Motor control apparatus, air conditioner, control method for motor in refrigeration device, and refrigeration device

Abstract

The present application discloses a motor control apparatus, an air conditioner, a control method for a motor in a refrigeration device, and a refrigeration device. The motor control apparatus comprises: a position / rotation speed inference unit, configured to infer, on the basis of detected currents (iq, id) on a control shaft and voltage instruction values (Vd*, Vq*) input to an inverter, a rotor position and a rotor rotation speed of an alternating current motor driven by the inverter; and a current ripple suppression controller, configured to infer, on the basis of the detected currents (iq, id) on the control shaft and the mechanical angle of a rotor respectively, compensation currents (iqcmp, idcmp) for compensating the current instruction values (iq*, id*) on the control shaft, so as to reduce position observation errors caused by current control fluctuations.

Description

Motor control devices and control methods for motors in air conditioners and refrigeration equipment

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application No. 2024115256461, filed on October 29, 2024; and Chinese patent application No. 2025100255884, filed on January 7, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of motor control technology, and in particular to a motor control device, a method for controlling a motor in an air conditioner or refrigeration equipment, and refrigeration equipment. Background Technology

[0004] Related technologies include sensorless control that infers the rotor position of an AC motor from the current detection value of the inverter, and then controls the drive of the AC motor based on the inferred position. AC motors driven by sensorless control exhibit excellent environmental resistance, and are particularly useful when driving compressors.

[0005] The air conditioning systems of this technology mostly use sensorless FOC (Field-Oriented Control) technology to control the compressor for frequency adjustment and frequency conversion. Moreover, the compressors of this technology are mostly rotary compressors. When the rotary compressor operates at low frequency without a position sensor, it exhibits mechanical characteristic pulsation, which leads to fluctuations in current control. As a result, the rotor position estimation error is relatively large, especially when the load fluctuates (for example, at high temperature (e.g., 59 degrees Celsius) and high load, the pressure difference between the compressor discharge pressure and suction pressure is large, and there is a pressure difference between the suction and discharge pressure in the compressor cavity, resulting in load fluctuations). The load torque fluctuations combined with the mechanical characteristic pulsation can easily lead to a large increase in position observation error and cause the machine to stop out of sync.

[0006] Many air conditioner manufacturers need to add a system pressure relief valve to relieve the compressor's discharge pressure under extreme conditions such as high frequency and high load. For example, when the discharge pressure is greater than about 3.8 MPa, the system pressure relief valve is opened to release the discharge pressure; otherwise, the system pressure relief valve is closed to ensure stable operation of the compressor.

[0007] This method requires manual intervention and an additional system pressure relief valve, resulting in low automation. Summary of the Invention

[0008] Some embodiments of this application relate to a motor control device, including:

[0009] The position / speed inference unit infers the rotor position and rotor speed of the AC motor driven by the inverter based on the detected current (iq, id) on the control shaft and the voltage command value (Vd*, Vq*) input to the inverter.

[0010] The current ripple suppression controller is used to infer the compensation current (iqcmp, idcmp) for compensating the current command value (iq*, id*) on the control axis based on the detected current (iq, id) on the control axis and the mechanical angle of the rotor, so as to reduce the position observation error caused by current control fluctuations.

[0011] In some embodiments of this application, the position / rotation speed inference unit includes:

[0012] The shaft error inference unit infers the shaft error Δθ between the real shaft and the control shaft of the AC motor driven by the inverter based on the detected current (iq, id) on the control shaft and the voltage command value (Vd*, Vq*) input to the inverter.

[0013] A phase-locked loop (PLL) outputs the rotor position and rotor speed based on the shaft error output by the shaft error inference unit.

[0014] In some embodiments of this application, the current ripple suppression controller includes:

[0015] The first compensation unit is used to infer the compensation current idcmp for compensating the current command value id* on the control shaft based on the detected current id on the control shaft and the mechanical angle of the rotor.

[0016] The second compensation unit is used to infer the compensation current iqcmp for compensating the current command value iq* on the control shaft based on the detected current iq on the control shaft and the mechanical angle of the rotor.

[0017] In some embodiments of this application, the first compensation unit includes:

[0018] The first current processing unit is used to transform the detected current id on the control axis and the mechanical angle into a first current pulsation component represented by a sine wave through Fourier transform processing.

[0019] The first current conversion unit converts the nth harmonic component to be extracted from the first current pulsation component into a DC component under the synchronous rotating coordinate system of the nth harmonic dq.

[0020] The first branch and the second branch are connected in parallel to the rear end of the first current conversion unit. The first branch is used to control the DC component of the nth harmonic on the d-axis in the dq synchronous rotating coordinate system to be zero, and the second branch is used to control the DC component of the nth harmonic on the q-axis in the dq synchronous rotating coordinate system to be zero.

[0021] The second current processing unit is used to process the current signals output from the first branch and the second branch, and the mechanical angle respectively, through inverse Fourier transform to obtain the compensation current idcmp.

[0022] In some embodiments of this application, the second compensation unit includes:

[0023] The third current processing unit is used to transform the detected current iq on the control axis and the mechanical angle into a second current pulsation component represented by a sine wave through Fourier transform processing.

[0024] The second current conversion unit converts the nth harmonic component to a DC component based on the nth harmonic component to be extracted from the second current pulsation component, in the nth harmonic dq synchronous rotating coordinate system.

[0025] The third and fourth branches are connected in parallel to the rear end of the second current conversion unit. The third branch is used to control the DC component of the nth harmonic on the d-axis in the dq synchronous rotating coordinate system to be zero, and the fourth branch is used to control the DC component of the nth harmonic on the q-axis in the dq synchronous rotating coordinate system to be zero.

[0026] The fourth current processing unit is used to process the current signals output from the third branch and the fourth branch, and the mechanical angle respectively, through inverse Fourier transform, and inverse transform them into the compensation current iqcmp.

[0027] Where n is a natural number greater than 1.

[0028] In some embodiments of this application, the first branch, the second branch, the third branch, and the fourth branch have the same structure, and the first branch includes:

[0029] A filter, connected to the back end of the first current conversion unit, is used to filter out other pulsating components besides the d-axis DC component;

[0030] An integral controller that receives the negative value of the DC component of the d-axis;

[0031] A limiter is connected to the output of the integral controller, and the output of the limiter is input to the second current processing unit.

[0032] In some embodiments of this application, the first compensation unit further includes:

[0033] The first angle compensation unit is used to obtain the mechanical position error corresponding to the nth harmonic and to compensate for the mechanical angle.

[0034] The second current processing unit performs inverse Fourier transform on the current signals output from the first branch and the second branch, and the difference between the mechanical angle and the mechanical position error, respectively, to obtain the compensation current idcmp.

[0035] In some embodiments of this application, the second compensation unit further includes:

[0036] The second angle compensation unit is used to obtain the mechanical position error corresponding to the nth harmonic and to compensate for the mechanical angle.

[0037] The second current processing unit, based on the current signals output from the third and fourth branches and the difference between the mechanical angle and the mechanical position error, performs inverse Fourier transform processing to convert the current into the compensation current iqcmp.

[0038] Some embodiments of this application also relate to an air conditioner, comprising:

[0039] The refrigerant circulation loop allows the refrigerant to circulate within a loop consisting of the compressor, condenser, expansion valve, and evaporator.

[0040] A compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser.

[0041] An outdoor heat exchanger and an indoor heat exchanger, one of which functions as a condenser and the other as an evaporator;

[0042] An inverter for driving an AC motor, wherein the compressor uses the rotational force of the AC motor as a drive source;

[0043] Motor control device, comprising:

[0044] The position / speed inference unit infers the rotor position and rotor speed of the AC motor based on the detected current (iq, id) on the control shaft and the voltage command values ​​(Vd*, Vq*) input to the inverter.

[0045] The current ripple suppression controller is used to infer the compensation current (iqcmp, idcmp) for compensating the current command value (iq*, id*) on the control axis based on the detected current (iq, id) on the control axis and the mechanical angle of the rotor, so as to reduce the position observation error caused by current control fluctuations.

[0046] Some embodiments of this application provide a method for controlling a motor in a refrigeration device, the refrigeration device comprising:

[0047] A compressor that compresses refrigerant;

[0048] An electric motor for driving the compressor, the electric motor including a rotor; and

[0049] The controller is electrically connected to the motor;

[0050] The method includes:

[0051] The controller generates a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational frequency.

[0052] The controller corrects the motor's current value based on the compensation current to control the motor's operation.

[0053] According to some embodiments of this application, the target angle signal is obtained based on the sampled current signal; the target angle signal includes the angular frequency of the rotor or the mechanical angle of the rotor;

[0054] According to some embodiments of this application, generating the compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational frequency includes:

[0055] By combining the target angle signal and the target frequency harmonic, a Fourier transform is performed on the sampled current signal to obtain a first signal with frequencies from 1 to n; where n is greater than 1 and is a positive integer.

[0056] The first signal is low-pass filtered to obtain the first signal of the target frequency multiplication.

[0057] The first signal, which is the target frequency multiplier, is subjected to amplitude limiting based on the target amplitude to obtain the second signal;

[0058] The second signal is subjected to an inverse Fourier transform to obtain the compensation current.

[0059] According to some embodiments of this application, the step of combining the target angle signal and the target frequency harmonic to perform a Fourier transform on the sampled current signal to obtain a first signal with a frequency harmonic of 1 to n includes:

[0060] Based on the target angle signal, the target frequency, the phase of the first signal of any frequency from 1 to n, the amplitude of the first signal of the target frequency, the DC bias of any frequency and the current value of the motor, the sampled current signal is expanded by Fourier series to obtain the first signal of any frequency.

[0061] According to some embodiments of this application, the target frequency multiplication is determined based on the mechanical characteristics of the motor.

[0062] According to some embodiments of this application, the step of combining the target angle signal and the target frequency harmonic to perform a Fourier transform on the sampled current signal to obtain a first signal with a frequency harmonic of 1 to n includes:

[0063] By combining the target angle signal and the target frequency multiplication, Fourier transforms are performed on the d-axis signal and the q-axis signal in the sampled current signal to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis.

[0064] According to some embodiments of this application, the controller includes a current beat frequency suppression controller; the controller generates a compensation current based on a sampled current signal, a target angle signal of the rotor, and a target multiple of the motor's rotational speed frequency, including:

[0065] The sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency are input to the current beat frequency suppression controller, which then outputs the compensation current.

[0066] According to some embodiments of this application, the current beat frequency suppression controller includes: a Fourier transform module, a filter connected to the output terminal of the Fourier transform module, a PI controller connected to the output terminal of the filter, and an inverse Fourier transform module connected to the output terminal of the PI controller.

[0067] The step of inputting the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency to the current beat frequency suppression controller, and having the current beat frequency suppression controller output the compensation current, includes:

[0068] The sampled current signal, the target angle signal, and the target frequency multiple of the motor's rotational speed are input to the Fourier transform module, and the target amplitude is input to the PI controller to obtain the compensation current output by the inverse Fourier transform module.

