CN107070343A - A kind of dynamic loss minimization controller method and system of line inductance electromotor - Google Patents
A kind of dynamic loss minimization controller method and system of line inductance electromotor Download PDFInfo
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- CN107070343A CN107070343A CN201710212339.1A CN201710212339A CN107070343A CN 107070343 A CN107070343 A CN 107070343A CN 201710212339 A CN201710212339 A CN 201710212339A CN 107070343 A CN107070343 A CN 107070343A
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- 238000000034 method Methods 0.000 title claims abstract description 67
- 230000004907 flux Effects 0.000 claims abstract description 93
- 230000006698 induction Effects 0.000 claims description 115
- 230000008569 process Effects 0.000 claims description 35
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 30
- 230000000694 effects Effects 0.000 claims description 22
- 230000005284 excitation Effects 0.000 claims description 18
- 229910052742 iron Inorganic materials 0.000 claims description 15
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 12
- 229910052802 copper Inorganic materials 0.000 claims description 12
- 239000010949 copper Substances 0.000 claims description 12
- 230000001276 controlling effect Effects 0.000 claims description 11
- 238000004364 calculation method Methods 0.000 claims description 10
- 230000009466 transformation Effects 0.000 claims description 10
- 230000001105 regulatory effect Effects 0.000 claims description 7
- 230000033228 biological regulation Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 3
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 230000008901 benefit Effects 0.000 description 3
- 238000011217 control strategy Methods 0.000 description 3
- 238000009795 derivation Methods 0.000 description 3
- 238000000053 physical method Methods 0.000 description 3
- 230000014509 gene expression Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000013178 mathematical model Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
Classifications
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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
- 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
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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
- 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
- H02P25/06—Linear motors
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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
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
-
- 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
- H02P2207/01—Asynchronous machines
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- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a kind of dynamic loss minimization controller method and system of line inductance electromotor, line inductance electromotor primary current i is gathered firstA、iB, speed v2, by v2Obtain secondary angular frequencyr；Based on direct field orientation method, by iA、iB、ωrObtain motor secondary magnetic linkage amplitude ψdr, magnetic linkage angle, θ1, by coordinate transform by θ1With iA、iBObtain primary d shaft currents idsWith primary q shaft currents iqs；Electromagnetic push F is obtained with reference to electric moter voltage equation, flux linkage equations；Based on F, ωrObtain the optimal magnetic linkage value of dynamic loss minimization controllerBy ψdr、ωr、ids、iqsRespectively with it is correspondingMore afterwards primary d shaft current controlled quentity controlled variables are obtained through PI regulationsPrimary q shaft currents controlled quentity controlled variablePrimary d shaft voltages controlled quentity controlled variablePrimary q shaft voltages controlled quentity controlled variableModulated again through coordinate transform and SVPWM, the line inductance electromotor operation of control Driven by inverter.Line inductance electromotor dynamic loss can be reduced, line inductance electromotor energy consumption is reduced, lift its performance driving economy.
Description
Technical Field
The invention belongs to the field of linear induction motors, and particularly relates to a dynamic minimum loss control method and system of a linear induction motor.
Background
The linear induction motor has the advantage of generating direct thrust, and is widely applied and developed in the industrial field, such as rail transit, servo systems, oil pumping units and the like. However, the linear induction motor is affected by the special structure of the primary magnetic circuit, which is disconnected, and the widths of the primary and secondary circuits are different, so that a serious longitudinal side effect and a serious transverse edge effect (collectively called side effect) exist in the operation process. The end effect will cause the excitation inductance to decay and the secondary resistance to rise, resulting in increased motor loss and reduced efficiency. On the other hand, when the motor operates under a light-load working condition, the motor has high copper consumption and low efficiency because the traditional control mode adopts constant excitation.
In order to improve the operation efficiency of the linear induction motor, a minimum loss control strategy can be adopted, and the excitation level of the motor is adjusted by optimally controlling a flux linkage so as to reduce the loss of the motor. The minimum loss control is divided into a physical method and a model method, wherein the physical method adopts an intelligent algorithm to search the optimal flux linkage on line, and the model method solves the optimal flux linkage by establishing a loss model. Obviously, compared with a physical method, the model method has the advantages of smaller calculation amount, high solving speed and the like, and has low requirement on hardware, so that the applicability is wide. Most of the current linear induction motor minimum loss control strategies based on a model method aim at steady-state working conditions and fail to carry out systematic research on the dynamic loss of the linear induction motor. In the dynamic operation process, the operation working conditions such as load, speed and the like are continuously changed, and the optimal flux linkage needs to be adjusted in real time according to the operation working conditions, so that the loss model of the magnetic flux linkage control system is more complicated than that in a steady state, and simultaneously, the magnetic flux linkage control system also puts high requirements on the practicability and the real-time performance of the control method. Currently, in the field, a complete dynamic loss model of the linear induction motor and a corresponding dynamic optimal flux linkage calculation method do not exist, and a practical dynamic minimum loss control strategy is lacked.
