A method for angle identification and correction of permanent magnet synchronous motor

Abstract

The present invention discloses a method for angle identification and correction of a permanent magnet synchronous motor. The method uses a current sensor to sample the motor's current information, performs coordinate transformation on the sampled current to obtain the current in a stationary two-phase coordinate system and the current in a rotating two-phase coordinate system. A position identification algorithm is used to obtain the motor's initial position identification value. The AC and DC axis currents are set, and an identification angle deviation is calculated based on the DC component of the AC and DC axis voltages. This is combined with speed information and stored in a working condition table. Finally, the working condition table is consulted to obtain the identification angle deviation at the current speed. The motor angle is updated and applied to the permanent magnet synchronous motor's vector control system. The angle identification and correction method of the present invention can improve the power factor and load capacity of a permanent magnet synchronous motor.

Description

Technical Field

[0001] The present invention belongs to the field of electrical signal detection, and in particular relates to a method for identifying and correcting the angle of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motor systems that use position sensorless control technology do not require mechanical position sensors such as traditional encoders, and are increasingly used in high-vibration, high-pollution areas such as textiles, steelmaking, and oil fields.

[0003] Based on the relationship between the motor rotor position and electromagnetic state variables such as back EMF and inductance, numerous researchers have proposed position identification algorithms based on back EMF and flux linkage, which can be applied to medium- and high-speed operating conditions, and position identification algorithms based on high-frequency signal injection, which can be applied to low-speed and stationary operating conditions. However, existing position identification methods have the following shortcomings: 1) Regardless of the identification method used, position identification will inevitably deviate due to factors such as motor parameter accuracy and observer characteristics; 2) While angle deviation optimization can achieve MTPA maximum torque-to-current ratio control, it still cannot accurately determine the position. Summary of the Invention

[0004] The purpose of the invention is to address the above problems and propose a simple, reliable and easy-to-implement method for angle identification and correction of permanent magnet synchronous motors.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a method for angle identification and correction of a permanent magnet synchronous motor, which is used for a three-phase or multi-phase permanent magnet synchronous motor powered by a voltage-type inverter, and is based on a control system consisting of a current detection and calculation link, a rotor position identification link, a position deviation calculation link, and a position compensation and action link, and the steps are as follows:

[0006] Step 1: Get the permanent magnet synchronous motor current i by sampling the current sensor na 、i nb and i nc , the current detection calculation link samples the current i na 、i nb and i nc Coordinate transformation gives the current i in the stationary coordinate system αβ0 and the current i in the rotating coordinate system dq0 ;

[0007] Step 2: The rotor position identification link obtains the initial position identification value of the permanent magnet synchronous motor rotor according to the position identification algorithm.

[0008] Step 3: Set the current given by the quadrature and direct axes i in the position deviation calculation step. dq_ref=0, calculate the identification angle deviation Δθ based on the DC component of the AC and DC axis voltages, and store it in the operating condition table in combination with the speed information;

[0009] Step 4: Position compensation and action link check the working condition table to obtain the identification angle deviation Δθ at the current speed and update the motor angle Act on the permanent magnet synchronous motor vector control system.

[0010] The method for angle identification and correction of a permanent magnet synchronous motor, step 1 specifically includes:

[0011] Step 1.1, the current i in the stationary three-phase coordinate system na 、i nb and i nc The current i in the stationary coordinate system is obtained by 3s / 2s coordinate transformation αβ0 , the calculation formula is:

[0012]

[0013] Step 1.2, transform the current i in the stationary three-phase coordinate system into na 、i nb and i nc Transformed into the current i in the rotating two-phase coordinate system q , the position transformation uses the identification angle θ, and the calculation formula is:

[0014]

[0015] The above-mentioned method for angle identification and correction of permanent magnet synchronous motor, wherein the rotor initial position identification value in step 2 is It is obtained through a position identification algorithm based on back electromotive force, magnetic flux or a position identification algorithm based on high frequency signal injection.

[0016] The method for angle identification and correction of a permanent magnet synchronous motor, step 3 specifically includes:

[0017] Step 3.1, set the DC axis current reference i dq_ref =0;

[0018] Step 3.2, the DC-axis voltage u dq Filter and extract the DC component u dq_dc ;

[0019] Step 3.3, according to the DC component of the AC and DC axis voltage u d_dc and u q_dc , calculate the back electromotive force amplitude at the current speed

[0020] Step 3.4, j converts the DC component of the direct axis voltage u d_dcNormalized to

[0021] Step 3.5, use PI regulator or variable step size to calculate the angle deviation Δθ=f(u pu );

[0022] Step 3.6, record and store the current speed and angle compensation value;

[0023] Step 3.7, determine whether the position identification deviation calculation at all speeds is completed. If completed, exit the position deviation calculation; otherwise, change the speed closed-loop setting and return to step 3.1.

