CN116208054B - Method for detecting initial position of rotor of sinusoidal electro-magnetic doubly salient motor - Google Patents

Abstract

The application discloses a method for detecting the initial position of a rotor of a sinusoidal electro-magnetic doubly salient motor, which relates to the field of sinusoidal electro-magnetic doubly salient motors. Compared with the method of phase current change caused by injection signals, the method has the advantages that the value of the phase current containing rotor position information is larger, the signal-to-noise ratio of detection signals is increased, and the accuracy of position estimation is improved.

Description

A detection method for the initial position of the rotor of a sinusoidal electric excitation doubly salient pole motor

technical field

The present application relates to the field of sinusoidal electric excitation double salient pole motors, in particular to a method for detecting the initial position of a sinusoidal electric excitation double salient pole motor rotor.

Background technique

The sinusoidal electric excitation double salient motor is a new type of special motor, which has the advantages of simple and reliable structure, suitable for high temperature and high speed operation, etc., and has broad application prospects in aerospace, wind power generation and electric vehicles and other fields. Since the no-load back EMF of the sinusoidal electrically excited double salient motor is sinusoidal, the use of vector control can make the sinusoidal electrically excited double salient motor achieve good operating performance.

Vector control requires real-time access to rotor position information, which is traditionally achieved by using mechanical position sensors. However, the mechanical position sensor has the problems of large volume and weight, high cost, inconvenient installation and unusable in special occasions. Therefore, the position sensorless control technology has attracted widespread attention as an effective solution. Position sensorless control technology is mainly divided into two categories based on high-frequency signal injection method and motor fundamental wave model method. Among them, the position sensorless control technology based on high-frequency signal injection method is suitable for zero-speed and low-speed operation. The wave model method is suitable for position sensorless control technology operating at medium and high speeds. At present, the zero-speed and low-speed position sensorless control technology is a major difficulty in the motor's position sensorless operation.

Estimating the initial position of the rotor is the basis for realizing the operation of the motor without a position sensor, and it is the key to realize the fast start of the motor without reverse rotation. At present, the detection method of the initial position of the sine wave motor rotor is mainly based on the high frequency signal injection method. Introduced in the paper "Initial position detection of the rotor magnet surface-mounted permanent magnet synchronous motor" published by Liu Ying et al. A method for detecting the initial position of the permanent magnet synchronous motor rotor is proposed. This method first injects a high-frequency sinusoidal signal in the direction of the estimated d-axis for initial position estimation, and then injects positive and negative voltage pulses in the direction of the estimated d-axis. The positive direction of the d-axis is judged by the difference of the equivalent time constant of the axis, and the initial estimated value of the initial rotor position plus the compensation value after judging the positive direction of the d-axis is the final estimated value of the initial position. This method divides the estimation process into two stages: the initial position estimation and the judgment of the positive direction of the d-axis. The signal needs to be injected twice, which takes a long time. In the paper "Research on Position Sensorless Control System in Low-speed Area of Hybrid Excitation Motor" published by Niu Daqiang et al. (Master's thesis of Hebei University of Technology, April 2020), an initial position detection method based on numerical analysis is proposed. The pulse signal is injected, and the rotor position information is directly calculated by detecting the armature current.

The current initial position detection method usually requires additional injection of pulse signals. The amplitude of the injected signal should not be too large, otherwise it will easily cause the motor to vibrate. If the amplitude of the injected signal is too small, it will reduce the signal-to-noise ratio of the position estimation signal and reduce the Therefore, there are often problems such as complex operation, long detection time, and easy motor vibration.

