CN111865158A - An adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method - Google Patents

Abstract

The invention discloses a speed sensorless control method of an adaptive sliding mode gain permanent magnet synchronous motor, comprising the following steps: collecting three-phase stator currents of the motor under test, which are respectively:

,

,

; and the measured current is obtained by Clark transformation

,

; Calculate the observed current value using the motor mathematical model

,

, calculate the sliding mode gain adaptive rate K, and apply the sliding mode gain adaptive rate to the motor mathematical model in S2 to correct the current error value between the measured current value and the observed current value

, gradually approaching zero. The adaptive sliding mode gain observer adopted in the patent of the present invention can make the motor under test configure the adaptive gain factor in real time, better improve the sliding mode chattering phenomenon, and improve the observation accuracy; The current curve is smoother, the chattering content is less, and the operation is more stable.

Description

An adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method

technical field

The invention belongs to the technical field of motor control, and in particular relates to an adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method.

Background technique

The adaptive sliding mode observer control method of permanent magnet synchronous motor is a very common use method in the existing permanent magnet synchronous motor control. Sliding mode observer is a kind of dynamic system that obtains the estimated value of state variable according to the measured value of external variables (input variable and output variable) of the system, also known as state reconstructor. Sliding mode observers not only provide practical possibilities for the technical realization of state feedback, but also have practical applications in many aspects of control engineering. Sliding mode observers can obtain estimates of the internal state of a given system by measuring the input and output of the actual system. Sliding mode observers use nonlinear high-gain feedback to force the estimated state to approximate the hyperplane, making the estimated output equal to the measured output. By building a permanent magnet synchronous motor adaptive sliding mode observer control experimental platform, the performance of the control system is tested by collecting and analyzing relevant data according to the operation of the motor under different working conditions. As shown in Figure 1, the traditional adaptive sliding mode observer control method consists of the measured current output link of the motor, the observed current output link estimated by the motor model, and the sliding mode adaptive control part, and the error value is fed back through a closed-loop method. into the motor model. The existing PMSM adaptive sliding mode observer control method has the following shortcomings: 1. The sliding mode chattering in the sliding mode observation control system is relatively large; 2. The phase current output is unstable, and there is a phenomenon around the peak value of the phase current curve. Sawtooth waveform; 3. The observation accuracy of the sliding mode observer is low; 4. A fixed adaptive factor is used in the whole system, however, the adaptive sliding mode gain is not used to make the adaptive factor change according to the change of the control system. Variety.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method which can better improve the sliding mode chattering phenomenon and improve the observation accuracy.

To achieve the above object, the present invention adopts the following technical solutions:

An adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method, comprising the following steps: S1, collecting three-phase stator currents of the motor under test through a current sensor, which are respectively i _a , i _b , and _ic ; Phase stator current obtains measured current i _α , i _β through Clark transformation; finally output its measured current;

S2. Calculate the observed current values i _α ^* and i _β ^* by using the motor mathematical model,

S3. Calculate the sliding mode gain adaptive rate K, and apply the sliding mode gain adaptive rate to the motor mathematical model in S2 to correct the current error value δ between the measured current value and the observed current value, so that it gradually approaches at zero.

其中i_α ^*、i_β ^*分别为观测电流分量，

分别为反电动势分量，Z_α、Z_β为滑模控制器的输出校正因子分量，R为定子电阻，L为定子电感，u_α、u_β为α、β坐标系上的定子电压；

利用电机数学模型估算出其中的观测电流值i_α ^*、i_β ^*，然后将自适应增益因子反馈至电机模型中，判断测量电流和观测电流的差值大小，并通过自适应增益因子来校正测量电流和观测电流的差值，使其逐渐接近于零，使观测电流更加接近测量电流。Further, the motor mathematical model formula described in S2 is:

where i _α ^* and i _β ^* are the observed current components, respectively,

are the back electromotive force components respectively, Z _α and Z _β are the output correction factor components of the sliding mode controller, R is the stator resistance, L is the stator inductance, and u _α and u _β are the stator voltages on the α and β coordinate systems;

The observed current values i _α ^* and i _β ^* are estimated by the motor mathematical model, and then the adaptive gain factor is fed back to the motor model to judge the difference between the measured current and the observed current, and correct it through the adaptive gain factor The difference between the measured current and the observed current is gradually approached to zero, so that the observed current is closer to the measured current.

