Phase current reconstruction method and system, computer equipment and readable storage medium

Abstract

The invention provides a phase current reconstruction method and system, computer equipment and a readable storage medium, and belongs to the technical field of phase current reconstruction, and the method comprises the steps: installing a single current sensor on two branches of an inverter, so as to construct a dual-branch single current sensor circuit topological structure; dividing six sectors formed by the non-zero voltage vector to form twelve sub-sectors; and for each sub-sector, sampling the single current sensor in the action time of the non-zero voltage vector and the zero voltage vector of one PWM period to obtain current information of two different phases, and reconstructing a third-phase current of the motor according to the current information of the two different phases. The method has the advantages that the zero voltage vector and the non-zero voltage vector are introduced for each sub-sector in the twelve sub-sectors to perform current sampling and reconstruction, the problem of current reconstruction blind areas of a sector boundary area and a low modulation ratio area is solved, meanwhile, the current reconstruction mode is single, and the complexity of an algorithm during actual reconstruction is reduced.

Description

Technical Field

[0001] This invention relates to the field of phase current reconstruction technology, and in particular to a phase current reconstruction method and system, computer equipment and readable storage medium. Background Technology

[0002] With the rapid development of power electronics technology, high-performance permanent magnet materials such as neodymium iron boron have been widely studied and applied. The size and weight of permanent magnet synchronous motors (PMSMs) have been greatly reduced, and the power density has been significantly improved. Therefore, they have been widely used in aerospace, military, medical devices, new energy electric vehicles and other fields.

[0003] In the control system of permanent magnet synchronous motors, phase current is a crucial parameter for achieving closed-loop control and monitoring load status. To precisely control motor operation, it is necessary to acquire the motor's phase current information in real time and accurately.

[0004] Traditional current sensing methods use multiple current sensors to collect current information. These sensors are not only expensive, increasing the size and cost of the system, but the sampling differences between different sensors can also increase torque fluctuations in the entire system, limiting performance improvements. Therefore, phase current reconstruction technology has emerged. Phase current reconstruction technology uses algorithms to extract complete phase current information from data from a single current sensor, effectively solving the above problems and significantly reducing system size and cost.

[0005] However, existing phase current reconstruction methods for single current sensors have current reconstruction blind zones in sector boundary regions and low modulation ratio regions. Summary of the Invention

[0006] To address the above technical problems, the present invention provides a phase current reconstruction method; furthermore, it provides a phase current reconstruction system; yet another aspect provides a computer device; and still another aspect provides a readable storage medium.

[0007] The technical problem solved by this invention can be achieved by the following technical solutions:

[0008] On the one hand, a phase current reconstruction method is provided, including:

[0009] Step S1: Install the single current sensor on two branches of the inverter to construct a dual-branch single current sensor circuit topology.

[0010] Step S2: Divide the six sectors formed by the non-zero voltage vector into twelve sub-sectors;

[0011] Step S3: For each sub-sector, the single current sensor is sampled during the non-zero voltage vector and zero voltage vector action time of one PWM cycle to obtain the current information of two different phases, and the third phase current of the motor is reconstructed based on the current information of the two different phases.

[0012] Preferably, the inverter includes a first phase upper arm power transistor, a first phase lower arm power transistor, a second phase upper arm power transistor, a second phase lower arm power transistor, a third phase upper arm power transistor, and a third phase lower arm power transistor.

[0013] In step S1, the single current sensor is installed between the power transistor of the first phase upper arm and the power transistor of the second phase upper arm, and between the power transistor of the second phase lower arm and the power transistor of the third phase lower arm; or

[0014] The single current sensor is installed between the power transistor of the first phase upper arm and the power transistor of the second phase upper arm, and between the power transistor of the second phase upper arm and the power transistor of the second phase lower arm; or

[0015] The single current sensor is installed between the power transistors of the first phase upper arm and the second phase upper arm, and between the power transistors of the third phase upper arm and the third phase lower arm; or

[0016] The single current sensor is installed between the power transistor of the second phase upper arm and the power transistor of the third phase upper arm, and between the power transistor of the first phase lower arm and the power transistor of the second phase lower arm.

