CN112468032B - Full-speed domain efficiency MAP graph generation method of permanent magnet synchronous motor - Google Patents

Full-speed domain efficiency MAP graph generation method of permanent magnet synchronous motor Download PDF

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CN112468032B
CN112468032B CN202011519753.5A CN202011519753A CN112468032B CN 112468032 B CN112468032 B CN 112468032B CN 202011519753 A CN202011519753 A CN 202011519753A CN 112468032 B CN112468032 B CN 112468032B
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CN112468032A (en
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郑萍
乔光远
尹佐生
杨士杰
陈闯
梁晓宇
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Harbin Institute of Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/34—Modelling or simulation for control purposes
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/0003—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control
    • H02P21/0014—Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control using neural networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/0085—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation specially adapted for high speeds, e.g. above nominal speed
    • H02P21/0089—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation specially adapted for high speeds, e.g. above nominal speed using field weakening
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/141—Flux estimation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
    • H02P21/20—Estimation of torque
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
    • H02P21/22—Current control, e.g. using a current control loop
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/022—Synchronous motors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
    • H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation

Abstract

The invention discloses a method for generating a full-speed domain efficiency MAP (MAP) of a permanent magnet synchronous motor, belongs to the field of motors, and aims to solve the problems that the calculation of the traditional motor efficiency MAP needs to be repeated for multiple times through finite element simulation or test, the calculation amount is large, and the calculation time is long. The method comprises the following steps: the method comprises the steps that firstly, current tracks of a plurality of working points of a motor in a full-speed domain range are obtained by a full-speed domain efficiency optimal control current track searching method; step two, calculating the copper loss of the corresponding working point according to the current track of the step one; thirdly, calculating the iron loss of the motor under corresponding working conditions by using a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation; and step four, generating a full-speed domain efficiency MAP according to the copper loss in the step two and the iron loss in the step three.

Description

Full-speed domain efficiency MAP graph generation method of permanent magnet synchronous motor
Technical Field
The invention relates to a method for quickly calculating a full-speed domain efficiency MAP (MAP of permanent magnet synchronous) motor, belonging to the field of motors.
Background
In recent years, the traditional automobile has a great amount of conservation, the problem of environmental pollution is becoming more serious, and the environmental pollution becomes one of the important factors for increasing the global warming and the greenhouse effect. Meanwhile, the traditional automobile uses an internal combustion engine, the energy conversion rate is low, the internal combustion engine is very dependent on non-renewable resources such as petroleum, and the dual pressure of environmental pollution and energy crisis prompts the traditional automobile industry to gradually develop towards new energy automobiles. The rare earth permanent magnet synchronous motor has the advantages of high power factor, high power density, high efficiency, high reliability and the like, and is widely applied to the fields of electric automobiles, rail transit, household appliances, aerospace, national defense industry and the like. The rare earth permanent magnet motor can be divided into a surface-mounted permanent magnet synchronous motor and a built-in permanent magnet synchronous motor according to different rotor structures, wherein the built-in permanent magnet synchronous motor has different alternating-axis and direct-axis inductances, and additional reluctance torque can be generated by utilizing the asymmetry of the inductances, so that the torque output capability of the motor is improved.
The motor efficiency MAP is a key index for testing the performance of the motor and is used for reflecting the efficiency distribution condition of the motor under different rotating speeds and torques, the motor efficiency MAP can not only reflect the performance of the motor, but also provide guidance for the formulation of the operation control strategy of the motor, and the motor generally works in an efficient operation interval as much as possible. However, the calculation of the motor efficiency MAP generally requires a finite element simulation or a test which is repeated for many times, and the calculation amount is large and the calculation time is long. Taking a finite element calculation motor efficiency MAP as an example, the process of determining the current track by the traditional calculation mode is complex, the current working points are required to be brought into finite element simulation after the current track is determined to calculate the iron loss of the corresponding working points, and then the efficiency of the motor at the corresponding working points is calculated, the calculation process is complex, the calculation amount is large, and the calculation time is long.
Disclosure of Invention
The invention aims to solve the problems that the calculation of the traditional motor efficiency MAP needs to be carried out through repeated finite element simulation or test, the calculation amount is large, and the calculation time is long, and provides a method for generating the full-speed domain efficiency MAP of a permanent magnet synchronous motor. The method only needs to carry out a small amount of finite element simulation or test work when the nonlinear load flux linkage model of the motor is established in the previous period, and does not need to carry out the finite element simulation or test in the implementation process of the efficiency MAP calculation method, so that the method is simple in calculation, small in calculation amount and high in calculation speed.
The invention discloses a method for generating a full-speed domain efficiency MAP of a permanent magnet synchronous motor, which comprises the following steps:
the method comprises the steps that firstly, current tracks of a plurality of working points of a motor in a full-speed domain range are obtained by a full-speed domain efficiency optimal control current track searching method;
step two, calculating the copper loss of the corresponding working point according to the current track of the step one;
thirdly, calculating the iron loss of the motor under corresponding working conditions by using a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation;
and step four, generating a full-speed domain efficiency MAP according to the copper loss in the step two and the iron loss in the step three.
Preferably, in the first step, the method for searching the full-speed-domain efficiency-optimized control current trajectory includes: when the motor runs below a basic speed value, under the given torque instruction, rotating speed instruction, voltage limit and current limit, acquiring a current working point with the minimum current amplitude as a current track by adopting an MTPA control mode; when the motor operates above a basic speed value, under the given torque instruction, rotating speed instruction, voltage limit and current limit, acquiring a current working point with the minimum current amplitude as a current track by adopting an optimal efficiency control mode of a weak magnetic area;
the process of acquiring the current working point with the minimum current amplitude by adopting an MTPA control mode comprises a current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude; nesting a current amplitude iteration loop step in the current angle iteration process to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting an MTPA current track;
the process of obtaining the current working point with the minimum current amplitude by adopting the flux weakening area efficiency optimal control mode comprises a flux weakening current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude under the voltage limit; and in the current angle iteration process, nesting a current amplitude iteration loop step to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting the current track with the optimal efficiency control in the weak magnetic region.
Preferably, the process of obtaining the current working point with the minimum current amplitude by adopting the MTPA control mode includes a current angle iteration loop step and a current amplitude iteration loop step:
the current angle iterative loop step comprises:
a1, initial current angle range [ a ]1,b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
A2, judging the current amplitude target function value I (lambda) at the probe point of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk) And the iteration times k of the current angle is 1,2 and 3.
