A power-on zero finding method and apparatus

Abstract

This invention relates to the field of motor control and discloses a method and apparatus for finding the zero point upon power-on. The method includes: controlling the motor to run in the direction approaching the limit for one full electrical angle cycle; when the motor has completed running in the direction approaching the limit for one full electrical angle cycle, applying a composite current in the opposite direction and causing the motor to run for half an electrical angle cycle; when the motor has completed running in the direction away from the limit for half an electrical angle cycle, locking the shaft from the current position of the motor to obtain the control zero point. By controlling the motor to first run in the direction approaching the limit for one full electrical angle cycle, and then applying a current in the opposite direction to cause the motor to run in the opposite direction for half an electrical angle cycle, the locked position of the motor shaft is displaced from the limit. This avoids directly starting the motor from the limit, resulting in a small power-on displacement that is not affected by external loads. It eliminates the need to consider feedback pulses and is implemented solely based on the motor's structural characteristics, reducing the risk of abnormal output and runaway operation.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and particularly to a method and apparatus for finding the zero point upon power-on. Background Technology

[0002] Closed-loop drives are typically paired with closed-loop motors, among which incremental encoder motors are commonly used.

[0003] In practical applications, when a motor is mounted on a structure with limit switches at both ends, starting directly from the limit switches upon power-up can cause excessive zeroing deviation. Current solutions require a comprehensive judgment based on both the given position and the feedback position, which is highly parameter-dependent. Furthermore, it is difficult to quantify the standard for determining the positional error when encountering hard limit switches, relying mainly on empirical values.

[0004] The above content is only used to help understand the technical solution of the present invention and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main objective of this invention is to provide a power-on zero-point finding method and apparatus, which aims to solve the technical problem that the existing power-on zero-point finding methods rely on encoder feedback pulses as the judgment basis, are highly dependent on position parameters, and require adjustment of condition parameters for different load conditions.

[0006] To achieve the above objectives, the present invention provides a power-on zero-point finding method, wherein the power-on zero-point finding method is applied to a driver, the driver being used to drive a motor, and the method includes:

[0007] Control the motor to move it in the direction closer to the limit switch for one full electrical angle cycle;

[0008] When the motor completes one full electrical angle cycle in the direction closer to the limit, the combined current is applied in the opposite direction and the motor runs for half an electrical angle cycle.

[0009] When the motor completes half an electrical angle cycle in the direction away from the limit, the shaft is locked from the current position of the motor to obtain the control zero point.

[0010] Optionally, the step of controlling the motor to move towards the limit for one full electrical angle cycle includes:

[0011] When the motor is close to the limit, the motor is controlled to apply force in the direction of approaching the limit. At this time, the direction of the synthesized current leads the d-axis by 0 to 180 electrical degrees. Let the electrical angle of the synthesized current lead be δ1.

[0012] When the electrical angle of the motor is 180-δ1 degrees, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees.

[0013] When the electrical angle of the motor is between (180-δ1) and (360-δ1) degrees, the motor is controlled to continue applying force in the direction closer to the limit.

[0014] When the electrical angle of the motor is 360-δ1, the position of the motor is close to the limit, and the motor is controlled to continue to apply force in the direction closer to the limit.

[0015] Optionally, the step of controlling the motor to move towards the limit switch for one full electrical angle cycle further includes:

[0016] When the gap between the motor and the limit switch is the distance the motor moves by operating δ2 electrical angles, the motor is controlled to move closer to the limit switch, where δ2 is between 0 and 180 degrees.

[0017] When the electrical angle of the motor is δ2 degrees, the motor stops rotating and the position of the motor is close to the limit switch;

[0018] When the electrical angle of the motor is between δ2 and (180 + δ2), the motor is controlled to continue applying force in the direction closer to the limit.

[0019] When the electrical angle of the motor is 180 + δ2, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees.

[0020] When the electrical angle of the motor is between (180+δ2) and 360 degrees, the motor is controlled to run in the direction of the limit.

[0021] Optionally, the step of controlling the motor to move towards the limit switch for one full electrical angle cycle further includes:

[0022] When the gap between the motor and the limit switch is the distance the motor moves by an electrical angle of δ3, the motor is controlled to move closer to the limit switch, where δ3 is between 180 and 360.

[0023] When the electrical angle of the motor is δ3, the motor stops rotating and the position of the motor is close to the limit switch.

