阅读说明：本技术 一种直线同步电机参数的测量方法及系统 (Method and system for measuring parameters of linear synchronous motor ) 是由 梅文庆 廖武 文宇良 南永辉 石煜 于 2018-07-04 设计创作，主要内容包括：本发明公开了一种直线同步电机参数的测量方法及系统,与现有技术的参数测量方法相比,本申请利用直线同步电机的使用现场已有的矢量控制系统,两次调整其给定定子d轴电流,并对应获取PI控制器两次输出的电压。考虑到矢量控制系统中某些电力电子器件的非线性,为了消除非线性影响,本申请利用两次输出电压的差值进行电阻测量,从而计算出定子电阻。可见,本申请利用使用现场已有的矢量控制系统,无需设置额外的测量设备,节省了测量成本且容易实施；而且,本申请对定子d轴注入电流,对定子q轴未注入电流,从而将电机动子固定在d轴位置,应用性较强。(Compared with the parameter measuring method in the prior art, the method and the system have the advantages that the existing vector control system of the linear synchronous motor in the use field is utilized, the d-axis current of the given stator is adjusted twice, and the voltage output twice by the PI controller is correspondingly obtained. In order to eliminate the nonlinear influence by considering the nonlinearity of some power electronic devices in a vector control system, the stator resistance is calculated by measuring the resistance by using the difference value of two output voltages. Therefore, the method and the device have the advantages that the existing vector control system on the site is used, extra measuring equipment is not needed, measuring cost is saved, and the method and the device are easy to implement; in addition, current is injected into the d axis of the stator, and current is not injected into the q axis of the stator, so that the motor rotor is fixed at the position of the d axis, and the application is strong.)

1. A method for measuring parameters of a linear synchronous motor is characterized by comprising the following steps:

according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage u of the linear synchronous motor under the steady-state condition that current is injected into a stator d axis and current is not injected into a stator q axis_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

carrying out two different adjustments on a given stator d-axis current and a given stator q-axis current in a vector control system of a stator, so as to inject two different currents into the stator d-axis and inject no current into the stator q-axis, and correspondingly obtaining two output voltages of a proportional differential PI controller of the d-axis in the vector control system;

by using

2. The method of measuring parameters of a linear synchronous motor according to claim 1, further comprising:

according to the motor model, determining the rotor voltage u of the linear synchronous motor under the steady-state conditions of stator d-axis injection current, stator q-axis non-injection current and rotor injection current of the linear synchronous motor_f＝R_fi_fWherein u is_fIs a mover voltage, R_fIs a mover resistance, i_fIs a rotor current;

carrying out different adjustment twice on the current of a given rotor in a closed-loop control system of the rotor so as to inject different currents twice into the rotor and correspondingly obtain the voltage output twice by a proportional-derivative-integral (PID) controller in the closed-loop control system;

by using

3. The method of measuring parameters of a linear synchronous motor according to claim 1, further comprising:

after current is injected into a stator d shaft and a rotor of the linear synchronous motor, an inverter in the vector control system and an excitation device in a closed-loop control system of the rotor are closed, and the intermediate capacitor of the inverter is discharged until the voltage of the intermediate capacitor is zero;

starting the excitation device, injecting a ramp current rising with a preset slope into the rotor until the current reaches the rated current of the rotor, and then injecting a ramp current falling with the slope into the rotor until the current is zero;

repeatedly executing the steps of injecting a slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting a slope current falling with the slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

under the topology of the two-level inverter, the voltage is obtained according to a charging circuit of the intermediate capacitor when the ramp current rises or falls

under the topology of a three-level inverter, the charging circuit is obtained according to the rising or falling of the ramp current of the intermediate capacitorAnd use of the same

4. Such asMethod for measuring parameters of a linear synchronous motor according to claim 3, characterized in that after the voltage of the intermediate capacitor has stabilized, the stator d-axis voltage of the stator at the time of the voltage stabilization of the intermediate capacitor is determined from the motor model

when the stable voltage of the intermediate capacitor is smaller than a preset voltage, increasing the slope;

and repeatedly executing the steps of injecting a ramp current rising with an increased slope into the rotor until the rated current of the rotor is reached, and then injecting a ramp current falling with an increased slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stabilized again.

5. The method of measuring parameters of a linear synchronous motor according to claim 1, further comprising:

inputting u to space vector modulation link in the vector control system_d＝Asin(ω₁t) and u_q0, adding alternating voltage to the d axis of the stator to obtain the current of the d axis of the stator, wherein u_qIs stator q-axis voltage, where A is stator d-axis voltage amplitude, ω₁t is the d-axis voltage phase of the stator, and the rated frequency of the stator is less than omega₁< switching frequency of inverter in said vector control system x 0.5, t is time;

determining the d-axis current amplitude and the d-axis current phase according to the current of the d-axis of the stator, and determining the current phase according to the current amplitude and the current phaseCalculating stator d-axis inductance, where L_dIs stator d-axis inductance, θ_idFor the d-axis current phase, | i_dAnd | is the d-axis current amplitude.

6. The method for measuring parameters of a linear synchronous motor according to claim 5, wherein the specific process of determining the d-axis current amplitude and the d-axis current phase according to the current of the d-axis of the stator comprises the following steps:

and carrying out Fourier transform on the current of the d axis of the stator to obtain a d axis current amplitude and a d axis current phase.

