A phase error compensation method for sensorless control of permanent magnet synchronous motor

Abstract

The application discloses a phase error compensation method for permanent magnet synchronous motor position sensorless control, and belongs to the technical field of permanent magnet synchronous motor position sensorless control.The application solves the problems that the existing method cannot realize closed-loop compensation, the compensation effect is influenced by motor parameters, and the phase error of the position sensorless algorithm cannot be detected.The application obtains the torque values of the motor in two working states by changing the excitation current reference value, and then obtains the torque error value by difference.The function relationship between the torque error and the phase error is established, and the phase error is compensated by the torque error.The application reflects the phase error by the size of the torque difference, can effectively detect the error in the compensation phase, realizes the online closed-loop compensation of the phase error, and has strong robustness because the influence of the motor parameter change is offset in the torque difference process of the two working points.The application can be applied to the position sensorless control phase error compensation.

Description

Technical Field

[0001] This invention belongs to the field of sensorless control technology for permanent magnet synchronous motors, and specifically relates to a phase error compensation method for sensorless control of permanent magnet synchronous motors. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in home appliances and new energy vehicles due to their high efficiency, high power density, and excellent dynamic performance. Traditional PMSM control typically relies on position sensors (such as rotary encoders or Hall effect sensors) to obtain rotor position. However, position sensors not only increase cost and complexity but also reduce system reliability. Therefore, sensorless control technology has gradually become a research hotspot.

[0003] Sensorless control estimates rotor position information using current, voltage, and motor parameters. However, in practical applications, motor parameters (such as stator inductance and stator resistance) change due to factors like temperature variations and saturation effects, leading to phase estimation errors and decreased control performance. To compensate for phase errors, some researchers have proposed solutions. For example, Reference 1 (Correction of rotor position estimation error for high-speed permanent magnet synchronous motor sensorless drive system based on minimum-current-tracking method) analyzes the constant torque curve of a surface-mounted permanent magnet synchronous motor using the minimum current vector method. When the constant torque curve is no longer parallel to the d-axis due to parameter changes, it affects the position error correction results. Furthermore, Reference 2 (Online temperature identification strategy for position sensorless PMSM drives with position error adaptive compensation) applies the minimum current vector magnitude method to an embedded permanent magnet synchronous motor by establishing functional relationships between different coordinate systems; however, this method is affected by parameter accuracy. Reference 3 (Simple and effective online position error compensation method for sensorless SPMSM drives) can effectively identify load-related position estimation errors in surface-mounted permanent magnet synchronous motors based on the torque characteristic method. However, this method is an open-loop control method, and if errors still exist in the compensation phase, they cannot be effectively detected, thus failing to achieve closed-loop compensation. Furthermore, this method is still inherently affected by motor parameters.

[0004] In summary, existing methods still cannot achieve closed-loop compensation, the compensation effect is affected by motor parameters, they are highly sensitive to changes in motor parameters, and they cannot detect the phase error in the compensation phase. Therefore, proposing a new phase error compensation method to solve the above problems is an urgent need. Summary of the Invention

[0005] The purpose of this invention is to solve the problems that existing methods cannot achieve closed-loop compensation, the compensation effect is affected by motor parameters, and the phase error of the sensorless algorithm cannot be detected. Therefore, this invention proposes a sensorless control phase error compensation method for permanent magnet synchronous motors.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for compensating phase error of permanent magnet synchronous motor without position sensor control, the method specifically including the following steps:

[0007] Step 1: Initialize the number of iterations for compensation, l = 1;

[0008] Step 2: Collect the torque current i of the motor under stable operating conditions. sq1,l and excitation current i sd1,l Then, based on the torque current i sq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l ;

[0009] Step 3: Change the excitation current reference value, and collect the torque current i again after the motor returns to a stable operating state. sq2,l and excitation current i sd2,l Then, based on the torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l ;

[0010] Step 4: Based on the electromagnetic torque T e1,l and electromagnetic torque T e2,l To calculate the torque error ΔT e,l And compare the torque error ΔT e,l Compared with the set torque error threshold ΔT e-min,l Size:

[0011] If ΔT e,l <ΔT e-min,l Then the phase error compensation ends;

[0012] If ΔT e,l ≥ΔT e-min,l If so, proceed to step 5;

[0013] Step 5: Obtain the rotor phase error compensation angle Δθ based on the torque error calculated in Step 4. l ;

[0014] Step 6: Compensate for rotor phase error angle After compensating for the rotor phase error, let l = l + 1, and then return to step 2.

