CN105227010B - A kind of permagnetic synchronous motor position-sensor-free position detection error harmonic pulse removing method - Google Patents

Abstract

The invention discloses a position sensorless position observation error harmonic pulse elimination method for a permanent magnet synchronous motor, which relates to the field of motor control. It solves the problem that the rotor position information of the permanent magnet synchronous motor is detected by the position sensorless control technology of medium and high speed, which contains 6th harmonic pulsation, which leads to the error of the rotor position detection. The present invention is realized through the following steps: Step 1. Based on the effective flux linkage model of the built-in permanent magnet synchronous motor, an observer is used to obtain the counter electromotive force information under the two-phase static coordinates of the permanent magnet synchronous motor, and perform normalization processing; Step 2 1. Using an adaptive vector filter cross-feedback network to eliminate the 5th and 7th harmonics in the back EMF observations; Step 3: Using a quadrature phase-locked loop to obtain the rotor position observations from the back EMF information. The invention can effectively suppress the influence of the sixth-order position observation error harmonic wave fluctuation.

Description

Harmonic pulse elimination of position observation error of a permanent magnet synchronous motor without position sensor method

technical field

The invention relates to the field of motor control.

Background technique

In recent years, the speed control system of permanent magnet synchronous motor has gradually become a research hotspot in the field of AC speed control transmission. The reason is that compared with the traditional asynchronous motor, the advantages of the permanent magnet synchronous motor are: simple structure, small size, light weight, reliable operation, high power density, good speed regulation performance, etc. It is the ideal choice for high-speed electric drive system, and its application field is very wide. According to the structure of the permanent magnet of the permanent magnet synchronous motor rotor, it can be divided into two types: surface mount type and built-in type.

At present, in the application of high-performance permanent magnet synchronous motor speed control systems, it is usually necessary to install mechanical position detection elements such as photoelectric encoders, resolvers or Hall sensors at the end of the motor shaft to obtain rotor magnetic pole position information. However, the installation of position sensors This brings many problems such as increased system cost, increased volume, and reduced reliability, and limits the application occasions of the permanent magnet synchronous motor. Therefore, the study of low-cost, strong robustness sensorless permanent magnet synchronous motor control method has become a research hotspot in the field of AC motor control technology. According to the scope of application of the permanent magnet synchronous motor position sensorless technology, it is usually divided into two categories: one is the position sensorless technology suitable for medium and high speeds, and the other is the position sensorless technology suitable for low speed (zero speed). They are respectively implemented according to the fundamental frequency mathematical model of the motor and the structural characteristics of the salient poles. The position sensorless technology for permanent magnet synchronous motors suitable for medium and high speeds observes rotor position/speed information through the back electromotive force or flux linkage model excited by the fundamental frequency, without using the salient poles of the motor, which makes it suitable for medium and high speed positionless motors. Sensor technology is more widely used and relatively simple. At present, sensorless control techniques using model methods mainly include open-loop flux linkage method, disturbance observer method, sliding mode observer method, effective flux linkage observer method, extended Kalman filter method, model reference adaptive method and based on Theoretical methods of artificial intelligence, etc.

However, using the model method to observe the rotor position requires motor parameter information, and the uncertainty of the parameters will lead to the observation error of the DC offset rotor position. The rotor position error of the DC offset can be reduced to a certain extent by online parameter identification, but accurate parameter identification is difficult to achieve and increases the complexity of the system. Due to the influence of the nonlinearity of the inverter and the space harmonics of the rotor flux, the back electromotive force in the two-phase static coordinates will generate 5th and 7th harmonics, which will lead to 6th harmonic fluctuations in the rotor position observation error. The traditional method is to use the average voltage method to compensate the nonlinearity of the inverter, and use the accurate modeling method of the inductance to eliminate the influence of the space harmonic of the rotor flux. However, in the actual application process, neither the nonlinear compensation of the inverter nor the accurate modeling method of the inductance can effectively reduce the 6th harmonic and eliminate its influence. The existence of DC offset and 6th harmonic pulsation rotor position observation error deteriorates the control performance of sensorless permanent magnet synchronous motor. Therefore, for the position sensorless permanent magnet synchronous motor control system, it is very important to eliminate the influence of the 6th harmonic pulsation rotor position error.

Contents of the invention

In order to solve the problem that the rotor position information of the permanent magnet synchronous motor is detected by the position sensorless control technology of medium and high speed, there are 6th harmonic pulsation, which leads to the error of the rotor position detection, the present invention proposes a permanent magnet synchronous motor without A method for eliminating harmonic pulses of position sensor position observation errors.

