Motor control method, controller, motor, refrigerator, medium, and program product

Abstract

The application discloses a motor control method, a controller, a motor, a refrigerator, a medium and a program product. A direct-current bus voltage and a cross-axis current of a motor are acquired, and a direct-axis voltage and a cross-axis voltage are acquired. An initial direct-axis current is generated through field weakening control according to the direct-axis voltage, the cross-axis voltage and the direct-current bus voltage. A target frequency disturbance component caused by direct-current bus voltage fluctuation and a direct-current component used for field weakening control are separated from the initial direct-axis current. A phase of the target frequency disturbance component is calculated and optimized to obtain a target alternating current component, with minimization of a harmonic component of the target frequency in the cross-axis current as an optimization target. A direct-axis reference current is synthesized according to the target alternating current component and the direct-current component, and the motor is controlled according to the direct-axis reference current. In the working condition of the direct-current bus voltage fluctuation, energy backflow can be effectively inhibited, current harmonics can be reduced, torque pulsation can be reduced, and the running stability of the motor can be improved.

Description

Technical Field

[0001] This application relates to the field of motor technology, and in particular to a motor control method, controller, motor, refrigerator, medium, and program product. Background Technology

[0002] In motor drive systems employing film capacitors, the DC bus voltage is prone to severe fluctuations due to the lack of electrolytic capacitors, leading to energy backflow and affecting system stability and reliability. While field weakening control can alleviate this problem in related technologies, it is difficult to effectively suppress the AC component introduced by voltage fluctuations, resulting in significant ripple in the direct-axis current, which in turn causes torque pulsation and additional current harmonics. Therefore, in film capacitor-based motor drive systems, there is an urgent need for a control method that can overcome the effects of DC bus voltage fluctuations and effectively suppress energy backflow. Summary of the Invention

[0003] The purpose of this application is to at least solve one of the technical problems existing in the prior art, and to provide a motor control method, controller, motor, refrigerator, medium and program product that can maintain voltage balance, effectively suppress energy backflow, reduce torque pulsation and improve the smoothness of motor operation.

[0004] In a first aspect, embodiments of this application provide a motor control method, the motor control method comprising: Obtain the DC bus voltage and quadrature axis current of the motor, and obtain the direct axis voltage and quadrature axis voltage; An initial direct-axis current is generated by magnetic weakening control based on the direct-axis voltage, the quadrature-axis voltage, and the DC bus voltage. The target frequency disturbance component caused by DC bus voltage fluctuation and the DC component used for field weakening control are separated from the initial direct-axis current. With minimizing the harmonic components of the target frequency in the quadrature-axis current as the optimization objective, the phase of the target frequency disturbance component is optimized and calculated to obtain the target AC component; A direct-axis reference current is synthesized based on the target AC component and the DC component, and the motor is controlled based on the direct-axis reference current.

[0005] In the motor control method proposed in this application embodiment, the step of optimizing the phase of the target frequency disturbance component to obtain the target disturbance parameter by minimizing the harmonic component of the target frequency in the quadrature-axis current as the optimization objective includes: The reference phase angle and reference amplitude information are extracted from the target frequency disturbance component in the initial direct-axis current; With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, the reference phase angle is adaptively iteratively calculated to obtain the target phase angle; The target AC component is obtained by combining the reference amplitude information and the target phase angle.

[0006] In the motor control method proposed in this application embodiment, the step of extracting the reference phase angle and reference amplitude information of the target frequency disturbance component caused by the DC bus voltage fluctuation from the initial direct-axis current includes: The initial direct-axis current is bandpass filtered to extract the target frequency disturbance component caused by DC bus voltage fluctuations; The target frequency disturbance component is multiplied by the first local oscillator signal, the product is low-pass filtered to obtain the phase error signal, and the phase error signal is subjected to proportional-integral control to obtain the reference phase angle. The target frequency disturbance component is multiplied by the second local oscillation signal, and the product is low-pass filtered to obtain the reference amplitude information. The second local oscillation signal is orthogonal to the first local oscillation signal, and the first local oscillation signal and the second local oscillation signal update phase information according to the reference phase angle.

[0007] In the motor control method proposed in this application embodiment, the step of adaptively iteratively calculating the reference phase angle to obtain the target phase angle includes: The harmonic component of the target frequency in the quadrature current is used as the instantaneous error signal, the reference phase angle is used as the starting phase value in the iteration process, and a reference input signal synchronized with the target frequency disturbance component is generated according to the reference phase angle. The phase value is adjusted based on the product of the instantaneous error signal and the reference input signal, and a preset step size factor; When the mean square value of the instantaneous error signal satisfies the convergence condition, the current phase value is taken as the target phase angle.

[0008] In the motor control method proposed in this application embodiment, the step of optimizing the phase of the target frequency disturbance component to obtain the target AC component by minimizing the harmonic component of the target frequency in the quadrature-axis current as the optimization objective includes: With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, an adaptive iterative algorithm is used to calculate the phase correction. The target phase angle is obtained by superimposing the reference phase angle and the phase correction amount.

[0009] In the motor control method proposed in this application embodiment, the step of calculating the phase correction amount using an adaptive iterative algorithm with the objective of minimizing the harmonic components of the target frequency in the quadrature-axis current includes: The initial value of the phase correction is set to zero, a reference input signal synchronized with the target frequency disturbance component is generated based on the reference phase angle, and the harmonic component of the target frequency in the quadrature current is used as the instantaneous error signal. When the mean square value of the instantaneous error signal does not meet the convergence condition, the reference input signal is multiplied by the instantaneous error signal to obtain the direction indication, the direction indication is multiplied by the preset adjustment step size to obtain the correction increment, and the correction increment is added to the current value of the phase correction to obtain the updated phase correction. When the mean square value of the instantaneous error signal satisfies the convergence condition, the phase correction amount is output.

[0010] In the motor control method proposed in this application embodiment, the convergence condition is that the mean square value of the instantaneous error signal is less than a first preset threshold, or the change in the number of consecutive preset iterations is less than a second preset threshold.

[0011] In the motor control method proposed in this application embodiment, the step of generating an initial direct-axis current through field weakening control based on the direct-axis voltage, the quadrature-axis voltage, and the DC bus voltage includes: The stator voltage amplitude is determined based on the direct-axis voltage and the quadrature-axis voltage, and the voltage limit is determined based on the DC bus voltage. The stator voltage amplitude is compared with the voltage limit to obtain the voltage error signal; The voltage error signal is input to a quasi-proportional-integral-resonant controller, which performs proportional, integral, and resonant operations centered on the target frequency in parallel to generate an initial direct-axis current.

[0012] In the motor control method proposed in the embodiments of this application, the step of controlling the motor according to the direct-axis reference current includes: The reference angular velocity and the actual angular velocity of the motor are obtained, and the difference between the reference angular velocity and the actual angular velocity is input to the proportional-integral controller, which outputs the quadrature-axis reference current. Current loop control is performed based on the direct-axis reference current and the quadrature-axis reference current to generate a direct-axis reference voltage and a quadrature-axis reference voltage. By performing coordinate transformation on the direct-axis reference voltage and the quadrature-axis reference voltage, two-phase static voltages are obtained; A pulse width modulation signal is generated based on the two-phase static voltage, and the motor is controlled based on the pulse width modulation signal.

[0013] In the motor control method proposed in this application embodiment, the step of performing coordinate transformation on the direct-axis reference voltage and the quadrature-axis reference voltage to obtain two-phase stationary voltage includes: When the quadrature axis reference voltage is less than zero, the quadrature axis reference voltage is limited to a preset positive voltage. Perform an inverse Park transformation on the direct-axis reference voltage and the quadrature-axis reference voltage after setting the limit to obtain the two-phase stationary voltage in the two-phase stationary coordinate system.

[0014] In the motor control method proposed in this application embodiment, the step of generating a pulse width modulation signal based on the two-phase stationary voltage includes: A composite voltage vector is generated based on the two-phase static voltage, and the modulation index is obtained based on the ratio of the amplitude of the composite voltage vector to the DC bus voltage. Based on the modulation coefficient, the modulation region where the synthesized voltage vector is located is determined, and the synthesized voltage vector is adjusted according to the modulation region to obtain the target voltage vector so that the target voltage vector meets the inverter output voltage limit of the motor. Based on the target voltage vector, a pulse width modulation signal is generated by space vector pulse width modulation.

[0015] In the motor control method proposed in this application embodiment, the modulation region includes a linear modulation region and an overmodulation region. The step of adjusting the synthesized voltage vector according to the current modulation region to obtain a target voltage vector includes: When the synthesized voltage vector is in the linear modulation region, the synthesized voltage vector is used as the target voltage vector; When the synthesized voltage vector is in the overmodulation region, the amplitude and / or phase angle of the synthesized voltage vector are corrected to obtain the target voltage vector.

[0016] In the motor control method proposed in this application embodiment, the target frequency is twice the grid voltage frequency.

[0017] Secondly, embodiments of this application provide a controller, including a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the program to implement the motor control method described in the first aspect embodiment above.

[0018] Thirdly, embodiments of this application also provide a motor, including the controller described in the second aspect of the embodiments above.

[0019] Fourthly, embodiments of this application also provide a refrigerator, including the controller described in the second aspect embodiment above or the motor described in the third aspect embodiment.

[0020] Fifthly, embodiments of this application also provide a computer-readable storage medium storing computer-executable instructions for causing a controller to perform the motor control method as described in the first aspect embodiment.

[0021] In a sixth aspect, embodiments of this application also provide a computer program product, including a computer program or computer instructions, the computer program or computer instructions being stored in a computer-readable storage medium, a processor of an electronic device reading the computer program or computer instructions from the computer-readable storage medium, and the processor executing the computer program or computer instructions to cause the electronic device to perform the motor control method as described in the first aspect embodiment.

