Permanent magnet synchronous motor dead zone compensation method

Abstract

The invention belongs to the technical field of motor control, and particularly relates to a permanent magnet synchronous motor dead zone compensation method. Comprising the following steps: S1, constructing a current loop system open-loop transfer function of the permanent magnet synchronous motor on an axis complex plane; s2, based on the open-loop transfer function of the current loop system, constructing a distortion voltage compensation loop comprising a closed-loop tracking transfer function and a closed-loop disturbance transfer function of the current loop system; s3, configuring an additional item of the closed-loop disturbance transfer function based on a notch principle, and solving an open-loop transfer function of the enhanced resonance controller based on a configuration result of the additional item; and S4, solving respective open-loop transfer functions of the sixth-harmonic enhanced resonance controller and the twelfth-harmonic enhanced resonance controller based on the open-loop transfer function of the enhanced resonance controller, and realizing configuration of a distortion voltage compensation loop. The method is not limited by the current polarity judgment precision of the sensor, and has better compensation precision and harmonic suppression effect.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, and in particular relates to a method for dead-zone compensation of permanent magnet synchronous motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in electric vehicles, aerospace, railway traction, and household appliances due to their high power density and efficiency. In the actual control of PMSMs, a dead time must be set during switching to avoid shoot-through in the inverter's upper and lower switching elements. Dead time directly introduces distorted voltage dominated by the 6th and 12th harmonics, causing a deviation between the actual and ideal output voltage, leading to phase current distortion and torque pulsation. Traditional offline compensation methods are limited by the accuracy of the sensor's current polarity determination and require known parameters of the switching elements. However, the 6th and 12th harmonics interfere with current polarity determination, and the parameters of the switching elements are difficult to measure and change with the system's operating state. These factors all contribute to inaccurate compensation or even miscompensation in offline compensation methods. Summary of the Invention

[0003] In view of this, the present invention aims to provide a dead-zone compensation method for permanent magnet synchronous motors (PMSMs) to solve the problems of existing offline compensation methods being limited by the accuracy of sensor current polarity determination and requiring known parameters of switching elements. The present invention achieves effective compensation for voltage distortion dominated by the 6th and 12th harmonics. Compared with traditional offline compensation methods, the present invention does not require known switching element parameters, is not limited by the accuracy of sensor current polarity determination, and has better compensation accuracy and harmonic suppression effect. The present invention helps to provide a new approach for achieving accurate dead-zone compensation methods for PMSMs.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A method for dead-time compensation of a permanent magnet synchronous motor specifically includes the following steps: S1: In The open-loop transfer function of the current loop system of a permanent magnet synchronous motor is constructed using a complex plane. S2: Based on the open-loop transfer function of the current loop system, construct a distortion voltage compensation loop that includes the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system. S3: Configure additional terms of the closed-loop disturbance transfer function based on the notch filter principle, and solve the open-loop transfer function of the enhanced resonant controller based on the configuration results of the additional terms; The enhanced resonant controller consists of a 6th harmonic enhanced resonant controller and a 12th harmonic enhanced resonant controller connected in parallel; S4: based on the open-loop transfer function of the enhanced resonant controller, the open-loop transfer functions of the 6th harmonic enhanced resonant controller and the 12th harmonic enhanced resonant controller are solved respectively, and the configuration of the distortion voltage compensation loop is realized.

[0005] Further, in step S1, the open-loop transfer function of the current loop system of the permanent magnet synchronous motor : ; wherein, , and are the stator resistance and the stator inductance respectively, is the sampling period of the current loop, is the electrical angular velocity, is a complex variable in the discrete domain, is the imaginary unit.

[0006] Further, in step S2, the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system are: ; wherein, is the closed-loop tracking transfer function, is the closed-loop disturbance transfer function, is the internal model control link, is the open-loop transfer function of the current loop system, is a complex variable in the discrete domain, is the open-loop transfer function of the enhanced resonant controller before correction, is the equivalent link of .

[0007] Further, in step S2, the distortion voltage compensation loop further includes estimating the open-loop transfer function of the current loop system : ; wherein, , and represent the estimated stator resistance and the estimated stator inductance respectively, is the sampling period of the current loop, is the electrical angular velocity.

[0008] Further, in step S3, the additional term of the closed-loop disturbance transfer function is , the additional term is configured as a standard second-order notch filter, and the continuous transfer function of the standard second-order notch filter is: ; wherein, is the Laplace operator, is the center frequency of the filter to be suppressed, is the filter bandwidth, is the open-loop transfer function of the enhanced resonant controller before modification, is the open-loop transfer function of the current loop system.

