Segmented synchronous SHEPWM switching method and device based on stator flux linkage vector deviation

Abstract

The invention discloses a segmented synchronous SHEPWM switching method and device based on stator flux linkage vector deviation. The segmented synchronous SHEPWM switching method based on stator flux linkage vector deviation comprises the following steps: acquiring a preset three-level full-speed domain range modulation strategy, wherein the preset three-level full-speed domain range modulation strategy comprises at least one modulation switching; acquiring switching information during each modulation switching according to the preset three-level full-speed domain range modulation strategy; obtaining stator flux linkage vector deviations before and after switching corresponding to the switching information according to the switching information; selecting an optimal switching point corresponding to the stator flux linkage vector deviation before and after each switching according to the stator flux linkage vector deviation before and after each switching; and realizing switching of different carrier ratios according to each optimal switching point. When the optimal switching point is obtained, the amplitude and the phase of the stator flux linkage deviation are considered at the same time, so that the motor current and the torque impact are minimized in the switching process.

Description

Technical Field

[0001] The present application relates to the field of computer technology, and in particular to a segmented synchronous SHEPWM switching method based on stator flux vector deviation and a segmented synchronous SHEPWM switching device based on stator flux vector deviation. Background Art

[0002] The switching frequency of high-power traction drive systems is usually only a few hundred hertz. In order to optimize the current and torque waveforms in the full speed range, different modulation strategies need to be adopted for different speed ranges. This places higher requirements on the modulation strategy of the inverter, which is manifested in two aspects: (1) The switching frequency of the high-voltage inverter is low, and the carrier ratio will vary widely during operation, so a multi-mode modulation strategy needs to be adopted; (2) Switching between different modulation modes will cause current and torque shocks, and smooth switching is the key to multi-mode modulation.

[0003] The commonly used multi-mode modulation strategy is: asynchronous modulation is used in the low frequency band to fully utilize the advantages of the switching frequency; synchronous modulation, SHEPWM or CHMPWM is used in the medium frequency band to optimize the current and torque harmonics; square waves are used in the high frequency band to enable the motor to run at a higher speed. With multi-mode modulation, different modulation modes contain different harmonic contents. The sudden change of harmonic content during the switching process of the modulation mode will cause current shock and torque fluctuation. Excessive shock will cause system oscillation and even trigger safety protection. A switching strategy needs to be applied to ensure a smooth transition of the switching process.

[0004] Existing multi-mode modulation switching methods can be divided into two categories from the fundamental principle: fundamental current continuity and stator flux continuity. The switching strategy based on current fundamental continuity is limited by specific modulation methods and load characteristics, and is not universal in practical applications. At the same time, the process of current harmonic analysis is relatively difficult, and generally only limited low-order harmonics with greater influence can be analyzed, while high-order harmonics are difficult to consider at the same time. Therefore, the switching strategy obtained still has considerable current shock and torque fluctuation when switching. The analysis of the stator flux characteristics is based on the stator flux characteristics at different switching points. By analyzing the harmonic flux amplitude and the harmonic flux amplitude deviation, it is determined whether the stator flux before and after different switching points is continuous, and the optimal switching point is selected. However, this method directly selects the optimal switching point based on only one factor, the stator flux vector deviation amplitude, and does not analyze the situation of the same amplitude but different phase angles. Summary of the invention

[0005] The object of the present invention is to provide a segmented synchronous SHEPWM switching method based on stator flux vector deviation to solve at least one of the above technical problems.

[0006] One aspect of the present invention provides a segmented synchronous SHEPWM switching method based on stator flux vector deviation, the segmented synchronous SHEPWM switching method based on stator flux vector deviation comprising:

[0007] Acquire a preset three-level full-speed domain-wide modulation strategy, wherein the preset three-level full-speed domain-wide modulation strategy includes at least one modulation switching;

[0008] Obtaining switch information at each modulation switching according to the preset three-level full-speed domain range modulation strategy;

[0009] Obtaining stator flux vector deviations before and after switching corresponding to the switching information respectively according to the switching information;

[0010] Selecting an optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching;

[0011] Switching between different carrier ratios is achieved according to each optimal switching point.

