Phase current limit frequency reduction control method and device and related equipment

Abstract

The present application relates to a kind of phase current limit frequency control method, device and related equipment, belong to motor control technical field.The phase current limit frequency control method, device and related equipment, the frequency of compressor is controlled by three degrees of freedom, i.e., from the consideration of three degrees of freedom of the resultant phase current, direct-axis current and cross-axis current, set different threshold, limit frequency control is carried out, so that different limit frequency control method is used in different working conditions, guarantee the reliability of each working condition, so as to solve the technical problems that if motor limit frequency current value is set too large when adjusting based on single compressor phase current (i.e., the resultant phase current) in the prior art, it is easy to lead to step loss under heavy load and low frequency, if set too small, motor capacity cannot be fully utilized.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically relating to a phase current limiting frequency reduction control method, device, and related equipment. Background Technology

[0002] Air conditioners typically use a compressor as the power source for their motors. For inverter air conditioners, the compressor usually uses a permanent magnet synchronous motor. As people's demands for air conditioning capacity continue to increase, the operating frequency range of the motor is becoming wider. Simultaneously, air conditioners are required to operate under harsh conditions of extremely high and low temperatures, leading to increasingly larger variations in the motor's load torque. The complexity of air conditioning operating conditions necessitates suitable frequency limiting and derating control methods for permanent magnet synchronous motors to ensure reliability across the entire operating range while fully utilizing the motor's capabilities.

[0003] In related technologies, the phase current limiting frequency reduction method is based on the compressor phase current (i.e., the composite phase current) for adjustment. However, if the motor frequency reduction current value is set too high, it is easy to cause loss of synchronism at low and medium frequencies under heavy load. If it is set too low, the motor capacity will not be fully utilized.

[0004] Therefore, how to improve the existing phase current limiting frequency reduction control method to solve the above problems has become an urgent technical problem to be solved in the existing technology. Summary of the Invention

[0005] This invention provides a phase current limiting frequency reduction control method, device, and related equipment to solve the technical problem that when adjusting based on the compressor phase current (i.e., the composite phase current), if the motor limiting frequency reduction current value is set too high, it can easily lead to loss of synchronism at low and medium frequencies under heavy loads; if the value is set too low, the motor capacity cannot be fully utilized.

[0006] The technical solution provided by this invention is as follows:

[0007] A phase current limiting frequency reduction control method is applied to a permanent magnet synchronous motor, the method comprising:

[0008] Determine the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, the direct-axis current, and the quadrature-axis current;

[0009] Based on the pre-set target degree of freedom judgment order and correlation relationship, the value of each target degree of freedom and the corresponding threshold are judged, and phase current limit frequency reduction control is performed.

[0010] Optionally, the step of determining the value of each target degree of freedom and the corresponding threshold based on a pre-set target degree of freedom judgment order and correlation relationship, and performing frequency reduction control, includes:

[0011] Determine the value of the synthesized phase current and the magnitude of the preset synthesized phase current threshold; and control the compressor frequency according to the relationship between the value of the synthesized phase current and the preset synthesized phase current threshold; and determine the value of the quadrature axis current and the magnitude of the preset quadrature axis current threshold.

[0012] Based on the relationship between the value of the quadrature axis current and the preset quadrature axis current threshold, the compressor frequency is controlled, and the absolute value of the direct axis current is determined to be greater than or equal to the preset DC current threshold.

[0013] The compressor frequency is controlled based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold.

[0014] Optionally, determining the value of the composite phase current and its relationship with a preset composite phase current threshold, and controlling the compressor frequency based on this relationship, includes:

[0015] Determine whether the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold;

[0016] If the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold, the compressor is triggered to reduce the frequency.

[0017] If the value of the synthesized phase current is greater than the preset synthesized phase current frequency limiting current threshold and is less than or equal to the preset synthesized phase current frequency reduction current threshold, then the frequency increase of the compressor is restricted; wherein, the preset synthesized phase current frequency limiting current threshold is less than the preset synthesized phase current frequency reduction current threshold.

