Permanent magnet auxiliary synchronous reluctance motor control method and system considering eddy current reaction

Abstract

The invention discloses a permanent magnet auxiliary synchronous reluctance motor control method and system considering eddy current reaction, and the method comprises the steps: building a motor magnetic impedance model considering the eddy current reaction effect, the magnetic saturation effect and the dq-axis cross coupling effect based on a vector magnetic circuit theory; calculating the magnetomotive force of the armature winding and the permanent magnet magnetomotive force of the interpolated ferrite; obtaining a stator flux linkage equation based on magnetomotive force and the motor magnetic impedance model; based on the stator flux linkage equation and the voltage equation, constructing a multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model; measuring a magnetic induction coefficient value in the motor magnetic impedance model based on a vector magnetic circuit theory magnetoelectric power law; and designing the maximum torque current ratio control method of the permanent magnet auxiliary synchronous reluctance motor based on the multi-factor coupled motor control model. According to the method, the reaction of the eddy current in the permanent magnet auxiliary synchronous reluctance motor on the stator flux linkage is quantitatively considered, the method has definite physical significance and higher modeling precision, and performance improvement of a control system is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic circuit theory and motor drive system, and in particular relates to a permanent magnet assisted synchronous reluctance motor control method and system taking eddy current reaction into account. Background Art

[0002] In recent years, permanent magnet assisted synchronous reluctance motors have attracted more and more attention from the industry due to their advantages such as high efficiency, high power factor and good dynamic performance. They have been widely used in the field of electric transmission, especially high-performance electric drive. In many medium-power applications, permanent magnet assisted synchronous reluctance motors are gradually replacing permanent magnet synchronous motors due to their performance and cost advantages.

[0003] The mathematical model of the motor is the theoretical basis of motor control. Accurately establishing the mathematical model of the permanent magnet assisted synchronous reluctance motor is a necessary condition for achieving its high-performance control. The current mathematical model of the permanent magnet assisted synchronous reluctance motor is limited to considering the magnetic saturation effect and the cross-coupling effect, and it is difficult to take into account the reaction of eddy currents to the magnetic flux. However, due to the inherent characteristics of the reluctance motor and the insertion of ferrites in the stator core of the permanent magnet assisted synchronous reluctance motor, its eddy current phenomenon is stronger than other motors of the same power level, so modeling taking into account the reaction of eddy currents is of great significance.

[0004] Most of the current models of permanent magnet assisted synchronous reluctance motors only consider magnetic saturation effects and cross-coupling effects. On this basis, some scholars take iron loss into account, equating it to a resistor connected in parallel between the motor's back electromotive force and inductance, and derive the fitting method of iron loss resistance. However, the physical meaning of this type of mathematical model is vague, and a large amount of experimental data is required to obtain a relatively accurate motor mathematical model within a certain range of operating conditions. Moreover, this type of motor model is usually only suitable for steady-state analysis. Summary of the invention

[0005] The purpose of the present invention is to provide a permanent magnet assisted synchronous reluctance motor control method and system taking into account the reaction of eddy current, which quantitatively takes into account the reaction of eddy current to stator flux, has clear physical meaning and higher modeling accuracy, and is conducive to improving the performance of the control system.

[0006] In order to achieve the above object, the solution of the present invention is:

[0007] A permanent magnet assisted synchronous reluctance motor control method taking into account eddy current reaction, comprising:

[0008] Based on the vector magnetic circuit theory, a motor magnetic impedance model is constructed that takes into account the eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect.

[0009] Calculate the magnetomotive force of the armature winding and the permanent magnet magnetomotive force of the inserted ferrite;

[0010] Obtaining a stator flux equation based on the magnetomotive force and the motor magnetic impedance model;

[0011] Based on the stator flux equation and voltage equation, a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model is constructed;

[0012] Based on the magnetoelectric power law of vector magnetic circuit theory, the magnetic induction coefficient value in the motor magnetic impedance model is measured by using the iron loss separation method;

[0013] A maximum torque-to-current ratio control method is designed based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model.

