Method and system for controlling a synchronous machine

Abstract

The application discloses a synchronous motor control method and system. The synchronous motor control method is applied to a synchronous motor control system, and comprises the following steps: acquiring real-time feedback rotating speed of the motor; acquiring a speed setting instruction input by a user; determining a speed control instruction based on the speed setting instruction and the real-time feedback rotating speed, so that a driving member drives the motor to rotate based on the speed control instruction; acquiring current operating current of the motor; and adjusting the speed control instruction based on the current operating current, so that the driving member drives the motor to rotate based on the adjusted speed control instruction, until a difference between current feedback rotating speeds of the motors is less than a first preset difference. By adopting the above scheme, the balance of operating current of each working motor is ensured, the service life of the motor is prolonged, the motor can be flexibly applied to different motor coupling control fields, and the number of coupled motors is not limited.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a control method and system for a synchronous motor. Background Technology

[0002] Motor coupling control is widely used in the field of asynchronous motors, where multiple asynchronous motors drive a load simultaneously. Due to the slip of asynchronous motors, predetermined control functions can be achieved relatively easily. In the field of synchronous motors, since there is no slip effect, the synchronous control of multiple motors requires position sensors for position feedback to achieve the corresponding control functions. Because encoders are expensive and their signals are easily interfered with, synchronous motor coupling control is limited to low-power synchronous motors in high-precision applications. In related technologies, when multiple motors control a load, the output current of each motor is unbalanced, resulting in different heating levels for each motor. The motor with higher heating levels has a shorter lifespan and is more prone to damage than the motor with lower heating levels. Summary of the Invention

[0003] This invention provides a control method and system for a synchronous motor to extend the service life of the motor.

[0004] According to one aspect of the present invention, a control method for a synchronous motor is provided. This control method is applied to a control system for a synchronous motor. The control system includes a coupling controller, a drive unit, and a motor. The drive unit and the motor are multiple in number and connected in a one-to-one correspondence. The coupling controller is electrically connected to the drive unit. The control method for the synchronous motor includes:

[0005] Obtain the real-time feedback speed of the motor;

[0006] Get the speed setting command input by the user;

[0007] Based on the speed setting command and the real-time feedback rotation speed, a speed control command is determined so that the drive unit drives the motor to rotate based on the speed control command.

[0008] Obtain the current operating current of the motor;

[0009] The speed control command is adjusted based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command until the difference between the current feedback speeds of the multiple motors is less than a first preset difference.

[0010] The speed control command is increased based on the difference between the current feedback speed of the motor and the speed control command, so that the drive unit drives the motor to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference.

[0011] In an optional embodiment of the present invention, adjusting the speed control command based on the current operating current includes:

[0012] The speed control command is adjusted in the form of negative feedback based on the current operating current.

[0013] In an optional embodiment of the present invention, adjusting the speed control command based on the current operating current in the form of negative feedback includes:

[0014] Based on the current operating current, the speed control command is reduced by a preset amount using the following formula:

[0015] F = I * K;

[0016] Where I is the current operating current; K is the reduction ratio; and F is the preset reduction magnitude.

[0017] In an optional embodiment of the present invention, the speed control command determined based on the speed setting command and the real-time feedback rotational speed includes:

[0018] Determine the speed difference between the speed setting command and the real-time feedback rotation speed;

[0019] Based on the speed difference, a speed control command is determined using a PID control algorithm.

[0020] In an optional embodiment of the present invention, the expression of the PID control algorithm is:

[0021]

[0022] Where Kp is the proportional constant, Ti is the integral time constant, Td is the derivative time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

[0023] In an optional embodiment of the present invention, the drive unit includes a frequency converter;

[0024] The step of obtaining the real-time feedback speed of the motor includes:

[0025] Obtain the real-time feedback speed of the motor estimated by the frequency converter.

[0026] In an optional embodiment of the present invention, determining the speed control command based on the speed setting command and the real-time feedback rotation speed, so that the drive unit drives the motor to rotate based on the speed control command, includes:

[0027] Based on the speed setting command and the real-time feedback rotation speed, a speed control command is determined so that the frequency converter outputs a drive frequency based on the speed control command to drive the motor to rotate.

