阅读说明：本技术 一种提升永磁同步电机无位置传感器估算性能的方法 (Method for improving estimation performance of permanent magnet synchronous motor without position sensor ) 是由 刘青 彭洵 王胜勇 王傲能 于 2020-06-19 设计创作，主要内容包括：本发明涉及电力电子控制技术,具体涉及一种提升永磁同步电机无位置传感器估算性能的方法,包括建立同步电机的数学模型,建立I/F流频比启动与基于扩展反电动势模型的滑模观测器转子位置、速度估算方案,针对低速段I/F到高速段滑模的硬切换产生的电流、转矩抖动问题,提出了一种新的平滑切换方法,使转矩、转速和电流的过渡过程平顺无冲击,并能保证从空载到额定负载不同负载条件下,切换过程都能够顺利实施。该方法具有成本低、估算精度高、速度快、实时性高、鲁棒性好以及抗干扰能力强的优点,能够提高永磁同步电机无位置传感器估算算法的估算精度,减小转子估算误差,对提升永磁同步电机无位置传感器矢量控制系统估算性能具有指导意义。(The invention relates to a power electronic control technology, in particular to a method for improving estimation performance of a permanent magnet synchronous motor without a position sensor, which comprises the steps of establishing a mathematical model of the synchronous motor, establishing an I/F (input/output) flow frequency ratio starting scheme and a sliding-mode observer rotor position and speed estimation scheme based on an extended back electromotive force model, and aiming at the problem of current and torque jitter generated by hard switching from a low-speed section I/F to a high-speed section sliding mode, providing a novel smooth switching method, so that the transition process of torque, rotating speed and current is smooth and impact-free, and the switching process can be smoothly implemented under different load conditions from no-load to rated load. The method has the advantages of low cost, high estimation precision, high speed, high real-time performance, good robustness and strong anti-interference capability, can improve the estimation precision of the permanent magnet synchronous motor position sensorless estimation algorithm, reduces the rotor estimation error, and has guiding significance for improving the estimation performance of the permanent magnet synchronous motor position sensorless vector control system.)

1. A method for improving the estimation performance of a permanent magnet synchronous motor without a position sensor is characterized by comprising the following steps:

step 1, establishing a mathematical model of a permanent magnet synchronous motor; decoupling the position information of the rotor into a motor extended back electromotive force mathematical model:

transforming the formula (1) into a two-phase static coordinate system through Park inverse transformation to obtain a mathematical model of the motor under the static two-phase coordinate system, wherein a motor stator voltage equation is as follows:

rewriting formula (1) to:

wherein u is_α、u_βIs the stator voltage component on axis of the stationary reference frame αβ_d、u_qThe direct axis voltage and quadrature axis voltage of the stator are obtained; i.e. i_d、i_qThe direct axis current and quadrature axis current of the stator are obtained;

Step 2, establishing an I/F flow frequency ratio starting mathematical model; position angle generator set position angleAnd d, carrying out dq- αβ coordinate transformation on the stator current, wherein the relation among the command position angle, the rotating speed and the acceleration is as follows:

ω^*＝∫k_ωdt (5)

starting currentAnd acceleration K_ωThe following relationship is followed:

p is a differential operator, J is a moment of inertia, K_tIn order to be the torque coefficient of the motor,estimating the torque current, T_LmaxIs the maximum load torque;

step 3, constructing a sliding mode observer based on the extended back electromotive force model according to the extended back electromotive force model of the motor:

in the formula, e_α＝-E_extsinθ_e，e_β＝E_extcosθ_eExtended electromotive force components in α - β two-phase stationary coordinate systems;the rotor position is extracted as follows:

wherein, | E_extI is the extended back EMF amplitude, Δ e is the back EMF error value, θ_eIs the actual position of the rotor;

when the angle error information is small, the above equation can be approximately equivalent to:

step 4, according to the constructed permanent magnet synchronous motor position-vector-free control system, the designated d for open-loop starting^*q^*Position angle of coordinate axisTransition to rotor position angle theta according to set coefficient_dExpressed as:

θ_cmdfor closed-loop control of angle, theta_estFor high-speed, non-inductive angle estimation, the parameter k determines the time required for the transition.

Technical Field

The invention belongs to the technical field of power electronic control, and particularly relates to a method for improving the estimation performance of a permanent magnet synchronous motor without a position sensor.

Background

In the last decade, the problem of energy shortage has restricted the development of human society. With the discovery of high-performance rare earth permanent magnet materials and the continuous development of power electronic devices, industrial automation, robots and electric automobiles are widely used in motors. Therefore, the motor is the electrical appliance with the largest electricity consumption in a plurality of energy consumption devices. The total annual power consumption can be greatly reduced by improving the energy efficiency level and the operating efficiency of the motor, and the problem of energy shortage is solved.

