Motor electromagnetic thrust control method in train operation process

Abstract

The invention relates to a motor electromagnetic thrust control method in a train operation process, and belongs to the technical field of suppression of motor vibration through vector control in motor control. According to the method, multiple control moments are divided by setting interval time, when a train runs to the nth moment, a target quadrature-axis current is obtained according to the real-time speed, the target direct-axis current is set to be 0, then the target direct-axis flux linkage, the target quadrature-axis flux linkage, the target direct-axis voltage and the target quadrature-axis voltage of a motor are obtained, and the target quadrature-axis flux linkage and the target direct-axis voltage are calculated. Converting the target direct-axis and quadrature-axis voltages into target alpha-axis and beta-axis voltages, and constructing a target voltage vector to solve a target angle; according to the method, six virtual voltage vectors are constructed on an original space vector pulse width modulation sector diagram, three voltage vectors with minimum errors are screened out in a sector corresponding to an angle range in which a target angle falls according to a screening value, and a switching signal is generated to control the electromagnetic thrust of the motor. According to the method, the correct electromagnetic thrust of the motor can be quickly regulated and controlled through the set voltage vector selection strategy.

Description

Technical Field

[0001] The present invention relates to a method for controlling electromagnetic thrust of a motor during train operation, and belongs to the technical field of suppressing motor vibration through vector control in motor control (H02P21 / 05). Background Art

[0002] Currently, flux-switching permanent magnet linear motors (PMLMs) are widely used in rail transit due to their significant advantages of high efficiency, low cost, and high electromagnetic thrust density. To ensure smooth train operation, the motor's electromagnetic thrust must be accurately controlled in real time during operation. Specifically, this electromagnetic thrust control involves selecting the three voltage vectors with the smallest error from the target voltage vector. Space vector pulse width modulation (SVM) is then used to generate a three-phase inverter switching signal, which then drives the three-phase inverter to adjust the motor's output electromagnetic thrust.

[0003] Conventional methods for controlling electromagnetic thrust in electric motors rely on constructing a value function to select the three voltage vectors with the smallest error. However, due to the different dimensions of electromagnetic thrust and magnetic flux, weight coefficients must be introduced when constructing this function. This often results in improper allocation of weight coefficients, leading to improper electromagnetic thrust control and subsequent electromagnetic thrust fluctuations and speed pulsation, impacting the smoothness of train operation. Furthermore, the value function-based screening process requires traversing all candidate voltage vectors, which is computationally complex and time-consuming. This makes it difficult to quickly adjust electromagnetic thrust, especially during critical acceleration and deceleration moments, further impacting train smoothness. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: how to quickly and correctly control the electromagnetic thrust of the motor when the train is running.

[0005] The present invention proposes a technical solution to solve the above technical problems: a method for controlling the electromagnetic thrust of a motor during train operation, comprising the following steps: Step 1: Set the interval time T for controlling the electromagnetic thrust of the motor during the train operation, take the moment when the electromagnetic thrust of the motor is controlled for the first time as the first moment t1, take the moment when the electromagnetic thrust of the motor is controlled for the second time after the interval time T as the second moment t2, and so on to the nth moment tn; Step 2: When the train runs to the nth time tn, the real-time speed v of the motor is collected, and the difference between the real-time speed v and the target speed of the motor is input into the proportional integral controller to obtain the target quadrature axis current of the motor When the train needs to accelerate or run at a constant speed, the target speed is the rated speed of the motor. When the train needs to decelerate, the target speed is 0. Set the target direct-axis current of the motor Set to 0; Step 3: Calculate the target direct-axis flux of the motor at the nth time tn according to formula (1): and target cross-axis flux

[0006] (1); In formula (1), is the real-time direct-axis inductance of the motor; is the real-time quadrature-axis inductance of the motor; is the permanent magnet flux linkage of the motor; Step 4: Calculate the target direct-axis voltage of the motor at time n tn according to formula (2): and target quadrature-axis voltage