If yes, go to step A3; judging whether to execute the step A5;
current magnitude objective function value I (λ)k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
a3, order ak+1＝λk，bk+1＝bk，λk+1＝βk，βk+1＝ak+1+0.618(bk+1-ak+1)，
A4, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step a7 is performed;
a5, order ak+1＝ak，bk+1＝βk，βk+1＝λk，λk+1＝ak+1+0.382(bk+1-ak+1)，
A6, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step a7 is performed;
a7, let k be k + 1;
a8, judging whether the iteration converges: if b isk-ak＜L1Execute byStep A9; otherwise, return to step A2;
wherein L is1Iteration precision is the current angle;
a9, judging whether the current operating point meets the requirements of current limit and voltage limit at the same time: if I (λ)k)≤Ilim&U(λk)≤Ulim，IlimFor a given current limit value, UlimOutputting the MTPA current track for a given voltage limit value; otherwise, inputting the torque and rotating speed commands again, and returning to execute the step A1;
the current traces are: current amplitude I ═ I (λ)k) D, the current angle theta is lambdak；
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And calculating the initial value mu of the current amplitude probing point1、v1：
μ1＝c1+0.382(d1-c1)、v1＝c1+0.618(d1-c1)；
B2, calculating a torque error objective function value at the two current amplitude probing points: f (. mu.) (1)、f(v1)，
Torque error objective function f (I)
Figure GDA0003443575650000031
Obtaining, wherein:
Figure GDA0003443575650000032
for a given torque, Te(I, theta) is torque corresponding to current angle theta, Te(I, theta) is obtained by calculation according to a motor nonlinear load quadrature-direct axis flux linkage model; the current angle theta is a current angle probing point lambda output by current angle iterative cyclek、βk(ii) a I is the current amplitude;
b3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) The number of current amplitude iterations h is 1,2,3 …
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dh，μh+1＝vh，vh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝νh，νh+1＝μh，μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwise, returning to the step B3; wherein L is2And the current amplitude iteration precision is obtained.
Preferably, the process of obtaining the current working point with the minimum current amplitude by adopting the weak magnetic region efficiency optimal control mode comprises a weak magnetic current angle iteration circulation step and a current amplitude iteration circulation step:
the weak magnetic current angle iteration loop step comprises:
c1, initial current angle interval [ a1,b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
C2, judging load voltage target function value U (beta)k) And voltage limit value UlimIf U (β) is large or smallk)＞UlimStep C6 is executed; otherwise, go to step C3;
load voltage objective function value U (β)k) Obtaining by calling a current amplitude iteration loop, wherein the current angle iteration number k is 1,2,3 …;
c3, judging the current amplitude target function value I (lambda) at the probing points of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk)，
If yes, go to step C4; if not, executing the step C6;
current magnitude objective function value I (λ)k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
c4, order ak+1＝λk，bk+1＝bk，λk+1＝βk，βk+1＝ak+1+0.618(bk+1-ak+1)，
C5, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step C8 is performed;
c6, order ak+1＝ak，bk+1＝βk，βk+1＝λk，λk+1＝ak+1+0.382(bk+1-ak+1)，
C7, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step C8 is performed;
c8, let k be k + 1;
c9, judging whether the iteration converges: if b isk-ak＜L1Step C10 is executed; otherwise, returning to step C2;
wherein L is1Iteration precision is the current angle;
c10, judging whether the current working point meets the requirement of the current limit at the same time: if I (λ)k)≤Ilim，IlimOutputting a current track with optimal efficiency control in a weak magnetic area for a given current limit value; otherwise, the torque and rotating speed commands are input again, and the step C1 is executed again;
the current traces are: current amplitude I ═ I (λ)k) D, the current angle theta is lambdak；
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And calculating the initial value mu of the current amplitude probing point1、ν1：
μ1＝c1+0.382(d1-c1)、v1＝c1+0.618(d1-c1)；
B2, calculating a torque error objective function value at the two current amplitude probing points: f (v)1)、f(ν1)，
Torque error objective function f (I)
Figure GDA0003443575650000051
Obtaining, wherein:
Figure GDA0003443575650000052
for a given torque, Te(I, theta) is torque corresponding to current angle theta, Te(I, theta) is obtained by calculation according to a motor nonlinear load quadrature-direct axis flux linkage model; the current angle theta is a current angle probing point lambda output by current angle iterative cyclek、βk(ii) a I is the current amplitude;
b3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) The number of current amplitude iterations h is 1,2,3 …
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dh，μh+1＝νh，νh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝vh，νh+1＝μh，μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwise, returning to the step B3; wherein L is2And the current amplitude iteration precision is obtained.
Preferably, the establishment process of the motor nonlinear load quadrature-direct axis flux linkage model comprises the following steps:
selecting a series of current working points at equal intervals or at unequal intervals within the current limit range of the motor, wherein the current working points comprise an equal-interval or unequal-interval current amplitude series value and an equal-interval or unequal-interval current angle series value, the interval of the selected current working points is determined by the saturation degree of the motor, the magnetic permeability of an iron core between two adjacent current working points needs to be ensured to be kept unchanged, and the iron core is processed according to linear materials;
calculating motor load alternate and direct axis flux linkage data corresponding to the selected current working point by adopting a simulation or experiment mode, and interpolating the obtained load alternate and direct axis flux linkage data to obtain load alternate and direct axis flux linkage models of all current working points in a current limit range, namely a nonlinear flux linkage model of the permanent magnet synchronous motor:
ψd(I,θ)＝ψd(id,iq)
ψq(I,θ)＝ψq(id,iq)。
preferably, the torque TeAnd (I, theta) is calculated and output by a motor nonlinear load quadrature-direct axis flux linkage model, and is obtained according to the following formula:
Te(I,θ)＝p(ψd(I,θ)iq-ψq(I,θ)id)
wherein p is the number of pole pairs of the motor, idIs the direct axis current of the motor iqIs the quadrature axis current of the motor,. psidIs a direct axis flux linkage of the motorqIs the quadrature axis flux linkage of the motor.
Preferably, the voltage amplitude U (θ) is obtained as follows:
Figure GDA0003443575650000061
wherein the direct axis voltage
Figure GDA0003443575650000062
Quadrature axis voltage
Figure GDA0003443575650000063
w is the electrical angular velocity of the motor, R1Is the motor resistance.
Preferably, the process of calculating the iron loss of the motor under the corresponding working condition by using the nonlinear load flux linkage model and the simplified iron loss calculation model based on the improved Steinmetz equation in the third step is as follows:
simplified iron loss calculation model of motor at any working point according to improved Steinmetz equation
Figure GDA0003443575650000064
Obtaining;
wherein, g1(U) is the loss in the open circuit state,
Figure GDA0003443575650000065
loss for short circuit condition:
Figure GDA0003443575650000066
Figure GDA0003443575650000067
in the formula, ahIs an open-circuit equivalent hysteresis loss coefficient, bhFor short-circuit equivalent hysteresis loss coefficient, aeEquivalent eddy current loss for open circuitCoefficient, beIs the short circuit equivalent eddy current loss coefficient;
ψmis a no-load flux linkage idMotor direct axis flux linkage psi when 0d，ψm＝ψd(0,iq)；
Figure GDA0003443575650000068
For the d-axis armature reaction pressure drop,
Figure GDA0003443575650000069
ψmand psid(id,iq) And obtaining according to the nonlinear load flux linkage model.
