Motor driving system and air conditioner

Abstract

Some embodiments of the present application relate to the technical field of motor control, and disclosed are a motor driving system and an air conditioner. The motor driving system comprises a driving motor and a controller; the controller comprises a current vector angle calculation unit, a current vector angle harmonic compensation unit, a vector current calculation unit, and a current vector distribution unit; the current vector angle harmonic compensation unit is configured to output a current vector angle harmonic compensation angle to the current vector angle calculation unit; the current vector angle calculation unit is configured to output a compensated current vector angle to the current vector distribution unit; the vector current calculation unit is configured to output a current vector instruction of the driving motor to the current vector distribution unit; and the current vector distribution unit is configured to regulate a direct axis current and a quadrature axis current of the driving motor, so as to suppress torque ripples of the driving motor.

Description

Motor drive system and air conditioner

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application No. 2025102393516, filed on February 28, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of motor control technology, and in particular relates to a motor drive system and an air conditioner. Background Technology

[0004] In motor drive systems, the capacitance value of the bus capacitor directly affects system performance; an excessively low value will cause significant fluctuations in the bus voltage. These voltage fluctuations interact with the motor's operating frequency, resulting in torque ripple. This torque ripple is particularly pronounced under low-frequency, high-load conditions, affecting not only the motor's operational smoothness but also reducing overall system efficiency and even shortening the motor's lifespan.

[0005] In motor drive systems, how to suppress torque fluctuations through control strategies to ensure stable and efficient operation under different working conditions is one of the problems that needs to be solved in this field. Summary of the Invention

[0006] Some embodiments of this application provide a motor drive system, including:

[0007] Drive motor;

[0008] Controller, the controller includes:

[0009] The current vector angle harmonic compensation unit is configured to output the current vector angle harmonic compensation angle based on the actual speed and speed error of the drive motor through compensation and addition operations.

[0010] A current vector angle calculation unit is provided, wherein the input terminal of the current vector angle calculation unit is connected to the output terminal of the current vector angle harmonic compensation unit to receive the current vector angle harmonic compensation angle, and the current vector angle calculation unit is configured to output the compensation current vector angle based on the initial current vector angle of the drive motor and the current vector angle harmonic compensation angle through algebraic superposition operation.

[0011] A current vector allocation unit, wherein the input terminal of the current vector allocation unit is connected to the output terminal of the current vector angle calculation unit to receive the compensated current vector angle;

[0012] The vector current calculation unit has its output terminal connected to the input terminal of the current vector allocation unit, and the vector current calculation unit is configured to output the current vector command of the drive motor to the current vector allocation unit.

[0013] The current vector allocation unit is configured to adjust the direct-axis current and quadrature-axis current of the drive motor through vector decomposition and coordinate transformation based on the current vector command and the compensation current vector angle, so as to suppress the torque fluctuation of the drive motor.

[0014] According to some embodiments of this application, the speed error is determined based on the commanded speed of the drive motor and the actual speed.

[0015] According to some embodiments of this application, the current vector angle harmonic compensation unit includes:

[0016] Harmonic compensation selection unit; and

[0017] At least two angle compensation units, the output of each angle compensation unit being connected to the input of the harmonic compensation selection unit;

[0018] Each angle compensation unit is configured to output a first compensation angle to the harmonic compensation selection unit based on the rotational speed error. The harmonic frequencies corresponding to the first compensation angle output by different angle compensation units are different.

[0019] The harmonic compensation selection unit is configured to output the harmonic compensation angle of the current vector angle to the current vector angle calculation unit based on at least two of the first compensation angles and the actual rotational speed.

[0020] According to some embodiments of this application, the angle compensation unit includes:

[0021] The harmonic extraction unit is configured to use the harmonic modulation signal of the target harmonic frequency and the rotational speed error, and outputs the harmonic modulation signal.

[0022] A phase lag unit is provided, wherein the input terminal of the phase lag unit is connected to the output terminal of the harmonic extraction unit to receive the harmonic modulation signal, and the phase lag unit is configured to perform phase lag processing on the harmonic modulation signal to obtain the lag harmonic signal of the target harmonic frequency, and output the lag harmonic signal.

[0023] A first compensation calculation module is configured to receive the harmonic modulation signal by connecting its input terminal to the output terminal of the harmonic extraction unit, and to perform compensation calculation on the harmonic modulation signal and output the angle result of the compensation calculation.

[0024] The second compensation calculation module has its input terminal connected to the output terminal of the phase lag unit to receive the lag harmonic signal, and the second compensation calculation module is configured to perform compensation calculation on the lag harmonic signal and output the angle result of the compensation calculation.

[0025] The first addition operation unit has its input terminal connected to the output terminal of the first compensation operation module and the output terminal of the second compensation operation module, respectively, and the first addition operation unit is configured to output the first compensation angle of the target harmonic frequency.

[0026] According to some embodiments of this application, the first compensation calculation module includes:

[0027] The first multiplication unit is configured to perform a multiplication operation on the harmonic modulation signal of the target harmonic frequency and the rotational speed error, and output the corresponding first product result.

[0028] A first proportional resonant arithmetic unit, wherein the input terminal of the first proportional resonant arithmetic unit is connected to the output terminal of the first multiplication arithmetic unit to receive the first product result, and the first proportional resonant arithmetic unit is configured to perform gain processing on the first product result and output a first gain result;

[0029] The second multiplication unit has its input terminal connected to the output terminal of the first proportional resonance unit to receive the first gain result, and its output terminal connected to the input terminal of the first addition unit. The second multiplication unit is configured to perform a multiplication operation on the harmonic modulation signal of the target harmonic frequency and the first gain result, and output the corresponding second product result to the first addition unit.

[0030] The second compensation calculation module includes:

[0031] The third multiplication unit is configured to perform a multiplication operation on the hysteresis signal of the target harmonic frequency and the rotational speed error, and output the corresponding third product result.

[0032] The second proportional resonant arithmetic unit has its input terminal connected to the output terminal of the third multiplication arithmetic unit to receive the third product result, and the second proportional resonant arithmetic unit is configured to perform gain processing on the third product result and output a second gain result.

[0033] The fourth multiplication unit has its input terminal connected to the output terminal of the second proportional resonance unit to receive the second gain result, and its output terminal connected to the input terminal of the first addition unit. The fourth multiplication unit is configured to perform a multiplication operation on the hysteresis signal of the target harmonic frequency and the second gain result, and output the corresponding fourth product result to the first addition unit.

[0034] The first addition unit is configured to add the second product result to the fourth product result and output the first compensation angle of the target harmonic frequency.

[0035] According to some embodiments of this application, the target harmonic frequency corresponding to the harmonic extraction unit is determined based on the power grid frequency of the power grid to which the drive motor is connected.

