Commutation method, device and equipment in braking state of brushless direct current motor, medium and product

Abstract

The invention discloses a commutation method, device, equipment, medium and product in a braking state of a brushless direct current motor, and relates to the field of motor control, and the method comprises the steps: constructing a plurality of chopping combinations corresponding to the brushless direct current motor at the current moment; inputting each chopping combination and the steady-state values of the angular velocity, the bus voltage and the non-commutation phase current of the brushless direct current motor at the current moment into a modulation mode selection model to obtain commutation time corresponding to each chopping combination; the modulation mode selection model comprises a commutation time calculation formula, a PWM duty ratio calculation formula and a duty ratio constraint; the PWM duty ratio calculation formula is an equation obtained by enabling the non-commutation phase current change rate general formula to be 0; according to the chopping combination with the shortest commutation time, commutation is conducted on the brushless direct current motor at the current moment, the torque ripple can be restrained, the shortest commutation time is achieved, and the commutation time and the torque ripple are synchronously optimized under the braking working condition.

Description

Technical Field

[0001] The present application relates to the field of motor control, and in particular to a commutation method, device, equipment, medium and product for a brushless DC motor in a braking state. Background Art

[0002] The underground coal mine environment is characterized by limited space and variable track gradients. Traditional manual inspections face challenges such as low efficiency and poor safety. As an intelligent alternative, track-mounted inspection robots must achieve stable operation and long endurance on complex slopes. The current mainstream drive solution uses brushless direct current motors (BLDCMs), but these present significant technical bottlenecks under braking conditions. First, torque ripple caused by non-ideal back-electromotive force waveforms during commutation is transmitted through the drive train to the robot body, causing mechanical vibration and positioning offset, directly impacting the detection accuracy of precision equipment such as infrared thermal imagers and gas sensors, and even triggering false alarms. Second, the undulating underground tracks sometimes cause the motor to engage in a braking-generating state. Traditional braking methods prolong commutation times during commutation, exacerbating torque ripple. Therefore, optimizing commutation time and torque ripple under braking conditions has become a core technical challenge in improving the overall performance of coal mine inspection robots. Summary of the Invention

[0003] The purpose of this application is to provide a commutation method, device, equipment, medium and product under the braking state of a brushless DC motor, which can suppress torque pulsation and achieve the shortest commutation time, and synchronously optimize the commutation time and torque pulsation under braking conditions.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a commutation method for a brushless DC motor in a braking state, comprising:

[0006] Constructing multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes a duty cycle of a modulation mode corresponding to a non-commutation phase, a duty cycle of exiting the corresponding modulation mode, and a duty cycle of entering the corresponding modulation mode; at least one of the non-commutation phase, the exit phase, and the corresponding modulation mode in a chopping combination is a PWM modulation mode;

[0007] Inputting each chopping combination and the current steady-state values ​​of the brushless DC motor's angular velocity, bus voltage, and non-commutating phase current into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the non-commutating phase current rate of change formula to 0;

[0008] Commutate the brushless DC motor at the current moment according to the chopping combination with the shortest commutation time.

[0009] In one embodiment, the PWM duty cycle calculation formula is:

[0010] where d

[0012] represents the duty cycle for entering the corresponding modulation mode, d b represents the duty cycle for exiting the corresponding modulation mode, d c represents the duty cycle for the non - commutation corresponding modulation mode, U d represents the bus voltage of the brushless DC motor at the current moment, k e represents the back - EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

[0011] In one embodiment, the duty cycle constraint is: 0 < d < 1, where d represents the PWM duty cycle.

[0012] In one embodiment, the commutation time calculation formula is:

[0013] where t ctm represents the commutation time, L represents the equivalent phase inductance of the brushless DC motor, I represents the steady - state value of the non - commutation phase current of the brushless DC motor at the current moment, d a represents the duty cycle for entering the corresponding modulation mode, d b represents the duty cycle for exiting the corresponding modulation mode, d c represents the duty cycle for the non - commutation corresponding modulation mode, U d represents the bus voltage of the brushless DC motor at the current moment, k e represents the back - EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

[0014] In one embodiment, the general process for determining the non - commutation phase current change rate is:

[0015] Construct the terminal voltage equation of the brushless DC motor;

[0016] Obtain the general formula for the non - commutation phase current change rate according to the terminal voltage equation.

[0017] In one embodiment, before inputting each chopping combination and the angular velocity, bus voltage, and steady - state value of the non - commutation phase current of the brushless DC motor at the current moment into the modulation mode selection model to obtain the commutation time corresponding to each chopping combination, it further includes:

[0018] The speed range of the brushless DC motor at the current moment is obtained according to the angular velocity and bus voltage of the brushless DC motor at the current moment; the speed range is a low speed range and a high speed range.

