Three-stage starting generator rotor position estimation method suitable for single-phase exciter

Abstract

The application discloses a three-stage starting generator rotor position estimation method suitable for a single-phase exciter, and belongs to the field of motor control. The method estimates the rotor d-axis current and extracts its outer envelope by applying an alternating voltage on the exciter stator side and collecting the stator current. The outer envelope crest and trough are detected to generate the discrete position state of the exciter. The discrete state of the main motor is generated according to the pole pair ratio and the duration is recorded. The discrete rotor position of the main motor and the interval average speed are calculated accordingly. The continuous rotor angle is obtained by using the previous interval speed compensation, and the real-time rotor position is obtained by combining the initial position. The application can realize high-precision estimation of the rotor position of the main motor by using only the electrical signal characteristics of the single-phase exciter itself, without the need for a mechanical position sensor. The application solves the problem that the existing method cannot be applied to the single-phase exciter structure, and has good stability and robustness in severe environments such as aviation high temperature and high pressure, strong electromagnetic interference and the like.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically relating to a method for estimating the position of a starter generator rotor, and more specifically to a method for estimating the position of a three-stage starter generator rotor applicable to a single-phase exciter. Background Technology

[0002] The starter / generator is a key component of a multi-electric aircraft system, integrating engine starting and onboard power supply functions, significantly reducing the mechanical complexity of the aircraft engine system. Aviation three-stage generators are widely used in integrated starter-generator systems due to their mature power generation technology and high reliability. For example... Figure 1 As shown, the three-stage motor consists of a main generator, an exciter, and an auxiliary exciter mounted coaxially, with a rotating rectifier connecting the rotor windings of the main generator and the exciter.

[0003] In starting mode, AC excitation is applied to the stator side of the exciter. The induced electromotive force is rectified and then provides DC excitation current to the main generator rotor. The main generator is then driven by an inverter to start the aero-engine. To meet the starting requirements under different load conditions, it is essential to ensure that the main generator has sufficient excitation current to generate the required electromagnetic torque. To this end, the industry has proposed various exciter solutions, such as... Figure 2 The three-phase exciter and the two-phase exciter shown both structures can provide rotating electromotive force.

[0004] During the startup phase, high-precision main motor rotor position is crucial for achieving high-performance startup control, typically achieved using mechanical position sensors. However, aerospace three-stage motors operate under high temperature, high pressure, and strong vibration environments for extended periods, which reduces the reliability of position sensors; furthermore, the sensors are idle when the motor is in the generator phase for extended periods. Therefore, sensorless startup control has become a cost-effective solution and a hot research topic.

[0005] Rotating rectifiers are a unique structure in brushless synchronous starters / generators, generating abundant internal harmonics during operation. These harmonics can be used as excitation signals to estimate the exciter rotor position. Since the main motor and exciter are coaxially mounted, the main motor rotor position can be deduced from the exciter rotor position, thus avoiding the use of mechanical sensors. Based on this principle, researchers have developed technologies for multiphase exciters capable of generating rotating magnetic fields (such as...). Figure 2 A corresponding sensorless control method was developed for the three-phase or two-phase exciter shown, and good results were achieved.

[0006] However, the most widely used and dominant type of three-stage motor starting / generating system in aviation is actually the simpler single-phase exciter. The aforementioned sensorless position method based on exciter harmonics, which relies on a multiphase rotating magnetic field, cannot be directly applied to the single-phase exciter structure. On the other hand, some methods attempting to estimate the position of the single-phase exciter directly based on the main motor signal are easily affected by changes in the main motor's salient polarity and rotor inductance parameters, making it difficult to guarantee stability and reliability in the harsh environment of aviation with high temperature, high pressure, and strong electromagnetic interference. Summary of the Invention

[0007] The purpose of this invention is to solve the problems that existing sensorless control methods based on exciter harmonics cannot be applied to single-phase exciter structures, and that estimation methods based on main motor signals have poor stability in harsh aviation environments. The invention proposes a method that utilizes the electrical signal characteristics of the single-phase exciter itself, and achieves continuous and accurate estimation of the main motor rotor position by discretizing the rotor current envelope and compensating for its speed.

