Three-phase four-leg three-level direct matrix converter and SVPWM modulation method

Abstract

The present invention belongs to the technical field of matrix converters, and discloses a three-phase four-leg three-level direct matrix converter and an SVPWM modulation method. The topology consists of 24 bidirectional switches and 8 flying capacitors. Each of the four legs A, B, C, and N includes 9 output switching states and 6 output voltages. There are a total of 6561 switching states, and the output phase line voltages altogether include six output voltages. The present invention proposes a novel SVPWM modulation method. This method mainly transforms the control of the output voltage from the conventional αβ coordinate system to the abc coordinate system, while the input current is still modulated separately in the αβ coordinate system. The biggest advantage of using the abc coordinate system is that through coordinate translation, the three-level modulation can be simplified to two-level modulation, greatly reducing the increase in algorithm complexity caused by the increase in the number of levels.

Description

Technical Field

[0001] The present invention belongs to the technical field of matrix converters, and particularly relates to a three-phase four-leg three-level direct matrix converter and an SVPWM modulation method. Background Art

[0002] The AC-AC conversion technology mainly converts one type of AC electrical energy into another type of electrical energy through power semiconductor devices, and is a major research focus in power electronics research. With the development of the times, in defense fields such as aviation, aerospace, and navigation, and civilian fields such as power electrics, power systems, energy transportation, petroleum textiles, industrial control, renewable energy power generation, and household appliances, the AC-AC converter is an indispensable technology.

[0003] The matrix converter is a new type of AC-AC converter. Compared with the commonly used AC-DC-AC topology structure at present, it has advantages such as bidirectional energy flow, controllable input power factor, high reliability, compact structure, small weight, low cost, and long service life, and has gradually become a research hotspot for scholars at home and abroad.

[0004] However, most of the current research on matrix converters is limited to the three-leg two-level structure and cannot be applied to systems with single-phase loads. By studying the conventional four-leg matrix converter and the three-leg three-level direct matrix converter, the topology structure of the three-phase four-leg three-level direct matrix converter is derived. Compared with the conventional four-leg matrix converter, the three-phase four-leg three-level direct matrix converter optimizes the output waveform, reduces the switching frequency and switching stress. Compared with the three-leg three-level direct matrix converter, it also increases the ability to supply power to unbalanced loads. However, with the increase in the number of levels and legs, the topology and space vector modulation difficulty of the matrix converter will increase.

[0005] Through the above analysis, the problems and defects of the existing technology are as follows:

[0006] (1) With the improvement of energy conservation and environmental protection requirements, problems such as the large DC energy storage components included in the AC-DC-AC converter topology and the uncontrollable input power factor have gradually become a major problem to be solved.

[0007] (2) With the increase in the number of levels and legs, the topology and space vector modulation difficulty of the matrix converter will increase. Summary of the Invention

[0008] Aiming at the problems of the existing technology, the present invention provides a three-phase four-leg three-level direct matrix converter and an SVPWM modulation method.

[0009] The present invention is implemented as follows. A three-phase four-leg three-level direct matrix converter. The topology of the three-phase four-leg three-level direct matrix converter consists of 24 bidirectional switches and 8 flying capacitors. Each of the four legs A, B, C, and N includes 9 output switch states and 6 output voltages. There are 9 4 = 6561 kinds of switch states. The output line voltages altogether include six output voltages, which are divided into three full voltages and three half voltages. There are 9 2 = 81 kinds of switch states in total.

[0010] Furthermore, for the three-phase four-leg three-level direct matrix converter, all vectors are classified into the following 19 types:

[0011] (1) Each output leg is connected to a different full-voltage input branch. Each output state has only 1 switching mode, and their voltage vector angles change with time in the vector space and usually cannot be used for modulation;

[0012] (2) Each output leg is connected to a different half-voltage input branch. Each output state corresponds to 16 switching modes, but their voltage vector angles change with time and usually cannot be used for modulation either;

[0013] (3) Each output leg is connected to a common full-voltage input branch. This type is the zero state used in the matrix converter. Each output state has only one switching mode, and the present invention calls it the "original" zero state to distinguish it from the additional zero states;

[0014] (4) Each output leg is connected to a common half-voltage input branch. This type is the additional zero state generated by the matrix converter. Each output state has 16 switching modes. Considering that the zero state only occupies the redundant time in the modulation algorithm, if the additional zero state is used, more complex flying capacitor voltage control needs to be considered. Therefore, only the original zero vector is used in the modulation process;

[0015] (5) Three output legs are connected to a common full-voltage input branch, and the remaining output leg is connected to another full-voltage input branch. Among these 24 states, each state has only one switching mode and can be divided into two categories: when the special leg is the N phase, the output amplitude is There are a total of 6 states. The remaining 18 are the states used in the traditional matrix converter, with an amplitude of Vin;

[0016] (6) Three output legs are connected to a common half-voltage input branch, and the remaining output leg is connected to another half-voltage input branch. This generates another 24 states. Each state has 16 switching modes and has two different input current vector angle directions and can be divided into two categories: when the special leg is the N phase, the output amplitude is There are a total of 6 states, and the remaining 18 state vector amplitudes are Vin / 2;

[0017] (7) Three output bridge arms are connected to a common full-voltage input branch, and the remaining output bridge arms are connected to a half-voltage input branch. Among these 36 states, each state has two switching modes and can be divided into two categories: When the special bridge arm is the N phase, the output amplitude is There are a total of 9 states. The remaining 27 state vector amplitudes are Vin / 2;

[0018] (8) Three output bridge arms are connected to a common half-voltage input branch, and the remaining output bridge arms are connected to a full-voltage input branch. Among all these 36 states, each state has 8 switching modes and can be divided into two categories: When the special bridge arm is the N phase, the output amplitude is There are a total of 9 states. The remaining 27 state vector amplitudes are Vin / 2;

[0019] (9) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are connected to the same other common full-voltage input branch. Among all 18 states, each state has only 1 switching mode, and the amplitude is

[0020] (10) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are connected to the same common half-voltage input branch. Among all 54 states, each state has only 4 switching modes, and 18 of these states are not used in modulation because the voltage vector angles are all time-varying. The remaining 36 states have an amplitude of

[0021] (11) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to the same other common half-voltage input branch. Among all 18 states, each state has 16 switching modes, and the amplitude is

[0022] (12) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are respectively connected to the same other common full-voltage input branch. Among all 72 states, when the special bridge arm is connected to a separate full-voltage input branch as the N phase, 18 states are not used in modulation because the voltage vector angles are all time-varying. Each of the remaining 54 states has only 1 switching state, and the amplitude is