[0069] According to some embodiments of this application, the filter includes two sub-filters, the PI controller includes two sub-PI controllers, the two sub-filters and the two sub-PI controllers are configured in a one-to-one correspondence, wherein the input terminals of the two sub-filters are respectively connected to the output terminal of the Fourier transform module, and the output terminals of the two sub-PI controllers are respectively connected to the input terminal of the inverse Fourier transform module.

[0070] According to some embodiments of this application, the controller further includes a first control module, a first output terminal of the first control module connected to a first input terminal of the current beat frequency suppression controller, a second output terminal of the current beat frequency suppression controller connected to a second input terminal of the first control module, a third output terminal of the first control module connected to the motor, a fourth input terminal of the first control module for inputting a sampled current signal, and a fifth input terminal of the first control module for inputting a reference signal.

[0071] Some embodiments of this application also provide a refrigeration device, the device comprising:

[0072] Equipment body; the equipment body includes:

[0073] A compressor that compresses refrigerant.

[0074] The motor electrically connected to the compressor;

[0075] A controller electrically connected to the motor, the controller controlling the operation of the motor based on the motor control method in the refrigeration equipment as described in the first aspect. Attached Figure Description

[0076] To more clearly illustrate the technical solutions in some embodiments or related technologies of this application, the accompanying drawings used in the description of some embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0077] Figure 1 is a block diagram of the principle of an air conditioner based on related technologies;

[0078] Figure 2 is a schematic block diagram of the application of a motor control device according to some embodiments of this application;

[0079] Figure 3 is a schematic diagram of the actual and estimated rotor positions of a motor when the motor control device proposed according to some embodiments of this application performs vector control;

[0080] Figure 4 is a detailed block diagram of related technologies for vector control of motors;

[0081] Figure 5 is an internal block diagram of the position / rotation inference unit in Figure 4;

[0082] Figure 6 is a detailed block diagram of a motor control device according to some embodiments of this application when performing vector control;

[0083] Figure 7 is an internal block diagram of the current ripple suppression controller in Figure 6;

[0084] Figure 8 is an internal block diagram of the first compensation unit in the current ripple suppression controller in Figure 6.

[0085] Figure 9 is a second internal block diagram of the first compensation unit in the current ripple suppression controller in Figure 6;

[0086] Figure 10 is an internal block diagram of the second compensation unit in the current ripple suppression controller in Figure 6.

[0087] Figure 11 shows the U-phase current waveform of the compressor before vector control of the motor is performed using the motor control device proposed in some embodiments of this application;

[0088] Figure 12 shows the U-phase current waveform of the compressor after the motor is vector controlled by the motor control device proposed in some embodiments of this application;

[0089] Figure 13 is a flowchart illustrating a motor control method in a refrigeration device provided in some embodiments of this application;

[0090] Figure 14 is a schematic diagram of the circuit structure of the motor control method in the refrigeration equipment provided in some embodiments of this application;

[0091] Figure 15 is a schematic diagram of the mechanical angle of the rotor of an electric motor provided in some embodiments of this application;

[0092] Figure 16 is a schematic diagram showing the results of a motor control method in a refrigeration device provided in some embodiments of this application;

[0093] Figure 17 is a schematic diagram showing the result of a motor control method in a refrigeration device provided in some embodiments of this application;

[0094] Figure 18 is a schematic diagram showing the results of a motor control method in a refrigeration device provided in some embodiments of this application;

[0095] Figure 19 is a flowchart illustrating a motor control method in a refrigeration device provided in some embodiments of this application;

[0096] Figure 20 is a flowchart illustrating a method for controlling a motor in a refrigeration device according to some embodiments of this application;

[0097] Figure 21 is a flowchart illustrating a motor control method in a refrigeration device provided in some embodiments of this application;

[0098] Figure 22 is a flowchart illustrating a motor control method in a refrigeration device provided in some embodiments of this application;

[0099] Figure 23 is a schematic diagram showing the results of a motor control method in a refrigeration device provided in some embodiments of this application;

[0100] Figure 24 is a schematic diagram showing the results of a motor control method in a refrigeration device provided in some embodiments of this application;

[0101] Figure 25 is a schematic diagram of the structure of the motor control device in the refrigeration equipment provided in some embodiments of this application;

[0102] Figure 26 is a schematic diagram of the structure of an electronic device provided in some embodiments of this application.

[0103] Reference numerals: 10, Motor control device; 101, Speed ​​control unit; 102, Current control unit; 103, Second coordinate transformer; 104, First coordinate transformer; 105, Position / speed inference unit; 105A, Shaft error inference unit; 105B, Phase-locked loop; 106, Current ripple suppression controller; 106A, First compensation unit; 106A1, First current processing unit; 106A2, First current conversion unit; 106A3, First branch; 106A4, Second branch; 106A5, Filter; 106A6, Integrator controller; 106A7, Limiter; 106A8, Second Current Processing Unit; 106A9, First Angle Compensation Unit; 106B, First Compensation Unit; 106B1, Third Current Processing Unit; 106B2, Second Current Conversion Unit; 106B3, Third Branch; 106B4, Fourth Branch; 106B5, Fourth Current Processing Unit; 20, Inverter; 30, Motor; 1a, Permanent Magnet; 1310, First Processing Module; 1320, Second Processing Module; 1400, Electronic Equipment; 1401, Processor; 1402, Memory. Detailed Implementation

[0104] The technical solutions of some embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on some embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0105] In the description of some embodiments of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing some embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0106] The terms "first" and "second" are used descriptively only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of some embodiments of this application, unless otherwise stated, "a plurality of" means two or more.

[0107] In the description of some embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to an indirect connection through an intermediate medium, or to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0108] In some embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature may include contact between the first and second features, or contact between the first and second features through other features between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0109] The following disclosure provides many different implementations or examples for different structures to implement some embodiments of this application. To simplify the disclosure of some embodiments of this application, components and arrangements of specific examples are described below. Of course, these are merely examples and are not intended to limit some embodiments of this application. Furthermore, some embodiments of this application may repeat reference numerals and / or reference letters in different examples; such repetition is for simplicity and clarity and does not in itself indicate a relationship between the various implementations and / or arrangements discussed. In addition, various specific processes and materials are provided in some examples of this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0110] In air conditioners using related technologies, the compressor employs sensorless position detection. During the position detection process, a vector control process of an AC motor is used. The output of the AC motor serves as the rotational force driving the compressor, which means that vector control is used to achieve position detection of the AC motor.

[0111] The basic working principle of an air conditioner will be described below.

[0112] Air conditioners execute a refrigeration cycle using a compressor, condenser, expansion valve, and evaporator. The refrigeration cycle involves a series of processes—compression, condensation, expansion, and evaporation—to cool or heat an indoor space. Low-temperature, low-pressure refrigerant enters the compressor, which compresses it into a high-temperature, high-pressure refrigerant gas and discharges the compressed gas. The discharged refrigerant gas flows into the condenser. The condenser condenses the compressed refrigerant into a liquid phase, releasing heat to the surrounding environment. The expansion valve expands the high-temperature, high-pressure liquid refrigerant formed in the condenser into a low-pressure liquid refrigerant. The evaporator evaporates the expanded refrigerant in the expansion valve, returning the low-temperature, low-pressure refrigerant gas to the compressor. The evaporator achieves its cooling effect by utilizing the latent heat of refrigerant evaporation to exchange heat with the material being cooled. Throughout the cycle, the air conditioner regulates the temperature of the indoor space.

[0113] Referring to Figure 1, the outdoor unit of an air conditioner refers to the part of the refrigeration cycle that includes the compressor and the outdoor heat exchanger. The indoor unit of an air conditioner includes the indoor heat exchanger, and an expansion valve can be provided in either the indoor or outdoor unit. The indoor and outdoor heat exchangers function as either condensers or evaporators. When the indoor heat exchanger functions as a condenser, the air conditioner acts as a heater in heating mode; when the indoor heat exchanger functions as an evaporator, the air conditioner acts as a cooler in cooling mode.

[0114] The following mainly describes the process of using the motor control device 10 to perform vector control on the motor 30.

[0115] Referring to Figure 2, a schematic block diagram of motor 30 controlled by motor control device 10 is shown. Motor 30 is a three-phase permanent magnet synchronous motor, having a permanent magnet assembly and a stator with three-phase armature coils. Inverter 20 provides motor 30 with a three-phase AC voltage consisting of U-phase, V-phase, and W-phase according to the rotor position of motor 30. Motor control device 10 provides PWM signals to inverter 20 circuitry to achieve the required vector control based on the detected motor current.

[0116] In some embodiments, by improving the modulation method of the PWM signal, the motor control device 10 can adjust the motor's response speed according to the air conditioner's operating requirements, ensuring the efficient operation of the air conditioning system. To cope with different working environments and load changes, the motor control device 10 can integrate adaptive control algorithms. These algorithms dynamically adjust the control strategy based on real-time data (such as current, temperature, and speed) to ensure the motor maintains a high-efficiency and stable operating state under different environments. For example, in cooling mode, the control device 10 can improve the compressor's responsiveness and efficiency by improving the parameters of vector control; while in heating mode, it can adjust the motor's power output in a timely manner to maintain the heating effect. The motor control device 10 can incorporate multiple protection mechanisms, such as overload protection, overheat protection, and abnormal current protection, to prevent motor damage or system failure. Furthermore, the motor control device can perform real-time fault diagnosis, monitor the motor's operating status, and promptly report abnormalities for easy maintenance and repair.

[0117] Figure 3 shows the analytical model diagram of motor 30. UVW represents the three-phase fixed coordinate axes. 1a is the permanent magnet installed on the rotor of motor 30. In a rotating coordinate system that rotates at the same speed as the rotational speed of the magnetic flux generated by permanent magnet 1a, the direction of the magnetic flux generated by permanent magnet 1a is taken as the d-axis, and the corresponding control rotation axis is taken as the dc-axis. The phase that leads the d-axis electrical angle by 90 degrees is taken as the q-axis, and the phase that leads the dc-axis electrical angle by 90 degrees is taken as the dq-axis. The rotating coordinate system corresponding to the real axes is a coordinate system that selects the d-axis and q-axis as coordinate axes, and this coordinate system is called the dq-axis. The control rotation coordinate system is a coordinate system that selects the dc-axis and dq-axis as coordinate axes, and this coordinate system is called the dcqc-axis.

[0118] In some embodiments of this application, referring to Figure 3, the dcqc axis represents the estimated position of the motor, indicating the axis on the control side of the rotational coordinate system in general torque control, denoted as the control axis; the dq axis represents the actual position of the motor, indicating the axis on the AC motor side of the rotational coordinate system, denoted as the real axis. The dq axis rotates, and its rotational speed is denoted by ωe. The dcqc axis also rotates, and its rotational speed is denoted by ω. In the dq axis, θe represents the d-axis angle (phase) observed from the fixed axis direction of the armature coil of phase U. Similarly, in the dcqc axis, θ represents the dc axis angle (phase) observed from the fixed axis direction of the armature coil of phase U. The angles represented by θ and θe are electrical angles, generally also referred to as rotor position or magnetic pole position. The rotational speeds represented by ω and ωe are the angular velocities of the electrical angles. The angular difference between the actual d-axis position (i.e., θe) and the estimated dc axis position (i.e., θ) is called the axis error Δθ. The motor control device 10 performs vector control to ensure that θ and θe are essentially consistent (i.e., the control axis error Δθ is zero), achieving the coincidence of the control axis and the real axis (i.e., the d-axis and q-axis are consistent with the dc-axis and qc-axis, respectively), thus realizing position-free observation of the permanent magnet synchronous motor rotor. The voltage command values ​​representing the target values ​​of the dc-axis voltage and qc-axis voltage are represented by the dc-axis voltage command value Vd* and the qc-axis voltage command value Vq*, respectively. The current command values ​​representing the target values ​​of the dc-axis voltage and qc-axis voltage are represented by the dc-axis current command value id* and the qc-axis current command value iq*, respectively. The U-phase, V-phase, and W-phase components of the motor voltage are represented by a three-phase voltage command value composed of the U-phase voltage command value Vu*, the V-phase voltage command value Vv*, and the W-phase voltage command value Vw*.

