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

Abstract

The invention discloses a compressor low-frequency operation control method and device, air conditioning equipment and a medium, and the method comprises the steps that frequency conversion parameters of a compressor in the frequency conversion operation process are obtained, and the frequency conversion parameters are parameters influencing the operation frequency of the compressor; the direct-axis current of the compressor is adjusted according to the parameter value change of the frequency conversion parameter, so that the amplitude of the direct-axis current is not smaller than a target current amplitude within a target time period, and the target time period is a time period when the parameter value of the frequency conversion parameter is smaller than a first parameter threshold value; when the parameter value of the frequency conversion parameter is smaller than the first parameter threshold value, the compressor is in the preset low-frequency state. The technical problem that the compressor is poor in stability during low-frequency operation is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-frequency motors, and in particular relates to a method and device for controlling low-frequency operation of a compressor, air-conditioning equipment and a medium. 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 uses position sensorless control, and the rotor position of its permanent magnet motor is estimated based on the position sensorless algorithm. When the compressor runs at a low frequency, 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, resulting in inaccurate estimation of the rotor position, which is easy to cause loss of control. The large load torque disturbance generated by the refrigerant compression of the single-rotor compressor is more prone to loss of control. Therefore, the compressor is unstable when running at a low frequency. Summary of the invention

[0004] The present invention provides a compressor low-frequency operation control method, device, air-conditioning equipment and medium, which are used to solve the technical problem of instability when the compressor is running 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: obtaining a variable frequency parameter of the compressor during variable frequency operation, wherein the variable frequency parameter is a parameter that affects the operating frequency of the compressor; adjusting the direct-axis current of the compressor according to a change in the parameter value of the variable frequency parameter, so that the amplitude of the direct-axis current is not less than a target current amplitude within a target time period, and the target current amplitude is greater than a zero value, the target time period is a time period when the parameter value of the variable frequency parameter is less than a first parameter threshold, and the parameter value of the variable frequency parameter being less than the first parameter threshold indicates that the compressor is in a preset low-frequency state.

[0006] In combination with the first aspect, in some embodiments, the direct-axis current of the compressor is adjusted according to the change in the parameter value of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within the target time period, including: within the target time period, setting the direct-axis current to a positive current value not less than a positive current threshold or a negative current value not greater than a negative current threshold, the amplitude of the positive current threshold is equal to the target current amplitude, and the amplitude of the negative current threshold is equal to the target current amplitude.

[0007] In combination with the first aspect, in some embodiments, the direct-axis current of the compressor is adjusted according to the change in the parameter value of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within the target time period, including: when the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, the direct-axis current is set to a positive current value not less than a positive current threshold, and the amplitude of the positive current threshold is equal to the target current amplitude; when the parameter value of the frequency conversion parameter increases to greater than a second parameter threshold, the direct-axis current is set to a negative current value not greater than a negative current threshold, the amplitude of the negative current threshold is equal to the target current amplitude, and the second parameter threshold is greater than the first parameter threshold.

[0008] In combination with the first aspect, in some embodiments, setting the direct-axis current to a positive current value that is not less than a positive current threshold value includes: setting the direct-axis current to a predetermined constant positive current value; determining the current phase current amplitude of the compressor based on the constant positive current value; if the current phase current amplitude is less than the target current amplitude, determining the target quadrature-axis current value and the target direct-axis current value based on the target speed and target torque required by the current load of the compressor; setting the direct-axis current to the target direct-axis current value, and setting the quadrature-axis current to the target quadrature-axis current value.

[0009] In combination with the first aspect, in some embodiments, the target quadrature-axis current value and the target direct-axis current value are determined according to the target speed and the target torque required by the current load of the compressor, including: according to the target speed and the target torque, obtaining the corresponding target quadrature-axis current value and the target direct-axis current value by looking up a table in offline calibration data, wherein the offline calibration data includes multiple quadrature-axis and direct-axis currents corresponding to multiple torques and speeds.

[0010] In combination with the first aspect, in some embodiments: the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit used to drive the compressor, and the first parameter threshold corresponds to the first preset duty cycle, or the frequency conversion parameter is the target operating frequency of the compressor, and the first parameter threshold corresponds to the first preset frequency.

