Compressor low-frequency operation torque ripple compensation method and device, air conditioning equipment and medium

Abstract

The invention discloses a torque ripple compensation method and device for low-frequency operation of a compressor, air conditioning equipment and a medium. The method comprises the steps that parameter information of the compressor in the variable-frequency operation process is obtained, and the parameter information represents the rotating speed fluctuation generated by the current load torque of the compressor; determining N compensation orders of the current load torque according to the parameter information, wherein the N compensation orders at least comprise one order of the current load torque; and carrying out torque ripple compensation on the load torque components corresponding to the N compensation orders. The technical problem that when the compressor operates at low frequency, the observation precision of the position and the rotating speed without position sensing control is not high is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of compressors, and in particular relates to a torque fluctuation compensation device, air conditioning equipment and medium for low-frequency operation of a compressor. Background Art

[0002] Small rooms or rooms with good insulation have a smaller cooling capacity requirement at a set temperature of around 27°, while the minimum cooling capacity of many air conditioners is much greater than this requirement. The difference between cooling demand and cooling capacity causes the compressor to stop and restart intermittently, resulting in large temperature fluctuations, poor comfort and noise. One of the core factors that limit the minimum cooling capacity of an air conditioner is the minimum stable operating frequency of the compressor.

[0003] Due to the large temperature changes inside the air-conditioning compressor and the presence of refrigerant and lubricating oil in the cavity, the reliability of the mechanical position sensor is difficult to guarantee. Therefore, the compressor of the variable frequency air conditioner often uses position sensorless control, and the refrigerant compression of the single-rotor compressor will produce large load torque fluctuations. The load torque fluctuation will have an adverse effect on the position and speed observation accuracy of the position sensorless control. Due to mechanical inertia, the torque fluctuation of the same amplitude will produce smaller speed fluctuations when the compressor frequency is lower. The related technology only compensates for the torque fluctuation of the fixed first-order load torque component, resulting in large speed fluctuations when the compressor is running at low frequency, which in turn leads to low position and speed observation accuracy of the position sensorless control when the compressor is running at low frequency. Summary of the invention

[0004] The present invention provides a torque fluctuation compensation device, air conditioning equipment and medium for low-frequency operation of a compressor, which are used to solve the technical problem of low position and speed observation accuracy without position sensor control when the compressor is running at low frequency.

[0005] In a first aspect of the present invention, a method for compensating torque fluctuations during low-frequency operation of a compressor is provided, comprising: obtaining parameter information of the compressor during variable frequency operation, the parameter information affecting the speed fluctuation generated by the compressor; determining N compensation orders of the current load torque of the compressor according to the parameter information, the N compensation orders including at least one order of the current load torque, and N being a positive integer; and performing torque fluctuation compensation on the load torque components of the N compensation orders.

[0006] In some embodiments, the parameter information includes a variable frequency parameter for controlling the operating frequency of the compressor; determining the N compensation orders of the current load torque of the compressor based on the parameter information includes: determining a target parameter interval in which the variable frequency parameter is located from M preset parameter intervals, M is an integer greater than 1, and the M preset parameter intervals are respectively pre-configured with compensation order information, the M preset parameter intervals are divided by the variation range of the variable frequency parameter, and the preset parameter interval with a larger parameter value has a pre-configured compensation order information indicating more compensation orders; determining the N compensation orders of the current load torque at least based on the compensation order information pre-configured in the target parameter interval.

[0007] In some embodiments, the N compensation orders of the current load torque are determined at least based on the compensation order information pre-configured in the target parameter interval, including: determining candidate compensation orders of the current load torque based on the compensation order information pre-configured in the target parameter interval; from the candidate compensation orders, obtaining each order in which the speed fluctuation amplitude generated by the load torque component is greater than a preset frequency threshold, to obtain the N compensation orders, wherein the parameter information includes the speed fluctuation amplitude generated by the load torque component of the candidate compensation orders.

[0008] In some embodiments, the compensation order information pre-configured according to the target parameter interval determines the candidate compensation order of the current load torque, including: if the parameter value of the frequency conversion parameter is less than the first parameter threshold, determining the candidate compensation order to be the first order to K1 order of the current load torque; if the parameter value of the frequency conversion parameter is less than the second parameter threshold, and not less than the first parameter threshold, determining the candidate compensation order to be the first order to K2 order of the current load torque, and the second parameter threshold is greater than the first parameter threshold; if the parameter value of the frequency conversion parameter is not less than the second parameter threshold, wherein K1 is greater than K2 and both are positive integers; if the parameter value of the frequency conversion parameter is not less than the second parameter threshold, determining the candidate compensation order to be at least the first order of the current load torque.

[0009] In some embodiments, obtaining from the candidate compensation orders each order in which the speed fluctuation amplitude generated by the load torque component is greater than a preset frequency threshold includes: extracting the load torque component of each candidate compensation order from the current load torque, the candidate compensation orders including at least one, and the parameter information also including the speed fluctuation amplitude generated by the load torque component of each candidate compensation order; for each candidate compensation order, if the speed fluctuation threshold generated by the load torque component of the candidate compensation order is greater than the preset frequency threshold, the candidate compensation order is used as one of the N compensation orders.