[0022] The motor control method, controller, motor, refrigerator, medium, and program product provided in the embodiments of this application have at least the following beneficial effects: The embodiments of this application obtain motor parameters and generate an initial direct-axis current based on field weakening control. In addition to the DC component used to suppress energy backflow, the initial direct-axis current also contains an AC disturbance component of the target frequency introduced by DC bus voltage coupling. Therefore, the AC component of the target frequency is extracted, and minimizing the harmonic components of the same frequency in the quadrature-axis current is the direct objective. The phase of the target frequency disturbance component is optimized, and the phase angle is changed by optimizing the phase angle. The interference effect of the direct-axis current disturbance component transmitted to the quadrature-axis current is used to obtain the target AC component. The optimized target AC component is then combined with the DC component to generate the direct-axis reference current used to control the motor. Field weakening control effectively alleviates the energy backflow problem caused by insufficient voltage, ensuring system stability. Targeted phase optimization specifically suppresses the specific frequency harmonics of the quadrature-axis current caused by field weakening control itself. The combination of these two measures enables the system to maintain voltage balance when dealing with severe fluctuations in DC bus voltage, effectively suppressing energy backflow, reducing torque ripple, and improving the smoothness of motor operation.

[0023] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0024] The accompanying drawings are used to provide a further understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0025] The present application will be further described below with reference to the accompanying drawings and embodiments; Figure 1 This is a flowchart of a motor control method provided in one embodiment of this application; Figure 2 This is a flowchart illustrating the calculation of the target AC component according to an embodiment of this application; Figure 3 This is a flowchart illustrating the extraction of disturbance component information according to an embodiment of this application; Figure 4 This is a schematic diagram illustrating the extraction of disturbance component information provided in an embodiment of this application; Figure 5 This is a flowchart of phase angle iterative calculation provided in one embodiment of this application; Figure 6 This is a flowchart of phase angle iterative calculation provided in another embodiment of this application; Figure 7 This is a flowchart of phase angle iterative calculation provided in another embodiment of this application; Figure 8 This is a flowchart illustrating the calculation of the initial direct-axis current according to an embodiment of this application; Figure 9 This is a flowchart of motor control provided in one embodiment of this application; Figure 10 This is a flowchart of voltage coordinate transformation provided in one embodiment of this application; Figure 11 This is a flowchart of overmodulation provided in one embodiment of this application; Figure 12 This is a schematic diagram of overmodulation region division provided in one embodiment of this application; Figure 13 This is a flowchart of overmodulation vector adjustment provided in one embodiment of this application; Figure 14 This is a flowchart illustrating the specific process of the motor control method provided in the embodiments of this application; Figure 15 The figures show comparative experimental results of using the motor control method proposed in the embodiments of this application with and without the method used. Figure 16 This is a comparative experimental result diagram showing the results of using the motor control method proposed in the embodiments of this application, but without employing it. Figure 17 This is a comparative experimental result diagram showing the results of using the motor control method proposed in the embodiments of this application, but without employing it. Figure 18 This is a schematic diagram of a controller for performing a motor control method according to an embodiment of this application. Detailed Implementation

[0026] The embodiments of this application are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0027] In the description of this application, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., indicate the orientation or positional relationship according to the accompanying drawings. They are only for the convenience of describing 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.

[0028] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0029] In the description of this application, unless otherwise expressly defined, terms such as "setup," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this application in conjunction with the specific content of the technical solution.

[0030] In traditional thin-film capacitor-based motor drive systems, the DC bus voltage fluctuates due to the lack of electrolytic capacitor filtering, which in turn causes energy backflow, affecting system stability and reliability. In particular, the field weakening control method used in related technologies is affected by voltage fluctuations and cannot effectively suppress the AC component introduced by voltage fluctuations, resulting in ripple in the direct-axis current, which in turn causes torque pulsation and current harmonics.

[0031] Therefore, this application proposes a motor control method, controller, motor, refrigerator, medium, and program product that can maintain voltage balance, effectively suppress energy backflow, reduce torque pulsation, and improve the smoothness of motor operation.

[0032] The various embodiments of the refrigerator of this application will be further described below with reference to the accompanying drawings.

[0033] like Figure 1 As shown, Figure 1 This is a flowchart of a motor control method provided in one embodiment of this application. The motor control method includes, but is not limited to, steps S110 to S150.

[0034] Step 110: Obtain the DC bus voltage and quadrature axis current of the motor, and obtain the direct axis voltage and quadrature axis voltage; Step 120: Generate the initial direct-axis current by using field weakening control based on the direct-axis voltage, quadrature-axis voltage, and DC bus voltage; Step 130: Separate the target frequency disturbance component caused by DC bus voltage fluctuation and the DC component used for field weakening control from the initial direct-axis current; Step 140: With minimizing the harmonic components of the target frequency in the quadrature-axis current as the optimization objective, optimize the phase of the target frequency disturbance component to obtain the target AC component; Step 150: Synthesize the direct-axis reference current based on the target AC component and the DC component, and control the motor based on the direct-axis reference current.

[0035] Understandably, the first step is to acquire the motor's operating status information, such as DC bus voltage, direct-axis current, quadrature-axis current, direct-axis voltage, and quadrature-axis voltage. Specifically, sensors or sampling circuits can be used to measure the motor's DC bus voltage, direct-axis current, and quadrature-axis current in real time. Simultaneously, based on calculations of the current and motor parameters, the direct-axis voltage and quadrature-axis voltage can be obtained. For example, Hall effect sensors can be used to measure the current, and a voltage divider resistor network can be used to measure the voltage.

[0036] The direct-axis current and quadrature-axis current can be measured by the three-phase current of the motor, and then transformed from the three-phase stationary coordinate system to the two-phase stationary coordinate system using the Clarke transformation. Finally, the Park transformation is used to convert the two-phase stationary coordinate system current to the direct-axis and quadrature-axis currents in the two-phase rotating coordinate system. The direct-axis voltage and quadrature-axis voltage are the required voltages of the motor at the moment of operation. These can refer to the voltages calculated in the current loop of the previous control cycle and used as the reference voltage command for PWM modulation.

[0037] In motor drive systems using thin-film capacitors, the DC bus voltage fluctuates. When the back electromotive force (EMF) required for motor operation exceeds this fluctuating DC bus voltage, the inverter cannot provide sufficient voltage, causing energy to flow back from the motor side to the DC bus, leading to system instability. The stator voltage amplitude of a permanent magnet synchronous motor is related to the direct-axis current. By injecting a negative direct-axis current, the air gap magnetic field generated by the rotor permanent magnets can be weakened, thereby reducing the motor's back EMF while maintaining the same output torque, and thus reducing the required stator voltage amplitude. Therefore, the stator voltage amplitude is calculated in real-time using the current direct-axis and quadrature-axis voltages. Simultaneously, the calculated required voltage is compared with the DC bus voltage. When the required voltage approaches or exceeds the DC bus voltage, a risk of energy backflow is identified. A field-weakening control algorithm is then used to calculate and output a negative initial direct-axis current based on the difference between the required voltage and the DC bus voltage. This negative initial direct-axis current weakens the field, reducing the required voltage below the allowable limit of the DC bus voltage and mitigating the risk of energy backflow.

[0038] Next, the initial direct-axis current undergoes signal processing, such as filtering, to separate it into two parts: a DC component, which is required by field weakening control to suppress energy backflow; and an AC component, the target frequency disturbance component, which is a specific frequency AC ripple generated by the violently fluctuating DC bus voltage coupled into the control loop—a side effect of field weakening control. The direct objective is to minimize the harmonic components of the same frequency extracted from the quadrature-axis current. The phase of the target frequency disturbance component is optimized using methods such as least squares or gradient descent. By adjusting the phase of the target frequency, the interference effect transmitted from the target frequency disturbance component to the harmonic components of the same frequency extracted from the quadrature-axis current is minimized. Therefore, the optimized phase is calculated, and this is used to generate the target AC component, which has the same frequency as the original disturbance but with the optimized phase. Then, the target AC component is added to the DC component to obtain the required direct-axis reference current. This direct-axis reference current is used as a command input to the current loop. After coordinate transformation and space vector pulse width modulation, it can drive the motor. By actively separating and optimizing the harmonic side effects of specific frequency current generated by field weakening control, and adjusting the phase of the target frequency disturbance component, the interference transmission effect of the AC disturbance component on the quadrature axis current is minimized, thereby ensuring that energy backflow is suppressed while reducing the torque pulsation of the system and improving the smoothness of operation.

[0039] Understandably, in a permanent magnet synchronous motor drive system where the DC bus voltage fluctuates, the first step is to acquire the motor's DC bus voltage, direct-axis current, and quadrature-axis current in real time. For example, the DC bus voltage is acquired using a voltage sensor mounted on the DC bus, and the three-phase stator current is acquired using a current sensor. These are then converted to a two-phase rotating coordinate system to obtain the direct-axis and quadrature-axis currents. Next, based on the current direct-axis voltage, quadrature-axis voltage, and DC bus voltage, field weakening control is executed to ensure that the stator voltage amplitude does not exceed the allowable range of the DC bus voltage during high-speed operation. For instance, the field weakening controller can generate the initial direct-axis current based on the difference between the voltage limit and the actual stator voltage amplitude. However, due to the fluctuations in the DC bus voltage, the initial direct-axis current will still contain a second-harmonic disturbance component introduced by the voltage fluctuations, which is precisely the problem that needs to be addressed.

[0040] It should be noted that the field weakening control algorithm and field weakening controller used in this embodiment are technologies known to those skilled in the art. The improvement focus of this application embodiment is not on the field weakening control algorithm itself, but on the subsequent method for phase extraction and adaptive optimization of the disturbance component introduced by DC bus voltage fluctuation in the initial direct-axis current of the field weakening control output. This application embodiment extracts the target frequency (e.g., twice the grid voltage frequency) disturbance component caused by DC bus voltage fluctuation from the initial direct-axis current. For example, the target frequency disturbance component can be separated through a specific signal processing module.

[0041] Therefore, this method can effectively suppress ripple in the direct-axis current, reduce torque pulsation, improve system stability and reliability, and effectively solve the problem of energy backflow and harmonics caused by DC bus voltage fluctuations.

