Control method, device and equipment of permanent magnet linear synchronous motor and medium

Abstract

The invention discloses a control method, device and equipment of a permanent magnet linear synchronous motor and a medium, and relates to the field of motors, when the permanent magnet linear synchronous motor just starts to start, the motor is started by adopting a specific first target current vector in an open-loop control mode, and after a rotor of the motor reaches a certain speed, the motor is started by adopting a second target current vector. The position of the rotor is identified by using back electromotive force, and the motor is controlled to operate in a closed-loop control mode; and when the motor needs to be shut down, the specific second target current vector is also adopted to control the motor to be shut down in the open-loop control mode. The open-loop starting mode can solve the problem of rotor position identification at a low speed, and the open-loop stopping mode can solve the problem of mechanical shock. The combined control mode can simply and quickly start the motor, and non-inductive control over the motor is achieved. Meanwhile, the control system has the advantages that the requirement for power supply voltage quality is not high, motor heating and mechanical shock are reduced, the service life of the motor is prolonged, and the safety and reliability of motor operation are ensured.

Description

Technical Field

[0001] The present invention relates to the field of motors, and in particular to a control method, device, equipment and medium for a permanent magnet linear synchronous motor. Background Art

[0002] At present, most oil fields have reached the middle and late stages of exploitation. The self - spraying capacity of oil wells has decreased significantly, and the number of high - viscosity oil wells, high - sand, high - wax and high - gas crude oil wells has gradually increased. Special mechanical equipment is needed to extract oil. With the development of motor structure design and materials, the application range of submersible permanent magnet linear synchronous motors with higher efficiency and power factor is becoming wider and wider. The submersible permanent magnet linear synchronous motor cleverly combines a cylindrical linear motor and a reciprocating piston pump to form a rodless oil production system. The moving part of the linear motor is tightly connected to the piston of the downhole reciprocating piston pump. When the primary winding of the linear motor is energized, the moving part can drive the piston to reciprocate up and down in the pump barrel, so as to effectively suck the crude oil.

[0003] In the prior art, there are mainly two ways to control motors. The first is to set a hardware position encoder and rely on the hardware position encoder to obtain the real - time position of the motor mover, so as to control the motor. However, the permanent magnet linear synchronous motor for oil pumping runs in an environment with high pressure and large temperature difference for a long time. In this environment, the encoder is easy to be damaged and has a high failure rate. Once the encoder is damaged, the motor cannot run. The second way is to identify the mover position through a sensorless algorithm, such as extracting the position information of the motor mover through the back electromotive force. However, when the motor runs at a low speed, the back electromotive force of the motor is low, and the identification and control are difficult. Especially, the linear motor for oil pumping is located deep in the oil well during operation, and the line pressure difference is large. The line voltage loss further aggravates the inaccuracy of the motor position identification. Therefore, how to accurately control the permanent magnet linear synchronous motor has become an urgent technical problem to be solved at present. Summary of the Invention

[0004] The purpose of the present invention is to provide a control method, device, equipment and medium for a permanent magnet linear synchronous motor, which avoids control errors caused by low back electromotive force and line voltage damage during startup, and realizes accurate control of the motor; through current vector control, soft start and soft stop of the permanent magnet linear synchronous motor are realized, avoiding system failures caused by over - current during motor startup, preventing collisions or equipment damage caused by inertial impact or sudden change of mechanical stress during emergency stop, and ensuring the safety and reliability of motor operation.

[0005] To solve the above - mentioned technical problems, the present invention provides a control method for a permanent magnet linear synchronous motor, including:

[0006] Control the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, and control the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; the amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset rule;

[0007] When the speed of the mover reaches a preset speed, determine the position of the mover according to the back electromotive force of the permanent magnet linear synchronous motor, and control the operation of the permanent magnet linear synchronous motor based on the position of the mover;

[0008] Control the stator of the permanent magnet linear synchronous motor to synthesize a second target current vector, and control the mover of the permanent magnet linear synchronous motor to stop with uniform deceleration based on the second target current vector; the amplitude of the second target current vector is a second preset amplitude, and the slope of the second target current vector gradually decreases from a second preset value to zero based on a second preset rule.

[0009] Optionally, before controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, it further includes:

[0010] Inject a current signal with a preset frequency into the stator winding of the permanent magnet linear synchronous motor to determine the initial position of the mover of the permanent magnet linear synchronous motor.

[0011] Optionally, controlling the operation of the permanent magnet linear synchronous motor includes:

[0012] Obtain the instantaneous values of the three-phase back electromotive forces of the permanent magnet linear synchronous motor;

[0013] Control the voltage application mode between the three-phase bridge arms and the DC bus in the drive circuit of the permanent magnet linear synchronous motor based on the magnitude relationship between the instantaneous values of the three-phase back electromotive forces.

[0014] Optionally, controlling the voltage application mode between the three-phase bridge arms and the DC bus in the drive circuit of the permanent magnet linear synchronous motor based on the magnitude relationship between the instantaneous values of the three-phase back electromotive forces includes:

[0015] Control the bridge arm corresponding to the phase with the largest back electromotive force in the drive circuit of the permanent magnet linear synchronous motor to connect to the positive pole of the DC bus;

[0016] Control the bridge arm corresponding to the phase with the smallest back electromotive force in the drive circuit to connect to the negative pole of the DC bus;

[0017] Control the bridge arm corresponding to the phase with the intermediate back electromotive force in the drive circuit to be suspended.

[0018] Optionally, determining the mover position based on the back electromotive force of the permanent magnet linear synchronous motor to control the operation of the permanent magnet linear synchronous motor based on the mover position includes:

[0019] Determining the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor;

[0020] Determining the mover position based on the zero-crossing point of the back electromotive force to control the permanent magnet linear synchronous motor based on the mover position.

[0021] Optionally, determining the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor includes:

[0022] Obtaining the phase voltages of the three-phase windings in the stator winding of the permanent magnet linear synchronous motor;

[0023] Determining the voltage average value of the phase voltages of the three-phase windings and calculating the difference between the preset phase voltage and the voltage average value;

[0024] Determining the zero-crossing point of the difference between the preset phase voltage and the voltage average value as the zero-crossing point of the preset back electromotive force.

