Current hysteresis control method, device and electronic equipment for permanent magnet synchronous motor

Abstract

Embodiments of the present invention disclose a current hysteresis control method, device, and electronic device for a permanent magnet synchronous motor. The method includes: determining a hysteresis output value of a predetermined axis based on a current parameter of the predetermined axis in a dq coordinate system; determining a predetermined axis voltage command to be output based on the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the predetermined axis voltage command is directly output according to a voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage command is calculated according to a voltage command output strategy and output. The present invention solves the technical problem in the related art of non-constant switching frequency and large steady-state current fluctuations in current hysteresis control of PMSMs. This achieves the technical effect of significantly reducing the steady-state current fluctuations of hysteresis control and maintaining a constant switching frequency without reducing dynamic response performance.

Description

Technical Field

[0001] The present invention relates to the technical field of three-phase inverter current control, and in particular to a current hysteresis control method, device and electronic equipment for a permanent magnet synchronous motor. Background Art

[0002] Currently, the mainstream solutions for implementing three-phase current hysteresis control technology used in fields such as motor drive and inverter grid connection can be divided into two categories.

[0003] The first approach uses three sign functions to control each phase separately. This approach suffers from drastic changes in the inverter's switching frequency and high switching frequency, complicating power device selection. Furthermore, due to the mutual influence of the three-phase currents, the actual current can exceed the tolerance range by up to twice. Existing technologies have improved this approach, addressing the current out-of-tolerance drawback while maintaining a nearly constant switching frequency. However, its hardware and software implementation is quite complex.

[0004] The second type is to select a spatial voltage vector through a truth table in the dq coordinate system or the αβ coordinate system for control. Compared with the first type of method, this type of control reduces the number of switching times and eliminates the three-phase current coupling, but the switching frequency is still not constant. Moreover, this type of method involves coordinate transformation and the output of the voltage vector, which can often only be implemented by digital circuits. This will cause the control strategy to be limited by the sampling frequency and the delay of A / D conversion and digital circuit calculation, resulting in the actual current still exceeding the hysteresis tolerance range. Moreover, for permanent magnet synchronous motors (PMSMs), since the PMSM inductance is usually small, this current out-of-tolerance caused by the inherent defects of the digital control system often causes the current fluctuation to be unacceptable, affecting the steady-state performance of the system.

[0005] For the above problems, no effective solutions have been proposed yet. Summary of the Invention

[0006] The embodiments of the present invention provide a current hysteresis control method, device and electronic device for a permanent magnet synchronous motor, so as to at least solve the technical problems in the related art of current hysteresis control of the PMSM switching frequency being non-constant and the current steady-state fluctuation being large.

[0007] According to one aspect of an embodiment of the present invention, a current hysteresis control method for a permanent magnet synchronous motor is provided, comprising: determining a hysteresis output value of a predetermined axis based on current parameters of the predetermined axis in a dq coordinate system, wherein the current parameters include a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, 2; wherein 0 indicates that the actual current of the predetermined axis exceeds the upper limit of the hysteresis, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds the lower limit of the hysteresis; determining an output predetermined axis voltage instruction according to the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage instruction is directly output according to a voltage instruction output strategy, and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage instruction is calculated according to the voltage instruction output strategy, and the predetermined axis voltage instruction is output.

[0008] Optionally, the predetermined axis is any one of the d-axis and the q-axis, and the hysteresis output value of the predetermined axis is determined based on the current parameter of the predetermined axis in the dq coordinate system, and the calculation expression used is as follows:

[0009]

[0010] The subscript d(q) indicates that the d-axis and the q-axis are common, i hd Indicates the current tolerance range of the d-axis, i hq Indicates the current tolerance range of the q axis, represents the given current of the d-axis, Indicates the given current of the q axis, i d Indicates the actual current of the d-axis, i q Indicates the actual current of the q axis, X d Indicates the hysteresis output value of the d-axis, X q Indicates the hysteresis output value of the q-axis.

[0011] Optionally, the voltage instruction output strategy includes at least one of the following: when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 0, the d-axis voltage instruction is -1 / 3 of the bus voltage; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 1, the d-axis voltage instruction is a voltage calculated according to a first output voltage expression; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 2, the d-axis voltage instruction is 1 / 3 of the bus voltage; or, when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 0, the q-axis voltage instruction is -1 / 3 of the bus voltage; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 1, the q-axis voltage instruction is a voltage calculated according to a second output voltage expression; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 2, the q-axis voltage instruction is 2 / 3 of the bus voltage.