Disclosure of Invention
The invention provides a dynamic minimum loss control method and system of a linear induction motor, aiming at solving the defects or the improvement requirements of the prior art, deeply analyzing and calculating the copper loss and the iron loss of the linear induction motor in the dynamic process, then deducing a dynamic loss model of the linear induction motor, and providing a simple, convenient and practical method for estimating the dynamic optimal flux linkage value required by minimum loss control. The invention can effectively reduce the calculation amount of the dynamic optimal flux linkage value, reduce the dynamic loss of the linear induction motor, reduce the energy consumption of the linear induction motor and improve the operation economy of the linear induction motor.
To achieve the above object, according to an aspect of the present invention, there is provided a linear induction motor dynamic minimum loss control method, including:
(1) collectingPrimary current i of linear induction motorA、iBSpeed v of the motor2And from the motor speed v2Calculating to obtain the secondary angular frequency omega of the motorr；
(2) Based on direct magnetic field orientation method, using motor primary current iA、iBCombining the ABC- αβ coordinate transformation with the secondary angular frequency omega of the motorrCalculating to obtain secondary flux linkage amplitude psi of linear induction motordrAngle of secondary flux linkage theta1(ii) a From motor primary current iA、iBCombining a secondary flux linkage angle theta after ABC-dq coordinate transformation1Calculating to obtain a primary d-axis current idsWith primary q-axis current iqs；
(3) After correcting the excitation inductance and the secondary resistance of the dq axis of the linear induction motor based on the side effect coefficient, calculating by combining the voltage of the dq axis of the linear induction motor and the flux linkage of the dq axis of the linear induction motor to obtain the electromagnetic thrust F of the motor;
(4) based on electromagnetic thrust F and secondary angular frequency omega of motorrObtaining the optimal flux linkage value of the dynamic minimum loss control of the linear induction motor through the copper loss and the iron loss in the dynamic process of the linear induction motorThe secondary flux linkage amplitude psidrAnd the optimal flux linkage valueAfter comparison, obtaining primary d-axis current control quantity through PI regulationSecondary angular frequency omega of motorrAnd a preset valueAfter comparison, obtaining primary q-axis current control quantity through PI regulation
(5) Will convert the primary d-axis current idsAnd primary d-axis current control quantityAfter comparison, obtaining primary d-axis voltage control quantity through PI regulationThe primary q-axis current iqsWith primary q-axis current controlAfter comparison, obtaining primary q-axis voltage control quantity through PI regulationControlling the primary d-axis voltagePrimary q-axis voltage control quantityAnd carrying out Space Vector Pulse Width Modulation (SVPWM) after dq- αβ coordinate transformation, and controlling an inverter to drive a linear induction motor to operate.
Further, the voltage of the dq axis of the linear induction motor in the step (3) is as follows:
wherein u isdsIs the primary d-axis voltage, uqsFor primary q-axis voltage, idsFor primary d-axis current, iqsFor primary q-axis current, idrIs the secondary d-axis current, iqrFor secondary q-axis current, idmFor exciting branch d-axis current, iqmFor exciting branch q-axis current, psidsIs a primary d-axis flux linkage, psiqsIs a primary q-axis flux linkage, psidrIs a secondary d-axis flux linkage, #qrIs a secondary q-axis flux, ωsAt primary angular frequency, ωslFor slip angular frequency, p is a differential operator, RsIs a primary resistance, Rre＝KrCrRrIs an equivalent secondary resistance, RrIs a secondary resistance, KrCorrection factor for the secondary resistance of the longitudinal side effect, CrThe secondary resistance correction coefficient is the lateral edge effect.
Further, the flux linkage of the dq axis of the linear induction motor in the step (3) is as follows:
wherein L isme＝KxCxLm，idmFor exciting branch d-axis current, iqmFor exciting branch q-axis current, KxCorrection coefficient of excitation inductance for longitudinal side effect, CxAnd the correction coefficient is a transverse edge effect excitation inductance correction coefficient.
Further, the electromagnetic thrust F of the motor is: ,wherein idcFor the branch of the iron-loss resistor d-axis current, iqcThe q-axis current of the iron loss resistance branch circuit is shown, and tau is the pole pitch of the linear induction motor.
