Motor position-free vector control system based on dead zone compensation and motor system
阅读说明：本技术 一种基于死区补偿的电机无位置矢量控制系统及电机系统 (Motor position-free vector control system based on dead zone compensation and motor system ) 是由 尹泉 罗慧 刘青 于 2019-10-23 设计创作，主要内容包括：本发明公开了一种基于死区补偿的无位置矢量控制系统及电机系统,属于电力电子控制技术领域,包括：电流采样模块,其输入端连接至三相桥臂；观测模块,其第一输入端连接至电流采样模块的输出端,第二输入端用于接收电压矢量U<Sub>αβ</Sub>,第三输入端连接至观测模块的第二输出端,用于估算电机转子的位置和角速度,并过滤掉其中的五次谐波和七次谐波；反馈控制模块,其三个输入端分别连接至观测模块的第一输出端、第二输出端以及电流采样模块的输出端；死区补偿模块,其第一输入端用于接收相电流,第二输入端连接至反馈控制模块的输出端；以及SVPWM模块,其输入端和输出端分别连接至死区补偿模块的输出端和三相桥臂。本发明能够提高永磁同步电机的控制性能。(The invention discloses a dead zone compensation-based position vector-free control system and a motor system, which belong to the technical field of power electronic control and comprise the following steps: the input end of the current sampling module is connected to the three-phase bridge arm; an observation module having a first input terminal connected to the output terminal of the current sampling module and a second input terminal for receiving the voltage vector U αβ The third input end is connected to the second output end of the observation module and used for estimating the position and the angular speed of the motor rotor and filtering fifth harmonic and seventh harmonic; a feedback control module with three input terminalsThe first output end and the second output end of the observation module and the output end of the current sampling module are respectively connected; the dead zone compensation module is used for receiving the phase current at a first input end and is connected to the output end of the feedback control module at a second input end; and the input end and the output end of the SVPWM module are respectively connected to the output end of the dead zone compensation module and the three-phase bridge arm. The invention can improve the control performance of the permanent magnet synchronous motor.)
1. A dead-time compensation based motor position-free vector control system, comprising: the device comprises a current sampling module, an observation module, a feedback control module, a dead zone compensation module and an SVPWM module;
the input end of the current sampling module is connected to a three-phase bridge arm of the motor inverter; the current sampling module is used for collecting any two-phase current so as to convert the phase current into a two-phase static coordinate system to obtain a current vector i αβ；
The first input end of the observation module is connected to the output end of the current sampling module, and the second input end of the observation module is used for receiving a voltage vector U of the motor under a two-phase static coordinate system αβA third input terminal of the observation module is connected to a second output terminal of the observation module; the observation module is used for estimating the position and the angular speed of the motor rotor according to the input signal, filtering out fifth harmonic and seventh harmonic in the position and the angular speed, and obtaining an electrical angle observation value of the rotor
A first input end of the feedback control module is connected to a first output end of the observation module, a second input end of the feedback control module is connected to a second output end of the observation module, and a third input end of the feedback control module is connected to an output end of the current sampling module; the feedback control module is used for carrying out speed feedback control and current feedback control according to the input signal to obtain a voltage vector instruction value under a two-phase static coordinate system
The dead zone compensation module has a first input terminal for receiving phase current, and the dead zoneThe second input end of the compensation module is connected to the output end of the feedback control module; the dead zone compensation module is used for determining corresponding phase voltage compensation quantity according to each phase current and then converting the phase voltage compensation quantity into a two-phase static coordinate system to obtain a compensation voltage vector for dead zone compensation
The input end of the SVPWM module is connected to the output end of the dead zone compensation module, and the output end of the SVPWM module is connected to a three-phase bridge arm of a motor inverter; the SVPWM module is used for generating a voltage vector instruction value according to the voltage vector instruction value
2. The dead-time compensation based motor position-less vector control system of claim 1, wherein the observation module comprises: the system comprises a full-order sliding mode observer, a self-adaptive notch filter and a quadrature phase-locked loop;
a first input end of the full-order sliding mode observer is used as a first input end of the observation module, a second input end of the full-order sliding mode observer is used as a second input end of the observation module, and a third input end of the full-order sliding mode observer is used as a third input end of the observation module; the full-order sliding-mode observer is used for observing a current vector i αβElectricity, electricityPressure vector U αβAnd observed value of angular velocity Estimating an extended back EMF vector observation under a two-phase stationary coordinate system
The input end of the self-adaptive notch filter is connected to the output end of the full-order sliding mode observer; the adaptive notch filter is used for continuously and automatically tuning the internal parameters thereof to obtain a notch frequency omega which enables the observation module not to be influenced by fifth harmonic and seventh harmonic hThen according to the notch frequency omega hFiltering extended back EMF vector observations
The input end of the orthogonal phase-locked loop is connected to the output end of the adaptive notch filter, the first output end of the orthogonal phase-locked loop is used as the first output end of the observation module, and the second output end of the orthogonal phase-locked loop is used as the second output end of the observation module; the quadrature phase-locked loop is used for expanding the back electromotive force vector Estimating an electrical angle observation of a rotor of an electrical machine
