Inverter modulation method, system and device and storage medium

Abstract

The invention discloses an inverter modulation method, system and device and a storage medium, the method is used for modulating an inverter, the inverter comprises a first power unit, a second power unit and a third power unit, and the method comprises the following steps: obtaining a first modulation degree and a first frequency of an initial modulation wave; determining a first modulated wave signal of the first power unit, a second modulated wave signal of the second power unit and a third modulated wave signal of the third power unit based on the first modulation degree and the first frequency; and according to the first modulated wave signal, the second modulated wave signal and the third modulated wave signal, determining a driving signal of each power electronic switching device in the inverter, and modulating the output of the inverter through the driving signals. The method can be widely applied to the technical field of inverter modulation.

Description

Technical Field

[0001] The present application relates to the field of inverter modulation technology, and in particular to an inverter modulation method, system, device and storage medium. Background Art

[0002] In the related art, the inverter modulation strategy is a key technology in the type II asymmetric CHB 15-level inverter, which directly determines the output voltage waveform quality and performance of the inverter. The existing modulation strategy often leads to the problem of power backflow between the power units of the type II asymmetric CHB 15-level inverter, the output voltage waveform quality is not ideal, and the implementation is difficult. On the one hand, the power backflow will introduce low-order harmonics at the output end of the inverter, reducing the quality of the inverter output voltage waveform, and on the other hand, it will also bring hidden dangers to the safe operation of the inverter. In response to the problem of power backflow of the power unit, the traditional method is to increase the number of power units of the asymmetric CHB inverter, and select the polarity non-different level combination from the redundancy of the inverter output voltage level as a multi-level, but this will increase the number of power units, and due to the increase in the number of power units, the driving signal required by the power unit is also increased accordingly, which increases the difficulty of implementing the modulation strategy and leads to an increase in the cost of the inverter. Therefore, there are still technical problems that need to be solved in the related art. Summary of the invention

[0003] The purpose of this application is to solve one of the technical problems existing in the prior art to at least a certain extent.

[0004] To this end, an object of an embodiment of the present application is to provide an inverter modulation method, system, device and storage medium, which can simplify the modulation strategy and reduce the cost of the inverter.

[0005] In order to achieve the above-mentioned technical objectives, the technical solution adopted in the embodiments of the present application includes: an inverter modulation method for modulating an inverter, wherein the inverter includes a first power unit, a second power unit and a third power unit, and the method includes: obtaining a first modulation degree and a first frequency of an initial modulation wave; based on the first modulation degree and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit and a third modulation wave signal of the third power unit; according to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, determining a drive signal for each power electronic switching device in the inverter, and modulating the output of the inverter by the drive signal.

[0006] The present application can be used to modulate an inverter including a first power unit, a second power unit, and a third power unit. The method of the present application includes: obtaining a first modulation index and a first frequency of an initial modulation wave; based on the first modulation index and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit; according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, determining a drive signal for each power electronic switching device in the inverter, and modulating the output of the inverter through the drive signal. The present application can reduce the problem of power backflow between power units through a new modulation method. The present application can improve the defects of unsatisfactory output voltage waveform quality and difficulty in implementation without changing the conventional design of the inverter. The present solution can simplify the modulation strategy and reduce the cost of the inverter.

[0007] In addition, the inverter modulation method according to the above embodiment of the present invention may also have the following additional technical features:

[0008] Further, in an embodiment of the present application, based on the first modulation degree and the first frequency, determining the first modulation wave signal of the first power unit, the second modulation wave signal of the second power unit, and the third modulation wave signal of the third power unit includes:

[0009] Determine a reconstructed modulated wave based on the first modulation degree and the first frequency;

[0010] The first modulation wave signal, the second modulation wave signal and the third modulation wave signal are determined according to the reconstructed modulation wave.

[0011] Further, in the embodiment of the present application, determining the reconstructed modulated wave based on the first modulation degree and the first frequency includes:

[0012] Substituting the first modulation degree and the first frequency into the first waveform expression, a reconstructed modulated wave is obtained, wherein the first waveform expression is:

[0013] v m5 =7m a |sin(2πf m t)|

[0014] where v m5 To reconstruct the modulated wave, m a is the first modulation index, f m is the first frequency.

[0015] Further, in the embodiment of the present application, determining the first modulation wave signal, the second modulation wave signal and the third modulation wave signal according to the reconstructed modulation wave includes:

[0016] Substitute the reconstructed modulation wave into the first formula group to determine the first modulation wave signal; wherein the first formula group is:

[0017]

[0018] Substitute the first modulated wave signal into the second formula group to determine the second modulated wave signal; wherein the second formula group is:

[0019]

[0020] Substitute the second modulated wave signal into the third formula group to determine the third modulated wave signal; wherein the third formula group is:

[0021]

[0022] Further, in an embodiment of the present application, the first power unit, the second power unit, and the third power unit each include a first power electronic switch device, a second power electronic switch device, a third power electronic switch device, and a fourth power electronic switch device, and determining a drive signal for each power electronic switch device in the inverter according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, and modulating the output of the inverter by the drive signal, includes:

[0023] Determine a first working signal of the first power unit, a second working signal of the second power unit, and a third working signal of the third power unit according to the first modulated wave signal, the second modulated wave signal, and the third modulated wave signal;

[0024] According to the first working signal, the second working signal and the third working signal, a first drive signal of the first power electronic switching device, a second drive signal of the second power electronic switching device, a third drive signal of the third power electronic switching device and a fourth drive signal of the fourth power electronic switching device are determined, and the output of the inverter is modulated by the first drive signal, the second drive signal, the third drive signal and the fourth drive signal.

[0025] Further, in an embodiment of the present application, determining the first working signal of the first power unit, the second working signal of the second power unit, and the third working signal of the third power unit according to the first modulated wave signal, the second modulated wave signal, and the third modulated wave signal includes:

[0026] Convert the first modulated wave signal into a first level signal, convert the second modulated wave signal into a second level signal, and convert the third modulated wave signal into a third level signal;

[0027] The first working signal, the second working signal and the third working signal are determined according to the first level signal, the second level signal and the third level signal.