[0028] Accordingly, adjusting the speed control command based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command includes:

[0029] The speed control command is adjusted based on the current operating current, so that the frequency converter outputs a drive frequency based on the adjusted speed control command to drive the motor to rotate.

[0030] According to another aspect of the present invention, a control system for a synchronous motor is provided, the control system for the synchronous motor including a coupling controller, a drive unit and a motor;

[0031] There are multiple drive components and motors, and they are connected in a one-to-one correspondence. The drive component is used to drive the motor to rotate.

[0032] The coupling controller is electrically connected to the drive component;

[0033] The coupling controller is used to execute the synchronous motor control method described in any embodiment of the present invention.

[0034] In an optional embodiment of the present invention, the drive unit includes a frequency converter;

[0035] The frequency converter is used to output a drive frequency to drive the motor to rotate; and / or, the frequency converter is used to estimate the real-time feedback speed of the motor.

[0036] In an optional embodiment of the invention, the coupling controller includes a PLC.

[0037] The technical solution of this invention involves: acquiring the real-time feedback speed of the motor; acquiring a speed setting command input by the user; determining a speed control command based on the speed setting command and the real-time feedback speed, so that the drive component drives the motor to rotate based on the speed control command; acquiring the current operating current of the motor; adjusting the speed control command based on the current operating current, so that the drive component drives the motor to rotate based on the adjusted speed control command, until the difference between the current feedback speeds of multiple motors is less than a first preset difference; and finally increasing the speed control command based on the difference between the current feedback speed of the motor and the speed control command, so that the drive component drives the motor to rotate based on the increased speed control command, until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference. This allows the speed control command to change according to the current operating current of the motor, thereby balancing the load of each motor. This solves the problem of uneven output current of each motor when multiple motors control a load, leading to different heating rates for each motor. Motors with higher heating rates have shorter lifespans and are more prone to damage than those with lower heating rates. This ensures a balanced operating current for each working motor and extends the motor's lifespan. It can be flexibly applied in different motor coupling control fields, without limiting the number of coupled motors.

[0038] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a structural block diagram of the control system of the synchronous motor used in the control method of the synchronous motor provided in Embodiment 1 of the present invention;

[0041] Figure 2 This is a flowchart of a synchronous motor control method provided in Embodiment 1 of the present invention;

[0042] Figure 3 This is a structural block diagram of another synchronous motor control system used in the synchronous motor control method provided in Embodiment 1 of the present invention;

[0043] Figure 4This is a flowchart of a synchronous motor control method provided in Embodiment 2 of the present invention.

[0044] The components include: 1. Coupler controller; 2. Drive unit; 21. Frequency converter; 3. Motor. Detailed Implementation

[0045] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0046] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0047] Example 1

[0048] Figure 1 This is a structural block diagram of the control system of the synchronous motor used in the synchronous motor control method provided in Embodiment 1 of the present invention. Figure 2 This is a flowchart of a synchronous motor control method provided in Embodiment 1 of the present invention. This embodiment is applicable to situations where multiple motors are coupled and controlled. The synchronous motor control method is applied to a synchronous motor control system, such as... Figure 1 As shown, the control system of the synchronous motor includes a coupling controller, a drive unit, and a motor. Multiple drive units and motors are connected in a one-to-one correspondence. The coupling controller is electrically connected to the drive units. The inputs to the coupling controller are the real-time feedback speed of the motor and the speed setting command input by the user. The output of the coupling controller is the input to the drive unit. The drive unit drives the motor to rotate based on the inputs. In this embodiment, the control method of the synchronous motor can be applied to the coupling controller, which executes the control method of the synchronous motor through hardware and / or software methods. Figure 2 As shown, the control method for the synchronous motor includes:

[0049] S110. Obtain the real-time feedback speed of the motor.

[0050] Among them, the real-time feedback speed of the motor refers to the actual speed value of the motor under the current operating state.

[0051] S120, Obtain the speed setting command input by the user.

[0052] The speed setting command input by the user refers to the motor speed value that the user sets to be reached.

