Current loop decoupling control method of permanent magnet synchronous motor and permanent magnet synchronous motor assembly

Abstract

The invention discloses a current loop decoupling control method of a permanent magnet synchronous motor and a permanent magnet synchronous motor assembly. The current loop decoupling control method of the permanent magnet synchronous motor comprises the following steps: acquiring a d-axis current reference value and a q-axis current reference value of the permanent magnet synchronous motor in a d-q coordinate system; enabling the d-axis current reference value and the q-axis current reference value to pass through a first-order inertia link to obtain d-axis current correction values and q-axis current correction values; obtaining a motor inductance parameter and a motor rotor electrical angular velocity of the permanent magnet synchronous motor; and calculating and outputting d-axis and q-axis compensation voltages of the permanent magnet synchronous motor under the d-q coordinate system according to a compensation voltage calculation formula. The method can solve the problem that when a current reference value is used for decoupling, the reference value suddenly changes, control time delay and the like cause that the reference current and the actual current are inconsistent and cannot be completely decoupled.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment technology, and in particular to a current loop decoupling control method for a permanent magnet synchronous motor and a permanent magnet synchronous motor component. Background Art

[0002] Permanent magnet synchronous motors have the advantages of high efficiency and high power density, and are widely used in many occasions requiring high precision and high dynamic response. However, in the actual control process, permanent magnet synchronous motors have the characteristics of nonlinearity and strong coupling. In particular, as the speed increases, the motor AC-DC coupling problem gradually intensifies. Therefore, how to achieve high-precision control of the current loop is very important. At present, the commonly used decoupling method is to use the internal model principle for feedforward decoupling. One is to calculate the compensation voltage through the current feedback value and the motor parameters, so that the compensation voltage and the voltage coupling term just offset each other to achieve decoupling control. However, this method obtains the three-phase current feedback value through current sampling, and then obtains the dq axis current through coordinate transformation. At this time, sampling errors and interference will be introduced into the current feedback value, causing system noise problems. Another method is to calculate the compensation voltage through the current reference value and the motor parameters, but the dq axis current reference value is given by the speed loop controller and changes in real time, and there is an error with the actual motor current. Therefore, the current loop cannot be completely decoupled, that is, the compensation voltage cannot completely offset the coupling voltage inside the permanent magnet synchronous motor, thereby affecting the dynamic response of the system. Summary of the invention

[0003] The main purpose of the present invention is to propose a current loop decoupling control method for a permanent magnet synchronous motor, aiming to solve the problem that when using a current reference value for decoupling, the reference value mutation, control delay, etc. cause the reference current to be inconsistent with the actual current and cannot be completely decoupled.

[0004] To achieve the above object, the present invention proposes a current loop decoupling control method for a permanent magnet synchronous motor, comprising:

[0005] Obtain the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system;

[0006] The d-axis and q-axis current reference values ​​are passed through the first-order inertia link to obtain the d-axis and q-axis current correction values;

[0007] Obtain the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor;

[0008] Calculate and output the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system;

[0009] According to the feedforward link, the d-axis and q-axis compensation voltages are superimposed on the d-axis and q-axis current closed-loop controller output voltages to obtain the d-axis and q-axis input voltages;

[0010] The d-axis and q-axis input voltages are offset from the d-axis and q-axis coupling term voltages to achieve current loop decoupling.

[0011] Optionally, the compensation voltage calculation formula is:

[0012]

[0013] In the formula, and are the dq axis compensation voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the dq axes, ψ f is the permanent magnet flux, and They are the d-axis and q-axis current correction values ​​respectively.

[0014] Optionally, the transfer function of the first-order inertia link is:

[0015]

[0016] In the formula, ω 0 is the cut-off frequency of the first-order inertia link.

[0017] Optionally, the cut-off frequency ω 0 The value range is the current loop controller bandwidth ω c 0.3 to 3 times of.

[0018] Optionally, the cut-off frequency ω 0 and the current loop controller bandwidth ω c equal.

