Modulation method for full-range minimum direct current side capacitance current effective value of three-phase inverter

Abstract

The invention discloses a modulation method for a full-range minimum direct current side capacitance current effective value of a three-phase inverter. The modulation method comprises the following steps: S1, determining a three-vector combination corresponding to a predetermined modulation method; grouping according to an intersection of a synthesizable area of the three-vector combination on a space vector alpha beta plane and the first sector; s2, based on the effective value of the minimum direct current side instantaneous inverter current in each group, determining a predetermined modulation method of the effective value of the minimum direct current side capacitance current in each group; and S3, globally comparing the determined predetermined modulation method, and obtaining the modulation method of the full-range minimum direct current side capacitance current effective value of the three-phase inverter based on the minimum direct current side instantaneous inverter current effective values under different phase angles, modulation degrees and power factor angles. According to the modulation method provided by the invention, on the basis of traversing all possible three-vector combination modulation methods, the current effective value of the minimum direct-current capacitor under a full-range power factor angle and a modulation degree can be realized.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a modulation method for a full-range minimum DC side capacitor current effective value of a three-phase inverter. Background Art

[0002] Three-phase bridge inverters are widely used in motor drives, electric vehicles, and renewable energy conversion. At present, the use of new wide bandgap switching devices can achieve faster switching speeds. After increasing the switching frequency, the volume of passive components such as output filters is significantly reduced, but the DC bus capacitor used to absorb DC current pulsation and suppress DC voltage ripple remains the same, occupying more than one-third of the volume of the three-phase bridge inverter.

[0003] Reducing the effective value of capacitor current is the key to reducing the size of DC bus capacitors. The effective value of capacitor current of a three-phase bridge inverter is determined by the AC current amplitude, modulation degree, power factor angle, and is also closely related to the modulation method. However, the existing three-phase inverter modulation method can only achieve the minimum effective value of DC capacitor current under a specific modulation degree and power factor angle, which needs to be improved urgently. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a modulation method for the full-range minimum DC side capacitor current effective value of a three-phase inverter.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] A method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter, comprising:

[0007] S1: Determine a three-vector combination corresponding to a predetermined modulation method; group the three-vector combination according to the intersection of a synthesizable area on the space vector αβ plane and the first sector;

[0008] S2: Based on the minimum instantaneous inverter current effective value i on the DC side in each group inv,rms , determine a predetermined modulation method for the effective value of each group of minimum DC side capacitor current;

[0009] S3: Perform a global comparison of the determined predetermined modulation methods based on different phase angles θ, modulation degrees m and power factor angles The inverter current effective value i inv,rms , and obtain the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter.

[0010] Furthermore, the inverter current effective value i inv,rms The calculation formula is:

[0011]

[0012] Among them, i 2 inv,rms is the square of the effective value of the inverter current, T s is a switching cycle, i inv,i is the instantaneous input current of the inverter corresponding to the i-th space vector in a switching cycle, t i is the action time of the i-th space vector.

[0013] Furthermore, the number of the predetermined modulation methods and the number of the three-vector combinations are both 13, and the three-vector combinations correspond one-to-one to the predetermined modulation methods.

[0014] Furthermore, the number of groups in step S1 is 5; and the predetermined modulation methods determined in step S2 are: SVPWM, TSPWM1L, TSPWM2L, TSPWM1H, TSPWM2H.

[0015] Furthermore, the modulation method obtained in step S3 is:

[0016]

[0017] Among them, MC 2 PWM is the modulation method of the full range minimum DC side capacitor current effective value of the three-phase inverter, sgn represents the sign function, Δ1 is Δ2 is k is an integer.