[0025] To solve the above technical problems, the present invention also provides a control device for a permanent magnet linear synchronous motor, including:

[0026] A starting unit, configured to control the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector to control the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; the amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset law;

[0027] An operating unit, configured to determine the mover position according to the back electromotive force of the permanent magnet linear synchronous motor when the speed of the mover reaches a preset speed, so as to control the operation of the permanent magnet linear synchronous motor based on the mover position;

[0028] A stopping unit, configured to control the stator to synthesize a second target current vector to control the mover of the permanent magnet linear synchronous motor to stop with uniform deceleration based on the second target current vector; the amplitude of the second target current vector is a second preset amplitude, and the slope of the second target current vector gradually decreases from the second preset value to zero based on a second preset law.

[0029] To solve the above technical problems, the present invention also provides an electronic device, including:

[0030] A memory, configured to store a computer program;

[0031] A processor for implementing the steps of the control method of the permanent magnet linear synchronous motor as described above.

[0032] To solve the above technical problems, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the steps of the control method of the permanent magnet linear synchronous motor as described above.

[0033] The present invention provides a control method for a permanent magnet linear synchronous motor. When the permanent magnet linear synchronous motor starts, a specific first target current vector is directly used to start the motor in an open-loop control manner. After the mover of the motor reaches a certain speed, the back electromotive force is used to control the operation of the motor in a closed-loop control manner. When stopping the machine, a specific second target current vector is also used to control the motor to stop in an open-loop control manner. Thus, it avoids the control error caused by the low back electromotive force and line voltage damage during startup, and realizes the accurate control of the motor. Through current vector control, soft start and soft stop of the permanent magnet linear synchronous motor are realized, avoiding system failures caused by overcurrent during motor startup, preventing collisions or equipment damage caused by inertial impact or sudden change of mechanical stress during emergency stop, and ensuring the safety and reliability of motor operation.

[0034] The present invention also provides a control device, an electronic device and a computer-readable storage medium for a permanent magnet linear synchronous motor, which have the same beneficial effects as the control method of the permanent magnet linear synchronous motor described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 It is a schematic flowchart of a control method for a permanent magnet linear synchronous motor provided by the present invention;

[0037] Figure 2 It is a control flowchart of a control strategy for a permanent magnet linear synchronous motor provided by the present invention;

[0038] Figure 3 It is a schematic diagram of the working principle of a brushless DC motor provided by the present invention;

[0039] Figure 4 It is an equivalent circuit diagram of a brushless DC motor provided by the present invention;

[0040] Figure 5Schematic diagram of the back electromotive force waveform of a brushless DC motor provided by the present invention;

[0041] Figure 6 Schematic diagram of the equivalent circuit of a permanent magnet linear synchronous motor in the B+, A- working mode provided by the present invention;

[0042] Figure 7 Schematic diagram of different switching modes of six-step commutation of a permanent magnet linear synchronous motor provided by the present invention;

[0043] Figure 8 Schematic diagram of the circuit of a permanent magnet linear synchronous motor in the B+, A- working mode provided by the present invention;

[0044] Figure 9 Schematic diagram of the back electromotive force waveform of a permanent magnet oil-well linear synchronous motor provided by the present invention;

[0045] Figure 10 Schematic diagram of the structure of a control system of a permanent magnet linear synchronous motor provided by the present invention;

[0046] Figure 11 Schematic diagram of the structure of an electronic device provided by the present invention. Detailed implementation manners

[0047] The core of the present invention is to provide a control method, device, equipment and medium for a permanent magnet linear synchronous motor, which avoids control errors caused by low back electromotive force and line voltage damage during startup, and realizes accurate control of the motor; through current vector control, soft start and soft stop of the permanent magnet linear synchronous motor are realized, avoiding system failures caused by overcurrent during motor startup, preventing collisions or equipment damage caused by inertial impact or sudden change of mechanical stress during emergency stop, and ensuring the safety and reliability of motor operation.

[0048] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] Please refer to Figure 1 , Figure 1 Schematic diagram of the flow of a control method for a permanent magnet linear synchronous motor provided by the present invention; Please refer to Figure 2 , Figure 2The control flow chart of a control strategy for a permanent magnet linear synchronous motor provided by the present invention; To solve the above technical problems, the present invention provides a control method for a permanent magnet linear synchronous motor, including:

[0050] S11: Control the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, so as to control the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; The amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset law.

[0051] It is not difficult to understand that considering the heavy load of the submersible permanent magnet linear synchronous motor used for oil pumping, if closed-loop control is directly adopted, it is difficult for the controller to work stably and it is also difficult to achieve accurate control of the motor. Therefore, in this application, when the motor starts, the IF start (current-frequency control start) method is adopted. The frequency converter in the motor control system outputs a first target sinusoidal current vector with a specific amplitude, that is, the first preset amplitude, to the stator winding of the motor. The amplitude of the first target sinusoidal current vector remains unchanged, and the frequency ramps up to the set first preset value. The mover starts with uniform acceleration under the action of the current vector synthesized by the stator. The IF start adopts a speed open-loop method, which does not rely on the feedback of the operating states such as the speed and position of the motor, but directly uses a preset sinusoidal current vector to drive the motor to operate, controls the motor start in an open-loop control manner, uses the preset current vector to generate a certain electromagnetic torque to drive the mover to start to move, and uses a larger electromagnetic force to make the motor mover reach a certain speed and then switch to closed-loop control, thereby improving the stability of the control system. The soft start of the motor, that is, the flexible start, is realized through the sinusoidal current vector control. When starting, the speed of the motor rises slowly, avoiding system failures caused by overcurrent.