[0011] In combination with the first aspect, in some embodiments, the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit used to drive the compressor, and the obtaining of the frequency conversion parameter of the compressor during the frequency conversion operation process includes: during the frequency conversion operation process of the compressor, obtaining the switch duty cycle difference between each two-phase inverter circuits in the three-phase inverter circuit of the compressor; based on the switch duty cycle difference between each two-phase inverter circuits in the three-phase inverter circuit, determining the effective duty cycle of the corresponding phase of the three-phase inverter circuit; and obtaining the maximum effective duty cycle from the three-phase effective duty cycles of the three-phase inverter circuit.

[0012] In combination with the first aspect, in some embodiments, it also includes: when the compressor is in variable frequency operation, obtaining fluctuation characterization information of the cross-axis current of the compressor; determining the target current amplitude based on the fluctuation characterization information, wherein the greater the fluctuation of the cross-axis current represented by the fluctuation characterization information, the greater the target current amplitude.

[0013] In a second aspect of the present invention, a compressor low-frequency operation control device is provided, comprising: a parameter acquisition unit, used to acquire the variable frequency parameters of the compressor during the variable frequency operation process, the variable frequency parameters are parameters that affect the operating frequency of the compressor; a current adjustment unit, used to adjust the direct-axis current of the compressor according to the parameter value change of the variable frequency parameters, so that the amplitude of the direct-axis current is not less than the target current amplitude within a target time period, and the target current amplitude is greater than zero, the target time period is a time period when the parameter value of the variable frequency parameter is less than a first parameter threshold, and the parameter value of the variable frequency parameter is less than the first parameter threshold, indicating that the compressor is in a preset low-frequency state.

[0014] 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 when the processor executes the computer program, the compressor low-frequency operation control method described in any embodiment of the first aspect is implemented.

[0015] 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 described in any embodiment of the first aspect is implemented.

[0016] According to one or more embodiments provided by the present invention, at least the following technical effects or advantages are achieved:

[0017] By obtaining the variable frequency parameters that affect the operating frequency of the compressor during the variable frequency operation of the compressor; adjusting the direct axis current of the compressor according to the variable frequency parameters, so that the amplitude of the direct axis current is not less than the target current amplitude greater than zero during the period when the parameter value of the variable frequency parameter is less than the first parameter threshold, and the parameter value of the variable frequency parameter is less than the first parameter threshold, indicating that the compressor is in a preset low frequency state. By setting the amplitude of the direct axis current to be greater than zero during the period when the parameter value of the variable frequency parameter is less than the first parameter threshold, the zero crossing point of the phase current of the compressor is clear when it is running at low frequency, and there is no longer a period of time close to zero, so that the direction of the phase current can be accurately determined, which is conducive to improving the accuracy of the modulation voltage deviation generated by the dead zone according to the positive and negative polarity compensation of the current when the compressor is running at low frequency, so that the position estimation is more accurate when the back electromotive force is small, which also improves the stability of low frequency operation and makes it less likely to get out of control. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 A flowchart of a compressor low-frequency operation control method provided by an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of a compressor controlled by a three-phase inverter circuit in an embodiment of the present invention;

[0021] Figure 3 : is a waveform diagram of the X-phase current and the X-phase modulation voltage when Id=0 in an embodiment of the present invention;

[0022] Figure 4 : is the waveform diagram of the X-phase current and the X-phase modulation voltage of the single-rotor compressor with Id=1A;

[0023] Figure 5 1 is a waveform diagram of the X-phase current and the X-phase modulation voltage when Id=-1A in an embodiment of the present invention;

[0024] Figure 6 Schematic diagram of the structure of a low-frequency operation control device for a compressor in an embodiment of the present invention;

[0025] Figure 7 Schematic diagram of the structure of the air conditioning device in the embodiment of the present invention. DETAILED DESCRIPTION

[0026] 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.

[0027] 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.

[0028] The invention provides a method for controlling low-frequency operation of a compressor. 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 steps S101-S102.

[0029] S101: Obtaining a variable frequency parameter of the compressor during variable frequency operation, where the variable frequency parameter is a parameter that affects the operating frequency of the compressor.