[0010] In some implementations, the frequency conversion parameter includes a maximum effective duty cycle of a three-phase inverter circuit for driving the compressor or a target operating frequency of the compressor.

[0011] In some embodiments, determining N compensation orders of the current load torque of the compressor according to the parameter information includes: extracting load torque components of orders 1 to K from the current load torque, and taking the first order of the current load torque as one of the N compensation orders, where K is a preset integer value greater than N; determining the rotation fluctuation amplitude generated by load torque components of orders 2 to K, and the parameter information includes the speed fluctuation amplitude generated by load torque components of orders 2 to K in the current load torque; if the speed fluctuation amplitude generated by the load torque component of order X is greater than a preset frequency threshold, taking the X order as one of the N compensation orders, where X is 2 to K.

[0012] In some embodiments, the torque fluctuation compensation for the load torque components of the N compensation orders includes: acquiring the current direct-axis current and motor parameters of the compressor; determining the torque coefficient according to the current direct-axis current and motor parameters; for each compensation order of the N compensation orders, determining the quadrature-axis current compensation value of the compensation order at least according to the torque coefficient, and performing torque fluctuation compensation for the load torque component of the compensation order according to the quadrature-axis current compensation value of the compensation order.

[0013] In some embodiments, for each of the N compensation orders, the cross-axis current compensation value of the compensation order is determined at least according to the torque coefficient, including: for each of the N compensation orders, the cross-axis current compensation value of the compensation order is determined based on the torque coefficient and the current limiting value corresponding to the compensation order; wherein the sum of the current limiting values ​​of the N compensation orders is less than a target parameter threshold, and the target reference threshold is determined according to the motor demagnetization current and a preset protection coefficient.

[0014] In a second aspect of the present invention, a fluctuation compensation device for low-frequency operation of a compressor is provided, comprising: a parameter acquisition unit, used to acquire parameter information of the compressor during variable frequency operation, the parameter information characterizing the speed fluctuation magnitude generated by each order of load torque in the current load torque of the compressor; a compensation determination unit, used to determine N compensation orders of the current load torque based on the parameter information, the N compensation orders including at least one order of the current load torque; and a fluctuation compensation unit, used to perform torque fluctuation compensation on the load torque components corresponding to the N compensation orders.

[0015] In a third aspect of the present invention, an air conditioning device is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program and is a method for compensating torque fluctuations during low-frequency operation of the compressor.

[0016] In a fourth aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the torque fluctuation compensation method for low-frequency operation of the compressor is implemented.

[0017] According to one or more embodiments provided by the present invention, at least the following technical effects or advantages are achieved:

[0018] By obtaining parameter information that affects the speed fluctuation size of the compressor during variable frequency operation; and determining N compensation orders of the current load torque of the compressor according to the parameter information, the N compensation orders include at least the first order of the current load torque, and N is a positive integer; performing torque fluctuation compensation on the load torque components of the N compensation orders, the above technical scheme can adjust the order to be compensated according to the current actual speed fluctuation of the compressor, and is not limited to the first order of the current load torque, so that the compensation order matches the speed fluctuation size of the compressor, and selects multi-order torque fluctuation compensation according to actual conditions, thereby realizing compensation for all order load torque components that affect the observation accuracy of sensorless position control, so as to reduce the speed fluctuation size of the compressor when it is running at low frequency and high load. Thereby, the position and speed observation accuracy of the position sensorless control of the compressor when it is running at low frequency can be improved, and then the stability of the compressor when it is running at low frequency and high load can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 A schematic diagram of a method for compensating torque fluctuations during low-frequency operation of a compressor provided by an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the connection between a compressor and a three-phase inverter circuit driving the compressor provided in an embodiment of the present invention;

[0022] Figure 3 A compressor speed control logic for applying the torque fluctuation compensation method for low-frequency operation of a compressor provided by an embodiment of the present invention;

[0023] Figure 4 A schematic structural diagram of a torque fluctuation compensation device for low-frequency operation of a compressor provided in an embodiment of the present invention.

[0024] Figure 5 A schematic diagram of the structure of an air conditioning device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0027] The invention provides a method for compensating torque fluctuations of a compressor in low-frequency operation. Figure 1 Schematic diagram of a method for compensating torque fluctuations during low-frequency operation of a compressor provided by an embodiment of the present invention. Figure 1 As shown, the torque fluctuation compensation method for low-frequency operation of the compressor includes the following steps S101 to S103.

[0028] S101: Acquire parameter information of the compressor during variable frequency operation, where the parameter information affects the speed fluctuation generated by the compressor.

[0029] It is understandable that, due to mechanical inertia, for load torque fluctuations of the same magnitude, the higher the operating frequency of the compressor, the smaller the speed fluctuations generated, and vice versa. Therefore, in some embodiments, the parameter information obtained in step S101 may be a variable frequency parameter for controlling the operating frequency of the compressor.

[0030] Figure 2The following is a schematic diagram of the connection between the compressor and the three-phase inverter circuit driving the compressor provided in the embodiment of the present invention. Figure 2 As shown, in some embodiments, the variable frequency parameter may be the target operating frequency of the compressor 20. The target operating frequency of the compressor 20 changes dynamically with the set temperature and the ambient temperature of the environment being acted upon. The target operating frequency is the mechanical frequency required by the compressor determined according to the temperature difference between the ambient temperature and the set temperature. The greater the temperature difference between the ambient temperature and the set temperature, the greater the target operating frequency. It is necessary to continuously detect the ambient temperature and the set temperature during the variable frequency operation of the compressor 20 to track the dynamic changes in the target operating frequency of the compressor 20.