[0008] To achieve the above objectives, the technical solution provided by this invention is:

[0009] A method for estimating the rotor position of a three-stage starting generator suitable for a single-phase exciter is provided, comprising the following steps:

[0010] Step 1: Apply AC voltage to the stator side of the exciter and collect the exciter stator current;

[0011] Step 2: Estimate the d-axis current of the exciter rotor based on the stator side voltage and stator current of the exciter;

[0012] Step 3: Superimpose a square wave signal into the d-axis current of the exciter rotor. By detecting the current response within the period of the square wave signal, extract the maximum and minimum values ​​of the d-axis current of the exciter rotor, and calculate the outer envelope of the d-axis current of the exciter rotor based on the maximum and minimum values.

[0013] Step 4: Detect the peaks and troughs of the obtained outer envelope, and generate a discrete state sequence of the exciter rotor position based on the detection results of the peaks and troughs.

[0014] Step 5: Based on the generated discrete state sequence of the exciter rotor position, and combined with the ratio of the number of pole pairs between the main motor and the exciter, establish the discrete state sequence of the main motor, and record the duration of each discrete state of the main motor.

[0015] Step 6: Calculate the discrete rotor position of the main motor based on the established discrete state sequence of the main motor, and calculate the average speed of the main motor in the current discrete interval based on the fixed electrical angle step size and duration corresponding to each discrete state of the main motor.

[0016] Step 7: Use the calculated average speed of the main motor to compensate for the rotor position in the current discrete interval to obtain the continuous rotor rotation angle of the main motor. Add the rotation angle to the initial position of the main motor to obtain the real-time rotor position of the main motor.

[0017] Furthermore, in step 2, the specific calculation formula for estimating the d-axis current of the exciter rotor is as follows:

[0018]

[0019] In the formula, This refers to the d-axis current of the exciter rotor. For the mutual inductance between the stator and rotor of the exciter, This is the stator side voltage of the exciter. For the exciter stator resistance, This refers to the stator current of the exciter. This is the stator inductance of the exciter.

[0020] Furthermore, in step 3, the specific process for calculating the outer envelope of the exciter rotor d-axis current is as follows:

[0021]

[0022] In the formula, This is the outer envelope of the d-axis current of the exciter rotor. and These are the maximum and minimum values ​​of the exciter rotor d-axis current within a single square wave signal period, respectively.

[0023] Furthermore, the outer envelope The quantitative expression is:

[0024]

[0025] In the formula, This refers to the rotor position angle of the exciter. is the excitation current constant.

[0026] Furthermore, in step 4, the specific process of generating the discrete state sequence of the exciter is as follows: calculate the derivative function of the outer envelope, detect the zero-crossing point of the derivative function, initialize the discrete state of the exciter to 0, and increment by 1 each time a zero-crossing point is detected. When it increases to 11, it is automatically cleared to zero, thus obtaining 12 discrete states from 0 to 11, each discrete state corresponding to an electrical angle of π / 6.

[0027] Furthermore, in step 5, the specific process of generating the discrete state sequence of the main motor is as follows: the discrete state of the main motor is initialized to 0; each time a change in the discrete state of the exciter is detected, the discrete state of the main motor is increased by 1; when it increases to a preset maximum value... Automatically reset to zero, thus obtaining common There are discrete state values, among which The total number of discrete states of the main motor within one electrical cycle is determined based on the ratio of the number of pole pairs of the main motor and the exciter. The specific calculation formula is as follows:

[0028]

[0029] In the formula, and These are the number of pole pairs for the main motor and the exciter, respectively.

[0030] Furthermore, when the extreme logarithmic ratio When the number is not an integer, the total number of discrete states takes an integer value.

[0031] Furthermore, in step 6, the formula for calculating the discrete rotor position of the main motor is:

[0032]

[0033] In the formula, The current discrete state value of the main motor, with a value range of [value missing]. , The total number of discrete states of the main motor within one electrical cycle. Discrete rotor position of the main motor; fixed electrical angle step size is... The formula for calculating the average speed of the main motor within the current discrete interval is:

[0034]

[0035] In the formula, The average speed of the main motor within the current discrete interval. The duration of the discrete state of the main motor.