The invention has the beneficial effects that:
(1) the method can quickly and accurately give the efficiency MAP of the motor in the control modes of MTPA control, flux weakening control, maximum output power control and the like. In the calculation process of the efficiency MAP, only a small amount of finite element simulation or test work is needed to be carried out for establishing the nonlinear load flux linkage model of the motor, and the finite element simulation or test is not needed to be carried out in the calculation process of the other efficiency MAP, so that the calculation is simple, the calculation amount is small, and the calculation speed is high.
(2) The method comprises two parts, namely an efficiency optimal control current track searching method of a constant torque area and an efficiency optimal control current track searching method of a weak magnetic area, wherein each searching method has two iteration loops: flux weakening current angle iteration and current amplitude iteration. By utilizing the load flux linkage model of the motor, the iterative convergence speed of the search process is high, the calculated amount is small, the optimal control of the full-speed domain efficiency of the permanent magnet synchronous motor can be quickly and accurately realized, and the running performance of the motor is improved.
(3) The load flux linkage model fully considers the nonlinearity of the motor, fully considers the influence rule of nonlinear factors such as iron core saturation and the like on the motor model under different magnetization states and different load conditions, can accurately simulate the nonlinear characteristics of the motor under different magnetization states and different load conditions, does not need to calculate parameters such as inductance and permanent magnet flux linkage, and can accurately calculate the torque, the load voltage and the like of the motor.
(4) The simplified iron loss calculation model based on the improved Steinmetz equation is provided, and the iron loss of the motor under the corresponding working condition can be quickly and accurately calculated by utilizing the nonlinear load flux linkage model and the simplified iron loss calculation model based on the improved Steinmetz equation according to the current track obtained by a searching method without finite element simulation.
The invention is not only applicable to the conventional permanent magnet synchronous motor, but also applicable to a novel permanent magnet synchronous motor, such as an adjustable flux permanent magnet synchronous motor, and the like, the structure of the adjustable flux permanent magnet synchronous motor is similar to that of the conventional permanent magnet synchronous motor, and the magnetization state of the motor can be correspondingly adjusted by applying charging and demagnetizing currents in an armature winding due to the adoption of the low-coercive-force permanent magnet, so that the motor can operate in a plurality of magnetization states, but the operation principle of the motor in each magnetization state is consistent with that of the conventional permanent magnet synchronous motor, and the invention is also applicable to the novel permanent magnet synchronous motor.
Drawings
FIG. 1 is a flow chart of a method for generating a full speed domain efficiency MAP for a PMSM according to the present invention;
FIG. 2 is an efficiency MAP chart obtained by using the method for generating a full-speed-domain efficiency MAP for a PMSM according to the present invention, where the PMSM employs an optimal control mode for full-speed-domain efficiency;
FIG. 3 is a flow chart of a current trajectory searching method for optimally controlling a constant torque zone in a full speed domain based on a double golden section iteration method;
FIG. 4 is a flow chart of a full-speed domain efficiency optimal control weak magnetic area current track searching method based on a double golden section iteration method;
fig. 5 is a load flux linkage model after saturation demagnetization of the series-parallel adjustable flux permanent magnet synchronous motor, wherein (a) of fig. 5 is a load direct-axis flux linkage model, and (b) of fig. 5 is a load quadrature-axis flux linkage model.
Detailed Description
The invention discloses a fast calculation method of a full-speed domain efficiency MAP (MAP of the permanent magnet synchronous motor), which can quickly and accurately give an efficiency MAP of the motor in control modes such as MTPA (maximum magnetic power amplifier) control, flux weakening control, maximum output power control and the like. The calculation method comprises the steps of firstly obtaining a current track of a motor through a full-speed domain efficiency optimal control current track searching method based on a double-golden section iteration method, calculating output torque and load voltage of the motor by utilizing a nonlinear load flux linkage model of the permanent magnet synchronous motor, calculating motor iron loss under corresponding working conditions by utilizing the nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation, and quickly and accurately calculating power, copper loss, iron loss and the like of the motor without finite element simulation so as to realize quick and accurate calculation of motor efficiency.
The first embodiment is as follows: the present embodiment is described below with reference to fig. 1 to 5, and the method for generating a full-speed-domain efficiency MAP of a permanent magnet synchronous motor according to the present embodiment includes the following steps:
the method comprises the steps that firstly, current tracks of a plurality of working points of a motor in a full-speed domain range are obtained by a full-speed domain efficiency optimal control current track searching method;
in this step, the current trajectory of a series of multiple working points is obtained by using the full-speed domain efficiency optimal control current trajectory searching method shown in fig. 3 and 4: current amplitude I ═ I (λ)k) D, the current angle theta is lambdak；
Step two, calculating the copper loss of the corresponding working point according to the current track of the step one;
and calculating the copper loss after acquiring the current amplitude of each working point.
Thirdly, calculating the iron loss of the motor under corresponding working conditions by using a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation;
and step four, generating a full-speed domain efficiency MAP according to the copper loss in the step two and the iron loss in the step three.
The method for searching the current track for optimal control of the full-speed domain efficiency in the first step is based on the idea of golden section, and can obtain the current working point with the minimum current amplitude under the given torque instruction, rotating speed instruction and motor magnetization state, so as to realize optimal control of the full-speed domain efficiency. In order to realize the optimal efficiency of a full-speed domain, the MTPA control mode acquires a current working point with the minimum current amplitude as a current track when the motor operates below a basic speed value and is in a constant rotating speed region, and the motor operates above the basic speed value and is in a weak magnetic region; when the motor operates above a basic speed value, acquiring a current working point with the minimum current amplitude as a current track by adopting a weak magnetic area efficiency optimal control mode; the nonlinearity of the inductance and the permanent magnet flux linkage is considered, the current amplitude is difficult to directly obtain through a torque formula, so that the current amplitude iteration is nested in the current angle (weak magnetic current angle) iteration process, a motor nonlinear load quadrature-direct axis flux linkage model is used for calculating the torque in the current amplitude iteration process, the influence of the nonlinearity of the inductance and the permanent magnet flux linkage is considered, and the calculation result is accurate. The nonlinear load flux linkage model can accurately calculate the motor torque, the load voltage and the like, does not need to calculate parameters such as inductance, permanent magnet flux linkage and the like, has small calculated amount and high calculating speed, can accurately simulate the change rule of the iron core saturation degree of the permanent magnet synchronous motor under different magnetization states and different load conditions, and realizes accurate modeling of the motor.
The method for searching the current track with optimal efficiency control in the full-speed domain comprises the steps that when a motor runs below a basic speed value, a current working point with the minimum current amplitude is obtained as a current track in an MTPA control mode under a given torque instruction, a given rotating speed instruction, a given voltage limit and a given current limit; when the motor operates above a basic speed value, under the given torque instruction, rotating speed instruction, voltage limit and current limit, acquiring a current working point with the minimum current amplitude as a current track by adopting an optimal efficiency control mode of a weak magnetic area;
the process of acquiring the current working point with the minimum current amplitude by adopting an MTPA control mode comprises a current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude; nesting a current amplitude iteration loop step in the current angle iteration process to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting an MTPA current track;
the process of obtaining the current working point with the minimum current amplitude by adopting the flux weakening area efficiency optimal control mode comprises a flux weakening current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude under the voltage limit; and in the current angle iteration process, nesting a current amplitude iteration loop step to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting the current track with the optimal efficiency control in the weak magnetic region.