[0018] The present invention also provides a modulation method for the full-range minimum DC side capacitor current effective value of a three-phase inverter, and the implementation steps of the modulation method include:

[0019] S10: performing per-unit and coordinate transformation on a given reference voltage vector in the dqz synchronous rotating coordinate system to obtain a reference voltage vector in the abc three-phase stationary coordinate system;

[0020] S20: Calculate the power factor angle according to the sampled three-phase AC voltage and three-phase AC current;

[0021] S30: Determine a modulation method for a full-range minimum effective value of a DC side capacitor current of a three-phase inverter based on a power factor angle, a phase angle and a modulation degree;

[0022] S40: dividing the modulation method into sectors and determining a zero vector and a carrier; determining an injected zero-sequence component based on the zero vector, and calculating a three-phase duty cycle using the zero-sequence component and a reference voltage vector in the abc three-phase stationary coordinate system;

[0023] S50: Generate a three-phase symmetrical pulse width sequence using the three-phase duty cycle and the carrier at a predetermined switching frequency.

[0024] Further, step S10 includes:

[0025] S100: The reference voltage vector given in the dqz synchronous rotating coordinate system is converted into half of the DC voltage u obtained by sampling. dc / 2 is calibrated to obtain the reference voltage vector after calibration;

[0026] S110: Use the phase angle to perform an inverse DQZ transformation on the reference voltage vector after standardization to obtain the reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c ′, specifically:

[0027]

[0028] in, is the reference voltage vector after standardization, and θ is the phase angle.

[0029] The power factor angle of step S20 The calculation formula is:

[0030]

[0031] Among them, u as 、u bs 、u cs is the three-phase AC voltage, i a 、i b 、i c It is a three-phase alternating current.

[0032] The zero sequence component d z 'for:

[0033]

[0034] The reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c ′ is injected with zero sequence component d z 'Get the modulated wave, the modulated wave is shifted upward by 1 and the amplitude is halved to obtain the three-phase duty cycle.

[0035] Furthermore, the step of determining the carrier includes: using a carrier wave per phase required for symmetrical pulse width modulation.

[0036] The present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the method for modulating the full-range minimum DC side capacitor current effective value of the three-phase inverter are implemented.

[0037] The present invention also provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter are implemented.

[0038] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0039] 1. Improve capacitor utilization: The present invention significantly reduces the effective value of the capacitor current in the inverter by achieving the minimum effective value of the DC side capacitor current under the full range of power factor angles and modulation degrees, thereby effectively reducing the volume of the DC bus capacitor and optimizing space utilization.

[0040] 2. Reduce the size and cost of the inverter: Since the effective value of the capacitor current is reduced, the DC bus capacitance of the inverter can be reduced, thereby reducing the size and manufacturing cost of the entire device, making it more suitable for miniaturized power electronic devices that require high power density.

[0041] 3. Improve modulation flexibility: The present invention can achieve the minimum capacitor current under different power factor angles and modulation degrees, which means that it has higher flexibility in adapting to different operating conditions. Compared with traditional methods, it is not limited to specific modulation degrees and power factor angles and has a wider range of applications.

[0042] 4. Efficiently achieve optimal modulation: By adopting space vector pulse width modulation (SVPWM) and various TSPWM methods, combined with the injection of zero-sequence components, the implementation process is simplified, making the selection of the optimal modulation method more convenient and efficient.

[0043] 5. Improve inverter performance and reliability: After achieving a smaller effective value of capacitor current, the heat loss inside the capacitor is reduced, thereby improving the operating efficiency and reliability of the inverter and extending the overall life of the system.

[0044] The above beneficial effects summarize the innovative features of the present invention and its advantages in practical use, and can highlight its value in technical improvement and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is the topology structure of the three-phase three-wire two-level inverter according to an embodiment of the present application.

[0046] Figure 2 Flow chart of the modulation method according to an embodiment of the present application.

[0047] Figure 3 This is a three-vector combination modulation method in the Ith sector of the space vector αβ plane according to an embodiment of the present application.

[0048] Figure 4 This is the regional division of the minimum DC side capacitor current effective value modulation method of the embodiment of the present application.

[0049] Figure 5 for Figure 4 Grayscale image of .

[0050] Figure 6 This is a block diagram of an implementation method of a minimum DC link capacitor current effective value modulation method according to an embodiment of the present application.

