阅读说明：本技术 磁链角度限幅处理、无速度传感器矢量控制方法及系统 (Flux linkage angle amplitude limiting processing and velocity sensorless vector control method and system ) 是由 熊志伟 张宁 于 2019-11-05 设计创作，主要内容包括：本申请提供了一种磁链角度限幅处理、无速度传感器矢量控制方法及系统,获取当前采样周期的电机频率,当电机频率小于预设阈值频率时,需要对估算的转子磁链进行转子磁链角度限幅,首先根据估算的转子磁链计算出预测的转子磁链角度,根据上一采样周期的转子磁链角度与预测的转子磁链角度得到转子磁链角度偏差值,根据转子磁链角度偏差值与角度变化上下限值确定当前采样周期的转子磁链角度变化量,根据当前采样周期的转子磁链角度变化量与上一次采样周期的转子磁链角度得到当前采样周期的转子磁链角度。通过对小转矩低频下的转子磁链角度进行限幅处理,解决小转矩超低频下电机输出转矩波动很大、电机正反转异常的问题。(The application provides a flux linkage angle amplitude limiting processing and velocity sensor-free vector control method and system, the motor frequency of a current sampling period is obtained, when the motor frequency is smaller than a preset threshold frequency, rotor flux linkage angle amplitude limiting needs to be carried out on an estimated rotor flux linkage, a predicted rotor flux linkage angle is calculated according to the estimated rotor flux linkage at first, a rotor flux linkage angle deviation value is obtained according to a rotor flux linkage angle of a previous sampling period and the predicted rotor flux linkage angle, the rotor flux linkage angle variation of the current sampling period is determined according to the rotor flux linkage angle deviation value and an upper limit value and a lower limit value of the angle variation, and the rotor flux linkage angle of the current sampling period is obtained according to the rotor flux linkage angle variation of the current sampling period and the rotor flux linkage angle of the previous sampling period. By carrying out amplitude limiting processing on the rotor flux linkage angle under low torque and low frequency, the problems that the output torque of the motor is greatly fluctuated and the motor rotates reversely and abnormally under low torque and ultralow frequency are solved.)

1. A rotor flux linkage angle amplitude limiting processing method is applied to vector control of a low-torque low-frequency down converter without a speed sensor, and is characterized by comprising the following steps of:

acquiring the motor frequency of the current sampling period;

when the motor frequency is smaller than a preset threshold frequency, calculating a predicted rotor flux linkage angle according to the estimated rotor flux linkage;

obtaining a rotor flux linkage angle deviation value according to the rotor flux linkage angle of the last sampling period and the predicted rotor flux linkage angle;

determining the rotor flux linkage angle variation of the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle variation;

and obtaining the rotor flux linkage angle of the current sampling period according to the rotor flux linkage angle variable quantity of the current sampling period and the rotor flux linkage angle of the last sampling period.

2. The method of claim 1, wherein the upper and lower limit values of the angular change are obtained by:

obtaining corresponding theoretical rotor flux linkage angle variation according to the motor frequency of the current sampling period;

and obtaining an angle change upper limit value and an angle change lower limit value according to a preset angle adjusting value and the theoretical rotor flux linkage angle variation.

3. The method of claim 2, wherein obtaining the upper and lower limit values of the angle change according to the preset angle adjustment value and the theoretical rotor flux linkage angle change amount comprises:

adding the theoretical rotor flux linkage angle variation and the preset angle adjusting value to obtain an angle variation upper limit value;

subtracting the theoretical rotor flux linkage angle variation from the preset angle adjusting value to obtain an angle variation lower limit value;

and obtaining the upper and lower limit values of the angle change according to the upper limit value of the angle change and the lower limit value of the angle change.

4. The method of claim 3, wherein determining the rotor flux linkage angle variation for the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle variation comprises:

when the rotor flux linkage angle deviation value exceeds the angle change upper limit value, determining the rotor flux linkage angle variation of the current sampling period as the angle change upper limit value;

when the rotor flux linkage angle deviation value exceeds the angle change lower limit value, determining the rotor flux linkage angle variation of the current sampling period as the angle change lower limit value;

and when the rotor flux linkage angle deviation value is within the numerical range of the upper limit value and the lower limit value of the angle change, determining the rotor flux linkage angle change amount of the current sampling period as the rotor flux linkage angle deviation value.

