Two-degree-of-freedom permanent magnet synchronous motor driving method and driving device thereof

Abstract

The invention discloses a two-degree-of-freedom permanent magnet synchronous motor driving method and a driving device thereof. A current instruction value of a d-q axis passes through a first coordinate conversion module to obtain an instruction value of a three-phase stator current; then comparing with a three-phase current actual value fed back by sampling, and obtaining a feedback item of a three-phase instruction voltage through a PI regulator module; deriving a recursive relational expression of d-q axis current along with the change of the control period, processing three-phase voltage fed back by the motor through a third coordinate transformation module to obtain d-q axis voltage, substituting the feedback three-phase current through a second coordinate transformation module to obtain d-q axis current and a d-q axis current instruction value into the recursive relational expression, and finally obtaining a three-phase instruction voltage feed-forward item; and adding the feed-forward item and the feedback item to obtain a three-phase voltage instruction value, inputting the three-phase voltage instruction value into a switch function module, determining a power device in the controlled three-level inverter bridge module according to the positive and negative of each instruction value, comparing the power device with a carrier wave to obtain a required PWM wave, and finally obtaining an alternating current and outputting the alternating current to the three-phase permanent magnet synchronous motor.

Description

Technical Field

[0001] The present invention belongs to the technical field of three-phase AC motor control, and in particular relates to a two-degree-of-freedom permanent magnet synchronous motor driving method and a driving device thereof. Background Art

[0002] At present, direct torque control and vector control are the two most commonly used methods in the field of high-performance AC variable frequency speed regulation. Direct torque control uses the space vector analysis method to directly realize the calculation control and torque control of the flux space vector in the stator coordinate system, which simplifies the actual control system and improves the system's rapid response capability, but it is accompanied by defects such as poor robustness and large torque pulsation.

[0003] Therefore, direct torque control is not common in high-performance servo control systems. Vector control technology is also called field-oriented control technology, which is to use the direction of the rotating magnetic field vector as the reference direction of the coordinate axis to establish a rotating coordinate system, and the motor current vector and the like are all represented in the above rotating coordinate system. Its basic feature is that in the rotating coordinate system, the stator current of the three-phase motor can be decomposed into independent excitation components and torque components for separate control. In this way, the mathematical model of the AC motor is reconstructed into the form of a separately excited DC motor through vector transformation, realizing the decoupling of the motor torque and the motor flux, and then realizing the separate control of the instantaneous torque.

[0004] The specific steps of vector control are generally: sector judgment, vector action time calculation, vector switching time calculation, and finally the generation of pulse width modulation switch signal (PWM wave). However, in order to obtain higher voltage resolution, when the driver is 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. The amount of calculation required for sector judgment and PWM generation process is greatly increased, making the control method more complicated, the calculation time is extended, and the control cycle is reduced. Because high-performance servo systems require high speed, high precision, high stability and wide speed regulation range, it is necessary to propose a control algorithm that adapts to three levels. 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 a driving device thereof in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problems that the three-level motor control algorithm is complex, the calculation time is long, and the control cycle is affected.

[0006] The present invention adopts the following technical solutions: A two-degree-of-freedom permanent magnet synchronous motor driving method, comprising: S1, sampling the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor; S2, through Park inverse transform and Clark inverse transformd-q The shaft current command value is converted into a three-phase current command value, and then a difference operation is performed with the actual value of the three-phase current obtained in step S1 to obtain an error term; S3, the error term obtained in step S2 is obtained by a PI controller to obtain a three-phase voltage command value feedback term; S4. According to the electromagnetic model of the motor, obtain d-q The recursive relationship of shaft current is based on d-q The shaft current recursive relation predicts the current prediction value after the command current has been calculated and modulated for two control cycles; S5. Make the current prediction value obtained in step S4 equal to the command current, and obtain the required current. d-q Shaft voltage command value feedforward item; S6, the step S5 obtained d-q The shaft voltage command value feedforward term is subjected to Park inverse transformation and Clark inverse transformation, and is added to the three-phase voltage command value feedback term obtained in step S3 to obtain the three-phase voltage command value; S7, the step S5 obtained d-q The shaft voltage command value feedforward item is modulated. When the modulus is greater than half of the DC bus voltage, it is overloaded and scaled proportionally to obtain a voltage within the modulation range. S8, calculating the pulse width modulation duty ratio of each phase of the motor according to the magnitude and positive and negative of the three-phase voltage command value obtained in step S6, and generating a PWM wave based on the pulse width modulation duty ratio; S9. The PWM wave generated in step S8 is output to the three-level inverter bridge module to form the required driving voltage, which acts on the motor to form the motor current.