3. The dead-zone compensation based motor position-free vector control system of claim 2, wherein the full-order sliding-mode observer performs an observed state equation determined by the method comprising:
transforming a motor stator voltage equation to realize decoupling of rotor position information, and obtaining a first voltage equation as follows:
converting the first voltage equation into a two-phase static coordinate system to obtain a second voltage equation;
transforming the second voltage equation into a state equation to obtain a target state equation as follows:
establishing a state equation of a full-order sliding-mode observer according to the target state equation:
wherein R is sRepresenting the resistance in the stator winding, p representing the differential operator, L dAnd L qRespectively representing the d-axis and q-axis inductance values, u, of the stator winding dAnd u qRespectively representing d-axis voltage and q-axis voltage, i dAnd i qRepresenting d-axis current and q-axis current, ω, respectively eRepresenting the actual rotor angular velocity, # fThe flux linkage of the rotor is shown,
4. The dead-zone compensation based motor position-free vector control system of claim 2 or 3, wherein the switching function of the full-order sliding mode observer is a sigmoid function.
5. The dead-zone compensation-based motor position-vector-free control system of claim 2, wherein the adaptive notch filter performs continuous self-tuning on internal parameters thereof according to a minimum mean square error algorithm to obtain a notch frequency ω that makes the observation module free from fifth harmonic and seventh harmonic h。
6. The dead-zone compensation based motor position-free vector control system of claim 2 or 5, wherein the transfer function of the adaptive notch filter is:
where μ is a constant parameter inside the adaptive notch filter.
7. The dead-zone compensation based motor position-free vector control system of claim 1, wherein the dead-zone compensation module determines a corresponding phase voltage compensation amount according to each phase current by:
for each phase current I, according to a preset threshold value I oct -、I ct -、I ct +And I oct +Dividing the phase current I into five intervals if I > I oct +If the phase voltage compensation quantity delta V of the corresponding phase is positive; if I < I oct -If the phase voltage compensation quantity delta V of the corresponding phase is negative; if I ∈ (I) ct -,I ct +) Then no dead zone compensation is performed; if I belongs to [ I ] oct -,I ct -]Or I ∈ [ I ] ct +,I oct +]If the phase voltage compensation quantity delta V of the corresponding phase is a linear function of the phase current i;
wherein, I oct -＜I ct -＜0＜I ct +＜I oct +Phase current i is a phase current i aPhase i of b-phase current bOr c-phase current i c。
8. The dead-time compensation based motor position-free vector control system of claim 7, wherein the phase voltage compensation amount Δ V determined by the dead-time compensation module and the phase current i of the corresponding phase satisfy:
wherein, U dcFor the DC bus voltage, τ is the time of influence of the dead-zone effect, T sIs an SVPWM period.
9. The dead-zone compensation based motor position-free vector control system of claim 1, wherein the feedback control module comprises αβ -dq coordinate transformation unit, d-axis current PI control unit, speed PI control unit, q-axis current PI control unit, and dq- αβ coordinate transformation unit;
a first input end of the αβ -dq coordinate transformation unit is connected with a first input end of the dq- αβ coordinate transformation unit and then serves as a first input end of the feedback control module;
a second input end of the αβ -dq coordinate transformation unit is used as a third input end of the feedback control module, and the αβ -dq coordinate transformation unit is used for observing a value according to an electrical angle
The input end of the d-axis current PI control unit is connected to the first output end of the αβ -dq coordinate transformation unit, and the d-axis current PI control unit is used for controlling the d-axis current i dAnd a preset d-axis current command value
The input end of the speed PI control unit is used as a second input end of the feedback control module; the speed PI control unit is used for observing the angular speed of the motor rotor
A first input end of the q-axis current PI control unit is connected to an output end of the speed PI control unit, a second input end of the q-axis current PI control unit is connected to a second output end of the αβ -dq coordinate transformation unit, and the q-axis current PI control unit is used for converting a q-axis current i qAnd q-axis current command value
A second input end of the dq- αβ coordinate transformation unit is connected to an output end of the d-axis current PI control unit, a third input end of the dq- αβ coordinate transformation unit is connected to an output end of the q-axis current PI control unit, an output end of the dq- αβ coordinate transformation unit is used as an output end of the feedback control module, and the dq- αβ coordinate transformation unit is used for observing a value according to an electrical angle
10. A motor system comprising a motor and a motor position vector-free control system, wherein the motor position vector-free control system is the motor position vector-free control system based on dead zone compensation according to any one of claims 1 to 9;
the input end of a current sampling module of the motor position-less vector control system is connected to a three-phase bridge arm of a motor inverter, and the output end of an SVPWM module of the motor position-less vector control system is connected to the three-phase bridge arm of the motor inverter; the motor non-position vector control system is used for controlling the motor.