[0051] Figure 7 This is the zero vector sector division of the minimum DC link capacitor current effective value modulation method of the embodiment of the present application.

[0052] Figure 8 This is a flow chart of zero vector selection and carrier selection for the minimum DC link capacitor current effective value modulation method according to an embodiment of the present application.

[0053] Fig. 9 1 is a comparison diagram of the effective values ​​of per-unit capacitance current according to the embodiment of the present application.

[0054] Fig.10 for Fig. 9 Grayscale image of . DETAILED DESCRIPTION

[0055] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0056] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0057] This embodiment provides a modulation method for the full range minimum DC side capacitor current effective value of a three-phase inverter. The topology structure of the three-phase three-wire two-level inverter (referred to as the three-phase inverter) is as follows: Figure 1 shown.

[0058] exist Figure 1 In, L x is the AC filter inductor, Z x is the AC load impedance, C dc is the DC bus capacitance, u dcis a DC power supply, S1~S6 are 6 field effect switch tubes, and the upper and lower switch tubes of the same bridge arm are complementary and turned on; the 8 switching states of the three bridge arm switch tubes correspond to 8 basic space vectors. When the upper switch tube of the bridge arm is turned on and the lower switch tube is turned off, the DC side current is the phase current of the bridge arm; when the upper switch tube of the bridge arm is turned off and the lower switch tube is turned on, the DC side current is zero. When the switching frequency f s and filter inductor L x When the phase current i is large enough, x The ripple can be ignored. In one switching cycle T s The internal approximation assumes that the phase current i x Keeping its average value unchanged, a switching cycle T s The square of the instantaneous inverter current effective value i on the inner DC side 2 inv,rms It is expressed as:

[0059]

[0060] Among them, i inv,i is a switching cycle T s The instantaneous input current of the inverter corresponding to the i-th space vector, t i is the action time of the i-th space vector.

[0061] From the above results, we can see that the effective value of the inverter current i inv,rms is the modulation index m, power factor angle Phase angle θ, AC current amplitude I m function of the switching frequency f s Not relevant.

[0062] The inverter current i in one switching cycle inv The DC component (i.e. the average current i dc ) has nothing to do with the modulation method and is also the average current I within a power frequency cycle dc , specifically:

[0063]

[0064] When the DC side capacitor is large enough to completely absorb the inverter current i inv The AC component (i.e., the capacitive current i cap ), the inverter current i inv The DC component is completely composed of the DC power supply current i dc Provide. The square of the effective value of the capacitor current considering only the average value of the phase current in one switching cycle is i 2 cap,rms It is expressed as:

[0065]

[0066] If a modulation method can be found so that only the capacitor current effective value i of the average phase current is considered in each switching cycle, cap,rms Can be used in various modulation degrees m, power factor angle If the phase angle θ reaches the minimum, then the effective value of the capacitor current in the entire power frequency cycle must also be the minimum. dc It has nothing to do with the modulation method. Under the same modulation index m and power factor angle The following is the only certainty, then, the effective value of the capacitor current i cap,rms Taking the minimum value also means that the effective value of the inverter current i inv,rms Take the minimum value, that is, the effective value of the inverter current i inv,rms When the capacitor current is at its minimum, the effective value i cap,rms Also the smallest.

[0067] like Figure 2 As shown, this embodiment provides a method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter, including:

[0068] Step S1: determine a three-vector combination corresponding to a predetermined modulation method; and group the three-vector combination according to the intersection of a synthesizable area on the space vector αβ plane and the Ith sector.

[0069] Figure 3 All 13 three-vector combination modulation methods in sector I of the space vector αβ plane are shown, that is, the number of predetermined modulation methods and three-vector combinations are both 13, and the three-vector combinations correspond one-to-one to the predetermined modulation methods.

