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

Abstract

The application discloses a kind of permanent magnet auxiliary synchronous reluctance motor control method and system considering eddy current reaction, method includes, based on vector magnetic circuit theory, construct the motor magnetic impedance model considering eddy current reaction effect, magnetic saturation effect and dq axis cross-coupling effect;Calculate armature winding magnetic motive force and permanent magnet magnetic motive force of interpolation ferrite;Based on magnetic motive force and the motor magnetic impedance model, obtain stator flux linkage equation;Based on the stator flux linkage equation and voltage equation, construct the permanent magnet auxiliary synchronous reluctance motor control model of multi-factor coupling;Based on vector magnetic circuit theory magnetic-electric power law, measure the magnetic induction coefficient value in motor magnetic impedance model;Based on the multi-factor coupling motor control model, design permanent magnet auxiliary synchronous reluctance motor maximum torque current ratio control method.The application quantitatively considers that eddy current in permanent magnet auxiliary synchronous reluctance motor reacts on stator flux linkage, with clear physical meaning and higher modeling accuracy, is favorable to the performance improvement of control system.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnetic circuit theory and motor driving system, and particularly relates to a control method and system of a permanent magnet auxiliary synchronous reluctance motor considering eddy current reaction. BACKGROUND

[0002] In recent years, the permanent magnet auxiliary synchronous reluctance motor has been increasingly concerned by the industry due to its advantages of high efficiency, high power factor and good dynamic performance, and has been widely used in electric power transmission, especially in high-performance electric power driving. In many medium-power application occasions, the permanent magnet auxiliary synchronous reluctance motor is gradually replacing the permanent magnet synchronous motor due to its performance advantages and cost advantages.

[0003] The mathematical model of the motor is the theoretical basis for motor control, and accurately establishing the mathematical model of the permanent magnet auxiliary synchronous reluctance motor is a necessary condition for realizing its high-performance control. The current establishment of the mathematical model of the permanent magnet auxiliary synchronous reluctance motor only considers the magnetic saturation effect and the cross-coupling effect, and it is difficult to consider the reaction of eddy current on the flux linkage. However, due to the characteristics of the reluctance motor and the insertion of ferrite in the stator core of the permanent magnet auxiliary synchronous reluctance motor, the eddy current phenomenon is stronger than that of other motors of the same power level, so the modeling considering the reaction of eddy current is of great significance.

[0004] The current model of the permanent magnet auxiliary synchronous reluctance motor mostly considers the magnetic saturation effect and the cross-coupling effect. Some scholars consider the iron loss by equivalent to a resistance connected in parallel to the motor back electromotive force and inductance, and derive the fitting method of the iron loss resistance. However, the physical meaning of such mathematical model is ambiguous, and a large amount of experimental data is needed to obtain a relatively accurate motor mathematical model within a certain operating condition range. Moreover, such motor model is usually only applicable to steady-state analysis. SUMMARY

[0005] The purpose of the present application is to provide a control method and system of a permanent magnet auxiliary synchronous reluctance motor considering eddy current reaction, which quantitatively considers the reaction of eddy current on the stator flux linkage, has clear physical meaning and higher modeling accuracy, and is beneficial to the performance improvement of the control system.

[0006] In order to achieve the above purpose, the solution of the present application is:

[0007] A control method of a permanent magnet auxiliary synchronous reluctance motor considering eddy current reaction, comprising,

[0008] constructing a motor reluctance impedance model considering the effects of eddy current reaction, magnetic saturation and dq-axis cross-coupling based on vector magnetic circuit theory;

[0009] The magnetic motive force of the armature winding and the permanent magnet interposed ferrite are calculated;

[0010] The stator flux linkage equation is obtained based on the magnetic motive force and the magnetic impedance model of the motor;

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

[0012] Based on the magnetic 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;

[0013] Based on the multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model, a maximum torque current ratio control method is designed.

