Zero-vector modulation method, system and storage medium for low common mode voltage frequency

Abstract

The present invention provides a zero-vector modulation method, system and storage medium with low common-mode voltage frequency, which further reduces the frequency of the common-mode voltage on the basis of the commonly used NSPWM. The strategy consists of three sectors to form a voltage plane, and the basic vector of the synthetic reference vector in each sector remains unchanged, which will make the common-mode voltage in each 60° sector unchanged. In addition, the PWM waveform of the strategy is three-segment, and the frequency of the three-segment common-mode voltage is lower than that of the five-segment common-mode voltage. The method further reduces its frequency on the basis of reducing the common-mode voltage amplitude in the traditional NSPWM, and is suitable for occasions with strict requirements on the common-mode voltage. The present invention further increases the suppression effect on the common-mode voltage and further reduces the common-mode voltage frequency.

Description

Technical Field

[0001] The present invention relates to the field of motor technology, and in particular to a zero-vector modulation method, system and storage medium for low common-mode voltage frequency. Background Art

[0002] Vector control technology is a common method in motor drive, especially in the motor control part of electric vehicles, aerospace, energy storage and other fields. The most common driving method of this technology is PWM (pulse width modulation) inversion, which converts the DC voltage into a three-phase AC voltage through a voltage source inverter, and then drives a three-phase AC motor. The common SVPWM strategy has good characteristics in terms of THD of output voltage, fluctuation of output current, pulsation of bus voltage, etc., but the higher PWM frequency interacts with the parasitic capacitance, inductance and other parameters in the drive circuit, which will produce larger du / dt, di / dt, causing larger electromagnetic interference, causing voltage and current fluctuations, and the common-mode electromagnetic interference generated will cause shaft current to cause electrical corrosion of bearings, and will also interfere with components around the motor.

[0003] Therefore, suppressing electromagnetic interference helps to improve the reliability of the motor drive system and improve the control accuracy. The main methods for suppressing common mode voltage include: adding active and passive filters to hardware, designing special motor structures, optimizing inverter structures, improving modulation strategies, etc. In order to further increase the suppression effect of common mode voltage and further reduce its frequency, the present invention provides a zero-vector modulation method, system and storage medium with low common mode voltage frequency. Summary of the invention

[0004] Therefore, the embodiments of the present invention provide a zero-vector modulation method, system and storage medium for low common-mode voltage frequency, which further increase the suppression effect on the common-mode voltage and further reduce the common-mode voltage frequency.

[0005] To solve the above problems, the present invention provides a zero-vector modulation method for low common-mode voltage frequency, comprising: obtaining the state information of the current target motor to obtain first data, subtracting the first data from a first set value to obtain a first difference; the first difference passes through the proportional and integral link of the speed loop of the target motor to obtain a first current value; performing MTPA calculation according to the first current value to obtain a corresponding first-axis current; calculating the second data of the target motor according to the state information of the target motor, and performing calculation according to the second data to obtain a second-axis current; subtracting the first-axis current from the second-axis current to obtain a second difference; passing the second difference through the proportional and integral link of the current loop of the target motor to obtain a first-axis voltage; establishing a voltage coordinate system, dividing the voltage coordinate system plane into three sectors, performing sector judgment according to the first-axis voltage, and judging the sector in which the first-axis voltage is located; selecting three basic voltage vectors in the sector according to the sector judgment result, synthesizing the required voltage vector, and calculating the action time of the basic voltage vector, wherein the three basic vectors in sector I are U4 (100), U6 (110), and U2 (010), and the three basic vectors in sector II are U4 (100), U6 (110), and U2 (010). The three basic vectors in sector III are U2 (010), U3 (011), and U1 (001); the three basic vectors in sector III are U1 (001), U5 (101), and U4 (100); the target motor adopts a three-stage wave generation method in one PWM cycle; the common mode voltage of the target motor is adjusted and reduced according to the wave generation method and the action time.

