Motor control method, device and motor equipment

Abstract

The present application relates to a motor control method, device and motor equipment, which obtains bus voltage and motor current, performs vector coordinate transformation to obtain operating torque, obtains the first axis current command value according to the operating torque and the command torque, performs step calculation and current PI controller processing on the voltage deviation between the bus voltage and the rated voltage to obtain the voltage vector, and controls the operation of the motor. The method is based on bus voltage, adopts magnetic field oriented control, obtains the operating torque by decoupling the motor current, designs the current PI controller, and performs feedback adjustment on the motor according to the error between the electronic flux and the torque, so that the motor torque is kept within a certain tolerance band, so that the motor can maintain stable torque output under different voltage inputs, improves the voltage adaptability of the motor, and is reliable to use.

Description

Technical Field

[0001] The present application relates to the field of motor technology, and in particular to a motor control method, device and motor equipment. Background Art

[0002] A motor is an electromagnetic device that converts or transmits electrical energy based on the law of electromagnetic induction. Its main function is to generate driving torque. It is widely used as a power source for electrical appliances or various machines.

[0003] However, in the actual operation of motor application equipment, the rated power supply standards of various countries / regions are different, and there may be power supply fluctuations, which leads to unstable input voltage of the motor. When the input voltage of the motor is below the rated voltage of the motor, the actual torque output of the motor cannot reach the maximum, and the output torque decreases with the decrease of voltage, resulting in weak adaptability of the motor to voltage, which reduces the working performance of the motor application equipment. Summary of the invention

[0004] In view of the problem that traditional motors have weak adaptability to voltage, resulting in poor working performance of motor application equipment, the present invention proposes a motor control method, device and motor equipment. The motor control method, device and motor equipment can improve the voltage adaptability of the motor and achieve reliable technical effects.

[0005] A motor control method comprises the following steps:

[0006] Get bus voltage and motor current;

[0007] Performing vector coordinate transformation on the motor current to obtain operating torque;

[0008] A first axis current command value is obtained according to the operating torque and the command torque; the command torque is obtained according to the current gear position of the motor;

[0009] When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain a second axis current command value;

[0010] The first axis current command value and the second axis current command value are used as inputs of a current PI controller, and the output of the current PI controller is inversely transformed to obtain a voltage vector; the voltage vector is used to control the operation of the motor.

[0011] A motor control device, comprising:

[0012] Parameter acquisition module, used to obtain bus voltage and motor current;

[0013] A coordinate transformation module, used for performing vector coordinate transformation on the motor current to obtain a running torque;

[0014] A first axis current command value acquisition module, used to obtain a first axis current command value according to the operating torque and the command torque; the command torque is obtained according to the current gear position of the motor;

[0015] A second axis current command value acquisition module, used for performing step calculation on the voltage deviation between the bus voltage and the rated voltage to obtain a second axis current command value when the bus voltage is less than the rated voltage of the motor;

[0016] The inverse transformation module is used to use the first axis current command value and the second axis current command value as inputs of the current PI controller, and inversely transform the output of the current PI controller to obtain a voltage vector; the voltage vector is used to control the operation of the motor.

[0017] A motor device comprises a motor and the motor control device as described above.

[0018] The motor control method, device and motor equipment described above first obtain the bus voltage and motor current, perform vector coordinate transformation on the motor current to obtain the operating torque, then obtain the first axis current command value based on the operating torque and the command torque, the command torque is obtained according to the current gear of the motor, when the bus voltage is less than the rated voltage of the motor, the voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain the second axis current command value, and then the first axis current command value and the second axis current command value are used as the input of the current PI controller, and the output of the current PI controller is inversely transformed to obtain the voltage vector, which is used to control the operation of the motor. The method is based on the bus voltage and adopts magnetic field oriented control. By decoupling the motor current, the operating torque is obtained, and the current PI controller is designed. The motor is feedback-regulated according to the error between the electronic flux and the torque, so that the motor torque is kept within a certain tolerance band, the motor output torque is stable, and the regulated voltage vector is used to control the motor operation, so that the motor can maintain stable torque output under different voltage inputs, improve the voltage adaptability of the motor, and is reliable in use.

[0019] In one embodiment, after obtaining the first axis current command value according to the operating torque and the command torque, before using the first axis current command value and the second axis current command value as inputs of a current PI controller and performing an inverse transformation on the output of the current PI controller to obtain a voltage vector, the method further includes:

[0020] When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value.

[0021] In one embodiment, when the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value, including:

[0022] When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a torque deviation adjustment coefficient is obtained according to the operating torque, the maximum torque of the motor and a preset minimum torque deviation unit;

[0023] The second axis current command value is obtained according to the torque deviation adjustment coefficient and a preset second axis current torque deviation minimum adjustment unit; the preset second axis current torque deviation minimum adjustment unit corresponds to the preset minimum torque deviation unit.

[0024] In one embodiment, when the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value, including:

[0025] When the bus voltage is greater than or equal to the rated voltage of the motor, and under the premise that the command torque is the maximum torque of the motor, if the operating torque is less than the maximum torque of the motor, the torque deviation between the operating torque and the maximum torque of the motor is step-calculated to obtain the second axis current command value.