[0007] (2); In formula (2), R is the real-time phase resistance of the motor; is the real-time speed of the motor; is the real-time direct-axis flux of the motor; is the real-time quadrature-axis flux of the motor; Step 5: Use the inverse Park transform formula to convert the target direct axis voltage and target quadrature-axis voltage Converted into the target α-axis voltage in the motor two-phase stationary coordinate system and target β-axis voltage ; The origin of the two-phase stationary coordinate system of the motor is located at the center of the motor, the α-axis points to the center of the A-phase coil of the motor, and the β-axis is orthogonal to the α-axis; Step 6: Set the α-axis voltage and target β-axis voltage As two components, the target voltage vector is obtained by synthesis; The target angle of the target voltage vector is calculated according to formula (3): (3); Step 7: According to formula (4), construct 6 virtual voltage vectors on the space vector pulse width modulation sector diagram, denoted as U7, U8, U9, U 10 、U 11 、U 12 (4); In formula (4), is the kth non-zero voltage vector of the three-phase inverter; The space vector pulse width modulation sector diagram is that the six non-zero voltage vectors U1 to U6 of the three-phase inverter all start from the origin of the motor two-phase stationary coordinate system and are radiated at 60° angular intervals. The angular directions of the non-zero voltage vectors U1 to U6 are 0°, 60°, 120°, 180°, 240°, and 300°, respectively. The motor two-phase stationary coordinate system plane is divided into six 60° sectors, which are: The first sector is located between U1 and U2, with an angle range of 0°~60° and sector number 1; The second sector is located between U2 and U3, with an angle range of 60°~120° and sector number 2; The third sector is located between U3 and U4, with an angle range of 120°~180° and sector number 3; The fourth sector is located between U4 and U5, with an angle range of 180°~240° and sector number 4; The fifth sector is located between U5 and U6, with an angle range of 240°~300° and sector number 5; The sixth sector is located between U6 and U1, with an angle range of 300°~360° and sector number 6; Step 8: Set the Target Angle The sector corresponding to the angle range falls into is taken as the candidate sector, and the screening value P of the non-zero voltage vector is calculated according to the following formula (5): (5); In formula (5), is the sector number of the candidate sector; If P<0, a non-zero voltage vector, a virtual voltage vector, and a zero voltage vector with the largest direction angle are selected in the candidate sector as the first candidate voltage vector; the zero voltage vector is a vector located at the origin of the two-phase stationary coordinate system of the motor and having an amplitude of 0; If P>0, select the non-zero voltage vector, the virtual voltage vector and the zero voltage vector with the smallest direction angle in the candidate sector as the second candidate voltage vector; Step 9: Use space vector pulse width modulation to convert the selected first candidate voltage vector or second candidate voltage vector into a switching signal of the three-phase inverter and input it into the three-phase inverter, so that the three-phase inverter outputs a three-phase voltage and applies it to the motor to control the electromagnetic thrust of the motor at the nth time tn.

[0008] Furthermore, the interval time T in step 1 is set to 100 us.

[0009] Furthermore, in step 2, the real-time speed v of the motor is collected through a grating ruler.

[0010] Furthermore, the inverse Park transform formula of step 5 is shown in the following formula (6): (6); In formula (6), θ is the real-time electrical angle of the motor.

[0011] The beneficial effects of the present invention are as follows: since six virtual voltage vectors are constructed on the existing space vector pulse width modulation sector diagram, the three voltage vectors with the smallest error with the target voltage vector can be directly selected through the set voltage vector selection method. Compared with the traditional method of traversing all voltage vectors and repeatedly screening through the value function, the complexity of motor control is significantly reduced. More importantly, the motor can be immediately controlled to output the correct electromagnetic thrust according to the target operating state at the next moment. With such high responsiveness, the smoothness of train operation is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The following further illustrates a method for controlling electromagnetic thrust of a motor during train operation according to the present invention with reference to the accompanying drawings.