[0014] Based on the vector magnetic circuit theory, a motor magnetic impedance model considering the eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect is constructed, 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] Wherein, F A ,F B ,F C are the magnetic motive forces of ABC three-phase windings, R(θ) is the magnetic resistance, L m is the magnetic induction, are the magnetic fluxes of ABC three-phase windings;

[0018] The motor magnetic impedance model in the three-phase stationary coordinate system is subjected to clark transformation and park transformation, and the motor magnetic impedance model in the two-phase rotating coordinate system is obtained:

[0019]

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

[0021] Wherein, the armature winding magnetic motive force is calculated, comprising,

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

[0023]

[0024] Wherein, F d is the d-axis armature winding magnetic motive force component, F q is the q-axis armature winding magnetic motive force component, i d is the d-axis current, i q is the q-axis current.

[0025] Wherein, the permanent magnet magnetic motive force of the interposed ferrite is calculated, comprising,

[0026] The calculation formula of the permanent magnet magnetic motive force is:

[0027]

[0028] Wherein, F dψ is the ferrite permanent magnet magnetic linkage acting on the d-axis magnetic motive force, F qψ is the ferrite permanent magnet magnetic linkage acting on the q-axis magnetic motive force, ψ f is the corresponding permanent magnet magnetic linkage value of the ferrite.

[0029] Wherein, the stator flux linkage equation is obtained based on the magnetic motive force and the motor magnetic impedance model, comprising,

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

[0031]

[0032] Wherein, ψ d is the d-axis flux linkage, ψ q is the q-axis flux linkage; k is the magnetic induction coefficient, which is proportional to the magnetic induction value L m ; L Δ is the coupling equivalent inductance.

[0033] Wherein, the permanent magnet auxiliary synchronous reluctance motor control model of multi-factor coupling is constructed, comprising,

[0034]

[0035] Wherein, 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 d-axis and q-axis cross-coupling incremental inductance; T e is the electromagnetic torque, N pis the pole pair number of the motor.

[0036] The magnetic induction coefficient value in the motor magnetic impedance model is measured by using the iron loss separation method based on the magneto-electric power law of vector magnetic circuit theory, and includes,

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

[0038] P ironloss = kU 2

[0039] Wherein, U is the terminal voltage of the motor, 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] Wherein, P in is the input power of the motor, 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, y is the vertical axis of the coordinate system;

[0045] Change the current and load torque of the motor on the direct axis and the cross axis, and obtain a series of data points in the x-y coordinate system; when the motor works in the linear region of the magnetic field, these data points will form a straight line, and 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.

[0046] The maximum torque current ratio control method is designed based on the multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model, and includes,

[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] wherein R s is the resistance at temperature T, R0 is the resistance at temperature T0, and 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 considering eddy current reaction, comprising,

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

[0057] An armature winding magnetic motive force calculation unit configured to calculate armature winding magnetic motive force;

[0058] A permanent magnet magnetic motive force calculation unit configured to calculate the permanent magnet magnetic motive force of the interpolation ferrite;

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

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

[0061] The magnetic induction coefficient value measuring unit is configured to measure the magnetic induction coefficient value in the motor magnetic impedance model by using the iron loss separation method based on the magneto-electric power law of the vector magnetic circuit theory.

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

[0063] After the above scheme is adopted, the beneficial effects of the present application are:

[0064] (1) The motor magnetic impedance model of the present application is established by taking into account the eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect, which is different from the traditional model. The magnetic induction parameter is used to quantitatively characterize the reaction of eddy current on the stator flux linkage. Compared with the traditional method of equivalent iron loss by connecting a resistance in parallel with the motor back electromotive force and inductance, the model of the present application has a clear physical meaning for the modeling of iron loss.

[0065] (2) The magnetic induction parameter introduced in the model of the present application can be measured by a clear scheme, and the influence of magnetic saturation on magnetic induction can be considered. After the value is measured at a rated or specific frequency, the magnetic induction coefficient value at other frequencies can be calculated by using the skin effect of magnetic flux. Compared with the traditional modeling method which needs a large number of experiments and data fitting, the modeling method of the present application has stronger practicability because it only needs to perform one measurement experiment.

