A driving method and driving device for a two-degree-of-freedom permanent magnet synchronous motor

Abstract

This invention discloses a driving method and driving device for a two-degree-of-freedom permanent magnet synchronous motor. d‑q The current command value of the shaft is used by the first coordinate transformation module to obtain the command value of the three-phase stator current; then it is compared with the actual value of the three-phase current fed back by sampling, and the feedback term of the three-phase command voltage is obtained through the PI regulator module; derivation d‑q The recursive formula for the change of shaft current with the control cycle is obtained by transforming the three-phase voltage fed back from the motor through the third coordinate transformation module. d‑q The axis voltage is obtained by transforming the feedback three-phase current through the second coordinate transformation module. d‑q shaft current and d‑q The shaft current command value is substituted into the recursive formula to obtain the three-phase command voltage feedforward term. The feedforward term is added to the feedback term to obtain the three-phase voltage command value, which is then input into the switching function module. The power devices in the controlled three-level inverter bridge module are determined according to the positive and negative values ​​of each command value. The required PWM wave is obtained by comparing it with the carrier wave, and finally the AC power is output to the three-phase permanent magnet synchronous motor.

Description

Technical Field

[0001] This invention belongs to the field of three-phase AC motor control technology, specifically relating to a two-degree-of-freedom permanent magnet synchronous motor driving method and driving device. Background Technology

[0002] Currently, direct torque control (DTC) and vector control are the two most commonly used methods in the field of high-performance AC variable frequency speed regulation. DTC uses space vector analysis to directly calculate and control the flux linkage space vector and torque in the stator coordinate system, which simplifies the actual control system and improves the system's fast response capability. However, it is accompanied by defects such as poor robustness and large torque ripple.

[0003] Therefore, direct torque control is not commonly found in high-performance servo control systems. Vector control, also known as field-oriented control, establishes a rotating coordinate system by using the direction of the rotating magnetic field vector as the reference direction of the coordinate axes. Motor current vectors and other parameters are represented within this rotating coordinate system. Its fundamental characteristic is that, in the rotating coordinate system, the stator current of a three-phase motor can be decomposed into independent excitation and torque components for separate control. Thus, by reconstructing the AC motor mathematical model into a separately excited DC motor form through vector transformation, the decoupling of motor torque and motor flux is achieved, thereby enabling individual control of instantaneous torque.

[0004] The general steps of vector control are: sector determination, vector action time calculation, vector switching time calculation, and finally, generation of pulse width modulation (PWM) switching signal. However, to achieve higher voltage resolution, when the driver has a three-level structure as shown in Figure 1, the number of sectors in the vector control process increases from 6 to 24, as shown in Figure 2. This significantly increases the computational load required for sector determination and PWM generation, making the control method more complex, extending the calculation time, and reducing the control cycle. Since high-performance servo systems require high speed, high precision, high stability, and a wide speed range, a control algorithm adapted to three-level conditions is needed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a two-degree-of-freedom permanent magnet synchronous motor driving method and driving device to address the shortcomings of the prior art, thereby solving the technical problem that the control algorithm of a three-level motor is complex, the calculation time is long, and the control cycle is affected.

[0006] The present invention adopts the following technical solution:

[0007] A method for driving a two-degree-of-freedom permanent magnet synchronous motor, including

[0008] S1. Sample the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor;

[0009] S2, using the inverse Park transform and the inverse Clark transform to... d-q The shaft current command value is converted into a three-phase current command value, and then the difference is calculated with the actual three-phase current value obtained in step S1 to obtain the error term;

[0010] S3. The error term obtained in step S2 is used by the PI controller to obtain the feedback term of the three-phase voltage command value.

[0011] S4. Obtain information about the electromagnetic model of the motor. d-q The recursive formula for shaft current is based on... d-q The axis current recursive formula predicts the current prediction value after two control cycles required for the command current to be calculated and modulated.