[0036] Furthermore, step 7 specifically includes:

[0037] Step 7.1: Utilize the average rotational speed calculated from the previous discrete interval. Compensation is performed on the rotor position within the current discrete interval to obtain the continuous rotation angle of the main motor rotor:

[0038]

[0039] In the formula, This represents the time elapsed within the current discrete interval;

[0040] Step 7.2, calculate the compensated rotor rotation angle of the main motor. relative to the initial position of the main motor By adding them together, we can obtain the real-time rotor position of the main motor: .

[0041] The advantages of this invention are:

[0042] This invention provides a rotor position estimation method for a three-stage starter generator suitable for single-phase exciters. The method estimates the d-axis current of the exciter rotor by applying an AC voltage to the stator side of the exciter and collecting the stator current. Based on this, a square wave signal is superimposed to extract the maximum and minimum values ​​of the current response, thereby calculating the outer envelope of the rotor d-axis current. By detecting the peaks and troughs of this outer envelope, a discrete state sequence of the exciter rotor position is generated. Then, combined with the ratio of the number of pole pairs between the main motor and the exciter, a discrete state sequence of the main motor is established, and the duration of each state is recorded. Subsequently, the discrete rotor position is calculated based on the discrete state sequence of the main motor, and the average rotational speed within each discrete interval is calculated based on a fixed electrical angle step size and duration. Finally, the rotor position in the current interval is compensated using the average rotational speed of the previous discrete interval to obtain continuous main motor rotor rotation angles. These angles are then added to the initial position to obtain the real-time rotor position. This method fully utilizes the current harmonic characteristics generated by the single-phase exciter during operation. Through discrete state partitioning and speed compensation strategies, it achieves accurate estimation of the main motor rotor position without the need for mechanical position sensors, effectively overcoming the limitation of multi-phase exciter methods being unsuitable for single-phase structures. Furthermore, because this method processes the exciter's own electrical signals and does not rely on the main motor's saliency polarity and inductance parameters, it maintains good stability and anti-interference capabilities even in harsh environments with high temperatures, high pressures, and strong electromagnetic interference. Simulation results show that after a brief initial phase during startup, the position estimation error converges to within ±5°, meeting the practical engineering requirements for sensorless starting control of three-stage motors. Attached Figure Description

[0043] The above and / or other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, which are not drawn to scale and some features are enlarged or reduced to show details of specific parts.

[0044] Figure 1 This is a schematic diagram of the overall structure of a three-stage starter generator.

[0045] Figure 2 The diagram shows a comparison of the exciter structure of a three-stage starter generator, where (a) and (b) are the structural forms of a three-phase exciter and a two-phase exciter, respectively.

[0046] Figure 3 This is a flowchart illustrating the overall process of a three-stage starter generator rotor position estimation method applicable to single-phase exciters according to an embodiment of the present invention.

[0047] Figure 4 This is a schematic diagram of the correlation waveform between the d-axis current of the single-phase exciter rotor and the position of the exciter rotor in an embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of the calculation process for the discrete state of the exciter in an embodiment of the present invention;

[0049] Figure 6 This is a schematic diagram of the calculation results of the discrete state of the exciter rotor position in an embodiment of the present invention, wherein (a) is the waveform of the outer envelope of the d-axis current of the exciter rotor, (b) is the curve of the discrete state change of the exciter, and (c) is the curve of the counter change corresponding to each discrete state.

[0050] Figure 7 This is a schematic diagram of the overall calculation process for the main motor rotor position in an embodiment of the present invention;

[0051] Figure 8 This is a schematic diagram of the calculation results of the main motor's estimated rotation angle in an embodiment of the present invention, wherein (a) is the discrete state change curve of the exciter, (b) is the discrete state change curve of the main motor, and (c) is the change waveform of the main motor's estimated rotation angle.

