Pulse width modulation method and three-phase inverter

Abstract

The embodiment of the invention discloses a pulse width modulation method and a three-phase inverter. The pulse width modulation method is applied to the three-phase inverter, the three-phase inverter comprises a three-level inversion topology circuit, and the pulse width modulation method comprises the following steps: acquiring a basic vector of the three-level inversion topology circuit; the basic vectors comprise thirteen vectors; dividing a vector space formed by the basic vectors into a large sector, a middle sector and a small sector according to thirteen vectors in the basic vectors; based on a preset modulation reference signal and the symmetry of the sectors, the large sector, the medium sector and the small sector are judged, and the sector where the space voltage vector is located is determined; according to the sector where the space voltage vector is located, the action time of the basic vector is determined, and the overturning moment and driving configuration of the pulse width modulation signal are determined based on the symmetry of the sector and the action time of the basic vector. According to the pulse width modulation method and the three-phase inverter provided by the embodiment of the invention, the operand can be reduced, and the operation complexity can be reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to pulse width modulation technology, and more particularly to a pulse width modulation method and a three-phase inverter. Background Technology

[0002] Pulse width modulation (PWM) technology is widely used in inverters. By controlling the on / off duration of the switching transistors in the inverter, the output of the inverter can be changed, making it a very effective technique for inverter control. However, existing PWM methods involve a large amount of computation and are complex in the PWM process. Summary of the Invention

[0003] This invention provides a pulse width modulation method and a three-phase inverter to reduce the amount of computation and lower computational complexity.

[0004] In a first aspect, embodiments of the present invention provide a pulse width modulation method applied to a three-phase inverter, the three-phase inverter including a three-level inverter topology circuit, the pulse width modulation method comprising:

[0005] Obtain the basic vector of the three-phase inverter; the basic vector includes thirteen vectors.

[0006] Based on the thirteen basic vectors, the vector space formed by the basic vectors is divided into large sectors, medium sectors, and small sectors; the number of small sectors is twice the number of medium sectors.

[0007] Based on the preset modulation reference signal and the symmetry of the sector, the large sector, medium sector and small sector are determined to identify the sector where the space voltage vector is located;

[0008] Based on the sector where the space voltage vector is located, the duration of the basic vector is determined. Based on the symmetry of the sector and the duration of the basic vector, the flip-off time and driving configuration of the pulse width modulation signal are determined. The pulse width modulation signal is used to drive the three-level inverter topology circuit. When the basic vector used by the space voltage vector is transformed, the switching states of two-phase switches in the three-level inverter topology circuit change simultaneously.

[0009] Optionally, dividing the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors includes:

[0010] The vector space formed by the thirteen basic vectors is divided into a first large sector of 0°-120°, a second large sector of 120°-240°, and a third large sector of 240°-0°. Each large sector is divided into two medium sectors by its respective angle bisector, and each medium sector is divided into two small sectors by its respective angle bisector. The sector numbers of each large sector, each medium sector, and each small sector are determined.

[0011] Optionally, the step of determining the large, medium, and small sectors based on a preset modulation reference signal to identify the sector where the space voltage vector resides includes:

[0012] Based on preset modulation reference signals Vα and Vβ, the preset modulation reference signals Vα and Vβ are normalized to obtain normalized modulation reference signals Vα1 and Vβ1.

[0013] Based on the normalized modulation reference signals Vα1 and Vβ1, the calculated values ​​A and B are obtained, where A = Vα1 and B = Vβ1 / ;

[0014] Based on the relationship between the calculated value B and 0, and the relationship between the sum and / or subtraction of the calculated values ​​A and B and 0, the sector number of the large sector where the space voltage vector is located is determined;

[0015] Based on the sector number of the large sector where the space voltage vector is located, m and n are represented by a preset equation of A and / or B, and the sector number of the middle sector where the space voltage vector is located is determined according to the magnitude of m and n. m and n are the projection values ​​of the composite vector of Vα1 and Vβ1 on the 0-degree coordinate axis and the 120-degree coordinate axis of the 120-degree coordinate system, respectively.

[0016] Based on sector symmetry and the large and medium sectors where the space voltage vector is located, the sector number of the small sector where the space voltage vector is located is determined according to the preset relationship between m and n.

[0017] Optionally, each of the aforementioned small sectors corresponds to a basic vector V1, V2, V3, V4, V5;

[0018] The step of determining the duration of action of the basic vector based on the sector where the space voltage vector is located includes:

[0019] When the space voltage vector is located in the first middle sector of the first large sector, the functional relationship between T0, T1, and T2 with respect to m, n, and T is determined according to the small sector where the space voltage vector is located, and T0, T1, and T2 are determined based on the functional relationship; where T is the switching period of the pulse width modulation signal, T0 is the duration of action of the basic vectors V1 and V5 in one switching period, T1 is the duration of action of the basic vectors V2 and V4 in one switching period, and T2 is the duration of action of the basic vector V3 in one switching period.

[0020] Optionally, determining the flip-off time and drive configuration of the pulse width modulation signal based on sector symmetry and the action time of the basic vector includes:

[0021] When the space voltage vector is located in the first middle sector of the first large sector, the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal are determined according to the action time of the basic vector; where t1 = T0′×0.5, t2 = t1+0.5×T1′, and T0′ and T1′ are the per-unit values ​​of T0 and T1, respectively;

[0022] Based on the sector symmetry, according to the flip time and drive configuration of the pulse width modulation signal when the space voltage vector is located in the first middle sector of the first large sector, the flip time and drive configuration of the pulse width modulation signal when the space voltage vector is located in the second middle sector of the first large sector, each middle sector of the second large sector, and each middle sector of the third large sector, the flip time and drive configuration of the pulse width modulation signal are determined.

