Compressor low-frequency operation control method and device, air conditioning equipment and medium

Abstract

The invention discloses a low-frequency operation control method and device for a compressor, air conditioning equipment and a medium, and the method comprises the steps that if the compressor is in a preset low-frequency state, the compressor is controlled to operate according to a phase current with a given first target amplitude, and the direct-axis current of the compressor is observed according to a preset observation frequency; and if the direct-axis current observed value obtained through current observation exceeds the target current range, the amplitude of the phase current is adjusted from the first target amplitude to the second target amplitude according to the size relation between the direct-axis current observed value and the target current range, so that the phase current is changed to the phase current with the given second target amplitude to control the compressor to operate. The technical problems that the compressor is poor in stability and prone to being out of control during low-frequency operation are solved.

Description

Technical Field

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

[0002] 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 rotor position of its permanent magnet motor is estimated by an algorithm. When the conventional compressor runs at a mechanical frequency below 10Hz, the back electromotive force is small, the signal-to-noise ratio of the position sensorless algorithm is low, and it is greatly affected by external interference, and the estimation of the rotor speed and rotor position is inaccurate.

[0003] The estimation of rotor speed and rotor position is inaccurate. As a result, the cross-axis current Iq and direct-axis current Id calculated based on the estimated rotor position are inaccurate. In the related art, the operation of the compressor is controlled based on the calculated cross-axis current Iq and direct-axis current Id, which will cause the compressor to lose control when operating at a low frequency. Among them, the large load torque disturbance generated by the refrigerant compression of the single-rotor compressor is more likely to lose control when operating at a low frequency. Therefore, there is currently a minimum stable operating frequency, and a minimum frequency that is not lower than the minimum stable operating frequency is set. When the target operating frequency calculated based on the temperature difference between the ambient temperature and the set temperature is lower than the set minimum frequency, the compressor will operate at the minimum frequency or shut down. Summary of the invention

[0004] The present invention provides a method, device, air conditioning equipment and medium for controlling low-frequency operation of a compressor, so as to solve the technical problem that the compressor has poor stability and is easy to lose control when operating at a low frequency.

[0005] In a first aspect of the present invention, a method for controlling low-frequency operation of a compressor is provided, comprising: if the compressor is in a preset low-frequency state, controlling the operation of the compressor according to a phase current with a given first target amplitude, and observing the direct-axis current of the compressor at a preset observation frequency; if the direct-axis current observation value obtained by the current observation exceeds the target current range, adjusting the amplitude of the phase current from the first target amplitude to a second target amplitude according to the magnitude relationship between the direct-axis current observation value and the target current range, so as to change the operation of the compressor to be controlled according to the phase current with the given second target amplitude.

[0006] In some embodiments, the method further includes: during the variable frequency operation of the compressor, obtaining a variable frequency parameter for controlling the operating frequency of the compressor; if the parameter value of the variable frequency parameter decreases to less than a first parameter threshold, determining that the compressor enters the preset low-frequency state; if the parameter value of the variable frequency parameter increases to greater than a second parameter threshold, determining that the compressor exits the preset low-frequency state, wherein the second parameter threshold is greater than or equal to the first parameter threshold.

[0007] In some implementations, the method further includes: when the parameter value of the frequency conversion parameter decreases to be less than the first parameter threshold, determining a target initial value that matches the current load; and the given first target amplitude is the target initial value.

[0008] In some embodiments, adjusting the amplitude of the phase current from the first target amplitude to the second target amplitude based on the magnitude relationship between the direct-axis current observation value and the target current range includes: if the direct-axis current observation value is greater than an upper current threshold of the target current range, reducing the first target amplitude to obtain a second target amplitude less than the first target amplitude; if the direct-axis current observation value is less than a lower current threshold of the target current range, increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude; and resetting the amplitude of the phase current to the second target amplitude.

[0009] In some embodiments, reducing the first target amplitude to obtain a second target amplitude smaller than the first target amplitude includes: obtaining the second target amplitude based on the difference between the first target amplitude and the target current decrement; increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude includes: obtaining the second target amplitude based on the sum of the first target amplitude and the target current increment.