7. The method of measuring parameters of a linear synchronous motor according to claim 5, further comprising:

injecting constant current into the d axis of the stator, and inputting u to the q axis voltage input end of the space vector modulation link_q＝Bsin(ω₂t) adding alternating voltage to the q axis of the stator to obtain the current of the q axis of the stator, wherein B is the voltage amplitude of the q axis of the stator, and omega is₂To a predetermined frequency, ω₂t is the stator q-axis voltage phase;

determining the q-axis current amplitude and the q-axis current phase according to the current of the q axis of the stator, and determining the q-axis current amplitude and the q-axis current phase according to the currentCalculating stator q-axis inductance, wherein L_qIs stator q-axis inductance, θ_iqFor the q-axis current phase, | i_qAnd | is the q-axis current amplitude.

8. The method for measuring parameters of a linear synchronous motor according to claim 7, wherein the specific process of determining the q-axis current amplitude and the q-axis current phase according to the current of the q-axis of the stator comprises the following steps:

and carrying out Fourier transform on the current of the q axis of the stator to obtain a q axis current amplitude and a q axis current phase.

9. A system for measuring parameters of a linear synchronous motor, comprising:

a first determining unit, configured to determine, according to a motor model of the linear synchronous motor in dq coordinate axes, that the linear synchronous motor injects current in a stator d axis and that the stator q axis is not injectedStator d-axis voltage u in steady-state condition of current_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

the current adjusting unit is used for carrying out two different adjustments on the d-axis current of a given stator and setting the q-axis current of the given stator to zero in a vector control system of the stator so as to inject two different currents into the d-axis of the stator and inject no current into the q-axis of the stator, and correspondingly obtaining the two output voltages of a proportional differential PI controller of the d-axis in the vector control system;

resistance calculation unit for using

10. The system for measuring parameters of a linear synchronous motor of claim 9, further comprising:

the capacitor discharging unit is used for closing an inverter in the vector control system and an excitation device in a closed-loop control system of the mover after injecting current into a stator d shaft and the mover of the linear synchronous motor, so that the middle capacitor of the inverter is discharged until the voltage of the middle capacitor is zero;

the current injection unit is used for starting the excitation device, injecting a slope current rising with a preset slope into the rotor until the current reaches the rated current of the rotor, and then injecting a slope current falling with the slope into the rotor until the current is zero;

the repeated injection unit is used for repeatedly executing the steps of injecting a slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting a slope current falling with the slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

second determinationA fixed unit for determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

a mutual inductance calculation unit for obtaining the charging circuit of the intermediate capacitor when the ramp current rises or falls under the topology of the two-level inverterAnd use of the same

Technical Field

The invention relates to the technical field of motor control, in particular to a method and a system for measuring parameters of a linear synchronous motor.

Background

At present, the linear synchronous motor has the advantages of low noise, high efficiency, quick response and the like, so that the linear synchronous motor is widely applied to various fields. Generally, a control system matched with the linear synchronous motor is further included in a use site of the linear synchronous motor. Referring to fig. 1, fig. 2 and fig. 3, fig. 1 is a schematic structural diagram of a vector control system of a stator of a linear synchronous motor in the prior art, fig. 2 is a schematic structural diagram of a closed-loop control system of a mover of a linear synchronous motor in the prior art, and fig. 3 is a circuit diagram of a connection circuit of an inverter and a stator of a motor in the prior art.

The control process of the vector control system of the stator comprises the following steps: 1) three-phase alternating current i to be input to stator_a、i_b、i_cConverting into two direct currents, i is stator d-axis current, according to coordinate conversion formula_dAnd stator q-axis current i_q(ii) a 2) Setting a given stator d-axis current of the statorAnd setting stator q-axis currentAnd i_d、i_qCorrespondingly making a difference, and correspondingly adjusting the two difference values by two PI (proportional-integral) controllers to respectively output voltages; 3) the inverter comprises a chopper device, an intermediate capacitor and a switch, and the voltage output by the two PI controllers is modulated by a space vector modulation algorithm to control the on-state of the switch in the inverter, so that the inverter can adjust the three-phase alternating current output to the three-phase windings a, b and c of the stator. The control process of the closed-loop control system of the rotor comprises the following steps: 1) setting a given mover current of a mover

And the mover current i_fMaking a difference, and regulating the output voltage of the difference value by a PID (proportional-integral-derivative) controller; 2) the voltage output by the PID controller is modulated by a carrier modulation algorithm and regulated by an excitation device in sequence to realize the input electric quantity of the rotorAnd (6) adjusting.

For the linear synchronous motor, the control system is crucial to control the stable operation of the linear synchronous motor, and the measurement of motor parameters cannot be avoided for the control of the linear synchronous motor. In the prior art, there are two commonly used methods for measuring motor parameters, the first method is to use an extra measuring device arranged on site to measure the motor parameters, such as a resistance measuring device for measuring the resistance of the stator, but the measuring cost of the method is high and the method is not easy to implement; second, a parameter measurement method of a rotating electrical machine is used for reference, namely, a motor parameter is measured in the rotating process of the rotating electrical machine, but the motor parameter can be measured only by operating a rotor of the linear synchronous motor for a long distance as the rotor of the linear synchronous motor does linear motion, and the method cannot be implemented in some practical applications.

Therefore, how to provide a solution to the above technical problem is a problem that needs to be solved by those skilled in the art.

Disclosure of Invention

The invention aims to provide a method and a system for measuring parameters of a linear synchronous motor, which utilize the existing vector control system on the use site, do not need to arrange additional measuring equipment, save the measuring cost and are easy to implement; in addition, current is injected into the d axis of the stator, and current is not injected into the q axis of the stator, so that the motor rotor is fixed at the position of the d axis, and the application is strong.