[0012] Optionally, the first output voltage expression is as follows:

[0013]

[0014]

[0015] Among them, U db Indicates the voltage corresponding to the d-axis voltage command, i d represents the actual current of the d-axis, Indicates the given current of the d-axis, i q Indicates the actual current of the q axis, Ri d Indicates the stator resistance corresponding to the actual current of the d-axis, Li q Indicates the stator inductance corresponding to the actual current of the q axis, ω e represents the electrical angular velocity, K represents the proportional coefficient, U ed represents the error voltage of the d-axis, b represents a constant, and sign represents a sign function.

[0016] Optionally, the method further comprises: determining whether to adjust the error voltage U of the d-axis according to the hysteresis output value of the d-axis of the previous beat ed Estimated value of Update, where if the hysteresis output value of the previous d-axis is 1, and the given current and actual current of the previous d-axis meet the first conditional expression or the second conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the d-axis in the previous shot db ; Otherwise, do not update The first conditional expression is:

[0017]

[0018] The second conditional expression is:

[0019]

[0020] in, Indicates the given current of the d-axis in the previous shot, i d(k-1) Indicates the actual current of the d-axis in the previous shot, i d(k) Indicates the given current of the d-axis of this beat.

[0021] Optionally, the second output voltage expression is as follows:

[0022]

[0023]

[0024] Among them, U qb Indicates the voltage corresponding to the q-axis voltage command, i d Indicates the actual current of the d-axis, i q represents the actual current of the q axis, Indicates the given current of the q axis, Ri q Indicates the stator resistance corresponding to the actual current of the q axis, Li d Indicates the stator inductance corresponding to the actual current of the d-axis, ω e represents the electrical angular velocity, ψ f represents the permanent magnet flux, K represents the proportional coefficient, U eq represents the error voltage of the q-axis, b represents a constant, and sign represents a sign function.

[0025] Optionally, the method further comprises: determining whether to adjust the error voltage U of the q-axis according to the hysteresis loop output value of the q-axis in the previous beat. eq Estimated value of Update, wherein, if the hysteresis loop output value of the previous q-axis is 1, and the given current and actual current of the previous q-axis meet the third conditional expression or the fourth conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the q axis in the previous beat qb ; Otherwise, do not update Wherein, the third conditional expression is:

[0026]

[0027] The fourth conditional expression is:

[0028]

[0029] in, Indicates the given current of the q axis in the previous shot, i q(k-1) Indicates the actual current of the q axis in the previous shot, i q(k) Indicates the given current of the q axis of this beat.

[0030] According to another aspect of an embodiment of the present invention, a current hysteresis control device for a permanent magnet synchronous motor is also provided, comprising: a first determination module, for determining a hysteresis output value of a predetermined axis based on current parameters of the predetermined axis in a dq coordinate system, wherein the current parameters include a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, 2; wherein 0 indicates that the actual current of the predetermined axis exceeds the upper limit of the hysteresis, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds the lower limit of the hysteresis; a second determination module, for determining an output predetermined axis voltage instruction based on the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage instruction is directly output according to the voltage instruction output strategy, and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage instruction is calculated according to the voltage instruction output strategy, and the predetermined axis voltage instruction is output.

[0031] According to another aspect of an embodiment of the present invention, an electronic device is provided, comprising: a processor; and a memory for storing processor-executable instructions; wherein the processor is configured to execute any one of the above-mentioned current hysteresis control methods for a permanent magnet synchronous motor.

[0032] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is further provided, wherein the computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any of the above-mentioned current hysteresis control methods for the permanent magnet synchronous motor.

[0033] In an embodiment of the present invention, a hysteresis output value of a predetermined axis is determined based on a current parameter of a predetermined axis in a dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds the upper hysteresis limit, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds the lower hysteresis limit; based on the hysteresis output value of the predetermined axis, a voltage command for the predetermined axis is determined; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage command is directly output according to a voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage command is calculated according to a voltage command output strategy and output. In other words, based on the current hysteresis control strategy in the dq coordinate system, the embodiment of the present invention adopts a vector synthesis method to synthesize a spatial voltage vector with a maximum amplitude and a relatively appropriate phase angle when the actual current is outside the current tolerance range, so as to quickly return the actual current to the current tolerance range. When the current is within the tolerance range, the error voltage is continuously iterated, and an appropriate voltage vector is synthesized according to the actual current error, so that the actual current always closely follows the given current, thereby keeping the switching frequency constant and avoiding the defect of the traditional hysteresis control that the amplitude and size of the output voltage cannot be freely adjusted, resulting in unnecessary current fluctuations. This solves the technical problems of the non-constant switching frequency and large steady-state current fluctuations of the current hysteresis control PMSM in the related technology, and achieves the technical effect of greatly reducing the steady-state current fluctuations of the hysteresis control and keeping the switching frequency constant without reducing the dynamic response performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0035] Figure 1 An overall control block diagram of a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0036] Figure 2 A flow chart of a current hysteresis control method for a permanent magnet synchronous motor provided by an embodiment of the present invention;

