A three-level inverter permanent magnet synchronous motor SVPWM control method for electric vehicles

Abstract

The application discloses a kind of SVPWM control methods of three-level inverter permanent magnet synchronous motor for electric vehicle, it is related to motor drive and control technical field in electric vehicle high-voltage main drive system, method is: the basic voltage vector of the larger common-mode voltage is discarded to obtain new basic voltage vector diagram;The difference between reference speed and current speed is obtained by outer ring speed PI controller, and q-axis reference current is given d-axis reference current;Three-phase stator current is obtained by Clark and Park conversion d, q-axis component;The α, β-axis component of reference voltage vector is obtained by using deadbeat current prediction control method and through anti-park conversion;The sector where reference voltage vector is located is judged, and the appropriate basic voltage vector is selected based on the new basic voltage vector diagram, the optimal vector combination is selected by value function, and the switching sequence is output in the principle of minimum total switching times, and the inverter is acted on, to drive permanent magnet synchronous motor, improve the energy utilization efficiency of electric vehicle.

Description

Technical Field

[0001] This invention relates to the field of motor drive and control technology in high-voltage main drive systems for electric vehicles, and in particular to an SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles. Background Technology

[0002] Inverters, as a key power conversion component connecting the battery pack and the permanent magnet synchronous motor (PMSM), play a crucial role in the power drive and control system of electric vehicles. Their performance directly determines the driving range, acceleration performance, and ride comfort of the electric vehicle. Although traditional two-level inverters have a simple topology and mature control methods, with the increasing demand for high-voltage, high-power, and high-efficiency drive in electric vehicles, the switching losses and output waveform quality of two-level inverters in high-voltage, high-power applications are gradually becoming insufficient to meet the requirements.

[0003] In comparison, three-level inverters, due to their unique topology, possess significant advantages, making them particularly suitable for high-power motor drive systems in electric vehicles. Three-level inverters achieve lower switching losses, provide higher output waveform quality, and offer more flexible control. However, neutral-point clamped (NPC) three-level inverters inherently suffer from neutral-point potential imbalance. This imbalance increases output voltage harmonic content and reduces the lifespan of inverter components. Furthermore, the common-mode voltage generated during high-frequency switching leads to additional heat loss in electric vehicle motor drives, affecting the mechanical life of motor bearings and accelerating the aging of motor winding insulation. These factors all pose challenges to the long-term reliability of electric vehicle drive systems.

[0004] SVPWM (Space Vector Pulse Width Modulation) control is considered an effective technology for solving the high dynamic performance control of electric vehicle motor drives due to its advantages such as fast response speed, ability to achieve multi-objective optimization, and simple principle. However, traditional single-vector MPCC (Model Predictive Current Control) only applies one voltage vector in each sampling cycle, resulting in relatively poor steady-state performance. While the closest three-vector method using SVPWM improves the current waveform, it still faces the contradiction of redundant vector selection and optimization balance in addressing midpoint voltage imbalance and common-mode voltage suppression in three-level inverters. Therefore, researching an SVPWM control method that can effectively suppress midpoint voltage fluctuations and common-mode voltage while improving the output current waveform is of significant practical importance, given the high-performance and high-reliability drive requirements of electric vehicles. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides an SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles, which is applicable to the main drive system of electric vehicles and can effectively suppress midpoint voltage fluctuations and common-mode voltage, while improving the output current waveform and dynamic response performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution, including:

[0007] An SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles includes the following steps:

[0008] S1, establish the basic voltage vector diagram and divide it into sectors. Discard the basic voltage vector diagrams whose common-mode voltage exceeds the set threshold to obtain a new basic voltage vector diagram.

[0009] S2, obtain the electrical angle θ(k) and speed ω(k) of the permanent magnet synchronous motor at time k, and convert the three-phase stator current of the motor... , , The d-axis and q-axis components of the stator current are obtained through Clark and Park transformations. , ;

[0010] S3, reference speed The difference between the current motor speed ω(k) and the input to the outer loop speed PI controller is used to obtain the q-axis reference current. Given the d-axis reference current ;

[0011] S4. Calculate the reference voltage vector using the deadbeat current predictive control method to obtain the reference voltage vector values ​​on the d and q axes. , By using the inverse Park transformation, the reference voltage vector values ​​along the α and β axes are obtained. , ;

[0012] S5. Determine the sector where the reference voltage vector is located. Based on the new basic voltage vector diagram, select three basic voltage vectors in the sector where the reference voltage vector is located and the two adjacent sectors and determine the corresponding action time to satisfy the reference voltage vector. Select the vector combination with the minimum value function as the optimal vector combination through rolling optimization. Then, determine the action order of the three basic voltage vectors in the optimal vector combination according to the principle of minimizing the total number of switching, and convert it into the switching sequence of the three-level inverter for output.