[0017] Preferably, the non-zero voltage vector forms six sectors, including sector I, sector II, sector III, sector IV, sector V, and sector VI. Step S2 further includes:

[0018] The six sectors are divided into two groups, with sectors II, III, V, and VI forming the first group and sectors I and IV forming the second group.

[0019] Each of the six sectors is divided equally to form the twelve sub-sectors; wherein, in the non-low modulation ratio region, one of the sampling vectors of each sub-sector is a non-zero voltage vector, and the other sampling vector is a zero voltage vector that samples a different phase current from the selected non-zero voltage vector.

[0020] Preferably, in step S2, the zero-voltage vectors of the two sub-sectors of any sector in the first group of sectors are the same;

[0021] The zero-voltage vectors of the two sub-sectors of any sector in the second group of sectors are different.

[0022] Preferably, the twelve sub-sectors include sub-sector I-1, sub-sector I-2, sub-sector II-1, sub-sector II-2, sub-sector III-1, sub-sector III-2, sub-sector IV-1, sub-sector IV-2, sub-sector V-1, sub-sector V-2, sub-sector VI-1, and sub-sector VI-2. Step S2 further includes:

[0023] The twelve sub-sectors are re-divided into six groups. Sub-sectors I-2 and II-1 form the first group, sub-sectors II-2 and III-1 form the second group, sub-sectors III-2 and IV-1 form the third group, sub-sectors IV-2 and V-1 form the fourth group, sub-sectors V-2 and VI-1 form the fifth group, and sub-sectors VI-2 and I-1 form the sixth group. In each group, the sampling vectors of the two sub-sectors are the same.

[0024] Preferably, one of the sampling vectors of the first group, the second group, and the third group is a zero voltage vector V0, and one of the sampling vectors of the fourth group, the fifth group, and the sixth group is a zero voltage vector V7.

[0025] Preferably, in step S3, in the low modulation ratio region of any sector, the zero voltage vector of one sub-sector is replaced with the adjacent non-zero voltage vector of the sector, and the zero voltage vector of the other sub-sector is replaced with the complementary vector of the adjacent non-zero voltage vector.

[0026] On the other hand, a phase current reconstruction system sampling by a dual-branch single current sensor is also provided for implementing the phase current reconstruction method as described above, including:

[0027] The topology building module is used to install a single current sensor on two branches of the inverter to build a dual-branch single current sensor circuit topology.

[0028] The partitioning module, connected to the topology construction module, is used to partition the six sectors formed by the non-zero voltage vectors into twelve sub-sectors;

[0029] The current sampling and reconstruction module, connected to the partitioning module, is used to sample the single current sensor for each sub-sector during the non-zero voltage vector and zero voltage vector action time of a PWM cycle, to obtain current information of two different phases, and to reconstruct the third phase current of the motor based on the current information of the two different phases.

[0030] In another aspect, a computer device is also provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the phase current reconstruction method as described above.

[0031] Furthermore, a readable storage medium is also provided, which stores computer instructions for causing a computer to perform the phase current reconstruction method as described above.

[0032] The advantages or beneficial effects of the technical solution of this invention are as follows:

[0033] The phase current reconstruction method proposed in this invention is based on sampling by a dual-branch single current sensor. Within one PWM cycle, for each of the twelve sub-sectors, zero voltage vector and non-zero voltage vector are introduced for sampling, thereby reconstructing the third phase current of the motor. This solves the current reconstruction blind zone in the sector boundary region and the low modulation ratio region. At the same time, the current reconstruction method is simple, which reduces the complexity of the algorithm during actual reconstruction. Attached Figure Description

[0034] Figure 1 This is a circuit topology diagram of an inverter in the existing technology;

[0035] Figure 2 The circuit topology diagram of the inverter is shown in the preferred embodiment of the present invention.

[0036] Figure 3 This is a flowchart illustrating the phase current reconstruction method in a preferred embodiment of the present invention.