[0014] Among them, the motor magnetic impedance model considering eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect is constructed based on the vector magnetic circuit theory, including:

[0015] Based on the vector magnetic circuit theory, the motor magnetic impedance model in the three-phase stationary coordinate system is obtained:

[0016]

[0017] Among them, F A ,F B ,F C They are the magnetomotive force of the three-phase windings ABC, R(θ) is the magnetic resistance, L m It's magnetic induction. They are the magnetic flux of the three-phase windings ABC respectively;

[0018] The motor magnetic impedance model in the three-phase stationary coordinate system is subjected to Clark transformation and Park transformation to obtain the motor magnetic impedance model in the two-phase rotating coordinate system:

[0019]

[0020] Among them, F d ,F q They are the magnetomotive force components of the dq-axis armature winding, R dd is the d-axis magnetic resistance, R qq is the q-axis magnetic resistance, R dq is the magnetoresistance term corresponding to the inverse magnetomotive force term caused by the cross-coupling of the dq-axis flux linkage, They are dq axis flux, N is the number of turns of each phase winding of the motor, L dd is the armature d-axis self-inductance, L qq is the armature q-axis self-inductance, L dq is the mutual inductance between the d-axis and the q-axis, and ω is the motor current angular frequency.

[0021] Among them, the calculation of the armature winding magnetomotive force includes,

[0022] The calculation formula of the armature winding magnetomotive force is:

[0023]

[0024] Among them, F d is the magnetomotive force component of the d-axis armature winding, F q is the magnetomotive force component of the q-axis armature winding, i d is the d-axis current, i q is the q-axis current.

[0025] Among them, the calculation of the permanent magnet magnetomotive force of the interpolated ferrite includes,

[0026] The calculation formula of permanent magnet magnetomotive force is:

[0027]

[0028] Among them, F dψ is the magnetomotive force of the ferrite permanent magnet flux acting on the d-axis, F qψ is the magnetomotive force of the ferrite permanent magnet flux acting on the q axis, ψ f It is the permanent magnet flux linkage value corresponding to ferrite.

[0029] Wherein, the stator flux equation is obtained based on the magnetomotive force and the motor magnetic impedance model, including:

[0030] The calculation formula of the stator flux equation is:

[0031]

[0032] Among them, ψ d is the d-axis flux, ψ q is the q-axis flux; k is the magnetic induction coefficient, which is related to the magnetic induction value L m Proportional to L Δ is the coupled equivalent inductance.

[0033] Among them, a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model is constructed, including:

[0034]

[0035] Among them, u d is the d-axis voltage, u q is the q-axis voltage, R s is the stator resistance, is the d-axis incremental inductance, is the q-axis incremental inductance, is the incremental inductance of the cross coupling between the d-axis and the q-axis; T e is the electromagnetic torque, N pis the number of motor pole pairs.

[0036] Among them, based on the magnetoelectric power law of vector magnetic circuit theory, the iron loss separation method is used to measure the magnetic induction coefficient value in the motor magnetic impedance model, including:

[0037] First, according to the magnetoelectric power law of vector magnetic circuit theory:

[0038] P ironloss =kU 2

[0039] Among them, U is the motor terminal voltage, P ironloss is the iron loss, k is the magnetic induction coefficient;

[0040] Calculate the iron loss of the motor:

[0041] P ironloss =P in -P Te -P Cu -P mech

[0042] x=1.5[(u d -R s i d ) 2 +(u q -R s i q ) 2 ]

[0043] y=P in -P Te -P Cu

[0044] Among them, P in is the motor input power, P Te is the torque output power, P Cu is the copper loss, P mech is the mechanical loss; x is the horizontal axis of the coordinate system, and y is the vertical axis of the coordinate system;

[0045] By changing the current and load torque of the motor's direct and quadrature axes, a series of data points can be obtained in the xy coordinate system. When the motor operates in the linear region of the magnetic field, these data points will form a straight line, the slope of which is the value of the magnetic induction coefficient k, and the intercept of the y-axis is the mechanical loss.

[0046] The maximum torque-to-current ratio control method is designed based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model, including:

[0047] L dd =L dd (i d ,i q )

[0048] L dq =L dq (i d ,i q )

[0049] L qq =L qq (i d ,i q )

[0050] ψ f =ψ f (i d ,i q )

[0051] k=k(i d ,i q )

[0052] R s =R0[1+α(T-T0)]

[0053]

[0054] Among them, R s is the resistance at temperature T, R0 is the resistance at temperature T0, α is the temperature coefficient of resistance; T e is the electromagnetic torque, is the electromagnetic torque reference value, is the d-axis current reference value.