[0052] Figure 9 This is a schematic diagram of the result of estimating the rotor position of the main motor in an embodiment of the present invention, wherein (a) is the waveform of the actual position change of the main motor, (b) is the comparison waveform of the discrete state of the main motor and the discrete state of the exciter changing with time, (c) is the waveform of the real-time estimated rotor position change of the main motor, (d) is the curve of the estimated change of the main motor speed, and (e) is the curve of the estimation error of the main motor rotor position. Detailed Implementation

[0053] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments thereof. It should be noted that the following detailed description of the present invention is for illustrative purposes only and is not intended to limit the scope of the invention.

[0054] This invention addresses the problem that existing sensorless control methods based on exciter harmonics are not applicable to single-phase exciter structures, while estimation methods based on the main motor suffer from poor stability in harsh aviation environments. It proposes a technical solution that utilizes the electrical signal characteristics of the single-phase exciter itself to achieve accurate estimation of the main motor rotor position.

[0055] In this exemplary embodiment, the number of exciter pole pairs of the three-stage starter generator Number of pole pairs of the main motor Both are mounted coaxially. The initial position of the main motor is set to... During startup, the motor accelerates uniformly from rest, with the speed increasing from 0 to 200 r / min within 0-3 seconds. The AC voltage applied to the stator side of the exciter has a frequency of 200 Hz. The following is combined with... Figure 3 The flowchart shown describes the overall process of implementing this invention, and the implementation steps are described in detail.

[0056] Step S1: Apply excitation voltage and collect current.

[0057] A frequency of is applied to the stator side of the exciter. Amplitude AC voltage Simultaneously, the stator current is collected through a current sensor. This step provides the foundational data for subsequent current analysis and location estimation.

[0058] Step S2: Estimate the d-axis current of the exciter rotor.

[0059] Based on the measured exciter stator voltage and stator current Estimate the d-axis current of the exciter rotor. The estimation formula is:

[0060]

[0061] In the formula, For the mutual inductance between the stator and rotor of the exciter, For the exciter stator resistance, This is the stator inductance of the exciter.

[0062] Step S3: Extract the outer envelope of the current.

[0063] Generate a frequency related to the excitation frequency Equal square wave signals are superimposed on the rotor d-axis current. Then, the maximum current value within each square wave cycle is collected. and minimum value And calculate the outer envelope according to the following formula. :

[0064]

[0065] like Figure 4 As shown, With the position of the exciter rotor It exhibits periodic fluctuations, with 12 peaks and troughs appearing within one electrical angle period (0–360°). Theoretical analysis shows… It can be approximated as:

[0066]

[0067] In the formula, Let be the excitation current constant. From this expression, it can be deduced that the peak appears at... The trough appeared or ,in It is an integer.

[0068] Step S4: Generate the discrete state sequence of the exciter.

[0069] Calculate the outer envelope derivative function ,in For differential operators, The time constant is used for subsequent detection. The point crossing zero. Whenever When it crosses zero, it indicates An extreme point is reached. The discrete state counter of the exciter is initialized to 0. Each time a zero-crossing is detected, the counter is incremented by 1. When the count value increases to 11, it is automatically reset to zero, thus obtaining 12 discrete states from 0 to 11. Each discrete state of the exciter rotor position corresponds to one electrical angle step of the exciter. . Figure 5 A complete flowchart for the discrete state calculation of the exciter is presented, clearly showing the processing logic from the outer envelope input to the discrete state output. Figure 6 The waveform diagram for this process is given, showing, from top to bottom, the exciter rotor d-axis current obtained based on the synchronization signal sampling. outer envelope The final generated discrete state sequence, and the counters under different discrete states. It can be seen that the changes in the discrete states are related to... The extreme points are precisely synchronized.

[0070] Step S5: Generate the discrete state sequence of the main motor and record the time.

[0071] Since the main motor and exciter are coaxially mounted, they have the same mechanical angular velocity, but the electrical angle period is inversely proportional to the number of pole pairs. Each discrete state (electrical angle increment) experienced by the exciter... The electrical angle increment corresponding to the main motor is Therefore, one complete electrical cycle of the main motor ( The total number of discrete states required for:

[0072]

[0073] Substitute the parameters in this embodiment , ,have to That is, the discrete states of the main motor are 18 values ​​from 0 to 17, and the electrical angle step size corresponding to each state is... Generally, when the ratio of extreme logarithms... When it is a non-integer, Integer values ​​must be used to ensure the integer number of discrete states. In practical applications, the number of pole pairs can be determined by rounding or rounding down.