[0023] (13) Two output bridge arms are connected to a common full - voltage input branch, and the remaining two output bridge arms are respectively connected to different common half - voltage input branches. Among all 216 states, when the special bridge arm is the N - phase connected to a separate half - voltage input branch, since the voltage vector angles are all time - varying, a total of 27 states are not used in modulation. For the remaining 189 states, each state has only 4 switching states, and the amplitude is

[0024] (14) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are respectively connected to other different common full - voltage input branches. Among all 216 states, when the special bridge arm is the N - phase connected to a separate full - voltage input branch, since the voltage vector angles are all time - varying, a total of 27 states are not used in modulation. For the remaining 189 states, each state has only 4 switching states, and the amplitude is

[0025] (15) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are respectively connected to different common full - voltage input branches. Among all 72 states, when the special bridge arm is the N - phase connected to a separate full - voltage input branch, since the voltage vector angles are all time - varying, a total of 18 states are not used in modulation. For the remaining 54 states, each state has only 16 switching states, and the amplitude is

[0026] (16) Two output bridge arms are connected to a common full - voltage input branch, and one of the remaining two output bridge arms is connected to a different full - voltage input branch and the other is connected to a half - voltage input branch. Among all 432 states, each state has only 2 switching states. When the special bridge arm is the N - phase connected to a separate full - voltage input branch, there are 54 states in total, and the amplitude is 3Vin / 2. When the special bridge arm is the N - phase connected to a half - voltage input branch, there are 54 states in total, and the amplitude is For the remaining 324 states, the amplitude is

[0027]

[0028] (17) Two output bridge arms are connected to a common half - voltage input branch, and one of the remaining two output bridge arms is connected to a full - voltage input branch and the other is connected to a different half - voltage input branch. Among all 432 states, each state has only 8 switching states. When the special bridge arm is the N - phase connected to a full - voltage input branch, there are 54 states in total, and the amplitude is When the special bridge arm is the N - phase connected to a separate half - voltage input branch, there are 54 states in total, and the amplitude is For the remaining 324 states, the amplitude is

[0029] (18) Two output bridge arms are connected to a common full - voltage input branch, and the remaining two output bridge arms are connected to different half - voltage input branches. Among all 432 states, each state has only 4 switching states. When the special bridge arm is connected to the half - voltage input branch in the N - phase, there are 108 states in total, and the amplitude is For the remaining 324 states, the amplitude is

[0030] (19) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are connected to different full - voltage input branches. Among all 432 states, each state has only 4 switching states. When the special bridge arm is connected to the full - voltage input branch in the N - phase, there are 108 states in total, and the amplitude is For the remaining 324 states, the amplitude is

[0031] Another object of the present invention is to provide an SVPWM modulation method, and the SVPWM modulation method includes:

[0032] Step 1, three - phase four - bridge - arm three - level output cube positioning;

[0033] Step 2, three - phase four - bridge - arm three - level duty - cycle calculation.

[0034] Further, the three - phase four - bridge - arm three - level output cube positioning includes:

[0035] (1) Assume that the three - phase input voltage is:

[0036]

[0037] where u a , u b , u c are the transient values of the a, b, and c - phase input voltages respectively, and U i and ω i are the effective value and angular frequency of the input phase voltage respectively;

[0038] Assume that the ideal output voltage is:

[0039]

[0040] where u A , u B , u C are the transient values of the A, B, and C - phase output voltages respectively, and U o and ω o are the effective value and angular frequency of the output phase voltage respectively;

[0041] (2) Transform the output current into the two-phase stationary coordinate system through formula (3), and obtain the space vector corresponding to the input current at this moment, which is the same as the current space vector diagram formed by the flying capacitor multilevel matrix converter:

[0042]

[0043] (3) Draw the output voltage space vector diagram, and the finally output phase voltage is ±u ab 、±u bc 、±u ca and ±u ab / 2, ±U bc / 2, ±u ca / 2, twelve kinds of output line voltages;

[0044] (4) Through the positive and negative of u A , u B , u C of the three output phase voltages, divide the space vector diagram into 6 pentahedrons;

[0045] (5) Further divide the pentahedrons. First, translate all the pentahedrons so that all the coordinates in the pentahedron are positive, that is, subtract each switching vector by the equivalent origin corresponding to each pentahedron, and then divide the translated pentahedrons according to the relationship between the magnitudes of the phase voltages of phases A, B, and C and the half voltage, and then translate the equivalent origin of the cube. Finally, translate all the cubes to the same position;

[0046] (6) Divide the cube after translation into tetrahedrons, divide it into six tetrahedrons, and the vector falling in a certain tetrahedron is synthesized by the four vertices of the tetrahedron.

[0047] Furthermore, for the calculation of the duty ratio of the three-phase four-leg three-level, the translated coordinates are used for calculation, and during the calculation process, only the numerical values in the coordinates, that is, n times the input line voltage, are used. Assuming that the coordinates of the vector to be synthesized are (U A , U B , U C ), the following equations can be obtained in the present invention:

[0048]

[0049] It can be seen that when using the abc coordinate system for duty ratio calculation, no complex arctangent function is required, and only simple addition and subtraction of the magnitudes of each phase voltage are needed. Simplifying the above formula, we can get:

[0050]

[0051] Since the calculation of the input current does not increase with the increase in the number of levels, the input current still adopts the αβ coordinate system, that is, the calculation result is the same as that of the flying-capacitor multilevel matrix converter, and the current satisfies formula (6).

[0052]

[0053] Combining formula (5) and (6), the final duty cycle as shown in (7) can be obtained:

[0054]

[0055] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which when executed by a processor causes the processor to execute the steps of the SVPWM modulation method.

[0056] Another object of the present invention is to provide an information data processing terminal for implementing the three-phase four-leg three-level direct matrix converter and the SVPWM modulation method.

[0057] The present invention provides a control method for a three-phase four-leg three-level direct matrix converter, and the method includes the following steps:

[0058] (1) According to the topological structure of the three-phase four-leg three-level direct matrix converter, by controlling 24 bidirectional switches and 8 flying capacitors, the voltage and current outputs of the converter are realized;

[0059] (2) According to the output requirements of the converter, select appropriate vector types, including full-voltage input branch connection, half-voltage input branch connection, and common input branch connection, etc.;

[0060] (3) According to the selected vector type, determine the switching states and switching modes of each output leg to achieve the required output voltage and current;

[0061] (4) During the modulation process, preferentially use the original zero state to avoid the complexity of flying-capacitor voltage control brought by using additional zero states;

[0062] (5) According to the output requirements and the working state of the converter, dynamically adjust the switching states and switching modes to achieve efficient and stable power conversion.