[0026] In one embodiment, performing vector coordinate transformation on the motor current to obtain the operating torque includes:

[0027] Performing vector coordinate transformation on the motor current to obtain a motor space vector torque / current model;

[0028] The operating torque is estimated based on the motor space vector torque / current model.

[0029] In one embodiment, when the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain a second axis current command value, including:

[0030] When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is calculated step by step to obtain an intermediate value of the second axis current;

[0031] The second axis current intermediate value is limited to obtain a second axis current command value.

[0032] In one embodiment, when the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain a second axis current command value, including:

[0033] When the bus voltage is less than the rated voltage of the motor, a voltage deviation adjustment coefficient is obtained according to the bus voltage, the rated voltage of the motor and a preset minimum voltage deviation unit;

[0034] The second axis current command value is obtained according to the voltage deviation adjustment coefficient and a preset voltage deviation minimum adjustment unit of the second axis current; the preset voltage deviation minimum adjustment unit of the second axis current corresponds to the preset voltage deviation minimum adjustment unit.

[0035] In one embodiment, the current PI controller includes a first current PI controller and a second current PI controller, and the first axis current command value and the second axis current command value are used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain a voltage vector, including:

[0036] Using the first axis current command value as the input of the first current PI controller, and outputting a first voltage signal;

[0037] using the second axis current command value as an input of the second current PI controller and outputting a second voltage signal;

[0038] The first voltage signal and the second voltage signal are inversely transformed to obtain a voltage vector.

[0039] In one embodiment, before obtaining the bus voltage and the motor current, the method further includes:

[0040] Send a power-on command to the motor; the power-on command is used to control the motor to power on and initialize.

[0041] In one embodiment, the motor device is a DC fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a flow chart of a motor control method in one embodiment;

[0043] Figure 2 is a flow chart of a motor control method in another embodiment;

[0044] Figure 3 is a flow chart of a motor control method in yet another embodiment;

[0045] Figure 4 A flowchart of a motor control method in another embodiment;

[0046] Figure 5 is a flow chart of a motor control method in another embodiment;

[0047] Figure 6 A block diagram of a constant torque control method for a motor control in one embodiment;

[0048] Figure 7 A motor load characteristic curve diagram in one embodiment;

[0049] Figure 8 A step-type torque compensation control flow chart of a motor control method in one embodiment;

[0050] Fig. 9 This is a torque test result diagram of a motor control method applied to a fan disk in an embodiment. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is described more comprehensively below through embodiments and in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present invention.

[0052] In one embodiment, a motor control method is provided. The method can be applied to various motor drives such as water pumps and air conditioning compressors. For example, it can be applied to small and medium-power constant torque DC fan disks. Small and medium-power fan disks have a high market share and have cost requirements. The application of the motor control method of the present application can take into account low costs while not sacrificing product performance, thereby improving the adaptability of fan disk products and improving product competitiveness. The motor control method can be executed by a controller that is already present in the motor application device. The corresponding functions can be added to the original controller to reduce hardware costs. Alternatively, an independent controller can be set in the motor application device to execute the method proposed in this application. The specific selection can be based on actual needs. Please refer to Figure 1 , the motor control method comprises the following steps:

[0053] Step S100: Obtain bus voltage and motor current.

[0054] Specifically, the bus voltage is the voltage at the bus that provides electrical energy to the motor, which can reflect the input voltage of the motor. The bus voltage is generally a DC bus voltage. The motor current can be a two-phase current of the motor or a three-phase current of the motor. Taking the motor current as a two-phase current as an example, the two-phase current refers to any two-phase current of the motor. Because the three-phase current of the motor conforms to the KCL law, ia+ib+ic=0, the third-phase current can be solved if the two-phase current is known. That is, if the two-phase currents ia and ib are obtained, the calculation formula for the other phase current ic of the motor is ic=-(ia+ib). Obtaining the two-phase current can reduce one current sampling and save hardware costs.

[0055] Step S200: Perform vector coordinate transformation on the motor current to obtain the operating torque.

[0056] The controller processes the received motor current. In this embodiment, taking the motor current as a two-phase current as an example, the two-phase current is vector-coordinate transformed, that is, the equivalent three-phase magnetic field, two-phase magnetic field and rotating DC magnetic field are described by magnetic potential or current space vector, and their coordinates are transformed to obtain the operating torque. The method of vector coordinate transformation is not unique and can be selected according to actual needs as long as the technicians in this field believe that it can be implemented. The operating torque refers to the real torque of the current motor, which can reflect the torque output of the motor.

[0057] Step S300: Obtain a first axis current command value according to the operating torque and the command torque.