[0119] Referring to Figure 4, the principle of motor vector control is described. It adopts dual closed-loop control of speed and current, with the speed loop as the outer loop and the current loop as the inner loop.

[0120] First, the working principle of the current loop is explained. The U-phase current *iu* and V-phase current *iv* supplied to the motor by the inverter 20 are detected by a current detection unit (not shown). The W-phase current *iw* is calculated using the relationship "iw = -iu - iv". *iu*, *iv*, and *iw* are the currents of the U-phase, V-phase, and W-phase armature coils in the motor stator, respectively. The first coordinate transformer 104 can transform the coordinates of the U-phase current *iu* and V-phase current *iv* to the dc-qc axes based on the rotor position θ, to calculate and output the dc-axis current *id* and qc-axis current *iq*. In the vector control of the motor, the first coordinate transformer 104 can include Clark transformation and Park transformation; that is, the three-phase currents *iu* / *iv* / *iw* are transformed by Clark to obtain *iα* and *iβ*, and then *iα* and *iβ* are transformed by Park to obtain *iq* and *id*.

[0121] Then, iq and id are used to calculate the q-axis current error value and d-axis current error value with iq* and id*, respectively. The q-axis current error value and d-axis current error value are then fed into the current control unit 102 to obtain the dc-axis voltage command value Vd* and the qc-axis voltage command value Vq*. In some embodiments of this application, the current control unit 102 uses current feedback control such as proportional-integral control to make the current errors (id*-id) and (iq*-iq) converge to zero. The second coordinate transformer 103 can transform Vd* and Vq* onto the fixed coordinate axes of the three phases based on Vd* and Vq*, and the rotor position θ, to calculate and output the three-phase voltage command values ​​(Vu*, Vv*, and Vw*). In some embodiments of this application, the second coordinate transformer 103 may include the inverse Park transformation (i.e., the anti-Park transformation). That is, Vd* and Vq* are subjected to Park inverse transformation to obtain Vα* and Vβ*, and then SVPWM (Space Vector Pulse Width Modulation) is used to obtain PWM signal. The PWM signal controls the state of the switching transistors in inverter 20 and outputs three-phase voltage command values ​​(Vu*, Vv* and Vw*) to drive motor 30 to rotate.

[0122] In some embodiments of this application, to adapt to different environmental conditions and load changes, the motor control device 10 can combine adaptive control algorithms and machine learning techniques to adjust the parameters of vector control in real time. For example, by learning the operating mode of the air conditioning system (such as temperature and humidity changes) in real time, the control device can automatically improve torque output and current regulation strategies, further improving the system's response speed and energy efficiency. Through big data analysis of the operating status of the motor and air conditioner, the control system can predict load changes and make corresponding adjustments, thereby reducing energy waste and improving overall performance. The first coordinate transformer 104 and the second coordinate transformer 103 can be integrated into a more efficient processing unit, using hardware acceleration technologies such as digital signal processors (DSPs) or field-programmable gate arrays (FPGAs) to improve transformation efficiency and reduce system response time. The control device can also improve the overall control system performance by reducing the amount of computation during the transformation process through algorithm improvements. The various functional modules of the motor control device 10 (such as the current control unit, coordinate transformer, PWM modulation unit, etc.) can be integrated into a single microprocessor or multi-core processor, reducing system cost and complexity, and improving control accuracy and response speed.

[0123] Next, the working principle of the speed loop is explained. Referring again to Figure 4, the rotor speed ω output by the position / speed estimation unit 105 is subtracted from the target speed command value ω*, and then input to the speed control unit (e.g., a PI controller) 101 for speed adjustment to obtain iq*. As described above, the position / speed estimation unit 105 estimates the rotor position θ and speed ω by using all or part of Vd* and Vq* from the current control unit 102 and iq and id from the first coordinate transformer 104, performing proportional-integral control, etc., to control the shaft error Δθ to converge to zero. Various methods have been proposed as methods for estimating the rotor position θ and rotor speed ω. Here, the position / speed estimation unit 105 can adopt any method of related technology.

[0124] Referring to Figure 5, an example of an internal block diagram of a position / speed inference unit 105 is given. In some embodiments of this application, the position / speed inference unit 105 includes a shaft error inference unit 105A and a phase-locked loop 105B. The shaft error inference unit 105A calculates the shaft error Δθ based on Vd*, Vq*, iq, and id, for example using the following formula (1) shown in Japanese Patent No. 3411878.

[0125] The 105B phase-locked loop (PLL) enables PLL control, performing proportional-integral (PI) control to lock the shaft error Δθ to zero, obtaining the calculated motor speed ω. Integrating ω then allows for the calculation of the motor's rotor position θ. In air conditioners, the compressor exhibits mechanical pulsations during low-frequency operation, especially under high temperature and heavy load conditions. The large pressure difference between the compressor's discharge and suction pressures, coupled with the pressure difference within the compressor cavity, also generates load fluctuations. These load torque fluctuations, combined with the mechanical pulsations, can easily lead to increased position observation errors and ultimately, out-of-step shutdown.

[0126] Therefore, in some embodiments of this application, in addition to the parts described above, in order to avoid the current control pulsation caused by the above pulsation, which would lead to a larger observation position error, the motor control device 10 introduces a current pulsation suppression controller 106, referring to FIG6, to infer the compensation current idcmp for compensating the current command value id* and the compensation current iqcmp for compensating the current command value iq*, so as to eliminate the influence of pulsation on position observation.

[0127] In some embodiments of this application, referring to FIG6, after obtaining the compensation currents idcmp and iqcmp, they are injected in reverse to the current command values ​​id* and iq*, respectively, so that the DC-axis current error received by the current control unit 102 changes from id*-id to id*-id-idcmp, and the QC-axis current error received by the current control unit 102 changes from iq*-iq to iq*-iq-iqcmp, so as to eliminate the current pulsation component generated by torque pulsation in vector control, reduce the position observation error, and thereby improve the accuracy of motor position observation.

[0128] The following describes the process of calculating the compensation currents idcmp and iqcmp, in conjunction with Figures 6 and 12. The electromagnetic torque equation of the motor is: Te=1.5P*iq[Ψf+id*(Ld-Lq)]. Where, P is the number of pole pairs of the motor; Ψf is the flux linkage of the permanent magnet; Ld and Lq are the direct-axis inductance and quadrature-axis inductance, respectively; iq is the qc-axis current, and id is the dc-axis current. Therefore, for torque pulsation, the electromagnetic torque can be adjusted by adjusting the feedback value of the dcqc-axis current, thereby suppressing or balancing the fluctuation of the load torque. Combining the above formula (1), it can be seen that the shaft error Δθ is related to the dcqc-axis currents id and iq. Therefore, adjusting iq and id can adjust the influence of pulsation on position observation.

[0129] In some embodiments of this application, to improve the real-time performance and processing capability of the compensation current calculation, the current ripple suppression controller 106 can employ a digital signal processor (DSP) or a field-programmable gate array (FPGA). These hardware devices have high concurrency processing capabilities, enabling them to respond to current fluctuations in real time and perform efficient compensation calculations. In complex motor control systems, the current ripple suppression controller 106 can be designed as a multi-level control architecture, including both low-level current control and high-level torque and position control. This ensures that current ripples are comprehensively suppressed under multi-level control, while maintaining accurate motor torque and position. To ensure system stability, the current ripple suppression controller 106 can also integrate a fault diagnosis module to monitor current ripple patterns in the system and provide early warnings. By analyzing the current waveform, the controller can promptly detect potential fault sources and take preventative measures to prevent the long-term impact of current ripples on the motor or the entire control system.

[0130] In some embodiments of this application, based on the design concept of filtering out harmonics of the mechanical frequency, a compensation current corresponding to the nth harmonic component of the mechanical frequency is obtained. It should be noted that the nth harmonic component corresponding to the obtained compensation current should have the largest or relatively large amplitude to eliminate the influence on current control fluctuations. In some embodiments of this application, referring to Figure 7, the current ripple suppression controller 106 includes a first compensation unit 106A. The first compensation unit 106A is used to infer the compensation current idcmp for compensating the current command value id* on the control shaft based on the detected current id on the control shaft and the mechanical angle θr of the rotor. Wherein, the mechanical angle θr is equal to the product of the rotor position θ and the number of pole pairs.

[0131] Referring to Figures 8 and 9, the first compensation unit 106A includes a first current processing unit 106A1. This first current processing unit 106A1 is used to convert the time-domain signal into a frequency-domain signal through Fourier transform processing based on the detected current id on the control axis and the mechanical angle θr. The id is transformed into a first current pulsation component represented by a sine wave. The detected current id, as described above, can be the sampled value idfb obtained by sampling the current id output by the first coordinate transformer 104, or it can be the average value obtained from multiple samples. The detected current id is expanded using a Fourier series with respect to the angle θr, transforming id into a first current pulsation component represented by a sine wave, including a DC component, a fundamental wave, and an nth harmonic component, where n is a natural number greater than 1. Each harmonic component in the first current pulsation component is an AC component. To achieve current control of the nth harmonic dc-axis and dq-axis, a synchronous rotating coordinate system corresponding to the nth harmonic is established.

[0132] According to the principle of UVW / dq coordinate transformation, frequency components with the same rotation direction and speed as the dq axis rotation system are DC components in the dq synchronous rotating coordinate system. Therefore, through coordinate transformation, the nth harmonic component to be extracted in the nth harmonic dq synchronous rotating coordinate system is a DC component, while the fundamental wave and other harmonic components are AC components. For example, taking the 2nd harmonic component as an example, in the 2nd harmonic dq synchronous rotating coordinate system, the 2nd harmonic component is a DC component, while the fundamental wave and other harmonic components are AC components. Among them, the nth harmonic component that is a DC component includes the amplitude of the nth harmonic current in the d-axis and q-axis in the nth harmonic dq synchronous rotating coordinate system, that is, it branches into two DC components, which will be processed separately below.

[0133] The conversion process described above is performed by the first current conversion unit 106A2. For ease of description, the following explanation uses the extraction of the second harmonic as an example. After processing the first current pulsation component into the second harmonic DC component, the fundamental DC component, and other harmonic AC components as described above, in order to control the two DC components of the second harmonic (denoted as the d-axis DC component and the q-axis DC component) separately, a first branch 106A3 and a second branch 106A4 are designed to be connected in parallel to the rear end of the first current conversion unit 106A2. The structures of the first branch 106A3 and the second branch 106A4 are the same, both controlling the DC component to zero. That is, the first branch 106A3 is used to control the d-axis DC component to zero, and the second branch 106A4 is used to control the q-axis DC component to zero.