[0024] When the electrical angle of the motor is between δ3 and 360 degrees, the motor is controlled to continue applying force in the direction closer to the limit.

[0025] Optionally, the step of controlling the motor to move towards the limit switch for one full electrical angle cycle further includes:

[0026] When the gap between the motor and the limit switch is the distance the motor moves by operating δ4 electrical degrees, the motor is controlled to move towards the limit switch for one full electrical degree cycle, where δ4 is greater than 360.

[0027] Optionally, the torque equation of the motor is:

[0028] The torque is positive when the synthesized current leads the d-axis by 0 to 180 electrical degrees, and negative when the synthesized current leads the d-axis by 180 to 360 electrical degrees.

[0029] Optionally, before the step of controlling the motor to move in the direction closer to the limit for one full electrical angle cycle, the method further includes:

[0030] Given a preset current for the first phase, start the motor when the current for the second phase is 0.

[0031] Optionally, before the step of controlling the motor to move in the direction closer to the limit for one full electrical angle cycle, the method further includes:

[0032] The motor is started when the first phase current is set to 0 and the second and third phase currents are set to 0.

[0033] In addition, to achieve the above objectives, the present invention also proposes a power-on zero-point finding device, which can realize the power-on zero-point finding method as described above.

[0034] The driver of this invention controls the motor to run in the direction close to the limit for one full electrical angle cycle. When the cycle is completed, a reverse current is applied to make the motor run in the opposite direction for half an electrical angle cycle. The control zero point of the motor is obtained from the current position of the motor shaft lock, so that the motor shaft lock position is displaced from the limit. The motor is started from the current position of the shaft lock, eliminating the need to start the motor directly from the limit. The control is simple, the electrical displacement is small and it is not affected by the external load. It is implemented only based on the characteristics of the motor structure, without the need to consider feedback pulses, reducing the risk of abnormal output and runaway operation. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0036] Figure 1 This is a flowchart illustrating the first embodiment of the power-on zero-point finding method of the present invention;

[0037] Figure 2 This is a schematic diagram of the dq-axis coordinate system for the power-on zero-point finding method of the present invention;

[0038] Figure 3 This is a schematic diagram of the second embodiment of the power-on zero-point finding method of the present invention;

[0039] Figure 4 This is a simulation demonstration diagram of the second embodiment of the power-on zero-point finding method of the present invention;

[0040] Figure 5 This is a schematic diagram of the second embodiment of the power-on zero-point finding method of the present invention;

[0041] Figure 6 This is a simulation diagram of other processes in the second embodiment of the power-on zero-point finding method of the present invention.

[0042] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0043] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] Reference Figure 1 , Figure 1 This is a flowchart illustrating the first embodiment of the power-on zero-point finding method of the present invention;

[0046] based on Figure 1 The first embodiment of the power-on zero-point finding method of the present invention is proposed;

[0047] In this embodiment, the power-on zero-point finding method is applied to a driver, which is used to drive a motor, and the method includes:

[0048] Step S100: Control the motor to move towards the limit switch for one full electrical angle cycle;

[0049] It needs to be explained that, during the operation of the motor, the equation for the d-axis voltage of the motor is as follows: The equation for the q-axis voltage of the motor is as follows: Among them, u d u q R represents the d-axis and q-axis voltages of the motor rotor. s i is the stator resistance of the motor. d i q For d-axis and q-axis currents, Let ω be the magnetic flux linkage along the d and q axes. e R is the electric angular velocity. s i d u d It can be obtained directly, therefore it can be calculated using the above d-axis voltage equation formula, and similarly, it can be calculated using the q-axis voltage equation formula. Where, R... s i d i q u d u q The method of obtaining the data can be measurement in production applications or direct acquisition from the manufacturer's manual or technical documents; this embodiment does not impose any restrictions on this.

[0050] It should be noted that during the operation of the motor, the torque equation of the motor is: Among them, T e Let p be the torque and p be the pole pair number. This is combined with the calculations obtained above. The motor torque T can be calculated. e .