The speed regulation method of the alternating current motor is mainly divided into two types: direct torque control and vector control. Although the control ideas and control theories of the two types of control are different, in order to achieve high-performance control of the motor, the two control methods both need accurate rotor position and angular speed. Therefore, in the motor control system, a position sensor such as a photoelectric encoder, a rotary transformer, etc. is generally added. Mechanical position sensors, while capable of accurately providing angular information about the rotor, can also have some negative impact on the motor control system. The price of mechanical position sensors is generally high, the cost is increased when the position sensors are installed in the motor control system, and the size of the motor driver is increased. 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; 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; 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 no position sensor cannot smoothly switch from the low speed section to the medium and high speed section.

Disclosure of Invention

The invention aims to provide a smooth switching method for starting an I/F (input/output) stream frequency ratio to a sliding mode observer.

In order to achieve the purpose, the invention adopts the technical scheme that: a method for improving estimation performance of a permanent magnet synchronous motor without a position sensor comprises the following steps:

step 1, establishing a mathematical model of a permanent magnet synchronous motor; decoupling the position information of the rotor into a motor extended back electromotive force mathematical model:

transforming the formula (1) into a two-phase static coordinate system through Park inverse transformation to obtain a mathematical model of the motor under the static two-phase coordinate system, wherein a motor stator voltage equation is as follows:

rewriting formula (1) to:

wherein u is_α、u_βIs the stator voltage component on axis of the stationary reference frame αβ_d、u_qThe direct axis voltage and quadrature axis voltage of the stator are obtained; i.e. i_d、i_qThe direct axis current and quadrature axis current of the stator are obtained;

the direct axis flux linkage component and the quadrature axis flux linkage component of the stator are obtained; l is_d、L_qThe direct axis flux linkage component and the quadrature axis flux linkage component of the stator are obtained; omega_eIs the rotor speed; p is a differential operator; l is₀＝(L_d+L_q)/2，L₁＝(L_d-L_q)/2；

Step 2, establishing an I/F flow frequency ratio starting mathematical model; position angle generator set position angleAnd d, carrying out dq- αβ coordinate transformation on the stator current, wherein the relation among the command position angle, the rotating speed and the acceleration is as follows:

ω^*＝∫k_ωdt (5)

starting currentAnd acceleration K_ωThe following relationship is followed:

p is a differential operator, J is a moment of inertia, K_tIn order to be the torque coefficient of the motor,

estimating the torque current, T_LmaxIs the maximum load torque;

step 3, constructing a sliding mode observer based on the extended back electromotive force model according to the extended back electromotive force model of the motor:

in the formula, e_α＝-E_extsinθ_e，e_β＝E_extcosθ_eExtended electromotive force components in α - β two-phase stationary coordinate systems;the rotor position is extracted as follows:

wherein, | E_extI is the extended back EMF amplitude, Δ e is the back EMF error value, θ_eIs the actual position of the rotor;to estimate a rotor position;

when the angle error information is small, the above equation can be approximately equivalent to:

step 4, according to the constructed permanent magnet synchronous motor position-vector-free control system, the designated d for open-loop starting^*q^*Position angle of coordinate axisTransition to rotor position angle theta according to set coefficient_dExpressed as:

θ_cmdfor closed-loop control of angle, theta_estFor high-speed, non-inductive angle estimation, the parameter k determines the time required for the transition.

The invention has the beneficial effects that: the method can basically eliminate the motor speed jitter and the current jitter generated under the switching of two modes, and has important guiding significance for the smooth switching between different speed sections of the motor position-sensorless control system.

The invention is suitable for any system adopting a vector control strategy, and does not need an additional photoelectric encoder or a rotary transformer.

The method has the advantages of high estimation precision, high speed and high real-time performance, and can accurately estimate the position of the motor rotor in real time and stably run in the whole process.

The method has the advantages that the robustness is good, the anti-interference capability is strong, and the dynamic processes of motor starting, speed changing, sudden loading or sudden unloading and the like can not generate negative influence on the result of the method; the scheme is insensitive to the internal parameters of the motor and has strong anti-noise capability.

The method is simple to realize, and the method can be embedded into the control program as a subprogram without influencing or modifying the control program.

Drawings

FIG. 1 is a flow chart of a method for improving sensorless estimation performance of a permanent magnet synchronous motor according to an embodiment of the present invention;

FIG. 2(a) is a schematic diagram of phase current crossing points in an initial phase according to an embodiment of the present invention;

FIG. 2(b) is a schematic diagram of phase current crossing points during an acceleration phase according to an embodiment of the present invention;

fig. 3 is a topology of a rectifier in a method for real-time detection of an open circuit fault of a three-phase rectifier power tube according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The embodiment provides a soft transition switching method aiming at the problem that the position-free sensor can not be switched smoothly from a low-speed section to a medium-high speed section in the prior art, so that the transition process of torque, rotating speed and current is smooth and has no impact, and the switching process can be smoothly implemented under different load conditions from no load to rated load.

