Disclosure of Invention
The invention aims to provide a direct torque control method of a double-independent-power-supply type open-winding permanent magnet synchronous motor system based on a simplified switch table, so as to solve the problems of complex switch table, complex selected voltage vector and large motor torque ripple in the related technology.
In order to achieve the purpose, the invention adopts the technical scheme that:
in a first aspect, an embodiment of the present invention provides a direct torque control method for an open-winding permanent magnet synchronous motor system, including:
collecting three-phase stator current, line voltage and rotor position angle of the motor, and differentiating the rotor position angle to obtain the rotating speed of the motor;
calculating a flux linkage vector of the motor according to the three-phase stator current and the line voltage, and calculating a flux linkage given vector according to the rotor position angle;
respectively calculating reference voltage vectors of the motor in an alpha-beta coordinate system and an a-b-c coordinate system according to a flux linkage vector and a flux linkage given vector of the motor and a coordinate transformation principle;
calculating the area mark of the motor reference voltage vector according to the reference voltage vector of the motor in an a-b-c coordinate system, and selecting the required basic voltage vector by simplifying a switch table;
and generating a driving signal of each phase bridge arm switching device in the double inverter according to the preset switching state combination corresponding to each basic voltage vector so as to control the motor system.
Further, calculating a flux linkage vector of the motor according to the three-phase stator current and the line voltage, wherein the flux linkage vector comprises the following steps:
ψα=∫(uα-Rsiα)dt
ψβ=∫(uβ-Rsiβ)dt
wherein: u. ofα、uβStator voltages, u, of the motor's alpha and beta axes, respectivelyab、ubcLine voltages i between phases a and b and between phases b and c of the motor, respectivelyα、iβStator currents, i, of the motor's alpha and beta axes, respectivelya~icThree-phase stator currents of the electric machine, psiα、ΨβFlux linkage, R, of the motor's alpha and beta axes, respectivelysIs the stator resistance of the motor.
Further, calculating a flux linkage given vector according to the rotor position angle comprises:
θr=np×θr0
θδ=arcsin(kp(ωr_ref-ωr)+ki∫(ωr_ref-ωr)dt)
ψα_ref=|ψs_ref|·cos(θδ+θr)
ψβ_ref=|ψs_ref|·sin(θδ+θr)
wherein: thetarIs the rotor electrical angle of the motor, npIs the number of pole pairs, θ, of the motorr0Is the rotor position angle, θδIs the power angle, omega, of the motorr_refFor a given speed of rotation, ω, of the motorrIs the rotational speed of the motor, kpIs a proportionality coefficient, kiIs an integral coefficient, Ψα_ref、Ψβ_refFor the flux linkage of the alpha and beta axes of the motor, a vector is given, psis_refAnd setting the stator flux linkage value of the motor.
Further, calculating a reference voltage vector of the motor in an alpha-beta coordinate system, comprising:
Vα_ref=(ψα_ref-ψα)/Ts+Rsiα
Vβ_ref=(ψβ_ref-ψβ)/Ts+Rsiβ
wherein: vα_ref、Vβ_refReference voltages for the alpha and beta axes of the motor, Ψα_ref、Ψβ_refBy a given amount, psi, for the flux linkage of the motor's alpha and beta axesα、ΨβIs the flux linkage of the alpha axis and the beta axis of the motor, TsIs the sampling period of the system, RsIs the stator resistance of the motor, iα、iβThe stator currents of the alpha axis and the beta axis of the motor.
Further, calculating a reference voltage vector of the motor under an a-b-c coordinate system, comprising:
wherein: va_ref、Vb_ref、Vc_refReference voltages V of three phases of the motor in an a-b-c coordinate systemα_ref、Vβ_refReference voltages for the alpha and beta axes of the motor.
Further, calculating a zone flag of the motor reference voltage vector, comprising:
wherein: x represents one of three abc phases, i.e. x ═ a, b, c, VdcIs the sum of the dc voltages of the two dc voltage sources.
Further, the required basic voltage vector is selected by simplifying a switch table, and the method comprises the following steps:
the selected basic voltage vector is obtained from table 1:
TABLE 1
Wherein: v. ofm(m ═ 1,2,3,. and 19) respectively represent at Vdc1=Vdc2In the case of open-winding permanent-magnet synchronous machines, 19 basic voltage vectors, where Vdc1、Vdc2The voltages of the two dc voltage sources, respectively, "/" indicates that the corresponding zone-mark combination is not present in the space voltage vector plane.