Firstly, establishing a motor nonlinear load quadrature-direct axis flux linkage model:
aiming at the characteristics that the saturation degree of an iron core of a permanent magnet synchronous motor is obviously changed under different magnetization states and different loads, and the parameter change of the motor is obvious, firstly, a nonlinear flux linkage model is provided and established to simulate the nonlinear characteristics of the motor under different magnetization states and different loads.
A series of current working points are selected at equal intervals or at unequal intervals within the current limit range of the motor, for example, the current amplitude is selected to be (0, 2, 4, …), the current angle is selected to be (0 degrees, 5 degrees, 10 degrees and …), the distance between the selected current working points is determined by the saturation degree of the motor, the magnetic permeability of an iron core between two adjacent current working points needs to be ensured to be kept unchanged, and the iron core can be treated as a linear material. Calculating motor load alternate and direct axis flux linkage data corresponding to the selected current working point by adopting a simulation or experiment mode, and interpolating the obtained load alternate and direct axis flux linkage data to obtain load alternate and direct axis flux linkage models of all current working points in a current limit range, namely a nonlinear flux linkage model of the permanent magnet synchronous motor:
ψd(I,θ)＝ψd(id,iq)
ψq(I,θ)＝ψq(id,iq)
direct axis flux linkage model: psid(I,θ)＝ψd(id,iq) The direct-axis flux linkage psi of the motor can be correspondingly calculated according to the alternating-direct-axis current of the motord。
Quadrature axis flux linkage model: psiq(I,θ)＝ψq(id,iq) The quadrature-axis flux linkage psi of the motor can be correspondingly calculated according to the quadrature-axis and direct-axis currents of the motorq。
According to the obtained nonlinear flux linkage model, the electromagnetic torque, the load voltage and the like of the motor can be accurately calculated, and the calculation formulas of the electromagnetic torque and the load voltage are as follows:
torque calculation formula:
Te(I,θ)＝p(ψd(I,θ)iq-ψq(I,θ)id)
wherein, Te(I, theta) is electromagnetic torque, p is number of pole pairs of the motor, IdIs the direct axis current of the motor iqIs the quadrature axis current of the motor,. psidIs a direct axis flux linkage of the motorqIs the quadrature axis flux linkage of the motor.
Amplitude of voltage
Figure GDA0003443575650000101
Wherein the direct axis voltage
Figure GDA0003443575650000102
Quadrature axis voltage
Figure GDA0003443575650000103
w is the electrical angular velocity of the motor, R1Is the motor resistance.
The model combines the characteristic that the permanent magnet synchronous motor can be processed into a piecewise linear model when the iron core saturation is considered, only load flux linkages corresponding to a small part of current working points in the rated operating current range of the motor need to be calculated, then the load flux linkages of all current working points are obtained by utilizing the piecewise linear characteristic through interpolation, parameters such as inductance and permanent magnet flux linkages do not need to be calculated, the model is small in calculated amount and high in calculation speed, the change rule of the iron core saturation degree of the permanent magnet synchronous motor under different magnetization states and different load conditions can be accurately simulated, and the motor can be accurately modeled.
An example of a model is given below: taking a series-parallel magnetic circuit type permanent magnet synchronous motor with the pole number of 6, the slot number of 45, the rated rotating speed of 2100 revolutions per minute and the rated torque of 12.2Nm after saturation demagnetization as an example, a nonlinear flux linkage model of the motor is obtained by means of finite element simulation. At the moment, the magnetization state of the motor is saturation demagnetization, and the current of the motor is given as follows: direct axis current idThe value is (0, -2, -4, -6, -8, -10, -12) (A), for a total of 7 discrete current points; quadrature axis current iqThe value is (0, 2, 4, 6, 8, 10, 12) (A), and 7 discrete current points are provided; there are 49 discrete current operating points, 7 × 7. Through finite element simulation software, motor direct and alternating axis flux linkages of the motor at the 49 current working points in a saturated demagnetization state are obtained through simulation calculation, and flux linkages corresponding to other current working points between two adjacent current working points are interpolated to obtain direct and alternating axis load flux linkages corresponding to all current working points of the series-parallel permanent magnet synchronous motor in a current limit value range, namely a nonlinear flux linkage model of the motor, as shown in figure 5.
Acquiring a current track in an MTPA current control mode based on a double golden section iterative method: the current operating point with the minimum current amplitude can be obtained under the given torque instruction, rotation speed instruction and motor magnetizing state, so as to realize the MTPA control, which is specifically shown in fig. 3.
The process has two iterative loops: current angle iteration and current magnitude iteration. Firstly, current angle iteration is carried out, and the current angle iteration direction is the direction of current amplitude reduction under the given torque instruction, rotating speed instruction and motor magnetizing state; and nesting iteration of current amplitude while current angle iteration is carried out to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction in which the error between the given torque and the actual torque is reduced. When the iteration interval of the current angle is smaller than a given value, the current amplitude is considered to be converged to the minimum value, namely the MTPA working point.
Objective function value I (lambda) in current angle iterative loop stepk) And I (. beta.)k) The target function value obtained by calling the current amplitude iteration loop, where k is 1,2,3 …, that is, the current amplitude iteration loop needs to be called, is I (λ)1)、I(β1)；I(λ2)、I(β2)；I(λ3)、I(β3) …, the parameter output to the current amplitude iteration loop is a current angle probe point lambdak、βkWhen k is 1, θ is λ1And beta1Two values, where two current amplitude iteration cycles are required, k is 2,3 …, and θ is λkOr betakPerforming a current amplitude iteration loop, and outputting I (theta) through current amplitude iteration, which is equivalent to output I (lambda)k) Or I (. beta.)k) And returning to the current angle iteration loop as the objective function value.
The nonlinearity of the inductance and the permanent magnet flux linkage is considered, the current amplitude is difficult to directly obtain through a torque formula, so that amplitude iteration is nested in the current angle iteration process, a nonlinear load flux linkage model is used for calculating the torque in the amplitude iteration process, the influence of the nonlinearity of the inductance and the permanent magnet flux linkage is considered, and the current amplitude iteration result is accurate.
The implementation steps of obtaining the current track by MTPA control based on the double golden section iteration method are described as follows: the method comprises a current angle iteration loop step and a current amplitude iteration loop step.
The current angle iterative loop step comprises:
a1, initial current angle range [ a ]1,b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
Such as [ a ]1，b1]Take on values of [0 °, 90 ° ]]And simultaneously, setting iteration precision, and considering iteration convergence when the interval length is smaller than the given iteration precision along with the continuous process of the iteration process.