[0058] Among them, the command torque is obtained according to the current gear of the motor, and the corresponding relationship between the motor gear and the command torque is known. After obtaining the current gear of the motor, the corresponding command torque can be obtained, so that the command torque can be used as a known quantity to participate in subsequent operations. The method of obtaining the first axis current command value according to the operating torque and the command torque is not unique. In this embodiment, the first axis current command value is obtained according to the error integration of the operating torque and the command torque after passing through the torque PI controller. Specifically, the torque PI controller uses the operating torque and the command torque as input to obtain the first axis current command value. The first axis current command value can be the q axis current command value.

[0059] Step S400: When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is calculated in steps to obtain a second axis current command value.

[0060] According to the detected bus voltage, the relationship between it and the rated voltage of the motor is judged. If the bus voltage is less than the rated voltage of the motor, considering that the input voltage of the motor is low, the flux adjustment is performed, and the voltage deviation between the bus voltage and the rated voltage is calculated in steps to obtain the second axis current command value. The step calculation can be understood as the calculation of the stair climbing process (knowing the stride required to climb one step, then the total stride to be adjusted is known by how many steps are corresponding to climbing one floor). That is, the step calculation refers to setting a numerical range corresponding to a minimum unit (which can be considered as a step), calculating the deviation between the two variables, and judging how many minimum units are included in the deviation between the two variables, that is, how many steps there are between the two variables, and each step has a corresponding processing measure for the deviation. In this embodiment, the bus voltage and the rated voltage are two variables. After setting a minimum voltage unit, according to the voltage difference between the bus voltage and the rated voltage, it is judged how many minimum voltage units are included in the voltage difference, and each minimum voltage unit has a corresponding processing measure (torque adjustment) for the deviation. The second axis current command value can be the d-axis current command value.

[0061] Step S500: taking the first axis current command value and the second axis current command value as inputs of the current PI controller, and performing inverse transformation on the output of the current PI controller to obtain a voltage vector.

[0062] Among them, the voltage vector is used to control the operation of the motor. Specifically, the first axis current command value and the second axis current command value are obtained after the current PI controller to obtain voltage signals Ud and Uq. After inverse transformation, the first axis current command value and the second axis current command value are converted into voltage vectors in a stationary coordinate system. The voltage vector generates a controllable PWM control signal via SVPWM (a commonly used voltage space vector pulse width modulation method, which is used to adjust the switching state of the inverter switching device) to drive the inverter bridge to output a three-phase symmetrical sinusoidal wave voltage, thereby driving the motor to achieve stable operation. The inverse transformation of this step is the reverse process of the vector coordinate transformation in step S200. The specific type of inverse transformation is not unique, and can be selected with reference to the type of the aforementioned vector coordinate transformation, as long as the technicians in this field believe that it can be achieved.

[0063] In one embodiment, see Figure 2 , after step S300 and before step S500 , the motor control method further includes step S410 .

[0064] Step S410: When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value.

[0065] Specifically, when the bus voltage is greater than or equal to the rated voltage of the motor, the input voltage of the motor is considered to be sufficient. At this time, if the operating torque is less than the maximum torque of the motor, it is considered to be an extreme case that the actual torque of the motor after torque compensation under low voltage still cannot reach the maximum torque of the motor. In this case, a second layer of real-time torque judgment is added, and the torque deviation between the operating torque and the maximum torque of the motor is calculated in steps to obtain the second-axis current command value. In this step, the process of performing a step-by-step calculation of the torque deviation between the operating torque and the maximum torque of the motor can be analogous to the process of performing a step-by-step calculation of the voltage deviation between the bus voltage and the rated voltage in step S400, which will not be repeated here. Similarly, the second-axis current command value can also be the d-axis current command value.

[0066] In one embodiment, see Figure 3 , step S410 includes step S411 and step S412.

[0067] Step S411: when the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a torque deviation adjustment coefficient is obtained according to the operating torque, the maximum torque of the motor and a preset minimum torque deviation unit.

[0068] When the bus voltage is greater than or equal to the rated voltage of the motor, the input voltage of the motor is considered to be sufficient. At this time, if the operating torque is less than the maximum torque of the motor, it is considered to be an extreme case that the actual torque of the motor still cannot reach the maximum torque of the motor after torque compensation under low voltage. In this case, a second layer of real-time torque judgment is added to perform a step-by-step calculation on the torque deviation between the operating torque and the maximum torque of the motor to obtain the second axis current command value. Specifically, the specific value of the preset minimum torque deviation unit is not unique and can be set according to actual needs. For example, it can be 0.1N·m or 1N·m, etc. The method of obtaining the torque deviation adjustment coefficient according to the operating torque, the maximum torque of the motor and the preset minimum torque deviation unit can be:

[0069] K2=(T max -T f ) / ΔT (1)

[0070] Among them, K2 is the torque deviation adjustment coefficient, T max is the maximum torque of the motor, T f is the operating torque, and ΔT is the preset minimum torque deviation unit. It can be understood that in other embodiments, the torque deviation adjustment coefficient can also be calculated in other ways, as long as those skilled in the art consider it feasible.

[0071] Step S412: obtaining a second-axis current command value according to the torque deviation adjustment coefficient and a preset second-axis current torque deviation minimum adjustment unit.

