A segmented straight-line induction motor speed observation method based on compound reaching law

Abstract

This invention provides a method for speed observation of a piecewise linear induction motor based on a composite reaching law, belonging to the field of motor control technology. The method includes: constructing an equivalent mathematical model based on vector superposition using a unit motor mathematical model of the piecewise linear induction motor; constructing a linear sliding surface and building a composite reaching law based on system state variables and adaptive terminal sliding mode adjustment coefficients; constructing a sliding mode observer based on the composite reaching law using the equivalent mathematical model and the composite reaching law to obtain back electromotive force (EMF) observation values; inputting the back EMF observation values ​​into a phase-locked loop (PLL) to extract synchronous angular velocity estimates and synchronous electrical angle estimates, thereby calculating secondary velocity estimates and secondary displacement estimates. This invention suppresses sliding mode chattering through the composite reaching law, improves the accuracy of back EMF observation, and thus enhances the accuracy of secondary velocity and position observations. It has advantages such as fast dynamic response and simple implementation.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and more specifically, relates to a method for observing the speed of a piecewise linear induction motor based on a composite reaching law. Background Technology

[0002] Long Primary Double-Sided Linear Induction Motors (LP-DSLIMs) offer advantages such as high thrust-to-weight ratio and no need for secondary power supply, making them particularly suitable for applications requiring short-duration, high-acceleration operation. However, because the secondary winding of an LP-DSLIM is shorter than its primary winding, it suffers from issues such as high leakage inductance and low voltage utilization. To address these problems, in practical applications, the long primary winding is typically divided into several segments, and multiple inverters are connected in parallel for power supply.

[0003] During the operation of segmented LP-DSLIM, secondary speed is a crucial parameter reflecting the system's operating status and propulsion performance. Especially under short-duration high acceleration and high dynamic operating conditions, speed information can not only characterize motor operating characteristics and propulsion effects but also provide a basis for system performance testing, operating status analysis, and subsequent operational strategy optimization. Therefore, achieving accurate observation of the secondary speed of segmented LP-DSLIM is of great significance.

[0004] Currently, commonly used velocity observation methods mainly include flux linkage observers, Kalman filters, sliding mode observers, and model reference adaptive methods. However, most of these methods are designed for traditional steady-state or slowly variable-speed systems. Under the high-dynamic operating conditions of segmented LP-DSLIM, they still suffer from problems such as large back EMF observation chattering, insufficient observation convergence speed, and the resulting decrease in velocity observation accuracy, making it difficult to meet the requirements for speed and accuracy of velocity information under high-speed operating conditions. Therefore, it is urgent to propose a velocity observation method suitable for the high-dynamic operating conditions of segmented LP-DSLIM. Summary of the Invention

[0005] The purpose of this invention is to provide a segmented linear induction motor speed observation method based on a composite reaching law, which solves the problems of large back EMF chattering, slow observation convergence speed, and low speed observation accuracy of existing observation methods under the short-time high acceleration operation condition of segmented LP-DSLIM.

[0006] To achieve the above objectives, this invention provides a method for observing the speed of a piecewise linear induction motor based on a composite reaching law, the method comprising:

[0007] Step S1: Based on the unit motor mathematical model of the piecewise linear induction motor, construct an equivalent mathematical model based on vector superposition.

[0008] Step S2: Construct a linear sliding surface and build a composite reaching law based on the system state variables and the adaptive terminal sliding adjustment coefficient;

[0009] Step S3: Based on the equivalent mathematical model and the composite reaching law, construct a sliding mode observer based on the composite reaching law to observe the back electromotive force of the motor secondary to obtain the observed value of the back electromotive force.

[0010] Step S4: Input the back EMF observation value into the phase-locked loop, extract the synchronous angular velocity estimate and the synchronous electrical angle estimate, and calculate the secondary velocity estimate and the secondary displacement estimate.