[0036] According to some embodiments of this application, the harmonic compensation selection unit includes:

[0037] The second addition unit is configured to perform addition operations on the first compensation angle other than the first compensation angle corresponding to the first harmonic frequency to obtain the second compensation angle and output the second compensation angle.

[0038] The selection unit has its input terminal connected to the output terminal of the second addition unit to receive the second compensation angle, and the selection unit is configured to output a third compensation angle based on the actual rotational speed and the second compensation angle.

[0039] The third addition operation unit has its input terminal connected to the output terminal of the selection unit to receive the third compensation angle, and its output terminal connected to the input terminal of the current vector angle operation unit. The third addition operation unit is configured to perform an addition operation on the third compensation angle and the first compensation angle corresponding to the first harmonic frequency, and output the current vector angle harmonic compensation angle to the current vector angle operation unit.

[0040] According to some embodiments of this application, the selection unit is configured to determine that the third compensation angle is equal to the second compensation angle when the actual rotational speed is greater than a preset rotational speed threshold.

[0041] Alternatively, the selection unit is configured to determine that the third compensation angle is zero when the actual rotational speed is less than or equal to the rotational speed threshold.

[0042] According to some embodiments of this application, the current vector angle calculation unit includes:

[0043] The current angle calculation unit is configured to output the initial current vector angle based on the bus voltage, α-axis voltage, and β-axis voltage of the drive motor using a vector algorithm; and

[0044] The fourth addition operation unit has its input terminal connected to the output terminal of the current angle calculation unit to receive the initial current vector angle. The output terminal of the fourth addition operation unit is connected to the input terminal of the current vector distribution unit. The fourth addition operation unit is configured to perform an addition operation on the initial current vector angle and the current vector angle harmonic compensation angle, and output the compensation current vector angle to the current vector distribution unit.

[0045] According to some embodiments of this application, the vector current calculation unit includes:

[0046] The first subtraction unit is configured to subtract the actual rotational speed from the commanded rotational speed and output the rotational speed error; and

[0047] A speed regulator, wherein the input terminal of the speed regulator is connected to the output terminal of the first subtraction operation unit to receive the rotational speed error, the output terminal of the speed regulator is connected to the input terminal of the current vector allocation unit, and the speed regulator is configured to output the current vector command to the current vector allocation unit based on the rotational speed error and through a speed adjustment algorithm.

[0048] According to some embodiments of this application, the drive motor is a capacitorless motor.

[0049] Some embodiments of this application provide an air conditioner, which includes:

[0050] As described above, this is a motor drive system. Attached Figure Description

[0051] The above and / or additional aspects of this application will become apparent and readily understood from the description of some embodiments taken in conjunction with the following drawings, in which:

[0052] Figure 1 is a schematic diagram of the structure of a motor drive system provided in some embodiments of this application;

[0053] Figure 2 is a schematic diagram of the structure of a controller provided in some embodiments of this application;

[0054] Figure 3 is a schematic diagram of the current vector angle harmonic compensation unit provided in some embodiments of this application;

[0055] Figure 4 is a flowchart illustrating the operation of the angle compensation unit provided in some embodiments of this application.

[0056] Figure 5 is a flowchart illustrating the operation of the harmonic compensation selection unit provided in some embodiments of this application.

[0057] Figure 6 is a schematic diagram of the structure of an nth-order angle compensation unit provided in some embodiments of this application;

[0058] Figure 7 is a schematic flowchart of the operation of the harmonic extraction unit provided in some embodiments of this application;

[0059] Figure 8 is a schematic flowchart of the phase lag unit performing its operation according to some embodiments of this application;

[0060] Figure 9 is a flowchart illustrating the operation of the first compensation calculation module, the second compensation calculation module, and the first addition unit provided in some embodiments of this application.

[0061] Figure 10 is one of the flowcharts illustrating the operation of the nth angle compensation unit provided in some embodiments of this application.

[0062] Figure 11 is a schematic diagram of the structure of the first compensation calculation module provided in some embodiments of this application;

[0063] Figure 12 is a schematic diagram of the structure of the second compensation calculation module provided in some embodiments of this application;

[0064] Figure 13 is a second schematic flowchart of the nth angle compensation unit performing its work according to some embodiments of this application;

[0065] Figure 14 is a schematic diagram of the structure of a harmonic compensation selection unit provided in some embodiments of this application;

[0066] Figure 15 is a schematic flowchart of the operation of the harmonic compensation selection unit provided in some embodiments of this application.

[0067] Figure 16 is a schematic diagram of the structure of the current vector angle calculation unit provided in some embodiments of this application;

[0068] Figure 17 is a schematic diagram of the structure of a vector current calculation unit provided in some embodiments of this application;

[0069] Figure 18 is a flowchart illustrating the operation of the current vector angle calculation unit, vector current calculation unit, and current vector allocation unit provided in some embodiments of this application.

[0070] Figure 19 is a schematic diagram of the structure of an air conditioner provided in some embodiments of this application;

[0071] Figure label:

[0072] The system includes a motor drive system 1000, a drive motor 1100, a controller 1200, a current vector angle calculation unit 1210, a current angle calculation unit 1211, a fourth addition unit 1212, a vector current calculation unit 1220, a first subtraction unit 1221, a speed regulator 1222, and a current vector distribution unit 1230.

[0073] The system includes: a current vector angle harmonic compensation unit 2000, a first-order angle compensation unit 2100, a second-order angle compensation unit 2200, an nth-order angle compensation unit 2300, an nth-order harmonic extraction unit 2310, a phase lag unit 2320, a first compensation operation module 2330, a first multiplication operation unit 2331, a first proportional resonance operation unit 2332, a second multiplication operation unit 2333, a second compensation operation module 2340, a third multiplication operation unit 2341, a second proportional resonance operation unit 2342, a fourth multiplication operation unit 2343, a first addition operation unit 2350, a harmonic compensation selection unit 2400, a second addition operation unit 2410, a selection unit 2420, and a third addition operation unit 2430.

[0074] Air conditioner 3000. Detailed Implementation

[0075] Some embodiments of this application are described in detail below. Examples of these 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. 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.

[0076] In the motor drive system 1000, effective control strategies are needed to suppress torque fluctuations to ensure stable and efficient operation under different working conditions. Some embodiments of this application provide a motor drive system 1000 and an air conditioner 3000 that suppress torque fluctuations in the motor drive system 1000 through current vector angle harmonic compensation, thereby improving the stability of the drive motor 1100 operating at different frequencies and making it suitable for various working conditions.