[0009] Further, in step S4, the open-loop transfer function of the enhanced resonant controller before modification is: ; wherein, and are the stator resistance and the stator inductance, respectively, is the sampling period of the current loop, is the center frequency of the filter to be suppressed, is the filter bandwidth, is a complex variable in the discrete domain, is the open-loop transfer function of the enhanced resonant controller before modification, , is the attenuation factor.

[0010] Further, the open-loop transfer function of the enhanced resonant controller before modification is: ; wherein, is the stator resistance, is the sampling period of the current loop, is the center frequency of the filter to be suppressed, is the filter bandwidth, , is the attenuation factor, is a complex variable in the discrete domain.

[0011] Further, the open-loop transfer function of the enhanced resonant controller before modification is derived by combining the discrete transfer function and the open-loop transfer function of the current loop system, wherein the discrete transfer function is derived by discretizing the continuous transfer function of the standard second-order notch filter using the pre-distortion bilinear transformation method, and the discrete transfer function is: ; wherein, is the sampling period of the current loop, is the center frequency of the filter to be suppressed, is the filter bandwidth, is a complex variable in the discrete domain.

[0012] Further, in step S4, the open-loop transfer function of the 6th harmonic resonance controller and the open-loop transfer function of the 12th harmonic resonance controller are: ; wherein, and are filter bandwidths of and respectively, is the open-loop transfer function of the 6th harmonic resonance controller, is the open-loop transfer function of the 12th harmonic resonance controller, is the resonance frequency corresponding to the 6th harmonic resonance controller, is the resonance frequency corresponding to the 12th harmonic resonance controller, is the sampling period of the current loop, is the center frequency to be suppressed by the filter, is a complex variable in the discrete domain, is the stator resistance, , is an attenuation factor, is the rotor electrical angular velocity of the permanent magnet synchronous motor.

[0013] Compared with the prior art, the present application can achieve the following beneficial effects: The permanent magnet synchronous motor dead-time compensation method of the present application can effectively compensate the 6th harmonic and 12th harmonic distortion voltage in real time, without the need for knowing the parameters of the inverter switching device and being limited by the current polarity judgment accuracy of the sensor. From the form of the closed-loop tracking transfer function and the closed-loop disturbance transfer function, the structure of the present application can effectively suppress the 6th harmonic and 12th harmonic disturbances caused by the dead-time effect, without affecting the closed-loop frequency response characteristics of the original system and the disturbance frequency response characteristics of other frequency bands, thereby achieving effective compensation of the distortion voltage. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings: Figure 1 is a flowchart of the permanent magnet synchronous motor dead-time compensation method according to an embodiment of the present application; Figure 2 is a schematic diagram of the principle of the permanent magnet synchronous motor dead-time compensation method according to an embodiment of the present application; Figure 3 is a Bode plot of the closed-loop tracking transfer function according to an embodiment of the present application; Figure 4 Bode diagram of the closed-loop disturbance transfer function according to an embodiment of the present invention; Figure 5 Compensation voltage waveform and total harmonic distortion analysis diagram of the variable voltage compensation loop according to an embodiment of the present invention; Figure 6 Three-phase current waveform diagram according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and do not constitute a limitation on the present invention.

[0016] It should be noted that the embodiments in the present invention and the features in the embodiments can be combined with each other without conflict.

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited by "first", "second" and the like can explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0018] In the description of the present invention, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood through specific circumstances.

[0019] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0020] As Figure 1As shown, this invention proposes a method for dead-time compensation of a permanent magnet synchronous motor, specifically including the following steps: S1: In S1: Construct the open-loop transfer function of the current loop system of the permanent magnet synchronous motor using a complex plane; S2: Based on the open-loop transfer function of the current loop system, construct a distortion voltage compensation loop that includes the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system; S3: Configure additional terms of the closed-loop disturbance transfer function based on the notch filter principle, and solve the open-loop transfer function of the enhanced resonant controller based on the configuration results of the additional terms; The enhanced resonant controller consists of a 6th harmonic enhanced resonant controller and a 12th harmonic enhanced resonant controller connected in parallel; S4: Solve the open-loop transfer functions of the 6th harmonic enhanced resonant controller and the 12th harmonic enhanced resonant controller based on the open-loop transfer function of the enhanced resonant controller, and realize the configuration of the distortion voltage compensation loop.

