LC filtering type permanent magnet motor optimal vector sequence prediction control method and system

Abstract

The invention discloses an LC filtering type permanent magnet motor optimal vector sequence prediction control method and system, and belongs to the field of motor control. Firstly, a symmetric optimal vector sequence is defined in a space vector sector, so that the switching frequency of a system is fixed, and a filter inductive current trajectory prediction model is established by means of a system gradient equation. Through system steady-state working point analysis, an inductive current reference value is deduced, and a capacitive current component is introduced to correct the inductive current reference value, so that the resonance suppression effect of a filter capacitor series resistor is simulated. And determining an optimal sector and sequence according to an inductive current one-beat tracking principle, and designing a sectional tracking error value function to realize system harmonic wave minimization. And solving the action time of each vector through a minimum principle, and converting the action time into an inverter switching signal to realize the overall control of the system. According to the invention, the resonance problem of a high-order system is effectively solved, the switching frequency is constant, and the steady-state performance of the system is improved.

Description

Technical Field

[0001] The invention relates to an LC filter type permanent magnet motor optimal vector sequence prediction control and system, belonging to the field of motor control. Background Art

[0002] Permanent magnet motors are widely used in electric drive fields such as electric vehicles due to their simple structure, high power density and high efficiency. However, the commonly used pulse width modulation technology will produce high dv / dt, which will cause common mode voltage interference and overvoltage on the motor side. With the rapid development of wide bandgap semiconductors, traditional silicon-based (S i ) semiconductor devices are gradually replaced by silicon carbide (S i C) and gallium nitride (G a N), etc., which significantly increases the switching frequency of the system, making the above problems more serious. Therefore, filters are usually installed on the output side of the inverter. Among them, LC filters have received widespread attention because they require small inductance and are low in cost. They can filter the square wave signal output by the inverter into a nearly sinusoidal signal to power the motor side, significantly reducing the impact of dv / dt and system harmonics. However, the LC filter and the stator inductance of the subsequent motor form an LCL third-order system, which introduces resonance problems and threatens the stability of the electric drive system.

[0003] For LC filter type permanent magnet motor drive system, the traditional field oriented control method is no longer applicable. It is often controlled by multi-loop cascading of linear controllers or adding damping outer loops, which makes the overall control parameter design of the system complicated and limits the dynamic response of the system. Predictive control has been widely used in various industrial fields because of its simple control principle, simple parameter design, fast dynamic response and the advantages of multivariable control. Therefore, the design of LC filter type permanent magnet motor drive system based on predictive control is considered to be a very promising solution. Summary of the invention

[0004] In view of the shortcomings of the existing control technology, the present invention provides an LC filter type permanent magnet motor optimal vector sequence predictive control and system. The algorithm first defines a symmetrical optimal vector sequence for each space vector sector according to the harmonic minimization principle, and establishes an inductor current prediction model based on trajectory tracking in combination with the gradient equation of the system. By analyzing the steady-state operating point of the system, the inductor current reference value is derived, and the capacitor current component is introduced for correction to simulate the resonance suppression effect of the filter capacitor series resistance. Subsequently, the optimal sector and vector sequence are determined by the one-beat tracking principle of the inductor current, and a segmented tracking error value function is designed. The action time of each vector is solved by the error minimization principle, and it is converted into a switching signal of the inverter to achieve overall control of the system. Compared with traditional predictive control, the present invention not only effectively solves the resonance problem of high-order systems, but also achieves a constant switching frequency and improves the steady-state performance of the system.

[0005] In order to achieve the above control objectives, the present invention provides an LC filter type permanent magnet motor optimal vector sequence predictive control and system, comprising the following steps:

[0006] Step 1: For different space vector sectors of the three-phase two-level voltage source inverter, a symmetrical optimal vector sequence is defined to make the switching frequency of the system fixed;

[0007] Step 2: Based on the symmetrical optimal vector sequence idea in step 1 and the gradient equation of the LC filter permanent magnet motor system, an inductor current trajectory prediction model is established;

[0008] Step 3: Based on the steady-state operating point of the system, the permanent magnet motor stator current reference i s * Converted into the inductor current reference i L * , and use the capacitor current component to correct it, and get the inductor current reference i with resonance suppression component L_AD * , in order to simulate the working condition of the filter capacitor in series with the resistor, and realize the system resonance suppression;