[0030] Figure 2 Schematic diagram of a compressor controlled by a three-phase inverter circuit in an embodiment of the present invention. Figure 2 As shown, the variable frequency parameter may be the target operating frequency of the compressor 10. The target operating frequency of the compressor 10 changes dynamically with the set temperature and the ambient temperature of the environment being acted on, that is, the mechanical frequency required by the compressor is 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. During the variable frequency operation of the compressor 10, the ambient temperature and the set temperature are continuously detected, and the dynamic changes of the target operating frequency are tracked according to the set temperature and the ambient temperature.

[0031] In other embodiments, Figure 2 As shown, the variable frequency parameter may be the maximum effective duty cycle of the three-phase inverter circuit 20 for driving the compressor 10. In the variable frequency operation process of the compressor 10, the switch duty cycle difference between each two-phase inverter circuit in the three-phase inverter circuit 20 is obtained; based on the switch duty cycle difference between each two-phase inverter circuit in the three-phase inverter circuit 20, the effective duty cycle of the corresponding phase inverter circuit is determined, so that the three-phase effective duty cycle corresponding to the three-phase inverter circuit 20 can be obtained; and the maximum effective duty cycle is obtained from the three-phase effective duty cycles corresponding to the three-phase inverter circuit.

[0032] It is understandable that 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 the two-phase inverter circuit. Duv, Dwu, and Dvw represent the difference in the switching duty cycle between two phases of UVW.

[0033] It is understandable that how to obtain the maximum effective duty cycle Dmax based on the effective duty cycles Du0, Dv0, and Dw0 of the three-phase inverter circuit 113 can be calculated by referring to the following formula:

[0034]

[0035] S102: Adjust the direct-axis current of the compressor according to the change of the parameter value of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within the target time period, and the target current amplitude is greater than zero. The target time period is the time period when the parameter value of the frequency conversion parameter is less than the first parameter threshold, and the parameter value of the frequency conversion parameter less than the first parameter threshold indicates that the compressor is in a preset low-frequency state.

[0036] Ismin represents the target current amplitude, and it is necessary to satisfy abs(Id)≥Ismin>0. It should be noted that, because the accuracy of the rotor position estimation is related to the mechanical frequency of the compressor, the relevant technology is that the permanent magnet synchronous motor of the compressor is always controlled by Id=0 or MTPA during the entire operation of the compressor, there will be a minimum stable operating frequency, and it is necessary to give the compressor a minimum operating frequency that is not lower than the minimum stable operating frequency. The compressor in the relevant technology does not operate at a frequency point below the minimum operating frequency. The preset low-frequency state in the embodiment of the present invention refers to the state where the target operating frequency of the compressor is lower than the minimum stable operating frequency. For example: the permanent magnet synchronous motor of the single-rotor compressor is always controlled by Id=0 or MTPA control mode, resulting in the minimum stable operating frequency of the single-rotor compressor being 10Hz. Then, the minimum operating frequency can be set to 10Hz or a frequency point slightly greater than 10Hz, and the preset low-frequency state is the state where the operating frequency of the compressor is lower than 10Hz. However, different compressors have different minimum stable operating frequencies controlled by Id=0 or MTPA, and the preset low-frequency state is correspondingly different.

[0037] In some embodiments, in order to make the amplitude of the direct-axis current not less than the target current amplitude within the target period, the direct-axis current can be set to a positive current value not less than the positive current threshold within the target period, wherein the amplitude of the positive current threshold is equal to the target current amplitude. It can be understood that as the temperature difference between the ambient temperature and the set temperature changes dynamically, the parameter value of the frequency conversion parameter will change dynamically accordingly, so the parameter value of the frequency conversion parameter will gradually increase after decreasing to less than the first parameter threshold for a period of time. When the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, the direct-axis current is set to a positive current value not less than the positive current threshold, and the Id=0 control mode or the MTPA control mode is no longer used to control the direct-axis current; when the parameter value of the frequency conversion parameter increases to greater than the third parameter threshold, switch back to the Id=0 control mode or the MTPA (Maximum Torque per Ampere) control mode to control the direct-axis current, so that the direct-axis current is 0 or a negative value close to 0 outside the target period, wherein the third parameter threshold is greater than or equal to the first parameter threshold.