[0052] It should be noted that in actual applications, the process of the frequency converter outputting a sine current vector with a specific amplitude to the stator winding of the motor corresponds to a control operation that uses vector control to output three-phase equivalent sine voltages to the stator winding. By adjusting the amplitudes and phases of the three-phase equivalent sine voltages output to the three-phase stator windings, the three-phase stator currents are synthesized in space to form a first target current vector or a second target current vector. The specific values and implementation methods of the first preset amplitude, the first preset law, and the first preset value are not particularly limited in this application. The first preset amplitude can be set and adjusted according to actual requirements such as the suction force required by the motor. The larger the amplitude of the current vector, the stronger the generated magnetic field, thereby realizing the setting and adjustment of the linear motion speed of the mover. The first preset law can generally be realized by setting a specific increase step. The first preset value can be determined according to actual application requirements and set and adjusted according to the suction force required by the motor. The slope of the current vector affects the magnitude and change rate of the magnetic field generated by the stator. Therefore, the magnitude of the slope of the current vector and the first preset law of change can be determined according to the suction force requirement and the mover speed requirement during application. The specific implementation methods such as the specific amplitude of the three-phase equivalent sine voltages output by the frequency converter can be adjusted and controlled according to the amplitudes and slopes of the preset first target current vector or second target current vector, which are not particularly limited in this application.

[0053] S12: When the speed of the mover reaches the preset speed, determine the position of the mover according to the back electromotive force of the permanent magnet linear synchronous motor, so as to control the operation of the permanent magnet linear synchronous motor based on the position of the mover.

[0054] It can be understood that when the mover accelerates to a certain preset speed under IF start control, it can be switched to a sensorless control method to extract information such as the position and speed of the mover by detecting the back electromotive force of the motor, thereby realizing the closed-loop control of the motor. This method has a very weak dependence on motor parameters and is suitable for occasions where the control application is not demanding such as oil pumping, and has strong control robustness. The specific implementation methods of the closed-loop control are not particularly limited in this application. The specific process of the closed-loop control can include obtaining the real-time position and / or real-time speed of the mover according to the real-time detected back electromotive force, and judging whether the real-time position and / or real-time speed of the mover is consistent with the required target position or target speed. If not, adjust the control command to ensure the accurate control of the mover position; the control command specifically includes the power supply frequency of the motor, the magnitude of the current output to the stator winding, the phase between the three-phase currents output to the stator winding, the magnitude of the voltage output to the stator winding, etc. There are also various methods for estimating and identifying the rotor position, which are not particularly limited in this application. The zero-crossing detection method can be used to extract speed and position information from the estimated back electromotive force information.

[0055] S13: Control the stator to synthesize the second target current vector to control the mover of the permanent magnet linear synchronous motor to decelerate uniformly to stop based on the second target current vector; the amplitude of the second target current vector is the second preset amplitude, and the slope of the second target current vector gradually decreases from the second preset value to zero based on the second preset rule.

[0056] It is not difficult to understand that when the motor needs to stop, a control method similar to that during stopping can be adopted to achieve the stopping of the motor through IF control. The frequency converter outputs a sine current vector with a specific amplitude to the stator winding. The amplitude of this vector remains unchanged, and the frequency ramps down to near zero. The mover decelerates uniformly under the action of the stator current vector until the motor stops. The specific values and implementation methods of the second preset amplitude, the second preset rule, and the second preset value are not particularly limited in this application. The second preset amplitude can be set and adjusted according to actual requirements such as the required stopping duration and stopping space of the motor; the second preset rule can be implemented using the same rule as the first preset rule. For example, if the first preset rule is to set a specific increase step, then the second preset rule is to set a specific decrease step. The second preset value can be determined according to the real-time stator current at the moment when the motor starts to stop. As a preferred embodiment, the second preset amplitude is equal to the first preset amplitude, and the first preset value is equal to the second preset value, realizing symmetric control of motor startup and stopping and further improving the control accuracy. Soft stop of the motor is achieved through sine current vector control.

[0057] It should be noted that the control system realizes the pumping of the oil field by driving the reciprocating operation of the mover in the permanent magnet linear synchronous motor. Each upward or downward movement of the mover is called a stroke. The operation of the mover in any stroke needs to be realized by using the above steps S11 to S13. At the same time, due to the limited operating space of the permanent magnet linear synchronous motor, the distance of each operation needs to be strictly controlled without error, otherwise the accumulation of errors will cause the fault of the mover colliding with the stator. By adopting IF startup and IF braking, the problem of stroke accuracy can also be effectively solved. The electrical angles of the two current vectors running are determined. Under the action of the electromagnetic force, the mover of the motor will run a specified stroke.

[0058] It can be understood that through the reasonable combined use of different control methods, this application provides a high-efficiency motor control strategy for a permanent magnet linear synchronous motor used in submersible oil pumping without sensors to meet the stringent requirements of the oil pumping project for the high reliability and wide speed range operation of the permanent magnet synchronous linear motor. The control strategy during the entire operation process of the permanent magnet synchronous linear motor is as Figure 2As shown in the figure, the top dead center is the top position of the permanent magnet synchronous linear motor; the bottom dead center is the bottom position of the permanent magnet synchronous linear motor, and the mover moves between the top dead center and the bottom dead center. The specific type and implementation manner of the permanent magnet synchronous linear motor applicable to this application are not particularly limited herein.

[0059] Furthermore, the collision detection algorithm can be started when the mover runs to the top dead center and / or runs to the bottom dead center. By monitoring the collision situation when the linear motor runs to both ends of the stroke, the position of the mover can be further located, and the occurrence of frequent collisions can be effectively avoided, improving the stability of motor control and preventing the mover from losing steps and jittering. When it is detected that the motor current increases due to collision in the deceleration section of the motor, the motor is controlled to enter active braking, effectively avoiding the mechanical impact of the mover on the motor housing and improving the service life of the motor.