[0051] Meanwhile, the d-axis flux linkage equation during motor operation is: The equation for the q-axis flux linkage is: Among them, L d L q For the stator d-axis and q-axis inductances of the motor, This refers to the rotor flux linkage. During the actual power-on process of the driver, the electrical angular velocity is low and therefore negligible. and The term. Combining the d-axis flux linkage equation, q-axis flux linkage equation, and torque equation as described above, we can obtain the following:

[0052] Since the q-axis inductance and d-axis inductance in a motor are almost identical, it can be assumed that... The direction of the torque can be determined by the sign of the q-axis current.

[0053] like Figure 2 As shown, Figure 2 This is a schematic diagram of the dq-axis coordinate system for the power-on zero-point finding method of the present invention;

[0054] Once the motor rotor position is fixed, a dq-axis coordinate system can be established, as shown in the figure. The angle between the d-axis and α is δ, and the α-axis represents the direction and magnitude of the A-phase current. Within one electrical angle cycle, when rotating counterclockwise, the torque is positive when the resultant current leads the d-axis by 0 to 180 electrical angles, and negative when it leads the d-axis by 180 to 360 degrees.

[0055] When the motor is mounted on a platform with limit switches at both ends, the motor's position when the driver is powered on is uncertain; it may start at one of the limit switches or between the two limit switches. The driver will provide an electrical angle current when powered on.

[0056] It should be explained that the aforementioned motor can be either a two-phase or a three-phase motor. When the motor is a three-phase motor, this application assumes that the motor starts from a position where the first phase current is preset, the second phase current is 0, and the third phase current is 0. When the motor is a two-phase motor, this application assumes that the motor starts from a position where the first phase current is preset, and the second phase current is 0, i.e., the position coinciding with the α axis. If the shaft is locked directly from this position, the resulting motor control zero point may cause misalignment between the motor's mechanical zero point and the encoder / driver, because there is a significant zero-position deviation when the given electrical angle is locked within 180 degrees of the limit. To prevent this, it is necessary to perform a power-on self-run of an open-loop displacement (current loop control only). First, the motor runs in one direction for a full electrical angle cycle displacement, and then runs in the other direction for half an electrical angle cycle displacement.

[0057] It should be noted that the above-mentioned driver can be a device with driving or control functions, such as a stepper driver, a servo driver, etc. The following describes this embodiment and the following embodiments with the driver as the execution subject.

[0058] It should be explained that the aforementioned combined current is the combined current of each phase current of the motor, such as the combined current of phase A and phase B of a two-phase motor, or the combined current of phase A, phase B, and phase C of a three-phase motor. The application of the combined current described in this embodiment and the following embodiments refers to applying the current of each phase according to the number of phases of the motor. The magnitude of the current can vary depending on the actual application, and this embodiment does not impose any limitations on this.

[0059] It is understood that an electric motor is an electromagnetic device that converts or transmits electrical energy based on the law of electromagnetic induction. According to its application, it can be divided into drive motors and control motors. The motor used in this embodiment can be an incremental encoder motor, or other types of motors. This embodiment does not limit the type of motor used; however, this embodiment and the following embodiments will use an incremental encoder motor as an example for detailed explanation.

[0060] It should be noted that the driver can control the position of the motor by controlling its movement, enabling the motor to start far from the limit position.

[0061] It is understood that the aforementioned limit switch is a device that can realize sequential control, positioning control, and position status detection, used to control the stroke and limit protection of mechanical equipment. It can be a soft limit switch or a hard limit switch, and this embodiment does not impose any restrictions on it.

[0062] It should be explained that the electrical angle is an actual spatial geometric angle, and the 360-degree electrical angle is defined based on the completion of a full cycle of current change. One 360-degree cycle of the electrical angle can be completed in 360 degrees in space, or in 180 degrees or 90 degrees in space, depending on the number of pole pairs of the motor. In this embodiment, one complete electrical angle cycle is a 360-degree electrical angle.

[0063] It should be noted that in CNC machine tools or other equipment equipped with limit switches, the limit switches are usually installed in pairs. In this embodiment, running towards the limit switch can be understood as running towards one side of the limit switch, and running away from the limit switch can be understood as running towards the other side of the limit switch. The specific running direction of the motor can be determined according to the actual application situation, and this embodiment does not impose any restrictions on it.

[0064] It should be explained that the distance or gap mentioned in this embodiment and the following embodiments, which is N (N can be any angle) degrees of electrical angle, refers to the distance or gap that the motor moves when it runs N degrees of electrical angle under the current condition. The specific situation will change depending on the position of the motor in the actual application. For example, if the motor is 60 degrees of electrical angle away from the limit, the motor will stop rotating after running 60 degrees of electrical angle due to hitting the limit. If it continues to run in the direction closer to the limit, only the resultant current electrical angle will change and no motor displacement will occur.