[0013] Preferably, step S1 specifically includes the following:

[0014] S11, Create the basic voltage vector diagram:

[0015] The DC-side voltage of the three-level inverter is A three-level inverter has three phase arms, A, B, and C. Each phase arm has four switches, labeled 1, 2, 3, and 4. Opening switches 1 and 2 and closing switches 3 and 4 is called the P state. In the P state, the output voltage of the arm is... Open switches 2 and 3, and close switches 1 and 4 (recorded as state 0). In state 0, the output voltage of the bridge arm is 0. Open switches 3 and 4, and close switches 1 and 2 (recorded as state N). In state N, the output voltage of the bridge arm is... ;

[0016] use , , This indicates the switching state value of each phase arm of the bridge, and the three-phase voltages A, B, and C. , , Represented as:

[0017] , , ;

[0018] In the formula, , ; This indicates that the switch state of the bridge arm is P. This indicates that the switch state of the bridge arm is N. This indicates that the switch state of the bridge arm is 0.

[0019] There are 3×3×3=27 switching states in the three-phase bridge arm. Substituting the 27 switching states into the voltage space vector expression, we can calculate the direction and magnitude of the corresponding voltage space vector in the stationary coordinate system to obtain the basic voltage vector diagram. The basic voltage vector of the basic voltage vector diagram is denoted as V. There are a total of 27 basic voltage vectors.

[0020] The voltage space vector expression is:

[0021] ;

[0022] In the formula, U is the voltage space vector, and j is the imaginary part;

[0023] S12, divide into sectors:

[0024] The sector is determined by the angle δ between the basic voltage vector and the α axis, and is denoted as follows: First major sector, 0≤δ<60°; Second major sector, 60°≤δ<120°; Third major sector, 120°≤δ<180°; Fourth major sector, 180°≤δ<240°; Fifth major sector, 240°≤δ<300°; Sixth major sector, 300°≤δ<360°.

[0025] S13, Calculate the common-mode voltage :

[0026] ;

[0027] Based on the absolute value of the common-mode voltage, it is divided into , , , Four categories, discarding the absolute value of the common-mode voltage. and The corresponding basic voltage vector;

[0028] S14, Based on the remaining basic voltage vector, establish a new basic voltage vector diagram.

[0029] Preferably, in step S4, a deadbeat current prediction control method is used to calculate the reference voltage vector values ​​on the d and q axes according to the following formula. , :

[0030] ;

[0031] ;

[0032] In the formula, , The d-axis and q-axis inductances of the motor stator windings. Sampling time, For stator resistance, It is a permanent magnet flux linkage.

[0033] Preferably, in step S5, the method for determining the sector where the reference voltage vector is located is as follows:

[0034] when >0 and At that time, the reference voltage vector is in the first largest sector;

[0035] when >0 and At that time, the reference voltage vector is in the second largest sector;

[0036] when >0 and At that time, the reference voltage vector is in the third largest sector;

[0037] when <0 and At that time, the reference voltage vector is in the fourth largest sector;

[0038] when <0 and At that time, the reference voltage vector is in the fifth major sector;

[0039] when <0 and At that time, the reference voltage vector is in the sixth sector.

[0040] Preferably, in step S5, three basic voltage vectors satisfying the reference voltage vector are found in the sector where the reference voltage vector is located and in the two adjacent sectors using the volt-second balance principle, and the corresponding action time is determined. The calculation formula is as follows:

[0041] ;

[0042] In the formula, Uo is the reference voltage vector. , , These are the three basic voltage vectors. , , These are the three basic voltage vectors. , , Duration of action Let be the sampling time, and we have:

[0043] , ;

[0044] Among them, the absolute value of the reference voltage vector .