[0023] Optionally, when the space voltage vector is located in the first middle sector of the first large sector, determining the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal based on the action time of the basic vector includes:

[0024] When the space voltage vector is located in the first middle sector of the first large sector, the correspondence between the switching function of each phase of the three-phase inverter and the per-unit value of the comparison register of the pulse width modulation signal is determined according to the complementary state of the upper and lower bridge arm switches of each phase of the three-phase inverter; the value of each phase switching function of the three-phase inverter corresponds to the on / off state of each phase switch, and the switches of each phase upper and lower bridge arm that are in a complementary state correspond to the same comparison register;

[0025] Based on the correspondence, determine the per-unit value of each comparison register corresponding to each of the small sectors.

[0026] Optionally, the value of the switching function is -1, 0, or 1, and the per-unit value of the comparison register is 1, t1, or t2. When the per-unit value of the comparison register is t1 or t2, it indicates that the value of the switching function of the corresponding phase has changed.

[0027] Optionally, determining the sector number of the small sector where the space voltage vector is located, based on sector symmetry and the large and medium sectors where the space voltage vector is located, according to the preset relationship between m and n, includes:

[0028] When the spatial vector is located in the first sector of one of the large sectors, the small sector where the spatial vector is located is determined according to the preset relationship between m and n;

[0029] Based on the symmetry of sectors, when the spatial vector is located in the second sector of the large sector, the values ​​of m and n are swapped, and the small sector where the spatial vector is located is determined according to the preset relationship group.

[0030] Optionally, the basic vectors V1 and V5 are the same vector, the basic vectors V2 and V4 are the same vector, and the basic vectors V1 and V5 are zero vectors.

[0031] Secondly, embodiments of the present invention provide a three-phase inverter, including: a three-level inverter topology circuit and a controller, wherein the controller is electrically connected to the three-level inverter topology circuit, and the controller is used to implement the pulse width modulation method as described in the first aspect to output the pulse width modulation signal to the three-level inverter topology circuit.

[0032] The present invention provides a pulse width modulation (PWM) method and a three-phase inverter. The PWM method is applied to a three-phase inverter, which includes a three-level inverter topology circuit. The PWM method includes: obtaining the basic vectors of the three-level topology circuit; the basic vectors include thirteen vectors; dividing the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors according to the thirteen basic vectors; the number of small sectors is twice the number of medium sectors; determining the large, medium, and small sectors based on a preset modulation reference signal and the symmetry of the sectors to determine the sector where the space voltage vector is located; determining the action time of the basic vectors according to the sector where the space voltage vector is located; and determining the flip time and driving configuration of the PWM signal based on the symmetry of the sectors and the action time of the basic vectors. The PWM signal is used to drive the three-level inverter topology circuit. When the basic vectors used for the space voltage vector change, the switching states of two-phase switches in the three-level inverter topology circuit change simultaneously. The pulse width modulation method and three-phase inverter provided in this invention divide the vector space formed by the thirteen basic vectors into large, medium, and small sectors, without having to divide the sector according to all the basic vectors. This reduces the number of small sectors, thereby reducing the amount of computation and computational complexity when calculating the action time of the basic vectors, the flipping time of the pulse width modulation signal, and the drive configuration. Attached Figure Description

[0033] Figure 1 This is a flowchart of a pulse width modulation method provided in Embodiment 1 of the present invention;

[0034] Figure 2 This is a schematic diagram of a three-level inverter topology circuit provided in Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of a basic vector distribution provided in Embodiment 1 of the present invention;

[0036] Figure 4 This is a flowchart of a pulse width modulation method provided in Embodiment 2 of the present invention;

[0037] Figure 5 This is a schematic diagram of a sector distribution provided in Embodiment 2 of the present invention;

[0038] Figure 6 This is a schematic diagram of vector space per-unitization provided in Embodiment 2 of the present invention;

[0039] Figure 7 This is a schematic diagram of a large sector determination method provided in Embodiment 2 of the present invention;

[0040] Figure 8 This is a schematic diagram of a sector determination method provided in Embodiment 2 of the present invention;

[0041] Figure 9 This is a schematic diagram of a switching function change provided in Embodiment 2 of the present invention;

[0042] Figure 10 This is a schematic diagram of a pulse width modulation signal configuration provided in Embodiment 2 of the present invention;

[0043] Figure 11 This is a schematic diagram of the state changes of each phase switch provided in Embodiment 2 of the present invention;

[0044] Figure 12 This is a schematic diagram of another change in the state of each phase switch provided in Embodiment 2 of the present invention;

[0045] Figure 13 This is a structural block diagram of a pulse width modulation device provided in Embodiment 3 of the present invention;

[0046] Figure 14 This is a schematic diagram of the structure of an electronic device provided in Embodiment 4 of the present invention. Detailed Implementation

[0047] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0048] Example 1

[0049] Figure 1 This is a flowchart of a pulse width modulation method provided in Embodiment 1 of the present invention. This embodiment can be applied to pulse width modulation of three-phase inverters, etc. The three-phase inverter includes a three-level inverter topology circuit and a controller. The controller is electrically connected to the three-level inverter topology circuit. The method can be executed by the controller. For example, the controller can be the main control chip DSP of the three-phase inverter. The controller can be implemented in software and / or hardware. The method specifically includes the following steps:

[0050] Step 110: Obtain the basic vectors of the three-level inverter topology circuit; the basic vectors include thirteen vectors.

[0051] For example, Figure 2 This is a schematic diagram of a three-level inverter topology circuit provided in Embodiment 1 of the present invention. (Reference) Figure 2In a three-level inverter topology, each phase upper arm has two switching transistors, and each phase lower arm has two switching transistors. The switching function Si is defined as 1, 0, or -1. 1 indicates that the two upper power transistors of phase i are closed, and the remaining power transistors of phase i are open; 0 indicates that the two middle power transistors of phase i are closed, and the remaining power transistors of phase i are open; -1 indicates that the two lower power transistors of phase i are closed, and the remaining power transistors of phase i are open. Phase i refers to phases A, B, and C of the three-phase inverter.

[0052] Step 120: Based on the thirteen basic vectors, divide the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors; the number of small sectors is twice the number of medium sectors.