[0015] Further, in step 1, the number of iterations for compensation is initialized to l = 1;

[0016] Step 2: Collect the torque current i of the motor under stable operating conditions. sq1,l and excitation current i sd1,l Then, based on the torque current isq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l ;

[0017] Step 3: Change the excitation current reference value, and collect the torque current i again after the motor returns to a stable operating state. sq2,l and excitation current i sd2,l Then, based on the torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l ;

[0018] Step 4: Based on the electromagnetic torque T e1,l and electromagnetic torque T e2,l To calculate the torque error ΔT e,l And compare the torque error ΔT e,l Compared with the set torque error threshold ΔT e-min,l Size:

[0019] If ΔT e,l <ΔT e-min,l Then the phase error compensation ends;

[0020] If ΔT e,l ≥ΔT e-min,l If so, proceed to step 5;

[0021] Step 5: Obtain the rotor phase error compensation angle Δθ based on the torque error calculated in Step 4. l ;

[0022] Step 6: Compensate for rotor phase error angle After compensating for the rotor phase error, let l = l + 1, and then return to step 2.

[0023] Furthermore, in step 3, changing the excitation current reference value specifically involves:

[0024] i′ d,ref =i d,ref -Δi d,ref

[0025] Among them, i d,ref This is the original reference value for the excitation current;

[0026] Δi d,ref This represents the change in the reference value of the excitation current.

[0027] i′ d,ref This is the changed reference value for the excitation current.

[0028] Furthermore, the statement based on torque current isq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l Specifically:

[0029]

[0030] Among them, T e2,l This refers to the electromagnetic torque of the motor when the reference value of the excitation current changes.

[0031] Furthermore, the specific process of step 4 is as follows:

[0032] ΔT e,l =T e1,l -T e2,l

[0033] Where, ΔT e,l This represents the torque error.

[0034] Furthermore, the specific process of step 5 is as follows:

[0035] Δθ l =k i ·ΔT e,l

[0036] Where, Δθ l This is the rotor phase error compensation angle;

[0037] k i This represents the slope of the phase error relative to the torque error.

[0038] Furthermore, the calculation process for the slope of the phase error relative to the torque error is as follows:

[0039] Differentiating the torque error with respect to the rotor phase error yields:

[0040]

[0041] Among them, i s1,l This represents the steady-state current amplitude before the excitation current changes. The rotor phase angle calculated by the low-pass second-order filter observer before the excitation current change, i s2,l This represents the steady-state current amplitude after the excitation current is changed. The rotor phase angle calculated by the low-pass second-order filter observer after the excitation current is changed;

[0042] The slope of the phase error relative to the torque error is:

[0043]

[0044] Where, k iThis represents the slope of the phase error relative to the torque error.

[0045] Furthermore, the method of utilizing rotor phase error compensation angle The specific process for compensating for rotor phase error is as follows:

[0046]

[0047] in, The rotor phase error before compensation;

[0048] This is the compensated rotor phase error.

[0049] The beneficial effects of this invention are:

[0050] This invention obtains the motor torque values ​​under two operating conditions by changing the excitation current reference value, and then calculates the difference to obtain the torque error value. A functional relationship between torque error and phase error is then established, and the phase error is compensated for by the torque error. Since changes in motor parameters cause simultaneous changes in the torque calculations under both operating conditions, the impact of these changes is canceled out during the torque difference calculation at the two operating points. This reduces the sensitivity of the method to changes in motor parameters and ensures the effectiveness of phase error compensation. Furthermore, this invention uses whether the magnitude of the torque difference meets the required range to reflect the phase error, effectively detecting and compensating for phase errors, and achieving online closed-loop compensation for phase errors, thus improving the accuracy of rotor position estimation. Attached Figure Description

[0051] Figure 1 This is a structural block diagram of a sensorless control phase error compensation method for a permanent magnet synchronous motor according to the present invention.

[0052] Figure 2 The results are experimental findings of the phase error compensation method of the present invention under 30% rated load when the motor suddenly introduces a phase error with a lag of 30° at 1600 r / min.

[0053] Figure 3 When the motor is running at a steady state of 1000 r / min under 25% rated load, and the inductance parameter changes from L... S The mutation was 0.3L. S Experimental results of the phase error compensation method of the present invention under the following circumstances;

[0054] Figure 4 When the motor is running at a steady state of 1000 r / min under 25% rated load, and the inductance parameter changes from L... S The mutation resulted in 1.7L. S Experimental results of the phase error compensation method of the present invention under the following circumstances;

[0055] Figure 5 When the motor is running at 1000 r / min in steady state under 80% rated load, and the inductance parameter changes from L... S The mutation was 0.3L. S Experimental results of the phase error compensation method of the present invention under the following circumstances;

[0056] Figure 6 When the motor is running at 1000 r / min in steady state under 80% rated load, and the inductance parameter changes from L... S The mutation resulted in 1.7L. S Experimental results of the phase error compensation method of the present invention under the following circumstances;