[0066] (3) The model of the present application can calculate the iron loss caused by the current ripple on the switching sub-harmonic. Compared with the traditional method of calculating the iron loss by using the voltage ripple by ignoring the copper loss resistance voltage drop, the model based on the vector magnetic circuit theory has higher accuracy and realizability. BRIEF DESCRIPTION OF DRAWINGS

[0067] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0068] Figure 1 is a step diagram of the modeling method and control system of the permanent magnet auxiliary synchronous reluctance motor of the present application considering the eddy current reaction effect;

[0069] Figure 2 is an equivalent circuit diagram considering only the cross coupling effect and magnetic saturation effect;

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

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

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

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

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

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

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

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

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

[0079] Figure 8 is the curve diagram of measuring magnetic induction coefficient by energy conservation at given frequency;

[0080] Figure 9 is the parameter value diagram of inductance and permanent magnet flux linkage of permanent magnet assisted synchronous reluctance motor under different working conditions according to finite element software simulation;

[0081] wherein (a) is the diagram of L dd under different working conditions, (b) is the diagram of L qq under different working conditions, (c) is the diagram of L dq under different working conditions, (d) is the diagram of ψ f under different working conditions;

[0082] Figure 10 is the comparison diagram of maximum torque current ratio operating point of permanent magnet assisted synchronous reluctance motor prototype under different load torque conditions based on DSP controller using traditional cross coupling model, the model considering eddy current reaction proposed in the application and traversal search method;

[0083] Wherein, the circular point is the calculation result of the traversal search method, the square point is the calculation result of the traditional cross-coupling model, and the triangular point is the calculation result of the model considering the eddy current reaction; (a) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under six different load torque conditions, (b) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 0.5 N·m, (c) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 1.0 N·m, (d) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 1.5 N·m, (e) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 2.0 N·m, (f) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 2.5 N·m, and (g) is a comparison diagram of the maximum torque current ratio working points obtained by the three methods under the condition that the load torque is 3.0 N·m. DETAILED DESCRIPTION

[0084] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0085] The flux linkage equation of the conventional three-phase permanent magnet auxiliary synchronous reluctance motor considering only the dq-axis cross-coupling effect in the rotating coordinate system can be written as:

[0086]

[0087] Wherein, ψ d is the d-axis flux linkage, ψ q is the q-axis flux linkage, 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 is the permanent magnet flux linkage value corresponding to the ferrite.

[0088] The following mathematical model can be obtained by substituting the voltage equation:

[0089]

[0090] Wherein, 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 d-q axis cross-coupling incremental inductance. The traditional model only considers the magnetic saturation effect and the dq axis cross-coupling effect, without considering the eddy current back-EMF, whose equivalent circuit is shown in Figure 2 .

[0091] To calculate the eddy current loss, some models add a parallel iron loss resistance to the back-EMF and inductance, whose equivalent circuit is shown in Figure 3 . Where R c is the iron loss resistance, and the active loss on the resistance is equal to the iron loss power. E d and E q are the d-axis and q-axis back-EMF, respectively, which satisfy:

[0092]

[0093] Since the voltage equation is a very complex multi-variable 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, only the steady-state condition can be considered.

[0094] In order to simplify the model, the modeling method of permanent magnet assisted synchronous reluctance motor based on vector magnetic circuit theory is made as follows:

[0095] (1) Ignore the spatial harmonics, assume that the three-phase winding is symmetrical, and the magnetic motive force generated by the three-phase winding is sinusoidal along the air gap at a spatial mutual difference of electrical angle;

[0096] (2) Ignore the hysteresis loss;

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

[0098] (4) Assume that the inductance, permanent magnet flux linkage and other parameters do not change with temperature;

[0099] As shown in Figure 1 , the modeling method of permanent magnet assisted synchronous reluctance motor considering the eddy current back-EMF effect includes the following steps:

[0100] S1, considering the motor magnetic impedance model of eddy current back-EMF effect, magnetic saturation effect and dq axis cross-coupling effect, the magnetic induction parameter in the vector magnetic circuit theory is used to quantitatively characterize the eddy current back-EMF effect on the flux linkage.