[0031] like Figure 2 As shown, in other embodiments, the frequency conversion parameter may be the maximum effective duty cycle of the three-phase inverter circuit 10 of the compressor 20. In some embodiments, in order to obtain the maximum effective duty cycle of the three-phase inverter circuit 10, it may include: obtaining the switch duty cycle difference between every two-phase inverter circuits in the three-phase inverter circuit 10; determining the effective duty cycle of the corresponding phase inverter circuit based on the switch duty cycle difference between every two-phase inverter circuits in the three-phase inverter circuit 10, so as to obtain the three-phase effective duty cycle corresponding to the three-phase inverter circuit 10; and obtaining the maximum effective duty cycle from the three-phase effective duty cycles corresponding to the three-phase inverter circuit 10.

[0032] The difference in the switching duty cycle between each two-phase inverter circuit can be calculated by referring to the following formula: xy =D x -D y ,x,y=u,v,w, where D x , D y is the duty cycle of any two-phase inverter circuit. Duv, Dwu, and Dvw represent the difference in the switching duty cycle between two phases in the three phases UVW respectively. The effective duty cycle Du0, Dv0, Dw0 of each phase inverter circuit and the maximum effective duty cycle Dmax are calculated by referring to the following formula:

[0033]

[0034] In other implementations, the parameter information acquired in step S101 may be: the speed fluctuation amplitudes generated by load torque components of multiple orders in the current load torque of the compressor.

[0035] In other implementations, the parameter information acquired in step S101 may include: the speed fluctuation amplitudes generated by multiple orders of load torque components in the current load torque of the compressor, and the frequency conversion parameters that affect the operating frequency of the compressor.

[0036] S102: Determine N compensation orders of the current load torque according to the parameter information, where the N compensation orders include at least one order of the current load torque.

[0037] It should be noted that the N compensation orders are the orders in the current load torque that require torque fluctuation compensation. The first-order load torque component of the current load torque must be compensated for torque fluctuations, and whether other order load torque components are compensated for torque fluctuations is determined based on parameter information that affects the speed fluctuation of the compressor. Therefore, the value of N does not need to be set in advance, but changes with the operating frequency and load of the compressor.

[0038] In some embodiments, if the acquired parameter information includes at least a variable frequency parameter for controlling the operating frequency of the compressor, determining the N compensation orders of the current load torque of the compressor based on the parameter information may include: determining a target parameter interval including the variable frequency parameter from M preset parameter intervals, where M is an integer greater than 1; and determining the N compensation orders of the current load torque based on at least the compensation order information pre-configured in the target parameter interval including the variable frequency parameter.

[0039] It can be understood that the M preset parameter intervals are formed by dividing the variation range of the frequency conversion parameter, and the compensation order information pre-configured in the parameter interval with a larger parameter value represents more compensation orders. The variation range of the frequency conversion parameter can be divided into M preset parameter intervals according to M-1 parameter thresholds selected from the variation range of the frequency conversion parameter.

[0040] Wherein, in case the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit 10, the M-1 parameter thresholds may be: d and the switching period Tsw set the M-1 duty cycle thresholds. For example, it can be the dead zone duty cycle T d The M-1 duty cycle thresholds are selected within the range of 5 to 10 times of / Tsw. The M preset parameter intervals are M duty cycle intervals divided based on the M-1 duty cycle thresholds.

[0041] Among them, as long as the variable frequency parameter is the target operating frequency of the compressor, the M-1 parameter thresholds can be: M-1 frequency points selected within the full frequency range of the compressor, and the full frequency range of the compressor is divided into M frequency intervals based on the M-1 frequency points.

[0042] In the related art, when the compressor is running at a mechanical frequency of more than 10Hz, the physical frequency corresponding to the second and third harmonics in the mechanical frequency is above 20Hz, and the speed fluctuation generated is small. Therefore, torque fluctuation compensation based on the related art can meet the needs, and the compressor can operate stably. When the mechanical frequency is less than 10Hz, the compressor cannot continue to operate stably. Therefore, 10Hz is the minimum stable operating frequency of the compressor in the related art. However, the minimum stable operating frequencies of different compressors are different. Therefore, in some embodiments, the maximum frequency point among the M-1 frequency points can be set according to the minimum stable operating frequency of the compressor measured in the related art, for example: the maximum frequency point can use the minimum stable operating frequency of the compressor, or use a frequency point that is close to the minimum stable operating frequency and slightly greater than the minimum stable operating frequency. And the other frequency points except the maximum frequency point among the M-1 frequency points are all less than the minimum stable operating frequency of the compressor. The Id=0 or MTPA control mode can be used in advance to make the compressor 20 run the full frequency range, and the minimum frequency point that makes the compressor 20 run without losing control is measured, that is, the minimum stable operating frequency of the compressor is obtained. For example, if the minimum stable operating frequency of the compressor 20 is measured to be 10 Hz, the maximum frequency point among the M-1 frequency points can be set to a frequency point within the range of 10 Hz to 20 Hz, and the other frequency points among the M-1 frequency points are all less than 10 Hz.

