycle as the basis, calculate the i The error of traction force per electrical cycle f xerr ( i ), as follows:

[0094] f xerr ( i )=(∑ j=1 Nstep ( f x ( iN step + j )- f x (39 iN step + j ))) 1 / 2

[0095] in, N step is the number of simulation steps for one electrical cycle, N step = T s / T d +1; f x ( ) is the traction result under a certain step length; j The first j step.

[0096] Then the variation of the traction force error with the electrical cycle under the two speed conditions is obtained, such as Figure 6 As shown. Figure 6 It can be seen that the simulation errors of the two groups of speed conditions do not become stable until 15 electrical cycles have been simulated.

[0097] Table 1

[0098]

[0099] Then, the traction force error of the method of the present invention is calculated at different speeds, and compared with the traction force errors of the 10th and 11th cycles of the finite element simulation using a voltage source directly, as shown in Table 2. It can be seen that under the working conditions studied in this embodiment, the method of the present invention only needs 2 electrical cycles of finite element simulation to reduce the traction force error to the error level of at least the 11th electrical cycle of the finite element simulation using a voltage source directly. The traction force calculation results of the two methods are shown in Table 3, which shows that the calculation accuracy of the method of the present invention is higher.

[0100] Table 2

[0101]

[0102] Table 3

[0103]

[0104] As a preferred embodiment, the stator segment length is optimized. l s , so that the traction force fluctuation is minimized. Under the operating conditions of a speed of 600 km / h, a square wave voltage amplitude of 12.5 kV, and an average traction force of about 112 kN, this embodiment calculates the following five groups of stator segment lengths: l s The traction force fluctuations are shown in Table 4. l s The increase in phase resistance R And external circuit leakage inductance L becomes larger, causing the square wave voltage conduction angle to decrease, resulting in changes in the voltage and current harmonic content, and ultimately causing changes in traction force fluctuations. Figure 7 It can be seen that when the stator segment length is 1.5 km, the traction force fluctuation is the smallest, which can be used as the optimal design scheme.

[0105] Table 4

[0106]

[0107] It can be seen from this embodiment that the method of the present invention can quickly and accurately complete the simulation study of the steady-state electromagnetic performance of the long-stator linear synchronous motor of the high-speed maglev transportation system under the power supply of the voltage source, avoiding the simulation of the complete transient process in the finite element simulation software, and has the advantages of fast calculation speed, high accuracy, and applicability to different speed conditions. The recursive model used in the numerical calculation process is based on the conventional three-phase synchronous motor voltage equation, the principle is simple, and it is easy to program and implement. Ultimately, it can be applied to other different types of three-phase synchronous motor voltage source simulation conditions, providing new ideas for the design of three-phase synchronous motors.

[0108] It should be understood by those skilled in the art that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, optical storage, etc.) containing computer-usable program codes. The schemes in the embodiments of the present application may be implemented in various computer languages. The present application is described according to the flowcharts of the methods, systems and computer program products of the embodiments of the present application.

[0109] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the scope of protection of the present invention.

Claims

1. A design method for a long-stator linear synchronous motor powered by a voltage source, characterized in that: include: Step 1) constructing a finite element simulation model of a long stator linear synchronous motor; Step 2) Obtain a first sinusoidal current generated by a sinusoidal current source under the condition that the d-axis current is zero and a second sinusoidal current having the same effective value as the first sinusoidal current and a phase lag or lead by a preset angle, and use the first and second sinusoidal currents as the stator three-phase winding excitation of the long stator linear synchronous motor, thereby obtaining the three-phase inductance and the inductance excluding 3 according to the finite element simulation model. n Subharmonic mover excitation flux; Step 3) Establish a three-phase current recursive model, and transform the three-phase inductance and the n The rotor excitation flux of subharmonics and excluding 3 n The expected value of the three-phase voltage of the subharmonic is input into the three-phase current recursive model for processing, and the three-phase current recursive model outputs the first steady-state three-phase current after processing; Step 4) The first steady-state three-phase current is used as the three-phase winding current excitation of the long stator linear synchronous motor, so that the three-phase voltage obtained by the finite element simulation model is obtained according to the three-phase voltage and the current excluding 3 n The voltage difference is obtained by using the expected value of the three-phase voltage of the subharmonic and inputted into the three-phase current recursive model for processing. After the three-phase current recursive model is processed, the second steady-state three-phase current is output; Step 5) using the second steady-state three-phase current as a current source excitation for the long-stator linear synchronous motor, obtaining electromagnetic performance under a square wave voltage condition according to a finite element simulation model, thereby determining optimal motor structural parameters to achieve the design of the long-stator linear synchronous motor; In the step 3), the three-phase current recursive model is as follows: i 3s,k = A k -1 b k A k =( R + L / T d ) I 3+ L 3s,k / T d b k = u 3s,k +( L 3s,k-1 + LI 3) i 3s,k-1 / T d -( ψ f,3s,k - ψ f,3s,k-1 ) / T d in, i 3s,k and u 3s,k They are respectively the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase current matrix of simulation step length and the current matrix without 3 n The expected value matrix of three-phase voltage of subharmonics, i 3s,k-1 The long stator linear synchronous motor is in the three-phase stationary coordinate system. k -Three-phase current matrix of 1 simulation step; A k and b k Respectively k The first and second intermediate variables at simulation steps; R is the phase resistance of the long stator linear synchronous motor; L It is the external circuit leakage inductance of the long stator linear synchronous motor; T d is the simulation step length; I 3 is the third-order unit matrix; L 3s,k and L 3s,k-1 They are respectively the first and second coordinates of the long stator linear synchronous motor in the three-phase stationary coordinate system. k and k -Three-phase inductance at 1 simulation step; ψ f,3s,k and ψ f,3s,k-1 They are the stator linear synchronous motor in the three-phase stationary coordinate system. k and k -1 simulation step does not include 3 n Subharmonic mover excitation flux; When using the three-phase current recursive model to iterate, the three-phase current of the long stator linear synchronous motor is asymmetric in the initial stage. After iterating several electrical cycles, the three-phase current of the long stator linear synchronous motor becomes symmetric. When the three-phase current of the long stator linear synchronous motor is symmetric, the three-phase current matrix of the long stator linear synchronous motor in one electrical cycle in the three-phase stationary coordinate system is the first steady-state three-phase current.