[0055] A permanent magnet assisted synchronous reluctance motor control system taking into account eddy current reaction, comprising:

[0056] A magnetic impedance model calculation unit is configured to construct a motor magnetic impedance model taking into account eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect based on vector magnetic circuit theory;

[0057] An armature winding magnetomotive force calculation unit, configured to calculate the armature winding magnetomotive force;

[0058] a permanent magnet magnetomotive force calculation unit configured to calculate the permanent magnet magnetomotive force of the interpolated ferrite;

[0059] A stator flux equation calculation unit is configured to obtain a stator flux equation based on the magnetomotive force and the motor magnetic impedance model;

[0060] A motor control model building unit is configured to build a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model based on the stator flux equation and the voltage equation;

[0061] A magnetic induction coefficient value measuring unit is configured to measure the magnetic induction coefficient value in the motor magnetic impedance model by using the magnetoelectric power law based on the vector magnetic circuit theory and the iron loss separation method; and

[0062] The maximum torque-to-current ratio control unit is configured to design a maximum torque-to-current ratio control method based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model.

[0063] After adopting the above scheme, the beneficial effects of the present invention are:

[0064] (1) The present invention takes into account the eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect to establish a motor magnetic impedance model different from the traditional model, and quantitatively characterizes the reaction of eddy current to stator flux linkage with the help of magnetic induction parameters; compared with the traditional method of equivalent iron loss at the motor back electromotive force end and inductor parallel resistance, the model of the present invention has a clear physical meaning for modeling iron loss;

[0065] (2) The model proposed in the present invention can introduce magnetic induction parameters that can be calculated through a clear scheme, and the influence of magnetic saturation on magnetic induction can be taken into account. After calculating its value at the rated or specific frequency, the skin effect of the magnetic flux can be used to calculate the magnetic induction coefficient value at other frequencies. Compared with the traditional modeling method that requires a large number of experiments and data fitting, the modeling method proposed in the present invention is more practical because it only requires one measurement experiment;

[0066] (3) The model proposed in the present invention can use current ripple to calculate the iron loss caused by switching subharmonics. Compared with the traditional method of calculating iron loss using voltage ripple while ignoring copper loss resistance drop, the model based on vector magnetic circuit theory has higher accuracy and feasibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0068] Figure 1 It is a step diagram of a modeling method and a control system of a permanent magnet assisted synchronous reluctance motor taking into account eddy current reaction effect of the present invention;

[0069] Figure 2 It is an equivalent circuit diagram that only considers the cross-coupling effect and magnetic saturation effect;

[0070] Among them, (a) is the equivalent circuit diagram considering only the cross-coupling effect, and (b) is the equivalent circuit diagram considering only the magnetic saturation effect;

[0071] Figure 3 It is the equivalent circuit diagram of the iron loss model of parallel resistors;

[0072] Among them, (a) is the equivalent circuit diagram of the d-axis, and (b) is the equivalent circuit diagram of the q-axis;

[0073] Figure 4 It is the dq axis equivalent magnetic circuit diagram based on the vector magnetic circuit theory;

[0074] Among them, (a) is the equivalent magnetic circuit diagram of the d-axis, and (b) is the equivalent magnetic circuit diagram of the q-axis;

[0075] Figure 5 It is the definition and relationship diagram of incremental inductance and apparent inductance after considering magnetic saturation effect;

[0076] Figure 6 It is the equivalent circuit diagram of the permanent magnet assisted synchronous reluctance motor based on the vector magnetic circuit theory;

[0077] Among them, (a) is the equivalent circuit diagram of the d-axis, and (b) is the equivalent circuit diagram of the q-axis.