[0042] Understandably, in traditional motor drive systems, especially in scenarios using thin-film capacitors, the DC bus voltage fluctuates significantly. While field weakening control in related technologies can extend the motor's operating range, it has limitations in addressing direct-axis current ripple caused by voltage fluctuations, often leading to torque pulsation and additional current harmonics, thus affecting system performance. This application's embodiment, by introducing the extraction of the target frequency disturbance component in the initial direct-axis current and adaptive phase compensation, can identify the disturbance component caused by DC bus voltage fluctuations. With the goal of minimizing the target frequency harmonic component in the quadrature-axis current, it adaptively iteratively calculates the phase angle requiring compensation. Compared to traditional solutions relying solely on fixed parameters or simple field weakening control, this application's adaptive iterative mechanism dynamically adjusts the compensation strategy, ensuring that disturbances are suppressed under different operating conditions, thereby reducing ripple in the direct-axis current, decreasing torque pulsation, and ultimately improving the operational smoothness, system stability, and reliability of the motor drive system.

[0043] like Figure 2 As shown, Figure 2 This is a flowchart illustrating the calculation of the target AC component according to an embodiment of this application. The method includes, but is not limited to, steps S210 to S230.

[0044] Step S210: Extract the reference phase angle and reference amplitude information from the target frequency disturbance component in the initial direct-axis current; Step S220: With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, the reference phase angle is adaptively iteratively calculated to obtain the target phase angle; Step S230: Based on the reference amplitude information and the target phase angle, the target AC component is obtained by combining them.

[0045] Understandably, signal processing techniques such as quadrature demodulation can be used to separate the target frequency disturbance component caused by DC bus voltage fluctuations from the initial direct-axis current, and to measure the reference phase angle and reference amplitude information. The reference phase angle represents the position of the disturbance component on the time axis, and the reference amplitude information represents the intensity of the disturbance. It should be noted that the harmonic components of the quadrature-axis current refer to the sampled value of the actual quadrature-axis current flowing in the motor stator windings after measurement by the sensor, rather than the quadrature-axis reference current command generated internally by the controller. The target frequency disturbance component is a specific frequency AC component generated in the motor current or voltage under the influence of DC bus voltage fluctuations; for example, it could be twice the grid voltage frequency. Subsequently, based on a preset compensation model, the reference phase angle can be iteratively adjusted using optimization algorithms such as gradient descent until the harmonic components in the quadrature-axis current reach an acceptable level. Then, the extracted reference amplitude information is synthesized with the target phase angle obtained through adaptive iterative calculation to obtain the direct-axis reference current. The synthesized direct-axis reference current is then fed into the current loop controller, compared with the actual direct-axis current, and a direct-axis reference voltage is generated, which is then used to control the motor via the inverter. Therefore, by actively identifying and optimizing the disturbance phase in the field weakening control output, when this optimized phase is injected into the direct-axis current disturbance, a mutually canceling effect is achieved on the quadrature-axis side. This minimizes the specific frequency harmonics generated by the disturbance transmitted to the quadrature-axis current, thereby suppressing torque ripple and improving motor running smoothness.

[0046] The reference phase angle refers to the initial phase information of the target frequency disturbance component extracted from the initial direct-axis current, used for subsequent adaptive calculations; the reference amplitude information is the direct-axis amplitude of the target frequency disturbance component extracted from the initial direct-axis current. Based on this, to eliminate the influence of the target frequency disturbance component on the quadrature-axis current, and with the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, the reference phase angle is adaptively iteratively calculated. By continuously adjusting the phase angle and observing the changes in the harmonic components in the quadrature-axis current, an optimized target phase angle is found that can effectively suppress the harmonic components in the quadrature-axis current. Then, using the reference amplitude information and the optimized target phase angle, an optimized target AC component is synthesized. The target AC component is then combined with the DC component to obtain the corrected direct-axis reference current. The direct-axis reference current includes a compensation component for the direct-axis current output of the original field weakening control. This compensation component has the same amplitude as the target frequency disturbance component but with an adjusted phase. Specifically, the extracted reference amplitude information is combined with the target phase angle to generate a compensation signal that is out of phase with the disturbance component, and this signal is superimposed on the initial direct-axis current to form the direct-axis reference current. The direct-axis reference current is then sent to the motor's current loop controller to control the motor's operation.

[0047] like Figure 3 As shown, Figure 3 This is a flowchart illustrating the extraction of disturbance component information according to an embodiment of this application. The method includes, but is not limited to, steps S310 to S330.

[0048] Step S310: Perform bandpass filtering on the initial direct-axis current to extract the target frequency disturbance component caused by DC bus voltage fluctuation; Step S320: Multiply the target frequency disturbance component with the first local oscillator signal, perform low-pass filtering on the product result to obtain the phase error signal, and perform proportional-integral control on the phase error signal to obtain the reference phase angle; Step S330: Multiply the target frequency disturbance component with the second local oscillator signal, and perform low-pass filtering on the product to obtain the reference amplitude information.

[0049] Understandably, the initial direct-axis current is a mixed signal containing both DC and AC disturbance components. The DC component is the fundamental field-weakening current required to suppress energy backflow, while the AC disturbance component is a specific frequency AC signal caused by fluctuating DC bus voltage and coupled into the field-weakening control loop. Bandpass filtering of the initial direct-axis current can separate the target frequency disturbance component related to DC bus voltage fluctuations from the initial direct-axis current, while suppressing noise and interference at other frequencies, ensuring the purity of the signal in subsequent processing. Bandpass filtering can be implemented using digital bandpass filters, such as filters based on infinite impulse response or finite impulse response structures, achieved by designing a suitable center frequency and bandwidth in a digital signal processor or microcontroller; the center frequency can be set as the target frequency. Alternatively, analog bandpass filters can be used, such as filters based on RC or LC circuits, to preprocess the analog signal at the signal acquisition front end.

[0050] Reference Figure 4 , Figure 4 This is a specific schematic diagram of the disturbance component information extraction provided in the embodiments of this application, which extracts the initial direct-axis current. Bandpass filtering is performed in the input bandpass filter (BPF). The filtered AC disturbance component is then multiplied by the first local oscillator signal, which can be... ,in, Indicates the frequency of the power grid voltage. Indicates the target frequency. The reference phase angle is represented by a product-to-difference formula based on trigonometric functions. The product results in a DC component and a second harmonic AC component. The second harmonic AC component is filtered by a low-pass filter, and the resulting DC signal is the phase error signal. The amplitude and polarity of this signal reflect the deviation between the actual phase of the disturbance component and the phase of the local oscillator signal. This phase error signal is input to a proportional-integral (PI) controller. The PI controller continuously adjusts the phase of the local oscillator signal through closed-loop regulation until the phase difference signal is zero. At this point, the phase of the local oscillator signal is synchronized with the phase of the target frequency disturbance component, and this locked phase is the extracted reference phase angle. Simultaneously, the same AC disturbance component is multiplied by a second local oscillator signal. The second local oscillator signal is orthogonal to the first local oscillator signal, meaning the second local oscillator signal can be... Similarly, another DC signal can be obtained. The absolute value of this DC signal is the reference amplitude information of the target frequency disturbance component. This can characterize the magnitude of the disturbance. Therefore, by demodulating the AC signal of a single target frequency with a synchronous orthogonal signal, it is decomposed into two DC parameters to obtain the reference phase angle and reference amplitude information. In subsequent steps, the reference phase angle can be used for optimization and adjustment to solve the problem of current harmonics introduced by the previous field weakening control steps. This allows the present application to actively eliminate its own harmonics while suppressing energy backflow, thereby improving system stability.

[0051] The first local oscillation signal and the second local oscillation signal are orthogonal, and the first local oscillation signal and the second local oscillation signal are based on a reference phase angle. Update phase information. For example, if the first local oscillator signal is sinusoidal and the second local oscillator signal is cosine, when the two local oscillator signals are orthogonal, they can be used to detect the in-phase and quadrature components of the signal, respectively, thereby achieving independent phase and amplitude extraction. Update the phase information of the local oscillator signal according to the reference phase angle to ensure synchronization between the local oscillator and the input signal, guaranteeing the accuracy of the extraction. The local oscillator signal can be generated by a digital oscillator or a voltage-controlled oscillator. The phase is adjusted in real time by the reference phase angle output by the PI controller. That is, the reference phase angle output at each stage is fed back to the local oscillator, and the local oscillator adjusts the phase of the local oscillator signal based on the output reference phase angle to ensure that the local oscillator signal remains synchronized and orthogonal to the target frequency disturbance component.

[0052] like Figure 5 As shown, Figure 5 This is a flowchart illustrating phase angle iterative calculation according to an embodiment of this application. The method includes, but is not limited to, steps S410 to S430.

[0053] Step S410: Use the harmonic component of the target frequency in the quadrature-axis current as the instantaneous error signal, use the reference phase angle as the initial phase value in the iteration process, and generate a reference input signal that is synchronized with the target frequency disturbance component based on the reference phase angle; Step S420: Adjust the phase value based on the product of the instantaneous error signal and the reference input signal and the preset step size factor; Step S430: When the mean square value of the instantaneous error signal satisfies the convergence condition, the current phase value is taken as the target phase angle.

[0054] The instantaneous error signal refers to the harmonic components in the quadrature-axis current related to the target frequency, reflecting the harmonics generated in the quadrature axis due to the direct-axis disturbance that need to be minimized. The harmonic components of the target frequency can be extracted from the quadrature-axis current using various signal processing techniques. For example, bandpass filters or adaptive notch filters can be used to isolate harmonic components of specific frequencies, or frequency domain analysis methods such as Fourier transform can be used to identify and extract them. The reference phase angle is the initial phase information extracted from the initial direct-axis current, providing a starting value for the adaptive iterative process. This initial phase value allows the iterative process to start from a position relatively close to the optimal solution, thereby accelerating convergence and improving iterative efficiency. The reference input signal is a signal with the same frequency and controllable phase as the target frequency disturbance component. The reference input signal is generated based on the reference phase angle, for example, by using a digital oscillator or phase-locked loop circuit to generate a sine or cosine signal synchronized with the target frequency disturbance component.