[0006] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: the first data is obtained by setting the state information of the target motor, and the first difference is obtained by subtracting it from the first set value. This method can more conveniently obtain the first difference, and also have a better understanding of the current state of the target motor. At the same time, the first difference is calculated through the speed loop to quickly obtain the first current value, and the first axis current is obtained through the first current value, which makes the calculation of the first axis current more convenient and has a better foundation for subsequent calculations. The second axis current is then obtained through the state information of the target motor, and the second difference is obtained by subtracting it from the first axis current, and then the second axis current is obtained through the second The difference is used to obtain the first-axis voltage, which makes the method of obtaining the first-axis voltage simpler and faster. Subsequently, the first-axis voltage is substituted into the voltage coordinate system for sector judgment through setting, and the voltage coordinate system plane is divided into three sectors, which makes the sector judgment faster. At the same time, due to the setting of a three-stage wave generation method, the combination of the two can obtain a smaller common-mode voltage change frequency, and can also reduce the number of actions of the switching tube, thereby reducing the switching loss. At the same time, the setting of three sectors simplifies the algorithm, making the overall calculation faster and more convenient, and can better adapt to environmental conditions, thereby ensuring better suppression of common-mode voltage and improving the stability and safety of the motor.

[0007] In one example of the present invention, the state information of the current target motor is obtained to obtain first data, and the first data is subtracted from a first set value to obtain a first difference value, which includes: calculating the rotor electrical angle and speed of the target motor; subtracting the rotor electrical angle and speed from a given speed to obtain a speed difference; and calculating a first current value through the speed difference.

[0008] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by calculating the rotor electrical angle and speed of the target motor and performing a difference calculation with the given speed, the speed difference is quickly obtained, and the first current value can be calculated through the speed difference, so that the calculation of the first current value is more in line with reality, and at the same time, the grasp of the current motor situation is more accurate, thereby making the subsequent motor control and adjustment more convenient and quick, and thus better realizing the suppression of the motor common mode voltage, and ensuring the normal operation and stability of the motor.

[0009] In one example of the present invention, calculating the second data of the target motor according to the state information of the target motor, and calculating according to the second data to obtain the second axis current also includes: calculating the three-phase current of the target motor and performing Park transformation on the three-phase current to obtain the second axis current.

[0010] Compared with the existing technology, the technical effect achieved by adopting this technical solution is as follows: by setting the three-phase current of the target motor for calculation, and quickly obtaining the second axis current through Park transformation, the current can be quickly converted into the axis current, so that subsequent calculations can be better performed. This method is simple to calculate, can simplify the analysis and control of the system, and improves the calculation efficiency, thereby providing faster data support for subsequent adjustment of the motor, thereby ensuring more stable operation of the motor and better suppressing the common-mode voltage.

[0011] In one embodiment of the present invention, a voltage coordinate system is established, and the voltage coordinate system plane is divided into three sectors. According to the first axis voltage, sector determination is performed. Determining the sector where the first axis voltage is located further includes: transforming the first axis voltage coordinate to α - β Axis, sector judgment is performed to determine the specific location of the required voltage vector on the voltage plane.

[0012] Compared with the prior art, the technical effect achieved by adopting this technical solution is: by setting the coordinate transformation of the first axis voltage and then performing sector judgment, the current axis voltage can be better suitable for the subsequent sector judgment process, thereby making the sector judgment process simpler and faster, making the system's subsequent common mode voltage suppression process more efficient, and ensuring the stability of the motor.

[0013] In one embodiment of the present invention, the three sectors are divided according to the following ranges: inU α and U β for α and β The voltage of the shaft.

[0014] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: through this partitioning method, the voltage plane can be divided into three sectors, which is different from the traditional six sectors. This partitioning method simplifies the judgment rules of the sectors, which can make the subsequent vector selection more adaptable and improve the judgment efficiency of the system, thereby better suppressing the generation of common mode voltage, better ensuring the stability of the motor, and ensuring the safe use of the motor.

[0015] In an example of the present invention, multiple reference voltage vectors are calculated based on three sectors, and the method further includes: each sector is divided into two secondary sectors, wherein the basic voltage vectors selected by the two secondary sectors are the same.

