Instantaneous power observation method for dual three-phase permanent magnet synchronous motor system

Abstract

A method for observing instantaneous power in a dual three-phase permanent magnet synchronous motor system relates to the field of motor control technology. The present invention addresses the difficulty of using traditional instantaneous power theory to observe power when the motor experiences asymmetric operation or fault conditions. The present invention performs vector space decoupling transformation and rotating coordinate transformation on the phase currents of the dual three-phase permanent magnet synchronous motor system. The difference between the obtained feedback currents in the dq plane and the z1z2 plane and the command currents of their corresponding axes is input into a current regulator to obtain the command voltages in the dq plane and the z1z2 plane. Spatial delay compensation is then performed to obtain the compensated voltage value. Based on the compensated voltage value and the feedback currents in the two planes, the instantaneous active power, instantaneous reactive power, instantaneous apparent power, and the instantaneous reactive power flow between each two axes of the dual three-phase permanent magnet synchronous motor system are calculated using a quaternion instantaneous power calculation formula.

Description

Technical Field

[0001] The invention belongs to the technical field of motor control. Background Art

[0002] Instantaneous power theory, developed after the concept of instantaneous power was introduced into three-phase systems, is primarily used in PWM rectifiers, power regulation, and active power filters. In recent years, multiphase motors, such as dual three-phase permanent magnet synchronous motors, have garnered widespread attention from both academia and industry due to their suitability for low-voltage, high-power output applications, minimal output torque ripple, and strong fault tolerance. These motors are primarily used in AC motor drives (e.g., electric ship propulsion and submarines) and energy production (e.g., wind power generation and aerospace). Instantaneous power calculation not only enables motor drivers to accurately calculate the inverter's output power but also serves as an essential component in direct power control and predictive power control.

[0003] However, existing instantaneous power theory rarely discusses six-phase circuits, and the meaning of instantaneous reactive power is vague and unclear. Moreover, when the motor experiences asymmetric operation or fault conditions, traditional instantaneous power theory usually has difficulty in correctly explaining and describing them. Summary of the Invention

[0004] The present invention aims to solve the problem that when the motor is in asymmetric operation or fault condition, the traditional instantaneous power theory is difficult to perform power observation. Now, a method for observing the instantaneous power of a dual three-phase permanent magnet synchronous motor system is provided.

[0005] The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system includes:

[0006] Perform vector space decoupling transformation and rotating coordinate transformation on the phase current of the dual three-phase permanent magnet synchronous motor system to obtain feedback currents in the dq plane and z1z2 plane;

[0007] The difference between the feedback current of the dq plane and the z1z2 plane and the command current of the corresponding axis is input into the current regulator to obtain the command voltage of the dq plane and the z1z2 plane;

[0008] Performing spatial delay compensation on the command voltages of the dq plane and the z1z2 plane to obtain compensated voltage values;

[0009] Based on the compensated voltage value and the feedback current in the dq plane and the z1z2 plane, the instantaneous active power, instantaneous reactive power, instantaneous apparent power and instantaneous reactive power flow between each two axes of the dual three-phase permanent magnet synchronous motor system are calculated using the instantaneous power calculation formula of the quaternion.

[0010] Furthermore, the above-mentioned vector space decoupling transformation and rotating coordinate transformation are performed on the phase current of the dual three-phase permanent magnet synchronous motor system to obtain the feedback current in the dq plane and the z1z2 plane, including:

[0011] Collecting the current of each phase of the dual three-phase permanent magnet synchronous motor system and performing analog-to-digital conversion on the current of each phase;

[0012] Perform vector space decoupling transformation on the current after analog-to-digital conversion to obtain α-axis, β-axis, x-axis and y-axis current feedback values;

[0013] Perform rotation coordinate transformation on the α-axis current feedback value, β-axis current feedback value, x-axis current feedback value and y-axis current feedback value respectively to obtain the d-axis current feedback value i d , q-axis current feedback value i q , z1 axis current feedback value i z1 and z2 axis current feedback value i z2 .

[0014] Furthermore, the transformation matrix T used in the above vector space decoupling transformation is VSD for:

[0015]

[0016] Furthermore, the transformation matrix T used in the above rotation coordinate transformation is Park (θ e )for:

[0017]

[0018] Among them, θ e is the angle between the d-axis and the A-phase axis.

[0019] Furthermore, the expression of the above spatial delay compensation is as follows:

[0020]

[0021] Among them, u dc (k-1),u qc (k-1),u z1c (k-1) and u z2c (k-1) are the voltages after compensation for the k-1th beat of the d-axis, q-axis, z1-axis and z2-axis, respectively. d (k-1),u q (k-1),u z1 (k-1) and u z2 (k-1) are the k-1th beat command voltages of the d-axis, q-axis, z1-axis and z2-axis, respectively. d is the compensation time, ω e is the electrical angular velocity.