[0019] Optionally, the current loop decoupling control method of the permanent magnet synchronous motor further includes:

[0020] Optionally, the feedforward link is:

[0021]

[0022] In the formula, u d and u q are the d-axis and q-axis input voltages, u d0 and u q0 They are the d-axis and q-axis output voltages of the current closed-loop controller, and They are the d-axis and q-axis compensation voltages respectively.

[0023] Optionally, the mathematical model of the controlled object of the current closed-loop controller is:

[0024]

[0025] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, U d (s) and U q (s) is the Laplace transform form of the d-axis and q-axis input voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the d-axis and q-axis, ψ f is the permanent magnet flux. e L q I q (s) is the d-axis current coupling term, -ω e L d I d (s)-ω e ψ f is the q-axis current coupling term.

[0026] Optionally, the current closed-loop controller is a PI controller, and the proportional coefficient k p and the integration coefficient k i for:

[0027]

[0028] In the formula, ω c is the bandwidth of the current loop controller, L corresponds to the d-axis and q-axis inductance, R s is the stator winding resistance.

[0029] Optionally, the transfer function of the current inner loop is:

[0030]

[0031]

[0032]

[0033]

[0034]

[0035] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ωqc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0036] Optionally, the cut-off frequency ω 0 and the current loop controller bandwidth ω c equal;

[0037] The transfer function of the entire current inner loop is:

[0038]

[0039]

[0040] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0041] The present invention also proposes a permanent magnet synchronous motor component, characterized in that it includes a permanent magnet synchronous motor and a controller, wherein a current loop decoupling control program is stored in the controller, and when the current loop decoupling control program is executed by the controller, the current loop decoupling control method of the permanent magnet synchronous motor as described above is implemented.

[0042] In the technical solution of the present invention, the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system are first obtained, and then the d-axis and q-axis current reference values ​​are passed through a first-order inertia link to obtain the d-axis and q-axis current correction values, and the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor are obtained at the same time, and according to the compensation voltage calculation formula, the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system are calculated and output, so that the decoupling module can superimpose the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system with the d-axis and q-axis current closed-loop controller output voltages, and then offset the d-axis and q-axis coupling term voltages to achieve current loop decoupling. The present invention uses the value of the current reference value after passing through the first-order inertia link to calculate the coupling voltage, does not need to use the current feedback value for decoupling compensation, avoids the sampling delay and noise problems brought to the decoupling link by current sampling, and solves the problem that the reference current is inconsistent with the actual current and cannot be completely decoupled due to the sudden change of the current reference value and the control delay. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 the structures shown in these drawings without paying creative work.

[0044] Figure 1 A schematic diagram of current loop decoupling term compensation of an embodiment of a current loop decoupling control method for a permanent magnet synchronous motor of the present invention;

[0045] Figure 2 It is a flow chart of an embodiment of a current loop decoupling control method for a permanent magnet synchronous motor of the present invention;

[0046] Figure 3 It is a schematic diagram comparing the d-axis current waveforms of the traditional reference value feedforward decoupling and the decoupling method of the present invention when the dq-axis current command changes;

[0047] Figure 4 It is a schematic diagram comparing the q-axis current waveforms of the traditional reference value feedforward decoupling and the decoupling method of the present invention when the dq-axis current command changes;

[0048] Figure 5 is the first-order inertia link cut-off frequency ω of the permanent magnet synchronous motor of the present invention 0 Curve diagram showing the effect of different values ​​on the dq axis current decoupling effect;

[0049] Figure 6 This is a vector control block diagram of the permanent magnet synchronous motor of the present invention.

[0050] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0051] 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 only 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.

[0052] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0053] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0054] The field oriented control technology (FOC) of high-performance permanent magnet synchronous motors is mostly implemented using the direct axis (d-axis) in the direction of the rotor's N pole and the quadrature axis (q-axis) coordinates that differ from the d-axis by 90 degrees in electrical angle. This technology calculates the three-phase voltage and current on the output dq axis through coordinate transformation, and then implements the current feedback control of the dq axis respectively according to the dq axis current reference value through PI control technology, etc., to meet the motion control requirements of the permanent magnet motor. However, due to the mutual coupling mechanism between the voltage and current inside the motor, the voltage on the dq axis is mutually coupled with parameters such as the motor speed. Especially when the speed is high and the current reference value changes greatly, these coupling quantities have a greater impact on the motor control performance, and removing the influence of these couplings (decoupling) is very necessary to improve the motor performance.