[0078] Figure 7 This is a flow chart of a dual closed-loop control system of a permanent magnet assisted synchronous reluctance motor based on vector magnetic circuit theory modeling;

[0079] Figure 8 It is a graph that measures the magnetic induction coefficient using the law of energy conservation at a given frequency;

[0080] Fig. 9 It is a parameter value diagram of the inductance and permanent magnet flux linkage of the permanent magnet assisted synchronous reluctance motor under different working conditions obtained by finite element software simulation;

[0081] Where (a) is L dd The value of L under different working conditions is shown in (b). qq The value of L under different working conditions is shown in (c). dq The value of ψ under different working conditions, (d) is f Plots of values ​​under different operating conditions;

[0082] Fig.10 It is a comparison diagram of the maximum torque-to-current ratio operating points obtained by using the traditional cross-coupling model, the model taking into account the eddy current reaction proposed in the present invention, and the ergodic search method for the permanent magnet assisted synchronous reluctance motor prototype based on the DSP controller under different load torque conditions;

[0083] Among them, the circular points are the calculation results of the traversal search method, the square points are the calculation results of the traditional cross-coupling model, and the triangular points are the calculation results of the model taking into account the eddy current reaction; (a) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under 6 different load torque conditions, (b) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 0.5 N·m, (c) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 1.0 N·m, (d) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 1.5 N·m, (e) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 2.0 N·m, (f) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 2.5 N·m, and (g) is a comparison diagram of the maximum torque-to-current ratio working points obtained by the three methods under the load torque of 3.0 N·m. DETAILED DESCRIPTION

[0084] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] The flux equation of the traditional three-phase permanent magnet assisted synchronous reluctance motor in the rotating coordinate system that only considers the dq axis cross-coupling effect can be written as:

[0086]

[0087] Among them, ψ d is the d-axis flux, ψ q is the q-axis magnetic flux, i d is the d-axis current, i q is the q-axis current, L dd is the armature d-axis self-inductance, L qq is the armature q-axis self-inductance, L dq is the mutual inductance between the d-axis and the q-axis, ψ f It is the permanent magnet flux linkage value corresponding to ferrite.

[0088] Substituting the voltage equation into the equation yields the following mathematical model:

[0089]

[0090] Among them, u d is the d-axis voltage, u q is the q-axis voltage, R s is the stator resistance, is the d-axis incremental inductance, is the q-axis incremental inductance, is the incremental inductance of the cross-coupling between the d-axis and the q-axis. The traditional model only considers the magnetic saturation effect and the cross-coupling effect between the d-axis and the q-axis, without considering the reaction of the eddy current. Its equivalent circuit is as follows: Figure 2 shown.

[0091] In order to calculate the eddy current loss, some models connect the iron loss resistor in parallel with the back EMF and the inductor. The equivalent circuit is as follows: Figure 3 As shown. c E is the iron loss resistor, and the active power loss on the resistor is equal to the iron loss power. d and E q are the back EMF of the d-axis and q-axis respectively, satisfying:

[0092]

[0093] Since the voltage equation is a very complex multivariate high-order differential equation, it is difficult to establish an analytical relationship between voltage and current in the dynamic process. In order to simplify the model, usually only the steady-state situation can be considered.

[0094] In order to simplify the model, the following assumptions are made for the modeling method of the permanent magnet assisted synchronous reluctance motor based on vector magnetic circuit theory:

[0095] (1) Ignore spatial harmonics and assume that the three-phase windings are symmetrical. In electrical angle, the generated magnetomotive force is distributed along the air gap according to the sinusoidal law;

[0096] (2) Ignore hysteresis loss;

[0097] (3) Ignore the effects of frequency and temperature changes on winding resistance;

[0098] (4) Assume that parameters such as inductance and permanent magnet flux do not change with temperature;

[0099] like Figure 1 As shown, the modeling method of the permanent magnet assisted synchronous reluctance motor taking into account the eddy current reaction effect includes the following steps:

[0100] S1, the motor magnetic impedance model considering the eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect, uses the magnetic induction parameters in the vector magnetic circuit theory to quantitatively characterize the reaction of eddy current to magnetic flux.