[0012] S5. Set the predicted current value obtained in step S4 to be equal to the commanded current to obtain the value required for calculation. d-q Shaft voltage command value feedforward term;

[0013] S6. The result obtained in step S5 d-q The feedforward term of the shaft voltage command value undergoes Park inverse transformation and Clark inverse transformation, and is added to the feedback term of the three-phase voltage command value obtained in step S3 to obtain the three-phase voltage command value.

[0014] S7. The result obtained in step S5 d-q The modulus of the feedforward term of the shaft voltage command value is calculated. When the modulus is greater than half of the DC bus voltage, it is considered an overload. The value is then scaled proportionally to obtain the voltage within the modulation range.

[0015] S8. Calculate the pulse width modulation duty cycle of each phase of the motor based on the magnitude and sign of the three-phase voltage command value obtained in step S6, and generate a PWM wave based on the pulse width modulation duty cycle.

[0016] S9. The PWM wave generated in step S8 is output to the three-level inverter bridge module to form the required driving voltage, which is applied to the motor to form the motor current.

[0017] Preferably, in step S2, the motor is... d-q Shaft command current Perform coordinate transformation Obtain the three-phase command current of the motor ; and combine it with the motor feedback three-phase current The difference is used to obtain the current error term. .

[0018] Preferably, in step S3, the three-phase voltage command value feedback item for:

[0019]

[0020] in, This is the proportionality coefficient. The integral coefficient is... These are frequency domain characteristic parameters. The three-phase command current and the three-phase feedback current of the motor The current error term obtained by subtraction.

[0021] Preferably, in step S4, the predicted current value for:

[0022]

[0023] in, The three-phase output voltage of the inverter, after passing through Park and Clark converters, is then... d-q The result obtained after removing the coupling term from the axis voltage. for, for, for d-q The value of the shaft current in the k-th period.

[0024] Preferably, the electromagnetic model of the motor is used to obtain information about... d-q Recurrence relation for shaft current:

[0025]

[0026] Preferably, and They are respectively:

[0027]

[0028]

[0029] in, For the direct-axis inductance of the motor, This refers to the stator phase resistance of the motor. For motor control cycle, This is the quadrature axis inductance of the motor.

[0030] Preferably, in step S5, the... d-q Substitute the shaft current command value obtained in step S4 In the middle, calculate according to the formula And add it to the previously removed coupling terms to obtain d-q Feedforward term in shaft voltage command value.

[0031] Preferably, in step S8, the positive or negative value of the generated three-phase voltage command is first determined, and the corresponding control power device is selected according to the positive or negative value;

[0032] The absolute value of the three-phase voltage command value is then generated, and the absolute value is compared with the carrier wave whose amplitude is equal to half of the DC bus voltage to generate the PWM wave for controlling the power device.

[0033] By using three-phase voltage command values ​​and carrier waves to generate and control the PWM waves of the 12 power devices in the three phases of the inverter, different switching states are achieved in the three-phase outputs, thereby controlling the actual values ​​of the three-phase stator currents of the motor. Trace command value .

[0034] Another technical solution of the present invention is a two-degree-of-freedom permanent magnet synchronous motor drive device, comprising:

[0035] The motor electrical angle detection module is used to sample the rotor electrical angle of a three-phase AC permanent magnet synchronous motor and feed back the actual value of the three-phase current to the first coordinate transformation module, the second coordinate transformation module and the third coordinate transformation module;

[0036] The first coordinate transformation module is used to obtain coordinates based on settings or the outer loop servo controller. d-q The commanded value of the shaft current is used to obtain the commanded value of the three-phase stator current, and the commanded value of the three-phase stator current is compared with the actual value of the three-phase current fed back by sampling to obtain the error term;

[0037] The PI regulator module is used to calculate the three-phase voltage command value feedback term from the error term;

[0038] The feedforward calculation module is used to compensate for the error caused by the two-cycle lag between the current command value and the actual output voltage of the inverter to the permanent magnet synchronous motor, and at the same time to prevent the voltage command value from being overloaded.

[0039] The second coordinate transformation module is used to convert the obtained actual values ​​of the three-phase current into... d-q The actual value of the shaft current is used for calculations in the feedforward calculation module.