[0009] Step 4: Based on the inductor current reference value i with resonance suppression component derived in step 3 L_AD * , using the one-shot tracking control principle, the optimal voltage reference of the inverter based on the dq axis synchronous rotating coordinate system is solved: id * and v iq * ;

[0010] Step 5: Based on the inverter optimal voltage reference in the dq-axis synchronous rotating coordinate system obtained in step 4, perform Park inverse transformation on it to obtain the inverter optimal voltage reference based on the α-β stationary coordinate system: v iα * and v iβ * , and then use the inverse tangent function to get the angle of the optimal voltage reference for sector judgment, so as to determine the optimal vector sequence in the current control cycle;

[0011] Step 6: Based on the optimal vector sequence selected in step 5, a piecewise tracking error value function G(t1, t2) is designed to minimize the system harmonics, and the action time of each voltage vector is solved using the minimum principle;

[0012] Step 7: According to the voltage vector action time obtained in step 6, it is converted into a corresponding switching signal and acts on the inverter switch tube, thereby realizing an optimal vector sequence predictive control of an LC filter type permanent magnet motor.

[0013] Furthermore, in the above step 1, a symmetrical optimal vector sequence is defined for different space vector sectors, and each sequence consists of two valid vectors and one zero vector, thereby achieving the fixation of the system switching frequency. The vector sequences corresponding to each space sector are respectively expressed as: SS1 = [01277210], SS2 = [03277320], SS3 = [03477430], SS4 = [05477540], SS5 = [05677650], SS6 = [01677610]. Among them, the subscript numbers 1-6 correspond to the number of each sector, and the numbers 0-7 contained in each sequence respectively represent the numbers corresponding to the eight basic voltage vectors: v0, v1, v2, v3, v4, v5, v6, v7.

[0014] Furthermore, the inductor current gradient equation of the LC filter permanent magnet motor system in the above step 2 based on the dq axis synchronous rotating coordinate system is expressed as:

[0015]

[0016] Where n represents the voltage vector type corresponding to the vector sequence, n=0 represents the zero vector, and n=1 and n=2 represent the other two valid vectors respectively. f , R f is the filter inductance value and its corresponding parasitic resistance value, i Ld (k), i Lq (k), v fd (k), v fq (k) is the sampling value of the inductor current and capacitor voltage in the dq axis synchronous rotating coordinate system at time k.id,n (k) and v iq,n (k) is the magnitude of the corresponding voltage vector in the dq axis synchronous rotating coordinate system at time k. e (k) is the electrical angular velocity of the permanent magnet motor at time k. Based on the above equation, the inductor current trajectory prediction model can be established:

[0017]

[0018] Where t0, t1 and t2 represent the action time of the zero vector, the first effective vector and the second effective vector in the symmetrical vector sequence in half a switching cycle, respectively. Represents the predicted value of the inductor current at time k+1.

[0019] Furthermore, the inductor current reference value obtained in the above step 3 is derived from the stator current reference value of the permanent magnet motor based on the state equation of the system under the condition of a steady-state operating point:

[0020]

[0021] Then, the inductor current reference is corrected using the capacitor current component to simulate the working condition of the filter capacitor in series with the resistor to achieve the suppression of system resonance. Therefore, the inductor current reference expression with the resonance suppression component is as follows:

[0022]

[0023] Where i cd (k) and i cq (k) is the sampling value of the capacitor current in the dq axis synchronous rotating coordinate system at time k, which can be obtained by making a difference between the inductor current and the stator current, that is, i cd,q =i Ld,q -i sd,q . K v is the capacitance current correction factor, C f is the capacitance value of the filter capacitor of the LC filter, T s is the time for one control cycle.

[0024] Furthermore, the inductor current reference value with resonance suppression component obtained after correction in step 3 adopts the one-shot tracking control principle, and the inverter optimal voltage reference v at time k based on the dq axis synchronous rotating coordinate system in step 4 can be obtained. id * and v iq * :

[0025]

[0026] Furthermore, according to the inverter optimal voltage reference in the dq-axis synchronous rotating coordinate system obtained in step 4, the inverter optimal voltage reference in the α-β stationary coordinate system can be obtained by performing Park inverse transformation: iα * and v iβ * , and then use the inverse tangent function to get the optimal voltage reference angle for sector judgment, so as to determine the optimal vector sequence in the current control cycle.

