A parameter-free method for estimating the rotor position of a main motor

Abstract

This invention relates to the field of electrically excited synchronous motor technology, specifically to a parameter-free method for estimating the rotor position of a main motor. The method includes: acquiring the derivative function of the exciter's synthesized current; generating a first square wave signal and a second square wave signal; sampling the stator current of the exciter to obtain the envelope signal of the exciter rotor position; acquiring the rotor position angle increment of the main motor; and estimating the rotor position of the main motor. This invention requires no motor parameters throughout the entire process, resulting in less computation. It is applicable to the entire speed range of the starting process, improves the stability of rotor position estimation methods based on exciter nonlinear harmonics, and provides more accurate estimation results.

Description

Technical Field

[0001] This invention relates to the field of electrically excited synchronous motor technology, and specifically to a method for estimating the rotor position of a main motor without requiring parameters. Background Technology

[0002] The integrated starter-generator system is a crucial component of multi-electric aircraft. During startup, the main generator operates in electric mode to power the aircraft engine, significantly reducing the system's size and weight, and improving system reliability and aircraft space utilization. The brushless electrically excited synchronous motor (BEM) is a key research area in this technology, widely applicable in the aviation field due to its mature power generation technology and high reliability. The BEM mainly consists of a main motor, exciter, permanent magnet auxiliary exciter, and rotating rectifier, as shown in the schematic diagram below. Figure 2 As shown.

[0003] During the startup phase, high-precision rotor position of the main motor is crucial for achieving high-performance startup control of a brushless electrically excited synchronous motor. This process is typically achieved using a mechanical position sensor mounted on the motor shaft. However, the main motor operates as a generator most of the time, resulting in low utilization of the position sensor. Furthermore, brushless electrically excited synchronous motors operate in high-temperature, high-pressure, and high-vibration environments, which reduces the reliability of the position sensor. Therefore, sensorless startup control of brushless electrically excited synchronous motors is a very attractive topic.

[0004] The unique nonlinear rectification process of the rotating rectifier introduces a large number of high-order harmonics into the exciter rotor. As the motor rotates, these harmonics exhibit frequency and phase changes, depending on the relative velocity between the rotor and the rotating magnetic field. Therefore, these harmonics naturally contain information related to the exciter rotor position. Since the main motor and exciter are coaxially mounted, the rotor rotation angle of the main motor can be calculated from the exciter rotor position. Adding this to the initial position of the main motor yields its final rotor position.

[0005] The back electromotive force (EMF) and flux linkage of the exciter are the direct sources of harmonics. Due to the brushless electrical structure, the back EMF needs to be observed, a process dependent on accurate stator parameters of the exciter. When these parameters are incorrect, the rotor position estimation will also be inaccurate, thus affecting its accuracy. Furthermore, harmonic demodulation methods based on rotational transformation are only suitable for low-speed operation. As the main motor speed increases, the relative velocity between the rotor and stator magnetic fields continuously changes, amplifying the position estimation error and reducing its accuracy.

[0006] Therefore, there is a need to provide a parameter-free method for estimating the rotor position of the main motor that is applicable to higher speed ranges in order to solve the above problems. Summary of the Invention

[0007] This invention provides a parameter-free method for estimating the rotor position of a main motor to solve existing problems.

[0008] The present invention provides a parameter-free method for estimating the rotor position of a main motor, which employs the following technical solution:

[0009] Obtain the three-phase stator current of the exciter and convert it into the stator current of the exciter in a stationary coordinate system. Shaft current, stator Shaft current; and according to the stator of the exciter. Shaft current, stator The derivative function of the synthesized current of the exciter is obtained from the shaft current.

[0010] Generate a first square wave signal with the same frequency as the derivative of the synthesized current of the exciter; generate a sine wave signal with the same frequency and orthogonal phase as the first square wave signal as the second square wave signal;

[0011] When the first square wave signal and the second square wave signal are at their rising edges, the stator current of the exciter is sampled to obtain the envelope signal of the rotor position of the exciter.

[0012] The exciter rotor position angle increment is obtained from the envelope signal of the exciter rotor position. The main motor rotor position angle increment is obtained from the pole pair relationship between the exciter and the main motor based on the exciter rotor position angle increment.

[0013] The rotor position of the main motor is estimated based on the rotor position angle increment and the initial rotor position.

[0014] A further technical solution of the present invention is as follows: the step of obtaining the three-phase stator current of the exciter is: applying a three-phase symmetrical voltage on the stator side of the exciter and collecting the three-phase stator current of the exciter.