[0040] The third coordinate transformation module is used to convert the actual three-phase voltage values ​​output by the inverter into... d-q The actual value of the shaft voltage is used for calculation by the feedforward calculation module;

[0041] The PWM generation module is used to generate PWM waves to control the power devices in the inverter bridge.

[0042] The inverter bridge module switches the power devices according to the PWM wave to generate AC power, which is then transmitted to the permanent magnet synchronous motor.

[0043] Preferably, the power devices for each phase of the permanent magnet synchronous motor are IGBTs or MOSEFTs.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] A two-degree-of-freedom permanent magnet synchronous motor drive method utilizes a PI regulator to compensate for disturbances and a delay feedforward module to improve the dynamic tracking characteristics of the current. Simultaneously, because the three-level output level is... This allows the method to generate PWM switching signals for each phase based on the duty cycle of the upper and lower half-bridges, according to the positive and negative values ​​of the output voltage. Compared to traditional space vector pulse width modulation (SVPWM), this method eliminates the need for sector determination and vector action time calculation, significantly reducing computational load. Therefore, this method balances dynamic characteristics and disturbance rejection, featuring simple structure, high bandwidth, and strong robustness.

[0046] Furthermore, to correct the current following error, PI control is applied to the three-phase current and the motor. d-q Shaft command current Perform coordinate transformation to obtain the three-phase command current of the motor. The current error term is obtained by subtracting this from the three-phase feedback voltage from the motor. .

[0047] Furthermore, to ensure the control algorithm has a certain degree of anti-interference capability, feedback control is required to obtain feedback terms from the three-phase voltage command values. .

[0048] Furthermore, to compensate for the error caused by the two control cycles from the command current to the actual output voltage during motor control, feedforward control is performed on the command current to obtain the current value after two control cycles. .

[0049] Furthermore, in order to obtain d-q The value of the shaft current after two cycles needs to be obtained from the motor current relationship based on the motor electromagnetic model, and then the relationship needs to be discretized to obtain the value. d-q The value of shaft current after one control cycle .

[0050] Furthermore, to compensate for the error caused by the two control cycles from the command current to the actual output voltage during motor control, the following measures will be implemented: d-q Substitute the shaft current command value into This ensures that the final output can follow the input command value required by the inverter. d-q shaft voltage value At the same time, adding the coupling terms that were previously removed for easier calculation, we get... d-q Shaft voltage command feedforward term .

[0051] Furthermore, because this method can output using three levels... The circuit structure is configured as follows: To facilitate power device control, the sign of the output voltage command value determines the controlled power device. Simultaneously, to simplify duty cycle calculation, the absolute values ​​of the three-phase voltage command values ​​are taken. These absolute values ​​are then compared with a carrier wave whose amplitude is equal to half the DC bus voltage to generate the PWM wave controlling the power devices. This ensures the final actual value of the stator three-phase current... Can track instruction values The PWM waves corresponding to the 12 power devices in the three phases need to be input to the inverter bridge.

[0052] In summary, the three-phase stator current value in this invention can quickly track the command value, and compared with the traditional vector control drive method of motor, the response time is significantly shortened.

[0053] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the following description of the relative embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 shows an existing three-level structure driver, where (a) is one type of three-level structure driver and (b) is another type of three-level structure driver;

[0056] Figure 2 is a vector control diagram;

[0057] Figure 3 This is a block diagram illustrating the principle of two-degree-of-freedom three-level SPWM motor drive control using feedback and feedforward in this invention.

[0058] Figure 4 For the motor in this invention under simulation environment d-q Step response diagram of shaft current;

[0059] Figure 5 For motors in traditional SPWM control under simulation environment d-q Axis current step response diagram.