[0057] Figures 2 to 6 In the figure, the horizontal axis of the curve represents time. Detailed Implementation

[0058] Specific implementation method one: Combining Figure 1 This embodiment describes a sensorless control phase error compensation method for a permanent magnet synchronous motor, which specifically includes the following steps:

[0059] Step 1: Initialize the number of iterations for compensation, l = 1;

[0060] Step 2: Collect the torque current i of the motor under stable operating conditions. sq1,l and excitation current i sd1,l This will also affect the torque current i sq1 This is called the d-axis fundamental current, and also the excitation current i sd1 This is called the q-axis fundamental current, and then based on the torque current i sq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l ;

[0061] Step 3: Change the excitation current reference value, and collect the torque current i again after the motor returns to a stable operating state. sq2,l and excitation current i sd2,l Then, based on the torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l ;

[0062] Step 4: Based on the electromagnetic torque T e1,l and electromagnetic torque T e2,l To calculate the torque error ΔT e,l And compare the torque error ΔT e,l Compared with the set torque error threshold ΔT e-min,l Size:

[0063] If ΔT e,l <ΔT e-min,l Then the phase error compensation ends;

[0064] If ΔT e,l ≥ΔT e-min,l If so, proceed to step 5;

[0065] Step 5: Obtain the rotor phase error compensation angle Δθ based on the torque error calculated in Step 4. l ;

[0066] Step 6: Compensate for rotor phase error angle After compensating for the rotor phase error, let l = l + 1, and then return to step 2.

[0067] This invention uses torque error as the criterion for whether phase error compensation is needed. When the torque error is within the required range, the rotor phase is considered close to the actual phase, and phase error compensation ends. When the torque error is outside the required range, phase error compensation is performed iteratively until the torque error is within the required range.

[0068] Specific Implementation Method Two: This implementation method is a further limitation of Specific Implementation Method One, wherein the torque current i sq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l The specific process is as follows:

[0069]

[0070] Where p is the pole logarithm;

[0071] ψ f For permanent magnet flux;

[0072] L d It is the d-axis inductance;

[0073] L q It is the q-axis inductance.

[0074] The other steps and parameters are the same as in Specific Implementation Method 1.

[0075] Specific Implementation Method 3: This implementation method further defines Specific Implementation Method 2. In step 3, changing the excitation current reference value specifically involves:

[0076] i′ d,ref =i d,ref -Δi d,ref

[0077] Among them, i d,refThis is the original reference value for the excitation current;

[0078] Δi d,ref This represents the change in the reference value of the excitation current.

[0079] i′ d,ref This is the changed reference value for the excitation current.

[0080] The other steps and parameters are the same as in Specific Implementation Method Two.

[0081] Specific Implementation Method Four: This implementation method is a further limitation of Specific Implementation Method Three, wherein the torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l Specifically:

[0082]

[0083] Among them, T e2,l This refers to the electromagnetic torque of the motor when the reference value of the excitation current changes.

[0084] The other steps and parameters are the same as in Specific Implementation Method 3.

[0085] Specific Implementation Method Five: This implementation method is a further limitation of Specific Implementation Method Four. The specific process of step 4 is as follows:

[0086] ΔT e,l =T e1,l -T e2,l

[0087] Where, ΔT e,l This represents the torque error.

[0088] The other steps and parameters are the same as in Specific Implementation Method Four.

[0089] Specific Implementation Method Six: This implementation method is a further limitation of Specific Implementation Method Five. The specific process of step 4 is as follows:

[0090] The specific process of step 5 is as follows:

[0091] Δθ l =k i ·ΔT e,l

[0092] Where, Δθ l This is the rotor phase error compensation angle;

[0093] k i This represents the slope of the phase error relative to the torque error.

[0094] The other steps and parameters are the same as in Specific Implementation Method 5.

[0095] Specific Implementation Method Seven: This implementation method further defines Specific Implementation Method Six. The calculation process for the slope of the phase error relative to the torque error is as follows:

[0096] Differentiating the torque error with respect to the rotor phase error yields:

[0097]

[0098] Among them, i s1,l This represents the steady-state current amplitude before the excitation current changes. The rotor phase angle calculated by the low-pass second-order filter observer before the excitation current change, i s2,l This represents the steady-state current amplitude after the excitation current is changed. The rotor phase angle calculated by the low-pass second-order filter observer after the excitation current is changed;

[0099] The slope of the phase error relative to the torque error is:

[0100]

[0101] Where, k i This represents the slope of the phase error relative to the torque error.

[0102] The parameter relationships in this embodiment satisfy: According to i sd1,l You can get i s1,l and According to i sd2,l You can get i s2,l and And satisfied

[0103] The other steps and parameters are the same as in Specific Implementation Method Six.