[0021] It should be noted that this invention is based on the discrete domain complex plane model of a permanent magnet synchronous motor, and designs a distortion voltage compensation loop that decouples closed-loop tracking performance and disturbance suppression performance; then, based on the notch filter principle, it configures additional terms of the closed-loop disturbance transfer function to obtain the discrete transfer function of the control loop in the distortion voltage compensation loop, thereby realizing the configuration of the distortion voltage compensation loop.

[0022] System open-loop transfer function One-shot delay segment Internal mold control process The position in the main circuit is as follows: Figure 2 As shown, in addition, Figure 2 It also demonstrates the estimation of the system's open-loop transfer function. 6th Harmonic Enhanced Resonant Controller and 12th harmonic enhanced resonant controller The location of the distortion voltage compensation circuit. Related to the estimation of the open-loop transfer function. Serial Together, we simulate the effect of a one-beat delay.

[0023] First of all, A mathematical model is established in the complex plane, and the open-loop transfer function of the permanent magnet synchronous motor system from voltage input to stator current output is obtained. It can be represented as: (1); In the formula: , and These represent stator resistance and stator inductance, respectively. It is the sampling period of the current loop. It is electric angular velocity. It is the sampling period of the current loop. It is a complex variable in the discrete domain. is the imaginary unit.

[0024] Considering the computation time required by the actual control process, there is also a one-beat delay between the inverter voltage input and the disturbance input , which is expressed as: (2). According to the internal model design rule, the controller is composed of an inverse system model and an integrator with a gain that determines the closed-loop bandwidth. Since the inverse model of the open-loop transfer function cannot be directly physically implemented, an additional link is added in digital applications, and the internal model control link is designed as: (3). In the formula: k is the closed-loop bandwidth gain, and k is taken as 0.25 to achieve optimal closed-loop tracking performance. The distortion voltage compensation loop shown in Figure 2 is designed, and in the distortion voltage compensation loop is the estimated open-loop transfer function of the current loop system: (4). In the formula: , and represent the estimated stator resistance and the estimated stator inductance, respectively. If the estimated parameters are accurate, the and the system open-loop transfer function are completely identical.

[0025] As shown in Figure 2 , in the distortion voltage compensation loop, and are the enhanced resonant controllers (ERC) for the 6th harmonic and the 12th harmonic, respectively, and and are combined into the enhanced resonant controller , and the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system are obtained as: (5). In the formula: is the equivalent link of . Formula (5) shows that the distortion voltage compensation loop does not affect the closed-loop tracking transfer function , but only affects the closed-loop disturbance transfer function , which is manifested as introducing an additional term .

[0026] The above, by introducing, such as Figure 2 The distortion voltage compensation circuit shown effectively configures the system's disturbance suppression characteristics without changing the system's closed-loop tracking characteristics. Therefore, the distortion voltage compensation circuit of the present invention achieves decoupling of closed-loop tracking performance and disturbance suppression performance, and can maintain the original closed-loop tracking capability while effectively suppressing distortion voltage disturbances.

[0027] Next, the present invention configures additional terms in the closed-loop disturbance transfer function. This effectively compensates for voltage distortion dominated by the 6th and 12th harmonics, reducing the impact of dead time on phase current distortion. Specifically, additional items... Configured as a standard second-order notch filter, the continuous transfer function of the standard second-order notch filter. for: (6); In the formula: It is the Laplace operator. It is the center frequency that the filter wants to suppress. This is the filter bandwidth. Equation (6) is discretized using the pre-distortion bilinear transform method to obtain the discrete transfer function. : (7); In the formula: sin represents the sine operation, and cos represents the cosine operation. Combining equations (1) and (7), the open-loop transfer function of the enhanced resonant controller before modification can be obtained. The expression: (8); Due to the process The highest order of the molecule is 2 higher than the highest order of the denominator, which cannot be physically realized, therefore multiplying by... This is used to correct the open-loop transfer function. The purpose of this is to reduce the order of the numerator by 2 to match the order of the denominator, thereby satisfying the causal requirement; Its function is at the center frequency Compensation will be provided for the delay. The resulting phase shift ensures the optimal frequency response at the center frequency point.