[0037] Figure 3 The error voltage U for the q axis provided by an optional embodiment of the present invention is eq Estimated value of A flowchart for updating;

[0038] Figure 4 The no-load time provided by the embodiment of the present invention and Schematic diagram of the identification situation;

[0039] Figure 5 The load time provided by the embodiment of the present invention and Schematic diagram of the identification situation;

[0040] Figure 6 A comparison chart of the dynamic performance of the method used in the present invention and the dynamic performance of FOC when the load is suddenly increased or decreased according to an embodiment of the present invention;

[0041] Figure 7 A schematic diagram of a current hysteresis control device for a permanent magnet synchronous motor provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to enable those skilled in the art to better understand the solutions of the present invention, 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 embodiments described 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 making creative efforts should fall within the scope of protection of the present invention.

[0043] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish different objects rather than to limit a specific order.

[0044] Figure 1 The overall control block diagram of the permanent magnet synchronous motor provided by the embodiment of the present invention is as follows: Figure 1 As shown, U dc After being processed by the three-phase inverter, the input is the permanent magnet synchronous motor PMSM, i a 、i b And θ is transformed by 3 / 2, 2 / 2 to get i d 、i q ;ω r The given speed is obtained through PI processing with i q Then it passes through the q-axis hysteresis loop and then the q-axis voltage command is output, that is, V q ; with i d After the d-axis hysteresis loop, the d-axis voltage command is output, that is, V d ; Further, V d With V q After space vector pulse width modulation (SVPWM), it is converted into U a 、U b 、U c, which are then input into the three-phase inverter. Compared to existing current hysteresis control methods, the current hysteresis control method for a permanent magnet synchronous motor provided by the present invention utilizes SVPWM vector synthesis, which can output a synthetic voltage vector with arbitrary amplitude and phase angle, maintaining a constant switching frequency for the motor.

[0045] Furthermore, taking the hidden-pole permanent magnet synchronous motor as an example, the voltage equation after discretization of the motor is:

[0046]

[0047] Among them, i d(k) 、i q(k) is the actual current of the dq axis at the Kth beat; i d(k-1) 、i q(k-1) is the actual current of the dq axis at the k-1th beat.

[0048] From the above formula, we can see that if the given amplitude is large enough, d 、V q , then its positive and negative will be related to the dq axis current change Δi d , Δi q The positive and negative of Δi d , Δi q The amplitude is also related to V d 、V q The amplitude of the voltage command is positively correlated. Therefore, if the actual current exceeds the tolerance range, a larger dq-axis voltage is output to quickly force the current back within the tolerance range. Once the actual current is within the tolerance range, the sign and amplitude of the voltage command must be carefully controlled to ensure that after the speed loop stabilizes, there will be no significant current fluctuations while the given current remains essentially unchanged.

[0049] Therefore, the current hysteresis control can be performed based on the given current.

[0050] According to one aspect of an embodiment of the present invention, a current hysteresis control method for a permanent magnet synchronous motor is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0051] Figure 2 Flowchart of the current hysteresis control method of the permanent magnet synchronous motor provided by the embodiment of the present invention, such as Figure 2 As shown, the method includes the following steps:

[0052] Step S202: Determine a hysteresis output value of the predetermined axis based on a current parameter of the predetermined axis in the dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds an upper limit of the hysteresis, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds a lower limit of the hysteresis.

[0053] Optionally, two three-level hysteresis comparators are provided in the dq rotating coordinate system, and different dq axis voltage instructions are output according to the output values ​​of the hysteresis comparators, so that the actual stator current closely follows the given value.

[0054] It should be noted that the above-mentioned dq coordinate system is composed of the d-axis and q-axis of the permanent magnet synchronous motor; the above-mentioned hysteresis output value is the output value of the hysteresis comparator corresponding to the predetermined axis; the above-mentioned actual current is the d-axis or q-axis current converted from the actual sampled three-phase current after coordinate transformation; the above-mentioned current tolerance range, also known as the current hysteresis range, includes the hysteresis upper limit and the hysteresis upper limit.

[0055] Step S204, determining the output predetermined axis voltage instruction based on the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage instruction is directly output according to the voltage instruction output strategy; when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage instruction is calculated according to the voltage instruction output strategy, and the predetermined axis voltage instruction is output.