[0101] According to the vector magnetic circuit theory, the motor magnetic impedance model in the three-phase stationary coordinate system can be obtained:

[0102]

[0103] Among them, F A ,FB ,F C They are the magnetomotive force of the three-phase windings ABC, R(θ) is the magnetic resistance, L m It's magnetic induction. They are the magnetic flux of the three-phase windings ABC respectively; through Clark transformation and Park transformation, the motor magnetic impedance model in the two-phase rotating coordinate system can be obtained as follows:

[0104]

[0105] Among them, F d ,F q They are the magnetomotive force components of the dq-axis armature winding, R dd is the d-axis magnetic resistance, R qq is the q-axis magnetic resistance, R dq is the magnetoresistance term corresponding to the inverse magnetomotive force term caused by the cross-coupling of the dq-axis flux linkage, They are dq axis flux, ω is the motor current angular frequency, N is the number of turns of each phase winding of the motor, L dd is the armature d-axis self-inductance, L qq is the armature q-axis self-inductance, L dq is the mutual inductance between the d-axis and the q-axis. Figure 4 The equivalent magnetic circuit diagram corresponding to the permanent magnet motor magnetic impedance model shown includes magnetic resistance, magnetic induction and magnetomotive force, and the magnetomotive force includes armature magnetomotive force and permanent magnet magnetomotive force;

[0106] S2, calculate the armature winding magnetomotive force; the calculation formula for the armature winding magnetomotive force is:

[0107]

[0108] Among them, F d is the magnetomotive force component of the d-axis armature winding, F q is the magnetomotive force component of the q-axis armature winding, i d is the d-axis current, i q is the q-axis current.

[0109] S3, calculate the permanent magnet magnetomotive force of the inserted ferrite; the calculation formula for the permanent magnet magnetomotive force is:

[0110]

[0111] Among them, F dψ is the magnetomotive force of the ferrite permanent magnet flux acting on the d-axis, F qψ is the magnetomotive force of the ferrite permanent magnet flux acting on the q axis, ψ f It is the permanent magnet flux linkage value corresponding to ferrite.

[0112] S4, derive the stator flux equation based on the magnetomotive force and magnetic impedance model; combine steps S1, S2 and S3, and use the superposition theorem to obtain the calculation formula of the stator flux equation:

[0113]

[0114] Among them, ψ d is the d-axis flux, ψ q is the q-axis flux; k is the magnetic induction coefficient, which is related to the magnetic induction value L m Proportional to L Δ is the coupled equivalent inductance.

[0115] S5, derive the motor control model with multi-factor coupling based on the voltage equation and the stator flux equation; the mathematical model of the motor is:

[0116]

[0117] Among them, u d is the d-axis voltage, u q is the q-axis voltage, R s is the stator resistance, is the d-axis incremental inductance, is the q-axis incremental inductance, is the incremental inductance of the cross-coupling between the d-axis and the q-axis. The relationship between the incremental inductance and the apparent inductance is as follows: Figure 5 As shown. Due to the influence of magnetic saturation, the incremental inductance value under the same working condition is often smaller than the apparent inductance. For convenience, the inductance values ​​without superscripts are uniformly regarded as apparent inductance, which is referred to as "inductance" in the present invention. The equivalent circuit of the permanent magnet assisted synchronous reluctance motor based on the vector magnetic circuit theory is shown in Figure 6 As shown. Figure 6 It can be seen that both the d-axis and q-axis circuits introduce additional coupling potentials, which are related to Figure 2 and Figure 3 There are obvious differences in the equivalent circuit shown. Since the iron loss expression is as follows:

[0118]

[0119] According to the law of conservation of energy, the power of electromagnetic torque is:

[0120] P Te =P in -P ironloss -P Cu (11)

[0121] Among them, P ironloss is the iron loss, P in is the motor input power, P Te is the torque output power, P Cu is the copper loss. The electromagnetic torque T is derivede The expression is:

[0122]

[0123] Among them, N p is the number of motor pole pairs, ω m is the mechanical angular velocity of the motor.

[0124] S6, based on the magnetoelectric power law of vector magnetic circuit theory, the magnetic induction coefficient value in the magnetic impedance model is measured by the iron loss separation method; the magnetic induction coefficient value measurement scheme is:

[0125] From the law of conservation of energy, we know that:

[0126] P ironloss =P in -P Te -P Cu -P mech (13)

[0127] Among them, P mech is the mechanical loss, which is related to the speed. It can be assumed that when the speed remains constant, the mechanical loss also remains constant.