[0010] In some implementations, the method further includes: if the compressor exits the preset low-frequency state, switching to adopting an Id=0 control strategy or an MTPA control strategy to control the operation of the compressor.

[0011] In some embodiments, observing the direct-axis current of the compressor at a preset observation frequency includes: using a pre-built state observer to observe the rotor position and rotor speed of the compressor at the preset observation frequency to obtain a current rotor position observation value of the compressor; and estimating based on the current rotor position observation value of the compressor to obtain a direct-axis current observation value of the compressor.

[0012] In a second aspect of the present invention, a compressor low-frequency operation control device is provided, comprising: a first control unit, for controlling the operation of the compressor according to a phase current of a given first target amplitude if the compressor is in a preset low-frequency state; a current observation unit, for observing the direct-axis current of the compressor at a preset observation frequency; an amplitude adjustment unit, for adjusting the amplitude of the phase current from the first target amplitude to a second target amplitude according to the relationship between the direct-axis current observation value and the target current range if the direct-axis current observation value obtained by the current observation exceeds the target current range, so that the first control unit is changed to control the operation of the compressor according to the phase current of the given second target amplitude.

[0013] 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 implements the compressor low-frequency operation control method when executing the computer program.

[0014] 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 compressor low-frequency operation control method is implemented.

[0015] According to one or more embodiments provided by the present invention, at least the following technical effects or advantages are achieved:

[0016] If the compressor is in a preset low-frequency state, the operation of the compressor is controlled according to the phase current of a given first target amplitude, and the direct-axis current of the compressor is observed at a preset observation frequency; if the direct-axis current observation value obtained in the current observation exceeds the target current range, the amplitude of the phase current is adjusted from the first target amplitude to the second target amplitude according to the magnitude relationship between the direct-axis current observation value and the target current range, so as to change to the phase current of the given second target amplitude to control the operation of the compressor. Through the above technical scheme, when the compressor is running at a low frequency, the operation of the compressor is controlled based on the phase current of a given amplitude, and the phase current amplitude will not fluctuate with the load torque within a mechanical cycle, but will remain constant within a mechanical cycle. The direct-axis current observation value is only used as a reference for whether to adjust the phase current amplitude, and is not directly used to control the compressor. Therefore, when the compressor is running at a low frequency, an inaccurate direct-axis current observation value will not affect the operating stability of the compressor, thereby improving the stability of the low-frequency operation of the compressor, so that the compressor can run at a lower frequency and will not lose control when running at a low frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 A flowchart of a compressor low-frequency operation control method provided by an embodiment of the present invention;

[0019] 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;

[0020] Figure 3 A schematic diagram of phase current amplitude and corresponding modulation voltage when the compressor low-frequency operation control method provided by an embodiment of the present invention is adopted;

[0021] Figure 4 Schematic diagram of phase current amplitude and corresponding modulation voltage when Id=0 control strategy is adopted;

[0022] Figure 5 A schematic diagram of the structure of a low-frequency operation control device for a compressor provided by an embodiment of the present invention;

[0023] Figure 6 A schematic diagram of the structure of an air conditioning device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] 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.

[0026] The present invention provides a compressor low-frequency operation control method, which is applied to a compressor requiring variable frequency control. Figure 1 Flow chart of the compressor low frequency operation control method provided by the embodiment of the present invention. Figure 1 As shown, the compressor low-frequency operation control method includes the following steps S101 to S103.

[0027] S101: If the compressor is in a preset low-frequency state, the operation of the compressor is controlled according to a phase current with a given first target amplitude, and the direct-axis current of the compressor is observed at a preset observation frequency.

[0028] In some embodiments, it can be determined whether the compressor is in a preset low-frequency state based on a variable frequency parameter used to control the operating frequency of the compressor: during the variable frequency operation of the compressor, the variable frequency parameter used to control the operating frequency of the compressor is obtained; if the parameter value of the variable frequency parameter decreases to less than a first parameter threshold, it is determined that the compressor enters the preset low-frequency state; if the parameter value of the variable frequency parameter increases to greater than a second parameter threshold, it is determined that the compressor exits the preset low-frequency state and enters a state of operation at a higher frequency relative to the preset low-frequency state, wherein the second parameter threshold is greater than or equal to the first parameter threshold.