[0027] Further, according to the inductor current trajectory prediction model established in step 2 and the optimal vector sequence determined in step 5, a piecewise tracking error cost function described in step 6 can be designed:

[0028]

[0029] Where f Ld,0 =f Ld,3 =f Ld,4 =f Ld,7 , f Ld,1 =f Ld,6 , f Ld,2 =f Ld,5 The gradient relationship of the q-axis component is the same; and the vector action time relationship also satisfies: t0=t3=t4=t7, t1=t6, t2=t5.

[0030] On this basis, the minimum principle is used to solve the action times t0, t1 and t2 of the three basic voltage vectors in the optimal vector sequence within half a control cycle:

[0031]

[0032] An LC filter type permanent magnet motor optimal vector sequence prediction control method and system, characterized in that it comprises six modules connected in sequence, namely an inductor current trajectory prediction module, an inductor current reference correction module, an inverter optimal voltage reference generation module, an optimal vector sequence selection module, a time calculation module and a switch signal module. The inductor current trajectory prediction module uses the inductor current value, the capacitor voltage value and the permanent magnet motor electrical angular velocity in the dq axis synchronous rotating coordinate system at time k to calculate the inductor current gradient expression and the inductor current trajectory prediction model; the inductor current reference correction module uses the steady-state operating point of the system to convert the permanent magnet motor stator current reference into the inductor current reference, and corrects it through the capacitor current component, thereby simulating the working condition of the filter capacitor series resistance to achieve system resonance suppression; the inverter optimal voltage reference generation module uses the one-beat tracking control principle to convert the inductor current reference with the resonance suppression component into the inverter optimal voltage reference of the desired output; The optimal vector sequence selection module converts the inverter's optimal voltage reference to the α-β stationary coordinate system through Park's inverse transformation, and uses the inverse tangent function to obtain the angle of the optimal voltage reference for sector judgment, thereby selecting the optimal vector sequence in the current control cycle; the time calculation module constructs a piecewise tracking error value function based on the obtained optimal vector sequence, and uses the minimum principle to calculate the corresponding action time of the three basic voltage vectors in the selected sequence within half a control cycle; finally, the action time of each vector is input into the switch signal module, and the generated switch signal is used to control the six switch tubes of the inverter, thereby realizing efficient control of the inverter.

[0033] An inductor current trajectory prediction module, used to generate an inductor current trajectory prediction value at time k+1;

[0034] An inductor current reference correction module, for outputting an inductor current reference with a resonance suppression component;

[0035] An inverter optimal voltage reference generation module, used for outputting the inverter optimal voltage reference within the control cycle;

[0036] The optimal vector sequence selection module is used to determine the sector where the optimal voltage reference of the inverter is located, so as to select the optimal vector sequence in the current control cycle;

[0037] A time calculation module, used to calculate the action time corresponding to the three basic voltage vectors included in the selected optimal vector sequence in half a control cycle;

[0038] The switch signal module is used to convert the action time of the basic voltage vector into a corresponding switch signal, thereby controlling the six switch tubes of the inverter.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The method provided by the present invention defines a symmetrical optimal vector sequence to fix the system switching frequency, and designs a piecewise tracking error value function based on the inductor current trajectory prediction model to achieve minimization of system harmonics.

[0041] 2. The method provided by the present invention corrects the inductor current reference value by means of the capacitor current component, simulates the resonance suppression effect of the filter capacitor series resistor, and solves the system resonance problem.

[0042] 3. The optimal vector sequence is determined by calculating the optimal voltage reference of the inverter through one-shot tracking control, which reduces the computational complexity and makes it suitable for practical engineering applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the control system structure corresponding to the method provided by the present invention;

[0044] Figure 2 The system outputs key variable waveforms for LC filter permanent magnet motors under different given speed references and loading conditions;

[0045] Figure 3 The present invention provides a schematic diagram of the steady-state waveform and harmonic spectrum of the three-phase stator current under the method. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0047] Figure 1 The schematic diagram of the control system structure corresponding to the method of the present invention is shown in FIG. The DC voltage is converted into an AC square wave voltage signal by a three-phase two-level voltage source inverter, and then filtered into an approximate AC sine wave by an LC filter to power the permanent magnet motor; the state variables of the system are sampled by a sampling module, including the three-phase inductor current of the LC filter, the three-phase capacitor voltage, the three-phase stator current of the permanent magnet motor, and the angular velocity ω. r The outer loop of the system uses a proportional-integral controller to control the motor speed, and the stator current reference generated by the controller is sent to the inner loop of the current, that is, the optimal vector sequence prediction controller designed by the present invention.