Technical Field
The invention belongs to the technical field of power electronic control, and particularly relates to a dead zone compensation-based motor position vector-free control system and a motor system.
Background
In recent years, the development of human society is restricted by the problem of energy shortage. With the discovery of high-performance rare earth permanent magnet materials in China and the continuous development of power electronic devices, industrial automation, robots and electric automobiles are widely used in motors. The motors used in the electrical transmission industry are mainly classified into ac motors and dc motors, wherein the ac motors are classified into induction ac motors and permanent magnet synchronous motors. The permanent magnet synchronous motor has the advantages of high reliability, simple structure, small volume and good control performance, and compared with a direct current motor, the permanent magnet synchronous motor has high reliability and relatively low maintenance cost because no mechanical commutator and electric brush are arranged in the permanent magnet synchronous motor; compared with an induction type alternating current motor, the permanent magnet synchronous motor does not need exciting current, and the power factor is higher. At present, the permanent magnet synchronous motor is widely applied to the fields of industrial production, household appliances, transportation and the like, and the control performance of the permanent magnet synchronous motor is improved, so that the permanent magnet synchronous motor has great practical value.
The control method of the permanent magnet synchronous motor is mainly divided into two types: direct torque control and vector control, both of which require precise rotor position and angular velocity. Therefore, in the motor control system, a position sensor such as a photoelectric encoder is generally added. Although the mechanical position sensor can accurately provide the angle information of the rotor, it also has a certain negative effect on the motor control system, which is mainly reflected in: (1) the price of the mechanical position sensor is generally higher, the cost is increased when the position sensor is installed in the motor control system, and the size of the motor driver is increased; (2) a QEP coding interface circuit is additionally arranged between the motor and the driver, so that inconvenience is brought to engineering application, and the stability of a system is also not facilitated; (2) the mechanical position sensor is an electromagnetic element, is greatly influenced by the operating condition of the system, and the detection precision of the mechanical position sensor is easily limited by external conditions, so that the reliability of the system is reduced; (4) in some special applications, which are limited by operating conditions, mechanical position sensors, such as air conditioning compressor systems, cannot be used, so that the entire system cannot operate properly.
The motor position-less control system estimates the rotor position and the angular velocity from the measured values of the external variables of the system using the observer without using a position sensor, and thus can solve the above problems well. However, due to the influence of the dead zone effect, an observed value estimated by an observer often has a large error with an actual value, so that the control performance of the motor position-free control system is not ideal.
Disclosure of Invention
Aiming at the defects and improvement requirements of the prior art, the invention provides a dead zone compensation-based motor position vector-free control system and a motor system, and aims to improve the control performance of a permanent magnet synchronous motor.