[0016] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: by dividing each sector into two secondary sectors, and then setting the selected reference voltage vector to be the same, when the vector action sequence changes, the frequency of change of the common-mode voltage is reduced, thereby making the operation of the motor more stable. At the same time, this vector selection method can further reduce the number of actions of the switch tube, thereby reducing the loss of the switch, making the service life of the switch longer, and thus ensuring the service life and operation stability of the current motor.

[0017] In an embodiment of the present invention, calculating the action time corresponding to the plurality of reference voltage vectors according to the plurality of reference voltage vectors further includes: the action time is calculated according to the following formula: in, θ is the electrical angle between the basic voltage vector at the middle position of a sector and the reference voltage vector, T s is the PWM period, T 1 N1 , T 2 N1 , T 3 N1 is the action time of the three vectors, V ref is the magnitude of the reference voltage vector, U dc is the bus voltage amplitude.

[0018] Compared with the prior art, the technical effect achieved by adopting this technical solution is as follows: through the action time calculation method, the action time of each vector can be obtained more conveniently, so that the subsequent sector action can be more efficient. At the same time, the calculation method can better adapt to the vector action sequence and sector judgment rules of the current motor, and can better suppress the common-mode voltage of the motor, and reduce the frequency of change of the common-mode voltage, so that the current motor can be more stable. At the same time, it can also reduce the number of actions of the switching tube, reduce switching losses, and thus ensure the stable operation of the motor.

[0019] In one example of the present invention, a zero-free vector modulation system with a low common-mode voltage frequency is also provided. The zero-free vector modulation method as described above is applied to the zero-free vector modulation system, and the zero-free vector modulation system also includes: an acquisition module, the acquisition module is used to acquire the state information of the target motor; a calculation module, the calculation module is used to calculate the acquired state information and perform voltage coordinate system and sector calculations; a control module, the control module is used to control the target motor.

[0020] The zero-free vector modulation system has all the features of the above-mentioned zero-free vector modulation method, and therefore has the same technical effects, which will not be described in detail here.

[0021] The present invention also provides a readable storage medium, on which computer executable instructions are stored, wherein when the computer executable instructions are executed by a processor, the device where the storage medium is located is controlled to execute steps of implementing any of the above-mentioned zero-vector modulation methods.

[0022] After adopting the technical solution of the present invention, the following technical effects can be achieved:

[0023] (1) The first data is obtained by setting the state information of the target motor, and the first difference is obtained by subtracting it from the first set value. This method makes it more convenient to obtain the first difference and provides a better understanding of the current state of the target motor. At the same time, the first difference is calculated through the speed loop to quickly obtain the first current value, and the first axis current is obtained through the first current value, making the calculation of the first axis current more convenient and laying a better foundation for subsequent calculations. The second axis current is then obtained through the state information of the target motor, and the second difference is obtained by subtracting it from the first axis current, and then the first axis voltage is obtained through the second difference. The method for obtaining the first axis voltage is simpler and faster. The first axis voltage is subsequently substituted into the voltage coordinate system for sector judgment by setting. Since the voltage coordinate system plane is divided into three sectors, the sector judgment is faster. At the same time, since a three-segment wave generation method is set, the combination of the two can obtain a smaller common-mode voltage change frequency, and can also reduce the number of switching tube actions, thereby reducing switching losses. At the same time, the setting of three sectors simplifies the algorithm, making the overall calculation faster and more convenient, and can better adapt to environmental conditions, thereby ensuring better suppression of common-mode voltage and improving the stability and safety of the motor.