[0053] S130. Based on the speed setting command and the real-time feedback rotation speed, determine the speed control command so that the drive unit drives the motor to rotate based on the speed control command.

[0054] The speed control command is an instruction that specifies the required rotational speed for the drive motor. Since there are multiple drive units, each drive unit controls its corresponding connected motor to operate at the speed specified in the speed control command.

[0055] S140. Obtain the current operating current of the motor.

[0056] The current operating current refers to the current when the motor is currently running. When multiple motors control the load, the current operating current of each motor will be different.

[0057] S150. Adjust the speed control command based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command until the difference between the current feedback speeds of the multiple motors is less than a first preset difference.

[0058] The current feedback speed refers to the current actual speed of the motor. When the load of each motor tends to be balanced, the actual speed of each motor will tend to be equal, that is, the difference between the current feedback speeds of multiple motors is less than the first preset difference.

[0059] When the drive unit controls the corresponding connected motors to run according to the speed control command, each motor receives the same speed control command, but their current operating current will be different. At this time, by adjusting the corresponding speed control command according to the current operating current of each motor, the speed control command can be changed according to the current operating current of the motor, thereby balancing the load of each motor and extending the service life of the motor.

[0060] S160. Based on the difference between the current feedback speed of the motor and the speed control command, the speed control command is increased so that the drive unit drives the motor to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference.

[0061] Through the aforementioned continuous adjustment process, the load of each motor eventually tends to be balanced. During this process, the increase in current causes a decrease in the motor's operating speed, resulting in the actual load speed being lower than the set speed. That is, when the load of each motor tends to be balanced, the current feedback speed of the motor will be lower than the speed setting command. Simultaneously, due to accuracy requirements, the actual load speed and the set speed cannot be perfectly synchronized and will have some fluctuation. When the difference between the speed setting command and the real-time feedback speed is less than a second preset difference, it indicates that the difference between the speed setting command and the real-time feedback speed is small and tends to be consistent. The magnitude of the second preset difference reflects the control accuracy and is not specifically limited here; it can be set according to usage requirements.

[0062] Since the current feedback speed of the motor will be less than the speed setting command when the load of each motor tends to be balanced, the speed control command is increased based on the difference between the current feedback speed of the motor and the speed control command. This allows the drive unit to drive the motor to rotate based on the increased speed control command, so that the actual load speed is consistent with the set speed, thus achieving the final control objective.

[0063] For example, in a specific embodiment, assuming the speed setting command is 1000 RPM, the speed control command will control the drive unit to drive the motor to rotate at the required 1000 RPM. During motor rotation, due to load imbalance, the speed and current of different motors will differ. After continuous adjustment, the load will be balanced. However, when the load of each motor tends to be balanced, the current feedback speed of the motor will be less than the speed setting command, meaning each motor may stabilize at around 950 RPM. This illustrates that when a 1000 RPM command is given to send a speed control command, the actual speed when the load is balanced, i.e., the current feedback speed, can only be around 950 RPM, which is insufficient to achieve the control objective. Therefore, based on the difference between the current feedback speed and the speed control command, the speed control command is increased—that is, based on the difference of 50 RPM between 1000 RPM and 950 RPM—causing it to send a 1050 RPM command to control the drive unit to drive the motor to rotate at the required 1050 RPM. Thus, when the load of each motor tends to be balanced, the motor can reach the speed setting command of 1000 RPM, achieving the final control objective.

[0064] The above solution involves: acquiring the real-time feedback speed of the motor; acquiring the speed setting command input by the user; determining a speed control command based on the speed setting command and the real-time feedback speed, so that the drive unit drives the motor to rotate according to the speed control command; acquiring the current operating current of the motor; adjusting the speed control command based on the current operating current, so that the drive unit drives the motor to rotate according to the adjusted speed control command, until the difference between the current feedback speeds of multiple motors is less than a first preset difference; and finally increasing the speed control command based on the difference between the current feedback speed of the motor and the speed control command, so that the drive unit drives the motor to rotate according to the increased speed control command, until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference. This allows the speed control command to change according to the current operating current of the motor, thereby balancing the load of each motor. This solves the problem of uneven output current of each motor when multiple motors control a load, leading to different heating rates for each motor. Motors with higher heating rates have shorter lifespans and are more prone to damage than those with lower heating rates. This solution ensures a balanced operating current for each working motor, extending the motor's lifespan. It can be flexibly applied in different motor coupling control fields, without limiting the number of coupled motors.