[0055] During the iteration process, the reference input signal and the instantaneous error signal are multiplied to determine the direction and magnitude of the phase adjustment. Multiplying the instantaneous error signal by the reference input signal yields a quantity indicating the current phase deviation direction. For example, if the instantaneous error signal is in phase with the reference input signal, it indicates that the current phase needs adjustment in a certain direction; if it is out of phase, it needs adjustment in the opposite direction. Multiplying the product of the instantaneous error signal and the reference input signal by a preset step size factor yields the phase adjustment amount for this iteration, and the phase value is updated in the direction of reducing the error in each iteration. The preset step size factor determines the magnitude of each adjustment, used to balance convergence speed and stability. Specifically, adaptive filtering principles such as gradient descent or least mean square algorithm can be used to adjust the phase value.

[0056] The mean square value of the instantaneous error signal can be used as an indicator of its energy. When the mean square value is sufficiently small or its change tends to be stable, it indicates that the iterative process has converged, meaning the current phase value is close enough to the optimal solution. The convergence condition can be set as the mean square value being less than a preset threshold, or the change in the mean square value being less than a preset threshold in consecutive iterations. When the mean square value meets the convergence condition, the current phase value is determined as the final target phase angle.

[0057] Understandably, the following steps can be used when adaptively iteratively calculating the reference phase angle: First, a digital bandpass filter is used to extract the harmonic components of the target frequency in the quadrature-axis current, which serve as the instantaneous error signal. The center frequency of this bandpass filter is set to the target frequency, and the bandwidth is adjusted according to the actual application requirements. Second, the previously obtained reference phase angle is used as the initial phase value for the iteration. Then, a digitally controlled oscillator is used to generate a sinusoidal reference input signal synchronized with the target frequency disturbance component based on the current phase value. In each iteration, the instantaneous error signal is multiplied by the sinusoidal reference input signal to obtain a product. This product is multiplied by a preset step size factor (e.g., a small constant between 0.001 and 0.01) as the phase correction amount for this iteration. This correction amount is then added to the current phase value to obtain the updated phase value. Repeat the above process until the mean square value of the instantaneous error signal is less than a preset threshold, such as 0.001, for 100 consecutive iterations, or the change in the mean square value is less than another preset threshold, such as 0.0001, for 50 consecutive iterations. When any one of these convergence conditions is met, the current phase value is determined as the target phase angle.

[0058] Since the fluctuations in DC bus voltage are continuous, the disturbance characteristics may change slowly, and the iterative process continues to run, tracking and adjusting the phase in real time to adapt to changes in system state. Therefore, by dynamically and adaptively searching for and locking a suitable phase angle, when the direct-axis current disturbance is synthesized according to this target phase angle, the harmonics of the same frequency induced by the direct-axis current in the quadrature-axis current can be offset to the greatest extent, thereby actively suppressing torque pulsation and improving the smoothness of motor operation.

[0059] like Figure 6 As shown, Figure 6 This is a flowchart of phase angle iterative calculation provided in another embodiment of this application. The method includes, but is not limited to, steps S510 to S520.

[0060] Step S510: With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, an adaptive iterative algorithm is used to calculate the phase correction amount; Step S520: Superimpose the reference phase angle and the phase correction amount to obtain the target phase angle.

[0061] Understandably, adaptive iterative algorithms do not rely on precise system models. They can adjust their parameters based on real-time feedback signals, which are the harmonic components of the target frequency in the quadrature-axis current monitored in real time, enabling the evaluation of the current phase adjustment effect. For example, based on the gradient descent principle, in each iteration cycle, the gradient of the energy or amplitude of the target frequency harmonic component in the quadrature-axis current relative to the phase correction can be calculated, and the phase correction can be adjusted in the opposite direction of the gradient. That is, the adjustment direction of the phase correction always points in the direction that can reduce the harmonic components. The magnitude of the phase correction can be determined by multiplying the harmonic component of the target frequency by the reference input signal generated based on the reference phase angle, and then multiplying by a preset step size factor. The calculated phase correction is superimposed on the reference phase angle as the starting point. This superposition process is continuously iterated. In each iteration, a new reference phase angle is used to synthesize the direct-axis current, and the change of the quadrature-axis harmonics is observed to calculate the next phase correction. When the harmonic components of the quadrature-axis current are suppressed to the point that the convergence condition is met, the iterative process stabilizes, and the obtained reference phase angle is the target phase angle. The reference phase angle provides a relatively accurate preliminary phase estimate, while the phase correction is further adjusted on this basis to compensate for various uncertainties, thereby obtaining a more accurate and optimized target phase angle. Compared with the simple reference phase angle, this target phase angle can more accurately reflect the phase information required to eliminate the target frequency harmonic components in the quadrature axis current, thus more effectively suppressing the harmonic components in the quadrature axis current. Therefore, based on this optimized target phase angle and reference amplitude information, the target AC component is synthesized, and then the target AC component and DC component are combined to synthesize the direct axis reference current to control the motor. This can effectively make up for the shortcomings that may exist by relying solely on the reference phase angle, ensuring that the harmonic components in the quadrature axis current can be continuously and effectively suppressed in a dynamically changing environment.

[0062] Understandably, after obtaining the reference phase angle, an adaptive iterative algorithm based on the least mean square principle can be used to calculate the phase correction. First, the initial value of the phase correction is set to zero. Then, the harmonic components of the target frequency in the quadrature-axis current are continuously detected and used as the instantaneous error signal. Simultaneously, a reference input signal synchronized with the target frequency disturbance component, such as a sine or cosine signal, is generated based on the current reference phase angle. In each iteration cycle, this reference input signal is multiplied by the instantaneous error signal to obtain a direction indication. This direction indication is multiplied by a preset adjustment step size to obtain the correction increment. Subsequently, this correction increment is superimposed on the current phase correction, thereby updating the phase correction. This process continues until the mean square value of the instantaneous error signal meets a preset convergence condition, such as being less than a first preset threshold, or the change in the mean square value in consecutive iterations being less than a second preset threshold. When the convergence condition is met, the current phase correction is determined as the desired phase correction. Finally, the target phase angle is obtained by simply adding this determined phase correction amount to the previously extracted reference phase angle using algebraic summation. Therefore, based on the obtained reference phase angle, an adaptive iterative algorithm is further introduced to calculate the phase correction amount, and the target phase angle is obtained by superposition. This can dynamically and accurately compensate for the phase error caused by disturbances, thereby enabling the synthesized direct-axis reference current to more accurately cancel the target frequency harmonic components caused by DC bus voltage fluctuations in the quadrature-axis current. This effectively improves the stability of motor control, effectively suppresses torque pulsation during motor operation, and enhances the reliability of system operation.

[0063] like Figure 7 As shown, Figure 7 This is a flowchart of phase angle iterative calculation provided in another embodiment of this application. The method includes, but is not limited to, steps S610 to S630.

[0064] Step S610: Set the initial value of the phase correction to zero, generate a reference input signal synchronized with the target frequency disturbance component based on the reference phase angle, and use the harmonic component of the target frequency in the quadrature axis current as the instantaneous error signal; Step S620: When the mean square value of the instantaneous error signal does not meet the convergence condition, the reference input signal is multiplied with the instantaneous error signal to obtain the direction indication, the direction indication is multiplied with the preset adjustment step size to obtain the correction increment, and the correction increment is added to the current value of the phase correction to obtain the updated phase correction. Step S630: When the mean square value of the instantaneous error signal satisfies the convergence condition, output the phase correction amount.

[0065] Understandably, the initial value of the phase correction is set to zero, serving as the starting point for the adaptive iterative process. The reference input signal is used to provide a reference standard that is in phase or orthogonal to the target frequency perturbation component; for example, generating a... The signal can be referenced to detect the target frequency component in the instantaneous error signal during subsequent iterations.

[0066] The convergence condition determines whether the iterative process has reached the expected stable state. The mean square value of the instantaneous error signal is used as a measure of the error magnitude; when the mean square value is less than a preset threshold, the current iteration is considered converged. Alternatively, the convergence condition can be that the change in phase correction during multiple iterations is less than another preset threshold. The direction indicator is obtained by multiplying the reference input signal and the instantaneous error signal in each iteration cycle, and is used to determine the adjustment direction of the phase correction. The direction indicator is proportional to the instantaneous gradient estimate of the phase angle relative to the mean square value of the instantaneous error signal. The sign of the direction indicator indicates which direction the phase should be adjusted to reduce the error. Then, the direction indicator is multiplied by a preset adjustment step size to obtain the correction increment. This calculated correction increment is then added to the current value of the phase correction to obtain a new phase correction, completing one iteration update. This iterative update is continued until the mean square value of the instantaneous error signal meets the preset convergence condition. The current value of the phase correction is considered to have converged to the target value. Adding this phase correction to the reference phase angle yields the target phase angle. Therefore, by real-time gradient estimation and iteration, a suitable phase compensation value can be automatically found, dynamically tracking and compensating for the target frequency disturbance caused by DC bus voltage fluctuations. When the phase of the direct-axis current disturbance is corrected according to this compensation, the harmonics of the same frequency induced by the disturbance in the quadrature-axis current can be effectively canceled. This achieves dynamic suppression of specific harmonics transmitted to the quadrature-axis caused by voltage fluctuations, solving the harmonic problem that is difficult to handle with related technologies.

[0067] It is understandable that convergence criteria refer to a set of rules used in iterative algorithms to determine whether the algorithm has reached a predetermined accuracy or meets the stopping requirements. Convergence criteria can be set based on various factors such as the magnitude of the error signal, the amount of parameter change, and the number of iterations. The mean square value of the instantaneous error signal is the average of the squares of the instantaneous error signal over a period of time. This value reflects the overall magnitude and fluctuation of the error signal. The mean square value of the instantaneous error signal can be obtained by squaring the instantaneous error signal and then performing a moving average or exponentially weighted average. The first preset threshold is a pre-set value used to compare with the mean square value of the instantaneous error signal. When the mean square value of the instantaneous error signal is lower than the first preset threshold, it indicates that the error is small enough, and the iterative process can be considered converged.