[0077] As shown in Figure 1, the motor drive system 1000 includes a drive motor 1100 and a controller 1200. The drive motor 1100 is a device that converts electrical energy into mechanical energy, generating rotational torque through the principle of electromagnetic induction to provide power output for various mechanical devices. For example, the drive motor 1100 of an air conditioner fan can convert electrical energy into mechanical energy, driving the fan blades to rotate through rotational torque, thereby promoting airflow. As another example, the drive motor 1100 of an air conditioner compressor can convert electrical energy into mechanical energy, driving the piston or scroll plate inside the compressor to move through rotational torque, thereby compressing the refrigerant. The controller 1200 is an electronic device that can effectively control the motor speed, torque, and operating status by accurately adjusting parameters such as the motor's voltage, current, and frequency.

[0078] In some embodiments, the controller 1200 not only includes voltage and frequency regulation functions, but may also further integrate: a power grid status detection and adaptation module, which can monitor the frequency and voltage fluctuations of the power grid in real time and dynamically adjust the control strategy to avoid system instability caused by power grid disturbances; a multi-condition identification and switching module, which can identify different operating conditions of the air conditioner (such as cooling, heating, dehumidification, etc.) and environmental changes (temperature, humidity, load changes), and automatically match different motor control strategies; and a learning optimization module (AI optimization), which optimizes control parameters through online learning algorithms (such as neural networks, fuzzy control, etc.) to achieve long-term dynamic compensation and improved control accuracy.

[0079] In some embodiments, the controller 1200 is connected to the drive motor 1100, as shown in FIG2. The controller 1200 includes:

[0080] The current vector angle harmonic compensation unit 2000 is configured to output a current vector angle harmonic compensation angle based on the actual speed and speed error of the drive motor 1100; in some embodiments, the speed error is determined based on the commanded speed and actual speed of the drive motor 1100.

[0081] The input terminal of the current vector angle calculation unit 1210 is connected to the output terminal of the current vector angle harmonic compensation unit 2000 to receive the current vector angle harmonic compensation angle.

[0082] Vector current processing unit 1220; and

[0083] Current vector distribution unit 1230.

[0084] In some embodiments, the speed error is the difference between the actual speed and the commanded speed, or the absolute value of the difference. It is understood that the power grid connected to the drive motor 1100 may experience voltage fluctuations. Abnormal fluctuations in the input voltage may cause sudden changes in the speed of the drive motor 1100, resulting in the actual speed deviating from the previously set commanded speed. The controller 1200 adjusts the voltage, current, etc., of the drive motor 1100 to bring the actual speed closer to the commanded speed. In some embodiments, the output terminal of the current vector angle calculation unit 1210 is connected to the input terminal of the current vector distribution unit 1230. The current vector angle calculation unit 1210 is configured to output a compensated current vector angle to the current vector distribution unit 1230 based on the initial current vector angle of the drive motor 1100 and the current vector angle harmonic compensation angle.

[0085] In some embodiments, the compensated current vector angle output by the current vector angle calculation unit 1210 is a vector angle after being compensated by the current vector angle harmonic compensation angle. The current vector angle harmonic compensation angle is the angle obtained by extracting harmonic signals based on speed error. By superimposing the current vector angle harmonic compensation angle on the initial current vector angle, speed error can be compensated, thereby suppressing torque fluctuations of the motor. The initial current vector angle is the initial angle of the current vector in the drive motor 1100. The current vector angle calculation unit 1210 calculates the initial current vector angle based on the bus voltage, α-axis voltage, and β-axis voltage. Among them, the bus voltage is the voltage value of the bus in the motor drive system 1000. The bus voltage follows the voltage fluctuations of the power grid connected to the drive motor 1100. Power grid fluctuations may cause torque fluctuations in the drive motor 1100. It is understandable that the α-axis voltage and β-axis voltage are the results of the Clarke transformation (also known as the αβ transformation), which transforms the three-phase AC voltage of the power grid from a three-phase stationary coordinate system (ABC coordinate system) to a two-phase stationary coordinate system (αβ coordinate system). The α-axis voltage refers to the horizontal component in the two-phase stationary coordinate system, and the β-axis voltage refers to the vertical component in the two-phase stationary coordinate system. The output terminal of the vector current calculation unit 1220 is connected to the input terminal of the current vector distribution unit 1230. The vector current calculation unit 1220 is used to output the current vector command of the drive motor 1100 to the current vector distribution unit 1230.

[0086] In some embodiments, the vector current calculation unit 1220 first obtains the speed error by comparing the commanded speed with the actual speed, and then outputs a current vector command based on the motor's speed error. It is understood that there is a correspondence between motor current and speed; when the input current to the motor increases, the electromagnetic force generated by the motor strengthens, and the speed increases accordingly; conversely, when the current decreases, the speed decreases. Based on this correspondence, the vector current calculation unit 1220 can obtain a current vector command through the motor's speed error. In some embodiments, the current vector allocation unit 1230 is configured to adjust the direct-axis current and quadrature-axis current of the drive motor 1100 based on the current vector command and the compensation current vector angle to suppress torque fluctuations in the drive motor 1100.

[0087] In some embodiments, the current vector distribution unit 1230 can distribute the current according to the current vector command and the compensation current vector angle, and output the corresponding direct-axis current and quadrature-axis current after distribution. The direct-axis current, also known as the d-axis current, is in the same direction as the motor's magnetic field and is mainly used to adjust the magnetic field strength; the quadrature-axis current, also known as the q-axis current, is perpendicular to the magnetic field direction and directly determines the motor's output torque. During motor operation, the current vector command is distributed to the direct and quadrature axes respectively. The distributed direct-axis and quadrature-axis currents independently adjust the magnetic field strength and torque magnitude to avoid mutual interference affecting control accuracy and achieve more accurate torque control. In actual execution, the current vector command distribution is based on the compensation current vector angle. If torque fluctuations are detected due to sudden load changes or grid frequency fluctuations, adjusting the compensation current vector angle can achieve dynamic current distribution, making the quadrature-axis current more stable, thereby suppressing torque fluctuations.