Further, the optimum flux linkage valueThe specific implementation mode is as follows:
determining a dynamic loss function of the linear induction motor:
wherein,is the primary copper loss in the dynamic process of the linear induction motor,for the secondary copper loss in the dynamic process of the linear induction motor,is the iron loss, R, in the dynamic process of the linear induction motorcThe resistance is an iron loss resistance, in a dynamic process, current and flux linkage are continuously changed due to the change of electromagnetic thrust and speed, and the voltage drop on each inductor is not zero. Secondary q-axis flux linkage psi when using secondary field orientationqrIf the value is zero, the dynamic loss function P of the linear induction motor is setlossThe method is simplified as follows:wherein t represents time, a1、a2、a3、a4、a5Represents the loss factor:
wherein, ω isrTo be the secondary angular frequency of the frequency,
based on PlossEstablishing an objective function:wherein, T represents the dynamic process duration of the linear induction motor, J represents the total energy loss of the motor when the dynamic process duration of the linear induction motor is T, and the obtained optimal flux linkage estimation value is as follows:wherein psi0Is the initial value psi of flux linkage in the dynamic process of the linear induction motor1Psi to be calculated in real time for the end value of flux linkage in the dynamic process of the linear induction motordr(t) optimal flux linkage value as dynamic minimum loss control for linear induction motor
According to another aspect of the present invention, there is provided a linear induction motor dynamic minimum loss control system comprising:
a controller for acquiring velocity v of the linear induction motor2Calculating to obtain the secondary angular frequency omega of the motorr；
The controller is also used for acquiring the primary current i of the linear induction motor based on a direct magnetic field orientation methodA、iBCombining the ABC- αβ coordinate transformation with the secondary angular frequency omega of the motorrCalculating to obtain secondary flux linkage amplitude psi of linear induction motordrAngle of secondary flux linkage theta1(ii) a Linear induced electricity obtained by collectionCurrent i of machine primaryA、iBCombining a secondary flux linkage angle theta after ABC-dq coordinate transformation1Calculating to obtain a primary d-axis current idsWith primary q-axis current iqs；
The controller is further used for correcting the excitation inductance and the secondary resistance of the dq axis of the linear induction motor based on the side effect coefficient, and then combining the voltage of the dq axis of the linear induction motor and the flux linkage calculation of the dq axis of the linear induction motor to obtain the electromagnetic thrust F of the motor;
the controller is also used for controlling the motor based on the electromagnetic thrust F and the secondary angular frequency omega of the motorrObtaining the optimal flux linkage value required for minimizing the dynamic loss of the linear induction motor
A first comparator for comparing the secondary flux linkage amplitude psidrAnd the optimal flux linkage valueComparing;
a first PI regulator for regulating the result compared by the first comparator to obtain a primary d-axis current control quantity
A second comparator for comparing the secondary angular frequency ω of the motorrAnd a preset valueComparing;
a second PI regulator for regulating the result compared by the second comparator to obtain a primary q-axis current control quantity
A third comparator for comparing the primary d-axis current idsAnd primary d-axis current control quantityComparing;
a third PI regulator for regulating the result compared by the third comparator to obtain a primary d-axis voltage control quantity
A fourth comparator for comparing the primary q-axis current iqsWith primary q-axis current controlComparing;
a fourth PI regulator for regulating the result compared by the fourth comparator to obtain the primary q-axis voltage control quantity
The controller is also used for controlling the primary d-axis voltagePrimary q-axis voltage control quantityAnd carrying out Space Vector Pulse Width Modulation (SVPWM) after dq- αβ coordinate transformation, and controlling an inverter to drive a linear induction motor to operate.
In general, compared with the prior art, the method can quickly estimate the optimal flux linkage value required by the dynamic minimum loss control of the linear induction motor on line, effectively reduce the optimal flux linkage calculation amount, reduce the dynamic loss of the linear induction motor and reduce the energy loss of the motor.
