Motor control method, device and air conditioner

Abstract

The application discloses a motor control method and device and an air conditioner, relates to the field of variable frequency air conditioners, and the motor control method is applied to a motor control device, the motor control device comprises a permanent magnet synchronous motor, a first coordinate transformation module, a rotating speed control module, a current control module, a compensation module and a second coordinate transformation module; the motor control method modulates a d-axis current sampling value through the current control module, modulates a q-axis current sampling value through the rotating speed control module, the current control module and the compensation module, obtains a d-axis voltage instruction value and a compensated q-axis voltage instruction value, and controls the permanent magnet synchronous motor through the second coordinate transformation module; in the case that the amplitudes of two signals are both at a high level, the frequencies of the two signals are similar, and a significant beat frequency phenomenon is caused, the compensation module is used for compensating the q-axis voltage instruction value, the amplitude of a signal corresponding to the q-axis is reduced, and the beat frequency phenomenon is inhibited.

Description

Technical Field

[0001] This application relates to the field of variable frequency air conditioners, and more particularly to a motor control method, device, and air conditioner. Background Technology

[0002] In the field of variable frequency air conditioning control, permanent magnet synchronous motors are widely used to drive compressors due to their advantages such as high efficiency, energy saving, and good speed regulation performance. They can precisely control the compressor speed, allowing the air conditioner to flexibly adjust its cooling or heating power according to the indoor temperature, achieving both high efficiency and precise temperature control.

[0003] In related technologies, when a permanent magnet synchronous motor drives a compressor, the compressor's mechanical frequency may be close to the power supply frequency, causing a beat frequency phenomenon. Once a beat frequency occurs, the compressor will produce a beat frequency sound. In permanent magnet synchronous motor control devices, the beat frequency phenomenon is generally suppressed by optimizing loop parameters, because changes in loop parameters will affect the motor's operating characteristics; for example, optimizing the response frequency of loops such as Automatic Speed ​​Regulation (ASR), Automatic Current Regulation (ACR), or Phase-Locked Loop.

[0004] However, the optimization of the loop parameters mentioned above has limited effect on suppressing beat frequency, thus necessitating a more effective method to suppress beat frequency. Summary of the Invention

[0005] This application provides a motor control method, device, and air conditioner that can effectively suppress beat frequency phenomena.

[0006] In a first aspect, a motor control method is provided, applied to a motor control device, which includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, and a second coordinate transformation module.

[0007] The motor control method includes: inputting the three-phase AC power output from the permanent magnet synchronous motor into a first coordinate transformation module to obtain d-axis current sampling values ​​and q-axis current sampling values; inputting the difference between the q-axis current command value and the q-axis current sampling value output from the speed control module, as well as the difference between the d-axis current command value and the d-axis current sampling value, into a current control module to obtain d-axis voltage command values ​​and q-axis voltage command values; inputting the q-axis current command value and the q-axis current sampling value into a compensation module to obtain a q-axis voltage compensation value; wherein, the compensation module is used to adjust the q-axis voltage command value output from the current control module; inputting the d-axis voltage command value output from the current control module and the compensated q-axis voltage command value into a second coordinate transformation module, the signal output from the second coordinate transformation module being used to control the permanent magnet synchronous motor, wherein, the compensated q-axis voltage command value is obtained by compensating the q-axis voltage command value with the q-axis voltage compensation value.

[0008] The motor control method provided in this application can suppress beat frequency by adjusting the amplitude of the q-axis voltage command value during motor control. Specifically, when two signals are detected to have high amplitudes and similar frequencies, causing obvious beat frequency phenomena, the q-axis voltage command value is compensated by a compensation module to reduce the amplitude of the corresponding q-axis signal. This effectively reduces the amplitude of the combined amplitude of the two signals changing periodically over time, thereby suppressing the beat frequency phenomenon.

[0009] In one possible implementation, the q-axis current command value and the q-axis current sample value are input to the compensation module to obtain the q-axis voltage compensation value. This includes: calculating the difference between the q-axis current command value and the q-axis current sample value to obtain the q-axis current error value; performing a first processing on the q-axis current error value to obtain a first amplitude modulation signal and a second amplitude modulation signal corresponding to the q-axis current error value; performing low-pass filtering on the first amplitude modulation signal and the second amplitude modulation signal respectively to obtain a first filtered signal and a second filtered signal; performing a second processing on the first filtered signal and the second filtered signal to obtain a composite signal; and adjusting the amplitude of the composite signal to obtain the q-axis voltage compensation value.

[0010] It should be understood that the compensation module can obtain the q-axis voltage compensation value by analyzing the q-axis current command value and the q-axis current sample value. This q-axis voltage compensation value is used to compensate the q-axis voltage command value output by the current control module, thereby reducing the amplitude of the corresponding q-axis signal.

[0011] In one possible implementation, the q-axis current error value undergoes a first processing step to obtain a first amplitude modulation signal and a second amplitude modulation signal corresponding to the q-axis current error value, including:

[0012] The q-axis current error value is transformed to obtain the corresponding current signal; the transformation process is as follows:

[0013]

[0014] in, Here, A is the q-axis current error value, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and Asin(ω0T) is the current signal corresponding to the q-axis current error value.

[0015] Interpolate the current signal corresponding to the q-axis current error value with sin(ω) c After multiplying T) and converting the sum and difference based on trigonometric functions, the first amplitude-modulated signal is obtained. The calculation process of the first amplitude-modulated signal is as follows:

[0016]

[0017] Where, ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the first amplitude modulation signal;

[0018] The current signal corresponding to the q-axis current error value is compared with cos(ω c After multiplying T) and converting the sum and difference based on trigonometric functions, the second amplitude-modulated signal is obtained. The calculation process of the second amplitude-modulated signal is as follows:

[0019]

[0020] in, This is the second amplitude modulation signal.

[0021] It should be understood that the first processing step is used to process the q-axis current error value. Adjustments are made to obtain the first amplitude modulation signal and the second amplitude modulation signal corresponding to the q-axis current error value, thereby realizing the modulation, demodulation and frequency analysis of signals in motor control.

[0022] In one possible implementation, low-pass filtering is performed on the first amplitude-modulated signal and the second amplitude-modulated signal to obtain a first filtered signal and a second filtered signal, respectively. This includes: low-pass filtering the first amplitude-modulated signal to obtain the first filtered signal, which is represented as follows:

[0023]

[0024] The second amplitude-modulated signal is low-pass filtered to obtain the second filtered signal, which is expressed as follows:

[0025]

[0026] Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω cThe angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

[0027] It should be understood that the high-frequency components in the first and second amplitude-modulated signals have a frequency of ω0 + ω. c The signal. In motor control devices, current signals may be subject to various interferences. Therefore, a low-pass filter can attenuate or remove signal components above the set cutoff frequency, making the signal smoother and more stable for subsequent processing.