[0074] In actual implementation, the main motor discrete state counter is initialized to 0. Each time the exciter's discrete state changes (i.e., a change in the exciter's state value is detected), the main motor discrete state counter is incremented by 1. The counter is automatically reset to zero when it reaches a preset maximum value of 17. Simultaneously, the duration of each main motor discrete state is recorded. ( (), that is, the time that the state takes from the beginning to the end.

[0075] Step S6: Calculate the discrete rotor position and average speed of the main motor.

[0076] Reference Figure 7 It illustrates the processing steps from generating the discrete state of the main motor to the final estimated position output. First, based on the current discrete state value of the main motor... Calculate the corresponding discrete rotor position (i.e., the electrical angle at the starting point of this state):

[0077]

[0078] For example, when hour ; hour And so on.

[0079] The main motor is in the current discrete interval (i.e., the first discrete interval). The range of electrical angles covered by each state Average speed within ) It can be calculated based on a fixed step size and the actual measurement time:

[0080]

[0081] An equivalent form can also be obtained by converting the exciter angle:

[0082]

[0083] The results from both methods are consistent. Figure 8 The discrete states of the exciter and the main motor are shown, as well as the estimated rotation angle of the main motor.

[0084] Step S7: Compensate to obtain continuous rotor position and output the final result.

[0085] Because of the information given in step S6 This only provides the starting position of each discrete interval. To obtain the continuous position at any given time, rotational speed compensation is required. The specific compensation process consists of two steps:

[0086] Step S7.1, assume the current time is at the i-th Within a discrete interval, and the time elapsed in that interval is... ( Then, the electrical angle increment at the current moment relative to the starting point of this interval is: ,in The average rotational speed calculated for the previous discrete interval (used to approximate the instantaneous rotational speed within the current interval). Therefore, the current continuous rotor rotation angle is:

[0087]

[0088] For the first interval ( The initial rotational speed can be used for compensation.

[0089] Step S7.2, the rotor rotation angle obtained above is... With the known initial position of the main motor Adding them together gives the real-time absolute rotor position of the main motor:

[0090]

[0091] Figure 9 The final estimation result of this embodiment is shown. In the initial stage of startup (approximately within the first second), since the speed has not yet stabilized, the position estimation error is within 13°; after about 10 discrete states, the speed compensation algorithm enters the stable operating region, and the error quickly converges to within ±5°. This accuracy fully meets the requirements of sensorless starting control of a three-stage motor.

[0092] Throughout the process, this invention utilizes only the electrical signal characteristics of the single-phase exciter itself, achieving continuous and accurate estimation of the main motor rotor position through discrete state partitioning and speed compensation, without requiring any mechanical position sensors. Because the algorithm is based on the inherent harmonics of the exciter current and does not depend on the saliency polarity and inductance parameters of the main motor, it maintains excellent stability and robustness even in harsh environments such as high-temperature, high-pressure, and strong electromagnetic interference in aviation.

[0093] Finally, it should be noted that the features mentioned and / or shown in the above description of exemplary embodiments of the present invention can be combined in the same or similar manner with one or more other embodiments, combined with or substituted for corresponding features in other embodiments. These combined or substituted technical solutions should also be considered to be included within the scope of protection of the present invention.