In order to solve the technical problem, the invention provides a method for measuring parameters of a linear synchronous motor, which comprises the following steps:

according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage u of the linear synchronous motor under the steady-state condition that current is injected into a stator d axis and current is not injected into a stator q axis_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

carrying out two different adjustments on a given stator d-axis current and a given stator q-axis current in a vector control system of a stator, so as to inject two different currents into the stator d-axis and inject no current into the stator q-axis, and correspondingly obtaining two output voltages of a proportional differential PI controller of the d-axis in the vector control system;

by usingCalculating the stator resistance, wherein u_d1、u_d2Voltage twice output for the PI controller i_d1、i_d2Given stator d-axis current for two adjustments.

Preferably, the measurement method further comprises:

according to the motor model, determining the rotor voltage u of the linear synchronous motor under the steady-state conditions of stator d-axis injection current, stator q-axis non-injection current and rotor injection current of the linear synchronous motor_f＝R_fi_fWherein u is_fIs a mover voltage, R_fIs a mover resistance, i_fIs a rotor current;

carrying out different adjustment twice on the current of a given rotor in a closed-loop control system of the rotor so as to inject different currents twice into the rotor and correspondingly obtain the voltage output twice by a proportional-derivative-integral (PID) controller in the closed-loop control system;

by usingCalculating a mover resistance, wherein u_f1、u_f2Voltage output twice for the PID controller, i_f1、i_f2Given the mover current for two adjustments.

Preferably, the measurement method further comprises:

after current is injected into a stator d shaft and a rotor of the linear synchronous motor, an inverter in the vector control system and an excitation device in a closed-loop control system of the rotor are closed, and the intermediate capacitor of the inverter is discharged until the voltage of the intermediate capacitor is zero;

starting the excitation device, injecting a ramp current rising with a preset slope into the rotor until the current reaches the rated current of the rotor, and then injecting a ramp current falling with the slope into the rotor until the current is zero;

repeatedly executing the steps of injecting a slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting a slope current falling with the slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

And obtaining the rising u of the slope current according to a preset coordinate transformation formula_a＝u_d、U when the ramp current decreases_a＝-u_d、

Wherein L is_mFor mutual inductance of mover to stator, u_aIs the voltage of the stator winding a, u_bIs the voltage of the stator winding b, u_cIs the voltage of the stator winding c;

under the topology of the two-level inverter, the voltage is obtained according to a charging circuit of the intermediate capacitor when the ramp current rises or falls

And use of the same

And voltage formula calculation of three-phase windings a, b and c of statorWherein u is_dcIs the voltage of the intermediate capacitor u_fwdFor conduction of anti-parallel diodes in switches of said two-level inverterThe pressure drop is reduced and the pressure drop,

k is the slope;

under the topology of a three-level inverter, the charging circuit is obtained according to the rising or falling of the ramp current of the intermediate capacitor

And use of the same

And voltage formula calculation of three-phase windings a, b and c of stator

And ufwd is the conduction voltage drop of an antiparallel diode in a switch of the three-level inverter.

Preferably, after the voltage of the intermediate capacitor is stabilized, the stator d-axis voltage of the stator at the time when the voltage of the intermediate capacitor is stabilized is determined according to the motor model

Previously, the measurement method further includes:

when the stable voltage of the intermediate capacitor is smaller than a preset voltage, increasing the slope;

and repeatedly executing the steps of injecting a ramp current rising with an increased slope into the rotor until the rated current of the rotor is reached, and then injecting a ramp current falling with an increased slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stabilized again.

Preferably, the measurement method further comprises:

inputting u to space vector modulation link in the vector control system_d＝Asin(ω₁t) and u_q0, adding alternating voltage to the d axis of the stator to obtain the current of the d axis of the stator, wherein u_qIs stator q-axis voltage, where A is stator d-axis voltage amplitude, ω₁t is the d-axis voltage phase of the stator, and the rated frequency of the stator is less than omega₁< switching frequency of inverter in said vector control system x 0.5, t is time;

determining the d-axis current amplitude and the d-axis current phase according to the current of the d-axis of the stator, and determining the current phase according to the current amplitude and the current phase

Calculating stator d-axis inductance, where L_dIs stator d-axis inductance, θ_idFor the d-axis current phase, | i_dAnd | is the d-axis current amplitude.

Preferably, the specific process of determining the d-axis current amplitude and the d-axis current phase according to the current of the d-axis of the stator is as follows:

and carrying out Fourier transform on the current of the d axis of the stator to obtain a d axis current amplitude and a d axis current phase.

Preferably, the measurement method further comprises:

injecting constant current into the d axis of the stator, and inputting u to the q axis voltage input end of the space vector modulation link_q＝B sin(ω₂t) adding alternating voltage to the q axis of the stator to obtain the current of the q axis of the stator, wherein B is the voltage amplitude of the q axis of the stator, and omega is₂To a predetermined frequency, ω₂t is the stator q-axis voltage phase;

determining the q-axis current amplitude and the q-axis current phase according to the current of the q axis of the stator, and determining the q-axis current amplitude and the q-axis current phase according to the current

Calculating stator q-axis inductance, wherein L_qIs stator q-axis inductance, θ_iqFor the q-axis current phase, | i_qAnd | is the q-axis current amplitude.

Preferably, the specific process of determining the q-axis current amplitude and the q-axis current phase according to the current of the q-axis of the stator is as follows:

and carrying out Fourier transform on the current of the q axis of the stator to obtain a q axis current amplitude and a q axis current phase.

