CN114865971A - A speed sensorless control method of PMSM driven by MMC variable frequency - Google Patents

Abstract

The invention discloses a PMSM (permanent magnet synchronous motor) non-speed sensor control method driven by MMC (modular multilevel converter) variable frequency, belonging to the field of alternating current speed regulation. The method for multiplexing the high-frequency signal and the weighting function in the speed sensorless control system based on the MMC driving permanent magnet synchronous motor specifically comprises the following steps: the high-frequency signals in the pulse vibration high-frequency voltage injection method without the speed sensor at the zero low-speed stage and the high-frequency signals required by the capacitor voltage fluctuation of the suppression sub-module are multiplexed, and simultaneously, along with the increase of the rotating speed of the PMSM (permanent magnet synchronous motor), namely the increase of the system frequency, a weighting function required by the cut-off of the injected high-frequency signals and a weighting function required by the switching of the pulse vibration high-frequency voltage injection method without the speed sensor into the sliding mode observer are multiplexed, so that the system control structure is simplified, and the cost is reduced. Finally, the system control of the permanent magnet synchronous motor based on MMC driving in the full speed range can be realized.

Description

A speed sensorless control method of PMSM driven by MMC variable frequency

manual

A speed sensorless control method of PMSM driven by MMC variable frequency

technical field

The invention relates to the field of AC speed regulation, and more particularly, to a speed sensorless speed sensor based on a modular multilevel converter (Modular Multilevel Converter, MMC) driving a permanent magnet synchronous motor (Permanent Magnetic Synchronous Machine, PMSM) in a full speed range A method of multiplexing the high frequency signal of a control system with a weighting function.

Background technique

In recent decades, with the continuous improvement of the level of industrialization and the rapid development of permanent magnet materials, power electronic technology and motor control theory, permanent magnet synchronous motors have been widely used in CNC machine tools, aerospace and industrial applications due to their superior performance and firmness. Robots and other fields are increasingly widely used.

Permanent magnet synchronous motors are widely used in AC variable speed drives because they do not require excitation current and have high operating efficiency, torque inertia and power density, but their high-performance control requires precise rotor position and speed signals to achieve Magnetic field orientation. In traditional motion control systems, photoelectric encoders or resolvers are usually used to detect the position and speed of the rotor. However, these mechanical sensors are subject to their own volume, quality and other factors, especially in some environments, mechanical sensors are greatly affected by surrounding environmental factors, which may easily cause system instability. At the same time, the position sensor increases the cost of the system. Therefore, canceling these devices and adopting the position sensorless vector control technology of permanent magnet synchronous motor has become a hot spot in the field of AC speed regulation.

At present, most of the topologies for controlling motors are traditional two-level inverters with simple structures and relatively easy control methods, which are widely used. However, limited by the withstand voltage level and switching frequency of the device, the traditional two-level topology is difficult to meet the needs of high-voltage and high-power applications. In order to solve this problem, researchers from various countries have sought solutions in terms of converter control methods and topology structures. . Due to its many advantages, MMC is widely used in flexible DC transmission and power quality management and other fields. In recent years, many scholars at home and abroad have begun to apply it in the field of high-power transmission to realize the drive of high-power motors. However, when the MMC operates at a low frequency, the capacitor voltage of the bridge arm sub-module fluctuates greatly. In the process of starting the motor, it will inevitably go through the low frequency stage, so how to reduce the voltage fluctuation of the sub-module capacitor during the low frequency operation of the motor becomes a difficult problem.

At present, MMC usually uses high-frequency circulating current and high-frequency zero-sequence voltage signal injection to reduce the voltage fluctuation of sub-module capacitors during low-frequency operation, while the permanent magnet synchronous motor speed sensor uses pulse vibration high-frequency signals in zero-low-speed and medium-high-speed stages respectively. Voltage injection method and sliding mode observer. In order to simplify the control structure of the system and reduce the cost, the multiplexing problem of zero-low-speed high-frequency signals in the PMSM speed sensorless control system driven by MMC and the weighting function multiplexing problem of speed sensorless switching during operation in the full speed range can be deeply studied. Finally, a position sensorless vector control system based on MMC-driven PMSM in the full-speed operating range is realized.

