Resistance parameter determination method and system of permanent magnet synchronous motor

Abstract

The invention relates to a resistance parameter determination method for a permanent magnet synchronous motor, and the method comprises the steps: setting an excitation frequency and an excitation current amplitude of a low-frequency excitation signal, and generating an excitation current instruction and an excitation signal angle of the low-frequency excitation signal according to the excitation frequency and the excitation current amplitude; the excitation current instruction is applied to a motor control loop, and a voltage signal and a current signal of the permanent magnet synchronous motor are collected; according to the excitation signal angle, the voltage signal and the current signal are synchronized to a low-frequency excitation source synchronous rotating coordinate system, and conversion voltage and conversion current are generated; and determining a resistance parameter according to the conversion voltage and the conversion current. According to the method, in the operation process of the motor, the low-frequency excitation current is injected into the motor, the voltage and current changes of the motor are synchronously detected, and in combination with a coordinate transformation method, online calculation of the resistance can be effectively achieved. Since the injected low-frequency excitation current is far away from the operation frequency, the injected current signal does not have any influence on the operation of the motor.

Description

Technical Field

[0001] The present invention belongs to the field of AC transmission, and in particular relates to a method and system for determining resistance parameters of a permanent magnet synchronous motor. Background Art

[0002] In the context of aircraft engine applications, due to the complex changes in the application environment, such as excessive current flowing through the coil, poor motor cooling, temperature rise caused by the operating environment, and other heating components near the motor, the stator coil temperature may be greatly affected, resulting in large differences in the parameter performance of the motor under complex environmental conditions. Usually, under high and low temperatures, the range of variation of the motor stator resistance parameters is large, and the variation can exceed 50% of the initial value, which has a serious impact on the motor's high-precision key control algorithms such as position-free control and control bandwidth. In addition, the change in resistance can also be used as a key indicator for motor health detection. For this reason, a method for determining the resistance parameters of a permanent magnet synchronous motor is urgently needed. Summary of the invention

[0003] The present invention provides a method and system for determining resistance parameters of a permanent magnet synchronous motor, which can detect the stator resistance of the motor online without interfering with the operation of the motor, thereby improving detection efficiency and detection accuracy.

[0004] A technical solution of the present invention is as follows: A method for determining resistance parameters of a permanent magnet synchronous motor, comprising:

[0005] S10: setting the excitation frequency and excitation current amplitude of the low-frequency excitation signal, and generating an excitation current instruction and an excitation signal angle of the low-frequency excitation signal according to the excitation frequency and the excitation current amplitude;

[0006] S20: applying the excitation current command to the motor control loop to collect the voltage signal and current signal of the permanent magnet synchronous motor;

[0007] S30: according to the excitation signal angle, synchronizing the voltage signal and the current signal to the synchronous rotating coordinate system of the low-frequency excitation source to generate a conversion voltage and a conversion current;

[0008] S40: Determine resistance parameters according to the conversion voltage and the conversion current.

[0009] Furthermore, the step S10 includes:

[0010] Integrate the excitation frequency to generate an excitation signal angle;

[0011] Performing a difference operation on the excitation signal angle and the motor frequency angle of the permanent magnet synchronous motor to obtain a difference angle;

[0012] According to the difference angle, the excitation current amplitude is subjected to αβ / dq transformation to obtain an excitation current instruction.

[0013] Further, performing αβ / dq transformation on the excitation current amplitude according to the difference angle to obtain the excitation current instruction includes:

[0014] The excitation current amplitude is used as the α component in the αβ / dq transformation, the β component in the αβ / dq transformation is set to 0, and the αβ / dq transformation is performed according to the difference angle to obtain the excitation current command under the dq axis system.

[0015] Furthermore, the step S20 includes:

[0016] The excitation current instruction includes: an excitation excitation component and an excitation torque component;

[0017] The excitation magnetic component and the excitation torque component are both applied to the inner current loop of the motor control.

[0018] Furthermore, the step S30 includes:

[0019] Performing ABC / αβ transformation from three phases to two phases on the voltage signal and the current signal to obtain αβ voltage signals and αβ current signals of the voltage signal and the current signal in the αβ axis system;

[0020] According to the excitation signal angle, the αβ voltage signal and the αβ current signal are subjected to αβ / dq transformation to generate the conversion voltage and conversion current in the synchronous rotating coordinate system of the low-frequency excitation source.

[0021] Furthermore, the step S40 includes:

[0022] Low-pass filtering the conversion voltage and the conversion current;

[0023] The conversion voltage and the conversion current after low-pass filtering are divided to determine the resistance parameter.