As shown in fig. 1, a method for improving estimation performance of a permanent magnet synchronous motor without a position sensor includes the following steps:

s1, completely decoupling the position information of the rotor into a motor extended back electromotive force mathematical model on the basis of the mathematical model of the permanent magnet synchronous motor,

transforming the formula (1') into a two-phase static coordinate system through Park inverse transformation to obtain a mathematical model of the motor under the static two-phase coordinate system, wherein a motor stator voltage equation is as follows:

formula (2') can be rewritten as:

wherein u is_α、u_βIs the stator voltage component on axis of the stationary reference frame αβ_d、u_qThe direct axis voltage and quadrature axis voltage of the stator are obtained; i.e. i_d、i_qThe direct axis current and quadrature axis current of the stator are obtained;the direct axis flux linkage component and the quadrature axis flux linkage component of the stator are obtained; l is_d、L_qThe direct axis flux linkage component and the quadrature axis flux linkage component of the stator are obtained; omega_eIs the rotor speed; p is a differential operator; l is₀＝(L_d+L_q)/2，L₁＝(L_d-L_q)/2；

S2, establishing an I/F flow frequency ratio starting mathematical model; position angle generator set position angleAnd d, carrying out dq- αβ coordinate transformation on the stator current, wherein the relation among the command position angle, the rotating speed and the acceleration is as follows:

ω^*＝∫k_ωdt (5′)

the larger the starting current amplitude is, the smaller the set acceleration is, the larger the disturbance tolerance of the system is, the stronger the anti-step-out capability is, and the starting current is

And acceleration K_ωThe following relationship is followed:

p is a differential operator, J is a moment of inertia, K_tIn order to be the torque coefficient of the motor,

estimating the torque current, T_LmaxIs the maximum load torque; as shown in fig. 2(a) and 2 (b);

s3, constructing the sliding mode observer based on the extended back electromotive force model according to the extended back electromotive force model of the motor, wherein as shown in FIG. 3, the mathematical model of the sliding mode observer is as follows:

in the formula, e_α＝-E_extsinθ_e，e_β＝E_extcosθ_eExtended electromotive force components in α - β two-phase stationary coordinate systems;

the rotor position is extracted as follows:

wherein, | E_extI is the extended back EMF amplitude, Δ e is the back EMF error value, θ_eIs the actual position of the rotor;

to estimate the rotor position. When the angle error information is small, the above equation is approximately equivalent to

S4, correcting the rotor position by adopting a weighting coefficient according to the constructed permanent magnet synchronous motor position-free vector control systemBy angling the transition method, i.e. d, specified for open-loop start-up^*q^*Position angle of coordinate axisTransition to rotor position angle theta according to set coefficient_dExpressed as:

θ_cmdfor closed-loop control of angle, theta_estFor high-speed, non-inductive estimation of the angle parameter, k is a key factor affecting the transition process, which determines the time required for the transition process.

Through tests, the method is applied to series products of electric vehicles and series products of industrial frequency converters, the transition process of torque, rotating speed and current is smooth and has no impact, and the switching process can be smoothly implemented under different load conditions from no load to rated load.

In the embodiment, a photoelectric encoder or a rotary transformer is omitted in the motor control system, so that the size of the motor control system is reduced, the cost of the whole system is also reduced, and the motor control system has the advantages of small environmental influence factor and low system maintenance cost. And the non-inductive algorithm is widely applied to the field of electric automobiles, and has larger influence and practical value.

The I/F flow frequency ratio control is carried out in the low-speed stage, the problem that the back electromotive force of a sliding mode observer is small when the sliding mode observer runs at low speed is solved, and the error generated by estimating the position and the speed of a rotor by extracting the back electromotive force of a motor is large is solved. The smooth switching from the low speed to the high speed has important significance for the whole automobile getting on the road of the electric automobile.

The problems of overlarge rotating speed and current vibration amplitude generated by a low-speed to high-speed motor are solved, and the smooth switching from the low speed to the high speed of a non-inductive system of the motor is realized.

It should be understood that parts of the specification not set forth in detail are well within the prior art.

Although specific embodiments of the present invention have been described above with reference to the accompanying drawings, it will be appreciated by those skilled in the art that these are merely illustrative and that various changes or modifications may be made to these embodiments without departing from the principles and spirit of the invention. The scope of the invention is only limited by the appended claims.