In order to solve the above technical problem, the present invention provides a system for measuring parameters of a linear synchronous motor, comprising:

a first determining unit, configured to determine, according to a motor model of the linear synchronous motor in dq coordinate axes, a stator d-axis voltage u of the linear synchronous motor in a steady-state condition where a stator d-axis injection current and a stator q-axis non-injection current are injected into the linear synchronous motor_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

the current adjusting unit is used for carrying out two different adjustments on the d-axis current of a given stator and setting the q-axis current of the given stator to zero in a vector control system of the stator so as to inject two different currents into the d-axis of the stator and inject no current into the q-axis of the stator, and correspondingly obtaining the two output voltages of a proportional differential PI controller of the d-axis in the vector control system;

resistance calculation unit for using

Calculating the stator resistance, wherein u_d1、u_d2Voltage i output twice by the PI controller_d1、i_d2Given stator d-axis current for two adjustments.

Preferably, the measurement system further comprises:

the capacitor discharging unit is used for closing an inverter in the vector control system and an excitation device in a closed-loop control system of the mover after injecting current into a stator d shaft and the mover of the linear synchronous motor, so that the middle capacitor of the inverter is discharged until the voltage of the middle capacitor is zero;

the current injection unit is used for starting the excitation device, injecting a slope current rising with a preset slope into the rotor until the current reaches the rated current of the rotor, and then injecting a slope current falling with the slope into the rotor until the current is zero;

the repeated injection unit is used for repeatedly executing the steps of injecting a slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting a slope current falling with the slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

a second determination unit for determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

And obtaining the rising u of the slope current according to a preset coordinate transformation formula_a＝u_d、

U when the ramp current decreases_a＝-u_d、Wherein L is_mFor mutual inductance of mover to stator, u_aIs the voltage of the stator winding a, u_bIs the voltage of the stator winding b, u_cIs the voltage of the stator winding c;

a mutual inductance calculation unit for obtaining the charging circuit of the intermediate capacitor when the ramp current rises or falls under the topology of the two-level inverter

And use of the same

And voltage formula calculation of three-phase windings a, b and c of statorOr under the topology of a three-level inverter, the voltage is obtained according to a charging circuit of the intermediate capacitor when the ramp current rises or falls

And use of the same

And voltage formula calculation of three-phase windings a, b and c of stator

Wherein u is_dcIs the voltage of the intermediate capacitor u_fwdIs the conduction voltage drop of an anti-parallel diode in the switch of the two-level inverter,

k is the slope, u_fwd' is the conduction voltage drop of an anti-parallel diode in the switch of the three-level inverter.

The invention provides a method for measuring parameters of a linear synchronous motor, which comprises the following steps: according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage u of the linear synchronous motor under the steady-state condition that current is injected into a stator d axis and current is not injected into a stator q axis_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current; carrying out different adjustments twice on d-axis current of a given stator and setting zero on q-axis current of the given stator in a vector control system of the stator so as to inject different currents twice into the d-axis of the stator and not inject currents into the q-axis of the stator, and correspondingly obtaining the voltage output twice by a PI (proportional-integral) controller of the d-axis in the vector control system; by using

Calculating the stator resistance, wherein u_d1、u_d2Voltage twice output for the PI controller i_d1、i_d2Given stator d-axis current for two adjustments.

Compared with the parameter measurement method in the prior art, the method utilizes the existing vector control system of the linear synchronous motor in the use field to adjust the d-axis current of the given stator twice and correspondingly obtain the voltage output twice by the PI controller. In order to eliminate the nonlinear influence by considering the nonlinearity of some power electronic devices in a vector control system, the stator resistance is calculated by measuring the resistance by using the difference value of two output voltages. Therefore, the method and the device have the advantages that the existing vector control system on the site is used, extra measuring equipment is not needed, measuring cost is saved, and the method and the device are easy to implement; in addition, current is injected into the d axis of the stator, and current is not injected into the q axis of the stator, so that the motor rotor is fixed at the position of the d axis, and the application is strong.

The invention also provides a system for measuring the parameters of the linear synchronous motor, which has the same beneficial effects as the measuring method.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed in the prior art and the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a vector control system of a linear synchronous motor stator in the prior art;

fig. 2 is a schematic structural diagram of a closed-loop control system of a linear synchronous motor mover in the prior art;

fig. 3 is a circuit diagram of a prior art connection of an inverter to a stator of a motor;

FIG. 4 is a flow chart of a method for measuring parameters of a linear synchronous motor according to the present invention;

fig. 5(1) is an equivalent circuit diagram of the circuit diagram shown in fig. 3 at a ramp-up stage according to the present invention;

fig. 5(2) is an equivalent circuit diagram of the circuit diagram shown in fig. 3 at a ramp current falling stage according to the present invention;

FIG. 6 is a schematic diagram illustrating the identification of d-axis inductance of a stator according to the present invention;

FIG. 7 is a schematic diagram illustrating the identification of a stator q-axis inductance according to the present invention;

fig. 8 is a schematic structural diagram of a system for measuring parameters of a linear synchronous motor according to the present invention.

Detailed Description

The core of the invention is to provide a method and a system for measuring parameters of a linear synchronous motor, which utilize the existing vector control system on the use site, do not need to arrange additional measuring equipment, save the measuring cost and are easy to implement; in addition, current is injected into the d axis of the stator, and current is not injected into the q axis of the stator, so that the motor rotor is fixed at the position of the d axis, and the application is strong.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, 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 some, but not all, embodiments of the present invention. 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.

Referring to fig. 4, fig. 4 is a flowchart of a method for measuring parameters of a linear synchronous motor according to the present invention.