[0028] In one possible implementation, a second processing is performed on the first filtered signal and the second filtered signal to obtain a composite signal, including: combining the first filtered signal with sin(v) c Multiply the filtered signal by cos(ω) to obtain the first signal; multiply the filtered signal by cos(ω) to obtain the second signal. c Multiply the first signal (T) by the second signal to obtain the second signal; add the first signal and the second signal together to obtain the initial composite signal. The calculation process of the initial composite signal is as follows:

[0029]

[0030] in, As the first signal, This is the second signal;

[0031] The initial composite signal is simplified to obtain the composite signal, which is represented as:

[0032]

[0033] Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

[0034] The second processing step mainly involves integrating the first and second filtered signals, for example, by superposition. By merging signals at different frequencies or coordinates, a composite signal is obtained. This composite signal can more comprehensively reflect the current state during motor operation and the difference from the desired state, providing a more accurate basis for subsequent calculation of voltage compensation values.

[0035] In one possible implementation, adjusting the amplitude of the composite signal to obtain the q-axis voltage compensation value includes: multiplying the composite signal by the proportional gain to obtain the q-axis voltage compensation value. The calculation process for the q-axis voltage compensation value is as follows:

[0036]

[0037] in, Here, K represents the q-axis voltage compensation value, and K is the proportional gain.

[0038] The proportional gain is determined by parameters such as the angular velocity output by the phase-locked loop and the constant of the permanent magnet synchronous motor. Therefore, the proportional gain will change as the angular velocity output by the phase-locked loop and the constant of the permanent magnet synchronous motor change.

[0039] By optimizing the q-axis voltage compensation value through proportional gain, the q-axis voltage compensation value can better compensate the q-axis voltage command value output by the current control module, thereby reducing the amplitude of the corresponding q-axis signal.

[0040] In a second aspect, a motor control device is provided, comprising a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, a phase-locked loop, a second coordinate transformation module, and a control module, wherein the control module is used to execute the motor control method of any one of the first aspects.

[0041] Thirdly, an air conditioner is provided, including a compressor, a frequency converter, a heat exchanger, a fan, an expansion valve, and a motor control device, which is used to control the compressor.

[0042] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect above, and will not be repeated here. Attached Figure Description

[0043] Figure 1 A schematic diagram of the permanent magnet synchronous motor control device is shown.

[0044] Figure 2 A schematic diagram of the current captured by the twin-rotor compressor when the operating frequency of the twin-rotor compressor is 47 rpm is shown.

[0045] Figure 3 It shows Figure 2 A schematic diagram of the sampling values ​​of the motor current and q-axis current;

[0046] Figure 4 A schematic diagram of FFT analysis of q-axis current sampling values ​​is shown;

[0047] Figure 5 A schematic diagram of the structure of a motor control device provided in an embodiment of this application is shown;

[0048] Figure 6 A schematic diagram of another motor control device provided in an embodiment of this application is shown;

[0049] Figure 7 This paper shows a schematic diagram of the structure of a compensation module in a motor control device provided in an embodiment of this application;

[0050] Figure 8 This paper shows a schematic diagram of the structure of another compensation module in the motor control device provided in an embodiment of this application;

[0051] Figure 9 This paper shows a schematic diagram of the structure of another compensation module in the motor control device provided in an embodiment of this application;

[0052] Figure 10 A flowchart illustrating a motor control method provided in an embodiment of this application is shown;

[0053] Figure 11 This diagram illustrates the FFT analysis of the q-axis current sampling value after implementing the motor control method provided in this embodiment of the application.

[0054] Figure 12 A flowchart illustrating a motor control method provided in an embodiment of this application is shown;

[0055] Figure 13 A comparative schematic diagram of the motor control method provided in this application for analyzing the compressor in an air conditioner is shown. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0057] It should be understood that "multiple" as mentioned in this application refers to two or more. In the description of this application, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist, for example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, to facilitate a clear description of the technical solutions of this application, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., do not necessarily imply differences.

[0058] Before providing a detailed explanation of the motor control method, device, and air conditioner provided in the embodiments of this application, the application scenarios and related technologies of the motor control method, device, and air conditioner will be explained first.

[0059] Air conditioners are devices that regulate indoor temperature and other environmental parameters, and can be classified into various types from a technical perspective. Among them, inverter air conditioners precisely control the compressor speed by changing the power supply frequency, achieving flexible adjustment of cooling or heating, thus demonstrating excellent energy efficiency and comfort.

[0060] Variable frequency air conditioners mainly consist of a compressor, a variable frequency controller, a heat exchanger, a fan, a throttling element (such as an expansion valve), and a control system. The control system, through its control circuitry, performs logical calculations and judgments based on preset parameters such as temperature and operating mode, as well as feedback signals from various sensors. This results in the issuance of corresponding control commands to precisely control the compressor speed, fan speed, and the opening degree of the electronic expansion valve, enabling the air conditioner to achieve optimal operating conditions.

[0061] The control system may include a digital signal processor (DSP), a microcontroller unit (MCU), or a field-programmable gate array (FPGA), as well as memory, input / output interfaces, etc.

[0062] In inverter air conditioners, the compressor is the core component. In cooling or heating mode, the compressor compresses the low-temperature, low-pressure refrigerant gas into a high-temperature, high-pressure gas to provide power for the cooling or heating cycle and achieve the function of temperature regulation.

[0063] The compressor is powered by a compressor motor. In a variable frequency air conditioner, the speed of the compressor motor is adjusted by changing the power supply frequency and voltage under the regulation of the variable frequency controller. The compressor motor drives the compressor rotor and other components to operate, thereby precisely controlling the compressor's operating frequency and the amount of refrigerant circulating. This allows the air conditioner to flexibly adjust its cooling or heating capacity according to changes in indoor and outdoor ambient temperatures and the set temperature, achieving the goals of energy saving and precise temperature control.

[0064] In the field of variable frequency air conditioning control, permanent magnet synchronous motors (PMSMs) are widely used to drive compressors, such as rotary compressors and twin-rotor compressors, due to their advantages such as high efficiency and energy saving, good speed regulation performance, high reliability and environmental protection.

[0065] Taking permanent magnet synchronous motors as an example, Figure 1 A schematic diagram of the permanent magnet synchronous motor control device is shown, such as... Figure 1 As shown, the three-phase AC output i of the permanent magnet synchronous motor a i b i cAfter Clark transformation, the current i is converted into a two-phase stationary coordinate system. α i β And transmit it to the Park transform, the Park transform is based on the received i α i β The rotor position angle θ converts the current into a direct-axis current in a rotating coordinate system (i.e., the d-axis current sampling value i). d ) and quadrature-axis current (i.e., q-axis current sampling value i) q ).