[0013] Figure 1 This is a space vector pulse width modulation sector diagram of the motor electromagnetic thrust control method during train operation in an embodiment.

[0014] Figure 2 It is a virtual voltage vector construction diagram of the motor electromagnetic thrust control method during train operation in the embodiment. DETAILED DESCRIPTION Example

[0015] The method for controlling the electromagnetic thrust of a motor during train operation in this embodiment includes the following steps: Step 1: Set the interval time T=100us for controlling the electromagnetic thrust of the motor during the operation of the train, and take the moment when the electromagnetic thrust of the motor is controlled for the first time as the first moment t1, and the moment when the electromagnetic thrust of the motor is controlled for the second time after the interval T as the second moment t2, and so on to the nth moment tn.

[0016] Step 2: When the train runs to the nth time tn, the real-time speed v of the motor is collected, and the difference between the real-time speed v and the target speed of the motor is input into the proportional integral controller to obtain the target quadrature axis current of the motor When the train needs to accelerate or run at a constant speed, the target speed is the rated speed of the motor. When the train needs to decelerate, the target speed is 0. Set the target direct-axis current of the motor Set to 0.

[0017] The grating ruler is a high-precision displacement sensor that is widely used in the field of speed control to collect parameters such as motor speed, three-phase current, and electrical angle.

[0018] The proportional-integral controller (PI controller) is a linear feedback controller widely used in the field of motor speed control. It aims to perform proportional-integral calculations on the difference between the real-time speed and the target speed of the motor and output the target quadrature-axis current of the motor.

[0019] Step 3: Calculate the target direct-axis flux of the motor at the nth time tn according to formula (1): and target cross-axis flux

[0020] (1); In formula (1), is the measured real-time direct-axis inductance of the motor; is the measured real-time quadrature-axis inductance of the motor; is the permanent magnet flux linkage of the motor.

[0021] Step 4: Calculate the target direct-axis voltage of the motor at time n tn according to formula (2): and target quadrature-axis voltage

[0022] (2); In formula (2), R is the measured real-time phase resistance of the motor; is the real-time speed of the motor. According to the motor speed formula Ask for, is the stator pole pitch of the motor, v is the real-time speed of the motor; is the real-time direct-axis flux of the motor; is the real-time quadrature-axis flux of the motor; The real-time electrical angle θ and real-time three-phase current of the motor collected by the grating ruler 、 and , which can be converted into the real-time direct-axis current of the motor through the existing Park transformation formula and real-time quadrature-axis current , as follows:

[0023] The real-time direct-axis flux of the motor is The motor direct axis flux formula can be used = L d i d +φ f Calculate the real-time quadrature-axis flux of the motor The motor quadrature axis flux formula can be used = L q i q Find out.

[0024] Step 5: Use the inverse Park transform formula of the following formula (6) to convert the target direct axis voltage and target quadrature-axis voltage Converted into the target α-axis voltage in the motor two-phase stationary coordinate system and target β-axis voltage ; (6); In formula (6), θ is the measured real-time electrical angle of the motor; The origin of the motor's two-phase stationary coordinate system is located at the center of the motor, the α-axis points to the center of the motor's A-phase coil, and the β-axis is orthogonal to the α-axis.

[0025] Step 6: Set the α-axis voltage and target β-axis voltage As two components, the target voltage vector is obtained by synthesis; The target angle of the target voltage vector is calculated according to formula (3): (3).

