Torque current mode switching thin film capacitor motor system control method

Abstract

The application relates to a torque current mode switching thin film capacitor motor system control method. The method comprises the following steps: obtaining a reference value of input current according to a power grid phase angle and an equivalent input current, and obtaining an average value of torque current according to the running power and the rotating speed of a motor system; determining a current switching mode according to the power grid voltage, the DC side voltage, the average value of the DC side voltage and the voltage required by the motor system, and determining the reference value of the torque current as the reference value of the input current, the average value of the torque current or zero according to the current switching mode; obtaining a target q-axis voltage according to the reference value of the torque current and the actual torque current; obtaining a target d-axis voltage according to the reference value of the excitation current and the actual excitation current; obtaining the driving voltage of the motor system according to the target q-axis voltage and the target d-axis voltage, and driving and controlling the motor system according to the driving voltage. The method can timely optimize the current reference value when the voltage drops, and can avoid the early occurrence of current cut-off.

Description

Technical Field

[0001] This application relates to the field of thin-film capacitor motor system control, and in particular to a control method, system, computer device, computer-readable storage medium, and computer program product for a thin-film capacitor motor system with torque-current mode switching. Background Technology

[0002] In the field of thin-film capacitor motor control, replacing traditional electrolytic capacitors on the DC side of the motor control system with small-capacity thin-film capacitors can significantly improve system efficiency and power density, and enhance system reliability. However, the removal of electrolytic capacitors also brings new challenges: the DC side energy buffering capacity decreases, leading to increased voltage fluctuations and forcing an increase in the conduction angle of the uncontrolled rectifier bridge. This characteristic, however, eliminates the need for an input power factor correction circuit, thereby reducing system size and cost. With the power factor correction circuit removed, optimizing the system power factor becomes a critical issue. Ideally, the minimum DC bus voltage can be zero, at which point the input current is fully conducting and the power factor is close to 1. However, in actual operation, the presence of the motor's back electromotive force prevents the minimum DC voltage from dropping to zero, causing a reduction in the input current conduction angle and consequently a decrease in the power factor.

[0003] However, existing power factor correction methods do not fully consider the impact of DC voltage drops and do not deeply analyze the impact of input current cutoff on the system, resulting in the conduction angle and power factor being lower than expected. Summary of the Invention

[0004] Based on this, it is necessary to provide a control method, system, computer device, computer-readable storage medium, and computer program product for a thin-film capacitor motor system that can optimize the current reference value in a timely manner when the voltage drops, avoid premature current cutoff, thereby increasing the conduction angle and improving the input power factor, in order to address the above-mentioned technical problems.

[0005] In a first aspect, this application provides a control method for a thin-film capacitor motor system with torque-current mode switching, comprising:

[0006] The reference value of the input current is obtained based on the grid phase angle and the equivalent input current, and the average value of the torque current is obtained based on the operating power and speed of the motor system.

[0007] Based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, the current switching mode is determined, and the reference value of the torque current is determined according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0008] Based on the reference value and actual torque current, the target q-axis voltage is obtained; based on the reference value and actual excitation current, the target d-axis voltage is obtained.

[0009] Based on the target q-axis voltage and the target d-axis voltage, the driving voltage of the motor system is obtained, and the motor system is driven and controlled according to the driving voltage.

[0010] In one embodiment, the grid phase angle is obtained by converting the measured grid input voltage through a phase-locked loop;

[0011] The process of obtaining the reference value of the input current based on the grid phase angle and the equivalent input current includes:

[0012] Obtain the absolute value of the sine of the phase angle of the power grid;

[0013] The reference value of the input current is obtained by multiplying the equivalent input current by the absolute value of the sine of the phase angle of the power grid.

[0014] In one embodiment, the method further includes:

[0015] Obtain the phase angle adjustment factor;

[0016] Based on the phase angle adjustment factor, the power grid phase angle is corrected to obtain the corrected power grid phase angle;

[0017] The reference value of the input current is obtained by multiplying the equivalent input current by the absolute value of the sine of the corrected grid phase angle.

[0018] In one embodiment, obtaining the phase angle adjustment factor includes:

[0019] Obtain the capacitance of the thin-film capacitor, the grid angular frequency, and the grid input voltage;

[0020] The phase angle adjustment factor is calculated based on the capacitance of the thin-film capacitor, the grid angular frequency, the grid input voltage, and the equivalent input current.