[0028] Multiply The open-loop transfer function of the enhanced resonant controller for: (9); When the enhanced resonant controller is implemented using equation (9), the closed-loop disturbance transfer function is... At the center frequency A notch filter effect occurs. To effectively compensate for voltage distortion dominated by the 6th and 12th harmonics, a configuration is needed. Parallel links and The center frequencies are respectively and This enables effective compensation for distorted voltage. After configuration... and Represented as: (10); In the formula: and They are respectively and The filter bandwidth is selected as the corresponding resonant frequency in practical applications. and resonant frequency A fixed gain multiple is used to achieve consistent harmonic attenuation at the 6th and 12th harmonic frequencies.

[0029] like Figure 3 As shown, the permanent magnet synchronous motor speed is 500 r / min, and the filter bandwidth is... and filter bandwidth These are the resonant frequencies. and When the voltage is 0.05 times the normal value, the Bode plot of the closed-loop tracking transfer function before and after introducing the distortion voltage compensation circuit is shown. Since this invention is based on... The mathematical model is established using the complex plane, so each case corresponds to two curves: one in positive order and one in negative order. Figure 3 As can be seen, the closed-loop frequency response curves completely overlap, indicating that the introduction of the distortion voltage compensation circuit of the present invention will not change the closed-loop tracking characteristics of the original system, effectively ensuring the stability of the current loop during reference tracking.

[0030] like Figure 4 As shown, the permanent magnet synchronous motor speed is 500 r / min, and the filter bandwidth is... and filter bandwidth These are the resonant frequencies. and The Bode plot of the closed-loop disturbance transfer function at 0.05 times the value. (From...) Figure 4 It can be seen that after introducing the distortion voltage compensation circuit, the disturbance frequency response curve is in resonant frequency and The resonant amplitude attenuation is significant at the resonant frequency, while it coincides with the original system at other frequency bands. This indicates that the present invention can effectively suppress the distortion voltage disturbance dominated by the 6th and 12th harmonics, and achieve effective dead zone compensation without affecting the performance of other frequency bands of the system.

[0031] As shown in Figure 5 , the permanent magnet synchronous motor speed is 500r / min, the filter bandwidth and the filter bandwidth are respectively 0.05 times of the resonant frequency and , the compensation voltage waveform and the total harmonic distortion of the output of the distortion voltage compensation circuit are analyzed. Figure 5 THD in the formula represents the total harmonic distortion (THD), and DC represents the direct current (DC). It can be seen from the formula that Figure 5 the compensated distortion voltage is mainly the alternating component of the 6th harmonic and the 12th harmonic, which is consistent with the harmonic characteristics of the distortion voltage caused by the dead time, so the compensation effect of the distortion voltage compensation circuit proposed in the application is verified.

[0032] As shown in Figure 6 , the permanent magnet synchronous motor speed is 500r / min, the filter bandwidth and the filter bandwidth are respectively 0.05 times of the resonant frequency and , the three-phase current waveform when the filter bandwidth is 0.05 times of the resonant frequency is shown, wherein, no compensation measure is used within 0.3-0.4s, the traditional offline compensation method is used within 0.5-0.6s, the 6th distortion voltage compensation is introduced within 0.7-0.8s, and the 6th and 12th distortion voltage compensations are introduced simultaneously within 0.9-1s. It can be seen from the formula that Figure 6 the three-phase waveform after the 6th and 12th distortion voltage compensations are introduced simultaneously has the best sinusoidal degree, compared with the traditional offline compensation method, the THD is further reduced by 8.65%, and has better compensation accuracy and harmonic suppression effect.

[0033] Therefore, compared with the traditional offline compensation method, the compensation method of the application realizes better compensation accuracy and harmonic suppression effect without knowing the parameters of the inverter switching device and being limited by the current polarity judgment accuracy of the sensor, which helps to provide a new idea for realizing the precise dead-time compensation method of the permanent magnet synchronous motor.

[0034] It should be understood that the various forms of flow shown above can be reordered, added or deleted steps. For example, the steps described in the present disclosure can be executed in parallel, in sequence or in different order, as long as the desired results of the technical solutions of the present disclosure can be achieved, which is not limited herein.

[0035] The above detailed description does not limit the scope of the application. Various modifications, combinations, sub-combinations and alternatives can be made to the detailed embodiment within the scope of the application. Any modification, equivalent replacement and improvement made without departing from the spirit and principle of the application shall fall within the scope of the application.