[0134] The following description, referring to Figure 8, uses the structure of the first branch 106A3 as an example. In some embodiments of this application, the first branch 106A3 includes a filter 106A5 connected to the rear end of the first current conversion unit 106A2, used to filter out harmonic components other than the d-axis DC component, and to extract the d-axis DC component. In some embodiments of this application, the first branch 106A3 also includes an integrator controller 106A6, which receives the negative value of the d-axis DC component and is used to control the d-axis DC component to zero, achieving elimination control. In some embodiments of this application, the first branch 106A3 also includes a limiter 106A7 connected to the output of the integrator controller 106A6 to prevent the integrator controller 106A6 from easily saturating. Referring to the description of the first branch 106A3, the second branch 106A4 is used to control the q-axis DC component to zero; the difference from the first branch 106A3 is that the filter in the second branch 106A4 is used to extract the q-axis DC component. The above describes the processing of the current signal in the frequency domain. If it is to be applied to the vector control of the motor, the signal needs to be converted from the frequency domain to the time domain, which requires the inverse Fourier transform.

[0135] In some embodiments of this application, referring to FIG8, the first compensation unit 106A further includes a second current processing unit 106A8. This second current processing unit 106A8 is used to process the current signals output from the first branch 106A3 and the second branch 106A4, and the mechanical angle θr, respectively, through an inverse Fourier transform to obtain a compensation current idcmp, i.e., the signal is converted from the frequency domain to the time domain. As described above, referring to FIG6, the compensation current idcmp is negatively fed back to the current control unit 102.

[0136] In some embodiments of this application, referring to FIG7, the current ripple suppression controller 106 further includes a second compensation unit 106B. Referring to FIG10, the second compensation unit 106B has the same structure as the first compensation unit 106A, the only difference being that the first compensation unit 106A compensates for the current id, while the second compensation unit 106B compensates for the current iq. The second compensation unit 106B includes a third current processing unit 106B1, the structure of which is the same as that of the first current processing unit 106A1 described above, and will not be described again here. The second compensation unit 106B includes a second current conversion unit 106B2, the structure of which is the same as that of the first current conversion unit 106A2 described above, and will not be described again here. The second compensation unit 106B includes a third branch 106B3 and a fourth branch 106B4, the structures of which are the same as those of the first branch 106A3 and the second branch 106A4 described above, and will not be described again here. The second compensation unit 106B includes a fourth current processing unit 106B5, the structure of which is described above as the second current processing unit 106A8, and will not be repeated here. In some embodiments of this application, it can be seen from the shaft error calculation formula (1) that the actual values ​​of iq and id will affect the estimated value of the rotor position error. Therefore, when performing the inverse Fourier transform, it is necessary to compensate for the angle used only for the inverse transform, in order to remove the mechanical frequency harmonic pulsation component contained in the rotor position information.

[0137] To achieve angle compensation, referring to Figure 9, the first compensation unit 106A further includes a first angle compensation unit 106A9. This first angle compensation unit 106A9 can obtain the mechanical position error Δθnω corresponding to the harmonic pulsation component of the mechanical frequency n (n is a natural number greater than 1) from the rotor position output by the position / speed inference unit 105, and use it to compensate for the mechanical angle θr. After obtaining the mechanical position error Δθnω, the second current processing unit 106A8 performs inverse Fourier transform processing on the current signals output by the first branch 106A3 and the second branch 106A4, and the difference θr-Δθω θdcmp, respectively, to obtain the compensation current idcmp. Similarly, the second compensation unit 106B also includes a second angle compensation unit (not shown). This second angle compensation unit can obtain the mechanical position error Δθnω corresponding to the harmonic pulsation component of the mechanical frequency n (n is a natural number greater than 1) from the rotor position output by the position / speed inference unit 105, and use it to compensate for the mechanical angle θr. After obtaining the mechanical position error Δθnω, the fourth current processing unit 106B5 processes the current signals output from the third branch 106B3 and the fourth branch 106B4, and the difference between θr-Δθω, through inverse Fourier transform, converting them into a compensation current iqcmp. Thus, by performing an inverse Fourier transform on the compensated angle and compensating for the current command values ​​id* and iq*, the position observation error caused by current fluctuations is effectively eliminated.

[0138] In some embodiments of this application, the first angle compensation unit 106A9 is equipped with a position error extraction module. This module extracts error components related to the mechanical frequency harmonics from the rotor position data output by the position / speed inference unit 105. By analyzing the high-frequency pulsation components of the rotor position, errors affecting position observation can be accurately identified. After extracting the mechanical position error, the first angle compensation unit 106A9 generates a compensation current idcmp through a compensation current generation module combined with inverse Fourier transform technology. The function of this module is to convert the error components into a current compensation signal, which is then injected into the current control loop. To ensure the accuracy and real-time performance of the compensation current, the first angle compensation unit 106A9 can be designed as a real-time feedback adjustment module. This module can continuously track the operating status of the motor and continuously adjust the compensation current based on real-time speed and position data to maintain the accuracy of the motor control system.

[0139] Referring to Figures 11 and 12, Figure 11 shows the compressor U-phase current waveform before vector control of the motor 30 using the motor control device 10 proposed in this application, and Figure 12 shows the compressor U-phase current waveform after vector control of the motor 30 using the motor control device 10 proposed in this application. A comparison of Figures 11 and 12 shows that the motor control device 10 involved in this application can reduce the pulsation of the compressor current under low-frequency, high-load conditions, improve the stability of current control, and thus improve the accuracy of position observation.

[0140] The preceding embodiments disclosed a motor control device and an air conditioner. This device, through the coordinated operation of a position / speed inference unit and a current ripple suppression controller, effectively suppresses position observation errors caused by current ripples, thereby improving the accuracy of motor position observation. Building upon this, the following embodiments further extend this technology by proposing a motor control method in refrigeration equipment, aiming to reduce beat frequency phenomena caused by current control fluctuations. By generating a compensating current and correcting the motor current value, these embodiments effectively reduce the noise and vibration of the compressor drive motor, thereby improving the motor's operational stability and the user comfort of the refrigeration equipment. The application of this method will significantly improve the user experience, bringing higher performance and lower operating noise to the refrigeration equipment.

[0141] In some embodiments of this application, the motor control method in the refrigeration device can be applied to a terminal, specifically executed by hardware or software within the terminal. This terminal includes, but is not limited to, portable communication devices such as mobile phones or tablets. It should also be understood that in some embodiments, the terminal may not be a portable communication device, but rather a desktop computer. The following embodiments describe terminals including a display and a touch-sensitive surface. However, it should be understood that the terminal may include one or more other physical user interface devices such as a physical keyboard, mouse, and joystick.

[0142] The present application provides a method for controlling a motor in a refrigeration device according to some embodiments. The subject executing the method can be a refrigeration device or a functional module or entity in the refrigeration device that can implement the method for controlling the motor in the refrigeration device. The refrigeration devices mentioned in some embodiments of the present application include, but are not limited to, wall-mounted air conditioners, floor-standing air conditioners, central air conditioners and evaporative coolers. The following describes the method for controlling a motor in a refrigeration device according to some embodiments of the present application, taking the refrigeration device as the subject of execution.

[0143] As shown in Figure 13, the motor control method in this refrigeration equipment includes steps 110 and 120. In some embodiments of this application, the motor control method in the motor control device shown in Figure 2 and the motor control method in the refrigeration equipment shown in Figure 13 both improve motor efficiency, save energy, and reduce noise. The refrigeration equipment includes a compressor that compresses refrigerant, a motor for driving the compressor, and a controller electrically connected to the motor. The motor includes a rotor. In some embodiments, the motor can be a permanent magnet synchronous motor. The motor is used to drive the compressor. During motor startup, there is a control block diagram as shown in Figure 14, which may include a PMSM motor, a Clark converter module, a Park converter module, a position observer, a PLL phase-locked loop, an outer loop speed loop PI controller, an inner loop current loop PI controller, an inverse Park converter module, a PWM inverter, a DC bus, a diode rectifier bridge, an AC power input module, and a field weakening control module.

[0144] In some embodiments of this application, the output terminal of the PMSM motor is connected to the input terminal of the Clark converter module, the output terminal of the Clark converter module is connected to the input terminal of the Park converter module, the output terminal of the Park converter module is connected to the first input terminal of the inner loop current loop PI controller, the output terminal of the inner loop current loop PI controller is connected to the input terminal of the inverse Park converter module, the output terminal of the inverse Park converter module is connected to the input terminal of the PWM inverter, and the output terminal of the PWM inverter is connected to the PMSM motor. Additionally, the output terminal of the position observer is connected to the input terminal of the PLL phase-locked loop, the output terminal of the PLL phase-locked loop is connected to the input terminal of the outer loop speed loop PI controller, and the output terminal of the outer loop speed loop PI controller is connected to the input terminal of the inner loop current loop PI controller. Furthermore, the output terminal of the AC power input module is connected to the input terminal of the diode rectifier bridge, and the output terminal of the diode rectifier bridge is connected to the input terminal of the PWM inverter via a DC bus.

[0145] During execution, during motor startup, the phase currents ia, ib, and ic of the PMSM motor can first be acquired using a current sensor or sampling resistor. Then, through the Clark transformation module, the coordinates of the phase currents ia, ib, and ic are transformed to iα and iβ of the stationary coordinate system αβ axis. Simultaneously, using a position observer, based on the sampled values ​​idfb and iqfb of the motor voltages Ud* and Uq* on the dq axis of the rotating coordinate system, and the motor currents id and iq on the dq axis of the rotating coordinate system, the rotor position angle Δθ is estimated (as shown in Figure 15). Then, using a PLL phase-locked loop, based on the estimated rotor position angle Δθ, the rotor position angle θ and rotor angular frequency ω are obtained. This can be based on iα, iβ, and... The rotor's position angle θ is transformed by the Park transformation module to obtain the dq-axis currents id and iq in the rotating coordinate system. The outer loop speed loop PI controller receives the angular frequency reference value ω* and performs closed-loop control of the motor speed, outputting the q-axis current reference value iq*. The inner loop current loop PI controller receives the d-axis current reference value id*, the dq-axis currents id and iq, and the q-axis current reference value iq* output by the outer loop speed loop PI controller, outputting the motor voltages Ud* and Uq* in the rotating coordinate system. Based on Ud*, Uq*, and the rotor's position angle θ, the inverse Park transformation module obtains Uα and Uβ. Uα and Uβ are then transformed by SVPWM (Space Vector Pulse Width Modulation) to obtain the duty cycle signal controlling the motor output. Here, Ud* is the d-axis voltage value of the motor in the rotating coordinate system, Uq* is the q-axis voltage value of the motor in the rotating coordinate system, and Uα and Uβ are the α-axis and β-axis voltage values ​​of the motor in the orthogonal stationary coordinate system, respectively.