[0024] (2) By setting each sector to be divided into two secondary sectors, and then setting the selected reference voltage vector to be the same, when the vector action sequence changes, the frequency of change of the common-mode voltage is reduced, thereby making the operation of the motor more stable. At the same time, this vector selection method can further reduce the number of actions of the switch tube, thereby reducing the loss of the switch, making the service life of the switch longer, and thus ensuring the service life and operation stability of the current motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 A schematic flow chart of a zero-vector modulation method with low common-mode voltage frequency provided by an embodiment of the present invention;

[0027] Figure 2 It is one of the processes of sector division and synthesis of reference vectors of the present invention;

[0028] Figure 3 This is the second process of sector division and synthesis of reference vectors of the present invention;

[0029] Figure 4The three-phase PWM waveforms of five-segment and three-segment NSPWM within two PWM cycles;

[0030] Figure 5 The common mode voltage waveforms of the two sector judgment rules of the NSPWM of the present invention within two PWM cycles;

[0031] Figure 6 A module diagram of a zero-free vector modulation system provided by an embodiment of the present invention;

[0032] Figure 7 This is a schematic diagram of the structure of a readable storage medium according to Embodiment 2 of the present invention.

[0033] Description of reference numerals:

[0034] 100 is a zero-free vector modulation system; 110 is an acquisition module; 120 is a calculation module; 130 is a control module; 200 is a readable storage medium; and 210 is a computer executable instruction. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] [First embodiment]

[0037] See also Figure 1-Figure 6 The present invention provides a zero-vector modulation method with low common mode voltage frequency, comprising:

[0038] Step S100: Acquire the current state information of the target motor to obtain the first data, and perform a subtraction between the first data and the first set value to obtain the first difference; the first difference is passed through the proportional and integral link of the speed loop of the target motor to obtain the first current value; perform MTPA calculation according to the first current value to obtain the corresponding first axis current; calculate the second data of the target motor according to the state information of the target motor, and perform calculation according to the second data to obtain the second axis current; perform a subtraction between the first axis current and the second axis current to obtain the second difference; pass the second difference through the proportional and integral link of the current loop of the target motor to obtain the first axis voltage;

[0039] Step S200: establishing a voltage coordinate system, dividing the voltage coordinate system plane into three sectors, performing sector determination according to the first axis voltage, and determining the sector in which the first axis voltage is located; calculating a plurality of reference voltage vectors according to the three sectors, and calculating the action times corresponding to the plurality of reference voltage vectors according to the plurality of reference voltage vectors;

[0040] Step S300: the target motor adopts a three-stage wave generation mode within one PWM cycle; the common mode voltage of the target motor is adjusted and reduced according to the wave generation mode and action time.

[0041] Specifically, the first set value is a given speed, which is a manually set value. The target motor may be a three-phase motor, that is, the rotor electrical angle of the target three-phase motor is calculated. θ e With speed n The first set value is subtracted from the given speed, and the speed difference obtained is the first difference. The first difference is passed through the proportional and integral links of the speed loop to obtain the required current output, that is, the first current value.

[0042] Furthermore, the current output of the speed loop is calculated by MTPA to obtain the required dq axis current, i.e., the first axis current, and then the three-phase current of the target three-phase motor is calculated. After Park transformation, the actual dq axis current, i.e., the second axis current, is obtained and subtracted from the required dq axis current; the dq axis current difference, i.e., the second difference, is passed through the current loop proportional and integral links to obtain the required dq axis voltage, i.e., the first axis voltage.

[0043] Furthermore, a three-stage wave generation method is used to determine the on-off time of each phase bridge arm.

[0044] Specifically, the voltage plane is divided into three sectors of 120° electrical angle, such as Figure 2 and Figure 3 As shown, in each sector, the reference voltage vector is synthesized using the three basic vectors in the sector. For example, in sector I, U4, U6 and U2 are the basic vectors used. In sector I (1), the basic vectors selected are two vectors adjacent to the reference vector plus a vector on the left, and in sector I (2), the basic vectors selected are two vectors adjacent to the reference vector plus a vector on the right. This is also a feature that distinguishes the present invention from the commonly used NSPWM (near-state PWM) modulation without zero vector. For the vector action sequence of the present invention, at the switching moment, the last cycle ends at 100 and the next cycle begins at 100. Therefore, the sector judgment and vector selection rules of the present invention are combined with the vector action sequence of the commonly used NSPWM, which can reduce the number of actions of the switch tube, thereby reducing the switching loss.