Claims

1. A method for dead-time compensation of a permanent magnet synchronous motor, characterized in that: Specifically, the steps include the following: S1: In The open-loop transfer function of the current loop system of a permanent magnet synchronous motor is constructed using a complex plane. S2: Based on the open-loop transfer function of the current loop system, construct a distortion voltage compensation loop that includes the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system. S3: Configure additional terms of the closed-loop disturbance transfer function based on the notch filter principle, and solve the open-loop transfer function of the enhanced resonant controller based on the configuration results of the additional terms; The enhanced resonance controller consists of a 6th harmonic enhanced resonance controller and a 12th harmonic enhanced resonance controller connected in parallel; S4: Solve the open-loop transfer functions of the 6th harmonic enhanced resonant controller and the 12th harmonic enhanced resonant controller based on the open-loop transfer function of the enhanced resonant controller, and realize the configuration of the distortion voltage compensation circuit.

2. The dead-time compensation method for permanent magnet synchronous motors according to claim 1, characterized in that: In step S1, the open-loop transfer function of the current loop system of the permanent magnet synchronous motor is... : ； in, , and These are the stator resistance and stator inductance, respectively. The sampling period of the current loop. It is electric angular velocity. It is a complex variable in the discrete domain. It is the imaginary unit.

3. The dead-time compensation method for permanent magnet synchronous motors according to claim 1, characterized in that: In step S2, the closed-loop tracking transfer function and the closed-loop disturbance transfer function of the current loop system are: ； in, For closed-loop tracking transfer function, Let be the closed-loop disturbance transfer function. For the internal mold control link, Let be the open-loop transfer function of the current loop system. It is a complex variable in the discrete domain. The open-loop transfer function of the enhanced resonant controller before modification. for The equivalent link.

4. The dead-time compensation method for permanent magnet synchronous motors according to claim 1, characterized in that: In step S2, the distortion voltage compensation loop also includes estimating the open-loop transfer function of the current loop system. : ； in, , and These represent the estimated stator resistance and the estimated stator inductance, respectively. The sampling period of the current loop. It is electric angular velocity.

5. The dead-time compensation method for permanent magnet synchronous motors according to claim 3, characterized in that: In step S3, the additional term of the closed-loop disturbance transfer function is: The additional item is configured as a standard second-order notch filter, and the continuous transfer function of the standard second-order notch filter is... for: ； in, For the Laplace operator, The center frequency that the filter wants to suppress. For the filter bandwidth, The open-loop transfer function of the enhanced resonant controller before modification. Let be the open-loop transfer function of the current loop system.

6. The dead-time compensation method for permanent magnet synchronous motors according to claim 1, characterized in that: In step S4, the open-loop transfer function of the enhanced resonant controller is... for: ； in, and These are the stator resistance and stator inductance, respectively. The sampling period of the current loop. The center frequency that the filter wants to suppress. For the filter bandwidth, It is a complex variable in the discrete domain. The open-loop transfer function of the enhanced resonant controller before modification. , This is the attenuation factor.

7. The dead-time compensation method for a permanent magnet synchronous motor according to claim 3 or 6, characterized in that: Open-loop transfer function of the enhanced resonant controller before modification for: ； in, For stator resistance, The sampling period of the current loop. The center frequency that the filter wants to suppress. For the filter bandwidth, , As the attenuation factor, It is a complex variable in the discrete domain.

8. The dead-time compensation method for a permanent magnet synchronous motor according to claim 7, characterized in that: The open-loop transfer function of the original enhanced resonant controller was obtained by simultaneously solving the discrete transfer function and the open-loop transfer function of the current loop system. The discrete transfer function was derived by discretizing the continuous transfer function of the standard second-order notch filter using the predistortion bilinear transform method. for: ； in, The sampling period of the current loop. The center frequency that the filter wants to suppress. For the filter bandwidth, It is a complex variable in the discrete domain.

9. The dead-time compensation method for a permanent magnet synchronous motor according to claim 1, characterized in that: In step S4, the open-loop transfer function of the 6th harmonic enhanced resonant controller and the open-loop transfer function of the 12th harmonic enhanced resonant controller are: ； in, and They are respectively and The filter bandwidth, The open-loop transfer function of the 6th harmonic enhanced resonant controller is given. The open-loop transfer function of the 12th harmonic enhanced resonant controller is given. The resonant frequency corresponding to the 6th harmonic enhancement resonant controller. The resonant frequency corresponding to the 12th harmonic enhancement resonant controller. The sampling period of the current loop. The center frequency that the filter wants to suppress. It is a complex variable in the discrete domain. For stator resistance, , As the attenuation factor, This refers to the rotor electric angular velocity of the permanent magnet synchronous motor.

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