[0043] In some embodiments, the acquired parameter information includes, in addition to the variable frequency parameters for controlling the operating frequency of the compressor, the speed fluctuation amplitude generated by the load torque components of the 2nd to Kth order in the current load torque, where K is a preset integer value greater than N. Based on this, the step of determining the N compensation orders of the current load torque at least according to the compensation order information pre-configured in the target parameter interval where the variable frequency parameters are located may include: acquiring the speed fluctuation amplitude generated by the load torque components of the 2nd to Kth order in the current load torque; and determining N-1 compensation orders of the current load torque from the 2nd to Kth order based on the speed fluctuation amplitude generated by the load torque components of the 2nd to Kth order and the compensation order information pre-configured in the target parameter interval where the variable frequency parameters are located. Among them, among the 2nd to Kth order, if it satisfies both the order recorded in the compensation order information and the speed fluctuation amplitude generated by the load torque component of the order is greater than the preset frequency threshold, then the order is taken as one of the N compensation orders. It should be noted that the above judgment may not be performed for the first-order load torque component in the current load torque, but the first-order of the current load torque may be directly used as one of the N compensation orders.

[0044] In some embodiments, the N compensation orders of the current load torque are determined by pre-configuring the compensation order information in the target parameter interval where the variable frequency parameter is located, determining the candidate compensation orders of the current load torque, wherein the candidate compensation orders include at least one; from the candidate compensation orders, obtaining each order where the speed fluctuation amplitude generated by the load torque component is greater than the preset frequency threshold, and obtaining N compensation orders, wherein the parameter information also includes the speed fluctuation amplitude generated by the load torque component of each candidate compensation order. Thus, the N orders of torque fluctuation compensation required in the current load torque are determined by combining the operating frequency of the compressor and the speed fluctuation amplitudes of different orders, which can improve the accuracy of determining the compensation order.

[0045] In some embodiments, if the parameter value of the frequency conversion parameter is less than the first parameter threshold, the candidate compensation order is determined to be the first order to K1 order of the current load torque; if the parameter value of the frequency conversion parameter is less than the second parameter threshold, and not less than the first parameter threshold, the candidate compensation order is determined to be the first order to K2 order of the current load torque, and the second parameter threshold is greater than the first parameter threshold, wherein K1 is greater than K2, and both are positive integers; if the parameter value of the frequency conversion parameter is not less than the second parameter threshold, the candidate compensation order is determined to be at least the first order of the current load torque. In other words, the larger the parameter value of the frequency conversion parameter, the fewer the candidate compensation orders.

[0046] In some embodiments, the parameter information also includes the speed fluctuation amplitude generated by the load torque component of each candidate compensation order, and the load torque component of each candidate compensation order can be extracted from the current load torque, and the candidate compensation orders include at least one; for each candidate compensation order, if the speed fluctuation threshold generated by the load torque component of the candidate compensation order is greater than a preset frequency threshold, the candidate compensation order is used as one of the N compensation orders, so that N compensation orders that require torque fluctuation compensation can be screened out from the candidate compensation orders.

[0047] Take judging whether the second order of the current load torque needs to be compensated for torque fluctuation as an example: judging whether the target operating frequency of the compressor is less than the second preset frequency f0, if not less than f0, there is no need to compensate for the torque fluctuation of the second order load torque component; if less than f0, continue to judge whether the target operating frequency is less than the first preset frequency f1, if less than f1, it is necessary to compensate for the torque fluctuation of the second order load torque component, then start the torque fluctuation compensation of the second order load torque component; if not less than f1, continue to judge whether the speed fluctuation amplitude Fmflut generated by the second order load torque component satisfies greater than 1Hz, if Fmflut>1Hz, it is necessary to compensate for the torque fluctuation of the second order load torque component, then start the torque fluctuation compensation of the second order load torque component, if not greater than 1Hz, there is no need to compensate for the torque fluctuation of the second order load torque component. Whether to start the torque fluctuation compensation of the higher order load torque component can refer to the implementation principle of the above logic.

[0048] In other embodiments, if the parameter information obtained is only the frequency conversion parameter for controlling the operating frequency of the compressor, and does not include the speed fluctuation amplitude generated by the load torque components of order 2 to order K in the current load torque. Then the compensation order recorded in the compensation order information corresponding to the target parameter interval is directly used as the order that needs to be compensated for torque fluctuations in the current load torque. Taking M=2 as an example, three preset parameter intervals are divided based on two parameter thresholds, wherein the two parameter thresholds are: a first parameter threshold and a second parameter threshold that is less than the first parameter threshold. If the parameter value of the frequency conversion parameter is less than the first parameter threshold, the parameter value characterizing the frequency conversion parameter is in the first preset parameter interval (0, a1), and the first parameter threshold is represented by a1, then the N compensation orders are from order 1 to order K1 in the current load torque. If the parameter value of the frequency conversion parameter is less than the second parameter threshold and not less than the first parameter threshold, the parameter value characterizing the frequency conversion parameter is in the second preset parameter interval [a1, a2), the second parameter threshold is greater than the first parameter threshold, and the second parameter threshold is represented by a2, then the N compensation orders are from the first order to the K2 order in the current load torque; if the parameter value of the frequency conversion parameter is not less than the second parameter threshold: the parameter value characterizing the frequency conversion parameter is in the third preset parameter interval: [a2, +∞), then the N compensation orders include at least the first order of the current load torque. Of course, in the actual implementation process, more preset parameter intervals can be divided, so that the order that needs to be compensated for torque fluctuations can be determined more accurately.