SUMMARY OF THE INVENTION

Aiming at the deficiencies and existing problems of the prior art, the present invention provides a speed sensorless control method of PMSM driven by MMC variable frequency, which can realize the position sensorless control in the full speed range, and its purpose is to achieve zero and low speed at the stage of zero and low speed. The pulse vibration high-frequency voltage injection method and the high-frequency signal required to suppress the fluctuation of the sub-module are multiplexed. As the system frequency increases, the MMC needs to gradually cut off the injected high-frequency signal. Correspondingly, the speedless sensor should also be The pulsed high-frequency voltage injection method is switched to a sliding mode observer. The switching process of the two is similar, and their switching functions can be reused.

To achieve the above object, the technical scheme adopted by the present invention is:

Step 1: analyze the energy flow of the MMC bridge arm half-bridge sub-module, and obtain the relationship between the fluctuation of the sub-mode fast capacitor voltage ΔW _ap and the DC side bus voltage U _dc , the output current amplitude _Im and the output angular frequency ω;

Step 2: For low-frequency conditions, use high-frequency circulating current and high-frequency zero-sequence voltage injection to suppress capacitor voltage fluctuations;

比较，通过比例积分环节即PI控制器得到q轴给定电流i_q ^*；Step 3: Compare the given speed n ^* with the predicted speed

By comparison, the q-axis given current i _q ^* is obtained through the proportional integral link, that is, the PI controller;

Step 4: Compare the dq-axis given currents id ^* and _iq ^* with the id and _iq obtained from the _dq -axis feedback respectively, and obtain the _dq -axis voltage _udq through the PI current regulator;

Step 5: The three-phase modulation voltage u _abc is obtained from the inverse transformation of the dq axis voltage u _dq by the park;

Step 6: Input the three-phase modulation voltage u _abc into a reasonable modulation strategy to control the on-off of the device in the MMC inverter, so as to control the permanent magnet synchronous motor.

Further, in the step 1, through the analysis of the energy flow of the capacitor sub-module of the bridge arm, the fluctuation ΔW _ap of the sub-mode fast capacitor voltage, the DC side bus voltage U _dc , the output current amplitude _Im and the output angular frequency ω can be obtained. The relationship between is calculated as follows:

Further, in the step 2, the high-frequency circulating current and high-frequency zero-sequence voltage to be injected are calculated as follows (taking phase a as an example):

和滑模观测器预测转速

加权计算得到预测转速

本申请中，在永磁同步电机低速阶段采用的脉振高频电压注入法所需的高频信号和MMC低频运行时注入的高频环流以及高频零序电压信号可以进行复用。Further, in the step 3, the rotation speed predicted by the pulse vibration high-frequency voltage injection method

and sliding mode observer to predict rotational speed

Weighted calculation to get predicted speed

In this application, the high-frequency signal required by the pulse-vibration high-frequency voltage injection method used in the low-speed phase of the permanent magnet synchronous motor and the high-frequency circulating current and high-frequency zero-sequence voltage signal injected during the low-frequency operation of the MMC can be multiplexed.

的计算公式

其中G₁和G₂分别为

和

的加权因子。本申请中全速运行范围内的无位置传感器控制方法，采用加权系数算法在脉振高频电压注入法和滑模观测法之间切换，此加权系数算法也可用于切换MMC低频运行时所注入的高频信号。ω₁-ω₂为转速切换区间，ω≤ω₁时为低速运行阶段，无速度传感器采用脉振高频电压注入法，MMC运行采用高频信号注入，此时加权系数G₁＝1；ω₁＜ω＜ω₂时为切换阶段，此时预测转速

的计算公式

MMC拓扑中注入的高频信号为u′＝G₁*i_ah+G₂*0，G₁+G₂＝0，G₁和G₂随转速线性变化；ω≥ω₂为中高速运行阶段，速度传感器采用滑模观测器，MMC不需采用高频信号注入，此时G₂＝1。具体的转速切换区间通过进一步实验确定最佳值，由此即可实现基于MMC驱动的永磁同步电机在全速范围内的无速度传感器。Further, in the step 3, predict the rotational speed