[0053] For example, Figure 3 This is a schematic diagram of a basic vector distribution provided in Embodiment 1 of the present invention. (Reference) Figure 2 and Figure 3 The basic vectors include 27 basic vectors such as 000, 001, 011, 111, 101, 100, 10-1, and -10-1 (basic vectors 000, 111, and -1-1-1 are zero vectors). For example, 10-1 indicates that the top two power transistors of phase A are closed, the middle two power transistors of phase B are closed, and the bottom two power transistors of phase C are closed. Based on the thirteen basic vectors, namely the zero vector (000, 111, -1-1-1), six intermediate vectors (10-1, 1-10, 0-11, -101, -110, 01-1), and six large vectors (1-1-1, 1-11, -1-11, -111, -11-1, 11-1), the resulting vector space can be divided into multiple large sectors, such as... Figure 3 The three red lines divide the vector space into three large sectors, each large sector into two medium sectors, and each medium sector into two small sectors.

[0054] Step 130: Based on the preset modulation reference signal and the symmetry of the sector, determine the large sector, medium sector and small sector, and determine the sector where the space voltage vector is located.

[0055] Specifically, firstly, based on the magnitude of the preset modulation reference signal, the large sector where the space voltage vector is located is determined. Then, the middle sector of the large sector where the space voltage vector is located is determined. Finally, the small sector of the middle sector where the space voltage vector is located is determined. When the space vector is located in the first middle sector of the first large sector, the small sector where the space vector is located is determined based on the magnitude of the preset modulation reference signal. And based on the symmetry of the sectors, the small sector where the space vector is located when it is located in the second middle sector of the first large sector is determined based on the magnitude of the preset modulation reference signal.

[0056] Step 140: Determine the duration of the basic vector based on the sector where the space voltage vector is located. Based on the symmetry of the sector and the duration of the basic vector, determine the flip-off time and driving configuration of the pulse width modulation signal. The pulse width modulation signal is used to drive the three-level inverter topology circuit. When the basic vector used for the space voltage vector is transformed, the switching states of the two-phase switches in the three-level inverter topology circuit change simultaneously.

[0057] Specifically, based on the large, medium, and small sectors where the space voltage vector is located, the duration of the basic vector is determined. Based on the duration of the basic vector and the symmetry of the sectors, the flip-off time and drive configuration of the PWM (Pulse Width Modulation) signal are determined to achieve SVPWM (Space Vector Pulse Width Modulation) based on thirteen vectors.

[0058] It should be noted that the specific duration of the above preset time can be determined according to actual control needs, and is not limited here.

[0059] The pulse width modulation method provided in this embodiment includes: obtaining the basic vector of a three-level inverter topology circuit; the basic vector includes thirteen vectors; dividing the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors according to the thirteen vectors in the basic vectors; the number of small sectors is twice the number of medium sectors; determining the large, medium, and small sectors based on a preset modulation reference signal and the symmetry of the sectors, and determining the sector where the space voltage vector is located; determining the action time of the basic vector according to the sector where the space voltage vector is located, and determining the flip time and driving configuration of the pulse width modulation signal based on the symmetry of the sectors and the action time of the basic vector, the pulse width modulation signal is used to drive the three-level inverter topology circuit; when the basic vector used for the space voltage vector is transformed, the switching state of the two-phase switches in the three-level inverter topology circuit changes simultaneously. The pulse width modulation method provided in this embodiment divides the vector space formed by the thirteen basic vectors into large, medium, and small sectors, without having to divide the sector according to all the basic vectors. This reduces the number of small sectors, thereby reducing the amount of computation and computational complexity when calculating the action time of the basic vectors and the flipping time and drive configuration of the pulse width modulation signal.

[0060] Example 2

[0061] Figure 4This is a flowchart of a pulse width modulation method provided in Embodiment 2 of the present invention. This embodiment can be applied to pulse width modulation of three-phase inverters, etc. The three-phase inverter includes a three-level inverter topology circuit and a controller. The controller is electrically connected to the three-level inverter topology circuit. The method can be executed by the controller, which can be the main control chip DSP of the three-phase inverter. The controller can be implemented in software and / or hardware. The method specifically includes the following steps:

[0062] Step 210: Obtain the basic vectors of the three-level inverter topology circuit. The basic vectors include thirteen vectors.

[0063] The basic vectors of the three-level inverter topology circuit can be referred to in the specific description of step 110 above, and will not be repeated here.

[0064] Step 220: Divide the vector space formed by the thirteen basic vectors into the first large sector (0°-120°), the second large sector (120°-240°), and the third large sector (240°-0°). Each large sector is divided into two medium sectors by its respective angle bisector, and each medium sector is divided into two small sectors by its respective angle bisector. Determine the sector numbers of each large sector, each medium sector, and each small sector.

[0065] For example, Figure 5 This is a schematic diagram of a sector distribution provided in Embodiment 2 of the present invention. In this embodiment, the vector space formed by the thirteen basic vectors is divided into three major sectors in a counterclockwise direction: a first major sector (0°-120°), a second major sector (120°-240°), and a third major sector (240°-0°), starting from the sector line where the basic vectors 000-111 are located. (Reference) Figure 5 Each major sector comprises a first medium sector and a second medium sector, and each medium sector comprises a first minor sector and a second minor sector. Major sectors N1 = 1, 2, 3, where N1=1 represents the first major sector, N1=2 represents the second major sector, and N1=3 represents the third major sector. Medium sectors N2 = 1, 2, where N2=1 represents the first medium sector and N2=2 represents the second medium sector. Minor sectors N3 = 1, 2, where N3=1 represents the first minor sector and N3=2 represents the second minor sector.

[0066] Step 230: Based on the preset modulation reference signals Vα and Vβ, normalize the preset modulation reference signals Vα and Vβ to obtain the normalized modulation reference signals Vα1 and Vβ1.