5. The method of any of claims 1 to 4, wherein calculating the predicted rotor flux angle from the estimated rotor flux when the motor frequency is less than a predetermined threshold frequency comprises:

when the motor frequency is smaller than a preset threshold frequency, low-pass filtering is carried out on the estimated rotor flux linkage, and the filtered rotor flux linkage is output;

and calculating the predicted rotor flux linkage angle according to the filtered rotor flux linkage.

6. The method of claim 5, wherein low pass filtering the rotor flux linkage when the motor frequency is less than a predetermined threshold frequency, and outputting the filtered rotor flux linkage comprises:

when the motor frequency is smaller than a preset threshold frequency, taking 2 times of the preset threshold frequency as a cut-off frequency of a low-pass filter;

obtaining a low-pass filter coefficient according to the cut-off frequency;

and filtering the estimated rotor flux linkage according to the low-pass filtering coefficient to obtain the filtered rotor flux linkage.

7. The method of claim 1, wherein the rotor flux angle is calculated from the estimated rotor flux as the rotor flux angle for the current sampling period when the motor frequency is greater than a predetermined threshold frequency.

8. A small-torque low-frequency down converter velocity-sensorless vector control method is characterized by comprising the following steps:

performing speed estimation on the rotor flux linkage angle obtained by the method according to any one of claims 1 to 7 to obtain a corresponding rotor rotation speed;

obtaining a torque set value according to the rotating speed of the rotor;

outputting a deviation voltage signal through a PI regulator according to the torque set value and the received torque feedback value;

obtaining a voltage vector angle according to the deviation voltage signal;

obtaining a wave sending angle of SVPWM according to the rotor flux linkage angle and the voltage vector angle;

and obtaining a driving signal acted on the motor according to the wave sending angle of the SVPWM.

9. The method of claim 8, further comprising:

acquiring three-phase current of a motor;

reconstructing the stator voltage according to the collected bus voltage and the PWM duty ratio combination of the three-phase frequency converter;

converting the obtained three-phase current and the reconstructed stator voltage by CLARKE to obtain current and voltage under a two-phase static coordinate;

converting the current and the voltage under the two-phase static coordinate to obtain an exciting current, an exciting voltage, a torque current and a torque voltage under a rotating coordinate system;

sending the current and voltage, the excitation current, the excitation voltage, the torque current and the torque voltage under the two-phase static coordinate to a flux linkage observer to obtain an estimated rotor flux linkage under the static coordinate;

performing the method according to any of claims 1 to 7 on the basis of the estimated rotor flux linkage to obtain a rotor flux linkage angle.

10. A rotor flux linkage angle clipping processing system, comprising:

the frequency acquisition module is used for acquiring the motor frequency of the current sampling period;

the predicted angle calculating module is used for calculating a predicted rotor flux linkage angle according to the estimated rotor flux linkage when the motor frequency is smaller than a preset threshold frequency;

the deviation value obtaining module is used for obtaining a rotor flux linkage angle deviation value according to the rotor flux linkage angle of the previous sampling period and the predicted rotor flux linkage angle;

the variable quantity obtaining module is used for determining the rotor flux linkage angle variable quantity of the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle change;

and the flux linkage angle determining module is used for obtaining the rotor flux linkage angle of the current sampling period according to the rotor flux linkage angle variation of the current sampling period and the rotor flux linkage angle of the last sampling period.

Technical Field

The invention relates to the technical field of motor driving, in particular to a flux linkage angle amplitude limiting processing and velocity sensorless vector control method and system.

Background

Generally, the speed sensorless vector control of the frequency converter comprises two control modes, namely a speed mode and a torque mode. The speed mode is the frequency converter's purpose of controlling the rotational speed of the motor, at which time the torque of the motor must be adjusted in order to maintain this speed. The torque mode is that the frequency converter aims at controlling the output torque of the motor, and the speed is related to the external load and is not related to the torque.

In the torque mode, the motor speed is determined by the load, the load is larger than the given output torque, the motor speed can be reduced, the given output torque is larger than the load, the speed can be increased, and under the condition of small torque, when the load is increased, the rotating speed of the motor can be reduced or even locked. The frequency converter realizes speed regulation by changing the power supply frequency of the motor, and the motor is easy to generate low-frequency vibration at low speed because the frequency or the voltage of the motor for the frequency converter is very low when the motor runs at low speed. Aiming at the problems that the open-loop vector control is operated at low speed, because the output frequency and the output voltage of a torque mode down converter with small torque and ultralow frequency (less than 20 percent of the rated torque of a motor and less than 1 percent of the rated frequency of the motor) are very small, the estimated rotating speed and the rotor flux linkage at low speed are further sensitive to the change of motor parameters, particularly the change of a stator resistor, and the estimated rotating speed and flux linkage error caused by the nonlinear error of a low-speed frequency converter, such as sampling error, calculation error, dead zone, temperature and the like, for example, the untimely processing can cause a series of problems that the output torque of the motor is very large in fluctuation, the motor is abnormal in positive and negative rotation, the motor can not rotate and even flies, and the like.