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

[0102]

[0103] Where, F A , FB ,F C These are the magnetomotive forces of the three-phase windings A, B, and C, respectively, where R(θ) is the magnetic reluctance and L is the magnetic flux density. m It's magnetic induction. These are the magnetic fluxes of the three-phase windings A, B, and C; through Clark and Park transformations, the motor magnetoresistance model in a two-phase rotating coordinate system can be obtained as follows:

[0104]

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

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

[0107]

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

[0109] S3, calculate the permanent magnetomotive force of the interpolated ferrite; the formula for calculating the permanent magnetomotive force is:

[0110]

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

[0112] S4, deriving the stator flux linkage equation based on the magnetomotive force and magnetic impedance model; combining steps S1, S2 and S3, and using the superposition theorem, the calculation formula of the stator flux linkage equation is obtained as follows:

[0113]

[0114] wherein ψ d is the d-axis flux linkage, ψ q is the q-axis flux linkage; k is the magnetic induction coefficient, which is proportional to the magnetic induction value L m ; L Δ is the coupling equivalent inductance.

[0115] S5, deriving the motor control model with multiple factors coupling based on the voltage equation and the stator flux linkage equation; the mathematical model of the motor is as follows:

[0116]

[0117] wherein 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 shown in Figure 5 . Due to the influence of magnetic saturation, the incremental inductance value under the same working condition is often less than the apparent inductance. For convenience, the inductance value without superscript is uniformly regarded as the apparent inductance, which is referred to as "inductance" in the present application. The equivalent circuit of the permanent magnet auxiliary synchronous reluctance motor based on the vector magnetic circuit theory is shown in Figure 6 . As can be seen from Figure 6 , the d-axis and q-axis circuits are additionally introduced with new coupling potentials, which is obviously different from the equivalent circuits shown in Figure 2 and Figure 3 . Since the iron loss expression is as follows:

[0118]

[0119] According to the energy conservation, the power of the electromagnetic torque is obtained as follows:

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

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

[0122]

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

[0124] S6, based on the magnetoelectric power law of vector magnetic circuit theory, uses the iron loss separation method to measure the magnetic flux density value in the magnetoresistance model; the magnetic flux density value measurement scheme is as follows:

[0125] According to the law of conservation of energy:

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

[0127] Among them, P mech This refers to mechanical losses, which are related to rotational speed. We can assume that when the rotational speed remains constant, the mechanical losses are also constant. Let:

[0128]

[0129] Changing the current and load torque along the direct and quadrature axes of the motor will yield a series of data points in the xy-coordinate system. Here, x is the horizontal axis and y is the vertical axis. When the motor operates in the linear region of the magnetic field, these data points will form a straight line, the slope of which represents the magnetic flux density k, and the y-intercept represents mechanical losses. When the motor operates in the magnetic field saturation region, the change in magnetic flux density can be analyzed according to the definition of magnetic flux density:

[0130]

[0131] Where Γ is the charge chain passing through the cross-section of the conductor per unit time, N is the number of turns, and Q is the amount of charge passing through the cross-section of the conductor per unit time. It's magnetic flux. As magnetic saturation increases, As the value of x decreases, the magnetic flux density decreases. Therefore, the set of scattered points in the magnetic saturation region forms a convex function curve, and the slope of the curve can be approximated as the value of the magnetic flux density k under this operating condition. Since the q-axis current of the permanent magnet assisted synchronous reluctance motor is more significantly affected by magnetic saturation, as x increases, the q-axis current increases, the degree of magnetic saturation is higher, the value of the magnetic flux density k is smaller, and the slope is smaller.

