Current lookup table-based permanent magnet synchronous motor wide voltage range control method and medium

Abstract

Disclosed in the present invention are a current lookup table-based permanent magnet synchronous motor wide voltage range control method and a medium. The method comprises: by means of a full-speed domain current calibration method, obtaining a rotating speed-torque two-dimensional lookup table under a rated bus voltage; on the basis of the lookup table, multiplying a given rotating speed with a front-and-rear amplitude limiting voltage ratio to achieve wide voltage range control; and performing friction torque compensation and sampling delay compensation of a three-phase current at different rotating speeds. The present invention takes into account bus voltage fluctuation under the complex working condition of an electric vehicle, and multiplies the given rotating speed with a variable voltage coefficient ku to obtain an input rotating speed of an input current lookup table, such that precise current control of the permanent magnet synchronous motor under different bus voltage working conditions can be achieved, thereby avoiding the complex and tedious process of re-calibration of the current lookup table under different bus voltages; the present invention also takes into account friction torque compensation and phase current sampling delay compensation at different rotating speeds, wherein the friction torque compensation can be achieved by directly adding a friction torque error into a given torque signal in real time.

Description

Permanent magnet synchronous motor wide voltage range control method and medium based on current lookup table Technical Field

[0001] The present invention relates to the field of voltage range control, and more particularly to a method and medium for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table. Background Art

[0002] Faced with increasing environmental pollution and energy depletion, new energy vehicles (NEVs) have become a mainstream alternative to traditional fuel vehicles due to their environmentally friendly nature. With the continuous development of permanent magnet materials and power electronics, permanent magnet synchronous motors (PMSMs), with their high power density and high efficiency, have gained widespread application in the NEV sector. As a key component in pure electric vehicles (BEVs), the motor's primary task is to replace the traditional engine, providing propulsion and ensuring sufficient power and stability during driving. Therefore, the driving quality of BEVs is closely linked to the motor's control performance.

[0003] To improve the efficiency of permanent magnet synchronous motor drive systems, different control algorithms are used for speeds below and above base speed. The MTPA control algorithm is used in the low-speed, non-field-weakening region of the motor; in the high-speed field-weakening region, the MTPV control algorithm is required due to DC bus voltage limitations. In industrial applications, the motor is typically calibrated to obtain a current lookup table (LUT). During motor operation, a two-dimensional speed-torque LUT is used to query the optimal quadrature and direct axis current commands in real time based on the given torque and speed, achieving optimal current control under different operating conditions. Currently, there are two main methods for obtaining the current LUT: calculating the LUT using parameters such as torque and flux linkage under stalled rotor conditions; or calibrating the LUT using a test bench under rotor rotating conditions.

[0004] Existing permanent magnet synchronous motor calibration methods only consider MTPA or MTPV current calibration under different speed and torque conditions, and control the motor using a two-dimensional speed-torque lookup table derived from bench calibration. However, most existing current calibration techniques fail to consider the impact of varying bus voltage, a significant condition in electric vehicles. While some existing technologies involve recalibration at different DC bus voltages, these methods suffer from high workload, computational complexity, and limited practicality.

[0005] FIG1 shows a current schematic diagram according to the prior art without considering the voltage variation condition.

[0006] Most existing current calibration methods fail to consider the fluctuations in the DC bus voltage of an on-board motor drive under complex operating conditions. The original two-dimensional lookup table for a fixed bus voltage is no longer feasible and may even cause motor loss of control. Figure 1 illustrates this. At a constant speed of ω1, assuming the current lookup table is calibrated at a DC bus voltage of U1, the actual motor bus voltage gradually decreases from U1 to U2 to U3. When the actual motor DC bus voltage is U2 or U3, the voltage constraint ellipse decreases. Because the current lookup table cannot adapt to changes in DC bus voltage, if the torque input to the lookup table is curve T1, this torque curve will exceed the voltage constraints corresponding to U2 or U3, resulting in reduced motor control performance and even motor loss of control.

[0007] At present, there is still a need to develop a permanent magnet synchronous motor wide voltage range control method based on current lookup table.

[0008] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0009] Summary of the Invention

[0010] The present invention proposes a wide voltage range control method and medium for a permanent magnet synchronous motor based on a current lookup table.

[0011] In a first aspect, an embodiment of the present disclosure provides a method for controlling a permanent magnet synchronous motor over a wide voltage range based on a current lookup table, comprising:

[0012] The speed-torque two-dimensional lookup table under rated bus voltage is obtained by full-speed current calibration method.