[0019] In a second aspect, the present application provides a commutation device for a brushless DC motor in a braking state, comprising:

[0020] A chopping combination generation module is used to construct multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes a duty cycle of a modulation mode corresponding to a non-commutation phase, a duty cycle of an exit phase corresponding to the modulation mode, and a duty cycle of an entry phase corresponding to the modulation mode; at least one of the non-commutation phase, the exit phase, and the entry phase corresponding to the modulation mode in a chopping combination is a PWM modulation mode;

[0021] A commutation time calculation module is configured to input each chopping combination and the current steady-state values ​​of the brushless DC motor's angular velocity, bus voltage, and non-commutation phase current into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the non-commutation phase current rate of change formula to 0;

[0022] The commutation module is used to commutate the brushless DC motor at the current moment according to the chopping combination with the shortest commutation time.

[0023] In a third aspect, the present application provides a computer device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the above-mentioned commutation methods for a brushless DC motor in a braking state.

[0024] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the above-mentioned commutation methods for a brushless DC motor in a braking state.

[0025] In a fifth aspect, the present application provides a computer program product, comprising a computer program, which, when executed by a processor, implements any of the above-mentioned commutation methods for a brushless DC motor in a braking state.

[0026] According to the specific embodiments provided in this application, this application has the following technical effects:

[0027] The present application provides a commutation method, device, equipment, medium and product for a brushless DC motor in a braking state. In the related art, research on torque pulsation suppression of brushless motors is mostly focused on the driving state. Among them, there is a torque compensation method based on harmonic current injection, but it relies on a fixed parameter compensation model. In the braking and power generation state, the compensation fails due to the phase offset of the back electromotive force, which aggravates the commutation current distortion. Some other schemes use an improved PWM chopping combination. Although it can shorten the commutation time, it does not take into account the particularity of the braking working condition. More importantly, the existing methods mostly regard torque pulsation suppression and commutation time optimization as independent problems, and lack an analysis of the synergistic mechanism between the two. This contradiction is particularly prominent in underground scenarios where ramps are frequently switched, which seriously restricts the reliability of robot operation. This application establishes for the first time a mathematical model of the commutation time, torque pulsation and chopping combination under braking conditions - a modulation mode selection model. By setting the general formula of the non-commutation phase current change rate to 0, the PWM duty cycle calculation formula is obtained. The duty cycle calculated based on this formula can suppress torque pulsation. Then, on this basis, the chopping combination with the shortest commutation time is selected to reduce torque pulsation, and the commutation time and torque pulsation are simultaneously optimized under braking conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 A schematic flow chart of a commutation method for a brushless DC motor in a braking state provided in one embodiment of the present application;

[0030] Figure 2 A main power circuit diagram of a brushless DC motor provided in one embodiment of the present application;

[0031] Figure 3 An experimental scheme diagram provided for an embodiment of the present application;

[0032] Figure 4 A commutation method for a brushless DC motor in a braking state provided in one embodiment of the present application is applied to a phase current waveform diagram at a speed of 600 r / min in a braking state;

[0033] Figure 5 A commutation method for a brushless DC motor in a braking state provided in one embodiment of the present application is applied to a phase current waveform diagram at a speed of 1600 r / min in a braking state;

[0034] Figure 6This is a structural block diagram of a commutation device in a braking state of a brushless DC motor provided in one embodiment of the present application;

[0035] Figure 7 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0038] Due to the inductive characteristics of the armature winding of the brushless DC motor, the commutation process cannot be completed instantaneously. During the commutation stage, current paths exist simultaneously in the three-phase windings (defined as the entry phase, exit phase and non-commutation phase respectively). In order to suppress torque pulsation and achieve the shortest commutation time, the PWM duty cycle of the three-phase winding needs to be optimized. In view of the problem that the brushless DC motor has commutation torque pulsation and a long commutation time in the braking state, thereby affecting its smooth operation, the present application proposes a commutation method for shortening the commutation time and pulsation suppression in the braking state of a brushless DC motor in an exemplary embodiment, which effectively realizes torque pulsation in the braking state and solves the problem of poor smoothness of the inspection robot's operation due to torque pulsation. The commutation method of the brushless DC motor in the braking state is shown, as shown in FIG. Figure 1 As shown, the following steps are included:

[0039] Step 201: Construct multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes a duty cycle of a non-commutating phase corresponding to a modulation mode, a duty cycle of exiting a corresponding modulation mode, and a duty cycle of entering a corresponding modulation mode; in a chopping combination, at least one of the non-commutating phase, the exiting phase, and the entering corresponding modulation mode is a PWM modulation mode.