[0029] Figure 2 The 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.

[0030] It should be noted that the first parameter threshold and the second parameter threshold in the present invention are parameters of the same type as the variable frequency parameter. That is, if the variable frequency parameter is the target operating frequency of the compressor, the first parameter threshold is the first frequency threshold, and the second parameter threshold is the second frequency threshold that is greater than or equal to the first frequency threshold, wherein the first frequency threshold is a frequency value that is not less than the minimum stable operating frequency of the compressor. During the variable frequency operation of the compressor, if the target operating frequency decreases to less than the first frequency threshold, it is determined that the compressor enters a preset low-frequency state; if the target operating frequency increases to greater than the second frequency threshold, it is determined that the compressor exits the preset low-frequency state, wherein the second frequency threshold is greater than or equal to the first frequency threshold.

[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] In some implementations, the switch duty cycle difference 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] It should be noted that the first parameter threshold and the second parameter threshold need to be the same type of parameters as the frequency conversion parameter. That is, if the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit 10, the first parameter threshold is the first duty cycle threshold, and the second parameter threshold is the second duty cycle threshold that is greater than or equal to the first duty cycle threshold, wherein the first duty cycle threshold and the second duty cycle threshold can both be adjusted according to the dead time T of the three-phase inverter circuit 10. dand the switching period Tsw, for example, the first duty cycle threshold DytyLim1 and the second duty cycle threshold DytyLim2 can be set to the dead zone duty cycle T d / 5 to 10 times of Tsw:

[0035]

[0036] During the variable frequency operation of the compressor, if the maximum effective duty cycle of the three-phase inverter circuit 10 is reduced to less than the first duty cycle threshold, it is determined that the compressor enters the preset low-frequency state; if the target operating frequency increases to greater than the second duty cycle threshold, it is determined that the compressor exits the preset low-frequency state.

[0037] In some embodiments, observing the direct-axis current of the compressor according to a preset observation frequency may include: observing the rotor position and rotor speed of the compressor according to the preset observation frequency through a pre-built state observer, and obtaining the current rotor position observation value of the compressor; estimating the direct-axis current of the compressor according to the current rotor position observation value of the compressor, and obtaining the direct-axis current observation value of the compressor. Among them, the direct-axis current observation value is used to rotate the two-phase given current in the stationary coordinate system, and the direct-axis current observation value and the quadrature-axis current observation value can be obtained accordingly. It can be understood that the state observer here can use a sliding mode observer (SMO), a linear Romberg observer or a Kalman observer. The phase voltage and phase current of the motor are measured by a sensor according to the preset observation frequency, and the current phase current measurement value and phase voltage measurement value of the compressor are obtained accordingly; the state observer estimates the current rotor speed and the position angle of the rotor position of the compressor according to the current phase current measurement value and voltage measurement value, and the estimated rotor position position angle is the rotor position observation value.

[0038] It is understandable that the preset observation frequency can be set according to the switching frequency of the three-phase inverter circuit 10, for example, the preset observation frequency can be 1 to 2 times the switching frequency of the three-phase inverter circuit 10. Of course, other logics can also be used to set the preset observation frequency.

[0039] In some embodiments, when the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, when the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, a target initial value matching the current load is determined; the given first target amplitude is the target initial value. That is, when the compressor enters the preset low-frequency state, the given first target amplitude of the compressor is the target initial value. Among them, the target initial value matches the current load. In order to match the given first target amplitude with the current load when the compressor enters the preset low-frequency state, the phase current amplitude reached by the compressor based on the Id=0 control strategy or the MTPA control strategy when entering the preset low-frequency state is obtained as the target initial value. Alternatively, the product result of the phase current amplitude reached by the architecture compressor when entering the preset low-frequency state and the first preset coefficient is used as the target initial value, wherein the first preset coefficient can be greater than 1 and less than 2. For example, before entering the preset low-frequency state, the compressor operation is controlled based on the Id=0 control strategy or the MTPA control strategy. When entering the preset low-frequency state, the amplitude of the phase current changes to 2 amperes. Then, the target initial value can be given as 2 amperes or slightly greater than 2 amperes, which can match the current load.