[0063] The present invention provides a modulation method for a three-phase four-leg three-level direct matrix converter, and the method includes the following steps:

[0064] (1) According to the vector classification of the three-phase four-leg three-level direct matrix converter, select a vector type suitable for the modulation requirements;

[0065] (2) Construct the corresponding modulation algorithm according to the selected vector type, including the selection of switch states, the determination of switching modes, and the allocation of modulation time;

[0066] (3) Generate a control signal according to the modulation algorithm, and adjust the output voltage and current by controlling the on / off of the bidirectional switch;

[0067] (4) During the modulation process, monitor in real time the parameters such as the output voltage, current, and flying capacitor voltage of the converter, and dynamically adjust the modulation algorithm according to the monitoring results to optimize the power conversion effect;

[0068] (5) By repeatedly executing the above steps, realize the continuous and stable modulation of the three-phase four-leg three-level direct matrix converter.

[0069] The present invention provides a fault diagnosis and processing method for a three-phase four-leg three-level direct matrix converter, and the method includes the following steps:

[0070] (1) Collect key parameters such as switch states, voltages, and currents by monitoring the operating state of the three-phase four-leg three-level direct matrix converter;

[0071] (2) Process and analyze the collected data to identify potential fault modes, such as switch failures, flying capacitor faults, etc.;

[0072] (3) Take corresponding processing measures according to the identified fault modes, such as replacing the failed switch, adjusting the voltage of the flying capacitor, etc.;

[0073] (4) During the fault handling process, monitor the operating state of the converter in real time to ensure the effectiveness of the handling measures;

[0074] (5) Record and analyze the fault handling process, summarize experience and lessons, and optimize the fault diagnosis and processing method.

[0075] The present invention provides an optimized control method for a three-phase four-leg three-level direct matrix converter, and the method includes the following steps:

[0076] (1) Establish a corresponding mathematical model according to the topological structure and operating characteristics of the three-phase four-leg three-level direct matrix converter;

[0077] (2) Based on the mathematical model, analyze the variation laws of key parameters such as the voltage, current, and power of the converter;

[0078] (3) According to the analysis results, formulate an optimized control strategy, such as reducing switch losses, improving conversion efficiency, optimizing output voltage quality, etc.;

[0079] (4) According to the optimized control strategy, adjust the switching state and switching mode of the converter to achieve the optimized control of key parameters;

[0080] (5) Through real-time monitoring and feedback mechanism, evaluate and adjust the optimized control effect to achieve the best performance of the three-phase four-leg three-level direct matrix converter.

[0081] Combined with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by the present invention are as follows:

[0082] First, compared with the conventional four-leg matrix converter, the three-phase four-leg three-level direct matrix converter optimizes the output waveform, reduces the switching frequency and switching stress, and compared with the three-leg three-level direct matrix converter, it also increases the ability to supply power to unbalanced loads.

[0083] The present invention proposes a new SVPWM modulation method. This method mainly transforms the control of the output voltage from the conventional αβ coordinate system to the abc coordinate system for modulation. After the coordinate system is switched, through coordinate translation, the three-level can be simplified to two-level for modulation, greatly reducing the increase in algorithm complexity caused by the increase in the number of levels.

[0084] Second, the significant technical progress reflected by this three-phase four-leg three-level direct matrix converter is mainly reflected in the following aspects:

[0085] 1. Improvement of vector classification and energy conversion efficiency:

[0086] By classifying all vectors in detail, the converter can select appropriate vector combinations for energy conversion according to the requirements of different application scenarios. This classification method makes the energy conversion more flexible and efficient, improving the overall performance of the system.

[0087] 2. Enhancement of the diversity and flexibility of output voltage vectors:

[0088] By including various vector classifications, the converter can generate output voltages with different amplitudes and switching modes, thus meeting the requirements under different load conditions. This diversity makes the converter more adaptable to the complex and changeable actual working environment.

[0089] 3. Improvement of system stability and reliability:

[0090] By classifying vectors in detail, the converter can optimize the combination of output voltage vectors, reduce unnecessary switching and losses, thereby improving the stability and reliability of the system. At the same time, this also helps to reduce the maintenance cost and extend the service life of the system.

[0091] 4. Promotion of the development of matrix converter technology:

[0092] The design concept and implementation method of this three-phase four-leg three-level direct matrix converter provide new ideas and methods for the development of matrix converter technology. This technological progress not only promotes the research and application in related fields but also lays a solid foundation for the future development of power electronics technology.

[0093] This three-phase four-leg three-level direct matrix converter has shown significant technological progress in aspects such as vector classification, energy conversion efficiency, output voltage vector diversity, and system stability and reliability, providing new impetus for the development and application of power electronics technology.

[0094] Third, the technical problems solved by the present invention and the obtained technical effects are mainly reflected in the following aspects:

[0095] Technical problems:

[0096] 1. Control accuracy of output voltage and current: In the application of the three-phase four-leg three-level direct matrix converter, it is necessary to achieve high-precision control of the output voltage and current. However, due to complex calculations and lookup table operations in traditional control methods, it is difficult to achieve ideal control effects.

[0097] 2. Complexity of hardware implementation: Complex control algorithms usually require more hardware resources to implement, which not only increases costs but also reduces the stability and reliability of the system.

[0098] 3. Voltage control during modulation: During the modulation process of the matrix converter, it is necessary to effectively control the voltage of the flying capacitor to avoid the impact of voltage fluctuations on system performance.

[0099] Technical effects:

[0100] 1. Improve control accuracy: The present invention adopts a control method based on double-line voltage synthesis. By separately controlling the fourth leg, the average value of the output voltage of the fourth leg in each sampling modulation period is the same as the average value of the common-mode voltage of the first three legs. This method does not require complex calculations and a large number of lookup table operations, thus improving the control accuracy of the output voltage and current.

[0101] 2. Simplify hardware implementation: Since the method of the present invention avoids complex calculations and lookup table operations, it is beneficial for hardware implementation, reduces the hardware cost of the system, and improves stability and reliability.

[0102] 3. Optimize voltage control: During the modulation process, the method of the present invention can effectively control the voltage of the flying capacitor, reduce voltage fluctuations, and improve the stability and performance of the system.