[0055] At present, the commonly used decoupling method is to use the mechanism of direct mutual coupling between the dq axes of the motor for feedforward decoupling, that is, the voltage coupling term is calculated through the motor speed (the electrical frequency obtained by multiplying the motor mechanical speed by the number of rotor poles), d-axis inductance, q-axis inductance, rotor flux, etc., and then applied in reverse to the coupled dq axes to remove the influence of coupling.

[0056] There are two main decoupling technologies currently in use. One is to calculate the compensation voltage through the current feedback value and the motor parameters, so that the compensation voltage and the voltage coupling term just offset each other to achieve decoupling control. However, this method obtains the three-phase current feedback value through current sampling, and then obtains the dq axis current through coordinate transformation. At this time, sampling errors and interference will be introduced into the current feedback value, causing system noise problems. Another method is to calculate the compensation voltage through the current reference value and the motor parameters, but the dq axis current reference value is given by the speed loop controller and changes in real time, and there is an error with the actual motor current. Therefore, the current loop cannot be completely decoupled, that is, the compensation voltage cannot completely offset the coupling voltage inside the permanent magnet synchronous motor, thereby affecting the dynamic response of the system.

[0057] In order to solve the above problems, the present invention proposes a current loop decoupling control method for a permanent magnet synchronous motor. Figure 1 and Figure 2 In one embodiment, the current loop decoupling control method of the permanent magnet synchronous motor includes:

[0058] Step S100, obtaining d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in a dq coordinate system;

[0059] Step S200, passing the d-axis and q-axis current reference values ​​through a first-order inertia link to obtain d-axis and q-axis current correction values;

[0060] Step S300, obtaining the motor inductance parameter and the motor rotor electrical angular velocity of the permanent magnet synchronous motor;

[0061] Step S400, calculating and outputting the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system according to the compensation voltage calculation formula;

[0062] Step S500, according to the feedforward link, the d-axis and q-axis compensation voltages are superimposed on the d-axis and q-axis current closed-loop controller output voltages to obtain d-axis and q-axis input voltages;

[0063] Step S600: offset the d-axis and q-axis input voltages with the d-axis and q-axis coupling term voltages to achieve current loop decoupling.

[0064] Wherein, the compensation voltage calculation formula is:

[0065]

[0066] In the formula, and are the dq axis compensation voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the dq axes, ψ f is the permanent magnet flux, and They are the d-axis and q-axis current correction values ​​respectively.

[0067] In this embodiment, a controller for controlling the permanent magnet synchronous motor may be provided, such as an MCU, a DSP (Digital Signal Process), an FPGA (Field Programmable Gate Array), etc., to control the operation of the permanent magnet synchronous motor, as well as parameter information of the permanent magnet synchronous motor.

[0068] In this embodiment, the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system are first obtained. It can be understood that the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system are pre-set for current loop control. After obtaining the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system, the d-axis and q-axis current reference values ​​are passed through a first-order inertia link to obtain the d-axis and q-axis current correction values. After obtaining the d-axis and q-axis current correction values, the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor are obtained, and according to the compensation voltage calculation formula, the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system are calculated and output, wherein the compensation voltage calculation formula is:

[0069]

[0070] In the formula, and are the dq axis compensation voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the dq axes, ψ f is the permanent magnet flux, and are the d-axis and q-axis current correction values, respectively. In this way, the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system can be obtained, and the decoupling module can superimpose the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system with the d-axis and q-axis current closed-loop controller output voltages, and then offset them with the d-axis and q-axis coupling term voltages to achieve current loop decoupling.

[0071] It can be understood that when the decoupling module is designed as above, the transfer function of the entire current inner loop is:

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] In the formula, I d (s) and I q (s) is the Laplace transform form of the dq axis current, and is the Laplace transform form of the dq axis reference current input, ω d0 and ωq0 are the cutoff frequencies of the first-order inertial links of the dq axes, ω dc and ω qc are the bandwidths of the dq axis current loop controller respectively.