[0028] Further, in the embodiment of the present application, determining the first drive signal of the first power electronic switch device, the second drive signal of the second power electronic switch device, the third drive signal of the third power electronic switch device, and the fourth drive signal of the fourth power electronic switch device according to the first working signal, the second working signal, and the third working signal includes:

[0029] Substituting the first working signal, the second working signal, and the third working signal into the fourth formula group, the first driving signal, the second driving signal, the third driving signal, and the fourth driving signal are obtained; wherein the fourth formula group is:

[0030]

[0031] Among them, g is the preset square wave signal, SH i is the working signal, i is the serial number of the working signal, and also the serial number of the power unit, g i1 is the first driving signal, g i2 is the second driving signal, g i3 is the third driving signal, g i4 is the fourth driving signal, SH i g stands for SH i Perform a logical AND operation with g, Indicates the negation of g, Indicates SH i Perform a logical AND operation with the negation of g.

[0032] On the other hand, an embodiment of the present application further provides an inverter modulation system for modulating an inverter, wherein the inverter includes a first power unit, a second power unit, and a third power unit, and the system includes:

[0033] A first processing unit, used for obtaining a first modulation degree and a first frequency of an initial modulation wave;

[0034] a second processing unit, configured to determine, based on the first modulation degree and the first frequency, a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit;

[0035] The third processing unit is used to determine the driving signal of each power electronic switching device in the inverter according to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, and modulate the output of the inverter through the driving signal.

[0036] On the other hand, the present application also provides an inverter modulation device, comprising:

[0037] at least one processor;

[0038] at least one memory for storing at least one program;

[0039] When the at least one program is executed by the at least one processor, the at least one processor implements an inverter modulation method as described in any one of the invention contents.

[0040] In addition, the present application also provides a computer-readable storage medium, which stores processor-executable instructions, and the processor-executable instructions are used to execute an inverter modulation method as described in any of the above items when executed by the processor.

[0041] The advantages and benefits of the present application will be partially given in the following description, and partially become apparent from the following description, or be understood through the practice of the present application:

[0042] The present application can be used to modulate an inverter including a first power unit, a second power unit, and a third power unit. The method of the present application includes: obtaining a first modulation index and a first frequency of an initial modulation wave; based on the first modulation index and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit; according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, determining a drive signal for each power electronic switching device in the inverter, and modulating the output of the inverter through the drive signal. The present application can reduce the problem of power backflow between power units through a new modulation method. The present application can improve the defects of unsatisfactory output voltage waveform quality and difficulty in implementation without changing the conventional design of the inverter. The present solution can simplify the modulation strategy and reduce the cost of the inverter. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of a circuit structure of an inverter in a specific embodiment of the present invention;

[0044] Figure 2 A schematic diagram of the steps of an inverter modulation method in a specific embodiment of the present invention;

[0045] Figure 3It is a flow chart of an embodiment of a type II asymmetric CHB fifteen-level modulation strategy in another specific embodiment of the present invention;

[0046] Figure 4 It is a schematic diagram of the conventional modulation strategy of a type II asymmetric CHB fifteen-level inverter in the prior art;

[0047] Figure 5 A modulation principle diagram of a type II asymmetric CH B fifteen-level inverter with switch state function combination optimization in a specific embodiment of the present invention;

[0048] Figure 6 It is a modulation principle diagram of a type II asymmetric CHB fifteen-level inverter with modulation wave reconstruction in another specific embodiment of the present invention;

[0049] Figure 7 The inverter output voltage waveform after the modulation wave is reconstructed in a specific embodiment of the present invention;

[0050] Figure 8 The output voltage simulation waveform of the inverter under the traditional modulation strategy in the prior art;

[0051] Fig. 9 The inverter output voltage simulation waveform after the modulation method is improved in a specific embodiment of the present invention;

[0052] Fig.10 The output power simulation waveform of the inverter under the traditional modulation method in the prior art;

[0053] Fig.11 In a specific embodiment of the present invention, the inverter output power simulation waveform after the modulation method is improved;

[0054] Fig.12 This is an output voltage spectrum analysis diagram under the traditional modulation method in the prior art;

[0055] Fig.13 This is a spectrum analysis diagram of output voltage after improving the modulation method in a specific embodiment of the present invention;

[0056] Fig.14 It is an experimental waveform of the output voltage of the power unit of the inverter when the modulation degree of the modulation wave is 0.9 after the modulation method is improved in a specific embodiment of the present invention;

[0057] Fig.15 The voltage and current experimental waveforms and spectrum of the inverter output when the modulation degree of the modulation wave is 0.9 after the modulation method is improved in a specific embodiment of the present invention;

[0058] Fig.16It is an experimental waveform of the output voltage of the power unit of the inverter when the modulation degree of the modulation wave is 0.6 after the modulation method is improved in a specific embodiment of the present invention;

[0059] Fig.17 The experimental waveform and spectrum of the inverter output voltage and current when the modulation degree of the modulation wave is 0.6 after the modulation method is improved in a specific embodiment of the present invention;

[0060] Fig.18 To improve the modulation method, the output voltage, current and power waveform of the inverter power unit when the modulation degree of the modulation wave is 0.9;

[0061] Fig.19 After the modulation method is improved, the output voltage, current and power waveforms of the inverter power unit are obtained when the modulation index of the modulation wave is 0.6;

[0062] Fig. 20 A schematic diagram of the structure of an inverter modulation system in a specific embodiment of the present invention;

[0063] Fig.21 It is a structural schematic diagram of an inverter modulation device in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0064] The embodiments of the present invention are described in detail below with reference to the accompanying drawings to illustrate the principles and processes of the inverter modulation method, system, device and storage medium in the embodiments of the present invention.

[0065] In the related art, the inverter modulation strategy is a key technology in the type II asymmetric CHB 15-level inverter, which directly determines the output voltage waveform quality and performance of the inverter. The existing modulation strategy often leads to the problem of power backflow between the power units of the type II asymmetric CHB 15-level inverter, the output voltage waveform quality is not ideal, and the implementation is difficult. On the one hand, the power backflow will introduce low-order harmonics at the output end of the inverter, reducing the quality of the inverter output voltage waveform, and on the other hand, it will also bring hidden dangers to the safe operation of the inverter. In response to the problem of power backflow of the power unit, the traditional method is to increase the number of power units of the asymmetric CHB inverter, and select the polarity non-different level combination from the redundancy of the inverter output voltage level as a multi-level, but this will increase the number of power units, and due to the increase in the number of power units, the driving signal required by the power unit is also increased accordingly, which increases the difficulty of implementing the modulation strategy and leads to an increase in the cost of the inverter. Therefore, there are still technical problems that need to be solved in the related art.