[0068] The second preset threshold is another pre-set value used to compare with the changes in key parameters during the iteration process. The change refers to the difference in the mean square value of the error signal between two or more consecutive iterations during the iteration process; the magnitude of this difference reflects the convergence speed and stability of the iteration process. The change can be obtained by calculating the absolute or relative difference between the current value and the previous value. When this change is less than the second preset threshold for a preset number of consecutive iterations, it indicates that the iteration result has stabilized, and even if the mean square value of the instantaneous error signal has not yet reached the first preset threshold, the iteration process can be considered to have converged. Setting the second preset threshold prevents the iteration process from failing to terminate due to small fluctuations near the convergence point, improving the robustness of the algorithm.

[0069] Specifically, in the adaptive iterative calculation of the target phase angle or phase correction, the convergence condition can be set as follows: First, continuously calculate the mean square value of the instantaneous error signal. For example, a first preset threshold can be set to 0.001. When the mean square value of the instantaneous error signal is less than 0.001 for 5 consecutive iterations, the iteration is considered converged. Alternatively, the change in the mean square value of the instantaneous error signal in continuous iterations can be monitored. For example, a preset number of iterations can be set to 10, and a second preset threshold can be set to 0.0001. If, in 10 consecutive iterations, the change in the mean square value of the instantaneous error signal in each iteration (i.e., the absolute difference between the current mean square value and the previous mean square value) is less than 0.0001, the iteration is also considered converged. These two conditions can be used independently or in combination to adapt to different control precision and system dynamic characteristics requirements. For example, the first condition can be prioritized; if it is not met, the second condition can be used.

[0070] like Figure 8 As shown, Figure 8 This is a flowchart illustrating the initial direct-axis current calculation according to an embodiment of this application. The method includes, but is not limited to, steps S710 to S730.

[0071] Step S710: Determine the stator voltage amplitude based on the direct-axis voltage and quadrature-axis voltage, and determine the voltage limit based on the DC bus voltage; Step S720: Compare the stator voltage amplitude with the voltage limit to obtain the voltage error signal; Step S730: Input the voltage error signal to the quasi-proportional-integral-resonant controller, and perform proportional operation, integral operation and resonant operation centered on the target frequency on the voltage error signal in parallel to generate the initial direct-axis current.

[0072] The direct-axis voltage and quadrature-axis voltage are the voltage components of the motor in a two-phase rotating coordinate system, determining the stator voltage vector. Specifically, they can be obtained by performing coordinate transformation on the three-phase voltages. The stator voltage amplitude refers to the magnitude of the voltage vector actually applied to the stator windings, calculated as the square root of the sum of the squares of the direct-axis and quadrature-axis voltages. It reflects the motor's current operating state and voltage requirements. The voltage limit, based on the current DC bus voltage, determines the maximum effective voltage amplitude that the motor inverter can output at the current moment. In motor drive systems using film capacitors, the voltage limit fluctuates due to DC bus voltage fluctuations, ensuring the motor operates within a safe and efficient range. The voltage error signal is the difference between the stator voltage amplitude and the voltage limit (voltage limit minus stator voltage amplitude). It reflects the gap between the motor's current voltage requirements and the inverter's maximum output capacity. When the stator voltage amplitude approaches or exceeds the voltage limit, it indicates a risk of voltage saturation, which could trigger energy backflow.

[0073] The voltage error signal is input to a quasi-proportional-integral-resonant controller. Building upon the traditional proportional-integral processing, a resonant processing layer is added, enabling simultaneous tracking or suppression of DC components and AC components at specific frequencies. This controller performs three operations in parallel on the voltage error signal: proportional operation provides a fast transient response, immediately generating control action based on the error magnitude; integral operation eliminates steady-state errors, particularly compensating for DC bias errors introduced into the control loop by DC bus voltage fluctuations; and the newly added resonant processing provides high gain at the target frequency, effectively suppressing the AC error component at that frequency—a capability difficult to achieve with traditional proportional-integral controllers due to their limited gain at the target frequency. Since the initial direct-axis current is the direct-axis current component generated by the field-weakening control element based on the voltage error signal, adjusting the initial direct-axis current can change the motor's flux linkage, thereby reducing the back electromotive force during high-speed operation. The quasi-proportional-integral-resonant controller combines the outputs of the three operations to generate an initial direct-axis current. This initial direct-axis current is used to inject current into the motor to weaken the magnetic field, thereby reducing the stator voltage amplitude to within the voltage limit and avoiding the instability risk that may occur when using a proportional-integral controller.

[0074] Understandably, the direct-axis and quadrature-axis voltages can be obtained by sampling the three-phase output voltages of the inverter and performing a Parker transformation. The DC bus voltage is measured in real time using a dedicated voltage sensor. The stator voltage amplitude can be calculated using the formula... Calculations are performed, in which, Indicates the stator voltage amplitude. Represents direct-axis voltage. This represents the quadrature-axis voltage. The voltage limit can be determined based on the inverter's modulation method. For example, if space vector pulse width modulation is used, the voltage limit can be set to... ,in This is the DC bus voltage. The voltage error signal is... A quasi-proportional-integral-resonant controller can be implemented using a software algorithm, where the output of the proportional element is... The output of the integral stage is The output of the resonant circuit is ,in It is a voltage error signal. It is the target frequency. , , These are proportional gain, integral gain, and resonant gain, respectively. It refers to the phase angle. These operations are performed in parallel, and the superimposed outputs serve as the command to generate the initial direct-axis current. For example, in field weakening control, when the stator voltage amplitude approaches the voltage limit, the voltage error signal increases. The quasi-proportional-integral-resonant controller generates a negative initial direct-axis current to weaken the motor's magnetic field, thereby reducing the back electromotive force and enabling the motor to operate at higher speeds.

[0075] Therefore, by dynamically monitoring the motor voltage demand and system power supply capacity, and generating an initial direct-axis current through a quasi-proportional-integral-resonant controller when the voltage is about to saturate, the motor magnetic field is actively weakened, thereby reducing the stator voltage demand and preventing and suppressing energy backflow from the root. Furthermore, by effectively suppressing DC bias and major AC disturbances, the quality of the output initial direct-axis current is higher, enabling smoother current loop tracking in subsequent steps. In addition to the DC component required for field weakening, the generated initial direct-axis current also includes an AC disturbance component of the target frequency coupled in by DC bus voltage fluctuations. This disturbance component is precisely the target that needs to be analyzed and optimized in subsequent steps for extracting the reference phase angle and adaptive iterative calculations. In other words, while solving the voltage problem, the signal required for subsequent optimization steps is also generated.

[0076] like Figure 9 As shown, Figure 9 This is a flowchart of motor control provided in one embodiment of this application. The method includes, but is not limited to, steps S810 to S840.

[0077] Step S810: Obtain the reference angular velocity and the actual angular velocity of the motor, input the difference between the reference angular velocity and the actual angular velocity to the proportional-integral controller, and output the quadrature-axis reference current; Step S820: Perform current loop control based on the direct-axis reference current and the quadrature-axis reference current to generate the direct-axis reference voltage and the quadrature-axis reference voltage; Step S830: Perform coordinate transformation on the direct-axis reference voltage and the quadrature-axis reference voltage to obtain the two-phase static voltage; Step S840: Generate a pulse width modulation signal based on the two-phase static voltage, and control the motor based on the pulse width modulation signal.

[0078] The reference angular velocity can be set by upper-level commands or the controller, while the actual angular velocity can be estimated by a speed observer based on signals such as motor phase current and voltage. The difference between the reference and actual angular velocities is calculated and input to the proportional-integral (PI) controller. The PPI controller processes this difference and outputs a quadrature-axis reference current. The initial quadrature-axis current corresponds to the electromagnetic torque required by the motor, and is used to adjust the actual angular velocity of the motor to approximate the reference angular velocity. Furthermore, the PPI controller can be implemented using software algorithms within a digital signal processor or microcontroller. The parameters of the PPI controller need to be set according to the motor characteristics and control requirements.

[0079] Specifically, the direct-axis reference current and quadrature-axis reference current are used as the setpoints for the current loop. The current loop typically employs two independent proportional-integral (PI) controllers to control the direct-axis and quadrature-axis currents respectively. By comparing the difference between the reference current and the actual detected direct-axis and quadrature-axis currents of the motor, the PPI controllers output the corresponding direct-axis and quadrature-axis reference voltages. That is, in a two-phase rotating coordinate system, the direct-axis current error is obtained by subtracting the direct-axis reference current from the quadrature-axis reference current, and the quadrature-axis current error is obtained by subtracting the quadrature-axis reference current from the quadrature-axis reference current. These errors are then input to the PPI controllers, which output the direct-axis and quadrature-axis reference voltages. Next, the direct-axis and quadrature-axis reference voltages in the two-phase rotating coordinate system, combined with the actual angular velocity of the motor, are transformed to a two-phase stationary coordinate system using the inverse Parker transformation to obtain the two-phase stationary voltages. Then, space vector pulse width modulation is applied to the two-phase static voltage to calculate the pulse width modulation signal that controls the on / off state of the six switching transistors of the three-phase inverter. The pulse width modulation signal is then sent to the three-phase inverter, which generates the required three-phase AC voltage to drive the permanent magnet synchronous motor.

[0080] Therefore, based on the direct-axis reference current generated by field weakening control, the difference between the motor's reference angular velocity and actual angular velocity is obtained through a speed loop and input to a proportional-integral controller to output an initial quadrature-axis current, thereby achieving effective regulation of the motor speed. Subsequently, current loop control is performed by combining the direct-axis and quadrature-axis reference currents to generate direct-axis and quadrature-axis reference voltages, ensuring motor current tracking. By performing coordinate transformation on these voltages and generating pulse-width modulation signals, the motor is driven, enabling the motor to not only respond to the direct-axis reference current generated by field weakening control to suppress DC bus voltage fluctuations, but also to operate stably at the desired speed or torque, effectively improving the dynamic response performance and operational stability of the motor control system.

[0081] like Figure 10 As shown, Figure 10 This is a flowchart of voltage coordinate transformation provided in one embodiment of this application. The method includes, but is not limited to, steps S910 to S920.

[0082] Step S910: When the quadrature axis reference voltage is less than zero, set the quadrature axis reference voltage limit to a preset positive voltage. Step S920: Perform Parker inverse transformation on the direct-axis reference voltage and the quadrature-axis reference voltage after the limit to obtain the two-phase stationary voltage in the two-phase stationary coordinate system.