[0021] In one embodiment, obtaining the average value of the torque current based on the operating power and speed of the motor system includes:

[0022] Calculate the operating power of the motor system based on the d-axis voltage, q-axis voltage, actual excitation current, and actual torque current during the operation of the motor system.

[0023] The actual speed and flux linkage of the motor system are obtained, and the average value of the torque current is determined based on the operating power of the motor system, the actual speed, the flux linkage, and the actual torque current.

[0024] In one embodiment, determining the current switching mode based on the grid voltage, DC-side voltage, the average value of the DC-side voltage, and the voltage required by the motor system, and determining a reference value for the torque current according to the current switching mode, includes:

[0025] When the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is greater than or equal to the voltage required by the motor system, the current switching mode is determined to be mode one, and the reference value of the input current is determined as the reference value of the torque current.

[0026] When the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is less than the voltage required by the motor system, the current switching mode is determined to be mode two, and the average value of the torque current is determined as the reference value of the torque current.

[0027] When the grid voltage is less than the DC side voltage, the current switching mode is determined to be mode one, and the reference value of the torque current is set to zero.

[0028] Secondly, this application also provides a thin-film capacitor motor system with torque current mode switching, comprising:

[0029] The torque current calculation module is used to obtain a reference value of the input current based on the grid phase angle and the equivalent input current, and to obtain the average value of the torque current based on the operating power and speed of the motor system.

[0030] The torque current mode switching module is used to determine the current switching mode based on the grid voltage, DC side voltage, the average value of the DC side voltage and the voltage required by the motor system, and to determine the reference value of the torque current according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0031] The torque current control module is used to obtain the target q-axis voltage based on the reference value of the torque current and the actual torque current.

[0032] The excitation current control module is used to obtain the target d-axis voltage based on the reference value of the excitation current and the actual excitation current.

[0033] The drive control module is used to obtain the drive voltage of the motor system based on the target q-axis voltage and the target d-axis voltage, and to perform drive control on the motor system based on the drive voltage.

[0034] Thirdly, this application also provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0035] The reference value of the input current is obtained based on the grid phase angle and the equivalent input current, and the average value of the torque current is obtained based on the operating power and speed of the motor system.

[0036] Based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, the current switching mode is determined, and the reference value of the torque current is determined according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0037] Based on the reference value and actual torque current, the target q-axis voltage is obtained; based on the reference value and actual excitation current, the target d-axis voltage is obtained.

[0038] Based on the target q-axis voltage and the target d-axis voltage, the driving voltage of the motor system is obtained, and the motor system is driven and controlled according to the driving voltage.

[0039] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0040] The reference value of the input current is obtained based on the grid phase angle and the equivalent input current, and the average value of the torque current is obtained based on the operating power and speed of the motor system.

[0041] Based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, the current switching mode is determined, and the reference value of the torque current is determined according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0042] Based on the reference value and actual torque current, the target q-axis voltage is obtained; based on the reference value and actual excitation current, the target d-axis voltage is obtained.

[0043] Based on the target q-axis voltage and the target d-axis voltage, the driving voltage of the motor system is obtained, and the motor system is driven and controlled according to the driving voltage.

[0044] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0045] The reference value of the input current is obtained based on the grid phase angle and the equivalent input current, and the average value of the torque current is obtained based on the operating power and speed of the motor system.

[0046] Based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, the current switching mode is determined, and the reference value of the torque current is determined according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0047] Based on the reference value and actual torque current, the target q-axis voltage is obtained; based on the reference value and actual excitation current, the target d-axis voltage is obtained.

[0048] Based on the target q-axis voltage and the target d-axis voltage, the driving voltage of the motor system is obtained, and the motor system is driven and controlled according to the driving voltage.