[0066] Speed ​​setting value ω * The input to the proportional-integral (PI) controller 110 for speed regulation is compared with the actual speed ω of the permanent magnet synchronous motor output from the phase-locked loop (PLL), and the output q-axis current command value is generated. And, the compensation amount Δi of the d-axis current output of the field weakening control. d Used for subsequent d-axis current command values The calculation, in which the d-axis current command value This is the default value.

[0067] Will with i q The difference after comparison with i d After comparison with Δi d The difference values ​​are respectively input to the PI controller 120 used for current regulation, and the output d-axis voltage setpoint u is obtained. ′ d and q-axis voltage setting value u ′ q .

[0068] Inverse Park Transform ( Figure 1 The inverse Park) receives i ′ d u ′ q And θ, converting the voltage in the rotating coordinate system into the voltage u in the two-phase stationary coordinate system. ′ α u ′ β The signal is transmitted to the modulation wave generator. The modulation wave is generated based on u. ′ α u ′ β Generate modulation signal U ′ V ′ W ′The signal is transmitted to a Pulse Width Modulation (PWM) inverter. The PWM inverter receives the modulated signal and combines it with the DC bus voltage u. dc (Output from diode rectifier bridge) The output three-phase AC voltage drives the permanent magnet synchronous motor.

[0069] It should be understood that, for Figure 1 The motor control device shown can be implemented in hardware, software, or a combination of both.

[0070] For example, in a noise test on an inverter air conditioner equipped with a dual-rotor compressor, using AC mains power at a frequency of 50 Hz, the results showed that the air conditioner produced a humming sound when the dual-rotor compressor's operating frequency was between 45 rpm and 55 rpm. Testing with an oscilloscope and current probe revealed that the dual-rotor compressor's current exhibited a beat frequency phenomenon, which directly caused the humming beat frequency sound.

[0071] It should be understood that different countries and regions around the world may use different power frequency standards. In addition to 50Hz, some countries and regions use a frequency of 60Hz.

[0072] It should also be understood that when describing the operating frequency of a twin-rotor compressor, revolutions per second (rps) is often used, which represents the number of revolutions per second. It is numerically equal to the frequency unit Hz (Hertz), which can more directly emphasize the rotational motion characteristics of the twin-rotor compressor and highlight the frequency of its mechanical operation.

[0073] In the example above, when two alternating currents with similar but not identical frequencies interact, a special current change phenomenon occurs, namely current beat frequency, which is the specific manifestation of the beat frequency phenomenon in the current field.

[0074] It should also be understood that permanent magnet synchronous motors, compressors, and other components mounted on sheet metal, as well as pipes connecting to other parts of the air conditioner, such as condenser pipes, can cause vibrations in the sheet metal, pipes, and other hardware when beat frequency occurs, further increasing the noise.

[0075] To investigate the cause of the beat frequency phenomenon in the example Figure 2 The diagram shows the current of a twin-rotor compressor captured when the compressor operates at a frequency of 47 rpm. Figure 2 As shown, waveforms of different colors are used to represent different current signals, where waveform 10 is the q-axis current sampling value. Figure 3 It shows Figure 2 A schematic diagram of the sampling values ​​of the motor current and q-axis current is shown below. Figure 3 As shown, waveform 20 is the motor current and waveform 11 is the q-axis current sampling value. Through analysis, it can be seen that the motor current generates a certain amplitude beat frequency due to the influence of the q-axis current sampling value.

[0076] Specifically, the q-axis current sampling values ​​can be analyzed using the Fast Fourier Transform (FFT). Figure 4 A schematic diagram of FFT analysis of q-axis current sample values ​​is shown, as follows: Figure 4 As shown, two signals with similar frequencies were found, namely the first current signal 31 and the second current signal 32. The first current signal 31 has a frequency of 94Hz and an amplitude of 500, while the second current signal 32 has a frequency of 100Hz and an amplitude of 260.

[0077] Analysis of the first and second current signals reveals that the first current signal is primarily generated by the mechanical characteristics of the twin-rotor compressor itself. During operation, the twin-rotor compressor generates a harmonic at the second harmonic of its mechanical frequency (harmonics are sinusoidal wave components in periodic AC signals whose frequencies are integer multiples of the fundamental frequency). In this example, the mechanical frequency of the twin-rotor compressor is 47 rpm, and the second harmonic is exactly 94 Hz. Therefore... Figure 4 The first current signal in the system is generated by the twin-rotor compressor.

[0078] Secondly, the second current signal is considered to be related to the mains input. The mains provides 50Hz AC power, while the PWM inverter in the permanent magnet synchronous motor control device requires DC power to generate a controllable AC output. The rectifier can convert AC power to DC power. In this experiment, the rectifier uses single-phase rectification, which inherently contains a second harmonic. The second harmonic of 50Hz is exactly 100Hz. Therefore, Figure 4 The second current signal is an inherent harmonic introduced during the mains rectification process.

[0079] In other words, when a permanent magnet synchronous motor drives a dual-rotor compressor, there are two signals with high amplitudes and similar frequencies (i.e., the mechanical frequency of the dual-rotor compressor is similar to the power supply frequency). The signals with similar frequencies superimpose each other, resulting in a high amplitude of the composite signal that exhibits periodic changes, which in turn causes a significant beat frequency phenomenon. Once a beat frequency occurs, the compressor will produce a beat frequency sound.

[0080] In permanent magnet synchronous motor control devices, beat frequency phenomena are generally suppressed by optimizing loop parameters, because changes in loop parameters will affect the operating characteristics of the motor; for example, optimizing the response frequency of loops such as Automatic Speed ​​Regulation (ASR), Automatic Current Regulation (ACR), or phase-locked loop.

[0081] Automatic Speed ​​Regulation (ASR) is primarily used for precise control of motor speed, such as... Figure 1 The ASR (Air Conditioner Regulator) uses a PI controller 110 for speed regulation and its surrounding loops. By monitoring and providing feedback on the motor speed in real time, the ASR can automatically adjust the power supply frequency or voltage of the motor according to the operating requirements of the air conditioner, so that the motor can operate within the set speed range.

[0082] Automatic Current Regulation (ACR) is mainly used for automatic control of motor current, such as... Figure 1 The ACR (Active Current Controller) uses a PI controller 120 for current regulation and its surrounding loops. The ACR monitors the motor current in real time, and when the current exceeds or falls below a set threshold, it adjusts the motor's drive signal to change the motor's operating state, ensuring the current remains within a safe and efficient operating range.

[0083] However, since the two signals that generate current beat frequency are inherent properties of the air conditioner itself, current beat frequency may be generated as long as the compressor in the air conditioner operates within the range corresponding to this frequency. Under the above-mentioned optimization of loop parameters, the effect of suppressing beat frequency phenomenon is poor.

