A path planning-based servo motor repeated positioning operation efficiency optimization method

Abstract

The application relates to a path planning-based servo motor repeated positioning operation efficiency optimization method, and belongs to the field of servo motors. The method comprises the following steps: taking the time for single positioning in repeated positioning operation as a time period, calculating a path planning function of the servo motor under the condition of meeting actual positioning requirements, obtaining a single positioning speed and torque time function of a permanent magnet synchronous motor based on path planning, and obtaining a torque-speed operation curve in the single positioning process of the permanent magnet synchronous motor; a finite element model of the permanent magnet synchronous motor is established, the power of copper loss and iron loss of the motor in the full torque and speed range under the thermal steady state of repeated operation is solved, and a motor efficiency map is obtained; the application can integrate the actual operation condition of the servo motor and motor design, greatly reduces the total energy loss of the motor under the premise of meeting the servo repeated positioning function, improves the repeated positioning operation efficiency of the servo motor, and has important practical value for widely used position servo systems.

Description

Technical Field

[0001] This invention belongs to the field of servo motors and relates to a method for optimizing the repetitive positioning operation efficiency of servo motors based on path planning. Background Technology

[0002] Due to their small size, high torque density, and high energy efficiency, permanent magnet synchronous motor servo systems are finding increasingly wider applications in military, industrial, and civilian fields. In applications such as aerospace servos, airborne turntables, and industrial robots, the repetitive positioning operation of servo motors is crucial, as their operating efficiency determines the equipment's endurance and energy consumption level. This efficiency is key to improving equipment performance and achieving high energy efficiency in servo systems. During actual repetitive positioning operations, servo motors often operate repeatedly according to the path planned by the servo control system. In this case, the servo motor's operating point is represented by a torque-speed curve. Currently, motor efficiency optimization design generally considers long-term operation at rated and peak operating points, or operation over a wide torque-speed range, as exemplified by servo motors in new energy electric vehicles. Efficiency optimization is then performed targeting fixed operating points or wide operating ranges of torque and speed. However, since the operating point of a servo motor under repetitive positioning operation is a torque-speed curve, fixed-point or overall wide-range efficiency optimization methods cannot meet the actual efficiency optimization requirements. Therefore, in order to improve the endurance and energy conversion efficiency of servo equipment, it is necessary to invent a path planning-based servo motor repetitive positioning operation efficiency optimization design method. Combining the special characteristics of the torque-speed working curve under the repetitive positioning operation of the servo motor, and based on the fixed point and overall wide-area efficiency optimization methods, a high-efficiency zone movement control design in the efficiency map is proposed to increase the coverage ratio of the high-efficiency zone on the torque-speed working curve and reduce the total energy consumption under the torque-speed working curve as the integral path in a single positioning cycle. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method for optimizing the efficiency of servo motor repetitive positioning operation based on path planning. While meeting the performance requirements of the position servo system for motor positioning, and considering the unique characteristics of the torque-speed working curve under repetitive positioning operation of the servo motor, the invention designs a movement and control mechanism for the high-efficiency zone in the efficiency map. This increases the coverage ratio of the high-efficiency zone on the torque-speed working curve and reduces the total energy consumption within a single positioning cycle along the torque-speed working curve as the integral path.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for optimizing the repetitive positioning efficiency of a servo motor based on path planning, the method specifically includes the following steps:

[0006] S1: Calculate the path planning function within the single positioning time cycle of the repetitive servo motor, solve the speed and torque time functions of the permanent magnet synchronous motor within the single positioning cycle based on the path planning function, and obtain the torque-speed working curve of the permanent magnet synchronous motor in the single positioning process.

[0007] S2: Establish a finite element model of the permanent magnet synchronous motor, solve for the power of copper and iron losses in the full torque and speed range under the thermal steady state of repeated operation, and obtain the motor efficiency map;

[0008] S3: Establish the functional relationship between copper loss and iron loss power and torque speed. Using the torque-speed working curve in a single positioning process as the integration path, calculate the copper loss energy and iron loss energy consumed by the motor within a single positioning time period.

[0009] S4: For the torque-speed working curve in the motor efficiency map, reduce the power of copper loss and iron loss by reducing stator resistance and optimizing core materials, thereby improving the overall efficiency of the region traversed by the working curve.

[0010] S5: By optimizing electrical load, magnetic load and current density, the ratio of copper loss and iron loss is controlled, and the efficiency map is shifted to the high-efficiency region towards the torque-speed working curve, so that the sum of copper loss energy and iron loss energy under the torque-speed working curve as the integral path in a single positioning cycle is reduced.