[0045] Preferably, in step S5, the value function is as follows:

[0046] ;

[0047] in, Where C is the midpoint voltage, and C is the capacitance of a single DC bus capacitor in a three-level inverter. , , These are the three basic voltage vectors. , , The generated midpoint current, This is the value of the value function.

[0048] Preferably, in step S5, the order of action of the three basic voltage vectors in the optimal vector combination is determined based on the principle of minimizing the total number of switching operations, as shown below:

[0049] A three-level inverter has three phase arms, A, B, and C. Each phase arm has four switches, labeled as switches one, two, three, and four. Switches one and two are open and switches three and four are closed, which is called the P state. Switches two and three are open and switches one and four are closed, which is called the O state. Switches three and four are open and switches one and two are closed, which is called the N state.

[0050] When a switch transitions from state P to state O, one switch state change is required; when transitioning from state O to state N, one switch state change is required; when transitioning from state P to state N, two switch states change. Calculate the number of switch changes required when transforming any two basic voltage vectors in the optimal vector combination:

[0051] ;

[0052] ;

[0053] ;

[0054] Among them, the three basic voltage vectors are respectively , , Three basic voltage vectors , , The duration of action are respectively , , ;

[0055] In the formula, for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ; Represents the basic voltage vector The count value corresponding to the switching state of the j-th phase bridge arm, where i=1,2,3 represent the three basic voltage vectors, and j=1,2,3 represent phases A, B, and C respectively; when in state P, When in state 0, When it is state N, ;

[0056] Based on the calculation results of the number of switch changes, determine the sequence of vector action and the duration of each action:

[0057] when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , ;

[0058] when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , ;

[0059] when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , .

[0060] The present invention also provides a readable storage medium having a computer program stored thereon, which, when executed, implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles.

[0061] The present invention also provides an electronic device, which includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles.

[0062] The present invention also provides a computer program product comprising a computer program / instruction that, when executed by a processor, implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles.

[0063] The advantages of this invention are:

[0064] (1) In order to solve the problem of poor steady-state performance of traditional single-vector MPCC and the inability to effectively solve the contradiction between neutral point voltage imbalance and common-mode voltage suppression in NPC inverters in high-voltage drive systems of electric vehicles, this invention provides an SVPWM control method for a three-level inverter permanent magnet synchronous motor that is suitable for the main drive system of electric vehicles, can effectively suppress neutral point voltage fluctuations and common-mode voltage, and improves the output current waveform and dynamic response performance.

[0065] (2) Based on the original basic voltage vector, this invention discards the basic voltage vector with a large common-mode voltage, thereby effectively suppressing the common-mode voltage. Effective suppression of the common-mode voltage can reduce the motor bearing current and the high-frequency loss of the motor, thereby improving the life of the electric vehicle drive motor and the reliability of the system.

[0066] (3) Since the basic voltage vector with a large common-mode voltage is discarded, it is impossible to use redundant small vectors for midpoint voltage balancing. This invention is not limited to selecting the three nearest vectors for synthesis, but selects usable basic voltage vectors in the sector where the target voltage (reference voltage vector) is located and adjacent sectors for synthesis, and performs comprehensive evaluation. This can minimize the deviation of the midpoint voltage and significantly solve the problem of balancing the midpoint voltage of the three-level system. The minimization of the midpoint voltage deviation ensures the quality of the inverter's output waveform on the high-voltage side, improves the inverter efficiency, and helps to extend the driving range of electric vehicles. Attached Figure Description

[0067] Figure 1 This is a flowchart of the method of the present invention.

[0068] Figure 2 This is a control principle diagram of the present invention.

[0069] Figure 3 This is the original basic voltage vector diagram.

[0070] Figure 4 This is the new basic voltage vector diagram. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0072] like Figure 1 As shown, an SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles includes the following steps:

[0073] S1. Establish the basic voltage vector diagram and divide it into sectors. Discard the basic voltage vector diagram with larger common-mode voltage to obtain a new basic voltage vector diagram.

[0074] S2, obtain the electrical angle θ(k) and speed ω(k) of the permanent magnet synchronous motor at time k, and convert the three-phase stator current... , , The d-axis and q-axis components of the stator current are obtained through Clark and Park transforms. , .

[0075] S3, reference speed The difference between the current speed ω(k) of the permanent magnet synchronous motor and the input to the outer loop speed PI controller is used to obtain the q-axis reference current of the permanent magnet synchronous motor at time k. Given the d-axis reference current .