[0011] The beneficial effects of this invention are as follows:

[0012] Compared to traditional sliding mode observation methods, this invention introduces a composite reaching law, which can effectively suppress sliding mode chattering while ensuring a faster convergence speed, improve the accuracy of back EMF observation, and thus improve the speed observation performance of the system under high dynamic operating conditions. Attached Figure Description

[0013] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0014] Figure 1 This is a flowchart of the segmented linear induction motor speed observation method based on the composite reaching law provided in the embodiments of the present invention;

[0015] Figure 2 This is a block diagram of the sliding mode observer based on the composite reaching law provided by the present invention;

[0016] Figure 3 This is a diagram showing the back electromotive force observation results provided by the composite reaching law sliding mode observer provided by the present invention;

[0017] Figure 4 This is a graph showing the velocity observation results based on the composite reaching law sliding mode observer provided by the present invention;

[0018] Figure 5 This is a diagram showing the displacement observation results based on the composite reaching law sliding mode observer provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. To achieve the above objectives, this invention adopts the following technical solution.

[0020] Figure 1 This is a flowchart of the segmented linear induction motor speed observation method based on the composite reaching law provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the method includes:

[0021] Step S1: Based on the unit motor mathematical model of the piecewise linear induction motor, construct an equivalent mathematical model based on vector superposition.

[0022] Step S2: Construct a linear sliding surface and build a composite reaching law based on the system state variables and the adaptive terminal sliding adjustment coefficient;

[0023] Step S3: Based on the equivalent mathematical model and the composite reaching law, construct a sliding mode observer based on the composite reaching law to observe the back electromotive force of the motor secondary in order to obtain the observed value of the back electromotive force.

[0024] Step S4: Input the back electromotive force observation value into the phase-locked loop (PLL) to extract the synchronous angular velocity estimate and the synchronous electrical angle estimate, so as to calculate the secondary velocity estimate and the secondary displacement estimate.

[0025] In step S1, the mathematical model of the segmented linear induction motor as a unit motor in the stationary coordinate system is as follows:

[0026] ;

[0027] in, For the first The primary voltage vector of each unit motor For the first The flux linkage vector of each unit motor, For the first Virtual secondary voltage vector of each unit motor For the first Virtual secondary flux linkage vector of each unit motor For the first The actual secondary flux linkage vector of each unit motor For secondary mechanical angular velocity, For the first The proportional coefficient for coupling between the primary and secondary windings of the motor. For primary resistors, For secondary resistors, This is a primary form of self-perception. For secondary self-induction, For differential operators, For the first The primary current vector of each unit motor For the first The secondary current vector of each unit motor This refers to the unit motor serial number. This is primary mutual induction.

[0028] Considering In a piecewise linear induction motor system where the secondary winding is simultaneously coupled to n unit motors, assuming the set of unit motors coupled to the secondary winding is (the following is a list of unit motors coupled to the secondary winding at any given time),... For the primary and secondary voltages, currents, and flux linkages of n individually powered unit motors, the vector superposition method is used to calculate the vector parameters of the coupled system, and its expression is:

[0029] ;

[0030] in, For the primary voltage vector sum, For the primary current vector sum, Divide into primary magnetic flux vectors and, For the vector sum of secondary currents, For the sum of virtual secondary flux linkage vectors, It is an integer from 1 to n, where n is the number of unit motors.

[0031] The equivalent mathematical model of a piecewise linear induction motor is:

[0032] ;

[0033] in, For primary length, This is the secondary length.

[0034] The state equation of the equivalent mathematical model in the stationary coordinate system is:

[0035] ;

[0036] in, , , , , It is the back electromotive force. This is the secondary time constant.

[0037] Figure 2 This is a block diagram of the sliding mode observer based on the composite reaching law provided by the present invention, as follows: Figure 2As shown, the primary current vector of the segmented long primary double-sided linear induction motor (LP-DSLIM) is obtained. and primary current observations obtained based on equivalent mathematical models Then, the back electromotive force observation is obtained by combining the linear sliding surface and the composite reaching law. Below is Figure 2 To elaborate further.