[0037] Figure 4 This is a schematic diagram of twelve sub-sectors in a preferred embodiment of the present invention;

[0038] Figure 5 This is a block diagram of the phase current reconstruction system in a preferred embodiment of the present invention. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0042] The classic SVPWM control algorithm works based on Space Vector Pulse Width Modulation (SVPWM), using different state combinations of the inverter's six power transistors to generate eight basic voltage vectors. These vectors can form a hexagon in a three-phase stationary coordinate system, and all modulation methods revolve around this hexagon. The magnitude of the non-zero voltage vector is 2 / 3V. DC , where V DC This refers to the DC bus voltage. SVPWM achieves precise motor control by selecting appropriate combinations of non-zero and zero voltage vectors and synthesizing the required voltage vector for each sector according to the volt-second balance principle.

[0043] The following is an explanation of the voltage vector terminology in SVPWM:

[0044] Zero-voltage vector: including V0 (000) and V7 (111), the corresponding space voltage vector amplitude is zero. In motor control, the role of the zero-voltage vector is mainly to adjust the timing of switching state transitions in order to achieve smooth voltage output and reduce switching losses.

[0045] Effective vector: refers to the six basic spatial non-zero voltage vectors V1(001), V2(010), V3(011), V4(100), V5(101), and V6(110), which are spatially separated by 60° and have equal amplitudes, and are used to synthesize the required reference voltage vector.

[0046] Complementary vector: For any valid vector, its complementary vector is the valid vector that is 180° away from it in space. For example, the complementary vector of V1 (001) is V4 (100), the complementary vector of V2 (010) is V5 (101), and the complementary vector of V3 (011) is V6 (110).

[0047] like Figure 1As shown, the inverter includes a first-phase upper arm power transistor AH, a first-phase lower arm power transistor AL, a second-phase upper arm power transistor BH, a second-phase lower arm power transistor BL, a third-phase upper arm power transistor CH, and a third-phase lower arm power transistor CL. The source of the first-phase upper arm power transistor AH is connected to the drain of the first-phase lower arm power transistor AL, and this connection point is electrically connected to the first-phase winding of the permanent magnet synchronous motor. The source of the second-phase upper arm power transistor BH is connected to the drain of the second-phase lower arm power transistor BL, and this connection point is electrically connected to the second-phase winding of the permanent magnet synchronous motor. The source of the third-phase upper arm power transistor CH is connected to the drain of the third-phase lower arm power transistor CL, and this connection point is electrically connected to the third-phase winding of the permanent magnet synchronous motor. The drains of the first-phase upper arm power transistor AH, the second-phase upper arm power transistor BH, and the third-phase upper arm power transistor CH are respectively connected to the DC bus voltage V. DC The positive terminal of the transistor, and the sources of the first phase lower arm power transistor AL, the second phase lower arm power transistor BL, and the third phase lower arm power transistor CL are respectively connected to the DC bus voltage V. DC The negative electrode.

[0048] For ease of description, the various current branches of the inverter are labeled, such as... Figure 1 As shown, ① represents the current branch between the drain of the first phase upper arm power transistor AH and the drain of the second phase upper arm power transistor BH; ② represents the current branch between the drain of the second phase upper arm power transistor BH and the drain of the third phase upper arm power transistor CH; ③ represents the current branch between the source of the first phase lower arm power transistor AL and the source of the second phase lower arm power transistor BL; ④ represents the current branch between the source of the second phase lower arm power transistor BL and the source of the third phase lower arm power transistor CL; ⑤ represents the current branch between the source of the first phase upper arm power transistor AH and the drain of the first phase lower arm power transistor AL; ⑥ represents the current branch between the source of the second phase upper arm power transistor BH and the drain of the second phase lower arm power transistor BL; ⑦ represents the current branch between the source of the third phase upper arm power transistor CH and the drain of the third phase lower arm power transistor CL; ⑧ represents the DC bus voltage V. DC The current branch between the negative terminal and the source terminal of the first phase lower bridge arm power transistor AL.

[0049] Let i a i b i c This refers to the three-phase winding current of the permanent magnet synchronous motor, and it is defined that the direction of current flowing into the permanent magnet synchronous motor is positive, and the direction of current flowing out of the permanent magnet synchronous motor is negative.

[0050] The current reconstruction technique of this embodiment is a sampling method for the inverter branches. A single Hall current sensor 100 is installed on two branches of the inverter to sample the sum of the currents of the two branches.