[0070] Preferably, the predetermined modulation method is: SVPWM (Space Vector Pulse Width Modulation), AZSPWM2 (Active Zero State Pulse Width Modulation 2), AZSPWM3, AZSPWM2A, AZSPWM3A, AZSPWM2B, AZSPWM3B, RSPWM2B (Remote State Pulse Width Modulation 2B), RSPWM2A, TSPWM1L (Tri-State Pulse Width Modulation 1Low), TSPWM2L, TSPWM1H (Tri-State Pulse Width Modulation 1High), and TSPWM2H.

[0071] Step S2: Based on the minimum instantaneous inverter current effective value i on the DC side in each group inv,rms , determine the predetermined modulation method for the effective value of each group of minimum DC link capacitor current.

[0072] Preferably, the inverter current effective value i inv,rms The calculation formula is:

[0073]

[0074] Among them, i 2 inv,rms is the square of the effective value of the inverter current, T s is a switching cycle, i inv,i is the instantaneous input current of the inverter corresponding to the i-th space vector in a switching cycle, t i is the action time of the i-th space vector.

[0075] exist Figure 3 In the figure, the bold arrow line represents the basic vector used by the predetermined modulation method; the zero vector is also regarded as a vector because its modulus is zero and there is no Figure 3 The dashed area indicates the synthesizable area of ​​the three vectors on the entire space vector αβ plane, and the dark shadow indicates the synthesizable area of ​​the three vectors in sector I (i.e., the intersection of the synthesizable area of ​​the three vectors on the space vector αβ plane and sector I). The synthesizable area of ​​the three vectors in sector I is divided into 5 groups.

[0076] The first group: The range of the synthesizable area of ​​the three vectors in sector I is the entire sector I, that is, the dark shadow covers sector I.

[0077] The predetermined modulation methods in the first group are: SVPWM, AZSPWM2, AZSPWM3.

[0078] Compared with SVPWM, AZSPWM2 and AZSPWM3 have a square of the effective value of the inverter current. Increase Due to the vector action time t 5azs2 ,t 4azs3 , and the switching period T s Both are positive numbers, so both differences are positive numbers, so SVPWM is the effective value of the inverter current in the first group i inv,rms Minimal modulation method.

[0079] The second group: The range of the synthesizable area of ​​the three vectors in sector I is the left half of sector I, that is, the dark shadow covers the left half of sector I.

[0080] The predetermined modulation methods in the second group are: TSPWM1L, AZSPWM2A, AZSPWM3A, RSPWM2B.

[0081] Compared with TSPWM1L, AZSPWM2A, AZSPWM3A, RSPWM2B have a square of the effective value of the inverter current. Increase Similarly, since the vector action time and the switching period are both positive, the three differences are all positive, so TSPWM1L is the effective value of the inverter current i in the second group. inv,rms Minimal modulation method.

[0082] The third group: The range of the synthesizable area of ​​the three vectors in sector I is the entire lower left part of sector I, that is, the dark shadow covers the lower left part of sector I.

[0083] The predetermined modulation methods in the third group are: TSPWM2L, AZSPWM2B, AZSPWM3B, RSPWM2A.

[0084] Compared with TSPWM2L, AZSPWM2B, AZSPWM3B, RSPWM2A, the square of the effective value of the inverter current Increase Similarly, since the vector action time and the switching period are both positive, the three differences are all positive, so TSPWM2L is the effective value of the inverter current in the third group i inv,rms Minimal modulation method.

[0085] The fourth group: The range of the synthesizable area of ​​the three vectors in sector I is the right half of the entire sector I, that is, the dark shadow covers the right half of sector I.

[0086] The predetermined modulation method in the fourth group is: TSPWM1H.

[0087] The fifth group: The range of the synthesizable area of ​​the three vectors in sector I is the upper right part of the entire sector I, that is, the dark shadow covers the upper right part of sector I.

[0088] The predetermined modulation method in the fifth group is: TSPWM2H.