[0060] Starting from the actual engineering situation, the present invention proposes a combined control strategy for application to submersible motors. The IF start avoids the problem of inaccurate rotor position detection relying on the motor back electromotive force at zero speed, and realizes high-reliability sensorless control of the motor over a wide speed range. It meets the high-reliability requirements of the motor in the application scenario of deep well pumping. In this application scenario, the requirements for the speed and torque fluctuations of the motor are not strict. Therefore, through the combined control strategy of soft stop and soft start and sensorless operation of the motor, sensorless control of the entire speed range of the motor is achieved. Considering the special working conditions of deep well pumping, the motor is started with heavy load by using magnetic positioning plus IF start. Not only can the motor start with load, but also under the control of sensor operation, it can cooperate with the six-step commutation operation to achieve maximum control of the electromagnetic thrust. In addition, protection algorithms such as soft start, soft stop, and collision detection algorithm ensure the stable and reliable operation of the entire system, effectively improving the motor life and operation stability, and perfectly adapting to the pumping operation conditions. The control of soft stop includes passive braking and active braking triggered by the collision detection algorithm. Active braking is achieved by introducing IF soft stop control to protect the motor housing from impact, effectively preventing the problem of mover collision during motor operation and improving the service life of the motor. The voltage supply range is wide, avoiding the problem that the motor cannot start due to line voltage drop. The combination of multiple control strategies is most applicable to actual engineering, and at the same time avoids the problem of shortened motor life caused by control breakdown.

[0061] Based on the above embodiments:

[0062] As an optional embodiment, before controlling the stator of the permanent magnet linear synchronous motor to synthesize the first target current vector, it further includes:

[0063] Injecting a current signal with a preset frequency into the stator winding of the permanent magnet linear synchronous motor to determine the initial position of the mover of the permanent magnet linear synchronous motor.

[0064] It is not difficult to understand that before starting the motor, it is necessary to determine the initial position of the mover first in order to achieve accurate control of the motor. Therefore, before controlling the motor to start, a magnetic positioning operation is also required to determine the initial position of the mover. The magnetic positioning operation can be specifically implemented by inputting a high-frequency current. The frequency converter supplies a sinusoidal current vector with a specific frequency to the stator winding. The electrical angle of this sinusoidal current vector remains unchanged, and the amplitude ramps up from zero to the set value, so that the motor mover can move to the specified position under the action of electromagnetic force, and the initial position of the mover is determined. The specific implementation method of the current signal and the like are not particularly limited in this application, and the specific value of its preset frequency can be set and adjusted according to the parameters of the motor in actual application.

[0065] Specifically, by determining the initial position of the mover in advance, the accuracy and reliability of the motor control process are guaranteed, a position reference is provided for subsequent vector control, abnormal situations such as jitter during startup are avoided, the dynamic response ability of the entire control system is improved, and the safety and reliability during motor operation are further improved.

[0066] Please refer to Figure 3 , Figure 3 which is a schematic diagram of the working principle of a brushless DC motor provided by the present invention; please refer to Figure 4 , Figure 4 which is a schematic diagram of the equivalent circuit of a brushless DC motor provided by the present invention; please refer to Figure 5 , Figure 5 which is a schematic diagram of the back electromotive force waveform of a brushless DC motor provided by the present invention, with the abscissa being time t and the ordinate being the back electromotive force; as an optional embodiment, controlling the operation of a permanent magnet linear synchronous motor includes:

[0067] Obtaining the instantaneous values of the three-phase back electromotive forces of the permanent magnet linear synchronous motor;

[0068] Based on the magnitude relationship between the instantaneous values of the three-phase back electromotive forces, controlling the voltage application method between the three-phase bridge arms and the DC bus in the drive circuit of the permanent magnet linear synchronous motor.

[0069] It is not difficult to understand that in order to improve the working efficiency of the motor, in the process of closed-loop control of the permanent magnet linear synchronous motor according to the back electromotive force, the step-changing idea of the DC brushless motor can also be introduced into the control process of the permanent magnet linear synchronous motor to achieve maximum thrust senseless control with zero-crossing detection every 60 degrees (electrical angle). The specific method of obtaining the instantaneous back electromotive force is not particularly limited in this application. The instantaneous value of the three-phase back electromotive force includes the instantaneous value of the A back electromotive force, the instantaneous value of the B back electromotive force, and the instantaneous value of the C back electromotive force. The voltage application method between the three-phase bridge arm and the DC bus refers to the three-phase bridge arm of the inverter in the drive circuit of the control system. The three-phase bridge arm generates a magnetic field to drive the operation of the motor by outputting three-phase voltage and three-phase current to the stator winding. In this application, the drive circuit mainly refers to the inverter and / or inverter in the control system. This application does not make any special restrictions on the specific types and implementation methods of the motor control system and the drive circuit therein. The drive circuit generally uses switching devices such as MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor) or IGBTs (Insulate-Gate Bipolar Transistor) to form bridge arms, and forms a frequency converter or inverter by connecting the three-phase bridge arms in parallel.

[0070] It should be noted that because the brushless DC motor is essentially still a special AC motor, the step-changing theory during its operation can also be applied to linear motors. First, take the brushless DC motor as an example to explain its step-changing operation. Figure 3 As shown, the stator winding includes phase A winding, phase B winding and phase C winding, and the rotor flux space vector by The electrical angular velocity (angular frequency) of the Indicates the spatial position of the rotor flux; the equivalent circuit of the brushless DC motor is as follows Figure 4 As shown, the equivalent circuit of each phase of the brushless DC motor is the inductor L s , resistor R s The permanent magnet linear synchronous motor can also be equivalent to a similar circuit with a corresponding series circuit of a pair of reverse electromotive force. s 、Inductor R s The equivalent value of is determined by the stator winding of the motor, and the waveform of the back electromotive force is determined by the motor position (electrical angle) and the angular frequency of the motor operation. This article adopts the motor convention. The reference direction of the three-phase voltage and current is the same and the positive direction is the flow into the motor. The reference direction of the back electromotive force is opposite to the reference direction of the current. The positive direction of the magnetic flux and the positive direction of the current satisfy the right-hand screw rule. The mathematical equation for the calculation of the parameters of the brushless DC motor in the three-phase stationary coordinate system is:

[0071] ;

[0072] Wherein, is the input phase voltage of the A-phase winding of the motor, is the input phase voltage of the B-phase winding of the motor, is the input phase voltage of the C-phase winding of the motor; is the back electromotive force of the A-phase winding of the motor, is the back electromotive force of the B-phase winding of the motor, is the back electromotive force of the C-phase winding of the motor; is the phase inductance of the stator winding of the motor, is the resistance of the stator winding of the motor, is the current of the stator A-phase winding, is the current of the stator B-phase winding, is the current of the stator C-phase winding, is the electromagnetic torque of the motor, is the number of pole pairs, is the angular frequency of the mover operation. The phase inductance of the permanent magnet linear synchronous motor for pumping is a constant.