[0103] By optimizing the control method, the present invention not only improves the performance of the three-phase four-leg three-level direct matrix converter, but also simplifies the hardware implementation, reduces the cost, and has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 is the flying-capacitor three-phase four-leg three-level direct matrix converter provided by the embodiment of the present invention;

[0105] Figure 2 is the flowchart of the SVPWM modulation method provided by the embodiment of the present invention;

[0106] Figure 3 is the output voltage vector diagram provided by the embodiment of the present invention;

[0107] Figure 4 is the division of the output voltage pentahedron provided by the embodiment of the present invention;

[0108] Figure 5 is the further division of the output voltage pentahedron provided by the embodiment of the present invention;

[0109] Figure 6 is the output voltage tetrahedron provided by the embodiment of the present invention;

[0110] Figure 7 is the output voltage and input current sectors provided by the embodiment of the present invention;

[0111] Figure 8 is the output line voltage and FFT analysis of the three-phase four-leg three-level direct matrix converter provided by the embodiment of the present invention;

[0112] Figure 9 is the output line voltage and FFT analysis of the four-leg matrix converter provided by the embodiment of the present invention;

[0113] Figure 10 is the output line voltage and FFT analysis of the flying-capacitor multilevel matrix converter provided by the embodiment of the present invention;

[0114] Figure 11 is the input phase voltage and phase current of the three-phase four-leg three-level direct matrix converter provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0115] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0116] The following are two specific embodiments of the control method for the three-phase four-leg three-level direct matrix converter:

[0117] Embodiment 1: Modulation Method Based on Voltage Vector Classification

[0118] In this embodiment, the present invention adopts a modulation method based on voltage vector classification to achieve efficient modulation of a three-phase four-leg three-level direct matrix converter.

[0119] First, according to the vector classification in Claim 1, the present invention identifies 19 different types of voltage vectors. Then, according to the current output requirements, the present invention selects appropriate vector types for modulation.

[0120] For example, when full voltage needs to be output, the present invention selects vectors of type (1) or type (5), where the output leg is connected to different full voltage input branches. By precisely controlling the switch states and switching patterns, the present invention can achieve the required full voltage output.

[0121] Similarly, when half voltage needs to be output, the present invention selects vectors of type (2) or type (6), where the output leg is connected to different half voltage input branches. By adjusting the switch states and switching patterns, the present invention can achieve the required half voltage output.

[0122] During the modulation process, the present invention preferentially uses the original zero state to avoid the complexity brought by additional zero states. At the same time, the present invention dynamically adjusts the switch states and switching patterns according to the operating state and output requirements of the converter to achieve efficient and stable power conversion.

[0123] Embodiment 2: Fault Diagnosis and Handling Method Based on Optimized Control Strategy

[0124] In this embodiment, the present invention adopts a fault diagnosis and handling method based on an optimized control strategy to improve the reliability and safety of a three-phase four-leg three-level direct matrix converter.

[0125] First, the present invention monitors the operating state of the converter and collects key parameters such as switch states, voltages, and currents. Then, using advanced signal processing and data mining techniques, the collected data is processed and analyzed to identify potential fault patterns.

[0126] Once a fault pattern is identified, the present invention immediately takes corresponding handling measures. For example, if a switch failure is detected, the present invention will immediately replace the failed switch to restore the normal operation of the converter. If a flying capacitor fault is detected, the present invention will adjust the voltage of the capacitor or replace it to ensure the stable operation of the system.

[0127] During the fault handling process, the present invention monitors the operating status of the converter in real time and dynamically adjusts the handling measures according to the feedback results. At the same time, the present invention also records and analyzes the fault handling process and summarizes the lessons learned so as to better prevent and handle similar faults in future operations.

[0128] By implementing the fault diagnosis and processing method based on the optimization control strategy, the present invention can significantly improve the reliability and safety of the three-phase four-bridge-arm three-level direct matrix converter, reduce the failure rate, and improve the overall performance of the system.

[0129] like Figure 1 As shown in FIG. 1 , the three-phase four-bridge-arm three-level direct matrix converter topology provided in the embodiment of the present invention is composed of 24 bidirectional switches and 8 flying capacitors. The four bridge arms A, B, C, and N each include 9 output switch states and 6 output voltages. Therefore, there are 9 switch states in total. 4 = 6561, but due to the existence of rotating vectors, not all switching vectors can be used. The output phase line voltage contains a total of six output voltages, divided into three full voltages and three half voltages, and the switching states have a total of 9 2 =81, but due to the existence of the rotating vector, the available switching states are shown in Table 1.

[0130] Table 1A, N bridge arm working state combination and output level

[0131]

[0132]

[0133]

[0134]

[0135] It can be seen from Table 1 that there are 6 voltage output levels of the A and N bridge arms, 54 available working modes, and 27 unavailable modes. The unavailable modes are mainly because the output phase voltage cannot be simplified to a multiple of the input line voltage through simple equivalent calculation. A =(U a +U b ) / 2,U N =U c , after calculation, we get U AN =(U a +U b -2U c ) / 2, and since the input power is AC power, the final U AN The value of is difficult to determine, that is, it is judged as an unavailable vector. Each working mode of the four bridge arms corresponds to an output level (U AN ,UBN , U CN ), which is also called a switching vector. However, different switching vectors also output the same number of levels. Those switching vectors that can output the same voltage level are called redundant switching vector points. All vectors are classified into the following 19 types:

[0136] (1) Each output arm is connected to a different full-voltage input branch. Each output state has only 1 switching mode, and their voltage vector angles change with time in the vector space and are usually not suitable for modulation.

[0137] (2) Each output arm is connected to a different half-voltage input branch. Each output state corresponds to 16 switching modes, but their voltage vector angles change with time and are usually not suitable for modulation either.

[0138] (3) Each output arm is connected to a common full-voltage input branch. This is the zero state used in matrix converters. Each output state has only one switching mode, and the present invention calls it the "original" zero state to distinguish it from the additional zero states.

[0139] (4) Each output arm is connected to a common half-voltage input branch. This is the additional zero state generated by matrix converters. Each output state has 16 switching modes. Considering that the zero state only occupies the redundant time in the modulation algorithm, if the additional zero state is used, more complex flying capacitor voltage control needs to be considered. Therefore, only the original zero vector is used in the modulation process.

[0140] (5) Three output arms are connected to a common full-voltage input branch, and the remaining output arm is connected to another full-voltage input branch. Among these 24 states, each state has only one switching mode and can be divided into two categories: when the special arm is the N phase, the output amplitude is There are a total of 6 states. The remaining 18 are the states used in traditional matrix converters, with an amplitude of Vin.