[0013] Based on the lookup table, wide voltage range control is achieved by multiplying a given speed by the ratio of the front and rear limit voltages;

[0014] Perform friction torque compensation at different speeds and sampling delay compensation of three-phase current.

[0015] Preferably, obtaining the speed-torque two-dimensional lookup table at rated bus voltage by the full-speed domain current calibration method includes:

[0016] For the low-speed non-weakening magnetic area, the exhaustive current calibration method is used for calibration;

[0017] For current calibration in the high-speed field-weakening region, use a dynamometer to drag the motor speed to a speed greater than the turning speed, maintain a constant current amplitude, and change the current vector angle. Record the current vector angle value at which the bus voltage reaches the maximum and the current can follow. Test each current vector point with equal amplitude increase to find the corresponding torque angle. Finally, select the current amplitude corresponding to the maximum torque at the same speed. Increase the speed with equal amplitude and repeat the above process, recording the feedback torque and current setpoint.

[0018] Through the above current calibration process, the bench test calibrates the current vector amplitude and its weakening magnetic angle under different speed and torque conditions, and measures the data of all working points;

[0019] Fit the data measured at different speeds and output the dq axis current i in equal parts according to the torque d and i q The data table is obtained by linear interpolation fitting of the table data to obtain the final speed-torque two-dimensional lookup table.

[0020] Preferably, the exhaustive current calibration method includes:

[0021] The dynamometer controls the motor under test to run at a constant speed under the base speed. The test bench host computer controls the motor stator current vector to start with an amplitude of 0A and a vector angle of 0°, and then changes the current vector with equal amplitude and angle in sequence and outputs it to the motor under test.

[0022] Record the actual motor output torque transmitted by CAN communication under different current vector settings until the output torque decreases. Record the maximum motor output torque and its corresponding current vector angle under this current amplitude.

[0023] Increase the given current vector amplitude by the same amount, start again from 0° and gradually increase the vector angle, and repeat the above process until the current vector amplitude reaches the maximum current value.

[0024] Preferably, based on the lookup table, achieving wide voltage range control by multiplying a given speed by the ratio of the front and rear limiting voltages includes:

[0025] Establish a mathematical model of a three-phase interior permanent magnet synchronous motor;

[0026] In a synchronously rotating dq coordinate system, calculating the amplitude of the stator voltage vector, thereby obtaining the limiting voltage of the lookup table;

[0027] Establish the voltage limit constraint equation, and then obtain the voltage limit ellipse equation and torque equation;

[0028] The input variables of the lookup table are determined to be the input speed n' and the input torque T e ', achieving wide voltage range control.

[0029] Preferably, the mathematical model of the three-phase interior permanent magnet synchronous motor is:

[0030] Where u d 、u q is the d-axis and q-axis stator voltage component; i d 、i q are the d-axis and q-axis stator current components; ω e is the electrical angular velocity; R s is the stator resistance; L d , L q is the orthogonal axis inductance; ψ f is the magnetic flux amplitude of the rotor permanent magnet; T e is the electromagnetic torque; n p is the number of motor pole pairs; J is the motor moment of inertia; B is the viscous friction coefficient; T L is the load torque; ω r is the mechanical angular velocity.

[0031] Preferably, the voltage limit constraint equation is:

[0032] Where U smax =kU dc , is the limiting voltage when using the table lookup method for control; k is the voltage coefficient, which represents the voltage margin left for the bus voltage.

[0033] Preferably, the voltage limit ellipse equation is:

[0034] Preferably, the friction torque compensation includes:

[0035] According to the motion equation of the permanent magnet synchronous motor, the friction torque is analyzed and obtained

[0036] From the above formula, we can see that the friction torque T m =Bω r , which is proportional to the mechanical angular velocity;

[0037] The friction torque is obtained by the no-load torque test. When testing the motor to be tested, its three-phase cables are suspended in the air, and the motor is controlled by a test bench at a mechanical angular velocity ω r No-load operation is performed under

[0038] The no-load torque T at the corresponding speed is obtained through CAN communication feedback m , which is the friction torque, divided by ω r Obtain the viscous friction coefficient;

[0039] The actual torque transmitted back to the test bench host computer by CAN communication is Te -T m , the real torque is used as the input torque of the speed-torque two-dimensional table and recorded;

[0040] When wide range voltage control is performed, the given speed n * Different from the input speed n', when the motor is running in steady state, the actual torque does not match the load torque, which is:

[0041] in, Denoted as friction torque error T err ;

[0042] The given torque T output by the host computer e * Add the friction torque error T err , get the input torque T from the real input current lookup table e ', that is

[0043] Preferably, the sampling delay compensation of the three-phase current includes:

[0044] The sampling circuit filter will introduce delay while suppressing high-frequency noise interference. The delay compensation should be performed according to the sampling circuit transfer function. The sampling filter transfer function H(s) is expressed as:

[0045] Where s is the Laplace operator.