Drawings
FIG. 1 is a schematic diagram of a linear induction motor dynamic minimum loss control;
fig. 2(a) is an equivalent circuit of d-axis of the linear induction motor in the embodiment of the present invention;
fig. 2(b) is a q-axis equivalent circuit of the linear induction motor in the embodiment of the present invention;
fig. 3 is a graph showing flux linkage comparison, power loss comparison and energy loss comparison of the linear induction motor under dynamic minimum loss control and magnetic field orientation control during dynamic operation of the linear induction motor.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, a method for controlling dynamic minimum loss of a linear induction motor includes:
(1) collecting primary current i of linear induction motorA、iBSpeed v of the motor2And from the motor speed v2Calculating to obtain the secondary angular frequency omega of the motorr；
(2) Based on direct magnetic field orientation method, using motor primary current iA、iBCombining the ABC- αβ coordinate transformation with the secondary angular frequency omega of the motorrCalculating to obtain secondary flux linkage amplitude psi of linear induction motordrAngle of secondary flux linkage theta1(ii) a By electric motor primaryCurrent iA、iBCombining a secondary flux linkage angle theta after ABC-dq coordinate transformation1Calculating to obtain a primary d-axis current idsWith primary q-axis current iqs；
(3) After correcting the excitation inductance and the secondary resistance of the dq axis of the linear induction motor based on the side effect coefficient, calculating by combining the voltage of the dq axis of the linear induction motor and the flux linkage of the dq axis of the linear induction motor to obtain the electromagnetic thrust F of the motor;
(4) based on electromagnetic thrust F and secondary angular frequency omega of motorrObtaining the optimal flux linkage value of the dynamic minimum loss control of the linear induction motor through the copper loss and the iron loss in the dynamic process of the linear induction motorThe secondary flux linkage amplitude psidrAnd the optimal flux linkage valueAfter comparison, obtaining primary d-axis current control quantity through PI regulationSecondary angular frequency omega of motorrAnd a preset valueAfter comparison, obtaining primary q-axis current control quantity through PI regulation
(5) Will convert the primary d-axis current idsAnd primary d-axis current control quantityAfter comparison, obtaining primary d-axis voltage control quantity through PI regulationThe primary q-axis current iqsWith primary q-axis current controlAfter comparison, obtaining primary q-axis voltage control quantity through PI regulationControlling the primary d-axis voltagePrimary q-axis voltage control quantityAnd carrying out Space Vector Pulse Width Modulation (SVPWM) after dq- αβ coordinate transformation, and controlling the inverter to drive the linear induction motor to operate.
The invention deeply analyzes and calculates the copper loss and the iron loss of the linear induction motor in the dynamic process, then deduces a dynamic loss model of the linear induction motor, and provides a simple, convenient and practical method for estimating the dynamic optimal flux linkage value required by the minimum loss control, which is respectively explained below.
1. Mathematical model of linear induction motor
Fig. 2 is a d-q axis equivalent circuit of the linear induction motor, wherein fig. 2(a) is a d axis equivalent circuit and fig. 2(b) is a q axis equivalent circuit. In the figure, KrCorrection factor for the secondary resistance of the longitudinal side effect, KxCorrection coefficient of excitation inductance for longitudinal side effect, CrCorrection of the secondary resistance for lateral edge effects, CxAnd the correction coefficient is a transverse edge effect excitation inductance correction coefficient. These four coefficients can be expressed as:
wherein s is the slip ratio of the linear induction motor, G is the quality factor, tau is the polar distance, T, C1And C2As a function of slip and quality factor, Re(T)、Im(T) represents the real and imaginary parts of T, respectively. p is a radical ofeIs equivalent pole pair number, and its expression is
In the formula, npIs the actual pole pair number of the linear induction motor, and is short pitch, m1Q is the number of primary phases and the number of slots per pole per phase.
In FIG. 2, Rs、RcAnd RrRespectively, primary resistance, iron loss resistance and secondary resistance, LmIs an excitation inductance. In particular, the equivalent excitation inductance L is defined in consideration of the influence of the side-end effectmeAnd equivalent secondary resistance RreComprises the following steps:
based on the equivalent circuit shown in fig. 2, the voltage equation and flux linkage equation of the linear induction motor can be written as follows:
in the formula uds、uqsPrimary d-axis voltage, primary q-axis voltage, ids、iqs、idr、iqr、idm、iqmPrimary d-axis current, primary q-axis current, secondary d-axis current, secondary q-axis current, excitation branch d-axis current, excitation branch q-axis current, psids、ψqs、ψdr、ψqrAre respectively primary d-axis flux linkage, primary q-axis flux linkage, secondary d-axis flux linkage and secondary q-axis flux linkage, omegas、ωslPrimary angular frequency, slip angular frequency, respectively, and p is a differential operator.
The equations of the voltage and the current of the iron loss branch are as follows:
in the formula idc、iqcThe d-axis current and the q-axis current of the iron loss branch are respectively.