[0051] More specifically, the combination of two branches can be any of the following combinations:

[0052] Branch combination ①+④: That is, a single current sensor is installed between the power transistor AH of the first phase upper arm and the power transistor BH of the second phase upper arm, and between the power transistor BL of the second phase lower arm and the power transistor CL of the third phase lower arm.

[0053] Branch combination ①+⑥: That is, a single current sensor is installed between the power transistor AH of the first phase upper arm and the power transistor BH of the second phase upper arm, and between the power transistor BH of the second phase upper arm and the power transistor BL of the second phase lower arm.

[0054] Branch combination ①+⑦: That is, a single current sensor is installed between the power transistor AH of the first phase upper arm and the power transistor BH of the second phase upper arm, and between the power transistor CH of the third phase upper arm and the power transistor CL of the third phase lower arm.

[0055] Branch combination ②+③: That is, a single current sensor is installed between the power transistor BH of the upper arm of the second phase and the power transistor CH of the upper arm of the third phase, and between the power transistor AL of the lower arm of the first phase and the power transistor BL of the lower arm of the second phase.

[0056] This embodiment uses branch combination ①+④ as an example for detailed explanation, such as... Figure 2 As shown, phase current reconstruction is achieved by simultaneously sampling the currents of two branches ①+④. This requires the use of a Hall current sensor 100, which has a through-hole in the middle to allow the current to pass through both branches simultaneously, thus sampling the sum of the currents in the two branches.

[0057] Therefore, the relationship between the Hall current sensor sampling current and the winding phase current under the eight voltage vectors in the classic SVPWM control algorithm is shown in Table 1.

[0058] Table 1 shows the relationship between the Hall current sensor sampling current and the winding phase current under different voltage vectors.

[0059]

[0060]

[0061] In the classic vector control algorithm, the basic idea of ​​phase current reconstruction technology is to sample a single current sensor within a PWM cycle at different voltage vector action times. If two different phase currents can be sampled under two different voltage vectors within a PWM cycle, then the three-phase winding current of the motor can be calculated based on these sampling results.

[0062] From the current sensor sampling results corresponding to each voltage vector in Table 1, it can be seen that current can be collected from all six non-zero voltage vectors and two zero voltage vectors. However, if only the sampling results of the non-zero voltage vectors are used, it cannot be guaranteed that different currents in two phases can be collected within one PWM cycle. Therefore, phase current reconstruction can be achieved by simultaneously using the sampling results of both non-zero and zero voltage vectors within one PWM cycle. Using this method, phase current reconstruction can be completed in each sector as long as the non-zero voltage vector and the zero voltage vector, whose sums of the currents of the two branches are different.

[0063] See Figure 3 In a preferred embodiment of the present invention, based on the above-mentioned problems existing in the prior art, a phase current reconstruction method is provided, comprising:

[0064] Step S1: Install the single current sensor on two branches of the inverter. Taking branch combination ①+④ as an example, construct a dual-branch single current sensor circuit topology.

[0065] Step S2: Divide the six sectors formed by the non-zero voltage vector into twelve sub-sectors;

[0066] Among them, Figure 4 As shown, the non-zero voltage vector forms six sectors, including sector I, sector II, sector III, sector IV, sector V, and sector VI.

[0067] Each of the six sectors is divided equally to form twelve sub-sectors. The twelve sub-sectors are sub-sectors I-1, I-2, II-1, II-2, III-1, III-2, IV-1, IV-2, V-1, V-2, VI-1, and VI-2. In the non-low modulation ratio region, one sampling vector of each sub-sector is a non-zero voltage vector, and the other sampling vector is a zero voltage vector that samples a different phase current from the selected non-zero voltage vector.

[0068] Step S2 further includes: dividing the six sectors into two groups according to the different problems encountered in phase current reconstruction, wherein sectors II, III, V, and VI are the first group of sectors G1, and sectors I and IV are the second group of sectors G2, and the modification ideas of their PWM modulation methods are as follows:

[0069] (1) In sectors II, III, V and VI, since their adjacent non-zero voltage vectors are equal, zero voltage vectors V0 and V7 are introduced.