[0078] In particular, when the cutoff frequency ω of the first-order inertial link on the d-axis d0 and the q-axis current loop bandwidth ω qc Equal, the cutoff frequency of the first-order inertial link of the q axis is ω q0 and the d-axis current loop bandwidth ω dc When they are equal, the transfer function can be simplified to:

[0079]

[0080]

[0081] It can be seen from the above formula that the AC and DC axis currents of the motor are only related to its own reference current input. At this time, the current loop is completely decoupled, that is, at the cutoff frequency ω 0 and the current loop controller bandwidth ω c When the current loop is completely decoupled, the transfer function of the first-order inertia link for obtaining the d-axis and q-axis current correction values ​​can be expressed as:

[0082]

[0083] In the formula, ω 0 is the cut-off frequency of the first-order inertia link.

[0084] In the technical solution of the present invention, the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system are first obtained, and then the d-axis and q-axis current reference values ​​are passed through a first-order inertia link to obtain the d-axis and q-axis current correction values, and the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor are obtained at the same time, and according to the compensation voltage calculation formula, the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system are calculated and output, so that the decoupling module can superimpose the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system with the d-axis and q-axis current closed-loop controller output voltages, and then offset the d-axis and q-axis coupling term voltages to achieve current loop decoupling. The present invention uses the value of the current reference value after passing through the first-order inertia link to calculate the coupling voltage, does not need to use the current feedback value for decoupling compensation, avoids the sampling delay and noise problems brought to the decoupling link by current sampling, and solves the problem that the reference current is inconsistent with the actual current and cannot be completely decoupled due to the sudden change of the current reference value and the control delay.

[0085] Reference Figure 6 In one embodiment, the cut-off frequency ω 0 The value range is the current loop controller bandwidth ωc 0.3 to 3 times of.

[0086] Reference Figure 6 , Figure 6 is the cutoff frequency ω of the first-order inertia link 0 The influence curve of different values ​​on the dq axis current decoupling effect is shown in the attached figure. Figure 6 The ω shown 0 / ω c The effect of ratio on the decoupling effect of dq axis current, when the cut-off frequency ω 0 Take the current loop controller bandwidth ω c When the cutoff frequency ω is 0.3 to 3 times of the reference current, the current mutation caused by the coupling effect is much smaller than the change caused by the reference current feedforward decoupling. 0 The value range of can be the current loop controller bandwidth ω c Preferably, when the cutoff frequency ω 0 and the current loop controller bandwidth ω c When the current is equal, the current suddenly changes to 0, and the current loop can be completely decoupled.

[0087] Reference Figure 1 and Figure 3 In one embodiment, the feedforward link is:

[0088]

[0089] In the formula, u d and u q are the d-axis and q-axis input voltages, u d0 and u q0 They are the d-axis and q-axis output voltages of the current closed-loop controller, and They are the d-axis and q-axis compensation voltages respectively.

[0090] Optionally, the mathematical model of the controlled object of the current closed-loop controller is:

[0091]

[0092] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, U d (s) and U q (s) is the Laplace transform form of the d-axis and q-axis input voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the d-axis and q-axis, ψ f is the permanent magnet flux. e Lq I q (s) is the d-axis current coupling term, -ω e L d I d (s)-ω e ψ f is the q-axis current coupling term.

[0093] Optionally, it is characterized in that the current closed-loop controller is a PI controller, and the proportional coefficient k p and the integration coefficient k i for:

[0094]

[0095] In the formula, ω c is the bandwidth of the current loop controller, L corresponds to the d-axis and q-axis inductance, R s is the stator winding resistance.

[0096] Optionally, it is characterized in that the transfer function of the entire current inner loop is:

[0097]

[0098]

[0099]

[0100]

[0101]

[0102] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0103] Optionally, it is characterized in that the cut-off frequency ω 0 and the current loop controller bandwidth ω c equal;

[0104] The transfer function of the inner current loop is:

[0105]

[0106]

[0107] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0108] In this embodiment, the current closed-loop controller adopts PI control. By designing the PI parameters, the system is corrected into a typical type I system. At this time, the proportional coefficient k p and the integration coefficient k i Take it as:

[0109]

[0110] Among them, ω c is the current loop controller bandwidth, L corresponds to the dq axis inductance, R s is the stator winding resistance.