[0018] Optionally, determining the value of the quadrature-axis current and its relationship with a preset quadrature-axis current threshold, and controlling the compressor frequency based on this relationship, includes:

[0019] Determine whether the value of the quadrature-axis current is greater than a preset quadrature-axis current frequency reduction current threshold;

[0020] If the value of the quadrature axis current is greater than the preset quadrature axis current frequency reduction current threshold, the compressor is triggered to reduce the frequency.

[0021] If the value of the quadrature axis current is greater than the preset quadrature axis current frequency limiting current threshold and is less than or equal to the preset quadrature axis current frequency reducing current threshold, then the frequency increase of the compressor is restricted; wherein the preset quadrature axis current frequency limiting current threshold is less than the preset quadrature axis current frequency reducing current threshold.

[0022] Optionally, determining the magnitude of the absolute value of the direct-axis current and a preset DC current threshold, and controlling the compressor frequency based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold, includes:

[0023] Determine whether the absolute value of the direct-axis current is greater than a preset direct-axis current frequency reduction current threshold.

[0024] If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, the compressor is triggered to reduce its frequency.

[0025] If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, and is less than or equal to the preset direct-axis current frequency reduction threshold, then the frequency increase of the compressor is restricted; wherein, the preset direct-axis current frequency reduction threshold is less than the preset direct-axis current frequency reduction threshold.

[0026] Optional, also includes:

[0027] The preset direct-axis current reduction current threshold is less than the characteristic current of the permanent magnet synchronous motor. Optionally, before determining the target degree of freedom of the permanent magnet synchronous motor, the method further includes: determining that the permanent magnet synchronous motor is in the powered-on operating state.

[0028] On another front, a phase current limiting frequency reduction control device is applied to a permanent magnet synchronous motor, the device comprising:

[0029] The determination module is used to determine the value of the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, the direct-axis current, and the quadrature-axis current;

[0030] The control module is used to determine the value of each target degree of freedom and the corresponding threshold based on the pre-set target degree of freedom judgment order and correlation relationship, and to perform phase current limit frequency reduction control.

[0031] In another aspect, a phase current limiting frequency reduction control device includes: a processor, and a memory connected to the processor;

[0032] The memory is used to store a computer program, which is at least used to execute the phase current limiting frequency reduction control method described above.

[0033] The processor is used to call and execute the computer program in the memory.

[0034] In another aspect, an air conditioner is characterized by comprising a permanent magnet synchronous motor and the aforementioned phase current limiting frequency reduction control device; the permanent magnet synchronous motor is connected to the phase current limiting frequency reduction control device.

[0035] The technical solution provided by this invention has at least the following beneficial effects:

[0036] The compressor frequency is controlled by three degrees of freedom: the composite phase current, the direct-axis current, and the quadrature-axis current. Different thresholds are set to limit the frequency reduction, thus employing different frequency reduction control methods under different operating conditions to ensure reliability under each condition. This solves the technical problem in the existing technology where the frequency reduction limit current value is set too high when adjusting based on a single compressor phase current (i.e., composite phase current), which can easily lead to loss of synchronism at low and medium frequencies under heavy loads, while setting it too low will not allow the motor's capacity to be fully utilized. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a flowchart illustrating a phase current limiting frequency reduction control method according to an embodiment of the present invention;

[0039] Figure 2 This is a schematic diagram of a voltage limit ellipse provided in an embodiment of the present invention;

[0040] Figure 3 This is a schematic diagram of a phase current limiting frequency reduction control device according to an embodiment of the present invention;

[0041] Figure 4 This is a schematic diagram of a phase current limiting frequency reduction control device according to an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] As described in the background art, in related technologies, the phase current limiting frequency reduction method is based on the compressor phase current (i.e., the composite phase current) for adjustment. However, if the motor limiting frequency reduction current value is set too high, it is easy to cause loss of synchronism at low and medium frequencies under heavy load. If it is set too low, the motor capacity will not be fully utilized.

[0044] To at least address the technical problems raised in this invention, embodiments of this invention provide a phase current limiting frequency reduction control method, apparatus, and related equipment to solve the technical problem that when adjusting based on compressor phase current (i.e., composite phase current), if the motor limiting frequency reduction current value is set too high, it can easily lead to loss of synchronism at medium and low frequencies under heavy loads; if the value is set too low, the motor's capacity cannot be fully utilized.