[0070] Within its eight sub-sectors, one sampling vector can be selected from the fundamental non-zero voltage vector contained within each sub-sector. For the other sampling vector, a zero-voltage vector sampling a different current than the selected fundamental non-zero voltage vector can be chosen. For example, in sub-sector II-1, non-zero voltage vector V2 can be selected as one sampling vector, while for the other sampling vector, since the current sampled by non-zero voltage vector V2 is i... a Therefore, a zero-voltage vector V0 can be selected that is different from the sampled current. The current sampled by the zero-voltage vector V0 is i. c This allows for the acquisition of two different phase currents, thus enabling phase current reconstruction. Similarly, the selection of sampling vectors for other sub-sectors follows the same principle, and will not be elaborated upon here.

[0071] (2) Within sectors I and IV, different non-zero voltage vectors and zero voltage vectors are selected as sampling vectors in the four sectors they are divided into. For example, in sub-sector I-1, V1 is selected as one of the sampling vectors, and its sampling current is i. c In order to complete the phase current reconstruction, the zero voltage vector V7 is selected as another sampling vector. Similarly, in sub-sector I-2, V2 and V0 are selected as sampling vectors, in sub-sector IV-1, V4 and V0 are selected as sampling vectors, and in sub-sector IV-2, V5 and V7 are selected as sampling vectors.

[0072] Both the first group of sectors G1 and the second group of sectors G2 use non-zero voltage vectors and zero voltage vectors to collect phase current in each sub-sector. The difference is that any sector in the first group of sectors G1 requires a total of three voltage vectors, while any sector in the second group of sectors G2 requires four voltage vectors.

[0073] For the first group, taking sector II as an example. In sub-sector II-1, non-zero voltage vector V2 and zero voltage vector V0 are selected to complete phase current reconstruction; in sub-sector II-2, non-zero voltage vector V3 and zero voltage vector V0 are selected to complete phase current reconstruction. At this point, it can be seen that sector II uses only three voltage vectors in total: non-zero voltage vector V2, non-zero voltage vector V3, and zero voltage vector V0.

[0074] For the second group, taking sector I as an example, in sub-sector I-1, a non-zero voltage vector V1 and a zero voltage vector V7 are required to complete phase current reconstruction; in sub-sector I-2, a non-zero voltage vector V2 and a zero voltage vector V0 are required to complete phase current reconstruction. Thus, sector I uses a total of four voltage vectors: non-zero voltage vectors V1 and V2, and zero voltage vectors V7 and V0.

[0075] In summary, the zero-voltage vectors of the two sub-sectors of any sector in the first group of sectors are the same, meaning that any sector in the first group of sectors uses a total of three voltage vectors; the zero-voltage vectors of the two sub-sectors of any sector in the second group of sectors are different, meaning that any sector in the second group of sectors uses a total of three voltage vectors.

[0076] For ease of understanding, Table 2 provides the sampling vector and corresponding sampling results for each sub-sector.

[0077] Table 2 shows the sampling vectors and corresponding sampling results for each sub-sector.

[0078]

[0079]

[0080] It should be noted that the combination of sampling vectors for each sub-sector shown in Table 2 is only an example and will not be enumerated here, but all of them should be within the protection scope of this invention.

[0081] As shown in Table 2, although this phase current reconstruction method divides the traditional six sectors of SVPWM into twelve sub-sectors, the sampling of the sampling vector in the subsequent control algorithm can still re-divide the twelve sub-sectors into six groups. Sub-sectors I-2 and II-1 form the first group, II-2 and III-1 the second group, III-2 and IV-1 the third group, IV-2 and V-1 the fourth group, V-2 and VI-1 the fifth group, and VI-2 and I-1 the sixth group. The sampling vectors of the two sub-sectors within each group are identical.

[0082] Step S3: For each sub-sector, the single current sensor is sampled during the non-zero voltage vector and zero voltage vector action time of one PWM cycle to obtain the current information of two different phases, and the third phase current of the motor is reconstructed based on the current information of the two different phases.