[0049] The aforementioned control method, system, computer equipment, computer-readable storage medium, and computer program product for a thin-film capacitor motor system with torque-current mode switching first obtains a reference value for the input current based on the grid phase angle and equivalent input current, and obtains an average value for the torque current based on the operating power and speed of the motor system. Then, based on the grid voltage, DC-side voltage, the average value of the DC-side voltage, and the voltage required by the motor system, the current switching mode is determined. According to the current switching mode, the reference value for the torque current is determined to be either the reference value of the input current, the average value of the torque current, or zero. Further, based on the reference value of the torque current and the actual torque current, the target q-axis voltage is obtained; based on the reference value of the excitation current and the actual excitation current, the target d-axis voltage is obtained; finally, based on the target q-axis voltage and the target d-axis voltage, the drive voltage of the motor system is obtained, and the motor system is driven and controlled based on the drive voltage. This method considers the impact of DC-side voltage drops in the thin-film capacitor motor system and constructs torque current reference value switching logic based on the motor system's operating conditions. This switching logic integrates the grid voltage, DC-side voltage, average DC-side voltage, and the voltage required by the motor system to determine the switching mode in real time. Specifically, it first compares the grid voltage and the DC-side voltage, and then compares the average DC-side voltage with the voltage required by the motor system. This allows the reference value of the torque current to switch between different modes, improving the input power factor. Through precise voltage monitoring and dynamic adjustment, the current reference value can be optimized in a timely manner when the voltage drops, preventing premature current cutoff, thereby increasing the conduction angle and improving the input power factor. This solves the problems of traditional methods that do not fully consider the impact of DC voltage drops, do not deeply analyze the impact of input current cutoff on the system, and do not achieve dynamic switching of the torque current reference value. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a circuit diagram of a thin-film capacitor motor system in one embodiment;

[0052] Figure 2 This is a flowchart illustrating a thin-film capacitor compressor control method with torque current mode switching in one embodiment.

[0053] Figure 3 This is a graph showing the relationship between a reference value of the input current and the capacitor current in one embodiment;

[0054] Figure 4 This is a schematic diagram of the torque current calculation module in one embodiment;

[0055] Figure 5 This is a schematic diagram illustrating the logic for determining the current switching mode in one embodiment;

[0056] Figure 6 This is a schematic diagram of a torque current mode switching module in one embodiment;

[0057] Figure 7 This is a control block diagram of a thin-film capacitor motor system with torque current mode switching in one embodiment;

[0058] Figure 8 The waveforms of the grid voltage and input current in the existing technology are shown.

[0059] Figure 9 The image shows the waveforms of the grid voltage and input current when this method is applied in one embodiment.

[0060] Figure 10 This is a structural block diagram of a thin-film capacitor motor system with torque current mode switching in one embodiment;

[0061] Figure 11 This is an internal structural diagram of a computer device in one embodiment. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0063] It should be noted that the terms "comprising" and "having" as used in this application, and any variations thereof, are intended to cover non-exclusive inclusion.

[0064] Figure 1 The circuit diagram of a thin-film capacitor motor system shown in one embodiment is as follows: the grid input voltage is passed through an uncontrolled rectifier bridge to obtain the DC side voltage. The DC side is a small-capacity thin-film capacitor, which causes the DC side voltage to fluctuate. The inverter then drives and controls the motor system.

[0065] Based on the above motor system, this application proposes a thin-film capacitor compressor control method with torque-current mode switching. Figure 2 This is a flowchart illustrating the method. In this embodiment, the method includes the following steps:

[0066] Step S210: Obtain a reference value for the input current based on the grid phase angle and the equivalent input current, and obtain the average value of the torque current based on the operating power and speed of the motor system.

[0067] The following sections provide a detailed explanation of the calculation of the reference value of the input current and the average value of the torque current.

[0068] For the calculation of the reference value of the input current:

[0069] First, the grid input voltage is measured. The measured grid input voltage is then converted using a phase-locked loop (PLL) to obtain the grid phase angle. Finally, the equivalent input current is determined based on the given and actual speeds of the motor system. Then, a reference value for the input current is calculated using the grid phase angle and the equivalent input current.

[0070] In one exemplary embodiment, obtaining a reference value for the input current based on the grid phase angle and the equivalent input current includes: obtaining the absolute value of the sine of the grid phase angle; and multiplying the equivalent input current by the absolute value of the sine of the grid phase angle to obtain the reference value for the input current.

[0071] Specifically, it involves collecting the grid input voltage. The measured grid input voltage Obtain the grid phase angle through a phase-locked loop. And, the given speed of the motor system. and actual speed The difference is calculated, and the equivalent input current is obtained through the speed control module. Utilizing the power grid phase angle and equivalent input current The reference value of the input current is calculated. The calculation process is shown in formula (1):

[0072] (1)

[0073] Furthermore, considering the effect of the thin-film capacitor current on the grid phase angle... This can cause phase deviation. Therefore, this application also proposes a method for correcting the grid phase angle. In some embodiments, the method further includes: obtaining a phase angle adjustment factor; correcting the grid phase angle based on the phase angle adjustment factor to obtain a corrected grid phase angle; and multiplying the equivalent input current by the absolute value of the sine of the corrected grid phase angle to obtain a reference value for the input current.

