Method, device, storage medium and servo drive for expanding current loop bandwidth

Abstract

The present application relates to a method, device, storage medium and servo driver for expanding the current loop bandwidth. The method includes performing multiple current reconstructions through single current sampling within one carrier period, thereby achieving multiple PWM duty cycle updates within one carrier period. Without increasing the current sampling frequency, the present application solves the problem of low bandwidth in the existing single current sampling of the current loop, and at the same time overcomes the limitations of the hardware circuit. By flexibly setting the number of PWM duty cycle updates through software, the loop delay of the current loop is effectively reduced and the current loop bandwidth is increased.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet synchronous motor control, and particularly relates to a method, device, storage medium, and servo driver for expanding the current loop bandwidth. Background Art

[0002] At present, the main control method for permanent magnet synchronous motors is field-oriented control, which adopts a three-loop cascade control structure. The innermost loop is the current control loop, the middle loop is the speed control loop, and the outermost loop is the position control loop. As the inner loop of the permanent magnet synchronous motor vector control system, the bandwidth of the current loop directly affects the performance of the speed loop and the position loop.

[0003] In a servo control system, the micro control unit (MCU) of the permanent magnet synchronous motor control system generally uses a digital signal processor. Due to the discrete characteristics of the digital system, a certain amount of calculation delay will be introduced during the control process. At the same time, considering the system hardware cost and power device loss, the switching frequency of the power devices in the inverter cannot be increased without limit. Therefore, the main factors restricting the current loop bandwidth are the delay of the digital system and the switching frequency of the power devices. Increasing the switching frequency of the power devices can increase the current loop bandwidth, but it will increase the system cost. Therefore, increasing the switching frequency of the power devices is not very meaningful.

[0004] It can be known from the disclosed technology that the current loop bandwidth is inversely proportional to the system delay. Therefore, reducing the loop delay of the digital system is of great significance for improving the control performance of the servo system. The general execution timing of the current loop in engineering is to perform current sampling once within a PWM carrier period, and at the same time, combined with relevant transformations and the principle of space vector pulse width modulation, perform duty cycle update once. Due to the serial calculation characteristics of the digital signal processor, a certain amount of current sampling and calculation delay will be introduced, and at the same time, there will also be a certain delay between the duty cycle update and the output corresponding voltage of the inverter. Therefore, the bandwidth of the current loop is greatly restricted.

[0005] Regarding the problem of bandwidth reduction caused by delay, relevant researchers proposed to perform multiple current samplings and multiple duty cycle updates within a PWM carrier period. Although this solution can effectively reduce the delay of the digital system, due to the too high sampling frequency, the requirements for the microprocessor are relatively high, which will make the digital signal processor in a high-frequency sampling state, greatly increasing the calculation load of the microprocessor and affecting the execution timing of other programs, reducing the working efficiency of the microprocessor.

[0006] In view of the problem that the bandwidth of the existing current loop is relatively low during a single current sampling without increasing the current sampling frequency in the related technology, no effective solution has been proposed yet. Summary of the Invention

[0007] The present invention provides a method, device, storage medium, and servo driver for expanding the current loop bandwidth to solve the problem of low bandwidth during a single current sampling in the existing current loop without increasing the current sampling frequency in the related art.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] Set the switching frequency of the power device of the servo driver to which the current loop belongs, the number of PWM duty cycle updates N within one carrier period, and the corresponding current sampling period and PWM duty cycle update period;

[0010] Perform current sampling at the start of the carrier in the k-th PWM period to obtain a current sampling value, and obtain the d-axis current reference value I d ref(k) and the q-axis current reference value I q ref(k); where k is any natural number from 1 to N;

[0011] Calculate the first d-axis current i d1 (k) and the first q-axis current i q1 (k) required for the first calculation of the duty cycle according to the current sampling value, where i d1 (k) = i d (k), i q1 (k) = i q (k), and combine the corresponding transformation and the space vector pulse width modulation principle to calculate the PWM duty cycle for the first time within the k-th period, and wait until the update moment to update the PWM duty cycle;

[0012] Reconstruct the current required for the n-th duty cycle update within the k-th PWM period, calculate the corresponding PWM duty cycle, and determine whether it reaches the position of the n-th duty cycle update in the K-th period. If it reaches, perform the duty cycle update until the update times reach N; where the current required for the n-th duty cycle update is calculated based on the current required for the (n - 1)-th duty cycle update, and n is a natural number greater than 1 and less than or equal to N.