[0065] It should be noted that the driver controls the motor's movement by applying a composite current to the motor to make it run in one direction, and applying a composite current in the opposite direction to make it run in the other direction. Furthermore, during motor operation, the direction in which the composite current leads the d-axis changes continuously. When the composite current leads the d-axis by 180 to 360 degrees, the motor torque changes, meaning the motor runs in the opposite direction.

[0066] In practice, the driver controls the motor to move in the direction of the limit switch for one full electrical angle cycle.

[0067] Step S200: When the motor completes one full electrical angle cycle in the direction close to the limit, apply the combined current in the opposite direction and make the motor run half an electrical angle cycle.

[0068] It should be noted that the above-mentioned combined current is the combined current of the q-axis current and the d-axis current of the motor. By applying a current in the opposite direction, the direction of the motor's motion is changed, moving it away from the limit.

[0069] It is understandable that after the motor moves 360 electrical degrees in the direction of approaching the limit, the closest position of the motor to the limit is the point where it is right next to the limit. At this point, if the motor moves 180 electrical degrees in the opposite direction, the motor can be started away from the limit.

[0070] In practice, when the motor completes one full electrical angle cycle in the direction close to the limit, the reverse current is applied to make the motor run half an electrical angle cycle.

[0071] Step S300: When the motor completes half an electrical angle cycle in the direction away from the limit, lock the shaft from the current position of the motor to obtain the control zero point.

[0072] It should be noted that the aforementioned control zero point is the position where the electrical angle of the motor and the angle of the encoder coincide. After shaft locking, the driver judges the position of the motor and encoder and sends back pulses for the user to judge whether the motor control zero point is accurate. When the motor control zero point is accurate, the motor control can be accurate, thereby reducing the risk of abnormal output and runaway operation.

[0073] It is understandable that when the motor completes half a cycle in the direction away from the limit, the motor will have moved at least a certain distance from the limit. Locking the shaft from the current position of the motor can avoid the problem of inaccurate motor shaft locking.

[0074] In practice, when the motor completes half an electrical angle cycle of reverse movement towards the operating limit, the shaft is locked from the current position of the motor to obtain an accurate control zero point.

[0075] In this embodiment, the driver controls the motor to run in the direction close to the limit for one full electrical angle cycle. When the cycle is complete, a reverse current is applied to make the motor run in the opposite direction for half an electrical angle cycle. The motor's control zero point is obtained from the current position of the motor shaft lock, so that the motor shaft lock position is displaced from the limit. The motor starts from this shaft lock position, eliminating the need to start the motor directly from the limit. The control is simple, and engineers do not need to spend too much time on on-site debugging. They can simply set the power-on self-running current for different working conditions. Moreover, the power-on displacement is small and is not affected by external loads. It is implemented only based on the characteristics of the motor structure and does not need to consider feedback pulses, reducing the risk of abnormal output and runaway operation.

[0076] Based on the first embodiment of the present invention described above, and considering that different operating conditions may occur at different positions of the motor distance limit switch, a second embodiment of the power-on zero-point finding method of the present invention is proposed, with reference to... Figure 3 , Figure 3 This is a flowchart illustrating the second embodiment of the power-on zero-point finding method of the present invention.

[0077] In this embodiment, the step of controlling the motor to move towards the limit switch for one full electrical angle cycle includes:

[0078] Step S210: When the motor is close to the limit, control the motor to apply force in the direction of approaching the limit. At this time, the direction of the synthesized current leads the d-axis by 0 to 180 electrical degrees. Let the electrical angle of the synthesized current lead be δ1.

[0079] It is understandable that when the motor is close to the limit, continuing to control the motor to apply force towards the limit will cause the motor to continue to squeeze the limit. Since the direction of the resultant current will change during operation, the direction of the motor torque will change. It is possible to make the resultant current of the motor in the initial state lead the d-axis by an electrical angle of δ1.

[0080] In the specific implementation, when the motor is close to the limit switch, the motor is controlled to apply force in the direction of approaching the limit switch, and the electrical angle by which the combined current leads the d-axis is set to δ1.