[0104] Specific Implementation Method Eight: This implementation method is a further limitation of Specific Implementation Method Seven, wherein the rotor phase error compensation angle is utilized. The specific process for compensating for rotor phase error is as follows:

[0105]

[0106] in, The rotor phase error before compensation;

[0107] This is the compensated rotor phase error.

[0108] The other steps and parameters are the same as in Specific Implementation Method Seven.

[0109] The following is through Figure 2 , Figure 3 , Figure 4 , Figure 5 as well as Figure 6 The experimental results shown are used to verify the effectiveness of the method proposed in this invention. Figure 2 The experimental results show that when the motor suddenly introduces a phase error with a lag of 30° at 1600 r / min under 30% rated load, the phase error is corrected using the method of this invention. The waveforms from top to bottom are: phase error, d-axis current, calculated phase error compensation value, torque error, rotor phase calculated by the positionless control algorithm and the actual phase. This shows that the method of this invention can calculate the phase error well and achieve online compensation under high speed and large lag angle.

[0110] Figure 3 and Figure 4 The results are experimental findings of varying motor parameters under light load (25% of rated load) conditions when the motor is running at a steady state of 1000 r / min. Figure 5 and Figure 6 The results show that the phase error caused by the change of motor parameters can be effectively suppressed by the method of this invention when the motor is running at a steady state of 1000 r / min under heavy load (80% of rated load).

[0111] The above examples of the present invention are merely illustrative of the computational model and process of the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is impossible to exhaustively list all possible implementations here. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for compensating phase error in sensorless control of a permanent magnet synchronous motor, characterized in that, The method specifically includes the following steps: Step 1: Initialize the number of iterations for compensation, l = 1; Step 2: Collect the torque current i of the motor under stable operating conditions. sq1,l and excitation current i sd1,l Then, based on the torque current i sq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l ; Step 3: Change the excitation current reference value, and collect the torque current i again after the motor returns to a stable operating state. sq2,l and excitation current i sd2,l Then, based on the torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l ; Step 4: Based on the electromagnetic torque T e1,l and electromagnetic torque T e2,l To calculate the torque error ΔT e,l And compare the torque error ΔT e,l Compared with the set torque error threshold ΔT e-min,l Size: If ΔT e,l <ΔT e-min,l Then the phase error compensation ends; If ΔT e,l ≥ΔT e-min,l If so, proceed to step 5; Step 5: Obtain the rotor phase error compensation angle Δθ based on the torque error calculated in Step 4. l ; Step 6: Compensate for rotor phase error angle After compensating for the rotor phase error, let l = l + 1, and then return to step 2.

2. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 1, characterized in that, The information based on torque current i sq1,l and excitation current i sd1,l Calculate the electromagnetic torque T of the motor under steady operating conditions. e1,l The specific process is as follows: Where p is the pole logarithm; ψ f For permanent magnet flux; L d It is the d-axis inductance; L q It is the q-axis inductance.

3. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 2, characterized in that, In step 3, changing the excitation current reference value specifically involves: i′ d,ref =i d,ref -Δi d,ref Among them, i d,ref This is the original reference value for the excitation current; Δi d,ref This represents the change in the reference value of the excitation current. i′ d,ref This is the changed reference value for the excitation current.

4. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 3, characterized in that, The information based on torque current i sq2,l and excitation current i sd2,l Calculate the electromagnetic torque T of the motor when the excitation current reference value changes. e2,l Specifically: Among them, T e2,l This refers to the electromagnetic torque of the motor when the reference value of the excitation current changes.

5. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 4, characterized in that, The specific process of step 4 is as follows: ΔT e,l =T e1,l -T e2,l Where, ΔT e,l This represents the torque error.

6. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 5, characterized in that, The specific process of step 5 is as follows: Dth l =k i ·ΔT e,l Where, Δθ l This is the rotor phase error compensation angle; k i This represents the slope of the phase error relative to the torque error.

7. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 6, characterized in that, The calculation process for the slope of the phase error relative to the torque error is as follows: Differentiating the torque error with respect to the rotor phase error yields: Among them, i s1,l This represents the steady-state current amplitude before the excitation current changes. The rotor phase angle calculated by the low-pass second-order filter observer before the excitation current change, i s2,l This represents the steady-state current amplitude after the excitation current is changed. The rotor phase angle calculated by the low-pass second-order filter observer after the excitation current is changed; The slope of the phase error relative to the torque error is: Where, k i This represents the slope of the phase error relative to the torque error.

8. The method for compensating phase error in sensorless control of a permanent magnet synchronous motor according to claim 7, characterized in that, The use of rotor phase error compensation angle The specific process for compensating for rotor phase error is as follows: in, The rotor phase error before compensation; This is the compensated rotor phase error.

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