为了克服该控制系统中存在的电流误差，通过引入滑模增益自适应因子，利用输出误差来驱动自适应结构，得出滑模增益自适应率K，根据公式

使电流输出误差随着自适应率变化而变化。在自适应率的作用下能够不断修正待估计参数，使滑模观测模型输出误差趋向于零。Further, the sliding mode observer control is required to calculate the sliding mode gain adaptive rate K in S3. When the sliding mode observer control is used, it is observed that the output waveform of the motor current has a large ripple chattering in the sampling frequency period. Chattering is the real error δ existing between the observed current and the measured current when the permanent magnet synchronous motor is running. The formula is

In order to overcome the current error existing in the control system, by introducing a sliding mode gain adaptive factor and using the output error to drive the adaptive structure, the sliding mode gain adaptive rate K is obtained, according to the formula

Make the current output error vary with the adaptation rate. Under the action of the adaptive rate, the parameters to be estimated can be continuously corrected, so that the output error of the sliding mode observation model tends to zero.

Essentially, the constant boundary layer thickness is the root cause of the poor performance of the saturation function. Therefore, in order to improve the control performance of the saturation function, a continuously variable adaptive coefficient must be found to control the change of the function, so that the thickness of the boundary layer can be narrowed with the convergence of the system state trajectory, and finally coincide with the switching surface to achieve the system trajectory Asymptotic convergence to the given switching plane. When the control function is constantly changing, there is an approach angle between it and the abscissa axis. The approach angle is the angle between the system state trajectory and the switching plane. It decreases as the state trajectory approaches the switching plane, so the approach angle is It is the most intuitive variable to measure the degree of convergence of the state trajectory, so the approach angle is used as the adaptive coefficient of the function change, and the boundary layer thickness function is constructed.

By calculating the effective value of the measured current, the intrinsic relationship between the current effective value, the current error value and the adaptive factor is found out, and the sliding mode gain adaptive rate is obtained, thereby effectively reducing the current error in the control system.

其中

为整个周期数内的电流有效值。其中r为函数关系式的自适应率系数。利用电流误差值(δ)和电流有效值

之间存在的变化关系，确定系数r的值，使自适应率一直控制在固定范围内，从而有效克服测量电流与观测电流之间的误差，使整个滑模控制系统处于稳定精准的观测状态。The formula for calculating the sliding mode adaptive rate K in S3 is:

in

is the rms value of the current over the number of cycles. where r is the adaptive rate coefficient of the functional relationship. Utilize current error value (δ) and current rms value

The value of the coefficient r is determined, so that the adaptive rate is always controlled within a fixed range, so as to effectively overcome the error between the measured current and the observed current, so that the entire sliding mode control system is in a stable and accurate observation state.

的计算公式为：

其中

_j为数据样本指数；p为周期循环次数；M为滤波后同步信号定义的周期中采样数；M_p为循环数中采样点的个数；m为起始采样点指数；_mp为循环次数的起始采样点指数；N为周期数(由选定的同步源信号定义)；

为每个周期内的电流有效值。Further, the effective value of the current in the whole number of cycles

The calculation formula is:

in

_j is the data sample index; p is the number of cycles; M is the number of samples in the cycle defined by the filtered synchronization signal; M _p is the number of sampling points in the cycle; m is the index of the initial sampling point; _mp is the number of cycles Start sampling point index; N is the number of cycles (defined by the selected synchronization source signal);

is the rms value of the current in each cycle.

可以根据上述公式并在仿真过程中使永磁同步电机在不同的工况下运行，从而求出。RMS value of phase current under different working conditions

According to the above formula and in the simulation process, the permanent magnet synchronous motor is operated under different working conditions, so as to obtain.

In the present invention, the sliding mode gain adaptive factor is introduced by using the current error value between the measured current and the observed current to obtain the sliding mode gain adaptive rate K, and then the adaptive gain factor can change with the magnitude of the current error in the control system , can better make the current error smaller and approach zero, make the measured current closer to the actual current, and better improve the sliding mode chattering phenomenon.