[0076] S4. Calculate the reference voltage vector using the deadbeat current predictive control method to obtain the reference voltage vector values ​​on the d and q axes. , By performing an inverse Park transformation, the reference voltage vector values ​​for the α and β axes are obtained. , .

[0077] S5. Determine the sector where the reference voltage vector is located. Based on the new basic voltage vector diagram, select three basic voltage vectors in the sector where the reference voltage vector is located and the two adjacent sectors, determine the corresponding action time to satisfy the reference voltage vector, and select the vector combination with the minimum value function through rolling optimization. Then, determine the action order of the three basic voltage vectors according to the principle of minimizing the total number of switches, and convert it into the switching sequence of the three-level inverter for output.

[0078] Step S1 specifically includes the following:

[0079] S11, Create the basic voltage vector diagram:

[0080] The voltage space vector synthesized from the three-phase voltages in the stator is:

[0081] ;

[0082] In the formula, j is the imaginary part, and U is the voltage space vector. , , These are the three-phase voltages, A, B, and C, respectively.

[0083] Given the DC side voltage of an NPC-type three-level inverter The output voltage of the three-phase bridge arms A, B, and C of the inverter is 0 or Each phase arm of the inverter has four switches, designated as switches 1, 2, 3, and 4. Switch 1 is connected to the positive DC bus, switch 2 is located between the upper clamping diode and the midpoint, switch 3 is located between the lower clamping diode and the midpoint, and switch 4 is connected to the negative DC bus. Opening switches 1 and 2 and closing switches 3 and 4 is designated as state P. In state P, the output voltage of the bridge arm is... Open switches 2 and 3, and close switches 1 and 4 (recorded as state 0). In state 0, the output voltage of the bridge arm is 0. Open switches 3 and 4, and close switches 1 and 2 (recorded as state N). In state N, the output voltage of the bridge arm is... .

[0084] use , , This indicates the switching state of each phase arm of the bridge, and the three-phase voltages A, B, and C. , , Represented as:

[0085] , , ;

[0086] In the formula, , ; This indicates that the switch state of the bridge arm is P. This indicates that the switch state of the bridge arm is N. This indicates that the switch state of the bridge arm is 0.

[0087] Substituting the phase voltage representations into the voltage space vector, we obtain:

[0088] ;

[0089] There are 3×3×3=27 switching states in the three-phase bridge arm. Substituting these 27 switching states into the voltage space vector, we can calculate the direction and magnitude of the corresponding voltage space vector in the stationary coordinate system, thus obtaining the basic voltage vector diagram, as shown below. Figure 3 As shown, the basic voltage vector in the basic voltage vector diagram is denoted as V. There are 27 basic voltage vectors in total. Based on their amplitudes, the basic voltage vectors are divided into four categories: zero vectors (with an amplitude of zero), small vectors (with an amplitude of...), and... ; the vector whose magnitude is Large vector, whose magnitude is .

[0090] S12, divide into sectors:

[0091] The sector is determined by the angle δ between the basic voltage vector and the α axis, and is denoted as follows: First sector, 0 ≤ δ < 60°; Second sector, 60° ≤ δ < 120°; Third sector, 120° ≤ δ < 180°; Fourth sector, 180° ≤ δ < 240°; Fifth sector, 240° ≤ δ < 300°; Sixth sector, 300° ≤ δ < 360°.

[0092] S13, Calculate the common-mode voltage The calculation formula is as follows:

[0093] ;

[0094] Based on the absolute value of the common-mode voltage, it is divided into , , , Four categories, discarding the absolute value of the common-mode voltage. and The corresponding basic voltage vectors, that is, the switching states PPP, NNN, PPO, POP, OPP, NNO, NON, ONN are discarded, leaving 19 basic voltage vectors. Taking the first large sector as an example, the switching states corresponding to the remaining basic voltage vectors in the first large sector are OOO, PNN, POO, PON, OON, PPN.

[0095] The relationship between the absolute value of the common-mode voltage and the fundamental voltage vector is shown in Table 1 below:

[0096] Table 1. Correspondence between the absolute value of common-mode voltage and the fundamental voltage vector

[0097]

[0098] The remaining basic voltage vectors are shown in Table 2:

[0099] Table 2 Remaining Basic Voltage Vector

[0100]

[0101] In Table 2, V[OOO] represents the basic voltage vector corresponding to the switch state OOO.

