NVH optimization method for permanent magnet synchronous motor based on frequency adaptive repetitive control

Abstract

The application discloses a permanent magnet synchronous motor NVH optimization method based on frequency adaptive repetitive control, and comprises the following steps: S1, an air gap magnetic field model generated by a permanent magnet and an armature reaction is established; S2, a relationship between a radial electromagnetic force order and a three-phase current harmonic order is derived according to the air gap magnetic field model; S3, a frequency adaptive repetitive control algorithm is used to suppress the harmonic of the dq-axis current; and S4, a joint simulation platform is built to verify the effect. The frequency adaptive repetitive controller and the PI controller are used to suppress the harmonic in the current loop, the harmonic content of the three-phase current of the motor is greatly reduced, and the NVH performance of the motor is improved.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet synchronous motor technology, specifically to a method for optimizing the NVH (noise, vibration, and harshness) of a permanent magnet synchronous motor based on frequency adaptive repetitive control. Background Technology

[0002] Built-in permanent magnet synchronous motors are widely used in electric vehicles. Due to the influence of current harmonics, their radial force composition is complex, making the NVH (noise, vibration, and harshness) problems of the motor increasingly prominent. Radial electromagnetic force acts on the motor stator housing, causing deformation of the stator structure, thereby generating vibration and noise. Moreover, many studies have shown that the lower the order and the larger the amplitude of the radial electromagnetic force, the more significant the impact on the NVH performance of the motor.

[0003] Maximum torque ratio control (MTPA) is a high-performance control method for controlling embedded permanent magnet synchronous motors (PMSMs) and is widely used in electric vehicles. Common MTPA control uses traditional PI control to regulate the current loop. While PI controllers can achieve zero steady-state error tracking of step signals, their error tracking capability for sinusoidal signals is weak, and their ability to suppress current harmonics is poor, thus affecting the motor's NVH performance. Since repetitive control technology can regulate AC signals containing complex components, it can be added to the current loop of the MTPA control strategy to suppress harmonics. However, the performance of traditional repetitive controllers degrades when the ratio of the sampling frequency to the disturbance signal frequency is not an integer, significantly reducing the suppression effect. Therefore, if these problems are not addressed, the vibration and noise issues of embedded PMSMs will persist. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes an NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control. By utilizing a frequency adaptive repetitive controller and a PI controller, harmonics in the current loop are suppressed, significantly reducing the harmonic content of the motor's three-phase current and improving the motor's NVH performance.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for optimizing the NVH (Noise, Vibration, and Harshness) of a permanent magnet synchronous motor based on frequency adaptive repetitive control includes the following steps:

[0007] S1. Establish a model of the air gap magnetic field generated by the permanent magnet and armature reaction;

[0008] S2. Derive the relationship between the order of radial electromagnetic force and the order of three-phase current harmonics based on the air gap magnetic field model;

[0009] S3. Harmonics of the dq-axis current are suppressed by a frequency adaptive repetitive control algorithm;

[0010] S4. Build a joint simulation platform to verify the effect.

[0011] Preferably, in step S2, the method for deriving the relationship between the order of radial electromagnetic force and the harmonic order of the three-phase current is as follows: the mathematical relationship between radial electromagnetic force, three-phase current and dq-axis current is obtained through Maxwell's tensor equation and coordinate transformation.

[0012] Preferably, step S2 includes the following sub-steps:

[0013] S2-1. According to Maxwell's tensor equations, the radial electromagnetic force P is obtained. r Its expression is as follows:

[0014]

[0015] Because of B r >>B t It can be simplified to B r Let μ0 be the radial air gap magnetic flux density, μ0 be the free permeability, and B be the radial air gap magnetic flux density. r The radial air gap magnetic flux density generated by the permanent magnet and the radial air gap magnetic flux density generated by the armature reaction are multiplied by the air gap ratio permeability.

[0016] S2-2, Further analysis yields the relationship between the radial electromagnetic force frequency and the current harmonics.

[0017] The Clark transformation matrix is

[0018]

[0019] Three-phase current i a i b i c The current i in the two-phase stationary coordinate system can be obtained through the Clark transformation. α and i β The Park transformation matrix is

[0020]

[0021] i α and i β The d-axis current i in the two-phase rotating coordinate system is obtained through the Park transformation. d and q-axis current i q The relationship between the harmonic orders of the three-phase current and the harmonic orders of the dq-axis current was obtained.