Contents of the invention

In response to the above problems and technical requirements, the applicant proposed a method for detecting the initial position of the rotor of a sinusoidal electrically excited double salient pole motor. The technical solution of the application is as follows:

A method for detecting the initial position of a sinusoidal electrically excited doubly salient pole motor rotor, the method comprising:

During the static process of the sinusoidal electric excitation doubly salient motor, energize the excitation winding of the sinusoidal electric excitation doubly salient motor;

Determine the response currents of the two-phase reference windings of the sinusoidal electric excitation doubly salient pole motor during the rise of the excitation current of the excitation windings as the reference response current i ₁ and the reference response current i ₂ respectively. The two-phase reference windings are sinusoidal electric excitation double One of the two-phase armature windings of the salient pole motor;

According to the reference response current i ₁ and reference response current i ₂ of the two-phase reference winding, the estimated value of the initial rotor position of the sinusoidal electrically excited doubly salient pole motor is obtained

Its further technical solution is to calculate the estimated value of the initial rotor position of the sinusoidal electrically excited double salient pole motor The methods include:

Calculate the initial rotor position estimate The first estimate of /> and the second estimate />

calculated according to and /> Calculate the initial rotor position estimate />

Its further technical solution is, according to the calculated and /> Calculate the initial rotor position estimate /> The methods include:

when calculated and /> When one of the values is positive and the other is negative, determine the initial rotor position estimate

when calculated and /> When the values of are all positive or negative, determine the estimated value of the initial rotor position

Its further technical scheme is that the method also includes:

Combined with the characteristic that the sum of the response currents of the three-phase armature windings is 0, determine the current amplitude i _s in the rotating coordinate system with respect to the reference response current i ₁ and reference response current i ₂ of the two-phase reference winding in the natural coordinate system expression;

Taking the q-axis current i _q =0 and the d-axis current i _d =i _s in the rotating coordinate system and combining the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system, the rotor initial location estimate Expressions for reference response current _i1 and reference response current _i2 .

Its further technical solution is that the method for determining the expression of the current amplitude _is under the rotating coordinate system with respect to the reference response current _i1 and the reference response current _i2 includes:

Determine the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system as Among them, i _q is the q-axis current in the rotating coordinate system, _id is the d-axis current in the rotating coordinate system, i _a , i _b , and i _c are the response currents of the three-phase armature windings in the natural coordinate system, respectively, θ is the rotor position;

Combined with the feature of i _a +i _b +i _c =0, according to The expression of the current amplitude i _s in the rotating coordinate system with respect to the reference response current i ₁ and the reference response current i ₂ is /> i ₁ and i ₂ are two response currents of _ia , _ib and _ic .

Its further technical solution is to obtain the estimated value of the rotor initial position Methods regarding the expressions of the reference response current _i1 and the reference response current _i2 include:

Take i _q =0, Combined with the transformation of the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system:

Combining the characteristic transformation of i _a +i _b +i _c =0 to obtain the estimated value of the initial position of the rotor Expressions for reference response current _i1 and reference response current _i2 .

Its further technical scheme is that the three-phase armature windings of the sinusoidal electric excitation doubly salient pole motor are connected in a Y shape and connected to the midpoints of the three bridge arms of the three-phase full-bridge inverter respectively. The control method of the excitation doubly salient motor also includes:

During the static process of the sinusoidal electric excitation double salient pole motor, the upper bridge arm switch tubes controlling the three bridge arms of the three-phase full-bridge inverter are all turned off, and the lower bridge arm switch tubes controlling the three bridge arms are all turned on , so that the three-phase armature windings of the sinusoidal electrically excited doubly salient motor are in a short-circuit state and the d-axis voltage and q-axis voltage in the rotating coordinate system are always equal to 0, so that the excitation of the sinusoidal electrically excited doubly salient pole motor The windings are energized and an initial rotor position estimate is obtained During the detection process, the electromagnetic torque of the sinusoidal electric excitation doubly salient motor is 0, and the rotor does not rotate.

Its further technical proposal is that the method of energizing the field winding of the sinusoidal electric excitation doubly salient pole motor includes:

Acquisition of the actual value of the field current i _f flowing through the field winding;

Set the excitation current given value The difference with the actual value of the excitation current i _f is used as the input of the PI controller, and the output of the PI controller is generated through the PWM control algorithm to generate the first control signal;

According to the first control signal, the asymmetrical half-bridge connected to the excitation winding of the sinusoidal electric excitation doubly salient pole motor is controlled, so that the actual value of the excitation current i _f of the excitation winding rises and follows the given value of the excitation current

The beneficial technical effect of the application is:

This application discloses a method for detecting the initial position of the rotor of a sinusoidal electric excitation double salient pole motor. The method directly detects the initial position during the process of motor excitation and voltage build-up, without additional injection signals, and does not need to consider the selection of the amplitude of the injection signals. No electromagnetic torque is generated during the detection process, so the detection method is easy to implement, the position estimation time is significantly shortened, and the problem of motor vibration during the initial position detection process is avoided. And compared with the method of causing phase current changes by injecting signals, the value of the phase current including the rotor position information in this application is larger, which increases the signal-to-noise ratio of the detection signal and is beneficial to improving the accuracy of position estimation.

