Force control method and force control system of linear switched reluctance motor

Abstract

The present invention relates to the field of linear switched reluctance motor control technology, and specifically to a force control method and a force control system for a linear switched reluctance motor. The method comprises: obtaining the actual position, speed and current of the linear switched reluctance motor in the process of the linear switched reluctance motor approaching a processing target; judging whether the linear switched reluctance motor reaches or exceeds a preset contact condition according to the actual position and speed conditions; when the judgment result is yes, it indicates that the linear switched reluctance motor is in contact with the target; when the linear switched reluctance motor is in contact with the target, the output force of the linear switched reluctance motor is limited according to the output strategy, thereby controlling the output of the force. The force control method and system for a linear switched reluctance motor of the present invention enter a force control mode after the linear switched reluctance motor reaches the contact condition, and limits the output force by limiting the output current of the motor, so that the output force of the motor and the target is stable, thereby achieving a force control effect.

Description

[Technical field]

[0001] The present invention relates to the technical field of linear switched reluctance motor control, and in particular to a force control method and a force control system of a linear switched reluctance motor. [Background technology]

[0002] The linear switched reluctance motor is a transmission device that converts electrical energy directly into linear motion mechanical energy without any intermediate conversion mechanism. It is widely used in modern processing industries, such as laser cutting, high-speed grinders, precision lathes, machining centers, etc., all of which require high-speed and high-precision linear motion.

[0003] The output of the linear switched reluctance motor is mainly thrust. Due to many reasons such as the theory, design, manufacturing, load and interference of the linear switched reluctance motor, thrust fluctuations exist in the linear switched reluctance motor.

[0004] The linear switched reluctance motor in the prior art generally switches between position and force by hard switching. During the force loading process, especially when the linear switched reluctance motor contacts the critical point of an obstacle, the thrust fluctuates greatly, resulting in unstable operation of the linear switched reluctance motor.

[0005] Therefore, it is necessary to provide a new force control method for a linear switched reluctance motor. [Summary of the invention]

[0006] The object of the present invention is to provide a force control method and a force control system for a linear switched reluctance motor, so as to solve the technical problem of large thrust fluctuation in the prior art.

[0007] The technical solution of the present invention is as follows: a force control method for a linear switched reluctance motor is provided, the method comprising:

[0008] When the linear switched reluctance motor approaches the processing target, the actual position, speed and current of the linear switched reluctance motor are obtained;

[0009] Determining whether the linear switched reluctance motor reaches or exceeds a preset contact condition according to the actual position and speed;

[0010] When the judgment result is yes, the linear switched reluctance motor is in contact with the target; after the linear switched reluctance motor is in contact with the target, the output force of the linear switched reluctance motor is limited according to the output strategy, thereby controlling the output of the force.

[0011] Preferably, whether the linear switched reluctance motor is close to the processing target is determined based on the actual position. When the linear switched reluctance motor is close to the processing target, the controller switches from the position loop to the speed loop. At this time, the linear switched reluctance motor runs at a low constant speed. When the feedback speed decreases, it indicates that the linear switched reluctance motor has contacted the processing target.

[0012] Preferably, when the linear switched reluctance motor contacts the processing target, the output force of the linear switched reluctance motor is limited according to the output strategy, thereby controlling the output of the force.

[0013] Preferably, when the linear switched reluctance motor contacts the processing target, the controller is converted from speed mode to force control mode, and the force control limitation method at this time is to limit the output force command of the controller, and its limitation strategy is u*k / umax, where u is the force command output of the controller in the force control mode, umax is the maximum output force command of the controller, and K is the preset limit value, 0<K<umax.

[0014] Preferably, whether the linear switched reluctance motor is in contact with the processing target is determined based on the change in the speed and the actual position or based on the change in the current.

[0015] The present invention also provides a force control system for a linear switched reluctance motor, the system comprising:

[0016] A feedback module is used to obtain the actual position, speed and current of the linear switched reluctance motor when the linear switched reluctance motor approaches the processing target;

[0017] The force control limiting module is used to control the force output when the linear switched reluctance motor contacts the processing target;

[0018] A controller is used to control the output of force instructions during the machining process;

[0019] Preferably, the control system transfer function of the controller is:

[0020] C(s)×K(s)×G(s) / (1+C(s)×K(s)×G(s)), C(s) is the PID controller transfer function, K(s) is the force control limit transfer function, G(s) is the controlled object transfer function, wherein the force control limit transfer function K(s) is K / umax, wherein umax is the maximum output instruction of the controller, K is the preset limit value, and 0<K<umax.

[0021] Preferably, when the linear switched reluctance motor does not contact the processing target, the output force of the linear switched reluctance motor is not controlled, and the limiting transfer function K(s) is 1, then the control system transfer function of the controller is C(s)×G(s) / (1+C(s)×G(s)), C(s) is the PID controller transfer function, and G(s) is the controlled object transfer function.