[0015] A further technical solution of the present invention is: to perform Clark transformation on the three-phase stator current of the exciter to obtain the static coordinate system. shaft current, Axis current.

[0016] A further technical solution of the present invention is: based on the stator of the exciter Shaft current, stator The steps to obtain the derivative function of the exciter's synthesized current from the shaft current are as follows:

[0017]

[0018] In the formula, The derivative of the resultant current of the exciter; The stator of the exciter The derivative of the shaft current; The stator of the exciter The derivative of the shaft current.

[0019] A further technical solution of the present invention is as follows: the expression for the envelope signal of the exciter rotor position obtained by sampling is:

[0020]

[0021] In the formula, This represents the envelope sinusoidal signal related to the rotor position of the exciter, obtained by sampling the stator current of the exciter when the first square wave signal is at its rising edge. This represents the envelope cosine signal related to the rotor position of the exciter, obtained by sampling the stator current of the exciter when the second square wave signal is at its rising edge. For the number of pole pairs of the exciter, The mechanical speed of the exciter during operation; Sampling time.

[0022] A further technical solution of the present invention is as follows: the envelope signal of the exciter rotor position is input into the quadrature phase-locked loop to obtain the exciter angle increment. Based on the exciter angle increment, the ratio of the operating speed of the exciter magnetic field to the mechanical speed of the exciter during operation is used to obtain the exciter rotor position angle increment during operation.

[0023] A further technical solution of the present invention is: the exciter rotor position angle increment is obtained by dividing the exciter angle increment by the ratio of the exciter magnetic field operating speed to the mechanical speed of the exciter during operation.

[0024] A further technical solution of the present invention is as follows: the step of obtaining the rotor position angle increment of the main motor based on the rotor position angle increment of the exciter and the pole pair relationship between the exciter and the main motor is as follows:

[0025] Obtain the pole pair ratio of the main motor and the exciter;

[0026] The increment of the exciter rotor position angle is obtained by dividing the pole pair ratio.

[0027] A further technical solution of the present invention is to use the rotor position angle increment of the main motor and the sum of the initial rotor position as the rotor position of the main motor.

[0028] The beneficial effects of this invention are:

[0029] Compared to existing rotor position estimation methods based on exciter rotor flux linkage or back EMF, this invention analyzes the waveform characteristics of the exciter back EMF in the exciter stator current, i.e., the waveform characteristics of the exciter's synthetic current derivative function. Based on these waveform characteristics, two square wave signals with orthogonal phases and the same frequency as the exciter's synthetic current derivative function are generated. The envelope signal of the exciter rotor position can be extracted from these two square wave signals and the exciter stator current signal. Therefore, the exciter rotor position angle increment can be estimated based on the exciter rotor position angle increment. The main motor rotor position angle increment is obtained based on the exciter rotor position angle increment and the pole pair relationship between the exciter and the main motor. Finally, the main motor rotor position is estimated based on the main motor rotor position angle increment and the initial rotor position. This entire process requires no exciter rotor parameters, has a lower computational load, is applicable across the entire speed range, improves the stability of exciter-based nonlinear harmonic rotor position estimation methods, and provides more accurate rotor position estimation. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart illustrating a parameter-free main motor rotor position estimation method according to the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of the brushless electrically excited synchronous motor in this embodiment;

[0033] Figure 3 This is a schematic diagram of the three-phase current waveforms of the exciter rotor.

[0034] Figure 4 This is a schematic diagram of the derivative function of the synthesized current of the exciter;

[0035] Figure 5 This is a schematic diagram of the first square wave signal;

[0036] Figure 6 This is a detailed flowchart of the main motor rotor position estimation method proposed in this invention;

[0037] Figure 7 This is a schematic diagram showing the actual rotor position of the main motor in an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram showing the estimation results of the main motor rotation angle and the exciter rotation angle in an embodiment of the present invention;

[0039] Figure 9 This is a schematic diagram of the rotor position estimation result of the main motor proposed in this invention;

[0040] Figure 10 This is a schematic diagram illustrating the error between the actual rotor position and the estimated rotor position of the main motor proposed in this invention.

[0041] Figure 11 This is the estimated speed of the main motor proposed in this invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] An embodiment of the parameter-free main motor rotor position estimation method of the present invention is as follows: Figure 1 and Figure 6 As shown, it includes:

[0044] S1. Obtain the derivative function of the synthesized current of the exciter;

[0045] Specifically, the three-phase stator current of the exciter is obtained and converted into... Stator of exciter in stationary coordinate system Shaft current, stator Shaft current; and according to the stator of the exciter. Shaft current, stator The shaft current is used to obtain the derivative function of the synthesized current of the exciter.