[0012] Optionally, the switching information includes a switching sequence, a switching instant modulation degree, a number of switching angles before switching, and a number of switching angles after switching.

[0013] Optionally, the obtaining, according to the switch information, stator flux vector deviations before and after the switching corresponding to the switch information respectively includes:

[0014] The stator flux vector deviation before and after switching corresponding to any switching information is obtained by the following method:

[0015] Acquiring a three-phase stator voltage of the motor according to the switch information, wherein the three-phase stator voltage includes a steady-state stator voltage before switching and a steady-state stator voltage after switching;

[0016] Obtaining the stator flux vector according to the three-phase stator voltage;

[0017] Obtaining an actual stator flux trajectory and an expected stator flux trajectory at the switching moment according to the steady-state stator voltage before switching and the steady-state stator voltage after switching;

[0018] The stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment.

[0019] Optionally, the expected stator flux trajectory is obtained by the following formula:

[0020] in,

[0021] Ψ s2 (t 2 ) is Ψs2 (t) at t 2 The magnetic flux amplitude at the moment, Ψ s2 (t) is the expected stator flux trajectory and dt is the time increment.

[0022] Optionally, the actual stator flux trajectory at the switching moment is obtained by the following formula:

[0023] in,

[0024] t 1 To start calling the switch sequence P(N 1 ,M) time, the steady-state stator voltage u before switching s1 P(N 1 ,M) corresponds to the PWM output steady-state stator voltage, Ψ s1 (t 1 ) is t 1 The initial value of stator flux at time .

[0025] Optionally, the stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment by using the following formula:

[0026] Ψ sd (t) = Ψ s2 (t)-Ψ s1 (t); where

[0027] Ψ s1 (t) is the actual stator flux trajectory at the switching moment, Ψ s2 (t) is the desired stator flux trajectory, Ψ sd Indicates the stator flux error before and after switching.

[0028] Optionally, selecting the optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching includes:

[0029] The optimal switching point corresponding to the stator flux vector deviation before and after each switching is obtained by the following method:

[0030] The flux deviation during three-phase switching is obtained according to the stator flux vector deviation before and after the switching;

[0031] Extracting the maximum phase of the flux deviation amplitude of the flux deviation;

[0032] Obtaining an objective function for minimizing switching impact that can make a relatively small point of maximum flux linkage amplitude as an optimal switching point;

[0033] The minimum point of flux vector deviation is selected according to the maximum phase of flux deviation amplitude of the flux deviation and the result of the objective function, and the minimum point of flux vector deviation is used as the optimal switching point corresponding to the stator flux vector deviation before and after the switching.

[0034] Optionally, the flux deviation during three-phase switching is obtained according to the stator flux vector deviation before and after the switching using the following formula:

[0035] in,

[0036] Ψ ad ,Ψ bd ,Ψ cd They represent the flux deviation of the three phases respectively, and θ is the stator flux vector deviation phase angle.

[0037] The present application also provides a segmented synchronous SHEPWM switching device based on stator flux vector deviation, and the segmented synchronous SHEPWM switching device based on stator flux vector deviation includes:

[0038] A three-level full-speed domain-wide modulation strategy acquisition module, wherein the three-level full-speed domain-wide modulation strategy acquisition module is used to acquire a preset three-level full-speed domain-wide modulation strategy, wherein the preset three-level full-speed domain-wide modulation strategy includes at least one modulation switching;

[0039] A switch information acquisition module, the switch information acquisition module is used to obtain the switch information at each modulation switching according to the preset three-level full-speed domain range modulation strategy;

[0040] A stator flux vector deviation acquisition module, the stator flux vector deviation acquisition module is used to respectively acquire the stator flux vector deviations before and after the switching corresponding to the switching information according to the switching information;

[0041] An optimal switching point acquisition module, the optimal switching point acquisition module is used to select an optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching;

[0042] A switching module, wherein the switching module is used to implement switching of different carrier ratios according to various optimal switching points.