[0007] Preferably, in step S2, the motor d-q Axis command current Perform coordinate transformation Get the motor three-phase command current ; and it is combined with the motor feedback three-phase current The current error term is obtained by subtracting .

[0008] Preferably, in step S3, the three-phase voltage command value feedback item for:

[0009] in, is the proportionality coefficient, is the integration coefficient, is the frequency domain characteristic parameter, The motor three-phase command current and the motor feedback three-phase current The current error term is obtained by taking the difference.

[0010] Preferably, in step S4, the current prediction value for:

[0011] in, The inverter outputs three-phase voltage after Park and Clark transformation. d-q The result obtained after removing the coupling term from the shaft voltage is: for, for, for d-q The value of the shaft current at the kth cycle.

[0012] Preferably, the electromagnetic model of the motor is used to obtain d-q Recursive relationship of shaft current:

[0014] Preferably, and They are:

[0015]

[0016] in, is the motor direct axis inductance, is the motor stator phase resistance, is the motor control cycle, is the quadrature-axis inductance of the motor.

[0017] Preferably, in step S5, d-q The shaft current command value is substituted into the value obtained in step S4. According to the formula, , and add it to the previously removed coupling term to get d-q Feedforward term in the shaft voltage command value.

[0018] Preferably, in step S8, first determine whether the generated three-phase voltage command value is positive or negative, and select the corresponding control power device according to the positive or negative; Then, the absolute value of the three-phase voltage command value is generated, and the absolute value is compared with a carrier wave whose amplitude is equal to half of the DC bus voltage to generate a PWM wave for controlling the power device; The three-phase voltage command value and carrier wave are used to generate the PWM wave of the 12 power devices in the three-phase inverter to make the three-phase output different switching states, so that the actual value of the three-phase current of the motor stator Tracking instruction values .

[0019] Another technical solution of the present invention is a two-degree-of-freedom permanent magnet synchronous motor drive device, comprising: The motor electrical angle detection module 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, the second coordinate transformation module and the third coordinate transformation module; The first coordinate transformation module is used to obtain the coordinate transformation module according to the setting or according to the outer loop servo controller. d-q The command value of the shaft current is obtained to obtain the command value of the three-phase stator current, and 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; A PI regulator module is used to calculate the error term to obtain a three-phase voltage command value feedback term; A 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, while preventing the voltage command value from being overloaded; The second coordinate transformation module is used to convert the actual value of the three-phase current into d-q The actual value of the shaft current is used for calculation in the feedforward calculation module; The third coordinate transformation module is used to convert the actual value of the three-phase voltage output by the inverter into d-q The actual value of the shaft voltage is used for calculation in the feedforward calculation module; PWM generation module, used to generate PWM waves for controlling each power device in the inverter bridge; The inverter bridge module switches the power devices according to the PWM wave to generate AC power which is transmitted to the permanent magnet synchronous motor.

[0020] Preferably, the power device of each phase of the permanent magnet synchronous motor is an IGBT or a MOSFET.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects: A two-degree-of-freedom permanent magnet synchronous motor driving method uses a PI regulator to compensate for disturbances and uses a delayed feedforward module to improve the dynamic following characteristics of the current. At the same time, since the three-level output level is , 0 enables it to generate PWM switching signals for each phase according to the duty cycle through the upper and lower half bridges according to the positive and negative output voltage. Compared with the traditional space vector pulse width modulation (SVPWM), this method does not need to perform sector judgment and vector action time calculation, which greatly reduces the amount of calculation. Therefore, this method takes into account both dynamic characteristics and anti-interference, and has the characteristics of simple structure, high bandwidth and strong robustness.