Claims

1. A method for estimating the rotor position of a three-stage starting generator suitable for a single-phase exciter, characterized in that, Includes the following steps: Step 1: Apply AC voltage to the stator side of the exciter and collect the exciter stator current; Step 2: Estimate the d-axis current of the exciter rotor based on the stator side voltage and stator current of the exciter; Step 3: Superimpose a square wave signal into the d-axis current of the exciter rotor. By detecting the current response within the period of the square wave signal, extract the maximum and minimum values ​​of the d-axis current of the exciter rotor, and calculate the outer envelope of the d-axis current of the exciter rotor based on the maximum and minimum values. Step 4: Detect the peaks and troughs of the obtained outer envelope, and generate a discrete state sequence of the exciter rotor position based on the detection results of the peaks and troughs. Step 5: Based on the generated discrete state sequence of the exciter rotor position, and combined with the ratio of the number of pole pairs between the main motor and the exciter, establish the discrete state sequence of the main motor, and record the duration of each discrete state of the main motor. Step 6: Calculate the discrete rotor position of the main motor based on the established discrete state sequence of the main motor, and calculate the average speed of the main motor in the current discrete interval based on the fixed electrical angle step size and duration corresponding to each discrete state of the main motor. Step 7: Use the calculated average speed of the main motor to compensate for the rotor position in the current discrete interval to obtain the continuous rotor rotation angle of the main motor. Add the rotation angle to the initial position of the main motor to obtain the real-time rotor position of the main motor.

2. The rotor position estimation method for a three-stage starter generator according to claim 1, characterized in that, In step 2, the specific calculation formula for estimating the d-axis current of the exciter rotor is as follows: In the formula, This refers to the d-axis current of the exciter rotor. For the mutual inductance between the stator and rotor of the exciter, This is the stator side voltage of the exciter. For the exciter stator resistance, This refers to the stator current of the exciter. This is the stator inductance of the exciter.

3. The rotor position estimation method for a three-stage starter generator according to claim 1, characterized in that, In step 3, the specific process for calculating the outer envelope of the exciter rotor d-axis current is as follows: In the formula, This is the outer envelope of the d-axis current of the exciter rotor. and These are the maximum and minimum values ​​of the exciter rotor d-axis current within a single square wave signal period, respectively.

4. The rotor position estimation method for a three-stage starter generator according to claim 3, characterized in that, The outer envelope The quantitative expression is: In the formula, This refers to the rotor position angle of the exciter. is the excitation current constant.

5. The rotor position estimation method for a three-stage starter generator according to claim 1, characterized in that, In step 4, the specific process of generating the discrete state sequence of the exciter is as follows: calculate the derivative function of the outer envelope, detect the zero-crossing point of the derivative function, initialize the discrete state of the exciter to 0, and increment by 1 each time a zero-crossing point is detected. When it increases to 11, it is automatically cleared to zero, thus obtaining 12 discrete states from 0 to 11, each discrete state corresponding to an electrical angle of π / 6.

6. The rotor position estimation method for a three-stage starter generator according to claim 1, characterized in that, In step 5, the specific process of generating the discrete state sequence of the main motor is as follows: the discrete state of the main motor is initialized to 0. Each time a change in the discrete state of the exciter is detected, the discrete state of the main motor is incremented by 1. When the increment reaches a preset maximum value... Automatically reset to zero, thus obtaining common There are discrete state values, among which The total number of discrete states of the main motor within one electrical cycle is determined based on the ratio of the number of pole pairs of the main motor and the exciter. The specific calculation formula is as follows: In the formula, and These are the number of pole pairs for the main motor and the exciter, respectively.

7. The rotor position estimation method for a three-stage starter generator according to claim 6, characterized in that, When the pole pair ratio When the number is not an integer, the total number of discrete states takes an integer value.

8. The rotor position estimation method for a three-stage starter generator according to claim 1, characterized in that, In step 6, the formula for calculating the discrete rotor position of the main motor is: In the formula, The current discrete state value of the main motor, with a value range of [value missing]. , The total number of discrete states of the main motor within one electrical cycle. The discrete rotor position of the main motor; the fixed electrical angle step size is... The formula for calculating the average speed of the main motor within the current discrete interval is: In the formula, The average speed of the main motor within the current discrete interval. The duration of the discrete state of the main motor.

9. The rotor position estimation method for a three-stage starter generator according to claim 8, characterized in that, Step 7 specifically includes: Step 7.1: Utilize the average rotational speed calculated from the previous discrete interval. Compensation is performed on the rotor position within the current discrete interval to obtain the continuous rotation angle of the main motor rotor: In the formula, This represents the time elapsed within the current discrete interval; Step 7.2, calculate the compensated rotor rotation angle of the main motor. relative to the initial position of the main motor By adding them together, we can obtain the real-time rotor position of the main motor: .

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