[0072] Among them, the preset torque deviation minimum adjustment unit of the second axis current corresponds to the preset minimum torque deviation unit, and the specific value of the preset torque deviation minimum adjustment unit of the second axis current is not unique, and can be set according to actual needs, for example, it can be 0.01A or 0.1A, etc. Further, when obtaining the second axis current command value according to the torque deviation adjustment coefficient, the torque deviation adjustment coefficient obtained in the above steps can be rounded off, and the rounded value can be used to update the torque deviation adjustment coefficient to reduce the complexity of the calculation. The calculation method for obtaining the second axis current command value according to the torque deviation adjustment coefficient and the preset torque deviation minimum adjustment unit of the second axis current is:

[0073] Idref=Id-K2ΔidT (2)

[0074] Among them, Idref is the second axis current command value, K2 is the torque deviation adjustment coefficient, ΔidT is the torque deviation minimum adjustment unit of the preset second axis current, and Id is the second axis current intermediate conversion value, which is used to update the second axis current command value, and Id is 0 initially. It can be understood that in other embodiments, the second axis current command value can also be calculated according to other methods, as long as those skilled in the art believe that it can be achieved.

[0075] In one embodiment, step S410 includes step 414 .

[0076] Step 414: When the bus voltage is greater than or equal to the rated voltage of the motor, under the premise that the command torque is the maximum torque of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain the second axis current command value.

[0077] Specifically, when the bus voltage is greater than or equal to the rated voltage of the motor, the input voltage of the motor is considered to be sufficient. At this time, under the premise that the command torque is the maximum torque of the motor, the motor needs to output a large torque output. If the operating torque is less than the maximum torque of the motor, it is considered that the actual torque of the motor still cannot reach the maximum torque of the motor after torque compensation under low voltage. In this case, a second layer of real-time torque judgment is added to perform step calculation on the torque deviation between the operating torque and the maximum torque of the motor to obtain the second axis current command value.

[0078] In one embodiment, see Figure 4 , step S200 includes step S210 and step S220.

[0079] Step S210: performing vector coordinate transformation on the motor current to obtain a motor space vector torque / current model.

[0080] Vector coordinate transformation is to describe the equivalent three-phase magnetic field, two-phase magnetic field and rotating DC magnetic field with magnetic potential or current space vector, and perform coordinate transformation on them. The vector coordinate transformation method is not unique. In this embodiment, it can include Clark transformation and Park coordinate transformation. Clark transformation is the transformation of three-phase plane coordinate system ABC to two-phase plane rectangular coordinate system αβ. Park transformation is the transformation of two-phase plane rectangular coordinate system αβ to two-phase rotating coordinate system dq. After the motor current is vector coordinate transformed, the motor space vector torque / current model can be obtained, which is convenient for subsequent calculations.

[0081] Step S220: Estimate the operating torque according to the motor space vector torque / current model.

[0082] Specifically, taking the vector coordinate transformation including Clark transformation and Park coordinate transformation, and the motor current being a two-phase current as an example, the motor space vector torque / current models obtained are:

[0083] Current: (i d ,i q )=Γ1(i a ,i b ,i c )

[0084] Torque: T = Γ2(i d ,i q )

[0085] Finally, the stator three-phase current (i a ,i b ,i c ) to get (i d ,i q ),i q is the intermediate conversion value of the q-axis current, the q-axis is the first axis, i d is the intermediate conversion value of the d-axis current, the d-axis is the second axis, and the torque can be expressed as the current vector (i d ,i q ) function Γ. Γ1 and Γ2 represent a known function. It can be understood that in other embodiments, other methods can also be used to obtain the operating torque, as long as those skilled in the art believe that it can be achieved.

[0086] In one embodiment, see Figure 4 , step S400 includes step S401 and step S402.

[0087] Step S401: when the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is calculated in steps to obtain an intermediate value of the second axis current.

[0088] The relationship between the detected bus voltage and the rated voltage of the motor is judged. If the bus voltage is less than the rated voltage of the motor, considering that the input voltage of the motor is too low, flux adjustment is performed, and the voltage deviation between the bus voltage and the rated voltage is calculated in steps to obtain the intermediate value of the second axis current.

[0089] Step S402: performing a limiting process on the intermediate value of the second axis current to obtain a second axis current command value.

[0090] After the second axis current intermediate value is limited, the limited value is used as the second axis current command value. Limiting refers to limiting the maximum and minimum output values, such as limiting the variable x by ±100, that is, the maximum value of x does not exceed 100, and the minimum value does not exceed -100. If it exceeds the limiting range, it will be processed according to the limiting value. In this embodiment, the obtained second axis current intermediate value can be compared with the preset second axis current threshold. When the second axis current intermediate value is less than or equal to the preset second axis current threshold, the second axis current intermediate value is used as the second axis current command value. When the second axis current intermediate value is greater than the preset second axis current threshold, the preset second axis current threshold is used as the second axis current command value. The second axis current command value can be limited to a certain range by limiting processing to avoid the second axis current command value being too large or too small.