[0083] Specifically, sampling was performed according to Table 2 above. The non-zero voltage vector and the duration of zero voltage vector action during each group sampling are as follows:

[0084] Sub-sectors I-2 and II-1: Zero voltage vector is V0, sampling current is +i c The non-zero voltage vector is V2, and the sampling result is -i. a ;

[0085] Sub-sectors II-2 and III-1: Zero voltage vector is V0, sampling current is +i c The non-zero voltage vector is V3, and the sampling result is -i.a ;

[0086] Sub-sectors III-2 and IV-1: Zero voltage vector is V0, sampling current is +i c The non-zero voltage vector is V4, and the sampling result is -i. a ;

[0087] Sub-sectors IV-2 and V-1: Zero voltage vector is V7, sampling current is -i a The non-zero voltage vector is V5, and the sampling result is +i. c ;

[0088] Sub-sectors V-2 and VI-1: Zero voltage vector is V7, sampling current is -i a The non-zero voltage vector is V6, and the sampling result is +i. c ;

[0089] Sub-sectors VI-2 and I-1: Zero voltage vector is V7, sampling current is -i a The non-zero voltage vector is V1, and the sampling result is +i. c .

[0090] More specifically, since one of the sampling vectors in the first, second, and third groups is a zero-voltage vector V0, and one of the sampling vectors in the fourth, fifth, and sixth groups is a zero-voltage vector V7, switching between different groups only requires switching another sampling vector to complete the phase current sampling. Furthermore, the sampling results show that the current collected in each group is +i. c ,-i a .

[0091] Finally, according to the formula +i b =-i a -i c The third-phase current can then be calculated. This completes the acquisition of the three-phase current.

[0092] According to the sampling method in Table 2 above, there is no boundary reconstruction blind zone in the sector boundary region, but there is a phase current reconstruction blind zone in the low / high modulation ratio region.

[0093] For the sector boundary region, the sampling method used is to maintain the traditional SVPWM control algorithm, and one of the sampling vectors is the zero voltage vector (V0 or V7). The sampling point based on the zero voltage vector (V0 or V7) fully satisfies the sampling conditions in the sector boundary region and does not introduce a reconstruction blind zone, while the other sampling point is determined based on the sub-sectors within each sector.

[0094] For the first group of sectors G1, when the voltage vector is located in sub-sector II-1, if the reference voltage vector Vref Having just entered sector II from sector I, if the duration of the non-zero voltage vector V2 within each switching cycle is long enough to fully meet the minimum sampling time requirement, then sampling is performed under the non-zero voltage vector V2. When the reference voltage vector V... ref As the rotation continues, gradually moving from sub-sector II-1 to sub-sector II-2, the duration of the non-zero voltage vector V2 gradually decreases until it reaches the sector boundary region between sector II and sector III. At this point, the duration of the non-zero voltage vector V2 no longer meets the minimum sampling time requirement, and continuing to use the non-zero voltage vector V2 as the sampling vector will introduce a reconfiguration dead zone. Therefore, the non-zero voltage vector V3 is replaced as the sampling vector. Based on the above sampling method, the current sampled using the zero voltage vector V0 can complete the three-phase current reconfiguration within each switching cycle. By switching the sampling vector once, there is no reconfiguration dead zone in the boundary region of the entire sector II. Similarly, the remaining sectors III, V, and VI are similar to sector II and also do not have boundary reconfiguration dead zones, which will not be elaborated further here.

[0095] For the second group of sectors G2, it is similar to the first group of sectors G1, but in addition to switching the non-zero voltage vector, it also needs to switch the corresponding zero voltage vector. For example, when the reference voltage vector V ref Located in sub-sector I-1, the non-zero voltage vector V1 and the zero voltage vector V7 are used as sampling vectors; when the reference voltage vector V ref As we gradually move from sub-sector I-1 to sub-sector I-2, the duration of the non-zero voltage vector V1 gradually decreases until it no longer meets the minimum sampling time requirement. In addition to replacing V1 with a non-zero voltage vector V2 as the sampling vector, to meet the phase current reconstruction requirements, zero voltage vector V0 must also be used instead of V7. This allows for three-phase current reconstruction to be completed within each switching cycle. This method also ensures that there is no reconstruction blind zone in the boundary region of the entire I-sector. Similarly, sector IV, like sector I, also has no boundary reconstruction blind zone.

[0096] In a preferred embodiment, in step S3, in the low modulation ratio region of any sector, the zero voltage vector of one sub-sector is replaced with the adjacent non-zero voltage vector of the sector, and the zero voltage vector of the other sub-sector is replaced with the complementary vector of the adjacent non-zero voltage vector.