[0022] The beneficial effects of the present invention are as follows: the force control method and system of the linear switched reluctance motor of the present invention enters a force control mode after the linear switched reluctance motor reaches the contact condition, and limits the output force by limiting the output current of the motor, so that the output force of the motor and the target is stable, thereby achieving the effect of force control.

Brief Description of the Drawings

[0023] Figure 1 is a block diagram of a force control system according to an embodiment of the present invention;

[0024] Figure 2 is a schematic diagram of a force control system according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of force output of a force control system according to an embodiment of the present invention. [Specific implementation method]

[0026] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] In order to make the description of the disclosed content more detailed and complete, the following is an illustrative description of the implementation methods and specific embodiments of the present application; however, this is not the only form of implementing or using the specific embodiments of the present application. The implementation methods cover the features of multiple specific embodiments and the method steps and sequences used to construct and operate these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step sequences.

[0028] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0029] An embodiment of the present invention provides a force control method for a linear switched reluctance motor, the method comprising the following steps:

[0030] S101, when the linear switched reluctance motor approaches a processing target, obtaining the actual position, speed and current of the linear switched reluctance motor.

[0031] S102, judging whether the linear switched reluctance motor reaches or exceeds a preset contact condition according to the actual position and speed.

[0032] In this embodiment, during the operation of the linear switched reluctance motor, first the linear switched reluctance motor continuously approaches the processing target. At this time, the linear axis of the linear switched reluctance motor does not contact the processing target; then, as the linear switched reluctance motor continues to approach the processing target, the linear switched reluctance motor comes into physical contact with the processing target; then, the linear switched reluctance motor cooperates with the instructions to implement operations such as cutting or grinding the processing target.

[0033] In step S102, it is determined whether the linear switched reluctance motor is close to the processing target based on the actual position. When the linear switched reluctance motor is close to the processing target, the controller switches from the position loop to the speed loop. At this time, the linear switched reluctance motor runs at a low constant speed. When the feedback speed decreases, it indicates that the linear switched reluctance motor has contacted the processing target. Specifically, when the linear switched reluctance motor is close to the processing target, the controller switches from the position loop to the speed loop. The linear switched reluctance motor can run at a first speed value and continue to approach the processing target. When the speed of the linear switched reluctance motor decreases (that is, the speed of the linear switched reluctance motor is less than the set speed value), it is determined that the linear switched reluctance motor has contacted the processing target. Step S102 specifically includes:

[0034] S1021, determining whether the linear switched reluctance motor is close to the processing target according to the actual position.

[0035] S1022, when the linear switched reluctance motor approaches the processing target, the controller switches from the position loop to the speed loop to make the linear switched reluctance motor run at a set speed value.

[0036] S1023, when the speed of the linear switched reluctance motor is less than the set speed value, it is determined that the linear switched reluctance motor reaches or exceeds a preset contact condition, that is, the linear switched reluctance motor has contacted the processing target.

[0037] In step S1021, a conditional position can be set, which is located between the starting point of the linear switched reluctance motor and the processing target, and is close to the processing target. For example, the starting position is 0, the position of the processing target is 100, and the conditional position can be 95 or 98. Between the starting point and the conditional position, the linear switched reluctance motor can run quickly; between the conditional position and the position of the processing target, the linear switched reluctance motor runs at a low speed to achieve weak force contact with the processing target. When the actual position of the linear switched reluctance motor reaches or exceeds the conditional position, the linear switched reluctance motor approaches the processing target. Further, it can be judged by distance, and the distance X(s) between the actual position and the starting point is compared with the distance xk between the conditional position and the starting point; when the distance X(s) between the actual position and the starting point is greater than or equal to the distance xk between the conditional position and the starting point, it is judged that the linear switched reluctance motor reaches or exceeds the preset conditional position; when the distance X(s) between the actual position and the starting point is less than the distance xk between the conditional position and the starting point, it is judged that the linear switched reluctance motor has not reached the preset conditional position.

[0038] In step S102, whether the linear switched reluctance motor is in contact with the processing target may be determined based on the change in the speed and the actual position; and whether the linear switched reluctance motor is in contact with the processing target may also be determined based on the change in the current.

[0039] S103, when the judgment result is yes, obtaining the output force of the linear switched reluctance motor based on the force control limitation strategy.

[0040] In step S103, when the linear switched reluctance motor contacts the processing target, the controller is converted from speed mode to force control mode, and the force control limitation method at this time is to limit the output force command of the controller, and the force control limitation strategy is u*k / umax, where u is the force command output of the controller in the force control mode, umax is the maximum output force command of the controller, and K is the preset limit value, 0<K<umax.

[0041] In this example, see Figure 1 As shown, assuming that the transfer function of the PID controller is C(s), the force control limit transfer function is K(s), and the controlled object transfer function is G(s), it can be deduced that the control system transfer function of the controller is C(s)×K(s)×G(s) / (1+C(s)×K(s)×G(s)).