[0084] Therefore, embodiments of this application provide a motor control method, device, and air conditioner. The motor control method is applied to a motor control device and an air conditioner. The motor control device includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, and a second coordinate transformation module. The motor control method inputs the three-phase AC power output from the permanent magnet synchronous motor into the first coordinate transformation module to obtain d-axis current sampling values ​​and q-axis current sampling values. The current control module then modulates the d-axis current sampling values, and the speed control module, current control module, and compensation module modulate the q-axis current sampling values ​​to obtain d-axis voltage command values ​​and compensated q-axis voltage command values. Finally, the signal output from the second coordinate transformation module controls the permanent magnet synchronous motor. The compensation module is used to adjust the q-axis voltage command value output by the current control module.

[0085] The motor control method provided in this application can suppress beat frequency by adjusting the amplitude of the q-axis voltage command value during motor control. Specifically, when two signals are detected to have high amplitudes and similar frequencies, causing obvious beat frequency phenomena, the q-axis voltage command value is compensated by a compensation module to reduce the amplitude of the corresponding q-axis signal. This effectively reduces the amplitude of the combined amplitude of the two signals changing periodically over time, thereby suppressing the beat frequency phenomenon.

[0086] The embodiments of this application will be illustrated below with reference to the accompanying drawings and through several exemplary embodiments. Figure 5 This illustration shows a schematic diagram of a motor control device provided in an embodiment of this application, taking a permanent magnet synchronous motor as an example. Figure 5 As shown, the motor control device includes a permanent magnet synchronous motor 210, a first coordinate transformation module 220, a speed control module 230, a current control module 240, a compensation module 250, and a second coordinate transformation module 260.

[0087] It should be noted that, Figure 5 The connections between the modules shown are merely illustrative and do not constitute a limitation on the connections between the modules in the permanent magnet synchronous motor control device. In other embodiments of this application, the permanent magnet synchronous motor control device may include... Figure 5 The components shown may include more or fewer components, or the permanent magnet synchronous motor control device may include... Figure 5 The combination of certain components shown in the components, or the magnetic synchronous motor control device may include sub-components of certain components shown in 5.

[0088] It should be understood that the motor control device also includes a control module, which is used to implement the software control of the motor control device. In other words, the control module is used to execute the motor control method proposed in the embodiments of this application.

[0089] The first coordinate transformation module 220 converts the three-phase AC output of the permanent magnet synchronous motor into direct-axis and quadrature-axis currents in a rotating coordinate system. It should be understood that a permanent magnet synchronous motor generates electromagnetic torque based on the interaction between the magnetic field generated by the permanent magnet and the magnetic field generated by the current in the stator windings, thus driving the motor rotor to rotate. The first coordinate transformation module 220 can transform the complex, multi-variable, strongly coupled three-phase stationary coordinate system into a two-phase rotating coordinate system, facilitating field-oriented control and precise regulation of the excitation magnetic field and electromagnetic torque. Simultaneously, in this coordinate system, the motor parameters are stable and clearly correlated with the operating state, allowing for adjustment and optimization of control parameters based on actual operating conditions. This results in good dynamic and steady-state performance of the permanent magnet synchronous motor under different conditions, improving efficiency.

[0090] In other words, the first coordinate transformation module 220 transforms the three-phase AC power output from the permanent magnet synchronous motor into a single coordinate transformation module. a i b i c Convert to d-axis current in a rotating coordinate system (i.e., d-axis current sampling value i) d ) and q-axis current (i.e., q-axis current sampling value i) q ).

[0091] In some embodiments, the first coordinate transformation module 220 may include a first transformation unit and a second transformation unit. The first transformation unit is a Clark transformation, also known as the Clark transformation, which is a linear transformation that converts a three-phase stationary coordinate system into a two-phase stationary coordinate system (αβ coordinate system). The second transformation unit is a Park transformation, also known as the Park transformation, which is a transformation that converts a two-phase stationary coordinate system into a two-phase rotating coordinate system (dq coordinate system). In motor control, although the number of variables in the two-phase stationary coordinate system after the Clark transformation is reduced, coupling still exists. The Park transformation further transforms the variables in the stationary coordinate system into the rotating coordinate system, enabling decoupled control of the motor's electromagnetic torque and flux linkage under specific control strategies (such as field-oriented control), thus simplifying the motor control algorithm.

[0092] The speed control module 230 is used to compare the real-time speed ω of the permanent magnet synchronous motor output by the phase-locked loop (i.e., to obtain the synchronization signal of the permanent magnet synchronous motor) with the speed setpoint ω preset by the control module. * By comparison, the q-axis current command value is obtained.

[0093] In some embodiments, the speed control module 230 includes a first arithmetic unit and a speed regulation control unit. The first arithmetic unit may be an adder or a subtractor, used to determine a preset speed setpoint ω. * The difference between the real-time speed ω of the permanent magnet synchronous motor output by the phase-locked loop and the speed control unit. The speed regulation control unit can be a proportional-integral controller, also known as a PI controller, which consists of a proportional (P) element and an integral (I) element. The proportional element can quickly respond to system deviations, while the integral element is used to eliminate the steady-state error of the system. The combination of the two can effectively improve the performance of motor control.

[0094] The current control module 240 is used to receive with i q The difference after comparison with i d The difference obtained from the comparison is used to output a voltage control signal for adjustment, i.e., the d-axis voltage command value. and q-axis voltage command value in, It is the d-axis current command value preset by the control module.

[0095] In some embodiments, the current control module 240 includes a field weakening control unit, a second arithmetic unit, and a current adjustment control unit. The field weakening control unit is used to implement the field weakening control function, i.e., to obtain the d-axis current compensation amount Δi. d d-axis current compensation amount Δi d For subsequent use and with i d The difference is calculated after comparison. Using field weakening control in air conditioner motors can increase the upper limit of motor operating speed, meeting the needs of air conditioners under high fan speed and other operating conditions. The second calculation unit can be an adder or a subtractor.

[0096] The current regulation and control unit can be a proportional-integral controller, also known as a PI controller, used to receive... with i q The difference after comparison with i d After comparison with Δi d The difference is used to output a voltage control signal for adjustment, i.e., the d-axis voltage command value. and q-axis voltage command value

[0097] The compensation module 250 is used to adjust the q-axis voltage command value output by the current control module. Specifically, the compensation module 250 analyzes the q-axis current command value and the q-axis current sampling value to obtain the q-axis voltage compensation value. This q-axis voltage compensation value is used to compensate the q-axis voltage command value output by the current control module, thereby reducing the amplitude of the corresponding q-axis signal.

[0098] The second coordinate transformation module 260 is used to transform the d-axis voltage (i.e., the d-axis voltage command value) in the two-phase rotating coordinate system. ) and q-axis voltage (i.e., the compensated q-axis voltage command value) Converted into a three-phase modulation signal U * V * W * This causes the PWM inverter to receive the modulation signal U * V * W * With DC bus voltage u dc Combined, the output three-phase AC voltage drives the permanent magnet synchronous motor.