[0011] Optionally, in S1, the speed and torque time functions, and the torque-speed operating curve calculation method are as follows:

[0012] S=S(t)=a0+a1(t-t0)+a2(t-t0) 2 +a3(t-t0) 3 +a4(t-t0) 4 +a5(t-t0) 5 (M.Deg)

[0013]

[0014]

[0015] T(n)=T(f -1 (n))

[0016] Where S(t) is the mechanical rotation angle as a function of time under a fifth-order polynomial path planning algorithm, a0, a1, a2, a3, a4, and a5 are the polynomial coefficients that satisfy the time period and angle of a single positioning, J is the moment of inertia of the servo motor shaft system, and the torque-speed working curve in the single positioning process is obtained by the inverse function of the speed-time function.

[0017] Optionally, in S2, the finite element model of the permanent magnet synchronous motor is an electro-magnetic-thermal coupled finite element model under repeated operation to reach thermal steady state, and the power of the motor copper loss and iron loss within the torque-speed range covering the maximum torque and the highest speed on the torque-speed working curve is solved, an efficiency map is drawn, and the power data of the motor copper loss and iron loss at different torque-speed combination points are obtained.

[0018] Optionally, in step S3, establishing the functional correspondence between the power magnitudes of copper and iron losses and torque / speed specifically includes: fitting a polynomial function of the power magnitudes of copper and iron losses with torque and speed as independent variables using the power data of the motor's copper and iron losses at different torque-speed combination points; the functional correspondence is as follows:

[0019] p Cu =f(n,T)(W)

[0020] p Fe =g(n,T)(W)

[0021] The method for calculating copper and iron energy losses using the torque-speed working curve as the integration path during a single positioning process:

[0022] W Cu +W Fe =∫ L p Cu ds+∫ L p Fe ds=∫ L f(n,T)ds+∫ L g(n,T)ds(J)

[0023]

[0024] Where L is the integral arc segment, that is, the torque-speed working curve within a single positioning time period, and t0 in the parametric equation of L is the single positioning time period.

[0025] Optionally, S5 specifically includes: a method for optimizing electrical load, magnetic load, and current density.

[0026] Based on the characteristics of servo torque motors, such as low speed, high torque, and a high proportion of copper loss in the overall loss, the electrical load of the motor design is kept constant, the magnetic load is increased, and the area ratio of the stator magnetic circuit in the 2D radial section of the motor is reduced, thereby increasing the winding slot area and reducing the current density; the proportion of iron loss in the total loss of the motor is increased, and the proportion of copper loss in the motor is reduced, so that the sum of copper loss energy and iron loss energy under the torque-speed working curve as the integral path in a single positioning cycle is reduced.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) This invention proposes a repetitive positioning servo motor design method based on path planning, which integrates the actual operating conditions of the servo system with the design of the motor body.

[0029] (2) The torque-speed running curve of the servo motor under path planning can be plotted, which can accurately improve the efficiency of the motor under the actual operating conditions in the motor efficiency map.

[0030] (3) By adopting the efficiency map high-efficiency zone movement control design, the total loss of a single positioning of the repetitive positioning servo system is greatly reduced, thereby improving the operating efficiency of the servo system. The design method proposed in this invention has strong practicality in the field of position servo systems such as industrial robots and aviation servo systems.

[0031] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0033] Figure 1 This is a flowchart of the optimized design method of the present invention;

[0034] Figure 2 A path planning curve for a single positioning operation of a position servo motor;

[0035] Figure 3 The graph shows the speed versus time curve of the position servo motor during a single positioning operation.

[0036] Figure 4 The torque versus time curve of a single positioning operation of a position servo motor;

[0037] Figure 5 The initial scheme efficiency map and the torque-speed working curve of the motor under single positioning conditions are provided.

[0038] Figure 6 Efficiency map and motor operating curve for a separate loss suppression scheme;

[0039] Figure 7 The efficiency map and motor operating curve of the present invention are shown below;

[0040] Figure 8 This is a comparison chart of the energy consumption of three different schemes under the single-positioning motor operating condition. Detailed Implementation

[0041] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0042] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0043] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0044] like Figure 1 The diagram shown is a flowchart of a servo motor repetitive positioning operation efficiency optimization design method based on path planning according to the present invention, which specifically includes the following steps:

[0045] S1: Calculate the path planning function within the single positioning time cycle of the repetitive servo motor, solve the speed and torque time functions of the permanent magnet synchronous motor within the single positioning cycle based on the path planning function, and obtain the torque-speed working curve of the permanent magnet synchronous motor in the single positioning process.