[0013] Preferably, perform current sampling at the start position of the K-th PWM carrier period, and perform relevant calculations to obtain the first d-axis current i d1 (k), the first q-axis current i q1 (k), calculate the first duty cycle according to i d1 (k), i q1 (k), and update the PWM duty cycle. Calculate the current reference value I d1 ref(k), I q1 ref(k).

[0014] Preferably, according to the first d-axis current i d1 (k), the first q-axis current i q1 (k) and the current reference value I d1 ref(k), I q1 ref(k), the current deviation value e d1 (k) can be obtained at this time, e q1 (k), that is

[0015]

[0016] Preferably, when reconstructing the current required for the second duty ratio update within the Kth PWM period, according to the current deviation e d1 (k), e q1 (k), the current i d2 (k) required for calculating the second duty ratio can be reconstructed, i q2 (k),

[0017]

[0018] Among them, the variables x and y respectively represent the incremental adjustment coefficients of the d-axis current and the q-axis current.

[0019] Preferably, when calculating the nth duty ratio within the Kth PWM period,

[0020]

[0021] Among them, I dn-1 ref(k), I qn-1 ref(k) are respectively the d-axis current reference value and the q-axis current reference value calculated by the (n - 1)th duty ratio update within the Kth period. i dn (k) represents the nth d-axis current in the Kth period, i dn-1 (k) represents the (n - 1)th d-axis current in the Kth period, i qn (k) represents the nth q-axis current in the Kth period, i qn-1 (k) represents the (n - 1)th q-axis current in the Kth period.

[0022] Preferably, by adjusting the magnitudes of the variable x and the variable y, the incremental magnitudes of the d-axis current and the q-axis current are respectively adjusted to improve the current response effect, where the value ranges of the coefficients x and y are:

[0023]

[0024] Preferably, within the same PWM carrier cycle, when the number of switching times of the power device is greater than 1, limit processing is performed on the output PWM.

[0025] Preferably, when the triangular carrier counts up, the PWM output is determined by the first equality of the timer comparison value and the triangular carrier. When the triangular carrier counts down, the PWM output is determined by the first equality of the timer comparison value and the triangular carrier.

[0026] Matched with the above method, on the other hand, the present invention provides an apparatus for expanding the current loop bandwidth, including: a parameter setting unit for setting the switching frequency of the power device of the servo driver to which the current loop belongs, the number N of PWM updates within one carrier cycle, and the corresponding current sampling period and PWM update period; a current sampling unit for sampling the current at the start moment of the carrier in the Kth PWM period; a current control unit for making the current required for the first calculation of the duty cycle equal to the current sampling value according to the current sampling value, that is, i d1 (k) = i d (k), i q1 (k) = i q (k), calculating the current required for the nth duty cycle update within the Kth PWM period according to the set formula; a PWM duty cycle control unit for calculating the first PWM duty cycle within the Kth period, waiting until the update moment and updating the duty cycle. When calculating the nth PWM duty cycle within the Kth period, it is judged whether the nth duty cycle update position within the Kth period is reached. If it is reached, the duty cycle is updated; the parameter setting unit judges whether the set number N of duty cycle updates is reached. When the update times reach the set value N, it enters the next cycle, where the current required for the nth duty cycle update is calculated based on the current required for the (n - 1)th duty cycle update, and n is a natural number greater than 1 and less than or equal to N.

[0027] Matched with the above method, on the other hand, the present invention provides a storage medium, including: a plurality of instructions are stored in the storage medium; the plurality of instructions are used to be loaded and executed by a processor to perform the above-mentioned method for expanding the current loop bandwidth.

[0028] Matched with the above method, on the other hand, the present invention provides a servo driver, including: a processor for executing a plurality of instructions; a memory for storing a plurality of instructions; wherein, the plurality of instructions are used to be stored by the memory and loaded and executed by the processor to perform the above-mentioned method for expanding the current loop bandwidth.