[0038] In other embodiments, in order to make the amplitude of the direct-axis current not less than the target current amplitude within the target period, the direct-axis current may also be set to a negative current value not less than the negative current threshold within the target period, wherein the amplitude of the negative current threshold is equal to the target current amplitude. It is understandable that when the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, the direct-axis current is set to a negative current value not greater than the negative current threshold, and the Id=0 control mode or the MTPA control mode is no longer used to control the direct-axis current; when the parameter value of the frequency conversion parameter increases to greater than the third parameter threshold, the Id=0 control mode or the MTPA control mode is switched back to control the direct-axis current, so that the direct-axis current is 0 or a negative value close to 0 outside the target period, wherein the third parameter threshold is greater than or equal to the first parameter threshold.

[0039] If the variable frequency parameter is the target operating frequency of the compressor, the first parameter threshold is the first preset frequency, and the third parameter threshold is the third preset frequency greater than or equal to the first preset frequency. That is, when the target operating frequency of the compressor decreases to less than the first preset frequency, it indicates that the compressor enters the preset low-frequency state, and the direct-axis current is set to a positive current value not less than the positive current threshold, or the direct-axis current is set to a negative current value not greater than the negative current threshold; when the target operating frequency of the compressor increases to greater than the third preset frequency, it indicates that the compressor exits the preset low-frequency state and switches back to the Id=0 control mode or the MTPA control mode to control the direct-axis current, so that the direct-axis current is 0 or a negative value close to 0 outside the target period.

[0040] Among them, the first preset frequency and the third preset frequency are not less than the minimum stable operating frequency of the compressor. In order to improve the operating reliability of the compressor, the first preset frequency can be a frequency point close to the minimum stable operating frequency and greater than the minimum stable operating frequency. The minimum stable operating frequency is the minimum operating frequency that the compressor can run to by adopting Id=0 control or MTPA control. The compressor can be controlled to run the full frequency range under Id=0 control or MTPA control, and the minimum stable operating frequency of the compressor can be measured. For example: after measurement, it is found that the minimum stable operating frequency of the compressor is 10Kz, then the first preset frequency and the third preset frequency can be any two different frequency values ​​in the range of 10Hz to 20Hz.

[0041] If the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit, the first parameter threshold is the first preset duty cycle, and the third parameter threshold is the third preset duty cycle that is greater than or equal to the first preset duty cycle. That is to say, when the maximum effective duty cycle of the three-phase inverter circuit is reduced to the first preset duty cycle, the direct-axis current is set to a positive current value not less than the positive current threshold, or the direct-axis current is set to a negative current value not greater than the negative current threshold, and the Id=0 control method or the MTPA control method is no longer used to control the direct-axis current; when the maximum effective duty cycle of the three-phase inverter circuit increases to be greater than the third preset duty cycle, switch back to the Id=0 control method or the MTPA control method to control the direct-axis current, so that the direct-axis current is 0 or a negative value close to 0 outside the target time period. Among them, the first preset duty cycle and the third preset duty cycle can be based on the dead time T of the three-phase inverter circuit. d and the switching period Tsw are set, for example, the first preset duty cycle and the third preset duty cycle can be set to the dead zone duty cycle T d / 5 to 10 times of Tsw.

[0042] In some embodiments, in order to improve the direct-axis current stability of the compressor, hysteresis control can be performed. If the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, the direct-axis current is set to a positive current value not less than the positive current threshold, and the Id=0 control method or the MTPA control method is no longer used to control the direct-axis current. Different from various embodiments, when the parameter value of the frequency conversion parameter increases to greater than the second parameter threshold, the direct-axis current is set to a negative current value not greater than the negative current threshold, wherein the amplitude of the negative current threshold is the target current amplitude, and the second parameter threshold is greater than the first parameter threshold; when the parameter value of the frequency conversion parameter increases from less than the second parameter threshold to greater than the third parameter threshold, switch back to the Id=0 control method or the MTPA control method to control the direct-axis current, so that the direct-axis current is 0 or a negative value close to 0 outside the target time period, wherein the third parameter threshold is greater than the second parameter threshold.