[0046] S2: Establish a finite element model of the permanent magnet synchronous motor, solve for the power of copper and iron losses in the full torque and speed range under the thermal steady state of repeated operation, and obtain the motor efficiency map;

[0047] S3: Establish the functional relationship between the power of copper loss and iron loss and torque and speed. Using the torque-speed working curve in a single positioning process as the integration path, calculate the copper loss energy and iron loss energy consumed by the motor in a single positioning time period.

[0048] S4: For the torque-speed working curve in the motor efficiency map, copper loss and iron loss are reduced by methods such as reducing stator resistance and optimizing core materials, thereby improving the overall efficiency of the region traversed by the working curve.

[0049] S5: By optimizing electrical load, magnetic load and current density, the ratio of copper loss and iron loss is controlled, and the high-efficiency region of the efficiency map is moved towards the torque-speed working curve, so that the sum of copper loss energy and iron loss energy under the torque-speed working curve as the integral path in a single positioning cycle is reduced.

[0050] Figure 2 This is a path planning curve for a single positioning operation by a position servo motor. The path planning uses a fifth-order polynomial, with a single positioning time period of 0.2 seconds and a positioning rotation angle of 180° (mechanical angle). The path planning function is:

[0051] S=S(t)=(0.225t 3 -1.6875t 4 +3.375t 5 )×10 6 (M.deg)

[0052] Figure 3 This is a graph showing the speed versus time curve of a position servo motor during a single positioning operation. The speed versus time function for a single positioning operation is as follows:

[0053]

[0054] Figure 4 This is a graph showing the torque versus time curves for a single positioning operation of a position servo motor. The torque versus time function for a single positioning operation is as follows:

[0055] T=ψ(t)=(0.2355t-3.5325t 2 +11.775t 3 )×10 4 (N·m)

[0056] Based on the torque and speed time functions of a single positioning operation, it can be seen that the servo motor operates in motor mode for the first half of the time cycle and in generator mode for the second half. Ignoring mechanical friction, the torque and speed in the motor and generator modes are perfectly symmetrical, as shown by the torque and speed time function curves. Simultaneously, by using a bidirectional energy flow power supply to feed back the generator's output energy, the mechanical power output of the motor is equal to the electrical power output of the generator. The energy actually consumed by the motor to complete a single positioning operation is the sum of copper loss, iron loss, and other energy losses during the servo motor positioning process. Since other energy losses account for a relatively small proportion, they are ignored, simplifying the calculation to the copper and iron losses under motor mode in the first half of the time cycle, and then calculating the total energy consumption for the entire single positioning cycle. The method for calculating the copper and iron losses under the integral path in the torque-speed working curve during the single positioning motor mode is as follows:

[0057]

[0058]

[0059] Figure 5 The initial efficiency map and the torque-speed working curve of the motor under single-positioning conditions are prepared by the following steps: establishing an electro-magnetic-thermal coupled finite element model of the permanent magnet synchronous motor under thermal steady state during repeated operation, solving for the power of the motor copper and iron losses within the torque-speed range covering the maximum torque and highest speed on the torque-speed working curve, drawing the efficiency map, and plotting the torque-speed working curve of the motor under single-positioning conditions in the efficiency map.

[0060] Figure 6 To develop efficiency maps and motor operating curves for individual copper and iron loss suppression schemes, the specific steps include: reducing stator winding resistance or stator current RMS value; optimizing silicon steel sheet selection, magnetic load, and magnetic circuit design; and plotting efficiency maps and torque-speed operating curves for single-position motor operation. Figure 6 As can be seen, the overall efficiency of the map has been improved.

[0061] Figure 7 The present invention provides an efficiency map and motor operating curve after synergistic regulation of copper and iron losses. Specific steps include: maintaining the electrical load of the motor design unchanged, increasing the magnetic load, and reducing the area ratio of the stator magnetic circuit in the 2D radial section of the motor, thereby increasing the winding slot area and reducing the current density, and plotting the efficiency map and torque-speed operating curve under single-position motor conditions. Figure 7 As can be seen, the high-efficiency zone of the efficiency map moves along the upper left, covering more torque-speed operating curves.

[0062] Figure 8 This chart compares the copper loss, iron loss, and total energy consumption of three different schemes under the single-positioning motor condition. The iron loss (W) of the initial scheme under the single-positioning motor condition is shown in the chart. Fe Copper energy consumption W Cu The losses are 4.1 J and 33.7 J respectively, with a total energy consumption of 37.8 J; the iron loss energy W under the single-positioning motor condition of the separate copper loss and iron loss suppression schemes. Fe Copper energy consumption W Cu The energy consumption is 4J and 26.5J respectively, with a total energy consumption of 30.5J, which is a 19% reduction compared to the initial scheme; the iron loss energy W of the single-positioning motor under the operating condition of the present invention is... Fe Copper energy consumption W Cu The energy consumption was 4.54 J and 22.4 J respectively, with a total energy consumption of 26.94 J, which is a 28.7% reduction compared to the initial scheme.