[0141] (6) Three output arms are connected to a common half-voltage input branch, and the remaining output arm is connected to another half-voltage input branch. This generates another 24 states, each state having 16 switching modes and having two different input current vector angle directions, which can be divided into two categories: when the special arm is the N phase, the output amplitude is There are a total of 6 states. The remaining 18 state vectors have an amplitude of Vin / 2.

[0142] (7) Three output arms are connected to a common full-voltage input branch, and the remaining output arm is connected to a half-voltage input branch. Among these 36 states, each state has two switching modes and can be divided into two categories: when the special arm is the N phase, the output amplitude is There are a total of 9 states. The remaining 27 state vector amplitudes are Vin / 2.

[0143] (8) Three output bridge arms are connected to a common half-voltage input branch, and the remaining output bridge arms are connected to the full-voltage input branch. Among all these 36 states, each state has 8 switching modes, which can be divided into two categories: when the special bridge arm is the N phase, the output amplitude is There are a total of 9 states. The remaining 27 state vector amplitudes are Vin / 2.

[0144] (9) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are connected to the same other common full-voltage input branch. Among all 18 states, each state has only 1 switching mode, and the amplitude is

[0145] (10) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are connected to the same common half-voltage input branch. Among all 54 states, each state has only 4 switching modes, and among them, 18 states are not used in modulation because the voltage vector angles are all time-varying. The remaining 36 states have an amplitude of

[0146] (11) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to the same other common half-voltage input branch. Among all 18 states, each state has 16 switching modes, and the amplitude is

[0147] (12) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are respectively connected to the same other common full-voltage input branches. Among all 72 states, when the special bridge arm is the N phase connected to the separate full-voltage input branch, since the voltage vector angles are all time-varying, a total of 18 states are not used in modulation. Each of the remaining 54 states has only 1 switching state, and the amplitude is

[0148] (13) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are respectively connected to different common half-voltage input branches. Among all 216 states, when the special bridge arm is the N phase connected to the separate half-voltage input branch, since the voltage vector angles are all time-varying, a total of 27 states are not used in modulation. Each of the remaining 189 states has only 4 switching states, and the amplitude is

[0149] (14) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are respectively connected to other different common full - voltage input branches. Among all 216 states, when the special bridge arm is connected to a single full - voltage input branch in the N - phase, since the voltage vector angles are all time - varying, a total of 27 states are not used in modulation. Each of the remaining 189 states has only 4 switching states, and the amplitude is

[0150] (15) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are respectively connected to different common full - voltage input branches. Among all 72 states, when the special bridge arm is connected to a single full - voltage input branch in the N - phase, since the voltage vector angles are all time - varying, a total of 18 states are not used in modulation. Each of the remaining 54 states has only 16 switching states, and the amplitude is

[0151] (16) Two output bridge arms are connected to a common full - voltage input branch, and the remaining two output bridge arms, one is connected to a different full - voltage input branch and the other is connected to a half - voltage input branch. Among all 432 states, each state has only 2 switching states. When the special bridge arm is connected to a single full - voltage input branch in the N - phase, there are 54 states, and the amplitude is 3Vin / 2. When the special bridge arm is connected to a half - voltage input branch in the N - phase, there are 54 states, and the amplitude is For the remaining 324 states, the amplitude is

[0152]

[0153] (17) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms, one is connected to a full - voltage input branch and the other is connected to a different half - voltage input branch. Among all 432 states, each state has only 8 switching states. When the special bridge arm is connected to a full - voltage input branch in the N - phase, there are 54 states, and the amplitude is When the special bridge arm is connected to a single half - voltage input branch in the N - phase, there are 54 states, and the amplitude is For the remaining 324 states, the amplitude is

[0154] (18) Two output bridge arms are connected to a common full - voltage input branch, and the remaining two output bridge arms are connected to different half - voltage input branches. Among all 432 states, each state has only 4 switching states. When the special bridge arm is connected to a half - voltage input branch in the N - phase, there are 108 states, and the amplitude is For the remaining 324 states, the amplitude is

[0155] (19) Two output bridge arms are connected to a common half - voltage input branch, and the remaining two output bridge arms are connected to different full - voltage input branches. Among all 432 states, each state has only 4 switching states. When the special bridge arm is connected to the full - voltage input branch in the N - phase, there are a total of 108 states, and the amplitude is For the remaining 324 states, the amplitude is

[0156] Then, taking half of the input line voltage as the unit, all vectors are normalized, and finally all switching vectors can be classified into ten categories according to the amplitude.

[0157] Table 2 Switching Vectors of Three - Phase Four - Leg Three - Level Direct Matrix Converter

[0158]

[0159] As Figure 2 shown, the SVPWM modulation method provided by the embodiment of the present invention includes:

[0160] S101, three - phase four - leg three - level output cube positioning;

[0161] S102, three - phase four - leg three - level duty cycle calculation.

[0162] For the three - phase four - leg three - level output cube positioning provided by the embodiment of the present invention, assume that the three - phase input voltage is:

[0163]

[0164] where u a , u b , u c are the transient values of the input voltages of phases a, b, and c respectively, and U i and ω i are the effective value and angular frequency of the input phase voltage respectively.

[0165] Assume that the ideal output voltage is:

[0166]

[0167] where u A , u B , u C are the transient values of the output voltages of phases A, B, and C respectively, and U o and ω o are the effective value and angular frequency of the output phase voltage respectively.

[0168] Since the output voltage adopts the abc coordinate system, there is no need to perform the Clarke transformation. It is only necessary to transform the output current into the two-phase stationary coordinate system through formula (3) to obtain the space vector corresponding to the input current at that moment, which is the same as the current space vector diagram formed by the flying capacitor multilevel matrix converter.

[0169]

[0170] Because the output voltage space vector diagram is directly in the abc coordinate system and is drawn through the corresponding phase voltages as Figure 3 shown in the output voltage space vector diagram.

[0171] There are a total of u a 、u b 、u c and (u a +u b ) / 2、(u b +u c ) / 2、(u c +u a ) / 2 six output voltages. Since the drawing of the abc coordinate system requires phase voltages, the values are the differences between the voltages of the ABC three phases and the N phase voltage. That is, the finally output phase voltages are ±u ab 、±u bc 、±u ca and ±u ab / 2、±U bc / 2、±u ca / 2 twelve output line voltages.

[0172] Since the output A, B, and C three phases will not be all positive or all negative at the same time, finally, according to the positive and negative of the three output phase voltages of u A 、u B 、u C the space vector diagram is divided into 6 pentahedrons as Figure 4 shown.