[0043] That is to say, when the target operating frequency of the compressor drops below f0, set Id≥Ismin>0; when the target operating frequency of the compressor rises above f1, set Id≤-Ismin<0; when the target operating frequency of the compressor rises above f3, set Id = 0 or Id = MTPA. It can also be that when the maximum effective duty ratio of the three-phase inverter circuit decreases to Dmax<DutyLim0, set Id≥Ismin>0; when the maximum effective duty ratio of the three-phase inverter circuit increases to Dmax>DutyLim1, set Id≤-Ismin<0; when the maximum effective duty ratio of the three-phase inverter circuit increases to Dmax>DutyLim2, set Id = 0 or Id = MTPA. Among them, f0, f1, and f2 correspond to the first preset frequency, the second preset frequency, and the third preset frequency respectively, and f0<f1<f2; Id is the direct-axis current, Ismin is the positive current threshold, -Ismin is the negative current threshold, Dmax is the maximum effective duty ratio, and DutyLim0, DutyLim1, and DutyLim2 correspond to the first preset duty ratio, the second preset duty ratio, and the third preset duty ratio respectively, and DutyLim0<DutyLim1<DutyLim2.

[0044] The first, second, and third preset frequencies increase in sequence and are all not less than the minimum stable operating frequency of the compressor. For example, the first and second preset frequencies can be set to frequency points within the range of 10Hz to 15Hz, while the third preset frequency is greater than the upper limit frequency point of the range of 10Hz to 15Hz. For example: the first preset frequency is 10Hz, the second preset frequency is 13Hz, and the third preset frequency is 20Hz. The first, second, and third preset duty ratios increase in sequence and can all be set within 5 to 10 times of the dead-time duty ratio Td / Tsw:

[0045]

[0046] It can be understood that when the parameter value of the variable-frequency parameter decreases to be less than the first parameter threshold, setting the direct-axis current as a positive current value not less than the positive current threshold is to make the phase current amplitude of the compressor greater than the target current amplitude. Because the phase current amplitude satisfies the following relationship with the quadrature-axis current and the direct-axis current Among them, i sis the phase current amplitude, and Id and Iq correspond to the direct-axis current and the quadrature-axis current. When setting the direct-axis current to a positive current value greater than the positive current threshold, it can be set to a preset constant positive current value first. However, during the implementation process, after the direct-axis current is given a preset constant positive current value, the phase current amplitude of the compressor can be made greater than the target current amplitude Is≥Ismin with a high probability, but it is also possible that the phase current amplitude is greater than the target current amplitude. In order to improve the reliability of controlling the direct-axis current, after setting the direct-axis current to a preset constant positive current value, the current phase current amplitude of the compressor is determined based on the constant positive current value; if the current phase current amplitude is less than the target current amplitude, the target quadrature-axis current value and the target direct-axis current value are determined according to the target speed and target torque required by the current load of the compressor; the direct-axis current is set to the target direct-axis current value, and the quadrature-axis current is set to the target quadrature-axis current value to satisfy that the phase current amplitude is greater than the target current amplitude: Is≥Ismin.

[0047] In some implementations, the corresponding target quadrature-axis current value and target direct-axis current value can be obtained by looking up a table in offline calibration data according to the target speed and target torque, wherein the offline calibration data includes quadrature-axis and direct-axis currents corresponding to a variety of torques and speeds.

[0048] For a single-rotor compressor, during the variable frequency operation of the compressor, the fluctuation characterization information characterizing the current fluctuation state of the quadrature axis current of the compressor is obtained; the target current amplitude is determined based on the fluctuation characterization information, wherein the greater the fluctuation of the quadrature axis current represented by the fluctuation characterization information, the greater the target current amplitude. It should be noted that the fluctuation characterization information may be the fluctuation amplitude or peak-to-peak value of the quadrature axis current Iq. Among them, a one-to-one correspondence between the fluctuation interval and the current amplitude may be pre-calibrated. According to the fluctuation interval where the fluctuation characterization information of the quadrature axis current Iq is located, the target current amplitude is determined. For example, when the peak-to-peak value of the fluctuation of the quadrature axis current Iq is less than Iq1, the target current amplitude is 0.5A; when the peak-to-peak value of the fluctuation of the quadrature axis current Iq is not less than Iq1, and less than Iq2 (Iq2>Iq1), the target current amplitude is 1A; when the peak-to-peak value of the fluctuation of the quadrature axis current Iq is not less than Iq2, and less than Iq3 (Iq3>Iq2), the target current amplitude is 2A. That is to say, the target current amplitude used by the single-rotor compressor is not constant, but changes dynamically within a mechanical cycle.