The calculation formula of

where _G1 and _G2 are respectively

and

weighting factor. The position sensorless control method in the full-speed operation range in this application adopts a weighting coefficient algorithm to switch between the pulse vibration high-frequency voltage injection method and the sliding mode observation method. high frequency signal. ω ₁ -ω ₂ is the speed switching interval, when ω ≤ ω ₁ is the low-speed operation stage, the pulse vibration high-frequency voltage injection method is used for the speed sensorless, and the high-frequency signal injection is used for the MMC operation. At this time, the weighting coefficient G ₁ =1; ω ₁ < ω < ω ₂ is the switching stage, and the rotation speed is predicted at this time

The calculation formula of

The high-frequency signal injected into the MMC topology is u′=G ₁ *i _ah +G ₂ *0, G ₁ +G ₂ =0, G ₁ and G ₂ change linearly with the rotational speed; ω≥ω ₂ is the middle and high-speed operation stage , the speed sensor uses a sliding mode observer, and the MMC does not need to use high-frequency signal injection, at this time G ₂ =1. The specific speed switching interval is determined by further experiments to determine the optimal value, so that the MMC-driven permanent magnet synchronous motor can be realized without a speed sensor in the full speed range.

Further, in the step 4, i ^* _d = 0 is assumed, and the current i _abc collected in the step 6 is transformed by the 3s/2r coordinate to obtain the dq-axis feedback current _idq .

进行积分得到的预测角度

输入到3s/2r坐标变换中。Further, by predicting the angular velocity

Integrate the predicted angle

Input into the 3s/2r coordinate transformation.

积分得到预测角度

输入到park逆变换中。Further, in the step 5, the predicted angular velocity will be

Integrate to get the predicted angle

Input to park inverse transform.

Further, in the step 6, a reasonable modulation strategy is adopted to generate the pulse width signal of the power device according to the three-phase modulation voltage, and then the pulse width signal of the power device is generated by the voltage source inverter to generate the three-phase winding current i _abc , which is sent to for permanent magnet synchronous motors.

Among them, according to the obtained modulated three-phase voltage u _abc , a power device pulse width signal is generated through a reasonable modulation strategy, and then the three-phase winding current i _abc is generated by the power device pulse width signal through the voltage source inverter, and sent to the Permanent magnet synchronous motor.

The modulation strategy, according to the obtained three-phase modulation voltage, adopts a reasonable modulation strategy to generate the pulse width signal of the power device; the voltage source inverter is used to generate the three-phase winding current according to the pulse width signal of the power device, and send it to the power device. Permanent magnet synchronous motor.

对预测转速进行积分得到预测角度

Further, based on the principle of the pulse vibration high-frequency voltage injection method: inject a sinusoidal high-frequency voltage signal into the d-axis in the estimated synchronous rotating coordinate system, and excite the motor to produce an inductance saturation effect to show the saliency of the motor. Improve the high-frequency response current component, demodulate it accordingly, and obtain the rotor position information, that is, the predicted speed

Integrate the predicted speed to get the predicted angle

Further, the method based on the sliding mode observer: The state equation of the current error system can be obtained by making a difference between the three-phase PMSM synchronous rotating coordinate system and the mathematical model designed by the sliding mode observer:

和

为电流观测误差；in,

and

is the current observation error;

当系统进入滑动模态，可以获得dq轴感应电动势：The sliding mode observer is used to estimate the current, and the sliding mode surface is defined as

When the system enters the sliding mode, the dq-axis induced electromotive force can be obtained:

从而得到预测转速

对预测转速进行积分得到预测角度

It can be seen that the q-axis induced electromotive force contains the rotor speed information, namely

to get the predicted speed

Integrate the predicted speed to get the predicted angle

Based on the above technical solutions, this paper proposes a speed sensorless control multiplexing method based on MMC-driven PMSM, which uses the high-frequency signal required by the pulsed high-frequency voltage injection method in the low-speed stage of the permanent magnet synchronous motor and the high-frequency circulating current required by the MMC low-frequency operation. And the high-frequency zero-sequence voltage signal can be multiplexed. During the start-up process of the PMSM, the weighting function that the MMC is injected into the high-frequency signal is gradually cut off and the weighting function that switches between the speed sensor is multiplexed, and finally realized in the full speed range. MMC-driven PMSM speed sensorless control system.