[0056] In an embodiment of the present invention, a hysteresis output value of a predetermined axis is determined based on a current parameter of a predetermined axis in a dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds the upper hysteresis limit, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds the lower hysteresis limit; based on the hysteresis output value of the predetermined axis, a voltage command for the predetermined axis is determined; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage command is directly output according to a voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage command is calculated according to a voltage command output strategy and output. In other words, based on the current hysteresis control strategy in the dq coordinate system, the embodiment of the present invention adopts a vector synthesis method to synthesize a spatial voltage vector with a maximum amplitude and a relatively appropriate phase angle when the actual current is outside the current tolerance range, so as to quickly return the actual current to the current tolerance range. When the current is within the tolerance range, the error voltage is continuously iterated, and an appropriate voltage vector is synthesized according to the actual current error, so that the actual current always closely follows the given current, thereby keeping the switching frequency constant and avoiding the defect of the traditional hysteresis control that the amplitude and size of the output voltage cannot be freely adjusted, resulting in unnecessary current fluctuations. This solves the technical problems of the non-constant switching frequency and large steady-state current fluctuations of the current hysteresis control PMSM in the related technology, and achieves the technical effect of greatly reducing the steady-state current fluctuations of the hysteresis control and keeping the switching frequency constant without reducing the dynamic response performance.

[0057] In an optional embodiment, the predetermined axis is any one of the d-axis and the q-axis. The hysteresis output value of the predetermined axis is determined based on the current parameter of the predetermined axis in the dq coordinate system, and the calculation expression used is as follows:

[0058]

[0059] The subscript d(q) indicates that the d-axis and the q-axis are common, i hd Indicates the current tolerance range of the d-axis, i hq Indicates the current tolerance range of the q axis, represents the given current of the d-axis, Indicates the given current of the q axis, i d Indicates the actual current of the d-axis, i q Indicates the actual current of the q axis, X d Indicates the hysteresis output value of the d-axis, X q Indicates the hysteresis output value of the q-axis.

[0060] In an optional embodiment, the above-mentioned voltage instruction output strategy specifically relates to the following application scenarios: when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 0, the d-axis voltage instruction is -1 / 3 of the bus voltage; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 1, the d-axis voltage instruction is the voltage calculated according to the first output voltage expression; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 2, the d-axis voltage instruction is 1 / 3 of the bus voltage; or, when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 0, the q-axis voltage instruction is -1 / 3 of the bus voltage; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 1, the q-axis voltage instruction is the voltage calculated according to the second output voltage expression; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 2, the q-axis voltage instruction is 2 / 3 of the bus voltage.

[0061] In an optional implementation, the first output voltage expression is as follows:

[0062]

[0063]

[0064] Among them, U db Indicates the voltage corresponding to the d-axis voltage command, i d represents the actual current of the d-axis, Indicates the given current of the d-axis, i q Indicates the actual current of the q axis, Ri d Indicates the stator resistance corresponding to the actual current of the d-axis, Li q Indicates the stator inductance corresponding to the actual current of the q axis, ω e represents the electrical angular velocity, K represents the proportional coefficient, U ed represents the error voltage of the d-axis, b represents a constant, and sign represents a sign function.

[0065] In an optional embodiment, the above method further includes: determining whether to adjust the error voltage U of the d-axis according to the hysteresis output value of the d-axis of the previous beat ed Estimated value of Update, where if the hysteresis output value of the previous d-axis is 1, and the given current and actual current of the previous d-axis meet the first conditional expression or the second conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the d-axis in the previous shot db ; Otherwise, do not update

[0066] Furthermore, the first conditional expression is:

[0067]

[0068] In addition, the second conditional expression is:

[0069]

[0070] in, Indicates the given current of the d-axis in the previous shot, i d(k-1) Indicates the actual current of the d-axis in the previous shot, i d(k) Indicates the given current of the d-axis of this beat.

[0071] In an optional implementation, the second output voltage expression is as follows:

[0072]

[0073]

[0074] Among them, U qb Indicates the voltage corresponding to the q-axis voltage command, i d Indicates the actual current of the d-axis, i q represents the actual current of the q axis, Indicates the given current of the q axis, Ri q Indicates the stator resistance corresponding to the actual current of the q axis, Li d Indicates the stator inductance corresponding to the actual current of the d-axis, ω e represents the electrical angular velocity, ψ f represents the permanent magnet flux, K represents the proportional coefficient, U eq represents the error voltage of the q-axis, b represents a constant, and sign represents a sign function.

[0075] It should be noted that the dq-axis error voltage is equivalent to the sum of the permanent magnet back electromotive force, the dq-axis current mutual coupling term, and the resistance voltage drop.