[0024] The method for identifying and correcting the angle of a permanent magnet synchronous motor is described, wherein step 4 is to obtain the normalized value u pu Perform PI regulator operation to obtain position deviation Δθ, and set the proportional and integral parameters of PI regulator to be k p and k i , the function is Δθ=k p +k i ∫u pu dt, can be calculated using a variable step size, changing the regulator proportional and integral parameters k according to the normalized direct axis voltage p =f1(u pu ) and k i =f2(u pu ), improving the dynamic performance of the system.

[0025] The beneficial effects of the present invention are as follows: the present invention applies position identification correction to the mechanical position sensorless control of a permanent magnet synchronous motor, and can suppress the position deviation caused by the position sensorless control method; the method is simple and easy to implement, can quickly realize the correction of position identification deviation, is easy to implement in engineering, and is suitable for high-reliability and high-redundancy control places of permanent magnet synchronous motors, and is particularly suitable for fields such as rim propulsion and high-power multi-phase motors that require the use of position sensorless control to improve reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the control method of the present invention;

[0027] The reference numerals of the figures are: 1—current detection and calculation link, 2—rotor position identification link, 3—position deviation calculation link, 4—position compensation and action link. DETAILED DESCRIPTION

[0028] The following further describes the implementation of the present invention with reference to specific examples and drawings.

[0029] Example 1

[0030] like Figure 1As shown, the present invention discloses a method for angle identification and correction of a permanent magnet synchronous motor, which is used in a control system of a three-phase or multi-phase permanent magnet synchronous motor powered by a voltage-type inverter. The method comprises a current detection and calculation link 1, a rotor position identification link 2, a position deviation calculation link 3, and a position compensation and action link 4. The control method includes the following steps.

[0031] Step 1: Get the permanent magnet synchronous motor current i by sampling the current sensor na 、i nb and i nc , the current detection calculation link 1 is used to sample the current i na 、i nb and i nc Coordinate transformation gives the current i in the stationary coordinate system αβ0 and the current i in the rotating coordinate system dq0 The specific steps include:

[0032] Step 1.1, the current i in the stationary three-phase coordinate system na 、i nb and i nc The current i in the stationary coordinate system is obtained by 3s / 2s coordinate transformation αβ0 , the calculation formula is:

[0033]

[0034] Step 1.2, transform the current i in the stationary three-phase coordinate system into na 、i nb and i nc Transformed into the current i in the rotating two-phase coordinate system q , the position transformation uses the identification angle θ, and the calculation formula is:

[0035]

[0036] Step 2: Rotor position identification link 2 obtains the initial position identification value of the motor based on the position identification algorithm based on back electromotive force, magnetic flux or high frequency signal injection.

[0037] Step 3, position deviation calculation link 3 sets the DC axis current given i dq_ref =0, calculate the identification angle deviation Δθ based on the DC component of the AC and DC axis voltages, and store it in the operating condition table in combination with the speed information. Specifically including:

[0038] Step 3.1, set the DC axis current reference i dq_ref =0.

[0039] Step 3.2, AC and DC axis voltage u dq Filter and extract the DC component u dq_dc.

[0040] Step 3.3, according to the DC component of the AC and DC axis voltage u d_dc and u q_dc , calculate the back electromotive force amplitude at the current speed

[0041] Step 3.4, direct axis voltage u d_dc Normalized to

[0042] Step 3.5, use PI regulator or variable step size to calculate the angle deviation Δθ=f(u pu ).

[0043] Step 3.6: record and store the current rotation speed and angle compensation value.

[0044] Step 3.7, determine whether the position identification deviation calculation at all speeds is completed. If completed, exit the position deviation calculation; otherwise, change the speed closed-loop setting and return to step 3.1.

[0045] Step 4, position compensation and action link 4 check the working condition table to obtain the identification angle deviation Δθ at the current speed, and update the motor angle Act on the permanent magnet synchronous motor vector control system.

[0046] The step 4 can be achieved by normalizing the value u pu Perform PI regulator operation to obtain position deviation Δθ, and set the proportional and integral parameters of PI regulator to be k p and k i , the function is:

[0047] Δθ=k p +k i ∫u pu dt,

[0048] The variable step size calculation can be used to change the regulator proportional and integral parameters k according to the normalized direct axis voltage p =f1(u pu ) and k i =f2(u pu ), improving the dynamic performance of the system.