Further, the combination of the switch states corresponding to each preset basic voltage vector includes:
the switching state combination corresponding to the preset basic voltage vector is obtained through table 2:
TABLE 2
Wherein: sa1Sb1Sc1-Sa2Sb2Sc2The states of the switching devices in six bridge arms of the double-inverter are shown, if the switching device of the upper bridge arm is conducted, S is equal to 1, and if the switching device of the lower bridge arm is conducted, S is equal to 0.
In a second aspect, an embodiment of the present invention provides a direct torque control apparatus for an open-winding permanent magnet synchronous motor system, including:
the acquisition module is used for acquiring three-phase stator current, line voltage and a rotor position angle of the motor and differentiating the rotor position angle to obtain the rotating speed of the motor;
the first calculation module is used for calculating a flux linkage vector of the motor according to the three-phase stator current and the line voltage and calculating a flux linkage given vector according to the rotor position angle;
the second calculation module is used for calculating reference voltage vectors of the motor in an alpha-beta coordinate system and an a-b-c coordinate system respectively according to the flux linkage vector and the flux linkage given vector of the motor and a coordinate transformation principle;
the table look-up module is used for calculating the area mark of the motor reference voltage vector according to the reference voltage vector of the motor in the a-b-c coordinate system and selecting the required basic voltage vector by simplifying a switch table;
and the driving signal generating module is used for generating driving signals of the switching devices of the bridge arms of each phase in the double inverter according to the preset switching state combination corresponding to each basic voltage vector so as to control the motor system.
According to the embodiment of the invention, the projection of the basic voltage vector in three phases abc is used for dividing the space voltage vector plane, and the concept of the area mark is introduced, so that the selection of the basic voltage vector is realized, the switching state of each bridge arm is obtained to generate the driving signal of each switching device, the control is applied to the motor system, and the whole control structure is simpler; the control algorithm eliminates a hysteresis comparator required in the traditional structure, simplifies a switching table, improves the precision of the selected voltage vector, and has low torque ripple and flux linkage ripple of the motor, thereby improving the static running performance of a motor system.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of the present invention and the above-described drawings, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
In accordance with an embodiment of the present invention, there is provided an embodiment of a method for direct torque control of an open-winding permanent magnet synchronous machine system, wherein the steps illustrated in the flowchart of the figure may be performed in a computer system, such as a set of computer executable instructions, and wherein, although a logical order is illustrated in the flowchart, in some cases, the steps illustrated or described may be performed in an order different than that illustrated herein.
FIG. 1 is a typical dual independent power type open-winding permanent magnet synchronous motor system structure applicable to the embodiment of the present invention, which includes an open-winding permanent magnet synchronous motor 1 and two three-phase six switchesInverters 2 and 3, in which the DC voltages of the two inverters are equal, i.e. Vdc1=Vdc2。
FIG. 2 is a flow chart of a method of direct torque control of an open-winding permanent magnet synchronous motor system according to an embodiment of the present invention; FIG. 3 is a control block diagram of a direct torque control method of an open-winding permanent magnet synchronous motor system according to an embodiment of the present invention; as shown in fig. 2, the method comprises the steps of:
step S101, collecting three-phase stator current, line voltage and rotor position angle of a motor, and differentiating the rotor position angle to obtain the rotating speed of the motor;
step S102, calculating a flux linkage vector of the motor according to the three-phase stator current and the line voltage, and calculating a flux linkage given vector according to the rotor position angle;
step S103, respectively calculating reference voltage vectors of the motor in an alpha-beta coordinate system and an a-b-c coordinate system according to a flux linkage vector and a flux linkage given vector of the motor and a coordinate transformation principle;
step S104, calculating the area mark of the motor reference voltage vector according to the reference voltage vector of the motor in the a-b-c coordinate system, and selecting the required basic voltage vector through a simplified switch table;
and step S105, generating driving signals of the switching devices of the bridge arms of each phase in the double inverter according to the preset switching state combination corresponding to each basic voltage vector for controlling the motor system.