[0102] S14, Based on the remaining basic voltage vector, establish a new basic voltage vector diagram, such as... Figure 4 As shown.

[0103] Step S4 specifically includes the following:

[0104] S41 employs a deadbeat current predictive control method, calculating the reference voltage vector values ​​for the d and q axes according to the following formula. and :

[0105] ;

[0106] ;

[0107] In the formula, , These are the d-axis and q-axis components of the stator voltage predicted at time k, respectively. , These are the reference current values ​​for the stator current along the d and q axes at time k, respectively. , The d-axis and q-axis inductances of the motor stator windings. Sampling time, For stator resistance, Let k be the motor speed at time k. It is a permanent magnet flux linkage.

[0108] S42, based on the electrical angle θ(k) of the permanent magnet synchronous motor at time k, the reference voltage vector values ​​of the d and q axes are transformed according to the inverse Park transformation formula. , Transformed into reference voltage vector values ​​in the α and β axis coordinate system , .

[0109] Step S5 specifically includes the following:

[0110] S51, by comparing the relationship between the reference voltage vector Uo and the sector boundary, the sector where the reference voltage vector Uo is located is determined.

[0111] ;

[0112] In the formula, Uo is the reference voltage vector. , Let be the components of the reference voltage vector of the permanent magnet synchronous motor at time k along the α and β axes.

[0113] when >0 and At that time, the reference voltage vector is in the first largest sector;

[0114] when >0 and At that time, the reference voltage vector is in the second largest sector;

[0115] when >0 and At that time, the reference voltage vector is in the third largest sector;

[0116] when <0 and At that time, the reference voltage vector is in the fourth largest sector;

[0117] when <0 and At that time, the reference voltage vector is in the fifth major sector;

[0118] when <0 and At that time, the reference voltage vector is in the sixth sector.

[0119] S52, using the volt-second balance principle, finds three basic voltage vectors that can synthesize the reference voltage vector Uo in the sector containing the reference voltage vector and the two adjacent sectors, and calculates the duty cycle of each of the three basic voltage vectors. Specifically, the volt-second balance principle is an important concept in physics, especially in circuit analysis and switching power supply design. It refers to the requirement that, in a steady-state inductor, the number of volt-seconds (voltage multiplied by time) during the switch's on-time (current rise phase) must be numerically equal to the number of volt-seconds during the switch's off-time (current fall phase). In this embodiment, the volt-second balance principle is applied to the SVPWM method of a three-level converter based on multi-vector synthesis. The calculation formula is:

[0120] ;

[0121] In the formula, Uo is the reference voltage vector. , , These are the three basic voltage vectors. , , These are the three basic voltage vectors. , , The duration of operation (duty cycle) Let be the sampling time, and we have:

[0122] , ;

[0123] Taking the first major sector as an example, if the reference voltage vector Uo is in the first major sector, then the basic voltage vectors of the first, second, and sixth major sectors are substituted sequentially for calculation, i.e., V[OOO], V[POO], V[PNN], V[PON], V[OON], V[PPN], V[OPN], V[NPN], V[OPO], V[PNP], V[ONO], V[PNO]. During the synthesis of the reference voltage vector Uo, the basic voltage vectors (V[NPN], V[OPO]) located at the sector boundaries are also included in the calculation.

[0124] S53, for vector combinations that have solutions to the above equations, rolling optimization is performed according to the following value function to obtain the vector combination with the minimum value function, i.e., the optimal vector combination:

[0125] ;

[0126] in, Where C is the midpoint voltage, and C is the capacitance of a single DC bus capacitor in a three-level inverter. , , These are the three basic voltage vectors. , , The generated midpoint current, This is the value of the value function.

[0127] The midpoint currents generated by the fundamental voltage vector are shown in Table 3 below:

[0128] Table 3 Midpoint current generated by the basic voltage vector

[0129]

[0130] Among them, the midpoint current generated by the fundamental voltage vectors of zero vector and large vector is... .

[0131] S54, when the switch changes from P state to O state, one switch state needs to be changed; when changing from O state to N state, one switch state needs to be changed; when changing from P state to N state, two switch states need to be changed; according to To obtain the optimal vector combination, the number of switching changes when any two basic voltage vectors are transformed is calculated using the following formula. The order of action of the three basic voltage vectors is determined based on the principle of minimizing the total number of switching changes.