[0060] The module includes: 1. Motor electrical angle detection module; 2. First coordinate transformation module; 3. PI regulator module; 4. Feedforward calculation module; 5. Second coordinate transformation module; 6. Third coordinate transformation module; 7. PWM generation module; 8. Inverter bridge module. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "one side," "one end," and "one side," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0063] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0064] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0065] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0066] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0067] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0068] This invention provides a two-degree-of-freedom permanent magnet synchronous motor driving method and driving device, which utilizes a PI regulator to compensate for disturbances and a delay-inducing feedforward calculation module to improve the dynamic tracking characteristics of the current. Simultaneously, because the three-level output level is... 0 allows it to utilize either the positive or negative output voltage. and 0 or The duty cycle is calculated using zero, and PWM switching signals for each phase are generated, greatly reducing the computational load. Therefore, the method of this invention balances dynamic characteristics and disturbance rejection characteristics, and features simple structure, high bandwidth, and strong robustness.

[0069] This invention discloses a two-degree-of-freedom permanent magnet synchronous motor driving method, comprising the following steps:

[0070] S1. Sample the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor;

[0071] The actual three-phase stator current is obtained by sampling the three-phase stator current of the motor. The motor rotor electrical angle is obtained by sampling the motor encoder through the motor speed and position detection module 1.

[0072] S2, using the inverse Park transform and the inverse Clark transform to... d-q Shaft current command value and The error term is obtained by calculating the difference between the three-phase current command value and the motor feedback three-phase current value.

[0073] When the controlled motor is a surface-mounted permanent magnet synchronous motor, let The first coordinate transformation module 2 commands the motor q-axis current value. and d-axis command current Perform the Park inverse transformation using the rotor electrical angle obtained in step S1. The command values ​​of the three-phase stator current of the motor are obtained. The details are as follows:

[0074]

[0075] The three-phase command current of the motor Feedback three-phase current with the motor The difference is used to obtain the current error term, as follows:

[0076]

[0077] S3. The error term is processed by the PI controller to obtain the three-phase voltage command value feedback term;

[0078] Will The motor stator voltage command value feedback item is obtained through PI regulator module 3. :

[0079]

[0080] S4. Obtain information about the electromagnetic model of the motor. d-q The axis current recursive formula is used to predict the current prediction value after two control cycles required for the command current to be calculated and modulated.

[0081] Based on the electromagnetic model of the motor, we obtain the following... d-q Recurrence relation for shaft current:

[0082]

[0083] in, ,

[0084] Based on the recursive formula, the command current is predicted. After calculation and modulation into the PWM wave required to drive the power device for two control cycles, the predicted value is obtained. :

[0085]

[0086] in, The three-phase output voltage of the inverter, after passing through Park and Clark converters, is then... d-q The result obtained after removing the coupling term from the axis voltage.

[0087] S5. Set the predicted value to be equal to the command current, and then calculate the value required for the calculation. d-q Shaft voltage command value feedforward term ;

[0088] Will d-q Substitute the shaft current command value obtained in step S4 In the middle, calculate according to the formula And add it to the previously removed coupling terms to obtain d-q Feedforward term in shaft voltage command value .

[0089]

[0090] in, The electric angular velocity of the motor. Permanent magnet flux linkage, feeding back the motor stator voltage command value. Feedforward term of motor stator voltage command value The summation yields the motor stator voltage command value. .

[0091] S6. The result obtained after step S5 d-q The feedforward term of the shaft voltage command value is subjected to Park inverse transform and Clark inverse transform to obtain the feedforward term of the motor three-phase voltage command value. and combine it with feedback items The three-phase voltage command value is obtained by adding them together. ;

[0092] S7, to d-q The modulus of the feedforward term of the shaft voltage command value is calculated and compared with half of the DC bus voltage value. If it exceeds the value, it is scaled proportionally.

[0093] right Modulus: If If the load is greater than half of the bus voltage, it is considered an overload; calculate the overload ratio. ,make If the voltage is less than or equal to half of the bus voltage, it is considered not to be overloaded and no action is taken.

[0094] S8. Calculate the pulse width modulation duty cycle of each phase of the motor based on the magnitude and sign of the voltage command value of each phase, and generate PWM waves.