[0066] In view of the above-mentioned defects of the prior art, the present application provides an inverter modulation method. The method is used to modulate the inverter, wherein, referring to Figure 1The inverter may include a first power unit, a second power unit and a third power unit. Each power unit includes four power electronic switching devices, which may be insulated gate bipolar transistors, and the connection method thereof is as follows: Figure 1 See Figure 2 , the method of the present application may include steps S101 to S103.

[0067] S101, obtaining a first modulation degree and a first frequency of an initial modulation wave.

[0068] S102: Determine a first modulation wave signal of a first power unit, a second modulation wave signal of a second power unit, and a third modulation wave signal of a third power unit based on the first modulation degree and the first frequency.

[0069] S103, determining a drive signal for each power electronic switch device in the inverter according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, and modulating the output of the inverter by the drive signal.

[0070] In some feasible embodiments of the present application, the processor can establish a wired or wireless connection with the acquisition module, and after the connection is established, the processor can obtain the first modulation degree and the first frequency of the initial modulation wave. Based on the first modulation degree and the first frequency, the first modulation wave signal of the first power unit, the second modulation wave signal of the second power unit, and the third modulation wave signal of the third power unit are determined. According to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, the drive signal of each power electronic switching device in the inverter is determined, and the output of the inverter is modulated by the drive signal.

[0071] It should be noted that the above-mentioned wired connection method may include a connection between a mobile device and a processing module, and may also include a connection between a processing module and a hardware device, as well as a wired connection between other devices currently known or to be developed in the future and the processing module; and the above-mentioned wireless connection method may include but is not limited to 3G / 4G / 5G connection, WiFi connection, Bluetooth connection, WiMAX connection, Zigbee connection, UWB (Ultra Wide Band) connection, and other wireless connection methods currently known or to be developed in the future.

[0072] The present application can be used to modulate an inverter including a first power unit, a second power unit, and a third power unit. The method of the present application includes: obtaining a first modulation index and a first frequency of an initial modulation wave; based on the first modulation index and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit; according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal, determining a drive signal for each power electronic switching device in the inverter, and modulating the output of the inverter through the drive signal. The present application can reduce the problem of power backflow between power units through a new modulation method. The present application can improve the defects of unsatisfactory output voltage waveform quality and difficulty in implementation without changing the conventional design of the inverter. The present solution can simplify the modulation strategy and reduce the cost of the inverter.

[0073] Furthermore, in an embodiment of the present application, based on the first modulation degree and the first frequency, the step of determining the first modulation wave signal of the first power unit, the second modulation wave signal of the second power unit, and the third modulation wave signal of the third power unit may include steps S201-S202.

[0074] S201. Determine a reconstructed modulated wave based on a first modulation degree and a first frequency.

[0075] S202: Determine a first modulation wave signal, a second modulation wave signal, and a third modulation wave signal according to the reconstructed modulation wave.

[0076] Further, in the embodiment of the present application, based on the first modulation degree and the first frequency, the step of determining to reconstruct the modulated wave may specifically include:

[0077] Substitute the first modulation index and the first frequency into the first waveform expression to obtain the reconstructed modulated wave, where the first waveform expression is:

[0078] v m5 =7m a |sin(2πf m t)|

[0079] where v m5 To reconstruct the modulated wave, m a is the first modulation index, f m is the first frequency.

[0080] Further, in the embodiment of the present application, the step of determining the first modulation wave signal, the second modulation wave signal and the third modulation wave signal according to the reconstructed modulation wave may specifically include:

[0081] Substitute the reconstructed modulation wave into the first formula group to determine the first modulation wave signal; wherein the first formula group is:

[0082]

[0083] Substitute the first modulated wave signal into the second formula group to determine the second modulated wave signal; wherein the second formula group is:

[0084]

[0085] Substitute the second modulated wave signal into the third formula group to determine the third modulated wave signal; wherein the third formula group is:

[0086]

[0087] Further, in the embodiment of the present application, the first power unit, the second power unit and the third power unit may include a first power electronic switch device, a second power electronic switch device, a third power electronic switch device and a fourth power electronic switch device. According to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, the step of determining the drive signal of each power electronic switch device in the inverter and modulating the output of the inverter by the drive signal may specifically include: step S301-step S302.

[0088] S301, determining a first working signal of a first power unit, a second working signal of a second power unit, and a third working signal of a third power unit according to a first modulation wave signal, a second modulation wave signal, and a third modulation wave signal.

[0089] S302. Determine a first drive signal of a first power electronic switching device, a second drive signal of a second power electronic switching device, a third drive signal of a third power electronic switching device, and a fourth drive signal of a fourth power electronic switching device according to a first working signal, a second working signal, and a third working signal, and modulate the output of an inverter by the first drive signal, the second drive signal, the third drive signal, and the fourth drive signal.

[0090] Furthermore, in an embodiment of the present application, the step of determining the first working signal of the first power unit, the second working signal of the second power unit, and the third working signal of the third power unit according to the first modulation wave signal, the second modulation wave signal, and the third modulation wave signal may include steps S401-S402.

[0091] S401, converting a first modulated wave signal into a first level signal, converting a second modulated wave signal into a second level signal, and converting a third modulated wave signal into a third level signal.

[0092] S402: Determine a first working signal, a second working signal, and a third working signal according to the first level signal, the second level signal, and the third level signal.

[0093] Further, in the embodiment of the present application, determining the first drive signal of the first power electronic switch device, the second drive signal of the second power electronic switch device, the third drive signal of the third power electronic switch device, and the fourth drive signal of the fourth power electronic switch device according to the first working signal, the second working signal, and the third working signal includes:

[0094] Substituting the first working signal, the second working signal and the third working signal into the fourth formula group, the first driving signal, the second driving signal, the third driving signal and the fourth driving signal are obtained; wherein the fourth formula group is:

[0095]

[0096] Among them, g is the preset square wave signal, SH i is the working signal, i is the serial number of the working signal, and also the serial number of the power unit, g i1 is the first driving signal, g i2 is the second driving signal, g i3 is the third driving signal, g i4 is the fourth driving signal; SH i g stands for SH i Perform a logical AND operation with g, Indicates the negation of g, Indicates SH i Perform a logical AND operation with the negation of g.

[0097] The following is combined with Figure 5-Figure 7 The principle of this application is explained.

[0098] This embodiment provides an improved modulation strategy for a type II asymmetric CHB fifteen-level inverter.