[0091] In one embodiment, see Figure 5 , step S400 includes step S4011 and step S4022.

[0092] Step S4011: when the bus voltage is less than the motor rated voltage, a voltage deviation adjustment coefficient is obtained according to the bus voltage, the motor rated voltage and a preset minimum voltage deviation unit.

[0093] If the bus voltage is less than the rated voltage of the motor, considering that the input voltage of the motor is too low, the flux adjustment is performed, and the voltage deviation between the bus voltage and the rated voltage is calculated in steps to obtain the second axis current command value. Specifically, the specific value of the preset minimum voltage deviation unit is not unique and can be set according to actual needs, for example, it can be 0.1N·m or 1N·m. The method of obtaining the voltage deviation adjustment coefficient based on the bus voltage, the rated voltage of the motor and the preset minimum voltage deviation unit can be:

[0094] K1=(V N -V dc ) / ΔV (3)

[0095] Among them, K1 is the voltage deviation adjustment coefficient, V N is the rated voltage of the motor, V dcis the bus voltage, and ΔV is the preset minimum voltage deviation unit. It can be understood that in other embodiments, the voltage deviation adjustment coefficient can also be calculated in other ways, as long as those skilled in the art consider it feasible.

[0096] Step S4022: obtaining a second-axis current command value according to the voltage deviation adjustment coefficient and a preset second-axis current voltage deviation minimum adjustment unit.

[0097] Among them, the preset voltage deviation minimum adjustment unit of the second axis current corresponds to the preset voltage deviation minimum adjustment unit. The specific value of the preset voltage deviation minimum adjustment unit of the second axis current is not unique and can be set according to actual needs. For example, it can be 0.01A or 0.1A, etc. Further, when obtaining the second axis current command value according to the voltage deviation adjustment coefficient, the voltage deviation adjustment coefficient obtained in the above steps can be rounded off and the rounded value can be used to update the voltage deviation adjustment coefficient to reduce the complexity of the calculation. The calculation method for obtaining the second axis current command value according to the voltage deviation adjustment coefficient and the preset voltage deviation minimum adjustment unit of the second axis current is:

[0098] Idref=Id-K1Δidv (2)

[0099] Among them, Idref is the second axis current command value, K1 is the voltage deviation adjustment coefficient, Δidv is the voltage deviation minimum adjustment unit of the preset second axis current, and Id is the second axis current intermediate conversion value, which is used to update the second axis current command value, and Id is 0 initially. It can be understood that in other embodiments, the second axis current command value can also be calculated according to other methods, as long as those skilled in the art believe that it can be achieved.

[0100] In one embodiment, the current PI controller includes a first current PI controller and a second current PI controller, see Figure 5 , step S500 includes step S510 to step S530.

[0101] Step S510: taking the first axis current command value as the input of the first current PI controller and outputting a first voltage signal.

[0102] The first axis current command value is used as the input of the first current PI controller, and the first voltage signal Uq is obtained after passing through the first current PI controller.

[0103] Step S520: taking the second axis current command value as the input of the second current PI controller and outputting a second voltage signal.

[0104] The second axis current command value is used as the input of the second current PI controller, and the second voltage signal Ud is obtained after passing through the second current PI controller.

[0105] Step S530: performing inverse transformation on the first voltage signal and the second voltage signal to obtain a voltage vector.

[0106] The first voltage signal and the second voltage signal are inversely transformed, and the first axis current command value and the second axis current command value are converted into a voltage vector in a stationary coordinate system. Taking the inverse transformation as an example, the Park inverse transformation is the reverse process of the Park transformation. After the Park inverse transformation, the rotating coordinate system dq is converted into the voltage vectors Uα and Uβ in the stationary coordinate system αβ, and a controllable PWM control signal is generated through SVPWM to drive the inverter bridge to output a three-phase symmetrical sinusoidal wave voltage, thereby driving the motor to achieve stable operation.

[0107] In one embodiment, see Figure 5 Before step S100, the motor control method further includes step S101.

[0108] Step S101: Send a power-on command to the motor.

[0109] Among them, the power-on command is used to control the motor to power on and initialize. Before obtaining the bus voltage and the motor current, the motor needs to be running first. At this time, the power-on command is sent to the motor. After the motor receives the power-on command, it is initialized and other startup command confirmations can also be performed. In addition, when sending the power-on command, the controller can also give the initial second axis current command value of 0 and the initial second axis current intermediate conversion value of 0, so as to facilitate the smooth progress of the subsequent adjustment process.