[0038] In step S2, the expression for the linear sliding surface is:

[0039] ;

[0040] Where s is the linear sliding surface of the sliding mode observer. For current error, , For the primary current vector sum, These are primary current observations. is the linear sliding surface gain matrix.

[0041] In step S2, a convergence law is constructed based on the system state variables, adaptive gain adjustment coefficient, sliding mode approach velocity coefficient, terminal attraction coefficient, terminal attraction power parameter, and exponential decay coefficient.

[0042] In step S2, the expression for the composite reaching law is as follows:

[0043] ;

[0044] in, The derivative of the linear sliding surface s, For system state variables, The adaptive gain adjustment coefficient and , The sliding mode approach velocity coefficient, This is the terminal attraction coefficient. and To attract power-law parameters to the terminal and , and All are odd numbers. The exponential decay coefficient is... , where e is the natural constant.

[0045] The expression for the sliding mode observer based on the composite reaching law is:

[0046] ;

[0047] in, It is a linear sliding mode control law. For the primary voltage vector sum, For differential operators, , , , , For primary resistors, This is a primary form of self-perception. For primary mutual induction, For secondary self-induction, For secondary length, denoted as the primary length, and n as the number of unit motors.

[0048] Differentiating the expression for the linear sliding surface, and based on the expression for the sliding observer and the state equation of the equivalent mathematical model in the stationary coordinate system, combined with the composite reaching law, we obtain the following intermediate expression:

[0049] ;

[0050] in, It is the back electromotive force.

[0051] When the current error approaches 0, the observed values ​​of the sliding mode control law and the back electromotive force are equal, and its expression is:

[0052] ;

[0053] in, This is the observed value of the back electromotive force.

[0054] Combining the intermediate expression, the sliding mode control law of the sliding mode observer based on the composite reaching law is constructed as follows:

[0055] .

[0056] In step S4, the back electromotive force observation is input into the phase-locked loop (PLL), and the calculation expressions for the synchronous angular velocity estimate and the synchronous electrical angle estimate are as follows:

[0057] ;

[0058] in, For angular error, This is an estimate of the synchronous angular velocity. This is an estimated value for the synchronous electrical angle. and The back electromotive force in the stationary coordinate system are respectively shaft and Components on the axis, The magnitude of the observed back electromotive force. and t represents the proportional and integral coefficients of the PI controller, and t represents time.

[0059] Step S4 further includes: calculating the secondary speed estimate based on the synchronous angular velocity estimate, slip frequency, and motor pole pitch; and calculating the secondary displacement estimate based on the secondary speed estimate. The slip frequency is calculated based on the primary current d-axis reference value, the primary current q-axis reference value, the secondary resistance, and the secondary self-inductance. The specific calculation formula is as follows:

[0060] ;

[0061] in, The secondary speed estimate for the segmented long primary double-sided linear induction motor LP-DSLIM is given. The estimated secondary displacement values ​​are for the segmented long primary double-sided linear induction motor LP-DSLIM. The slip angular frequency, The pole pitch of the motor. This is the primary current d-axis reference value. This is the q-axis reference value for the primary current.

[0062] Figure 3 This is a diagram showing the back electromotive force observation results based on the composite reaching law sliding mode observer provided by the present invention. Figure 3 The simulation results of the back electromotive force observation values ​​in the two-phase stationary coordinate system obtained by the technical solution of the present invention can be obtained.

[0063] Figure 4 This is a velocity observation result diagram based on the composite reaching law sliding mode observer provided by the present invention. Figure 4 The speed estimate obtained by the technical solution of this invention can be obtained ( Figure 4 The figure shows the results of a simulation comparison between the observed velocity and the actual velocity.