The method of the present invention has the following advantages:

1. Compared with the traditional sliding mode observer control method. The self-adaptive sliding mode gain observer adopted in the patent of the present invention can make the motor under test configure the self-adaptive gain factor in real time, better improve the sliding mode chattering phenomenon, and improve the observation accuracy.

2. Compared with the traditional sliding mode observer, the current curve obtained by the adaptive sliding mode gain observer is smoother, with less chattering content and more stable operation.

Description of drawings

Figure 1 is a schematic diagram of the control structure of a traditional permanent magnet synchronous motor adaptive sliding mode observer;

FIG. 2 is a design diagram of the speed sensorless control of an adaptive synovial gain permanent magnet synchronous motor according to the present invention;

Fig. 3 is the control flow chart of the present invention;

Figure 4 is the stator current waveform when the speed is 1500r/min;

Figure 5 shows the waveform changes of the actual speed and the observed speed under the steady-state speed of 1500r/min;

Figure 6 shows the rotor position waveform and error when the speed is 1500r/min.

Detailed ways

In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved more clearly, the technical solutions of the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only the present invention. Some examples, but not all examples. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

As shown in Figure 2, an adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method. It includes: the measured current output link of the motor, the observed current output link estimated by the motor model, and the adaptive sliding mode gain control part. In order to match the measured current and the observed current, the error value is fed back to the motor model through a closed-loop method. Thereby correcting the current error value. The specific plan is implemented as follows:

S1, the measurement current output link of the motor. The three-phase stator currents of the motor under test are collected by the current sensor, which are i _a , i _b , and _ic respectively; the three-phase stator currents are converted by Clark to obtain the measured currents i _α , i _β ; finally, the measured currents are output;

S2. The observed current output link estimated by the motor model. Calculate the observed current values i _α ^* and i _β ^* by using the motor mathematical model,

其中i_α ^*、i_β ^*分别为观测电流分量，

分别为反电动势分量，Z_α、Z_β为滑模控制器的输出校正因子分量，R为定子电阻，L为定子电感，u_α、u_β为α、β坐标系上的定子电压；

The formula of the motor mathematical model is:

where i _α ^* and i _β ^* are the observed current components, respectively,

are the back electromotive force components respectively, Z _α and Z _β are the output correction factor components of the sliding mode controller, R is the stator resistance, L is the stator inductance, and u _α and u _β are the stator voltages on the α and β coordinate systems;

It can be seen from the formula that the adaptive gain factor is fed back to the motor model through the sliding mode gain adaptive rate K, the difference between the measured current and the observed current is judged, and the difference between the measured current and the observed current is corrected by the adaptive gain factor. , gradually approaching zero.

其中

为整个周期数内的电流有效值，

其中r为函数关系式的自适应率系数。利用电流误差值(δ)和电流有效值

之间存在的变化关系，确定系数r的值，使自适应率一直控制在固定范围内，从而有效克服测量电流与观测电流之间的误差，使整个滑模控制系统处于稳定精准的观测状态。S3, adaptive sliding mode gain control. Calculate the sliding mode gain adaptive rate K, use the sliding mode observer control during calculation, the formula is

in

is the rms value of the current over the number of cycles,

where r is the adaptive rate coefficient of the functional relationship. Utilize current error value (δ) and current rms value

The value of the coefficient r is determined, so that the adaptive rate is always controlled within a fixed range, so as to effectively overcome the error between the measured current and the observed current, so that the entire sliding mode control system is in a stable and accurate observation state.

的计算公式为：

其中

j为数据样本指数；p为周期循环次数；M为滤波后同步信号定义的周期中采样数；M_p为循环数中采样点的个数；m为起始采样点指数；m_p为循环次数的起始采样点指数；N为周期数(由选定的同步源信号定义)；

为每个周期内的电流有效值。Current rms value over the stated number of cycles

The calculation formula is:

in

j is the data sample index; p is the number of cycles; M is the number of samples in the cycle defined by the synchronous signal after filtering; M _p is the number of sampling points in the cycle number; m is the index of the initial sampling point; m _p is the number of cycles The index of the starting sampling point; N is the number of cycles (defined by the selected synchronization source signal);

is the rms value of the current in each cycle.