[0040] S102: If the direct-axis current observation value obtained in the current observation exceeds the target current range, the amplitude of the phase current is adjusted from the first target amplitude to the second target amplitude according to the size relationship between the direct-axis current observation value and the target current range, so as to change the compressor operation to be controlled according to the phase current of the given second target amplitude.

[0041] It can be understood that when the compressor enters the preset low-frequency state, after setting the first target amplitude as the target initial value, the direct-axis current of the compressor is observed according to the preset observation frequency. Each time the direct-axis current observation value is observed, it is determined whether the direct-axis current observation value obtained by the current observation exceeds the target current range. If the direct-axis current observation value obtained by the current observation is within the target current range, the phase current amplitude will not be adjusted, and the next observation of the direct-axis current will be waited; if the direct-axis current observation value obtained by the current observation exceeds the target current range, the amplitude of the phase current is adjusted from the first target amplitude to the second target amplitude according to the size relationship between the direct-axis current observation value obtained by the current observation and the target current range, so as to change to the phase current according to the given second target amplitude to control the operation of the compressor.

[0042] It should be noted that the first target amplitude and the second target amplitude are relative to before and after each adjustment of the phase current amplitude, and are not two fixed amplitudes. That is to say, the phase current amplitude before each adjustment of the phase current amplitude is the first target amplitude, and the phase current amplitude after each adjustment of the phase current amplitude is the second target amplitude. For example, when entering the preset low-frequency state, the phase current amplitude is set to 2A, and the direct-axis current observation value obtained from a certain observation exceeds the target current range for the first time. The given phase current amplitude is adjusted from the first phase current threshold of 2A to the second phase current threshold of 3A. After that, the direct-axis current observation value obtained from another observation exceeds the target current range for the second time, and the given phase current amplitude is adjusted from the first phase current threshold of 3A to the second phase current threshold of 4A, and so on, until the compressor exits the preset low-frequency state.

[0043] It is understandable that the target current range is constructed based on the upper current threshold and the lower current threshold. For example, the target current range can be expressed as [idMin, idMax], where the lower current threshold of the target current range is greater than 0 and less than the upper current threshold, and the upper current threshold is the product of the current phase current amplitude and the preset coefficient, where the second preset coefficient is greater than 0 and less than 1. For example, if the current phase current amplitude is 3 amperes, then the upper current threshold can be 3 amperes * 0.5 = 1.5 amperes, and the lower current threshold can be 0.1 amperes. The above logic can be used to set the current range more reasonably.

[0044] In some embodiments, adjusting the given value of the phase current amplitude based on the size relationship between the direct-axis current observation value obtained by the current observation and the target current range may include: if the direct-axis current observation value is greater than the upper current threshold of the target current range, reducing the first target amplitude to obtain a second target amplitude less than the first target amplitude; if the direct-axis current observation value is less than the lower current threshold of the target current range, increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude; after obtaining the second target amplitude, resetting the amplitude of the given phase current to the second target amplitude.

[0045] In some embodiments, reducing the first target amplitude to obtain a second target amplitude smaller than the first target amplitude may include: obtaining the second target amplitude Is' according to the difference between the first target amplitude Is and the target current decrement dIsp: Is'=Is-dIsp, wherein the target current decrement may be a pre-set fixed current value, thereby achieving an increase in a given phase current amplitude according to a fixed step size, and the target current decrement may also be determined according to the magnitude relationship between the direct-axis current observation value obtained currently and the current threshold of the target current range: the greater the difference between the direct-axis current observation value obtained currently and the upper limit current threshold of the target current range, the greater the target current decrement.