2. The method for designing a long-stator linear synchronous motor powered by a voltage source according to claim 1, characterized in that: In the step 2), the first sinusoidal current and the second sinusoidal current are respectively used as the stator three-phase winding excitation of the long stator linear synchronous motor, and then the first three-phase flux and the second three-phase flux containing burrs in one electrical cycle of the long stator linear synchronous motor are respectively obtained by the finite element simulation model, and the first three-phase flux and the second three-phase flux without burrs in one electrical cycle of the long stator linear synchronous motor are respectively obtained by the harmonic analysis method, and then the first three-phase flux without burrs and the second three-phase flux without burrs of the long stator linear synchronous motor are respectively obtained according to the first sinusoidal current and the first three-phase flux without burrs and the second sinusoidal current and the second three-phase flux without burrs. n Subharmonic rotor excitation flux and three-phase inductance.

3. The design method of a long-stator linear synchronous motor powered by a voltage source according to claim 2, characterized in that: The three-phase inductance of the long-stator linear synchronous motor is obtained according to the sinusoidal current and the three-phase flux without burrs. First, the three-phase inductance of the long-stator linear synchronous motor in the dq coordinate system is obtained according to the sinusoidal current and the three-phase flux without burrs. k The inductance of a simulation step is as follows: L D,k =( ψ D,k - ψ f,k ) / i d,k L Q,k = ψ Q,k / i q,k in, L D,k and L Q,k They are respectively the first and second coordinates of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis inductances of the simulation steps; ψ D,k and ψ Q,k They are the three-phase flux without burrs of the long stator linear synchronous motor in the dq coordinate system. k The d-axis and q-axis flux linkages of simulation steps; ψ f,k For long stator linear synchronous motor k The excitation flux of the rotor under the simulation step size; i d,k and i q,k They are the sinusoidal current in the dq coordinate system. k The d-axis and q-axis currents of simulation steps; The long stator linear synchronous motor is placed in the dq coordinate system. k The inductance of each simulation step is transformed by Park transformation and inverse Park transformation to obtain the first inductance of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase inductance under simulation steps L 3s,k .

4. The method for designing a long stator linear synchronous motor powered by a voltage source according to claim 2, characterized in that: The long stator linear synchronous motor does not include 3 n The subharmonic rotor excitation flux is obtained based on the sinusoidal current and the three-phase flux without burrs. First, the three-phase flux without burrs under the condition of zero d-axis current is transformed by Park to obtain the subharmonic of the long stator linear synchronous motor in the dq coordinate system. k Flux linkage of simulation step ψ 2r,k , thus obtaining the long stator linear synchronous motor in the first k The excitation flux of the rotor under the simulation step size ψ f,k , the long stator linear synchronous motor is placed in the k The excitation flux of the rotor under the simulation step size ψ f,k The first coordinate of the long stator linear synchronous motor in the three-phase stationary coordinate system is obtained by inverse Park transformation. k The simulation steps do not include 3 n Subharmonic rotor excitation flux ψ f,3s,k .

5. The method for designing a long-stator linear synchronous motor powered by a voltage source according to claim 1, characterized in that: In the step 3), 3 n The expected value of the three-phase voltage of the subharmonic is obtained according to the given voltage source square wave voltage. First, the given voltage source square wave voltage is transformed by Park to obtain the subharmonic value in the dq coordinate system. k The d-axis and q-axis voltages of the simulation step length are then calculated according to the dq coordinate system. k The d-axis and q-axis voltages of the simulation step are inversely transformed to obtain the k The step length does not include 3 n The expected values ​​of the three-phase voltage of the subharmonics are as follows: u 3s,k = C k -1 [ u d,k u q,k 0] T in, u d,k and u q,k They are respectively k The d-axis and q-axis voltages for each simulation step.

6. The method for designing a long stator linear synchronous motor powered by a voltage source according to claim 1, characterized in that: In the step 4), according to the three-phase voltage and excluding 3 n The expected value of the three-phase voltage of the subharmonics is used to obtain the voltage difference. First, the three-phase voltage and the voltage without the harmonics are summed. n The expected values ​​of the three-phase voltages without harmonics are subtracted to obtain the intermediate voltage difference, and then the n The final voltage difference is obtained by subtracting the intermediate voltage difference from the expected value of the three-phase voltage of the subharmonic; The three-phase voltage will be n The voltage difference obtained by the expected value of the three-phase voltage of the subharmonic replaces the voltage difference of the long stator linear synchronous motor in the three-phase stationary coordinate system. k The three-phase voltage matrix of simulation step u 3s,k As the input of the three-phase current recursive model.

7. The method for designing a long-stator linear synchronous motor powered by a voltage source according to claim 1, characterized in that: In the step 5), the electromagnetic performance under the square wave voltage condition includes the three-phase current and electromagnetic force of the long stator linear synchronous motor in a steady state.

8. An electronic device, characterized in that: include: A memory and a processor coupled to each other, wherein the memory stores program data, and the processor calls the program data to execute the method according to any one of claims 1 to 7.

9. A computer-readable storage medium having program data stored thereon, characterized in that: When the program data is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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