[0026] Step 7: According to formula (4), construct 6 virtual voltage vectors on the space vector pulse width modulation sector diagram, denoted as U7, U8, U9, U 10 、U 11 、U 12 (4); In formula (4), is the kth non-zero voltage vector of the three-phase inverter; like Figure 1 As shown in the figure, the space vector pulse width modulation sector diagram is that the six non-zero voltage vectors U1~U6 of the three-phase inverter all start from the origin of the two-phase stationary coordinate system of the motor and are radiated at 60° angular intervals. The angular directions of the non-zero voltage vectors U1~U6 are 0°, 60°, 120°, 180°, 240°, and 300°, respectively. The plane of the two-phase stationary coordinate system of the motor is divided into six 60° sectors, which are: The first sector is located between U1 and U2, with an angle range of 0°~60° and sector number 1; The second sector is located between U2 and U3, with an angle range of 60°~120° and sector number 2; The third sector is located between U3 and U4, with an angle range of 120°~180° and sector number 3; The fourth sector is located between U4 and U5, with an angle range of 180°~240° and sector number 4; The fifth sector is located between U5 and U6, with an angle range of 240°~300° and sector number 5; The sixth sector is located between U6 and U1, with an angle range of 300°~360° and sector number 6; The six virtual voltage vectors constructed in this embodiment are as follows: Figure 2 shown.

[0027] Step 8: Set the Target Angle The sector corresponding to the angle range falls into is taken as the candidate sector, and the screening value P of the non-zero voltage vector is calculated according to the following formula (5): (5); In formula (5), is the sector number of the candidate sector; If P < 0, the non-zero voltage vector, virtual voltage vector, and zero voltage vector with the largest direction angle in the candidate sector are selected as the first candidate voltage vector; the zero voltage vector is a vector located at the origin of the two-phase stationary coordinate system of the motor and has an amplitude of 0; If P>0, the non-zero voltage vector, the virtual voltage vector and the zero voltage vector with the smallest direction angle in the candidate sector are selected as the second candidate voltage vector; In this embodiment, at the third moment t3 =45°, and the angle range is 0~60°, so the first sector with sector number 1 is selected as the candidate sector. Since P calculated according to formula (5) is less than 0, U2, U7 and the zero voltage vector are selected as the first candidate voltage vector at the third time t3 in the candidate sector.

[0028] Step 9: Use space vector pulse width modulation to convert the selected first candidate voltage vector or second candidate voltage vector into a switching signal of the three-phase inverter and input it into the three-phase inverter, so that the three-phase inverter outputs a three-phase voltage and applies it to the motor to control the electromagnetic thrust of the motor at the nth time tn.

[0029] Space vector pulse width modulation (SVM) is a high-performance modulation technology for three-phase inverters, primarily used in the field of electromagnetic thrust control for motors. It is currently available. Its core principle is to precisely regulate the three-phase output voltage of the three-phase inverter by converting the voltage vector into switching signals for the three-phase inverter, ultimately controlling the electromagnetic thrust of the motor.

[0030] In this embodiment, at the third moment t3, the first candidate voltage vector selected in step 8 is converted into a switching signal of the three-phase inverter according to space vector pulse width modulation and input into the three-phase inverter, so that the three-phase inverter outputs a three-phase voltage and applies it to the motor to control the electromagnetic thrust of the motor at the third moment t3.