Description of drawings

Figure 1 is the main circuit topology of the modular multilevel converter; Figure 2 is the system control composition of the high-frequency signal and the weighting function multiplexing within the full-speed operating range; Figure 3 is the weighting function control strategy diagram.

Detailed ways

In order to make the basic principles, technical solutions and advantages of the present invention clearer, a method for controlling multiplexing based on MMC-driven PMSM speed sensorless control multiplexing related to the present invention will be described in detail below. It should be understood that the following descriptions are only exemplary, and are not intended to limit the scope of protection of the present invention and its application.

The present invention provides a method for controlling multiplexing based on MMC driving PMSM without speed sensor. Referring to FIG. 1, it is a main circuit topology structure of a modular multi-level converter, which is composed of three-phase six bridge arms, each bridge arm has There are N sub-modules, and the sub-modules may be full-bridge, half-bridge and other structures, but the present invention adopts the half-bridge sub-module for analysis, the DC side of the MMC is connected to the DC source or the DC bus of the power grid, and the DC side voltage is U _dc , The AC side is connected to a permanent magnet synchronous motor, and the AC side can output three-phase AC sinusoidal electricity of N+1 level. Referring to Fig. 2, a system control composition for multiplexing high-frequency signals and weighting functions in the full-speed operating range is proposed. The sliding-mode observer suitable for medium and high speeds is combined with the pulse vibration high-frequency voltage injection method for zero and low speeds. In this process, Multiplexing the high-frequency signal required by MMC to be injected under the condition of zero and low speed with the high-frequency signal required by the pulse vibration high-frequency voltage method without speed sensor and the weighting of the high-frequency signal removed from the MMC during the process of zero low speed to medium high speed function and the weighting function for speed sensorless switching.

比较后通过PI速度调节器得到q轴给定电流，这里采用i_d ^*＝0的控制方法，dq轴给定电流分别与i_abc经过坐标变换得到的dq轴反馈电流比较，通过PI电流调节器得到dq轴电压u_dq，经过Park反变换得到三相电压u_abc输入到合理的调制策略中控制逆变器的开关通断，从而控制永磁同步电机。The main system still adopts the double closed-loop structure of speed and current, the given speed n ^* and the feedback predicted speed

After the comparison, the q-axis reference current is obtained through the PI speed regulator. Here, the control method of id ^* = 0 is used. The dq-axis reference current is compared with the _dq -axis feedback current obtained by i _abc through coordinate transformation. The dq axis voltage u _dq is obtained, and the three-phase voltage u _abc is obtained through the inverse Park transformation, which is input into a reasonable modulation strategy to control the switch of the inverter, thereby controlling the permanent magnet synchronous motor.

为脉振高频电压注入法预测的速度，

为滑模观测器预测的速度，两者分别乘以加权因子G₁G₂得到反馈的预测速度

对得到的预测速度

进行积分则得到预测的角度

然后输入到Park变换与反变换中；对于加权系数G₁G₂，同样可以应用于MMC拓扑中，则注入的高频信号为u′＝G₁*i_ah+G₂*0，G₁+G₂＝0，G₁和G₂随转速线性变化。pictured

is the velocity predicted by the pulsed high-frequency voltage injection method,

For the predicted speed of the sliding mode observer, the two are respectively multiplied by the weighting factor G ₁ G ₂ to get the predicted speed of the feedback

for the predicted speed obtained

Integrate to get the predicted angle

Then input into Park transform and inverse transform; for the weighting coefficient G ₁ G ₂ , it can also be applied to MMC topology, then the injected high-frequency signal is u′=G ₁ *i _ah +G ₂ *0, G ₁ + G ₂ =0, G ₁ and G ₂ vary linearly with the rotational speed.