[0146] In some embodiments, Ud* and Uq* can be obtained based on the motor equations in the rotating coordinate system as shown below:

[0147] Where Ud and Uq are the voltage values ​​of the motor on the d-axis and q-axis in the rotating coordinate system, respectively; r is the winding resistance of the motor; id and iq are the current values ​​of the motor on the d-axis and q-axis in the rotating coordinate system, respectively; Ke is the stator flux linkage of the permanent magnet synchronous motor; ω is the angular frequency of the motor; and Ld and Lq are the dq-axis inductances of the motor, respectively.

[0148] As shown in Figure 14, in some embodiments, the motor start-up control may further include a current beat frequency suppression controller module. The input terminal of the current beat frequency suppression controller module can be connected to the output terminal of the PLL phase-locked loop, and the output terminal of the current beat frequency suppression controller module is connected to the input terminal of the inner loop current PI controller. During execution, in the case of SVPWM conversion, it is necessary to collect the DC bus voltage. The AC ripple of the DC bus voltage contains the power supply frequency. Without correcting the motor current value based on the compensation current, there are large harmonic components related to the motor's mechanical speed in the motor's current spectrum. These harmonic components will beat with the power supply frequency contained in the DC bus voltage, causing motor current pulsation, which in turn leads to poor piping stress and high vibration and noise in the refrigeration equipment.

[0149] The following example, using single-phase power with a frequency of 50Hz and a harmonic component that is twice the frequency of the motor's mechanical speed, illustrates the beat frequency phenomenon: During operation, when the input power frequency is 50Hz, the DC bus voltage after passing through the bridge rectifier will contain a 100Hz power supply ripple. Due to mechanical characteristics, the motor's current spectrum contains a second harmonic component of the mechanical speed, and this component has significant energy. When the frequency of this second harmonic component approaches 100Hz, the two energies will interact and beat each other, resulting in an envelope-like pulsation in the motor current, as shown in Figure 16 (in Figure 16, the upper spectrum represents the motor current, and the lower spectrum represents the q-axis current). Assuming the mechanical speed is 47 rpm, the second harmonic of the current acting on the motor is 94Hz. When interacting with the 100Hz power supply, the beat frequency is approximately 100-94=6Hz, as shown in Figure 17.

[0150] In some embodiments, the current beat frequency suppression controller module identifies harmonic components of the power supply frequency and mechanical speed by analyzing the spectrum of the motor current in real time. When these components are close together, the current beat frequency suppression controller module can detect the beat frequency phenomenon and activate a suppression strategy. The current beat frequency suppression controller module generates a compensation signal based on the detected beat frequency and adjusts the motor current, thereby effectively suppressing current pulsation and reducing mechanical vibration and noise caused by the beat frequency phenomenon. The PLL phase-locked loop module works in conjunction with the current beat frequency suppression controller module to ensure the timeliness and accuracy of beat frequency suppression control by tracking the phase relationship between the power supply frequency and the motor mechanical speed.

[0151] As shown in Figure 18, in some embodiments, the spectrum analysis of the q-axis current can also be performed to find that when the motor is at 47 rpm, its second harmonic frequency of 94 Hz has an amplitude of 500, while the amplitude of the power supply frequency of 100 Hz energy is 260. The two energies affect each other, resulting in a beat frequency. Therefore, the amplitude of the second harmonic frequency of the mechanical speed can be reduced to reduce the energy of the beat frequency of the two.

[0152] In some embodiments, when a current beat frequency suppression controller module is included in the motor start-up control, the current beat frequency suppression controller module can process and output compensation currents iqcmp and idcmp to reduce the amplitude of harmonic components based on the sampled values ​​idfb and iq of the motor current in the dq axis of the rotating coordinate system, and the rotor position angle θ or rotor angular frequency ω output by the PLL phase-locked loop, in order to control and reduce beat frequency energy.

[0153] Step 110: The controller generates a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's speed frequency;

[0154] In this step, the sampled current signal is the sampled value of the motor current in a rotating coordinate system (dq coordinate system). In some embodiments, the sampled current signal can be obtained by the following formula:

[0155] Where Iqfb is the q-axis sampled current signal, Idfb is the d-axis sampled current signal, iα is the motor current value under the orthogonal stationary coordinate system α-axis, iβ is the motor current value under the orthogonal stationary coordinate system β-axis, and θ is the rotor position angle.

[0156] In some embodiments, the calculation process of the above formula for obtaining the sampled current signal can be performed by the Clark transform module. In some embodiments, iα and iβ can be obtained by the following formula:

[0157] Where ia is the a-phase current of the motor, ib is the b-phase current of the motor, and ic is the c-phase current of the motor.

[0158] In some embodiments, the calculation process for obtaining iα and iβ using the above formulas can be performed by the Park transformation module. The target angle signal can be obtained based on the sampled current signal. The target angle signal may include the rotor's angular frequency or the rotor's mechanical angle. The rotor's angular frequency is the angular velocity of the motor rotor. The rotor's mechanical angle is the actual rotation angle of the motor rotor, i.e., the rotor's position angle. In some embodiments, the relationship between the rotor's angular frequency and the rotor's mechanical angle can be expressed as: θ = ω·t

[0159] Where θ is the rotor's mechanical angle, ω is the rotor's angular frequency, and t is time. It can be understood that the rotor's mechanical angle is the product of the rotor's angular frequency and time. In some embodiments, the target angle signal can be obtained by processing the sampled current signal and the motor's voltage value along the dq axis of the rotating coordinate system, followed by processing by a position observer and a PLL (phase-locked loop). The position observer is a device used to estimate the position of the motor rotor; it can estimate the rotor's position using the input sampled current signal and the motor's voltage value along the dq axis of the rotating coordinate system. The PLL is an electronic circuit that can receive the estimated rotor position output by the position observer and process it to obtain more accurate rotor position information.

[0160] During execution, the current spectrum of the sampled current signal contains significant harmonic components related to the motor speed frequency. These harmonic components beat with the power supply frequency contained in the inverter's DC bus voltage, causing motor current pulsation, which in turn leads to poor piping stress and high vibration and noise in the refrigeration equipment. The frequency of this harmonic component is related to the motor speed frequency and is a multiple of it. During execution, the frequency of this harmonic component can be 1 to n times the motor speed frequency, meaning that the current spectrum of the sampled current signal can contain harmonic components of 1 to n harmonic frequencies. The target harmonic frequency is the multiple of the harmonic component that beats with the power supply frequency in the DC bus voltage. For example, if the harmonic component that beats with the power supply frequency in the DC bus voltage is a second harmonic component, the target harmonic frequency is the second harmonic frequency.

[0161] In some embodiments, the target harmonic frequency can be determined based on the mechanical characteristics of the motor. In some embodiments, during execution, the harmonic frequency can be determined as the target harmonic frequency based on the mechanical characteristics of the motor, such as whether there are harmonic components related to the motor's rotational speed frequency in the motor's rotational speed frequency spectrum.

[0162] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, by determining the target frequency based on the mechanical characteristics of the motor, the harmonic component that actually beats the power supply frequency in the DC bus voltage of the motor can be determined, thereby facilitating the subsequent processing of the harmonic component.

[0163] In some embodiments, through spectrum analysis, the system can detect multiple harmonics in the motor speed spectrum and determine which harmonic components (such as the second and third harmonics) resonate with the power supply frequency, thus generating beat frequency phenomena. Based on real-time feedback of the current signal and speed changes, the target harmonic can be adjusted in each control cycle. Especially during load fluctuations or operating mode switching, changes in motor speed affect the occurrence of harmonics, and the system can adjust the target harmonic value in a timely manner according to the changes, thereby improving the control strategy. After determining the target harmonic, the control system generates a compensation current corresponding to the harmonic component and suppresses low-frequency pulsations caused by beat frequency by adjusting the parameters in the current control loop. This compensation helps improve motor operation and increase system efficiency.

[0164] The compensation current is a sampled current signal obtained by reducing harmonic components, based on the sampled current signal, the target rotor angle signal, and the target multiple of the motor's speed frequency. In some embodiments, generating the compensation current based on the sampled current signal, the target rotor angle signal, and the target multiple of the motor's speed frequency may include:

[0165] By combining the target angle signal and the target frequency harmonic, a Fourier transform is performed on the sampled current signal to obtain the first signal with frequencies from 1 to n; n is greater than 1 and is a positive integer.

[0166] The first signal is low-pass filtered to obtain the first signal with the target frequency multiplier.

[0167] The second signal is obtained by limiting the first signal, which is a multiple of the target frequency, based on the target amplitude.

[0168] The second signal is subjected to an inverse Fourier transform to obtain the compensation current.

[0169] In some embodiments, the sampled current signal is first converted into a frequency domain signal using a Fourier transform to identify harmonic components from 1 to n harmonics. The target harmonic frequency is determined by the relationship between the rotor angle signal and the target harmonic frequency of the motor speed frequency, thus more accurately identifying the frequency components related to the power supply frequency. After the Fourier transform, low-pass filtering of the first signal helps remove high-frequency noise and clutter signals unrelated to the target harmonic frequency. The low-pass filter is designed to retain only the signal within the target harmonic frequency and its vicinity, suppressing other irrelevant spectral components. This ensures that the compensation current is adjusted for the target harmonic frequency related to the power supply frequency, thereby reducing unnecessary interference. In the amplitude limiting process, the target amplitude can be dynamically adjusted based on the motor's operating state and load conditions, ensuring that the current amplitude is always within a controllable range. By controlling the amplitude, the effectiveness of the compensation current can be improved, thereby improving the operation of the motor control system. Through real-time feedback control, the system can automatically adjust the compensation current according to changes in load and motor operating state, thereby improving the stability and efficiency of motor operation. Especially when the motor load fluctuates, the compensation current can be adjusted in a timely manner to eliminate current pulsations caused by beat frequency phenomena.

[0170] In some embodiments, Fourier Transform (FFT) is a mathematical method for converting a time-domain signal into a frequency-domain signal. It decomposes a signal into a combination of sine and cosine waves of different frequencies, thereby analyzing the signal's characteristics in the frequency domain. The harmonic components of the motor's rotational speed are 1 to n times the frequency of the target harmonic components. The first signal includes the DC quantity of the amplitude * phase of the 1st to nth harmonic components. During execution, by combining the target angle signal and the target harmonic, a Fourier transform is performed on the sampled current signal to obtain the DC quantity of the amplitude * phase of the 1st to nth harmonic components in the sampled current signal, with the target harmonic component as the fundamental frequency. Understandably, by combining the target angle signal and the target harmonic, performing a Fourier transform on the sampled current signal can decompose it into multiple harmonic components of different frequencies, with the target harmonic component as the fundamental frequency. The amplitude of each harmonic component is the same as that of the target harmonic component, but their phases differ. Each harmonic component is then converted into a DC quantity equal to its amplitude multiplied by its phase. During execution, the first signal can be low-pass filtered to remove harmonics other than the target harmonic, thus processing the harmonic components that cause beat frequency phenomena with the actual power supply frequency in the DC bus voltage.

[0171] As shown in Figures 19 and 20, a low-pass filter, such as an LPF filter, can be used to low-pass filter the first signal. The target amplitude is a pre-set desired amplitude for the target harmonic component. During execution, the first signal at the target harmonic can be amplitude-limited based on the target amplitude, i.e., a DC quantity equal to the amplitude * phase of the target harmonic, to obtain the amplitude-limited second signal.