The electromagnetic thrust of the linear induction motor is as follows:
2. dynamic loss model of linear induction motor
The linear induction motor dynamic loss model can be expressed as:
wherein,is the primary copper loss in the dynamic process of the linear induction motor,for the secondary copper loss in the dynamic process of the linear induction motor,for the iron loss in the dynamic process of the linear induction motor, it should be noted that in the dynamic process, the current and the flux linkage are constantly changed due to the change of the electromagnetic thrust and the speed, so that the voltage drop on each inductor is not zero. With orientation of the secondary field, the secondary q-axis flux linkage psiqrIs zero, i.e.
ψqr＝0 (13)
The third term of the formulae (13) and (7) is:
the fourth term of the formulae (13) and (8) is:
iqm＝0 (15)
the second term of the formulas (15) and (8) is combined:
ψqs＝0 (16)
from the equivalent circuit, the d-axis voltage balance equation can be written as follows:
Rcidc＝pψds-ωsψqs(17)
from the formulae (16), (17) and (8):
based on equation (10) and the above derivation, it is possible to obtain:
similarly, the column writes the q-axis voltage balance equation:
Rciqc＝pψqs+ωsψds(20)
from the formulae (16), (20) and (8):
based on equation (10) and the above derivation, there are:
further, the following equations (11) and (13) can be derived:
the slip angular frequency can be expressed as:
the primary angular frequency can then be expressed as:
in the formula of omegarThe secondary angular frequency.
Based on the above derivation, the respective current expressions are now simplified as follows:
substituting (26) into (12) and finishing to obtain:
in the formula, t represents a certain time in the dynamic process of the linear induction motor, and each coefficient is defined as follows:
3. dynamic minimum loss control method for linear induction motor
The optimized objective function of the minimum loss control in the dynamic process of the linear induction motor is as follows:
wherein, T represents the dynamic process duration of the linear induction motor, and J represents the total energy loss of the dynamic process of the linear induction motor.
To the formula (27)The second partial derivative of (c) to obtain:
as is apparent from (32), a5Greater than zero, so:
therefore, the euler-lagrange equation under the optimized objective function is a sufficient necessary condition that the optimal flux linkage satisfies, namely:
the formula is simplified and arranged as follows:
equation (37) is a second-order non-second differential equation, and it is difficult to directly solve the optimal flux linkage analytic solution (in many cases, there is no analytic solution). Therefore, the optimal flux linkage estimation value is adopted to approximately replace the optimal flux linkage replacement analytic solution. Defining the optimal flux linkage estimation value as:
ψdr(t)＝ψ0+(ψ1-ψ0)(1-e-βt) (38)
wherein psi0And psi1The initial value corresponds to the steady-state optimal flux linkage value immediately before the dynamic process, and the final value corresponds to the steady-state optimal flux linkage value after the dynamic process is finished.
In the formula (38), β is an undetermined coefficient and can be obtained by iterative solution using a numerical method. However, the requirements of the dynamic operation process on the response capability of the motor and the calculation speed of the controller are high, and the calculation time consumption is long by adopting a numerical method, so that the dynamic performance of the motor is inevitably reduced.
In order to eliminate the iterative calculation process of numerical bureaus, the invention adopts a method for solving a special solution to obtain a beta value. Making the electromagnetic thrust F zero, a simplified euler-lagrange equation is obtained, as follows:
solving equation (39) yields:
in the formula, k is a coefficient to be constant. The index coefficient in equation (40) is extracted and made equal to β, i.e.:
the optimal flux linkage estimate is thus:
obtaining the optimal flux linkage estimation value at each moment according to the formula (42) real-time calculation, and taking the optimal flux linkage estimation value as the optimal flux linkage value of the dynamic minimum loss control of the linear induction motor
4. Minimum loss control effect analysis
Fig. 3 is a comparison of flux linkage, power loss, and energy loss of the linear induction motor when dynamic minimum loss control and magnetic field orientation control are employed during dynamic operation. It can be seen that compared with the field oriented control, the dynamic minimum loss control effectively reduces the power loss and energy loss of the linear induction motor by continuously adjusting the flux linkage on line.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A dynamic minimum loss control method of a linear induction motor is characterized by comprising the following steps:
(1) collecting primary current i of linear induction motorA、iBSpeed v of the motor2And from the motor speed v2Calculating to obtain the secondary angular frequency omega of the motorr；
(2) Based on direct magnetic field orientation method, using motor primary current iA、iBCombining the ABC- αβ coordinate transformation with the secondary angular frequency omega of the motorrCalculating to obtain secondary flux linkage of linear induction motorAmplitude psidrAngle of secondary flux linkage theta1(ii) a From motor primary current iA、iBCombining a secondary flux linkage angle theta after ABC-dq coordinate transformation1Calculating to obtain a primary d-axis current idsWith primary q-axis current iqs；