[0046] In a second aspect, an embodiment of the present disclosure further provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the permanent magnet synchronous motor wide voltage range control method based on a current lookup table.

[0047] Its beneficial effects are:

[0048] The present invention takes into account the wide voltage range control of the vehicle-mounted motor under variable voltage conditions, avoiding the performance degradation and loss of control problems of the traditional lookup table method;

[0049] No need to recalibrate under different bus voltages. Only the speed signal input to the lookup table is changed to achieve wide voltage control, which is simple and efficient.

[0050] Friction torque compensation and current sampling delay compensation at different speeds improve the wide voltage range control method, and the motor has good steady-state performance.

[0051] The methods and apparatus of the present invention have other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and subsequent detailed descriptions incorporated herein, which together serve to explain the specific principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0053] FIG1 shows a current schematic diagram according to the prior art without considering the voltage variation condition.

[0054] FIG2 is a flowchart showing steps of a method for controlling a permanent magnet synchronous motor in a wide voltage range based on a current lookup table according to an embodiment of the present invention.

[0055] FIG3 shows a current diagram of changing a given rotation speed to achieve wide-range voltage control according to an embodiment of the present invention.

[0056] FIG4 shows a schematic diagram of a phase current sampling and filtering circuit according to an embodiment of the present invention.

[0057] FIG5 shows a Bode diagram of a transfer function of a current sampling filter circuit according to an embodiment of the present invention.

[0058] FIG6 is a schematic diagram showing the influence of rotor angle deviation on dq axis currents according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0060] To facilitate understanding of the solutions and effects of the embodiments of the present invention, two specific application examples are given below. Those skilled in the art should understand that the examples are only for facilitating understanding of the present invention, and any specific details thereof are not intended to limit the present invention in any way.

[0061] Example 1

[0062] FIG2 is a flowchart showing steps of a method for controlling a permanent magnet synchronous motor in a wide voltage range based on a current lookup table according to an embodiment of the present invention.

[0063] As shown in FIG2 , the current lookup table-based permanent magnet synchronous motor wide voltage range control method includes: step 101, obtaining a speed-torque two-dimensional lookup table at the rated bus voltage through a full-speed current calibration method; step 102, based on the lookup table, achieving wide voltage range control by multiplying a given speed by the ratio of the front and rear limiting voltages; step 103, performing friction torque compensation at different speeds and sampling delay compensation for the three-phase current.

[0064] In one example, obtaining a two-dimensional speed-torque lookup table at rated bus voltage using a full-speed current calibration method includes:

[0065] For the low-speed non-weakening magnetic area, the exhaustive current calibration method is used for calibration;

[0066] For current calibration in the high-speed field-weakening region, use a dynamometer to drag the motor speed to a speed greater than the turning speed, maintain a constant current amplitude, and change the current vector angle. Record the current vector angle value at which the bus voltage reaches the maximum and the current can follow. Test each current vector point with equal amplitude increase to find the corresponding torque angle. Finally, select the current amplitude corresponding to the maximum torque at the same speed. Increase the speed with equal amplitude and repeat the above process, recording the feedback torque and current setpoint.

[0067] Through the above current calibration process, the bench test calibrates the current vector amplitude and its weakening magnetic angle under different speed and torque conditions, and measures the data of all working points;

[0068] Fit the data measured at different speeds and output the dq axis current i in equal parts according to the torque d and i q The data table is obtained by linear interpolation fitting of the table data to obtain the final speed-torque two-dimensional lookup table.

[0069] In one example, an exhaustive current calibration method includes:

[0070] The dynamometer controls the motor under test to run at a constant speed under the base speed. The test bench host computer controls the motor stator current vector to start with an amplitude of 0A and a vector angle of 0°, and then changes the current vector with equal amplitude and angle in sequence and outputs it to the motor under test.

