Dynamic performance enhanced permanent magnet synchronous motor voltage closed-loop field weakening control algorithm

Abstract

The invention relates to a permanent magnet synchronous motor voltage closed-loop field weakening control algorithm, in particular to a dynamic performance enhanced permanent magnet synchronous motor voltage closed-loop field weakening control algorithm. The invention aims to overcome the defects of the traditional field weakening control method of the permanent magnet synchronous motor. The method comprises the following steps: step 1, calculating a dynamic performance enhancement lookup table, and constructing a voltage closed-loop weak magnetic framework; 2, calculating a weight factor K in a smooth transition process; and step 3, synthesizing the weak magnetic reference output of the voltage closed-loop method and the weak magnetic reference output of the lookup table method according to the weight factor K. The invention belongs to the technical field of voltage closed-loop field weakening control of the permanent magnet synchronous motor.

Description

Technical Field

[0001] The invention relates to a permanent magnet synchronous motor voltage closed-loop weak magnetic field control algorithm, belonging to the technical field of permanent magnet synchronous motor voltage closed-loop weak magnetic field control. Background Art

[0002] Permanent magnet synchronous motors require weak magnetic field control when running above base speed. However, traditional methods for obtaining weak magnetic field control reference values, such as voltage closed-loop method and lookup table method, cannot achieve high speed and strong robustness at the same time, resulting in loss of dynamic or steady-state performance.

[0003] like Figure 1 As shown in the figure, the traditional voltage closed-loop weak magnetic control framework introduces a voltage loop on the basis of the double closed-loop; there are two problems with the traditional permanent magnet synchronous motor weak magnetic control method: first, for the voltage closed-loop method, the voltage closed-loop PI regulator will output a negative d-axis current only when the stator voltage amplitude exceeds the voltage limit, which is bound to cause overshoot of the voltage vector amplitude in the dynamic process; second, for the lookup table method, the set value is greatly affected by the parameter change. If the motor parameters are inaccurate, the steady-state operating point position of the weak magnetic field of the lookup table method will deviate from the actual one. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the conventional permanent magnet synchronous motor weak magnetic field control method and further proposes a permanent magnet synchronous motor voltage closed-loop weak magnetic field control algorithm with enhanced dynamic performance.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problem is: the steps of the present invention include:

[0006] Step 1: Calculate the dynamic performance enhancement lookup table and build a voltage closed-loop magnetic weakening framework;

[0007] Step 2, calculating the weight factor K in the smooth transition process;

[0008] Step 3: The weak magnetic reference output of the voltage closed-loop method and the weak magnetic reference output of the lookup table method are synthesized according to the weight factor K.

[0009] Furthermore, step 1 specifically includes:

[0010] The dynamic performance enhancement lookup table is calculated according to the permanent magnet synchronous motor's weakening magnetic working point, and a weakening magnetic control framework is established.

[0011] Furthermore, the minimum value of the weight factor K in step 2 is 1, K=1 indicates steady state, K>1 indicates dynamic state, and the calculation formula of the weight factor K is:

[0012]

[0013] In formula (1), ω e,error is the speed reference value ωe,ref With feedback value ω e The error, δ is the expected speed control accuracy set by humans, when ω e,error >δ·ω e,ref When ω e,error <δ·ω e,ref It indicates that the system is in steady state.

[0014] Furthermore, the final output i in step 3 d,ref for:

[0015]

[0016] In formula (2), i d,ref1 represents the output of the voltage closed-loop method, i d,ref2 represents the output of the lookup table method. When the speed or load changes, K suddenly increases to its maximum value, i d,ref by i d,ref2 dominant, as time goes by, K gradually decreases to 1, i d,ref2 The weight gradually becomes 0, achieving i d,ref1 and i d,ref2 Adaptive smooth transition between.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention combines the advantages of the table lookup method and the voltage closed-loop method, and optimizes the dynamic current trajectory of the traditional voltage closed-loop weak magnetic field through an adaptive trade-off algorithm;

[0019] 2. The present invention suppresses current overshoot in the dynamic process while ensuring the robustness of steady-state parameters;

[0020] 3. The present invention optimizes the dynamic current trajectory of the traditional voltage closed-loop method and solves the parameter sensitivity problem of the lookup table method through the voltage closed-loop method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the framework of voltage closed-loop weak magnetic control of a traditional permanent magnet synchronous motor;

[0022] Figure 2 is a schematic diagram of the present invention;

[0023] Figure 3 It is a schematic diagram of the dynamic current trajectory comparison experimental results;

[0024] Figure 4 It is a schematic diagram of the step acceleration test results when the parameters are mismatched;

[0025] Figure 5 This is a schematic diagram of the test results of sudden load when the parameters are mismatched. DETAILED DESCRIPTION