[0089] There is a predetermined modulation method in both the fourth and fifth groups, so TSPWM1H is the effective value of the inverter current i in the fourth group. inv,rms The smallest modulation method, TSPWM2H, is the effective value of the inverter current in the fifth group i inv,rms Minimal modulation method.

[0090] Since the inverter current effective value i inv,rms When the capacitor current is at its minimum, the effective value icap,rms It is also the smallest, so the predetermined modulation methods for the minimum effective value of the DC link capacitor current determined after the comparison within the group in step S2 are: SVPWM, TSPWM1L, TSPWM2L, TSPWM1H, and TSPWM2H.

[0091] Step S3: Perform a global comparison on the determined predetermined modulation methods, based on different phase angles θ, modulation degrees m and power factor angles The minimum instantaneous inverter current effective value i on the DC side under inv,rms , and obtain the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter.

[0092] Here, TSPWM1L, TSPWM2L, TSPWM1H, TSPWM2H and SVPWM are globally compared to obtain the effective value of the inverter current i inv,rms Minimal modulation method.

[0093] TSPWM1L Vector The action time is t 1sv ,t 1sv +t 2sv ,t 0sv –t 1sv ;TSPWM2L vector The action time is t 1sv +t 2sv ,t 2sv ,t 0sv –t 2sv ;TSPWM1H vector The action time is t 1sv –t 0sv ,t 2sv +t 0sv ,t 0sv ;TSPWM2H vector The action time is t 1sv +t 0sv ,t 2sv –t 0sv ,t 0sv Compared with SVPWM, TSPWM1L, TSPWM2L, TSPWM1H, and TSPWM2H have a square of the effective value of the inverter current. The calculation result is:

[0094]

[0095] In the above four equations, Δ1 is Δ2 is By determining the signs of Δ1 and Δ2 in the difference, the phase angle θ, modulation index m and power factor angle can be determined. A modulation method switching mode is used to achieve the minimum effective value of the DC side capacitor current.

[0096] Figure 4 and Figure 5 The area division of the minimum DC side capacitor current effective value modulation method on the space vector αβ plane is shown. The minimum effective value modulation method of the DC side capacitor current is a mixture of five modulation methods: TSPWM1L, TSPWM2L, TSPWM1H, TSPWM2H, and SVPWM. The minimum effective value of the DC side capacitor current can be achieved under the full range of power factor angles and modulation degrees.

[0097] The comparison results are shown in Table 1, where k is an integer, sgn represents the sign function, and MC 2 PWM (Minimum DC-link Capacitor RMS Current Pulse Width Modulation) is a modulation method for the minimum DC-link capacitor RMS current pulse width modulation of a three-phase inverter.

[0098] Table 1: Minimum DC capacitor current modulation method corresponding to different phase angles, modulation degrees and power factor angles

[0099]

[0100] The above-mentioned modulation method of the full-range minimum DC side capacitor current effective value can be physically implemented in the controller.

[0101] like Figure 6 As shown, the implementation steps of the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter in the embodiment of the present application include:

[0102] S10: Given reference voltage vector in dqz synchronous rotating coordinate system Perform per-unit and coordinate transformation to obtain the reference voltage vector d in the abc three-phase stationary coordinate system x ′(x=a,b,c, the same below).

[0103] Preferably, the reference voltage vector given in the dqz synchronous rotating coordinate system is According to half of the DC voltage u obtained by sampling dc / 2 is calibrated to obtain the reference voltage vector after calibration Use the phase angle θ to normalize the reference voltage vector Perform inverse DQZ transformation to obtain the reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c′, specifically:

[0104]

[0105] S20: The three-phase AC voltage u obtained by sampling the hardware circuit as 、u bs 、u cs and the three-phase alternating current i a 、i b 、i c Calculating the power factor angle Specifically:

[0106]

[0107] S30: Based on power factor angle The phase angle θ and the modulation index m determine the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter.

[0108] Here, the method of steps S1 to S3 is used to determine the phase angle θ, modulation degree m and power factor angle Modulation method MC for the full range minimum DC side capacitor current effective value of three-phase inverter 2 PWM.