[0043] Beneficial effects:

[0044] The segmented synchronous SHEPWM switching method based on stator flux vector deviation proposed in the present application takes into account both the amplitude and phase of the stator flux deviation when obtaining the optimal switching point, and can directly obtain the optimal switching point between any two synchronous modulation modes through quantitative calculation, thereby minimizing the motor current and torque impact during the switching process. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of a segmented synchronous SHEPWM switching method based on stator flux vector deviation in one embodiment of the present invention;

[0046] Figure 2 It is a schematic diagram of a three-level full-speed range modulation strategy based on SHWPWM;

[0047] Figure 3 It is a schematic diagram of the structure for solving the SHEPWM switch angle when N=5;

[0048] Figure 4 It is a schematic diagram of the output voltage waveform of the three-phase bridge arm of the SHEPWM inverter when N=5;

[0049] Figure 5 It is a schematic diagram of the output voltage waveform of the three-phase bridge arm of the SHEPWM inverter when N=3;

[0050] Figure 6 It is the flux error between the two when SHEPWM switches from the switching angle N=5 to N=3;

[0051] Figure 7 It is the curve of the change of the amplitude of the three-phase flux deviation vector before and after the space voltage vector phase is switched in the range of 0 to π / 3;

[0052] Figure 8 It is a schematic diagram of selecting the optimal switching point from the maximum flux linkage deviation amplitude;

[0053] Fig. 9 It is a schematic diagram of the current (i.e., stator current) change curve caused by switching at the 10° sampling point;

[0054] Fig.10 It is a schematic diagram of the torque (i.e. electromagnetic torque) impact curve caused by switching at the 10° sampling point;

[0055] Fig.11 It is a schematic diagram of the current (i.e., stator current) change curve caused by switching at the 30° sampling point;

[0056] Fig.12 It is a schematic diagram of the torque (i.e., electromagnetic torque) impact curve caused by switching at the 30° sampling point;

[0057] Fig.13 is a schematic diagram of an electronic device in an embodiment of the present application. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0059] like Figure 1 The segmented synchronous SHEPWM switching method based on stator flux vector deviation shown includes:

[0060] Step 1: obtaining a preset three-level full-speed domain-wide modulation strategy, wherein the preset three-level full-speed domain-wide modulation strategy includes at least one modulation switching;

[0061] Step 2: Obtaining switch information at each modulation switching according to the preset three-level full-speed range modulation strategy;

[0062] Step 3: Obtaining stator flux vector deviations before and after switching corresponding to the switching information respectively according to the switching information;

[0063] Step 4: Selecting the optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching;

[0064] Step 5: Implement switching of different carrier ratios according to each optimal switching point.

[0065] The segmented synchronous SHEPWM switching method based on stator flux vector deviation proposed in the present application takes into account both the amplitude and phase of the stator flux deviation when obtaining the optimal switching point, and can directly obtain the optimal switching point between any two synchronous modulation modes through quantitative calculation, thereby minimizing the motor current and torque impact during the switching process.

[0066] In this embodiment, the switching information includes a switching sequence, a switching instant modulation degree, a number of switching angles before switching, and a number of switching angles after switching.

[0067] In this embodiment, respectively obtaining the stator flux vector deviation before and after the switching corresponding to the switching information according to the switching information includes:

[0068] The stator flux vector deviation before and after switching corresponding to any switching information is obtained by the following method:

[0069] Acquiring a three-phase stator voltage of the motor according to the switch information, wherein the three-phase stator voltage includes a steady-state stator voltage before switching and a steady-state stator voltage after switching;

[0070] Obtaining the stator flux vector according to the three-phase stator voltage;

[0071] Obtaining an actual stator flux trajectory and an expected stator flux trajectory at the switching moment according to the steady-state stator voltage before switching and the steady-state stator voltage after switching;

[0072] The stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment.

[0073] In this embodiment, the desired stator flux trajectory is obtained by the following formula:

[0074] in,

[0075] Ψ s2 (t 2 ) is Ψ s2 (t) at t 2 The magnetic flux amplitude at the moment, Ψ s2 (t) is the expected stator flux trajectory and dt is the time increment.