[0099] First, this embodiment creates favorable conditions for eliminating power backflow and reducing the difficulty of implementing the modulation strategy by optimizing the switch state combination of each power unit, thereby balancing the contradiction between the two indicators of output voltage quality and eliminating power backflow and the goal of reducing the difficulty of implementing the modulation strategy.

[0100] Secondly, this embodiment focuses on how to design a modulation strategy that can effectively balance the contradiction between the two indicators of ensuring the output voltage quality and eliminating power backflow and reducing the difficulty of implementing the modulation strategy. To this end, this embodiment adopts a modulation strategy based on "step wave + PWM" for high and medium voltage power units, which is characterized by controlling the high and medium voltage power units of the type II asymmetric CHB fifteen-level inverter by optimizing the amplitude of the comparison potential signal of the high and medium voltage power units, so that the inverter output voltage waveform has good quality.

[0101] For low-voltage power units, this embodiment uses PWM modulation technology to make the output waveform of the II-type asymmetric CHB 15-level inverter have low harmonic content. In order to reduce the difficulty of implementing the modulation strategy of the II-type asymmetric CHB 15-level inverter, the modulation wave is reconstructed to achieve the purpose of reducing the number of high-voltage and medium-voltage power unit comparison potential signals and low-voltage power unit carriers.

[0102] Finally, this embodiment coordinates and controls the high voltage power unit, the medium voltage power unit and the low voltage power unit to enable the II-type asymmetric CHB fifteen-level inverter to achieve low harmonic content in the output voltage waveform and eliminate the phenomenon of power backflow.

[0103] like Figure 3 As shown, the method includes steps S1 to S4.

[0104] Step S1, optimizing the switch state combination of each power unit to create favorable conditions for eliminating power backflow and reducing the difficulty of implementing the modulation strategy.

[0105] like Figure 1 As shown, the topology of the type II asymmetric CHB fifteen-level inverter consists of three cascaded H-bridge units. The DC side voltage ratio of the inverter is 4:2:1, corresponding to the high voltage power unit H1 with a DC side voltage of 4E, the medium voltage power unit H2 with a DC side voltage of 2E, and the low voltage power unit H3 with a DC side voltage of E. Each power unit has four power electronic switching devices S ie (i=1,2,3,e=1,2,3,4), the corresponding power electronic switch device drive signal is g ie (i=1,2,3,e=1,2,3,4). Define the switch state function of the i-th power unit as H fi , expressed as:

[0106] H fi =g i1 g i4 -g i2 g i3 i=1,2,3 (1)

[0107] When the driving signal g ie When (i=1,2,3,e=1,2,3,4) is at high level (value is 1), the corresponding power electronic switch device S ie (i=1,2,3,e=1,2,3,4) is turned on, when the driving signal g ie When (i=1,2,3,e=1,2,3,4) is at low level (value is 0), the corresponding power electronic switch device S ie (i=1,2,3,e=1,2,3,4) is turned off. Then from formula (1), we can know that the switching state function H of each power unitfi There are three possible values: 1, 0, and -1.

[0108] The output voltages of the inverter high, medium and low voltage power units are defined as u H1 、u H2 and u H3 , the total output voltage of the inverter is u AN , from the working principle of H bridge:

[0109] u Hi =H fi ×2 |i-3| ×E i=1,2,3 (2)

[0110] u AN =u H1 +u H2 +u H3 (3)

[0111] The high voltage power unit H1 can output three levels of ±4E and 0, the medium voltage power unit H2 can output three levels of ±2E and 0, and the low voltage power unit H3 can output three levels of ±E and 0. Therefore, the II-type asymmetric CHB fifteen-level inverter can output 15 levels of ±7E, ±6E, ±5E, ±4E, ±3E, ±2E, ±1E and 0.

[0112] From the permutations and combinations, it can be seen that the type II asymmetric CHB fifteen-level inverter has a total of 27 different switch state function combinations. The relationship between all switch state function combinations and output voltage is shown in Table 1.

[0113] Table 1 Relationship between switch state function combination and inverter output voltage

[0114]

[0115] It can be seen from Table 1 that when the output voltage of the type II asymmetric CHB fifteen-level inverter is ±E, ±2E, ±3E and ±5E, there is a power backflow phenomenon under some switching state function combinations. Therefore, it is necessary to optimize the inverter modulation strategy to avoid the inverter working under this switching state function combination.

[0116] The modulation principle of the traditional type II asymmetric CHB 15-level inverter is as follows Figure 4 As shown by Figure 4 It can be seen that the traditional II inverter modulation uses "step wave" modulation for the high voltage power unit H1 and the medium voltage power unit H2, and uses PWM modulation for the low voltage power unit H3. Now define the modulation wave v r The modulation index is m a , frequency is f m , then the expression of the modulation wave of each power unit of the inverter is:

[0117] v r =7m a sin(2πf m t) (4)

[0118]

[0119] Formula (4) is the modulation wave v of the high voltage power unit H1 r , and the amplitude is +3(v c1+ ) and -3(v c1- ) is compared with the potential when v r ≥v c1+ When the driving signal g 11 is high level, driving signal g 12 is low level; when v r <v c1+ When the driving signal g of the first insulated gate bipolar transistor of the high voltage power unit is 11 The driving signal g of the second insulated gate bipolar transistor of the high voltage power unit is low level. 12 is high level; when v r ≤v c1- When the driving signal g of the third insulated gate bipolar transistor of the high voltage power unit is 13 is high level, the driving signal g of the fourth insulated gate bipolar transistor of the high voltage power unit 14 is low level; when v r >v c1- When the driving signal g of the third insulated gate bipolar transistor of the high voltage power unit is 13 is low level, the driving signal g of the fourth insulated gate bipolar transistor of the high voltage power unit 14 is high level.

[0120] Modulation wave v of medium voltage power unit H2 r1 After processing by formula group (5), we can get c2+ ) and -1(v c2- ) is compared with the potential when v r1 ≥v c2+ When the driving signal g of the first insulated gate bipolar transistor of the medium voltage power unit is 21 is high, the driving signal g of the second insulated gate bipolar transistor of the medium voltage power unit 22 is low level; when v r1 <v c2+ When the driving signal g of the first insulated gate bipolar transistor of the medium voltage power unit is 21 is low level, the driving signal g of the second insulated gate bipolar transistor of the medium voltage power unit22 is high level; when v r1 ≤v c2- When the driving signal g of the third insulated gate bipolar transistor of the medium voltage power unit is 23 is high, the drive signal g of the fourth insulated gate bipolar transistor of the medium voltage power unit 24 is low level; when v r1 >v c2- When the driving signal g of the third insulated gate bipolar transistor of the medium voltage power unit is 23 is low level, the drive signal g of the fourth insulated gate bipolar transistor of the medium voltage power unit 24 is high level.