The measuring method comprises the following steps:

step S1: according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage u of the linear synchronous motor under the steady-state condition that current is injected into a stator d axis and current is not injected into a stator q axis_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

it should be noted that the preset in the present application is set in advance, and only needs to be set once, and the preset does not need to be reset unless modified according to actual conditions.

Specifically, the coordinate transformation process of the linear synchronous motor specifically includes:

1) in a known linear synchronous motor, three-phase windings a, b and c of a stator are supplied with three-phase balanced alternating currents i_a、i_b、i_cThen, a resultant magnetomotive force F is generated. The principle of the multi-phase motor model equivalence is as follows: under different coordinate systemsThe generated magnetomotive force is completely consistent. Considering the simplest two-phase motor model, two-phase balanced alternating currents i are applied to the two-phase windings alpha and beta which are perpendicular to each other_α、i_βThe resultant electromotive force F is also generated, i.e., the three-phase motor model is equivalent to a two-phase motor model, i.e., the transformation of the abc coordinate system into the α β coordinate system.

2) It is known to pass a two-phase alternating current i_α、i_βAnd two direct currents i are introduced_d、i_qWhen the two-phase motor of (2) rotates at a synchronous speed to generate an equal synthetic magnetomotive force F, the conversion from an alpha beta coordinate system to a dq coordinate system is realized.

The method and the device utilize the linear synchronous motor model under the dq coordinate axis to identify the parameters of each motor, and also complete parameter measurement. The principle of parameter identification is as follows: a set of parameter values is determined from the experimental data and the established model so that the numerical results calculated by the model can best fit the test data, thereby achieving prediction of the unknown process.

In dq coordinate axis, assuming that air gap magnetic fields are distributed according to a sine rule, neglecting the influence of corresponding space harmonic magnetic fields, magnetic circuit saturation, magnetic hysteresis and the like, the model of the linear synchronous motor is as follows:

voltage equation:

the flux linkage equation:

wherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs the d-axis current of the stator,

is stator d-axis magnetic field, omega_rThe frequency of the rotation angle of the rotor is,

for stator q-axis magnetic field, u_qIs stator q-axis voltage, i_qFor stator q-axis current, u_fIs a mover voltage, R_fIs a mover resistance, i_fIs a rotor current, and is a current,

is a mover magnetic field, L_dIs stator d-axis inductance, L_mFor mutual inductance of mover to stator, L_qIs stator q-axis inductance, L_fThe rotor is an excitation inductor.

Next, the stator resistance is identified: firstly, according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage of the linear synchronous motor under the steady state condition that direct current is injected into a stator d axis and direct current is not injected into a stator q axis, and fixing a magnetic field under the steady state condition, so that the linear synchronous motor is stable

Since the d-axis of the stator is injected with DC current and the q-axis of the stator is not injected with DC current, the stator can fix the position of the mover, even if the mover is injected with DC current, the mover will not move because the magnetic field of the traveling wave will not move in a steady state, so omega_r0, thereby determining stator d-axis voltage u_d＝R_si_d。

Step S2: carrying out different adjustments twice on a given stator d-axis current and setting a given stator q-axis current to zero in a vector control system of a stator so as to inject different currents twice into a stator d-axis and inject no current into a stator q-axis, and correspondingly obtaining voltages output twice by a proportional differential PI controller of the d-axis in the vector control system;

specifically, as can be seen from fig. 1, when a given current of the vector control system of the stator changes, the output voltage of its corresponding PI controller changes accordingly. In the method, although an error exists between the given current of the stator and the actual current of the stator, the error is small, and an error also exists between the voltage output by the PI controller and the actual voltage of the stator, but the error is small, so that the method takes the given stator d-axis current as the stator d-axis current i_dThe voltage output by the PI controller for controlling the d-axis current of the stator is used as the d-axis voltage u of the stator_d。

Considering the nonlinearity of power electronic devices in an inverter in a vector control system, the voltage output by the inverter has deviation from the actual voltage, so that the current of a given stator d-axis of the vector control system is adjusted differently twice, and different currents are injected into the stator d-axis twice; and the q-axis current of the given stator is set to be zero, so that no current is injected into the q-axis of the stator, and the voltage output twice by the PI controller of the d-axis is correspondingly obtained, so that the stator resistance identification is conveniently carried out by utilizing the difference value of the voltage output twice, and the nonlinear influence of a power electronic device is eliminated.

Step S3: by usingCalculating the stator resistance, wherein u_d1、u_d2Voltage twice output for PI controller, i_d1、i_d2Given stator d-axis current for two adjustments.

Specifically, after the d-axis current of the stator is given to be adjusted to a steady state twice, the voltage output twice by the PI controller of the d-axis is: u. of_d1＝R_si_d1、u_d2＝R_si_d2Therefore, use is made ofAnd the stator resistance is calculated, so that the influence of nonlinearity of the power electronic device is eliminated. The invention provides a method for measuring parameters of a linear synchronous motor, which comprises the following steps: according to a motor model of the linear synchronous motor in dq coordinate axis, determining stator d-axis voltage u of the linear synchronous motor under the steady-state condition that current is injected into a stator d axis and current is not injected into a stator q axis_d＝R_si_d(ii) a Carrying out different adjustments twice on d-axis current of a given stator and setting zero on q-axis current of the given stator in a vector control system of the stator so as to inject different currents twice into the d-axis of the stator and not inject currents into the q-axis of the stator, and correspondingly obtaining the voltage output twice by a PI (proportional-integral) controller of the d-axis in the vector control system; by using

The stator resistance is calculated.