[0045] Figure 1 This is a flowchart illustrating a phase current limiting frequency reduction control method according to an embodiment of the present invention. This method operates on an electronic device, which can be a general-purpose computer, server, or similar device. In practical applications, it can also be a data processing center, cloud platform, etc. This application does not limit the specific implementation of the aforementioned electronic device. Figure 1 As shown, the method provided in this embodiment of the invention may include the following steps:

[0046] S11. Determine the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, direct-axis current and quadrature-axis current;

[0047] S12. Based on the pre-set target degree of freedom judgment order and correlation relationship, determine the value of each target degree of freedom and the corresponding threshold, and perform phase current limit frequency reduction control.

[0048] In a specific implementation, the phase current limiting frequency reduction control method provided in this embodiment is applied to a permanent magnet synchronous motor, thereby controlling the compressor by controlling the frequency of the permanent magnet synchronous motor.

[0049] In permanent magnet synchronous motors The magnitudes of the combined phase current, direct-axis current, and quadrature-axis current can be obtained based on different operating conditions of the motor, which is existing technology and will not be elaborated here. In the vector control of permanent magnet synchronous motors, the current is decoupled into direct-axis and quadrature-axis components, i.e., direct-axis current and quadrature-axis current. Then, the phase current frequency reduction limit can also be based on the decoupled current to achieve more reasonable protection.

[0050] It is understood that the technical solution provided in this embodiment controls the compressor frequency through three degrees of freedom: the composite phase current, the direct-axis current, and the quadrature-axis current. Different thresholds are set to limit the frequency reduction, thereby employing different frequency reduction control methods under different operating conditions to ensure the reliability of each condition. This solves the technical problem in the prior art where, when adjusting based on a single compressor phase current (i.e., the composite phase current), if the motor frequency reduction current value is set too high, it can easily lead to loss of synchronization at low and medium frequencies under heavy loads; if it is set too low, the motor's capacity cannot be fully utilized.

[0051] In some embodiments, based on a pre-defined order and correlation of target degrees of freedom, the value of each target degree of freedom and the corresponding threshold are determined, and frequency reduction control is performed, including:

[0052] Determine the value of the synthesized phase current and its magnitude relative to a preset synthesized phase current threshold; and control the compressor frequency based on the relationship between the value of the synthesized phase current and the preset synthesized phase current threshold; and determine the value of the quadrature axis current and its magnitude relative to a preset quadrature axis current threshold.

[0053] Based on the relationship between the value of the quadrature axis current and the preset quadrature axis current threshold, the compressor frequency is controlled, and the absolute value of the direct axis current is compared with the preset DC current threshold.

[0054] The compressor frequency is controlled based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold.

[0055] During the judgment process, the system can be configured to first determine the magnitude of the composite phase current relative to a threshold, then determine the magnitude of the quadrature-axis current relative to a threshold, and finally determine the magnitude of the direct-axis current relative to a threshold. After each judgment, the corresponding control action is executed. Specifically, for the composite phase current, a composite phase current threshold can be preset, allowing for magnitude judgment after obtaining the composite phase current, and compressor frequency control based on the obtained magnitude relationship. For the quadrature-axis current, a quadrature-axis current threshold can be preset, allowing for magnitude judgment after obtaining the quadrature-axis current, and compressor frequency control based on the obtained magnitude relationship. For the direct-axis current, a direct-axis current threshold can be preset, allowing for magnitude judgment after obtaining the absolute value of the direct-axis current, and compressor frequency control based on the obtained magnitude relationship.

[0056] It is understood that by adopting the technical solution provided in this embodiment, the magnitude of the synthesized phase current and the threshold are determined first, then the magnitude of the quadrature axis current and the threshold are determined, and finally the magnitude of the direct axis current and the threshold are determined. After each determination, the corresponding control action is executed, thereby realizing the association of the three degrees of freedom, achieving adaptation to different working conditions, and ensuring the reliability of various working conditions.