To achieve the above object, according to a first aspect of the present invention, there is provided a dead-zone compensation based motor position-less vector control system, comprising: the device comprises a current sampling module, an observation module, a feedback control module, a dead zone compensation module and an SVPWM module;
the input end of the current sampling module is connected to a three-phase bridge arm of the motor inverter; the current sampling module is used for collecting any two-phase current so as to convert the phase current into a two-phase static coordinate system to obtain a current vector i αβ；
The first input end of the observation module is connected to the output end of the current sampling module, and the second input end of the observation module is used for receiving a voltage vector U of the motor under a two-phase static coordinate system αβThe third input end of the observation module is connected to the second output end of the observation module; the observation module is used for estimating the position and the angular speed of the motor rotor according to the input signal, filtering out fifth harmonic and seventh harmonic in the position and the angular speed, and obtaining an electrical angle observation value of the rotor
A first input end of the feedback control module is connected to a first output end of the observation module, a second input end of the feedback control module is connected to a second output end of the observation module, and a third input end of the feedback control module is connected to an output end of the current sampling module; the feedback control module is used for carrying out speed feedback control and current feedback control according to the input signal to obtain a voltage vector instruction value under a two-phase static coordinate system
The first input end of the dead zone compensation module is used for receiving phase current, and the second input end of the dead zone compensation module is connected to the output end of the feedback control module; the dead zone compensation module is used for determining corresponding phase voltage compensation quantity according to each phase current and then converting the phase voltage compensation quantity into a two-phase static coordinate system to obtain a compensation voltage vector for dead zone compensation And using the compensation voltage vector
The input end of the SVPWM module is connected to the output end of the dead zone compensation module, and the output end of the SVPWM module is connected to a three-phase bridge arm of the motor inverter; the SVPWM module is used for generating a voltage vector instruction value according to the voltage vector instruction value
The influence generated by the dead zone effect is mainly five harmonics and seven harmonics, when the observation module is used for obtaining the electric angle observation value and the angular speed observation value of the motor rotor, the five harmonics and seven harmonics can be filtered out, so that the influence of mismatch voltage vectors generated by the dead zone effect on a system can be reduced, the estimated rotor position is closer to an actual value, the steady-state error oscillation of the rotor position is reduced, and because a differential relation exists between the rotor position (electric angle) and the rotor speed (angular speed), the estimation precision of the rotor speed is improved while the estimation precision of the rotor position is improved, so the control performance of the permanent magnet synchronous motor can be improved; the traditional dead zone compensation scheme adopts a unified compensation strategy, and does not consider the actual value of phase current, so that the phase current can generate larger deviation at a zero crossing point; according to the invention, the compensation voltage vector for vector compensation is determined according to the actual phase current, so that the deviation of the phase current caused by the zero crossing point can be effectively avoided, and the control performance is improved. In general, the influence of the dead zone effect on the permanent magnet synchronous motor is fully considered, and the control performance of the permanent magnet synchronous motor is improved.
Further, the observation module includes: the system comprises a full-order sliding mode observer, a self-adaptive notch filter and a quadrature phase-locked loop;
the first input end of the full-order sliding mode observer is used as the first input end of the observation module, the second input end of the full-order sliding mode observer is used as the second input end of the observation module, and the third input end of the full-order sliding mode observer is used as the third input end of the observation module; the full-order sliding-mode observer is used for observing a current vector i αβVoltage vector U αβAnd observed value of angular velocity
The input end of the self-adaptive notch filter is connected to the output end of the full-order sliding mode observer; the adaptive notch filter is used for continuously self-tuning the internal parameters thereof to obtain a notch frequency omega which makes the observation module not influenced by the fifth harmonic and the seventh harmonic hThen according to the notch frequency omega hFiltering extended back EMF vector observations
The input end of the orthogonal phase-locked loop is connected to the output end of the adaptive notch filter, the first output end of the orthogonal phase-locked loop is used as the first output end of the observation module, and the second output end of the orthogonal phase-locked loop is used as the second output end of the observation module; the quadrature phase-locked loop is used for expanding the back electromotive force vector
According to the method, the extended back electromotive force vector observed value under the two-phase static coordinate system is estimated by using the full-order sliding-mode observer, the fifth harmonic and the seventh harmonic in the extended back electromotive force vector are filtered by using the self-adaptive notch filter, the influence of a mismatch voltage vector generated by a dead zone effect on a system can be reduced, meanwhile, the phase lag generated by the estimation of the rotor position due to the use of a low-pass filter is avoided, the electric angle observed value of the rotor is ensured to be closer to an actual value, and the estimation accuracy of the rotor position and the rotor speed is improved.
Further, the state equation observed by the full-order sliding-mode observer is determined by the following method:
transforming a motor stator voltage equation to realize decoupling of rotor position information, and obtaining a first voltage equation as follows:
converting the first voltage equation into a two-phase static coordinate system to obtain a second voltage equation;
transforming the second voltage equation into a state equation to obtain a target state equation as follows:
establishing a state equation of a full-order sliding-mode observer according to a target state equation:
wherein R is sRepresenting the resistance in the stator winding, p representing the differential operator, L dAnd L qRespectively representing the d-axis and q-axis inductance values, u, of the stator winding dAnd u qRespectively representing d-axis voltage and q-axis voltage, i dAnd i qRepresenting d-axis current and q-axis current, ω, respectively eRepresenting the actual rotor angular velocity, # fThe flux linkage of the rotor is shown,
According to the invention, when the state equation of full-order sliding mode observation is determined, the voltage equation of the motor stator is transformed, and the decoupling of the position information of the rotor is realized, so that the position information of the rotor can be extracted by using the observation module.