[0128]

[0129] By changing the current and load torque of the motor's direct and quadrature axes, a series of data points will be obtained in the xy coordinate system. Among them, x is the horizontal axis of the coordinate system, and y is the vertical axis of the coordinate system. When the motor works in the linear region of the magnetic field, these data points will form a straight line. The slope of the straight line is the value of the magnetic induction coefficient k, and the intercept of the y-axis is the mechanical loss. When the motor works in the magnetic field saturation region, the change of the magnetic induction value is analyzed according to the definition of magnetic induction:

[0130]

[0131] Among them, Γ is the charge chain passing through the wire cross section per unit time, N is the number of turns, Q is the amount of charge passing through the wire cross section per unit time, is the magnetic flux. As the magnetic saturation increases, The value of decreases, and thus the magnetic induction decreases. Therefore, the collection of scattered points in the magnetic saturation region will form a convex function curve, and the slope of the curve can be approximately considered as the value of the magnetic induction coefficient k under this working condition. Since the q-axis current of the permanent magnet assisted synchronous reluctance motor is more obviously affected by magnetic saturation, as x increases, the q-axis current increases, the higher the degree of magnetic saturation, the smaller the value of the magnetic induction coefficient k, and the smaller the slope.

[0132] However, the above method can only calculate the magnetic induction coefficient k at a certain fixed frequency. When the motor operates in the magnetic field linear region, when the stator frequency reaches the region where the skin effect of the resistor cannot be ignored, the magnetic induction coefficient can be corrected as follows:

[0133]

[0134] Among them, k2 is the magnetic induction coefficient when the current angular frequency is ω2, and k1 is the magnetic induction coefficient when the current angular frequency is ω1. Therefore, under two different working conditions, the magnetic induction coefficient can be updated according to formula (16), and the magnetic induction coefficient under different frequencies is inversely proportional to the arithmetic square root of the frequency.

[0135] S7, design a maximum torque current ratio control method based on a multi-factor coupling control model; the maximum torque current ratio control system design method is as follows:

[0136] Due to the existence of electromagnetic magnetic saturation, the parameters such as magnetic induction coefficient, inductance, and flux linkage are closely related to the working conditions, that is, they satisfy:

[0137]

[0138] Resistance is mainly determined by temperature and satisfies:

[0139] R s =R0[1+α(T-T0)] (18)

[0140] Among them, R s is the resistance at temperature T, R0 is the resistance at temperature T0, and α is the temperature coefficient of resistance. The parameters of different operating points are made into a lookup table using finite element software in advance.

[0141] The maximum torque current ratio operating point is solved according to the following formula:

[0142]

[0143] in, is the d-axis current reference value, is the electromagnetic torque reference value.

[0144] The d-axis current reference value at the maximum torque current ratio operating point can be calculated offline based on the load and parameter lookup table.

[0145] The present invention also provides a permanent magnet assisted synchronous reluctance motor control system taking into account eddy current reaction, comprising:

[0146] A magnetic impedance model calculation unit is configured to construct a motor magnetic impedance model taking into account eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect based on vector magnetic circuit theory;

[0147] An armature winding magnetomotive force calculation unit, configured to calculate the armature winding magnetomotive force;

[0148] a permanent magnet magnetomotive force calculation unit configured to calculate the permanent magnet magnetomotive force of the interpolated ferrite;

[0149] A stator flux equation calculation unit is configured to obtain a stator flux equation based on the magnetomotive force and the motor magnetic impedance model;

[0150] A motor control model building unit is configured to build a multi-factor coupled motor control model based on the stator flux equation and the voltage equation;

[0151] The magnetic induction coefficient value measuring unit is configured to measure the magnetic induction coefficient value in the magnetic impedance model by using the magnetoelectric power law based on the vector magnetic circuit theory and the iron loss separation method; and

[0152] The maximum torque-to-current ratio control unit is configured to design a maximum torque-to-current ratio control method based on the multi-factor coupled motor control model.

[0153] In the present invention, a permanent magnet assisted synchronous reluctance motor model taking into account eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect is applied to an embodiment of a model-based motor control algorithm. Next, the effect of the model proposed in the present invention for maximum torque current ratio control is demonstrated. The control system flow chart is shown in FIG. Figure 7 As shown, it includes: a speed closed-loop PI regulator, a current PI regulator, a maximum torque current ratio control module, a three-phase two-level inverter, a three-phase permanent magnet assisted synchronous reluctance motor, a coordinate transformation module, a modulation wave calculation module, a position encoder and a speed calculation module.