[0057] In some embodiments, determining the magnitude of the composite phase current and a preset composite phase current threshold; and controlling the compressor frequency based on the relationship between the composite phase current and the preset composite phase current threshold, includes:

[0058] Determine whether the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold.

[0059] If the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold, the compressor is triggered to reduce the frequency.

[0060] If the value of the synthesized phase current is greater than the preset synthesized phase current frequency limiting current threshold and is less than or equal to the preset synthesized phase current frequency reduction current threshold, then the frequency increase of the compressor is restricted; wherein, the preset synthesized phase current frequency limiting current threshold is less than the preset synthesized phase current frequency reduction current threshold.

[0061] For example, in this embodiment, a preset composite phase current frequency reduction current threshold and a preset composite phase current frequency limiting current threshold can be preset for the composite phase current, wherein the preset composite phase current frequency limiting current threshold is less than the preset composite phase current frequency reduction current threshold.

[0062] Under the same motor control algorithm and parameters, appropriate phase current limiting frequency reduction control can fully utilize the motor's capabilities and improve reliability under various operating conditions. In this embodiment, it can first be determined whether the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold. If it is greater, the compressor frequency is triggered to decrease; if it is less than or equal to, and the value of the synthesized phase current is greater than the preset synthesized phase current frequency limiting current threshold, the compressor frequency increase is restricted. The preset synthesized phase current frequency reduction current threshold can be set based on the maximum current allowed to pass through the compressor phase line or the maximum current allowed by the motor.

[0063] It is understood that by adopting the technical solution provided in this embodiment, the composite phase current can be judged by preset composite phase current frequency limiting current threshold and preset composite phase current frequency reduction current threshold, so as to achieve adaptation to high-speed load conditions.

[0064] In some embodiments, determining the value of the quadrature-axis current and its relationship with a preset quadrature-axis current threshold; controlling the compressor frequency based on the relationship between the quadrature-axis current value and the preset quadrature-axis current threshold, including:

[0065] Determine whether the value of the quadrature-axis current is greater than the preset quadrature-axis current frequency reduction current threshold;

[0066] If the value of the quadrature axis current is greater than the preset quadrature axis current frequency reduction current threshold, the compressor is triggered to reduce the frequency.

[0067] If the value of the quadrature axis current is greater than the preset quadrature axis current frequency limiting current threshold and is less than or equal to the preset quadrature axis current frequency reducing current threshold, then the frequency increase of the compressor is restricted; wherein, the preset quadrature axis current frequency limiting current threshold is less than the preset quadrature axis current frequency reducing current threshold.

[0068] For example, in this embodiment, a preset cross-axis current frequency reduction threshold and a preset cross-axis current frequency limiting threshold can be preset for the cross-axis current, wherein the preset cross-axis current frequency limiting threshold is less than the preset cross-axis current frequency reduction threshold.

[0069] Under the same motor control algorithm and parameters, appropriate phase current limiting frequency reduction control can fully utilize the motor's capabilities and improve reliability under various operating conditions. In this embodiment, it can first be determined whether the value of the quadrature axis current is greater than the preset quadrature axis current frequency reduction current threshold. If it is greater, the compressor frequency is triggered to decrease; if it is less than or equal to, and the value of the quadrature axis current is greater than the preset quadrature axis current frequency limiting current threshold, the compressor frequency increase is restricted. The preset quadrature axis current frequency reduction current threshold can be set based on low-frequency heavy load reliability.

[0070] The quadrature-axis current reflects the magnitude of the motor's load torque and driving torque. Considering both motor control and the motor itself, the maximum driving torque that the motor can provide is higher at medium frequencies and lower at low and high frequencies. Furthermore, for single-rotor compressors, torque fluctuations make them more prone to instability at low frequencies.

[0071] It is understood that by adopting the technical solution provided in this embodiment, the quadrature axis current can be judged by setting a preset quadrature axis current frequency limiting current threshold and a preset quadrature axis current frequency reduction current threshold, thereby achieving adaptation to heavy load low-frequency operating conditions.

[0072] In some embodiments, determining the magnitude of the absolute value of the direct-axis current and a preset DC current threshold; controlling the compressor frequency based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold, including:

[0073] Determine whether the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction current threshold.