[0022] Furthermore, in order to correct the current following error, PI control is performed on the three-phase current to control the motor d-q Axis command current Perform coordinate transformation to obtain the three-phase command current of the motor ; Subtract it from the three-phase power of the motor feedback to get the current error term .

[0023] Furthermore, in order to ensure that the control algorithm has a certain degree of anti-interference, it is necessary to perform feedback control on the three-phase voltage command value to obtain the feedback term .

[0024] Furthermore, in order to compensate for the error caused by two control cycles from the command current to the actual output voltage to the motor control process, the command current is feedforward controlled to obtain the value of the current after two control cycles. .

[0025] Furthermore, to obtain d-q The value of the shaft current after two cycles needs to be obtained based on the motor electromagnetic model to obtain the motor current relationship, and then the relationship is discretized to obtain d-q The value of shaft current after one control cycle .

[0026] Furthermore, in order to compensate for the error caused by two control cycles from the command current to the actual output voltage during the motor control process, d-q Substitute the shaft current command value into The final output can follow the input command value and is then sent to the inverter. d-q Shaft voltage value , and add the coupling term removed for convenience of calculation to obtain d-q Shaft voltage command feedforward term .

[0027] Furthermore, since this method uses three levels to output , 0 circuit structure, in order to facilitate the control of power devices, the controlled power device part is determined according to the positive and negative output voltage command value. At the same time, in order to facilitate the calculation of duty cycle, the three-phase voltage command value is taken as the absolute value, and the absolute value is compared with the carrier wave with an amplitude equal to half of the DC bus voltage to generate the PWM wave for controlling the power device. In order to ensure the actual value of the final stator three-phase current Can track instruction values The PWM waves corresponding to the three-phase 12 power devices need to be input into the inverter bridge.

[0028] In summary, the three-phase stator current value in the present invention can quickly track the command value, and compared with the traditional vector control driving method of the motor, the response time is significantly shortened.

[0029] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] FIG1 is a diagram of an existing three-level structure driver, wherein (a) is a three-level structure driver, and (b) is another three-level structure driver; Figure 2 is a vector control diagram; Figure 3 This is a block diagram of the control principle of a two-degree-of-freedom three-level SPWM motor drive using feedback plus feedforward in the present invention; Figure 4 The motor in the present invention is in a simulation environment d-q Step response diagram of shaft current; Figure 5 For the traditional SPWM control of the motor in the simulation environment d-q Shaft current step response graph.

[0032] Among them: 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 DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0040] The present invention provides a two-degree-of-freedom permanent magnet synchronous motor driving method and a driving device thereof, which uses a PI regulator to compensate for disturbances and uses a delay-considered feedforward calculation module to improve the dynamic following characteristics of the current. , 0 so that it can be used according to the positive or negative output voltage and 0 or The duty cycle is calculated by 0, and the PWM switching signal of each phase is generated, which greatly reduces the amount of calculation. Therefore, the method of the present invention takes into account both dynamic characteristics and anti-interference characteristics, and has the characteristics of simple structure, high bandwidth and strong robustness.

[0041] The present invention provides a two-degree-of-freedom permanent magnet synchronous motor driving method, comprising the following steps: S1, sampling the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor; Sample the three-phase stator current of the motor to obtain the actual three-phase stator current The motor encoder is sampled through the motor speed position detection module 1 to obtain the motor rotor electrical angle.