[0029] Compared with the related art, a method, device, storage medium, and servo drive for expanding the current loop bandwidth provided in this embodiment solve the problem of low bandwidth during single sampling of the existing current loop. At the same time, it overcomes the limitations of the hardware circuit. The duty cycle update times can be flexibly set through software. Through single current sampling and multiple current reconstructions, multiple duty cycle updates within one carrier period are achieved, which can effectively reduce the current loop delay and improve the current loop bandwidth.

[0030] Details of one or more embodiments of this application are presented in the following drawings and description to make other features, objectives, and advantages of this application more concise and understandable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of this application and form a part of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0032] Figure 1 is a flowchart of a method for expanding the current loop bandwidth in this embodiment;

[0033] Figure 2 is a flowchart of a method for realizing N PWM duty cycle updates with single current sampling in this embodiment;

[0034] Figure 3 is a flowchart of a method for reconstructing the current required for PWM duty cycle update in this embodiment;

[0035] Figure 4 is a preferred flowchart of a method for expanding the current loop bandwidth in this embodiment;

[0036] Figure 5 is a schematic diagram of a sampling update process in this embodiment;

[0037] Figure 6 is a structural block diagram of a device for expanding the current loop bandwidth in this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] To understand the purpose, technical solution, and advantages of this application more clearly, the following describes and explains this application in combination with the drawings and embodiments.

[0039] Unless otherwise defined, technical or scientific terms used in this application shall have the ordinary meanings as understood by those of ordinary skill in the technical field to which this application pertains. In this application, words such as "a", "an", "one kind", "the", "these", etc. do not indicate a limitation in quantity and can be singular or plural. Terms such as "include", "comprise", "have" and any variations thereof in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent in these processes, methods, products or devices. Terms such as "connect", "be connected", "couple" and the like in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The term "plurality" in this application refers to two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. Usually, the character " / " indicates that the objects associated before and after are in an "or" relationship. Terms such as "first", "second", "third", etc. in this application are only used to distinguish similar objects and do not represent a specific order for the objects.

[0040] The method embodiment provided in this embodiment may be executed in a terminal, a computer or a similar computing device. The terminal may include one or more processors and a memory for storing data. Among them, the processor may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA. The above terminal may further include a transmission device for communication functions and input / output devices.

[0041] The memory may be used to store computer programs, for example, software programs and modules of application software. The processor executes various functional applications and data processing by running the computer programs stored in the memory, that is, the above-mentioned method is implemented. The memory may include a high-speed random access memory and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some instances, the memory may further include a memory remotely set relative to the processor, and these remote memories may be connected to the terminal through a network. Examples of the above network include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network and their combinations.

[0042] In this embodiment, a method for expanding the current loop bandwidth is provided. Figure 1 is a flowchart of the method for expanding the current loop bandwidth in this embodiment, as Figure 1As shown, the process includes the following steps:

[0043] Step S110, set the switching frequency of the power device of the servo driver to which the current loop belongs, the number of PWM duty cycle updates N within one carrier period, and the corresponding current sampling period and PWM duty cycle update period.

[0044] Step S120, perform current sampling at the start moment of the k-th PWM cycle carrier to obtain current sampling values i d (k) and i q (k), and obtain the d-axis current reference value I d ref(k) and the q-axis current reference value I q ref(k), where k is any natural number from 1 to N.

[0045] Step S130, calculate the first d-axis current i d1 (k) and the first q-axis current i q1 (k) required for the first duty cycle calculation according to the current sampling values, where i d1 (k) = i d (k), i q1 (k) = i q (k), and combine the corresponding transformation and the space vector pulse width modulation principle to calculate the first PWM duty cycle within the k-th cycle, and wait until the update moment to update the PWM duty cycle.

[0046] Specifically, starting from the start moment of the k-th PWM carrier cycle, perform one current sampling to obtain current sampling values i d (k) and i q (k); based on the first current sampling values i d (k) and i q (k), calculate the first d-axis current i d1 (k) and the first q-axis current i q1 (k) required for the first duty cycle calculation respectively; combine the corresponding transformation and the space vector pulse width modulation principle to calculate the first PWM duty cycle within the k-th cycle, and wait until the update moment to update the PWM duty cycle, where the update moment is determined according to the number of PWM duty cycle updates N set by the system within one carrier period, and there are N update moments within one carrier period. The first duty cycle update updates the PWM duty cycle when the carrier reaches the first update moment.