[0049] In the specific implementation process, two sets of reference data can also be obtained by looking up the table according to the fluctuation amplitude or peak-to-peak value characterizing the current fluctuation size of the cross-axis current Iq, and linear interpolation calculation is performed according to the two sets of reference data and the fluctuation amplitude (or peak-to-peak value) characterizing the current fluctuation size of the cross-axis current Iq to obtain the target current amplitude. Each set of reference data is the corresponding relationship data of the fluctuation amplitude (or fluctuation peak-to-peak value) and the current amplitude.

[0050] For other types of compressors, the target current threshold value can be a preset constant value.

[0051] It should be understood that for a single-rotor compressor, the Iq current is adjusted according to the load torque. Since the load torque is in a fluctuating state, the target value of the Iq current shows a fluctuating state. Among them, 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 Id = 0 control or MTPA control (the value calculated by MTPA is usually a negative value close to 0) is adopted, the phase current amplitude will be close to 0 for a period of time (Is < Ismin), as Figure 3 shown. Figure 3 is the waveform diagram of the X-phase current and the X-phase modulation voltage with Id = 0 in the embodiment of the present invention. And the positive current dead zone and the negative current dead zone will cause different modulation voltage deviations. Therefore, it is necessary to compensate for the modulation voltage deviation generated by the dead zone according to the positive and negative polarities of the phase current. During the period when the phase current amplitude is close to 0, in the actual application scenario, due to device deviations and sampling forms (such as single-resistance sampling), it is difficult to accurately determine the direction of the phase current during low-frequency operation, which affects the accuracy of compensating for the modulation voltage deviation, and further affects the angle estimation of sensorless positioning. And according to one or more embodiments provided by the embodiment of the present invention, the zero-crossing point of the phase current of the compressor can be made clear during low-frequency operation, and there will no longer be a situation where the phase current amplitude is close to 0 for a period of time, as Figure 4 and Figure 5 shown. Figure 4 is the waveform diagram of the X-phase current and the X-phase modulation voltage with Id = 1A for a single-rotor compressor; Figure 5 is the waveform diagram of the X-phase current and the X-phase modulation voltage with Id = -1A in the embodiment of the present invention. Thus, it is possible to accurately compensate for the modulation voltage deviation during the low-frequency operation of the compressor, thereby improving the stability of the compressor during low-frequency operation.

[0052] Based on the same inventive concept, the embodiment of the present invention also provides a compressor low-frequency operation control device. Figure 6 is the structural schematic diagram of the compressor low-frequency operation control device in the embodiment of the present invention. As Figure 6 shown, the compressor low-frequency operation control device includes: a parameter acquisition unit 601, configured to acquire the frequency conversion parameters during the frequency conversion operation of the compressor, where the frequency conversion parameters are parameters that affect the operating frequency of the compressor; a current adjustment unit 602, configured to adjust the direct-axis current of the compressor according to the change in the parameter value of the frequency conversion parameters, so that the amplitude of the direct-axis current is not less than the target current amplitude within the target period, the target current amplitude is greater than zero, the target period is the period when the parameter value of the frequency conversion parameters is less than the first parameter threshold, and the fact that the parameter value of the frequency conversion parameters is less than the first parameter threshold indicates that the compressor is in a preset low-frequency state.

[0053] In some embodiments, the current regulation unit 602 includes a first regulation subunit, which is used to: within the target time period, set the direct-axis current to a positive current value not less than a positive current threshold or a negative current value not greater than a negative current threshold, the amplitude of the positive current threshold is equal to the target current amplitude, and the amplitude of the negative current threshold is equal to the target current amplitude.