[0022] Furthermore, the instantaneous active power P of the above dual three-phase permanent magnet synchronous motor system is expressed as follows:

[0023] P=3(u dc i d +u qc i q +u z1c i z1 +u z2c i z2 ),

[0024] Among them, u dc 、u qc 、u z1c and u z2c are the compensated voltages of d, q, z1 and z2 axes respectively, i d 、i q 、i z1 and i z2 are the feedback currents of the d, q, z1 and z2 axes respectively.

[0025] Furthermore, the instantaneous reactive power flow between each two axes of the dual three-phase permanent magnet synchronous motor system is expressed as follows:

[0026]

[0027] Among them, Q dq is the instantaneous reactive power flow between the d-axis and the q-axis, Q z1z2 is the instantaneous reactive power flow between the z1 axis and the z2 axis, Q dz1 is the instantaneous reactive power flow between the d axis and the z1 axis, Q qz2 is the instantaneous reactive power flow between the q axis and the z2 axis, Q dz2 is the instantaneous reactive power flow between the d-axis and the z2-axis, Q qz1 is the instantaneous reactive power flow between the q axis and the z1 axis.

[0028] Furthermore, the instantaneous reactive power Q of the above dual three-phase permanent magnet synchronous motor system is expressed as follows:

[0029] Q=Q dq +Q z1z2 +Q dz1 +Q qz2 +Q dz2 +Q qz1 .

[0030] Furthermore, the instantaneous apparent power S of the above dual three-phase permanent magnet synchronous motor system is expressed as follows:

[0031]

[0032] in, is the instantaneous complex power,

[0033]

[0034] and They are the imaginary units of the three imaginary parts in quaternion operations.

[0035] The instantaneous power observation method of the dual three-phase permanent magnet synchronous motor system described in the present invention has the following beneficial effects:

[0036] The present invention is a method for calculating instantaneous power in a vector space decoupled VSD framework based on quaternions. This method introduces the concept and operation of four-dimensional complex numbers into instantaneous power calculation, and uses the real and imaginary parts of the product of the conjugate of complex voltage and complex current to calculate instantaneous power. The method is concise and clear and can be used for asymmetric and fault conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of the instantaneous power observation method for a dual three-phase permanent magnet synchronous motor system;

[0038] Figure 2 This is the principle block diagram of the instantaneous power calculation of dual three-phase permanent magnet synchronous motor;

[0039] Figure 3 It is the instantaneous active power curve of dual three-phase permanent magnet synchronous motor;

[0040] Figure 4 It is the instantaneous reactive power curve of dual three-phase permanent magnet synchronous motor;

[0041] Figure 5 Schematic diagram of quaternion space. DETAILED DESCRIPTION

[0042] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other in the absence of conflict.

[0043] Specific implementation method 1: refer to Figure 1 Specifically describing this embodiment, the instantaneous power observation method of the dual three-phase permanent magnet synchronous motor system described in this embodiment includes:

[0044] Step 1: The motor phase current signal is collected through the current sampling module, and the sampling signal is sent to the ADC (analog-to-digital conversion) module to convert the six-phase current signal into a digital signal. After vector space decoupling transformation and rotation coordinate transformation, the feedback current i in the dq plane and z1z2 plane under the k-th beat vector space decoupling VSD framework is obtained. d (k), i q (k), i z1 (k), i z2 (k) The vector space decoupling transformation and the rotation coordinate transformation establish the connection between the natural coordinate system and the dq-z1z2 plane in the vector space decoupling VSD framework, which is expressed as:

[0045] [f α f β f x f y f o1 f o2 ]=T VSD [f A f B f C f D f E f F ] T

[0046] [f d f q ] T =T Park (θ e )[f α f β ] T ,

[0047] [f z1 f z2 ] T =T Park (-θ e )[f x f y ] T

[0048] Where, T VSD and T Park (θ e ) are the VSD coordinate transformation matrix and the Park coordinate transformation matrix respectively, and there are:

[0049]

[0050] θ e is the angle between the d-axis and the A-phase axis, and f represents voltage, current or magnetic flux.

[0051] will id (k), i q (k), i z1 (k), i z2 (k) and command current The error between them is input to the current regulator to obtain the command voltage u of the dq plane and z1z2 plane under the k-th beat vector space decoupling VSD framework d (k),u q (k),u z1 (k),u z2 (k) These command voltages are input to the SVPWM module to output PWM to control the motor.