[0109] As an example, the phase angle θ can be obtained according to a phase-locked loop or a phase generator, and the modulation index m can be given as needed.

[0110] S40: Divide the modulation method MC 2 PWM sectors and determine the zero vector and carrier; determine the injected zero sequence component d based on the zero vector z ′, using the zero sequence component d z ′ and the reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c Calculate the three-phase duty cycle d x .

[0111] Preferably, the modulation method MC is determined according to the principle of avoiding simultaneous switching of multiple bridge arms in one switching cycle. 2 The zero vector that needs to be selected for PWM

[0112] like Figure 7 As shown, Modulation method MC for the minimum effective value of the DC link capacitor current 2 PWM zero vector sector division: oblique line area Ⅰ T , III T Ⅴ T Sector uses zero vector The remaining sectors use zero vectors

[0113] Preferably, the carrier u per phase required for symmetrical pulse width modulation is used. cx There are two types of carriers, one is the increase and decrease count u c1 , the other is the increment and decrement count u c2 .

[0114] like Figure 8 As shown, sector I T ~VI T The zero vector selection can be determined by still And the three-phase carrier selection increase and decrease count u c1 Or decrease or increase the count u c2 .

[0115] Zero sequence component d z 'for:

[0116]

[0117] The reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c ′ is injected with zero sequence component d z ′Get the three-phase modulation wave d x ", three-phase modulation wave d x The three-phase duty cycle d required for pulse width modulation is obtained by shifting upward by 1 and halving the amplitude. x .

[0118] This embodiment can simply and efficiently implement modulation by injecting zero-sequence components without tediously calculating the vector action time, and does not need to occupy a large amount of storage space compared to the lookup table method. Due to the consistency of the three-phase modulation wave, the modulation method of the minimum DC side capacitor current effective value can be used directly.

[0119] S50: At a predetermined switching frequency, use a three-phase duty cycle d x and carrier u cx Generates a three-phase symmetrical pulse width sequence.

[0120] Preferably, a comparator is used to convert the three-phase duty cycle d x and carrier u cx The action moment of the pulse width is determined by comparison to generate the final three-phase symmetrical pulse width sequence.

[0121] As an example, the predetermined switching frequency is 100 kHz.

[0122] In summary, the space vector pulse width modulation method of the three-phase three-wire two-level inverter can achieve the minimum effective value of the DC side capacitor current under the full range of power factor angles and modulation degrees.

[0123] like Fig. 9 and Fig.10 As shown, the modulation method of the embodiment of the present application was tested on a 100kHz full silicon carbide (SiC) three-phase inverter, including MC 2 Comparison of the effective value of per-unit capacitor current of PWM, SVPWM and TSPWM. When the modulation method MC of this embodiment 2 Compared with traditional SVPWM, PWM can reduce the effective value of capacitor current by 43% at most; When the modulation method MC of this embodiment 2 Compared with TSPWM, PWM can reduce the effective value of capacitor current by 62% at most.

[0124] The modulation method for the full-range minimum effective value of the DC side capacitor current of the three-phase inverter in the embodiment of the present application can achieve the minimum effective value of the DC capacitor current under the full range of power factor angles and modulation degrees based on the traversal of all possible three-vector combination modulation methods.

[0125] Preferably, the embodiment of the present application also provides a specific implementation of an electronic device capable of implementing all steps in the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter in the above embodiment, and the electronic device specifically includes the following contents:

[0126] Processor, memory, communication interface and bus;

[0127] Among them, the processor, memory, and communication interface communicate with each other through the bus; the communication interface is used to realize information transmission between related devices such as server-side devices, metering devices, and user-side devices.

[0128] The processor is used to call the computer program in the memory, and when the processor executes the computer program, all steps in the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter in the above embodiment are implemented.

[0129] The embodiments of the present application also provide a computer-readable storage medium capable of implementing all the steps in the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter in the above-mentioned embodiments. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements all the steps in the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter in the above-mentioned embodiments.