[0054] In some embodiments, the current regulation unit 602 includes a second regulation subunit, which is used to: when the parameter value of the frequency conversion parameter decreases to less than the first parameter threshold, set the direct-axis current to a positive current value not less than a positive current threshold, and the amplitude of the positive current threshold is equal to the target current amplitude; when the parameter value of the frequency conversion parameter increases to greater than the second parameter threshold, set the direct-axis current to a negative current value not greater than a negative current threshold, and the amplitude of the negative current threshold is equal to the target current amplitude, and the second parameter threshold is greater than the first parameter threshold.

[0055] In some embodiments, the current regulation unit 602 also includes a third regulation subunit, which is used to set the direct-axis current to a predetermined constant positive current value; based on the constant positive current value, determine the current phase current amplitude of the compressor; if the current phase current amplitude is less than the target current amplitude, determine the target quadrature-axis current value and the target direct-axis current value according to the target speed and target torque required by the current load of the compressor; set the direct-axis current to the target direct-axis current value, and set the quadrature-axis current to the target quadrature-axis current value.

[0056] In some embodiments, the third regulating subunit is used to: obtain the corresponding target quadrature-axis current value and target direct-axis current value from a table in offline calibration data according to the target speed and the target torque, wherein the offline calibration data includes quadrature-axis and direct-axis currents corresponding to multiple torques and speeds.

[0057] In some embodiments, the frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit used to drive the compressor, and the first parameter threshold corresponds to a first preset duty cycle, or the frequency conversion parameter is the target operating frequency of the compressor, and the first parameter threshold corresponds to a first preset frequency.

[0058] In some embodiments, the parameter acquisition unit 601 is used to: during the variable frequency operation process of the compressor, obtain the switch duty cycle difference between each two-phase inverter circuits in the three-phase inverter circuit of the compressor; based on the switch duty cycle difference between each two-phase inverter circuits in the three-phase inverter circuit, determine the corresponding phase effective duty cycle of the three-phase inverter circuit; and obtain the maximum effective duty cycle from the three-phase effective duty cycles of the three-phase inverter circuit.

[0059] In some embodiments, it also includes an amplitude determination unit, which is used to: obtain fluctuation characterization information of the cross-axis current of the compressor during the variable frequency operation of the compressor; determine the target current amplitude based on the fluctuation characterization information, wherein the greater the fluctuation of the cross-axis current represented by the fluctuation characterization information, the greater the target current amplitude.

[0060] The above-mentioned compressor low-frequency operation control device can be used to implement the above-mentioned compressor low-frequency operation control method. Therefore, more implementation details of the compressor low-frequency operation control device can refer to the above-mentioned compressor low-frequency operation control method. For the sake of brevity of the specification, they will not be repeated here.

[0061] Based on the same inventive concept, the present invention also provides an air conditioning device, Figure 7 FIG. 2 shows a schematic diagram of the structure of an air conditioning device in an embodiment of the present invention. Figure 7 As shown, the air conditioning device also includes: a memory 704, a processor 702, and a computer program stored in the memory 704 and executable on the processor 702. When the processor 702 executes the program, the compressor low-frequency operation control method of any of the aforementioned embodiments is implemented.

[0062] Among them, Figure 7 In the embodiment of the present invention, a bus architecture (represented by bus 700) is shown, which may include any number of interconnected buses and bridges, and bus 700 links various circuits including one or more processors represented by processor 702 and memory represented by memory 704. Bus 700 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 705 provides an interface between bus 700 and receiver 701 and transmitter 703. Receiver 701 and transmitter 703 may be the same element, namely a transceiver, providing a unit for communicating with various other devices over a transmission medium. Processor 702 is responsible for managing bus 700 and general processing, while memory 704 may be used to store data used by processor 702 when performing operations.

[0063] Based on the same inventive concept, the present invention further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the compressor low-frequency operation control method described in any of the aforementioned embodiments is implemented.

[0064] 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.

[0065] 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: Acquiring a variable frequency parameter of the compressor during variable frequency operation, wherein the variable frequency parameter is a parameter that affects the operating frequency of the compressor; The direct-axis current of the compressor is adjusted according to the change of the parameter value of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within the target time period, and the target current amplitude is greater than zero. The target time period is a time period when the parameter value of the frequency conversion parameter is less than a first parameter threshold, and the parameter value of the frequency conversion parameter is less than the first parameter threshold, which indicates that the compressor is in a preset low-frequency state.