[0063] Similarly, under a completely symmetrical negative torque-speed operating curve, the generator can achieve the same efficiency improvement, thereby reducing the total energy consumed during a single positioning process by 28.7%.

[0064] As can be seen from the above results, the method proposed in this invention integrates the actual path planning of the servo system with the design of the motor body, depicts the torque-speed operation curve of the servo motor under the path planning, and moves and controls the high-efficiency zone of the motor efficiency map. The total energy consumption of a single positioning is greatly reduced, and the repetitive positioning operation efficiency of the servo motor is greatly improved.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for optimizing the repetitive positioning operation efficiency of a servo motor based on path planning, characterized in that: The method specifically includes the following steps: S1: Calculate the path planning function within the single positioning time cycle of the repetitive servo motor, solve the speed and torque time functions of the permanent magnet synchronous motor within the single positioning cycle based on the path planning function, and obtain the torque-speed working curve of the permanent magnet synchronous motor in the single positioning process. S2: Establish a finite element model of the permanent magnet synchronous motor, solve for the power of copper and iron losses across the entire torque and speed range under repetitive thermal steady-state operation, and obtain the motor efficiency map; calculate the speed and torque-time functions, and the torque-speed operating curve. Where S(t) is the mechanical rotation angle as a function of time under the path planning algorithm of a fifth-order polynomial, a0, a1, a2, a3, a4, and a5 are the polynomial coefficients that satisfy the time period and angle of a single positioning, J is the moment of inertia of the servo motor shaft system, and the torque-speed working curve in the single positioning process is obtained by the inverse function of the speed-time function. S3: Establish the functional relationship between copper loss and iron loss power and torque speed. Using the torque-speed working curve in a single positioning process as the integration path, calculate the copper loss energy and iron loss energy consumed by the motor within a single positioning time period. S4: For the torque-speed working curve in the motor efficiency map, by reducing stator resistance and optimizing core materials, the power of copper loss and iron loss is reduced, thereby improving the overall efficiency of the region traversed by the working curve. S5: By optimizing electrical load, magnetic load and current density, the ratio of copper loss and iron loss is controlled, and the efficiency map is shifted to the high-efficiency region towards the torque-speed working curve, so that the sum of copper loss energy and iron loss energy under the torque-speed working curve as the integral path in a single positioning cycle is reduced.

2. The method for optimizing the repetitive positioning operation efficiency of a servo motor based on path planning according to claim 1, characterized in that: In S2, the finite element model of the permanent magnet synchronous motor is an electro-magnetic-thermal coupled finite element model under repeated operation to reach thermal steady state. The power of the motor copper loss and iron loss is solved within the torque-speed range covering the maximum torque and the highest speed on the torque-speed working curve. An efficiency map is drawn to obtain the power data of the motor copper loss and iron loss at different torque-speed combination points.

3. The method for optimizing the repetitive positioning operation efficiency of a servo motor based on path planning according to claim 1, characterized in that: In step S3, establishing the functional correspondence between the power magnitudes of copper and iron losses and torque / speed specifically includes: using the power data of motor copper and iron losses at different torque-speed combination points, fitting a polynomial function of the power magnitudes of copper and iron losses with torque and speed as independent variables; the functional correspondence is as follows: The method for calculating copper and iron energy losses using the torque-speed working curve as the integration path during a single positioning process: Where L is the integral arc segment, that is, the torque-speed working curve within a single positioning time period, and t0 in the parametric equation of L is the single positioning time period.

4. The method for optimizing the repetitive positioning operation efficiency of a servo motor based on path planning according to claim 1, characterized in that: Specifically, S5 includes: a method for optimizing electrical load, magnetic load, and current density. Based on the characteristics of servo torque motors, such as low speed, high torque, and a high proportion of copper loss in the overall loss, the electrical load of the motor design is kept constant, the magnetic load is increased, and the area ratio of the stator magnetic circuit in the 2D radial section of the motor is reduced, thereby increasing the winding slot area and reducing the current density; the proportion of iron loss in the total loss of the motor is increased, and the proportion of copper loss in the motor is reduced, so that the sum of copper loss energy and iron loss energy under the torque-speed working curve as the integral path in a single positioning cycle is reduced.

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