[0111] Furthermore, a dq-axis feedforward link is designed, and according to the feedforward link, the d-axis and q-axis compensation voltages are superimposed with the d-axis and q-axis current closed-loop controller output voltages to obtain d-axis and q-axis input voltages, and then the d-axis and q-axis input voltages are offset with the d-axis and q-axis coupling term voltages to achieve current loop decoupling.

[0112] Wherein, the feedforward link is:

[0113]

[0114] In the formula, u d and u q are the d-axis and q-axis input voltages, u d0 and u q0 They are the d-axis and q-axis output voltages of the current closed-loop controller, and They are the d-axis and q-axis compensation voltages respectively.

[0115] Furthermore, when the current loop controller and the decoupling module are designed as above, the transfer function of the entire current inner loop is:

[0116]

[0117]

[0118]

[0119]

[0120]

[0121] In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0122] In particular, when the cutoff frequency ω of the first-order inertial link on the d-axis d0 and the q-axis current loop bandwidth ω qc Equal, the cutoff frequency of the first-order inertial link of the q axis is ω q0 and the d-axis current loop bandwidth ω dc When they are equal, the transfer function can be simplified to:

[0123]

[0124]

[0125] It can be seen from the above formula that the AC and DC axis currents of the motor are only related to its own reference current input. At this time, the current loop is completely decoupled, that is, at the cutoff frequency ω 0 and the current loop controller bandwidth ω c When the current loop is completely decoupled, the current loop is completely decoupled. In addition, in practical applications, control delay needs to be considered. Therefore, the delay time can also be set in the motor controller to compensate for the delay link.

[0126] In order to better illustrate the inventive concept of the present invention, the working principle of the present invention is described below in conjunction with a specific embodiment and a schematic diagram of compensation for decoupling items in a current loop of a permanent magnet synchronous motor.

[0127] Figure 5 The figure shows a typical permanent magnet synchronous motor current vector control control block diagram with speed loop control. After receiving the speed command, the speed controller compares it with the feedback speed and generates the d-axis and q-axis current commands through control strategies such as PI control. The feedback speed can be calculated by differential calculation of the motor shaft position sensor, or by a motor position / speed observer (not shown).

[0128] The dq axis current feedback value is obtained by coordinate transformation based on the above position information and the sampled 3-phase / 2-phase current. The dq axis reference voltage given by the current controller is then calculated by SVPWM to obtain the inverter drive signal to control the motor speed. Figure 1 The control strategy implementation given is as follows:

[0129] According to the voltage equation of the permanent magnet synchronous motor, the motor current loop model in the dq coordinate system is established, and the mathematical model of the controlled object is:

[0130]

[0131] In the formula, I d (s) and I q (s) is the Laplace transform form of the dq axis current, U d (s) and U q (s) is the Laplace transform form of the dq axis input voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the dq axes, ψ f is the permanent magnet flux. e L q I q (s) is the d-axis current coupling term, -ω e L d I d (s)-ω e ψ f is the q-axis current coupling term.

[0132] The current closed-loop controller adopts PI control. By designing the PI parameters, the system is corrected into a typical type I system. At this time, the proportional coefficient k p and the integration coefficient k i Take it as:

[0133]

[0134] Among them, ω c is the current loop controller bandwidth, L corresponds to the dq axis inductance, R s is the stator winding resistance.

[0135] Then, the d-axis and q-axis current reference values ​​are passed through a first-order inertia link to obtain the d-axis and q-axis current correction values. The transfer function of the first-order inertia link is expressed as:

[0136]

[0137] Among them, ω 0 is the cut-off frequency of the first-order inertia link.