[0064] Figure 5 This is a displacement observation result diagram based on the composite reaching law sliding mode observer provided by the present invention. Figure 5 The displacement estimate obtained by the invention can be obtained ( Figure 5 The figure shows the simulation results comparing the observed displacement with the actual displacement.

[0065] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention.

[0066] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not describe the various possible combinations separately.

[0067] Furthermore, various different implementations of the present invention can be combined arbitrarily, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed in the present invention.

Claims

1. A method for observing the speed of a piecewise linear induction motor based on a composite reaching law, characterized in that, The method includes: Step S1: Based on the unit motor mathematical model of the piecewise linear induction motor, construct an equivalent mathematical model based on vector superposition. Step S2: Construct a linear sliding surface and build a composite reaching law based on the system state variables and the adaptive terminal sliding adjustment coefficient; Step S3: Based on the equivalent mathematical model and the composite reaching law, construct a sliding mode observer based on the composite reaching law to observe the back electromotive force of the motor secondary to obtain the observed value of the back electromotive force. Step S4: Input the back EMF observation value into the phase-locked loop, extract the synchronous angular velocity estimate and the synchronous electrical angle estimate, and calculate the secondary velocity estimate and the secondary displacement estimate.

2. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 1, characterized in that, In step S2, the expression for the linear sliding surface is: ； Where s is the linear sliding surface of the sliding mode observer. For current error, , For the primary current vector sum, These are primary current observations. is the gain matrix of the linear sliding surface.

3. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 2, characterized in that, In step S2, a convergence law is constructed based on the system state variables, adaptive gain adjustment coefficient, sliding mode approach velocity coefficient, terminal attraction coefficient, terminal attraction power parameter, and exponential decay coefficient.

4. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 3, characterized in that, In step S2, the expression for the composite reaching law is as follows: ； in, The derivative of the linear sliding surface s, For system state variables, The adaptive gain adjustment coefficient and , The sliding mode approach velocity coefficient, This is the terminal attraction coefficient. and To attract power-law parameters to the terminal and , and All are odd numbers. The exponential decay coefficient is... , where e is the natural constant.

5. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 4, characterized in that, The expression for the sliding mode observer based on the composite reaching law is: ； in, It is a linear sliding mode control law. For the primary voltage vector sum, For differential operators, , , , , For primary resistors, This is a primary form of self-perception. For primary mutual induction, For secondary self-induction, For secondary length, denoted as the primary length, and n as the number of unit motors.

6. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 5, characterized in that, Differentiating the expression for the linear sliding surface, and based on the sliding observer expression and the state equation of the equivalent mathematical model in the stationary coordinate system, combined with the composite reaching law, we obtain the following intermediate expression: ； in, For the back electromotive force, .

7. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 6, characterized in that, When the current error approaches 0, the observed values ​​of the sliding mode control law and the back electromotive force are equal, and its expression is: ； in, This is the observed value of the back electromotive force.

8. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 7, characterized in that, Combining the intermediate expression, the sliding mode control law of the sliding mode observer based on the composite reaching law is constructed as follows: 。 9. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 8, characterized in that, In step S4, the calculation expressions for the estimated synchronous angular velocity and the estimated synchronous electrical angle are as follows: ； in, For angular error, This is an estimate of the synchronous angular velocity. This is an estimated value for the synchronous electrical angle. and The back electromotive force in the stationary coordinate system are respectively shaft and Observations on the axis The magnitude of the observed back electromotive force. and , where are the proportional and integral coefficients of the PI controller, respectively, and t is time.

10. The method for observing the speed of a piecewise linear induction motor based on a composite reaching law according to claim 9, characterized in that, Step S4 further includes: The estimated secondary speed is calculated based on the synchronous angular velocity estimate, slip angular frequency, and motor pole pitch. The estimated value of the secondary displacement is calculated based on the estimated value of the secondary velocity. The slip angular frequency is calculated based on the primary current d-axis reference value, the primary current q-axis reference value, the secondary resistance, and the secondary self-inductance.

Images