[0052] Step 2: When using a current regulator, time delay will cause spatial rotation to produce angle errors, which will cause errors in the phase and amplitude of the voltage output. Therefore, it is necessary to perform spatial delay compensation on the dq plane and z1z2 plane command voltages respectively. Specifically, the command voltage u of the k-1th beat is d (k-1),u q (k-1),u z1 (k-1),u z2 (k-1) performs spatial delay compensation to obtain the voltage u after the k-1th beat compensation dc (k-1),u qc (k-1),u z1c (k-1),u z2c (k-1).

[0053] The voltage space delay compensation expression is:

[0054]

[0055] Where, T d is the compensation time, ω e is the electrical angular velocity.

[0056] Step 3: Compensate the voltage u of the d, q, z1, and z2 axes dc 、u qc 、u z1c 、u z2c And the feedback current i of d, q, z1, and z2 axes under the vector space decoupling VSD framework d 、i q 、i z1 、i z2 Substituting them into the instantaneous power calculation formula based on quaternion, the instantaneous active power P, instantaneous reactive power Q, instantaneous apparent power S of the dual three-phase permanent magnet synchronous motor system and the instantaneous reactive power flow between each two axes can be obtained.

[0057] Specifically, such as Figure 5As shown, quaternion It is represented by a real part and three imaginary parts, where the real part represents the angle of rotation and the imaginary part represents the axis of rotation:

[0058]

[0059] Among them, a, b, c, d are real numbers, Is an imaginary unit.

[0060] The basic operation rules of quaternions are as follows:

[0061]

[0062]

[0063] Quaternions The conjugate of

[0064] Defining voltage based on the vector space decoupling VSD framework and current They are:

[0065]

[0066] The instantaneous power in complex form (abbreviated as instantaneous complex power) is:

[0067]

[0068] Then we have:

[0069]

[0070] The real part and imaginary part of the instantaneous complex power are the instantaneous real power and instantaneous imaginary power of the system, respectively represented by p and q, then:

[0071] p=3(u dc i d +u qc i q +u z1c i z1 +u z2c i z2 ),

[0072]

[0073] Q dq , Q z1z2 , Q dz1 , Q qz2 , Q dz2 , Q qz1are the instantaneous reactive power flows between the d-axis and the q-axis, the z1-axis and the z2-axis, the d-axis and the z1-axis, the q-axis and the z2-axis, the d-axis and the z2-axis, and the q-axis and the z1-axis, respectively, and:

[0074]

[0075] The instantaneous active power P and instantaneous reactive power Q of the system are defined as:

[0076] P=3(u dc i d +u qc i q +u z1c i z1 +u z2c i z2 ),

[0077] Q=Q dq +Q z1z2 +Q dz1 +Q qz2 +Q dz2 +Q qz1 ,

[0078] The instantaneous apparent power S is the instantaneous complex power The module is:

[0079]

[0080] Specific implementation method 2: This implementation method is described by taking a vehicle dual three-phase permanent magnet synchronous motor drive system as an example.

[0081] The system is simulated using Matlab, with a control period of 40μs, a compensation time of 50μs, and a bus voltage of 270V. Asymmetric operating conditions are set: The speed command value is obtained through the PI regulator, that is, it starts at a speed of 1000r / min, and after stable operation, it increases to the rated speed of 3000r / min at 10ms; i z1 =-5A,i z2 =10A.

[0082] Step 1: The motor phase current signal is collected through the current sampling module, and the sampling signal is sent to the ADC module to convert the six-phase current signal into a digital signal. After the vector space decoupling transformation and the rotation coordinate transformation, the current under the k-th vector space decoupling VSD framework is obtained. The error between the current under the vector space decoupling (VSD) framework calculated for the k-th beat and the command value is input into the current regulator to obtain the voltage under the k-th vector space decoupling VSD framework. These voltages are input into the SVPWM module to output the PWM wave to control the motor. The control block diagram is shown as follows: Figure 2shown.

[0083] Step 2: Perform spatial delay compensation on the voltage of the k-1th beat.

[0084] Step 3: Substituting the voltage vector and current vector in the vector space decoupling VSD framework into the instantaneous power calculation formula based on quaternions can obtain the system's instantaneous active power P, instantaneous reactive power Q, instantaneous apparent power S, and the flow direction of instantaneous reactive power between each two axes.