[0121] The modulation wave v of the low voltage power unit H3 r2 After processing by formula group (6), we can get cr , an isosceles triangle carrier with a peak-to-peak value of 0 to 1 (v c3+ ) and frequency f cr , an isosceles triangle carrier with a peak-to-peak value of -1 to 0 (v c3- ) for comparison, when v r2 ≥v c3+ When the driving signal g 31 is high level, driving signal g 32 is low level; when v r2 <v c3+ When the driving signal g 31 is low level, driving signal g 32 is high level; when v r2 ≤v c3- When the driving signal g 33 is high level, driving signal g 34 is low level; when v r2 >v c3- When the driving signal g 33 is low level, driving signal g 34 The switch state function of each power unit is calculated by formula (1), the output voltage of each power unit is calculated by formula (2), and the total output voltage of the inverter is calculated by formula (3).

[0122] exist Figure 4 When the total output voltage u AN When in [E, 2E] and [-E, -2E], the output voltage of the low voltage power unit H3 and the output voltage of the medium voltage power unit H2 have a partially opposite polarity. AN When in [3E, 4E] and [-3E, -4E], the output voltage of the low-voltage power unit H3 and the output voltage of the high-voltage power unit H1 have a partially opposite polarity.AN When in [5E, 6E] and [-5E, -6E], the output voltage of the low voltage power unit H3 is partially opposite to the polarity of the output voltage of the high voltage power unit H1 and the medium voltage power unit H2. Therefore, when the output voltage is in the above level state, the traditional II type asymmetric CHB 15-level inverter modulation has the problem of power backflow.

[0123] From the above analysis, it can be seen that the type II asymmetric CHB fifteen-level inverter has the problem of power backflow under the traditional modulation strategy, so it is necessary to optimize the switch state combination. By optimizing the switch state combination, the inverter can be prevented from working in a state with different polarity of the switch state function, so as to achieve the purpose of eliminating power backflow. The relationship between the remaining 15 switch state function combinations and the output voltage after optimization is shown in Table 2.

[0124] Table 2 Relationship between optimized switch state function combination and inverter output voltage

[0125]

[0126]

[0127] In Table 2, the 15 optimized switch state functions of the type II asymmetric CHB fifteen-level inverter correspond one-to-one to the output voltage of the inverter, there is no redundant state, and the output voltage polarity of the inverter is the same as the output voltage polarity of each power unit, and there is no problem of power backflow between the power units.

[0128] Step S2, according to the optimized switch state combination of each power unit, reasonably setting the modulation wave function and the comparison potential signal amplitude of each power unit of the type II asymmetric CHB fifteen-level inverter.

[0129] Aiming at the power backflow problem of type II asymmetric CHB 15-level inverter under traditional modulation strategy, an improved modulation strategy with switch state combination optimization is proposed. Figure 5 As shown. Define the modulation wave v m1 The modulation index is m a , frequency is f m , then the expression of the modulation wave is:

[0130] v m1 =7m a sin(2πf m t) (7)

[0131]

[0132] exist Figure 5 In, v cr1+ is a potential with an amplitude of 4, v cr1-is a potential with an amplitude of -4, v cr2+ is a potential with an amplitude of 2, v cr2- is a potential with an amplitude of -2, v cr3+ is a potential with an amplitude of 1, v cr3- is a potential with an amplitude of -1, v cr4+ is an isosceles triangular carrier wave with a frequency of f cr and a peak-to-peak value ranging from 0 to 1, v cr4- is an isosceles triangular carrier wave with a frequency of f cr and a peak-to-peak value ranging from -1 to 0. When the modulating wave v m1 ≥v cr1+ , the pulse signal a1 is at a high level. When the modulating wave v m1 <v cr1+ , the pulse signal a1 is at a low level; when the modulating wave v m1 ≥v cr1- , the pulse signal a2 is at a high level. When the modulating wave v m1 <v cr1- , the pulse signal a2 is at a low level; when the modulating wave v m2 ≥v cr2+ , the pulse signal b1 is at a high level. When the modulating wave v m2 <v cr2+ , the pulse signal b1 is at a low level; when the modulating wave v m2 ≥v cr2- , the pulse signal b2 is at a high level. When the modulating wave v m2 <v cr2- , the pulse signal b2 is at a low level; when the modulating wave v m3 ≥v cr3+ , the pulse signal c1 is at a high level. When the modulating wave v m3 <v cr3+ , the pulse signal c1 is at a low level; when the modulating wave v m3 ≥v cr3- , the pulse signal c2 is at a high level. When the modulating wave vm3 < vcr3-, the pulse signal c2 is at a low level; when the modulating wave v m4 ≥v cr4+ , the pulse signal d1 is at a high level. When the modulating wave v m4 <v cr4+ , the pulse signal d1 is at a low level; when the modulating wave v m4 ≥v cr4- , the pulse signal d2 is at a high level. When the modulating wave vm4 < vcr4-, the pulse signal d2 is at a low level. The obtained pulse signals a1, a2, b1, b2, c1, c2, d1, d2 are subjected to logical operations, and the drive signals for each power electronic switching device of the inverter are:

[0133]

[0134] In formula group (11), formula group (12) and formula (13), b1c1d1 indicates that b1, c1 and d1 are subjected to a logical AND operation. In formula group (11), formula group (12) and formula group (13), all AND symbols are not shown, and + indicates a logical OR operation.

[0135] The switch state function value of each power unit can be calculated by formula group (11), formula group (12), formula group (13) and formula (1). The output voltage of each power unit and the total output voltage of the inverter can be calculated by formula (1), formula (2) and formula (3). That is, by controlling the drive signal of each power electronic switch device, the waveform of the output voltage of each unit of the inverter can be controlled. Figure 5 in, u H1 、u H2 and u H3 are the output voltages of the high, medium and low voltage power units of the II type asymmetric CHB fifteen-level inverter, respectively. Figure 5 It can be seen that under the improved modulation strategy of switch state function combination optimization proposed in the present invention, the inverter high and medium voltage power units H1 and H2 work at a lower switching frequency, which can effectively reduce the switching loss of the high and medium voltage power units and improve the inverter efficiency. The low voltage power unit H3 works at a higher switching frequency, which can effectively improve the quality of the inverter output voltage waveform. The polarity of the output voltage of each power unit of the inverter is not different, indicating that the improved modulation strategy after the switch state function combination optimization can eliminate the power backflow problem existing in the traditional II type asymmetric CHB fifteen-level inverter modulation strategy.