[0047] Step S140: Reconstruct the current required for the nth duty cycle update within the kth PWM cycle, calculate the corresponding PWM duty cycle, and determine whether it reaches the nth duty cycle update moment of the Kth cycle. If it reaches, perform the duty cycle update until the update count reaches N. The current required for the nth duty cycle update is calculated based on the current required for the (n - 1)th duty cycle update, where n is a natural number greater than 1 and less than or equal to N.

[0048] Specifically, according to the determined corresponding PWM duty cycle, the PWM duty cycle of the current loop is updated N times successively at the corresponding moments from the 1st update moment to the Nth update moment, so as to achieve N updates of the PWM duty cycle of the current loop in the current carrier cycle. When the update count reaches N, the update step of the duty cycle of the current carrier cycle ends, then enters the next cycle, and the steps of S120 - S140 are executed cyclically. The specific sampling and update process is as Figure 5 shown.

[0049] Through the above steps, in this application, within one carrier cycle, single - time current sampling is adopted, and multiple current reconstructions are carried out by combining the current sampling value, current deviation, and tangent function, so as to achieve multiple updates of the duty cycle within one carrier cycle. By flexibly setting the duty cycle update count through software, the hardware limitation is overcome, the flexible control of the duty cycle update count is realized, the delay of the digital system is effectively reduced, the current loop bandwidth is improved, and the problem of high current sampling frequency within one carrier cycle in the existing PWM update strategy is solved.

[0050] In some of these embodiments, in combination with Figure 2 the flowchart of the method for realizing N PWM duty cycle updates with one - time current sampling in this embodiment shown, the specific process of performing one - time current sampling on the current of the current loop in step S140 and successively updating the PWM duty cycle of the current loop N times at the corresponding moments from the 1st update moment to the Nth update moment is further described. As Figure 2 shown, this process includes the following steps:

[0051] Step S210: At the starting moment of the current carrier cycle, perform the 1st current sampling within the current carrier cycle, and calculate the first d - axis current i d1 (k) and the first q - axis current i q1 (k) required for the first duty cycle update. Combine the corresponding transformation and the space vector pulse width modulation principle to calculate the PWM duty cycle for the first time within the kth cycle, and wait until the first update moment to update the PWM duty cycle.

[0052] Step S220: After completing the first PWM duty cycle update within the current carrier cycle, calculate the current reference value I d1 ref(k), Iq1 ref(k), based on the first d-axis current i d1 (k), the first q-axis current i q1 (k) and the current reference value I d1 ref(k), I q1 ref(k), obtain the current deviation value e d1 (k), e q1 (k), calculate the current i d2 (k) required for the second duty ratio update q2 (k), wait until the second update moment to update the PWM duty ratio.

[0053] Step S230, and so on. After completing N - 1 PWM duty ratio updates within the current carrier period, calculate the current i dn (k) required for the Nth duty ratio update qn (k), wait until the Nth update moment to update the PWM duty ratio.

[0054] Thus, by performing the first current sampling within the current carrier period at the starting moment of the current carrier period, and calculating the current required for the first PWM duty ratio update based on the first current sampling value, waiting for the first update moment to update the PWM duty ratio, calculating the current required for the second PWM duty ratio update based on the current required for the first PWM duty ratio update, waiting for the second update moment to update the PWM duty ratio, and so on, it is possible to achieve multiple current reconstructions with one current sampling to reach N PWM duty ratio updates. The operation method is simple, the reduction of the current loop delay time is large, and the control accuracy is high.

[0055] In this embodiment, a method for reconstructing the current required for PWM duty ratio update is also provided. Figure 3 It is a flowchart of a method for reconstructing the current required for PWM duty ratio update in this embodiment, as Figure 3 shown, and this process includes the following steps:

[0056] Step S310, based on the current sampling value at the starting moment of the kth PWM carrier period, obtain the first d-axis current i d1 (k) required for the first PWM duty ratio update, the first q-axis current i q1 (k);

[0057] Step S320, based on the first d-axis current i d1 (k) required for the first PWM duty ratio update within the kth PWM carrier period, the first q-axis current i q1 (k), calculate the current reference value I d1 ref(k), I q1ref(k), and based on the first d-axis current i d1 (k), the first q-axis current i q1 (k), the current reference value I d1 ref(k) and I q1 ref(k), calculate the current i d2 (k) required for the second duty cycle update, i q2 (k);

[0058] Step S330, calculate the current i dn (k) required for the nth duty cycle update based on the current required for the (n - 1)th PWM duty cycle update within the kth PWM carrier period, i qn (k);

[0059] Step S340, repeatedly execute Step S330 until n is equal to N, the process ends, and enter the next carrier period.