[0067] For example, Figure 6 This is a schematic diagram of vector space per-unit scaling provided in Embodiment 2 of the present invention. (Reference) Figure 6The composite vector of the preset modulation reference signals Vα and Vβ is Vref, and the composite vector of the normalized modulation reference signals Vα1 and Vβ1 is Vref1. For a three-phase inverter with a DC voltage of Vdc, the hexagonal amplitude of the vector space formed by the basic vectors is 2 / 3 of Vdc. The space vector modulation algorithm is independent of the DC voltage. By normalizing the vector space and dividing by Vdc, we can obtain... Figure 6 The hexagonal vector space with a side length of 2 / 3 shown is normalized by multiplying it by k to simplify subsequent calculations and avoid decimal calculations. Preferably, 2k / 3 is an integer, resulting in a normalized hexagonal vector space with a side length of 2k / 3. For example, in this embodiment, k=6, i.e., Vα1=6Vα, Vβ1=6Vβ, resulting in a normalized hexagonal vector space with a side length of 4. For ease of demonstration, subsequent calculations are normalized by multiplying the hexagonal vector space by 6. In other embodiments, other k values ​​can also be used for normalization.

[0068] Step 240: Based on the standardized modulation reference signals Vα1 and Vβ1, obtain the calculated values ​​A and B, where A = Vα1 and B = Vβ1 / .

[0069] Step 250: Based on the relationship between B and 0, and the relationship between the sum and / or subtraction of A and B and 0, determine the sector number of the large sector where the space voltage vector is located.

[0070] For example, Figure 7 This is a schematic diagram illustrating a large sector determination method provided in Embodiment 2 of the present invention. (Reference) Figure 7 When B>0, if A+B>0, then N1=1; if A+B≤0, then N1=2. When B≤0, if AB>0, then N1=3; if AB≤0, then N1=2.

[0071] Step 260: Based on the sector number of the large sector where the space voltage vector is located, represent m and n using preset equations of A and / or B, and determine the sector number of the medium sector where the space voltage vector is located according to the magnitude of m and n.

[0072] Wherein, the first sector is farther away from the second largest sector than the second sector, and m and n are the projection values ​​of the composite vector of Vα1 and Vβ1 on the 0-degree and 120-degree coordinate axes of the 120-degree coordinate system, respectively; the preset equations for A and / or B include: when the space voltage vector is located in the first largest sector, m=A+B, n=2×B; when the space voltage vector is located in the second largest sector, m=-A+B, n=-AB; when the space voltage vector is located in the third largest sector, m=-2×B, n=AB; when m or n is greater than 4, m=4, n=4n / m. For example, Figure 8It is a schematic diagram of medium sector determination provided in the second embodiment of the present invention. Refer to Figure 8 , when N1 = 1, if m ≥ n, then N2 = 1; if m < n, then N2 = 2.

[0073] Step 270: Based on sector symmetry and the large sector and medium sector where the space voltage vector is located, determine the sector number of the small sector where the space voltage vector is located according to the preset relationship group of m and n, specifically including:

[0074] When the space vector is located in the first medium sector of one of the large sectors, determine the small sector where the space vector is located according to the preset relationship group of m and n;

[0075] Based on the symmetry of the sector, when the space vector is located in the second medium sector of this large sector, swap the assignment of m and n, and determine the small sector where the space vector is located according to the preset relationship group.

[0076] Specifically, the preset relationship group of m and n includes: when the space voltage vector is located in the first medium sector of the first large sector, if 2n ≤ m < 4 and n ≥ 0, it is determined that the space voltage vector is located in the first small sector; if m < 4 and n ≤ m < 2n, it is determined that the space voltage vector is located in the second small sector. Table 1 shows the satisfaction conditions and corresponding small sectors for determining the small sector where the space voltage vector is located when the space voltage vector is located in the first medium sector of the first large sector. As shown in Table 1, when the magnitude relationship between m and n is different, the value of the small sector N3 is different, that is, the small sector where the space voltage vector is located is different.

[0077] Table 1 N3 determination

[0078]

[0079] Furthermore, when N1=1, N2=1 and N2=2 are symmetrical about a 60-degree axis. Therefore, when N2=2, it is only necessary to swap the values ​​of m and n in N2=1 before determining the small sector N3. It can be understood that the preset relationship group of m and n remains unchanged; only the original values ​​of m and n have been swapped. Further, the space voltage vector is synthesized based on the basic vector of its small sector. Since small vectors are not used, there is a possibility that two phase switch states may change simultaneously. The small vectors include 001, 101, 0-1-1, 00-1, 010, 011, -1-10, 0-10, 100, 110, -10-1, and -100. If small vectors are used for the space voltage vector, when the small vector changes (e.g., from 001 to 101), only one phase switch state changes at any given time; there is no possibility of two phase switch states changing simultaneously. If small vectors are not used, but zero, medium, and large vectors are used instead, during large vector transformations, such as transforming from 11-1 to 1-11, there may be situations where the states of two phase switches change simultaneously. When the space voltage vector is in the sector where N1=1 and N2=1, the basic vectors used in the small sector shown in Table 2 can be obtained.

[0080] Table 2. The sector containing the space voltage vector and the basic vectors used.

[0081]

[0082] Step 280: When the space voltage vector is located in the first middle sector of the first large sector, determine the functional relationship between T0, T1, and T2 with respect to m, n, and T based on the small sector where the space voltage vector is located, and determine T0, T1, and T2 based on the functional relationship.

[0083] Where T is the switching period of the pulse width modulation signal, T0 is the duration of the basic vectors V1 and V5 in one switching period, T1 is the duration of the basic vectors V2 and V4 in one switching period, and T2 is the duration of the basic vector V3 in one switching period. For example, the functional relationships of T0, T1, and T2 with respect to m, n, and T include: when the space voltage vector is located in the first small sector, mT = 4T1 + 4T2, nT = 2T1, and T = T0 + T1 + T2; when the space voltage vector is located in the second small sector, mT = 4T1 + 4T2, nT = 2T1 + 4T2, and T = T0 + T1 + T2. Where T is known, Table 3 illustrates the solution results and per-unit values ​​of T0, T1, and T2.

[0084] Table 3. Basic Vector Action Time

[0085]

[0086] Table 3 standardizes the basic vector action time by dividing it by T / 2, which simplifies the calculation and eliminates the influence of the switching cycle variable on the algorithm.