[0040] Step 202: Input each chopping combination and the current steady-state values ​​of the angular velocity, bus voltage, and non-commutated phase current of the brushless DC motor into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the general formula of the non-commutated phase current change rate to 0.

[0041] Step 203: commutating the brushless DC motor at the current moment according to the chopping combination with the shortest commutation time.

[0042] In another exemplary embodiment of the present application, multiple chopping combinations corresponding to the brushless DC motor at the current moment are constructed. Specifically, the three-phase duty cycle during commutation is only allowed to take values ​​of d, 0, or 1. Combining the circuit principle and the effective current path during commutation, the chopping combination is constructed by exhaustive method. Figure 2 Take the brushless DC motor shown in the figure as an example: For the commutation phase, in which phases AB are commutated to phase AC, phases A, B, and C are designated as the non-commutation phase, exit phase, and entry phase. During commutation, the duty cycle of each phase can be 0, d, or 1. Based on circuit principles and the effective current paths during commutation, the possible chopping combinations are (d, 0, 0), (d, 0, 1), (d, 1, 0), (d, 1, 1), (0, d, 0), (0, d, 1), (1, d, 0), (1, d, 1), (0, 0, d), (0, 1, d), (1, 0, d), and (1, 1, d).

[0043] In another exemplary embodiment of the present application, the process of determining the non-commutating phase current change rate is as follows:

[0044] Construct the terminal voltage equation of the brushless DC motor. Figure 2 Take the brushless DC motor shown in the figure as an example: Since the armature winding is symmetrical and the inductive reactance is much greater than the impedance, the resistance of the armature winding is ignored. During the commutation stage when the AB phase is commutated to the AC phase, the terminal voltage equation can be expressed as:

[0045]

[0046] Among them, i a ,i b and i c Represent the instantaneous current values ​​of the entering phase, exiting phase and non-commutating phase respectively, Respectively represent the a ,i b and i c Find the derivative of time t, R a and L are phase resistance and equivalent phase inductance respectively, U N is the neutral point voltage. k is the chopping function, subscript k=a,b,c,S s To indicate the running state, when running in the braking state S s =-1, if the switch is always on d k =1, the switch is always off d k =0, if the switch tube is chopper d k =d, d represents the PWM duty cycle.

[0047] The general formula of the non-commutation phase current change rate is obtained based on the terminal voltage equation. Figure 2 Take the brushless DC motor shown in the figure as an example: the general formula for the non-commutated phase current change rate is:

[0048]

[0049] In another exemplary embodiment of the present application, Figure 2 Taking the brushless DC motor shown in the figure as an example, in order to suppress the commutation torque ripple, the current conversion rate of the non-commutation phase is set to zero, and the PWM duty cycle calculation formula is:

[0050]

[0051] Among them, d a Indicates the duty cycle of the corresponding modulation mode, d b Indicates the duty cycle of exiting the corresponding modulation mode, d c Indicates the duty cycle of the non-commutation modulation mode, U d Indicates the current moment of the brushless DC motor bus voltage, k e represents the back EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

[0052] In another exemplary embodiment of the present application, Figure 2 Take the brushless DC motor shown in the figure as an example: According to the terminal voltage equation, the general formula for the phase current change rate of the exit phase can be calculated as:

[0053]

[0054] Assuming that the steady-state value of the non-commutating phase current is I, the current change of the exiting phase is Δi=I. According to (4), the commutation time t can be calculated. ctm The calculation formula is:

[0055]

[0056] Among them, t ctm represents the commutation time, L represents the equivalent phase inductance of the brushless DC motor, I represents the steady-state value of the non-commutation phase current of the brushless DC motor at the current moment, and d a Indicates the duty cycle of the corresponding modulation mode, d b Indicates the duty cycle of exiting the corresponding modulation mode, d c Indicates the duty cycle of the non-commutation modulation mode, U d Indicates the current moment of the brushless DC motor bus voltage, k e represents the back EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

[0057] In another exemplary embodiment of the present application, the duty cycle constraint is:

[0058] 0 <d<1 (6);

[0059] In another exemplary embodiment of the present application, each chopping combination and the steady-state values ​​of the angular velocity, bus voltage, and non-commutated phase current of the brushless DC motor at the current moment are input into the modulation mode selection model to obtain the commutation time corresponding to each chopping combination. The brushless DC motor at the current moment is commutated according to the chopping combination with the shortest commutation time, specifically:

[0060] Substitute each chopping combination and the angular velocity of the brushless DC motor and the bus voltage at the current moment into formula (3) to obtain the value of the PWM duty cycle d in each chopping combination.