At present, a plurality of open-loop vector control processing methods are provided for a small-torque ultralow-frequency down converter, and the method mainly comprises software algorithm and hardware optimization, wherein the software algorithm comprises a high-performance flux linkage observation and speed identification algorithm, an online high-performance motor parameter identification algorithm, an adaptive compensation algorithm and the like, the high-performance flux linkage observation and speed identification algorithm, a low-frequency signal injection method, a high-frequency signal injection method, model reference adaptive method, a full-order flux linkage observer, a neural network method, an extended Kalman filter method and the like are used, and the algorithms aim to improve the precision of flux linkage observation and speed identification and simultaneously reduce the sensitivity to motor parameter errors. The online high-performance motor parameter identification algorithm detects motor parameters in real time and improves the motor parameter identification precision. Adaptive compensation algorithms, such as: stator voltage compensation, dead-time compensation, circuit delay compensation, temperature drift correction, and the like. The software algorithm is complex, large in processing capacity and high in implementation difficulty. The hardware optimization is optimized from a hardware circuit, the sampling precision is improved, the anti-interference capability is improved, the hardware driving delay is reduced, and a high-performance digital processor is used. But hardware optimized circuits are costly and add complexity to the circuit.

Therefore, a scheme for stabilizing the torque output of the low-torque low-frequency converter is urgently needed.

Disclosure of Invention

The invention mainly solves the technical problems that the output torque of a motor has large fluctuation under the condition of small torque and ultralow frequency, the motor rotates abnormally in the positive and negative directions, and the motor cannot rotate or even fly, and provides the rotor flux linkage angle amplitude limiting processing which is suitable for the condition of small torque and ultralow frequency, is simple to operate and is easy to execute.

According to a first aspect, an embodiment provides a velocity-sensor-less vector control applied to a low-torque low-frequency down-converter, comprising:

acquiring the motor frequency of the current sampling period;

when the motor frequency is smaller than a preset threshold frequency, calculating a predicted rotor flux linkage angle according to the estimated rotor flux linkage;

obtaining a rotor flux linkage angle deviation value according to the rotor flux linkage angle of the last sampling period and the predicted rotor flux linkage angle;

determining the rotor flux linkage angle variation of the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle variation;

and obtaining the rotor flux linkage angle of the current sampling period according to the rotor flux linkage angle variable quantity of the current sampling period and the rotor flux linkage angle of the last sampling period.

In one possible implementation manner, the upper and lower limit values of the angle change are obtained by:

obtaining corresponding theoretical rotor flux linkage angle variation according to the motor frequency of the current sampling period;

and obtaining an angle change upper limit value and an angle change lower limit value according to a preset angle adjusting value and the theoretical rotor flux linkage angle variation.

In one possible implementation manner, the obtaining an upper limit value and a lower limit value of an angle change according to a preset angle adjustment value and the theoretical rotor flux linkage angle variation includes:

adding the theoretical rotor flux linkage angle variation and the preset angle adjusting value to obtain an angle variation upper limit value;

subtracting the theoretical rotor flux linkage angle variation from the preset angle adjusting value to obtain an angle variation lower limit value;

and obtaining the upper and lower limit values of the angle change according to the upper limit value of the angle change and the lower limit value of the angle change.

In one possible implementation manner, the determining the rotor flux linkage angle variation amount of the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle variation includes:

when the rotor flux linkage angle deviation value exceeds the angle change upper limit value, determining the rotor flux linkage angle variation of the current sampling period as the angle change upper limit value;

when the rotor flux linkage angle deviation value exceeds the angle change lower limit value, determining the rotor flux linkage angle variation of the current sampling period as the angle change lower limit value;

and when the rotor flux linkage angle deviation value is within the numerical range of the upper limit value and the lower limit value of the angle change, determining the rotor flux linkage angle change amount of the current sampling period as the rotor flux linkage angle deviation value.