[0087] Step 290: When the space voltage vector is located in the first middle sector of the first large sector, determine the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal based on the action time of the basic vector, specifically including:

[0088] When the space voltage vector is located in the first middle sector of the first large sector, the correspondence between the switching function of each phase of the three-phase inverter and the per-unit value of the comparison register of the pulse width modulation signal is determined according to the complementary state of the upper and lower bridge arm switching transistors of each phase of the three-phase inverter. The value of the switching function of each phase of the three-phase inverter corresponds to the on / off state of each phase switching transistor, and the switching transistors of each phase upper and lower bridge arm that are in a complementary state correspond to the same comparison register.

[0089] Based on the correspondence, determine the per-unit value of each comparison register corresponding to each small sector.

[0090] Where t1 = T0′ × 0.5, t2 = t1 + 0.5 × T1′, and T0′ and T1′ are the per-unit values ​​of T0 and T1, respectively. For example, Figure 9 This is a schematic diagram illustrating the change of a switching function according to Embodiment 2 of the present invention. (Reference) Figure 9 The PWM signals are symmetrically distributed within the switching cycle. The transition time of the switching function of phase A from 0 to 1 (the transition time of the switching function of phase C from 0 to -1) is t1, and the transition time of the switching function of phase B from 0 to -1 is t2. According to... Figure 9 The schematic diagram of the switching function change shows that t1 = T0′ × 0.5 and t2 = t1 + 0.5 × T1′. Figure 10 This is a schematic diagram of a pulse width modulation signal configuration provided in Embodiment 2 of the present invention, for reference. Figure 10 The PWM signal configuration adopts an up-down calculation mode, and the action method is as follows: Figure 10 As shown. The drive signals EPWMx (x = 1 / 2 / 3 / 4 / 5 / 6) control PxA and PxB, and EPWM1 / 3 / 5 are used as follows. Figure 10 Modulation mode 1 is shown. EPWM2 / 4 / 6 uses modulation mode 2. For example, drive signal EPWM1 ​​controls P1A and P1B of phase A bridge arm, drive signal EPWM2 controls P2A and P2B of phase A bridge arm, drive signal EPWM3 controls P3A and P3B of phase B bridge arm, drive signal EPWM4 controls P4A and P4B of phase B bridge arm, drive signal EPWM5 controls P5A and P5B of phase C bridge arm, and drive signal EPWM6 controls P6A and P6B ​​of phase C bridge arm. Figure 10The value of the period register shown is normalized, and the value of the comparator register corresponding to EPWM x (x = 1 / 2 / 3 / 4 / 5 / 6) is Compx (x = 1 / 2 / 3 / 4 / 5 / 6). According to the PWM signal configuration, the correspondence between the switching function and the comparator register value is shown in Table 4 below.

[0091] Table 4. Correspondence between switch functions and compare register values

[0092]

[0093] Figure 11 This is a schematic diagram of the state changes of each phase switch provided in Embodiment 2 of the present invention. Figure 12 This is a schematic diagram of another change in the state of each phase switch provided in Embodiment 2 of the present invention. Figure 11 and Figure 12 In the diagram, H indicates that the corresponding switch is on, and L indicates that the corresponding switch is off. (Refer to...) Figure 11 , Figure 12 According to Table 4, for phase A, when the switching function jumps from 0 to 1, Comp1 is set to t1 and Comp2 is fixed to 1; for phase B, in the first sector (in the second sector), when the switching function jumps from 0 to -1 (1), Comp3 is fixed to 1 (t2) and Comp4 is set to t2 (1); for phase C, when the switching function jumps from 0 to -1, Comp5 is fixed to 1 and Comp6 is set to t1. The comparator register values ​​can be obtained as shown in Table 5.

[0094] Table 5 Comparison of Register Values

[0095]

[0096] Step 291: Based on the sector symmetry, determine the pulse width modulation signal flip time and drive configuration when the space voltage vector is located in the first middle sector of the first large sector, the second middle sector of the second large sector, and the middle sector of the third large sector, according to the flip time and drive configuration of the pulse width modulation signal when the space voltage vector is located in the second middle sector of the first large sector, each middle sector of the second large sector, and each middle sector of the third large sector.

[0097] The drive configuration includes the configuration of the values ​​of each comparison register of the pulse width modulation signal. Specifically, the results in Table 5 are the modulation results when N1=1 and N2=1. When N2=2, according to symmetry, the values ​​of Comp1 and Comp2 are swapped with the values ​​of Comp3 and Comp4, respectively, as shown in the following formula:

[0098]

[0099] When N1=2, based on rotational symmetry, the substitution is performed according to the following formula:

[0100]

[0101] When N1=3, based on rotational symmetry, the substitution is performed according to the following formula:

[0102]

[0103] If the value of the period register is p, the final value of the comparison register Comparex (x=1 / 2 / 3 / 4 / 5 / 6) can be obtained as follows: Comparex1=Comp1×p; Comparex2=Comp2×p; Comparex3=Comp3×p; Comparex4=Comp4×p; Comparex5=Comp5×p; Comparex6=Comp6×p.

[0104] Furthermore, when the space voltage vector is located in each of the middle sectors of the second largest sector and each of the middle sectors of the third largest sector, the flipping time and driving configuration of the pulse width modulation signal can be referred to the specific descriptions above for N1=1, N2=1 and N1=1, N2=2, which will not be repeated here.

[0105] The pulse width modulation method provided in this embodiment divides the vector space formed by the thirteen basic vectors into large, medium, and small sectors, eliminating the need to divide sectors based on all the basic vectors. This results in fewer small sectors, with each medium sector being divided into only two small sectors. Consequently, the computational load and complexity are reduced when calculating the duration of the basic vectors, the flipping time of the pulse width modulation signal, and the drive configuration. Furthermore, the pulse width modulation process uses the thirteen vectors, including the zero, medium, and large vectors, while omitting the small vectors, thus avoiding the risk of DC midpoint imbalance caused by the small vectors.