[0138] Targeting ω 0 The value of Figure 6 The ω shown 0 / ω c The effect of ratio on the decoupling effect of dq axis current, when the cut-off frequency ω 0 Take the current loop controller bandwidth ω c When the cutoff frequency ω is 0.3 to 3 times of the reference current, the current mutation caused by the coupling effect is much smaller than the change caused by the reference current feedforward decoupling. 0 and the controller bandwidth ω c When the current is equal, it suddenly changes to 0, which can achieve complete decoupling of the current loop.

[0139] Furthermore, the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor are obtained, and according to the compensation voltage calculation formula, the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system are calculated and output.

[0140] Design a dq axis feedforward link, and according to the feedforward link, superimpose the d axis and q axis compensation voltages with the d axis and q axis current closed-loop controller output voltages to obtain the d axis and q axis input voltages, and then offset the d axis and q axis input voltages with the d axis and q axis coupling term voltages to achieve current loop decoupling. Among them, the feedforward link is:

[0141]

[0142] In the formula, u d and u q are the d-axis and q-axis input voltages, u d0 and u q0 They are the d-axis and q-axis output voltages of the current closed-loop controller, and They are the d-axis and q-axis compensation voltages respectively.

[0143] Furthermore, when the current loop controller and the decoupling module are designed as above, the transfer function of the entire current inner loop is:

[0144]

[0145]

[0146]

[0147]

[0148]

[0149] In the formula, I d (s) and I q(s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

[0150] In particular, when the cutoff frequency ω of the first-order inertial link on the d-axis d0 and the q-axis current loop bandwidth ω qc Equal, the cutoff frequency of the first-order inertial link of the q axis is ω q0 and the d-axis current loop bandwidth ω dc When they are equal, the transfer function can be simplified to:

[0151]

[0152]

[0153] It can be seen from the above formula that the AC and DC axis currents of the motor are only related to its own reference current input. At this time, the current loop is completely decoupled, that is, at the cutoff frequency ω 0 and the current loop controller bandwidth ω c When they are equal, the current loop is completely decoupled.

[0154] From the simulation results, when the current command is directly decoupled and compensated, the dq axis current response results are as follows: Figure 4 and Figure 5 As shown. At the initial moment, the d and q axis current commands are both 0A. At 0.5s, the q axis current command changes to 1A. At this time, the d axis current waveform is distorted, and the maximum current change is 0.07A. After 0.05s, it returns to a steady state of 0A. At 1.5s, the d axis current command changes to -1A. At this time, the q axis current waveform is distorted, and the maximum current change is 0.06A. After 0.05s, it returns to a steady state of 1A.

[0155] When the decoupling method of the present invention is adopted and the cutoff frequency ω of the first-order inertia link is 0 Take the current loop controller bandwidth ω c When the dq axis current response waveform is as follows Figure 4 and Figure 5 As shown in the figure. At the initial moment, the d and q axis current commands are both 0A. At 0.5s, the q axis current command changes to 1A. At this time, the d axis current waveform does not change at all and remains at 0A. At 1.5s, the d axis current command changes to -1A. At this time, the q axis current waveform does not change at all and remains at 1A. It can be seen that the d and q axes are completely decoupled at this time.

[0156] Regarding the range of the cutoff frequency of the first-order inertia link, Figure 6 The figure shows the relationship between the dq axis current distortion and the first-order inertia link cutoff frequency. It can be seen that when ω 0 / ω c The value range of ω is 0.3 to 3 times, and the current distortion is very small, especially ω 0 / ω c When >1, a good decoupling effect can be obtained.

[0157] The present invention also proposes a permanent magnet synchronous motor component, which includes a permanent magnet synchronous motor and a controller. The controller stores a current loop decoupling control program. When the current loop decoupling control program is executed by the controller, it implements the current loop decoupling control method of the permanent magnet synchronous motor as in the above embodiment. Since the permanent magnet synchronous motor component adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here one by one.

[0158] Similarly, the technical viewpoint of the present invention is discussed in the form of a transfer function of Laplace transform. However, in actual control, a microprocessor (MCU) is often used for digital control (discrete control). Therefore, the decoupling control technology of the present invention can be controlled by an analog circuit or an equivalent discrete control technology.