[0048] Figure 1 In, V dc Indicates the DC bus voltage; L f , C f Represents the filter inductance and capacitance of the LC filter; i L,abc 、v f,abc and i s,abcrepresents the three-phase inductor current, capacitor voltage and permanent magnet motor three-phase stator current; θ and θ e Respectively represent the mechanical angle and electrical angle of the permanent magnet motor rotor; P N Represents the number of pole pairs of the permanent magnet motor; ω r * Indicates the set motor angular velocity reference; ω r Represents the actual angular velocity of the permanent magnet motor obtained by the encoder; i sd * is the d-axis reference current; i sq * is the q-axis reference current; d / dt represents the differential link; i Ld (k), i Lq (k), v fd (k), v fq (k), i sd (k) and i sq (k) respectively represent the LC filter inductor current, capacitor voltage and permanent magnet motor stator current based on the dq axis synchronous rotating coordinate system obtained by sampling and Park transformation at time k; i L p (k+1) represents the predicted value of the inductor current at time k+1 obtained by the inductor current trajectory prediction model; i L_AD * represents the inductor current reference with resonance suppression component; v i * represents the optimal voltage reference of the inverter in the dq-axis synchronous rotating coordinate system obtained by one-shot tracking control of the inductor current; v0, v1 and v2 respectively represent the three basic voltage vectors in the selected optimal vector sequence; t0, t1 and t2 respectively represent the corresponding action time of the three selected basic voltage vectors v0, v1 and v2 in half a control cycle; S abc Indicates the switch status corresponding to each bridge arm of the three-phase inverter.

[0049] An LC filter type permanent magnet motor optimal vector sequence prediction control and system, characterized in that it comprises six modules connected in sequence, namely an inductor current trajectory prediction module, an inductor current reference correction module, an inverter optimal voltage reference generation module, an optimal vector sequence selection module, a time calculation module and a switch signal module. The inductor current trajectory prediction module uses the inductor current value, the capacitor voltage value and the permanent magnet motor electrical angular velocity in the dq axis synchronous rotating coordinate system at time k to calculate the inductor current gradient expression and the inductor current trajectory prediction model; the inductor current reference correction module uses the steady-state operating point of the system to convert the permanent magnet motor stator current reference into the inductor current reference, and corrects it through the capacitor current component, thereby simulating the working condition of the filter capacitor series resistance to achieve system resonance suppression; the inverter optimal voltage reference generation module uses the one-beat tracking control principle to convert the inductor current reference with the resonance suppression component into the inverter optimal voltage reference of the desired output; The optimal vector sequence selection module converts the inverter's optimal voltage reference to the α-β stationary coordinate system through Park's inverse transformation, and uses the inverse tangent function to obtain the angle of the optimal voltage reference for sector judgment, thereby selecting the optimal vector sequence in the current control cycle; the time calculation module constructs a piecewise tracking error value function based on the obtained optimal vector sequence, and uses the minimum principle to calculate the corresponding action time of the three basic voltage vectors in the selected sequence within half a control cycle; finally, the action time of each vector is input into the switch signal module, and the generated switch signal is used to control the six switch tubes of the inverter, thereby realizing efficient control of the inverter.

[0050] An inductor current trajectory prediction module, used to generate an inductor current trajectory prediction value at time k+1;

[0051] An inductor current reference correction module, for outputting an inductor current reference with a resonance suppression component;

[0052] An inverter optimal voltage reference generation module, used for outputting the inverter optimal voltage reference within the control cycle;

[0053] The optimal vector sequence selection module is used to determine the sector where the optimal voltage reference of the inverter is located, so as to select the optimal vector sequence in the current control cycle;

[0054] A time calculation module, used to calculate the action time corresponding to the three basic voltage vectors included in the selected optimal vector sequence in half a control cycle;

[0055] The switch signal module is used to convert the action time of the basic voltage vector into a corresponding switch signal, thereby controlling the six switch tubes of the inverter.