[0022] Preferably, in step S2-2, the three-phase current i a i b i cThe current i in the two-phase stationary coordinate system can be obtained through the Clark transformation. α and i β The expression is as follows:

[0023]

[0024] Preferably, in step S2-2, i α and i β The d-axis current i in the two-phase rotating coordinate system is obtained through the Park transformation. d and q-axis current i q The expression is as follows:

[0025]

[0026] Preferably, in step S3, the frequency adaptive repetitive control algorithm is as follows:

[0027] The transfer function of the frequency adaptive repetitive controller is expressed as follows:

[0028]

[0029] In the formula, K rc It is the gain of the repetitive controller, and Q(s) is a novel FIR filter. For the delay element, T s For the sampling period, G f (s) is a compensator to ensure stability;

[0030] Interference current i d(h) To output i d The transfer function is:

[0031]

[0032] In the formula, G0(s) is the interference current i without a repetitive controller. d(h) To output i d The transfer function;

[0033] According to the small gain theorem, the condition for the system to be stable is:

[0034]

[0035] Further calculations yielded G. f The transfer function of (s).

[0036] Preferably, the co-simulation platform is Matlab / Simulink, Maxwell, and Simplier.

[0037] This invention has the following characteristics and beneficial effects:

[0038] 1. Because the stator current of a permanent magnet synchronous motor contains a large number of harmonics, which are closely related to the radial electromagnetic force, the permanent magnet synchronous motor generates significant vibration and noise. An improved control strategy is proposed, which uses a repetitive controller and a PI controller in parallel to replace the traditional PI controller in the maximum torque-to-current ratio control current loop to suppress harmonic currents. This invention's frequency-adaptive repetitive control method offers excellent control performance and is easily implemented in engineering. It not only improves the harmonic suppression capability of the permanent magnet synchronous motor, achieving the goal of improving the motor's NVH performance, but also increases the system's robustness through frequency adaptation, resulting in superior maximum torque-to-current ratio control performance for the built-in permanent magnet synchronous motor.

[0039] 2. This invention provides a joint simulation platform of Simulink, Maxwell and Simplier. The control algorithm is built in Simulink, the finite element model of the motor is provided by Maxwell, and the SVPWM module is provided by Simplier. This can not only improve the accuracy of the simulation and make the simulation results more reliable, but also analyze the radial electromagnetic force of the motor. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a flowchart illustrating a specific embodiment of the present invention.

[0042] Figure 2 This is a general structural block diagram of a specific embodiment of the present invention.

[0043] Figure 3 This is a block diagram of the co-simulation structure of a specific embodiment of the present invention.

[0044] Figure 4 This is a block diagram of the repeater controller according to a specific embodiment of the present invention.

[0045] In the diagram, 1-PI control module; 2-MTPA lookup table module; 3-d-axis PI control module; 4-q-axis PI control module; 5-d-axis repetitive controller module; 6-q-axis repetitive controller module; 7-2r / 2s coordinate transformation module; 8-SVPWM module; 9-inverter module; 10-built-in permanent magnet synchronous motor; 11-3s / 2r coordinate transformation module. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0047] This invention provides an NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control, such as... Figure 1 As shown, it includes the following steps:

[0048] S1. Establish a model of the air gap magnetic field generated by the permanent magnet and armature reaction.

[0049] S2. Based on the air gap magnetic field model, derive the relationship between the order of radial electromagnetic force and the order of harmonics of three-phase current. Specifically, the method for deriving the relationship between the order of radial electromagnetic force and the order of harmonics of three-phase current is as follows: obtain the mathematical relationship between radial electromagnetic force, three-phase current and dq-axis current through Maxwell's tensor equation and coordinate transformation.

[0050] Includes the following sub-steps:

[0051] S2-1. According to Maxwell's tensor equations, the radial electromagnetic force P is obtained. r Its expression is as follows:

[0052]

[0053] Because of B r ≥B t It can be simplified to B r Let μ0 be the radial air gap magnetic flux density, μ0 be the free permeability, and B be the radial air gap magnetic flux density. r The radial air gap magnetic flux density generated by the permanent magnet and the radial air gap magnetic flux density generated by the armature reaction are multiplied by the air gap ratio permeability.