A2, judging the current amplitude target function value I (lambda) at the probe point of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk) And the iteration times k of the current angle is 1,2 and 3.
If yes, go to step A3; judging whether to execute the step A5;
the input of the current amplitude objective function is the current angle, and the output of the objective function is the current amplitude at a given torque, the objective function value I (λ [ - ])k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
a3, order ak+1＝λk，bk+1＝bkThen, then
λk+1＝ak+1+0.382(bk+1-ak+1)
＝ak+0.382(bk-ak)+0.382(bk-ak-0.382(bk-ak))
＝ak+0.618(bk-ak)＝βk
βk+1＝ak+1+0.618(bk+1-ak+1)，
A4, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step a7 is performed;
in this step, no calculation of lambda is performedk+1Because of I (λ)k+1)＝I(βk) I.e. using the result of the last iteration. Because the golden section coefficient is used for determining the tentative point in the next iteration, when the tentative point is selected next time, one tentative point is directly taken from the tentative point in the previous iteration, and only another tentative point needs to be recalculated, so that the calculation resources are saved, the calculation amount is small, and the calculation speed is high.
A5, order ak+1＝ak，bk+1＝βkThen, then
βk+1＝ak+1+0.618(bk+1-ak+1)
＝ak+0.618(ak+0.618(bk-ak)-ak)
＝ak+0.382(bk-ak)＝λk
λk+1＝ak+1+0.382(bk+1-ak+1)，
A6, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step a7 is performed;
without performing the calculation I (beta) in this stepk+1) Because of I (β)k+1)＝I(λk) I.e. using the result of the last iteration. Because the golden section coefficient is used for determining the tentative point in the next iteration, when the tentative point is selected next time, one tentative point is directly taken from the tentative point in the previous iteration, and only another tentative point needs to be recalculated, so that the calculation resources are saved, the calculation amount is small, and the calculation speed is high.
A7, let k be k + 1;
a8, judging whether the iteration converges: if b isk-ak＜L1Executing the step A9; otherwise, return to step A2;
wherein L is1Iteration precision is the current angle;
a9, judging whether the current operating point meets the requirements of current limit and voltage limit at the same time: if I (λ)k)≤Ilim&U(λk)≤Ulim，IlimFor a given current limit value, UlimOutputting the MTPA current track for a given voltage limit value; otherwise, inputting the torque and rotating speed commands again, and returning to execute the step A1;
the output MTPA current trace is: current amplitude I ═ I (λ)k) D, the current angle theta is lambdakThe working point of the device can obtain a series of work by inputting different rotating speeds and torquesThe point data.
When k is 1, the initial value of the probe point is lambda1、β1Inputting the current amplitude iteration, and calculating the objective function value I (lambda) by calling the current amplitude iteration loop1)、I(β1) Returning to the current angle iteration loop, determining which trial point is calculated when k +1 is calculated according to the judgment result of the step A2, calling the current amplitude iteration loop to finish the objective function value when k +1 is calculated, judging whether the iteration is converged according to the step A8, and continuing the iteration loop if the iteration is not converged; if the current limit and voltage limit requirements of the step A9 are converged and met, an MTPV track is output, and if the current limit and voltage limit requirements are converged and not met, the deviation of parameters input by the system is proved to be large, torque and rotating speed commands are input again, and two iteration loops are executed again from the beginning.
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And calculating the initial value mu of the current amplitude probing point1、v1：
μ1＝c1+0.382(d1-c1)、ν1＝c1+0.618(d1-c1)；
For example, when the current limit value is 12A, the initial value interval of the current value is set as [0A, 12A ], and the iteration precision is set, and as the iteration process continues, when the interval length is smaller than the given iteration precision, the iteration is considered to be converged.
B2, calculating a torque error objective function value at the two current amplitude probing points: f (. mu.) (1)、f(v1)，
Torque error objective function f (I)
Figure GDA0003443575650000131
Obtaining, wherein:
Figure GDA0003443575650000132
for a given torque, Te(I, theta) is torque corresponding to the current angle theta, and the current angle theta is not changed in the current amplitude iteration process and is determined as oneThe value of the current angle theta is a current angle probing point lambda of the current angle iterative cycle outputk、βk(ii) a I is the current amplitude, Id＝I sinθ，iq＝I cosθ；
Torque TeAnd (I, theta) is calculated and output by a motor nonlinear load quadrature-direct axis flux linkage model, and is obtained according to the following formula:
Te(I,θ)＝p(ψd(I,θ)iq-ψq(I,θ)id)
wherein p is the number of pole pairs of the motor, idIs the direct axis current of the motor iqIs the quadrature axis current of the motor,. psidIs a direct axis flux linkage of the motorqIs the quadrature axis flux linkage of the motor.
B3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) And the iteration number h of the current amplitude is 1,2 and 3.
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dhThen, then
μh+1＝ch+1+0.382(dh+1-ch+1)
＝ch+0.382(dh-ch)+0.382(dh-ch-0.382(dh-ch))
＝ch+0.618(dh-ch)＝vh
vh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝vhThen, then
vh+1＝ch+1+0.618(dh+1-ch+1)＝ch+0.618(ch+0.618(dh-ch)-ch)
＝ch+0.382(dh-ch)＝μh
μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwise, returning to the step B3; wherein L is2And the current amplitude iteration precision is obtained.
The current track is obtained by optimally controlling the efficiency of the weak magnetic area based on a double golden section iterative method: the current working point with the minimum current amplitude can be obtained under the given torque instruction, rotation speed instruction, voltage limit and current limit, and the efficiency optimal control of the weak magnetic region is realized, and the specific reference is shown in fig. 4.
The process has two iterative loops: flux weakening current angle iteration and current amplitude iteration. Firstly, iteration of a weak magnetic current angle is carried out, and under the given torque instruction, rotating speed instruction, voltage limit and current limit, the current angle iteration direction is the direction in which the current amplitude is reduced under the voltage limit; and nesting iteration of current amplitude while current angle iteration is carried out to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction in which the error between the given torque and the actual torque is reduced. And when the iteration interval of the current angle is smaller than a given value, the current amplitude is considered to be converged to the minimum value, namely the weak magnetic region efficiency optimal control working point.
The nonlinearity of the inductance and the permanent magnet flux linkage is considered, the current amplitude is difficult to directly obtain through a torque formula, so that amplitude iteration is nested in the current angle iteration process, a nonlinear load flux linkage model is used for calculating the torque in the amplitude iteration process, the influence of the nonlinearity of the inductance and the permanent magnet flux linkage is considered, and the current amplitude iteration result is accurate.
The implementation steps of obtaining the current track based on the optimal control of the efficiency of the weak magnetic area by the double golden section iteration method are described as follows: the method comprises a flux weakening current angle iteration loop step and a current amplitude iteration loop step.
The weak magnetic current angle iteration loop step comprises:
c1, initial current angle interval [ a1，b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
Such as [ a ]1，b1]Take on values of [0 °, 90 ° ]]And simultaneously, setting iteration precision, and considering iteration convergence when the interval length is smaller than the given iteration precision along with the continuous process of the iteration process.