Compared with the parameter measurement method in the prior art, the method utilizes the existing vector control system of the linear synchronous motor in the use field to adjust the d-axis current of the given stator twice and correspondingly obtain the voltage output twice by the PI controller. In order to eliminate the nonlinear influence by considering the nonlinearity of some power electronic devices in a vector control system, the stator resistance is calculated by measuring the resistance by using the difference value of two output voltages. Therefore, the method and the device have the advantages that the existing vector control system on the site is used, extra measuring equipment is not needed, measuring cost is saved, and the method and the device are easy to implement; in addition, current is injected into the d axis of the stator, and current is not injected into the q axis of the stator, so that the motor rotor is fixed at the position of the d axis, and the application is strong.

On the basis of the above-described embodiment:

as a preferred embodiment, the measuring method further includes:

according to the motor model, determining the rotor voltage u of the linear synchronous motor under the steady-state conditions of the stator d-axis injection current, the stator q-axis non-injection current and the rotor injection current of the linear synchronous motor_f＝R_fi_fWherein u is_fIs a mover voltage, R_fIs a mover resistance, i_fIs a rotor current;

carrying out different adjustment twice on the current of a given rotor in a closed-loop control system of the rotor so as to inject different currents twice into the rotor and correspondingly obtain the voltage output twice by a proportional-derivative-integral (PID) controller in the closed-loop control system;

by using

Calculating a mover resistance, wherein u_f1、u_f2Voltage, i, output twice for PID controller_f1、i_f2Given the mover current for two adjustments.

Similarly, identifying the mover resistance: firstly, according to a motor model of the linear synchronous motor in dq coordinate axes, determining the rotor voltage of the linear synchronous motor under the steady state condition that direct current is injected into a stator d axis, direct current is not injected into a stator q axis and direct current is injected into the rotor, and fixing the magnetic field under the steady state condition

Thereby determining the mover voltage u_f＝R_fi_f。

As can be seen from fig. 2, when a given mover current of the closed loop control system of the mover changes, the output voltage of the PID controller also changes accordingly. In the present application, the given mover current is used as the mover current i in consideration of the fact that the error between the given mover current and the actual mover current is small, but the error is small, and the error between the voltage output by the PID controller and the actual mover voltage is small_fThe voltage output by the PID controller is used as a rotor voltage u_f。

In addition, the excitation device in the closed-loop control system comprises a nonlinear power electronic device, so that the voltage output by the excitation device is deviated from the actual voltage, therefore, under the condition that direct current is injected into a stator d axis and direct current is not injected into a stator q axis, the current of a given rotor in the closed-loop control system of the rotor is adjusted differently twice, so that different currents are injected into the rotor twice, the voltage output twice by the PID controller is correspondingly obtained, the rotor resistance identification is conveniently carried out by utilizing the difference of the voltage output twice, and the influence of the nonlinearity of the power electronic device is eliminated.

After the given rotor current is adjusted to the stable state twice, the voltage output twice by the PID controller is as follows: u. of_f1＝R_fi_f1、u_f2＝R_fi_f2Therefore, use is made ofAnd the rotor resistance is calculated, and the influence of nonlinearity of the power electronic device is eliminated. As a preferred embodiment, the measuring method further includes:

after the current is injected into a stator d shaft and a rotor of the linear synchronous motor, an inverter in a vector control system and an excitation device in a closed-loop control system of the rotor are closed, and the intermediate capacitor of the inverter is discharged until the voltage of the intermediate capacitor is zero;

starting an excitation device, injecting a slope current rising with a preset slope into the rotor until the current reaches the rated current of the rotor, and then injecting a slope current falling with the slope into the rotor until the current is zero;

repeatedly executing the steps of injecting a slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting a slope current falling with a slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

And obtaining the rising u of the slope current according to a preset coordinate transformation formula_a＝u_d、

U when ramp current decreases_a＝-u_d、

Wherein L is_mFor mutual inductance of mover to stator, u_aIs the voltage of the stator winding a, u_bIs the voltage of the stator winding b, u_cIs the voltage of the stator winding c;

under the topology of a two-level inverter, the power supply is obtained according to a charging circuit of an intermediate capacitor when the ramp current rises or falls

And useAnd voltage formula calculation of three-phase windings a, b and c of stator

Wherein u is_dcIs the voltage of the intermediate capacitor u_fwdIs the conduction voltage drop of an anti-parallel diode in a switch of the two-level inverter,

k is the slope;

under the topology of a three-level inverter, the three-level inverter is obtained according to a charging circuit of an intermediate capacitor when the ramp current rises or falls

And use

And voltage formula calculation of three-phase windings a, b and c of statorWherein u is_fwd' is the conduction voltage drop of an anti-parallel diode in a switch of the three-level inverter.

Specifically, identification of mutual inductance of the mover to the stator: 1) injecting direct current into a rotor of the linear synchronous motor, injecting direct current into a stator d axis, and not injecting current into a stator q axis, so that the rotor is kept at a d axis position; 2) closing an inverter in a vector control system and an excitation device in a closed-loop control system, discharging an intermediate capacitor until the voltage of the intermediate capacitor is zero by a chopper device at the direct current side of the inverter, and forcibly blocking pulse output of a three-phase semiconductor switching device of the inverter; 3) starting an excitation device, injecting a slope current rising with a certain slope into a motor rotor until a rated current of the motor rotor is reached, injecting a slope current falling with a certain slope into the motor rotor until the current is zero, controlling the slope current of the motor rotor to rise with a certain slope, and repeatedly executing the process that the slope current rises to the rated current and falls to the current until the voltage of an intermediate capacitor of the inverter is stable, wherein the rising slope is equal to the falling slope; 4) and calculating the mutual inductance of the rotor to the stator according to the stable voltage value of the intermediate capacitor.