(3) After correcting the excitation inductance and the secondary resistance of the dq axis of the linear induction motor based on the side effect coefficient, calculating by combining the voltage of the dq axis of the linear induction motor and the flux linkage of the dq axis of the linear induction motor to obtain the electromagnetic thrust F of the motor;
(4) based on electromagnetic thrust F and secondary angular frequency omega of motorrObtaining the optimal flux linkage value of the dynamic minimum loss control of the linear induction motor through the copper loss and the iron loss in the dynamic process of the linear induction motorThe secondary flux linkage amplitude psidrAnd the optimal flux linkage valueAfter comparison, obtaining primary d-axis current control quantity through PI regulationSecondary angular frequency omega of motorrAnd a preset valueAfter comparison, obtaining primary q-axis current control quantity through PI regulation
(5) Will convert the primary d-axis current idsAnd primary d-axis current control quantityAfter comparison, obtaining primary d-axis voltage control quantity through PI regulationThe primary q-axis current iqsWith primary q-axis current controlAfter comparison, obtaining primary q-axis voltage control quantity through PI regulationControlling the primary d-axis voltagePrimary q-axis voltage control quantityAnd carrying out Space Vector Pulse Width Modulation (SVPWM) after dq- αβ coordinate transformation, and controlling an inverter to drive a linear induction motor to operate.
2. The method of claim 1, wherein the voltage of the dq axis of the linear induction motor in the step (3) is:
<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <msub> <mi>u</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>R</mi> <mi>s</mi> </msub> <msub> <mi>i</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> <mo>+</mo> <mi>p</mi> <msub> <mi>&psi;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>&omega;</mi> <mi>s</mi> </msub> <msub> <mi>&psi;</mi> <mrow> <mi>q</mi> <mi>s</mi> </mrow> </msub> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>u</mi> <mrow> <mi>q</mi> <mi>s</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>R</mi> <mi>s</mi> </msub> <msub> <mi>i</mi> <mrow> <mi>q</mi> <mi>s</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>p&psi;</mi> <mrow> <mi>q</mi> <mi>s</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>&omega;</mi> <mi>s</mi> </msub> <msub> <mi>&psi;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mn>0</mn> <mo>=</mo> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>d</mi> <mi>r</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>p&psi;</mi> <mrow> <mi>d</mi> <mi>r</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>&omega;</mi> <mrow> <mi>s</mi> <mi>l</mi> </mrow> </msub> <msub> <mi>&psi;</mi> <mrow> <mi>q</mi> <mi>r</mi> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mn>0</mn> <mo>=</mo> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>q</mi> <mi>r</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>p&psi;</mi> <mrow> <mi>q</mi> <mi>r</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>&omega;</mi> <mrow> <mi>s</mi> <mi>l</mi> </mrow> </msub> <msub> <mi>&psi;</mi> <mrow> <mi>d</mi> <mi>r</mi> </mrow> </msub> </mrow> </mtd> </mtr> </mtable> </mfenced>
wherein u isdsIs the primary d-axis voltage, uqsFor primary q-axis voltage, idsFor primary d-axis current, iqsFor primary q-axis current, idrIs the secondary d-axis current, iqrFor secondary q-axis current, idmFor exciting branch d-axis current, iqmFor exciting branch q-axis current, psidsIs a primary d-axis flux linkage, psiqsIs a primary q-axis flux linkage, psidrIs a secondary d-axis flux linkage, #arIs a secondary q-axis flux, ωsAt primary angular frequency, ωslFor slip angular frequency, p is a differential operator, RsIs a primary resistance, Rre＝KrCrRrIs an equivalent secondary resistance, RrIs a secondary resistance, KrCorrection factor for the secondary resistance of the longitudinal side effect, CrThe secondary resistance correction coefficient is the lateral edge effect.
3. The method of claim 2, wherein the flux linkage of the dq axis of the linear induction motor in step (3) is:
<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <msub> <mi>&psi;</mi> <mrow> <mi>d</mi> <mi>s</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>d</mi> <mi>m</mi> </mrow> </msub> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>&psi;</mi> <mrow> <mi>q</mi> <mi>s</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>q</mi> <mi>m</mi> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>&psi;</mi> <mrow> <mi>d</mi> <mi>r</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>d</mi> <mi>m</mi> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>&psi;</mi> <mrow> <mi>q</mi> <mi>r</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> </msub> <msub> <mi>i</mi> <mrow> <mi>q</mi> <mi>m</mi> </mrow> </msub> </mrow> </mtd> </mtr> </mtable> </mfenced>1
wherein L isme＝KxCxLm，idmFor exciting branch d-axis current, iqmFor exciting branch q-axis current, KxCorrection coefficient of excitation inductance for longitudinal side effect, CxAnd the correction coefficient is a transverse edge effect excitation inductance correction coefficient.