[0056] An LC filter type permanent magnet motor optimal vector sequence prediction control and system, comprising the following steps:

[0057] Step 1: For different space vector sectors, a symmetrical optimal vector sequence is defined. Each sequence consists of two valid vectors and one zero vector, thereby achieving the fixed switching frequency of the system. The vector sequences corresponding to each space sector are expressed as: SS1 = [01277210], SS2 = [03277320], SS3 = [03477430], SS4 = [05477540], SS5 = [05677650], SS6 = [01677610]. Among them, the subscript numbers 1-6 correspond to the number of each sector, and the numbers 0-7 contained in each sequence represent the numbers corresponding to the eight basic voltage vectors: v0, v1, v2, v3, v4, v5, v6, v7.

[0058] Step 2: The inductor current gradient equation of the LC filter permanent magnet motor system based on the dq axis synchronous rotating coordinate system is expressed as:

[0059]

[0060] Where n represents the voltage vector type corresponding to the vector sequence, n=0 represents the zero vector, and n=1 and n=2 represent the other two valid vectors respectively. f , R f is the filter inductance value and its corresponding parasitic resistance value, i Ld (k), i Lq (k), v fd (k), v fq (k) is the sampling value of the inductor current and capacitor voltage in the dq axis synchronous rotating coordinate system at time k. id,n (k) and v iq,n (k) is the magnitude of the corresponding voltage vector in the dq axis synchronous rotating coordinate system at time k. e (k) is the electrical angular velocity of the permanent magnet motor at time k. Based on the above equation, the inductor current trajectory prediction model can be established:

[0061]

[0062] Where t0, t1 and t2 represent the action time of the zero vector, the first effective vector and the second effective vector in the symmetrical vector sequence in half a switching cycle, respectively. Represents the predicted value of the inductor current at time k+1.

[0063] Step 3: Based on the state equation of the system and under the steady-state operating point condition, the inductor current reference value is derived from the stator current reference value of the permanent magnet motor:

[0064]

[0065] Then, the inductor current reference is corrected using the capacitor current component to simulate the working condition of the filter capacitor in series with the resistor to achieve the suppression of system resonance. Therefore, the inductor current reference expression with the resonance suppression component is as follows:

[0066]

[0067] Where i cd (k) and i cq (k) is the sampling value of the capacitor current in the dq axis synchronous rotating coordinate system at time k, which can be obtained by making a difference between the inductor current and the stator current, that is, i cd,q =i Ld,q -i sd,q . K v is the capacitance current correction factor, C f is the capacitance value of the filter capacitor of the LC filter, T s is the time for one control cycle.

[0068] Step 4: Using the one-shot tracking control principle for the inductor current reference value with resonance suppression component obtained in step 3, the optimal inverter voltage reference v at time k based on the dq axis synchronous rotating coordinate system can be obtained. id * and v iq * :

[0069]

[0070] Step 5: Based on the inverter optimal voltage reference in the dq-axis synchronous rotating coordinate system obtained in step 4, perform Park inverse transformation on it to obtain the inverter optimal voltage reference based on the α-β stationary coordinate system: v iα * and v iβ * , and then use the inverse tangent function to get the optimal voltage reference angle for sector judgment, so as to determine the optimal vector sequence in the current control cycle.

[0071] Step 6: Based on the inductor current trajectory prediction model established in step 2 and the optimal vector sequence determined in step 5, a piecewise tracking error cost function described in step 6 can be designed:

[0072]

[0073] Where f Ld,0 =f Ld,3 =f Ld,4 =f Ld,7 , f Ld,1 =f Ld,6 , fLd,2 =f Ld,5 The gradient relationship of the q-axis component is the same; and the vector action time relationship also satisfies: t0=t3=t4=t7, t1=t6, t2=t5.

[0074] On this basis, the minimum principle is used to solve the action times t0, t1 and t2 of the three basic voltage vectors in the optimal vector sequence within half a control cycle:

[0075]

[0076] Step 7: According to the voltage vector action time obtained in step 6, it is converted into a corresponding switching signal and acts on the inverter switch tube, thereby realizing an optimal vector sequence predictive control of an LC filter type permanent magnet motor.

[0077] In order to verify the effectiveness of the optimal vector sequence predictive control and system of an LC filter permanent magnet motor provided by the present invention, the method provided by the present invention is applied to a permanent magnet motor drive system with an LC filter. The system parameters are shown in Table 1.