[0074] The relationship between the reference value of the input current and the capacitor current is as follows: Figure 3 As shown, capacitor current It can be represented as:

[0075] (2)

[0076] in, This indicates the capacitance of the film capacitor. Indicates the angular frequency of the power grid. This is the DC side voltage.

[0077] based on Figure 3 The relationship between the reference value of the input current and the capacitor current, as shown in formula (2), is used to determine the phase angle adjustment factor. In some embodiments, obtaining the phase angle adjustment factor includes: obtaining the capacitance of the thin-film capacitor, the grid angular frequency, and the grid input voltage; and calculating the phase angle adjustment factor based on the capacitance of the thin-film capacitor, the grid angular frequency, the grid input voltage, and the equivalent input current.

[0078] Specifically, when calculating the phase angle adjustment factor based on the film capacitor's capacitance, grid angular frequency, grid input voltage, and equivalent input current, the film capacitor's capacitance is first considered. Grid angular frequency and grid input voltage Multiply them to obtain the product of the three factors and the equivalent input current. The ratio of is used to calculate the arctangent of this ratio, which is then used as the phase angle adjustment factor, denoted as . The calculation process can be expressed as:

[0079] (3)

[0080] Furthermore, based on the phase angle adjustment factor, the grid phase angle is corrected. Specifically, the grid phase angle is subtracted from the phase angle correction factor to obtain the corrected grid phase angle. The equivalent input current is multiplied by the absolute value of the sine of the corrected grid phase angle to obtain a reference value for the input current.

[0081] Therefore, the reference value of the input current The calculation formula (1) can be modified as follows:

[0082] (4)

[0083] For the calculation of the average value of torque current:

[0084] First, obtain the operating power and actual speed of the motor system. Then, calculate the average value of the torque current based on the operating power and actual speed of the motor system.

[0085] Specifically, in an exemplary embodiment, obtaining the average value of torque current based on the operating power and speed of the motor system includes: calculating the operating power of the motor system based on the d-axis voltage, q-axis voltage, actual excitation current, and actual torque current during the operation of the motor system; obtaining the actual speed and flux linkage of the motor system; and determining the average value of torque current based on the operating power, actual speed, flux linkage, and actual torque current of the motor system.

[0086] Specifically, the d-axis voltage and q-axis voltage during the operation of the motor system are first obtained, and the phase current of the motor system is analyzed. , and The transformation is performed using the position angle of the motor system. The actual excitation current and actual torque current are obtained. The product of the d-axis voltage and the actual excitation current, and the product of the q-axis voltage and the actual torque current are calculated. The products of the two are added together to obtain the operating power of the motor system. The calculation process is shown in formula (5).

[0087] (5)

[0088] in, The operating power of the motor system, , These are the d-axis voltage and q-axis voltage during the operation of the motor system. and These are the actual excitation current and the actual torque current, respectively.

[0089] Further calculate the product of the actual speed, flux linkage and actual torque current of the motor system, obtain the ratio of the operating power of the motor system to the product, and then obtain the average value of the torque current. The calculation process is shown in formula (6).

[0090] (6)

[0091] in, This represents the average value of the torque current. The actual speed of the motor system For the magnetic flux linkage of the motor system.

[0092] In some implementations, step S210 can be achieved through a torque current calculation module. (See reference...) Figure 4 This is a schematic diagram of a torque current calculation module according to one embodiment, where the input is the grid phase angle. Equivalent input current Grid phase angle adjustment factor d-axis voltage during motor system operation q-axis voltage Actual excitation current Actual torque current and the actual speed of the motor system The output is a reference value for the input current. and the average value of torque current .

[0093] Step S220: Determine the current switching mode based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, and determine the reference value of the torque current according to the current switching mode; the reference value of the torque current is the reference value of the input current, the average value of the torque current or zero.

[0094] The voltage required by the motor system is based on the d-axis voltage during motor system operation. and q-axis voltage Determined, specifically can be expressed as .