[0081] Step S211: When the electrical angle of the motor is 180-δ1 degrees, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees.

[0082] It should be noted that when the electrical angle of the motor is 180-δ1, the combined current leads the d-axis by 180 electrical angles. At the next moment, because the leading electrical angle is between 180 and 360 degrees, the direction of the torque changes, that is, the direction of the force on the motor changes. Due to the change in force, there is a gap between the motor and the limit switch, and the size of the gap is 180 electrical angles.

[0083] In the specific implementation, when the electric angle of the motor is 180-δ1, the change in the direction of the motor torque causes a gap between the motor and the limit switch. The size of the gap is the distance traveled by the motor when it travels 180 electric angles.

[0084] Step S212: When the electrical angle of the motor is between (180-δ1) and (360-δ1) degrees, control the motor to continue applying force in the direction closer to the limit.

[0085] Step S213: When the electrical angle of the motor is 360-δ1, the position of the motor is close to the limit, and the motor is controlled to continue to apply force in the direction closer to the limit.

[0086] It should be noted that when the electrical angle of the motor is between (180-δ1) and (360-δ1) degrees, the motor will continue to apply force in the direction of approaching the limit; when the electrical angle of the motor is 360-δ1, the direction of the resultant current is close to the limit, that is, the direction of the torque is close to the limit, and the position of the motor is also close to the limit at this time.

[0087] It needs to be explained that when the electrical angle of the motor is between (360-δ1) and 360 degrees, the motor continues to apply force to the limit switch. At this time, the resultant current leads the d-axis electrical angle by 360-(360-δ1)=δ1. Then, the resultant current is applied in the opposite direction and the motor runs for half an electrical angle cycle, causing a gap to be created between the motor and the limit switch. At the end of the entire process, the gap between the motor and the limit switch is 180-δ1, ranging from 0 to 180 electrical angles.

[0088] In the specific implementation, when the electrical angle of the motor is between (180-δ1) and (360-δ1) degrees, the motor is controlled to continue to apply force in the direction of approaching the limit. When the electrical angle of the motor is 360-δ1, the position of the motor is close to the limit, and the motor is controlled to continue to apply force in the direction of approaching the limit.

[0089] In this embodiment, when the motor is close to the limit switch, the motor is controlled to apply force towards the limit switch. At this time, the combined current leads the d-axis by δ1 degrees (δ1 is between 0 and 180 degrees). When the motor's operating electrical angle is 180-δ1 degrees, the combined current leads the d-axis by 180 degrees. Due to the change in torque direction, a certain gap exists between the motor and the limit switch, the size of which is the displacement of the motor when it travels 180 degrees. When the motor's operating electrical angle is between (180-δ1) and (360-δ1) degrees, the motor is controlled to continue applying force towards the limit switch. When the motor's operating electrical angle is between 360-δ1, the motor is in close contact with the limit switch. The direction of the motor's torque changes, and the motor shaft will disengage from the limit switch. When the motor's operating electrical angle is between (360-δ1) and 360 degrees, the motor is controlled to continue applying force towards the limit switch. Then, the combined current is applied in the opposite direction and the motor runs for half an electrical angle cycle, causing a gap to form between the motor and the limit switch.

[0090] Furthermore, to make the demonstration of process one more intuitive, process one of the second embodiment can be simulated using a slider and a fixed guide rail, referring to... Figure 4 , Figure 4 This is a simulation demonstration diagram of the second embodiment of the power-on zero-point finding method of the present invention;

[0091] It is understandable that at this time, the electrical angle of the combined current leading the d-axis is δ (δ is between 0 and 180 degrees), the direction of the force is consistent with the direction of the combined current, and the slider can be driven on the fixed guide rail by the belt.

[0092] It should be noted that the limit switches referred to in this simulation and the following simulations are all fixed guide rails. The slider's initial position is against the limit switch, and the slider moves towards the limit switch in one full electrical angle cycle. The specific process is as follows:

[0093] First, continue to apply force to the limit. At 180-δ degrees, the torque changes. At this moment, due to the change in the direction of the force, there is a gap between the slider and the limit, which is 180 electrical degrees. After 180-δ degrees, the slider moves closer to the limit from a position away from 180 electrical degrees. At 360-δ degrees, the slider is in close contact with the limit. From (360-δ) to 360 degrees, the slider continues to apply force to the limit. At this time, the direction of the combined current leads the d-axis electrical angle by 360-(360-δ) = δ degrees.