[0071] Record the actual motor output torque transmitted by CAN communication under different current vector settings until the output torque decreases. Record the maximum motor output torque and its corresponding current vector angle under this current amplitude.

[0072] Increase the given current vector amplitude by the same amount, start again from 0° and gradually increase the vector angle, and repeat the above process until the current vector amplitude reaches the maximum current value.

[0073] In one example, based on a lookup table, achieving wide voltage range control by multiplying a given speed by a ratio of front and rear limit voltages includes:

[0074] Establish a mathematical model of a three-phase interior permanent magnet synchronous motor;

[0075] In the synchronously rotating dq coordinate system, the amplitude of the stator voltage vector is calculated to obtain the limiting voltage of the lookup table;

[0076] Establish the voltage limit constraint equation, and then obtain the voltage limit ellipse equation and torque equation;

[0077] The input variables of the lookup table are determined to be the input speed n' and the input torque T e ', achieving wide voltage range control.

[0078] In one example, the mathematical model of a three-phase interior permanent magnet synchronous motor is:

[0079] Where u d 、u q is the d-axis and q-axis stator voltage component; i d 、i q are the d-axis and q-axis stator current components; ω e is the electrical angular velocity; R s is the stator resistance; L d , L q is the orthogonal axis inductance; ψ f is the magnetic flux amplitude of the rotor permanent magnet; T e is the electromagnetic torque; n p is the number of motor pole pairs; J is the motor moment of inertia; B is the viscous friction coefficient; T L is the load torque; ω r is the mechanical angular velocity.

[0080] In one example, the voltage limit constraint equation is:

[0081] Where U smax =kU dc , is the limiting voltage when using the table lookup method for control; k is the voltage coefficient, which represents the voltage margin left for the bus voltage.

[0082] In one example, the voltage limit ellipse equation is:

[0083] In one example, friction torque compensation includes:

[0084] According to the motion equation of the permanent magnet synchronous motor, the friction torque is analyzed and obtained

[0085] From the above formula, we can see that the friction torque T m =Bω r , which is proportional to the mechanical angular velocity;

[0086] The friction torque is obtained by the no-load torque test. When testing the motor to be tested, its three-phase cables are suspended in the air, and the motor is controlled by a test bench at a mechanical angular velocity ω r No-load operation is performed under

[0087] The no-load torque T at the corresponding speed is obtained through CAN communication feedback m , which is the friction torque, divided by ω r Obtain the viscous friction coefficient;

[0088] The actual torque transmitted back to the test bench host computer by CAN communication is T e -T m , the real torque is used as the input torque of the speed-torque two-dimensional table and recorded;

[0089] When wide range voltage control is performed, the given speed n * Different from the input speed n', when the motor is running in steady state, the actual torque does not match the load torque, which is:

[0090] in, Denoted as friction torque error T err ;

[0091] The given torque T output by the host computer e * Add the friction torque error T err , get the input torque T from the real input current lookup table e ', that is

[0092] In one example, the sampling delay compensation of the three-phase current includes:

[0093] The sampling circuit filter will introduce delay while suppressing high-frequency noise interference. The delay compensation should be performed according to the sampling circuit transfer function. The sampling filter transfer function H(s) is expressed as:

[0094] Where s is the Laplace operator.

[0095] Specifically, a wide-voltage-range control system for a permanent magnet synchronous motor based on a current lookup table (CLT) includes a test bench host computer, a dynamometer, a motor under test, a motor controller, a DC voltage source, a cooling system, and current, voltage, and temperature sensors. The control system also includes a wide-voltage-range control algorithm based on the current lookup table within the motor controller. The test bench host computer controls the DC voltage source to stabilize the DC bus voltage at a fixed value. The dynamometer controls the motor under test to operate at a given speed. The test bench host computer generates a desired calibration current command, which is transmitted to the motor controller via CAN communication to control the motor under test at different operating points. CAN communication transmits torque and DC bus voltage information back to the test bench host computer. The cooling system provides a cooling circuit for the motor and its controller.

[0096] This method mainly includes three steps:

[0097] Step 1: Obtain a two-dimensional speed-torque lookup table at rated bus voltage using a full-speed current calibration method. This invention uses a test bench to perform current calibration, which is less affected by motor parameters than calculation calibration.