[0173] Table 3 Pentahedron division regulations

[0174]

[0175] After dividing the output voltage as shown above, further division of the pentahedrons is still needed. First, translate all the pentahedrons so that all the coordinates in the pentahedron are positive, that is, subtract the equivalent origin corresponding to each pentahedron from each switching vector, as shown in Table 4.

[0176] Table 4 Pentahedron equivalent origin

[0177]

[0178] Then, the translated pentahedron is divided according to the relationship between the magnitudes of the three-phase voltages of A, B, and C and the half voltage, as Figure 5 shown. The specific division method is shown in Table 5.

[0179] Table 5 Cube Division

[0180]

[0181] Then, the cube is translated according to the equivalent origin in Table 6. Finally, all the cubes are translated to the same position to facilitate the subsequent division of small cubes and the calculation of the duty cycle, that is, only one calculation needs to be performed for this final position.

[0182] Table 6 Cube Corresponding Equivalent Origin

[0183]

[0184] The translated cube is divided into tetrahedrons according to Table 7, and divided into six tetrahedrons as Figure 6 shown.

[0185] Table 7 Tetrahedron Division

[0186]

[0187] The vector falling into a certain tetrahedron is synthesized by the four vertices of the tetrahedron, where the equivalent origin is the same as the equivalent origin selected for the cube in Table 3.3. The final equivalent coordinate is the difference between the coordinate value of the vector to be solved and the equivalent origin of the cube where the vector falls.

[0188] Through Figure 5 it can be seen that the output voltage cube is not all composed of complete cubes, but each cube can be regarded as composed of tetrahedrons. As shown in Table 8, 1, 2, 3, 4, 5, and 6 in the table respectively represent Figure 6 the six tetrahedrons in.

[0189] Table 8 Tetrahedron Composition

[0190]

[0191] Therefore, each cube can be regarded as composed of multiple tetrahedrons and calculated according to the cube. However, all cubes can be analyzed through equivalence, so only one cube will be analyzed next.

[0192] For the three-phase four-leg three-level duty cycle calculation provided by the embodiment of the present invention, if the coordinates corresponding to the vector to be synthesized are when, by the positive and negative of the voltages output from the three phases of A, B, and C, it can be seen that the u in this coordinate A<0, u B >0, u C <0. It can be judged from Table 3.1 that this vector falls within the pentahedron 5. After translation, that is, subtracting the equivalent origin of the cube into which it falls from the coordinates of the synthesized vector, a new all-positive coordinate can be obtained: For this new coordinate, it can be seen that the magnitudes of the three phases A, B, and C at this point are all less than 1. After referring to Table 6, it can be judged that this point is located in the fifth cube. Since the equivalent origin of this pentahedron is the same as that of the cube, no further translation is required. Analyzing the new coordinate again, it can be seen that u in the new coordinate A >u C >u B , and it can be judged from Table 7 that this vector falls within the tetrahedron 1 in the corresponding regular cube.

[0193] Finally, select 8 vectors in the manner as Figure 7 shown. When selecting the switching vectors, first, the switching vectors are selected in the output voltage sector. At this time, not only the magnitude of each phase should be noted, but also the positive and negative of the input line voltage corresponding to the final output phase voltage amplitude should be judged. If it is negative at this time, the opposite voltage vector needs to be selected. Thus, at least 3 switching vectors can be selected at each vertex. Since the matrix converter needs to control not only the output voltage but also the input current, after the switching vectors are selected in the output voltage sector, the input current vectors also need to be selected from the selected switching vectors, that is, two vectors need to be selected from the switching vectors selected at each vertex to meet the input current control. These two vectors are located on both sides of the sector into which the synthesized input current vector falls.

[0194] Since in the abc coordinate system, no conversion is required and it can be directly calculated through the coordinate values of the vectors. Such as Figure 7It can be seen that the coordinates corresponding to V1 and V2 after equivalence are (1, 0, 0); the coordinates corresponding to V3 and V4 are (1, 0, 1); the coordinates corresponding to V5 and V6 are (1, 1, 1); the coordinates corresponding to V7 and V8 are (0, 0, 0), and the calculations are carried out according to these coordinates. However, the actual coordinates corresponding to V1 and V2 are (-1, 0, -2); the coordinates corresponding to V3 and V4 are (-1, 0, -1); the coordinates corresponding to V5 and V6 are (1-, 1, -1); the coordinates corresponding to V7 and V8 are (-2, 0, -2). Since the switching vectors have been selected at this time, only the duty cycle needs to be calculated, and the duty cycles obtained using the original coordinates and the translated coordinates will not be different. Only using the translated coordinates will greatly simplify the complexity of the calculation, that is, there is no need to repeat the calculation for the duty cycle of each sector. To simplify the calculation process, the translated coordinates are used in this article, and during the calculation process, only the numerical values in the coordinates, that is, n times the input line voltage, are used. Assuming the coordinates of the synthesized vector are (U A , U B , U C ), the following equations can be obtained in this invention:

[0195]

[0196] It can be seen that when using the abc coordinate system for duty cycle calculation, there is no need for a complex arctangent function, and only simple addition and subtraction of the magnitudes of each phase voltage are required. Simplifying the above formula gives:

[0197]

[0198] Since the calculation of the input current will not increase with the increase in the number of levels, the αβ coordinate system is still used for the input current, that is, the calculation result is the same as that of the flying capacitor multilevel matrix converter, and the current satisfies formula (6).

[0199]

[0200] Combining formula (5) and (6) can obtain the final duty cycle as in (7):

[0201]

[0202] II. Application examples. To prove the creativity and technical value of the technical solution of this invention, this part is an application example of the technical solution of the claims on specific products or related technologies.

[0203] Apply the SVPWM modulation method provided by the application embodiment of the present invention to a computer device, which includes a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the steps of the SVPWM modulation method.

[0204] Apply the SVPWM modulation method provided by the application embodiment of the present invention to an information data processing terminal, which is used to implement the SVPWM modulation method.

[0205] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. Those of ordinary skill in the art can understand that the above devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuits of programmable hardware devices such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips and transistors, or field programmable gate arrays and programmable logic devices, can also be implemented by software executed by various types of processors, or can be implemented by a combination of the above hardware circuits and software, such as firmware.

[0206] III. Evidence of related effects of the embodiments. Some positive effects have been achieved during the research and development or use of the embodiments of the present invention, and there are indeed great advantages compared with the prior art. The following content is described in combination with data, charts, etc. in the test process.