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

[0133]

[0134] Where 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 at different frequencies is inversely proportional to the arithmetic square root of the frequency.

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

[0136] Because of the existence of magnetic saturation in electromagnetism, the parameters such as magnetic induction coefficient, inductance, and flux linkage have strong correlation with working conditions, that is, satisfy:

[0137]

[0138] The resistance is mainly determined by the temperature, which satisfies:

[0139] R s = R0 [1 + α (T - T0)] (18)

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

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

[0142]

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

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

[0145] The application also provides a permanent magnet auxiliary synchronous reluctance motor control system considering eddy current reaction, comprising,

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

[0147] An armature winding magnetic motive force calculation unit configured to calculate an armature winding magnetic motive force;

[0148] A permanent magnet magnetic motive force calculation unit configured to calculate a permanent magnet magnetic motive force of the interposed ferrite;

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

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

[0151] A permeance value measurement unit configured to measure a permeance value in the magnetic impedance model by using a core loss separation method based on a vector magnetic circuit theory magnetic-electric power law; and

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

[0153] In the present application, the permanent magnet auxiliary synchronous reluctance motor model considering the eddy current counteraction effect, the magnetic saturation effect and the dq axis cross-coupling effect is applied to an embodiment of the model-based motor control algorithm, and the effect of the model proposed in the present application for maximum torque current ratio control is then demonstrated. Figure 7 The control system flow chart is shown in the figure, including: 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 auxiliary 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 current ratio algorithm generally needs to know the motor parameters in advance. The inductance and the permanent magnet flux linkage value corresponding to the ferrite can be obtained by finite element software simulation, and the value of the permeance k needs to be measured by experiment. In the experiment, the parameters of the permanent magnet motor are as follows: the pole pair number 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 the scatter plot between y and x can be obtained, and the curve is fitted according to the point set, and the slope is the value of k, as shown in the figure. Figure 8 The expression of k is:

[0155]

[0156] When x<1500, the magnetic saturation degree is low, the motor operating point is in the linear region, and the magnetic induction value is constant. When x>1500, the magnetic saturation degree increases, the motor operating point is in the nonlinear region, and the magnetic induction value gradually decreases. The inductance and permanent magnet flux linkage simulated by the finite element software at different operating points are shown in Table 1. Figure 9

[0157] Combined with equations (17), (18) and (19), the d-axis current reference value at the maximum torque current ratio operating point can be solved. Since the equation is transcendental 5 times, there is no analytical solution, and Newton iteration method is needed to converge to a numerical solution.

[0158] The experimental verification results of the maximum torque current ratio operating point are shown in FIG. 6. Figure 10 Figure 10 FIG. 6 is a comparison of the maximum torque current ratio operating points of the permanent magnet auxiliary synchronous reluctance motor prototype under different load torques, which are obtained by using the traditional model based on the DSP controller, the model based on the vector magnetic circuit theory proposed in the present application, and the exhaustive search method. The load torques are selected as 0.5 N·m, 1.0 N·m, 1.5 N·m, 2.0 N·m, 2.5 N·m and 3.0 N·m. The circular icons are the maximum torque current ratio operating points obtained by the exhaustive search, which are theoretically accurate values. The triangular icons are the maximum torque current ratio operating points calculated by the model proposed in the present application, and the square icons are the maximum torque current ratio operating points calculated by the traditional model. It can be seen that the calculation accuracy of the maximum torque current ratio operating point by the model proposed in the present application is better than that of the traditional model.