[0132] ;

[0133] ;

[0134] ;

[0135] In the formula, for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ;

[0136] Represents the basic voltage vector The count value corresponding to the switching state of the j-th phase bridge arm, i=1,2,3, j=1,2,3 represent the three phases a, b, and c respectively; when it is in state P When in state 0, When it is state N, .

[0137] Based on the calculation results of the number of switching changes, output the basic voltage vector in the order shown in Table 4:

[0138] Table 4. Sequence of action and duration of each of the three basic voltage vectors

[0139]

[0140] like Figure 2 As shown, the overall process of this invention is as follows: A reference rotational speed is given to the vehicle control unit. , The difference between the current rotational speed ω and the current speed is used by the outer loop speed PI controller to obtain the q-axis reference current. Given the d-axis reference current =0, to achieve maximum torque-to-current ratio control, which is beneficial to the efficiency of electric vehicles; the three-phase stator current of the motor is reduced. , , The dq-axis components are obtained through Clark and Park transformations. and The reference voltage vector values ​​of the d and q axes are calculated using a deadbeat current predictive control method. and Then, the reference voltage vector values ​​of the α and β axes are obtained through inverse Park transformation. and Based on the calculated reference voltage vector value and The system determines the sector in which the reference voltage vector is located, selects a suitable basic voltage vector from the newly established basic voltage vector diagram, performs value function rolling optimization on this vector, selects the optimal vector combination, and finally outputs the switching sequence with the minimum switching loss based on the principle of minimizing the total number of switching operations. This sequence is applied to the NPC type three-level inverter to drive the permanent magnet synchronous motor and improve the energy utilization efficiency of electric vehicles.

[0141] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles, characterized in that, Includes the following steps: S1, establish the basic voltage vector diagram and divide it into sectors. Discard the basic voltage vector diagrams whose common-mode voltage exceeds the set threshold to obtain a new basic voltage vector diagram. S2, obtain the electrical angle θ(k) and speed ω(k) of the permanent magnet synchronous motor at the current time k, and convert the three-phase stator current of the motor. , , The d-axis and q-axis components of the stator current are obtained through Clark and Park transformations. , ; S3, reference speed The difference between the current motor speed ω(k) and the input to the outer loop speed PI controller is used to obtain the q-axis reference current. Given the d-axis reference current ; S4. Calculate the reference voltage vector using the deadbeat current predictive control method to obtain the reference voltage vector values ​​on the d and q axes. , By using the inverse Park transformation, the reference voltage vector values ​​along the α and β axes are obtained. , ; S5. Determine the sector where the reference voltage vector is located. Based on the new basic voltage vector diagram, select three basic voltage vectors in the sector where the reference voltage vector is located and the two adjacent sectors and determine the corresponding action time to satisfy the reference voltage vector. Select the vector combination with the minimum value function as the optimal vector combination through rolling optimization. Then, determine the action order of the three basic voltage vectors in the optimal vector combination according to the principle of minimizing the total number of switching, and convert it into the switching sequence of the three-level inverter for output. In step S5, the three basic voltage vectors that satisfy the reference voltage vector are found in the sector containing the reference voltage vector and the two adjacent sectors using the volt-second balance principle, and their corresponding durations are determined. The calculation formula is as follows: ； In the formula, Uo is the reference voltage vector. , , These are the three basic voltage vectors. , , These are the three basic voltage vectors. , , Duration of action Let be the sampling time, and we have: ， ； Among them, the absolute value of the reference voltage vector ; In step S5, the value function is as follows: ； in, Where C is the midpoint voltage, and C is the capacitance of a single DC bus capacitor in a three-level inverter. , , These are the three basic voltage vectors. , , The generated midpoint current, For the value function value, , , These are the three basic voltage vectors. , , The duration of action.