[0065] In an optional embodiment of the present invention, the speed control command determined based on the speed setting command and the real-time feedback rotational speed includes:

[0066] Determine the speed difference between the speed setting command and the real-time feedback rotation speed.

[0067] Based on the speed difference, a speed control command is determined using a PID control algorithm.

[0068] The speed difference reflects the deviation between the actual speed of the motor under its current operating condition and the speed that the user sets the motor should reach.

[0069] PID stands for Proportional, Integral, and Differential. As the name suggests, the PID control algorithm combines proportional, integral, and derivative components into a single control algorithm. It is the most mature and widely used control algorithm for continuous systems. This algorithm emerged in the 1930s and 40s and is suitable for situations where the model of the controlled object is not well understood. Practical experience and theoretical analysis both show that this control law can achieve satisfactory results when used to control many industrial processes. The essence of PID control is to calculate the output based on the input deviation value according to the proportional, integral, and derivative functional relationship, and use the result to control the output.

[0070] Therefore, through the PID control algorithm, if the motor load increases, the motor speed decreases, and the deviation between the speed set command and the real-time feedback speed increases (i.e., the speed difference increases). This leads to an increase in the speed control command of the drive components, increasing the motor speed and thus reducing the deviation between the speed set command and the real-time feedback speed. Conversely, if the motor load decreases, the motor speed increases, and the deviation between the speed set command and the real-time feedback speed decreases (i.e., the speed difference decreases). This leads to a decrease in the speed control command through the coupling controller, reducing the motor speed and thus reducing the deviation between the speed set command and the real-time feedback speed. After continuous adjustment, the real-time feedback speed approaches the speed set command, thereby achieving the goal of controlling the motor speed.

[0071] For example, the expression for the PID control algorithm is:

[0072]

[0073] Where Kp is the proportional constant, Ti is the integral time constant, Td is the derivative time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

[0074] The output signal of the PID control algorithm is the current control command. Using the above expression, the current control command can be easily determined based on the speed difference, thereby achieving control of the motor speed.

[0075] In optional embodiments of the present invention, such as Figure 3 As shown, the driving element ( Figure 3 (Not shown in the image) Includes frequency converters.

[0076] The step of obtaining the real-time feedback speed of the motor includes: obtaining the real-time feedback speed of the motor estimated by the frequency converter.

[0077] A variable-frequency drive (VFD) is a power control device that uses frequency conversion technology and microelectronics to control an AC motor by changing the frequency of the power supply. The main circuit of a VFD can be broadly divided into two categories: voltage-source VFDs, which convert DC voltage to AC, and current-source VFDs, which convert DC current to AC, and current-source VFDs, which convert DC current to AC, and current-source VFDs, which use inductors for DC filtering.

[0078] Since there is a certain relationship between the speed and frequency of a motor, the formula for motor speed and frequency is: n = 60f / p. When a frequency converter drives the motor to rotate, it will change the frequency of the motor's operating power supply. Therefore, the speed of the motor can be estimated through the frequency converter, that is, the speed can be fed back in real time.

[0079] The above scheme obtains the real-time feedback speed of the motor estimated by the frequency converter, and then obtains the speed setting command input by the user; based on the speed setting command and the real-time feedback speed, it determines the speed control command so that the drive unit drives the motor to rotate according to the speed control command; it obtains the current operating current of the motor; and finally, it adjusts the speed control command based on the current operating current so that the drive unit drives the motor to rotate according to the adjusted speed control command. This allows the speed loop to be completed through a coupled controller, and the result after PID calculation is used as the input to the current loop formed by the frequency converters. Each frequency converter independently controls the motor to operate in the current loop, avoiding the conflict problem between motor speeds that may occur if multiple frequency converters operate in the speed loop simultaneously. This solves the coupled control of multiple motors without position sensors, reduces the cost of coupled control, and increases the reliability of the system. It also ensures that the actual load speed matches the set speed, achieving the final control objective.