[0046] In some embodiments, increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude may include: obtaining the second target amplitude Is' according to the sum of the first target amplitude Is and the target current increment dIsn: Is' = Is + dIsn. The target current increment may be a preset fixed current value, so as to achieve a fixed step adjustment of a given phase current amplitude, and the target current increment may also be determined according to the magnitude relationship between the direct-axis current observation value obtained at the current time and the current threshold of the target current range: the greater the difference between the lower limit current threshold of the target current range and the direct-axis current observation value obtained at the current time, the greater the target current increment.

[0047] It should be noted that the xy coordinate system is established to replace the dq coordinate system, the current amplitude IsSet is given, and the two-phase current in the xy coordinate system is given according to a fixed angle ratio: ix=is*cos(t) and iy=is*sin(t), where t is [0,π / 2], which can be directly taken as 0. Among them, the rotation speed of the xy coordinate system and the stationary coordinate system (that is, the α-β coordinate system) is calculated according to the program (when the target speed is w, the given speed is w), and the angle θ of the xy coordinate system relative to the stationary coordinate system can be calculated according to the rotation speed, and the two-phase current in the stationary coordinate system can be obtained according to the angle θ and the two-phase current in the xy coordinate system. In the xy coordinate system, the current loop is constructed to calculate the feedback current ixf, iyf respectively, and the output value of the modulation voltage is calculated according to the feedback current ixf, iyf and the target current ix, iy and acts on the three-phase inverter circuit. The current and voltage in the stationary coordinate system can be used to estimate the speed w_hat and rotor position theta_hat of the compressor motor. The rotor position theta_hat can be further used to rotate the two-phase current in the stationary coordinate system to obtain Id and Iq, where the calculated Id is the direct-axis current observation value in step S101.

[0048] In some embodiments, if the compressor exits the preset low-frequency state, it switches to controlling the operation of the compressor using the Id = 0 control strategy or the MTPA control strategy. Specifically, if the motor of the compressor is a surface-mounted permanent magnet motor, when the compressor exits the preset low-frequency state, it switches to controlling the operation of the compressor using the Id = 0 control strategy, so that the torque control performance of the compressor during high-frequency operation is good and the torque ripple is small. If the motor of the compressor is an interior permanent magnet motor, when the compressor exits the preset low-frequency state, it switches to controlling the operation of the compressor using the MTPA control strategy, which improves the utilization rate of the inverter voltage during high-frequency operation of the compressor, reduces losses, and improves the efficiency of the motor. Under the Id = 0 control strategy or the MTPA control strategy, the single-rotor compressor adjusts Iq according to the load torque. Since the load torque is in a fluctuating state, the obtained Iq target value shows a fluctuating state, and there will be a short period of time in each mechanical cycle when the absolute value of Iq is close to 0, that is, it is determined to be close to 0 by means such as abs(Iq) < Ismin. On the time scale, as Figure 3 shown, the amplitude of the phase current of the motor also changes within the mechanical cycle.

[0049] The single-rotor compressor sets the direct-axis current Id to a stable value and adjusts the quadrature-axis current Iq according to the load torque. Since the load torque is in a fluctuating state, the obtained Iq target value for controlling the compressor shows a fluctuating state, as Figure 3 shown. There will be a short period of time in each mechanical cycle when the absolute value of Iq is close to 0. At this time, if the Id = 0 control strategy or the MTPA control strategy (the value calculated by MTPA is usually a negative value close to 0) is used for closed-loop control, the amplitude of the phase current will be close to 0. The dead zones of positive and negative currents will cause different modulation voltage deviations. Therefore, the modulation voltage deviation generated by the dead zone is usually compensated according to the positive and negative polarities of the current. When using the Id = 0 control or the MTPA control, when the load torque is close to 0, the amplitude of the phase current is close to 0. At this time, it is difficult to accurately judge the positive and negative polarities of the current, and the dead zone compensation is inaccurate. When the compressor operates at low frequency, the signal-to-noise ratio of the position-sensorless algorithm is low and it is greatly affected by external interference. Inaccurate dead zone compensation will lead to inaccurate estimation of speed and angle, and is prone to out-of-control. According to one or more embodiments provided above of the present invention, when the compressor operates at low frequency, it is no longer driven to operate based on the Iq target value calculated by observing the rotor position and speed, but the operation of the compressor is open-loop controlled based on the phase current with a given amplitude. As Figure 4 shown, within a mechanical cycle, the amplitude of the phase current always remains at 2A and does not fluctuate. The Id calculated by observing the rotor position and speed is only used as reference information for adjusting the amplitude of the phase current. Therefore, even if the observed rotor position and speed are inaccurate, it will not affect the operation stability of the compressor. Thus, the stability of the compressor during low-frequency operation is improved, enabling the compressor to operate at a lower frequency.