And (3) analysis of a calculation process: because the mover is at the d-axis position, the mover does not move, and the excitation direction is always in the d-axis direction, the voltage induced on the stator is always on the d-axis, no current exists on the q-axis, and the stator voltage can be expressed as:

u_q＝0

since the mover does not move, the electromotive forces induced on the d-axis are all transformer electromotive forces, which can be expressed as:

when the stator windings a, b, c induce the transformer electromotive force, if the voltage on the intermediate capacitor is zero, the stator windings a, b, c will charge the intermediate capacitor, when the voltage of the intermediate capacitor reaches the steady state, the stator current becomes zero, the terminal voltage of the stator windings is equal to the transformer electromotive force, that is:

voltage u of stator winding a_aStatorVoltage u of winding b_bVoltage u of stator winding c_cAnd u_dThe relationship of (1): according to a coordinate transformation formula

Due to u_qWhen the ramp current rises, 0 and θ is 0, the following results are obtained:

u_a＝u_d

during the ramp current drop, it is possible to obtain:

u_a＝-u_d

referring to fig. 5(1) and fig. 5(2), fig. 5(1) is an equivalent circuit diagram of the circuit diagram shown in fig. 3 at the ramp current rising stage according to the present invention; fig. 5(2) is an equivalent circuit diagram of the circuit diagram shown in fig. 3 at the ramp current falling stage according to the present invention.

Equivalent circuit and u according to ramp current rising stage and ramp current falling stage_a、u_b、u_cAnd u_dIn parallel with the relationship (c), the on-state voltage drop of the antiparallel diode in the switch of the inverter (the inverter in fig. 3 is a two-level inverter) is set to u_fwdThereby obtaining the voltage u of the intermediate capacitor_dcRelation with stator winding phase voltage:it is known that

k is the slope of the ramp current, and the mutual inductance of the rotor to the stator at the ramp current rising stage is obtained:

if the inverter is a three-level inverter, the equivalent circuit u and u are increased or decreased according to the ramp current_a、u_b、u_cAnd u_dAnd the conduction voltage drop of the antiparallel diode in the switch of the three-level inverter is set as u_fwd', thereby obtaining the voltage u of the intermediate capacitor_dcRelation with stator winding phase voltage:

and further obtaining the mutual inductance of the rotor to the stator at the ramp current reduction stage:

as a preferred embodiment, after the voltage of the intermediate capacitor is stabilized, the stator d-axis voltage of the stator at the time of the voltage stabilization of the intermediate capacitor is determined according to the motor model

Previously, the measurement method further includes:

when the stable voltage of the intermediate capacitor is smaller than the preset voltage, increasing the slope;

and repeatedly executing the steps of injecting the slope current rising with the increased slope into the rotor until the rated current of the rotor is reached, and then injecting the slope current falling with the increased slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stabilized again.

Further, considering that mutual inductance calculation is not easy to perform and calculation is not accurate enough when the voltage value of the intermediate capacitor after being stabilized is too small, the stable voltage of the intermediate capacitor is compared with the preset voltage, when the stable voltage of the intermediate capacitor is smaller than the set voltage, the stable voltage is proved to be too small, the slope of the set slope current is increased, the process that the slope current rises to the rated current with the increased slope and falls to zero with the increased slope is repeatedly performed until the voltage of the intermediate capacitor of the inverter is stabilized again, and therefore the accuracy of calculating mutual inductance is improved.

As a preferred embodiment, the measuring method further includes:

for space vector modulation link input u in vector control system_d＝Asin(ω₁t) and u_q0, adding alternating voltage to the d axis of the stator to obtain the current of the d axis of the stator, wherein u_qIs stator q-axis voltage, where A is stator d-axis voltage amplitude, ω₁t is the d-axis voltage phase of the stator, and the rated frequency of the stator is less than omega₁The switching frequency of an inverter in the vector control system is multiplied by 0.5, and t is time;

determining the current amplitude and phase of the d-axis current according to the current of the d-axis of the stator

Calculating stator d-axis inductance, where L_dIs stator d-axis inductance, θ_idFor d-axis current phase, | i_dAnd | is the d-axis current amplitude.

Specifically, referring to fig. 6, fig. 6 is a schematic diagram illustrating an identification of a stator d-axis inductance according to the present invention. Identification of stator d-axis inductance: 1) for space vector modulation link input u in vector control system_d＝Asin(ω₁t) and u_qAdding an alternating voltage signal with the frequency larger than the rated frequency of the stator and less than 0.5 times of the switching frequency of the inverter to the d axis of the stator so as to detect the current of the d axis of the stator; 2) determining d-axis current amplitude | i according to current of d-axis of stator_dI and D-axis current phase θ_idAccording toAnd calculating the d-axis inductance of the stator.

In addition, analysis: in the stator static state, the stator d-axis voltage can be expressed as:

therefore, the magnitude of the d-axis current of the stator is related to the d-axis inductance and the stator resistance of the stator, the alternating voltage with certain frequency is added to the d axis, the current with corresponding frequency can appear in the stator winding, when the stator resistance is known, the magnitude of the d-axis inductance of the stator can be judged according to the magnitude of the d-axis current of the stator, namely, the magnitude of the d-axis inductance of the stator and the stator resistance are in a relational expression

As a preferred embodiment, the specific process of determining the d-axis current amplitude and the d-axis current phase according to the current of the d-axis of the stator is as follows:

and performing Fourier transform on the current of the d axis of the stator to obtain the current amplitude of the d axis and the current phase of the d axis.