[0045] Specifically, the second feature of the present invention is a simplified vector action sequence. The PWM action sequence of the present invention is: a three-stage method is used in one PWM cycle, U4-U6-U2, then the common mode voltage will only change twice, so the action sequence of the present invention can reduce the frequency of the common mode voltage, thereby further suppressing the common mode voltage. The three-stage PWM waveform of the present invention is different from the conventional five-stage PWM waveform. Figure 4As shown, it can be seen that within one PWM cycle, the five-stage type has two more switching operations than the three-stage type. However, at the switching moment of the PWM cycle, the three-stage type has two more switching operations, so the switching operations of the two are equivalent.

[0046] Specifically, by combining the first and second features of the present invention, a smaller common-mode voltage variation frequency can be obtained. When switching between sectors I (1) and I (2), the three-stage NSPWM is used in combination with the conventional vector action sequence. The three-stage NSPWM is used in combination with the vector action sequence of feature I of the present invention. Figure 5 As shown in the figure, the common mode voltage of the traditional vector action sequence changes when the sectors are switched, while the common mode voltage does not change when the action sequence of feature one is used. Therefore, feature one effectively reduces the number of common mode voltage changes when the 60° sector is switched, and reduces the frequency of change of the common mode voltage, further demonstrating the superiority of the vector action sequence of feature one of the present invention. In addition, by using the vector action sequence of feature one, the sector judgment can be reduced from six sectors to three sectors, simplifying the algorithm.

[0047] Preferably, the first data is obtained by setting the state information of the target motor, and the first difference is obtained by subtracting it from the first set value. This method makes it more convenient to obtain the first difference and also provides a better understanding of the current state of the target motor. At the same time, the first difference is calculated through the speed loop to quickly obtain the first current value, and the first axis current is obtained through the first current value, making the calculation of the first axis current more convenient and laying a better foundation for subsequent calculations. The second axis current is obtained through the state information of the target motor, and the second difference is obtained by subtracting it from the first axis current, and then the first axis current is obtained through the second difference. The voltage of the first axis is obtained by setting a three-segment wave generation method, which makes the method of obtaining the first axis voltage simpler and faster. Subsequently, the first axis voltage is substituted into the voltage coordinate system for sector judgment. Since the voltage coordinate system plane is divided into three sectors, the sector judgment is faster. At the same time, since a three-segment wave generation method is set, the combination of the two can obtain a smaller common-mode voltage change frequency, and can also reduce the number of actions of the switching tube, thereby reducing the switching loss. At the same time, the setting of three sectors simplifies the algorithm, making the overall calculation faster and more convenient, and can better adapt to environmental conditions, thereby ensuring better suppression of common-mode voltage and improving the stability and safety of the motor.

[0048] Specifically, the state information of the current target motor is obtained to obtain the first data, and the first data is subtracted from the first set value to obtain the first difference, which includes: calculating the rotor electrical angle and speed of the target motor; subtracting the rotor electrical angle and speed from the given speed to obtain the speed difference; and calculating the first current value through the speed difference.

[0049] Preferably, by calculating the rotor electrical angle and speed of the target motor and performing a difference calculation with a given speed, the speed difference is quickly obtained, and the first current value can be calculated through the speed difference, so that the calculation of the first current value is more in line with reality, and at the same time the grasp of the current motor condition is more accurate, thereby making the subsequent motor control and adjustment more convenient and quicker, and thus better suppressing the common mode voltage of the motor, thereby ensuring the normal operation and stability of the motor.

[0050] Specifically, calculating the second data of the target motor according to the state information of the target motor, and calculating according to the second data to obtain the second axis current also includes: calculating the three-phase current of the target motor, and performing Park transformation on the three-phase current to obtain the second axis current.

[0051] Preferably, by setting the calculation of the three-phase current of the target motor and quickly obtaining the second axis current through Park transformation, the current can be quickly converted into the axis current, so that subsequent calculations can be better performed. This method is simple to calculate, can simplify the analysis and control of the system, and improves the calculation efficiency, thereby providing faster data support for subsequent adjustment of the motor, thereby ensuring more stable operation of the motor and better suppressing the common mode voltage.