[0098] Step 2: Based on the lookup table at the rated bus voltage, wide voltage range control is achieved by multiplying the given speed by the ratio of the front and rear limit voltages. This step is the core content of the present invention. It does not require multiple recalibration of the current lookup table at different DC bus voltages, which is simple to implement and requires little effort.

[0099] Step 3: Realize friction torque compensation and three-phase current sampling delay compensation at different speeds. After step 2, the given speed of the test bench is not the same as the input speed of the input current lookup table. Therefore, it is necessary to eliminate the impact of the difference between the given speed and the input speed on some links of the motor control system, which is mainly manifested in the compensation of friction torque and current sampling delay.

[0100] The DC bus voltage is maintained at the rated value by controlling the DC voltage source through the test bench host computer, and the speed-torque two-bit lookup table at the rated voltage is obtained by the full-speed range test bench calibration method described below.

[0101] An exhaustive current calibration method is used in the low-speed, non-field-weakening region. The dynamometer controls the motor under test at a constant speed below base speed. The test bench host computer controls the motor's stator current vector, starting with an amplitude of 0A and a vector angle of 0°. The current vector is then varied with varying amplitudes and angles, and output to the motor under test. The actual motor output torque, as transmitted via CAN communication, is recorded for each given current vector until the output torque decreases. The maximum motor output torque at that current amplitude and its corresponding current vector angle are then recorded. The given current vector amplitude is then increased by a constant amplitude, starting again from 0° and gradually increasing the vector angle. This process is repeated until the current vector amplitude reaches its maximum value.

[0102] To calibrate the current in the high-speed field-weakening region, use a dynamometer to drag the motor speed to slightly above the turning speed, maintaining a constant current amplitude while varying the current vector angle. Record the current vector angle value at which the bus voltage reaches maximum and the current can follow. Then, test each current vector point with increasing amplitude to find the corresponding torque angle. Finally, select the current amplitude corresponding to the maximum torque at the same speed. Repeat the process while increasing the speed with increasing amplitude, recording the feedback torque and current setpoint. When the current vector is high, observe the output power. Calibrate no further after reaching the power limit. Leave the torque angle corresponding to the speed blank. Once completed, organize the record table and fill in the blank value with the data from the last recorded point.

[0103] Through the above current calibration process, the bench test calibrates the current vector amplitude and its weak magnetic angle under different speed and torque conditions, and measures the data of all working points. The data measured at different speeds are fitted and the dq axis current i is output equally according to the torque. d and i q The data table is used to obtain the final speed-torque two-dimensional lookup table through linear interpolation fitting. In actual application, the current setting of the current working condition can be obtained by looking up the two-dimensional table.

[0104] Based on the lookup table under rated bus voltage, wide voltage range control is achieved by multiplying the given speed by the ratio of the front and rear limit voltages.

[0105] In order to better understand the operating law of permanent magnet synchronous motor, the mathematical model of three-phase interior permanent magnet synchronous motor is:

[0106] Where u d 、u q is the d-axis and q-axis stator voltage component; i d 、i q are the d-axis and q-axis stator current components; ω e is the electrical angular velocity; R s is the stator resistance; L d , L q is the orthogonal axis inductance; ψ f is the magnetic flux amplitude of the rotor permanent magnet; T e is the electromagnetic torque; n p is the number of motor pole pairs; J is the motor moment of inertia; B is the viscous friction coefficient; T L is the load torque; ω r is the mechanical angular velocity.

[0107] In the synchronously rotating dq coordinate system, ignoring the stator resistance voltage drop, the magnitude of the stator voltage vector is:

[0108] Substituting the above voltage equation into the voltage limit constraint, we can obtain the voltage limit constraint equation:

[0109] Where U smax =kU dc , is the limiting voltage when using the table lookup method for control; k is the voltage coefficient, which represents that the bus voltage has a certain voltage margin.

[0110] Divide both ends of the voltage limit constraint equation by L d , which can be expressed as the voltage limit ellipse equation of the dq axis current plane:

[0111] The torque equation of the permanent magnet synchronous motor is listed separately for analysis.

[0112] Since the current lookup table is calibrated on the bench, the permanent magnet flux amplitude ψ f The influence of can be ignored, then the electromagnetic torque T of the motor e Only the dq axis current i d 、i q The magnitude of the voltage limit ellipse and the limiting voltage U smax , electrical angular velocity ω e Related.

[0113] FIG3 shows a current diagram of changing a given rotation speed to achieve wide-range voltage control according to an embodiment of the present invention.