[0076] Optionally, the error voltage is obtained by a current integrator; however, whether the integrator is activated in the current beat depends on whether the sign of the difference between the current of the current beat and the previous beat is as expected. If it is, the error voltage is not integrated; if not, the error voltage is integrated based on the error between the stored given current value of the previous beat and the actual current value multiplied by a fixed coefficient. After a certain period of integration, The value will be close to the actual U e(d)q At this point, when the hysteresis comparator output is 1, the control strategy is similar to deadbeat control. Clearly, as long as the value of K is appropriately chosen, the actual current will consistently track the set current. This avoids unnecessary current fluctuations caused by large voltage commands due to variations in the hysteresis comparator output, while also ensuring that the error between the actual current and the reference value is significantly smaller than the hysteresis bandwidth, eliminating steady-state fluctuations.

[0077] In an optional embodiment, the above method further includes: determining whether to adjust the error voltage U of the q-axis according to the hysteresis loop output value of the q-axis of the previous beat eq Estimated value of Update, wherein, if the hysteresis loop output value of the previous q-axis is 1, and the given current and actual current of the previous q-axis meet the third conditional expression or the fourth conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the q axis in the previous beat qb ; Otherwise, do not update

[0078] Furthermore, the third conditional expression is:

[0079]

[0080] In addition, the fourth conditional expression is:

[0081]

[0082] in, Indicates the given current of the q axis in the previous shot, i q(k-1) Indicates the actual current of the q axis in the previous shot, i q(k) Indicates the given current of the q axis of this beat.

[0083] Figure 3 The error voltage U for the q axis provided by an optional embodiment of the present invention is eq Estimated value of The updated flowchart is as follows: Figure 3 As shown, enter the k-beat interrupt, perform hysteresis comparison, and then judge X (k-1)q =1 is true, if so, then judge And i q(k) -i q(k-1) <0; if not, the q-axis voltage command V is output according to the hysteresis loop rule q Furthermore, if And i q(k) -i q(k-1) <0 holds true, then U eq =U qb(k-1) ;like And i q(k) -i q(k-1) <0 is not true, then continue to judge And i q(k) -i q(k-1) >0 is true; if And i q(k) -i q(k-1) >0 holds, then U eq =U qb(k-1) ;like And iq(k) -i q(k-1) >0 is not true, then the q-axis voltage command V is output according to the hysteresis loop rule q Until the kth beat interruption ends. It should be noted that based on the error voltage U eq Estimated value of Update, and similarly get the error voltage U on the d-axis ed Estimated value of to update.

[0084] Normally, the control strategy of d-axis current being 0 is adopted. Therefore, for d-axis, the resistance voltage drop Ri d and the influence of dq axis coupling ω e Li q The two are relatively small, so when the d-axis current exceeds the tolerance range, applying a small voltage to the d-axis can quickly bring it back to the current tolerance range, so the output voltage is

[0085] As for the q-axis, the back electromotive force of the permanent magnet will have a greater impact on the q-axis current and cause the q-axis current to decrease. And the q-axis current directly affects the torque. Therefore, when the q-axis current is small, its output is (i.e. the maximum vector amplitude in the SVPWM modulation limit circle) to make the q-axis current quickly track the given value. When the q-axis current is large, considering the influence of the permanent magnet back electromotive force, in order to make the rising and falling effects of the q-axis current basically the same, the output amplitude should be less than the maximum value, so take

[0086] When the hysteresis comparator is 1, U db and U qb The calculation is as follows:

[0087] In order to make the current change of each beat small enough so that the output value of the hysteresis comparator remains unchanged, and thus avoid unnecessary current fluctuations caused by the use of a voltage vector with a large amplitude in the steady state, when the hysteresis output is 1, the output voltage U db and U qb It should also be possible to make the actual current continuously approach the given value, that is, it should satisfy:

[0088]

[0089] Among them, U eq 、U ed The error voltages for the q and d axes are shown in Figure 1. K is the proportional coefficient, which enables the actual current to continuously track the given value even within the tolerance range.

[0090] For the selection of K, theoretically K should be L refis the rated inductance of the motor, and ΔT is the control period of one beat. This achieves a similar effect to deadbeat control in the inner loop. However, if K is calculated directly according to this formula, and considering the one-beat delay of the digital system, when the actual motor inductance is less than the given inductance, the system will diverge. Furthermore, considering the method proposed in this article, the dynamic performance of the system is essentially guaranteed by the hysteresis loop, so we only need to consider the value of K that can make the system stable. Therefore, K should be less than

[0091] Since the value of K is deliberately lowered, the actual current will continue to approach the given value during steady-state operation, but it is obvious that it cannot reach the given value, which will cause steady-state error. Therefore, the above expression can be corrected to:

[0092]

[0093] Where b is a small voltage constant set to avoid steady-state errors. The meaning of the sign function sign is as follows:

[0094]

[0095] After that, we need to consider U ed and U eq The calculation can get U db and U qb However, the resistance, inductance, and permanent magnet parameters of the motor will change during operation, and the output voltage will also be affected by unmodeled factors such as inverter dead zone and voltage drop. Therefore, U is calculated based on the PMSM model parameters. ed and U eq It is difficult to obtain satisfactory results, thus affecting the output voltage U db and U qb .