[0136] Step S3, reconstructing the modulated wave, reducing the number of carrier and pulse signals, and reducing the difficulty of implementing the modulation strategy.

[0137] After optimizing the switch state combination, the power backflow problem existing in the modulation strategy of the traditional type II asymmetric CHB 15-level inverter is solved, but there is still a problem of a large number of pulse signals and carriers. By reconstructing the modulation wave, the number of pulse signals and carriers is reduced. The modulation principle is as follows Figure 5 As shown, the modulation wave v is defined as m5 The modulation index is m a , frequency is f m , then the expression of the reconstructed modulation wave is:

[0138] v m5 =7m a |sin(2πf m t)| (14)

[0139]

[0140] exist Figure 6 In, v cr1+ is a potential with an amplitude of 4, v cr2+ is a potential with an amplitude of 2, v cr3+ is a potential with an amplitude of 1, v cr4+ The frequency is f cr , an isosceles triangle carrier with a peak-to-peak value ranging from 0 to 1.

[0141] When the modulation wave v m5 ≥v cr1+ When the pulse signal a3 is high level, when the modulation wave v m5 <v cr1+ When , the pulse signal a3 is at a low level;

[0142] When the modulation wave v m6 ≥v cr2+ When the pulse signal b3 is high level, when the modulation wave v m6 <v cr2+ When , the pulse signal b3 is at a low level;

[0143] When the modulation wave v m7 ≥v cr3+ When the pulse signal c3 is high level, when the modulation wave v m7 <v cr3+ When , the pulse signal c3 is at a low level;

[0144] When the modulation wave v m8 ≥v cr4+ When the pulse signal d3 is high, the modulation wave v m8 <v cr4+ When , the pulse signal d3 is at a low level.

[0145] The obtained pulse signals a3, b3, c3, and d3 are subjected to logical operations, and the obtained working signals of each power unit of the inverter are:

[0146]

[0147] In formula group (18), b3c3d3 indicates that b3, c3 and d3 are logically ANDed. In formula group (18), all AND symbols are not shown. + indicates logical OR.

[0148] At the same time, in order to obtain the driving signal of each power electronic switch device of the inverter, the square wave signal is defined as g, and its frequency is f m , the first half cycle outputs a high level, and the second half cycle outputs a low level. The square wave signal g is subjected to a secondary logic operation with the working signal obtained by formula group (18), and the driving signal of each power electronic switch device of the inverter is obtained as follows:

[0149]

[0150] The switch state function value of each power unit can be calculated by formula group (19) and formula (1), and the output voltage of each power unit and the total output voltage of the inverter can be calculated by formula (1), formula (2) and formula (3). That is, by controlling the drive signal of each power electronic switch device, the waveform of the output voltage of each unit of the inverter can be controlled. Figure 7 in, u H1 is the output voltage of the high voltage power unit, u H2 is the output voltage of the medium voltage power unit, u H3 is the output voltage of the low voltage power unit, u AN is the total output voltage of the inverter.

[0151] Combination Figure 5 and Figure 7 It can be seen that the modulation strategy after modulation wave reconstruction has the same output voltage waveform as the modulation strategy after switching state function combination optimization. This indicates that the modulation strategy after modulation wave reconstruction is the same as the modulation strategy after switching state function combination optimization, and can also effectively eliminate the power backflow problem in the traditional modulation strategy. Moreover, compared with the modulation strategy after switching state function combination optimization, the modulation strategy after modulation wave reconstruction has the number of pulse signals and the number of carriers reduced by half, which greatly reduces the difficulty of implementing the modulation strategy.

[0152] Step S4, obtaining an improved modulation strategy for a type II asymmetric CHB fifteen-level inverter by coordinated control of the high voltage power unit, the medium voltage power unit and the low voltage power unit.

[0153] By coordinating the control of high voltage power unit, medium voltage power unit and low voltage power unit, an improved modulation strategy for type II asymmetric CHB fifteen-level inverter is obtained, which has the advantages of low switching frequency, high efficiency, easy implementation and low cost.

[0154] In order to verify the feasibility and effectiveness of the improved modulation strategy proposed in this invention, a type II asymmetric CHB fifteen-level inverter model with a voltage ratio of 4:2:1 was built by Matlab2018b / Simulink software. The output voltage waveform, the output power of each power unit and the output voltage spectrum distribution were analyzed when the modulation index was 0.3, 0.6 and 0.9 respectively. The simulation parameters are shown in Table 3.

[0155] Table 3 Simulation parameters

[0156]

[0157] The inverter output voltage waveform of the traditional modulation strategy when the modulation index is 0.3, 0.6 and 0.9 is as follows: Figure 8 shown.

[0158] Depend on Figure 8 It can be seen that under the traditional modulation strategy of the type II asymmetric fifteen-level inverter, the output voltage polarity of the low-voltage power unit H3 is opposite to the output voltage polarity of the high and medium voltage power units in each modulation index, which will lead to the occurrence of power backflow, and the output voltage of the high and medium voltage power units is in the shape of a "step wave", which will lead to an increase in the THD of the inverter output voltage and affect the quality of the inverter output voltage waveform.

[0159] Fig. 9 The output voltage waveform of the type II asymmetric CHB 15-level inverter under the improved modulation strategy. a When the values ​​are 0.3, 0.6 and 0.9 respectively, the output voltages are seven levels, eleven levels and fifteen levels respectively, which are the same as the number of output voltage levels of the inverter under the traditional modulation strategy.

[0160] Depend on Fig. 9 It can be seen that when the modulation indexes of the improved modulation strategy are 0.3, 0.6 and 0.9 respectively, the output voltage polarities of each power unit are the same, there is no power backflow, and the output voltage of the high and medium voltage power units is a multi-pulse waveform, which improves the quality of the output voltage waveform compared with the traditional modulation strategy.

[0161] The output power of each power unit of the type II asymmetric CHB 15-level inverter under the traditional modulation strategy is as follows: Fig.10 As shown. Fig.10 It can be seen that the low-voltage power unit H3 outputs negative power when the modulation index is 0.3, 0.6 and 0.9. At this time, the output voltage of the low-voltage power unit is opposite to the total output voltage of the type II asymmetric CHB 15-level inverter, that is, there is a power backflow phenomenon between the low-voltage power unit of the inverter and the high and medium voltage power units.