[0095] First, determine the sign of the generated three-phase voltage command value, and then select the corresponding control power device based on the sign.

[0096] The absolute value of the three-phase voltage command value is then generated, and the absolute value is compared with the carrier wave whose amplitude is equal to half of the DC bus voltage to generate the PWM wave for controlling the power device.

[0097] Will Output to PWM module 7, according to The sign of each phase voltage command value determines the controlled power device. Simultaneously, a triangular carrier wave is set, with the carrier frequency being the control frequency and the carrier amplitude being half the DC bus voltage. The carrier wave is then compared with... The absolute values ​​of the voltage command values ​​of each phase are compared to output the PWM wave for controlling each power device.

[0098] S9. The generated PWM wave is output to the three-level inverter bridge module 8 to form the required drive voltage, which is applied to the motor to form the motor current.

[0099] Please see Figure 3 This invention discloses a two-degree-of-freedom permanent magnet synchronous motor drive device. It utilizes three-phase voltage command values ​​and carrier wave generation to control the PWM waves of the 12 power devices in the three phases of the inverter, causing different switching states in the three-phase outputs and thus controlling the actual value of the three-phase stator current of the motor. Trace command value It includes a motor electrical angle detection module 1, a first coordinate transformation module 2, a PI regulator module 3, a feedforward calculation module 4, a second coordinate transformation module 5, a third coordinate transformation module 6, a PWM generation module 7, and an inverter bridge module 8.

[0100] The output of the permanent magnet synchronous motor is divided into three paths. One path is split into two paths via the PI regulator module 3. One path is connected to the third coordinate transformation module 6 and the feedforward calculation module 4. The other path is connected to the control terminal of the permanent magnet synchronous motor via the PWM generation module 7 and the inverter bridge module 8.

[0101] The second path passes through the second coordinate transformation module 5 and the feedforward calculation module 4 in sequence, and then splits into two paths. One path connects to the third coordinate transformation module 6 and the feedforward calculation module 4, and the other path passes through the PWM generation module 7 and the inverter bridge module 8 to the control terminal of the permanent magnet synchronous motor.

[0102] The third path is split into three paths via the motor electrical angle detection module 1. The first path is split into two paths via the first coordinate transformation module 2 and the PI regulator module 3. One path is connected to the third coordinate transformation module 6 and the feedforward calculation module 4, and the other path is connected to the control terminal of the permanent magnet synchronous motor via the PWM generation module 7 and the inverter bridge module 8.

[0103] The second path connects to the third coordinate transformation module 6 and the feedforward calculation module 4. The other path connects to the second coordinate transformation module 5 and the feedforward calculation module 4, then splits into two paths: one path connects to the third coordinate transformation module 6 and the feedforward calculation module 4, and the other path connects to the control terminal of the permanent magnet synchronous motor via the PWM generation module 7 and the inverter bridge module 8.

[0104] Among them, the motor electrical angle detection module 1 is used to sample the rotor electrical angle of the three-phase AC permanent magnet synchronous motor and feed back the actual value of the three-phase current to the first coordinate transformation module 2, the second coordinate transformation module 5 and the third coordinate transformation module 6.

[0105] The first coordinate transformation module 2 is used to obtain coordinates based on settings or the outer loop servo controller. The command value of the shaft current is obtained, and then the command value of the three-phase stator current is obtained. The command value of the three-phase stator current is compared with the actual value of the three-phase current fed back by sampling to obtain the error term.

[0106] PI regulator module 3 is used to calculate the error term to obtain the feedback term of the three-phase voltage command value;

[0107] Feedforward calculation module 4 is used to compensate for the error caused by the two-cycle lag between the current command value and the actual output voltage of the inverter to the permanent magnet synchronous motor, and at the same time to prevent the voltage command value from being overloaded.