[0074] If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, the compressor is triggered to reduce its frequency.

[0075] If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, and is less than or equal to the preset direct-axis current frequency reduction threshold, then the frequency increase of the compressor is restricted; wherein, the preset direct-axis current frequency reduction threshold is less than the preset direct-axis current frequency reduction threshold.

[0076] For example, in this embodiment, a preset direct-axis current frequency reduction threshold and a preset direct-axis current frequency reduction threshold can be preset for the direct-axis current, wherein the preset direct-axis current frequency reduction threshold is less than the preset direct-axis current frequency reduction threshold.

[0077] Under the same motor control algorithm and parameters, appropriate phase current-limited frequency reduction control can fully utilize the motor's capabilities and improve reliability under various operating conditions. In this embodiment, it can first be determined whether the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold. If it is greater, the compressor is triggered to reduce its frequency; if it is less than or equal to, and the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, the compressor's frequency increase is restricted.

[0078] It is understood that by adopting the technical solution provided in this embodiment, the direct-axis current can be judged by setting a preset direct-axis current frequency reduction threshold, thereby achieving adaptation to light-load ultra-high-speed operating conditions.

[0079] In some embodiments, the method further includes: setting a direct-axis current reduction current threshold that is less than the characteristic current of the permanent magnet synchronous motor.

[0080] It is worth noting that the direct-axis current itself is less than or equal to 0. Therefore, in this application, the absolute value of the direct-axis current is compared with a preset value (the preset value is positive). If the preset direct-axis current frequency reduction domain value is limited to be less than the characteristic current of the motor, it can be guaranteed that the absolute value of the actual direct-axis current does not exceed the characteristic current of the motor.

[0081] In this embodiment, the relationship between motor speed and current is explained. Figure 2 This is a schematic diagram of a voltage limit ellipse provided in an embodiment of the present invention. (See attached diagram.) Figure 2 Iq represents the quadrature-axis current, and Id represents the direct-axis current. When the motor speed w1 < w2, the voltage limit ellipse... Contraction occurs, at which point the absolute value of the direct current increases, such as... Figure 2 The current trajectory is shown in the diagram. Stable operation is achieved when the voltage limit circle intersects with the current trajectory. To ensure this intersection, the absolute value of the direct-axis current should be limited to the motor's characteristic current. the following.

[0082] In some embodiments, it is possible to set This improves the stability of the operating conditions.

[0083] In some embodiments, before determining the target degree of freedom of the permanent magnet synchronous motor, the method further includes: determining that the permanent magnet synchronous motor is in a powered-on operating state.

[0084] It is understandable that by setting the permanent magnet synchronous motor to enter detection control in the power-on state, it is ensured that the system is always determining whether to perform phase current limiting frequency reduction control in the power-on state.

[0085] To further illustrate the technical solution provided by the invention, this embodiment also provides a phase current limiting frequency reduction control process under typical operating conditions of different motors:

[0086] Under high-speed load conditions, the combined current is large, triggering the combined current limiting frequency reduction to ensure that the motor phase current does not exceed the maximum allowable current of the motor or the allowable current of the motor phase line, while fully utilizing the motor's capacity; however, neither the quadrature axis current nor the direct axis current triggers the limiting frequency reduction value.

[0087] Under heavy load and low-frequency conditions, the quadrature-axis current is large, triggering frequency reduction due to quadrature-axis current limiting. The absolute value of the direct-axis current is not large, so it will not trigger frequency reduction due to direct-axis current limiting. The combined current is also small, so it will not trigger frequency reduction due to combined current limiting. Frequency reduction is triggered by quadrature-axis current until it reaches the lower limit frequency. Because a suitable preset quadrature-axis current reduction threshold is set, there will be no runaway during the frequency reduction process, and the frequency will stabilize at the lower limit frequency to ensure stable operation under high-temperature conditions.