2. The SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that, Step S1 specifically includes the following: S11, Create the basic voltage vector diagram: The DC-side voltage of the three-level inverter is A three-level inverter has three phase arms, A, B, and C. Each phase arm has four switches, labeled 1, 2, 3, and 4. Opening switches 1 and 2 and closing switches 3 and 4 is called the P state. In the P state, the output voltage of the arm is... Open switches 2 and 3, and close switches 1 and 4 (recorded as state 0). In state 0, the output voltage of the bridge arm is 0. Open switches 3 and 4, and close switches 1 and 2 (recorded as state N). In state N, the output voltage of the bridge arm is... ; use , , This indicates the switching state value of each phase arm of the bridge, and the three-phase voltages A, B, and C. , , Represented as: ， ， ； In the formula, , ; This indicates that the switch state of the bridge arm is P. This indicates that the switch state of the bridge arm is N. This indicates that the switch state of the bridge arm is 0. There are 3×3×3=27 switching states in the three-phase bridge arm. Substituting the 27 switching states into the voltage space vector expression, we can calculate the direction and magnitude of the corresponding voltage space vector in the stationary coordinate system to obtain the basic voltage vector diagram. The basic voltage vector of the basic voltage vector diagram is denoted as V. There are a total of 27 basic voltage vectors. The voltage space vector expression is: ； In the formula, U is the voltage space vector, and j is the imaginary part; S12, divide into sectors: The sector is determined by the angle δ between the basic voltage vector and the α axis, and is denoted as follows: First major sector, 0≤δ<60°; Second major sector, 60°≤δ<120°; Third major sector, 120°≤δ<180°; Fourth major sector, 180°≤δ<240°; Fifth major sector, 240°≤δ<300°; Sixth major sector, 300°≤δ<360°. S13, Calculate the common-mode voltage : ； Based on the absolute value of the common-mode voltage, it is divided into , , , Four categories, discarding the absolute value of the common-mode voltage. and The corresponding basic voltage vector; S14, Based on the remaining basic voltage vector, establish a new basic voltage vector diagram.

3. The SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that, In step S4, a deadbeat current predictive control method is used to calculate the reference voltage vector values ​​on the d and q axes according to the following formula. , : ； ； In the formula, , The d-axis and q-axis inductances of the motor stator windings. Sampling time, For stator resistance, It is a permanent magnet flux linkage.

4. The SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that, In step S5, the method for determining the sector where the reference voltage vector is located is as follows: when >0 and At that time, the reference voltage vector is in the first largest sector; when >0 and At that time, the reference voltage vector is in the second largest sector; when >0 and At that time, the reference voltage vector is in the third largest sector; when <0 and At that time, the reference voltage vector is in the fourth largest sector; when <0 and At that time, the reference voltage vector is in the fifth major sector; when <0 and At that time, the reference voltage vector is in the sixth sector.

5. The SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that, In step S5, the order of action of the three basic voltage vectors in the optimal vector combination is determined based on the principle of minimizing the total number of switching operations, as shown below: A three-level inverter has three phase arms, A, B, and C. Each phase arm has four switches, labeled as switches one, two, three, and four. Switches one and two are open and switches three and four are closed, which is called the P state. Switches two and three are open and switches one and four are closed, which is called the O state. Switches three and four are open and switches one and two are closed, which is called the N state. When a switch changes from the P state to the O state, one switch state must be changed. When transitioning from state 0 to state N, a switch state must be changed; When transitioning from P state to N state, the states of two switches must be changed; Calculate the number of switching changes when transforming any two basic voltage vectors in the optimal vector combination: ； ； ； Among them, the three basic voltage vectors are respectively , , Three basic voltage vectors , , The duration of action are respectively , , ; In the formula, for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ; for The number of switching changes, and Number of switching changes ; Represents the basic voltage vector The count value corresponding to the switching state of the j-th phase bridge arm, where i=1,2,3 represent the three basic voltage vectors, and j=1,2,3 represent phases A, B, and C respectively; when in state P, When in state 0, When it is state N, ; Based on the calculation results of the number of switch changes, determine the sequence of vector action and the duration of each action: when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , ; when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , ; when , At its maximum, the order of vector action is as follows: , , , , The corresponding single-action times are as follows: , , , , .

6. A readable storage medium, characterized in that, It stores a computer program, which, when executed, implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles as described in any one of claims 1 to 5.

7. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles as described in any one of claims 1 to 5.

8. A computer program product, characterized in that, It includes a computer program / instruction that, when executed by a processor, implements the SVPWM control method for a three-level inverter permanent magnet synchronous motor for electric vehicles as described in any one of claims 1 to 5.

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