[0159] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do 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 basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.​​

Claims

1. A control method of a permanent magnet assisted synchronous reluctance machine taking into account the eddy current reaction, characterized in that: The method comprises the following steps: a motor magnetic impedance model considering eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect is constructed based on vector magnetic circuit theory; magnetic motive force of the armature winding is calculated, including the calculation formula of the magnetic motive force of the armature winding is: magnetic motive force of the permanent magnet inserted into the ferrite is calculated, including the calculation formula of the magnetic motive force of the permanent magnet is: a stator flux linkage equation is obtained based on the magnetic motive force and the motor magnetic impedance model, 2. The method of claim 1, wherein: including the calculation formula of the obtained stator flux linkage equation is: where F A , F B , F C are the magnetic motive forces of the ABC three-phase windings, R(θ) is the reluctance, L m is the magnetic inductance, are the magnetic fluxes of the ABC three-phase windings; a multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model is constructed, including where F d , F q are the dq-axis armature winding magnet-motive force components, R dd is the d-axis reluctance, R qq is the q-axis reluctance, R dq is the reluctance term corresponding to the anti-magnet-motive force term caused by the cross-coupling of the dq-axis flux linkages, are the dq-axis fluxes, N is the number of turns per 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 q-axis, and ω is the motor current angular frequency.

3. The method of claim 2, wherein: a magnetic induction coefficient value in the motor magnetic impedance model is measured based on the magnetic-electric power law of vector magnetic circuit theory by using the iron loss separation method, including firstly, the magnetic-electric power law of vector magnetic circuit theory is used: F d = Ni d F q = Ni q where F d is the d-axis armature winding magnet-motive force component, F q is the q-axis armature winding magnet-motive force component, i d is the d-axis current, i q is the q-axis current.

4. The method of claim 3, wherein: the iron loss of the motor is calculated: a series of data points are obtained in the x-y coordinate system by changing the current and load torque of the direct axis and the quadrature axis of the motor; when the motor works in the magnetic field linear region, the 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. Wherein, F dψ is the magnetomotive force of the ferrite permanent magnet flux linkage on the d-axis, F qψ is the magnetomotive force of the ferrite permanent magnet flux linkage on the q-axis, ψ f is the corresponding permanent magnet flux linkage value of the ferrite.

5. The method of claim 4, wherein: a maximum torque current ratio control method is designed based on the multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model, including including a motor magnetic impedance model calculation unit is configured to construct a motor magnetic impedance model considering eddy current reaction effect, magnetic saturation effect and dq axis cross coupling effect based on vector magnetic circuit theory; where ψ d is the d-axis flux linkage, ψ q is the q-axis flux linkage; k is the magnetic inductance proportional to the magnetic inductance value L m L Δ is the coupling equivalent inductance.

6. The method of claim 5, wherein: an armature winding magnetic motive force calculation unit is configured to calculate armature winding magnetic motive force; where 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 d-axis and q-axis cross-coupled incremental inductance; T e is the electromagnetic torque, N p is the number of motor pole pairs.

7. The method of claim 6, wherein: a permanent magnet magnetic motive force calculation unit is configured to calculate permanent magnet magnetic motive force of the permanent magnet inserted into the ferrite; a stator flux linkage equation calculation unit is configured to obtain a stator flux linkage equation based on magnetic motive force and the motor magnetic impedance model; P ironloss = kU 2 where U is the motor terminal voltage, P ironloss is the iron loss, k is the magnetic induction coefficient; a motor control model construction unit is configured to construct a multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model based on the stator flux linkage equation and a voltage equation; 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 where 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. a magnetic induction coefficient value measurement unit is configured to measure a magnetic induction coefficient value in the motor magnetic impedance model based on the magnetic-electric power law of vector magnetic circuit theory by using the iron loss separation method; and 8. The method of claim 7, wherein: a maximum torque current ratio control unit is configured to design a maximum torque current ratio control method based on the multi-factor coupled permanent magnet auxiliary synchronous reluctance motor control model. 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 + a(T - T0)] wherein R s is the resistance at temperature T, R0 is the resistance at temperature T0, and a is the resistance temperature coefficient; T e is the electromagnetic torque, is the electromagnetic torque reference value, is the d-axis current reference value.

9. A control system for a permanent magnet assisted synchronous reluctance motor that takes into account eddy current reaction, characterized in that: ​ ​ ​ ​ ​ ​ ​ ​

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