[0024] Furthermore, it also includes: performing sliding filtering on the resistance parameter.

[0025] Furthermore, the excitation frequency of the low-frequency excitation signal is lower than the rated frequency of the permanent magnet synchronous motor, and the ratio of the rated frequency of the permanent magnet synchronous motor to the excitation frequency of the low-frequency excitation signal is greater than 100.

[0026] Another technical solution of the present invention is as follows: A system for determining resistance parameters of a permanent magnet synchronous motor, using any of the above-mentioned methods for determining resistance parameters of a permanent magnet synchronous motor, comprising:

[0027] A low-frequency excitation module, used to generate an excitation current instruction and an excitation signal angle of a low-frequency excitation signal according to an excitation frequency and an excitation current amplitude set by a user;

[0028] A motor vector control module for performing negative feedback control on the motor through a motor control loop applying an excitation current command;

[0029] A low-frequency rotation processing module, used to synchronize the voltage signal and the current signal to a synchronous rotation coordinate system of a low-frequency excitation source according to an excitation signal angle, and generate a conversion voltage and a conversion current;

[0030] The resistance calculation module is used to determine the resistance parameter according to the conversion voltage and the conversion current.

[0031] The beneficial effects of the present invention are as follows: during the operation of the motor, the present invention can effectively realize the online calculation of the resistance by injecting a low-frequency excitation current into the motor, synchronously detecting the voltage and current changes of the motor, and combining the coordinate transformation method. Since the injected low-frequency excitation current is far different from the operating frequency, the injected current signal has no effect on the operation of the motor.

[0032] The system of the present invention realizes online calculation and monitoring of resistance parameters by adding a low-frequency excitation module, a low-frequency rotation processing module and a resistance calculation module into a traditional vector control program framework. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 The present invention is a flow chart of a method for determining resistance parameters of a permanent magnet synchronous motor.

[0034] Figure 2 The system block diagram of a resistance parameter determination system of a permanent magnet synchronous motor of the present invention.

[0035] Figure 3 It is a schematic diagram of the coordinate transformation of the algorithm in the present invention.

[0036] Figure 4 It is a block diagram of the low-frequency excitation module in the present invention.

[0037] Figure 5 It is a block diagram of the low-frequency rotation processing module in the present invention.

[0038] Figure 6 It is a block diagram of the resistance calculation module in the present invention. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. The described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0040] In one technical solution of the present invention, Figure 1 It is a flowchart provided according to the specific process of a method for determining the resistance parameters of a permanent magnet synchronous motor of the present technical solution, such as Figure 1 As shown, the present invention includes:

[0041] S10: setting the excitation frequency and excitation current amplitude of the low-frequency excitation signal, and generating an excitation current instruction and an excitation signal angle of the low-frequency excitation signal according to the excitation frequency and the excitation current amplitude.

[0042] The excitation frequency of the low-frequency excitation signal is less than the rated frequency of the permanent magnet synchronous motor, and the ratio of the rated frequency of the permanent magnet synchronous motor to the excitation frequency of the low-frequency excitation signal is greater than 100.

[0043] The excitation frequency of the injected low-frequency excitation signal is far from the rated frequency of the permanent magnet synchronous motor (generally, the rated frequency of the motor is more than 100 times), so the injected current signal has no effect on the operation of the motor.

[0044] The excitation frequency is integrated to generate an excitation signal angle.

[0045] A difference operation is performed between the excitation signal angle and the motor frequency angle of the permanent magnet synchronous motor to obtain a difference angle.

[0046] According to the difference angle, the excitation current amplitude is transformed into an αβ / dq transformation to obtain an excitation current instruction. The excitation current amplitude is used as the α component in the αβ / dq transformation, the β component in the αβ / dq transformation is set to 0, and the αβ / dq transformation is performed according to the difference angle to obtain the excitation current instruction under the dq axis system.

[0047] like Figure 4 As shown, the user sets the excitation frequency f of the low-frequency excitation signal exc After that, an excitation signal angle θ is generated through digital integration. exc , the excitation signal angle θ exc The motor frequency angle θ of the current motor e Subtraction is performed as the angle input for the subsequent αβ / dq transformation. At the same time, the excitation current amplitude i set by the user excAs the excitation current command under the α axis, the excitation current command under the β axis is set to 0, and both are used as the α-β component input of the αβ / dq transformation module. Among them, the αβ / dq transformation is the coordinate system transformation used in traditional motor control. The excitation current command I under the synchronous dq axis system of the motor control loop obtained by the αβ / dq transformation calculation dExcRef and I qExcRef .