[0060] Through the above steps, by performing one current sampling and multiple duty cycle updates within one PWM carrier period, without increasing the current sampling frequency, the delay of the digital system is effectively reduced, and the problem of low bandwidth in the existing current loop during single current sampling is solved.

[0061] In some of these embodiments, the method for reconstructing the current calculation required for the nth duty cycle update within the kth PWM period includes:

[0062] Based on the first d-axis current i d1 (k), the first q-axis current i q1 (k), and the current reference values I d1 ref(k), I q1 ref(k), obtain the current deviation value e d1 (k), e q1 (k), that is

[0063]

[0064] Based on the current deviation e d1 (k), e q1 (k), reconstruct the current i d2 (k) required for the second duty cycle calculation, i q2 (k),

[0065]

[0066] where the variables x and y respectively represent the incremental adjustment coefficients of the d-axis current and the q-axis current.

[0067] During the nth duty cycle calculation in the Kth PWM cycle,

[0068]

[0069] where I dn-1 ref(k) and I qn-1 ref(k) are the d-axis current reference value and q-axis current reference value calculated by the (n - 1)th duty cycle update in the Kth cycle respectively. i dn (k) represents the nth d-axis current in the Kth cycle, i dn-1 (k) represents the (n - 1)th d-axis current in the Kth cycle, i qn (k) represents the nth q-axis current in the Kth cycle, i qn-1 (k) represents the (n - 1)th q-axis current in the Kth cycle. By adjusting the magnitudes of the variable x and variable y, the increment magnitudes of the d-axis current and q-axis current are adjusted respectively to improve the current response effect, where:

[0070] According to the current error, the value ranges of the coefficients x and y are:

[0071]

[0072] In formula (4): e dn-1 and e qn-1 are the d-axis and q-axis current deviations, and their values are:

[0073]

[0074] According to formulas (4) and (5), the ranges of the coefficients x and y can be obtained as:

[0075]

[0076] In an alternative example, within the same PWM carrier cycle, when the number of switching times of the power device is greater than 1, the output PWM is restricted. When the triangular carrier counts up, when the timer comparison value is equal to the triangular carrier for the first time, the PWM starts to be output. When the triangular carrier counts down, when the timer comparison value is equal to the triangular carrier for the first time, the PWM stops being output. Specifically, through the above restriction rules, the switching frequency of the switching device can be restricted to a given frequency.

[0077] The following describes and illustrates this embodiment through preferred embodiments.

[0078] Figure 4 is the preferred flowchart of a method for expanding the current loop bandwidth of this embodiment. As Figure 4 shown, the method for expanding the current loop bandwidth includes the following steps:

[0079] Step S410: Turn on the device and determine whether the system is working properly. If the system is normal, proceed to the next step; otherwise, end the process.

[0080] Step S420: When it is determined that the system is working properly, set the switching frequency of the power device of the servo driver to which the current loop belongs, the number N of PWM duty cycle updates within one carrier period, and the corresponding current sampling period and PWM duty cycle update period.

[0081] Step S430: At the start moment of the k-th carrier period, perform current sampling.

[0082] Step S440: Assign the first current sampling value to the first d-axis current i d1 (k) and the first q-axis current i q1 (k). Update the PWM duty cycle at the first PWM duty cycle update moment, and reconstruct the n-th d-axis current i dn (k) and the n-th q-axis current i qn (k) required for the n-th PWM duty cycle update, and update the PWM duty cycle at the n-th PWM duty cycle update moment.

[0083] Step S450: Repeat Step S440 until n = N, end the process, and enter the next carrier period.

[0084] It should be noted that the steps shown in the above process or the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0085] In this embodiment, an apparatus for expanding the current loop bandwidth is also provided. This apparatus is used to implement the above embodiment and the preferred implementation manners, and those that have been described will not be repeated here. The following terms such as "module", "unit", "sub-unit", etc. can be a combination of software and / or hardware that can achieve a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0086] Figure 6 is a structural block diagram of an apparatus for expanding the current loop bandwidth in this embodiment. As Figure 6 shown, the apparatus includes: a parameter setting unit 10, a current sampling unit 20, a current control unit 30, and a PWM duty cycle control unit 40.