[0076] In this embodiment, the actual stator flux trajectory at the switching moment is obtained by the following formula:

[0077] in,

[0078] t 1 To start calling the switch sequence P(N 1 ,M) time, the steady-state stator voltage u before switching s1 P(N 1 ,M) corresponds to the PWM output steady-state stator voltage, Ψ s1 (t 1 ) is t 1 The initial value of stator flux at time .

[0079] In this embodiment, the stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment by the following formula:

[0080] Ψ sd (t) = Ψ s2 (t)-Ψ s1 (t); where

[0081] Ψ s1(t) is the actual stator flux trajectory at the switching moment, Ψ s2 (t) is the desired stator flux trajectory, Ψ sd Indicates the stator flux error before and after switching.

[0082] In this embodiment, the selecting of the optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching includes:

[0083] The optimal switching point corresponding to the stator flux vector deviation before and after each switching is obtained by the following method:

[0084] The flux deviation during three-phase switching is obtained according to the stator flux vector deviation before and after the switching;

[0085] Extracting the maximum phase of the flux deviation amplitude of the flux deviation;

[0086] Obtaining an objective function for minimizing switching impact that can make a relatively small point of maximum flux linkage amplitude as an optimal switching point;

[0087] The minimum point of flux vector deviation is selected according to the maximum phase of flux deviation amplitude of the flux deviation and the result of the objective function, and the minimum point of flux vector deviation is used as the optimal switching point corresponding to the stator flux vector deviation before and after the switching.

[0088] In this embodiment, the flux deviation during three-phase switching is obtained based on the stator flux vector deviation before and after the switching using the following formula:

[0089] in,

[0090] Ψ ad ,Ψ bd ,Ψ cd They represent the flux deviation of the three phases respectively, and θ is the stator flux vector deviation phase angle.

[0091] The present application is further described in detail below by way of examples. It should be understood that the examples do not constitute any limitation to the present application.

[0092] See also Figure 2 , Figure 2 A three-level full-speed range modulation strategy of an embodiment of the present application is a full-speed range modulation based on selected harmonic elimination pulse width modulation (SHEPWM), where N is the number of switching angles within a 1 / 4 period.

[0093] For the convenience of description, the following description takes the case where the motor frequency is 40 Hz and the modulation ratio is 0.8 and the switching angle is switched from N=5 to N=3 as an example.

[0094] In this embodiment, the voltage waveform generated by the modulation mode has the characteristics of half-wave symmetry and quarter-wave symmetry. When N=5, the SHEPWM switch sequence distribution diagram with the modulation degree is as follows: Figure 3 As shown, it can be understood that the switching sequences of different modulation modes are obtained by solving phase voltage equations of different orders; the specific solution process can adopt any known method, for example, the method for solving the SHEPWM switching sequence generally includes Newton iteration method, genetic algorithm, homology algorithm, Walsh function transformation method, etc. The algorithm used in this article is Newton iteration method, which will not be repeated in this application.

[0095] In this embodiment, various switch information obtained in this application can be stored in a table for subsequent use.

[0096] It can be understood that in the present application, the switch sequences P(N1, M) and P(N2, M) before and after the modulation mode are obtained according to the switching instant modulation degree M, the number of switch angles N1 before switching and the number of switch angles N2 after switching. The specific calculation method can adopt any known method. For example, the method for obtaining the switch sequence includes Newton iteration method, genetic algorithm, homology algorithm, Walsh function transformation method, etc. The algorithm used in this article is Newton iteration method. It will not be repeated in the present invention.

[0097] In this embodiment, the three-phase stator voltage of the motor, the steady-state stator voltage before switching, and the steady-state stator voltage after switching can be obtained according to the switch information by using the following method:

[0098] The three-phase stator voltage of the reconstructed motor includes:

[0099]

[0100] Where S i (t) is the acquired switch sequence, t is the sampling time, i is the three-phase bridge arm a, b, c, u i is the reconstructed three-phase stator voltage, U dc is the DC bus voltage. According to the number of switch angles before switching, N 1 And the number of switch angles after switching N 2 , the modulation degree before and after switching, the motor stator fundamental frequency ω at the switching moment, and the reconstruction of the steady-state stator voltage u before switching s1 and the steady-state stator voltage u after switching s2 The voltage waveforms of the motor A, B, and C phases corresponding to the SHEPWM of N=5 and N=3 before and after the switching are calculated by the above formula as follows: Figure 4 and Figure 5shown.