[0088] In some embodiments, the current vector angle harmonic compensation unit 2000 not only supports low-order harmonics (such as the 3rd and 5th harmonics) extracted based on speed error, but also performs real-time separation and suppression of multi-order harmonics. It employs technologies such as bandpass filters and complex harmonic extractors to improve the system's vibration suppression capability. It implements online spectrum analysis algorithms based on phase-locked loops (PLLs) or Fourier analysis to track harmonics under dynamic speed fluctuations in real time, thereby improving the response speed to sudden disturbances. According to the current operating conditions and load characteristics, it dynamically adjusts the gain or weight of the harmonic compensation angle to achieve flexible control and avoid control overshoot caused by overcompensation. In some embodiments, the current vector angle calculation unit 1210 can support bidirectional conversion between the αβ coordinate system and the dq coordinate system. Combined with Park transformation, it can achieve more refined vector angle calculation and enhance the accuracy of current angle control. For nonlinear fluctuations in bus voltage or nonlinear magnetic saturation behavior of motor, a nonlinear compensation algorithm based on lookup table or function approximation is introduced to perform nonlinear correction on the current vector angle. In addition to bus voltage, α-axis and β-axis voltage, the influence of parameters such as motor inductance, resistance, and temperature on the initial vector angle can also be considered, thereby improving the completeness and adaptability of the calculation model. In some embodiments, the vector current calculation unit 1220 can combine with the model predictive control (MPC) strategy to predict the speed trend in the future time period, generate current vector commands in advance, realize feedforward control, and shorten the system response time. Through the online load model identification algorithm, the load type (constant torque type, variable torque type, etc.) is determined in real time and the current output strategy is adjusted to make the control more matched to the actual load requirements. In addition to considering speed error, objective functions such as efficiency enhancement, reduction of electromagnetic interference, and reduction of losses can also be introduced to achieve improved generation of current commands under multiple objectives. In some embodiments, the current vector distribution unit 1230 can perform cross-coupling and decoupling operations of the d-axis and q-axis currents based on the dynamic mathematical model of the motor, avoiding the influence of one axis adjustment on the other axis, and improving the independence and accuracy of the magnetic field control; it can adjust the current distribution strategy in real time under dynamic conditions such as torque mutation, grid disturbance, and load jump, and use dynamic weight or adaptive PID algorithm to ensure torque stability; it adopts a static distribution strategy to improve efficiency during steady-state operation, and switches to dynamic response mode during dynamic disturbances to ensure that the system quickly restores balance.

[0089] In some embodiments, the drive motor 1100 is an electrolytic capacitor-free motor. In some embodiments, an electrolytic capacitor-free motor refers to a motor system that does not use electrolytic capacitors in the drive circuit. The function of electrolytic capacitors is replaced by film capacitors, ceramic capacitors, or control algorithms, thereby improving system reliability, extending service life, and reducing size and cost. In the field of motor drive and control, the output torque of a motor can fluctuate due to factors such as voltage fluctuations, control algorithms, and mechanical problems, affecting the motor's operating performance. This is especially true in electrolytic capacitor-free motor systems, where the torque fluctuation problem is more pronounced due to the lack of filtering and energy storage functions of electrolytic capacitors.

[0090] In some embodiments of this application, a current vector angle harmonic compensation unit 2000, a current vector angle calculation unit 1210, a vector current calculation unit 1220, and a current vector distribution unit 1230 are provided in the motor drive system 1000. The current vector angle harmonic compensation unit 2000 outputs the current vector angle harmonic compensation angle based on the actual speed and speed error of the drive motor 1100. The current vector angle calculation unit 1210 calculates the initial current vector angle of the drive motor 1100 based on the bus voltage, α-axis voltage, and β-axis voltage, and superimposes the current vector angle harmonic compensation angle into the initial current vector angle, outputting the current vector angle harmonic compensation angle. The compensation current vector angle; the vector current calculation unit 1220 can output the current vector command of the drive motor 1100 based on the correspondence between the current and speed of the drive motor 1100 and the speed error; the current vector distribution unit 1230 can distribute the current vector command to the direct axis and quadrature axis according to the compensation current vector angle, thereby adjusting the direct axis current and quadrature axis current of the drive motor 1100 more accurately, realizing the torque fluctuation suppression strategy based on current vector angle harmonic compensation. This strategy can effectively suppress torque fluctuations under low frequency and high load conditions, effectively improve the operating stability of the drive motor, and is suitable for different working conditions.

[0091] According to some embodiments of the present application, the motor drive system 1000 provides a current vector angle harmonic compensation unit 2000 in the controller 1200. Based on the speed error between the actual speed and the commanded speed, the harmonics are extracted and the current vector angle harmonic compensation angle is calculated. This compensation current vector angle is then superimposed on the initial current vector angle by the current vector angle calculation unit 1210. Based on the compensation current vector angle and the current vector command calculated by the vector current calculation unit 1220, the current vector distribution unit 1230 can adjust the direct-axis current and quadrature-axis current of the drive motor 1100 more accurately. Under low-frequency and high-load conditions, it can effectively suppress torque fluctuations and effectively improve the operating stability of the drive motor, making it suitable for different working conditions.

[0092] In some embodiments, as shown in FIG3, the current vector angle harmonic compensation unit 2000 includes a harmonic compensation selection unit 2400 and at least two angle compensation units, the output terminals of the angle compensation units being connected to the input terminals of the harmonic compensation selection unit 2400. In some embodiments, the current vector angle harmonic compensation unit 2000 is provided with at least two angle compensation units. For example, as shown in FIG3, the current vector angle harmonic compensation unit 2000 includes n angle compensation units and one harmonic compensation selection unit 2400, where n is a positive integer greater than 2, and the output terminals of the n angle compensation units are connected to the input terminals of the harmonic compensation selection unit 2400. In some embodiments, the angle compensation units are configured to output a first compensation angle to the harmonic compensation selection unit 2400 based on the rotational speed error, and the harmonic frequencies corresponding to the first compensation angles output by different angle compensation units are different. It can be understood that the harmonic frequencies of a signal are integer multiples of the fundamental frequency, and a signal can have multiple harmonics of different frequencies. In some embodiments, the output of the angle compensation unit is connected to the input of the harmonic compensation selection unit 2400. By extracting the first compensation angle of at least two different harmonic frequencies through at least two angle compensation units, the speed error signal can be analyzed and compensated comprehensively and accurately, which helps to suppress torque fluctuations more precisely.

[0093] In some embodiments, such as as shown in Figure 4, during the operation of the motor, the actual rotational speed will fluctuate due to various factors, thereby generating an error signal, namely, the speed error (Δω). e The speed error contains harmonic signals of different frequencies (1st harmonic, 2nd harmonic, 3rd harmonic, etc.). The current vector angle harmonic compensation unit 2000 includes n angle compensation units, namely the 1st angle compensation unit 2100, the 2nd angle compensation unit 2200...then angle compensation unit 2300. Each angle compensation unit corrects and compensates for the harmonic signals of different frequencies in the speed error and outputs the corresponding first compensation angle. Among them, the 1st angle compensation unit 2100 extracts the 1st harmonic and outputs the 1st first compensation angle (Δθ1); the 2nd angle compensation unit 2200 extracts the 2nd harmonic and outputs the 2nd first compensation angle (Δθ2); the nth angle compensation unit 2300 extracts the nth harmonic and outputs the nth first compensation angle (Δθ1). n ).