[0099] In some embodiments, the second coordinate transformation module 260 may include a third transformation unit and a fourth transformation unit. The third transformation unit is an inverse Park transformation (IPT), also known as the reverse Park transformation, which is the inverse process of the Park transformation. Its function is to transform variables in a two-phase rotating coordinate system back to a two-phase stationary coordinate system. In the actual process of motor control, calculations and control are usually performed in the dq coordinate system, but the motor drive needs to be implemented in a three-phase stationary coordinate system. The fourth transformation unit is a modulation wave generation unit, used to generate a three-phase modulation signal from the voltage data in the two-phase stationary coordinate system using a specific modulation algorithm (e.g., space vector pulse width modulation, sinusoidal pulse width modulation, etc.).

[0100] It should be understood that the motor control device also includes a phase-locked loop, a PWM inverter, an AC power supply, a diode rectifier bridge, etc., which can be referred to above. Figure 1 The detailed descriptions of phase-locked loops, PWM inverters, AC power supplies, and diode rectifier bridges in the original text will not be repeated here.

[0101] Therefore, the motor control device provided in this application includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, and a second coordinate transformation module. A compensation module is added to the motor control device. When two signals are detected to have high amplitudes and similar frequencies, causing a significant beat frequency phenomenon, the compensation module can compensate for the q-axis voltage command value, thereby reducing the amplitude of the corresponding q-axis signal. This effectively reduces the amplitude of the combined amplitude of these two signals changing periodically over time, thus suppressing the beat frequency phenomenon.

[0102] Figure 6 This paper illustrates a schematic diagram of another motor control device provided in an embodiment of this application, taking a permanent magnet synchronous motor as an example. Figure 6 As shown, in some embodiments, the motor control device includes a position observer, a phase-locked loop, a Clark transform, a Park transform, a PI controller 231 for speed regulation, a field weakening control unit, a PI controller 241 for current regulation, a compensation module, an inverse Park transform, a modulation wave generation unit, a PWM inverter, an AC power supply, and a diode rectifier bridge.

[0103] The three-phase AC output of the permanent magnet synchronous motor i a i b i c After Clark transformation, the current i is converted into a two-phase stationary coordinate system. α i β And transmit it to the Park transform, the Park transform is based on the received i α i βThe rotor position angle θ is used to convert the current into a d-axis current sampling value i in a rotating coordinate system. d and q-axis current sampling value i q .

[0104] Speed ​​setting value ω * The input is fed to the PI controller 231 for speed regulation, compared with the actual speed ω of the permanent magnet synchronous motor output by the phase-locked loop, and outputs the q-axis current command value. And, the compensation amount Δi of the d-axis current output of the field weakening control. d , used for subsequent interactions with i d and The calculation of the difference after comparison, where the d-axis current command value This is the default value.

[0105] Will with i q The difference after comparison with i d After comparison with Δi d The differences are respectively input to the PI controller 241 used for current regulation, and the output d-axis voltage setpoint is obtained. And the q-axis voltage setting value.

[0106] q-axis current command value and q-axis current sampling value i q The input is sent to the compensation module, which then adjusts the q-axis current command value. and q-axis current sampling value i q Modulation is performed to obtain the q-axis voltage compensation value, and this q-axis voltage compensation value is then used to compensate the q-axis voltage command value output by the current control module to obtain the compensated q-axis voltage setpoint.

[0107] Inverse Park Transform ( Figure 6 The inverse Park receives the d-axis voltage setpoint. Compensated q-axis voltage setting And θ, converting the voltage in the rotating coordinate system into the voltage in the two-phase stationary coordinate system. Transmitted to modulated wave generation. Modulated wave generation is based on... Generate modulation signal U * V * W * The signal is transmitted to the PWM inverter, which receives the modulation signal and the DC bus voltage u. dc Combined, the output three-phase AC voltage drives the permanent magnet synchronous motor.

[0108] Therefore, the motor control device provided in this application includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, and a second coordinate transformation module. A compensation module is added to the motor control device. When two signals are detected to have high amplitudes and similar frequencies, causing a significant beat frequency phenomenon, the compensation module can compensate for the q-axis voltage command value, thereby reducing the amplitude of the corresponding q-axis signal. This effectively reduces the amplitude of the combined amplitude of these two signals changing periodically over time, thus suppressing the beat frequency phenomenon.

[0109] Figure 7 This paper shows a schematic diagram of the structure of a compensation module in a motor control device provided in an embodiment of this application, as shown below. Figure 7 As shown, the compensation module 250 includes an error calculation unit 251, a conversion unit 252, a filtering unit 253, and a gain unit 254.

[0110] Among them, the error calculation unit 251 is used to calculate the q-axis current command value. and q-axis current sampling value i q The difference is calculated to obtain the q-axis current error value. The conversion unit 252 is used to perform a first processing on the q-axis current error value. The first processing is used to process the q-axis current error value. Adjustments are made to obtain the first amplitude modulation signal and the second amplitude modulation signal corresponding to the q-axis current error value. The filtering unit 253 is used to perform low-pass filtering on the first amplitude modulation signal and the second amplitude modulation signal respectively to obtain the filtered first filter signal and the second filter signal; the gain unit 254 is used to perform a second processing on the first filter signal and the second filter signal, the second processing is used to integrate the first filter signal and the second filter signal to obtain a composite signal; and the amplitude of the composite signal is adjusted by the proportional gain to obtain the q-axis voltage compensation value.

[0111] The embodiments of this application can compensate the q-axis voltage command value through the compensation module, thereby reducing the amplitude of the corresponding q-axis signal. This can effectively reduce the amplitude of the combined amplitude of the two signals changing periodically over time, thereby suppressing the beat frequency phenomenon.

[0112] Figure 8 This paper shows a schematic diagram of the structure of another compensation module in the motor control device provided in an embodiment of this application, as shown below. Figure 8 As shown, in some embodiments, the conversion unit 252 includes a first conversion subunit and a second conversion subunit; the filtering unit 253 includes a first filtering subunit and a second filtering subunit; and the gain unit 254 includes a composite subunit and a gain subunit.

[0113] The first conversion subunit is used to adjust the q-axis current error value. The transformed current signal is modulated to obtain the first amplitude-modulated signal; the second conversion subunit is used to adjust the q-axis current error value. The transformed current signal is modulated to obtain a second amplitude-modulated signal; the process of loading the low-frequency current signal onto the high-frequency carrier signal facilitates subsequent processing and transmission.

[0114] Both the first and second filtering subunits are low-pass filtering subunits, which remove high-frequency components from the first and second amplitude-modulated signals.

[0115] The composite subunit is used to integrate the first and second filtered signals to obtain a composite signal.