[0108] The second coordinate transformation module 5 is used to convert the obtained actual values ​​of the three-phase current into... d-q The actual value of the shaft current is used for calculation in feedforward calculation module 4;

[0109] The third coordinate transformation module 6 is used to convert the actual values ​​of the three-phase voltage output by the inverter into... d-q The actual value of the shaft voltage is used for calculation in feedforward calculation module 4;

[0110] PWM generation module 7 is used to generate PWM waves to control each power device in the inverter bridge;

[0111] Inverter bridge module 8 uses PWM waves to switch power devices to generate AC power, which is then transmitted to the permanent magnet synchronous motor.

[0112] The power devices for each phase of the permanent magnet synchronous motor are IGBTs or MOSEFTs.

[0113] The working principle of the two-degree-of-freedom permanent magnet synchronous motor drive device of the present invention is as follows:

[0114] Set or obtained from the outer loop servo controller d-q Commanded value of shaft current. d shaft and q The current command value of the shaft is then processed by the first coordinate transformation module 2 to obtain the command value of the three-phase stator current;

[0115] The command value of the three-phase stator current obtained through the first coordinate transformation module 2 is compared with the actual value of the three-phase current sampled back, and the feedback term of the three-phase command voltage is obtained through the PI regulator module 3.

[0116] Based on the electromagnetic equations of the electric motor, the following is derived: d shaft and q The recursive formula for the change of shaft current with the control cycle is obtained by processing the three-phase voltage fed back from the motor through the third coordinate transformation module 6. d shaft and q The shaft voltage is obtained by passing the feedback three-phase current through the second coordinate transformation module 5. d shaft and q shaft current and d shaft and q Substituting the shaft current command value into the recursive formula, we finally obtain the three-phase command voltage feedforward term.

[0117] The feedforward term and the feedback term are added to obtain the three-phase voltage command value. The command value is input to the PWM generation module 7. The power device in the controlled inverter bridge module 8 is determined according to the positive and negative values ​​of each command value. The required PWM wave is obtained by comparing it with the carrier wave. Finally, it is input to the inverter bridge module 8 to obtain AC power output to the three-phase permanent magnet synchronous motor.

[0118] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0119] Example 1

[0120] The embodiments of the present invention will be described below based on the SimuLink simulation platform.

[0121] Please see d-q The feedback plus feedforward two-degree-of-freedom permanent magnet synchronous motor drive method of this embodiment includes the following steps:

[0122] Step 1: Initialize the motor parameters according to the motor nameplate to complete the setting of motor parameters in motor drive control;

[0123] Step 2: Analyze the three-phase stator current of the motor. Sampling is performed, and the rotor angle position of the motor is detected by the motor speed and position detection module 1, and multiplied by the number of motor pole pairs to obtain the rotor electrical angle. ;

[0124] Step 3: Set the command current value for the motor's q-axis. In this embodiment, a model simulation of a surface-mounted three-phase AC synchronous motor is used, therefore the current is set to... This allows us to obtain the command current values ​​for the motor's d-axis and q-axis, respectively. and ;

[0125] Step 4: After passing through the first coordinate transformation module 2, the command current value of the motor's q-axis is... and d-axis command current Perform coordinate transformation The command values ​​of the three-phase stator current of the motor are obtained. Specifically, it is expressed as:

[0126]

[0127] Among them, the command value of the three-phase stator current of the motor Represented as:

[0128]

[0129] in, , , These are the three-phase current command values ​​for phases a, b, and c, respectively, and their coordinate transformations. It is represented as follows, The electrical angle of the motor rotor obtained in step 2:

[0130]

[0131] Among them, motor Figure 3 Shaft current command value Represented as:

[0132]

[0133] Step 5: The three-phase stator current of the motor sampled in Step 1 is... Compared with the motor stator three-phase current command value obtained in step 3 The resulting deviation terms are as follows:

[0134]

[0135] Step 6, The motor stator voltage command value feedback item is obtained through PI regulator module 3. , The calculation formula is as follows:

[0136]

[0137] Step 7, obtain the information about the electromagnetic model of the motor. d-q Recurrence relation for shaft current:

[0138]

[0139] in, , ;