[0095] In an exemplary embodiment, step S220 further includes: when the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is greater than or equal to the voltage required by the motor system, determining the current switching mode as mode one, and determining the reference value of the input current as the reference value of the torque current; when the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is less than the voltage required by the motor system, determining the current switching mode as mode two, and determining the average value of the torque current as the reference value of the torque current; when the grid voltage is less than the DC side voltage, determining the current switching mode as mode one, and determining the reference value of the torque current as zero.

[0096] Specifically, the logic for determining the current switching mode is as follows: First, the grid voltage is compared with the DC-side voltage. When the grid voltage is less than the DC-side voltage, the system directly enters Mode 3, obtains the reference value of the torque current under Mode 3, and exits the current switching logic. When the grid voltage is greater than or equal to the DC-side voltage, it further determines whether the average value of the DC-side voltage can meet the voltage requirements of the motor system. When the average value of the DC-side voltage can meet the voltage requirements of the motor system, the system enters Mode 1, obtains the reference value of the torque current under Mode 1. Conversely, when the average value of the DC-side voltage cannot meet the voltage requirements of the motor system, the system enters Mode 2, obtains the reference value of the torque current under Mode 2.

[0097] In other words, Mode 1 indicates that the grid voltage is greater than the DC-side voltage, and the average value of the DC-side voltage is sufficient to meet the voltage requirements of the motor system; Mode 2 indicates that the grid voltage is greater than the DC-side voltage, but the average value of the DC-side voltage is insufficient to meet the voltage requirements of the motor system; Mode 3 indicates that the grid voltage is less than the DC-side voltage, i.e.:

[0098]

[0099] in, Indicates the grid voltage. Indicates the DC side voltage. This represents the average value of the DC-side voltage. This indicates the voltage required by the motor system.

[0100] Furthermore, after determining the current switching mode, the reference value of the torque current can be determined according to the current switching mode, whether it is the reference value of the input current, the average value of the torque current, or zero.

[0101] Specifically, in Mode 1, the grid voltage and DC-side voltage meet the operating requirements of the motor system, and the reference value of the torque current is in the form of a half-sine wave, which can follow the fluctuations of the DC-side voltage and improve the input power factor. In Mode 2, the DC-side voltage cannot meet the operating requirements of the motor system, and the reference value of the torque current is in the form of an approximate DC current to reduce the vibration of the motor system. In Mode 3, the grid voltage is lower than the DC-side voltage, and the reference value of the torque current is 0, which can effectively prevent overcharging of the DC-side voltage from causing system overvoltage. Thus, the reference values ​​of the torque current in different switching modes are obtained. for:

[0102]

[0103] In other words, in Mode 1, the reference value of the input current is determined as the reference value of the torque current; in Mode 2, the average value of the torque current is determined as the reference value of the torque current; and in Mode 3, the reference value of the torque current is zero.

[0104] To more clearly explain the switching logic of the switching mode, the following is in conjunction with the appendix. Figure 5 Further explanation is needed. (See reference.) Figure 5 This is an example illustrating the method based on the grid voltage. DC side voltage Average value of DC side voltage Voltage required by the motor system A logic diagram for determining the current switching mode. When the grid voltage... Less than DC side voltage When the grid voltage is high, it directly enters mode three; when the grid voltage is low... Greater than or equal to DC side voltage Then, further determine the average value of the DC side voltage. Whether it can meet the voltage requirements of the motor system, if the average value of the DC side voltage is... Able to meet the voltage requirements of the motor system, that is If the condition is true, then enter mode one. Otherwise, enter mode two.

[0105] In some implementations, step S220 can be achieved by a torque current mode switching module. Figure 6 A schematic diagram of the torque current mode switching module is shown, with the mains voltage as the input. DC side voltage Average value of DC side voltage Voltage required by the motor system Based on the designed switching logic, the reference value of the input current is... and the average value of torque current Switch to another device.

[0106] This implementation method considers the impact of DC-side voltage drops in the film capacitor motor system. Based on the motor system's operating conditions, when the DC-side voltage is insufficient to maintain the required voltage for the motor system, the reference value of the torque current is switched. By fully considering the fluctuations in the DC-side voltage of the film capacitor motor system and the voltage requirements of the motor system, overcharging of the DC-side voltage leading to system overvoltage is effectively prevented, while simultaneously improving the system's input power factor.

[0107] Step S230: Obtain the target q-axis voltage based on the reference value of the torque current and the actual torque current; obtain the target d-axis voltage based on the reference value of the excitation current and the actual excitation current.