[0116] The gain subunit is used to stabilize the amplitude of the signal corresponding to the q-axis. Based on the proportional gain, the amplitude of the composite signal is adjusted to obtain the q-axis voltage compensation value. It should be noted that the determination of the proportional gain includes the angular velocity of the PLL output and the permanent magnet synchronous motor constant. It should be understood that the proportional gain changes with parameters such as the angular velocity of the PLL output and the permanent magnet synchronous motor constant.

[0117] Figure 9 This paper shows a schematic diagram of the structure of another compensation module in the motor control device provided in an embodiment of this application, as shown below. Figure 9 As shown, in some embodiments, the command value for the q-axis current is... and q-axis current sampling value i q The difference is calculated to obtain the q-axis current error value. and q-axis current error value By performing a formal transformation, the q-axis current error value is obtained. The corresponding current signal; then pass through sin(ω) respectively c T), cos(ω) c The first amplitude-modulated signal and the second amplitude-modulated signal are multiplied by the current signal and subjected to trigonometric function product and difference operations to obtain the first amplitude-modulated signal and the second amplitude-modulated signal after modulation. Then, the first amplitude-modulated signal and the second amplitude-modulated signal are low-pass filtered to obtain the first filtered signal and the second filtered signal after filtering. Then, the second processing is used to integrate the first filtered signal and the second filtered signal, and the integrated composite signal is adjusted by adjusting the proportional gain to obtain the q-axis voltage compensation value.

[0118] It should be understood that the q-axis voltage compensation value is used to compensate for the q-axis voltage command value output by the current control module, thus obtaining the compensated q-axis voltage setpoint. Reduce the amplitude of the signal corresponding to the q-axis. Since the intensity of the beat frequency phenomenon is closely related to the amplitude of the signals involved in the superposition, when the amplitude of the signal corresponding to the q-axis is reduced, the periodic fluctuation amplitude of the synthesized signal also decreases.

[0119] To facilitate a further understanding of the technical solutions in some embodiments of this application, the technical solutions of the motor control method and how these solutions solve the aforementioned technical problems are described in detail below with reference to specific embodiments and accompanying drawings. The embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application.

[0120] Figure 10 This paper illustrates a flowchart of a motor control method provided in an embodiment of this application, which is applied to the above-mentioned... Figure 5 The motor control device shown, taking a permanent magnet synchronous motor as an example, compensates for the q-axis voltage command value and reduces the amplitude of the corresponding q-axis signal when it detects that the amplitudes of two signals are both at high levels and their frequencies are similar, causing a significant beat frequency phenomenon. For example... Figure 10 As shown, the motor control method includes the following steps:

[0121] S310. Input the three-phase AC power output from the permanent magnet synchronous motor into the first coordinate transformation module to obtain the d-axis current sampling value and the q-axis current sampling value.

[0122] S320. Input the difference between the q-axis current command value and the q-axis current sample value output by the speed control module, and the difference between the d-axis current command value and the d-axis current sample value, into the current control module to obtain the d-axis voltage command value and the q-axis voltage command value.

[0123] q-axis current command value With q-axis current sampling value i q The difference, d-axis current command value With d-axis current sampling value i d The difference is input to the current control module, which outputs a voltage control signal for adjustment, i.e., the d-axis voltage command value. and q-axis voltage command value in, It is the preset d-axis current command value.

[0124] It should be understood that before step 310, the process also includes detecting motor beat frequency and performing FFT analysis on the relevant current signals when beat frequency occurs in the motor control device (e.g., ...). Figure 4 As shown), a first current signal and a second current signal that generate beat frequency display are determined, wherein the first frequency of the first current signal is similar to the second frequency of the second current signal.

[0125] It should be understood that there is no limit to the number of the first current signal and the second current signal. Therefore, the current signal that can be displayed with beat frequency can be two signals or more signals.

[0126] Among them, the first current signal is the signal corresponding to the q-axis. For example, the first current signal is generated by the mechanical characteristics of the dual-rotor compressor itself. During the operation of the dual-rotor compressor, a harmonic of the second harmonic of the mechanical frequency will be generated.

[0127] The second current signal is an inherent harmonic introduced by the AC power supply, such as Figure 5 , Figure 6 As shown, AC power is input through a rectifier. The rectifier uses a single-phase rectification method, which will inherently contain harmonics of the second harmonic frequency.

[0128] S330: Input the q-axis current command value and the q-axis current sample value into the compensation module to obtain the q-axis voltage compensation value.

[0129] The compensation module is used to adjust the q-axis voltage command value output by the current control module.

[0130] In other words, the compensation module analyzes the q-axis current command value and the q-axis current sample value to obtain the q-axis voltage compensation value. This q-axis voltage compensation value is used to compensate the q-axis voltage command value output by the current control module, thereby reducing the amplitude of the corresponding q-axis signal.

[0131] It should be understood that since the intensity of the beat frequency phenomenon is closely related to the amplitude of the signals involved in the superposition, when the amplitude of the signal corresponding to the q-axis is reduced, the amplitude of the combined amplitude of the two signals changing periodically over time can be effectively reduced, thereby suppressing the beat frequency phenomenon.

[0132] S340. Input the d-axis voltage command value and the compensated q-axis voltage command value output by the current control module to the second coordinate transformation module. The signal output by the second coordinate transformation module controls the permanent magnet synchronous motor.

[0133] The compensated q-axis voltage command value is obtained by compensating the q-axis voltage command value with the q-axis voltage compensation value.

[0134] It should be understood that the voltage received by the second coordinate transformation module is the d-axis voltage command value and the q-axis voltage command value after compensation by the compensation module, and converts the d-axis voltage command value and the compensated q-axis voltage command value into a three-phase modulation signal for adjustment of the permanent magnet synchronous motor to control the permanent magnet synchronous motor.

[0135] It should also be understood that controlling the permanent magnet synchronous motor by using the d-axis voltage command value and the compensated q-axis voltage command value can reduce the amplitude of the corresponding q-axis signal, thereby alleviating the beat frequency phenomenon generated by the compressor controlled by the permanent magnet synchronous motor.

[0136] After compensating the q-axis voltage command value with the q-axis voltage compensation value, the amplitude of the corresponding q-axis current (i.e., the first current signal) can be reduced. At this time, the q-axis current sample value is analyzed by Fast Fourier Transform (FFT). Figure 11 This diagram illustrates the FFT analysis of the q-axis current sampling value after implementing the motor control method provided in this embodiment of the application. Figure 11 As shown, the first current signal 33 (i.e., the q-axis current sample value collected by compensating the q-axis voltage command value through the compensation module) and the second current signal 34 (i.e., the inherent harmonics introduced by the AC power supply) are obtained after compensation. The first current signal 33 has a frequency of 94Hz and an amplitude of 120, and the second current signal 34 has a frequency of 100Hz and an amplitude of 200.

[0137] Compare Figure 4 and Figure 11 It can be seen that the amplitude of the first current signal decreases significantly from 500 to 120, thus suppressing the amplitude of the first current signal.