[0049] As far as the variable frequency parameter is the target operating frequency of the compressor, M=2, that is, there are two frequency points: the first preset frequency and the second preset frequency greater than the first preset frequency. If the target operating frequency of the compressor is less than the first preset frequency, it is determined that the 1st to Kth orders of the current load torque need to be compensated for torque fluctuations; if the target operating frequency of the compressor is less than the second preset frequency and not less than the first preset frequency, it is determined that the first and second orders of the current load torque need to be compensated for torque fluctuations; if the target operating frequency of the compressor is not less than the second preset frequency, it is determined that the first order of the current load torque needs to be compensated for torque fluctuations. For example, the first preset frequency can be 5Hz, and the second preset frequency can be 10Hz. When the target operating frequency of the compressor is higher than 10Hz, only the load torque component of the first order is extracted. When the target operating frequency of the compressor exceeds 5Hz but does not exceed 10Hz, the load torque component of the first order and the load torque component of the second order are extracted. When the target operating frequency of the compressor does not exceed 5Hz, Cs is set as a low-pass filter, and the filter bandwidth is set to be above 20 times the mechanical frequency, for example: the filter bandwidth can be 100Hz.

[0050] As far as the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit, M=2, that is, there are two duty cycle thresholds: a first duty cycle threshold and a second duty cycle threshold that is greater than the first duty cycle threshold. If the maximum effective duty cycle of the three-phase inverter circuit is less than the first duty cycle threshold, it is determined that only the 1st to Kth orders of the current load torque need to be compensated for torque fluctuations. If the maximum effective duty cycle of the three-phase inverter circuit is less than the second duty cycle threshold and not less than the first duty cycle threshold, it is determined that the first and second orders of the current load torque need to be compensated for torque fluctuations. If the maximum effective duty cycle of the three-phase inverter circuit is not less than the second duty cycle threshold, it is determined that the torque fluctuation compensation that needs to be performed is the first order of the current load torque. For example: when Dmax>DutyLim2, extract the 1st and 2nd order load torque components respectively; when DutyLim1<Dmax≤DutyLim2, extract the 1st, 2nd and 3rd order load torque components respectively; when Dmax≤DutyLim1, Cs is set as a low-pass filter, and the filter bandwidth wb is set above 20 times the mechanical frequency. Dmax is the maximum effective duty cycle of the three-phase inverter circuit, and DutyLim1 and DutyLim2 correspond to the first duty cycle threshold and the second duty cycle threshold.

[0051] In other embodiments, if the acquired parameter information only includes the speed fluctuation amplitude generated by the load torque components of order 2 to K in the current load torque, and does not include the variable frequency parameters for controlling the operating frequency of the compressor, then step S102 may include: extracting the load torque components of order 1 to K from the current load torque, taking the first order of the current load torque as one of the N compensation orders, K being a preset integer value greater than N; determining the rotation fluctuation amplitude generated by the load torque components of order 2 to K, the parameter information including the speed fluctuation amplitude generated by the load torque components of order 2 to K in the current load torque; if the speed fluctuation amplitude generated by the load torque component of order X is greater than the preset frequency threshold, taking the X order as one of the N compensation orders, X being 2 to K. In some embodiments, the preset frequency threshold may be set to 1 Hz or other similar values.

[0052] In some implementations, load torque components of orders 1 to K in the current load torque may be extracted one-to-one based on pre-designed digital filters of orders 1 to K, with a total of K different digital filters.

[0053] S103: Perform torque ripple compensation on load torque components corresponding to N compensation orders.

[0054] In some embodiments, the current direct-axis current and motor parameters of the compressor are obtained; the torque coefficient is determined based on the current direct-axis current and motor parameters, wherein the torque coefficient describes the relationship between the motor current and the electromagnetic torque of the compressor; for each of the N compensation orders, the quadrature-axis current compensation value of the compensation order is determined at least based on the torque coefficient, and the torque fluctuation compensation is performed on the load torque component of the compensation order based on the quadrature-axis current compensation value of the compensation order.

[0055] The electromagnetic torque of the permanent magnet synchronous motor is:

[0056]

[0057] Among them, T e is the electromagnetic torque, P n is the number of motor pole pairs, ψ f is the permanent magnet flux of the motor, i d 、i q Corresponding to the direct axis current and quadrature axis current, L d , L q The corresponding inductance is the direct-axis inductance and the quadrature-axis inductance.