C2, judging load voltage target function value U (beta)k) And voltage limit value UlimIf U (β) is large or smallk)＞UlimStep C6 is executed; otherwise, go to step C3;
load voltage objective function value U (β)k) Obtaining by calling a current amplitude iteration loop, wherein the current angle iteration number k is 1,2 and 3;
invoking current amplitude iterative loop output U (theta) ═ U (beta)k) Or U (lambda)k) In this embodiment, only U (. beta.) is usedk) The input of the load voltage objective function is a current angle, and the output is the load voltage under the given torque and the given rotating speed.
C3, judging the current amplitude target function value I (lambda) at the probing points of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk)，
If yes, go to step C4; if not, executing the step C6;
current magnitude objective function value I (λ)k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
the input of the current amplitude target function is a current angle, and the output is a current amplitude under a given torque and a given rotating speed.
C4, order ak+1＝λk，bk+1＝bkThen, then
λk+1＝ak+1+0.382(bk+1-ak+1)
＝ak+0.382(bk-ak)+0.382(bk-ak-0.382(bk-ak))
＝ak+0.618(bk-ak)＝βk
βk+1＝ak+1+0.618(bk+1-ak+1)，
C5, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step C8 is performed;
in this step, no calculation of lambda is performedk+1Because of I (λ)k+1)＝I(βk) I.e. using the result of the last iteration. Because the golden section coefficient is used for determining the tentative point in the next iteration, when the tentative point is selected next time, one tentative point is directly taken from the tentative point in the previous iteration, and only another tentative point needs to be recalculated, so that the calculation resources are saved, the calculation amount is small, and the calculation speed is high.
C6, order ak+1＝ak，bk+1＝βkThen, then
βk+1＝ak+1+0.618(bk+1-ak+1)
＝ak+0.618(ak+0.618(bk-ak)-ak)
＝ak+0.382(bk-ak)＝λk
λk+1＝ak+1+0.382(bk+1-ak+1)，
C7, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step C8 is performed;
without performing the calculation I (beta) in this stepk+1) Because of I (β)k+1)＝I(λk) Using the result of the last iterationAnd (4) finishing. Because the golden section coefficient is used for determining the tentative point in the next iteration, when the tentative point is selected next time, one tentative point is directly taken from the tentative point in the previous iteration, and only another tentative point needs to be recalculated, so that the calculation resources are saved, the calculation amount is small, and the calculation speed is high.
C8, let k be k + 1;
c9, judging whether the iteration converges: if b isk-ak＜L1Step C10 is executed; otherwise, returning to step C2;
wherein L is1Iteration precision is the current angle;
c10, judging whether the current working point meets the requirement of the current limit at the same time: if I (λ)k)≤Ilim，IlimOutputting a current track with optimal efficiency control in a weak magnetic area for a given current limit value; otherwise, the torque and rotating speed commands are input again, and the step C1 is executed again;
the current track for the optimal efficiency control of the weak magnetic region is as follows: current amplitude I ═ I (λ)k) D, the current angle theta is lambdakA series of working point data can be obtained by inputting different rotating speeds and torques.
When k is 1, the initial value of the probe point is lambda1、β1Inputting the current amplitude iteration, and calculating the objective function value I (lambda) by calling the current amplitude iteration loop1)、I(β1)、U(β1) Returning to the current angle iteration loop, determining which trial point is calculated when k +1 is calculated according to the judgment result of the step C2, calling the current amplitude iteration loop to finish the objective function value when k +1 is calculated, judging whether the iteration is converged according to the step C8, and continuing the iteration loop if the iteration is not converged; if the current limit requirement of the step C10 is converged and satisfied, outputting a current track with the optimal efficiency of the weak magnetic region, and if the current limit requirement is converged and not satisfied, proving that the parameter deviation input by the system is large, re-inputting a torque instruction and a rotating speed instruction, and re-executing two iteration cycles from the beginning.
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And is combined withCalculating initial value mu of current amplitude probe point1、ν1：
μ1＝c1+0.382(d1-c1)、ν1＝c1+0.618(d1-c1)；
For example, when the current limit value is 12A, the initial value interval of the current value is set as [0A, 12A ], and the iteration precision is set, and as the iteration process continues, when the interval length is smaller than the given iteration precision, the iteration is considered to be converged.
B2, calculating a torque error objective function value at the two current amplitude probing points: f (. mu.) (1)、f(ν1)，
Torque error objective function f (I)
Figure GDA0003443575650000171
Obtaining, wherein:
Figure GDA0003443575650000172
for a given torque, Te(I, theta) is torque corresponding to the current angle theta, and the current angle theta is a current angle probing point lambda output by the flux-weakening current angle iteration cyclek、βk(ii) a I is the current amplitude;
b3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) And the iteration number h of the current amplitude is 1,2 and 3.
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dhThen, then
μh+1＝ch+1+0.382(dh+1-ch+1)
＝ch+0.382(dh-ch)+0.382(dh-ch-0.382(dh-ch))
＝ch+0.618(dh-ch)＝vh
vh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝vhThen, then
vh+1＝ch+1+0.618(dh+1-ch+1)＝ch+0.618(ch+0.618(dh-ch)-ch)
＝ch+0.382(dh-ch)＝μh
μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwise, returning to the step B3; wherein L is2And the current amplitude iteration precision is obtained.
The current amplitude and the phase which are applied when any working point (given torque instruction, rotating speed instruction, voltage limit and current limit) is in the full-speed domain range (constant torque region below a basic speed value) and the weak magnetic region above the basic speed value to realize the optimal efficiency control can be obtained by the full-speed domain optimal efficiency control current trajectory searching method based on the double-golden section iterative method.
When the motor runs in a constant torque area, the load end voltage of the motor does not reach the limit value of the motor, and the efficiency optimal control current track searching method of the constant torque area is based on the idea of golden section, can obtain the current working point with the minimum current amplitude when the motor runs in the constant torque area under the given torque instruction and rotating speed instruction, and realizes the efficiency optimal control, namely MTPA control, of the constant torque area; when the motor operates in the weak magnetic area, if MTPA control is continuously adopted, the load end voltage of the motor exceeds a voltage limit value, direct axis weak magnetic current must be increased to reduce the load end voltage of the motor, and the efficiency optimal control current track searching method of the weak magnetic area is based on the idea of golden section, can obtain the current working point with the minimum current amplitude when the motor operates in the weak magnetic area under the given torque instruction, rotating speed instruction, voltage limit and current limit, and realizes the efficiency optimal control of the weak magnetic area.
And step three, calculating the iron loss of the motor under the corresponding working condition by using a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation, wherein the process comprises the following steps:
finite element simulation is used for calculating the loss of the motor under two working conditions: open circuit loss and short circuit loss
Figure GDA0003443575650000181
Calculating the equivalent hysteresis loss coefficient and the equivalent eddy current loss coefficient a in the formulah、bh、ae、be。
Figure GDA0003443575650000182
Figure GDA0003443575650000183
The above equations are open circuit losses and short circuit losses calculated based on the modified Steinmetz equation. a ishf、bhf represents hysteresis loss, aef2、bef2Representing eddy current losses.