[0172] As shown in Figures 19 and 20, a PI controller can be used for amplitude limiting. Specifically, the second signal can be obtained by PI control based on the difference between the target amplitude and the amplitude of the first signal. In some embodiments, when using a PI controller for amplitude limiting, the target amplitude can be set to 0, resulting in a second signal with an amplitude close to 0. During execution, with the target amplitude set to 0, the PI controller will control the amplitude of the second signal to a steady state close to 0, for example, ±2 amperes. As shown in Figures 19 and 20, in some embodiments, a limiter can be set after using the PI controller for amplitude limiting to prevent PI integral saturation. The inverse Fourier transform, the opposite of the Fourier transform, is a mathematical method for converting a frequency signal into a time-domain signal. As shown in Figures 19 and 20, during execution, after obtaining the second signal, an inverse Fourier transform can be performed on the second signal to obtain a sampled current signal with a reduced target harmonic component amplitude, i.e., a compensation current.

[0173] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, by combining the target angle signal and the target harmonic, the sampled current signal is subjected to Fourier transform to obtain a first signal of harmonic 1 to n. Then, the first signal is low-pass filtered to obtain a first signal of the target harmonic. Based on the target amplitude, the first signal of the target harmonic is subjected to amplitude limiting processing to obtain a second signal. Then, the second signal is subjected to inverse Fourier transform to obtain a compensation current. This can realize the acquisition of compensation current to reduce the amplitude of the target harmonic component, thereby facilitating the subsequent correction of the motor current value based on the compensation current.

[0174] Step 120: The controller corrects the motor current value based on the compensation current to control the motor operation.

[0175] In this step, the motor current value is corrected based on the compensation current. This correction is applied to the outdoor unit motor's current in the rotating coordinate system during startup. During execution, the corrected outdoor unit motor current value, after suppressing harmonic components, allows the dq-axis current id,iq of the rotating coordinate system to be input into the current loop for control. This reduces the beat frequency energy between harmonic components and the power supply frequency contained in the DC bus voltage, thereby reducing motor current ripple, improving motor operational stability, and decreasing motor vibration and noise.

[0176] As shown in Figures 23 and 24, after the controller corrects the motor current value based on the compensation current, the current waveform of the motor under the same operating conditions is shown in Figure 23. The spectrum analysis of the q-axis current of the motor can be obtained as shown in Figure 24. It can be concluded that, compared with Figures 17 and 18, the current of the motor has reduced the beat frequency envelope phenomenon, and the amplitude of the second harmonic component has decreased from 500 as shown in Figure 18 to 130.

[0177] In some embodiments of this application, the controller can obtain a compensation current that reduces the beat frequency phenomenon caused by the harmonic components of the power supply frequency in the DC bus voltage, based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency. The controller then corrects the motor current value based on the compensation current and inputs the corrected motor current value into the current loop for current loop control. This reduces the beat frequency energy between the harmonic components in the motor's current spectrum and the power supply frequency in the DC bus voltage, thereby reducing motor current pulsation, improving motor operation stability, reducing motor vibration and noise, and ultimately enhancing the comfort of using the refrigeration equipment, thus improving the user experience.

[0178] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, the controller controls the motor operation by sampling the current signal and the target angle signal of the rotor, and then correcting the motor current value based on the compensation current. This can reduce the harmonic components contained in the motor current spectrum and the beat frequency energy contained in the DC bus voltage, thereby reducing the noise and vibration of the compressor drive motor of the refrigeration equipment caused by the beat frequency phenomenon, improving the motor's operating stability, enhancing the comfort of using the refrigeration equipment, and thus improving the user experience.

[0179] In some embodiments, combining the target angle signal and the target frequency harmonic, performing a Fourier transform on the sampled current signal to obtain a first signal with a frequency harmonic of 1 to n may include:

[0180] By combining the target angle signal and the target frequency harmonic, Fourier transforms are performed on the d-axis and q-axis signals in the sampled current signal to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis.

[0181] In some embodiments, during actual execution, Fourier transforms can be performed on the d-axis and q-axis signals of the current signal respectively to obtain the first signal containing the target harmonic component as the fundamental frequency in the spectrum of the d-axis signal of the sampled current signal (1 to n times the fundamental frequency), and the first signal containing the target harmonic component as the fundamental frequency in the spectrum of the q-axis signal of the sampled current signal (1 to n times the fundamental frequency). This allows for subsequent processing such as limiting the target harmonic frequency on the first signal corresponding to the d-axis and the first signal corresponding to the q-axis, respectively, to obtain the d-axis and q-axis compensation currents that reduce the amplitude of the target harmonic component. This facilitates the correction of the d-axis and q-axis current values ​​of the motor based on the d-axis and q-axis compensation currents respectively.

[0182] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, by combining the target angle signal, Fourier transform is performed on the d-axis signal and q-axis signal in the sampled current signal to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis. This facilitates subsequent processing such as limiting the target harmonic frequency on the first signal corresponding to the d-axis and the first signal corresponding to the q-axis, thereby obtaining the d-axis and q-axis compensation currents that reduce the amplitude of the target harmonic frequency components. This makes it easier to correct the d-axis and q-axis current values ​​of the motor based on the d-axis and q-axis compensation currents respectively.

[0183] In some embodiments, frequency components related to the target harmonic frequency can be obtained by performing Fourier transforms on the d-axis and q-axis signals of the sampled current signal, respectively. Through this analysis, the system can identify and distinguish the target harmonic components and their multiples, thus providing information for subsequent compensation current generation. The Fourier-transformed signal will display harmonic components from 1 to n harmonics. These harmonic components can be used to further determine beat frequency phenomena related to the power supply frequency and prepare for subsequent compensation processing. The Fourier-transformed spectral signal can be used to improve the current waveform, eliminate unwanted high-frequency or low-frequency components, and ensure the motor operates under ideal current conditions. The identification and processing of the target harmonic components helps to further smooth the current waveform and reduce system noise and vibration.

[0184] In some embodiments, combining the target angle signal and the target frequency harmonic, performing a Fourier transform on the sampled current signal to obtain a first signal with a frequency harmonic of 1 to n may include:

[0185] Based on the target angle signal, the target frequency, the phase of any frequency from 1 to n, the amplitude of the first signal of the target frequency, the DC bias of any frequency and the motor current value, the sampled current signal is expanded by Fourier series to obtain the first signal of any frequency.

[0186] In some embodiments, the DC bias of the motor current value is the DC component adjustment of the motor current along the d-axis or q-axis in the rotating coordinate system during motor control, which can be based on a PI controller. During execution, the sampled current signal can be expanded using a Fourier series based on the target angle signal, the target harmonic, the phase of any harmonic from 1 to n, the amplitude of the first signal of the target harmonic, any harmonic, and the DC bias of the motor current along the d-axis or q-axis in the rotating coordinate system. This expands the sampled current signal into the sum of the harmonic components of 1 to n with the target harmonic as the fundamental frequency and the DC bias of the motor current along the d-axis or q-axis in the rotating coordinate system. It is understood that performing a Fourier series expansion on the sampled current signal converts the time-domain information of the sampled current signal into frequency-domain information, obtaining the amplitude and phase of any harmonic component with the target harmonic as the fundamental frequency contained in the spectrum of the sampled current signal.

[0187] During execution, by performing Fourier transforms on the d-axis and q-axis signals of the sampled current signal respectively to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis, any harmonic component with the target harmonic component as the fundamental frequency contained in the spectrum of the d-axis and q-axis signals of the sampled current signal can be obtained.

[0188] In some embodiments, the Fourier series expansion of the sampled current signal can be expressed as follows:

[0189] Where id is the d-axis current, iq is the q-axis current, Id,0 and Iq,0 are the DC biases of the d-axis and q-axis respectively, Idn and Iqn are the amplitudes of the nth harmonic components respectively, ω is the angular frequency of the motor, and t is time. It represents the phase of the nth harmonic.

[0190] Taking a target harmonic as a second harmonic as an example, the above formula can be expressed as:

[0191] Where Id2 and Iq2 are the amplitudes of the first signal at any harmonic of the d-axis and q-axis signals (the second harmonic is the fundamental frequency), respectively; id is the d-axis current; iq is the q-axis current; Id,0 and Iq,0 are the DC biases of the d-axis and q-axis with the second harmonic as the fundamental frequency, respectively; ω is the angular frequency of the motor; and t is time. It represents the phase of the nth harmonic.

[0192] As shown in Figure 21, in some embodiments, after combining the target angle signal and the target harmonic, performing a Fourier transform on the sampled current signal to obtain any harmonic component with the target harmonic component as the fundamental frequency in the spectrum of the d-axis signal and the q-axis signal of the sampled current signal, a simple coordinate transformation can be performed on each harmonic component to output the DC quantity of the amplitude * phase of each harmonic component on the dq axis of the rotating coordinate system, which facilitates subsequent low-pass filtering processing.

[0193] As shown in Figure 22, correspondingly, in some embodiments, in the above embodiments, when performing an inverse Fourier transform on the second signal, a simple coordinate transformation can be performed to convert the DC quantity of the amplitude * phase of the target harmonic component after amplitude limiting on the dq axis of the rotating coordinate system back into the target harmonic component, and then perform an inverse Fourier transform to convert the target harmonic component into a compensation current, that is, to convert the frequency domain signal into a time domain signal.

[0194] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, the sampled current signal is expanded by Fourier series based on the target angle signal, the target harmonic, the phase of any harmonic from 1 to n, the amplitude of the first signal of the target harmonic, any harmonic and the DC bias of the motor current value, to obtain the first signal of any harmonic. The time domain information of the sampled current signal can be converted into frequency domain information to obtain the harmonic components of each harmonic with the target harmonic as the fundamental wave contained in the spectrum of the sampled current signal, and the amplitude and phase of each harmonic component can be obtained, which facilitates the subsequent acquisition of the target harmonic and the subsequent amplitude limiting processing of the target harmonic.

[0195] In some embodiments, the controller includes a current beat frequency suppression controller; the controller generates a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's speed frequency, and may include:

[0196] The sampled current signal, the target rotor angle signal, and the target multiple of the motor's speed frequency are input to the current beat frequency suppression controller, which then outputs a compensation current.

[0197] In this embodiment, it is understood that when the controller includes a current beat frequency suppression controller, the specific steps of generating the compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency can be executed by the current beat frequency suppression controller. During execution, the current beat frequency suppression controller may have the control algorithm involved in the above embodiment built-in.

[0198] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, when the controller includes a current beat frequency suppression controller, the sampled current signal, the target angle signal of the rotor and the target multiple of the motor speed frequency are input to the current beat frequency suppression controller, and the current beat frequency suppression controller outputs a compensation current. The current beat frequency suppression controller, which is based on a control algorithm for acquiring the compensation current, can realize convenient acquisition of the compensation current and improve the acquisition efficiency of the compensation current.

[0199] In some embodiments, the current beat frequency suppression controller may include:

[0200] Fourier transform module;

[0201] A filter connected to the output of the Fourier transform module;

[0202] A PI controller connected to the output of the filter; and

[0203] The inverse Fourier transform module is connected to the output of the PI controller.