的计算公式

MMC拓扑中注入的高频信号为u′＝G₁*i_ah+G₂*0，G₁+G₂＝0，G₁和G₂随转速线性变化；ω≥ω₂为中高速运行阶段，速度传感器采用滑模观测器，MMC不需采用高频信号注入，此时G₂＝1。具体的转速切换区间通过进一步实验确定最佳值，由此即可实现基于MMC驱动的永磁同步电机在全速范围内的无速度传感器。The following describes how to realize the position sensorless control method in the full speed range. The weighting function switching algorithm used here is not only a method of switching between the two detection methods, but also an algorithm of MMC high-frequency signal removal; the control strategy of the algorithm is shown in Figure 3, ω ₁ - ω ₂ is the speed switching range, when ω≤ω ₁ is the low-speed operation stage, the pulse vibration high-frequency voltage injection method is used for the speed sensorless, and the high-frequency signal injection is used for the MMC operation. At this time, the weighting coefficient G ₁ =1; ω ₁ <ω<ω ₂ is the switching stage, and the rotation speed is predicted at this time

The calculation formula of

The high-frequency signal injected into the MMC topology is u′=G ₁ *i _ah +G ₂ *0, G ₁ +G ₂ =0, G ₁ and G ₂ change linearly with the rotational speed; ω≥ω ₂ is the middle and high-speed operation stage , the speed sensor uses a sliding mode observer, and the MMC does not need to use high-frequency signal injection, at this time G ₂ =1. The specific speed switching interval is determined by further experiments to determine the optimal value, so that the speed sensorless of the permanent magnet synchronous motor driven by MMC in the full speed range can be realized.

The present invention provides a speed sensorless control multiplexing method based on MMC driving PMSM, which has the advantage of realizing the speed sensorless control system of permanent magnet synchronous motor driven by MMC topology in the full-speed operating range. The speed sensorless is applied in the field of MMC topology drive from two levels. Second, the present invention considers the injection of high-frequency signals under the low-frequency condition of MMC to suppress the voltage fluctuations of the sub-module capacitors, which is consistent with the high-frequency signals required by the pulse-vibration high-frequency voltage injection method without speed sensors at zero and low speed. System control, it can be multiplexed, in addition, in the transition stage of the system from zero low speed to medium high speed, the switching process of MMC high frequency signal injection and the switching process without speed sensor are consistent, so the same weighting function can be used for switching, further simplifying the system structure and cost.

The above is a specific embodiment of the present invention and its advantages, but the protection scope of the present invention is not limited to this. For those skilled in the art, changes and modifications can be made to the above-mentioned embodiments without departing from the technical spirit and principle described in the present invention, and these changes and modifications should also be regarded as the protection of the present invention scope.

Claims (11)

1. a PMSM speed sensorless control method of MMC variable frequency drive is characterized in that the high frequency signal of the pulse vibration high frequency voltage injection method without the speed sensor and the high frequency injected by the suppression capacitor voltage fluctuation under the MMC low frequency operating condition The signal is multiplexed and the weighting function of the speed sensorless switching in the low-speed transition stage of the permanent magnet synchronous motor is multiplexed, the repeated use of the control signal and the controller is reduced, and the control system is simplified. The method includes the following steps: Step 1: analyze the energy flow of the MMC bridge arm half-bridge sub-module, and obtain the relationship between the fluctuation of the sub-mode fast capacitor voltage ΔW _ap and the DC side bus voltage U _dc , the output current amplitude _Im and the output angular frequency ω; Step 2: For low-frequency conditions, use high-frequency circulating current and high-frequency zero-sequence voltage injection to suppress capacitor voltage fluctuations; Step 3: Compare the given speed n ^* with the predicted speed