[0097] For the low modulation ratio region, the traditional SVPWM algorithm is modified using the Advanced Zero Sequence Pulse Width Modulation (AZSPWM) method. That is, when the duration of the effective vector used for sampling is too short, that is, when it is in the low modulation ratio region, in each PWM cycle, one of the zero voltage vectors is converted into the effective vector adjacent to the sector, and the other zero voltage vector is converted into the complementary vector of the adjacent effective vector.

[0098] For example, in sector I, by replacing the original zero voltage vectors V0 and V7 with effective non-zero voltage vectors V3 and V6 respectively, and performing current sampling under non-zero voltage vectors V3 and V6, two different phase currents i can be obtained. a and i c This allows for current reconfiguration.

[0099] The vector synthesis formula under the traditional SVPWM control algorithm is shown in the following formula (1):

[0100] T s V ref =T1V1+T2V2+T0V0+T7V7 (1)

[0101] The vector synthesis formula under the AZSPWM control algorithm is shown in the following formula (2):

[0102] T s V ref =T1V1+T2V2+T0V6+T7V3 (2)

[0103] Since the non-zero voltage vector V6 and the non-zero voltage vector V3 have the same magnitude but are 180° out of phase, we can obtain:

[0104] T0V0+T7V7=T0V6+T7V3=0

[0105] In the above formula, V1, V2, V0, V7, V6, and V3 represent the magnitude (V) of each voltage vector, respectively.

[0106] T1, T2, T0, T7, T6, and T3 represent the duration (s) of each voltage vector;

[0107] V ref This represents the magnitude (V) of the reference voltage vector.

[0108] T s This indicates the duration of one PWM cycle (s).

[0109] Therefore, it can be seen that introducing two effective vectors in the low modulation ratio region does not affect the synthesis of the reference voltage vector. In other words, the above method can eliminate the current reconstruction dead zone in the low modulation ratio region without affecting the synthesis of the reference voltage vector.

[0110] See Figure 5 The present invention also provides a phase current reconstruction system for dual-branch single-current sensor sampling, used to implement the phase current reconstruction method as described above, including:

[0111] Topology building module 1 is used to install a single current sensor on two branches of the inverter to build a dual-branch single current sensor circuit topology.

[0112] The partitioning module 2, connected to the topology construction module 1, is used to partition the six sectors formed by the non-zero voltage vectors into twelve sub-sectors;

[0113] The current sampling and reconstruction module 3 is connected to the partitioning module 2. It is used to sample the single current sensor for each sub-sector during the non-zero voltage vector and zero voltage vector action time of a PWM cycle, obtain the current information of two different phases, and reconstruct the third phase current of the motor based on the current information of the two different phases.

[0114] Specifically, this invention proposes a phase current reconstruction method based on dual-branch single-current sensor sampling, addressing the traditional DC bus sampling phase current reconstruction technique. It also proposes corresponding solutions to the blind zone issues in the sector boundary region and low modulation ratio region current reconstruction blind zone of this method. Compared to the traditional DC bus sampling method, this reconstruction method eliminates the need for cumbersome judgment processes and complex compensation algorithms when eliminating blind zones. It can effectively solve the blind zone issues in the space vector hexagonal sector boundary region and low modulation ratio region. Furthermore, the current reconstruction algorithm is simple, reducing the complexity of the algorithm during actual reconstruction.

[0115] The present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the phase current reconstruction method as described above.

[0116] Furthermore, the present invention also provides a readable storage medium storing computer instructions, wherein the computer instructions are used to cause a computer to execute the phase current reconstruction method as described above.

[0117] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, permanent magnet synchronous motor, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0118] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made using the content of this specification and illustrations should be included within the protection scope of the present invention.

Claims

1. A phase current reconstruction method, characterized in that, include: Step S1: Install the single current sensor on two branches of the inverter to construct a dual-branch single current sensor circuit topology. Step S2: Divide the six sectors formed by the non-zero voltage vector into twelve sub-sectors; Step S3: For each sub-sector, the single current sensor is sampled during the non-zero voltage vector and zero voltage vector action time of one PWM cycle to obtain the current information of two different phases, and the third phase current of the motor is reconstructed based on the current information of the two different phases.