[0049] Example 2

[0050] The control method is described in detail using a surface-mount dual six-phase open-winding permanent magnet synchronous motor as an example. The motor has a rated power of 600 kW, a rated voltage of 280 V, a rated current of 200 A, a rated speed of 150 r / min, and a pole pair count of 10. The control method includes the following steps.

[0051] Step (1): obtain the permanent magnet synchronous motor current i by sampling the current sensor na 、i nb and i nc , for the sampling current i na 、i nb and i nc Coordinate transformation gives the current i in the stationary coordinate system αβ0 and the current i in the rotating coordinate system dq0 , the position transformation adopts the compensated identification angle θ.

[0052] Step (2): Obtain the initial value of the identification according to the fourth-order sliding mode full-state observer position identification algorithm

[0053] Step (3): Set the DC axis current given i dq_ref =0, calculate the identification angle deviation Δθ based on the DC component of the AC and DC axis voltages, and store it in the operating condition table in combination with the speed information. Follow the steps below.

[0054] Set the DC axis current reference i dq_ref =0; AC and DC axis voltage u dq Perform sliding average filtering, the number of filtering points is the current switching frequency / base frequency, and the DC component u is obtained by filtering dq_dc ; According to the DC component of the AC and DC axis voltage u d_dc and u q_dc , calculate the back electromotive force amplitude at the current speed Direct axis voltage u d_dc Normalized to PI regulator is used to calculate the angle deviation Δθ=f(u pu ), the detailed formula is Δθ=k p +k i ∫u pu dt, records and stores the current speed and angle compensation value Δθ; when the position identification deviation calculation at all speeds is completed, the position deviation calculation is exited.

[0055] Step (4): Look up the table to obtain the identification angle deviation Δθ at the current speed and update the motor angle Act on the permanent magnet synchronous motor vector control system.

[0056] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A method for identifying and correcting the angle of a permanent magnet synchronous motor, used for a three-phase or multi-phase permanent magnet synchronous motor powered by a voltage-source inverter, characterized in that: The control system is composed of the current detection calculation link (1), the rotor position identification link (2), the position deviation calculation link (3) and the position compensation and action link (4). The steps are as follows: Step 1: Get the permanent magnet synchronous motor current i by sampling the current sensor na 、i nb and i nc , the current detection calculation link (1) samples the current i na 、i nb and i nc Coordinate transformation gives the current i in the stationary coordinate system αβ0 and the current i in the rotating coordinate system dq0 ; Step 2, rotor position identification link (2) obtains the initial position identification value of the permanent magnet synchronous motor rotor according to the position identification algorithm ; Step 3, Position deviation calculation link (3) Set the DC axis current setting , calculate the identification angle deviation Δθ based on the DC component of the AC and DC axis voltages, and store it in the operating condition table in combination with the speed information: Step 3.1, set the DC axis current setting ; Step 3.2, the DC-axis voltage u dq Filter and extract the DC component u dq_dc ; Step 3.3, according to the DC component of the AC and DC axis voltage u d_dc and u q_dc , calculate the back electromotive force amplitude at the current speed ; Step 3.4, the DC component of the direct axis voltage u d_dc Normalized to ; Step 3.5: Calculate the angle deviation using a PI regulator or variable step size ; Step 3.6, record and store the current speed and angle compensation value; Step 3.7: Determine whether the position identification deviation calculation is completed at all speeds. If it is completed, exit the position deviation calculation; otherwise, change the speed closed-loop setting and return to step 3.

1. Step 4, position compensation and action link (4) Check the working condition table to obtain the identification angle deviation Δθ at the current speed and update the motor angle , acting on the permanent magnet synchronous motor vector control system.

2. A method for angle identification and correction of a permanent magnet synchronous motor according to claim 1, characterized in that: The step 1 specifically includes: Step 1.1, the current i in the stationary three-phase coordinate system na 、i nb and i nc The current i in the stationary coordinate system is obtained by 3s / 2s coordinate transformation αβ0 , the calculation formula is: ； Step 1.2, transform the current in the stationary three-phase coordinate system into na 、i nb and i nc Transformed into the current i in the rotating two-phase coordinate system q , the position transformation uses the identification angle θ, and the calculation formula is: 。 3. A method for angle identification and correction of a permanent magnet synchronous motor according to claim 2, characterized in that: The rotor initial position identification value in step 2 It is obtained through a position identification algorithm based on back electromotive force, magnetic flux or a position identification algorithm based on high-frequency signal injection.

4. A method for angle identification and correction of a permanent magnet synchronous motor according to claim 1, characterized in that: The step 3 is to normalize the value u pu Perform PI regulator operation to obtain position deviation Δθ. The proportional and integral parameters of PI regulator are k p and k i , the function is , using variable step size calculation, changing the regulator proportional and integral parameters according to the normalized direct axis voltage and .

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