[0073] Spatially, the rotation of the rotor of the motor generates a rotating magnetic field. The relative movement between the mover (rotor) winding and this magnetic field causes the stator winding to cut the magnetic force lines, inducing a back electromotive force on the stator side. Therefore, this back electromotive force is closely related to the rotor position, and the rotor position can reflect the waveform characteristics of the back electromotive force. Without loss of generality, assume that the back electromotive force waveform is a sine wave. When the motor rotor runs counterclockwise, the three-phase back electromotive force waveforms are as Figure 5 shown. From the torque equation of the motor, it can be known that when the current of each phase is in the same sign as the back electromotive force, the motor can obtain the maximum torque, which is reflected as control in the sine wave control scheme. Therefore, by adjusting the voltage application method between the three-phase bridge arm and the DC bus in the drive circuit of the permanent magnet linear synchronous motor, the current direction of each phase can be controlled, so as to maximize the motor torque.

[0074] Specifically, by analogy with the DC brushless motor, the permanent magnet linear synchronous motor can also control the current direction of each phase current output to the stator winding by controlling the voltage application method between the three-phase bridge arm and the DC bus, so as to achieve the maximum thrust control of the permanent magnet linear synchronous motor by maximizing the torque, realize the dynamic adjustment of the motor operating point, improve the working efficiency of the motor, ensure that the motor can output the maximum thrust under different load conditions, improve the adaptability and stability of the entire motor system, reduce energy loss, and improve energy utilization efficiency.

[0075] Please refer to Figure 6 ,Figure 6 Schematic diagram of the equivalent circuit of a permanent magnet linear synchronous motor provided by the present invention in the B+ and A- operating modes; please refer to Figure 7 , Figure 7 Schematic diagram of different switching modes of six-step commutation of a permanent magnet linear synchronous motor provided by the present invention; please refer to Figure 8 , Figure 8 Schematic diagram of the circuit of a permanent magnet linear synchronous motor provided by the present invention in the B+ and A- operating modes; As an alternative embodiment, based on the magnitude relationship between the instantaneous values of the three-phase back electromotive forces, the voltage application method between the three-phase bridge arm and the DC bus in the drive circuit of the permanent magnet linear synchronous motor is controlled, including:

[0076] Control the bridge arm corresponding to the phase with the largest back electromotive force in the drive circuit of the permanent magnet linear synchronous motor to connect to the positive pole of the DC bus;

[0077] Control the bridge arm corresponding to the phase with the smallest back electromotive force in the drive circuit to connect to the negative pole of the DC bus;

[0078] Control the bridge arm corresponding to the phase with the intermediate back electromotive force in the drive circuit to be floating.

[0079] It can be understood that in the square wave control scheme, the maximum thrust control is specifically embodied as the six-step commutation method control described below. Sort the instantaneous values of the three-phase back electromotive forces of the motor. The phase with the largest back electromotive force must be positive, and the smallest phase must be negative. The basic idea of the six-step commutation method is: connect the phase with the largest back electromotive force to the DC bus P (positive pole), connect the phase with the smallest back electromotive force to the DC bus N (negative pole), and the phase with the intermediate back electromotive force value is floating, so as to maximize the torque. For example, map the linear motion interval of the mover of the permanent magnet linear synchronous motor to the angular range of 0-360 degrees, and define the mover position with the angular information within the angular range of 0-360 degrees. For the permanent magnet linear synchronous motor, its mover position (electrical angle) is equal to the mover magnetic flux position. Therefore, when the mover magnetic flux is within the range of 30°-90°, the back electromotive force corresponding to phase B in the three-phase back electromotive forces is the largest, and the back electromotive force corresponding to phase A is the smallest. At this time, by configuring appropriate drive signals for the IGBTs on the bridge arm, controlling the IGBT corresponding to the upper bridge arm of the bridge arm connected to the B-phase stator winding to conduct to control phase B to connect to the DC bus P, and controlling the IGBT corresponding to the lower bridge arm of the bridge arm connected to the A-phase stator winding to conduct to control phase A to connect to N, the other IGBTs in the three-phase bridge arm are all kept off, and phase C is floating. At this time, the equivalent circuit of the motor drive circuit is as Figure 6 shown, the current direction of the motor is as shown by the arrow in the figure, flowing in from phase A and flowing out from phase B, so as to achieve the maximization of the electromagnetic torque. After adding the drive circuit, the circuit schematic of the entire motor is as Figure 8 shown.

[0080] It is not difficult to understand that the switching control mode of the entire six-step commutation method and the corresponding vector direction of the stator current are shown in Table 1. The essence of the six-step commutation method is to ensure that the angle between the stator current vector and the rotor flux linkage vector remains between 60° and 120° to maintain a relatively constant torque. During the entire operating cycle, the rotor flux linkage position is divided into six intervals, and there are a total of six switching modes, so it is called the six-step commutation method. The switching table of the six-step commutation method is shown in Table 1, where + represents the positive pole P of the DC bus connected to the corresponding phase, and - represents the negative pole N of the DC bus connected to the corresponding phase.

[0081] Table 1 Switching Table of Permanent Magnet Linear Synchronous Motor

[0082] Specifically, the six-step commutation of the permanent magnet linear synchronous motor is realized by dividing the rotor flux linkage position into six intervals and configuring six switching modes of the corresponding drive circuit. The IGBT drive signal can be directly output according to the rotor position of the motor, which is simple and effective and easy to implement. Based on the voltage vector control algorithm of six-step commutation, the motor outputs the maximum thrust; thus ensuring that the permanent magnet linear synchronous motor always maintains the maximum thrust during the operation of closed-loop control and improving the working efficiency.