[0108] The reference value for the excitation current is 0.5 times the demagnetizing current, which is determined based on the magnetic flux linkage and d-axis inductance of the motor system.

[0109] Specifically, the reference value of the torque current and actual torque current The two are compared, and the error between them is adjusted by the torque current control module to obtain the target q-axis voltage. And, the reference value of the excitation current. and actual excitation current The comparison is performed, and the error is adjusted by the excitation current control module to obtain the target d-axis voltage. .

[0110] Step S240: Based on the target q-axis voltage and the target d-axis voltage, obtain the driving voltage of the motor system, and perform drive control on the motor system based on the driving voltage.

[0111] Specifically, in obtaining the target q-axis voltage and target d-axis voltage Then, the two can be modulated using the SVPWM (Space Vector Pulse Width Modulation) method to obtain the driving voltage of the motor system, thereby driving and controlling the motor system according to the driving voltage.

[0112] In the aforementioned control method for a thin-film capacitor motor system with torque-current mode switching, a reference value for the input current is first obtained based on the grid phase angle and equivalent input current, and an average value for the torque current is obtained based on the operating power and speed of the motor system. Then, based on the grid voltage, DC-side voltage, the average value of the DC-side voltage, and the voltage required by the motor system, the current switching mode is determined. According to this current switching mode, the reference value for the torque current is determined to be either the reference value of the input current, the average value of the torque current, or zero. Further, based on the reference value of the torque current and the actual torque current, the target q-axis voltage is obtained; based on the reference value of the excitation current and the actual excitation current, the target d-axis voltage is obtained; finally, based on the target q-axis voltage and the target d-axis voltage, the drive voltage of the motor system is obtained, and the motor system is driven and controlled based on this drive voltage. This method considers the impact of DC-side voltage drops in the thin-film capacitor motor system and constructs a torque current reference value switching logic based on the motor system's operating conditions. This switching logic integrates the grid voltage, DC-side voltage, average DC-side voltage, and the voltage required by the motor system to determine the switching mode in real time. Specifically, it first compares the grid voltage and the DC-side voltage, and then compares the average DC-side voltage with the voltage required by the motor system. This allows the reference value of the torque current to switch between different modes, improving the input power factor. Through precise voltage monitoring and dynamic adjustment, the current reference value can be optimized in a timely manner when the voltage drops, preventing premature current cutoff, thereby increasing the conduction angle and improving the input power factor. This solves the problems of traditional methods that do not fully consider the impact of DC voltage drops, do not deeply analyze the impact of input current cutoff on the system, and do not achieve dynamic switching of the torque current reference value.

[0113] To more clearly illustrate the torque-current mode switching control method for thin-film capacitor motor systems provided in this application, the following is in conjunction with the appendix. Figure 7 This plan will be further explained.

[0114] Figure 7 A control block diagram of a thin-film capacitor motor system with torque-current mode switching is shown. (See diagram below.) Figure 7 As shown, the system includes a speed control module, a phase-locked loop, a torque and current calculation module, a torque and current mode switching module, a torque and current control module, an excitation current control module, and a coordinate transformation module. Wherein:

[0115] In the speed control module: the given speed from the motor system is utilized. and actual speed By subtracting the input current, we obtain the equivalent input current. .

[0116] In a phase-locked loop: using the measured grid input voltage Obtain the phase angle of the power grid .

[0117] In the torque and current calculation module: on the one hand, the power grid phase angle is utilized. Equivalent input current and phase angle adjustment factor The reference value of the input current is calculated. On the other hand, based on the d-axis voltage during the operation of the motor system... q-axis voltage Actual excitation current Actual torque current and the actual speed of the motor system The average value of the torque current is calculated. .

[0118] In the torque current mode switching module: utilizing the mains voltage DC side voltage Average value of DC side voltage Voltage required by the motor system Determine the switching mode. Based on the designed switching logic, obtain reference values ​​for the torque current under different switching modes. .

[0119] The coordinate transformation module is used to transform the acquired current of the motor system (including phase current). , and The transformation is performed using the position angle of the motor system. Obtain the actual excitation current and actual torque current .

[0120] The torque current control module is used to input the reference value of the torque current. and actual torque current By comparison, the target q-axis voltage is obtained. .

[0121] The excitation current control module is used to input the reference value of the excitation current. and actual excitation current By comparison, the target d-axis voltage is obtained. .