[0096] At the same time, considering that the digital system realizes hysteresis by first obtaining the actual current value and then comparing it with the given value, and finally obtaining a limited number of hysteresis output values, in fact, the effective current information is lost. Therefore, an integral solution strategy based on the current change information of two samples is used. By setting the integrator action condition, the integrator will act when the condition is met, and will not act when the condition is not met. ed and U eq Estimated value of and Calculate and use the estimated value instead of the true value for U db and U qb Calculation.

[0097] Taking the q axis as an example, the working principle of the integrator is as follows: In order to make the actual current within the tolerance area, it is also necessary to approach the given current as much as possible. Then at time k, we have

[0098] Further, according to The applied q-axis voltage should satisfy U qb(k) >U eq ; That is, there should be i q(k+1) >i q(k) If the current at time k+1 does not satisfy i q(k+1) >i q(k) , then there is U eq >U qb(k) Then let Then the calculation of the next beat is carried out. When the strategy is continuously updated Until the update

[0099] Since b is a small constant set to prevent static error, the final There will be high precision.

[0100] Furthermore, according to the above control strategy, the control board using DSP28335 as the main control chip is used to implement the above embodiment of the present invention. and Comparing the accuracy of the estimation with the current loop performance of a traditional dual-closed-loop PI control scheme and the dq-axis current fluctuations after steady state demonstrates the superiority of the above-described embodiment of the present invention. With the exception of the phase current waveform, which is directly read using an oscilloscope, the remaining waveforms are derived from data stored in the memory of the digital signal processing (DSP) chip. The speed waveform is read using the AD2S1210 resolver decoder chip.

[0101] Furthermore, the motor data used are as follows: the motor is surface mount; the number of pole pairs is 4; the rated power is 750W; the applied terminal voltage is consistent with the rated voltage, which is 220V; the rated speed is 3000rpm / min; the back EMF is 48V / 1000rpm; the moment of inertia is 1.82*10 -4 kg·m 2 The stator line resistance is 2.88Ω, and the dq-axis inductance is 9.6mH. The motor is loaded with a linear load and reaches a rated torque of 2.39Nm at a speed of 2500r / min.

[0102] Optionally, K is 0.375L ref / ΔT=36;b is 1V. Hysteresis loop width i hd =i hq =1A. The above embodiment of the present invention and the traditional PI speed loop PI parameter are K p =0.004; Ki =6*10 -6 Since the above embodiment of the present invention has similarities with PI in the control of the inner loop when the hysteresis loop output is 1, in order to be more objective, the traditional PI scheme current loop PI takes K p =36;K i =1.63.

[0103] Figure 4 The no-load time provided by the embodiment of the present invention and Schematic diagram of the identification situation, Figure 4 It can be seen that at a given speed n ref After the speed suddenly drops from 2500r / min to 1000r / min, the The value is reduced from 100 to 40, which is basically consistent with the nominal parameters of the motor. After returning to steady state, it remains basically unchanged at around 0, which is consistent with expectations.

[0104] Figure 5 The load time provided by the embodiment of the present invention and Schematic diagram of the identification situation, Figure 5 It can be seen that as the current increases, the resistance voltage drop increases and the dq axis coupling effect is enhanced. Under load, the identified There is a certain decline In addition, except for the transient process, the output of the hysteresis comparator is always 1, indicating that the current fluctuation in the steady state of the current hysteresis control is improved.

[0105] Figure 6 The following is a comparison chart of the dynamic performance of the method used in the present invention and the dynamic performance of the field oriented control (FOC) when the load is suddenly increased or decreased in accordance with the embodiment of the present invention. Figure 6 As shown in Figure 2, it can be seen from the changes in phase current that after sudden load increase and sudden load reduction, the dynamic performance of the current hysteresis control method using the permanent magnet synchronous motor is better than that of the traditional vector control.