[0088] Under light load and ultra-high speed conditions, the absolute value of the direct-axis current is large, triggering direct-axis current limiting frequency reduction. The quadrature-axis current is small and will not trigger quadrature-axis current limiting frequency reduction. The combined current is also small and will not trigger combined current limiting frequency reduction. Furthermore, when the bus voltage decreases, the absolute value of the direct-axis current increases at the same speed, potentially exceeding the characteristic current. Exceeding the characteristic current will cause field weakening runaway. The existence of direct-axis current limiting frequency reduction ensures that the frequency is limited to the highest controllable speed, preventing field weakening runaway.

[0089] Based on a general inventive concept, embodiments of the present invention also provide a phase current limiting frequency reduction control device to implement the phase current limiting frequency reduction control method described in the above embodiments.

[0090] Figure 3 This is a schematic diagram of a phase current limiting frequency reduction control device according to an embodiment of the present invention. (See attached diagram.) Figure 3 The apparatus provided in the embodiments of the present invention may include the following structures:

[0091] The determination module 31 is used to determine the value of the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, the direct-axis current and the quadrature-axis current;

[0092] The control module 32 is used to determine the value of each target degree of freedom and the corresponding threshold based on the preset target degree of freedom judgment order and correlation relationship, and to perform phase current limit frequency reduction control.

[0093] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0094] It is understandable that the technical solution provided in this embodiment controls the compressor frequency through three degrees of freedom, namely, considering the composite phase current, direct-axis current, and quadrature-axis current, setting different thresholds to control frequency reduction, thereby using different frequency reduction control methods under different operating conditions to ensure the reliability of each operating condition. This solves the technical problem in the prior art where, when adjusting based on a single compressor phase current (i.e., composite phase current), if the motor frequency reduction current value is set too high, it can easily lead to loss of synchronization at low and medium frequencies under heavy loads; if it is set too low, the motor capacity cannot be fully utilized.

[0095] Based on a general inventive concept, embodiments of the present invention also provide a phase current limiting frequency reduction control device.

[0096] Figure 4 This is a schematic diagram of a phase current limiting frequency reduction control device according to an embodiment of the present invention. Please refer to [the diagram]. Figure 4 The present invention provides a phase current limiting frequency reduction control device, including: a processor 41 and a memory 42 connected to the processor.

[0097] The memory 42 is used to store a computer program, which is used at least for the phase current limiting frequency reduction control method described in any of the above embodiments;

[0098] Processor 41 is used to call and execute computer programs in memory.

[0099] Based on a general inventive concept, embodiments of the present invention also provide an air conditioner.

[0100] The air conditioner provided in this embodiment may include a permanent magnet synchronous motor and the aforementioned phase current limiting frequency reduction control device; the permanent magnet synchronous motor is connected to the phase current limiting frequency reduction control device.

[0101] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0102] It is understood that the same or similar parts in the above embodiments can be referred to each other, and the contents not described in detail in some embodiments can be referred to the same or similar contents in other embodiments.

[0103] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means at least two.

[0104] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0105] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0106] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0107] Furthermore, the functional units in the various embodiments of the present invention can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0108] The storage media mentioned above can be read-only memory, disk, or optical disk, etc.

[0109] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0110] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A phase current limiting frequency reduction control method, characterized in that, Applied to permanent magnet synchronous motors, the method includes: Determine the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, the direct-axis current, and the quadrature-axis current; Based on the pre-set target degree of freedom judgment order and correlation relationship, determine the value of each target degree of freedom and the corresponding threshold, and perform phase current limit frequency reduction control; The step of determining the value of each target degree of freedom and its corresponding threshold based on a pre-set target degree of freedom judgment order and correlation, and performing phase current limiting frequency reduction control, includes: Determine the value of the synthesized phase current and the magnitude of the preset synthesized phase current threshold; and control the compressor frequency according to the relationship between the value of the synthesized phase current and the preset synthesized phase current threshold; and determine the value of the quadrature axis current and the magnitude of the preset quadrature axis current threshold. Based on the relationship between the value of the quadrature axis current and the preset quadrature axis current threshold, the compressor frequency is controlled, and the absolute value of the direct axis current is determined to be greater than or equal to the preset DC current threshold. The compressor frequency is controlled based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold.