[0204] The sampled current signal, the target rotor angle signal, and the target multiple of the motor's speed frequency are input to the current beat frequency suppression controller, which then outputs a compensation current, including:

[0205] The sampled current signal, target angle signal, and target frequency multiple of the motor's speed frequency are input to the Fourier transform module, and the target amplitude is input to the PI controller to obtain the compensation current output by the inverse Fourier transform module.

[0206] In some embodiments, as shown in Figure 14, during execution, taking the target frequency as the second harmonic and obtaining the compensation current of the d-axis as an example, the three-phase currents ia, ib, and ic of the motor can first be obtained through resistors or current sensors. Then, through the Clark transformation module, the coordinates of the phase currents ia, ib, and ic are transformed to the iα and iβ axes of the stationary coordinate system αβ. From the αβ axis coordinate system, the Park transformation module obtains the Id current sampling value, i.e., the sampled current signal Idfb. Then, the mechanical speed ω, i.e., the target angle signal, is obtained from the position observer and the PLL phase-locked loop. This is used to obtain the 2ω-axis compensation current. The sampled value Idfb is subjected to Fourier series expansion, that is, the time-domain signal is transformed into a frequency-domain signal through the Fourier transform module. An LPF low-pass filter is set to obtain the DC quantity of the second harmonic component. The DC quantity is used as the control variable to design a PI controller to suppress the second harmonic component of the d-axis current based on the target amplitude. After passing through the set limiter, an inverse Fourier transform is performed to obtain the d-axis beat frequency suppression compensation amount, that is, the compensation current. Finally, it is injected into the d-axis control command, that is, as the reference value in the PI controller of the inner current loop, to realize the d-axis current beat frequency suppression and compensation.

[0207] In some embodiments, the Fourier transform module continuously monitors the current waveform during motor operation, converts the sampled current signal into a frequency domain signal, and extracts harmonic components from harmonics of 1 to n, especially the target harmonic, for use by subsequent control modules. A filter removes frequency components unrelated to the target harmonic, ensuring the filtered signal accurately reflects low-frequency components related to the target harmonic for further processing. Based on the acquired target harmonic signal, the PI (proportional-integral) controller adjusts according to the set target amplitude. The PI controller adjusts the proportional and integral gains to ensure the amplitude of the target harmonic component in the current is reduced to a predetermined value, thereby suppressing beat frequency phenomena. Based on the input target amplitude, the PI controller adjusts the current feedback signal to generate an effective compensation current. The inverse Fourier transform module converts the frequency domain compensation signal adjusted by the PI control into a time domain compensation current, adapting it to the needs of motor current control. This compensation current acts on the motor's control loop, correcting the d-axis and q-axis current values. After the compensation current is injected into the inner loop control, the system will adjust the motor current according to the feedback signal, so that the current waveform tends to be stable and avoids the negative impact of current pulsation on motor performance.

[0208] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, the current beat frequency suppression controller includes a Fourier transform module, a filter connected to the output terminal of the Fourier transform module, a PI controller connected to the output terminal of the filter, and an inverse Fourier transform module connected to the output terminal of the PI controller. By inputting the sampled current signal, the target angle signal, and the target multiple of the motor's rotational speed frequency to the Fourier transform module, and inputting the target amplitude to the PI controller, the compensation current output by the inverse Fourier transform module can be obtained. This can realize an effective acquisition process for obtaining the compensation current based on the current beat frequency suppression controller, and improve the reliability of the current beat frequency suppression controller.

[0209] In some embodiments, the filter may include two sub-filters, and the PI controller may include two sub-PI controllers. The two sub-filters and two sub-PI controllers are configured in a one-to-one correspondence. The input terminals of the two sub-filters are respectively connected to the output terminals of the Fourier transform module, and the output terminals of the two sub-PI controllers are respectively connected to the input terminals of the inverse Fourier transform module. In some embodiments, during actual execution, the two sub-filters and two sub-PI controllers configured in a one-to-one correspondence can be used to process the d-axis current and q-axis current of the motor, respectively, thereby achieving differentiated processing of the d-axis current and q-axis current.

[0210] According to the motor control method in the refrigeration equipment provided in some embodiments of this application, the filter may include two sub-filters, and the PI controller may include two sub-PI controllers. The two sub-filters and the two sub-PI controllers are set in a one-to-one correspondence, and the input terminal of each sub-filter is connected to the output terminal of the Fourier transform module, and the output terminal of each sub-PI controller is connected to the input terminal of the inverse Fourier transform module. This can realize the differentiation and processing of d-axis current and q-axis current, and improve the accuracy and reliability of the compensation current corresponding to the obtained d-axis current and q-axis current.

[0211] In some embodiments, the controller further includes a first control module. The first output terminal of the first control module is connected to the first input terminal of the current beat frequency suppression controller. The second output terminal of the current beat frequency suppression controller is connected to the second input terminal of the first control module. The third output terminal of the first control module is connected to the motor. The fourth input terminal of the first control module is used to input a sampled current signal, and the fifth input terminal of the first control module is used to input a reference signal. In some embodiments, the first control module is the control part other than the current beat frequency suppression controller, as shown in FIG14. Specifically, the first output terminal of the first control module is used to output a target angle signal, the first input terminal of the current beat frequency suppression controller is used to receive the target angle signal output by the first output terminal of the first control module, the second output terminal of the current beat frequency suppression controller is used to output compensation currents corresponding to the d-axis and q-axis, and the second input terminal of the first control module is used to receive compensation currents corresponding to the d-axis and q-axis. The third output terminal of the first control module is used to output the duty cycle signal for controlling the motor output; the fourth input terminal of the first control module is used to input a sampled current signal, which may include the d-axis current sample value and the q-axis current sample value; the fifth input terminal of the first control module is used to input a reference signal, which may include the current signal controlling the inner loop current loop PI controller and the angular frequency signal controlling the outer loop speed loop PI controller. In some embodiments, the first control module may further include a sixth input terminal, which is used to input a field weakening control signal to control the d-axis current in the compensation inner loop current loop PI controller.

[0212] According to some embodiments of this application, a motor control method in a refrigeration device is provided. The controller includes a first control module, wherein the first output terminal of the first control module is connected to the first input terminal of a current beat frequency suppression controller, the second output terminal of the current beat frequency suppression controller is connected to the second input terminal of the first control module, the third output terminal of the first control module is connected to the motor, the fourth input terminal of the first control module is used to input a sampled current signal, and the fifth input terminal of the first control module is used to input a reference signal. This method enables a complete start-up process for the motor with reduced beat frequency energy, reduces noise and vibration of the compressor drive motor in the refrigeration device caused by beat frequency phenomena, improves the motor's operational stability, and enhances the comfort of using the refrigeration device.

[0213] The motor control method in a refrigeration device provided in some embodiments of this application can be executed by a motor control device in the refrigeration device. In some embodiments of this application, the motor control method in a refrigeration device is executed by a motor control device in the refrigeration device as an example to illustrate the motor control device in the refrigeration device provided in some embodiments of this application.

[0214] Some embodiments of this application also provide a control device for a motor in a refrigeration device. As shown in FIG25, the control device for the motor in the refrigeration device includes:

[0215] The first processing module 1310 is used by the controller to generate a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target frequency multiple of the motor's rotational speed; the target angle signal is obtained based on the sampled current signal; the target angle signal includes the rotor's angular frequency or the rotor's mechanical angle;

[0216] The second processing module 1320 is used by the controller to correct the motor current value based on the compensation current in order to control the motor operation.

[0217] According to some embodiments of this application, the motor control device in the refrigeration equipment controls the motor operation by using a controller based on the sampled current signal and the target angle signal of the rotor, and then using the controller based on the compensation current to correct the motor current value. This can reduce the harmonic components contained in the motor current spectrum and the beat frequency energy contained in the DC bus voltage, thereby reducing the noise and vibration of the compressor drive motor of the refrigeration equipment caused by the beat frequency phenomenon, improving the operating stability of the motor, enhancing the comfort of using the refrigeration equipment, and thus improving the user experience.

[0218] In some embodiments, the first processing module 1310 may also be used for:

[0219] By combining the target angle signal and the target frequency harmonic, a Fourier transform is performed on the sampled current signal to obtain the first signal with frequencies from 1 to n; n is greater than 1 and is a positive integer.

[0220] The first signal is low-pass filtered to obtain the first signal with the target frequency multiplier.

[0221] The second signal is obtained by limiting the first signal, which is a multiple of the target frequency, based on the target amplitude.

[0222] The second signal is subjected to an inverse Fourier transform to obtain the compensation current.

[0223] In some embodiments, the first processing module 1310 may also be used for:

[0224] Based on the target angle signal, the target frequency, the phase of the first signal of the target frequency of any frequency from 1 to n, the amplitude of the first signal of the target frequency, any frequency from 1 to n, and the DC bias of the motor current value, the sampled current signal is expanded by Fourier series to obtain the first signal of any frequency.

[0225] In some embodiments, the first processing module 1310 may also be used for:

[0226] By combining the target angle signal and the target frequency harmonic, Fourier transforms are performed on the d-axis and q-axis signals in the sampled current signal to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis.

[0227] In some embodiments, the first processing module 1310 can also perform a Fourier series expansion on the sampled current signal based on the target angle signal, the target harmonic, the phase and amplitude of the 1 to n harmonic signals, and the DC bias of the motor current value. This process can more accurately extract the harmonic components in the current signal and ensure that the amplitude and phase of the compensation current are consistent with the target harmonic of the motor speed frequency. In some embodiments, the first processing module 1310 is used to remove unwanted high-frequency components and retain only the signal related to the target harmonic. The low-pass filter ensures that the frequency domain signal contains only the effective signal within the target harmonic range by setting an appropriate cutoff frequency.

[0228] In some embodiments, the device may further include a third processing module for:

[0229] The controller includes a current beat frequency suppression controller; the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor speed frequency are input to the current beat frequency suppression controller, which then outputs a compensation current.

[0230] In some embodiments, the device may further include a fourth processing module for:

[0231] The current beat frequency suppression controller includes: a Fourier transform module, a filter connected to the output of the Fourier transform module, a PI controller connected to the output of the filter, and an inverse Fourier transform module connected to the output of the PI controller; the sampled current signal, the target angle signal, and the target multiple of the motor's speed frequency are input to the Fourier transform module, the target amplitude is input to the PI controller, and the compensation current output by the inverse Fourier transform module is obtained.

[0232] In some embodiments of this application, the motor control device in the refrigeration equipment can be an electronic device or a component within an electronic device, such as an integrated circuit or a chip. The electronic device can be a terminal or other devices besides a terminal. Some embodiments of this application do not impose specific limitations. The motor control device in some embodiments of this application can be a device with an operating system. This operating system can be Android, iOS, or other possible operating systems; some embodiments of this application do not impose specific limitations. The motor control device in the refrigeration equipment provided in some embodiments of this application can implement the various processes implemented in the method embodiment of FIG13; to avoid repetition, these will not be described again here.

[0233] Some embodiments of this application also provide a refrigeration device.

[0234] In this embodiment, the refrigeration device includes:

[0235] The main body of the equipment may include: a compressor that compresses refrigerant, and a motor for driving the compressor;

[0236] The controller is electrically connected to the motor and controls the operation of the motor based on the motor control method in the refrigeration equipment described in any of the above embodiments.