A method for eliminating harmonic pulses of position observation errors of permanent magnet synchronous motors without position sensors, which is realized through the following steps:

Step 1. Based on the effective flux linkage model of the built-in permanent magnet synchronous motor, the observer is used to obtain the back electromotive force information under the two-phase static coordinates of the permanent magnet synchronous motor, and perform normalization processing;

Step 2, using an adaptive vector filter cross-feedback network to eliminate the 5th and 7th harmonics in the back EMF observations;

Step 3, using a quadrature phase-locked loop to obtain the rotor position observation value from the back electromotive force information.

Beneficial effects: the method for eliminating the 6th order position observation error harmonic pulsation of the permanent magnet synchronous motor based on the self-adaptive vector filter cross-feedback network based on the position sensorless model method adopted by the present invention, the signal processing method is simple, reliable and practical, and can effectively suppress The 6th position observation error harmonic pulsation influence improves the position sensorless control performance of permanent magnet synchronous motors; it can be widely applied to permanent magnet synchronous motor control systems without additional hardware overhead, and can obtain satisfactory control performance.

Description of drawings

Fig. 1 is a block diagram of the sliding mode observer based on the back electromotive force model;

Fig. 2 is a functional block diagram of an adaptive vector filter cross-feedback network;

Fig. 3 is a structural block diagram of an adaptive vector filter;

Fig. 4 is a schematic diagram of the relative relationship between the two-phase synchronously rotating shafting system, the two-phase stationary shafting system and the three-phase stationary shafting system;

Figure 5 is when the permanent magnet synchronous motor speed given value 100r/min, with 25% rated load, the experimental waveform before the adaptive vector filter cross feedback network is enabled;

Figure 6 is when the permanent magnet synchronous motor speed given value 100r/min, with 25% rated load, the experimental waveform after the adaptive vector filter cross feedback network is enabled.

detailed description

Specific embodiments 1. This specific embodiment is described in conjunction with FIG. 1. A permanent magnet synchronous motor described in this embodiment without a position sensor position observation error harmonic pulse elimination method is realized by the following steps:

Step 1. Based on the effective flux linkage model of the built-in permanent magnet synchronous motor, the observer is used to obtain the back electromotive force information of the two-phase static coordinates of the permanent magnet synchronous motor, and perform normalization processing;

Step 2, using an adaptive vector filter cross-feedback network to eliminate -5 harmonics and 7th harmonics in the back EMF observations;

Step 3, using a quadrature phase-locked loop to obtain the rotor position observation value from the back electromotive force information.

The harmonic pulse elimination method described in this embodiment uses the adaptive vector filter cross-feedback network method to detect and compensate the 5th and 7th harmonics of the back electromotive force, thereby eliminating the 6th harmonic pulse of the position observation value

Specific embodiment 2. This specific embodiment is described in conjunction with FIG. 1 . The difference between this specific embodiment and the position sensorless harmonic pulse elimination method for a permanent magnet synchronous motor described in specific embodiment 1 is that step 1 Based on the effective flux linkage model of the built-in permanent magnet synchronous motor described above, the observer is used to obtain the back electromotive force information of the two-phase static coordinates of the permanent magnet synchronous motor, and the normalization process is as follows:

Step 11. Based on the effective flux linkage model, the sliding mode observer generates the current observation value from the input stator voltage u _s

Step one and two, according to to obtain the current error signal

Among them, the stator current i _s in the two-phase static coordinate system is according to the formula Carry out Clarke transformation to obtain, in the formula, i _a , i _b , i _c are the motor stator current detection values, i _α , i _β are the α-axis and β-axis current components in the two-phase stationary coordinate system;

Step 13, the current error signal obtained in step 12 Obtain the equivalent back electromotive force information z in the two-phase static coordinates of the permanent magnet synchronous motor through the transformation of the saturation function;

Step 14: Perform low-pass filtering and normalization processing on the equivalent back EMF information z in the two-phase static coordinates of the permanent magnet synchronous motor to generate a normalized back EMF The influence of speed change on the quadrature phase-locked loop is eliminated through the back electromotive force normalization link.

The permanent magnet synchronous motor is the main link of the AC synchronous motor speed control system. As shown in Figure 4, the axis of the fundamental excitation field of the rotor permanent magnet is taken as the d axis, the q axis is 90 degrees ahead of the d axis along the direction of rotation, and the dq axis system follows The rotor rotates together with the angular velocity ω _r , and its spatial coordinates are defined by the angle between the d axis and the reference axis A phase axis To indicate that the axis where phase A is located - the reference axis phase A axis is zero degrees. Then the rotor initial position angle is the angle between the initial rotor magnetic field and the reference axis A-phase axis. The reference axis A-phase axis coincides with the α-axis in the two-phase stationary coordinate system, and the β-axis advances the α-axis by 90 degrees along the direction of rotation.