[0130] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0131] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0132] Although the present application provides method operation steps such as embodiments or flow charts, more or fewer operation steps may be included based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device or client product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0133] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0134] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0135] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0136] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter, characterized in that: include: S1: Determine a three-vector combination corresponding to a predetermined modulation method; group the three-vector combination according to the intersection of a synthesizable area on the space vector αβ plane and the first sector; S2: Based on the minimum instantaneous inverter current effective value i on the DC side in each group inv,rms , determine a predetermined modulation method for the effective value of each group of minimum DC side capacitor current; S3: Perform a global comparison of the determined predetermined modulation methods based on different phase angles θ, modulation degrees m and power factor angles The inverter current effective value i inv,rms , and obtain the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter.

2. The method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter according to claim 1, characterized in that: The inverter current effective value i inv,rms The calculation formula is: Among them, i 2 inv,rms is the square of the effective value of the inverter current, T s is a switching cycle, i inv,i is the instantaneous input current of the inverter corresponding to the i-th space vector in a switching cycle, t i is the action time of the i-th space vector.

3. The method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter according to claim 1, characterized in that: The number of the predetermined modulation methods and the number of the three-vector combinations are both 13, and the three-vector combinations correspond one-to-one to the predetermined modulation methods.

4. The method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter according to claim 1, characterized in that: The number of groups in step S1 is 5; the predetermined modulation methods determined in step S2 are: SVPWM, TSPWM1L, TSPWM2L, TSPWM1H, TSPWM2H.

5. The method for constructing a full-range minimum DC side capacitor current effective value modulation method for a three-phase inverter according to claim 1, characterized in that: The modulation method obtained in step S3 is:

6. A method for modulating the effective value of the full-range minimum DC side capacitor current of a three-phase inverter, characterized in that: The implementation steps of the modulation method include: S10: performing per-unit and coordinate transformation on a given reference voltage vector in the dqz synchronous rotating coordinate system to obtain a reference voltage vector in the abc three-phase stationary coordinate system; S20: Calculate the power factor angle according to the sampled three-phase AC voltage and three-phase AC current; S30: Determine a modulation method for a full-range minimum effective value of a DC side capacitor current of a three-phase inverter based on a power factor angle, a phase angle and a modulation degree; S40: dividing the modulation method into sectors and determining a zero vector and a carrier; determining an injected zero-sequence component based on the zero vector, and calculating a three-phase duty cycle using the zero-sequence component and a reference voltage vector in the abc three-phase stationary coordinate system; S50: Generate a three-phase symmetrical pulse width sequence using the three-phase duty cycle and the carrier at a predetermined switching frequency.

7. The modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter according to claim 6, characterized in that: Step S10 includes: S100: The reference voltage vector given in the dqz synchronous rotating coordinate system is converted into half of the DC voltage u obtained by sampling. dc / 2 is calibrated to obtain the reference voltage vector after calibration; S110: Use the phase angle to perform an inverse DQZ transformation on the reference voltage vector after standardization to obtain the reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c ′, specifically: Among them, u d ** 、u q ** 、u z ** is the reference voltage vector after standardization, θ is the phase angle; The power factor angle of step S20 The calculation formula is: Among them, u as 、u bs 、u cs is the three-phase AC voltage, i a 、i b 、i c It is a three-phase alternating current.

8. The modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter according to claim 6, characterized in that: The zero sequence component d z 'for: The reference voltage vector d in the abc three-phase stationary coordinate system a ′、d b ′、d c ′ is injected with zero sequence component d z 'Get the modulated wave, the modulated wave is shifted upward by 1 and the amplitude is halved to obtain the three-phase duty cycle.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the modulation method of the full-range minimum DC side capacitor current effective value of the three-phase inverter as described in any one of claims 6 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for modulating the full-range minimum DC side capacitor current effective value of the three-phase inverter as described in any one of claims 6 to 8 are implemented.

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