[0052] Specifically, a voltage coordinate system is established, and the voltage coordinate system plane is divided into three sectors. According to the first axis voltage, sector determination is performed. Determining the sector where the first axis voltage is located also includes: transforming the first axis voltage coordinate to α - β Axis, sector judgment is performed to determine the specific location of the required voltage vector on the voltage plane.

[0053] Preferably, by setting the coordinate transformation of the first axis voltage and then performing sector judgment, the current axis voltage can be better applied to the subsequent sector judgment process, thereby making the sector judgment process simpler and faster, making the system more efficient in suppressing the subsequent common mode voltage and ensuring the stability of the motor.

[0054] Specifically, the three sectors are divided according to the following ranges: in U α and U β for α and βThe voltage of the shaft. According to the sector judgment result, three basic voltage vectors in the sector are selected to synthesize the required voltage vector, and the action time of the basic voltage vector is calculated. The three basic vectors in sector I are U4 (100), U6 (110), and U2 (010); the three basic vectors in sector II are U2 (010), U3 (011), and U1 (001); the three basic vectors in sector III are U1 (001), U5 (101), and U4 (100);

[0055] Preferably, through this partitioning method, the voltage plane can be divided into three sectors, which is different from the traditional six sectors. This partitioning method simplifies the judgment rules of the sectors, which can make the subsequent vector selection more adaptable and improve the judgment efficiency of the system, thereby better suppressing the generation of common mode voltage, better ensuring the stability of the motor, and ensuring the safe use of the motor.

[0056] Specifically, multiple reference voltage vectors are calculated based on the three sectors, and the method further includes: each sector is divided into two secondary sectors, wherein the reference voltage vectors selected by the two secondary sectors are the same.

[0057] Preferably, each sector is divided into two secondary sectors, and the selected reference voltage vectors are set to be the same, so that when the vector action sequence changes, the frequency of change of the common-mode voltage is reduced, thereby making the operation of the motor more stable. At the same time, the vector selection method can further reduce the number of actions of the switching tube, thereby reducing the loss of the switch, making the service life of the switch longer, and thus ensuring the service life and operation stability of the current motor.

[0058] Specifically, calculating the action times corresponding to the multiple reference voltage vectors according to the multiple reference voltage vectors also includes: the action time is calculated according to the following formula: in, θ is the electrical angle between the basic voltage vector at the middle position of a sector and the reference voltage vector, T 1 N1 , T 2 N1 , T 3 N1 is the action time of the three basic voltage vectors, V ref is the magnitude of the reference voltage vector, U dc is the bus voltage amplitude.

[0059] Specifically,V ref is the magnitude of the reference voltage vector, U dc is the bus voltage amplitude. The above values ​​are obtained from experiments and can be adjusted according to actual conditions.

[0060] Preferably, the action time of each vector can be obtained more conveniently through the action time calculation method, so that the subsequent sector action can be more efficient. At the same time, the calculation method can better adapt to the vector action sequence and sector judgment rules of the current motor, so that the common mode voltage of the motor can be better suppressed, and the frequency of change of the common mode voltage can be reduced, so that the current motor can be more stable. At the same time, it can also reduce the number of actions of the switching tube and reduce switching losses, thereby ensuring the stable operation of the motor.

[0061] Specifically, a zero-free vector modulation system 100 with a low common-mode voltage frequency is also provided. The zero-free vector modulation method as described above is applied to the zero-free vector modulation system 100, and the zero-free vector modulation system 100 also includes: an acquisition module 110, the acquisition module 110 is used to acquire the state information of the target motor; a calculation module 120, the calculation module 120 is used to calculate the acquired state information and perform voltage coordinate system and sector calculations; a control module 130, the control module 130 is used to control the target motor.

[0062] The zero-free vector modulation system has all the features of the above-mentioned zero-free vector modulation method, and therefore has the same technical effects, which will not be described in detail here.