2. The phase current reconstruction method according to claim 1, characterized in that, The inverter includes a first phase upper arm power transistor, a first phase lower arm power transistor, a second phase upper arm power transistor, a second phase lower arm power transistor, a third phase upper arm power transistor, and a third phase lower arm power transistor. In step S1, the single current sensor is installed between the power transistor of the first phase upper arm and the power transistor of the second phase upper arm, and between the power transistor of the second phase lower arm and the power transistor of the third phase lower arm; or The single current sensor is installed between the power transistor of the first phase upper arm and the power transistor of the second phase upper arm, and between the power transistor of the second phase upper arm and the power transistor of the second phase lower arm; or The single current sensor is installed between the power transistors of the first phase upper arm and the second phase upper arm, and between the power transistors of the third phase upper arm and the third phase lower arm; or The single current sensor is installed between the power transistor of the second phase upper arm and the power transistor of the third phase upper arm, and between the power transistor of the first phase lower arm and the power transistor of the second phase lower arm.

3. The phase current reconstruction method according to claim 1, characterized in that, The non-zero voltage vector forms six sectors, including sector I, sector II, sector III, sector IV, sector V, and sector VI. Step S2 further includes: The six sectors are divided into two groups, with sectors II, III, V, and VI forming the first group and sectors I and IV forming the second group. Each of the six sectors is divided equally to form the twelve sub-sectors; wherein, in the non-low modulation ratio region, one of the sampling vectors of each sub-sector is a non-zero voltage vector, and the other sampling vector is a zero voltage vector that samples a different phase current from the selected non-zero voltage vector.

4. The phase current reconstruction method according to claim 3, characterized in that, In step S2, the zero voltage vectors of the two sub-sectors of any one sector in the first group of sectors are the same. The zero-voltage vectors of the two sub-sectors of any sector in the second group of sectors are different.

5. The phase current reconstruction method according to claim 1, characterized in that, The twelve sub-sectors include sub-sector I-1, sub-sector I-2, sub-sector II-1, sub-sector II-2, sub-sector III-1, sub-sector III-2, sub-sector IV-1, sub-sector IV-2, sub-sector V-1, sub-sector V-2, sub-sector VI-1, and sub-sector VI-2. Step S2 further includes: The twelve sub-sectors are re-divided into six groups. Sub-sectors I-2 and II-1 form the first group, sub-sectors II-2 and III-1 form the second group, sub-sectors III-2 and IV-1 form the third group, sub-sectors IV-2 and V-1 form the fourth group, sub-sectors V-2 and VI-1 form the fifth group, and sub-sectors VI-2 and I-1 form the sixth group. In each group, the sampling vectors of the two sub-sectors are the same.

6. The phase current reconstruction method according to claim 5, characterized in that, One of the sampling vectors of the first group, the second group, and the third group is a zero voltage vector V0, and one of the sampling vectors of the fourth group, the fifth group, and the sixth group is a zero voltage vector V7.

7. The phase current reconstruction method according to claim 1, characterized in that, In step S3, in the low modulation ratio region of any sector, the zero voltage vector of one sub-sector is replaced with the adjacent non-zero voltage vector of the sector, and the zero voltage vector of the other sub-sector is replaced with the complementary vector of the adjacent non-zero voltage vector.

8. A phase current reconstruction system, characterized in that, A method for implementing the phase current reconstruction method as described in any one of claims 1-7, comprising: The topology building module is used to install a single current sensor on two branches of the inverter to build a dual-branch single current sensor circuit topology. The partitioning module, connected to the topology construction module, is used to partition the six sectors formed by the non-zero voltage vectors into twelve sub-sectors; The current sampling and reconstruction module, connected to the partitioning module, is used to sample the single current sensor for each sub-sector during the non-zero voltage vector and zero voltage vector action time of a PWM cycle, to obtain current information of two different phases, and to reconstruct the third phase current of the motor based on the current information of the two different phases.

9. A computer device, characterized in that, It includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the program, implements the phase current reconstruction method as described in any one of claims 1-7.

10. A readable storage medium, characterized in that, The readable storage medium stores computer instructions, wherein the computer instructions are used to cause the computer to perform the phase current reconstruction method as described in any one of claims 1-7.

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