According to the embodiment of the invention, the projection of the basic voltage vector in three phases abc is used for dividing the space voltage vector plane, and the concept of the area mark is introduced, so that the selection of the basic voltage vector is realized, the switching state of each bridge arm is obtained to generate the driving signal of each switching device, the control is applied to the motor system, and the whole control structure is simpler; the control algorithm eliminates a hysteresis comparator required in the traditional structure, simplifies a switching table, improves the precision of the selected voltage vector, and has low torque ripple and flux linkage ripple of the motor, thereby improving the static running performance of a motor system.
As shown in fig. 3, the method comprises the steps of:
according to the embodiment of the invention, the three-phase stator current, the line voltage and the rotor position angle of the motor are collected, and the rotor position angle is differentiated to obtain the motor rotating speed, which specifically comprises the following steps:
three-phase current sensor 3-1 is used for collecting three-phase stator current signals i of open-winding permanent magnet synchronous motor 1a~icThe stator line voltage u of the open winding permanent magnet synchronous motor 1 is collected by a voltage sensor 3-2ab、ubcAnd the encoder 3-3 measures the rotor angle theta of the permanent magnet synchronous motor 1r0And obtaining the rotor electrical angular velocity omega by the rotor position angle through a d/dt differentiatorrElectric angle of rotor thetarCan be calculated by the following formula:
θr=np×θr0
wherein: n ispIs the number of pole pairs of the motor.
According to the embodiment of the invention, the flux linkage vector of the motor is calculated according to the three-phase stator current and the line voltage, and the flux linkage given vector is calculated according to the rotor position angle, which is as follows:
to connect the stator line voltage uab、ubcAnd three-phase stator current ia~icThe voltage vector u of the motor under an alpha-beta coordinate system is obtained through coordinate transformation after the input into a Clark transformation module 4αβAnd stator current vector iαβThe calculation formula is as follows:
will voltage vector uαβAnd stator current vector iαβThe input stator flux linkage calculation module 5 obtains a flux linkage vector psi of the motorαβThe calculation formula is as follows:
ψα=∫(uα-Rsiα)dt
ψβ=∫(uβ-Rsiβ)dt
wherein: u. ofα、uβStator voltages, u, of the motor's alpha and beta axes, respectivelyab、ubcLine voltages i between phases a and b and between phases b and c of the motor, respectivelyα、iβStator currents, i, of the motor's alpha and beta axes, respectivelya~icThree-phase stator currents of the electric machine, psiα、ΨβFlux linkage, R, of the motor's alpha and beta axes, respectivelysIs the stator resistance of the motor.
Given speed of rotation omegar_refWith the motor speed omegarInputting the sine value sin theta of the power angle of the motor obtained by the PI regulator module 6δThen obtaining the motor power angle theta through arc tangent treatmentδThe calculation formula is as follows:
θδ=arcsin(kp(ωr_ref-ωr)+ki∫(ωr_ref-ωr)dt)
wherein: thetaδIs the power angle, omega, of the motorr_refFor a given speed of rotation, ω, of the motorrIs the rotational speed of the motor, kpIs a proportionality coefficient, kiIs an integral coefficient.
Given value psi of magnetic flux linkages_refAngle theta of motorδAnd rotor electrical angle thetarInput into a given flux linkage calculation module 7 to obtain a given flux linkage vector psiαβ_refThe calculation formula is as follows:
ψα_ref=|ψs_ref|·cos(θδ+θr)
ψβ_ref=|ψs_ref|·sin(θδ+θr)
wherein: wherein: thetarIs the rotor electrical angle of the motor, npIs the number of pole pairs, θ, of the motorr0Is the rotor position angle, θδIs the power angle of the motorα_ref、Ψβ_refFor the flux linkage of the alpha and beta axes of the motor, a vector is given, psis_refAnd setting the stator flux linkage value of the motor.
According to the above embodiment of the present invention, the reference voltage vectors of the motor in the α - β coordinate system and the a-b-c coordinate system are calculated according to the flux linkage vector and the flux linkage given vector of the motor and the coordinate transformation principle, specifically as follows:
will give the flux linkage vector Ψαβ_refWith flux linkage vector ΨαβThe difference is input into a reference voltage vector calculation module 8 to obtain a reference voltage vector V of the motor under an alpha-beta coordinate systemαβ_refThe required formula is as follows:
Vα_ref=(ψα_ref-ψα)/Ts+Rsiα
Vβ_ref=(ψβ_ref-ψβ)/Ts+Rsiβ
wherein: vα_ref、Vβ_refReference voltages for the alpha and beta axes of the motor, Ψα_ref、Ψβ_refBy a given amount, psi, for the flux linkage of the motor's alpha and beta axesα、ΨβIs the flux linkage of the alpha axis and the beta axis of the motor, TsIs the sampling period of the system, RsIs the stator resistance of the motor, iα、iβThe stator currents of the alpha axis and the beta axis of the motor.