[0162] Fig.11 The output power waveform of each power unit of the II-type asymmetric CHB 15-level inverter under the improved modulation strategy is shown in Figure 1. Fig.10 It can be seen that when the modulation index is 0.3, 0.6 and 0.9 respectively, the output power of each power unit of the inverter is always greater than zero, so there is no power backflow phenomenon between the power units of the inverter under the improved modulation strategy.

[0163] Fig.12 is the output voltage u of the type II asymmetric CHB 15-level inverter under the traditional modulation strategy AN The spectrum distribution diagram when the modulation degrees are 0.3, 0.6 and 0.9 respectively. Fig.13 is the output voltage u of the type II asymmetric CHB 15-level inverter under the improved modulation strategy ANThe spectrum distribution diagram when the modulation degrees are 0.3, 0.6 and 0.9 respectively is given by Fig.12 as well as Fig.13 It can be seen that the harmonic frequency of the total output voltage of the inverter is mainly distributed around 5kHz. Fig.12 and Fig.13 Analysis shows that the THD value of the output voltage under the improved modulation strategy is better than that of the traditional modulation strategy, which shows that the improved modulation strategy can eliminate power backflow while ensuring the quality of the output voltage waveform.

[0164] In order to further verify the correctness and feasibility of the improved modulation strategy of the type II asymmetric CHB 15-level inverter, a type II asymmetric CHB 15-level inverter experimental platform with a voltage ratio of 4:2:1 was built, and DSP+FPGA was used to control it, and experiments were carried out to test its output waveform. The specific experimental parameters are shown in Table 4.

[0165] Table 4 Experimental platform parameter settings

[0166]

[0167] By setting the modulation index to 0.9 and 0.6 respectively and testing the output waveform when the modulation index is constant, the correctness and feasibility of the improved modulation strategy proposed in the present invention are verified.

[0168] Type II asymmetric CHB 15-level inverter with modulation index m a =0.9, the output voltage waveform of each unit of the inverter is as follows Fig.14 As shown. Fig.14 It can be seen that the type II asymmetric CHB fifteen-level inverter has a a =0.9, the low-voltage power unit adopts PWM wave for modulation, and the high and medium-voltage power units adopt a modulation strategy combining PWM and step wave, which can effectively improve the quality of the output voltage waveform while reducing switching losses. The output voltage polarity of each power unit of the inverter is the same in the positive and negative half-cycles, and there is no power backflow problem existing in the traditional modulation strategy, which verifies the correctness of the improved modulation strategy proposed in the present invention.

[0169] m a = 0.9, the inverter output voltage spectrum and output voltage and current waveforms are as follows Fig.15 As shown. Fig.15 It can be seen that the inverter has a modulation index m a When it is 0.9, the output voltage is at a fifteen-level level, and the harmonic frequency of the output voltage is mainly distributed around 5kHz, which is consistent with the results obtained from the simulation analysis.

[0170] Type II asymmetric CHB fifteen-level inverter with modulation index m a=0.6, the output voltage waveform of each unit of the inverter is as follows Fig.16 As shown. Combined Fig.14 and Fig.16 It can be seen that the type II asymmetric CHB 15-level inverter has a modulation index of m a =0.6, the output voltage polarity of each power unit of the inverter is the same in both positive and negative half-cycles, and is related to m a The same as when it is 0.9, there is no power backflow problem existing in the traditional modulation strategy.

[0171] m a =0.6, the inverter output voltage spectrum and output voltage and current waveforms are as follows Fig.17 As shown. Combined Fig.15 and Fig.17 It can be seen that the inverter output voltage level is m a = 0.9 when the fifteenth level drops to m a =0.6, the frequency spectrum of the inverter output voltage is mainly distributed at 5kHz, which is consistent with the results obtained by simulation analysis.

[0172] Type II asymmetric CHB fifteen-level inverter with modulation index m a When the power outputs of each power unit of the inverter are 0.9 and 0.6 respectively, the output power waveforms are as follows: Fig.18 and Fig.19 shown.

[0173] comprehensive Fig.18 and Fig.19 When the modulation index ma of the inverter is 0.6 and 0.9 respectively, under the improved modulation strategy, the output power of each power unit of the inverter is positive, and there is no power backflow problem, which is consistent with the simulation analysis results, confirming the authenticity and effectiveness of the modulation strategy proposed in this invention.

[0174] In addition, refer to Fig. 20 ,and Figure 2 Corresponding to the method, an inverter modulation system is also provided in an embodiment of the present application. The system can be used to modulate an inverter, wherein the inverter includes a first power unit, a second power unit and a third power unit, and the system may include a first processing unit 1001, a second processing unit 1002 and a third processing unit 1003. Among them, the first processing unit 1001 can be used to obtain a first modulation degree and a first frequency of an initial modulation wave. The second processing unit 1002 can be used to determine a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit based on the first modulation degree and the first frequency. The third processing unit 1003 can be used to determine a drive signal of each power electronic switching device in the inverter according to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, and modulate the output of the inverter through the drive signal.

[0175] It should be noted that the first processing unit may be any integrated circuit unit or microprocessor unit obtained by integrating a chip having a processing function and its peripheral circuits through existing integration technology. The first processing unit and the second processing unit may also be any integrated circuit module or microprocessor module obtained by integrating a chip having a processing function and its peripheral circuits through existing integration technology. The first processing unit and the second processing unit may also include one or more memories.

[0176] It should be noted that the contents of the above-mentioned inverter modulation method embodiment are all applicable to the present inverter modulation system embodiment. The functions specifically implemented by the present inverter modulation system embodiment are the same as those of the above-mentioned inverter modulation method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned inverter modulation method embodiment.

[0177] and Figure 2 Corresponding to the method, the embodiment of the present application also provides an inverter modulation device, and its specific structure can be referred to Fig.21 ,include:

[0178] at least one processor 1011;

[0179] At least one memory 1012, used to store at least one program;

[0180] When the at least one program is executed by the at least one processor, the at least one processor implements the inverter modulation method.

[0181] The contents of the above method embodiments are all applicable to the present device embodiments. The functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0182] and Figure 1 Corresponding to the method, an embodiment of the present application further provides a computer-readable storage medium, which stores processor-executable instructions, and the processor-executable instructions are used to execute the inverter modulation method when executed by the processor.