[0106] Example 3

[0107] Figure 13This is a structural block diagram of a pulse width modulation (PWM) device provided in Embodiment 3 of the present invention. The PWM device is applied to a three-phase inverter, which includes a three-level inverter topology circuit and a controller. The controller is electrically connected to the three-level inverter topology circuit, and the PWM device is integrated into the controller. The PWM device includes: a vector acquisition module 310, a sector division module 320, a sector determination module 330, and a signal modulation module 340. The vector acquisition module 310 is used to acquire the basic vectors of the three-level inverter topology circuit; the basic vectors include thirteen vectors. The sector division module 320 is used to divide the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors based on the thirteen basic vectors. The number of sectors is twice the number of medium sectors; the sector determination module 330 is used to determine large, medium and small sectors based on the preset modulation reference signal and the symmetry of the sectors, and to determine the sector where the space voltage vector is located; the signal modulation module 340 is used to determine the action time of the basic vector according to the sector where the space voltage vector is located, and to determine the flip time and drive configuration of the pulse width modulation signal based on the symmetry of the sector and the action time of the basic vector. The pulse width modulation signal is used to drive the three-level inverter topology circuit; when the basic vector used for the space voltage vector is transformed, the switching state of the two-phase switches in the three-level inverter topology circuit changes simultaneously.

[0108] In one implementation, the sector division module 320 is specifically used to divide the vector space formed by the thirteen basic vectors into a first large sector of 0°-120°, a second large sector of 120°-240°, and a third large sector of 240°-0°. Each large sector is divided into two medium sectors by its respective angle bisector, and each medium sector is divided into two small sectors by its respective angle bisector. The module also determines the sector number of each large sector, the sector number of each medium sector, and the sector number of each small sector.

[0109] Based on the above implementation method, the sector determination module 330 includes:

[0110] The per-unit is used to normalize the preset modulation reference signals Vα and Vβ based on the preset modulation reference signals Vα and Vβ, so as to obtain the normalized modulation reference signals Vα1 and Vβ1.

[0111] The calculation value determination unit is used to obtain calculated values ​​A and B based on the standardized modulation reference signals Vα1 and Vβ1, where A = Vα1 and B = Vβ1 / ;

[0112] The large sector determination unit is used to determine the sector number of the large sector where the space voltage vector is located based on the relationship between B and 0, and the relationship between the sum and / or subtraction of A and B and 0.

[0113] The middle sector determination unit, based on the sector number of the large sector where the space voltage vector is located, uses a preset equation of A and / or B to represent m and n, and determines the sector number of the middle sector where the space voltage vector is located according to the magnitude of m and n, where m and n are the projection values ​​of the composite vector of Vα1 and Vβ1 on the 0-degree coordinate axis and the 120-degree coordinate axis of the 120-degree coordinate system, respectively.

[0114] The small sector determination unit is used to determine the sector number of the small sector where the space voltage vector is located based on the sector symmetry and the large and medium sectors where the space voltage vector is located, according to the preset relationship between m and n.

[0115] Optionally, the small sector determination unit includes a first small sector determination subunit and a second small sector determination subunit. The first small sector determination subunit is used to determine the small sector where the space vector is located based on a preset relationship group of m and n when the space vector is located in the first middle sector of a large sector. The second small sector determination subunit is used to swap the values ​​of m and n based on the symmetry of the sector when the space vector is located in the second middle sector of the large sector, and determine the small sector where the space vector is located based on the preset relationship group.

[0116] Optionally, each small sector corresponds to a basic vector V1, V2, V3, V4, and V5; the signal modulation module 340 includes a first time determination unit, which is used to determine the functional relationship between T0, T1, and T2 with respect to m, n, and T based on the small sector where the space voltage vector is located when the space voltage vector is located in the first middle sector of the first large sector, and to determine T0, T1, and T2 based on the functional relationship; wherein, T is the switching period of the pulse width modulation signal, T0 is the duration of action of the basic vectors V1 and V5 in one switching period, T1 is the duration of action of the basic vectors V2 and V4 in one switching period, and T2 is the duration of action of the basic vector V3 in one switching period.

[0117] Optionally, the signal modulation module 340 includes a first modulation unit and a second modulation unit. The first modulation unit is used to determine the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal according to the action time of the basic vector when the space voltage vector is located in the first middle sector of the first large sector. Wherein, t1 = T0′ × 0.5, t2 = t1 + 0.5 × T1′, and T0′ and T1′ are the per-unit values ​​of T0 and T1, respectively. The second modulation unit is used to determine the flip times and driving configuration of the pulse width modulation signal when the space voltage vector is located in the second middle sector of the first large sector, each middle sector of the second large sector, and each middle sector of the third large sector, based on the symmetry of the sector and the flip times and driving configuration of the pulse width modulation signal when the space voltage vector is located in the first middle sector of the first large sector.

[0118] Optionally, the first modulation unit includes a relationship determination subunit and a per-unit value determination subunit. The relationship determination subunit is used to determine the correspondence between the switching functions of each phase of the three-phase inverter and the per-unit value of the pulse width modulation signal comparison register, based on the complementary states of the upper and lower bridge arm switches of each phase of the three-phase inverter when the space voltage vector is located in the first middle sector of the first large sector. The value of each phase switching function of the three-phase inverter corresponds to the on / off state of each phase switch, and the switches of each phase upper and lower bridge arm in a complementary state correspond to the same comparison register. The per-unit value determination subunit is used to determine the per-unit value of each comparison register corresponding to each small sector based on the correspondence.

[0119] Optionally, the aforementioned small sector determination unit includes a third small sector determination subunit and a fourth small sector determination subunit. The third small sector determination subunit is used to determine the small sector where the space vector is located based on a preset relationship group of m and n when the space vector is located in the first middle sector of a large sector. The fourth small sector determination subunit is used to swap the values ​​of m and n based on the symmetry of the sector when the space vector is located in the second middle sector of the large sector, and determine the small sector where the space vector is located based on the preset relationship group.

[0120] This embodiment also provides a three-phase inverter, including: a three-level inverter topology circuit and a controller, the controller being electrically connected to the three-level inverter topology circuit, the controller being used to implement the pulse width modulation method as provided in any embodiment of the present invention, so as to output a pulse width modulation signal to the three-level inverter topology circuit.