Further, the switching function of the full-order sliding mode observer is a sigmoid function; the sigmoid function has smooth continuity, and the estimation accuracy of the rotor position information and the speed information can be improved by using the sigmoid function as a switching function of the full-order sliding mode observer.
Further, the adaptive notch filter continuously self-adjusts its internal parameters according to a least mean square error algorithm (LMS) to obtain a notch frequency ω that makes the observation module not affected by the fifth harmonic and the seventh harmonic h。
Further, the transfer function of the adaptive notch filter is:
where μ is a constant parameter inside the adaptive notch filter.
Further, the dead zone compensation module determines a corresponding phase voltage compensation amount according to each phase current, and the dead zone compensation module is implemented by the following steps:
for each phase current I, according to a preset threshold value I oct -、I ct -、I ct +And I oct +Dividing the phase current I into five intervals if I > I oct +If the phase voltage compensation quantity delta V of the corresponding phase is positive; if I < I oct -If the phase voltage compensation quantity delta V of the corresponding phase is negative; if I ∈ (I) ct -,I ct +) Then no dead zone compensation is performed; if I belongs to [ I ] oct -,I ct -]Or I ∈ [ I ] ct +,I oct +]If the phase voltage compensation quantity delta V of the corresponding phase is a linear function of the phase current i;
wherein, I oct -＜I ct -＜0＜I ct +＜I oct +Phase current i is a phase current i aPhase i of b-phase current bOr c-phase current i c。
The invention adopts a sectional compensation mode to divide the actual value of the phase current into five intervals, and adopts different compensation strategies according to the actual interval of the phase current, thereby effectively avoiding the deviation of the phase current caused by the zero crossing point, and further improving the control performance of the permanent magnet synchronous motor.
Further, the phase voltage compensation quantity Δ V determined by the dead zone compensation module and the phase current i of the corresponding phase satisfy:
wherein, U dcFor the DC bus voltage, τ is the time of influence of the dead-zone effect, T sIs an SVPWM period.
The feedback control module further comprises an αβ -dq coordinate transformation unit, a d-axis current PI control unit, a speed PI control unit, a q-axis current PI control unit and a dq- αβ coordinate transformation unit;
the first input end of the αβ -dq coordinate transformation unit is connected with the first input end of the dq- αβ coordinate transformation unit and then serves as the first input end of the feedback control module;
αβ -dq coordinate transformation sheetA second input of the element as a third input of the feedback control module, and an αβ -dq coordinate transformation unit for observing the value according to the electrical angle
The input end of the d-axis current PI control unit is connected to the first output end of the αβ -dq coordinate transformation unit, and the d-axis current PI control unit is used for controlling the d-axis current i dAnd a preset d-axis current command value
The input end of the speed PI control unit is used as a second input end of the feedback control module; the speed PI control unit is used for observing the angular speed of the motor rotor
A first input end of the q-axis current PI control unit is connected to the output end of the speed PI control unit, a second input end of the q-axis current PI control unit is connected to the second output end of the αβ -dq coordinate transformation unit, and the q-axis current PI control unit is used for converting the q-axis current i qAnd q-axis current command value
A second input end of the dq- αβ coordinate transformation unit is connected to the output end of the d-axis current PI control unit, a third input end of the dq- αβ coordinate transformation unit is connected to the output end of the q-axis current PI control unit, the output end of the dq- αβ coordinate transformation unit is used as the output end of the feedback control module, and the dq- αβ coordinate transformation unit is used for observing the value according to the electrical angle
According to a second aspect of the present invention, there is provided a motor system, comprising a motor and a motor non-position vector control system, wherein the motor non-position vector control system is the motor non-position vector control system based on dead zone compensation provided by the first aspect of the present invention;
the input end of a current sampling module of the motor position-less vector control system is connected to a three-phase bridge arm of a motor inverter, and the output end of an SVPWM module of the motor position-less vector control system is connected to the three-phase bridge arm of the motor inverter; the motor position vector-free control system is used for controlling the motor.
Generally, by the above technical solution conceived by the present invention, the following beneficial effects can be obtained:
(1) according to the dead zone compensation-based motor position vector-free control system and the motor system, when the observation module is used for estimating the electric angle observation value and the angular speed observation value of the motor rotor, quintuple harmonics and heptatuple harmonics in the electric angle observation value and the angular speed observation value can be filtered, the influence of mismatch voltage vectors generated by dead zone effects on the system can be reduced, the estimation precision of the rotor position and the rotor speed is improved, and therefore the control performance of the permanent magnet synchronous motor is improved; according to the invention, the compensation voltage vector for vector compensation is determined according to the actual current vector, so that the deviation of the phase current at the zero crossing point can be effectively avoided, and the control performance is improved. In general, the influence of the dead zone effect on the permanent magnet synchronous motor is fully considered, and the control performance of the permanent magnet synchronous motor is improved.