[0110] In order to better understand the above embodiment, a detailed explanation is given below in conjunction with a specific embodiment. In one embodiment, the motor application equipment is a DC fan disk, and the motor control method is based on the constant torque DC control technology of a low-cost, low-power fan disk permanent magnet synchronous motor, adopts magnetic field oriented control, decouples the three-phase current of the motor stator, and designs a torque and current dual PI controller. According to the error between the stator flux and the torque, the amplitude of the stator flux is controlled in real time and the torque is kept within a certain tolerance band to ensure that the motor output torque is constant. The motor speed can be self-regulated when the external resistance changes. ( Figure 6 This is the block diagram of the permanent magnet synchronous motor constant torque control. According to the detected bus voltage and motor two-phase current, the MCU obtains the motor space vector torque / current model after a series of Clark and Park coordinate transformations, and estimates the motor rotor position and operating torque through the command torque T ref With running torque T fThe error integral amplification is used as the input of the PI regulator of the torque current loop of the rotating coordinate system q axis, and the three voltage vectors of the motor at the next time are output through the PI action, and transmitted to the motor by the inverter module. In this way, when the load is relatively stable, the output torque on the motor shaft remains constant; when the load changes, the error is continuously reduced through closed-loop regulation until the output torque is consistent with the command torque, achieving the effect of direct torque stability control.

[0111] According to the motor characteristic curve, its maximum output torque tends to decrease with the decrease of power supply voltage. In order to adapt to the complex and uncertain working environment of the unit, Figure 7 The motor load characteristic curve shows the approximate relationship between the motor torque and speed. The motor characteristic curve will be offset under different input voltage levels, so that the maximum output torque / speed of the motor at low voltage input is lower than that at rated voltage, and will not meet the rated high-frequency output requirements of the unit at a wide voltage (especially low voltage). However, in a wide range of practical applications, there may be power supply fluctuations or different power supply standards. How to ensure that the motor output can reach the rated torque in a wide voltage range, especially at low voltage, without increasing costs has become another major problem.

[0112] This application designs a wide voltage range motor weak magnetic torque compensation control strategy, and achieves the purpose of step-type torque compensation and weak magnetic speed regulation by adjusting the excitation flux according to different standard power supply conditions, focusing on solving the problems of insufficient maximum torque output and poor high-frequency speed regulation capability of the motor under low voltage input conditions. Ultimately, it ensures that the performance of the unit is not affected by voltage fluctuations in various countries and regions, and has stronger universal adaptability to different power supply standards.

[0113] The d-axis flux current loop of the rotating coordinate system, as the part of flux regulation, performs corresponding PI control according to the input voltage level, including:

[0114] Specifically, Figure 8 This is the step-type torque compensation control flow chart of this embodiment. After the unit is powered on, the controller first performs initialization and confirms the fan start command, and determines the command torque T according to the current gear position. ref value, and give the initial d-axis current command value Idref=0 and the initial d-axis current intermediate conversion value Id=0. According to the detected bus voltage V dc Determine the difference between it and the motor rated voltage V N If the bus voltage is less than the rated voltage, the flux linkage is adjusted, the voltage deviation between the bus voltage and the rated voltage is calculated in steps, the minimum voltage deviation unit ΔV is set, and K1 = (V N -V dc) / ΔV, rounded to the nearest integer, regarded as the deviation adjustment coefficient between the bus voltage and the rated voltage (or the torque step compensation coefficient), and the minimum d-axis current voltage adjustment unit corresponding to a voltage deviation unit ΔV is set to Δi dv , then the d-axis current command value after torque compensation is Idref=Id-K1Δi dv After the limiting process, Idref is used as the final d-axis current command to participate in the PI operation.

[0115] In addition, considering the extreme situation that the actual torque of the motor still cannot reach the maximum torque of the motor after torque compensation under low voltage, a second layer of real-time torque judgment is added (the basic principle is analogous to voltage deviation torque compensation): according to the estimated operating torque T f Determine its relationship with the maximum torque T of the motor max Relationship between: Under the premise that the command torque demand is the maximum torque, if the operating torque T f Less than the maximum torque T of the motor max , then the flux linkage is adjusted, the torque deviation between the real-time torque and the maximum torque of the motor is calculated in steps, the minimum torque deviation unit ΔT is set, and K2=(T max -T f ) / ΔT, rounded off to the nearest integer, regarded as the deviation adjustment coefficient between the operating torque and the maximum torque, and set the d-axis current minimum torque adjustment unit corresponding to a torque deviation unit ΔT to Δi dT , then the d-axis current command value after torque compensation is Idref=Id-K2Δi dT In this way, the dq axis current in the rotating coordinate system is transformed by Park to output the three voltage vectors of the motor at the next time, which are transmitted to the motor by the inverter module. Figure 6 As shown, dual closed-loop control is performed to stabilize the operation with the current torque. Wherein, Tf, Id, and Idref are calculated values, Idmax, K1, K2, ΔV, ΔT, Δidv, and ΔidT are calculated values, T ref and T max is a known quantity.

[0116] The method and content involved in this application have been verified by application on a low-power DC fan unit with a power lower than 100W. The test results are shown in Fig. 9, the motor can still control the maximum output torque deviation within ±0.005N·m under low voltage. The method and content involved in this application designs a weak magnetic torque compensation control strategy for a wide voltage range motor. By adjusting the excitation flux according to different standard levels of power supply conditions, the purpose of step-type torque compensation and weak magnetic speed regulation is achieved, focusing on solving the problems of insufficient maximum torque output and poor high-frequency speed regulation capability of the motor under low voltage input conditions. Ultimately, it ensures that the performance of the unit is not affected by voltage fluctuations in various countries and regions and has stronger universal adaptability to different power supply standards. Without adding other circuits, it can also meet the maximum output capacity requirements of the motor load at low voltage. The cost is greatly reduced and the effect is significant. The product can occupy a good market advantage under the current low-cost pressure control of household appliances.