[0083] As an alternative embodiment, the rotor position is determined according to the back electromotive force of the permanent magnet linear synchronous motor to control the operation of the permanent magnet linear synchronous motor based on the rotor position, including:

[0084] Determine the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor;

[0085] Based on the zero-crossing point of the back electromotive force, determine the rotor position to control the permanent magnet linear synchronous motor based on the rotor position.

[0086] It can be understood that the back electromotive force is the electromotive force generated when the rotor magnetic field cuts the stator winding during the operation of the motor. The back electromotive force is proportional to the rotor position and speed. Among them, the zero-crossing point of the back electromotive force of each phase corresponds to a specific position of the rotor. As Figure 7 shown, when the back electromotive force of phase A is zero, the spatial position of the rotor flux linkage , so the discontinuous flux linkage angle positioning can be realized through the zero-crossing point detection of the back electromotive force, thereby realizing the determination of the rotor position. Especially when the zero-crossing point detection is combined with six-step commutation, the zero-crossing point detection can not only be used to estimate the rotor position of the motor, but also help to determine the switching moment of six-step commutation. The duration of each switching mode during six-step commutation is 60° electrical angle, and the midpoint moment within this 60° range is the moment when the back electromotive force of the floating phase is 0. As Figure 7 shown, , The moment corresponds to the midpoint moment of the switching patterns of A+ and B-, and A+ and C-. It can be seen that if this moment, that is, the zero-crossing point of the back electromotive force of phase A, can be accurately captured, and then a delay of 30° is applied, it is the moment to switch to the switching pattern of A+ and C-.

[0087] Furthermore, in addition to the collision detection algorithm, the protection algorithm of the motor also includes an overload detection algorithm. During the operation of the motor, by detecting the average value of the DC current in real time for each step of operation and determining whether the difference between the current means of two adjacent steps exceeds the load current. If it exceeds, an overload is determined, and the number of overloads is calculated through a threshold (such as a three-level counting mechanism). When necessary, such as when the number of overloads exceeds the counting threshold, a frequency reduction operation is performed to reduce the vibration of the mover and the heating of the motor. Introducing the overload detection algorithm, decelerating or stopping when necessary to prevent the motor from losing steps during operation and avoid insulation problems caused by overcurrent in the motor.

[0088] Specifically, the identification of the mover position is realized by zero-crossing detection, which is combined with the control process of starting and stopping the motor to achieve sensorless control of the motor. The accurate control of the motor is realized by adopting a combined control strategy of IF soft start + IF soft stop + six-step commutation + protection algorithm. The entire control process has weak dependence on parameters, reducing control failures caused by motor parameter mismatch.

[0089] Please refer to Figure 9 , Figure 9 FIG.

[0090] Obtain the phase voltages of the three-phase windings in the stator winding of the permanent magnet linear synchronous motor;

[0091] Determine the average voltage of the phase voltages of the three-phase windings and calculate the difference between the preset phase voltage and the average voltage;

[0092] Determine the zero-crossing point of the difference between the preset phase voltage and the average voltage as the zero-crossing point of the preset back electromotive force.

[0093] It is not difficult to understand that specifically, the zero-crossing points of the back electromotive forces of each phase can be determined by calculating the phase voltages. The preset phases include phase A, phase B, and phase C of the motor. Taking phase A as an example, the calculation formula for detecting the zero-crossing point of the back electromotive force is deduced. The hardware system (such as a voltage sensor) is used to measure the voltages of the three-phase stator windings of the motor with respect to the DC bus N point, that is, the voltage between phase A and the DC bus N point 、the voltage between phase B and the DC bus N point 、the voltage between phase C and the DC bus N point Taking the N point of the DC bus as the voltage reference point, the three-phase voltage equation of the motor is obtained as follows:

[0094] ;

[0095] Wherein, is the phase inductance of the stator winding, is the resistance of the motor stator winding, is the current of the stator phase A winding, is the current of the stator phase B winding, is the current of the stator phase C winding, is the back electromotive force of the motor phase A winding, is the back electromotive force of the motor phase B winding, is the back electromotive force of the motor phase C winding, is the voltage between the common connection point O of the three-phase windings of the stator and the N point of the DC bus. Then, according to Kirchhoff's current law and six-step commutation, we get:

[0096] ;

[0097] Wherein, is the sign function, represents , , The summation of, so by capturing The zero crossing of can obtain the zero crossing of the floating-phase back electromotive force.

[0098] As a specific embodiment, the back electromotive force waveform of a 660V submersible linear motor at 18Hz is as shown in Figure 9 , and it can be clearly seen from Figure 9 the rationality of detecting the back electromotive force zero crossing through the phase voltage. Through comprehensive theoretical analysis and simulation, it can be obtained that it is feasible to implement sensorless control of a brushless DC motor using the zero crossing detection scheme.

[0099] It should be noted that the only basis for motor commutation is whether the sector where the magnetic flux is located changes, and zero crossing detection can be used for sector judgment. At the same time, since the calculation of the phase voltage requires the resistance of the stator winding, the step of obtaining the resistance of the stator winding can also be added before zero crossing detection to prevent the motor from malfunctioning.

[0100] Specifically, the six-step commutation method enhances the accuracy of motor control, and at the same time calculates the back electromotive force using the phase voltage, so as to determine the back electromotive force zero crossing through phase voltage detection, and then judge the sector where the vector voltage is located. Only by collecting the voltage and current signals of the stator can the control of the motor be realized, which is simple, effective, and easy to implement.