Simplified iron loss calculation model of motor at any working point according to improved Steinmetz equation
Figure GDA0003443575650000184
Obtaining;
wherein the loss formula of the open circuit state is used to determine g1(U), formula of loss of short-circuit condition for determining
Figure GDA0003443575650000185
Figure GDA0003443575650000186
Figure GDA0003443575650000187
In the formula, ahIs an open-circuit equivalent hysteresis loss coefficient, bhFor short-circuit equivalent hysteresis loss coefficient, aeFor open-circuit equivalent eddy current loss coefficient, beIs the short circuit equivalent eddy current loss coefficient;
ψmis a no-load flux linkage idMotor direct axis flux linkage psi when 0d，ψm＝ψd(0,iq)；
Figure GDA0003443575650000191
For the d-axis armature reaction pressure drop,
Figure GDA0003443575650000192
ψmand psid(id,iq) And obtaining according to the nonlinear load flux linkage model.
In the above formula, the voltage amplitude U can be calculated by the load flux linkage,
Figure GDA0003443575650000193
Figure GDA0003443575650000194
for d-axis armature reaction voltage drop, it can be calculated by d-axis load flux linkage and d-axis no-load flux linkage considering cross-coupling effectSo as to obtain the compound with the characteristics of,
Figure GDA0003443575650000195
wherein psimAnd id is 0, and iq is d-axis flux linkage when the cross-axis current is loaded, namely d-axis no-load flux linkage considering cross coupling influence.
According to the current track obtained by the full-speed domain efficiency optimal control current track searching method, a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation are utilized, finite element simulation is not needed, and the iron loss of the motor under corresponding working conditions is calculated quickly and accurately.
The loss of the invention only calculates the copper loss and the iron loss, neglects the loss of the permanent magnet, and calculates the motor efficiency of each working point to form an efficiency MAP when the full-speed domain efficiency of the motor is optimally controlled by using the efficiency MAP fast calculation method, as shown in figure 2.

Claims (6)

1. The method for generating the full-speed domain efficiency MAP of the permanent magnet synchronous motor is characterized by comprising the following steps of:
the method comprises the steps that firstly, current tracks of a plurality of working points of a motor in a full-speed domain range are obtained by a full-speed domain efficiency optimal control current track searching method;
the method for searching the full-speed domain efficiency optimal control current track in the first step comprises the following steps: when the motor runs below a basic speed value, under the given torque instruction, rotating speed instruction, voltage limit and current limit, acquiring a current working point with the minimum current amplitude as a current track by adopting an MTPA control mode; when the motor operates above a basic speed value, under the given torque instruction, rotating speed instruction, voltage limit and current limit, acquiring a current working point with the minimum current amplitude as a current track by adopting an optimal efficiency control mode of a weak magnetic area;
the process of acquiring the current working point with the minimum current amplitude by adopting an MTPA control mode comprises a current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude; nesting a current amplitude iteration loop step in the current angle iteration process to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting an MTPA current track;
the process of obtaining the current working point with the minimum current amplitude by adopting the flux weakening area efficiency optimal control mode comprises a flux weakening current angle iteration circulation step and a current amplitude iteration circulation step, wherein the current angle iteration circulation step is firstly carried out, and the current angle iteration direction is the direction of reducing the current amplitude under the voltage limit; nesting a current amplitude iteration loop step in the current angle iteration process to determine the current amplitude corresponding to each current angle, wherein the iteration direction of the current amplitude is the direction of reducing the error between the given torque and the actual torque, and when the iteration interval of the current angle is smaller than the iteration precision of the given current angle, considering that the current amplitude has converged to the minimum value, and outputting the current track with the optimal efficiency control in the weak magnetic region;
step two, calculating the copper loss of the corresponding working point according to the current track of the step one;
thirdly, calculating the iron loss of the motor under corresponding working conditions by using a nonlinear load flux linkage model and a simplified iron loss calculation model based on an improved Steinmetz equation; the specific process is as follows:
simplified iron loss calculation model of motor at any working point according to improved Steinmetz equation
Figure FDA0003465104810000011
Obtaining;
wherein, g1(U) is the loss in the open circuit state,
Figure FDA0003465104810000012
loss for short circuit condition:
Figure FDA0003465104810000013
Figure FDA0003465104810000021
in the formula, ahIs an open-circuit equivalent hysteresis loss coefficient, bhFor short-circuit equivalent hysteresis loss coefficient, aeFor open-circuit equivalent eddy current loss coefficient, beIs the short circuit equivalent eddy current loss coefficient;
ψmis a no-load flux linkage, and idMotor direct axis flux linkage psi when 0dEqual, psim＝ψd(0，iq)；
Figure FDA0003465104810000022
For the d-axis armature reaction pressure drop,
Figure FDA0003465104810000023
ψmand psid(id，iq) Obtaining according to a nonlinear load flux linkage model; w is the electrical angular velocity of the motor, idIs the direct axis current of the motor iqIs quadrature axis current of the motor;
and step four, generating a full-speed domain efficiency MAP according to the copper loss in the step two and the iron loss in the step three.
2. The method for generating the full-speed domain efficiency MAP of the permanent magnet synchronous motor according to claim 1, wherein the step of obtaining the current operating point with the minimum current amplitude in the MTPA control mode comprises a current angle iteration loop step and a current amplitude iteration loop step:
the current angle iterative loop step comprises:
a1, initial current angle range [ a ]1，b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
A2, judging the current amplitude target function value I (lambda) at the probe point of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk) And the iteration times k of the current angle is 1,2 and 3.
If yes, go to step A3; judging whether to execute the step A5;
current magnitude objective function value I (λ)k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
a3, order ak+1＝λk，bk+1＝bk，λk+1＝βk，βk+1＝ak+1+0.618(bk+1-ak+1)，
A4, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step a7 is performed;
a5, order ak+1＝ak，bk+1＝βk，βk+1＝λk，λk+1＝ak+1+0.382(bk+1-ak+1)，
A6, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step a7 is performed;
a7, let k be k + 1;
a8, judging whether the iteration converges: if b isk-ak＜L1Executing the step A9; otherwise, return to step A2;
wherein L is1Iteration precision is the current angle;
a9, judging whether the current operating point meets the requirements of current limit and voltage limit at the same time: if I (λ)k)≤Ilim&U(λk)≤Ulim，IlimFor a given current limit value, UlimOutputting the MTPA current track for a given voltage limit value; otherwise, inputting the torque and rotating speed commands again, and returning to execute the step A1;
the current traces are: current amplitude I ═ I (λ)k) D, the current angle theta is lambdak；
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And calculating the initial value mu of the current amplitude probing point1、v1：
μ1＝c1+0.382(d1-c1)、v1＝c1+0.618(d1-c1)；
B2, calculating a torque error objective function value at the two current amplitude probing points: f (. mu.) (1)、f(v1)，
Torque error objective function f (I)
Figure FDA0003465104810000031
Obtaining, wherein:
Figure FDA0003465104810000032
for a given torque, Te(I, theta) is torque corresponding to current angle theta, Te(I, theta) is obtained by calculation according to a motor nonlinear load quadrature-direct axis flux linkage model; the current angle theta is a current angle probing point lambda output by current angle iterative cyclek、βk(ii) a I is the current amplitude;
b3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) And the iteration number h of the current amplitude is 1,2 and 3.