[0063] [Second embodiment]

[0064] See also Figure 7 The present invention also provides a readable storage medium 200, on which computer executable instructions 210 are stored, wherein when the computer executable instructions 210 are executed by a processor, the device where the storage medium is located is controlled to execute steps of implementing any of the above-mentioned zero-vector modulation methods.

[0065] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are only illustrative. For example, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist separately, or two or more modules can be integrated to form an independent part.

[0066] If the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods of various embodiments of the present invention. The aforementioned readable storage medium 200 includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zero-vector modulation method for low common mode voltage frequency, characterized in that: include: Acquire state information of the current target motor to obtain first data, and perform subtraction between the first data and a first set value to obtain a first difference value; The first difference is passed through a proportional and integral link of a speed loop of the target motor to obtain a first current value; Perform MTPA calculation according to the first current value to obtain a corresponding first axis current; Calculate second data of the target motor according to the state information of the target motor, and perform calculation according to the second data to obtain a second axis current; Subtract the first axis current from the second axis current to obtain a second difference value; Passing the second difference through the current loop proportional and integral link of the target motor to obtain a first shaft voltage; Establishing a voltage coordinate system, dividing the voltage coordinate system plane into three sectors, and performing sector determination according to the first axis voltage to determine the sector in which the first axis voltage is located; Transform the first axis voltage coordinates to α - β Axis, sector judgment is performed to determine the specific location of the required voltage vector on the voltage plane; The three sectors are divided according to the following ranges: in U α and U β for α and β Shaft voltage; According to the sector judgment result, three basic voltage vectors in the sector are selected to synthesize the required voltage vector, and the action time of the basic voltage vector is calculated. The three basic vectors in sector I are U4 (100), U6 (110), and U2 (010); the three basic vectors in sector II are U2 (010), U3 (011), and U1 (001); the three basic vectors in sector III are U1 (001), U5 (101), and U4 (100); The target motor adopts a three-stage wave generation method within one PWM cycle; The common mode voltage of the target motor is adjusted and reduced according to the wave generation mode and the action time.

2. The zero-vector modulation method for low common mode voltage frequency according to claim 1, characterized in that: The acquiring state information of the current target motor to obtain first data, and subtracting the first data from a first set value to obtain a first difference value comprises: Calculating the rotor electrical angle and rotation speed of the target motor; Calculate the difference between the rotation speed and the given rotation speed to obtain the rotation speed difference; The first current value is calculated according to the rotation speed difference.

3. The zero-vector modulation method for low common mode voltage frequency according to claim 1, characterized in that: The calculating the second data of the target motor according to the state information of the target motor, and performing calculation according to the second data to obtain the second axis current also includes: The three-phase current of the target motor is calculated, and the three-phase current is subjected to Park transformation to obtain the second axis current.

4. The zero-vector modulation method for low common mode voltage frequency according to claim 1, characterized in that: Also includes: Each sector is divided into two secondary sectors, wherein the basic voltage vector selected for the two secondary sectors is the same.

5. The zero-vector modulation method for low common mode voltage frequency according to claim 4, characterized in that: Also includes: The action time is calculated according to the following formula: in, θ is the electrical angle between the basic voltage vector at the middle position of a sector and the reference voltage vector, T s is the PWM period, T 1 N1 , T 2 N1 , T 3 N1 is the action time of the three basic voltage vectors, V ref is the magnitude of the reference voltage vector, U dc is the bus voltage amplitude.

6. A zero-vector modulation system with low common mode voltage frequency, characterized in that: The zero-free vector modulation method according to any one of claims 1 to 5 is applied to the zero-free vector modulation system, and the zero-free vector modulation system further comprises: An acquisition module, the acquisition module is used to acquire the state information of the target motor; A calculation module, the calculation module is used to calculate the acquired state information and perform the voltage coordinate system and sector calculation; A control module is used to control the target motor.

7. A readable storage medium, characterized in that: The readable storage medium stores computer executable instructions, wherein when the computer executable instructions are executed by a processor, the device where the storage medium is located is controlled to execute the steps of implementing the zero-vector modulation method according to any one of claims 1 to 5.

Images