[0106] According to another aspect of the embodiments of the present invention, a current hysteresis control device for a permanent magnet synchronous motor is provided. Figure 7 A schematic diagram of a current hysteresis control device for a permanent magnet synchronous motor according to an embodiment of the present invention is shown in FIG. Figure 7 As shown, the current hysteresis control device for the permanent magnet synchronous motor includes a first determination module 72 and a second determination module 74. The current hysteresis control device for the permanent magnet synchronous motor is described in detail below.

[0107] a first determining module 72 configured to determine a hysteresis output value of the predetermined axis based on a current parameter of the predetermined axis in a dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds an upper limit of the hysteresis band, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds a lower limit of the hysteresis band;

[0108] The second determination module 74 is connected to the above-mentioned first determination module 72, and is used to determine the output predetermined axis voltage instruction based on the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage instruction is directly output according to the voltage instruction output strategy; when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage instruction is calculated according to the voltage instruction output strategy, and the predetermined axis voltage instruction is output.

[0109] It should be noted here that the above-mentioned first determination module 72 and second determination module 74 correspond to steps S202 to S204 in the method embodiment. The examples and application scenarios implemented by the above-mentioned modules and corresponding steps are the same, but are not limited to the contents disclosed in the above-mentioned method embodiment.

[0110] In an embodiment of the present invention, the current hysteresis control device for a permanent magnet synchronous motor uses current parameters of a predetermined axis in a dq coordinate system to determine a hysteresis output value of the predetermined axis, wherein the current parameters include a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds the upper limit of the hysteresis, 1 indicates that the actual current of the predetermined axis is within the current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds the lower limit of the hysteresis; and based on the hysteresis output value of the predetermined axis, a voltage command for the predetermined axis is outputted; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the given predetermined axis voltage command is directly outputted according to the voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage command is calculated according to the voltage command output strategy and outputted. In other words, the embodiment of the present invention uses a vector synthesis method based on the current hysteresis control strategy in the dq coordinate system to synthesize a spatial voltage vector with the largest amplitude and a relatively appropriate phase angle when the actual current is outside the current tolerance range, so that the actual current quickly returns to the current tolerance range. When the current is within the tolerance range, the error voltage is continuously iterated, and an appropriate voltage vector is synthesized according to the actual current error, so that the actual current always closely follows the given current, thereby keeping the switching frequency constant and avoiding the defect of the traditional hysteresis control that the amplitude and size of the output voltage cannot be freely adjusted, resulting in unnecessary current fluctuations. This solves the technical problems of the non-constant switching frequency and large steady-state current fluctuations of the current hysteresis control PMSM in the related technology, and achieves the technical effect of greatly reducing the steady-state current fluctuations of the hysteresis control and keeping the switching frequency constant without reducing the dynamic response performance.

[0111] According to another aspect of an embodiment of the present invention, an electronic device is provided, comprising: a processor; and a memory for storing instructions executable by the processor; wherein the processor is configured to execute any one of the above-mentioned current hysteresis control methods for a permanent magnet synchronous motor.

[0112] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is further provided, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any of the above-mentioned current hysteresis control methods for a permanent magnet synchronous motor.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A current hysteresis control method for a permanent magnet synchronous motor, characterized in that: include: Determining a hysteresis output value of a predetermined axis based on a current parameter of the predetermined axis in a dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds an upper limit of the hysteresis band, 1 indicates that the actual current of the predetermined axis is within a current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds a lower limit of the hysteresis band; Determining a predetermined axis voltage command to be output according to the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, directly outputting the given predetermined axis voltage command according to a voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, calculating the predetermined axis voltage command according to the voltage command output strategy and outputting the predetermined axis voltage command; The voltage command output strategy includes at least one of the following: When the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 0, the d-axis voltage command is -1 / 3 of the bus voltage; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 1, the d-axis voltage command is a voltage calculated according to the first output voltage expression; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 2, the d-axis voltage command is 1 / 3 of the bus voltage; or, When the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 0, the q-axis voltage command is -1 / 3 of the bus voltage; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 1, the q-axis voltage command is a voltage calculated according to the second output voltage expression; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 2, the q-axis voltage command is 2 / 3 of the bus voltage; The first output voltage expression is as follows: Among them, U db Indicates the voltage corresponding to the d-axis voltage command, i d represents the actual current of the d-axis, Indicates the given current of the d-axis, i q represents the actual current of the q axis, R represents the stator resistance, L represents the stator inductance, ω e represents the electrical angular velocity, K represents the proportional coefficient, U ed represents the error voltage of the d-axis, b represents a constant, and sign represents a sign function.