[0117] The above motor control method first obtains the bus voltage and motor current, performs vector coordinate transformation on the motor current to obtain the operating torque, and then obtains the first axis current command value according to the operating torque and the command torque. The command torque is obtained according to the current gear of the motor. When the bus voltage is less than the rated voltage of the motor, the voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain the second axis current command value. The first axis current command value and the second axis current command value are then used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain the voltage vector, which is used to control the operation of the motor. This method is based on the bus voltage and adopts magnetic field oriented control. By decoupling the motor current, the operating torque is obtained, and the current PI controller is designed. The motor is feedback-regulated according to the error between the electronic flux and the torque, so that the motor torque is kept within a certain tolerance band, the motor output torque is stable, and the regulated voltage vector is used to control the motor operation, so that the motor can maintain stable torque output under different voltage inputs, improve the voltage adaptability of the motor, and is reliable in use.

[0118] In one embodiment, a motor control device is provided, including a parameter acquisition module, a coordinate transformation module, a first-axis current command value acquisition module, a second-axis current command value acquisition module and an inverse transformation module, wherein the parameter acquisition module is used to acquire the bus voltage and the motor current, the coordinate transformation module is used to perform vector coordinate transformation on the motor current to obtain the operating torque, the first-axis current command value acquisition module is used to obtain the first-axis current command value according to the operating torque and the command torque, the command torque is obtained according to the current gear of the motor, the second-axis current command value acquisition module is used to perform step calculation on the voltage deviation between the bus voltage and the rated voltage when the bus voltage is less than the rated voltage of the motor to obtain the second-axis current command value, and the inverse transformation module is used to use the first-axis current command value and the second-axis current command value as inputs of a current PI controller, perform inverse transformation on the output of the current PI controller to obtain a voltage vector, and the voltage vector is used to control the operation of the motor.

[0119] In one embodiment, the motor control device also includes a torque deviation adjustment module, which is used to obtain the first axis current command value according to the operating torque and the command torque by the first axis current command value acquisition module. In the inverse transformation module, the first axis current command value and the second axis current command value are used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain the voltage vector. When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, the torque deviation between the operating torque and the maximum torque of the motor is step-calculated to obtain the second axis current command value.

[0120] In one embodiment, the motor control device further includes a power-on module, which is used to send a power-on instruction to the motor before the parameter acquisition module acquires the bus voltage and the motor current, and the power-on instruction is used to control the motor to power on and initialize.

[0121] The specific contents of the motor control device correspond to the motor control method process described above and have been described in detail above, so they will not be repeated here.

[0122] The above motor control device first obtains the bus voltage and motor current, performs vector coordinate transformation on the motor current to obtain the operating torque, and then obtains the first axis current command value according to the operating torque and the command torque. The command torque is obtained according to the current gear of the motor. When the bus voltage is less than the rated voltage of the motor, the voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain the second axis current command value. The first axis current command value and the second axis current command value are then used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain the voltage vector, which is used to control the operation of the motor. The method is based on the bus voltage and adopts magnetic field oriented control. By decoupling the motor current, the operating torque is obtained, and the current PI controller is designed. The motor is feedback-regulated according to the error between the electronic flux and the torque, so that the motor torque is kept within a certain tolerance band, the motor output torque is stable, and the regulated voltage vector is used to control the motor operation, so that the motor can maintain stable torque output under different voltage inputs, improve the voltage adaptability of the motor, and is reliable in use.

[0123] In one embodiment, a motor device is provided, including a motor and the motor control device as described above. The motor device may be various motor drive devices such as a water pump, an air conditioning compressor, etc., for example, a fan or a fan disk.

[0124] In one embodiment, the motor device is a DC fan disk. DC fan disks have a high market share and have high cost requirements. The motor control device of the present application can achieve stable control of the motor torque without increasing the hardware cost, which is beneficial to improving the working performance of the DC fan disk and has good application prospects.

[0125] The above motor equipment first obtains the bus voltage and motor current, performs vector coordinate transformation on the motor current to obtain the operating torque, and then obtains the first axis current command value according to the operating torque and the command torque. The command torque is obtained according to the current gear of the motor. When the bus voltage is less than the rated voltage of the motor, the voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain the second axis current command value. The first axis current command value and the second axis current command value are then used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain the voltage vector, which is used to control the operation of the motor. The method is based on the bus voltage and adopts magnetic field oriented control. By decoupling the motor current, the operating torque is obtained, and the current PI controller is designed. The motor is feedback-regulated according to the error between the electronic flux and the torque, so that the motor torque is kept within a certain tolerance band, the motor output torque is stable, and the adjusted voltage vector is used to control the motor operation, so that the motor can maintain stable torque output under different voltage inputs, improve the voltage adaptability of the motor, and is reliable in use.