[0122] Based on the outputs of the torque current control module and the excitation current control module, the drive voltage of the motor system is obtained, thereby realizing the drive control of the motor system.

[0123] The effectiveness of this method can be determined by measuring the results using a waveform recording device. Figure 8 The waveforms of the grid voltage and input current when the method provided in this application is not implemented are shown below. Figure 8It can be seen that there is a serious distortion in the input current, which will affect the power factor of the grid input. The effective value of the corresponding input current is 2.90A. Figure 9 The waveforms of the grid voltage and input current are provided to illustrate the implementation of the method described in this application. Figure 9 It can be seen that the waveform of the input current is effectively improved and the distortion can be suppressed, which is conducive to improving the power factor of the grid input. The effective value of the corresponding input current is 2.99A.

[0124] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0125] Based on the same inventive concept, this application also provides a thin-film capacitor motor system for implementing the torque-current mode switching control method for the thin-film capacitor motor system described above. The solution provided by this system is similar to the implementation described in the above method. Therefore, the specific limitations of one or more embodiments of the thin-film capacitor motor system with torque-current mode switching provided below can be found in the limitations of the control method for the thin-film capacitor motor system with torque-current mode switching described above, and will not be repeated here.

[0126] In one exemplary embodiment, such as Figure 10 As shown, a thin-film capacitor motor system with torque-current mode switching is provided, comprising:

[0127] The torque current calculation module 1001 is used to obtain a reference value of the input current based on the grid phase angle and the equivalent input current, and to obtain the average value of the torque current based on the operating power and speed of the motor system.

[0128] The torque current mode switching module 1002 is used to determine the current switching mode based on the grid voltage, DC side voltage, the average value of DC side voltage and the voltage required by the motor system, and to determine the reference value of torque current according to the current switching mode. The reference value of torque current is the reference value of input current, the average value of torque current or zero.

[0129] The torque current control module 1003 is used to obtain the target q-axis voltage based on the reference value of the torque current and the actual torque current.

[0130] The excitation current control module 1004 is used to obtain the target d-axis voltage based on the reference value of the excitation current and the actual excitation current.

[0131] The drive control module 1005 is used to obtain the drive voltage of the motor system based on the target q-axis voltage and the target d-axis voltage, and to drive the motor system according to the drive voltage.

[0132] In one embodiment, the grid phase angle is obtained by converting the measured grid input voltage through a phase-locked loop; the torque current calculation module 1001 is also used to obtain the absolute value of the sine value of the grid phase angle; the equivalent input current is multiplied by the absolute value of the sine value of the grid phase angle to obtain a reference value of the input current.

[0133] In one embodiment, the torque current calculation module 1001 is further configured to obtain a phase angle adjustment factor; based on the phase angle adjustment factor, correct the grid phase angle to obtain a corrected grid phase angle; and multiply the equivalent input current by the absolute value of the sine of the corrected grid phase angle to obtain a reference value for the input current.

[0134] In one embodiment, the torque current calculation module 1001 is further configured to obtain the capacitance of the thin-film capacitor, the grid angular frequency, and the grid input voltage; and to calculate the phase angle adjustment factor based on the capacitance of the thin-film capacitor, the grid angular frequency, the grid input voltage, and the equivalent input current.

[0135] In one embodiment, the torque current calculation module 1001 is further configured to calculate the operating power of the motor system based on the d-axis voltage, q-axis voltage, actual excitation current, and actual torque current during the operation of the motor system; obtain the actual speed and flux linkage of the motor system; and determine the average value of the torque current based on the operating power, actual speed, flux linkage, and actual torque current of the motor system.

[0136] In one embodiment, the torque current mode switching module 1002 is further configured to: determine the current switching mode as mode one and set the reference value of the input current as the reference value of the torque current when the grid voltage is greater than or equal to the DC side voltage and the average value of the DC side voltage is greater than or equal to the voltage required by the motor system; determine the current switching mode as mode two and set the average value of the torque current as the reference value of the torque current when the grid voltage is greater than or equal to the DC side voltage and the average value of the DC side voltage is less than the voltage required by the motor system; and determine the current switching mode as mode one and set the reference value of the torque current to zero when the grid voltage is less than the DC side voltage.

[0137] The modules in the aforementioned torque-current mode switching thin-film capacitor motor system can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the computer device's memory as software, so that the processor can call and execute the corresponding operations of each module.