(2) According to the dead zone compensation-based motor position vector-free control system and the motor system, the extended back electromotive force vector observed value under a two-phase static coordinate system is estimated by using the full-order sliding mode observer, the fifth harmonic and the seventh harmonic in the extended back electromotive force vector are filtered by using the self-adaptive notch filter, the influence of a mismatch voltage vector generated by a dead zone effect on the system can be reduced, meanwhile, the phase lag generated by the estimation of the position of the rotor due to the use of a low-pass filter is avoided, the electric angle observed value of the rotor is ensured to be closer to an actual value, and the estimation accuracy of the position of the rotor and the speed of the rotor is improved.
(3) According to the dead zone compensation-based motor position vector-free control system and the motor system, when a state equation of full-order sliding mode observation is determined, a motor stator voltage equation is transformed, decoupling of rotor position information is achieved, and therefore the fact that the position information of a rotor can be extracted through an observation module is guaranteed.
(4) According to the dead zone compensation-based motor position vector control system and the motor system, the sigmoid function with smooth continuity is used as the switching function of the full-order sliding-mode observer, and the estimation accuracy of the rotor position information and the speed information can be improved.
(5) According to the dead zone compensation-based motor position vector-free control system and the motor system, the actual value of the current vector is divided into five intervals by adopting a sectional compensation mode, different compensation strategies are adopted according to the actual interval of the current vector, the deviation of the phase current at the zero crossing point can be effectively avoided, and the control performance of the permanent magnet synchronous motor is improved.
Drawings
FIG. 1 is a schematic diagram of a dead-time compensation-based motor position vector-free control system according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a conventional second-order sliding-mode observer;
FIG. 3 is a schematic diagram of a conventional full-order sliding-mode observer;
fig. 4 is a vector diagram of the back emf of the dead band effect according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
In the present application, the terms "first," "second," and the like (if any) in the description and the drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.
In order to improve the control performance of the permanent magnet synchronous motor, the dead zone compensation based motor position vector-free control system provided by the invention, as shown in fig. 1, comprises: the device comprises a current sampling module, an observation module, a feedback control module, a dead zone compensation module and an SVPWM module;
the input end of the current sampling module is connected to a three-phase bridge arm of the motor inverter; the current sampling module is used for collecting any two-phase current so as to convert the phase current into a two-phase static coordinate system to obtain a current vector i αβ(ii) a Since three phases are symmetrical, after phase currents of any two phases are collected, the phase current of the third phase can be calculated, and in this embodiment, as shown in fig. 1, the specifically collected phase current is a-phase current i aAnd b-phase current i b；
The first input end of the observation module is connectedTo the output end of the current sampling module, and the second input end of the observation module is used for receiving a voltage vector U of the motor under the two-phase static coordinate system αβThe third input end of the observation module is connected to the second output end of the observation module; the observation module is used for estimating the position and the angular speed of the motor rotor according to the input signal, filtering out fifth harmonic and seventh harmonic in the position and the angular speed, and obtaining an electrical angle observation value of the rotor
a first input end of the feedback control module is connected to a first output end of the observation module, a second input end of the feedback control module is connected to a second output end of the observation module, and a third input end of the feedback control module is connected to an output end of the current sampling module; the feedback control module is used for carrying out speed feedback control and current feedback control according to the input signal to obtain a voltage vector instruction value under a two-phase static coordinate system
The first input end of the dead zone compensation module is used for receiving phase current and compensating the dead zoneThe second input end of the compensation module is connected to the output end of the feedback control module; the dead zone compensation module is used for determining corresponding phase voltage compensation quantity according to each phase current and then converting the phase voltage compensation quantity into a two-phase static coordinate system to obtain a compensation voltage vector for dead zone compensation
The input end of the SVPWM module is connected to the output end of the dead zone compensation module, and the output end of the SVPWM module is connected to a three-phase bridge arm of the motor inverter; the SVPWM module is used for generating a voltage vector instruction value according to the voltage vector instruction value
According to the dead zone compensation-based motor position vector-free control system, when the observation module is used for obtaining the electric angle observation value and the angular speed observation value of the motor rotor, the fifth harmonic and the seventh harmonic can be filtered, the influence of a mismatch voltage vector generated by a dead zone effect on the system can be reduced, and the estimation precision of the rotor position and the rotor speed is improved, so that the control performance of the permanent magnet synchronous motor can be improved; according to the motor position-free vector control system based on dead zone compensation, the compensation voltage vector for vector compensation is determined according to the actual current vector, so that the deviation of phase current at the zero crossing point can be effectively avoided, and the control performance is improved. In general, the dead zone compensation-based motor position vector-free control system fully considers the influence of the dead zone effect on the permanent magnet synchronous motor, and improves the control performance of the permanent magnet synchronous motor.