Further, according to the method and the device, the current of the d axis of the stator is subjected to Fourier transform, and the current amplitude of the d axis and the current phase of the d axis are obtained.

As a preferred embodiment, the measuring method further includes:

constant current is injected into a d axis of the stator, and u is input to a q axis voltage input end of a space vector modulation link_q＝Bsin(ω₂t) adding alternating current voltage to a q axis of the stator to obtain the current of the q axis of the stator, wherein B is the voltage amplitude of the q axis of the stator, and omega₂To a predetermined frequency, ω₂t is the stator q-axis voltage phase;

determining the q-axis current amplitude and the q-axis current phase according to the current of the q-axis of the stator, and determining the q-axis current amplitude and the q-axis current phase according to the current

Calculating stator q-axis inductance, wherein L_qIs stator q-axis inductance, θ_iqFor q-axis current phase, (+)i_qAnd | is the q-axis current amplitude.

Similarly, referring to fig. 7, fig. 7 is a schematic diagram illustrating an identification of a stator q-axis inductance according to the present invention. Identification of stator q-axis inductance: 1) constant current is injected into a d axis of the stator, and u is input to a q axis voltage input end of a space vector modulation link_q＝Bsin(ω₂t) to add an alternating voltage signal of a certain frequency to the q axis of the stator so as to detect the current of the q axis of the stator, wherein, omega₂The frequency can also be larger than the rated frequency of the stator and smaller than 0.5 time of the switching frequency of the inverter, and is selected according to the actual situation; 2) determining a q-axis current amplitude i according to a current of a q-axis of a stator_qI and q axis current phase θ_iqAccording to

And calculating the q-axis inductance of the stator.

In addition, analysis: in the stator static state, the stator q-axis voltage can be expressed as:

therefore, the magnitude of the q-axis current of the stator is related to the q-axis inductance and the stator resistance of the stator, alternating voltage with certain frequency is added to the q axis, current with corresponding frequency can appear in a stator winding, when the stator resistance is known, the magnitude of the q-axis inductance of the stator can be judged through the magnitude of the q-axis current of the stator, namely, the two relational expressions

As a preferred embodiment, the specific process of determining the q-axis current amplitude and the q-axis current phase according to the current of the q-axis of the stator is as follows:

and performing Fourier transform on the current of the q axis of the stator to obtain the current amplitude of the q axis and the current phase of the q axis.

Similarly, the q-axis current amplitude and the q-axis current phase are obtained by performing Fourier transform on the current of the q-axis of the stator.

Referring to fig. 8, fig. 8 is a schematic structural diagram of a system for measuring parameters of a linear synchronous motor according to the present invention.

The measurement system includes:

a first determining unit 1, configured to determine, according to a motor model of the linear synchronous motor in dq coordinate axes, a stator d-axis voltage u of the linear synchronous motor under a steady-state condition that a stator d-axis injection current and a stator q-axis non-injection current of the linear synchronous motor are injected_d＝R_si_dWherein u is_dIs stator d-axis voltage, R_sIs stator resistance, i_dIs stator d-axis current;

the current adjusting unit 2 is used for performing two different adjustments on the d-axis current of a given stator and setting the q-axis current of the given stator to zero in the vector control system of the stator so as to inject two different currents into the d-axis of the stator and inject no current into the q-axis of the stator, and correspondingly acquiring the voltage output by the proportional derivative PI controller of the d-axis in the vector control system twice;

resistance calculation unit 3 for utilizing

Calculating the stator resistance, wherein u_d1、u_d2Voltage twice output for PI controller, i_d1、i_d2Given stator d-axis current for two adjustments.

As a preferred embodiment, the measuring system further comprises:

the capacitor discharging unit is used for closing an inverter in a vector control system and an excitation device in a closed-loop control system of the rotor after injecting current into a stator d shaft and the rotor of the linear synchronous motor, so that the middle capacitor of the inverter is discharged until the voltage of the middle capacitor is zero;

the current injection unit is used for starting the excitation device, injecting slope current rising with a preset slope into the rotor until the rated current of the rotor is reached, and then injecting slope current falling with the slope into the rotor until the current is zero;

the repeated injection unit is used for repeatedly executing the steps of injecting the slope current rising with the preset slope into the rotor until the rated current of the rotor is reached, and then injecting the slope current falling with the slope into the rotor until the current is zero until the voltage of the intermediate capacitor is stable;

a second determination unit for determining the stator d-axis voltage of the stator when the voltage of the intermediate capacitor is stable according to the motor model

And obtaining the rising u of the slope current according to a preset coordinate transformation formula_a＝u_d、

U when ramp current decreases_a＝-u_d、

Wherein L is_mFor mutual inductance of mover to stator, u_aIs the voltage of the stator winding a, u_bIs the voltage of the stator winding b, u_cIs the voltage of the stator winding c;

a mutual inductance calculation unit for obtaining the charging circuit of the intermediate capacitor during the ramp current rising or falling under the topology of the two-level inverter

And use

And voltage formula calculation of three-phase windings a, b and c of statorOr under the topology of a three-level inverter, the voltage is obtained according to a charging circuit of the intermediate capacitor when the ramp current rises or falls

And useAnd voltage formula calculation of three-phase windings a, b and c of statorWherein u is_dcIs the voltage of the intermediate capacitor u_fwdIs the conduction voltage drop of an anti-parallel diode in a switch of the two-level inverter,k is the slope, u_fwd' is the conduction voltage drop of an anti-parallel diode in a switch of the three-level inverter.

For the introduction of the system provided in the present application, reference is made to the method embodiment, which is not described herein again.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.