[0058] Definition of comprehensive flux linkage coefficient When controlling the direct-axis inductance i d When it is a stable value, the value of the comprehensive flux coefficient remains unchanged. At this time, the change of the electromagnetic torque provided by the permanent magnet synchronous motor of the compressor is related to the quadrature axis current i qThere is a linear relationship between them. Define the torque coefficient The electromagnetic torque, torque coefficient and quadrature axis current satisfy the following relationship T e =K t i q When the electromagnetic torque is adjusted to Te=Tload, the motor speed will remain stable. When the X-order load torque is equal to the X-order electromagnetic torque, the speed will no longer have the X-order fluctuation component. At this time, the X-order is any order of the current load torque. Therefore, based on the torque coefficient, the load torque components of N compensation orders are converted by 1 / Kt to obtain the quadrature-axis current compensation value for torque fluctuation compensation of the load torque components of N compensation orders:

[0059] i q，cx =T loadx / K t

[0060] Among them, X takes the order from 1 to N, T loadx is the load torque component of order X, i q，cx It is the quadrature-axis current compensation value used to compensate the torque ripple of the X-order load torque component.

[0061] In some embodiments, after performing a 1 / Kt conversion on the load torque components of N compensation orders based on the torque coefficient to obtain N quadrature-axis current compensation values, the quadrature-axis current compensation value of each compensation order in the N compensation orders can be limited based on the current limit value corresponding to the compensation order. It should be noted that the sum of the current limit values ​​of the N compensation orders should be less than the target parameter threshold, where the target reference threshold is determined based on the motor demagnetization current and the preset protection coefficient. In other words, the current limit values ​​of the N compensation orders meet the following conditions:

[0062]

[0063] Among them, K p is the preset protection factor, which is a value below 0.9, and i is the motor demagnetization current. abs(i q，cx ) is the amplitude of the quadrature-axis current compensation value corresponding to the X order, I xlimm is the current limit value of order X.

[0064] In some implementations, the current limit values ​​of two adjacent orders in the N compensation orders satisfy: the current limit value corresponding to the higher order is smaller. More specifically, the current limit value I of the X order and the X-1 order is xlimm ,I (x-1)limm The following size relationship can be satisfied between them: I xlimm <K×I (x-1)limm, where K takes a small value, for example, K=0.2.

[0065] It should be noted that the limiting current value of the same compensation order is not unique, and the limiting current value of the compensation order is determined according to the target operating frequency of the compressor, wherein the larger the target operating frequency of the compressor, the smaller the limiting current value of the compensation order. In some embodiments, the limiting current values ​​of N compensation orders are determined according to the frequency interval in which the target operating frequency of the compressor is located.

[0066] For example: If the target operating frequency of the compressor is higher than fm0, the current limit value of the Xth order is I xlimm0 ; If the target operating frequency of the compressor is higher than fm1 and not higher than fm0, the current limit value of the Xth order is I xlimm1 ; If the target operating frequency of the compressor is higher than fm2 and not higher than fm1, the current limit value of the Xth order is I xlimm2 Among them, fm0>fm1>fm2, I xlim0 <I xlim1 <I xlimm2 .

[0067] Figure 3 The compressor speed control logic of the torque fluctuation compensation method for low-frequency operation of the compressor provided by the embodiment of the present invention is applied. For ease of understanding, the following reference Figure 3 , the application process after obtaining the quadrature-axis current compensation values ​​of N compensation orders is explained:

[0068] The required speed is w*, the feedback speed is w; the load torque is Tload, and the electromagnetic torque provided by the motor is Te; J is the moment of inertia parameter of the motor; Kt is the torque coefficient, which describes the relationship between the motor current and the electromagnetic torque. s represents the differential operator, P(s) is the combination of the electrical model of the motor, the current control loop and the inverter model, the input of P(s) is the command current, and the output is the electromagnetic torque. M(s) is the mechanical model of the motor, the input of M(s) is the difference between the electromagnetic torque and the load torque, and the output is the speed w. M(s) and P(s) together represent the actual model of the motor; Iq,c is the compensation current on the Q axis for load torque fluctuations.

[0069] Principle of speed controller: In the large loop of the dotted box, the speed PI controller calculates the required electromagnetic torque based on the difference between the required speed w* and the feedback speed w, and obtains the current (Iq current is described in the figure) after 1 / Kt conversion, superimposing the quadrature-axis compensation current i of N compensation orders. q,cx(x ranges from 1 to N) and then acts on the system to obtain the feedback speed w. In the small loop on the right side of the dotted box, the speed estimation value ωhat is obtained according to the current signal (different from the feedback speed w above). The difference between the feedback speed w and the speed estimation value ωhat is calculated by the STA module to obtain the estimated load torque Tload, and then the load torque components of N compensation orders in Tload are extracted through the digital filter C(s). For the load torque components of N compensation orders, iq, cx for torque fluctuation compensation are converted respectively, and x ranges from 1 to N.

[0070] Based on the same inventive concept, the present invention also provides a torque fluctuation compensation device for low-frequency operation of a compressor. Figure 4 The structure diagram of the torque fluctuation compensation device for low-frequency operation of a compressor provided by an embodiment of the present invention is shown in FIG. Figure 4 As shown, the torque fluctuation compensation device for low-frequency operation of the compressor includes: a parameter acquisition unit 401, used to obtain parameter information of the compressor during variable frequency operation, wherein the parameter information characterizes the speed fluctuation generated by each order of load torque in the current load torque of the compressor; a compensation determination unit 402, used to determine N compensation orders of the current load torque according to the parameter information, wherein the N compensation orders include at least one order of the current load torque; and a fluctuation compensation unit 403, used to perform torque fluctuation compensation on the load torque components corresponding to the N compensation orders.