2. The method according to claim 1, characterized in that, The step of determining the value of the composite phase current and comparing it with a preset composite phase current threshold, and controlling the compressor frequency based on the relationship between the value of the composite phase current and the preset composite phase current threshold, includes: Determine whether the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold; If the value of the synthesized phase current is greater than the preset synthesized phase current frequency reduction current threshold, the compressor is triggered to reduce the frequency. If the value of the synthesized phase current is greater than the preset synthesized phase current frequency limiting current threshold and is less than or equal to the preset synthesized phase current frequency reduction current threshold, then the frequency increase of the compressor is restricted; wherein, the preset synthesized phase current frequency limiting current threshold is less than the preset synthesized phase current frequency reduction current threshold.

3. The method according to claim 1, characterized in that, The value of the cross-axis current is compared with the preset cross-axis current threshold. Based on the relationship between the value of the quadrature-axis current and a preset quadrature-axis current threshold, the compressor frequency is controlled, including: Determine whether the value of the quadrature-axis current is greater than a preset quadrature-axis current frequency reduction current threshold; If the value of the quadrature axis current is greater than the preset quadrature axis current frequency reduction current threshold, the compressor is triggered to reduce the frequency. If the value of the quadrature axis current is greater than the preset quadrature axis current frequency limiting current threshold and is less than or equal to the preset quadrature axis current frequency reducing current threshold, then the frequency increase of the compressor is restricted; wherein the preset quadrature axis current frequency limiting current threshold is less than the preset quadrature axis current frequency reducing current threshold.

4. The method according to claim 1, characterized in that, The absolute value of the direct-axis current is compared with the preset DC current threshold. Based on the relationship between the absolute value of the direct-axis current and a preset direct-axis current threshold, the compressor frequency is controlled, including: Determine whether the absolute value of the direct-axis current is greater than a preset direct-axis current frequency reduction current threshold. If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, the compressor is triggered to reduce its frequency. If the absolute value of the direct-axis current is greater than the preset direct-axis current frequency reduction threshold, and is less than or equal to the preset direct-axis current frequency reduction threshold, then the frequency increase of the compressor is restricted; wherein, the preset direct-axis current frequency reduction threshold is less than the preset direct-axis current frequency reduction threshold.

5. The method according to claim 4, characterized in that, Also includes: The preset direct-axis current reduction current threshold is less than the characteristic current of the permanent magnet synchronous motor.

6. The method according to claim 1, characterized in that, Before determining the target degree of freedom of the permanent magnet synchronous motor, the method further includes: determining that the permanent magnet synchronous motor is in the powered-on running state.

7. A phase current limiting frequency reduction control device, characterized in that, The device, applied to permanent magnet synchronous motors, includes: The determination module is used to determine the value of the target degree of freedom of the permanent magnet synchronous motor, wherein the target degree of freedom includes the composite phase current, the direct-axis current, and the quadrature-axis current; The control module is used to determine the value of each target degree of freedom and its corresponding threshold based on a pre-set target degree of freedom judgment order and correlation relationship, and to perform phase current limit frequency reduction control; the step of determining the value of each target degree of freedom and its corresponding threshold based on a pre-set target degree of freedom judgment order and correlation relationship, and performing phase current limit frequency reduction control includes: determining the value of the composite phase current and its preset composite phase current threshold; controlling the compressor frequency based on the relationship between the value of the composite phase current and its preset composite phase current threshold; and determining the value of the quadrature axis current and its preset quadrature axis current threshold. Based on the relationship between the value of the quadrature axis current and the preset quadrature axis current threshold, the compressor frequency is controlled, and the absolute value of the direct axis current is determined to be greater than or equal to the preset DC current threshold. The compressor frequency is controlled based on the relationship between the absolute value of the direct-axis current and the preset direct-axis current threshold.

8. A phase current limiting frequency reduction control device, characterized in that, include: A processor, and a memory connected to the processor; The memory is used to store a computer program, which is at least used to execute the phase current limiting frequency reduction control method according to any one of claims 1 to 6; The processor is used to call and execute the computer program in the memory.

9. An air conditioner, characterized in that, It includes a permanent magnet synchronous motor and the phase current limiting frequency reduction control device as described in claim 8; the permanent magnet synchronous motor is connected to the phase current limiting frequency reduction control device.

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