[0050] Based on the same inventive concept, the present invention provides a compressor low-frequency operation control device. Figure 5 Schematic diagram of the structure of the low-frequency operation control device of the compressor provided by the embodiment of the present invention. Figure 5 As shown, the compressor low-frequency operation control device includes: a first control unit 501, used for controlling the operation of the compressor according to a phase current with a given first target amplitude if the compressor is in a preset low-frequency state; a current observation unit 502, used for observing the direct-axis current of the compressor at a preset observation frequency; an amplitude adjustment unit 503, used for adjusting the amplitude of the phase current from the first target amplitude to the second target amplitude according to the size relationship between the direct-axis current observation value and the target current range if the direct-axis current observation value obtained by the current observation exceeds the target current range, so that the first control unit 501 is changed to control the operation of the compressor according to the phase current with the given second target amplitude.

[0051] In some embodiments, the compressor low-frequency operation control device may also include: a parameter acquisition unit, used to acquire a variable frequency parameter used to control the operating frequency of the compressor during the variable frequency operation of the compressor; a state determination unit, used to determine that the compressor enters the preset low-frequency state if the parameter value of the variable frequency parameter decreases to less than a first parameter threshold; if the parameter value of the variable frequency parameter increases to greater than a second parameter threshold, determine that the compressor exits the preset low-frequency state, wherein the second parameter threshold is greater than or equal to the first parameter threshold.

[0052] In some embodiments, the compressor low-frequency operation control device may also include: an initial setting unit, used to determine a target initial value matching the current load when the parameter value of the frequency conversion parameter is reduced to less than the first parameter threshold; and give the first target amplitude as the target initial value.

[0053] In some embodiments, the amplitude adjustment unit 503 may include: a reduction subunit, used to reduce the first target amplitude if the direct-axis current observation value is greater than an upper current threshold of the target current range, to obtain a second target amplitude less than the first target amplitude; an increase subunit, used to increase the first target amplitude if the direct-axis current observation value is less than a lower current threshold of the target current range, to obtain a second target amplitude greater than the first target amplitude; and a reset subunit, used to reset the amplitude of the phase current to the second target amplitude.

[0054] In some embodiments, the decreasing subunit is used to obtain the second target amplitude according to the difference between the first target amplitude and the target current decrement; the increasing subunit is used to obtain the second target amplitude according to the sum of the first target amplitude and the target current increment.

[0055] In some embodiments, the compressor low-frequency operation control device may further include a second control unit for: if the compressor exits the preset low-frequency state, switching to adopting the Id=0 control strategy or the MTPA control strategy to control the operation of the compressor.

[0056] In some embodiments, the current observation unit 502 may include: a rotor position observation subunit, which is used to use a pre-built state observer to observe the rotor position and rotor speed of the compressor according to the preset observation frequency to obtain the current rotor position observation value of the compressor; and a current estimation subunit, which is used to estimate based on the current rotor position observation value of the compressor to obtain the direct-axis current observation value of the compressor.

[0057] Based on the same inventive concept, the present invention also provides an air conditioning device. Figure 6 FIG. 1 is a schematic diagram of the structure of the air conditioning device in an embodiment of the present invention. Figure 6 As shown, the air conditioning device includes: a memory 604, a processor 602, and a computer program stored in the memory 604 and executable on the processor 602. When the processor 602 executes the program, the compressor low-frequency operation control method of any of the above-mentioned embodiments is implemented.