[0101] In this embodiment, calculating the stator flux vector according to the three-phase voltage includes:

[0102] u(t)=u m e jωt ;

[0103]

[0104] Among them, ω represents the fundamental frequency of the motor stator, u m is the stator voltage vector amplitude, t is the sampling time, u(t) is the stator voltage vector, Ψ(t) is the stator flux vector, Ψ(t 0 ) is the stator flux vector at t = t 0 The initial value of the time, j is the imaginary unit.

[0105] In this embodiment, by calculating the steady-state stator voltage u before switching s1 and the steady-state stator voltage u after switching s2 By performing integral calculation, the actual stator flux trajectory Ψ at the switching moment can be obtained s1 and the desired stator flux trajectory Ψ s2 .

[0106] In this embodiment, the flux integration process is an offline calculation, the starting point of the flux trajectory is the origin of the coordinate axis, and the center of the actual flux trajectory is the origin, so the result of the offline calculation has a DC bias, which needs to be corrected. In this embodiment, the bias correction of the stator flux trajectory includes:

[0107]

[0108] Among them, err is the correction value of stator flux DC bias, Ψ s (t) is the stator flux trajectory.

[0109] In this embodiment, the stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment using the following formula:

[0110] Ψ sd (t) = Ψ s2 (t)-Ψ s1 (t)

[0111] Among them, s1 (t) is the actual stator flux trajectory at the switching moment, Ψ s2 (t) is the expected stator flux trajectory.

[0112] In this embodiment, the actual stator flux trajectory Ψ at the switching moment s1 As shown below:

[0113]

[0114] Among them, t 1 To start calling the switch sequence P(N 1 ,M) time, the steady-state stator voltage u before switching s1 P(N 1 ,M) corresponds to the PWM output steady-state stator voltage, Ψ s1 (t 1 ) is t 1 The initial value of stator flux at time .

[0115] In this embodiment, when t 2 When the working conditions change, the stator flux vector expression is as follows:

[0116]

[0117] Among them, t2 is the start of calling the switch sequence P(N 2 ,M) time, the steady-state stator voltage u after switching s2 P(N 2 ,M) corresponds to the PWM output steady-state stator voltage, Ψ s1 (t 2 ) is Ψ s1 (t) Stator flux amplitude at time t2.

[0118] In this embodiment, the desired stator flux trajectory Ψ s2 It can be expressed by the following formula:

[0119]

[0120] Among them, s2 (t 2 ) is Ψ s2 (t) at t 2 The magnetic flux amplitude at the moment.

[0121] Because s1 (t 2 )≠Ψ s2 (t 2 ), so at t = t 2 Actual magnetic link at the moment s2 (t 2 ) does not optimize the flux trajectory Ψ s2 (t), thus a dynamic modulation error will occur.

[0122] Taking the switching angle of SHEPWM from N = 5 to N = 3 as an example, the magnetic flux error diagram of the two is as follows Figure 6 The solid line in the figure shows the SHEPWM switching sequence P(N) when N=5.1 ,M) corresponding to the optimized flux trajectory, the dotted line shows the SHEPWM switching sequence P(N) when N = 3 2 , M) corresponding to the optimized flux trajectory. The switching time t = t 2 The difference between the actual flux linkage and the steady-state optimized flux linkage is used to obtain the stator flux linkage error. The stator flux linkage error is stored in a table so that it can be called in real time according to the modulation index M and the fundamental phase.