[0042] S2, through Park inverse transform and Clark inverse transform d-q Axis current command value and Convert it into a three-phase current command value and perform difference calculation between it and the three-phase current value fed back by the motor to obtain the error term; When the controlled motor is a surface mounted permanent magnet synchronous motor, , the first coordinate transformation module 2 commands the motor q-axis current value And the d-axis command current Combine the rotor electrical angle obtained in step S1 to perform Park inverse transformation , get the motor stator three-phase current command value , as follows:

[0043] The motor three-phase command current Feedback three-phase current from the motor The current error term is obtained by subtracting, as follows:

[0045] S3, the error term is obtained through the PI controller to obtain the three-phase voltage command value feedback term; Will The motor stator voltage command value feedback item is obtained through PI regulator module 3 :

[0047] S4. According to the electromagnetic model of the motor, obtain d-q The shaft current recursive relation is used to predict the current prediction value after two control cycles required for calculation and modulation of the command current. According to the electromagnetic model of the motor, we can get d-q Recursive relationship of shaft current:

[0048] in, ,

[0049] According to the recursive relationship, the command current is predicted to be the predicted value after two control cycles of the PWM wave required to drive the power device after calculation and modulation. :

[0050] in, The inverter outputs three-phase voltage after Park and Clark transformation. d-q The result of shaft voltage after removing the coupling term.

[0051] S5, let the predicted value be equal to the command current, and then calculate the required d-q Shaft voltage command value feedforward term ; Will d-q The shaft current command value is substituted into the value obtained in step S4. According to the formula, , and add it to the previously removed coupling term to get d-q Feedforward term in shaft voltage command value .

[0052]

[0053] in, is the motor electrical angular velocity, Permanent magnet flux, the motor stator voltage command value feedback item Feedforward term with motor stator voltage command value Add to get the motor stator voltage command value .

[0054] S6, calculate the result obtained in step S5 d-q The shaft voltage command value feedforward term is subjected to Park inverse transformation and Clark inverse transformation to obtain the motor three-phase voltage command value feedforward term and compare it with the feedback item Add up to get the three-phase voltage command value ; S7, yes d-q The shaft voltage command value feedforward item is modulo-calculated and compared with half the DC bus voltage value. If it exceeds, it is scaled proportionally. right Find the model: If If it is greater than half of the bus voltage, it is considered overloaded and the overload ratio is calculated. ,make If it is less than or equal to half of the bus voltage, it is considered not to be overloaded and no processing is performed.

[0055] S8, calculating the pulse width modulation duty ratio of each phase of the motor according to the magnitude and positive and negative of each phase voltage command value, and generating a PWM wave; First determine whether the generated three-phase voltage command value is positive or negative, and select the corresponding control power device according to the positive or negative; The absolute value of the three-phase voltage command value is then generated, and the absolute value is compared with a carrier wave whose amplitude is equal to half of the DC bus voltage to generate a PWM wave for controlling the power device.

[0056] Will Output to PWM module 7, according to The positive and negative values ​​of the voltage command values ​​of each phase determine the controlled power device, and at the same time set the triangular carrier, the carrier frequency is the control frequency, and the carrier amplitude is half of the DC bus voltage. The absolute values ​​of the voltage command values ​​of each phase are compared and the PWM waves of each power device are output to control them.

[0057] S9, output the generated PWM wave to the three-level inverter bridge module 8 to form the required driving voltage, which acts on the motor to form the motor current.

[0058] See also Figure 3 The present invention discloses a two-degree-of-freedom permanent magnet synchronous motor drive device, which uses three-phase voltage command values ​​and carrier wave to generate PWM waves of 12 power devices in three phases of the inverter to make the three-phase output different switch states so that the actual value of the three-phase current of the motor stator is Tracking instruction values ; 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.

[0059] The output end of the permanent magnet synchronous motor is divided into three paths, one of which is divided into two paths through the PI regulator module 3, one of which is connected to the third coordinate transformation module 6 and the feedforward calculation module 4, and the other is connected to the control end of the permanent magnet synchronous motor through the PWM generation module 7 and the inverter bridge module 8; The second path is divided into two paths after passing through the second coordinate transformation module 5 and the feedforward calculation module 4 in sequence, 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 end of the permanent magnet synchronous motor through the PWM generation module 7 and the inverter bridge module 8; The third path is divided into three paths through the motor electrical angle detection module 1, and the first path is divided into two paths after passing through 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 end of the permanent magnet synchronous motor through the PWM generation module 7 and the inverter bridge module 8; The second path connects the third coordinate transformation module 6 and the feedforward calculation module 4, and the other path is divided into two paths after passing through the second coordinate transformation module 5 and the feedforward calculation module 4, one path connects the third coordinate transformation module 6 and the feedforward calculation module 4, and the other path is connected to the control end of the permanent magnet synchronous motor through the PWM generation module 7 and the inverter bridge module 8.