[0087] A parameter setting unit 10 is configured to set the switching frequency of the power device of the servo driver to which the current loop belongs, the number N of PWM duty cycle updates within one carrier period, and the corresponding current sampling period and PWM duty cycle update period when the servo driver to which the current loop belongs meets different working conditions.

[0088] A current sampling unit 20 is configured to perform a current sampling on the current of the current loop once starting from the starting moment of the current carrier period within each carrier period of the servo driver to which the current loop belongs, and obtain a current sampling value i d (k), i q (k).

[0089] A current control unit 30 is configured to calculate the current required for PWM wave duty cycle update according to the current sampling value starting from the starting moment of the current carrier period within each carrier period of the servo driver to which the current loop belongs. The specific calculation process can refer to the above steps S310 - S340.

[0090] A PWM duty cycle control unit 40 is configured to update the PWM duty cycle of the current loop N times in sequence at the starting moment of the current carrier period of the servo driver to which the current loop belongs and / or at the corresponding moments from the 1st update moment to the Nth update moment, so as to achieve N PWM duty cycle updates for one current sampling of the current loop within the current carrier period.

[0091] For the specific functions and processing of the current control unit 30, refer to step S140. Specifically, starting from the starting moment of the current carrier period, the current sampling unit 20 performs a current sampling, and the current control unit 30 assigns the current sampling value to the first d-axis current i d1 (k), the first q-axis current i q1 (k), that is: i d1 (k) = i d (k), i q1 (k) = i q (k). Combining the corresponding transformation and the space vector pulse width modulation principle, calculate the PWM duty cycle for the first time within the kth period, wait until the first update moment to update the PWM duty cycle, calculate the current reference value I d1 ref(k), I q1 ref(k). According to the first d-axis current i d1 (k), the first q-axis current i q1 (k) and the current reference values I d1 ref(k), I q1 ref(k), obtain the current deviation value e d1 (k), e q1(k), calculate the current i required for the second duty cycle update d2 (k), i q2 (k), wait until the second update moment to update the PWM duty cycle, and so on, calculate the current i required for the nth duty cycle update dn (k), i qn (k), wait until the nth update moment to update the PWM duty cycle, until n = N, the process ends, and enter the next carrier cycle.

[0092] Thus, by setting the switching frequency of the power device of the servo driver belonging to the current loop, the number of PWM duty cycle updates N within one carrier cycle, and the corresponding current sampling period and PWM duty cycle update period, and performing N updates on the PWM duty cycle of the current loop in sequence at the starting moment and / or the corresponding moments from the 1st update moment to the Nth update moment, the delay time of the current loop control can be reduced, the current loop bandwidth can be increased, and the control method is simple and the control effect is high.

[0093] It should be noted that the above-mentioned each module can be a functional module or a program module, and can be implemented either by software or by hardware. For the modules implemented by hardware, the above-mentioned each module can be located in the same processor; or the above-mentioned each module can also be located in different processors in any combination form.

[0094] According to an embodiment of the present invention, there is also provided a servo driver corresponding to the method for expanding the current loop bandwidth. The servo driver may include: a processor for executing a plurality of instructions; a memory for storing a plurality of instructions; wherein, the plurality of instructions are used to be stored by the memory and loaded and executed by the processor to perform the above method for expanding the current loop bandwidth.

[0095] In this embodiment, there is also provided an electronic device, including a memory and a processor, and a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0096] Optionally, the above-mentioned electronic device may further include a transmission device and an input / output device, wherein, the transmission device is connected to the above-mentioned processor, and the input / output device is connected to the above-mentioned processor.