[0094] Then, the combined current is applied in the opposite direction and the circuit is run for half an electrical angle cycle. Finally, the slider will create a gap with the limit switch.

[0095] Throughout the entire process, the gap between the slider and the limit switch is 180-δ, ranging from 0 to 180 electrical degrees.

[0096] Furthermore, referring to Figure 5 , Figure 5 This is another flowchart illustrating a second embodiment of the power-on zero-point finding method of the present invention.

[0097] When the gap between the motor and the limit switch is between 0 and 180 electrical degrees, the step of controlling the motor to move towards the limit switch for one full electrical degree cycle further includes:

[0098] Step S220: When the gap between the motor and the limit switch is the distance moved by the motor by an electrical angle of δ2, control the motor to move closer to the limit switch, where δ2 is between 0 and 180.

[0099] Step S221: When the electrical angle of the motor is δ2 degrees, the motor stops rotating and the position of the motor is close to the limit switch;

[0100] It is understandable that when the gap between the motor and the limit switch is δ2, the motor will stop rotating when it runs at an electrical angle of δ2 degrees, and at this time the motor will be in close contact with the limit switch.

[0101] In practice, when the gap between the motor and the limit switch is δ2, the motor is controlled to move closer to the limit switch. When the electrical angle of the motor is δ2 degrees, the motor stops rotating and its position is close to the limit switch.

[0102] Step S222: When the electrical angle of the motor is between δ2 and (180 + δ2), control the motor to continue applying force in the direction closer to the limit.

[0103] Step S223: When the electrical angle of the motor is 180+δ2, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees.

[0104] It should be noted that when the electrical angle of the motor is between δ2 and (180+δ2), the driver will control the motor to apply force to the limit switch until the electrical angle of the motor is 180+δ2. At this time, the combined current leads the d-axis by 180 degrees. At the next moment, because the leading electrical angle is between 180 degrees and 360 degrees, the direction of the torque changes, that is, the direction of the force on the motor changes. Due to the change in force, there is a gap between the motor and the limit switch, and the size of the gap is 180 electrical angles.

[0105] In practice, when the electrical angle of the motor is between δ2 and (180+δ2), the motor is controlled to continue applying force to the limit switch; when the electrical angle of the motor is 180+δ2, the change in motor torque causes a gap between the motor and the limit switch.

[0106] Step S224: When the electrical angle of the motor is between (180+δ2) and 360 degrees, control the motor to run in the direction of the limit.

[0107] In practice, when the electrical angle of the motor is between (180+δ2) and 360 degrees, the motor is controlled to move in the direction of the limit so that the motor continues to approach the limit.

[0108] In this embodiment, when the gap between the motor and the limit switch is δ2 (δ2 is between 0 and 180 degrees), the motor is controlled to move closer to the limit switch. When the electrical angle of the motor's movement is δ2 degrees, the motor stops rotating and its position is close to the limit switch. When the electrical angle of the motor's movement is between δ2 and (180 + δ2), the motor is controlled to continue applying force to the limit switch. When the electrical angle of the motor's movement is between 180 and δ2, the change in the motor's torque causes a gap between the motor and the limit switch. When the electrical angle of the motor's movement is between (180 + δ2) and 360 degrees, the motor is controlled to move closer to the limit switch.

[0109] Furthermore, to make the demonstration of process two more intuitive, process one of the second embodiment can be simulated using a slider and a fixed guide rail, referring to... Figure 6 , Figure 6 Other simulation demonstration diagrams are shown for the second embodiment of the power-on zero-point finding method of the present invention;

[0110] It is understandable that the slider is positioned between the two limits, and the gap between it and the limits is δ (δ is between 0 and 180 degrees) electrical angles.

[0111] It should be noted that the specific process of the slider moving towards the limit position for one full electrical angle cycle is as follows:

[0112] The slider first approaches the limit, and at δ electrical angle, it is in close contact with the limit. At this time, the motor stops rotating. Within δ+180 degrees, it continues to apply force to the limit. At δ+180 degrees, the direction of the torque changes. At this time, due to the change in force, there is a gap between the slider and the limit, which is 180 electrical angles. From (δ+180) to 360, the slider continues to approach the limit. After the entire cycle, the gap between the slider and the limit is 180–(360-(δ+180))=δ.