[0058] Among them, Figure 6 In the embodiment of the present invention, a bus architecture (represented by bus 600) is shown, which may include any number of interconnected buses and bridges, and bus 600 links various circuits including one or more processors represented by processor 602 and memory represented by memory 604. Bus 600 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 605 provides an interface between bus 600 and receiver 601 and transmitter 603. Receiver 601 and transmitter 603 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 602 is responsible for managing bus 600 and general processing, while memory 604 may be used to store data used by processor 602 when performing operations.

[0059] Based on the same inventive concept, the present invention further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the compressor low-frequency operation control method of any of the above-mentioned embodiments.

[0060] 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.

[0061] 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 compressor low frequency operation control method, characterized in that: include: If the compressor is in a preset low-frequency state, controlling the compressor to operate according to a phase current with a given first target amplitude, and observing the direct-axis current of the compressor at a preset observation frequency; If the direct-axis current observation value obtained in the current observation exceeds the target current range, the amplitude of the phase current is adjusted from the first target amplitude to the second target amplitude according to the magnitude relationship between the direct-axis current observation value and the target current range, so as to change the compressor operation to be controlled according to the phase current given the second target amplitude.

2. The method according to claim 1, characterized in that Also includes: During the variable frequency operation of the compressor, obtaining a variable frequency parameter for controlling the operating frequency of the compressor; If the parameter value of the frequency conversion parameter decreases to be less than a first parameter threshold, determining that the compressor enters the preset low-frequency state; If the parameter value of the frequency conversion parameter increases to be greater than a second parameter threshold, it is determined that the compressor exits the preset low-frequency state, wherein the second parameter threshold is greater than or equal to the first parameter threshold.

3. The method according to claim 2, characterized in that The method further comprises: When the parameter value of the frequency conversion parameter decreases to be less than the first parameter threshold, determining a target initial value matching the current load; The first target amplitude is given as the target initial value.

4. The method according to any one of claims 1 to 3, characterized in that The adjusting the amplitude of the phase current from the first target amplitude to the second target amplitude according to the magnitude relationship between the direct-axis current observation value and the target current range includes: If the direct-axis current observation value is greater than an upper current threshold of the target current range, reducing the first target amplitude to obtain a second target amplitude less than the first target amplitude; If the direct-axis current observation value is less than the lower current threshold of the target current range, increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude; The amplitude of the phase current is reset to the second target amplitude.

5. The method according to claim 4, characterized in that: The reducing the first target amplitude to obtain a second target amplitude smaller than the first target amplitude comprises: obtaining the second target amplitude according to a difference between the first target amplitude and the target current decrement; The increasing the first target amplitude to obtain a second target amplitude greater than the first target amplitude includes: obtaining the second target amplitude according to the sum of the first target amplitude and a target current increment.

6. The method according to claim 1, characterized in that Also includes: If the compressor exits the preset low-frequency state, the control strategy is switched to the Id=0 control strategy or the MTPA control strategy to control the operation of the compressor.

7. The method according to claim 1, characterized in that The observing the direct-axis current of the compressor according to a preset observation frequency includes: Using a pre-built state observer, observing the rotor position and rotor speed of the compressor according to the preset observation frequency to obtain a current rotor position observation value of the compressor; The direct-axis current observation value of the compressor is estimated based on the current rotor position observation value of the compressor to obtain the direct-axis current observation value of the compressor.

8. A compressor low frequency operation control device, characterized in that: include: a first control unit, configured to control the operation of the compressor according to a phase current of a given first target amplitude if the compressor is in a preset low-frequency state; A current observation unit, used for observing the direct-axis current of the compressor according to a preset observation frequency; An amplitude adjustment unit is used to adjust the amplitude of the phase current from the first target amplitude to the second target amplitude according to the magnitude relationship between the direct-axis current observation value and the target current range if the direct-axis current observation value obtained by the current observation exceeds the target current range, so that the first control unit changes to control the operation of the compressor according to the phase current given the second target amplitude.

9. 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 the processor implements the compressor low-frequency operation control method according to any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the compressor low-frequency operation control method described in any one of claims 1 to 7 is implemented.

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