In this embodiment, as shown in fig. 1, the observation module in the dead-time compensation based motor position vector free control system includes: the system comprises a full-order sliding mode observer, a self-adaptive notch filter and a quadrature phase-locked loop;
the first input end of the full-order sliding mode observer is used as the first input end of the observation module, the second input end of the full-order sliding mode observer is used as the second input end of the observation module, and the third input end of the full-order sliding mode observer is used as the third input end of the observation module; the full-order sliding-mode observer is used for observing a current vector i αβVoltage vector U αβAnd observed value of angular velocity
The input end of the self-adaptive notch filter is connected to the output end of the full-order sliding mode observer; the adaptive notch filter is used for continuously self-tuning the internal parameters thereof to obtain a notch frequency omega which makes the observation module not influenced by the fifth harmonic and the seventh harmonic hThen according to the notch frequency omega hFiltering extended back EMF vector observations
The input of the quadrature phase locked loop is connected to the output of the adaptive notch filter,a first output end of the orthogonal phase-locked loop is used as a first output end of the observation module, and a second output end of the orthogonal phase-locked loop is used as a second output end of the observation module; the quadrature phase-locked loop is used for expanding the back electromotive force vector
The structure and the principle of the second-order sliding mode observer are shown in fig. 2, the structure and the principle of the full-order sliding mode observer are shown in fig. 3, and the second-order sliding mode observer introduces a low-pass filter, so that the rotor position estimation generates phase lag; in the embodiment, the extended back electromotive force vector observed value under a two-phase static coordinate system is estimated by using the full-order sliding mode observer, and fifth harmonic and seventh harmonic in the extended back electromotive force vector are filtered by using the self-adaptive notch filter, so that the influence of a mismatch voltage vector generated by a dead zone effect on a system can be reduced, meanwhile, the phase lag generated by the estimation of the rotor position due to the use of a low-pass filter is avoided, the electric angle observed value of the rotor is ensured to be closer to an actual value, and the estimation accuracy of the rotor position and the rotor speed is improved;
in this embodiment, the determination method of the state equation observed by the full-order sliding-mode observer includes:
transforming a motor stator voltage equation to realize decoupling of rotor position information to obtain a first voltage equation;
the stator voltage equation of the permanent magnet synchronous motor is as follows:
wherein R is sRepresenting the resistance in the stator winding, p representing the differential operator, u dAnd u qRespectively representing d-axis voltage and q-axis voltage, i dAnd i qRepresenting d-axis current and q-axis current, ω, respectively eRepresenting the actual rotor angular velocity, # dAnd psi qRespectively represent a d-axis flux linkage and a q-axis flux linkage;
the rotor position information in the stator voltage equation is not completely decoupled, and a first voltage equation obtained by transforming the equation is as follows:
converting the first voltage equation into a two-phase static coordinate system to obtain a second voltage equation;
transforming the second voltage equation into a state equation to obtain a target state equation as follows:
establishing a state equation of a full-order sliding-mode observer according to a target state equation:
when a state equation of full-order sliding mode observation is determined, a motor stator voltage equation is transformed, decoupling of rotor position information is achieved, and therefore the fact that the position information of a rotor can be extracted by an observation module is guaranteed;
in a preferred embodiment, the switching function of the full-order sliding-mode observer is a sigmoid function; the sigmoid function has smooth continuity, and the estimation accuracy of the rotor position information and the speed information can be improved by using the sigmoid function as a switching function of the full-order sliding mode observer.
In a preferred embodiment, the Adaptive Notch Filter (ANF) continuously self-tunes its internal parameters according to a least mean square error algorithm (LMS) to obtain a notch frequency ω that leaves the observation block unaffected by the fifth and seventh harmonics h；
Accordingly, the transfer function of the adaptive notch filter is:
where μ is a constant parameter inside the adaptive notch filter.