[0048] S20: Apply the excitation current command to the motor control loop to collect the voltage signal and current signal of the permanent magnet synchronous motor.

[0049] Wherein, the excitation current instruction includes: the excitation excitation component I dExcRef and the excitation torque component I qExcRef .

[0050] The excitation excitation component and the excitation torque component are both applied to the inner current loop of the motor control.

[0051] S30: According to the excitation signal angle, the voltage signal and the current signal are synchronized to the synchronous rotating coordinate system of the low-frequency excitation source to generate a conversion voltage and a conversion current.

[0052] Performing ABC / αβ transformation from three phases to two phases on the voltage signal and the current signal to obtain αβ voltage signals and αβ current signals of the voltage signal and the current signal in the αβ axis system;

[0053] According to the excitation signal angle, the αβ voltage signal and the αβ current signal are subjected to αβ / dq transformation to generate the conversion voltage and conversion current in the synchronous rotating coordinate system of the low-frequency excitation source.

[0054] like Figure 5 As shown, the voltage signal and current signal collected by the motor are synchronized to the synchronous rotating coordinate system of the low-frequency excitation source, and the voltage signal U under the three phases ABC of the motor is collected. abc , current signal I abc , respectively perform ABC / αβ transformation from three phases to two phases to calculate the values ​​of voltage and current in the αβ axis system αβ voltage signal U αβ and αβ current signal I αβ , and U αβ and I αβ As synchronous rotation transformation sources of low-frequency excitation signals, the excitation signal angle θ exc Perform αβ / dq transformation calculation to generate the conversion voltage U in the synchronous rotating coordinate system of the low-frequency excitation source d ExcOri and the conversion current I d ExcOri .

[0055] S40: Determine resistance parameters according to the conversion voltage and the conversion current.

[0056] Low-pass filtering the conversion voltage and the conversion current;

[0057] The conversion voltage and the conversion current after low-pass filtering are divided to determine the resistance parameter.

[0058] A sliding filter is performed on the resistance parameter.

[0059] The signal in the low-frequency excitation source coordinate system is processed to generate a resistance estimate, such as Figure 6 As shown. Due to the conversion voltage U d_ExcOri and the conversion current I d_ExcOr Contains the fundamental wave component of the motor, presents high-frequency component characteristics in the synchronous rotating coordinate system of the low-frequency excitation source, and converts the voltage U d_ExcOri and the conversion current I d_ExcOr Perform low-pass filtering to eliminate the fundamental component of the motor, thereby obtaining U generated by the injected low-frequency excitation current. d_Exc and I d_Exc signal, both of which are DC components in this coordinate system. d_Exc and I d_Exc After zero-crossing detection, division calculation is performed to obtain the resistance parameter of the stator resistor. Since the real-time value fluctuation of the resistance parameter of the stator resistor is large, it is necessary to adjust the timing update through sliding filtering to obtain a stable estimated value with less fluctuation.

[0060] In another technical solution of the present invention, Figure 2 The present invention is a block diagram of a specific structure of a permanent magnet synchronous motor resistance parameter determination system according to the present technical solution. The present technical solution uses any of the above-mentioned permanent magnet synchronous motor resistance parameter determination methods, including:

[0061] A low-frequency excitation module, used to generate an excitation current instruction and an excitation signal angle of a low-frequency excitation signal according to an excitation frequency and an excitation current amplitude set by a user;

[0062] A motor vector control module, used for performing negative feedback control on the motor through a motor control loop to which an excitation current command is applied;

[0063] A low-frequency rotation processing module, used to synchronize the voltage signal and the current signal to a synchronous rotation coordinate system of a low-frequency excitation source according to an excitation signal angle, and generate a conversion voltage and a conversion current;

[0064] The resistance calculation module is used to determine the resistance parameter according to the conversion voltage and the conversion current.

[0065] The control principle diagram of this system is as follows Figure 2 As shown in the figure, the motor vector control module consists of an inner current loop and an outer speed loop. The added modules are on the inner current loop, where the low-frequency excitation module is set by the user through the excitation frequency f exc and the excitation current amplitude i exc Generate an excitation current command (excitation component I dExcRef and the excitation torque component I qExcRef ) and the excitation signal angle θ of the low-frequency excitation signal exc The corresponding instruction is added to the inner current loop, and the corresponding excitation current is generated by outputting the voltage instruction to the motor. The rotation signal processing module collects the voltage signal U of the motor. abc and the current signal I abc The two variables are synchronized to the synchronous rotating coordinate system of the low-frequency excitation source to generate a conversion voltage and a conversion current; the resistance calculation module generates a resistance value by calculating the conversion voltage and the conversion current, and generates an estimated resistance value by controlling the value update rate.