将滑模增益自适应率应用到S2中的电机数学模型中用来校正测量电流值和观测电流值之间的电流误差值δ，使其逐渐接近于零。此时滑模增益因子可以根据控制系统搞得变化而变化，不在是固定不变，更好的提高了系统的观测精度。After calculating the sliding mode gain adaptation rate K, through the formula

The sliding mode gain adaptation rate is applied to the motor mathematical model in S2 to correct the current error value δ between the measured current value and the observed current value, making it gradually approaching zero. At this time, the sliding mode gain factor can be changed according to the change of the control system, not fixed, and the observation accuracy of the system is better improved.

Figure 3 is a specific control flow chart of the present invention, wherein before implementing the steps in Figure 2, the stator voltage value of the motor is input in the computer input interface, the computer sends the electronic voltage value to the motor controller, and the controller drives the motor Operates and obtains the measured current value through the current sensor.

In order to verify the proposed sensorless control system of permanent magnet synchronous motor based on adaptive sliding mode observer, the method of the present invention is adopted, and a simulation model is built according to the control system.

Table 1 Specifications of Permanent Magnet Synchronous Motors

Experimental results:

Figure 4 shows the A-phase stator current waveform obtained by using the adaptive sliding mode gain observer and the traditional sliding mode observer at a speed of 1500 r/min. It can be seen from the simulation results that at a certain rotational speed, the simulated waveform obtained by the adaptive sliding mode gain observer has a small value of chattering amplitude, which effectively weakens the chattering.

As shown in Figure 5, the motor speed waveform at steady state is obtained by using the adaptive sliding mode gain observer and the traditional sliding mode observer at a speed of 1500 r/min. By comparison, it can be seen that the speed error obtained by the traditional sliding mode observer is at least 8r/min, and the speed error obtained by the adaptive sliding mode gain observer is 5r/min. At the same time, the speed curve obtained by the adaptive sliding mode gain observer is chattering. With less content, it has higher observation accuracy.

Figure 6 shows the target rotor position, the observed rotor position and the rotor position error waveforms obtained by using the adaptive sliding mode gain observer and the traditional sliding mode observer at a rotational speed of 1500 r/min. Through waveform comparison, it is found that the observed rotor position jitter amplitude value and rotor position error of the traditional sliding mode observer are large, and the adaptive sliding mode gain observer effectively improves the observation accuracy, weakens the jitter amplitude value and reduces the rotor position error. , with good dynamic performance.

Claims (5)

1. an adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method, is characterized in that, comprises the following steps: S1. Collect the three-phase stator currents of the motor under test, which are respectively i _a , i _b , and _ic ; and obtain the measured currents i _α and i _β through Clark transformation; S2. Calculate the observed current values i _α ^* and i _β ^* by using the motor mathematical model, S3. Calculate the sliding mode gain adaptive rate K, and apply the sliding mode gain adaptive rate to the motor mathematical model in S2 to correct the current error value δ between the measured current value and the observed current value, so that it gradually approaches at zero. 2. a kind of adaptive sliding mode gain permanent magnet synchronous motor sensorless control method according to claim 1, is characterized in that, described in S2, the motor mathematical model formula is:

where i _α ^* and i _β ^* are the observed current components, respectively,

are the back electromotive force components respectively, Z _α and Z _β are the output correction factor components of the sliding mode controller, R is the stator resistance, L is the stator inductance, and u _α and u _β are the stator voltages on the α and β coordinate systems;

3. a kind of adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method according to claim 1 and 2, is characterized in that, in S3, the calculation formula of sliding mode adaptive rate K is:

in

is the rms value of the current over the number of cycles. 4. a kind of adaptive sliding mode gain permanent magnet synchronous motor sensorless control method according to claim 1, is characterized in that, the calculation formula of current error value δ in S3 is:

5. a kind of adaptive sliding mode gain permanent magnet synchronous motor speed sensorless control method according to claim 3, is characterized in that, the current effective value in described whole cycle number

The calculation formula is:

in

j is the data sample index; p is the number of cycles; M is the number of samples in the cycle defined by the synchronous signal after filtering; M _p is the number of sampling points in the cycle number; m is the index of the initial sampling point; m _p is the number of cycles The index of the starting sampling point; N is the number of cycles;

is the rms value of the current in each cycle.

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