[0042] When the judgment result is yes, the controller is converted into the force control mode, and the force control limit transfer function K(s) is K / umax, wherein umax is the maximum output force command of the controller, K is the preset limit value, and 0<K<umax.

[0043] When the judgment result is no, that is, the linear switched reluctance motor does not contact the processing target, the output force of the linear switched reluctance motor is not controlled, and the force control limit transfer function K(s) is 1, that is, the control system transfer function is C(s)×G(s) / (1+C(s)×G(s)).

[0044] See also Figure 2 As shown, the force control method of this embodiment involves position control and force control. The position control can be divided into two stages: high-speed movement and low-speed exploration. The high-speed movement stage is between the starting point and the conditional position mentioned above, and the low-speed exploration stage is between the conditional position and the position of the processing target. The position deviation is used as the switching condition of the two stages to achieve rapid suppression of the movement speed, thereby achieving the purpose of smooth switching and further realizing weak force contact. The change of force output over time is shown in the figure Figure 3 shown.

[0045] Based on the same inventive concept, the present invention also provides a force control system for a linear switched reluctance motor, which is used to implement the above-mentioned force control method. The system includes: a feedback module, which is used to obtain the actual position, speed and current of the linear switched reluctance motor when the linear switched reluctance motor approaches the processing target; a force control limitation module, which is used to control the force output when the linear switched reluctance motor contacts the processing target; and a controller, which is used to control the output of force instructions during the processing.

[0046] Specifically, when the linear switched reluctance motor contacts the processing target, the control system transfer function of the controller is C(s)×K(s)×G(s) / (1+C(s)×K(s)×G(s)), wherein C(s) is the PID controller transfer function, K(s) is the force control limit transfer function, and G(s) is the controlled object transfer function. The limit transfer function K(s) is K / umax, wherein umax is the maximum output instruction of the controller, K is the preset limit value, and 0<K<umax.

[0047] When the linear switched reluctance motor does not contact the processing target, the output force of the linear switched reluctance motor is not controlled, and the limiting transfer function K(s) is 1. Then the control system transfer function of the controller is C(s)×G(s) / (1+C(s)×G(s)), where C(s) is the PID controller transfer function and G(s) is the controlled object transfer function.

[0048] The above description is only an implementation mode of the present invention. It should be pointed out that, for ordinary technicians in this field, improvements can be made without departing from the creative concept of the present invention, but these all belong to the protection scope of the present invention.

Claims

1. A force control method for a linear switched reluctance motor, characterized in that: The method comprises: When the linear switched reluctance motor approaches the processing target, the actual position, speed and current of the linear switched reluctance motor are obtained; Determining whether the linear switched reluctance motor has contacted a processing target according to the actual position and speed; When the judgment result is yes, the controller is converted from speed mode to force control mode. The force control limitation method in the force control mode is to limit the output force command of the controller. Its force control limitation strategy is u*k / umax, where u is the force command output of the controller in the force control mode, umax is the maximum output force command of the controller, K is the preset limit value, and 0<K<umax.

2. The force control method of a linear switched reluctance motor according to claim 1, characterized in that: Also includes: Whether the linear switched reluctance motor is close to the processing target is determined according to the actual position. When the linear switched reluctance motor is close to the processing target, the controller switches from the position loop to the speed loop. At this time, the linear switched reluctance motor runs at a low constant speed. When the feedback speed decreases, it indicates that the linear switched reluctance motor has contacted the processing target.

3. The force control method of the linear switched reluctance motor according to claim 2, characterized in that: Whether the linear switched reluctance motor is in contact with the processing target is determined based on the change in the speed and the actual position or based on the change in the current.

4. A force control system for a linear switched reluctance motor, characterized in that: The system comprises: A feedback module is used to obtain the actual position, speed and current of the linear switched reluctance motor when the linear switched reluctance motor approaches the processing target; The force control limiting module is used to control the force output when the linear switched reluctance motor contacts the processing target; A controller is used for controlling the output of force instructions during a machining process. When the linear switched reluctance motor contacts the machining target, the control system transfer function of the controller is C(s)×K(s)×G(s) / (1+C(s)×K(s)×G(s)), where C(s) is the PID controller transfer function, K(s) is the force control limit transfer function, and G(s) is the controlled object transfer function. The force control limit transfer function K(s) is K / umax, where umax is the maximum output force instruction of the controller, K is a preset limit value, and 0<K<umax.

5. The force control system of the linear switched reluctance motor according to claim 4, characterized in that: When the linear switched reluctance motor does not contact the processing target, the output force of the linear switched reluctance motor is not controlled, the limiting transfer function K(s) is 1, and the control system transfer function of the controller is C(s)×G(s) / (1+C(s)×G(s)).

Images