[0046] For example, in one specific embodiment, the step of obtaining the three-phase stator current of the exciter is as follows: applying a three-phase symmetrical voltage to the stator side of the exciter, and collecting the three-phase stator current of the exciter, that is, applying a three-phase voltage to the stator side of the exciter: Phase A voltage Phase B voltage and C-phase voltage This allows the acquisition of the three-phase stator current of the exciter: Phase A stator current. B-phase stator current C-phase stator current .

[0047] For example, in one specific embodiment, the three-phase stator current is converted into... stationary coordinate system shaft current, The steps for obtaining the shaft current are as follows: Perform Clark transformation on the three-phase stator currents of the exciter to obtain the stator current of the exciter in the stationary coordinate system. Shaft current, stator shaft current, where the expression is:

[0048]

[0049] In the formula, The stator of the exciter shaft current; The stator of the exciter Axis current.

[0050] For example, according to the stator of the exciter Shaft current, stator The steps to obtain the derivative of the resultant current of the exciter from the shaft current are as follows: Define the stator of the exciter. The derivative of the shaft current is The stator of the exciter The derivative of the shaft current is The stator of the exciter Shaft current, stator The magnitude of the derivative function corresponding to the shaft current is used as the derivative function of the resultant current of the exciter. That is, the derivative of the resultant current of the exciter. The expression is:

[0051]

[0052] In the formula, The derivative of the resultant current of the exciter; The stator of the exciter The derivative of the shaft current; The stator of the exciter The derivative of the shaft current.

[0053] In one specific embodiment, the waveform of the derivative function of the exciter's synthesized current is shown below. Figure 4 As shown, from Figure 4 As can be seen from this, the frequency is , in, , For the number of pole pairs of the exciter, For mechanical rotation speed, The rotational angular frequency of the three-phase AC voltage applied to the stator side of the exciter; ω is the rotational angular frequency of the exciter rotor.

[0054] S2. Generate the first square wave signal and the second square wave signal;

[0055] Specifically, a first square wave signal with the same frequency as the derivative function of the exciter's synthesized current is generated; a second square wave signal with the same frequency and orthogonal phase as the first square wave signal is generated.

[0056] For example, in one specific embodiment, the step of generating a first square wave signal with the same frequency as the derivative function of the exciter's synthesized current is: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] Sampling is performed, and results are obtained through comparison. Maximum value. When the derivative of the exciter's synthesized current... When the maximum value is reached, the generated signal is momentarily set to 1, and then immediately set to 0. This results in a signal with an indefinite duty cycle, an amplitude varying between 0 and 1, and a frequency of... The square wave signal is denoted as the first square wave signal. .

[0057] For example, in one specific embodiment, the step of generating a sinusoidal signal with the same frequency and orthogonal phase as the first square wave signal as the second square wave signal is: that is, generating a sinusoidal signal with a frequency of Phase and the first square wave signal Orthogonal (i.e., second square wave signal) With the first square wave signal A sinusoidal signal with a phase difference of 90° and an amplitude of 1 is denoted as the second square wave signal. .

[0058] S3. Sample the stator current of the exciter to obtain the envelope signal of the rotor position of the exciter;

[0059] For example, in one specific embodiment, when the first square wave signal and the second square wave signal are at their rising edges, the stator current of the exciter is sampled to obtain the envelope signal of the exciter rotor position. It should be noted that sampling is not performed when the first square wave signal and the second square wave signal are at their falling edges or 0. The expression for the envelope signal of the exciter rotor position is as follows:

[0060]

[0061] In the formula, This represents the envelope sinusoidal signal related to the rotor position of the exciter, obtained by sampling the stator current of the exciter when the first square wave signal is at its rising edge. This represents the envelope cosine signal related to the rotor position of the exciter, obtained by sampling the stator current of the exciter when the second square wave signal is at its rising edge. For the number of pole pairs of the exciter, The mechanical speed of the exciter during operation; Sampling time.

[0062] S4. Obtain the rotor position angle increment of the main motor;

[0063] Specifically, the exciter rotor position angle increment is obtained based on the envelope signal of the exciter rotor position, and the main motor rotor position angle increment is obtained based on the exciter rotor position angle increment and the pole pair relationship between the exciter and the main motor.

[0064] For example, in one specific embodiment, the step of obtaining the exciter rotor position angle increment based on the envelope signal of the exciter rotor position is as follows: inputting the envelope signal of the exciter rotor position into the quadrature phase-locked loop to obtain the exciter angle increment; and obtaining the exciter rotor position angle increment based on the ratio of the exciter magnetic field operating speed to the exciter mechanical speed during operation. In this embodiment, the ratio of the exciter magnetic field operating speed to the exciter mechanical speed during operation is 6, that is, the exciter rotor position angle increment can be obtained by dividing the exciter angle increment by 6.