[0140] Based on the recursive formula, the command current is predicted. After calculation and modulation into the PWM wave required to drive the power device for two control cycles, the predicted value is obtained. :

[0141]

[0142] in, The three-phase voltage output from the inverter is processed by the third coordinate transformation module 6. Later obtained d-q The result obtained after removing coupling terms from the axis voltage, coordinate transformation It is expressed as follows:

[0143]

[0144] Step 8, d-q Shaft current command value Substitute In the middle, calculate according to the formula And add it to the previously removed coupling terms to obtain d-q Feedforward term in shaft voltage command value The specific formula is as follows:

[0145]

[0146] in, The electric angular velocity of the motor. For permanent magnet flux linkage;

[0147] Represented as:

[0148]

[0149] Represented as:

[0150]

[0151] Next, the motor stator voltage command value feedback item Feedforward term of motor stator voltage command value The summation yields the motor stator voltage command value. .

[0152] Step 9, for Find the modulus, if If the load is greater than half of the bus voltage, it is considered an overload; calculate the overload ratio. ,make If the voltage is less than or equal to half of the bus voltage, it is considered not to be overloaded and no action is taken.

[0153] Step 10, Output to PWM module 7, according to The sign of the voltage command value for each phase determines the controlled power device. Simultaneously, a triangular carrier wave is set, with its frequency being the control frequency and its amplitude being half the DC bus voltage. Let the carrier value be P, and then the carrier wave is... Compare the absolute values ​​of the voltage command values ​​for each phase. Taking phase a as an example, if... If the value is less than P, output "0"; if the value is less than P, output "0". If the value is greater than P, then output "1" to obtain the PWM wave for controlling each power device;

[0154] Step 11: Output the PWM wave to the inverter bridge module 8 to control the switching state of the power devices therein to convert the DC bus voltage into the AC voltage required to drive the motor.

[0155] like d-q The image shows the motor in this invention under a simulation environment. Figure 3 Step response diagram of shaft current. (e.g.) d-q The image shows the motor in traditional SPWM control under a simulation environment. Figure 4 Axis current step response diagram.

[0156] As can be seen from the above, the actual current value in this invention can quickly track the command value, and the response time is significantly shortened compared to the traditional vector control driving method of motors.

[0157] In summary, this invention provides a two-degree-of-freedom permanent magnet synchronous motor driving method and driving device, which comprehensively utilizes feedback and feedforward control methods and combines a three-level driving device to implement current control of the permanent magnet synchronous motor. Firstly, this paper uses the difference between the actual values ​​of each phase current of the three-phase motor and the command values ​​obtained after transformation of the command current to suppress system disturbances through PI control. Simultaneously, through the derivation of the motor's electromagnetic model, it obtains... d-q d-q The recursive formula for shaft current is correlated with voltage to achieve feedforward control of the motor, improving the dynamic tracking characteristics of the motor current. Simultaneously, the PWM method required to control the power devices is sinusoidal pulse width modulation (SPWM), which significantly reduces the computational load, increases the control frequency, and improves the dynamic tracking characteristics of each phase current. Therefore, this invention overcomes the technical shortcomings of complex calculations in existing traditional motor vector control. The motor drive method of this invention has the advantages of good anti-interference performance and good dynamic tracking characteristics.