[0113] After that, the combined current is applied in the opposite direction for half an electrical angle cycle. Throughout the entire process, the gap between the slider and the limit switch is 180+δ, ranging from 180 to 360 electrical angles.

[0114] Furthermore, the third step of the second embodiment of the power-on zero-point finding method of the present invention includes: when the gap between the motor and the limit switch is between 180 and 360 electrical degrees, the step of controlling the motor to run towards the limit switch for one full electrical angle cycle further includes:

[0115] Step S230: When the gap between the motor and the limit switch is the distance moved by the motor by an electrical angle of δ3, control the motor to move closer to the limit switch, where δ3 is between 180 and 360.

[0116] Step S231: When the electrical angle of the motor is δ3, the motor stops rotating and the position of the motor is close to the limit switch;

[0117] Step S232: When the electrical angle of the motor is between δ3 and 360 degrees, control the motor to continue applying force in the direction closer to the limit.

[0118] It is understandable that when the gap between the motor and the limit switch is δ3, the motor needs to travel δ3 electrical degrees to make close contact with the limit switch. Therefore, the process of controlling the motor to travel one full electrical degree cycle towards the limit switch is as follows: when the motor travels to the limit switch at an electrical degree of δ3, the motor will stop rotating due to hitting the limit switch; when the electrical degree of the motor travels is between δ3 and 360 degrees, the motor will continue to apply force to the limit switch under the action of the combined current.

[0119] In the specific implementation, when the gap between the motor and the limit switch is δ3, the motor is controlled to move towards the limit switch. When the electrical angle of the motor is δ3, the motor is close to the limit switch and stops rotating due to hitting the limit switch. When the electrical angle of the motor is between δ3 and 360 degrees, the motor will continue to apply force to the limit switch due to the effect of the combined current. When the motor finishes running a full electrical angle cycle, the motor is controlled to run in the opposite direction for half an electrical angle cycle so that the motor position is away from the limit switch.

[0120] In this embodiment, when the gap between the limit switch and the motor is between 180 and 360 electrical degrees, the motor is controlled to move towards the limit switch. When the motor reaches the position where it hits the limit switch, it stops rotating and continues to apply force to the limit switch under the action of the combined current. By moving towards the limit switch for one full electrical degree cycle, the motor is brought closer to the limit switch. Then, the motor is controlled to move away from the limit switch for half an electrical degree cycle, allowing the motor to lock its shaft at a position away from the limit switch, thus achieving a control zero point.

[0121] Furthermore, to make the demonstration of process three above more intuitive, process one of the second embodiment can be simulated using a slider and a fixed guide rail, referring to... Figure 6 , Figure 6 Other simulation demonstration diagrams are shown for the second embodiment of the power-on zero-point finding method of the present invention;

[0122] It is understandable that the slider is positioned between the two limits, and the gap between it and the limits is δ (δ is between 180 and 360 degrees) electrical angles.

[0123] It should be noted that the specific process of the slider moving towards the limit position for one full electrical angle cycle is as follows:

[0124] The slider first approaches the limit, and after an electrical angle of δ, the slider is in close contact with the limit, at which point the motor stops rotating; within an electrical angle of δ to 360 degrees, force is continuously applied to the limit, at which point the slider is still in close contact with the limit, and the direction of the motor's combined current leads the d-axis by 360-δ electrical angles.

[0125] Then, the combined current is applied in the opposite direction for half an electrical angle cycle, at which point a gap will be generated between the slider and the limit switch.

[0126] Throughout the entire process, the gap between the slider and the limit switch is 180-(360-δ)=δ-180, which ranges from 0 to 180 electrical degrees.

[0127] Furthermore, the fourth step of the second embodiment of the power-on zero-point finding method of the present invention includes: when the gap between the motor and the limit switch is greater than 360 electrical degrees, the step of controlling the motor to run towards the limit switch for one full electrical angle cycle further includes:

[0128] When the gap between the motor and the limit switch is the distance the motor moves by operating δ4 electrical degrees, the motor is controlled to move towards the limit switch for one full electrical degree cycle, where δ4 is greater than 360.

[0129] It is understandable that when the gap between the motor and the limit switch is greater than 360 electrical degrees, even if the motor moves towards the limit switch for one full electrical angle cycle, there will still be a gap of δ4-360 electrical angles.