[0138] In one exemplary embodiment, a computer device is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 11 As shown, the computer device includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, Near Field Communication (NFC), or other technologies. When executed by the processor, the computer program implements a torque-current mode switching control method for a thin-film capacitor motor system. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the computer device can be a touch layer covering the display screen, or buttons, trackballs, or touchpads set on the casing of the computer device, or external keyboards, touchpads, or mice, etc.

[0139] Those skilled in the art will understand that Figure 11 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0140] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0141] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the above method embodiments.

[0142] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above method embodiments.

[0143] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0144] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0145] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A control method for a thin-film capacitor motor system with torque-current mode switching, characterized in that, The method includes: The reference value of the input current is obtained based on the grid phase angle and the equivalent input current, and the average value of the torque current is obtained based on the operating power and speed of the motor system. Based on the grid voltage, DC side voltage, average DC side voltage and the voltage required by the motor system, the current switching mode is determined, and the reference value of the torque current is determined according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero. Based on the reference value and actual torque current, the target q-axis voltage is obtained; based on the reference value and actual excitation current, the target d-axis voltage is obtained. Based on the target q-axis voltage and the target d-axis voltage, the driving voltage of the motor system is obtained, and the motor system is driven and controlled according to the driving voltage.

2. The method according to claim 1, characterized in that, The grid phase angle is obtained by converting the measured grid input voltage through a phase-locked loop; The process of obtaining the reference value of the input current based on the grid phase angle and the equivalent input current includes: Obtain the absolute value of the sine of the phase angle of the power grid; The reference value of the input current is obtained by multiplying the equivalent input current by the absolute value of the sine of the phase angle of the power grid.

3. The method according to claim 2, characterized in that, The method further includes: Obtain the phase angle adjustment factor; Based on the phase angle adjustment factor, the power grid phase angle is corrected to obtain the corrected power grid phase angle; The reference value of the input current is obtained by multiplying the equivalent input current by the absolute value of the sine of the corrected grid phase angle.

4. The method according to claim 3, characterized in that, The process of obtaining the phase angle adjustment factor includes: Obtain the capacitance of the thin-film capacitor, the grid angular frequency, and the grid input voltage; The phase angle adjustment factor is calculated based on the capacitance of the thin-film capacitor, the grid angular frequency, the grid input voltage, and the equivalent input current.

5. The method according to claim 1, characterized in that, The method of obtaining the average value of torque current based on the operating power and speed of the motor system includes: Calculate the operating power of the motor system based on the d-axis voltage, q-axis voltage, actual excitation current, and actual torque current during the operation of the motor system. The actual speed and flux linkage of the motor system are obtained, and the average value of the torque current is determined based on the operating power of the motor system, the actual speed, the flux linkage, and the actual torque current.

6. The method according to claim 1, characterized in that, The process of determining the current switching mode based on the grid voltage, DC-side voltage, the average value of the DC-side voltage, and the voltage required by the motor system, and determining the reference value of the torque current according to the current switching mode, includes: When the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is greater than or equal to the voltage required by the motor system, the current switching mode is determined to be mode one, and the reference value of the input current is determined as the reference value of the torque current. When the grid voltage is greater than or equal to the DC side voltage, and the average value of the DC side voltage is less than the voltage required by the motor system, the current switching mode is determined to be mode two, and the average value of the torque current is determined as the reference value of the torque current. When the grid voltage is less than the DC side voltage, the current switching mode is determined to be mode one, and the reference value of the torque current is set to zero.

7. A thin-film capacitor motor system with torque-current mode switching, characterized in that, The system includes: The torque current calculation module is used to obtain a reference value of the input current based on the grid phase angle and the equivalent input current, and to obtain the average value of the torque current based on the operating power and speed of the motor system. The torque current mode switching module is used to determine the current switching mode based on the grid voltage, DC side voltage, the average value of the DC side voltage and the voltage required by the motor system, and to determine the reference value of the torque current according to the current switching mode. The reference value of the torque current is the reference value of the input current, the average value of the torque current or zero. The torque current control module is used to obtain the target q-axis voltage based on the reference value of the torque current and the actual torque current. The excitation current control module is used to obtain the target d-axis voltage based on the reference value of the excitation current and the actual excitation current. The drive control module is used to obtain the drive voltage of the motor system based on the target q-axis voltage and the target d-axis voltage, and to perform drive control on the motor system based on the drive voltage.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

Images