FIG. 4 is a vector diagram of the back EMF with a dashed line representing the vector E sA vector Z shown by a solid line is a counter electromotive force vector in an ideal case sThe actual back electromotive force vector is influenced by the dead zone effect; as can be seen from fig. 4, the actual back emf vector is affected differently, and thus, the conventional dead-zone compensation scheme employs a uniform compensation strategy rather than a uniform compensation strategyConsidering the actual value of the current vector, the phase current generates larger deviation at the zero crossing point;
in this embodiment, the dead zone compensation module determines a corresponding phase voltage compensation amount according to each phase current, and the method includes:
for each phase current I, according to a preset threshold value I oct -、I ct -、I ct +And I oct +Dividing the phase current I into five intervals if I > I oct +If the phase voltage compensation quantity delta V of the corresponding phase is positive; if I < I oct -If the phase voltage compensation quantity delta V of the corresponding phase is negative; if I ∈ (I) ct -,I ct +) Then no dead zone compensation is performed; if I belongs to [ I ] oct -,I ct-]Or I ∈ [ I ] ct +,I oct +]If the phase voltage compensation quantity delta V of the corresponding phase is a linear function of the phase current i;
wherein, I oct -＜I ct -＜0＜I ct +＜I oct +Phase current i is a phase current i aPhase i of b-phase current bOr c-phase current i c(ii) a Threshold value I ct +The specific setting of (A) is required to meet the requirement that the phase current variation does not exceed I in one current control period ct +Here, the threshold value I is set ct +Setting the amplitude of the phase current to be 5%; i is oct +-I ct +Must be large enough so that the compensation voltage does not cause phase current oscillations;
specifically, the phase voltage compensation quantity Δ V determined by the dead zone compensation module and the phase current i of the corresponding phase satisfy:
wherein, U dcFor the DC bus voltage, τ is the time of influence of the dead-zone effect, T sIs SVPWM period;
specifically, a phase voltage compensation quantity DeltaV of a phase is obtained aB phase voltage compensation amount DeltaV of phase bAnd c-phase voltage compensation amount DeltaV cThen, converting into two static coordinate systems to obtain compensation voltage vector
In the embodiment, a sectional compensation mode is adopted, the actual value of the phase current is divided into five intervals, different compensation strategies are adopted according to the actual interval of the phase current, and the deviation of the phase current caused by the zero crossing point can be effectively avoided, so that the control performance of the permanent magnet synchronous motor is improved.
In the present embodiment, as shown in FIG. 1, the feedback control module includes an αβ -dq coordinate transformation unit, a d-axis current PI control unit, a speed PI control unit, a q-axis current PI control unit, and a dq- αβ coordinate transformation unit;
the first input end of the αβ -dq coordinate transformation unit is connected with the first input end of the dq- αβ coordinate transformation unit and then serves as the first input end of the feedback control module;
αβ -dq coordinate transformation unit as third input end of feedback control module, αβ -dq coordinate transformation unit for observing value according to electrical angle
The input end of the d-axis current PI control unit is connected to the first output end of the αβ -dq coordinate transformation unit, and the d-axis current PI control unit is used for controlling the d-axis current i dAnd a preset d-axis current command value
Input terminal of speed PI control unitA second input terminal of the feedback control module; the speed PI control unit is used for observing the angular speed of the motor rotor And a preset angular velocity command value
A first input end of the q-axis current PI control unit is connected to the output end of the speed PI control unit, a second input end of the q-axis current PI control unit is connected to the second output end of the αβ -dq coordinate transformation unit, and the q-axis current PI control unit is used for converting the q-axis current i qAnd q-axis current command value
A second input end of the dq- αβ coordinate transformation unit is connected to the output end of the d-axis current PI control unit, a third input end of the dq- αβ coordinate transformation unit is connected to the output end of the q-axis current PI control unit, the output end of the dq- αβ coordinate transformation unit is used as the output end of the feedback control module, and the dq- αβ coordinate transformation unit is used for observing the value according to the electrical angle
It is easily understood that in the dead-zone compensation based motor position vector-free control system, the voltage vector and the current vector in the two-phase stationary coordinate system are both formed by α axis components and β axis components, for example, the voltage vector U αβ＝[U α,U β] T，U αAnd U βRespectively representing a voltage vector U αβα axis component and β axis component, and further e.g., extended back emf vector observations
The invention also provides a motor system, which comprises a motor and a motor position-free vector control system, wherein the motor position-free vector control system is the motor position-free vector control system compensated in the dead zone;
the input end of a current sampling module of the motor position-less vector control system is connected to a three-phase bridge arm of a motor inverter, and the output end of an SVPWM module of the motor position-less vector control system is connected to the three-phase bridge arm of the motor inverter; the motor position vector-free control system is used for controlling the motor.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.