[0071] In some embodiments, the parameter information includes a variable frequency parameter for controlling the operating frequency of the compressor, and the compensation determination unit 402 includes: an interval determination subunit, used to determine a target parameter interval in which the variable frequency parameter is located from M preset parameter intervals, M is an integer greater than 1, and the M preset parameter intervals are respectively pre-configured with compensation order information, and the M preset parameter intervals are divided by the variation range of the variable frequency parameter, and the preset parameter interval with a larger parameter value has a pre-configured compensation order information indicating more compensation orders; at least based on the compensation order information pre-configured in the target parameter interval, determine the N compensation orders of the current load torque.

[0072] In some embodiments, the order determination subunit can be used to: determine the candidate compensation orders of the current load torque based on the compensation order information pre-configured in the target parameter interval; obtain from the candidate compensation orders each order in which the speed fluctuation amplitude generated by the load torque component is greater than a preset frequency threshold, to obtain the N compensation orders, wherein the parameter information also includes the speed fluctuation amplitude generated by the load torque component of the candidate compensation orders.

[0073] In some embodiments, the order determination subunit can be used to: if the parameter value of the frequency conversion parameter is less than a second parameter threshold and not less than the first parameter threshold, determine that the candidate compensation order is the first order to K2 order of the current load torque, and the second parameter threshold is greater than the first parameter threshold, wherein K1 is greater than K2 and both are positive integers; if the parameter value of the frequency conversion parameter is not less than the second parameter threshold, determine that the candidate compensation order is at least the first order of the current load torque.

[0074] In some embodiments, the order determination subunit can be used to: extract the load torque component of each candidate compensation order from the current load torque, the candidate compensation orders include at least one, and the parameter information also includes the speed fluctuation amplitude generated by the load torque component of each candidate compensation order; for each candidate compensation order, if the speed fluctuation threshold generated by the load torque component of the candidate compensation order is greater than a preset frequency threshold, the candidate compensation order is used as one of the N compensation orders.

[0075] In some implementations, the frequency conversion parameter is a maximum effective duty cycle of a three-phase inverter circuit for driving the compressor or a target operating frequency of the compressor.

[0076] In some embodiments, the compensation determination unit 402 can be used to: extract load torque components of order 1 to K from the current load torque, and use the first order of the current load torque as one of the N compensation orders, where K is a preset integer value greater than N; determine the rotation fluctuation amplitude generated by the load torque components of order 2 to K, and the parameter information includes the speed fluctuation amplitude generated by the load torque components of order 2 to K in the current load torque; if the speed fluctuation amplitude generated by the load torque component of order X is greater than a preset frequency threshold, use the X order as one of the N compensation orders, where X is 2 to K.

[0077] In some embodiments, the fluctuation compensation unit 403 may include: a coefficient determination subunit, used to obtain the current direct-axis current and motor parameters of the compressor; determine the torque coefficient based on the current direct-axis current and motor parameters; a compensation execution subunit, used to determine, for each of the N compensation orders, the cross-axis current compensation value of the compensation order at least based on the torque coefficient, and perform torque fluctuation compensation on the load torque component of the compensation order based on the cross-axis current compensation value of the compensation order.

[0078] In some embodiments, the compensation execution subunit can be used to: for each of the N compensation orders, determine the cross-axis current compensation value of the compensation order based on the torque coefficient and the current limiting value corresponding to the compensation order; wherein the sum of the current limiting values ​​of the N compensation orders is less than a target parameter threshold, and the target reference threshold is determined based on the motor demagnetization current and a preset protection coefficient.

[0079] Based on the same inventive concept, the present invention also provides an air conditioning device. Figure 5 FIG. 2 shows a schematic diagram of the structure of an air conditioning device in an embodiment of the present invention. Figure 5 As shown, the air conditioning equipment also includes: a memory 504, a processor 502, and a computer program stored in the memory 504 and executable on the processor 502. When the processor 502 executes the program, the torque fluctuation compensation method for low-frequency operation of the compressor described in any of the above-mentioned embodiments is implemented.

[0080] Among them, Figure 5 In the embodiment of the present invention, a bus architecture (represented by bus 500) is shown, which may include any number of interconnected buses and bridges, and bus 500 links various circuits including one or more processors represented by processor 502 and memory represented by memory 504. Bus 500 may also link various other circuits such as peripherals, voltage regulators, and power management circuits, which are well known in the art and are therefore not further described herein. Bus interface 505 provides an interface between bus 500 and receiver 501 and transmitter 503. Receiver 501 and transmitter 503 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 502 is responsible for managing bus 500 and general processing, while memory 504 may be used to store data used by processor 502 when performing operations.

[0081] Based on the same inventive concept, the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the torque fluctuation compensation method for low-frequency operation of a compressor as described in any of the above-mentioned embodiments.

[0082] Although some embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the present invention.

[0083] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for compensating torque fluctuations during low-frequency operation of a compressor, characterized in that: include: Acquiring parameter information of the compressor during variable frequency operation, wherein the parameter information affects the speed fluctuation magnitude generated by the compressor; Determine N compensation orders of the current load torque of the compressor according to the parameter information, wherein the N compensation orders include at least one order of the current load torque, and N is a positive integer; Torque ripple compensation is performed on the load torque components of the N compensation orders.