[0114] The variables of the input current lookup table are the input speed n' and input torque T after the test bench given instruction correction e ', where n = 30ω e / π. Figure 3 is used to analyze the relationship between the torque curve and the voltage limit ellipse, and to find a way to achieve wide-range voltage control.

[0115] Assuming that the rated DC bus voltage corresponding to the current lookup table pre-established in step 1 is U1, the current limiting voltage is U smax1 = kU1. When the motor runs at an electrical angular velocity ω1 higher than the base speed, the value on the right side of the voltage limit ellipse equation is Represents the size of the voltage limit ellipse. Under the same electrical angular velocity ω1, when the actual bus voltage is reduced to U2, the corresponding limiting voltage should be U smax2 = kU2, the value on the right side of the voltage limit ellipse equation is At this time, if the given torque input into the current lookup table is T1, that is, the current vector operating point corresponds to the T1 curve in the figure, which exceeds the actual voltage limit ellipse constraint, the motor will be out of control.

[0116] As can be seen from Figure 3, the size is The voltage limit ellipse contains the operational part of the torque T1 curve. It is easy to easily return the actual bus voltage in real time through CAN communication, multiply it by the voltage coefficient k, and get the actual limit voltage U smax2 , multiply the given electrical angular velocity ω1 by the ratio of the rated limiting voltage to the actual limiting voltage That is, ω1×k u , and then through n * =30ω1 / π to obtain the input speed n' of the current lookup table.

[0117] At this point, the voltage after the U smax2 The size of the corresponding voltage limit ellipse will be the same as the rated limiting voltage U smax1 The voltage limit ellipse under is equal in size. While the input torque T1 remains unchanged, from the electromagnetic torque equation analyzed above, the corresponding current vector operating point on the T1 curve also remains unchanged, i.e., n * 、U smax1 The current command will be equal to n * ×k u 、U smax2 If the current command is kept consistent, the motor output current will remain stable and the motor will not lose control.

[0118] According to the speed n given by the test bench host computer * Multiply by the voltage proportional coefficient k u , thus obtaining the input speed n' of the input current lookup table. It should be noted that due to the given speed n * Different from the input speed n', friction torque compensation and phase current sampling delay compensation are required for this purpose.

[0119] Realize friction torque compensation at different speeds:

[0120] The motion equation of the permanent magnet synchronous motor is listed separately to analyze the friction torque:

[0121] From the above formula, we can see that the friction torque T m =Bω r , which is proportional to the mechanical angular velocity; the friction torque needs to be obtained through the no-load torque test. When testing the motor to be tested, its three-phase cables are suspended in the air, and the test bench is used to control the motor at the mechanical angular velocity ω r The no-load torque T at the corresponding speed is obtained through CAN communication. m , which is the friction torque, divided by ω r Obtain the viscous friction coefficient.

[0122] The actual torque transmitted back to the test bench host computer by CAN communication is T e -T mIn the calibration process of step 1, the real torque is recorded as the input torque of the speed-torque two-dimensional table. However, when wide range voltage control is performed, the given speed n * Different from the input speed n', although the output electromagnetic torque is the same, the friction torque Bω corresponding to the given speed is r (n * ) and the friction torque Bω corresponding to the input speed r (n') is different, when the motor is running in steady state, the actual torque does not match the load torque, as shown in the following formula

[0123] in, Denoted as friction torque error T err .

[0124] In order to compensate for the given speed n * The friction torque error T caused by the difference between the input speed n' err , the given torque T output by the host computer needs to be e * Add the friction torque error T err Get the input torque T from the real input current lookup table e ',Right now

[0125] FIG4 shows a schematic diagram of a phase current sampling and filtering circuit according to an embodiment of the present invention.

[0126] Realize phase current sampling delay compensation at different speeds:

[0127] The motor drive control system requires current sampling from various circuits, including DC and phase currents. This invention utilizes a housing-mounted current sensor that passes through a copper busbar. Figure 4 shows the phase current sampling and filtering circuit. The current sensor output signal undergoes hardware filtering through a two-order Butterworth active filter. This filtering of the feedback phase current suppresses high-frequency noise in the current sampling signal, particularly near the switching frequency, thereby reducing noise interference and improving sampling accuracy.

[0128] However, while the sampling circuit filter suppresses high-frequency noise interference, it also introduces a certain delay, especially when the permanent magnet synchronous motor is under wide voltage and wide speed range field weakening control operation. The delay compensation should be performed according to the sampling circuit transfer function. The sampling filter transfer function H(s) used in the present invention is expressed as

[0129] Where s is the Laplace operator.