[0183] The contents of the above-mentioned inverter modulation method embodiment are all applicable to the present storage medium embodiment. The functions specifically implemented by the present storage medium embodiment are the same as those of the above-mentioned inverter modulation method embodiment, and the beneficial effects achieved are also the same as those achieved by the above-mentioned inverter modulation method embodiment.

[0184] In some optional embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the application is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Optional embodiments are expected, wherein the order of various operations is changed and the sub-operation described as a part of a larger operation is performed independently.

[0185] In addition, although the present application is described in the context of functional modules, it should be understood that, unless otherwise specified, one or more of the functions and / or features can be integrated into a single physical device and / or software module, or one or more functions and / or features can be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present application. More specifically, in view of the properties, functions, and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional techniques of the engineer. Therefore, those skilled in the art can implement the present application set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present application, which is determined by the full scope of the attached claims and their equivalents.

[0186] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several programs to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0187] The logic and / or steps represented in the flowchart or otherwise described herein, for example, may be considered as an ordered list of executable programs for implementing the logical functions, and may be embodied in any computer-readable medium for use by a program execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch and execute a program from a program execution system, device or apparatus), or in conjunction with such program execution systems, devices or apparatuses. For purposes of this specification, a "computer-readable medium" may be any device that can contain, store, communicate, propagate or transmit a program for use by a program execution system, device or apparatus, or in conjunction with such program execution systems, devices or apparatuses.

[0188] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0189] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable program execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0190] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0191] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

[0192] The above is a specific description of the preferred implementation of the present application, but the present application is not limited to the described embodiments. Technical personnel familiar with the field may make various equivalent modifications or substitutions without violating the spirit of the present application. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present application.

Claims

1. An inverter modulation method, characterized in that: For modulating an inverter, wherein the inverter includes a first power unit, a second power unit, and a third power unit, the method includes: Obtaining a first modulation degree and a first frequency of an initial modulation wave; Based on the first modulation degree and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit; According to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, a driving signal of each power electronic switching device in the inverter is determined, and the output of the inverter is modulated by the driving signal.

2. The inverter modulation method according to claim 1, characterized in that: Based on the first modulation degree and the first frequency, determining a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit includes: Determine a reconstructed modulated wave based on the first modulation degree and the first frequency; The first modulation wave signal, the second modulation wave signal and the third modulation wave signal are determined according to the reconstructed modulation wave.

3. The inverter modulation method according to claim 2, characterized in that: Determining a reconstructed modulated wave based on the first modulation degree and the first frequency includes: Substituting the first modulation degree and the first frequency into the first waveform expression, a reconstructed modulated wave is obtained, wherein the first waveform expression is: v m5 =7m a |sin(2πf m t)| where v m5 To reconstruct the modulated wave, m a is the first modulation index, f m is the first frequency.

4. The inverter modulation method according to claim 2, characterized in that: The determining the first modulation wave signal, the second modulation wave signal and the third modulation wave signal according to the reconstructed modulation wave comprises: Substitute the reconstructed modulation wave into the first formula group to determine the first modulation wave signal; wherein the first formula group is: Substitute the first modulated wave signal into the second formula group to determine the second modulated wave signal; wherein the second formula group is: Substitute the second modulated wave signal into the third formula group to determine the third modulated wave signal; wherein the third formula group is:

5. The inverter modulation method according to claim 1, characterized in that: The first power unit, the second power unit and the third power unit each include a first power electronic switch device, a second power electronic switch device, a third power electronic switch device and a fourth power electronic switch device, and determining a drive signal of each power electronic switch device in the inverter according to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, and modulating the output of the inverter by the drive signal, including: Determine a first working signal of the first power unit, a second working signal of the second power unit, and a third working signal of the third power unit according to the first modulated wave signal, the second modulated wave signal, and the third modulated wave signal; According to the first working signal, the second working signal and the third working signal, a first drive signal of the first power electronic switching device, a second drive signal of the second power electronic switching device, a third drive signal of the third power electronic switching device and a fourth drive signal of the fourth power electronic switching device are determined, and the output of the inverter is modulated by the first drive signal, the second drive signal, the third drive signal and the fourth drive signal.

6. The inverter modulation method according to claim 5, characterized in that: The determining, according to the first modulated wave signal, the second modulated wave signal and the third modulated wave signal, the first working signal of the first power unit, the second working signal of the second power unit and the third working signal of the third power unit comprises: Convert the first modulated wave signal into a first level signal, convert the second modulated wave signal into a second level signal, and convert the third modulated wave signal into a third level signal; The first working signal, the second working signal and the third working signal are determined according to the first level signal, the second level signal and the third level signal.

7. The inverter modulation method according to claim 5, characterized in that: The determining, according to the first working signal, the second working signal, and the third working signal, a first driving signal of the first power electronic switching device, a second driving signal of the second power electronic switching device, a third driving signal of the third power electronic switching device, and a fourth driving signal of the fourth power electronic switching device comprises: Substituting the first working signal, the second working signal, and the third working signal into the fourth formula group, the first driving signal, the second driving signal, the third driving signal, and the fourth driving signal are obtained; wherein the fourth formula group is: Among them, g is the preset square wave signal, SH i is the working signal, i is the serial number of the working signal, and also the serial number of the power unit, g i1 is the first driving signal, g i2 is the second driving signal, g i3 is the third driving signal, g i4 is the fourth driving signal; SH i g stands for SH i Perform a logical AND operation with g, Indicates the negation of g, Indicates SH i Perform a logical AND operation with the negation of g.

8. An inverter modulation system, characterized in that: For modulating an inverter, wherein the inverter includes a first power unit, a second power unit, and a third power unit, the system includes: A first processing unit, used for obtaining a first modulation degree and a first frequency of an initial modulation wave; a second processing unit, configured to determine, based on the first modulation degree and the first frequency, a first modulation wave signal of the first power unit, a second modulation wave signal of the second power unit, and a third modulation wave signal of the third power unit; The third processing unit is used to determine the driving signal of each power electronic switching device in the inverter according to the first modulation wave signal, the second modulation wave signal and the third modulation wave signal, and modulate the output of the inverter through the driving signal.

9. An inverter modulation device, characterized in that include: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the inverter modulation method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing instructions executable by a processor, characterized in that: The processor-executable instructions are used to execute an inverter modulation method as described in any one of claims 1-7 when executed by the processor.

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