[0066] The principle diagram of the algorithm coordinate transformation is as follows Figure 3 As shown. The motor controls the fundamental signal of the motor's dq axis system, and the motor rotation speed is ω e ; The rotation speed of the injected low-frequency excitation signal is ω exc , when the motor is running at rated speedω exc Relative to ω e On the one hand, the low-frequency signal is in the form of a high-frequency sinusoidal component in the dq axis system of the fundamental wave, and the average value is 0. Therefore, the interference of the low-frequency signal injected into the motor during operation is almost negligible. On the other hand, in the synchronous rotating coordinate system of the low-frequency excitation source, the low-frequency injection signal is a DC component, and the fundamental signal is a high-frequency sinusoidal component. The fundamental signal can be completely filtered out by low-pass filtering to obtain the low-frequency injection signal and response value, so as to further calculate the resistance of the motor. In summary, this method of combining low-frequency injection with coordinate transformation can effectively realize the estimation of the motor resistance without affecting the normal operation of the motor.

[0067] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for determining resistance parameters of a permanent magnet synchronous motor, characterized in that: include: S10: setting the excitation frequency and excitation current amplitude of the low-frequency excitation signal, and generating an excitation current instruction and an excitation signal angle of the low-frequency excitation signal according to the excitation frequency and the excitation current amplitude; S20: applying the excitation current command to the motor control loop to collect the voltage signal and current signal of the permanent magnet synchronous motor; S30: according to the excitation signal angle, synchronizing the voltage signal and the current signal to the synchronous rotating coordinate system of the low-frequency excitation source to generate a conversion voltage and a conversion current; S40: Determine resistance parameters according to the conversion voltage and the conversion current.

2. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 1, characterized in that: The step S10 comprises: Integrate the excitation frequency to generate an excitation signal angle; Performing a difference operation on the excitation signal angle and the motor frequency angle of the permanent magnet synchronous motor to obtain a difference angle; According to the difference angle, the excitation current amplitude is subjected to αβ / dq transformation to obtain an excitation current instruction.

3. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 2, characterized in that: The performing αβ / dq transformation on the excitation current amplitude according to the difference angle to obtain the excitation current instruction comprises: The excitation current amplitude is used as the α component in the αβ / dq transformation, the β component in the αβ / dq transformation is set to 0, and the αβ / dq transformation is performed according to the difference angle to obtain the excitation current command under the dq axis system.

4. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 1, characterized in that: The step S20 comprises: The excitation current instruction includes: an excitation excitation component and an excitation torque component; The excitation magnetic component and the excitation torque component are both applied to the inner current loop of the motor control.

5. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 1, characterized in that: The step S30 comprises: Performing ABC / αβ transformation from three phases to two phases on the voltage signal and the current signal to obtain αβ voltage signals and αβ current signals of the voltage signal and the current signal in the αβ axis system; According to the excitation signal angle, the αβ voltage signal and the αβ current signal are subjected to αβ / dq transformation to generate the conversion voltage and conversion current in the synchronous rotating coordinate system of the low-frequency excitation source.

6. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 1, characterized in that: The step S40 comprises: Low-pass filtering the conversion voltage and the conversion current; The conversion voltage and the conversion current after low-pass filtering are divided to determine the resistance parameter.

7. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 6, characterized in that: Also includes: A sliding filter is performed on the resistance parameter.

8. The method for determining the resistance parameter of a permanent magnet synchronous motor according to claim 7, characterized in that: The excitation frequency of the low-frequency excitation signal is less than the rated frequency of the permanent magnet synchronous motor, and the ratio of the rated frequency of the permanent magnet synchronous motor to the excitation frequency of the low-frequency excitation signal is greater than 100.

9. A resistance parameter determination system for a permanent magnet synchronous motor, characterized in that: The method for determining the resistance parameter of a permanent magnet synchronous motor according to any one of claims 1 to 8 comprises: A low-frequency excitation module, used to generate an excitation current instruction and an excitation signal angle of a low-frequency excitation signal according to an excitation frequency and an excitation current amplitude set by a user; A motor vector control module for performing negative feedback control on the motor through a motor control loop applying an excitation current command; A low-frequency rotation processing module, used to synchronize the voltage signal and the current signal to a synchronous rotation coordinate system of a low-frequency excitation source according to an excitation signal angle, and generate a conversion voltage and a conversion current; The resistance calculation module is used to determine the resistance parameter according to the conversion voltage and the conversion current.

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