[0083] In motor control, the quadrature-axis reference voltage is typically related to torque control. When the quadrature-axis reference voltage is negative, it indicates that the motor is in a generating state or requires reverse torque. Directly using a negative value may lead to control instability or low efficiency. Therefore, it is necessary to judge the magnitude of the quadrature-axis reference voltage in real time. If the quadrature-axis reference voltage is less than zero, it is limited to a preset positive voltage to avoid negative values. This ensures that subsequent coordinate transformations and pulse width modulation signal generation are performed within a controllable and stable range, especially when it is necessary to avoid negative voltage output or optimize control performance in a specific region. If the quadrature-axis reference voltage is greater than or equal to zero, it remains unchanged. Specifically, the sign of the quadrature-axis reference voltage can be determined by a comparator circuit or software logic. When a quadrature-axis reference voltage less than zero is detected, it is assigned a preset fixed voltage value greater than zero, such as a small positive number or a minimum allowable positive voltage calculated based on system characteristics. Another implementation method is to use a saturation function or limiter. When the quadrature-axis reference voltage is below zero, the output of the quadrature-axis reference voltage is clamped to zero or a small positive value. This preset positive voltage can be a constant or a variable that is dynamically adjusted according to the current operating state (such as DC bus voltage, motor speed, etc.) to provide more flexible control. Then, the voltage components in the two-phase rotating coordinate system, i.e., the direct-axis reference voltage and the limited quadrature-axis reference voltage, are subjected to an inverse Parker transform to transform them into the two-phase stationary coordinate system, obtaining the two-phase stationary voltage in the two-phase stationary coordinate system, which is used for subsequent space vector pulse width modulation to generate pulse width modulation signals.

[0084] In motor drive systems employing thin-film capacitors, significant fluctuations in the DC bus voltage can cause the control loop to fail to meet stability conditions in traditional field-weakening control algorithms when the fluctuating quadrature-axis reference voltage becomes negative, leading to algorithm instability or even system oscillation. Therefore, limiting the negative quadrature-axis reference voltage to a small positive value blocks feedback paths that could cause instability, ensuring that the quadrature-axis reference voltage remains within a safe threshold range during the Parker inverse transform and subsequent stages, thus avoiding instability caused by a negative quadrature-axis reference voltage.

[0085] like Figure 11 As shown, Figure 11 This is a flowchart of overmodulation provided in one embodiment of this application. The method includes, but is not limited to, steps S1010 to S1030.

[0086] Step S1010: Generate a composite voltage vector based on the two-phase static voltage, and obtain the modulation index based on the ratio of the amplitude of the composite voltage vector to the DC bus voltage; Step S1020: Determine the modulation region where the synthesized voltage vector is located based on the modulation coefficient, and adjust the synthesized voltage vector according to the modulation region to obtain the target voltage vector so that the target voltage vector meets the inverter output voltage limit of the motor. Step S1030: Generate a pulse width modulation signal by space vector pulse width modulation based on the target voltage vector.

[0087] Understandably, combining the voltage components in the two-phase stationary coordinate system into a single voltage vector allows for a direct representation of the desired voltage amplitude and phase applied to the motor stator windings. Next, the modulation index is obtained based on the ratio of the amplitude of the composite voltage vector to the DC bus voltage. This modulation index reflects the relationship between the desired output voltage and the inverter's maximum possible output voltage, serving as a key indicator for assessing whether the current voltage demand is within the inverter's linear operating range. The calculated modulation index determines whether the current motor control system is operating in the linear modulation region or the over-modulation region.

[0088] Understandably, the linear modulation region refers to a region where the modulation index is within a preset range, allowing the inverter to accurately output the desired voltage vector. The overmodulation region, on the other hand, refers to a region where the modulation index exceeds the linear modulation range. In this case, the inverter cannot fully output the desired voltage vector, requiring a corrective control strategy. When the voltage demand represented by the synthesized voltage vector exceeds the inverter's output capacity, the vector needs to be corrected. Specifically, this can involve limiting or reducing the voltage vector amplitude and fine-tuning the phase angle to ensure the output voltage vector remains within the range allowed by the inverter hardware.

[0089] Reference Figure 12 , Figure 12 This is a schematic diagram of the overmodulation region division provided in an embodiment of this application. For example... Figure 12 As shown, Figure 12In the diagram, the hexagon represents the maximum voltage vector output range of the inverter in stationary coordinates, while the inscribed circle of the hexagon represents the boundary between the linear modulation region and the overmodulation region. When the modulation index is greater than zero and less than or equal to the first preset index, the synthesized voltage vector is within the inscribed circle of the hexagon, i.e., the synthesized voltage vector is in the linear modulation region, and the inverter can accurately output the desired voltage vector. At this time, standard space vector pulse width modulation can be directly performed without correcting the synthesized voltage vector. The first preset index represents the maximum modulation index in the linear modulation region, specifically 0.9069. When the modulation index is less than 1 and greater than the first preset index, the synthesized voltage vector exceeds the inscribed circle but is still within the hexagon, and the synthesized voltage vector is in the overmodulation region. At this time, the inverter cannot fully output the desired voltage vector. The phase angle of the synthesized voltage vector can be kept unchanged, but the amplitude of the synthesized voltage vector can be reduced. Alternatively, the amplitude and phase angle of the synthesized voltage vector can be adjusted simultaneously so that the endpoint of the synthesized voltage vector falls on the side of the hexagon. For example, when the target voltage vector is in the overmodulation region, the amplitude of the synthesized voltage vector can be limited to the maximum effective output voltage amplitude that the inverter can provide, thus obtaining a target voltage vector that meets the limit. Then, using space vector pulse width modulation technology, the adjusted target voltage vector is converted into a pulse signal for controlling the switching devices of the inverter, and then the motor is controlled by the pulse signal.

[0090] Because the DC bus voltage fluctuates significantly at twice the grid voltage frequency, its value is low during troughs, causing a severe drop in the voltage limit corresponding to the traditional linear modulation zone. In this case, even if the motor only requires a moderate voltage, the modulation index may exceed the first preset index, falling into the over-modulation zone. Therefore, when generating pulse width modulation signals based on the two-phase stationary voltage, an over-modulation algorithm is used to effectively identify and handle situations where the voltage demand exceeds the inverter's output capacity. By introducing the modulation index and modulation zone judgment, and making necessary adjustments to the synthesized voltage vector, the effective output voltage range of the inverter is dynamically expanded under DC bus voltage fluctuation conditions, breaking through the traditional linear modulation zone. This allows the voltage demand of the motor to be met as much as possible when the voltage supply is insufficient, while ensuring that the voltage vector used for space vector pulse width modulation is always within the safe operating range of the motor inverter. This avoids problems such as motor control system instability and output voltage waveform distortion caused by voltage over-limit, enabling the motor to operate stably and efficiently over a wider operating range, thereby improving the reliability and performance of motor control.

[0091] like Figure 13 As shown, Figure 13 This is a flowchart of overmodulation vector adjustment provided in one embodiment of this application. The method includes, but is not limited to, step S1110 or step S1120.

[0092] Step S1110: When the synthesized voltage vector is in the linear modulation region, the synthesized voltage vector is used as the target voltage vector; or, Step S1120: When the synthesized voltage vector is in the overmodulation region, the amplitude and / or phase angle of the synthesized voltage vector are corrected to obtain the target voltage vector.

[0093] As can be understood, the modulation region refers to the different operating ranges defined in space vector pulse width modulation (SVM) technology based on the ratio of the amplitude of the synthesized voltage vector to the DC bus voltage (i.e., the modulation index). Different modulation regions determine the different characteristics of the inverter's output voltage and different control strategies. The linear modulation region refers to the range where the amplitude of the synthesized voltage vector is within the range where the inverter can output linearly. Within this region, the inverter can accurately synthesize the required voltage vector, and the harmonic content of the output voltage is low. For example... Figure 12 As shown, generally, when the modulation index is greater than zero and less than or equal to the first preset index, the synthesized voltage vector can be considered to be in the linear modulation region. The overmodulation region refers to the region where the amplitude of the synthesized voltage vector exceeds the range of the inverter's linear output. This region may occur when the motor requires a higher output voltage or when the DC bus voltage is low. For example, when the modulation index is greater than the first preset index, it can be considered to be in the overmodulation region. Based on the magnitude of the modulation index, it can be further subdivided into a first overmodulation region and a second overmodulation region. Within this region, if the synthesized voltage vector is not properly corrected, the inverter will not be able to accurately output the required voltage, potentially leading to output voltage waveform distortion or even motor control instability. Specifically, when the modulation index is greater than zero and less than or equal to the first preset index, the synthesized voltage vector is within the inscribed circle of the hexagon, i.e., in the linear modulation region. When the modulation index is greater than the first preset index and less than or equal to the second preset index, the endpoints of the synthesized voltage vector extend beyond the inscribed circle but remain within the hexagon, indicating the first overmodulation region. Specifically, when the modulation index reaches the second preset index, the endpoint of the synthesized voltage vector has already fallen on the boundary of the hexagon. If the modulation index continues to increase, the endpoint of the vector will exceed the hexagon. When the modulation index is greater than the second preset index and less than or equal to 1, the endpoint of the synthesized voltage vector has exceeded the boundary of the hexagon, and at this time it is in the second overmodulation region.