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dh，μh+1＝vh，vh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝νh，νh+1＝μh，μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwise, returning to the step B3; wherein L is2And the current amplitude iteration precision is obtained.
3. The method for generating the full-speed domain efficiency MAP of the permanent magnet synchronous motor according to claim 1, wherein the step of obtaining the current operating point with the minimum current amplitude by adopting the weak magnetic region efficiency optimal control mode comprises a weak magnetic current angle iteration loop step and a current amplitude iteration loop step:
the weak magnetic current angle iteration loop step comprises:
c1, initial current angle interval [ a1，b1]And calculating initial value lambda of current angle probing point1、β1：
λ1＝a1+0.382(b1-a1)、β1＝a1+0.618(b1-a1)；
C2, judging load voltage target function value U (beta)k) And voltage limit value UlimIf U (β) is large or smallk)＞UlimStep C6 is executed; otherwise, go to step C3;
load voltage objective function value U (β)k) Obtaining by calling a current amplitude iteration loop, wherein the current angle iteration number k is 1,2 and 3;
c3, judging the current amplitude target function value I (lambda) at the probing points of the two current anglesk) And I (. beta.)k) Whether or not the relation I (lambda) existsk)＞I(βk)，
If yes, go to step C4; if not, executing the step C6;
current magnitude objective function value I (λ)k) And I (. beta.)k) Obtaining by calling current amplitude iterative loop;
c4, order ak+1＝λk，bk+1＝bk，λk+1＝βk，βk+1＝ak+1+0.618(bk+1-ak+1)，
C5, calling current amplitude iterative loop to obtain current amplitude objective function value I (beta)k+1) Then, step C8 is performed;
c6, order ak+1＝ak，bk+1＝βk，βk+1＝λk，λk+1＝ak+1+0.382(bk+1-ak+1)，
C7, calling current amplitude iterative loop to obtain current amplitude target function value I (lambda)k+1) Then, step C8 is performed;
c8, let k be k + 1;
c9, judging whether the iteration converges: if b isk-ak＜L1Step C10 is executed; otherwise, returning to step C2;
wherein L is1Iteration precision is the current angle;
c10, judging whether the current working point meets the requirement of the current limit at the same time: if I (λ)k)≤Ilimm，IlimOutputting a current track with optimal efficiency control in a weak magnetic area for a given current limit value; otherwise, the torque and rotating speed commands are input again, and the step C1 is executed again;
the current traces are: current amplitude I ═ I (λ)k) D, the current angle theta is lambdak；
The current amplitude iterative loop step comprises:
b1, initial value interval of initialization current amplitude: [ c ] is1，d1]And calculating the initial value mu of the current amplitude probing point1、v1：
μ1＝c1+0.382(d1-c1)、v1＝c1+0.618(d1-c1)；
B2, calculating a torque error objective function value at the two current amplitude probing points: f (. mu.) (1)、f(v1)，
Torque error objective function f (I)
Figure FDA0003465104810000041
Obtaining, wherein:
Figure FDA0003465104810000042
for a given torque, Te(I, theta) is torque corresponding to current angle theta, Te(I, theta) is obtained by calculation according to a motor nonlinear load quadrature-direct axis flux linkage model; the current angle theta is a current angle probing point lambda output by current angle iterative cyclek、βk(ii) a I is the current amplitude;
b3, judging the torque error objective function value f (mu) at the probing point of the two current amplitudesh) And f (v)h) Whether or not the relationship f (μ) existsh)＞f(νh) And the iteration number h of the current amplitude is 1,2 and 3.
If yes, go to step B4; if not, executing the step B5;
b4, order ch+1＝μh，dh+1＝dh，μh+1＝vh，νh+1＝ch+1+0.618(dh+1-ch+1)，
Calculating the value of the objective function f (v)h+1) Then step B6;
b5, order ch+1＝ch，dh+1＝vh，vh+1＝μh，μh+1＝ch+1+0.382(dh+1-ch+1)，
Calculating the value of the objective function f (mu)h+1) Then step B6;
b6, let h be h +1,
b7, judging whether the iteration converges: if d ish-ch＜L2Outputting a current amplitude I (theta) and a voltage amplitude U (theta) corresponding to a given current angle, and outputting a result for an iterative search process of the current angle; otherwiseReturning to step B3; wherein L is2And the current amplitude iteration precision is obtained.
4. The method for generating the full-speed domain efficiency MAP of the PMSM according to claim 2 or 3, wherein the establishment process of the motor nonlinear load quadrature-direct axis flux linkage model is as follows:
selecting a series of current working points at equal intervals or at unequal intervals within the current limit range of the motor, wherein the current working points comprise an equal-interval or unequal-interval current amplitude series value and an equal-interval or unequal-interval current angle series value, the interval of the selected current working points is determined by the saturation degree of the motor, the magnetic permeability of an iron core between two adjacent current working points needs to be ensured to be kept unchanged, and the iron core is processed according to linear materials;
calculating motor load alternate and direct axis flux linkage data corresponding to the selected current working point by adopting a simulation or experiment mode, and interpolating the obtained load alternate and direct axis flux linkage data to obtain load alternate and direct axis flux linkage models of all current working points in a current limit range, namely a nonlinear flux linkage model of the permanent magnet synchronous motor:
ψd(I，θ)＝ψd(id，iq)
ψq(I，θ)＝ψq(id，iq)。
5. the method of generating a full speed domain efficiency MAP of a permanent magnet synchronous motor according to claim 4, wherein the torque T iseAnd (I, theta) is calculated and output by a motor nonlinear load quadrature-direct axis flux linkage model, and is obtained according to the following formula:
Te(I，θ)＝p(ψd(I，θ)iq-ψq(I，θ)id)
wherein p is the number of pole pairs of the motor, idIs the direct axis current of the motor iqIs the quadrature axis current of the motor,. psidIs a direct axis flux linkage of the motorqIs the quadrature axis flux linkage of the motor.
6. The method of generating a full-speed-domain efficiency MAP of a permanent magnet synchronous motor according to claim 5, wherein the voltage amplitude U (θ) is obtained as follows:
Figure FDA0003465104810000061
wherein the direct axis voltage
Figure FDA0003465104810000062
Quadrature axis voltage
Figure FDA0003465104810000063
w is the electrical angular velocity of the motor, R1Is the motor resistance.
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