[0097] Optionally, in this embodiment, the above-mentioned processor may be configured to execute the following steps through a computer program:

[0098] S1, set the switching frequency of the power device of the servo driver belonging to the current loop, the number of PWM duty cycle updates N within one carrier cycle, and the corresponding current sampling period and PWM duty cycle update period;

[0099] S2. At the starting moment of the carrier wave in the k-th PWM cycle, sample the current to obtain the current sampling values \(i_d(k)\) and \(i_q(k)\), and obtain the d-axis current reference value \(I_{ref}(k)\) and the q-axis current reference value \(I_{ref}(k)\) according to the output of the speed loop PI regulator of the servo driver to which the current loop belongs, where k is any natural number from 1 to N; d (k) and i q (k), and obtain the d-axis current reference value I d ref(k) and q-axis current reference value I q ref(k), where k is any natural number from 1 to N;

[0100] S3. Calculate the first d-axis current \(i_d(k)\) and the first q-axis current \(i_q(k)\) required for calculating the first duty cycle according to the current sampling values, where \(i_d(k)=i_d(k)\), \(i_q(k)=i_q(k)\). Combine the corresponding transformation and the space vector pulse width modulation principle to calculate the first PWM duty cycle in the k-th cycle, and wait until the update moment to update the PWM duty cycle; d1 (k) and the first q-axis current i q1 (k), where, i d1 (k) = i d (k), i q1 (k) = i q (k), and combine the corresponding transformation and the space vector pulse width modulation principle to calculate the first PWM duty cycle in the k-th cycle, and wait until the update moment to update the PWM duty cycle;

[0101] S4. Reconstruct the current required for the n-th duty cycle update in the k-th PWM cycle, calculate the corresponding PWM duty cycle, and determine whether it reaches the position of the n-th duty cycle update in the K-th cycle. If it reaches, update the duty cycle until the update times reach N; where the current required for the n-th duty cycle update is calculated according to the current required for the (n - 1)-th duty cycle update, and n is a natural number greater than 1 and less than or equal to N.

[0102] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementation manners, and will not be elaborated in this embodiment.

[0103] In addition, in combination with the method for expanding the current loop bandwidth provided in the above embodiments, a storage medium can also be provided in this embodiment to implement it. A computer program is stored on the storage medium; when the computer program is executed by a processor, it implements any one of the methods for expanding the current loop bandwidth in the above embodiments.

[0104] It should be understood that the specific embodiments described here are only used to explain this application, rather than to limit it. According to the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of this application.

[0105] Obviously, the accompanying drawings are only some examples or embodiments of the present application. For those of ordinary skill in the art, the present application can also be applied to other similar situations based on these drawings without creative efforts. Additionally, it can be understood that although the work done during this development process may be complex and time-consuming, for those of ordinary skill in the art, certain design, manufacturing, or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be regarded as insufficient disclosure of the present application.

[0106] The term "embodiment" in the present application means that the specific features, structures, or characteristics described in connection with the embodiments may be included in at least one embodiment of the present application. The phrase appears in various positions in the specification and does not necessarily mean the same embodiment, nor does it mean being independent or alternative to other embodiments and mutually exclusive. Those of ordinary skill in the art can clearly or implicitly understand that the embodiments described in the present application can be combined with other embodiments without conflict.

[0107] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of patent protection. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A method for expanding the bandwidth of a current loop, characterized in that, The method includes: Setting the switching frequency of the power device of the servo driver to which the current loop belongs, the number of PWM duty cycle updates N within one carrier period, and the corresponding current sampling period and PWM duty cycle update period; At the starting moment of the carrier wave in the k-th PWM cycle, current sampling is performed to obtain current sampling values \(i\) d (k) and \(i\) q (k), and the d-axis current reference value \(I\) d ref(k) and the q-axis current reference value \(I\) q ref(k) are obtained according to the output of the speed-loop PI regulator of the servo driver to which the current loop belongs, where k is any natural number from 1 to N;​​​​ Calculate the first d-axis current i d1 (k) and the first q-axis current i q1 (k) required for calculating the first duty cycle according to the current sampling value, where i d1 (k) = i d (k), i q1 (k) = i q (k). Combine the corresponding transformation and the space vector pulse width modulation principle to calculate the first PWM duty cycle in the k-th period, and wait until the update moment to update the PWM duty cycle; Reconstructing the current required for the nth duty cycle update within the kth PWM period, calculating the corresponding PWM duty cycle, and determining whether the position of the nth duty cycle update of the Kth period is reached. If it is reached, the duty cycle is updated until the update times reach N; wherein the current required for the nth duty cycle update is calculated based on the current required for the (n - 1)th duty cycle update, and n is a natural number greater than 1 and less than or equal to N.