[0094] In some embodiments, the harmonic frequencies corresponding to the first compensation angle output by different angle compensation units are multiples of each other. For example, the harmonic frequency corresponding to Δθ2 is twice the harmonic frequency corresponding to Δθ1, and Δθ nThe corresponding harmonic frequency is n times the harmonic frequency corresponding to Δθ1. In some embodiments, different angle compensation units have similar structures, only the harmonic frequencies corresponding to the output first compensation angle are different. The more angle compensation units set in the current vector angle harmonic compensation unit 2000, the higher the accuracy of the output current vector angle harmonic compensation angle. By setting at least two angle compensation units in the current vector angle harmonic compensation unit 2000, the accuracy of torque compensation of the motor drive system 1000 can be improved. In actual implementation, the specific number of angle compensation units depends on the actual application. Considering the requirements of cost, feasibility, and compensation accuracy, the number of angle compensation units can be set to 3 to 4. In some embodiments, the harmonic compensation selection unit 2400 is configured to output the current vector angle harmonic compensation angle to the current vector angle calculation unit 1210 based on at least two first compensation angles and the actual speed. In some embodiments, the output terminal of the harmonic compensation selection unit 2400 is connected to the input terminal of the current vector angle calculation unit 1210, and is used to calculate at least two first compensation angles, distinguish different operating conditions according to the actual speed, and output the current vector angle harmonic compensation angle corresponding to different operating conditions.

[0095] In some embodiments, as shown in FIG5, the input terminal of the harmonic compensation selection unit 2400 receives all the first compensation angles (Δθ1, Δθ2…Δθ). n ) and the motor's current actual speed (ω) e After processing, the current vector angle harmonic compensation angle (Δθ) is output to the current vector angle calculation unit 1210. In some embodiments, as shown in FIG6, the angle compensation unit includes a signal harmonic extraction unit 2310 configured to extract the target harmonic frequency, a phase lag unit 2320, a first compensation calculation module 2330, a second compensation calculation module 2340, and a first addition calculation unit 2350; the output terminal of the harmonic extraction unit 2310 is connected to the input terminals of the phase lag unit 2320 and the first compensation calculation module 2330, and the harmonic extraction unit 2310 is configured to extract the harmonic modulation signal of the target harmonic frequency of the rotational speed error, and output the harmonic modulation signal of the target harmonic frequency to the harmonic extraction unit and the first compensation calculation module 2330 respectively.

[0096] In some embodiments, to extract harmonic modulation signals of different harmonic frequencies, the target harmonic frequencies configured in the harmonic extraction units used in different angle compensation units are different. Taking the target harmonic frequency as the nth harmonic as an example, as shown in Figure 7, the nth harmonic extraction unit 2310 is configured to extract the harmonic modulation signal of the nth harmonic frequency of the speed error, and outputs the harmonic modulation signal of the nth harmonic frequency to the phase lag unit 2320 and the first compensation calculation module 2330 respectively. In some embodiments, the target harmonic frequency corresponding to the harmonic extraction unit is determined based on the grid frequency of the power grid to which the drive motor 1100 is connected. It is understood that the state of the power grid to which the drive motor 1100 is connected directly affects the operation of the drive motor 1100 and is an important cause of motor torque fluctuation. Setting the target harmonic frequency corresponding to the harmonic extraction unit based on the grid frequency of the power grid to which the drive motor 1100 is connected can suppress the motor torque fluctuation caused by the periodic fluctuation of the power grid. Taking the grid frequency as ω g For example, the target harmonic frequency of the first harmonic extraction unit is configured as 6ω. g The target harmonic frequency of the second harmonic extraction unit is configured to be 12ω. g The target harmonic frequency of the nth harmonic extraction unit 2310 is configured as 6nω. g The harmonic extraction unit extracts the harmonic frequency based on the grid frequency of the power grid to which the drive motor 1100 is connected, and can extract the periodic fluctuations of the power grid in the speed error for compensation.

[0097] In some embodiments, the nth harmonic extraction unit 2310 includes modules such as a bandpass filter, a phase-locked loop, and a harmonic detector, which can accurately extract signals of a specific frequency. In some embodiments, to improve filtering accuracy, the nth harmonic extraction unit 2310 also includes an adaptive frequency tracking module, which can dynamically adjust the center frequency to adapt to power grid frequency fluctuations; the extracted nth harmonic modulation signal not only retains frequency characteristics but also phase information, facilitating subsequent phase compensation. In some embodiments, the phase lag unit 2320 can implement a specific phase delay based on an FIR filter, an IIR filter, a delay network, etc.; the phase lag unit 2320 can also dynamically adjust the lag phase value so that it varies with the actual rotational speed (ω). eThe phase lag varies with frequency to match the delay characteristics of the control system; the phase lag can be obtained during system modeling and frequency response testing during design, or adaptively adjusted through online learning. In some embodiments, the first compensation calculation module 2330 can perform operations such as proportional amplification, weighted calculation, envelope detection, and amplitude normalization to convert the extracted signal into an angle compensation value; the first compensation angle is used to compensate for the instantaneous torque fluctuation of the motor, reflecting the high-frequency fast adjustment capability. In some embodiments, the second compensation calculation module 2340 is configured to calculate the second compensation angle component based on the nth harmonic modulation signal after phase lag processing, to stabilize the low-frequency error response and improve steady-state performance; proportional-integral control, average filtering, amplitude constraints, and other means can be used to improve the stability and convergence of the compensation angle. In some embodiments, the first addition unit 2350 can perform weighted synthesis to adjust the relative contribution ratio of the two compensation angles under different operating conditions in order to achieve a balance between dynamic and steady-state performance. The first addition unit 2350 also has a limiting or saturation control mechanism to prevent the superposition result from being too large and causing system instability. An input selection switch or logic judgment module can be further set to select to output only the first or second compensation angle under specific conditions to improve system flexibility.

[0098] In some embodiments, as shown in FIG8, the output terminal of the phase lag unit 2320 is connected to the input terminal of the second compensation calculation module 2340. The phase lag unit 2320 is configured to perform phase lag processing on the harmonic modulation signal of the target harmonic frequency to obtain the lag harmonic signal of the target harmonic frequency, and output the lag harmonic signal of the target harmonic frequency to the second compensation calculation module 2340. In some embodiments, the phase of the harmonic modulation signal output by the harmonic extraction unit will change relative to the input speed error. This phase change will have a negative impact on torque suppression. The phase lag unit 2320 can lag the phase of the harmonic modulation signal extracted by the harmonic extraction unit by 90°, thereby offsetting the effect of the harmonic extraction unit on the phase.