[0121] The pulse width modulation device and three-phase inverter provided in this embodiment belong to the same inventive concept as the pulse width modulation method provided in any embodiment of the present invention, and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the pulse width modulation method provided in any embodiment of the present invention.

[0122] Example 4

[0123] Figure 14 This is a schematic diagram of the structure of an electronic device provided in Embodiment 4 of the present invention. Figure 14 A block diagram is shown of an exemplary electronic device 412 suitable for implementing embodiments of the present invention. Figure 14 The electronic device 412 shown is merely an example and should not impose any limitation on the functionality and scope of use of the embodiments of the present invention.

[0124] like Figure 14 As shown, electronic device 412 is represented in the form of a general-purpose device. The components of electronic device 412 may include, but are not limited to: one or more processors 416, storage device 428, and bus 418 connecting different system components (including storage device 428 and processor 416).

[0125] Bus 418 represents one or more of several bus architectures, including a memory device bus or memory device controller, a peripheral bus, a graphics acceleration port, a processor, or a local bus using any of the various bus architectures. Examples of these architectures include, but are not limited to, the Industry Subversive Alliance (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnect (PCI) bus.

[0126] Electronic device 412 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by electronic device 412, including volatile and non-volatile media, removable and non-removable media.

[0127] Storage device 428 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 430 and / or cache memory 432. Electronic device 412 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, storage system 434 may be used to read and write non-removable, non-volatile magnetic media (… Figure 14 Not shown; usually referred to as a "hard drive"). Although Figure 14 As not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk") and an optical disc drive for reading and writing to a removable non-volatile optical disc, such as a Compact Disc Read-Only Memory (CD-ROM), a Digital Video Disc Read-Only Memory (DVD-ROM), or other optical media. In these cases, each drive may be connected to bus 418 via one or more data media interfaces. Storage device 428 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the embodiments of the present invention.

[0128] A program / utility 440 having a set (at least one) of program modules 442 may be stored in, for example, a storage device 428. Such program modules 442 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data. Each or some combination of these examples may include an implementation of a network environment. Program modules 442 typically perform the functions and / or methods described in the embodiments of the present invention.

[0129] Electronic device 412 can also communicate with one or more external devices 414 (e.g., keyboard, pointing terminal, display 424, etc.), and with one or more terminals that enable a user to interact with the electronic device 412, and / or with any terminal that enables the electronic device 412 to communicate with one or more other computing terminals (e.g., network card, modem, etc.). This communication can be performed via input / output (I / O) interface 422. Furthermore, electronic device 412 can also communicate with one or more networks (e.g., local area network (LAN), wide area network (WAN), and / or public networks, such as the Internet) via network adapter 420. Figure 14 As shown, network adapter 420 communicates with other modules of electronic device 412 via bus 418. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with electronic device 412, including but not limited to: microcode, terminal drivers, redundant processors, external disk drive arrays, Redundant Arrays of Independent Disks (RAID) systems, tape drives, and data backup storage systems.

[0130] Processor 416 (which can be considered as the controller in a three-phase inverter) executes various functional applications and data processing by running programs stored in storage device 428. For example, it implements the pulse width modulation method provided in this embodiment of the invention. The pulse width modulation method is applied to a three-phase inverter, which includes a three-level inverter topology circuit. The pulse width modulation method includes:

[0131] Obtain the basic vectors of a three-level topology circuit; the basic vectors include thirteen vectors.

[0132] Based on the thirteen basic vectors, the vector space formed by the basic vectors is divided into large sectors, medium sectors, and small sectors; the number of small sectors is twice the number of medium sectors.

[0133] Based on the preset modulation reference signal and the symmetry of the sector, large, medium and small sectors are determined to identify the sector where the space voltage vector is located.

[0134] Based on the sector where the space voltage vector is located, the duration of the basic vector is determined. Based on the symmetry of the sector and the duration of the basic vector, the flip-off time and drive configuration of the pulse width modulation signal are determined. The pulse width modulation signal is used to drive the three-level inverter topology circuit. When the basic vector used for the space voltage vector is transformed, the switching states of the two-phase switches in the three-level inverter topology circuit change simultaneously.

[0135] Example 5

[0136] Embodiment 5 of the present invention also provides a computer-readable storage medium storing a computer program thereon. When executed by a processor (which can be considered as a controller in a three-phase inverter), the program implements the pulse width modulation method provided in the embodiments of the present invention. The pulse width modulation method is applied to a three-phase inverter, which includes a three-level inverter topology circuit. The pulse width modulation method includes:

[0137] Obtain the basic vectors of a three-level topology circuit; the basic vectors include thirteen vectors.

[0138] Based on the thirteen basic vectors, the vector space formed by the basic vectors is divided into large sectors, medium sectors, and small sectors; the number of small sectors is twice the number of medium sectors.

[0139] Based on the preset modulation reference signal and the symmetry of the sector, large, medium and small sectors are determined to identify the sector where the space voltage vector is located.

[0140] Based on the sector where the space voltage vector is located, the duration of the basic vector is determined. Based on the symmetry of the sector and the duration of the basic vector, the flip-off time and drive configuration of the pulse width modulation signal are determined. The pulse width modulation signal is used to drive the three-level inverter topology circuit. When the basic vector used for the space voltage vector is transformed, the switching states of the two-phase switches in the three-level inverter topology circuit change simultaneously.

[0141] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0142] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0143] Program code contained on a computer-readable medium may be transmitted using any suitable medium, including—but not limited to—wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0144] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or terminal. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0145] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, rearrangements, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A pulse width modulation method, characterized in that, The pulse width modulation method is applied to a three-phase inverter, which includes a three-level inverter topology circuit. The pulse width modulation method includes: Obtain the basic vectors of the three-level inverter topology circuit; the basic vectors include thirteen vectors; Based on the thirteen basic vectors, the vector space formed by the basic vectors is divided into large sectors, medium sectors, and small sectors; the number of small sectors is twice the number of medium sectors. Based on the preset modulation reference signal and the symmetry of the sector, the large sector, medium sector and small sector are determined to identify the sector where the space voltage vector is located; Based on the sector where the space voltage vector is located, the duration of the basic vector is determined. Based on the symmetry of the sector and the duration of the basic vector, the flip-off time and driving configuration of the pulse width modulation signal are determined. The pulse width modulation signal is used to drive the three-level inverter topology circuit. When the basic vector used by the space voltage vector is transformed, the switching states of two-phase switches in the three-level inverter topology circuit change simultaneously.