[0138] The motor control method provided in this application, when it is detected that the amplitudes of two signals are both at a high level and their frequencies are similar, causing obvious beat frequency phenomenon, can compensate the q-axis voltage command value through the compensation module, thereby reducing the amplitude of the corresponding q-axis signal. This can effectively reduce the amplitude of the combined amplitude of the two signals changing periodically over time, alleviate the beat frequency phenomenon generated by the compressor controlled by the permanent magnet synchronous motor, and thus suppress the beat frequency phenomenon.

[0139] In order to compensate for the q-axis voltage command value. Figure 12 This paper illustrates a flowchart of a motor control method provided in an embodiment of this application. Figure 10 In step 330, regarding the process by which the compensation module modulates the q-axis current command value and the q-axis current sample value to obtain the d-axis voltage command value and the compensated q-axis voltage command value, as follows: Figure 12 As shown, it includes the following steps:

[0140] S331. Calculate the difference between the q-axis current command value and the q-axis current sample value to obtain the q-axis current error value.

[0141] Among them, the q-axis current error value in, The q-axis current command value and i q This is the q-axis current sampling value.

[0142] S332. Perform a first processing on the q-axis current error value to obtain the first amplitude modulation signal and the second amplitude modulation signal corresponding to the q-axis current error value.

[0143] The first process is used to process the q-axis current error value. The adjustment involves the first processing of the q-axis current error value, including the following processes (1)-(3):

[0144] (1) Transform the q-axis current error value to obtain the current signal corresponding to the q-axis current error value; the transformation process is as follows:

[0145]

[0146] in, Here, A is the q-axis current error value, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and Asin(ω0T) is the current signal corresponding to the q-axis current error value.

[0147] (2) Interpolate the current signal corresponding to the q-axis current error value with sin(ω) c After multiplying T) and converting the sum and difference based on trigonometric functions, the first amplitude-modulated signal is obtained. The calculation process of the first amplitude-modulated signal is as follows:

[0148]

[0149] Where, ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the first amplitude modulation signal.

[0150] (3) Compare the current signal corresponding to the q-axis current error value with cos(ω c After multiplying T) and converting the sum and difference based on trigonometric functions, the second amplitude-modulated signal is obtained. The calculation process of the second amplitude-modulated signal is as follows:

[0151]

[0152] Among them, among them, This is the second amplitude modulation signal.

[0153] It should be understood that processes (2) and (3) above can be performed simultaneously. The above processes are signal processing in motor control, used for modulation, demodulation, and frequency analysis, etc.

[0154] S333. Perform low-pass filtering on the first amplitude modulation signal and the second amplitude modulation signal respectively to obtain the first filtered signal and the second filtered signal.

[0155] It should be understood that the high-frequency components in the first and second amplitude-modulated signals have a frequency of ω0 + ω. cThe signal. In motor control devices, current signals may be subject to various interferences. Therefore, a low-pass filter can attenuate or remove signal components above the set cutoff frequency, making the signal smoother and more stable for subsequent processing.

[0156] The low-pass filtering of the first amplitude-modulated signal and the second amplitude-modulated signal includes the following processes (1)-(2):

[0157] (1) The first amplitude-modulated signal is low-pass filtered to obtain the first filtered signal, which is expressed as:

[0158]

[0159] (2) The second amplitude-modulated signal is low-pass filtered to obtain the second filtered signal, which is expressed as:

[0160]

[0161] Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

[0162] S334. Perform a second processing on the first filtered signal and the second filtered signal to obtain a composite signal, and adjust the amplitude of the composite signal to obtain the q-axis voltage compensation value.

[0163] It should be understood that the second processing mainly involves integrating the first and second filtered signals, for example, superimposing them. By merging signals at different frequencies or coordinates, a composite signal is obtained. This composite signal can more comprehensively reflect the current state during motor operation and the difference from the desired state, providing a more accurate basis for subsequent calculation of voltage compensation values.

[0164] The second processing of the first and second filtered signals includes the following processes (1)-(4):

[0165] (1) The first filtered signal is compared with sin(ω) c Multiplying T) yields the first signal.

[0166] (2) The second filtered signal is compared with cos(ω) c Multiplying T) yields the second signal.

[0167] (3) Add the first signal and the second signal to obtain the initial composite signal. The calculation process of the initial composite signal is as follows:

[0168]

[0169] (4) Simplify the initial composite signal to obtain the composite signal, which is represented as:

[0170]

[0171] Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

[0172] Furthermore, adjusting the amplitude of the composite signal involves multiplying the composite signal by the proportional gain to obtain the q-axis voltage compensation value. The calculation process for the q-axis voltage compensation value is as follows:

[0173]

[0174] in, Here, K represents the q-axis voltage compensation value, and K is the proportional gain.

[0175] The proportional gain is determined by parameters such as the angular velocity output by the phase-locked loop and the constant of the permanent magnet synchronous motor. Therefore, the proportional gain will change as the angular velocity output by the phase-locked loop and the constant of the permanent magnet synchronous motor change.

[0176] This application provides a motor control method applied to a motor control device and an air conditioner. The method inputs the three-phase AC power output from a permanent magnet synchronous motor into a first coordinate transformation module to obtain d-axis and q-axis current sampling values. Then, a current control module modulates the d-axis current sampling values, and a speed control module, a current control module, and a compensation module modulate the q-axis current sampling values ​​to obtain d-axis voltage command values ​​and compensated q-axis voltage command values. Finally, the permanent magnet synchronous motor is controlled by a signal output from a second coordinate transformation module. The compensation module is used to adjust the q-axis voltage command value output by the current control module.

[0177] In motor control, the amplitude of the q-axis voltage command value can be adjusted to suppress beat frequency. Specifically, when two signals are detected to have high amplitudes and similar frequencies, causing significant beat frequency, the q-axis voltage command value can be compensated by a compensation module to reduce the amplitude of the corresponding q-axis signal. This effectively reduces the amplitude of the combined amplitude of the two signals changing periodically over time, thereby suppressing the beat frequency phenomenon.

[0178] This application also provides an air conditioner, including a compressor, a frequency converter, a heat exchanger, a fan, an expansion valve, and a motor control device. The motor control device is used to control the compressor via a permanent magnet synchronous motor, and the motor control device is used to execute the above-described motor control methods.

[0179] Among them, the compressor can refer to a twin-rotor compressor.

[0180] It should be understood that the air conditioner provided in this application embodiment can have various implementation forms, such as central air conditioning, multi-split air conditioning, etc. Central air conditioning is a system in which one or more outdoor units deliver cooling or heating to multiple indoor areas through systems such as air ducts or hot and cold water pipes, thereby achieving centralized air conditioning of the entire building or a large space. Multi-split air conditioning is a special form of central air conditioning.