2. The method according to claim 1, characterized in that The step of adjusting the direct-axis current of the compressor according to the parameter value change of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within a target period of time includes: During the target time period, the direct-axis current is set to a positive current value not less than a positive current threshold or a negative current value not greater than a negative current threshold, the amplitude of the positive current threshold is equal to the target current amplitude, and the amplitude of the negative current threshold is equal to the target current amplitude.

3. The method according to claim 1, characterized in that The step of adjusting the direct-axis current of the compressor according to the parameter value change of the frequency conversion parameter so that the amplitude of the direct-axis current is not less than the target current amplitude within a target period of time includes: When the parameter value of the frequency conversion parameter decreases to be less than the first parameter threshold, setting the direct axis current to a positive current value not less than a positive current threshold, the amplitude of the positive current threshold being equal to the target current amplitude; When the parameter value of the frequency conversion parameter increases to be greater than the second parameter threshold, the direct-axis current is set to a negative current value not greater than the negative current threshold, the amplitude of the negative current threshold is equal to the target current amplitude, and the second parameter threshold is greater than the first parameter threshold.

4. The method according to claim 3, characterized in that The step of setting the direct-axis current to a positive current value that is not less than a positive current threshold value includes: Setting the direct-axis current to a predetermined constant positive current value; determining a current phase current amplitude of the compressor based on the constant positive current value; If the current phase current amplitude is less than the target current amplitude, determining a target quadrature-axis current value and a target direct-axis current value according to a target speed and a target torque required by a current load of the compressor; The direct-axis current is set to the target direct-axis current value, and the quadrature-axis current is set to the target quadrature-axis current value.

5. The method according to claim 4, characterized in that The step of determining the corresponding target quadrature-axis current value and target direct-axis current value according to the target speed and target torque required by the current load of the compressor includes: According to the target speed and the target torque, the corresponding target quadrature-axis current value and target direct-axis current value are obtained by looking up a table in the offline calibration data, wherein the offline calibration data includes the quadrature-axis and direct-axis currents corresponding to a plurality of torques and speeds.

6. The method according to any one of claims 1 to 5, characterized in that: The frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit used to drive the compressor, and the first parameter threshold corresponds to a first preset duty cycle, or The variable frequency parameter is the target operating frequency of the compressor, and the first parameter threshold corresponds to a first preset frequency.

7. The method according to any one of claims 1 to 5, characterized in that: The frequency conversion parameter is the maximum effective duty cycle of the three-phase inverter circuit used to drive the compressor. The step of obtaining the frequency conversion parameter of the compressor during the frequency conversion operation includes: During the variable frequency operation of the compressor, a switch duty ratio difference between every two phase inverter circuits in the three-phase inverter circuit of the compressor is obtained; Determining the effective duty cycle of the corresponding phase of the three-phase inverter circuit based on the switch duty cycle difference between every two-phase inverter circuit in the three-phase inverter circuit; The maximum effective duty cycle is obtained from the three-phase effective duty cycles of the three-phase inverter circuit.

8. The method according to claim 1, characterized in that Also includes: During the variable frequency operation of the compressor, obtaining fluctuation characterization information of the quadrature axis current of the compressor; The target current amplitude is determined based on the fluctuation characterization information, wherein the greater the fluctuation of the quadrature-axis current represented by the fluctuation characterization information, the greater the target current amplitude.

9. A compressor low frequency operation control device, characterized in that: include: A parameter acquisition unit, used to acquire a variable frequency parameter of the compressor during variable frequency operation, wherein the variable frequency parameter is a parameter that affects the operating frequency of the compressor; A current regulating unit is used to regulate the direct-axis current of the compressor according to the change of the parameter value of the frequency conversion parameter, so that the amplitude of the direct-axis current is not less than the target current amplitude within the target time period, and the target current amplitude is greater than zero. The target time period is the time period when the parameter value of the frequency conversion parameter is less than a first parameter threshold, and the parameter value of the frequency conversion parameter is less than the first parameter threshold, indicating that the compressor is in a preset low-frequency state.

10. 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 8 when executing the computer program.

11. 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 8 is implemented.

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