[0126] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0127] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A motor control method, characterized in that: The following steps are involved: Get bus voltage and motor current; Performing vector coordinate transformation on the motor current to obtain operating torque; A first axis current command value is obtained according to the operating torque and the command torque; the command torque is obtained according to the current gear position of the motor; When the bus voltage is less than the rated voltage of the motor, the voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain the second axis current command value; the step-calculation is to set a numerical range corresponding to a minimum unit, calculate the deviation between the two variables, and determine how many minimum units are included in the deviation between the two variables, which is the number of steps between the two variables; The first axis current command value and the second axis current command value are used as inputs of a current PI controller, and an output of the current PI controller is inversely transformed to obtain a voltage vector; the voltage vector is used to control the operation of the motor.

2. The motor control method according to claim 1, characterized in that: After obtaining the first axis current command value according to the operating torque and the command torque, the first axis current command value and the second axis current command value are used as inputs of a current PI controller, and the output of the current PI controller is inversely transformed to obtain a voltage vector, and the method further includes: When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value.

3. The motor control method according to claim 2, characterized in that: When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value, including: When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a torque deviation adjustment coefficient is obtained according to the operating torque, the maximum torque of the motor and a preset minimum torque deviation unit; The second axis current command value is obtained according to the torque deviation adjustment coefficient and a preset second axis current torque deviation minimum adjustment unit; the preset second axis current torque deviation minimum adjustment unit corresponds to the preset minimum torque deviation unit.

4. The motor control method according to claim 2, characterized in that: When the bus voltage is greater than or equal to the rated voltage of the motor, if the operating torque is less than the maximum torque of the motor, a step calculation is performed on the torque deviation between the operating torque and the maximum torque of the motor to obtain a second axis current command value, including: When the bus voltage is greater than or equal to the rated voltage of the motor, and under the premise that the command torque is the maximum torque of the motor, if the operating torque is less than the maximum torque of the motor, the torque deviation between the operating torque and the maximum torque of the motor is step-calculated to obtain the second axis current command value.

5. The motor control method according to claim 1, characterized in that: The step of performing vector coordinate transformation on the motor current to obtain the operating torque includes: Performing vector coordinate transformation on the motor current to obtain a motor space vector torque / current model; The operating torque is estimated based on the motor space vector torque / current model.

6. The motor control method according to claim 1, characterized in that: When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain a second axis current command value, including: When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is calculated step by step to obtain an intermediate value of the second axis current; The second axis current intermediate value is limited to obtain a second axis current command value.

7. The motor control method according to claim 1, characterized in that: When the bus voltage is less than the rated voltage of the motor, a voltage deviation between the bus voltage and the rated voltage is step-calculated to obtain a second axis current command value, including: When the bus voltage is less than the rated voltage of the motor, a voltage deviation adjustment coefficient is obtained according to the bus voltage, the rated voltage of the motor and a preset minimum voltage deviation unit; The second axis current command value is obtained according to the voltage deviation adjustment coefficient and a preset second axis current voltage deviation minimum adjustment unit; the preset second axis current voltage deviation minimum adjustment unit corresponds to the preset minimum voltage deviation unit.

8. The motor control method according to claim 1, characterized in that: The current PI controller includes a first current PI controller and a second current PI controller, wherein the first axis current command value and the second axis current command value are used as inputs of the current PI controller, and the output of the current PI controller is inversely transformed to obtain a voltage vector, including: Using the first axis current command value as the input of the first current PI controller, and outputting a first voltage signal; using the second axis current command value as an input of the second current PI controller and outputting a second voltage signal; The first voltage signal and the second voltage signal are inversely transformed to obtain a voltage vector.

9. The motor control method according to claim 1, characterized in that: Before obtaining the bus voltage and the motor current, the method further includes: Send a power-on command to the motor; the power-on command is used to control the motor to power on and initialize.

10. A motor control device, characterized in that: include: Parameter acquisition module, used to obtain bus voltage and motor current; A coordinate transformation module, used for performing vector coordinate transformation on the motor current to obtain a running torque; A first axis current command value acquisition module, used to obtain a first axis current command value according to the operating torque and the command torque; the command torque is obtained according to the current gear position of the motor; A second axis current command value acquisition module is used to perform step calculation on the voltage deviation between the bus voltage and the rated voltage to obtain the second axis current command value when the bus voltage is less than the rated voltage of the motor; the step calculation is to set a numerical range corresponding to a minimum unit, calculate the deviation between the two variables, and determine how many minimum units are included in the deviation between the two variables, which is the number of steps between the two variables; The inverse transformation module is used to use the first axis current command value and the second axis current command value as inputs of the current PI controller, and inversely transform the output of the current PI controller to obtain a voltage vector; the voltage vector is used to control the operation of the motor.

11. A motor device, characterized in that: The invention comprises a motor and the motor control device as claimed in claim 10.

12. The motor device according to claim 11, characterized in that The motor device is a DC fan disk.

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