[0159] In addition, in order to simplify the description of the technical solution, the dq axis current reference value described in the present invention is obtained by the bandwidth ω of the first-order inertia link. 0 However, according to the control requirements, when the design bandwidths of the dq axis current loops are different, the technical idea of ​​the present invention can be used to determine the values ​​of the dq axis current loops.

[0160] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A current loop decoupling control method for a permanent magnet synchronous motor, It is characterized in that include: Obtain the d-axis and q-axis current reference values ​​of the permanent magnet synchronous motor in the dq coordinate system; The d-axis and q-axis current reference values ​​are passed through the first-order inertia link to obtain the d-axis and q-axis current correction values; Obtain the motor inductance parameters and the motor rotor electrical angular velocity of the permanent magnet synchronous motor; Calculate and output the d-axis and q-axis compensation voltages of the permanent magnet synchronous motor in the dq coordinate system; According to the feedforward link, the d-axis and q-axis compensation voltages are superimposed on the d-axis and q-axis current closed-loop controller output voltages to obtain the d-axis and q-axis input voltages; The d-axis and q-axis input voltages are offset from the d-axis and q-axis coupling term voltages to achieve current loop decoupling.

2. The current loop decoupling control method of a permanent magnet synchronous motor according to claim 1, It is characterized in that The transfer function of the first-order inertia link is: In the formula, ω 0 is the cut-off frequency of the first-order inertia link.

3. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 2, It is characterized in that The compensation voltage calculation formula is: In the formula, and are the dq axis compensation voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the dq axes, ψ f is the permanent magnet flux, and They are the d-axis and q-axis current correction values ​​respectively.

4. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 2, It is characterized in that The cut-off frequency ω 0 The value range is the current loop controller bandwidth ω c 0.3 to 3 times of.

5. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 2, It is characterized in that The cut-off frequency ω 0 and the current loop controller bandwidth ω c equal.

6. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 2, It is characterized in that The current loop decoupling control method of the permanent magnet synchronous motor also includes: The feedforward link is: In the formula, u d and u q are the d-axis and q-axis input voltages, u d0 and u q0 They are the d-axis and q-axis output voltages of the current closed-loop controller, and They are the d-axis and q-axis compensation voltages respectively.

7. The current loop decoupling control method of a permanent magnet synchronous motor according to claim 6, It is characterized in that The mathematical model of the controlled object of the current closed-loop controller is: In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, U d (s) and U q (s) is the Laplace transform form of the d-axis and q-axis input voltage, ω e is the electrical angular velocity of the motor rotor, L d and L q are the equivalent inductances of the d-axis and q-axis, ψ f is the permanent magnet flux. e L q I q (s) is the d-axis current coupling term, -ω e L d I d (s)-ω e ψ f is the q-axis current coupling term.

8. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 7, It is characterized in that The current closed-loop controller is a PI controller, and the proportional coefficient k p and the integration coefficient k i for: In the formula, ω c is the bandwidth of the current loop controller, L corresponds to the d-axis and q-axis inductance, R s is the stator winding resistance.

9. The current loop decoupling control method of a permanent magnet synchronous motor as claimed in claim 8, It is characterized in that The transfer function of the inner current loop is: In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

10. The current loop decoupling control method of a permanent magnet synchronous motor according to claim 9, It is characterized in that The cut-off frequency ω 0 and the current loop controller bandwidth ω c equal; The transfer function of the entire current inner loop is: In the formula, I d (s) and I q (s) is the Laplace transform form of the d-axis and q-axis currents, and is the Laplace transform form of the d-axis and q-axis reference current input, ω d0 and ω q0 are the cutoff frequencies of the first-order inertial links of the d-axis and q-axis, ω dc and ω qc They are the bandwidths of the d-axis and q-axis current loop controllers respectively.

11. A permanent magnet synchronous motor control system, It is characterized in that It comprises a permanent magnet synchronous motor and a controller, wherein a current loop decoupling control program is stored in the controller, and when the current loop decoupling control program is executed by the controller, a current loop decoupling control method for a permanent magnet synchronous motor as described in any one of claims 1 to 10 is implemented.

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