[0123] The traditional strategy is to use the observed flux trajectory output by the flux observer as the stator flux of the motor before switching, and to subtract it from the expected stator flux to obtain the dynamic stator flux error of the switching process. However, the stator flux output by the observer is only the fundamental flux, while the actual flux contains multiple harmonic fluxes, and there is a large deviation between the observed flux and the actual flux. In the present invention, the actual stator flux trajectory at the moment of switching is obtained by solving the PWM pulse actually acting on the inverter, fully considering the harmonic flux, and the solution result is closer to the actual stator flux than the result obtained by the observer. Therefore, compared with the existing stator flux error calculation strategy by subtracting the observed flux from the target flux, the present invention is more in line with the actual switching process, and the error calculation result is more accurate.

[0124] In this embodiment, the flux deviation during three-phase switching can be obtained based on the stator flux vector deviation before and after the switching using the following formula:

[0125]

[0126] Among them ad ,Ψ bd ,Ψ cd They represent the flux deviation of the three phases respectively, and θ is the stator flux vector deviation phase angle.

[0127] In this embodiment, the following method is used to extract the maximum phase of the flux deviation amplitude of the flux deviation:

[0128] The maximum value of the three-phase stator flux amplitude during switching is extracted and expressed as:

[0129] Ψ m =max(|Ψ ad |,Ψ bd |,|Ψ cd |);

[0130] Ψ opt =min(Ψ m1 ,Ψ m2 ,Ψ m3 );

[0131] For a single-phase bridge arm, the stator flux amplitude before and after switching is not continuous, and the larger the amplitude deviation, the more obvious the current shock and torque fluctuation brought to the phase. Therefore, the present application first compares the flux deviation at the same switching point to obtain the maximum flux deviation at the switching point, and compares the maximum flux deviation at all switching points to obtain the point that can make the maximum flux deviation relatively small as the optimal switching point.

[0132] In this embodiment, the objective function for minimizing the switching impact is:

[0133] Ψ opt =min(Ψ m1 ,Ψ m2 ,Ψ m3 ).

[0134] Since the stator flux trajectory is symmetrical about 30° in the 0-60° sector, it is only necessary to analyze all sampling points in the 0-30° sector, and the remaining sectors can be normalized to the 0-60° sector for calculation.

[0135] This paper takes 10° as a sampling period, and there are 36 evenly distributed sampling points in a fundamental wave period, and the switching point can be selected from them. According to the above formula, a curve of the three-phase flux deviation vector amplitude is drawn in a sector, that is, when θ changes from zero to π / 3, and the maximum flux deviation at all switching points is compared, and the point that can make the maximum flux deviation relatively small is obtained as the optimal switching point.

[0136] Figure 7 It is the change curve of the three-phase flux deviation vector amplitude before and after the spatial voltage vector phase is switched in the range of 0-π / 3. It can be seen from the figure that at the 0° sampling point, the BC phase flux deviation is slightly larger than the A phase; at the 10° and 20° sampling points, the C phase flux deviation is the largest; at the 30° sampling point, the B phase flux deviation is larger than the A phase and the C phase. According to the above objective function of minimizing the switching impact, it can be obtained that the stator flux deviation is the smallest at the 30° sampling point, so the 30° sampling point can be selected as the optimal switching point within the spatial voltage vector range of 0 to 30°. Therefore, the 30° sampling point is the optimal switching phase for switching from SHEPWM of N=5 to SHEPWM of N=3 when the modulation ratio M=0.8. Figure 8 Schematic diagram of selecting the optimal switching point from the maximum flux deviation amplitude.

[0137] Fig. 9 is a schematic diagram of the current (i.e., stator current) change curve caused by switching at the 10° sampling point. Fig.10 It is a schematic diagram of the torque (i.e., electromagnetic torque) impact curve caused by switching at the 10° sampling point; Fig.11 The schematic diagram of the current change curve caused by switching at the 30° sampling point is shown in Figure 2. Fig.12Figure 3 is a schematic diagram of the torque shock curve caused by switching at the 30° sampling point. The results show that switching at the 30° sampling point can achieve smooth switching of torque and current without shock.