[0099] In some embodiments, as shown in Figures 9 and 10, the output terminal of the first compensation calculation module 2330 is connected to the input terminal of the first addition unit 2350. The first compensation calculation module 2330 is configured to perform compensation calculations on the harmonic modulation signal of the target harmonic frequency and output the angle result of the compensation calculation to the first addition unit 2350. The output terminal of the second compensation calculation module 2340 is connected to the input terminal of the first addition unit. The second compensation calculation module 2340 is configured to perform compensation calculations on the hysteresis harmonic signal of the target harmonic frequency and output the angle result of the compensation calculation to the first addition unit 2350. The first addition unit 2350 is configured to output a first compensation angle for the target harmonic frequency. It should be noted that in Figure 10, the first addition unit 2350 outputs the first compensation angle (Δθ) based on the calculation results of the first compensation calculation module 2330 and the second compensation calculation module 2340. n To harmonic compensation selection unit 2400, this first compensation angle (Δθ) n ) refers to any first compensation angle in the current vector angle harmonic compensation unit 2000 (n can be 1, 2, ...).

[0100] In some embodiments, as shown in FIG11, the first compensation operation module 2330 includes a first multiplication operation unit 2331, a first proportional resonance operation unit 2332, and a second multiplication operation unit 2333. The output of the first multiplication unit 2331 is connected to the input of the first proportional resonant unit 2332. The first multiplication unit 2331 is configured to multiply the harmonic modulation signal of the target harmonic frequency and the rotational speed error, and output the corresponding first product result to the first proportional resonant unit 2332. The output of the first proportional resonant unit 2332 is connected to the input of the second multiplication unit 2333. The first proportional resonant unit 2332 is configured to perform gain processing on the first product result and output the first gain result to the second multiplication unit 2333. The output of the second multiplication unit 2333 is connected to the input of the first addition unit 2350. The second multiplication unit 2333 is configured to multiply the harmonic modulation signal of the target harmonic frequency and the first gain result, and output the corresponding second product result to the first addition unit 2350.

[0101] In some embodiments, as shown in FIG12, the second compensation operation module 2340 includes a third multiplication operation unit 2341, a second proportional resonance operation unit 2342, and a fourth multiplication operation unit 2343. The output of the third multiplication unit 2341 is connected to the input of the second proportional resonant unit 2342. The third multiplication unit 2341 is configured to multiply the hysteresis signal of the target harmonic frequency and the rotational speed error, and output the corresponding third product result to the second proportional resonant unit 2342. The output of the second proportional resonant unit 2342 is connected to the input of the fourth multiplication unit 2343. The second proportional resonant unit 2342 is configured to perform gain processing on the third product result and output the second gain result to the fourth multiplication unit 2343. The output of the fourth multiplication unit 2343 is connected to the input of the first addition unit 2350. The fourth multiplication unit 2343 is configured to multiply the hysteresis signal of the target harmonic frequency and the second gain result, and output the corresponding fourth product result to the first addition unit 2350. The first addition unit 2350 is configured to add the second product result and the fourth product result, and output the first compensation angle of the target harmonic frequency.

[0102] In some embodiments, for example, as shown in Figure 13, in a motor control system, the motor experiences periodic speed errors due to fluctuations in the power grid frequency. The main interference frequency is 600Hz (caused by harmonics at 12 times the power grid frequency). The first compensation calculation module 2330 receives the 600Hz harmonic modulation signal separated by the resonance extraction unit. The first multiplication calculation unit 2331 directly multiplies the 600Hz harmonic modulation signal with the original speed error to extract relevant information related to the power grid frequency fluctuation, obtaining a first product result. Then, the first proportional calculation unit performs gain processing on the first product result to suppress the interference components of the signal, obtaining a first gain result. Finally, the first gain result is multiplied by the 600Hz harmonic modulation signal to generate a second product result. The second compensation calculation module 2340 receives the harmonic modulation signal delayed by 1 / 12ω. g The delayed harmonic signal is directly multiplied by the original speed error through the second multiplication unit 2333 to extract the phase lag interference characteristics, resulting in a third product. This third product is then processed by the second proportional unit to suppress other signal components, yielding a second gain result. Finally, the second gain result is multiplied by the delayed harmonic signal to generate a fourth product. The second and fourth products are then superimposed by the first addition unit 2350 to generate a first compensation angle. The target frequency of this first compensation angle is 600Hz, which is out of phase with the speed error caused by harmonics at 12 times the frequency of the power grid, and can be used to eliminate interference.

[0103] In some embodiments, as shown in FIG14, the harmonic compensation selection unit 2400 includes a second addition unit 2410, a selection unit 2420, and a third addition unit 2430. The output terminal of the second addition unit 2410 is connected to the input terminal of the selection unit 2420. The second addition unit 2410 is configured to perform addition operations on a first compensation angle other than the first compensation angle corresponding to the first harmonic frequency to obtain a second compensation angle, and output the second compensation angle to the selection unit 2420. The output terminal of the selection unit 2420 is connected to the input terminal of the third addition unit 2430. The selection unit 2420 is configured to output a third compensation angle to the third addition unit 2430 based on the actual rotational speed and the second compensation angle. The output terminal of the third addition unit 2430 is connected to the input terminal of the current vector angle calculation unit 1210. The third addition unit 2430 is used to perform addition operations on the third compensation angle and the first compensation angle corresponding to the first harmonic frequency, and output the current vector angle harmonic compensation angle to the current vector angle calculation unit 1210.

[0104] In some embodiments, the second addition unit 2410 is configured to perform addition operations on first compensation angles other than the first compensation angle corresponding to the first harmonic frequency, that is, to sum the second to nth first compensation angles to obtain the second compensation angle. For example, the current vector angle harmonic compensation unit 2000 is provided with a first-order angle compensation unit 2100, a second-order angle compensation unit 2200, a third-order angle compensation unit, and a fourth-order angle compensation unit, which output Δθ1, Δθ2, Δθ3, and Δθ4 to the harmonic compensation selection unit 2400, respectively. The second addition unit 2410 in the harmonic compensation selection unit 2400 sums Δθ2, Δθ3, and Δθ4 to obtain the second compensation angle (Δθ). sIn some embodiments, the selection unit 2420 is configured to determine that the third compensation angle is equal to the second compensation angle when the actual rotational speed is greater than a preset rotational speed threshold. In other embodiments, the selection unit 2420 is configured to determine that the third compensation angle is zero when the actual rotational speed is less than or equal to the rotational speed threshold. The rotational speed threshold is a preset speed critical value used to compare with the actual rotational speed to determine whether the drive motor 1100 is in a condition requiring compensation. In some embodiments, when the actual rotational speed is greater than the preset rotational speed threshold, it indicates that the drive motor 1100 is in a normal operating condition and torque fluctuations may occur; when the actual rotational speed is less than or equal to the rotational speed threshold, it indicates that the drive motor 1100 may be in a starting or about-to-shutdown operating condition, at which point torque fluctuations are small or do not affect control stability. By selectively outputting based on the actual rotational speed of the drive motor 1100, different compensation methods for torque fluctuations under different operating conditions can be achieved, increasing the flexibility of the motor drive system 1000. In actual implementation, the rotational speed threshold of the selection unit 2420 can be set according to the specific conditions of the motor.