[0207] Through Matlab / Simulink, the output waveforms of the flying capacitor multilevel matrix converter and the four-leg matrix converter are mainly compared with the output waveform of the three-phase four-wire three-level direct matrix converter proposed in this paper. Among them, the input phase voltage is set to a 50Hz three-phase AC power supply of 87.5V, the output line voltage is set to a 100Hz three-phase AC of 75V, and the single-phase load is set to an inductive load with a 124Ω resistor and a 4mH inductor in series. Simulations are carried out for the three topologies respectively.

[0208] As Figure 8 、 9, 10 are the output line voltage waveforms of three matrix converters and the FFT analysis results respectively. It is not difficult to see that the harmonics contained in the output of the three-phase four-leg three-level direct matrix converter proposed in this paper are close to those of the flying-capacitor multilevel matrix converter and far lower than those of the four-leg matrix converter, achieving the effect of optimizing the output waveform.

[0209] At the same time, through Figure 11 , it can also be seen that the three-phase four-leg three-level direct matrix converter can achieve a unity input power factor, that is, the requirement that the input voltage and current are in the same phase.

[0210] As mentioned above, the above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement and improvement made within the spirit and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A SVPWM modulation method for a three-phase four-bridge-arm three-level direct matrix converter, characterized in that: The three-phase four-bridge three-level direct matrix converter topology consists of 24 bidirectional switches and 8 flying capacitors. The four bridge arms A, B, C, and N each contain 9 output switch states and 6 output voltages. There are 9 switch states in total. 4 = 6561, the output phase line voltage includes six output voltages, three full voltages and three half voltages, and the switch states have 9 2 =81 kinds; The SVPWM modulation method of a three-phase four-bridge-arm three-level direct matrix converter includes: Step 1: Positioning of the three-phase four-bridge-arm three-level output cube; Step 2: Calculate the duty cycle of the three-phase four-bridge three-level; The three-phase four-bridge-arm three-level output cube positioning includes: (1) Assume that the three-phase input voltage is: where u a 、u b 、u c are the transient values ​​of the three-phase input voltages a, b, and c, respectively, U i and ω i are the input phase voltage effective value and angular frequency respectively; Assuming the ideal output voltage is: where u A 、u B 、u C are the transient values ​​of the three-phase output voltages A, B, and C, respectively, and U o and ω o are the output phase voltage effective value and angular frequency respectively; (2) The output current is transformed into a two-phase stationary coordinate system by formula (3), and the space vector corresponding to the input current at that moment is obtained, which is the same as the current space vector diagram formed by the flying capacitor multi-level matrix converter: (3) Draw the output voltage space vector diagram, and the final output phase voltage is ±u ab 、±u bc 、±u ca and ±u ab / 2, ±U bc / 2, ±u ca / 2Twelve output line voltages; (4) Through u A 、u B 、u C The positive and negative of the three output phase voltages divide the space vector diagram into 6 pentahedrons; (5) Further divide the pentahedron. First, translate all the pentahedrons so that all coordinates in the pentahedron are positive. That is, subtract the equivalent origin corresponding to each pentahedron from each switch vector. Then, divide the translated pentahedron according to the relationship between the phase voltage of the three phases A, B, and C and the half voltage. Then, translate the equivalent origin of the cube. Finally, translate all the cubes to the same position. (6) The cube after translation is divided into six tetrahedrons, and the vector falling on a tetrahedron is synthesized by the four vertices of the tetrahedron.

2. The SVPWM modulation method of a three-phase four-bridge-arm three-level direct matrix converter according to claim 1, characterized in that: The three-phase four-bridge three-level duty cycle calculation is performed using the translated coordinates, and in the calculation process, only the values ​​in the coordinates, i.e., n times the input line voltage, are used; assuming that the vector coordinates of the synthesis are (U A ,U B ,U C ) we can get the following equation: The use of the abc coordinate system to calculate the duty cycle no longer requires a complex inverse tangent function. It only requires a simple addition and subtraction of the magnitude of each phase voltage. Simplifying the above formula yields: Since the calculation of input current does not increase with the increase of the number of levels, the input current still uses the αβ coordinate system, that is, the calculation result is the same as that of the flying capacitor multi-level matrix converter, that is, the current satisfies formula (6); Combining formulas (5) and (6), the final duty cycle can be obtained as shown in (7):