[0080] Based on the above embodiments, the step of determining the speed control command based on the speed setting command and the real-time feedback rotation speed, so that the drive unit drives the motor to rotate based on the speed control command, includes:

[0081] Based on the speed setting command and the real-time feedback rotation speed determination speed control command, the frequency converter outputs a drive frequency based on the speed control command to drive the motor to rotate.

[0082] Since there is a certain relationship between the motor speed and frequency, the formula for motor speed and frequency is: n = 60f / p. When the frequency converter drives the motor to rotate, it will change the frequency of the motor's operating power supply. Therefore, by outputting the corresponding drive frequency based on the speed control command of the frequency converter, the motor can be made to rotate. At the same time, the motor speed can be adjusted by adjusting the output drive frequency.

[0083] Based on the above embodiments, adjusting the speed control command based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command includes:

[0084] The speed control command is adjusted based on the current operating current, so that the frequency converter outputs a drive frequency based on the adjusted speed control command to drive the motor to rotate.

[0085] The frequency converter adjusts the motor speed by adjusting the drive frequency. Therefore, when the speed control command is adjusted, the frequency converter outputs the drive frequency based on the adjusted speed control command, which can change the motor speed.

[0086] Example 2

[0087] Figure 4This is a flowchart of a synchronous motor control method provided in Embodiment 2 of the present invention. Embodiment 2 is an improvement upon Embodiment 1. Optionally, adjusting the speed control command based on the current operating current includes: adjusting the speed control command in a negative feedback manner based on the current operating current. Figure 4 As shown, the control method for the synchronous motor includes:

[0088] S210. Obtain the real-time feedback speed of the motor.

[0089] S220, Obtain the speed setting command input by the user.

[0090] S230. Based on the speed setting command and the real-time feedback rotation speed, determine the speed control command so that the drive unit drives the motor to rotate based on the speed control command.

[0091] S240. Obtain the current operating current of the motor.

[0092] S250. Adjust the speed control command in the form of negative feedback based on the current operating current, so that the drive unit drives the motor to rotate based on the adjusted speed control command, until the difference between the current feedback speeds of the multiple motors is less than a first preset difference.

[0093] Negative feedback refers to the fact that the current operating current superimposed on the speed control command will weaken the speed control command, and the larger the current operating current, the greater the reduction in the speed control command.

[0094] S260. Based on the difference between the current feedback speed of the motor and the speed control command, the speed control command is increased so that the drive unit drives the motor to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference.

[0095] In the above scheme, when a speed setting command is manually set, the speed control command currently sent to each drive unit is calculated based on the speed setting command and the real-time feedback rotational speed. Multiple drive units control the motor running speed according to the issued speed control command. At this time, multiple motors have the same speed, but the current differs.

[0096] Based on the operating current of multiple motors, the current operating current of each motor is superimposed on its respective speed control command in the form of negative feedback. When the current of a certain motor increases, its actual speed control command will decrease. At this time, the speed control commands of other motors remain unchanged, and the speed of the motor decreases. Therefore, the actual load of the motor will decrease, thereby reducing the current of the motor.

[0097] The speed reduction is greatest for the motors with the heaviest load and smaller for those with the lightest load. Through continuous adjustment, the loads of the motors will eventually tend to balance. However, this is because the decrease in motor speed due to increased current will cause the actual load speed to be lower than the set speed. At this point, based on the magnitude of the load reduction (i.e., the difference between the speed setting command and the real-time feedback speed), the speed setpoint of the entire system is increased again, thereby making the actual load speed match the set speed, achieving the final control objective.

[0098] In an optional embodiment of the present invention, adjusting the speed control command based on the current operating current in the form of negative feedback includes:

[0099] Based on the current operating current, the speed control command is reduced by a preset amount using the following formula:

[0100] F = I * K.

[0101] Where I is the current operating current; K is the reduction ratio; and F is the preset reduction magnitude.

[0102] In this way, the amplitude of the speed control command decreases more for heavier loads, which makes the load lighter, while the amplitude of the speed control command decreases less for lighter loads. Continuous adjustment can balance the current among multiple motors.