[0031] The above description is only a preferred embodiment of the present invention, but the present invention is not limited thereto. All equivalent replacements or equivalent changes of the concepts and technical solutions according to the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling electromagnetic thrust of a motor during train operation, characterized in that The steps include: Step 1: Set the interval time T for controlling the electromagnetic thrust of the motor during the train operation, take the moment when the electromagnetic thrust of the motor is controlled for the first time as the first moment t1, take the moment when the electromagnetic thrust of the motor is controlled for the second time after the interval time T as the second moment t2, and so on to the nth moment tn; Step 2: When the train runs to the nth time tn, the real-time speed v of the motor is collected, and the difference between the real-time speed v and the target speed of the motor is input into the proportional integral controller to obtain the target quadrature axis current of the motor When the train needs to accelerate or run at a constant speed, the target speed is the rated speed of the motor. When the train needs to decelerate, the target speed is 0. Set the target direct-axis current of the motor Set to 0; Step 3: Calculate the target direct-axis flux of the motor at the nth time tn according to formula (1): and target cross-axis flux （1）； In formula (1), is the real-time direct-axis inductance of the motor; is the real-time quadrature-axis inductance of the motor; is the permanent magnet flux linkage of the motor; Step 4: Calculate the target direct-axis voltage of the motor at time n tn according to formula (2): and target quadrature-axis voltage （2）； In formula (2), R is the real-time phase resistance of the motor; is the real-time speed of the motor; is the real-time direct-axis flux of the motor; is the real-time quadrature-axis flux of the motor; Step 5: Use the inverse Park transform formula to convert the target direct axis voltage and target quadrature-axis voltage Converted into the target α-axis voltage in the motor two-phase stationary coordinate system and target β-axis voltage ; The origin of the two-phase stationary coordinate system of the motor is located at the center of the motor, the α-axis points to the center of the A-phase coil of the motor, and the β-axis is orthogonal to the α-axis; Step 6: Set the α-axis voltage and target β-axis voltage As two components, the target voltage vector is obtained by synthesis; The target angle of the target voltage vector is calculated according to formula (3): （3）； Step 7: According to formula (4), construct 6 virtual voltage vectors on the space vector pulse width modulation sector diagram, denoted as U7, U8, U9, U 10 、U 11 、U 12 （4）； In formula (4), is the kth non-zero voltage vector of the three-phase inverter; The space vector pulse width modulation sector diagram is that the six non-zero voltage vectors U1 to U6 of the three-phase inverter all start from the origin of the motor's two-phase stationary coordinate system and are radially distributed at 60° angular intervals. The angular directions of the non-zero voltage vectors U1 to U6 are 0°, 60°, 120°, 180°, 240°, and 300°, respectively. The motor's two-phase stationary coordinate system plane is divided into six 60° sectors, which are: The first sector is located between U1 and U2, with an angle range of 0°~60° and sector number 1; The second sector is located between U2 and U3, with an angle range of 60°~120° and sector number 2; The third sector is located between U3 and U4, with an angle range of 120°~180° and sector number 3; The fourth sector is located between U4 and U5, with an angle range of 180°~240° and sector number 4; The fifth sector is located between U5 and U6, with an angle range of 240°~300° and sector number 5; The sixth sector is located between U6 and U1, with an angle range of 300°~360° and sector number 6; Step 8: Set the Target Angle The sector corresponding to the angle range falls into is taken as the candidate sector, and the screening value P of the non-zero voltage vector is calculated according to the following formula (5): （5）； In formula (5), is the sector number of the candidate sector; If P<0, a non-zero voltage vector, a virtual voltage vector, and a zero voltage vector with the largest direction angle are selected in the candidate sector as the first candidate voltage vector; the zero voltage vector is a vector located at the origin of the two-phase stationary coordinate system of the motor and having an amplitude of 0; If P>0, select the non-zero voltage vector, the virtual voltage vector and the zero voltage vector with the smallest direction angle in the candidate sector as the second candidate voltage vector; Step 9: Use space vector pulse width modulation to convert the selected first candidate voltage vector or second candidate voltage vector into a switching signal of the three-phase inverter and input it into the three-phase inverter, so that the three-phase inverter outputs a three-phase voltage and applies it to the motor to control the electromagnetic thrust of the motor at the nth time tn.

2. The method for controlling electromagnetic thrust of a motor during train operation according to claim 1, characterized in that: The interval time T in step 1 is set to 100 us.

3. The method for controlling electromagnetic thrust of a motor during train operation according to claim 1, characterized in that: The step 2 collects the real-time speed v of the motor through the grating ruler.

4. The method for controlling electromagnetic thrust of a motor during train operation according to claim 1, characterized in that: The inverse Park transform formula of step 5 is shown in the following formula (6): （6）； In formula (6), θ is the real-time electrical angle of the motor.

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