By comparison, the q-axis given current i _q ^* is obtained through the proportional integral link, that is, the PI controller; Step 4: Compare the given currents i _q ^* and id ^* of the _dq axis with the id and i _q obtained by the feedback of the _dq axis respectively, and obtain the _dq axis voltage udq through the PI current regulator; Step 5: The three-phase modulation voltage u _abc is obtained from the inverse transformation of the dq axis voltage u _dq by the park; Step 6: Input the three-phase modulation voltage u _abc into a reasonable modulation strategy to control the on-off of the device in the MMC inverter, so as to control the permanent magnet synchronous motor. 2. The method according to claim 1, characterized in that, in step 1, by analyzing the energy flow of the bridge arm sub-module capacitance, the fluctuation ΔW _ap of the fast capacitor voltage of the sub-module and the DC side bus voltage U _dc can be obtained , the relationship between the output current amplitude _Im and the output angular frequency ω, the specific calculation is as follows:

Among them, P _ap is the power of the sub-module of the upper bridge arm, m is the modulation degree,

is the power factor angle. 3. method according to claim 1 is characterized in that, in step 2, the high-frequency circulating current and high-frequency zero-sequence voltage required to inject are calculated as follows (take a phase as an example):

Among them, i _a is the output current of phase a, K _cm is the coefficient introduced to characterize the amplitude margin of the high-frequency common-mode voltage, generally between 1.0 and 1.2, and ω _h is the angular frequency of the high-frequency zero-sequence voltage. 4. The position monitoring method according to claim 1, wherein in the step 3, the rotational speed predicted by the pulse vibration high-frequency voltage injection method

and sliding mode observer to predict rotational speed

The predicted speed is then calculated by the weighting function

Among them, the high-frequency signal required by the pulse-vibration high-frequency voltage injection method used in the low-speed stage of the permanent magnet synchronous motor, the high-frequency circulating current and the high-frequency zero-sequence voltage signal injected during the low-frequency operation of the MMC can be multiplexed. 5. The method according to claim 4, characterized in that, in step 3, the rotation speed is predicted

The calculation formula of

where _G1 and _G2 are respectively

and

weighting factor. This weighting factor can not only be used for switching between the pulse vibration high-frequency voltage injection method and the sliding mode observation method, but also can be used as the signal of the high-frequency circulating current and the high-frequency zero-sequence voltage signal injected into the whole system during the transition from zero-low speed to medium-high speed. switch to achieve multiplexing. 6. The position detection method according to claim 1, characterized in that, in the step 4, i ^* _d = 0 is adopted, and the current i _abc collected in step 6 obtains the dq-axis feedback current through 3s/2r coordinate transformation i _dq . 7. The position detection method according to claim 6, wherein the predicted angular velocity is

Integrate the predicted angle

Input into the 3s/2r coordinate transformation. 8. The position detection method according to claim, characterized in that, in step 5, the angular velocity is predicted by

Integrate to get the predicted angle

Input to park inverse transform. 9 . The position detection method according to claim 1 , wherein in the step 6, a reasonable modulation strategy is adopted to generate the pulse width signal of the power device according to the three-phase modulation voltage u _abc , and then the pulse width signal of the power device is generated by the voltage source inverter. 10 . The pulse width signal of the power device generates a three-phase winding current i _abc , which is sent to the permanent magnet synchronous motor. 10. The position detection method according to claim 4, characterized in that, based on the principle of the pulse vibration high-frequency voltage injection method: inject a sinusoidal high-frequency voltage signal into the d-axis in the estimated synchronous rotating coordinate system, and excite the motor to generate an inductance Saturation effect to show motor saliency. Improve the high-frequency response current component, demodulate it accordingly, and obtain the rotor position information, that is, the predicted speed

Integrate the predicted speed to get the predicted angle

11. position detection method according to claim 4 is characterized in that, the method based on sliding mode observer: can obtain current error system by making difference between the mathematical model of three-phase PMSM synchronous rotation coordinate system and sliding mode observer design. Equation of state:

in,

and

is the current observation error; The sliding mode observer is used to estimate the current, and the sliding mode surface is defined as

When the system enters the sliding mode, the dq-axis induced electromotive force can be obtained:

It can be seen that the q-axis induced electromotive force contains the rotor speed information, namely

to get the predicted speed

Integrate the predicted speed to get the predicted angle

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