Moreover, the necessary process of establishing the magnetic field of the motor in the present application directly detects the initial position of the rotor without adding extra system time for detection, which simplifies the estimation process.

Description of drawings

Fig. 1 is a control block diagram of the rotor initial position detection method of the present application.

Fig. 2 is a curve diagram of the excitation current, the induction current of the three-phase armature winding, the d-axis current, and the q-axis current during the detection process of the initial position of the rotor.

Detailed ways

The specific implementation manners of the present application will be further described below in conjunction with the accompanying drawings.

This application discloses a method for detecting the initial position of the rotor of a sinusoidal electrically excited double salient pole motor. Please refer to the control block diagram shown in Figure 1. In the topology of the sinusoidal electrically excited double salient pole The three-phase armature windings A, B, and C of the electrically excited double salient pole motor (SDSEM) are connected in a Y shape, that is, one end of the A-phase armature winding, B-phase armature winding and C-phase armature winding is connected, and the three-phase The other end of the armature winding is respectively connected to the middle points of the three bridge arms of the three-phase full-bridge inverter, and the three-phase full-bridge inverter is connected to the bus voltage U _DC1 . The excitation winding F of the sinusoidal electrically excited doubly salient motor is connected to an internal asymmetrical half-bridge, and the asymmetrical half-bridge is connected to the bus voltage U _DC2 .

During the static process of the sinusoidal electric excitation double salient pole motor, the excitation winding of the sinusoidal electric excitation double salient pole motor is energized. The method for energizing the excitation winding of the sinusoidal electric excitation doubly salient pole motor includes: collecting the actual value if of the excitation current flowing through the excitation winding _F. Set the excitation current given value The difference with the actual value of the excitation current if is used as the input of the PI controller, and the output of the PI controller is used to generate _the first control signal S _F through the PWM control algorithm. According to the first control signal S _F , the asymmetrical half bridge connected to the excitation winding of the sinusoidal electric excitation double salient pole motor is controlled, so that the actual value of the excitation current i _f of the excitation winding rises and follows the given value of the excitation current />

During the rise of the excitation current of the excitation winding, a response current will be induced on the three-phase armature winding of the sinusoidal electric excitation doubly salient pole motor, and the A-phase armature winding and B-phase armature in the natural coordinate system (abc coordinate system) The response currents induced on the winding and the C-phase armature winding are _ia , _ib , and _ic respectively. Since the three-phase armature windings are Y-connected, i _a +i _b +i _c =0.

In this application, any two-phase armature winding is taken as the two-phase reference winding, and the response current induced by the two-phase reference winding is respectively used as the reference response current i ₁ and the reference response current i ₂ , therefore, i ₁ and i ₂ are i Two of _a , _ib , and _ic respond to currents. For example, in FIG. 1 , if the A-phase armature winding and the B-phase armature winding are used as two-phase reference windings, then the reference response current i ₁ =i _a , and the reference response current i ₂ =i _b . The combination of selecting other two-phase reference windings is similar, and so on.

Then, according to the reference response current i ₁ and reference response current i ₂ of the two-phase reference winding, the estimated value of the initial rotor position of the sinusoidal electrically excited doubly salient pole motor is obtained Estimated initial rotor position /> The expressions about the reference response current i ₁ and the reference response current i ₂ are pre-fitted, and the determination methods include:

(1) Combining the characteristics that the sum of the response currents of the three-phase armature windings is 0, that is, _ia + i _b + i _c = 0, determine the current amplitude i _s in the rotating coordinate system relative to the two in the natural coordinate system The expressions of the reference response current i ₁ and the reference response current i ₂ of the phase reference winding.