[0105] In some embodiments, for example as shown in FIG15, the current vector angle harmonic compensation unit 2000 is provided with four angle compensation units (i.e., n=4), and the second addition unit 2410 adds Δθ2, Δθ3 and Δθ4 to obtain the second compensation angle (Δθ). s The output is sent to the selection unit 2420, and the speed threshold of the selection unit 2420 is set to 5Hz. At this time, the actual speed of the motor (ω) e The frequency is 100Hz, which is greater than the speed threshold of 5Hz. Therefore, the third compensation angle output by unit 2420 is equal to the second compensation angle (Δθ). s The third addition unit 2430 adds the third compensation angle to Δθ1 and outputs the current vector angle harmonic compensation angle (Δθ). At this time, Δθ=Δθ1+Δθ s =Δθ1+Δθ2+Δθ3+Δθ4; after 1 minute, ω e When the frequency is reduced to 5Hz, which is equal to the speed threshold of 5Hz, the third compensation angle output by the selection unit 2420 is equal to 0. The third addition operation unit 2430 adds the third compensation angle to Δθ1 and outputs the current vector angle harmonic compensation angle (Δθ), at which point Δθ=Δθ1.

[0106] In some embodiments, as shown in FIG16, the current vector angle calculation unit 1210 includes a current angle calculation unit 1211 and a fourth addition unit 1212. The output terminal of the current angle calculation unit 1211 is connected to the input terminal of the fourth addition unit 1212. The current angle calculation unit 1211 is configured to output an initial current vector angle to the fourth addition unit 1212 based on the bus voltage, α-axis voltage, and β-axis voltage of the drive motor 1100. The output terminal of the fourth addition unit 1212 is connected to the input terminal of the current vector distribution unit 1230. The fourth addition unit 1212 is configured to perform an addition operation on the initial current vector angle and the current vector angle harmonic compensation angle, and output a compensated current vector angle to the current vector distribution unit 1230. The current vector angle calculation unit 1210 can realize real-time calculation of the initial current vector angle based on the bus voltage, α-axis voltage, and β-axis voltage, and obtain the compensated current vector angle by summing the initial current vector angle and the current vector angle harmonic compensation angle, which can be used for rapid response and compensation of torque fluctuations.

[0107] In some embodiments, as shown in FIG17, the vector current calculation unit 1220 includes a first subtraction calculation unit 1221 and a speed regulator 1222. The output terminal of the first subtraction calculation unit 1221 is connected to the input terminal of the speed regulator 1222. The first subtraction calculation unit 1221 is configured to perform a subtraction operation between the actual speed and the commanded speed, and output the speed error to the speed regulator 1222. The output terminal of the speed regulator 1222 is connected to the input terminal of the current vector distribution unit 1230. The speed regulator 1222 is configured to output a current vector command to the current vector distribution unit 1230 based on the speed error. It can be understood that there is a corresponding relationship between the motor current and the speed. When the input current of the motor increases, the electromagnetic force generated by the motor increases, and the speed will increase accordingly; conversely, when the current decreases, the speed decreases. Based on the above correspondence, the speed regulator 1222 can obtain the current vector command through the speed error of the motor. Based on the actual speed and the commanded speed, the vector current calculation unit 1220 can obtain the current speed error of the motor, and convert the speed error into a current vector command through the correspondence between speed and current, and output it to the current vector distribution unit 1230. The current vector distribution unit 1230 can distribute the current according to the current vector command and the compensation current vector angle, and output the corresponding direct-axis current and quadrature-axis current after distribution.

[0108] The following describes a specific embodiment, as shown in Figure 18. In the controller 1200 of the motor drive system 1000, the bus voltage, α-axis voltage, and β-axis voltage (u) are... dc u α u βThe input will be sent to the current angle calculation unit 1211. The current angle calculation unit 1211 can calculate the real-time position of the motor based on the above parameters, that is, the initial current vector angle (θ1). Then, the fourth addition unit 1212 adds θ1 with the current vector angle harmonic compensation angle (Δθ) output by the current vector angle harmonic compensation unit 2000 to obtain the compensated current vector angle (θ), and outputs θ to the current vector distribution unit 1230; the command speed of the motor (ω) e * ) and actual rotational speed (ω) e The input will be sent to the first subtraction unit 1221, which can calculate the motor speed error (Δω) based on the above parameters. e ), and Δω e The output is sent to speed regulator 1222, which is based on Δω. e Output current vector command (i s * ) to the current vector distribution unit 1230; the current vector distribution unit 1230 receives θ and i s * After that, i will be s * Based on the magnitude of θ, the current is decomposed onto the direct axis and the quadrature axis, and finally the direct axis current command (i) is output. d * ) and quadrature axis current command (i q * ), used to compensate for the motor.

[0109] Some embodiments of this application also provide an air conditioner 3000. As shown in FIG19, the air conditioner 3000 includes the aforementioned motor drive system 1000. According to the air conditioner 3000 provided in some embodiments of this application, by setting a current vector angle harmonic compensation unit 2000, a current vector angle calculation unit 1210, a vector current calculation unit 1220, and a current vector distribution unit 1230 in the motor drive system 1000 of the air conditioner 3000, the actual speed and speed error are input, and after calculation and operation by each unit, a current command can be output to compensate during the operation of the motor. Under low-frequency high load conditions, it can effectively suppress torque fluctuations, effectively improve the operating stability of the drive motor, and is suitable for different working conditions.

[0110] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship. In the description of some embodiments of this application, "first feature" and "second feature" can include one or more of that feature. In the description of some embodiments of this application, "multiple" means two or more. In the description of this specification, references to terms such as "an embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0111] Although some embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A motor drive system, comprising: Drive motor; A controller, connected to the drive motor, the controller comprising: The current vector angle harmonic compensation unit is configured to output the current vector angle harmonic compensation angle based on the actual speed and speed error of the drive motor through compensation and addition operations. A current vector angle calculation unit is provided, wherein the input terminal of the current vector angle calculation unit is connected to the output terminal of the current vector angle harmonic compensation unit to receive the current vector angle harmonic compensation angle, and the current vector angle calculation unit is configured to output the compensation current vector angle based on the initial current vector angle of the drive motor and the current vector angle harmonic compensation angle through algebraic superposition operation. A current vector allocation unit, wherein the input terminal of the current vector allocation unit is connected to the output terminal of the current vector angle calculation unit to receive the compensated current vector angle; The vector current calculation unit has its output terminal connected to the input terminal of the current vector allocation unit, and the vector current calculation unit is configured to output the current vector command of the drive motor to the current vector allocation unit. The current vector allocation unit is configured to adjust the direct-axis current and quadrature-axis current of the drive motor through vector decomposition and coordinate transformation based on the current vector command and the compensation current vector angle, so as to suppress the torque fluctuation of the drive motor.