2. The method according to claim 1, characterized in that The parameter information includes a frequency conversion parameter for controlling the operating frequency of the compressor; The determining, according to the parameter information, N compensation orders of the current load torque of the compressor comprises: Determine a target parameter interval in which the frequency conversion parameter is located from M preset parameter intervals, where M is an integer greater than 1, and the M preset parameter intervals are respectively pre-configured with compensation order information, and the M preset parameter intervals are formed by dividing the variation range of the frequency conversion parameter, and the compensation order information pre-configured in the preset parameter interval with a larger parameter value indicates that there are more compensation orders; The N compensation orders of the current load torque are determined at least according to the compensation order information pre-configured in the target parameter interval.

3. The method according to claim 2, characterized in that , the determining of the N compensation orders of the current load torque at least according to the compensation order information pre-configured in the target parameter interval comprises: Determining a candidate compensation order of the current load torque according to compensation order information pre-configured in the target parameter interval; From the candidate compensation orders, each order in which the speed fluctuation amplitude generated by the load torque component is greater than the preset frequency threshold is obtained to obtain the N compensation orders, wherein the parameter information also includes the speed fluctuation amplitude generated by the load torque component of the candidate compensation order.

4. The method according to claim 3, characterized in that The step of determining the candidate compensation order of the current load torque according to the compensation order information pre-configured in the target parameter interval includes: If the parameter value of the frequency conversion parameter is less than the first parameter threshold, determining the candidate compensation order to be the first order to K1 order of the current load torque; If the parameter value of the frequency conversion parameter is less than the second parameter threshold value and not less than the first parameter threshold value, the candidate compensation order is determined to be the first order to K2 order of the current load torque, and the second parameter threshold value is greater than the first parameter threshold value, wherein K1 is greater than K2 and both are positive integers; If the parameter value of the frequency conversion parameter is not less than the second parameter threshold, it is determined that the candidate compensation order is at least an order of the current load torque.

5. The method according to claim 3, characterized in that The step of obtaining, from the candidate compensation orders, each order of the rotation speed fluctuation amplitude generated by the load torque component being greater than a preset frequency threshold, comprises: Extracting a load torque component of each candidate compensation order from the current load torque, the candidate compensation order includes at least one, and the parameter information also includes a speed fluctuation amplitude generated by the load torque component of each candidate compensation order; For each of the candidate compensation orders, if a speed fluctuation threshold generated by a load torque component of the candidate compensation order is greater than a preset frequency threshold, the candidate compensation order is used as one of the N compensation orders.

6. The method according to claim 2, characterized in that The frequency conversion parameters include a maximum effective duty cycle of a three-phase inverter circuit for driving the compressor or a target operating frequency of the compressor.

7. The method according to claim 1, characterized in that The determining, according to the parameter information, N compensation orders of the current load torque of the compressor comprises: Extracting load torque components of order 1 to K from the current load torque, and using the first order of the current load torque as one of the N compensation orders, where K is a preset integer value greater than N; Determine the rotation fluctuation amplitude generated by the load torque components of order 2 to K, wherein the parameter information includes the rotation speed fluctuation amplitude generated by the load torque components of order 2 to K in the current load torque; If the speed fluctuation amplitude generated by the load torque component of order X is greater than the preset frequency threshold, the order X is used as one of the N compensation orders, and X is 2 to K.

8. The method according to any one of claims 1 to 7, characterized in that The performing torque fluctuation compensation on the load torque components of the N compensation orders comprises: Obtaining current direct-axis current and motor parameters of the compressor; Determine the torque coefficient according to the current direct-axis current and the motor parameters; For each of the N compensation orders, a quadrature-axis current compensation value of the compensation order is determined at least according to the torque coefficient, and torque fluctuation compensation is performed on the load torque component of the compensation order according to the quadrature-axis current compensation value of the compensation order.

9. The method according to claim 8, characterized in that The determining, for each compensation order of the N compensation orders, a quadrature-axis current compensation value of the compensation order at least according to the torque coefficient, comprises: For each compensation order of the N compensation orders, determining a quadrature-axis current compensation value of the compensation order based on the torque coefficient and a current limit value corresponding to the compensation order; The sum of the current limiting values ​​of the N compensation orders is less than the target parameter threshold, and the target reference threshold is determined according to the motor demagnetization current and a preset protection coefficient.

10. A fluctuation compensation device for low-frequency operation of a compressor, characterized in that: include: A parameter acquisition unit, used to acquire parameter information of the compressor during variable frequency operation, wherein the parameter information represents the speed fluctuation magnitude generated by each order of load torque in the current load torque of the compressor; A compensation determination unit, configured to determine N compensation orders of the current load torque according to the parameter information, wherein the N compensation orders include at least one order of the current load torque; The fluctuation compensation unit is used to perform torque fluctuation compensation on the load torque components corresponding to the N compensation orders.

11. An air conditioning device, characterized in that: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the method for compensating torque fluctuations during low-frequency operation of a compressor as claimed in any one of claims 1 to 9 is implemented.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the torque fluctuation compensation method for low-frequency operation of a compressor described in any one of claims 1 to 9 is implemented.

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