The coordinate transformation relationship between the rotating coordinate system and the natural coordinate system is:

Among them, i _q is the q-axis current in the rotating coordinate system, _id is the d-axis current in the rotating coordinate system, and θ is the rotor position.

Combined with the feature of i _a +i _b +i _c =0, according to can be converted to get the current amplitude i _s in the rotating coordinate system with respect to the reference response current i ₁ and the reference response current i ₂ as

(2) Since the excitation flux linkage only has a coupling relationship with the d-axis flux linkage, the change of the excitation current will only cause the change of the d-axis current i _d , while the q-axis current i _q is always equal to 0. In this process, the excitation current if , the response current _ia , _ib , _ic induced by the three-phase armature winding, the d-axis current _id and the q-axis current _{i q vary} with time as shown in Fig. 2 .

Therefore, taking the q-axis current i _q =0 and the d-axis current i _d =i _s in the rotating coordinate system and combining the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system, the sinusoidal electrically excited double salient pole motor can be obtained Rotor initial position estimate The expressions about the reference response current i ₁ and the reference response current i ₂ include:

Take i _q =0, Combined with the transformation of the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system:

Combining the characteristic transformation of i _a +i _b +i _c =0 to obtain the estimated value of the initial position of the rotor Expressions for reference response current _i1 and reference response current _i2 .

The resulting rotor initial position estimate The expressions about the reference response current i ₁ and the reference response current i ₂ include two expressions, and the estimated value of the initial rotor position can be obtained by calculating the following two expressions respectively.> The first estimate of /> and the second estimate /> in:

Then the estimated value of the initial rotor position is obtained by fitting the above method After the expression about the reference response current i ₁ and the reference response current i ₂ can be substituted into the collected reference response current i ₁ and reference response current i ₂ to calculate the estimated value of the initial rotor position /> include:

Firstly, calculate the estimated value of the initial position of the rotor separately The first estimate of and the second estimate /> Then according to the calculated /> and /> Calculate the initial rotor position estimate /> When calculated /> and /> When one of the values is positive and the other is negative, determine the estimated value of the initial rotor position /> When calculated /> and /> When the values of are all positive or negative, determine the estimated value of the initial rotor position />

In addition, in the process of detecting the initial position of the rotor according to the method provided by this application, the control of the sinusoidal electric excitation double salient pole motor also includes: in the stationary process of the sinusoidal electric excitation double salient pole motor, given the αβ coordinate system The α-axis voltage u _α =0 and the β-axis voltage u _β =0, adopt the SVPWM control method (space vector pulse width modulation method) to obtain the second control signal S _ABC according to u _α =0 and u _β =0, according to the second The control signal S _ABC controls the three-phase full-bridge inverter, so as to control the switch tubes of the upper bridge arms of the three bridge arms of the three-phase full-bridge inverter to be turned off, and to control the switch tubes of the lower bridge arms of the three bridge arms to be turned on. Pass. The three-phase armature windings of the sinusoidal electrically excited doubly salient motor are all in a short-circuit state and the d-axis voltage and q-axis voltage in the rotating coordinate system (dq coordinate system) are always equal to 0, that is, So that the excitation winding of the sinusoidal electric excitation doubly salient motor is energized and the estimated value of the initial rotor position is obtained /> During the detection process, the electromagnetic torque of the sinusoidal electric excitation double salient pole motor is 0, and the rotor does not rotate, so as to avoid the problem of vibration or even reversal during the detection process of the initial position of the rotor.