[0054] S2-2, Further analysis yields the relationship between the radial electromagnetic force frequency and the current harmonics.

[0055] The Clark transformation matrix is

[0056]

[0057] Three-phase current i a i b i c The current i in the two-phase stationary coordinate system can be obtained through the Clark transformation. α and i β Current i α and i β The expression is as follows:

[0058]

[0059] The Park transformation matrix is

[0060]

[0061] i α and i β The d-axis current i in the two-phase rotating coordinate system is obtained through the Park transformation. d and q-axis current i q The relationship between the harmonic orders of the three-phase current and the harmonic orders of the dq-axis current was obtained.

[0062] Wherein, the d-axis current i d and q-axis current i q The expression is as follows:

[0063]

[0064] S3. Harmonics of the dq-axis current are suppressed by a frequency adaptive repetitive control algorithm;

[0065] Specifically, such as Figure 4 As shown, in step S3, the frequency adaptive repetitive control algorithm is as follows:

[0066] The transfer function of the frequency adaptive repetitive controller is expressed as follows:

[0067]

[0068] In the formula, K rc It is the gain of the repetitive controller, and Q(s) is a novel FIR filter. For the delay element, T s For the sampling period, G f (s) is a compensator to ensure stability;

[0069] Understandably, when Q(s) is a standard low-pass filter, the controller's internal model will deviate from the ideal internal model, leading to N... i Even when the value is an integer, it will reduce the performance of the repetitive controller. Therefore, this invention selects Q(s) as a novel FIR filter, which can approximate the fractional delay stage in the mid-frequency band, making the controller's internal model closer to the ideal internal model.

[0070] floor() is the floor function. f is the sampling frequency. a For harmonic frequencies, N i It is an integer less than N.

[0071] Interference current i d(h) To output i d The transfer function is:

[0072]

[0073] In the formula, G0(s) is the interference current i without a repetitive controller. d(h) To output i d The transfer function;

[0074] It should be noted that the interference current i d(h) The harmonic current in the current loop is inherent to the system.

[0075] Understandable.

[0076]

[0077] In the formula, G pi (s) is the transfer function of the PI controller, G p (s) is the transfer function of the controlled object.

[0078] According to the voltage equation:

[0079]

[0080] The stator voltage equation in the rotating coordinate system is obtained through coordinate transformation:

[0081] u d =R s i d +pψ d -ω r ψ q

[0082] u q =R s i q +pψ q +ω r ψ d

[0083] p is the differential operator, ω r R is the electric angular velocity. s For stator resistance, ψ d ψ q Let dq be the flux linkage, and its equation is:

[0084] ψ d =L d i d +ψ f

[0085] ψ q =L q i q

[0086] Consider ψ f If the formula remains constant, rearranging it yields the following formula:

[0087]

[0088]

[0089] Thus, G was obtained. p (s). From Figure 1 As can be seen, Q1 is the d-axis coupling term, and Q2 is the q-axis coupling term. According to the small gain theorem, the stability condition of this system can be obtained as follows:

[0090]

[0091] Further calculations yielded G. f The transfer function of (s).

[0092] S4. Build a co-simulation platform to verify the effect. The co-simulation platform is Matlab / Simulink, Maxwell and Simplier.

[0093] Specifically, such as Figure 3 As shown, the voltage signal output by the inverter passes through the inductor (L... a L b L c ), resistance (R) a R b R c The inputs of the current measurement modules (AM1, AM2, AM3) are sent to the three-phase voltage ports of the motor.

[0094] The motor is a two-dimensional finite element model designed in Maxwell and imported through Simplier. The three-phase output terminals of the motor are short-circuited to form a neutral point.

[0095] Torque measurement, speed measurement, inertia, and load components were added to the MotionSetup_in and MotionSetup_out loops of the motor model. Finally, the harmonic order of the air gap radial electromagnetic force was analyzed in Maxwell software.

[0096] Further, in conjunction with the above technical solutions, a detailed explanation of step S3 and the simulation process in this embodiment will be provided:

[0097] like Figure 2 As shown, PI control module 1 takes the given speed n as input. * The difference Δn between the measured rotational speed n and the measured rotational speed n is output as the given torque T. * The output includes upper and lower limit reference motor parameters. The MTPA lookup table module 2 uses the given torque T... * Get the given current i d * and i q* Given current i d * and the feedback current i d The difference is the input of the d-axis current loop; given current i q * and the feedback current i q The difference is the input of the q-axis current loop.