[0060] 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; The first coordinate transformation module 2 is used to obtain the coordinate transformation module according to the setting or according to the outer loop servo controller. d-q The command value of the shaft current is obtained, and then the command value of the three-phase stator current is obtained, and 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; PI regulator module 3, used for calculating the error term to obtain the three-phase voltage command value feedback term; A 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 to prevent the voltage command value from being overloaded; The second coordinate transformation module 5 is used to convert the obtained three-phase current actual value into d-q The actual value of the shaft current is used for calculation by the feedforward calculation module 4; The third coordinate transformation module 6 is used to convert the actual value of the three-phase voltage output by the inverter into d-q The actual value of the shaft voltage is used for calculation by the feedforward calculation module 4; PWM generation module 7, used to generate PWM waves for controlling each power device in the inverter bridge; The inverter bridge module 8 switches the power devices according to the PWM wave to generate AC power which is transmitted to the permanent magnet synchronous motor.

[0061] The power devices of each phase of the permanent magnet synchronous motor are IGBT or MOS EFT.

[0062] The working principle of a two-degree-of-freedom permanent magnet synchronous motor drive device of the present invention is as follows: Set or get according to the outer loop servo controller d-q The command value of the shaft current, d Axis and q The current command value of the axis is then passed through the first coordinate transformation module 2 to obtain the command value of the three-phase stator current; The command value of the three-phase stator current obtained by the first coordinate transformation module 2 is compared with the actual value of the three-phase current fed back by sampling, and the feedback item of the three-phase command voltage is obtained by the PI regulator module 3; According to the motor electromagnetic equation, it is deduced d Axis and q The recursive relationship between the shaft current and the control cycle is obtained by converting the three-phase voltage fed back by the motor through the third coordinate transformation module 6. d Axis and q The shaft voltage is obtained by feeding back the three-phase current through the second coordinate transformation module 5. d Axis and q The shaft current and d Axis and q Substituting the shaft current command value into the recursive relationship finally obtains the three-phase command voltage feedforward term; 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, and the power device in the controlled inverter bridge module 8 is determined according to the positive and negative of each command value and the required PWM wave is obtained by comparing with the carrier wave, and finally input to the inverter bridge module 8 to obtain AC output to the three-phase permanent magnet synchronous motor.

[0063] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0064] Example 1 The following describes an embodiment of the present invention based on the SimuLink simulation platform.

[0065] See also Figure 3 The feedback plus feedforward two-degree-of-freedom permanent magnet synchronous motor driving method of this embodiment includes the following steps: Step 1: Initialize the motor parameters according to the motor nameplate and complete the setting of the motor parameters in the motor drive control; Step 2: Measure the three-phase stator current of the motor Sampling is performed, and the motor rotor angle position is detected by the motor speed position detection module 1, and the rotor electrical angle is obtained by multiplying it by the number of motor pole pairs. ; Step 3: Set the command current value of the motor q axis In this embodiment, a surface-mounted three-phase AC synchronous motor model is used for simulation, so the current , thereby obtaining the command current values ​​of the motor d-axis and q-axis respectively and ; Step 4: After the first coordinate transformation module 2, the command current value of the motor q axis is And the d-axis command current Perform coordinate transformation , get the motor stator three-phase current command value , specifically expressed as:

[0066] Among them, the motor stator three-phase current command value It is expressed as:

[0067] in, , , They are respectively the three-phase current command values ​​abc, and the coordinate transformation It is expressed as follows, The electrical angle of the motor rotor detected in step 2:

[0068] Among them, the motor d-q Axis current command value It is expressed as:

[0069] Step 5: The three-phase stator current of the motor sampled in step 1 is The motor stator three-phase current command value obtained in step 3 In comparison, the deviation term is as follows:

[0070] Step 6: The motor stator voltage command value feedback item is obtained through PI regulator module 3 , The calculation formula is as follows:

[0071] Step 7: Obtain the value of d-q Recursive relationship of shaft current:

[0072] in, , ; According to the recursive relationship, the command current is predicted to be the predicted value after two control cycles of the PWM wave required to drive the power device after calculation and modulation. :

[0073] in, The inverter outputs three-phase voltage which is converted by the third coordinate transformation module 6. After getting d-q The result obtained after removing the coupling term from the shaft voltage is the coordinate transformation It is expressed as follows:

[0074] Step 8: d-q Axis current command value Bring in According to the formula, , and add it to the previously removed coupling term to get d-q Feedforward term in shaft voltage command value , the specific formula is as follows:

[0075] in, is the motor electrical angular velocity, is the permanent magnet flux; It is expressed as:

[0076] It is expressed as:

[0077] After that, the motor stator voltage command value feedback item Feedforward term with motor stator voltage command value Add to get the motor stator voltage command value .

[0078] Step 9, Find the modulus, if If it is greater than half of the bus voltage, it is considered overloaded and the overload ratio is calculated. ,make If it is less than or equal to half of the bus voltage, it is considered not to be overloaded and no processing is performed.

[0079] Step 10: Output to PWM module 7, according to The positive and negative values ​​of the voltage command values ​​of each phase determine the controlled power device, and at the same time set the triangular carrier, the carrier frequency is the control frequency, and the carrier amplitude is half of the DC bus voltage; set the carrier value to P and The absolute values ​​of the voltage command values ​​of each phase are compared. Taking phase a as an example, if If it is less than P, then output "0". If it is greater than P, "1" is output to obtain the PWM wave for controlling each power device; Step 11, outputting the PWM wave to the inverter bridge module 8, controlling the switching state of the power devices therein to convert the DC bus voltage into the AC voltage required to drive the motor.

[0080] like Figure 3 The motor of the present invention is shown in the simulation environment. d-q The step response diagram of shaft current. Figure 4 The figure shows the motor in traditional SPWM control under simulation environment. d-q Shaft current step response graph.

[0081] It can be seen from the above that the actual current value in the present invention can quickly track the command value, and compared with the traditional vector control driving mode of the motor, the response time is significantly shortened.

[0082] In summary, the present invention provides a two-degree-of-freedom permanent magnet synchronous motor driving method and its driving device, which comprehensively utilizes the feedback and feedforward control methods and combines with a three-level driving device to implement current control on the permanent magnet synchronous motor. First, this paper uses the actual value of each phase current of the three-phase motor and the command current to obtain the command values ​​after transformation, and uses PI control to suppress the system disturbance through the error obtained. At the same time, through the derivation of the motor electromagnetic model, it is obtained d-q The recursive relation of the shaft current is derived and associated with the voltage to complete the feedforward control of the motor, thereby improving the dynamic following characteristics of the motor current. At the same time, the PWM method required for generating the control power device is sinusoidal pulse width modulation (SPWM), which greatly reduces the amount of calculation, increases the control frequency, and improves the dynamic following characteristics of each phase current. It can be seen that the present invention can overcome the technical disadvantages of the existing traditional motor vector control with complex calculations. The motor driving method of the present invention has the advantages of good anti-interference and good dynamic following characteristics.