[0065] For example, in one specific embodiment, the step of obtaining the main motor rotor position angle increment based on the exciter rotor position angle increment and the pole pair ratio of the exciter and the main motor is as follows: obtain the pole pair ratio of the main motor and the exciter; divide the exciter rotor position angle increment by the pole pair ratio to obtain the main motor rotor position angle increment.

[0066] S5. Estimate the rotor position of the main motor;

[0067] For example, in one specific embodiment, the sum of the main motor rotor position angle increment and the initial rotor position is used as the estimated rotor position of the main motor.

[0068] The following is in conjunction with the appendix Figures 3 to 11 The invention is further illustrated by specific simulation data:

[0069] This example uses MATLAB / Simulink to... Figure 2 The brushless electrically excited synchronous motor shown was simulated and verified. The initial rotor position of the main motor was set as follows: When the time is 0-8s, the excitation frequency of the exciter stator is 200Hz, the speed is 0-500r / min, the number of pole pairs of the exciter is 3, and the number of pole pairs of the main motor is 2.

[0070] Step 1: Obtain the derivative function of the synthesized current of the exciter;

[0071] First, analyze the waveform characteristics of the exciter's back-electrode during motor operation. The specific steps are as follows:

[0072] like Figure 3 As shown, the expression for the three-phase rotor current of the exciter in discontinuous commutation mode is analyzed. Within a single commutation cycle, the rotor three-phase current can be expressed as:

[0073]

[0074] in, The excitation current of the main motor ω is the rotational angular frequency of the exciter rotor; For rotor inductance; Let be the amplitude of the induced electromotive force of the exciter rotor; the three-phase rotor currents are as follows: Phase rotor current , b Phase rotor current , c Phase rotor current .

[0075] Rotor three-phase current through abc coordinate, dq After coordinate transformation and differentiation, the exciter rotor... d The derivative of the shaft current, q The derivative of the shaft current can be written as:

[0076]

[0077] In the formula, Indicates the exciter rotor d The derivative of the shaft current; Indicates the exciter rotor q The derivative of the shaft current; Represents the differential operator; Indicates the exciter The derivative of the phase rotor current; Indicates the exciter b The derivative of the phase rotor current; Indicates the exciter c The derivative of the phase rotor current;

[0078] Wherein, rotation matrix C The expression is:

[0079]

[0080] In the formula, This indicates the rotor position of the exciter.

[0081] Then the exciter rotor d The derivative of the shaft current, q The specific expression for the derivative of the shaft current is:

[0082]

[0083]

[0084] It can be seen that the exciter rotor dq The shaft current derivative can be divided into three parts: Part I, Part II, and Part III; due to the rotor inductance... The amplitude of the induced electromotive force of the exciter rotor is relatively small. The exciter rotor is relatively large, therefore... d Axial current derivative, q The main part of the axial current derivative is the corresponding Part I portion. Part II is sufficiently small compared to Part I and can be ignored. For Part III, since... Much larger Therefore, Part III can be disregarded compared to Part I, hence the exciter rotor... d The derivative of the shaft current, q The derivative of the shaft current can be rewritten as:

[0085]

[0086] The expression for the exciter stator voltage equation is as follows:

[0087]

[0088] in, This indicates the mutual inductance between the stator and rotor of the exciter; This represents the stator inductance of the exciter; This represents the rotor resistance of the exciter; in the voltage expression, , , and As the main component, therefore, the stator of the exciter Derivative of shaft current, stator The derivative of the shaft current is:

[0089]

[0090] Then, within a single commutation cycle, the magnitude of the stator current derivative of the exciter, i.e., the derivative function of the exciter's resultant current, can be expressed as:

[0091]

[0092] Among them, such as Figure 4 The waveform shown is the derivative of the exciter's synthetic current. Within one commutation cycle, it is a monotonically increasing sawtooth wave, and the duration of a single sawtooth wave corresponds to... Figure 4 The duration of the commutation process for the three-phase rotor current. Since one commutation cycle is 1 / 6 of the exciter rotor current cycle, the frequency of the exciter's resultant current derivative is... The frequency of this signal changes continuously with the speed of the motor.

[0093] Step 2: Generate the first square wave signal and the second square wave signal;

[0094] First square wave signal The derivative of the combined current of the exciter The frequency remains consistent, that is, the frequency is ,like Figure 5 As shown, the second square wave signal The phase of the first square wave signal Orthogonal (i.e., second square wave signal) With the first square wave signal (90° phase difference) Second square wave signal With the first square wave signal The amplitude is 1.