4. A method according to claim 3, wherein the electromagnetic thrust F of the machine is: ,wherein idcFor the branch of the iron-loss resistor d-axis current, iqcThe q-axis current of the iron loss resistance branch circuit is shown, and tau is the pole pitch of the linear induction motor.
5. The method of claim 4, wherein the optimal flux linkage valueThe specific implementation mode is as follows:
determining a dynamic loss function of the linear induction motor:
wherein,is the primary copper loss in the dynamic process of the linear induction motor,for the secondary copper loss in the dynamic process of the linear induction motor,is the iron loss, R, in the dynamic process of the linear induction motorcThe resistance is an iron loss resistance, in a dynamic process, current and flux linkage are continuously changed due to the change of electromagnetic thrust and speed, and the voltage drop on each inductor is not zero. Secondary q-axis flux linkage psi when using secondary field orientationqrIf the value is zero, the dynamic loss function P of the linear induction motor is setlossThe method is simplified as follows:wherein t represents time, a1、a2、a3、a4、a5Represents the loss factor:
<mrow> <msub> <mi>a</mi> <mn>1</mn> </msub> <mo>=</mo> <mfrac> <msub> <mi>R</mi> <mi>s</mi> </msub> <msubsup> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> <mn>2</mn> </msubsup> </mfrac> <mo>+</mo> <mfrac> <msubsup> <mi>&omega;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <msub> <mi>R</mi> <mi>c</mi> </msub> </mfrac> <mo>+</mo> <mfrac> <mrow> <msubsup> <mi>&omega;</mi> <mi>r</mi> <mn>2</mn> </msubsup> <msub> <mi>R</mi> <mi>s</mi> </msub> </mrow> <msubsup> <mi>R</mi> <mi>c</mi> <mn>2</mn> </msubsup> </mfrac> </mrow>
<mrow> <msub> <mi>a</mi> <mn>2</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>R</mi> <mi>s</mi> </msub> </mrow> <msub> <mi>L</mi> <mrow> <mi>m</mi> <mi>e</mi> </mrow> </msub> </mfrac> <mrow> <mo>(</mo> <mfrac> <mn>1</mn> <msub> <mi>R</mi> <mi>c</mi> </msub> </mfrac> <mo>+</mo> <mfrac> <mn>1</mn> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> </mfrac> <mo>)</mo> </mrow> </mrow>
<mrow> <msub> <mi>a</mi> <mn>3</mn> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>&tau;&omega;</mi> <mi>r</mi> </msub> <mi>F</mi> </mrow> <mrow> <msub> <mi>&pi;R</mi> <mi>c</mi> </msub> </mrow> </mfrac> <mrow> <mo>(</mo> <msub> <mi>R</mi> <mi>s</mi> </msub> <mo>+</mo> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <mo>+</mo> <mfrac> <mrow> <msub> <mi>R</mi> <mi>s</mi> </msub> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> </mrow> <msub> <mi>R</mi> <mi>c</mi> </msub> </mfrac> <mo>)</mo> </mrow> </mrow>
<mrow> <msub> <mi>a</mi> <mn>4</mn> </msub> <mo>=</mo> <mfrac> <mrow> <msup> <mi>&tau;</mi> <mn>2</mn> </msup> <msup> <mi>F</mi> <mn>2</mn> </msup> </mrow> <mrow> <msup> <mi>&pi;</mi> <mn>2</mn> </msup> <msubsup> <mi>R</mi> <mi>c</mi> <mn>2</mn> </msubsup> </mrow> </mfrac> <mrow> <mo>(</mo> <msub> <mi>R</mi> <mi>c</mi> </msub> <mo>+</mo> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <mo>)</mo> </mrow> <mrow> <mo>(</mo> <msub> <mi>R</mi> <mi>s</mi> </msub> <msub> <mi>R</mi> <mi>c</mi> </msub> <mo>+</mo> <msub> <mi>R</mi> <mi>s</mi> </msub> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>R</mi> <mi>c</mi> </msub> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow>
<mrow> <msub> <mi>a</mi> <mn>5</mn> </msub> <mo>=</mo> <mfrac> <mn>1</mn> <msub> <mi>R</mi> <mi>c</mi> </msub> </mfrac> <mo>+</mo> <mfrac> <mn>1</mn> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> </mfrac> <mo>+</mo> <mfrac> <msub> <mi>R</mi> <mi>s</mi> </msub> <msubsup> <mi>R</mi> <mi>c</mi> <mn>2</mn> </msubsup> </mfrac> <mo>+</mo> <mfrac> <msub> <mi>R</mi> <mi>s</mi> </msub> <msubsup> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> <mn>2</mn> </msubsup> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>R</mi> <mi>s</mi> </msub> </mrow> <mrow> <msub> <mi>R</mi> <mi>c</mi> </msub> <msub> <mi>R</mi> <mrow> <mi>r</mi> <mi>e</mi> </mrow> </msub> </mrow> </mfrac> <mo>,</mo> </mrow>
wherein, ω isrTo be the secondary angular frequency of the frequency,