[0083] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A two-degree-of-freedom permanent magnet synchronous motor driving method, characterized in that: include S1, sampling the actual value of the three-phase current of the three-phase AC permanent magnet synchronous motor; S2, through Park inverse transform and Clark inverse transform dq The shaft current command value is converted into a three-phase current command value, and then a difference operation is performed with the actual value of the three-phase current obtained in step S1 to obtain an error term; S3, the error term obtained in step S2 is obtained by a PI controller to obtain a three-phase voltage command value feedback term; S4. According to the electromagnetic model of the motor, obtain dq The recursive relationship of shaft current is based on dq The shaft current recursive relation predicts the current prediction value after the command current has been calculated and modulated for two control cycles; S5. Make the current prediction value obtained in step S4 equal to the command current, and obtain the required current. dq Shaft voltage command value feedforward item; S6, the step S5 obtained dq The shaft voltage command value feedforward term is subjected to Park inverse transformation and Clark inverse transformation, and is added to the three-phase voltage command value feedback term obtained in step S3 to obtain the three-phase voltage command value; S7, the step S5 obtained dq The shaft voltage command value feedforward item is modulated. When the modulus is greater than half of the DC bus voltage, it is overloaded and scaled proportionally to obtain a voltage within the modulation range. S8, calculating the pulse width modulation duty ratio of each phase of the motor according to the magnitude and positive and negative of the three-phase voltage command value obtained in step S6, and generating a PWM wave based on the pulse width modulation duty ratio; S9. The PWM wave generated in step S8 is output to the three-level inverter bridge module to form the required driving voltage, which acts on 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 S2, the motor dq Axis command current Perform coordinate transformation Get the motor three-phase command current ; and it is combined with the motor feedback three-phase current The current error term is obtained by subtracting .

3. 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, is the proportionality coefficient, is the integration coefficient, is the frequency domain characteristic parameter, The motor three-phase command current and the motor feedback three-phase current The current error term is obtained by taking the difference.

4. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that: In step S4, the current prediction value for: in, The inverter outputs three-phase voltage after Park and Clark transformation. dq The result obtained after removing the coupling term from the shaft voltage is: for, for, for dq The value of the shaft current at the kth cycle.

5. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 4, characterized in that: According to the electromagnetic model of the motor, we can get dq Recursive relationship of shaft current: 。 6. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 5, characterized in that: and They are: in, is the motor direct axis inductance, is the motor stator phase resistance, is the motor control cycle, is the motor quadrature-axis inductance.

7. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that: In step S5, dq The shaft current command value is substituted into the value obtained in step S4. According to the formula, , and add it to the previously removed coupling term to get dq Feedforward term in the shaft voltage command value.

8. The two-degree-of-freedom permanent magnet synchronous motor driving method according to claim 1, characterized in that: In step S8, first determine whether the generated three-phase voltage command value is positive or negative, and select the corresponding control power device according to the positive or negative; Then, the absolute value of the three-phase voltage command value is generated, and the absolute value is compared with a carrier wave whose amplitude is equal to half of the DC bus voltage to generate a PWM wave for controlling the power device; The three-phase voltage command value and carrier wave are used to generate the PWM wave of the 12 power devices in the three phases of the inverter to make the three-phase output different switching states, so that the actual value of the three-phase current of the motor stator Tracking instruction values .

9. A two-degree-of-freedom permanent magnet synchronous motor drive device, characterized in that: Utilize the method described in any one of claims 1 to 8, comprising: The motor electrical angle detection module 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, the second coordinate transformation module and the third coordinate transformation module; The first coordinate transformation module is used to obtain the coordinate transformation module according to the setting or according to the outer loop servo controller. dq The command value of the shaft current is obtained to obtain the command value of the three-phase stator current, and 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; A PI regulator module is used to calculate the error term to obtain a three-phase voltage command value feedback term; A 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, while preventing the voltage command value from being overloaded; The second coordinate transformation module is used to convert the actual value of the three-phase current into dq The actual value of the shaft current is used for calculation in the feedforward calculation module; The third coordinate transformation module is used to convert the actual value of the three-phase voltage output by the inverter into dq The actual value of the shaft voltage is used for calculation in the feedforward calculation module; PWM generation module, used to generate PWM waves for controlling each power device in the inverter bridge; The inverter bridge module switches the power devices according to the PWM wave to generate AC power which is transmitted to the permanent magnet synchronous motor.

10. The two-degree-of-freedom permanent magnet synchronous motor drive device according to claim 9, characterized in that: The power devices of each phase of the permanent magnet synchronous motor are IGBT or MOS EFT.

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