What is described above is only a preferred embodiment of the application, and the application is not limited to the above examples. It can be understood that other improvements and changes directly derived or conceived by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims (6)

1. A method for detecting the initial position of a sinusoidal electrically excited doubly salient pole motor rotor, characterized in that the method comprises: During the stationary process of the sinusoidal electrically excited double salient pole motor, energize the excitation winding of the sinusoidal electrically excited double salient pole motor; Determine the response currents of the two-phase reference windings of the sinusoidal electric excitation doubly salient pole motor during the rise of the excitation current of the excitation windings as the reference response current i ₁ and the reference response current i ₂ respectively, the two-phase reference windings are the Describe the two-phase armature windings of the sinusoidal electrically excited doubly salient motor; According to the reference response current _i1 and reference response current _i2 of the two-phase reference winding, the estimated value of the initial rotor position of the sinusoidal electrically excited double salient pole motor is obtained Calculating the estimated value of the initial rotor position of the sinusoidal electrically excited doubly salient motor The methods include: Calculate the initial rotor position estimate The first estimate of /> and the second estimate /> calculated according to and /> Calculate the initial rotor position estimate /> Include: when calculated /> and /> When one of the values is positive and the other is negative, determine the estimated value of the initial rotor position /> When calculated /> and /> When the values of are all positive or negative, determine the estimated value of the initial rotor position /> 2. The method according to claim 1, characterized in that the method further comprises: Combined with the characteristic that the sum of the response currents of the three-phase armature windings is 0, determine the current amplitude i _s in the rotating coordinate system with respect to the reference response current i ₁ and reference response current i ₂ of the two-phase reference winding in the natural coordinate system expression; Taking the q-axis current i _q =0 and the d-axis current i _d =i _s in the rotating coordinate system and combining the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system, the sinusoidal electrically excited doubly salient pole motor is obtained Rotor initial position estimate Expressions for reference response current _i1 and reference response current _i2 . 3. The method according to claim 2, characterized in that, the method for determining the current amplitude _i under the rotating coordinate system with respect to the expression of the reference response current i ₁ and the reference response current i ₂ includes: Determine the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system as Among them, i _q is the q-axis current in the rotating coordinate system, _id is the d-axis current in the rotating coordinate system, i _a , i _b , and i _c are the response currents of the three-phase armature windings in the natural coordinate system, respectively, θ is the rotor position; Combined with the feature of i _a +i _b +i _c =0, according to The expression of the current amplitude i _s in the rotating coordinate system with respect to the reference response current i ₁ and the reference response current i ₂ is /> i ₁ and i ₂ are two response currents of _ia , _ib and _ic . 4. The method according to claim 3, characterized in that obtaining an initial rotor position estimate Methods regarding the expressions of the reference response current _i1 and the reference response current _i2 include: Take i _q =0, Combined with the transformation of the coordinate transformation relationship between the rotating coordinate system and the natural coordinate system: Combining the characteristic transformation of i _a +i _b +i _c =0 to obtain the estimated value of the initial position of the rotor Expressions for reference response current _i1 and reference response current _i2 . 5. The method according to claim 1, characterized in that, the three-phase armature windings of the sinusoidal electric excitation doubly salient motor adopt Y-type connection and are respectively connected to the three bridge arms of the three-phase full-bridge inverter The midpoint of the bridge arm, the control method for the sinusoidal electric excitation doubly salient pole motor also includes: During the static process of the sinusoidal electric excitation double salient pole motor, the upper bridge arm switch tubes of the three bridge arms of the three-phase full-bridge inverter are all turned off, and the lower bridge arm switches of the three bridge arms are controlled The tubes are all turned on, so that the three-phase armature windings of the sinusoidal electrically excited double salient pole motor are all in a short-circuit state, and the d-axis voltage and the q-axis voltage in the rotating coordinate system are always equal to 0, so that the sinusoidal type The field winding of an electrically excited doubly salient motor is energized and an initial rotor position estimate is obtained During the detection process, the electromagnetic torque of the sinusoidal electrically excited double salient pole motor is 0, and the rotor does not rotate. 6. The method according to claim 1, wherein the method for energizing the field winding of the sinusoidal electric excitation doubly salient pole motor comprises: Acquisition of the actual value of the field current i _f flowing through the field winding; Set the excitation current given value The difference with the actual value of the excitation current i _f is used as the input of the PI controller, and the output of the PI controller is generated by a PWM control algorithm to generate the first control signal; According to the first control signal, the asymmetrical half-bridge connected to the excitation winding of the sinusoidal electric excitation doubly salient pole motor is controlled, so that the actual value of the excitation current if of the excitation winding _rises and follows the given excitation current value