Specific embodiment 3. This specific embodiment is described in conjunction with FIG. 2 and FIG. 3 . The difference between this specific embodiment and the position sensorless position observation error harmonic pulse elimination method of a permanent magnet synchronous motor described in specific embodiment 1 is that: The process of adopting the adaptive vector filter cross-feedback network described in step 2 to eliminate the -5th harmonic and the 7th harmonic in the counter electromotive force observation value includes:

Step 21: Take the quadrature phase-locked loop output rotor speed, multiply the rotor speed item by -5 times and 7 times of gain respectively, and at the same time use the adaptive vector filter gain constants k _f1 , k _f-5 , k _f7 as the adaptive Vector filter cross feedback network input;

Step 22. Get the normalized back electromotive force As an input, the adaptive vector filter output is taken after being adjusted by the adaptive vector filter (include ) to form cross-feedback.

Figure 3 is a structural block diagram of the adaptive vector filter, without loss of generality, the input signal to be adjusted is denoted as X _αβ =[x _α x _β ] ^T , the output signal is denoted as Y _αβ =[x _α x _β ] ^T , ω ₀ is the input signal frequency, k _f is the adjustable gain constant, and the transfer function of the adaptive vector filter can be obtained as shown in formula (2). It can be seen that the adaptive vector filter has the characteristic of band-pass filtering, and the pass-band frequency is ω ₀ .

Figure 2 is a cross-feedback network composed of three adaptive vector filter modules, and AVF in Figure 2 represents a vector filter. Take the quadrature phase-locked loop output rotor speed, the rotor speed item multiplied by -5 times, 7 times gain, and the adaptive vector filter gain constants k _f1 , k _f-5 , k _f7 as the adaptive vector filter cross feedback network enter. The use of a cross feedback network can effectively eliminate the influence of the 5th and 7th harmonics of the counter electromotive force observations and improve the accuracy of position observations.

The adaptive vector filter cross-feedback network output described in this embodiment Output the angle between the d-axis and the reference axis A-phase axis after being phase-locked by the phase-locked loop and velocity observations

Figures 5 and 6 are the waveforms obtained from the experiment. The experiment was carried out on the permanent magnet synchronous motor pair dragging test platform. Figures 5 and 6 are the waveforms before and after the cross-feedback network of the adaptive vector filter is enabled, and the six rotor positions The harmonic fluctuation of the observed value is successfully eliminated, and the experimental results verify the effectiveness of the method of the invention.

Claims (2)

1. a permanent magnet synchronous motor position sensorless position observation error harmonic pulse elimination method is characterized in that it is realized by the following steps: Step 1. Based on the effective flux linkage model of the built-in permanent magnet synchronous motor, the observer is used to obtain the back electromotive force information of the two-phase static coordinates of the permanent magnet synchronous motor, and perform normalization processing; Step 2, using an adaptive vector filter cross-feedback network to eliminate -5 harmonics and 7th harmonics in the back EMF observations; Step 3, using a quadrature phase-locked loop to obtain the rotor position observation value from the back electromotive force information; The process of adopting the adaptive vector filter cross-feedback network described in step 2 to eliminate the -5th harmonic and the 7th harmonic in the counter electromotive force observation value includes: Step 21, take the quadrature phase-locked loop output rotor speed, the rotor speed item is multiplied by -5 times and 7 times of gain, and at the same time, the adaptive vector filter gain constant is used as the input of the adaptive vector filter cross feedback network; Step two and two, take the normalized back electromotive force as input, take the back electromotive force of the adaptive vector filter output 1 harmonic, -5 harmonic and 7 harmonic after adjustment by the adaptive vector filter, thus Create cross feedback. 2. a kind of permanent magnet synchronous motor position sensorless position observation error harmonic pulse elimination method according to claim 1, it is characterized in that, based on the effective flux linkage model of built-in permanent magnet synchronous motor described in step one, adopt observation The process of obtaining the counter electromotive force information under the two-phase static coordinates of the permanent magnet synchronous motor and performing normalization processing is as follows: Based on the extended back EMF model of the permanent magnet synchronous motor, the sliding mode observer is used to obtain the equivalent back EMF information in the two-phase static coordinates of the permanent magnet synchronous motor. , through the normalization link of the back electromotive force to eliminate the influence of the speed change on the quadrature phase-locked loop, and obtain the normalized back electromotive force after normalization.