[0138] The present application also provides a segmented synchronous SHEPWM switching device based on stator flux vector deviation, the segmented synchronous SHEPWM switching device based on stator flux vector deviation comprises a three-level full-speed range modulation strategy acquisition module, a switch information acquisition module, a stator flux vector deviation acquisition module, an optimal switching point acquisition module and a switching module, wherein:

[0139] The three-level full-speed domain range modulation strategy acquisition module is used to acquire a preset three-level full-speed domain range modulation strategy, wherein the preset three-level full-speed domain range modulation strategy includes at least one modulation switching;

[0140] The switch information acquisition module is used to acquire the switch information at each modulation switching according to the preset three-level full-speed domain range modulation strategy;

[0141] The stator flux vector deviation acquisition module is used to acquire the stator flux vector deviation before and after the switching corresponding to the switching information according to the switching information;

[0142] The optimal switching point acquisition module is used to select the optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching;

[0143] The switching module is used to implement switching of different carrier ratios according to various optimal switching points.

[0144] It should be noted that the above explanations of the method embodiment are also applicable to the device of this embodiment and will not be repeated here.

[0145] The present application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor. When the processor executes the computer program, the above-mentioned segmented synchronous SHEPWM switching method based on stator flux vector deviation is implemented.

[0146] The present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the above-mentioned segmented synchronous SHEPWM switching method based on stator flux vector deviation can be implemented.

[0147] Fig.13 It is an exemplary structural diagram of an electronic device that can implement the segmented synchronous SHEPWM switching method based on stator flux vector deviation provided according to an embodiment of the present application.

[0148] like Fig.13 As shown, the electronic device includes an input device 501, an input interface 502, a central processor 503, a memory 504, an output interface 505, and an output device 506. The input interface 502, the central processor 503, the memory 504, and the output interface 505 are interconnected through a bus 507, and the input device 501 and the output device 506 are connected to the bus 507 through the input interface 502 and the output interface 505, respectively, and then connected to other components of the electronic device. Specifically, the input device 501 receives input information from the outside, and transmits the input information to the central processor 503 through the input interface 502; the central processor 503 processes the input information based on the computer executable instructions stored in the memory 504 to generate output information, temporarily or permanently stores the output information in the memory 504, and then transmits the output information to the output device 506 through the output interface 505; the output device 506 outputs the output information to the outside of the electronic device for use by the user.

[0149] That is to say, Fig.13 The electronic device shown can also be implemented as comprising: a memory storing computer executable instructions; and one or more processors, which can implement the combination when executing the computer executable instructions. Figure 1 A segmented synchronous SHEPWM switching method based on stator flux vector deviation is described.

[0150] In one embodiment, Fig.13 The electronic device shown can be implemented to include: a memory 504 configured to store executable program code; and one or more processors configured to run the executable program code stored in the memory 504 to execute the segmented synchronous SHEPWM switching method based on stator flux vector deviation in the above embodiment.

[0151] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0152] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0153] Computer readable media include permanent and non-permanent, removable and non-removable, and the media can be implemented by any method or technology to store information. The information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), data versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device.

[0154] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and a module, a program segment or a part of a code includes one or more executable instructions for realizing the specified logical function. It should also be noted that in some implementations as replacements, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes identified in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or the total flow chart can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0155] The processor referred to in this embodiment may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0156] The memory can be used to store computer programs and / or modules. The processor realizes various functions of the device / terminal equipment by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0157] In this embodiment, if the module / unit integrated in the device / terminal equipment is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. Although the present application is disclosed as above in terms of a preferred embodiment, it is not intended to limit the present application. Any technical personnel in this field may make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined by the claims of the present application.

[0158] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt 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.) that contain computer-usable program code.

[0159] In addition, it is obvious that the word "comprising" does not exclude other units or steps. Multiple units, modules or devices stated in the device claim can also be implemented by one unit or the overall device through software or hardware.

[0160] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A segmented synchronous SHEPWM switching method based on stator flux vector deviation, characterized in that: The segmented synchronous SHEPWM switching method based on stator flux vector deviation includes: Acquire a preset three-level full-speed domain-wide modulation strategy, wherein the preset three-level full-speed domain-wide modulation strategy includes at least one modulation switching; Obtaining switch information at each modulation switching according to the preset three-level full-speed domain range modulation strategy; Obtaining stator flux vector deviations before and after switching corresponding to the switching information respectively according to the switching information; Selecting an optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching; Switching between different carrier ratios is achieved according to each optimal switching point.

2. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 1 is characterized in that: The switching information includes a switching sequence, a switching instant modulation degree, a number of switching angles before switching, and a number of switching angles after switching.

3. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 2 is characterized in that: The step of respectively obtaining the stator flux vector deviation before and after the switching corresponding to the switching information according to the switching information comprises: The stator flux vector deviation before and after switching corresponding to any switching information is obtained by the following method: Acquiring a three-phase stator voltage of the motor according to the switch information, wherein the three-phase stator voltage includes a steady-state stator voltage before switching and a steady-state stator voltage after switching; Obtaining the stator flux vector according to the three-phase stator voltage; Obtaining an actual stator flux trajectory and an expected stator flux trajectory at the switching moment according to the steady-state stator voltage before switching and the steady-state stator voltage after switching; The stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment.

4. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 3 is characterized in that: The desired stator flux trajectory is obtained by the following formula: in, Ψ s2 (t2) is Ψ s2 (t) The flux amplitude at time t2, Ψ s2 (t) is the expected stator flux trajectory and dt is the time increment.

5. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 4 is characterized in that: The actual stator flux trajectory at the switching moment is obtained by the following formula: in, t1 is the moment when the switching sequence P(N1,M) is called. The steady-state stator voltage u before switching is s1 is the PWM output steady-state stator voltage corresponding to P(N1,M), Ψ s1 (t1) is the initial value of stator flux at time t1.

6. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 5 is characterized in that: The stator flux error is obtained according to the actual stator flux trajectory and the expected stator flux trajectory at the switching moment by the following formula: P sd (t)=Ψ s2 (t)-Ψ s1 (t); among which, Ψ s1 (t) is the actual stator flux trajectory at the switching moment, Ψ s2 (t) is the desired stator flux trajectory, Ψ sd Indicates the stator flux error before and after switching.

7. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 6 is characterized in that: The step of selecting the optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching comprises: The optimal switching point corresponding to the stator flux vector deviation before and after each switching is obtained by the following method: The flux deviation during three-phase switching is obtained according to the stator flux vector deviation before and after the switching; Extracting the maximum phase of the flux deviation amplitude of the flux deviation; Obtaining an objective function for minimizing switching impact that can make a relatively small point of maximum flux linkage amplitude as an optimal switching point; The minimum point of flux vector deviation is selected according to the maximum phase of flux deviation amplitude of the flux deviation and the result of the objective function, and the minimum point of flux vector deviation is used as the optimal switching point corresponding to the stator flux vector deviation before and after the switching.

8. The segmented synchronous SHEPWM switching method based on stator flux vector deviation according to claim 7 is characterized in that: The flux deviation during three-phase switching is obtained based on the stator flux vector deviation before and after the switching using the following formula: in, Ψ ad ,Ψ bd ,Ψ cd They represent the flux deviation of the three phases respectively, and θ is the stator flux vector deviation phase angle.

9. A segmented synchronous SHEPWM switching device based on stator flux vector deviation, characterized in that: The segmented synchronous SHEPWM switching device based on stator flux vector deviation includes: A three-level full-speed domain-wide modulation strategy acquisition module, wherein the three-level full-speed domain-wide modulation strategy acquisition module is used to acquire a preset three-level full-speed domain-wide modulation strategy, wherein the preset three-level full-speed domain-wide modulation strategy includes at least one modulation switching; A switch information acquisition module, the switch information acquisition module is used to obtain the switch information at each modulation switching according to the preset three-level full-speed domain range modulation strategy; A stator flux vector deviation acquisition module, the stator flux vector deviation acquisition module is used to respectively acquire the stator flux vector deviations before and after the switching corresponding to the switching information according to the switching information; An optimal switching point acquisition module, the optimal switching point acquisition module is used to select an optimal switching point corresponding to the stator flux vector deviation before and after each switching according to the stator flux vector deviation before and after each switching; A switching module, wherein the switching module is used to implement switching of different carrier ratios according to various optimal switching points.

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