2. The pulse width modulation method according to claim 1, characterized in that, The step of dividing the vector space formed by the basic vectors into large sectors, medium sectors, and small sectors includes: The vector space formed by the thirteen basic vectors is divided into a first large sector of 0°-120°, a second large sector of 120°-240°, and a third large sector of 240°-0°. Each large sector is divided into two medium sectors by its respective angle bisector, and each medium sector is divided into two small sectors by its respective angle bisector. The sector numbers of each large sector, each medium sector, and each small sector are determined.

3. The pulse width modulation method according to claim 2, characterized in that, The determination of the large, medium, and small sectors based on the preset modulation reference signal and the symmetry of the sectors, and the identification of the sector where the space voltage vector is located, includes: Based on preset modulation reference signals Vα and Vβ, the preset modulation reference signals Vα and Vβ are normalized to obtain normalized modulation reference signals Vα1 and Vβ1. Based on the normalized modulation reference signals Vα1 and Vβ1, the calculated values ​​A and B are obtained, where A = Vα1 and B = Vβ1 / ; Based on the relationship between the calculated value B and 0, and the relationship between the sum and / or subtraction of the calculated values ​​A and B and 0, the sector number of the large sector where the space voltage vector is located is determined; Based on the sector number of the large sector where the space voltage vector is located, m and n are represented by a preset equation of A and / or B, and the sector number of the middle sector where the space voltage vector is located is determined according to the magnitude of m and n, where m and n are the projection values ​​of the composite vector of Vα1 and Vβ1 on the 0-degree coordinate axis and the 120-degree coordinate axis of the 120-degree coordinate system, respectively. Based on sector symmetry and the large and medium sectors where the space voltage vector is located, the sector number of the small sector where the space voltage vector is located is determined according to the preset relationship between m and n.

4. The pulse width modulation method according to claim 3, characterized in that, Each of the aforementioned small sectors corresponds to a basic vector V1, V2, V3, V4, V5; The step of determining the duration of action of the basic vector based on the sector where the space voltage vector is located includes: When the space voltage vector is located in the first middle sector of the first large sector, the functional relationship between T0, T1, and T2 with respect to m, n, and T is determined according to the small sector where the space voltage vector is located, and T0, T1, and T2 are determined based on the functional relationship; where T is the switching period of the pulse width modulation signal, T0 is the duration of action of the basic vectors V1 and V5 in one switching period, T1 is the duration of action of the basic vectors V2 and V4 in one switching period, and T2 is the duration of action of the basic vector V3 in one switching period.

5. The pulse width modulation method according to claim 4, characterized in that, The determination of the pulse width modulation signal's flip-off time and driving configuration based on sector symmetry and the duration of the fundamental vector includes: When the space voltage vector is located in the first middle sector of the first large sector, the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal are determined according to the action time of the basic vector; where t1 = T0′ × 0.5, t2 = t1 + 0.5 × T1′, and T0′ and T1′ are the per-unit values ​​of T0 and T1, respectively; Based on the sector symmetry, according to the flip time and drive configuration of the pulse width modulation signal when the space voltage vector is located in the first middle sector of the first large sector, the flip time and drive configuration of the pulse width modulation signal when the space voltage vector is located in the second middle sector of the first large sector, each middle sector of the second large sector, and each middle sector of the third large sector, the flip time and drive configuration of the pulse width modulation signal are determined.

6. The pulse width modulation method according to claim 5, characterized in that, When the space voltage vector is located in the first middle sector of the first large sector, the flip times t1 and t2 of the pulse width modulation signal and the driving configuration of the pulse width modulation signal are determined according to the action time of the basic vector, including: When the space voltage vector is located in the first middle sector of the first large sector, the correspondence between the switching function of each phase of the three-phase inverter and the per-unit value of the comparison register of the pulse width modulation signal is determined according to the complementary state of the upper and lower bridge arm switches of each phase of the three-phase inverter; the value of each phase switching function of the three-phase inverter corresponds to the on / off state of each phase switch, and the switches of each phase upper and lower bridge arm that are in a complementary state correspond to the same comparison register; Based on the correspondence, determine the per-unit value of each comparison register corresponding to each of the small sectors.

7. The pulse width modulation method according to claim 6, characterized in that, The value of the switching function is -1, 0, or 1, and the per-unit value of the comparison register is 1, t1, or t2. When the per-unit value of the comparison register is t1 or t2, it indicates that the value of the switching function of the corresponding phase has changed.

8. The pulse width modulation method according to claim 3, characterized in that, The process of determining the sector number of the small sector where the space voltage vector is located, based on sector symmetry and the large and medium sectors where the space voltage vector is located, according to the preset relationship between m and n, includes: When the spatial vector is located in the first sector of one of the large sectors, the small sector where the spatial vector is located is determined according to the preset relationship between m and n; Based on the symmetry of sectors, when the spatial vector is located in the second sector of the large sector, the values ​​of m and n are swapped, and the small sector where the spatial vector is located is determined according to the preset relationship group.

9. The pulse width modulation method according to claim 4, characterized in that, The basic vectors V1 and V5 are the same vector, the basic vectors V2 and V4 are the same vector, and the basic vectors V1 and V5 are zero vectors.

10. A three-phase inverter, characterized in that, include: A three-level inverter topology circuit and a controller, wherein the controller is electrically connected to the three-level inverter topology circuit, and the controller is used to implement the pulse width modulation method as described in any one of claims 1-9 to output the pulse width modulation signal to the three-level inverter topology circuit.

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