2. The method according to claim 1, characterized in that The predetermined axis is any one of the d-axis and the q-axis. Based on the current parameter of the predetermined axis in the dq coordinate system, the hysteresis output value of the predetermined axis is determined. The calculation expression used is as follows: The subscript d(q) indicates that the d-axis and the q-axis are common, i hd Indicates the current tolerance range of the d-axis, i hq Indicates the current tolerance range of the q axis, represents the given current of the d-axis, Indicates the given current of the q axis, i d Indicates the actual current of the d-axis, i q Indicates the actual current of the q axis, X d Indicates the hysteresis output value of the d-axis, X q Indicates the hysteresis output value of the q-axis.

3. The method according to claim 1, characterized in that The method further comprises: Determine whether to adjust the error voltage U of the d-axis according to the hysteresis loop output value of the previous d-axis ed Estimated value of Update, where if the hysteresis output value of the previous d-axis is 1, and the given current and actual current of the previous d-axis meet the first conditional expression or the second conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the d-axis in the previous shot db ; Otherwise, do not update The first conditional expression is: The second conditional expression is: in, Indicates the given current of the d-axis in the previous shot, i d(k-1) Indicates the actual current of the d-axis in the previous shot, i d(k) Indicates the given current of the d-axis of this beat.

4. The method according to claim 1, wherein The second output voltage expression is as follows: Among them, U qb Indicates the voltage corresponding to the q-axis voltage command, i d Indicates the actual current of the d-axis, i q represents the actual current of the q axis, represents the given current of the q axis, R represents the stator resistance, L represents the stator inductance, ω e represents the electrical angular velocity, ψ f represents the permanent magnet flux, K represents the proportional coefficient, U eq represents the error voltage of the q-axis, b represents a constant, and sign represents a sign function.

5. The method according to claim 4, characterized in that The method further comprises: Determine whether to adjust the error voltage U of the q-axis according to the hysteresis loop output value of the previous q-axis eq Estimated value of Update, wherein, if the hysteresis loop output value of the previous q-axis is 1, and the given current and actual current of the previous q-axis meet the third conditional expression or the fourth conditional expression, then Equal to the voltage U corresponding to the voltage instruction of the q axis in the previous beat qb ; Otherwise, do not update Wherein, the third conditional expression is: The fourth conditional expression is: in, Indicates the given current of the q axis in the previous shot, i q(k-1) Indicates the actual current of the q axis in the previous shot, i q(k) Indicates the given current of the q axis of this beat.

6. A current hysteresis control device for a permanent magnet synchronous motor, characterized in that: include: a first determining module, configured to determine a hysteresis output value of a predetermined axis based on a current parameter of the predetermined axis in a dq coordinate system, wherein the current parameter includes a current tolerance range, a given current, and an actual current, and the hysteresis output value of the predetermined axis includes at least one of the following: 0, 1, or 2; wherein 0 indicates that the actual current of the predetermined axis exceeds an upper limit of the hysteresis band, 1 indicates that the actual current of the predetermined axis is within a current tolerance range, and 2 indicates that the actual current of the predetermined axis exceeds a lower limit of the hysteresis band; A second determination module is configured to determine a predetermined axis voltage command to be output based on the hysteresis output value of the predetermined axis; wherein, when the hysteresis output value of the predetermined axis is 0 or 2, the predetermined axis voltage command is directly output according to a voltage command output strategy; and when the hysteresis output value of the predetermined axis is 1, the predetermined axis voltage command is calculated according to the voltage command output strategy and outputted; the voltage command output strategy includes at least one of the following: When the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 0, the d-axis voltage command is -1 / 3 of the bus voltage; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 1, the d-axis voltage command is a voltage calculated according to the first output voltage expression; when the predetermined axis is the d-axis and the hysteresis output value of the d-axis is 2, the d-axis voltage command is 1 / 3 of the bus voltage; or, When the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 0, the q-axis voltage command is -1 / 3 of the bus voltage; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 1, the q-axis voltage command is a voltage calculated according to the second output voltage expression; when the predetermined axis is the q-axis and the hysteresis output value of the q-axis is 2, the q-axis voltage command is 2 / 3 of the bus voltage; The first output voltage expression is as follows: Among them, U db Indicates the voltage corresponding to the d-axis voltage command, i d represents the actual current of the d-axis, Indicates the given current of the d-axis, i q represents the actual current of the q axis, R represents the stator resistance, L represents the stator inductance, ω e represents the electrical angular velocity, K represents the proportional coefficient, U ed represents the error voltage of the d-axis, b represents a constant, and sign represents a sign function.

7. An electronic device, characterized in that: include: processor; a memory for storing processor-executable instructions; The processor is configured to execute the current hysteresis control method for a permanent magnet synchronous motor according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the current hysteresis control method of the permanent magnet synchronous motor according to any one of claims 1 to 7.

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