3. The SVPWM modulation method of a three-phase four-bridge-arm three-level direct matrix converter according to claim 1, characterized in that: All vectors of three-phase four-bridge three-level direct matrix converter are classified according to the following 19 types: (1) Each output bridge arm is connected to a different full-voltage input branch; each output state has only one switching mode, and their voltage vector angles vary with time in vector space and cannot be used for modulation; (2) Each output bridge arm is connected to a different half-voltage input branch; each output state has 16 corresponding switching modes, but their voltage vector angles vary with time and cannot be used for modulation; (3) Each output bridge arm is connected to a common full-voltage input branch; These are the zero states used in matrix converters, where each output state has only one switching pattern, and are referred to as "original" zero states to distinguish them from the extra zero states; (4) Each output bridge arm is connected to a common half-voltage input branch; This type is the extra zero state generated by the matrix converter; each output state has 16 switching modes. Considering that the zero state only occupies redundant time in the modulation algorithm, if the extra zero state is used, more complex flying capacitor voltage control needs to be considered, so only the original zero vector is used in the modulation process; (5) Three output bridge arms are connected to a common full-voltage input branch, and the remaining output bridge arms are connected to other full-voltage input branches. In these 24 states, each state has only one switching mode, which can be divided into two categories: when the output bridge arm is N-phase, the output amplitude is There are 6 states in total; the remaining 18 have amplitudes of Vin; (6) Three output bridge arms are connected to a common half-voltage input branch, and the remaining output bridge arms are connected to other half-voltage input branches, which produces another 24 states, each state has 16 switching modes, with two different input current vector angle directions, which can be divided into two categories: when the output bridge arm is N-phase, the output amplitude is There are 6 states in total, and the vector amplitude of the remaining 18 states is Vin / 2; (7) Three output bridge arms are connected to a common full-voltage input branch, and the remaining output bridge arms are connected to a half-voltage input branch. Each of the 36 states has two switching modes, which can be divided into two categories: when the output bridge arm is N-phase, the output amplitude is There are 9 states in total; the vector amplitude of the remaining 27 states is Vin / 2; (8) Three output bridge arms are connected to a common half-voltage input branch, and the remaining output bridge arms are connected to the full-voltage input branch. Among all the 36 states, each state has 8 switching modes, which can be divided into two categories: when the output bridge arm is N-phase, the output amplitude is There are 9 states in total, and the vector amplitude of the remaining 27 states is Vin / 2; (9) Two output bridge arms are connected to a common full voltage input branch, and the remaining two output bridge arms are connected to the same other common full voltage input branch. Among all 18 states, each state has only one switching mode with an amplitude of (10) Two output bridge arms are connected to a common full voltage input branch, and the remaining two output bridge arms are connected to the same common half voltage input branch. Among all 54 states, each state has only 4 switching modes, of which 18 states are not used in modulation because the voltage vector angle is time-varying, and the remaining 36 states have amplitudes of (11) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to other identical common half-voltage input branches. In all 18 states, each state has 16 switching modes with an amplitude of (12) Two output bridge arms are connected to a common full voltage input branch, and the remaining two output bridge arms are connected to other identical common full voltage input branches. Among all 72 states, when the output bridge arm is connected to a separate full voltage input branch for N phases, since the voltage vector angle is time-varying, a total of 18 states are not used in modulation; the remaining 54 states each have only one switching state, and the amplitude is (13) Two output bridge arms are connected to a common full voltage input branch, and the remaining two output bridge arms are connected to different common half voltage input branches. Among all 216 states, when the output bridge arm is connected to a separate half voltage input branch for N phases, since the voltage vector angle is time-varying, a total of 27 states are not used in modulation. The remaining 189 states each have only 4 switching states, with an amplitude of (14) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to other different common full-voltage input branches. Among all 216 states, when the output bridge arm is connected to a separate full-voltage input branch for N phases, since the voltage vector angle is time-varying, a total of 27 states are not used in modulation. The remaining 189 states each have only 4 switching states, with an amplitude of (15) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to different common full-voltage input branches. Among all 72 states, when the output bridge arm is connected to a separate full-voltage input branch for N phases, since the voltage vector angle is time-varying, a total of 18 states are not used in modulation. The remaining 54 states each have only 16 switching states, with an amplitude of (16) Two output bridge arms are connected to a common full-voltage input branch, and one of the remaining two output bridge arms is connected to a different full-voltage input branch and the other is connected to a half-voltage input branch; among all 432 states, each state has only 2 switching states. When the output bridge arm is connected to a separate full-voltage input branch for N phases, there are 54 states with an amplitude of 3Vin / 2. When the output bridge arm is connected to a half-voltage input branch for N phases, there are 54 states with an amplitude of The remaining 324 states have amplitudes of (17) Two output bridge arms are connected to a common half-voltage input branch, and one of the remaining two output bridge arms is connected to a full-voltage input branch and the other is connected to a different half-voltage input branch; among all 432 states, each state has only 8 switching states. When the output bridge arm is connected to the full-voltage input branch for N phases, there are 54 states in total, with an amplitude of When the output bridge arm is N-phase connected to a separate half-voltage input branch, there are 54 states with an amplitude of The remaining 324 states have amplitudes of (18) Two output bridge arms are connected to a common full-voltage input branch, and the remaining two output bridge arms are connected to different half-voltage input branches. Among all 432 states, each state has only 4 switching states. When the output bridge arm is connected to the half-voltage input branch for N phases, there are a total of 108 states with an amplitude of The remaining 324 states have amplitudes of (19) Two output bridge arms are connected to a common half-voltage input branch, and the remaining two output bridge arms are connected to different full-voltage input branches. Among all 432 states, each state has only 4 switching states. When the output bridge arm is connected to the full-voltage input branch for N phases, there are a total of 108 states with an amplitude of / 2, the remaining 324 states have amplitudes of 4. A control method for the three-phase four-bridge-arm three-level direct matrix converter according to claim 1, the method comprising the following steps: (1) Based on the topology of a three-phase four-bridge three-level direct matrix converter, the voltage and current output of the converter are realized by controlling 24 bidirectional switches and 8 flying capacitors; (2) According to the output requirements of the converter, select the appropriate vector type, including full voltage input branch connection, half voltage input branch connection, and common input branch connection; (3) Determine the switch state and switching mode of each output bridge arm according to the selected vector type to achieve the required output voltage and current; (4) During the modulation process, the zero state is used to avoid the complexity of flying capacitor voltage control caused by using additional zero states; (5) Dynamically adjust the switch state and switching mode according to the output demand and the working status of the converter to achieve efficient and stable power conversion.

5. A modulation method for the three-phase four-bridge-arm three-level direct matrix converter according to claim 1, the method comprising the following steps: (1) According to the vector classification of the three-phase four-bridge-arm three-level direct matrix converter, select the vector type that suits the modulation requirements; (2) constructing a corresponding modulation algorithm based on the selected vector type, including the selection of switch states, determination of switching modes, and allocation of modulation time; (3) Generate a control signal based on the modulation algorithm, and adjust the output voltage and current by controlling the on and off of the bidirectional switch; (4) During the modulation process, the output voltage, current and flying capacitor voltage parameters of the converter are monitored in real time, and the modulation algorithm is dynamically adjusted according to the monitoring results to optimize the power conversion effect; (5) By cyclically executing the above steps, continuous and stable modulation of the three-phase four-bridge-arm three-level direct matrix converter is achieved.

6. A fault diagnosis and processing method for the three-phase four-bridge-arm three-level direct matrix converter according to claim 1, the method comprising the following steps: (1) Collect switch status, voltage, and current parameters by monitoring the operating status of a three-phase, four-bridge-arm, three-level direct matrix converter; (2) Process and analyze the collected data to identify potential failure modes, including switch failure and flying capacitor failure; (3) Take appropriate treatment measures based on the identified fault mode, including replacing the failed switch and adjusting the voltage of the flying capacitor; (4) During the fault handling process, monitor the operating status of the converter in real time to ensure the effectiveness of the handling measures; (5) Record and analyze the fault handling process, summarize experience and lessons, and optimize fault diagnosis and handling methods.

7. An optimization control method for the three-phase four-bridge-arm three-level direct matrix converter according to claim 1, the method comprising the following steps: (1) According to the topological structure and operating characteristics of the three-phase four-bridge-arm three-level direct matrix converter, a corresponding mathematical model is established; (2) Based on the mathematical model, analyze the changing patterns of the voltage, current and power parameters of the converter; (3) Based on the analysis results, formulate an optimized control strategy, including reducing switching losses, improving conversion efficiency, and optimizing output voltage quality; (4) According to the optimization control strategy, adjust the switching state and switching mode of the converter to achieve optimal control of parameters; (5) Through real-time monitoring and feedback mechanism, the optimization control effect is evaluated and adjusted to achieve the best performance of the three-phase four-bridge-leg three-level direct matrix converter.

8. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the SVPWM modulation method of the three-phase four-bridge-arm three-level direct matrix converter as described in any one of claims 1-3.

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