[0094] Specifically, when the synthesized voltage vector is in the linear modulation region, it is used as the target voltage vector. This indicates that within the normal operating range where the inverter can output linearly and without distortion, no additional correction is needed for the synthesized voltage vector. At this time, the synthesized voltage vector itself satisfies the inverter's output voltage limit and can be directly used to generate a pulse width modulation signal, thereby ensuring that the motor receives accurate and low-harmonic power. However, when the synthesized voltage vector is in the overmodulation region, its amplitude and / or phase angle are corrected to obtain the target voltage vector. Overmodulation occurs when the amplitude of the synthesized voltage vector exceeds the inverter's linear output capability. To avoid severe output voltage distortion and maximize voltage utilization, the synthesized voltage vector needs correction. In the first overmodulation region, the phase angle of the synthesized voltage vector is kept constant, and its amplitude is limited, clamping it to the maximum amplitude that the inverter can output. For example, the amplitude of the synthesized voltage vector can be limited to a certain percentage of the DC bus voltage. In the second overmodulation region, while limiting the amplitude, the phase angle of the synthesized voltage vector is adjusted to keep the fundamental component of the output voltage as close as possible to the desired value, and to optimize the harmonic characteristics, even with amplitude limitations. By correcting the synthesized voltage vector, it is ensured that the amplitude of the obtained target voltage vector never exceeds the inverter's maximum output voltage limit determined by the instantaneous DC bus voltage, thereby satisfying the inverter's physical output constraints.

[0095] This application embodiment generates a composite voltage vector based on the two-phase static voltage and calculates its modulation coefficient to determine the modulation region. Based on this, differentiated processing strategies are adopted for different modulation regions. Specifically, when the composite voltage vector is in the linear modulation region, it indicates that the inverter can output the voltage vector completely and accurately. Therefore, this composite voltage vector is directly used as the target voltage vector without any correction, thus ensuring accurate control and low-harmonic operation of the motor within its normal operating range. However, when the composite voltage vector is in the overmodulation region, it means that the required voltage vector amplitude exceeds the inverter's linear output capability. In this case, to avoid severe output voltage distortion and fully utilize the inverter's voltage output capability, this application embodiment corrects the amplitude and / or phase angle of the composite voltage vector, adjusting it to the maximum output voltage range of the inverter while preserving its fundamental component characteristics as much as possible, thereby generating a target voltage vector that meets the output voltage limits of the motor inverter. By adaptively adjusting the synthesized voltage vector according to the modulation region, the embodiments of this application ensure that the motor control system can still operate stably and efficiently over a wide operating range, including high-speed or heavy-load conditions that require high voltage output, effectively avoiding the problems of output voltage distortion and control performance degradation caused by overmodulation.

[0096] By employing the aforementioned technical solution, and through targeted adjustments to the synthesized voltage vector based on its modulation region, the problem of inverters potentially entering over-modulation regions during motor control, leading to output voltage distortion and reduced control performance when the motor requires high voltage output, can be effectively solved. Specifically, within the linear modulation region, the synthesized voltage vector is directly used as the target voltage vector, ensuring control accuracy and low harmonic characteristics of the output voltage. In the over-modulation region, by correcting the amplitude and / or phase angle of the synthesized voltage vector, the DC bus voltage can be utilized to the maximum extent, improving the inverter's voltage utilization rate. Simultaneously, the harmonic content of the output voltage is suppressed, avoiding problems such as increased motor vibration, noise, and reduced efficiency caused by over-modulation. This allows the motor control system to maintain stable and efficient performance over a wider operating range, especially under extreme conditions such as high speed or heavy load, still providing reliable voltage output, thereby enhancing the robustness and dynamic response capability of the entire motor drive system.

[0097] like Figure 14 As shown, Figure 14 This is a flowchart illustrating the motor control method provided in this application embodiment. It can be understood that the DC bus voltage of the motor is first acquired in real time. quadrature axis current Direct-axis voltage and quadrature axis voltage ; Utilizing direct-axis voltage and quadrature axis voltage Calculate the stator voltage amplitude And due to fluctuating DC bus voltage Determined voltage limit A difference comparison is performed to generate a voltage error signal, which is then input to a quasi-proportional-integral-resonant (PIR) controller. The PIR controller outputs an initial direct-axis current. The current is then limited by a limiter to actively weaken the motor's magnetic field and reduce the stator voltage amplitude. The initial direct-axis current output contains AC disturbances caused by DC bus voltage fluctuations, which can lead to harmonics on the quadrature axis, causing torque pulsation. Therefore, the limited initial direct-axis current undergoes signal processing, separating it into two parts: one is the DC component. The other part is the target frequency perturbation component. Combined with the same frequency harmonic components extracted from the quadrature axis current To minimize the same-frequency harmonic components extracted from the quadrature-axis current For the direct target, the least squares method and gradient descent algorithm are used to optimize the phase calculation of the target perturbation component, obtaining the target AC component. Then, the target AC component is compared with the DC component. The two components are added together to synthesize the required direct-axis reference current. Field weakening control effectively alleviates the energy backflow problem caused by insufficient voltage, ensuring system stability; while targeted phase optimization specifically suppresses the specific frequency harmonics of the quadrature-axis current caused by field weakening control itself. The combination of the two enables the system to maintain voltage balance when dealing with severe fluctuations in DC bus voltage, effectively suppressing energy backflow, reducing torque ripple, and improving the smoothness of motor operation.

[0098] Reference Figure 15 , Figure 16 and Figure 17 , Figure 15 , Figure 16 and Figure 17 This is a schematic diagram illustrating the effect provided in the embodiments of this application. Figure 15 The experiment results show a comparison between using the motor control method proposed in this application and not using it under typical operating conditions of 800 r / min speed and 1 Nm load. The left side of the dashed line represents the experimental results when the field weakening control using the quasi-PIR controller in the motor control method proposed in this application is not used, while the right side of the dashed line represents the experimental results when the motor control method proposed in this application is used. Before 5 seconds, the back electromotive force exceeded the minimum value of the DC bus voltage, and the conventional method without the proposed solution led to energy backflow. In this situation, the DC bus current, torque, and inverter power all exhibited positive and negative values. The DC bus could not handle the backflow energy, causing the DC bus voltage amplitude to increase from 160V to 170V. After 5 seconds, using the field weakening control using the quasi-PIR controller in the motor control method proposed in this application, the negative DC bus current, torque, and inverter power components were basically eliminated, indicating that the energy backflow phenomenon was effectively suppressed. The abnormal increase trend of the DC bus voltage was curbed. Furthermore, the motor phase current waveform becomes smoother, its harmonic content is significantly reduced, and the system operation tends to be stable. Experimental results show that the field weakening control using a quasi-PIR controller in the motor control method proposed in this application can effectively suppress energy backflow caused by DC bus voltage fluctuations, while reducing current harmonics and improving the stability and performance of the system in thin-film capacitor application scenarios.

[0099] Figure 16The experiment presents comparative results under typical operating conditions of 800 r / min speed and 1 Nm load, comparing the results without and with the motor control method proposed in this application. The left side of the dashed line represents the experimental results without the motor control method proposed in this application, while the right side of the dashed line represents the experimental results using the phase angle selection method proposed in this application, which dynamically optimizes the direct-axis reference current phase with the goal of minimizing quadrature-axis current harmonics. Before 4 seconds (without using the phase angle selection method), due to the small DC bus capacitance and drastic bus voltage fluctuations, the system generated a significant 100Hz (twice the grid voltage frequency) current harmonic with an amplitude as high as 0.5A. At this time, this harmonic component was prominent in the current spectrum, indicating that the AC disturbance introduced by voltage fluctuations was not effectively suppressed. After 4 seconds (with the phase angle selection method of this application enabled), by dynamically optimizing the phase of the direct-axis reference current and reconstructing the waveform, the amplitude of the 100Hz current harmonic was significantly reduced from 0.5A to 0.3A, a reduction of 40%. The spectral comparison clearly shows that the harmonic component was effectively suppressed, and the current waveform quality was significantly improved. Experimental results demonstrate that the phase angle selection method in the motor control method proposed in this application can effectively suppress specific frequency current ripple caused by DC bus voltage fluctuations, thereby reducing torque pulsation and improving the system's operational stability and control performance under the electrolytic capacitor-free drive scheme.

[0100] Figure 17 The results show comparative experiments conducted under typical operating conditions of 800 r / min speed and 1 Nm load, comparing the results with and without the motor control method proposed in this application at different speeds (800-1000 rpm) and loads (0.5-1.5 Nm). Figure 17 As shown in the two sub-figures on the left, when the motor control method of this application is not adopted, the system exhibits significant negative backflow current (up to -2A) and backflow power (up to -200W) under certain operating conditions. And as... Figure 17 As shown in the two sub-figures on the right, after adopting the motor control method proposed in this application embodiment, the maximum return current is suppressed to around 0A and the maximum return power is also reduced to close to 0W throughout the entire test operating range. The parameter distribution surface changes from the original area with significant negative values ​​(shown in blue in the figure) to a flat distribution close to the zero-value plane (shown in the figure as a large area of ​​light blue transitioning to cyan), indicating that the energy backflow phenomenon is suppressed at each operating point.

[0101] Understandable Figures 15 to 17 This demonstrates the effectiveness of the motor control method proposed in the embodiments of this application in eliminating energy backflow and improving the stability of compressor drive systems based on electrolytic capacitors.

[0102] Based on the motor control methods of the above embodiments, the following presents various embodiments of the controller, refrigerator, computer-readable storage medium, and computer program product of this application.

[0103] like Figure 18 As shown, Figure 18 This is a schematic diagram of a controller for executing a motor control method according to an embodiment of this application. The controller 1800 implemented in this application includes: a processor 1810, a memory 1820, and a computer program stored in the memory 1820 and executable on the processor 1810, wherein... Figure 18 The example uses a processor 1810 and a memory 1820.

[0104] The processor 1810 and memory 1820 can be connected via a bus or other means. Figure 18 Taking the example of a connection between China and Israel via a bus.

[0105] Memory 1820, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs and non-transitory computer-executable programs. Furthermore, memory 1820 may include high-speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, memory 1820 may optionally include remotely located memories 1820 relative to processor 1810, which can be connected to controller 1800 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0106] Those skilled in the art will understand that Figure 18 The device structure shown does not constitute a limitation on the controller 1800 and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0107] exist Figure 18 In the controller 1800 shown, the processor 1810 can be used to call the control program stored in the memory 1820, thereby implementing the motor control method described above. Specifically, the non-transient software program and instructions required to implement the motor control method of the above embodiment are stored in the memory 1820, and when executed by the processor 1810, the motor control method of the above embodiment is executed.