In one possible implementation manner, the calculating the predicted rotor flux linkage angle when the motor frequency is less than a preset threshold frequency includes:

when the motor frequency is smaller than a preset threshold frequency, low-pass filtering is carried out on the estimated rotor flux linkage, and the filtered rotor flux linkage is output;

and calculating the predicted rotor flux linkage angle according to the filtered rotor flux linkage.

In one possible implementation manner, the low-pass filtering the rotor flux linkage when the motor frequency is less than a preset threshold frequency, and outputting the filtered rotor flux linkage includes:

when the motor frequency is smaller than a preset threshold frequency, taking 2 times of the preset threshold frequency as a cut-off frequency of a low-pass filter;

obtaining a low-pass filter coefficient according to the cut-off frequency;

and filtering the estimated rotor flux linkage according to the low-pass filtering coefficient to obtain the filtered rotor flux linkage.

In one possible implementation manner, when the motor frequency is greater than a preset threshold frequency, a rotor flux linkage angle is calculated according to the estimated rotor flux linkage and is used as the rotor flux linkage angle of the current sampling period.

According to a second aspect, an embodiment provides a small-torque low-frequency down-converter velocity-sensorless vector control method, including:

carrying out speed estimation on the rotor flux linkage angle obtained by the rotor flux linkage angle amplitude limiting processing method to obtain a corresponding rotor rotating speed;

obtaining a torque set value according to the rotating speed of the rotor;

outputting a deviation voltage signal through a PI regulator according to the torque set value and the received torque feedback value;

obtaining a voltage vector angle according to the deviation voltage signal;

obtaining a wave sending angle of SVPWM according to the rotor flux linkage angle and the voltage vector angle;

and obtaining a driving signal acted on the motor according to the wave sending angle of the SVPWM.

In one possible implementation manner, the method for vector control of a small-torque low-frequency down converter without a velocity sensor further includes:

acquiring three-phase current of a motor;

reconstructing the stator voltage according to the collected bus voltage and the PWM duty ratio combination of the three-phase frequency converter;

converting the obtained three-phase current and the reconstructed stator voltage by CLARKE to obtain current and voltage under a two-phase static coordinate;

converting the current and the voltage under the two-phase static coordinate to obtain an exciting current, an exciting voltage, a torque current and a torque voltage under a rotating coordinate system;

sending the current and voltage, the excitation current, the excitation voltage, the torque current and the torque voltage under the two-phase static coordinate to a flux linkage observer to obtain an estimated rotor flux linkage under the static coordinate;

and carrying out the rotor flux linkage angle amplitude limiting processing method according to the estimated rotor flux linkage to obtain the rotor flux linkage angle.

According to a third aspect, an embodiment provides a rotor flux linkage angle amplitude limiting processing system, including:

the frequency acquisition module is used for acquiring the motor frequency of the current sampling period;

the predicted angle calculating module is used for calculating a predicted rotor flux linkage angle according to the estimated rotor flux linkage when the motor frequency is smaller than a preset threshold frequency;

the deviation value obtaining module is used for obtaining a rotor flux linkage angle deviation value according to the rotor flux linkage angle of the previous sampling period and the predicted rotor flux linkage angle;

the variable quantity obtaining module is used for determining the rotor flux linkage angle variable quantity of the current sampling period according to the rotor flux linkage angle deviation value and the upper and lower limit values of the angle change;

and the flux linkage angle determining module is used for obtaining the rotor flux linkage angle of the current sampling period according to the rotor flux linkage angle variation of the current sampling period and the rotor flux linkage angle of the last sampling period.

The beneficial effect of this application is:

the application provides a flux linkage angle amplitude limiting processing method obtains current sampling period's motor frequency, works as when motor frequency is less than preset threshold frequency, needs carry out rotor flux linkage angle amplitude limiting to the rotor flux linkage of estimation, at first calculates the rotor flux linkage angle of prediction according to the rotor flux linkage of estimation, then according to last sampling period's rotor flux linkage angle with the rotor flux linkage angle of prediction obtains rotor flux linkage angle deviation value, then according to rotor flux linkage angle deviation value and the upper and lower limit value of angular variation confirm current sampling period's rotor flux linkage angle variation, obtain current sampling period's rotor flux linkage angle according to current sampling period's rotor flux linkage angle variation and last sampling period's rotor flux linkage angle at last. By carrying out amplitude limiting processing on the rotor flux linkage angle under low torque and low frequency, the problems that the output torque of the motor is greatly fluctuated, the motor rotates in the forward and reverse directions abnormally, and the motor cannot rotate or even fly under low torque and ultralow frequency are solved, so that the output torque is small in fluctuation, the torque output is stable, the operation is simple, and the execution is easy.