[0103] Furthermore, in a specific embodiment, when the drive is a frequency converter, since the frequency converter changes the motor speed by changing the frequency, K is the set parameter frequency reduction ratio, and F is the magnitude of the frequency reduction.

[0104] Example 3

[0105] Embodiment 3 of the present invention discloses a control system for a synchronous motor, such as... Figure 1 As shown, the control system of the synchronous motor includes a coupling controller 1, a drive unit 2, and a motor 3.

[0106] There are multiple drive components 2 and motors 3, and they are connected in a one-to-one correspondence. The drive component 2 is used to drive the motor 3 to rotate.

[0107] The coupling controller 1 is electrically connected to the drive unit 2, and the coupling controller 1 is used to execute the control method of the synchronous motor in any embodiment of the present invention.

[0108] The inputs to the coupling controller are the real-time feedback speed of the motor and the speed setting command input by the user. The output of the coupling controller is the input to the drive unit. The drive unit drives the motor to rotate based on the inputs.

[0109] The above scheme, by setting up a coupling controller 1 and a drive unit 2, and electrically connecting the coupling controller 1 and the drive unit 2, allows the coupling controller 1 to acquire the real-time feedback speed of the motor 3; acquire the speed setting command input by the user; then determine the speed control command based on the speed setting command and the real-time feedback speed, so that the drive unit 2 drives the motor 3 to rotate according to the speed control command; finally, acquire the current operating current of the motor 3; adjust the speed control command based on the current operating current, so that the drive unit 2 drives the motor 3 to rotate according to the adjusted speed control command, until the difference between the current feedback speeds of multiple motors 3 is less than a first preset difference; and increase the speed control command based on the difference between the current feedback speed of the motor 3 and the speed control command, so that the drive unit 2 drives the motor 3 to rotate according to the increased speed control command, until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference. This ensures the balance of the operating current of each working motor 3, extending the life of the motor 3. It can be flexibly applied in different motor 3 coupling control fields, without limiting the number of coupled motors 3.

[0110] In an optional embodiment of the invention, the coupling controller 1 is further configured to adjust the speed control command in the form of negative feedback based on the current operating current.

[0111] Based on the above embodiments, the coupling controller 1 is also used to reduce the speed control command by a preset amount based on the current operating current using the following formula:

[0112] F = I * K.

[0113] Where I is the current operating current; K is the reduction ratio; and F is the preset reduction magnitude.

[0114] In an optional embodiment of the present invention, the coupling controller 1 is further configured to determine the speed difference between the speed setting command and the real-time feedback rotational speed; and to determine the speed control command based on the speed difference using a PID control algorithm.

[0115] For example, the expression for the PID control algorithm is:

[0116]

[0117] Where Kp is the proportional constant, Ti is the integral time constant, Td is the derivative time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

[0118] In optional embodiments of the present invention, such as Figure 3 As shown, drive component 2 ( Figure 3(Not shown) Includes a frequency converter 21, which is also used to estimate the real-time feedback speed of the motor 3; the coupling controller 1 is also used to obtain the real-time feedback speed of the motor 3 estimated by the frequency converter 21. The frequency converter 21 (Variable-frequency Drive, VFD) is a power control device that uses frequency conversion technology and microelectronics to control the AC motor by changing the frequency of the power supply to the motor 3. The main circuit of the frequency converter 21 can be broadly divided into two types: voltage-type frequency converters 21 that convert DC voltage to AC, with capacitors used for DC circuit filtering; and current-type frequency converters 21 that convert DC current to AC, with inductors used for DC circuit filtering.

[0119] Since the speed and frequency of motor 3 have a certain relationship, the formula for the speed and frequency of motor 3 is: n = 60f / p. When the frequency converter 21 drives motor 3 to rotate, it will change the operating power frequency of motor 3. Therefore, the speed of motor 3 can be estimated by the frequency converter 21, that is, the real-time feedback speed. Since the coupling controller 1 is electrically connected to the drive component 2, the coupling controller 1 can obtain the real-time feedback speed estimated by the frequency converter 21.

[0120] In an optional embodiment of the present invention, the coupling controller 1 includes a PLC.