[0130] In practice, when the gap between the motor and the limit switch is greater than 360 electrical degrees, the motor is controlled to move towards the limit switch for one full electrical degree cycle.

[0131] In summary, all four scenarios described above enable the motor to start far from the limit switch, thus achieving an accurate motor control zero point.

[0132] Furthermore, this embodiment of the invention also proposes a power-on zero-point finding device, which can realize the power-on zero-point finding method as described above, so that the motor starts far from the limit position and obtains an accurate motor control zero point.

[0133] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0134] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0135] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A method for finding the zero point upon power-on, characterized in that, The power-on zero-point finding method is applied to a stepper driver, which is used to drive a motor. The method includes: Control the motor to move it in the direction closer to the limit switch for one full electrical angle cycle; When the motor completes one full electrical angle cycle in the direction closer to the limit, the combined current is applied in the opposite direction and the motor runs for half an electrical angle cycle. When the motor completes half an electrical angle cycle in the direction away from the limit, the shaft is locked from the current position of the motor to obtain the control zero point; The torque equation of the motor is: ; in, For torque, For extreme logarithms, For rotor flux linkage, This is the q-axis current; The torque is positive when the synthesized current leads the d-axis by 0 to 180 electrical degrees, and negative when the synthesized current leads the d-axis by 180 to 360 electrical degrees.

2. The method as described in claim 1, characterized in that, The step of controlling the motor to move towards the limit position for one full electrical angle cycle includes: When the motor is close to the limit, the motor is controlled to apply force in the direction of approaching the limit. At this time, the direction of the synthesized current leads the d-axis by 0~180 electrical degrees. Let the electrical angle of the synthesized current lead be δ1. When the electrical angle of the motor is 180-δ1 degrees, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees. When the electrical angle of the motor is between (180-δ1) and (360-δ1) degrees, the motor is controlled to continue applying force in the direction closer to the limit. When the electrical angle of the motor is 360-δ1, the position of the motor is close to the limit, and the motor is controlled to continue to apply force in the direction closer to the limit.

3. The method as described in claim 1, characterized in that, The step of controlling the motor to move towards the limit position for one full electrical angle cycle also includes: When the gap between the motor and the limit switch is the distance the motor moves by operating δ2 electrical angles, the motor is controlled to move closer to the limit switch, where δ2 is between 0 and 180 degrees. When the electrical angle of the motor is δ2 degrees, the motor stops rotating and the position of the motor is close to the limit switch; When the electrical angle of the motor is δ2~(180+δ2), the motor is controlled to continue applying force in the direction closer to the limit. When the electrical angle of the motor is 180 + δ2, the change in the motor torque causes a gap between the motor and the limit switch. The size of the gap is the displacement of the motor when it travels 180 electrical degrees. When the electrical angle of the motor is between (180+δ2) and 360 degrees, the motor is controlled to run in the direction of the limit.

4. The method as described in claim 2, characterized in that, The step of controlling the motor to move towards the limit position for one full electrical angle cycle also includes: When the gap between the motor and the limit switch is the distance the motor moves by operating an electrical angle of δ3, the motor is controlled to move closer to the limit switch, where δ3 is between 180 and 360. When the electrical angle of the motor is δ3, the motor stops rotating and the position of the motor is close to the limit switch. When the electrical angle of the motor is between δ3 and 360 degrees, the motor is controlled to continue applying force in the direction closer to the limit.

5. The method as described in claim 2, characterized in that, The step of controlling the motor to move towards the limit position for one full electrical angle cycle also includes: When the gap between the motor and the limit switch is the distance the motor moves by operating δ4 electrical degrees, the motor is controlled to move towards the limit switch for one full electrical degree cycle, where δ4 is greater than 360.

6. The method as described in claim 1, characterized in that, Before the step of controlling the motor to move towards the limit position for one full electrical angle cycle, the method further includes: Given a preset current for the first phase, start the motor when the current for the second phase is 0.

7. The method as described in claim 1, characterized in that, Before the step of controlling the motor to move towards the limit position for one full electrical angle cycle, the method further includes: The motor is started when the first phase current is set to 0 and the second and third phase currents are set to 0.

8. A power-on zero-point finding device, characterized in that, The device can implement the power-on zero-point finding method as described in any one of claims 1-7.

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