[0237] According to some embodiments of the refrigeration equipment provided in this application, the controller controls the motor operation by sampling the current signal and the target angle signal of the rotor, and then correcting the motor current value based on the compensation current. This reduces the harmonic components in the motor current spectrum and the beat frequency energy of the power supply frequency in the DC bus voltage, thereby reducing the noise and vibration of the compressor drive motor of the refrigeration equipment caused by the beat frequency phenomenon, improving the operating stability of the motor, enhancing the comfort of using the refrigeration equipment, and thus improving the user experience.

[0238] In some embodiments, as shown in FIG26, some embodiments of this application also provide an electronic device 1400, including:

[0239] Processor 1401; and

[0240] Memory 1402;

[0241] The computer program is stored in the memory 1402 and can run on the processor 1401. When the computer program is executed by the processor 1401, it implements the various processes of the above-described embodiment of the motor control method in the refrigeration equipment and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0242] It should be noted that the electronic devices in some embodiments of this application include the mobile electronic devices and non-mobile electronic devices described above.

[0243] Some embodiments of this application also provide a non-transitory computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the above-described embodiments of the motor control method in the refrigeration device and achieves the same technical effect. To avoid repetition, it will not be described again here.

[0244] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0245] Some embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the motor control method in the above-described refrigeration equipment.

[0246] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0247] Some embodiments of this application also provide a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the above-described embodiments of the motor control method in the refrigeration equipment, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0248] It should be understood that the chips mentioned in some embodiments of this application may also be referred to as system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0249] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0250] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0251] Some embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0252] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in some embodiments or examples of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in some embodiments or examples.

[0253] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A motor control device, comprising: The position / speed inference unit infers the rotor position and rotor speed of the AC motor driven by the inverter based on the detected current (iq, id) on the control shaft and the voltage command value (Vd*, Vq*) input to the inverter. The current ripple suppression controller is used to infer the compensation current (iqcmp, idcmp) for compensating the current command value (iq*, id*) on the control axis based on the detected current (iq, id) on the control axis and the mechanical angle of the rotor, so as to reduce the position observation error caused by current control fluctuations.

2. The motor control device according to claim 1, wherein, The position / rotation speed inference unit includes: The shaft error inference unit infers the shaft error Δθ between the real shaft and the control shaft of the AC motor driven by the inverter based on the detected current (iq, id) on the control shaft and the voltage command value (Vd*, Vq*) input to the inverter. A phase-locked loop (PLL) outputs the rotor position and rotor speed based on the shaft error output by the shaft error inference unit.

3. The motor control device according to claim 2, wherein, The current ripple suppression controller includes: The first compensation unit is used to infer the compensation current idcmp for compensating the current command value id* on the control shaft based on the detected current id on the control shaft and the mechanical angle of the rotor. The second compensation unit is used to infer the compensation current iqcmp for compensating the current command value iq* on the control shaft based on the detected current iq on the control shaft and the mechanical angle of the rotor.

4. The motor control device according to claim 3, wherein, The first compensation unit includes: The first current processing unit is used to transform the detected current id on the control axis and the mechanical angle into a first current pulsation component represented by a sine wave through Fourier transform processing. The first current conversion unit converts the nth harmonic component to be extracted from the first current pulsation component into a DC component under the synchronous rotating coordinate system of the nth harmonic dq. The first branch and the second branch are connected in parallel to the rear end of the first current conversion unit. The first branch is used to control the DC component of the nth harmonic on the d-axis in the dq synchronous rotating coordinate system to be zero, and the second branch is used to control the DC component of the nth harmonic on the q-axis in the dq synchronous rotating coordinate system to be zero. The second current processing unit is used to process the current signals output from the first branch and the second branch, and the mechanical angle respectively, through inverse Fourier transform to obtain the compensation current idcmp. The second compensation unit includes: The third current processing unit is used to transform the detected current iq on the control axis and the mechanical angle into a second current pulsation component represented by a sine wave through Fourier transform processing. The second current conversion unit converts the nth harmonic component to a DC component based on the nth harmonic component to be extracted from the second current pulsation component, in the nth harmonic dq synchronous rotating coordinate system. The third and fourth branches are connected in parallel to the rear end of the second current conversion unit. The third branch is used to control the DC component of the nth harmonic on the d-axis in the dq synchronous rotating coordinate system to be zero, and the fourth branch is used to control the DC component of the nth harmonic on the q-axis in the dq synchronous rotating coordinate system to be zero. The fourth current processing unit is used to process the current signals output from the third branch and the fourth branch, and the mechanical angle respectively, through inverse Fourier transform, and inverse transform them into the compensation current iqcmp. Where n is a natural number greater than 1.

5. The motor control device according to claim 4, wherein, The first branch, the second branch, the third branch, and the fourth branch have the same structure, and the first branch includes: A filter, connected to the back end of the first current conversion unit, is used to filter out other pulsating components besides the d-axis DC component; An integral controller that receives the negative value of the DC component of the d-axis; A limiter is connected to the output of the integral controller, and the output of the limiter is input to the second current processing unit.

6. The motor control device according to claim 5, wherein, The first compensation unit further includes: The first angle compensation unit is used to obtain the mechanical position error corresponding to the nth harmonic and to compensate for the mechanical angle. The second current processing unit performs inverse Fourier transform on the current signals output from the first branch and the second branch, and the difference between the mechanical angle and the mechanical position error, respectively, to obtain the compensation current idcmp.

7. The motor control device according to claim 4 or 6, wherein, The second compensation unit also includes: The second angle compensation unit is used to obtain the mechanical position error corresponding to the nth harmonic and to compensate for the mechanical angle. The second current processing unit, based on the current signals output from the third and fourth branches and the difference between the mechanical angle and the mechanical position error, performs inverse Fourier transform processing to convert the current into the compensation current iqcmp.

8. An air conditioner, comprising: The refrigerant circulation loop allows the refrigerant to circulate within a loop consisting of the compressor, condenser, expansion valve, and evaporator. A compressor is used to compress low-temperature, low-pressure refrigerant gas into high-temperature, high-pressure refrigerant gas and discharge it to the condenser. An outdoor heat exchanger and an indoor heat exchanger, one of which functions as a condenser and the other as an evaporator; An inverter for driving an AC motor, wherein the compressor uses the rotational force of the AC motor as a drive source; Motor control device, comprising: The position / speed inference unit infers the rotor position and rotor speed of the AC motor based on the detected current (iq, id) on the control shaft and the voltage command values ​​(Vd*, Vq*) input to the inverter. The current ripple suppression controller is used to infer the compensation current (iqcmp, idcmp) for compensating the current command value (iq*, id*) on the control axis based on the detected current (iq, id) on the control axis and the mechanical angle of the rotor, so as to reduce the position observation error caused by current control fluctuations.

9. A method for controlling a motor in a refrigeration device, wherein, The refrigeration equipment includes: A compressor that compresses refrigerant; An electric motor for driving the compressor, the electric motor including a rotor; and The controller is electrically connected to the motor; The method includes: The controller generates a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational frequency. The controller corrects the motor's current value based on the compensation current to control the motor's operation.

10. The method for controlling the motor in the refrigeration equipment according to claim 9, wherein, The target angle signal is obtained based on the sampled current signal; the target angle signal includes the angular frequency of the rotor or the mechanical angle of the rotor.

11. The method for controlling a motor in a refrigeration device according to claim 9 or 10, wherein, The generation of compensation current based on the sampled current signal, the target angle signal of the rotor, and the target frequency multiple of the motor's rotational speed includes: By combining the target angle signal and the target frequency harmonic, a Fourier transform is performed on the sampled current signal to obtain a first signal with frequencies from 1 to n; where n is greater than 1 and is a positive integer. The first signal is low-pass filtered to obtain the first signal of the target frequency multiplication. The first signal, which is the target frequency multiplier, is subjected to amplitude limiting based on the target amplitude to obtain the second signal; The second signal is subjected to an inverse Fourier transform to obtain the compensation current.

12. The method for controlling a motor in a refrigeration device according to claim 11, wherein, The step of combining the target angle signal and the target frequency harmonic to perform a Fourier transform on the sampled current signal to obtain a first signal with frequencies from 1 to n harmonics includes: Based on the target angle signal, the target frequency, the phase of the first signal of any frequency from 1 to n, the amplitude of the first signal of the target frequency, the DC bias of any frequency and the current value of the motor, the sampled current signal is expanded by Fourier series to obtain the first signal of any frequency.

13. The method for controlling the motor in the refrigeration equipment according to claim 11, wherein, The target frequency multiplication factor is determined based on the mechanical characteristics of the motor.

14. The method for controlling the motor in the refrigeration equipment according to claim 11, wherein, The step of combining the target angle signal and the target frequency harmonic to perform a Fourier transform on the sampled current signal to obtain a first signal with frequencies from 1 to n harmonics includes: By combining the target angle signal and the target frequency multiplication, Fourier transforms are performed on the d-axis signal and the q-axis signal in the sampled current signal to obtain the first signal corresponding to the d-axis and the first signal corresponding to the q-axis.

15. The method for controlling a motor in a refrigeration device according to any one of claims 9-14, wherein, The controller includes a current beat frequency suppression controller; The controller generates a compensation current based on the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational frequency, including: The sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency are input to the current beat frequency suppression controller, which then outputs the compensation current.

16. The method for controlling a motor in a refrigeration device according to claim 15, wherein, The current beat frequency suppression controller includes: a Fourier transform module, a filter connected to the output of the Fourier transform module, a PI controller connected to the output of the filter, and an inverse Fourier transform module connected to the output of the PI controller. The step of inputting the sampled current signal, the target angle signal of the rotor, and the target multiple of the motor's rotational speed frequency to the current beat frequency suppression controller, and having the current beat frequency suppression controller output the compensation current, includes: The sampled current signal, the target angle signal, and the target frequency multiple of the motor's rotational speed are input to the Fourier transform module, and the target amplitude is input to the PI controller to obtain the compensation current output by the inverse Fourier transform module.

17. The method for controlling a motor in a refrigeration device according to claim 16, wherein, The filter includes two sub-filters, and the PI controller includes two sub-PI controllers. The two sub-filters and the two sub-PI controllers are configured in a one-to-one correspondence. The input terminals of the two sub-filters are respectively connected to the output terminals of the Fourier transform module, and the output terminals of the two sub-PI controllers are respectively connected to the input terminals of the inverse Fourier transform module.

18. The method for controlling a motor in a refrigeration device according to claim 15, wherein, The controller further includes a first control module, the first output terminal of the first control module is connected to the first input terminal of the current beat frequency suppression controller, the second output terminal of the current beat frequency suppression controller is connected to the second input terminal of the first control module, the third output terminal of the first control module is connected to the motor, the fourth input terminal of the first control module is used to input a sampled current signal, and the fifth input terminal of the first control module is used to input a reference signal.

19. A refrigeration device, comprising: Equipment body; The main body of the device includes: A compressor that compresses refrigerant; The motor used to drive the compressor; A controller electrically connected to the motor, the controller controlling the operation of the motor based on the motor control method in the refrigeration equipment as described in any one of claims 1-18.

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