[0095] Step 3: Obtain the envelope signal of the exciter rotor position;

[0096] When the first square wave signal and the second square wave signal are at their rising edges, the stator current of the exciter is sampled to obtain the envelope signal of the exciter rotor position.

[0097] Step 4: Obtain the rotor position angle increment of the main motor and estimate the rotor position of the main motor;

[0098] After Figure 6 Following the estimation process shown, the incremental rotor position angle of the main motor is obtained. This is then added to the known initial rotor position of the main motor to obtain the estimated position of the main motor.

[0099] The estimation process is as follows Figure 7-10 As shown, firstly, Figure 7 The actual rotor position of the main motor during startup is given first. Figure 8 The envelope signal is transmitted via a quadrature phase-locked loop (PLL). Figure 6 As shown, the rotor position angle increment of the exciter is obtained (dashed line), and the rotor position angle increment of the main motor is obtained according to the pole pair number relationship (solid line). Figure 9 The estimated rotor position of the main motor is obtained by adding the rotor position angle increment of the main motor to the known initial position of the main motor. Figure 10 The error between the actual position and the estimated position of the main motor rotor. Figure 11 The estimated speed of the main motor, from Figure 10It can be seen that the error in the starting process is controlled within ±5 electrical degrees. This accuracy can meet the requirements of sensorless starting control of a three-stage motor, which demonstrates the effectiveness and advantages of the method of the present invention.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A parameter-free method of estimating the position of a rotor of a main electric machine, characterized in that, The method comprises the steps that: the three-phase stator currents of the exciter are converted into the stator of the exciter in the stationary coordinate system the rotor currents, the stator the rotor currents; and the stator of the exciter the rotor currents, the stator the rotor currents, the stator of the exciter the rotor currents, the stator the rotor currents, the stator of the exciter wherein represents the exciter machine composite current derivative function; represents the exciter machine stator axial current derivative function; represents the exciter machine stator axial current derivative function; a first square wave signal with the same frequency as the composite current guide function of the exciter is generated, and a sine signal with the same frequency and orthogonal phase as the first square wave signal is generated as a second square wave signal; when the first square wave signal and the second square wave signal are at rising edges, the stator current of the exciter is sampled to obtain an envelope signal of the exciter rotor position; an exciter rotor position angle increment is obtained according to the envelope signal of the exciter rotor position, and a main motor rotor position angle increment is obtained according to the exciter rotor position angle increment and the pole pair number relationship between the exciter and the main motor; the rotor position of the main motor is estimated according to the main motor rotor position angle increment and the initial rotor position.

2. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, The step of obtaining the three-phase stator current of the exciter is that: a three-phase symmetrical voltage is applied to the stator side of the exciter, and the three-phase stator current of the exciter is collected.

3. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, The three-phase stator current of the exciter is clark-transformed to obtain the axis current, axis current.

4. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, The expression of the envelope signal of the exciter rotor position obtained by sampling is: wherein represents an envelope sine signal related to the rotor position of the exciter obtained by sampling the stator current of the exciter when the first square wave signal is at the rising edge; represents an envelope cosine signal related to the rotor position of the exciter obtained by sampling the stator current of the exciter when the second square wave signal is at the rising edge; is the number of pole pairs of the exciter, is the mechanical rotational speed of the exciter when in operation; is the sampling time.

5. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, the exciter angle increment is obtained by inputting the envelope signal of the exciter rotor position into a quadrature phase-locked loop, and the exciter rotor position angle increment is obtained according to the exciter angle increment and the speed ratio of the exciter magnetic field running speed to the mechanical speed of the exciter when the exciter is running.

6. A parameter-free method of estimating the rotor position of a main electric machine according to claim 5, characterized in that, The exciter rotor position angle increment is obtained by dividing the exciter angle increment by the speed ratio of the exciter magnetic field running speed to the mechanical speed of the exciter when the exciter is running.

7. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, The step of obtaining the main motor rotor position angle increment according to the exciter rotor position angle increment and the pole pair number relationship between the exciter and the main motor is that: the pole pair number ratio of the main motor and the exciter is obtained; the main motor rotor position angle increment is obtained by dividing the exciter rotor position angle increment by the pole pair number ratio.

8. A parameter-free method of estimating the rotor position of a main electric machine according to claim 1, characterized in that, The sum of the main motor rotor position angle increment and the initial rotor position is taken as the rotor position of the main motor.

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