[0158] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for driving a two-degree-of-freedom permanent magnet synchronous motor, characterized in that, include S1. Sample the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor; S2, using the inverse Park transform and the inverse Clark transform to... dq The shaft current command value is converted into a three-phase current command value, and then the difference is calculated with the actual three-phase current value obtained in step S1 to obtain the error term; S3. The error term obtained in step S2 is used by the PI controller to obtain the feedback term of the three-phase voltage command value. S4. Obtain information about the electromagnetic model of the motor. dq The recursive formula for shaft current is based on... dq The recursive formula for shaft current predicts the current prediction value after two control cycles required for calculation and modulation of the command current. The relationship between shaft current and current is then derived from the electromagnetic model of the motor. dq Recurrence relation for shaft current: Current prediction value for: in, The three-phase output voltage of the inverter, after passing through Clark and Park converters, is... dq The result obtained after removing the coupling term from the axis voltage. for dq The value of the shaft current in the k-th period. and They are respectively: in, For the direct-axis inductance of the motor, This refers to the stator phase resistance of the motor. For motor control cycle, The quadrature axis inductance of the motor; S5. Set the predicted current value obtained in step S4 to be equal to the commanded current to obtain the value required for calculation. dq Shaft voltage command value feedforward term; S6. The result obtained in step S5 dq The feedforward term of the shaft voltage command value undergoes Park inverse transformation and Clark inverse transformation, and is added to the feedback term of the three-phase voltage command value obtained in step S3 to obtain the three-phase voltage command value. S7. Calculate the modulus of the three-phase voltage command value obtained in step S6. When the modulus is greater than half of the DC bus voltage, it is an overload. Scale the values ​​proportionally to obtain the three-phase voltage command value within the modulation range. S8. Calculate the pulse width modulation duty cycle of each phase of the motor based on the magnitude and sign of the three-phase voltage command value obtained in step S7, and generate a PWM wave based on the pulse width modulation duty cycle. S9. The PWM wave generated in step S8 is output to the three-level inverter bridge module to form the required driving voltage, which is applied to the motor to form the motor current.

2. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that, In step S3, the three-phase voltage command value feedback item for: in, This is the proportionality coefficient. The integral coefficient is... These are frequency domain characteristic parameters. The three-phase command current and the three-phase feedback current of the motor The current error term obtained by subtraction.

3. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that, In step S5, dq Substitute the shaft current command value obtained in step S4 In the middle, calculate according to the formula And add it to the previously removed coupling terms to obtain dq Feedforward term in shaft voltage command value.

4. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that, In step S8, the positive and negative values ​​of the generated three-phase voltage command value are first determined, and the corresponding control power device is selected according to the positive and negative values. The absolute value of the three-phase voltage command value is then generated, and the absolute value is compared with the carrier wave whose amplitude is equal to half of the DC bus voltage to generate the PWM wave for controlling the power device. By using the three-phase voltage command value and carrier wave to generate and control the PWM wave of the 12 power devices in the three phases of the inverter, the three-phase outputs are made to switch in different states, so that the actual value of the three-phase stator current of the motor tracks the command value.

5. A two-degree-of-freedom permanent magnet synchronous motor drive device, characterized in that, The method according to any one of claims 1 to 4 comprises: The motor electrical angle detection module is used to sample the rotor electrical angle of a three-phase AC permanent magnet synchronous motor and feed back the actual value of the three-phase current to the first coordinate transformation module, the second coordinate transformation module and the third coordinate transformation module; The first coordinate transformation module is used to obtain coordinates based on settings or the outer loop servo controller. dq The commanded value of the shaft current is used to obtain the commanded value of the three-phase stator current, and the commanded value of the three-phase stator current is compared with the actual value of the three-phase current fed back by sampling to obtain the error term; The PI regulator module is used to calculate the three-phase voltage command value feedback term from the error term; The feedforward calculation module is used to compensate for the error caused by the two-cycle lag between the current command value and the actual output voltage of the inverter to the permanent magnet synchronous motor, and at the same time to prevent the voltage command value from being overloaded. The second coordinate transformation module is used to convert the obtained actual values ​​of the three-phase current into... dq The actual value of the shaft current is used for calculations in the feedforward calculation module. The third coordinate transformation module is used to convert the actual three-phase voltage values ​​output by the inverter into... dq The actual value of the shaft voltage is used for calculation by the feedforward calculation module; The PWM generation module is used to generate PWM waves to control the power devices in the inverter bridge. The inverter bridge module switches the power devices according to the PWM wave to generate AC power, which is then transmitted to the permanent magnet synchronous motor.

6. The two-degree-of-freedom permanent magnet synchronous motor drive device according to claim 5, characterized in that, The power devices for each phase of the permanent magnet synchronous motor are IGBTs or MOSEFTs.

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