A reference voltage vector V under an alpha-beta coordinate systemαβ_refInputting the Clark inverse transformation module 9 to obtain a reference voltage vector V under an a-b-c coordinate systemabc_refThe required formula is as follows:
wherein: va_ref、Vb_ref、Vc_refReference voltages V of three phases of the motor in an a-b-c coordinate systemα_ref、Vβ_refReference voltages for the alpha and beta axes of the motor.
According to the above embodiment of the present invention, the area flag of the reference voltage vector of the motor is calculated according to the reference voltage vector of the motor in the a-b-c coordinate system, and the required basic voltage vector is selected by simplifying the switch table, specifically:
reference voltage vector Vabc_refInputting the signals into the switching signal generation module 10, fig. 4 is a sector division diagram of space voltage vector, and the region mark R of the motor reference voltage vector is obtained by calculationabcThe required formula is as follows:
wherein: x represents one of three abc phases, i.e. x ═ a, b, c, VdcIs the sum of the DC voltages of two DC voltage sources
According to the above embodiment of the present invention, the driving signals of the switching devices of the bridge arms in each phase in the dual inverter are generated according to the preset switching state combination corresponding to each basic voltage vector, so as to apply control to the motor system, specifically:
region index R based on motor reference voltage vectorabcThe desired basic voltage vector is selected by table 1:
TABLE 1
The switching state combination corresponding to the preset basic voltage vector is obtained through table 2:
TABLE 2
To verify the effectiveness of the control method according to the embodiment of the present invention, experimental verification studies are performed on the experimental platform shown in fig. 5, the experimental parameters are shown in table 3, and the control period of the system is set to 0.0001 s.
TABLE 3
Fig. 6 shows experimental waveforms of the motor in steady-state operation with a speed band of 750rpm and a load of 3Nm, where the waveforms are, from top to bottom, the motor speed, the electromagnetic torque, the flux linkage amplitude and the a-phase stator current, and it can be seen that the motor operates smoothly, the torque and flux linkage amplitude have small pulsation, and the stator current is sinusoidal.
Fig. 7 shows a sudden change in the speed setting, where the speed setting is stepped from 500rpm to 1000rpm and the motor is running without load, it can be seen that the motor speed follows the speed setting within 0.65 s.
The present invention also provides an embodiment of a direct torque control device of an open-winding permanent magnet synchronous motor system, configured to perform a direct torque control method of the open-winding permanent magnet synchronous motor system, and fig. 8 is a schematic structural diagram of the direct torque control device of the open-winding permanent magnet synchronous motor system according to the embodiment of the present invention, where the direct torque control device includes:
the acquisition module 91 is used for acquiring three-phase stator current, line voltage and rotor position angle of the motor and differentiating the rotor position angle to obtain the rotating speed of the motor;
the first calculation module 92 is used for calculating a flux linkage vector of the motor according to the three-phase stator current and the line voltage and calculating a flux linkage given vector according to the rotor position angle;
the second calculating module 93 is used for calculating reference voltage vectors of the motor in an alpha-beta coordinate system and an a-b-c coordinate system respectively according to the flux linkage vector and the flux linkage given vector of the motor and a coordinate transformation principle;
the table look-up module 94 is used for calculating the area mark of the motor reference voltage vector according to the reference voltage vector of the motor in the a-b-c coordinate system and selecting the required basic voltage vector by simplifying a switch table;
and a driving signal generating module 95, configured to generate a driving signal of each phase bridge arm switching device in the dual inverter according to a preset switching state combination corresponding to each basic voltage vector, so as to control the motor system.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units may be a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.
The embodiments described above are presented to enable a person having ordinary skill in the art to make and use the invention. It will be readily apparent to those skilled in the art that various modifications to the above-described embodiments may be made, and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications to the present invention based on the disclosure of the present invention within the protection scope of the present invention.