[0130] FIG5 shows a Bode diagram of a transfer function of a current sampling filter circuit according to an embodiment of the present invention.

[0131] Based on the transfer function established with the sampling circuit's component parameters, a Bode plot of the sampling filter transfer function H(s) was plotted using Matlab, as shown in Figure 5. Analyzing the delay introduced by the sampling filter in Figure 5 reveals that the actual sampling circuit has a very high bandwidth, with a stable low-frequency phase shift of 1.15 degrees. Therefore, for full-speed control of the permanent magnet synchronous motor at rated bus voltage (not approaching the speed limit), phase current sampling delay does not require compensation and can be set to zero.

[0132] FIG6 is a schematic diagram showing the influence of rotor angle deviation on dq axis currents according to an embodiment of the present invention.

[0133] For the wide-range voltage control proposed in this invention, it's still necessary to analyze the compensation principle for phase current sampling delay. The motor's dq-axis currents undergo a Park transform based on the sampled phase currents and the rotor electrical angle. In the Park transform, current and position acquisition should be performed synchronously. However, due to the filtering time delay in phase current sampling, current and position sampling can occur asynchronously, resulting in the current signal lagging behind the angle signal. This directly translates to an angle error in the Park transform, as shown in Figure 6.

[0134] It can be seen intuitively from Figure 6 that when the rotor electrical angle required for Park transformation has an error electrical angle θ due to the current sampling filter delay, the dq axis feedback current i d '、i q 'With the actual current i d 、i q The difference is large, and the rotor position error caused by the electrical angle leading current needs to be compensated, that is,

[0135] Where, is the corrected electrical angle after error electrical angle compensation; θ e The actual electrical angle returned by the resolver encoder.

[0136] The calculation of the error compensation electrical angle θ adopts the classic calculation method, which is proportional to the electrical angular velocity of the motor, that is, θ=mn * ; m is the phase current delay compensation coefficient, which can be determined based on the engineer's experience.

[0137] When the motor runs close to the limit speed; or when the bus voltage changes greatly, the given speed n * There will be a large gap between the input speed n', which is even equivalent to the motor running close to the limit speed. At this time, the error electrical angle θ can no longer be ignored. It is necessary to add the above-mentioned current error compensation link and set the given speed n* Instead of the current lookup table, the speed n' is input as the input signal of the θ calculation module.

[0138] The present invention obtains ω□T under a certain fixed bus voltage. e After the two-dimensional current lookup table is completed, there is no need to use bench calibration or calculation calibration to obtain the U under different bus voltages. dc □ω□T e The three-dimensional current lookup table can simply implement adaptive variable voltage permanent magnet synchronous motor lookup control by multiplying the given speed of the input current lookup table by the variable voltage coefficient, taking into account friction torque compensation and current sampling delay compensation.

[0139] Example 2

[0140] An embodiment of the present disclosure provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table is implemented.

[0141] According to an embodiment of the present disclosure, a computer-readable storage medium stores non-transitory computer-readable instructions, which, when executed by a processor, execute all or part of the steps of the aforementioned methods of the embodiments of the present disclosure.

[0142] The above-mentioned computer-readable storage media include, but are not limited to, optical storage media (e.g., CD-ROMs and DVDs), magneto-optical storage media (e.g., MOs), magnetic storage media (e.g., magnetic tapes or mobile hard disks), media with built-in rewritable non-volatile memory (e.g., memory cards), and media with built-in ROM (e.g., ROM cartridges).

[0143] Those skilled in the art should understand that the above description of the embodiments of the present invention is only for the purpose of illustrative purposes only to illustrate the beneficial effects of the embodiments of the present invention, and is not intended to limit the embodiments of the present invention to any given examples.

[0144] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table, characterized in that: include: The speed-torque two-dimensional lookup table under rated bus voltage is obtained by full-speed current calibration method. Based on the lookup table, wide voltage range control is achieved by multiplying a given speed by the ratio of the front and rear limit voltages; Perform friction torque compensation at different speeds and sampling delay compensation of three-phase current.

2. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 1, wherein: The speed-torque two-dimensional lookup table under rated bus voltage is obtained by the full-speed current calibration method, including: For the low-speed non-weakening magnetic area, the exhaustive current calibration method is used for calibration; For current calibration in the high-speed field-weakening region, use a dynamometer to drag the motor speed to a speed greater than the turning speed, maintain a constant current amplitude, and change the current vector angle. Record the current vector angle value at which the bus voltage reaches the maximum and the current can follow. Test each current vector point with equal amplitude increase to find the corresponding torque angle. Finally, select the current amplitude corresponding to the maximum torque at the same speed. Increase the speed with equal amplitude and repeat the above process, recording the feedback torque and current setpoint. Through the above current calibration process, the bench test calibrates the current vector amplitude and its weakening magnetic angle under different speed and torque conditions, and measures the data of all working points; Fit the data measured at different speeds and output the dq axis current i in equal parts according to the torque d and i q The data table is obtained by linear interpolation fitting of the table data to obtain the final speed-torque two-dimensional lookup table.

3. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 2, wherein: Exhaustive current calibration methods include: The dynamometer controls the motor to run at a constant speed under the base speed, and the test bench host computer The motor stator current vector is controlled to start with an amplitude of 0A and a vector angle of 0°, and the current vector is changed in equal amplitudes and angles and output to the motor under test; Record the actual motor output torque transmitted by CAN communication under different current vector settings until the output torque decreases. Record the maximum motor output torque and its corresponding current vector angle under this current amplitude. Increase the given current vector amplitude by the same amount, start again from 0° and gradually increase the vector angle, and repeat the above process until the current vector amplitude reaches the maximum current value.

4. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 1, wherein: Based on the lookup table, achieving wide voltage range control by multiplying a given speed by the ratio of the front and rear limit voltages includes: Establish a mathematical model of a three-phase interior permanent magnet synchronous motor; In a synchronously rotating dq coordinate system, calculating the amplitude of the stator voltage vector, thereby obtaining the limiting voltage of the lookup table; Establish the voltage limit constraint equation, and then obtain the voltage limit ellipse equation and torque equation; The input variables of the lookup table are determined to be the input speed n' and the input torque T e ', achieving wide voltage range control.

5. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 4, wherein: The mathematical model of the three-phase interior permanent magnet synchronous motor is: Where u d 、u q is the d-axis and q-axis stator voltage component; i d 、i q are the d-axis and q-axis stator current components; ω e is the electrical angular velocity; R s is the stator resistance; L d , L q is the orthogonal axis inductance; ψ f is the magnetic flux amplitude of the rotor permanent magnet; T e is the electromagnetic torque; n p is the number of motor pole pairs; J is the motor moment of inertia; B is the viscous friction coefficient; T L is the load torque; ω r is the mechanical angular velocity.

6. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 4, wherein: The voltage limit constraint equation is: Where U smax =kU dc , is the limiting voltage when using the table lookup method for control; k is the voltage coefficient, which represents the voltage margin left for the bus voltage.

7. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 4, wherein: The voltage limit ellipse equation is:

8. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 1, wherein: The friction torque compensation includes: According to the motion equation of the permanent magnet synchronous motor, the friction torque is analyzed and obtained From the above formula, we can see that the friction torque T m =Bω r , which is proportional to the mechanical angular velocity; The friction torque is obtained by the no-load torque test. When testing the motor to be tested, its three-phase cables are suspended in the air, and the motor is controlled by a test bench at a mechanical angular velocity ω r No-load operation is performed under The no-load torque T at the corresponding speed is obtained through CAN communication feedback m , that is, the friction torque, Divide it by ω r Obtain the viscous friction coefficient; The actual torque transmitted back to the test bench host computer by CAN communication is T e -T m , the real torque is used as the input torque of the speed-torque two-dimensional table and recorded; When wide range voltage control is performed, the given speed n * Different from the input speed n', when the motor is running in steady state, the actual torque does not match the load torque, which is: in, Denoted as friction torque error T err ; The given torque T output by the host computer e * Add the friction torque error T err , get the input torque T from the real input current lookup table e ', that is 9. The method for controlling a permanent magnet synchronous motor with a wide voltage range based on a current lookup table according to claim 1, wherein: The sampling delay compensation of three-phase current includes: The sampling circuit filter will introduce delay while suppressing high-frequency noise interference. The delay compensation should be performed according to the sampling circuit transfer function. The sampling filter transfer function H(s) is expressed as: Where s is the Laplace operator.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the permanent magnet synchronous motor wide voltage range control method based on a current lookup table according to any one of claims 1 to 9.

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