[0098] The FIR filter, delay circuit, and compensator of the repetitive controller are obtained based on parameters such as motor speed, system sampling frequency, and motor dq axis inductance and resistance.

[0099] The input of the d-axis current loop is obtained through a parallel controller of the respective d-axis repetitive controller module 5 and the d-axis PI adjustment module 3. d * The input of the q-axis current loop is obtained through a parallel controller of its respective q-axis repetitive controller module 6 and q-axis PI adjustment module 4. q * The d-axis PI adjustment module 3 and the q-axis PI adjustment module 4 adjust the corresponding DC signals, while the repeater controller adjusts the AC signals.

[0100] dq axis voltage vector u d * and u q * u is obtained after 2r / 2s coordinate transformation module 7 α * and u β * This signal is then input to the SVPWM module 8 to obtain the PWM control signal, which in turn controls the on / off state of the inverter module 9. Three-phase current i a i b i c The d-axis feedback current and q-axis feedback current are obtained through the 3s / 2r coordinate transformation module 11.

[0101] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments, including components, without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for optimizing the NVH (Noise, Vibration, and Harshness) of a permanent magnet synchronous motor based on frequency adaptive repetitive control, characterized in that, Includes the following steps: S1. Establish a model of the air gap magnetic field generated by the permanent magnet and armature reaction; S2. Derive the relationship between the order of radial electromagnetic force and the harmonic order of three-phase current based on the air gap magnetic field model. The method for deriving the relationship between the order of radial electromagnetic force and the harmonic order of three-phase current is as follows: obtain the mathematical relationship between radial electromagnetic force, three-phase current and dq-axis current through Maxwell's tensor equation and coordinate transformation. Includes the following sub-steps: S2-1. According to Maxwell's tensor equations, the radial electromagnetic force P is obtained. r Its expression is as follows: Because of B r >>B t It can be simplified to B r Let μ0 be the radial air gap magnetic flux density, μ0 be the free permeability, and B be the radial air gap magnetic flux density. r The radial air gap magnetic flux density generated by the permanent magnet and the radial air gap magnetic flux density generated by the armature reaction are multiplied by the air gap ratio permeability. S2-2, Further analysis yields the relationship between the radial electromagnetic force frequency and the current harmonics. The Clark transformation matrix is Three-phase current i a i b i c The current i in the two-phase stationary coordinate system can be obtained through the Clark transformation. α and i β , The Park transformation matrix is i α and i β The d-axis current i in the two-phase rotating coordinate system is obtained through the Park transformation. d and q-axis current i q The relationship between the harmonic order of the three-phase current and the harmonic order of the dq-axis current was obtained. S3. Harmonics in the dq-axis current are suppressed using a frequency-adaptive repetitive control algorithm. The transfer function of the frequency-adaptive repetitive control algorithm is expressed as follows: In the formula, K rc It is the gain of the repetitive controller, and Q(s) is a novel FIR filter. For the delay element, T s For the sampling period, G f (s) is a compensator to ensure stability; S4. Build a joint simulation platform to verify the effect.

2. The NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control according to claim 1, characterized in that, In step S2-2, the three-phase current i a i b i c The current i in the two-phase stationary coordinate system can be obtained through the Clark transformation. α and i β The expression is as follows:

3. The NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control according to claim 2, characterized in that, In step S2-2, i α and i β The d-axis current i in the two-phase rotating coordinate system is obtained through the Park transformation. d and q-axis current i q The expression is as follows:

4. The NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control according to claim 1, 2, or 3, characterized in that, In step S3, the interference current i d(h) To output i d The transfer function is: In the formula, G0(s) is the interference current i without a repetitive controller. d(h) To output i d The transfer function; According to the small gain theorem, the stability condition of the frequency adaptive repetitive control algorithm can be obtained as follows: Further calculations yielded G. f The transfer function of (s).

5. The NVH optimization method for permanent magnet synchronous motors based on frequency adaptive repetitive control according to claim 1, characterized in that, The co-simulation platform is Matlab / Simulink, Maxwell, and Simplier.

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