[0101] As a specific embodiment, please refer to Figure 10 , Figure 10 which is a schematic structural diagram of a control system for a permanent magnet linear synchronous motor provided by the present invention; the structure of the control system for the permanent magnet linear synchronous motor is as shown in Figure 10 . The control system includes an AC / DC (Alternating Current / Direct Current) inverter circuit and a frequency converter. The frequency converter includes an inductor L0 connected in series, a capacitor C0 connected in parallel, and a three-phase bridge arm composed of switching devices S A , S B , S C , S A ’, S B ’, S C ’. The frequency converter outputs three-phase currents to the motor PMLSM. The control board collects the voltage signals u ABC (voltages of three phases A, B, and C) and current signals i ABC (currents of three phases A, B, and C) of the stator to generate corresponding switching drive signals S ABC (drive signals of S A , S B , S C ), S ABC ’ (drive signals of S A ’, S B ’, S C ’), and executes protection algorithms such as collision detection. The control system only needs to collect the voltage and current signals of the stator to achieve the control of the motor, and adopts the control strategy as shown in Figure 2 . In addition, the control system can also realize the protection of the main circuit and the motor by detecting the voltage, current, and temperature in the motor. The control board can also be connected to an HMI (Human Machine Interface) and a DTU (Data Transfer unit) for communication with other devices. The control board can also establish communication with downhole measurement devices to obtain parameters such as oil well temperature and pressure through the downhole measurement devices, so as to control the motor according to the actual situation of the oil well. The frequency converter in the control system operates according to as shown in Figure 2The control strategy shown drives the motor to run. Then, the three-phase voltage and current during the operation of the frequency converter are detected by voltage sensors and current sensors and displayed on an oscilloscope to conduct experimental verification of the motor operation. It can be seen from the measured waveforms that the voltage waveforms of the three phases of the output of the frequency converter with respect to the DC bus as a reference and the current waveforms of the phase A current are consistent with the simulation curves, and the voltage shows obvious trapezoidal wave characteristics with freewheeling pulses. The measured waveforms indicate that the sensorless control scheme using zero-crossing sampling is feasible. This control algorithm enables the AC motor to obtain the control characteristics of a DC motor and can greatly improve the control performance.

[0102] To solve the above technical problems, the present invention also provides a control device for a permanent magnet linear synchronous motor, including:

[0103] A starting unit for controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector to control the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; the amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset law;

[0104] An operating unit for, when the speed of the mover reaches a preset speed, determining the position of the mover according to the back electromotive force of the permanent magnet linear synchronous motor to control the operation of the permanent magnet linear synchronous motor based on the position of the mover;

[0105] A stopping unit for controlling the stator to synthesize a second target current vector to control the mover of the permanent magnet linear synchronous motor to stop with uniform deceleration based on the second target current vector; the amplitude of the second target current vector is a second preset amplitude, and the slope of the second target current vector gradually decreases from the second preset value to zero based on a second preset law.

[0106] As an optional embodiment, it further includes:

[0107] A magnetic positioning unit for injecting a current signal with a preset frequency into the stator winding of the permanent magnet linear synchronous motor before controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector to determine the initial position of the mover of the permanent magnet linear synchronous motor.

[0108] As an optional embodiment, the operating unit includes:

[0109] A back electromotive force acquisition unit for acquiring the instantaneous values of the three-phase back electromotive force of the permanent magnet linear synchronous motor;

[0110] A commutation unit for controlling the voltage application mode between the three-phase bridge arm and the DC bus in the drive circuit of the permanent magnet linear synchronous motor based on the magnitude relationship between the instantaneous values of the three-phase back electromotive force.

[0111] As an alternative embodiment, the commutation unit includes:

[0112] A first commutation sub-unit, configured to control the arm of the drive circuit of the permanent magnet linear synchronous motor corresponding to the phase with the maximum back electromotive force to connect to the positive pole of the DC bus;

[0113] A second commutation sub-unit, configured to control the arm of the drive circuit corresponding to the phase with the minimum back electromotive force to connect to the negative pole of the DC bus;

[0114] A third commutation sub-unit, configured to control the arm of the drive circuit corresponding to the phase with the intermediate back electromotive force to be floating.

[0115] As an alternative embodiment, the operation unit includes:

[0116] A zero-crossing detection unit, configured to determine the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor;

[0117] An operation sub-unit, configured to determine the mover position based on the zero-crossing point of the back electromotive force, so as to control the permanent magnet linear synchronous motor based on the mover position.

[0118] As an alternative embodiment, the zero-crossing detection unit includes:

[0119] A phase voltage acquisition unit, configured to acquire the phase voltages of the three-phase windings in the stator windings of the permanent magnet linear synchronous motor;

[0120] A calculation unit, configured to determine the voltage average value of the phase voltages of the three-phase windings, and calculate the difference between a preset phase voltage and the voltage average value;

[0121] A zero-crossing detection sub-unit, configured to determine the zero-crossing point of the difference between the preset phase voltage and the voltage average value as the zero-crossing point of the preset back electromotive force.

[0122] For the introduction of a control device for a permanent magnet linear synchronous motor provided by the present invention, please refer to the embodiments of the control method for the permanent magnet linear synchronous motor described above, and the present invention will not be elaborated herein.

[0123] Please refer to Figure 11 , Figure 11 which is a schematic structural diagram of an electronic device provided by the present invention. To solve the above technical problems, the present invention also provides an electronic device, including:

[0124] A memory 21, configured to store a computer program;

[0125] A processor 22, configured to implement the steps of the control method for the permanent magnet linear synchronous motor as described above.

[0126] Among them, the processor 22 may include one or more processing cores, such as a 4-core processor, an 8-core processor, etc. The processor 22 may be implemented in at least one hardware form of DSP (Digital Signal Processor), FPGA (Field-Programmable Gate Array), or PLA (Programmable Logic Array). The processor 22 may also include a main processor and a coprocessor. The main processor is a processor used to process data in the wake state, also known as the central processor; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 22 may integrate a GPU (graphics processing unit), and the GPU is responsible for rendering and drawing the content to be displayed on the display screen. In some embodiments, the processor 22 may further include an AI (Artificial Intelligence) processor, and the AI processor is used to process computational operations related to machine learning.