2. The method for expanding the current loop bandwidth according to claim 1, wherein Current sampling is performed at the starting position of the k-th PWM carrier period, and relevant calculations are carried out to obtain the first d-axis current i d1 (k) and the first q-axis current i q1 (k). Based on i d1 (k) and i q1 (k), the first duty cycle is calculated, and the PWM duty cycle is updated. According to the first duty cycle, the current reference value I d1 ref(k) is calculated, where I q1 ref(k).

3. The method for expanding the current loop bandwidth according to claim 2, characterized in that, According to the first d-axis current i d1 (k), the first q-axis current i q1 (k) and the current reference values I d1 ref(k), I q1 ref(k), the current deviation value e d1 (k) can be obtained at this time, e q1 (k), that is 。 4. The method for expanding the current loop bandwidth according to claim 3, characterized in that, When reconstructing the current required for the second duty cycle update within the Kth PWM period, according to the current deviation e d1 (k), e q1 (k) can reconstruct the current i d2 (k), i q2 (k), Wherein, the variables x and y respectively represent the incremental adjustment coefficients of the d-axis current and the q-axis current.

5. The method for expanding the current loop bandwidth according to claim 4, wherein When calculating the nth duty cycle within the Kth PWM period, Among them, I dn-1 ref(k) and I qn-1 ref(k) are the reference values of the d-axis current and the q-axis current calculated by the (n-1)-th duty cycle update in the K-th period respectively. i dn (k) represents the d-axis current at the n-th time in the K-th period, and i dn-1 (k) represents the d-axis current at the (n-1)-th time in the K-th period. i qn (k) represents the q-axis current at the n-th time in the K-th period, and i qn-1 (k) represents the q-axis current at the (n-1)-th time in the K-th period.

6. The method for expanding the current loop bandwidth according to claim 5, characterized in that By adjusting the magnitudes of the variable x and the variable y to respectively adjust the incremental magnitudes of the d-axis current and the q-axis current, the current response effect is improved, and the value ranges of the coefficients x and y are: 。 7. The method for expanding the current loop bandwidth according to any one of claims 1-6, characterized in that: Within the same PWM carrier period, when the number of switching times of the power device is greater than 1, limit processing is performed on the output PWM.

8. The method for expanding the current loop bandwidth according to claim 7, characterized in that: When the triangular carrier counts up, the PWM output is determined by the first equality of the timer comparison value and the triangular carrier. When the triangular carrier counts down, the PWM output is determined by the first equality of the timer comparison value and the triangular carrier.

9. An apparatus for expanding the bandwidth of a current loop, characterized in that, It includes: A parameter setting unit, which sets the switching frequency of the power device of the servo driver to which the current loop belongs, the number of PWM updates N within one carrier period, and the corresponding current sampling period and PWM update period; A current sampling unit, which samples the current at the start moment of the carrier of the Kth PWM period; The current control unit makes the current required for the first calculation of the duty cycle equal to the current sampling value according to the current sampling value, that is, i d1 (k) = i d (k), i q1 (k) = i q (k), and calculates the current required for the nth duty cycle update in the Kth PWM period according to the set formula; A PWM duty cycle control unit, which calculates the first PWM duty cycle within the Kth period, waits until the update moment and updates the duty cycle. When calculating the nth PWM duty cycle within the Kth period, it determines whether the position of the nth duty cycle update of the Kth period is reached. If it is reached, the duty cycle is updated; the PWM duty cycle control unit determines whether the set number of duty cycle updates N is reached. When the update times reach the set value N, it enters the next period, wherein the current required for the nth duty cycle update is calculated based on the current required for the (n - 1)th duty cycle update, and n is a natural number greater than 1 and less than or equal to N.

10. A storage medium, characterized in that, Multiple instructions are stored in the storage medium; the multiple instructions are used to be loaded and executed by a processor to perform the method for expanding the current loop bandwidth as described in any one of claims 1 - 8.

11. A servo driver, characterized in that, It includes: A processor, which is used to execute multiple instructions; A memory, which is used to store multiple instructions; Wherein, the multiple instructions are used to be stored by the memory and loaded and executed by the processor to perform the method for expanding the current loop bandwidth as described in any one of claims 1 - 8.

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