[0154] The model-based maximum torque-to-current ratio algorithm usually requires the motor parameters to be known in advance. The permanent magnet flux linkage values ​​corresponding to the inductor and ferrite can be simulated by finite element software, while the value of the magnetic induction k needs to be measured experimentally. The parameters of the permanent magnet motor in the experiment are as follows: the number of pole pairs is 2, the stator resistance is 0.43Ω, the sampling frequency is 5kHz, the rated power is 1kW, the rated speed is 1500rpm, the rated torque is 3N·m, the rated current is 7A, and the rated voltage is 75V. According to step S8, the motor speed is set to 1000rpm, corresponding to a frequency of 33.3Hz, and a scatter plot between y and x can be obtained. A curve is fitted according to the point set, and the slope is the value of k, such as Figure 8 As shown. The expression of k is:

[0155]

[0156] When x<1500, the magnetic saturation is low, the motor is in the linear region, and the magnetic induction value is constant. When x>1500, the magnetic saturation increases, the motor is in the nonlinear region, and the magnetic induction value gradually decreases. The data of inductance and permanent magnet flux linkage simulated by finite element software at different working points are as follows: Fig. 9 shown.

[0157] Combining equations (17), (18), and (19), the d-axis current reference value at the maximum torque current ratio working point can be obtained. Since the equation exceeds 5 times, there is no analytical solution, and it is necessary to use the Newton iteration method to converge it to a numerical solution.

[0158] The experimental verification results of the present invention on solving the maximum torque current ratio working point are as follows Fig.10 shown. Fig.10 This is a comparison of the maximum torque-to-current ratio operating points obtained by the permanent magnet assisted synchronous reluctance motor prototype based on the DSP controller using the traditional model, the model based on the vector magnetic circuit theory proposed in this patent, and the traversal search method under different load torque conditions. The load torques are selected as 0.5N·m, 1.0N·m, 1.5N·m, 2.0N·m, 2.5N·m, and 3.0N·m, respectively. The circular icon is the maximum torque-to-current ratio operating point obtained by the traversal search, which is an accurate value in theory. The triangular icon is the maximum torque-to-current ratio operating point calculated by the model proposed in this invention, and the square icon is the maximum torque-to-current ratio operating point calculated by the traditional model. It can be seen that the calculation accuracy of the maximum torque-to-current ratio operating point of the model proposed in this invention is better than that of the traditional model.

[0159] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0160] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A permanent magnet assisted synchronous reluctance motor control method taking into account eddy current reaction, characterized in that: include, Based on the vector magnetic circuit theory, a motor magnetic impedance model is constructed that takes into account the eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect. Calculate the magnetomotive force of the armature winding and the permanent magnet magnetomotive force of the inserted ferrite; Obtaining a stator flux equation based on the magnetomotive force and the motor magnetic impedance model; Based on the stator flux equation and voltage equation, a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model is constructed; Based on the magnetoelectric power law of vector magnetic circuit theory, the magnetic induction coefficient value in the motor magnetic impedance model is measured by using the iron loss separation method; A maximum torque-to-current ratio control method is designed based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model.

2. The method according to claim 1, characterized in that: Based on the vector magnetic circuit theory, a motor magnetic impedance model is constructed that takes into account the eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect, including: Based on the vector magnetic circuit theory, the motor magnetic impedance model in the three-phase stationary coordinate system is obtained: Among them, F A ,F B ,F C They are the magnetomotive force of the three-phase windings ABC, R(θ) is the magnetic resistance, L m It's magnetic induction. They are the magnetic flux of the three-phase windings ABC respectively; The motor magnetic impedance model in the three-phase stationary coordinate system is subjected to Clark transformation and Park transformation to obtain the motor magnetic impedance model in the two-phase rotating coordinate system: Among them, F d ,F q They are the magnetomotive force components of the dq-axis armature winding, R dd is the d-axis magnetic resistance, R qq is the q-axis magnetic resistance, R dq is the magnetoresistance term corresponding to the inverse magnetomotive force term caused by the cross-coupling of the dq-axis flux linkage, They are dq axis flux, N is the number of turns of each phase winding of the motor, L dd is the armature d-axis self-inductance, L qq is the armature q-axis self-inductance, L dq is the mutual inductance between the d-axis and the q-axis, and ω is the motor current angular frequency.