[0127] The memory 21 may include one or more computer-readable storage media, and the computer-readable storage media may be non-transitory. The memory 21 may further include high-speed random access memory and non-volatile memory, such as one or more disk storage devices and flash storage devices. In this embodiment, the memory 21 is at least used to store the following computer programs. After the computer programs are loaded and executed by the processor 22, the relevant steps of the control method of the permanent magnet linear synchronous motor disclosed in any one of the foregoing embodiments can be implemented. In addition, the resources stored in the memory 21 may further include an operating system and data, etc., and the storage method may be temporary storage or permanent storage. Among them, the operating system may include Windows, Unix, Linux, etc. The data may include, but is not limited to, data of the control method of the permanent magnet linear synchronous motor, etc.

[0128] In some embodiments, the electronic device may further include a display screen, an input / output interface 25, a communication interface 24, a power supply 23, and a communication bus 26.

[0129] Those skilled in the art can understand that Figure 11 the structure shown in

[0130] does not constitute a limitation on the electronic device, and it may include more or fewer components than those shown in the figure.

[0131] To solve the above technical problems, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method of the permanent magnet linear synchronous motor as described above are implemented.

[0132] It can be understood that if the method in the above embodiments is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and executes all or part of the steps of the methods described in the various embodiments of the present application. Specifically, the computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical discs, mobile hard disks, etc., or any type of medium or device suitable for storing instructions and data, etc. The present application does not make special limitations here.

[0133] For the introduction of the computer-readable storage medium provided by the present invention, please refer to the embodiments of the control method of the permanent magnet linear synchronous motor above, and the present invention will not be elaborated here.

[0134] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple. For the relevant parts, please refer to the description of the method part. Professionals can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been generally described according to their functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0135] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a permanent magnet linear synchronous motor, characterized in that Including: Controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, and controlling the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; The amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset rule; When the speed of the mover reaches a preset speed, determining the mover position according to the back electromotive force of the permanent magnet linear synchronous motor, and controlling the operation of the permanent magnet linear synchronous motor based on the mover position; Controlling the stator of the permanent magnet linear synchronous motor to synthesize a second target current vector, and controlling the mover of the permanent magnet linear synchronous motor to stop with uniform deceleration based on the second target current vector; The amplitude of the second target current vector is a second preset amplitude, and the slope of the second target current vector gradually decreases from the second preset value to zero based on a second preset rule.

2. The control method of the permanent magnet linear synchronous motor according to claim 1, wherein Before controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, it further includes: Injecting a current signal with a preset frequency into the stator winding of the permanent magnet linear synchronous motor to determine the initial position of the mover of the permanent magnet linear synchronous motor.

3. The control method of the permanent magnet linear synchronous motor according to any one of claims 1 to 2, characterized in that Controlling the operation of the permanent magnet linear synchronous motor includes: Obtaining the instantaneous values of the three-phase back electromotive force of the permanent magnet linear synchronous motor; Based on the magnitude relationship between the instantaneous values of the three-phase back electromotive force, controlling the voltage application mode between the three-phase bridge arm and the DC bus in the drive circuit of the permanent magnet linear synchronous motor.

4. The control method of the permanent magnet linear synchronous motor according to claim 3, characterized in that Based on the magnitude relationship between the instantaneous values of the three-phase back electromotive force, controlling the voltage application mode between the three-phase bridge arm and the DC bus in the drive circuit of the permanent magnet linear synchronous motor, including: Controlling the bridge arm corresponding to the phase with the largest back electromotive force in the drive circuit of the permanent magnet linear synchronous motor to connect to the positive pole of the DC bus; Controlling the bridge arm corresponding to the phase with the smallest back electromotive force in the drive circuit to connect to the negative pole of the DC bus; Controlling the bridge arm corresponding to the phase with the intermediate back electromotive force in the drive circuit to be suspended.

5. The control method of the permanent magnet linear synchronous motor according to claim 4, characterized in that Determining the mover position according to the back electromotive force of the permanent magnet linear synchronous motor, and controlling the operation of the permanent magnet linear synchronous motor based on the mover position, including: Determining the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor; Based on the zero-crossing point of the back electromotive force, determining the mover position and controlling the permanent magnet linear synchronous motor based on the mover position.

6. The control method of the permanent magnet linear synchronous motor according to claim 5, characterized in that, Determining the zero-crossing point of the back electromotive force of the permanent magnet linear synchronous motor includes: Obtaining the phase voltages of the three-phase windings in the stator winding of the permanent magnet linear synchronous motor; Determining the voltage average value of the phase voltages of the three-phase windings, and calculating the difference between the preset phase voltage and the voltage average value; Determining the zero-crossing point of the difference between the preset phase voltage and the voltage average value as the zero-crossing point of the preset back electromotive force.

7. A control device for a permanent magnet linear synchronous motor, characterized in that, Including: A starting unit for controlling the stator of the permanent magnet linear synchronous motor to synthesize a first target current vector, and controlling the mover of the permanent magnet linear synchronous motor to start with uniform acceleration based on the first target current vector; the amplitude of the first target current vector is a first preset amplitude, and the slope of the first target current vector gradually increases from zero to a first preset value based on a first preset rule; An operating unit, configured to determine the position of the mover according to the back electromotive force of the permanent magnet linear synchronous motor when the speed of the mover reaches a preset speed, so as to control the operation of the permanent magnet linear synchronous motor based on the position of the mover; A shutdown unit, configured to control the stator to synthesize a second target current vector, so as to control the mover of the permanent magnet linear synchronous motor to decelerate uniformly to a stop based on the second target current vector; The amplitude of the second target current vector is a second preset amplitude, and the slope of the second target current vector gradually decreases from a second preset value to zero based on a second preset rule.

8. An electronic device, characterized in that, Comprising: A memory, configured to store a computer program; A processor, configured to implement the steps of the control method of the permanent magnet linear synchronous motor according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, and when the computer program is executed by the processor, the steps of the control method of the permanent magnet linear synchronous motor according to any one of claims 1 to 6 are implemented.

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