[0181] It should also be understood that when the mechanical frequency of a twin-rotor compressor is close to the power supply frequency, resulting in beat frequency, the compensation module in the motor control device can compensate for the q-axis voltage command value, thereby reducing the amplitude of the corresponding q-axis signal. Figure 13 This paper presents a comparative schematic diagram of the motor control method provided in the embodiments of this application for the analysis of the compressor in an air conditioner, as shown in the diagram. Figure 13 As shown in (1), this is the current waveform diagram of the beat frequency signal generated when no compensation module is added to the motor control device in the air conditioner. There is a clear beat frequency phenomenon and a clear humming sound. Figure 13 As shown in (2), the current waveforms of the two signals after adding the compensation module to the motor control device in the air conditioner are shown. This alleviates the beat frequency phenomenon generated by the compressor controlled by the permanent magnet synchronous motor. The beat frequency phenomenon suppression effect is obvious, and the humming sound is greatly reduced.

[0182] Furthermore, with the beat frequency phenomenon effectively suppressed, the vibration of hardware equipment such as sheet metal and pipes in the air conditioner is also reduced, improving the air conditioner's ability to operate smoothly and enhancing the user experience.

[0183] Specific details, such as particular system architectures and techniques, are set forth for illustrative purposes and not for limitation, to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted to avoid unnecessary detail that could obscure the description of this application.

[0184] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0185] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0186] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0187] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for example, the division of units is merely a logical functional division, and there may be other division methods in actual implementation; for example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0188] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0189] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0190] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A motor control method, characterized in that, It is applied to a motor control device, which includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, and a second coordinate transformation module. The motor control method includes: The three-phase AC power output from the permanent magnet synchronous motor is input into the first coordinate transformation module to obtain the d-axis current sampling value and the q-axis current sampling value. The difference between the q-axis current command value and the q-axis current sample value output by the speed control module, and the difference between the d-axis current command value and the d-axis current sample value, are input to the current control module to obtain the d-axis voltage command value and the q-axis voltage command value. The q-axis current command value and the q-axis current sample value are input to the compensation module to obtain the q-axis voltage compensation value; wherein, the compensation module is used to adjust the q-axis voltage command value output by the current control module; The d-axis voltage command value and the compensated q-axis voltage command value output by the current control module are input to the second coordinate transformation module. The signal output by the second coordinate transformation module is used to control the permanent magnet synchronous motor. The compensated q-axis voltage command value is obtained by compensating the q-axis voltage command value with the q-axis voltage compensation value.

2. The motor control method according to claim 1, characterized in that, The step of inputting the q-axis current command value and the q-axis current sample value into the compensation module to obtain the q-axis voltage compensation value includes: The difference between the q-axis current command value and the q-axis current sample value is calculated to obtain the q-axis current error value; The q-axis current error value is processed to obtain a first amplitude modulation signal and a second amplitude modulation signal corresponding to the q-axis current error value. The first amplitude-modulated signal and the second amplitude-modulated signal are respectively low-pass filtered to obtain the first filtered signal and the second filtered signal; The first filtered signal and the second filtered signal are subjected to a second processing to obtain a composite signal, and the amplitude of the composite signal is adjusted to obtain the q-axis voltage compensation value.

3. The motor control method according to claim 2, characterized in that, The first processing of the q-axis current error value to obtain the first amplitude modulation signal and the second amplitude modulation signal corresponding to the q-axis current error value includes: The q-axis current error value is transformed to obtain the current signal corresponding to the q-axis current error value; the transformation process is as follows: in, Let A be the q-axis current error value, ω0 be the angular velocity of the first current signal that generates the beat frequency phenomenon, T be the acquisition period, and Asin(ω0T) be the current signal corresponding to the q-axis current error value. The current signal corresponding to the q-axis current error value is compared with sin(ω) c After multiplying by T), and then converting the sum and difference based on the trigonometric function product, the first amplitude-modulated signal is obtained. The calculation process of the first amplitude-modulated signal is as follows: Where, ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. The first amplitude modulation signal; The current signal corresponding to the q-axis current error value is compared with cos(ω c After multiplying by T), and then converting the sum and difference based on trigonometric functions, the second amplitude-modulated signal is obtained. The calculation process of the second amplitude-modulated signal is as follows: in, This is the second amplitude modulation signal.

4. The motor control method according to claim 3, characterized in that, The step of performing low-pass filtering on the first amplitude-modulated signal and the second amplitude-modulated signal to obtain a first filtered signal and a second filtered signal includes: The first amplitude-modulated signal is low-pass filtered to obtain the first filtered signal, which is expressed as follows: The second amplitude-modulated signal is low-pass filtered to obtain the second filtered signal, which is expressed as follows: Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

5. The motor control method according to claim 4, characterized in that, The second processing of the first filtered signal and the second filtered signal to obtain a composite signal includes: The first filtered signal is compared with sin(ω) c Multiply T by T to obtain the first signal; The second filtered signal is compared with cos(ω) c Multiplying T) by T) yields the second signal; The first signal and the second signal are added together to obtain the initial composite signal. The calculation process of the initial composite signal is as follows: in, The first signal, This is the second signal; The initial composite signal is simplified to obtain the composite signal, which is represented as follows: Where A is the amplitude, ω0 is the angular velocity of the first current signal that generates the beat frequency phenomenon, T is the acquisition period, and ω c The angular velocity of the second current signal that generates the beat frequency phenomenon. This is the phase shift.

6. The motor control method according to claim 5, characterized in that, The step of adjusting the amplitude of the composite signal to obtain the q-axis voltage compensation value includes: The composite signal is multiplied by the proportional gain to obtain the q-axis voltage compensation value. The calculation process for the q-axis voltage compensation value is as follows: in, Here, K represents the q-axis voltage compensation value, and K is the proportional gain.

7. The motor control method according to claim 6, characterized in that, The motor control device also includes a phase-locked loop, and the determination of the proportional gain includes the angular velocity output by the phase-locked loop and the permanent magnet synchronous motor constant.

8. The motor control method according to any one of claims 1 to 7, characterized in that, Before inputting the difference between the q-axis current command value and the q-axis current sample value output by the speed control module, and the difference between the d-axis current command value and the d-axis current sample value, into the current control module, the method further includes: When the motor control device experiences a beat frequency phenomenon, an FFT analysis is performed on the relevant current signal to determine the first current signal and the second current signal that generate the beat frequency display, wherein the first frequency of the first current signal is similar to the second frequency of the second current signal.

9. A motor control device, characterized in that, The motor control device includes a permanent magnet synchronous motor, a first coordinate transformation module, a speed control module, a current control module, a compensation module, a phase-locked loop, a second coordinate transformation module, and a control module. The control module is used to execute the motor control method as described in any one of claims 1 to 8.

10. An air conditioner, characterized in that, It includes a compressor, a frequency converter, a heat exchanger, a fan, an expansion valve, and a motor control device as described in claim 9, wherein the motor control device is used to control the compressor.

Images