3. The method according to claim 2, characterized in that: Calculate the armature winding magnetomotive force, including, The calculation formula of the armature winding magnetomotive force is: F d =In d F q =In q Among them, F d is the magnetomotive force component of the d-axis armature winding, F q is the magnetomotive force component of the q-axis armature winding, i d is the d-axis current, i q is the q-axis current.

4. The method according to claim 3, characterized in that: Calculate the permanent magnet magnetomotive force of the interpolated ferrite, including, The calculation formula of permanent magnet magnetomotive force is: Among them, F dψ is the magnetomotive force of the ferrite permanent magnet flux acting on the d-axis, F qψ is the magnetomotive force of the ferrite permanent magnet flux acting on the q axis, ψ f It is the permanent magnet flux linkage value corresponding to ferrite.

5. The method according to claim 4, characterized in that: Based on the magnetomotive force and the motor magnetic impedance model, the stator flux equation is obtained: include, The calculation formula of the stator flux equation is: Among them, ψ d is the d-axis flux, ψ q is the q-axis flux; k is the magnetic induction coefficient, which is related to the magnetic induction value L m Proportional to L Δ is the coupled equivalent inductance.

6. The method according to claim 5, characterized in that: Construct a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model, including: Among them, u d is the d-axis voltage, u q is the q-axis voltage, R s is the stator resistance, is the d-axis incremental inductance, is the q-axis incremental inductance, is the incremental inductance of the cross coupling between the d-axis and the q-axis; T e is the electromagnetic torque, N p is the number of motor pole pairs.

7. The method according to claim 6, characterized in that: Based on the magnetoelectric power law of vector magnetic circuit theory, the magnetic induction coefficient value in the motor magnetic impedance model is measured by the iron loss separation method, including: First, according to the magnetoelectric power law of vector magnetic circuit theory: Q ironloss =kU 2 Among them, U is the motor terminal voltage, P ironloss is the iron loss, k is the magnetic induction coefficient; Calculate the iron loss of the motor: P ironloss =P in -P Te -P Cu -P mech x=1.5[(u d -R s i d ) 2 +(u q -R s i q ) 2 ] y=P in -P Te -P Cu Among them, P in is the motor input power, P Te is the torque output power, P Cu is the copper loss, P mech is the mechanical loss; x is the horizontal axis of the coordinate system, and y is the vertical axis of the coordinate system; By changing the current and load torque of the motor's direct and quadrature axes, a series of data points can be obtained in the xy coordinate system. When the motor operates in the linear region of the magnetic field, these data points will form a straight line, the slope of which is the value of the magnetic induction coefficient k, and the intercept of the y-axis is the mechanical loss.

8. The method according to claim 7, characterized in that: A maximum torque current ratio control method is designed based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model, including: L dd =L dd (i d ,i q ) L dq =L dq (i d ,i q ) L qq =L qq (i d ,i q ) ψ f =ψ f (i d ,i q ) k=k(i d ,i q ) R s =R0[1+α(T-T0)] Among them, R s is the resistance at temperature T, R0 is the resistance at temperature T0, α is the temperature coefficient of resistance; T e is the electromagnetic torque, is the electromagnetic torque reference value, is the d-axis current reference value.

9. A permanent magnet assisted synchronous reluctance motor control system taking into account eddy current reaction, characterized in that: include, A magnetic impedance model calculation unit is configured to construct a motor magnetic impedance model taking into account eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect based on vector magnetic circuit theory; An armature winding magnetomotive force calculation unit, configured to calculate the armature winding magnetomotive force; a permanent magnet magnetomotive force calculation unit configured to calculate the permanent magnet magnetomotive force of the interpolated ferrite; A stator flux equation calculation unit is configured to obtain a stator flux equation based on the magnetomotive force and the motor magnetic impedance model; A motor control model building unit is configured to build a multi-factor coupled permanent magnet assisted synchronous reluctance motor control model based on the stator flux equation and the voltage equation; A magnetic induction coefficient value measuring unit is configured to measure the magnetic induction coefficient value in the motor magnetic impedance model by using the magnetoelectric power law based on the vector magnetic circuit theory and the iron loss separation method; and The maximum torque-to-current ratio control unit is configured to design a maximum torque-to-current ratio control method based on the multi-factor coupled permanent magnet assisted synchronous reluctance motor control model.

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