[0026] Specific implementation method 1: Figure 2 As shown, a voltage closed-loop weakening control algorithm for a permanent magnet synchronous motor with enhanced dynamic performance includes the following specific steps:

[0027] Step 1: Calculate the dynamic performance enhancement lookup table and build a voltage closed-loop magnetic weakening framework;

[0028] Calculate the dynamic performance enhancement lookup table based on the permanent magnet synchronous motor's weak magnetic working point and build a weak magnetic control framework;

[0029] Step 2, calculating the weight factor K in the smooth transition process;

[0030] The minimum value of the weight factor K is 1. K = 1 indicates steady state, and K > 1 indicates dynamic state. The calculation formula of the weight factor K is:

[0031]

[0032] In formula (1), ω e,error is the speed reference value ω e,ref With feedback value ω e The error, δ is the expected speed control accuracy set by humans, when ω e,error >δ·ω e,ref When ω e,error <δ·ω e,ref When , the system is in steady state;

[0033] Step 3, combining the weak magnetic reference output of the voltage closed-loop method and the weak magnetic reference output of the lookup table method according to the weight factor K;

[0034] The final output i d,ref for:

[0035]

[0036] In formula (2), i d,ref1 represents the output of the voltage closed-loop method, i d,ref2 represents the output of the lookup table method. When the speed or load changes, K suddenly increases to its maximum value, i d,ref by i d,ref2 dominant, as time goes by, K gradually decreases to 1, i d,ref2 The weight gradually becomes 0, achieving i d,ref1 and i d,ref2 Adaptive smooth transition between.

[0037] Experimental verification

[0038] The present invention is used to conduct an experimental verification on an actual three-phase permanent magnet synchronous motor towing test platform. The motor used in the experiment has a rated voltage of 380V and a rated power of 2.2kW. Figure 3 As shown, the speed step experiment refers to the motor speed suddenly increasing from the base speed to 1.5 times the base speed and then suddenly decreasing to the base speed, and the load experiment refers to suddenly adding 50% of the rated load at 1.2 times the base speed and then removing the load; according to the experimental results, the area enclosed by the current trajectory of the voltage closed-loop method is the largest, which means its dynamic response is the worst, while the area of ​​the lookup table method is the smallest, which means better dynamic performance. The present invention enhances the dynamic performance of the traditional voltage closed-loop method, so that it has a dynamic current response similar to that of the lookup table method.

[0039] In order to further explain the parameter robustness of the present invention, a parameter mismatch experiment was conducted, such as Figure 4 and Figure 5 As shown, it can be seen that, in steady state, parameter changes will not affect the d-axis current reference of the voltage closed-loop method and the proposed method, but will deteriorate the performance of the lookup table method, especially the load experiment; in addition, since the speed adaptive voltage regulator is related to the inductance parameters, the dynamic performance of the voltage closed-loop method will also be affected by parameter mismatch; it can be seen from the experimental results that the present invention is least affected by parameter changes.

[0040] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A voltage closed-loop weakening control algorithm for a permanent magnet synchronous motor with enhanced dynamic performance, characterized in that: The specific steps include: Step 1: Calculate the dynamic performance enhancement lookup table and build a voltage closed-loop magnetic weakening framework; Step 2, calculating the weight factor K in the smooth transition process; Step 3: The weak magnetic reference output of the voltage closed-loop method and the weak magnetic reference output of the lookup table method are synthesized according to the weight factor K.

2. The voltage closed-loop weakening control algorithm of a permanent magnet synchronous motor with enhanced dynamic performance according to claim 1 is characterized in that: Step 1 specifically includes: The dynamic performance enhancement lookup table is calculated according to the permanent magnet synchronous motor's weakening magnetic working point, and a weakening magnetic control framework is established.

3. The voltage closed-loop weakening control algorithm of a permanent magnet synchronous motor with enhanced dynamic performance according to claim 1 is characterized in that: The minimum value of the weight factor K in step 2 is 1, K = 1 indicates steady state, K> 1 indicates dynamic state, and the calculation formula of the weight factor K is: In formula (1), ω e,error is the speed reference value ω e,ref With feedback value ω e The error, δ is the expected speed control accuracy set by humans, when ω e,error >δ·ω e,ref When ω e,error <δ·ω e,ref It indicates that the system is in steady state.

4. The voltage closed-loop weakening control algorithm of a permanent magnet synchronous motor with enhanced dynamic performance according to claim 1 is characterized in that: The final output i in step 3 d,ref for: In formula (2), i d,ref1 Represents the output of the voltage closed-loop method, i d,ref2 represents the output of the lookup table method. When the speed or load changes, K suddenly increases to its maximum value, i d,ref byi d,ref2 dominant, as time goes by, K gradually decreases to 1, i d,ref2 The weight gradually becomes 0, achieving i d,ref1 and i d,ref2 Adaptive smooth transition between.

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