[0108] It is worth noting that, since the controller 1800 of this application embodiment can execute the motor control method of any of the above embodiments, the specific implementation method and technical effect of the controller 1800 of this application embodiment can refer to the specific implementation method and technical effect of the motor control method of any of the above second aspects.

[0109] Furthermore, one embodiment of this application also provides a refrigerator that includes the controller described in the above embodiment.

[0110] It is worth noting that, since the refrigerator of this application embodiment includes the controller of the above embodiments, and the controller of the above embodiments can execute the motor control method of any of the above embodiments, the specific implementation method and technical effect of the refrigerator of this application embodiment can refer to the specific implementation method and technical effect of the motor control method of any of the above embodiments.

[0111] Furthermore, one embodiment of this application also provides a computer-readable storage medium storing computer-executable instructions for performing the above-described motor control method. Exemplarily, the above-described method is executed... Figure 1 , Figure 2 , Figure 3 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 13 The method and steps.

[0112] It is worth noting that, since the computer-readable storage medium of this application embodiment can execute the motor control method of any of the above embodiments, the specific implementation and technical effects of the computer-readable storage medium of this application embodiment can be referred to the specific implementation and technical effects of the motor control method of any of the above embodiments.

[0113] Furthermore, one embodiment of this application also provides a computer program product, including a computer program or computer instructions, which are stored in a computer-readable storage medium. A processor of a computer device reads the computer program or computer instructions from the computer-readable storage medium and executes the computer program or computer instructions, causing the computer device to perform the motor control method described above. Exemplarily, the above-described method is performed... Figure 1 , Figure 2 , Figure 3 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 13 The methods and steps in the text.

[0114] It is worth noting that, since the computer program product of this application embodiment can execute the motor control method of any of the above embodiments, the specific implementation method and technical effect of the computer program product of this application embodiment can refer to the specific implementation method and technical effect of the motor control method of any of the above embodiments.

[0115] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically include computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0116] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.

[0117] In the several embodiments provided in this application, it should be understood that the disclosed systems, instruments, and methods can be implemented in other ways. For example, the instrument embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. 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 shown or discussed mutual couplings, direct couplings, or communication connections may be through some interfaces; indirect couplings or communication connections between instruments or units may be electrical, mechanical, or other forms. Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, i.e., 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.

[0118] It should also be understood that the various implementation methods provided in this application can be combined arbitrarily to achieve different technical effects.

[0119] The above provides a detailed description of the preferred embodiments of this application. However, this application is not limited to the above-described embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A motor control method, characterized in that, The motor control method includes: Obtain the DC bus voltage and quadrature axis current of the motor, and obtain the direct axis voltage and quadrature axis voltage; An initial direct-axis current is generated by magnetic weakening control based on the direct-axis voltage, the quadrature-axis voltage, and the DC bus voltage. The target frequency disturbance component caused by DC bus voltage fluctuation and the DC component used for field weakening control are separated from the initial direct-axis current. With minimizing the harmonic components of the target frequency in the quadrature-axis current as the optimization objective, the phase of the target frequency disturbance component is optimized and calculated, and the target AC component is obtained based on the amplitude of the target frequency disturbance component and the phase obtained by the optimization calculation. A direct-axis reference current is synthesized based on the target AC component and the DC component, and the motor is controlled based on the direct-axis reference current.

2. The motor control method according to claim 1, characterized in that, The optimization objective is to minimize the harmonic components of the target frequency in the quadrature-axis current. The phase of the target frequency disturbance component is optimized and calculated. Based on the amplitude of the target frequency disturbance component and the optimized phase, the target AC component is obtained, including: The reference phase angle and reference amplitude information are extracted from the target frequency disturbance component in the initial direct-axis current; With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, the reference phase angle is adaptively iteratively calculated to obtain the target phase angle; The target AC component is obtained by combining the reference amplitude information and the target phase angle.

3. The motor control method according to claim 2, characterized in that, The step of extracting the reference phase angle and reference amplitude information of the target frequency disturbance component caused by the DC bus voltage fluctuation from the initial direct-axis current includes: The initial direct-axis current is bandpass filtered to extract the target frequency disturbance component caused by DC bus voltage fluctuations; The target frequency disturbance component is multiplied by the first local oscillator signal, the product is low-pass filtered to obtain the phase error signal, and the phase error signal is subjected to proportional-integral control to obtain the reference phase angle. The target frequency disturbance component is multiplied by the second local oscillation signal, and the product is low-pass filtered to obtain the reference amplitude information. The second local oscillation signal is orthogonal to the first local oscillation signal, and the first local oscillation signal and the second local oscillation signal update phase information according to the reference phase angle.

4. The motor control method according to claim 2, characterized in that, The adaptive iterative calculation of the reference phase angle to obtain the target phase angle includes: The harmonic component of the target frequency in the quadrature current is used as the instantaneous error signal, the reference phase angle is used as the starting phase value in the iteration process, and a reference input signal synchronized with the target frequency disturbance component is generated according to the reference phase angle. The phase value is adjusted based on the product of the instantaneous error signal and the reference input signal, and a preset step size factor; When the mean square value of the instantaneous error signal satisfies the convergence condition, the current phase value is taken as the target phase angle.

5. The motor control method according to claim 2, characterized in that, The optimization objective is to minimize the harmonic components of the target frequency in the quadrature-axis current. The phase of the target frequency disturbance component is optimized and calculated. Based on the amplitude of the target frequency disturbance component and the optimized phase, the target AC component is obtained, including: With the goal of minimizing the harmonic components of the target frequency in the quadrature-axis current, an adaptive iterative algorithm is used to calculate the phase correction. The target phase angle is obtained by superimposing the reference phase angle and the phase correction amount.

6. The motor control method according to claim 5, characterized in that, The step of calculating the phase correction using an adaptive iterative algorithm, with the objective of minimizing the harmonic components at the target frequency in the quadrature-axis current, includes: The initial value of the phase correction is set to zero, a reference input signal synchronized with the target frequency disturbance component is generated based on the reference phase angle, and the harmonic component of the target frequency in the quadrature current is used as the instantaneous error signal. When the mean square value of the instantaneous error signal does not meet the convergence condition, the reference input signal is multiplied by the instantaneous error signal to obtain the direction indication, the direction indication is multiplied by the preset adjustment step size to obtain the correction increment, and the correction increment is added to the current value of the phase correction to obtain the updated phase correction. When the mean square value of the instantaneous error signal satisfies the convergence condition, the phase correction amount is output.

7. The motor control method according to claim 4 or 6, characterized in that, The convergence condition is that the mean square value of the instantaneous error signal is less than a first preset threshold, or the change is less than a second preset threshold in a preset number of consecutive iterations.

8. The motor control method according to claim 1, characterized in that, The step of generating an initial direct-axis current through field weakening control based on the direct-axis voltage, the quadrature-axis voltage, and the DC bus voltage includes: The stator voltage amplitude is determined based on the direct-axis voltage and the quadrature-axis voltage, and the voltage limit is determined based on the DC bus voltage. The stator voltage amplitude is compared with the voltage limit to obtain the voltage error signal; The voltage error signal is input to a quasi-proportional-integral-resonant controller, which performs proportional, integral, and resonant operations centered on the target frequency in parallel to generate an initial direct-axis current.

9. The motor control method according to claim 1, characterized in that, The step of controlling the motor based on the direct-axis reference current includes: The reference angular velocity and the actual angular velocity of the motor are obtained, and the difference between the reference angular velocity and the actual angular velocity is input to the proportional-integral controller, which outputs the quadrature-axis reference current. Current loop control is performed based on the direct-axis reference current and the quadrature-axis reference current to generate a direct-axis reference voltage and a quadrature-axis reference voltage. By performing coordinate transformation on the direct-axis reference voltage and the quadrature-axis reference voltage, two-phase static voltages are obtained; A pulse width modulation signal is generated based on the two-phase static voltage, and the motor is controlled based on the pulse width modulation signal.

10. The motor control method according to claim 9, characterized in that, The process of performing coordinate transformation on the direct-axis reference voltage and the quadrature-axis reference voltage to obtain two-phase stationary voltages includes: When the quadrature axis reference voltage is less than zero, the quadrature axis reference voltage is set to a preset positive voltage. Perform an inverse Park transformation on the direct-axis reference voltage and the quadrature-axis reference voltage after setting the limit to obtain the two-phase stationary voltage in the two-phase stationary coordinate system.

11. The motor control method according to claim 9, characterized in that, The step of generating a pulse width modulation signal based on the two-phase stationary voltage includes: A composite voltage vector is generated based on the two-phase static voltage, and the modulation index is obtained based on the ratio of the amplitude of the composite voltage vector to the DC bus voltage. Based on the modulation coefficient, the modulation region where the synthesized voltage vector is located is determined, and the synthesized voltage vector is adjusted according to the modulation region to obtain the target voltage vector so that the target voltage vector meets the inverter output voltage limit of the motor. Based on the target voltage vector, a pulse width modulation signal is generated by space vector pulse width modulation.

12. The motor control method according to claim 11, characterized in that, The modulation region includes a linear modulation region and an overmodulation region. Adjusting the synthesized voltage vector according to the current modulation region to obtain the target voltage vector includes: When the synthesized voltage vector is in the linear modulation region, the synthesized voltage vector is used as the target voltage vector; When the synthesized voltage vector is in the overmodulation region, the amplitude and / or phase angle of the synthesized voltage vector are corrected to obtain the target voltage vector.

13. The motor control method according to claim 1, characterized in that, The target frequency is twice the grid voltage frequency.

14. A controller, characterized in that, The device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the motor control method as described in any one of claims 1 to 13.

15. An electric motor, characterized in that, Includes the controller as described in claim 14.

16. A refrigerator, characterized in that, This includes the controller as described in claim 14 or the motor as described in claim 15.

17. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing the controller to perform the motor control method as described in any one of claims 1 to 13.

18. A computer program product, comprising a computer program or computer instructions, characterized in that, The computer program or the computer instructions are stored in a computer-readable storage medium, the processor of the electronic device reads the computer program or the computer instructions from the computer-readable storage medium, and the processor executes the computer program or the computer instructions to cause the electronic device to perform the motor control method as described in any one of claims 1 to 13.

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