2. The motor drive system according to claim 1, wherein, The speed error is determined based on the commanded speed of the drive motor and the actual speed.

3. The motor drive system according to claim 1, wherein, The current vector angular harmonic compensation unit includes: Harmonic compensation selection unit; and At least two angle compensation units, the output of each angle compensation unit being connected to the input of the harmonic compensation selection unit; Each angle compensation unit is configured to output a first compensation angle to the harmonic compensation selection unit based on the rotational speed error. The harmonic frequencies corresponding to the first compensation angle output by different angle compensation units are different. The harmonic compensation selection unit is configured to output the harmonic compensation angle of the current vector angle to the current vector angle calculation unit based on at least two of the first compensation angles and the actual rotational speed.

4. The motor drive system according to claim 3, wherein, The angle compensation unit includes: The harmonic extraction unit is configured to extract the harmonic modulation signal of the target harmonic frequency and the rotational speed error, and output the harmonic modulation signal; A phase lag unit is provided, wherein the input terminal of the phase lag unit is connected to the output terminal of the harmonic extraction unit to receive the harmonic modulation signal, and the phase lag unit is configured to perform phase lag processing on the harmonic modulation signal to obtain the lag harmonic signal of the target harmonic frequency, and output the lag harmonic signal. A first compensation calculation module is configured to receive the harmonic modulation signal by connecting its input terminal to the output terminal of the harmonic extraction unit, and to perform compensation calculation on the harmonic modulation signal and output the angle result of the compensation calculation. The second compensation calculation module has its input terminal connected to the output terminal of the phase lag unit to receive the lag harmonic signal, and the second compensation calculation module is configured to perform compensation calculation on the lag harmonic signal and output the angle result of the compensation calculation. The first addition operation unit has its input terminal connected to the output terminal of the first compensation operation module and the output terminal of the second compensation operation module, respectively, and the first addition operation unit is configured to output the first compensation angle of the target harmonic frequency.

5. The motor drive system according to claim 4, wherein, The first compensation calculation module includes: The first multiplication unit is configured to perform a multiplication operation on the harmonic modulation signal of the target harmonic frequency and the rotational speed error, and output the corresponding first product result. A first proportional resonant arithmetic unit, wherein the input terminal of the first proportional resonant arithmetic unit is connected to the output terminal of the first multiplication arithmetic unit to receive the first product result, and the first proportional resonant arithmetic unit is configured to perform gain processing on the first product result and output a first gain result. The second multiplication unit has its input terminal connected to the output terminal of the first proportional resonance unit to receive the first gain result, and its output terminal connected to the input terminal of the first addition unit. The second multiplication unit is configured to perform a multiplication operation on the harmonic modulation signal of the target harmonic frequency and the first gain result, and output the corresponding second product result to the first addition unit. The second compensation calculation module includes: The third multiplication unit is configured to perform a multiplication operation on the hysteresis signal of the target harmonic frequency and the rotational speed error, and output the corresponding third product result. The second proportional resonant arithmetic unit has its input terminal connected to the output terminal of the third multiplication arithmetic unit to receive the third product result, and the second proportional resonant arithmetic unit is configured to perform gain processing on the third product result and output a second gain result. The fourth multiplication unit has its input terminal connected to the output terminal of the second proportional resonance unit to receive the second gain result, and its output terminal connected to the input terminal of the first addition unit. The fourth multiplication unit is configured to perform a multiplication operation on the hysteresis signal of the target harmonic frequency and the second gain result, and output the corresponding fourth product result to the first addition unit. The first addition unit is configured to add the second product result to the fourth product result and output the first compensation angle of the target harmonic frequency.

6. The motor drive system according to claim 4, wherein, The target harmonic frequency corresponding to the harmonic extraction unit is determined based on the power grid frequency to which the drive motor is connected.

7. The motor drive system according to claim 3, wherein, The harmonic compensation selection unit includes: The second addition unit is configured to perform addition operations on the first compensation angle other than the first compensation angle corresponding to the first harmonic frequency to obtain the second compensation angle and output the second compensation angle. The selection unit has its input terminal connected to the output terminal of the second addition unit to receive the second compensation angle, and the selection unit is configured to output a third compensation angle based on the actual rotational speed and the second compensation angle. The third addition operation unit has its input terminal connected to the output terminal of the selection unit to receive the third compensation angle, and its output terminal connected to the input terminal of the current vector angle operation unit. The third addition operation unit is configured to perform an addition operation on the third compensation angle and the first compensation angle corresponding to the first harmonic frequency, and output the current vector angle harmonic compensation angle to the current vector angle operation unit.

8. The motor drive system according to claim 7, wherein, The selection unit is configured to determine that the third compensation angle is equal to the second compensation angle when the actual rotational speed is greater than a preset rotational speed threshold. Alternatively, the selection unit is configured to determine that the third compensation angle is zero when the actual rotational speed is less than or equal to the rotational speed threshold.

9. The motor drive system according to any one of claims 1-8, wherein, The current vector angle calculation unit includes: The current angle calculation unit is configured to output the initial current vector angle based on the bus voltage, α-axis voltage, and β-axis voltage of the drive motor using a vector algorithm; and The fourth addition operation unit has its input terminal connected to the output terminal of the current angle calculation unit to receive the initial current vector angle. The output terminal of the fourth addition operation unit is connected to the input terminal of the current vector distribution unit. The fourth addition operation unit is configured to perform an addition operation on the initial current vector angle and the current vector angle harmonic compensation angle, and output the compensation current vector angle to the current vector distribution unit.

10. The motor drive system according to any one of claims 1-8, wherein, The vector current calculation unit includes: The first subtraction unit is configured to subtract the actual rotational speed from the commanded rotational speed and output the rotational speed error; and A speed regulator, wherein the input terminal of the speed regulator is connected to the output terminal of the first subtraction operation unit to receive the rotational speed error, the output terminal of the speed regulator is connected to the input terminal of the current vector allocation unit, and the speed regulator is configured to output the current vector command to the current vector allocation unit based on the rotational speed error and through a speed adjustment algorithm.

11. The motor drive system according to any one of claims 1-8, wherein, The drive motor is a capacitorless motor.

12. An air conditioner comprising a motor drive system as claimed in any one of claims 1-11.

Images