The application provides a rotor flux linkage angle amplitude limiting processing system includes: the device comprises a frequency acquisition module, a predicted angle calculation module and a variable acquisition module, wherein the frequency acquisition module is used for acquiring the motor frequency of the current sampling period, the predicted rotor flux angle is calculated according to the estimated rotor flux when the motor frequency is smaller than a preset threshold frequency, the variable acquisition module is used for acquiring the rotor flux angle deviation value according to the rotor flux angle of the last sampling period and the predicted rotor flux angle, the variable acquisition module is used for determining the rotor flux angle variable quantity of the current sampling period according to the rotor flux angle deviation value and the upper and lower limit values of the angle change, and the flux angle determination module is used for acquiring the rotor flux angle of the current sampling period according to the rotor flux angle variable quantity of the current sampling period and the rotor flux angle of the last sampling period. By carrying out amplitude limiting processing on the rotor flux linkage angle under low torque and low frequency, the problems that the output torque of the motor is greatly fluctuated, the motor rotates in the forward and reverse directions abnormally, and the motor cannot rotate or even fly under low torque and ultralow frequency are solved, so that the output torque is small in fluctuation, the torque output is stable, the operation is simple, and the execution is easy.

Drawings

Fig. 1 is a schematic flow chart of a rotor flux linkage angle amplitude limiting processing method according to an embodiment of the present invention;

FIG. 2 is a schematic flow chart of a method for calculating a predicted rotor flux linkage angle according to an embodiment of the present invention;

fig. 3 is a schematic flow chart of a rotor flux linkage filtering method according to an embodiment of the present invention;

fig. 4 is a schematic flow chart of a method for acquiring upper and lower limit values of angle change according to an embodiment of the present invention;

fig. 5 is a schematic flow chart of another method for acquiring upper and lower limit values of angle change according to an embodiment of the present invention;

fig. 6 is a schematic flow chart of a method for obtaining a rotor flux linkage angle variation according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a rotor flux linkage angle amplitude limiting processing system according to an embodiment of the present invention;

FIG. 8 is a schematic block diagram of an open-loop torque control of a frequency converter in accordance with an embodiment of the present invention;

fig. 9 is a schematic flow chart of a vector control method for a low-torque low-frequency down converter without a velocity sensor according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.

Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.

Under the vector control of a non-speed sensor of the frequency converter, the frequency of the output voltage of the frequency converter is low, the torque output by the control motor is small, the torque of the load rotation is small, when the load is increased, the rotating speed of the motor is reduced, and the motor stalling can occur under the condition that the load is not moved. The speed regulation principle of the frequency converter is mainly limited by four factors of the rotating speed n of the asynchronous motor, the frequency f of the asynchronous motor, the slip ratio s of the motor and the pole pair number p of the motor. The rotating speed n is in direct proportion to the frequency f, the rotating speed of the motor can be changed by only changing the frequency f, and when the frequency f is changed within the range of 0-50Hz, the rotating speed adjusting range of the motor is very wide. The variable frequency speed regulation is realized by changing the power supply frequency of the motor. The AC-DC-AC mode is mainly adopted, and the industrial frequency AC power supply is converted into the DC power supply through the rectifier, and then the DC power supply is converted into the AC power supply with controllable frequency and voltage to supply to the motor. The circuit of the frequency converter generally consists of 4 parts of rectification, intermediate direct current link, inversion and control. The rectification part is a three-phase bridge type uncontrollable rectifier, the inversion part is an IGBT three-phase bridge type inverter, the output is PWM waveform, and the middle direct current link is filtering, direct current energy storage and reactive power buffering.

In the embodiment of the invention, under the condition of low torque and ultralow frequency, the frequency converter runs, on the premise of not using special processing such as high-complexity high-difficulty flux linkage identification, a speed identification algorithm or a compensation algorithm, the rotor flux linkage angle is difficult to estimate, the estimated rotor flux linkage angle has large fluctuation, which causes large fluctuation and even abnormity of the output torque, frequency and the like of the frequency converter, and on the occasion of open-loop torque control of most frequency converters, the requirement on torque fluctuation is higher than the requirement on torque precision under the low torque and ultralow frequency.