[0085] In order to evaluate the accuracy of instantaneous power observation, Matlab simulation results are shown as follows: Figure 3 、 Figure 4 As shown in the figure, the control period is 40μs. The motor is stationary with load torque T L =2N·mStart to the speed of 1000r / min, after stable operation, increase the speed to the rated speed of 3000r / min at 10ms, and then suddenly add a load torque of T at 20ms. L =4N·m, then change the load torque to T in 10ms L =-6N·m.

[0086] from Figure 3 It can be seen that the calculated instantaneous active power is basically consistent with the motor power and mechanical power. Figure 4 The instantaneous reactive power in also changes with the experimental conditions, which verifies the validity of the calculation.

[0087] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A method for observing the instantaneous power of a dual three-phase permanent magnet synchronous motor system, characterized in that: include: Perform vector space decoupling transformation and rotating coordinate transformation on the phase current of the dual three-phase permanent magnet synchronous motor system to obtain feedback currents in the dq plane and z1z2 plane; The difference between the feedback current of the dq plane and the z1z2 plane and the command current of the corresponding axis is input into the current regulator to obtain the command voltage of the dq plane and the z1z2 plane; Performing spatial delay compensation on the command voltages of the dq plane and the z1z2 plane to obtain compensated voltage values; Based on the compensated voltage value and the feedback current in the dq plane and the z1z2 plane, the instantaneous active power, instantaneous reactive power, instantaneous apparent power and instantaneous reactive power flow between each two axes of the dual three-phase permanent magnet synchronous motor system are calculated using the instantaneous power calculation formula of the quaternion; The expression of the spatial delay compensation is as follows: Among them, u dc (k-1),u qc (k-1),u z1c (k-1) and u z2c (k-1) are the voltages after compensation for the k-1th beat of the d-axis, q-axis, z1-axis and z2-axis, respectively. d (k-1),u q (k-1),u z1 (k-1) and u z2 (k-1) are the k-1th beat command voltages of the d-axis, q-axis, z1-axis and z2-axis, respectively. d is the compensation time, ω e is the electrical angular velocity; The instantaneous apparent power S of the dual three-phase permanent magnet synchronous motor system is expressed as follows: in, is the instantaneous complex power, and are the imaginary units of the three imaginary parts in quaternion operations, u dc 、u qc 、u z1c and u z2c are the compensated voltages of d, q, z1 and z2 axes respectively, i d 、i q 、i z1 and i z2 are the feedback currents of the d, q, z1 and z2 axes respectively.

2. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 1, characterized in that: The process of performing vector space decoupling transformation and rotating coordinate transformation on the phase current of the dual three-phase permanent magnet synchronous motor system to obtain feedback currents in the dq plane and the z1z2 plane includes: Collecting the current of each phase of the dual three-phase permanent magnet synchronous motor system and performing analog-to-digital conversion on the current of each phase; Perform vector space decoupling transformation on the current after analog-to-digital conversion to obtain α-axis, β-axis, x-axis and y-axis current feedback values; The α-axis current feedback value, β-axis current feedback value, x-axis current feedback value and y-axis current feedback value are respectively subjected to rotation coordinate transformation to obtain the d-axis current feedback value i d , q-axis current feedback value i q , z1 axis current feedback value i z1 and z2 axis current feedback value i z2 .

3. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 2, characterized in that: The transformation matrix T used in the vector space decoupling transformation is VSD for:

4. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 3, characterized in that: The transformation matrix T used in the rotation coordinate transformation is Park (θ e )for: Among them, θ e is the angle between the d-axis and the A-phase axis.

5. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 1, characterized in that: The instantaneous active power P of the dual three-phase permanent magnet synchronous motor system is expressed as follows: P=3(in dc and d +in qc and q +in z1c and z1 +in z2c and z2 )。 6. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 5, characterized in that: The instantaneous reactive power flow between each two axes of the dual three-phase permanent magnet synchronous motor system is expressed as follows: Among them, Q dq is the instantaneous reactive power flow between the d-axis and the q-axis, Q z1z2 is the instantaneous reactive power flow between the z1 axis and the z2 axis, Q dz1 is the instantaneous reactive power flow between the d axis and the z1 axis, Q qz2 is the instantaneous reactive power flow between the q axis and the z2 axis, Q dz2 is the instantaneous reactive power flow between the d-axis and the z2-axis, Q qz1 is the instantaneous reactive power flow between the q axis and the z1 axis.

7. The instantaneous power observation method of a dual three-phase permanent magnet synchronous motor system according to claim 6, characterized in that: The instantaneous reactive power Q of the dual three-phase permanent magnet synchronous motor system is expressed as follows: Q=Q dq +Q z1z2 +Q dz1 +Q qz2 +Q dz2 +Q qz1 。

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