[0078] Table 1

[0079]

[0080] Set the speed reference to:

[0081]

[0082] Set the load torque to:

[0083]

[0084] Figure 2 The control method proposed in this invention is applied to the LC filter type permanent magnet motor drive system, and the corresponding system output key variable waveforms are as follows from top to bottom: motor speed, electromagnetic torque, three-phase stator current, three-phase filter inductor current, and three-phase filter capacitor voltage. Figure 2 It can be seen from the output waveform that the method provided by the present invention can track the stator current of the permanent magnet motor while effectively suppressing the resonance of the system, thereby ensuring that the permanent magnet motor can still maintain stable operation under various speeds and loading conditions.

[0085] Figure 3 The figure is a schematic diagram of the steady-state waveform and harmonic spectrum of the three-phase stator current of the permanent magnet motor corresponding to the control method proposed in the present invention. It can be seen that under the control method provided by the present invention, the steady-state waveform of the three-phase stator current of the permanent magnet motor has high sinusoidality and low total harmonic distortion, which improves the steady-state performance of the entire control system.

Claims

1. An optimal vector sequence predictive control method for an LC filter type permanent magnet motor, characterized in that: The steps include: Step 1: For different space vector sectors of the three-phase two-level voltage source inverter, a symmetrical optimal vector sequence is defined to make the switching frequency of the system fixed; Step 2: Based on the symmetrical optimal vector sequence idea in step 1 and the gradient equation of the LC filter permanent magnet motor system, an inductor current trajectory prediction model is established; Step 3: Based on the steady-state operating point of the system, the permanent magnet motor stator current reference i s * Converted into the inductor current reference i L * , and use the capacitor current component to correct it, and get the inductor current reference i with resonance suppression component L_AD * , in order to simulate the working condition of the filter capacitor in series with the resistor, and realize the system resonance suppression; Step 4: Based on the inductor current reference value i with resonance suppression component derived in step 3 L_AD * , using the one-shot tracking control principle, the optimal voltage reference of the inverter based on the dq axis synchronous rotating coordinate system is solved: id * and v iq * ; Step 5: Based on the inverter optimal voltage reference in the dq-axis synchronous rotating coordinate system obtained in step 4, perform Park inverse transformation on it to obtain the inverter optimal voltage reference based on the α-β stationary coordinate system: v iα * and v iβ * , and then use the inverse tangent function to get the angle of the optimal voltage reference for sector judgment, so as to determine the optimal vector sequence in the current control cycle; Step 6: Based on the optimal vector sequence selected in step 5, a piecewise tracking error value function G(t1, t2) is designed to minimize the system harmonics, and the action time of each voltage vector is solved using the minimum principle; Step 7: According to the voltage vector action time obtained in step 6, it is converted into a corresponding switching signal and acts on the inverter switch tube, thereby realizing an optimal vector sequence predictive control of an LC filter type permanent magnet motor.

2. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 1 is characterized in that: In the step 1, a symmetrical optimal vector sequence is defined for different space vector sectors, each sequence consisting of two valid vectors and one zero vector, thereby achieving the fixation of the system switching frequency; the vector sequences corresponding to each space sector are respectively expressed as: SS1 = [01277210], SS2 = [03277320], SS3 = [03477430], SS4 = [05477540], SS5 = [05677650], SS6 = [01677610]; wherein the subscript numbers 1-6 correspond to the number of each sector, and the numbers 0-7 contained in each sequence respectively represent the numbers corresponding to the eight basic voltage vectors: v0, v1, v2, v3, v4, v5, v6, v7.

3. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 2 is characterized in that: In step 2, the inductor current gradient equation of the LC filter permanent magnet motor system based on the dq axis synchronous rotating coordinate system is expressed as: Where n represents the voltage vector type corresponding to the vector sequence, n = 0 represents the zero vector, n = 1 and n = 2 represent the other two valid vectors respectively; L f , R f is the filter inductance value and its corresponding parasitic resistance value, i Ld (k), i Lq (k), v fd (k), v fq (k) is the sampling value of the inductor current and capacitor voltage in the dq-axis synchronous rotating coordinate system at time k; v id,n (k) and v iq,n (k) is the magnitude of the corresponding voltage vector in the dq-axis synchronous rotating coordinate system at time k; ω e (k) is the electrical angular velocity of the permanent magnet motor at time k; Based on the above equation, the inductor current trajectory prediction model can be established: Where t0, t1 and t2 represent the action time of the zero vector, the first effective vector and the second effective vector in the symmetrical vector sequence in half a switching cycle, respectively. Represents the predicted value of the inductor current at time k+1.

4. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 3 is characterized in that: The inductor current reference value obtained in step 3 is derived from the stator current reference value of the permanent magnet motor based on the state equation of the system under the steady-state operating point condition: Then, the inductor current reference is corrected by using the capacitor current component to simulate the working condition of the filter capacitor in series with the resistor to achieve the suppression of system resonance. Therefore, the inductor current reference expression with the resonance suppression component is as follows: Where i cd (k) and i cq (k) is the sampling value of the capacitor current in the dq axis synchronous rotating coordinate system at time k, which can be obtained by making a difference between the inductor current and the stator current, that is, i cd,q =i Ld,q -i sd,q ; K v is the capacitance current correction factor, C f is the capacitance value of the filter capacitor of the LC filter, T s The time for one control cycle.

5. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 4 is characterized in that: The inductor current reference value with resonance suppression component obtained in step 3 is subjected to one-shot tracking control principle, and the optimal inverter voltage reference v at time k in step 4 based on the dq axis synchronous rotating coordinate system can be obtained. id * and v iq * :

6. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 5, characterized in that: The inverter optimal voltage reference in the dq-axis synchronous rotating coordinate system obtained in step 4 is subjected to Park inverse transformation to obtain the inverter optimal voltage reference in the α-β stationary coordinate system: iα * and v iβ * , and then use the inverse tangent function to get the optimal voltage reference angle for sector judgment, so as to determine the optimal vector sequence in the current control cycle.

7. The optimal vector sequence prediction control method for an LC filter type permanent magnet motor according to claim 6, characterized in that: According to the inductor current trajectory prediction model established in step 2 and the optimal vector sequence determined in step 5, a piecewise tracking error cost function described in step 6 can be designed: Where f Ld,0 =f Ld,3 =f Ld,4 =f Ld,7 , f Ld,1 =f Ld,6 , f Ld,2 =f Ld,5 The gradient relationship of the q-axis component is the same; and the vector action time relationship also satisfies: t0=t3=t4=t7, t1=t6, t2=t5. On this basis, the minimum principle is used to solve the action times t0, t1 and t2 of the three basic voltage vectors in the optimal vector sequence within half a control cycle:

8. The LC filter type permanent magnet motor optimal vector sequence prediction control system according to claim 1, characterized in that: It includes six modules connected in sequence, namely, an inductor current trajectory prediction module, an inductor current reference correction module, an inverter optimal voltage reference generation module, an optimal vector sequence selection module, a time calculation module and a switch signal module; The inductor current trajectory prediction module uses the inductor current value, capacitor voltage value and permanent magnet motor electrical angular velocity in the dq-axis synchronous rotating coordinate system at time k to calculate the inductor current gradient expression and the inductor current trajectory prediction model; the inductor current reference correction module uses the steady-state operating point of the system to convert the permanent magnet motor stator current reference into the inductor current reference, and corrects it through the capacitor current component to simulate the working condition of the filter capacitor series resistance to achieve system resonance suppression; the inverter optimal voltage reference generation module uses the one-beat tracking control principle to convert the inductor current reference with resonance suppression component into the inverter optimal voltage reference of the desired output; The optimal vector sequence selection module converts the inverter's optimal voltage reference to the α-β stationary coordinate system through Park inverse transformation, and uses the inverse tangent function to obtain the angle of the optimal voltage reference for sector judgment, thereby selecting the optimal vector sequence in the current control cycle; the time calculation module constructs a piecewise tracking error value function based on the obtained optimal vector sequence, and uses the minimum value principle to calculate the corresponding action time of the three basic voltage vectors in the selected sequence within half a control cycle; finally, the action time of each vector is input into the switch signal module, and the generated switch signal is used to control the six switch tubes of the inverter, thereby realizing efficient control of the inverter; An inductor current trajectory prediction module, used to generate an inductor current trajectory prediction value at time k+1; An inductor current reference correction module, for outputting an inductor current reference with a resonance suppression component; An inverter optimal voltage reference generation module, used for outputting the inverter optimal voltage reference within the control cycle; The optimal vector sequence selection module is used to determine the sector where the optimal voltage reference of the inverter is located, so as to select the optimal vector sequence in the current control cycle; A time calculation module, used to calculate the action time corresponding to the three basic voltage vectors included in the selected optimal vector sequence in half a control cycle; The switch signal module is used to convert the action time of the basic voltage vector into a corresponding switch signal, thereby controlling the six switch tubes of the inverter.

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