based on PlossEstablishing an objective function:wherein T represents the dynamic process duration of the linear induction motor, and J represents the dynamic state of the linear induction motorThe optimal flux linkage estimation value obtained by the total energy loss of the motor in the process is as follows:wherein psi0Is the initial value psi of flux linkage in the dynamic process of the linear induction motor1Psi to be calculated in real time for the end value of flux linkage in the dynamic process of the linear induction motordr(t) optimal flux linkage value as dynamic minimum loss control for linear induction motor
6. A linear induction motor dynamic minimum loss control system, comprising:
a controller for acquiring velocity v of the linear induction motor2Calculating to obtain the secondary angular frequency omega of the motorr；
The controller is also used for acquiring the primary current i of the linear induction motor based on a direct magnetic field orientation methodA、iBCombining the ABC- αβ coordinate transformation with the secondary angular frequency omega of the motorrCalculating to obtain secondary flux linkage amplitude psi of linear induction motordrAngle of secondary flux linkage theta1(ii) a Acquired primary current i of linear induction motorA、iBCombining a secondary flux linkage angle theta after ABC-dq coordinate transformation1Calculating to obtain a primary d-axis current idsWith primary q-axis current iqs；
The controller is further used for correcting the excitation inductance and the secondary resistance of the dq axis of the linear induction motor based on the side effect coefficient, and then combining the voltage of the dq axis of the linear induction motor and the flux linkage calculation of the dq axis of the linear induction motor to obtain the electromagnetic thrust F of the motor;
the controller is also used for controlling the motor based on the electromagnetic thrust F and the secondary angular frequency omega of the motorrObtaining the optimal flux linkage value required for minimizing the dynamic loss of the linear induction motor
A first comparator for comparing the secondary flux linkage amplitude psidrAnd the optimal flux linkage valueComparing;
a first PI regulator for regulating the result compared by the first comparator to obtain a primary d-axis current control quantity
A second comparator for comparing the secondary angular frequency ω of the motorrAnd a preset valueComparing;
a second PI regulator for regulating the result compared by the second comparator to obtain a primary q-axis current control quantity
A third comparator for comparing the primary d-axis current idsAnd primary d-axis current control quantityComparing;
a third PI regulator for regulating the result compared by the third comparator to obtain a primary d-axis voltage control quantity
A fourth comparator for comparing the primary q-axis current iqsWith primary q-axis current controlComparing;
a fourth PI regulator forRegulating the result of comparison by the fourth comparator to obtain the primary q-axis voltage control quantity
The controller is also used for controlling the primary d-axis voltagePrimary q-axis voltage control quantityAnd carrying out Space Vector Pulse Width Modulation (SVPWM) after dq- αβ coordinate transformation, and controlling an inverter to drive a linear induction motor to operate.
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| CN108540037A (en) * | 2018-05-15 | 2018-09-14 | 华中科技大学 | A kind of line inductance electromotor normal force Detection ＆ Controling method and system |
| CN108616234A (en) * | 2018-05-15 | 2018-10-02 | 华中科技大学 | Line inductance electromotor drive system is lost and normal force optimal control method and system |
| CN108616234B (en) * | 2018-05-15 | 2020-07-14 | 华中科技大学 | Linear induction motor driving system loss and normal force optimization control method and system |
| CN108540037B (en) * | 2018-05-15 | 2020-07-28 | 华中科技大学 | Linear induction motor normal force detection and control method and system |
| CN108964549A (en) * | 2018-07-04 | 2018-12-07 | 华中科技大学 | Line inductance electromotor predicts thrust control method without weight Modulus Model |
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