1 lead

In this paper, the high-frequency voltage signal injection method is reviewed. The main contents are as follows: The high-frequency signal injection method is divided into three categories. The typical implementation schemes of each type of method and their advantages and disadvantages are introduced. The similarities and differences of the three methods are compared and analyzed. Looking forward to the development trend of high frequency signal injection method.

2 Research background

Permanent Magnet Synchronous Motor (PMSM) has the advantages of high power density, high efficiency, wide speed range and low noise, and is widely used in the industrial field.

Sensorless control technology helps improve the reliability and reduce system cost and complexity of PMSM drive systems compared to position and speed information through mechanical sensors. The high-frequency signal injection method uses the salient pole characteristics of the PMSM to obtain the rotor position information, and achieves sensorless control at zero speed and low speed of the motor. Therefore, the high frequency signal injection method has received extensive attention and research.

3 Research status at home and abroad

In this paper, the status quo of high-frequency signal injection method is reviewed. The methods are summarized into three categories: traditional high-frequency sine wave injection method, improved high-frequency sine wave injection method and high-frequency non-sine wave injection method.

The traditional high-frequency sine wave injection method includes the high-frequency rotary voltage injection method proposed by Lorenz RD and the high-frequency pulse voltage injection method proposed by Sul SK. The conventional high-frequency rotary injection method has good stability, but there is a problem that the position estimation accuracy is poor. The traditional high-frequency pulse injection method has high position identification accuracy, but has the problems of long convergence time, poor dynamic performance and small stability range.

In order to solve the problems of the traditional methods, some scholars have studied the improved high-frequency sine wave injection method.

1 Two-way high-frequency rotating sine wave injection into two-phase stationary coordinate system: This method has higher position estimation accuracy, which reduces the influence of stator resistance and system delay, but the signal processing is more complicated, and multiple parameter design is completed.

2 High-frequency pulsed sine wave injection into two-phase stationary coordinate system: Compared with the traditional high-frequency pulse injection method, this method can improve the stability of the position estimation system; compared with the traditional high-frequency rotary injection method, the method The signal demodulation process is much simpler. The disadvantage of this method is that the position calculation requires accurate acquisition of the motor parameters.

3 High-frequency pulsed sine wave injection into the ABC coordinate system: Compared with the traditional high-frequency pulse injection method, this method can solve the shortcomings of long convergence time and poor stability of position estimation, but the signal demodulation process is low. Pass the number of filters and complete multiple parameter designs.

4 High-frequency pulsed sine wave injection into fixed-frequency rotating coordinate system: Compared with the traditional high-frequency pulsed injection method, this method can improve the convergence rate of position estimation and improve system stability, but the position calculation needs to accurately obtain the motor parameters. Complete multiple parameter designs.

5 High-frequency injection method based on zero-sequence voltage demodulation: Since the zero-sequence component is less affected by the distortion voltage, this method can significantly improve the bandwidth and stability of the system, but requires an additional impedance network and a high-precision voltage sensor. Get the zero sequence voltage value.

In order to solve the problem of low bandwidth of high-frequency sine wave injection method, some scholars have studied the high-frequency non-sinusoidal injection method.

1 High-frequency pulse-wave square wave injection method: This method can increase the frequency of the injected signal to the switching frequency level, which can increase the system bandwidth and reduce the audible noise. However, in order to ensure a high signal-to-noise ratio, it is necessary to increase the amplitude of the injection voltage. The value, on the other hand, limits the utilization of the fundamental voltage.

2 High-frequency pulse vibration triangle wave injection method: This method is applied to initial position identification, has faster dynamics, and eliminates low-pass filter. Its disadvantages are resistance, system delay, inverter nonlinearity and other factors. Under the influence of factors such as cross saturation, the direct modulation method will superimpose high frequency glitch interference in the position error signal, which will affect the accuracy and stability of position estimation.

4 Similarities and differences analysis and development trend

It can be seen from the analysis that the difference between the three types of methods lies in the type of the injected signal and the way the signal is demodulated, and the common point is that the salient pole characteristics of the motor are utilized to observe the rotor position. In addition, since the salient pole position of the motor exhibits a fluctuation of 2 times in one electrical angle period, polarity determination is required.

The sensorless control technology of permanent magnet synchronous motor based on high frequency injection method should have high quality characteristics, mainly reflected in:

1) The dynamic performance of the observer is high.

2) The stability of the system is strong.

3) Position observation accuracy is high and is less affected by unfavorable factors.

4) The signal processing process is simple and the filtering process is small.

However, these quality characteristics are restrictive, so the high-frequency injection method is diversified, which is characterized by improving the quality of certain aspects to meet the needs of applications, such as improving position estimation accuracy, simplifying signal processing, and reducing Audible noise, etc.

5 Conclusion

The high frequency injection method can be well applied to the sensorless control technology of permanent magnet synchronous motor. The high frequency injection method can be divided into a conventional high frequency sine wave injection method, an improved high frequency sine wave injection method, and a high frequency non-sinusoidal wave injection method. The sensorless control technology based on the high-frequency injection method is diversified, and it is manifested by improving the quality characteristics of a certain aspect to meet the needs of the application.

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