[0121] Here, PLC (Programmable Logic Controller) refers to a programmable logic controller, which is a digital electronic system specifically designed for industrial applications. It employs a programmable memory to store instructions for performing logical operations, sequential control, timing, counting, and arithmetic operations, controlling various types of mechanical equipment or production processes through digital or analog inputs and outputs. Therefore, by including a PLC in the coupling controller 1, the synchronous motor control method described in any embodiment of this invention can be conveniently executed to achieve coupled control of multiple motors 3.

[0122] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A control method for a synchronous motor, characterized in that, In a control system for a synchronous motor, the control system for the synchronous motor includes a coupling controller, a drive unit, and a motor, wherein there are multiple drive units and motors, and they are connected in a one-to-one correspondence. The coupling controller is electrically connected to the drive component; The control method for the synchronous motor includes: Obtain the real-time feedback speed of the motor; Get the speed setting command input by the user; Based on the speed setting command and the real-time feedback rotation speed, a speed control command is determined so that the drive unit drives the motor to rotate based on the speed control command. Obtain the current operating current of the motor; The speed control command is adjusted based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command until the difference between the current feedback speeds of the multiple motors is less than a first preset difference. The speed control command is increased based on the difference between the current feedback speed of the motor and the speed setting command, so that the drive unit drives the motor to rotate based on the increased speed control command until the difference between the speed setting command and the real-time feedback speed is less than a second preset difference. The speed control command adjusted based on the current operating current includes: The speed control command is adjusted in the form of negative feedback based on the current operating current to achieve current balance among multiple motors; The step of adjusting the speed control command based on the current operating current in the form of negative feedback includes: Based on the current operating current, the speed control command is reduced by a preset amount using the following formula: F = I * K; Where I is the current operating current; K is the reduction ratio; and F is the preset reduction magnitude.

2. The control method for a synchronous motor according to claim 1, characterized in that, The speed control command based on the speed setting command and the real-time feedback rotation speed determination includes: Determine the speed difference between the speed setting command and the real-time feedback rotation speed; Based on the speed difference, a speed control command is determined using a PID control algorithm.

3. The control method for a synchronous motor according to claim 2, characterized in that, The expression for the PID control algorithm is: ； Where Kp is the proportional constant, Ti is the integral time constant, Td is the derivative time constant, u(t) is the output signal of the PID control algorithm, and e(t) is the speed difference.

4. The control method for a synchronous motor according to claim 1, characterized in that, The drive unit includes a frequency converter; The step of obtaining the real-time feedback speed of the motor includes: Obtain the real-time feedback speed of the motor estimated by the frequency converter.

5. The control method for a synchronous motor according to claim 4, characterized in that, The step of determining a speed control command based on the speed setting command and the real-time feedback rotation speed, so that the drive unit drives the motor to rotate based on the speed control command, includes: Based on the speed setting command and the real-time feedback rotation speed, a speed control command is determined so that the frequency converter outputs a drive frequency based on the speed control command to drive the motor to rotate. Accordingly, adjusting the speed control command based on the current operating current so that the drive unit drives the motor to rotate based on the adjusted speed control command includes: The speed control command is adjusted based on the current operating current, so that the frequency converter outputs a drive frequency based on the adjusted speed control command to drive the motor to rotate.

6. A control system for a synchronous motor, characterized in that, The control system of the synchronous motor includes a coupling controller (1), a drive unit (2), and a motor (3); The number of the driving component (2) and the motor (3) are both multiple and are connected in a one-to-one correspondence. The driving component (2) is used to drive the motor (3) to rotate. The coupling controller (1) is electrically connected to the drive unit (2); The coupling controller (1) is used to execute the control method of the synchronous motor according to any one of claims 1-5.

7. The control system for the synchronous motor according to claim 6, characterized in that, The drive unit (2) includes a frequency converter (21); The frequency converter (21) is used to output a drive frequency to drive the motor (3) to rotate; and / or, the frequency converter (21) is used to estimate the real-time feedback speed of the motor (3).

8. The control system for the synchronous motor according to claim 6 or 7, characterized in that, The coupling controller (1) includes a PLC.

Images