[0061] The chopping combinations corresponding to the values ​​of the PWM duty cycle d that meet the formula (6) are selected as candidate chopping combinations.

[0062] The candidate chopping combinations and the steady-state value of the non-commutating phase current are input into formula (5) to obtain the commutation time corresponding to each candidate chopping combination.

[0063] The brushless DC motor at the current moment is commutated according to the candidate chopping combination with the shortest commutation time.

[0064] In another exemplary embodiment of the present application, before inputting each chopping combination and the steady-state values ​​of the angular velocity, bus voltage, and non-commutating phase current of the brushless DC motor at the current moment into the modulation mode selection model to obtain the commutation time corresponding to each chopping combination, the following is also included:

[0065] The speed range of the brushless DC motor at the current moment is obtained according to the angular velocity and bus voltage of the brushless DC motor at the current moment; the speed range is a low speed range and a high speed range. Specifically: Through calculation, it is found that different chopping methods need to be adopted in different speed ranges in order to meet the conditions of formula (6), and the dividing point is When U d >4k e When ω, it is defined as the low speed range; when U d <4k e When ω, high-speed section.

[0066] In practical applications, the chopping combination corresponding to the duty cycle that satisfies formula (6) is substituted into formula (5) to calculate the commutation time under different chopping combinations. After comparison, it is found that in the low-speed range, the d0d (corresponding to the entry phase, exit phase, and non-commutation phase) chopping combination has the shortest commutation time. In this mode, the non-commutation phase and the entry phase are chopped synchronously (duty cycle d), and the exit phase is forced to be turned off (duty cycle 0), which can significantly reduce the current continuous flow time. The commutation time is

[0067]

[0068] In this mode, the PWM duty cycle is

[0069]

[0070] In the high-speed range, the 00d chopping combination is used, and the commutation time is the shortest. By suppressing the current change rate of the non-commutation phase (setting its derivative di / dt = 0) and simultaneously shutting off the exit phase and the non-commutation phase (duty cycle 0), the commutation delay in the high-speed domain is effectively shortened. The commutation time is

[0071]

[0072] In this mode, the PWM duty cycle

[0073]

[0074] If the current sampling value of the non-commutation phase current is i a (k), the speed sampling value is ω(k), then the PWM duty cycle and commutation time are shown in Table I.

[0075] Table I Duty cycle prediction values ​​under different chopping combinations

[0076]

[0077]

[0078] The commutation method provided in the above embodiment is applied to a motor with a rated speed of 2000 r / min, a rated voltage of 24 V, a phase inductance of 360 uH, and a rated torque of 0.5 N·m. The phase current waveforms obtained at a given speed of 600 r / min and 1600 r / min are respectively as follows: Figure 4 and Figure 5 shown.

[0079] This application is aimed at brushless DC motors used in rail inspection robots under braking conditions. By optimizing the PWM chopping combination in the commutation stage, the commutation time is shortened and the torque pulsation is suppressed, thereby improving the smoothness of the brushless DC motor operation. It is suitable for high-performance control scenarios and industrial fields such as drones, rail inspection robots, electric vehicles, and belt conveyors. It improves the smoothness of control while achieving energy feedback, and has important economic value.

[0080] This application can suppress the commutation torque fluctuation in the full speed range under braking state, and only needs to calculate one duty cycle, without the need to control the exit phase and the entry phase separately. The control is simple and easy to implement.

[0081] This application establishes for the first time a mathematical model of the commutation time and torque pulsation and chopping combination under braking conditions, and proposes a collaborative optimization method based on PWM chopping. Specific breakthroughs include: ① constructing a transient model of the motor equivalent circuit under braking, namely formula (1); ② innovatively designing a commutation interval segmentation and duty cycle compensation algorithm, namely the commutation method proposed in this application, which shortens the commutation time while reducing the torque pulsation peak. This technological breakthrough not only overcomes the industry problem of "difficulty in balancing commutation speed and torque stability" under braking conditions, but also promotes the evolution of mining robot drive systems towards "high dynamic response, low vibration and noise, and high energy efficiency", providing core technical support for unmanned inspections in deep mines, and has important strategic significance for ensuring mine safety and promoting intelligent transformation.

[0082] Based on the same inventive concept, embodiments of the present application further provide a commutation device for a brushless DC motor in a braking state, for implementing the aforementioned commutation method for a brushless DC motor in a braking state. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more embodiments of the commutation device for a brushless DC motor in a braking state provided below can be found in the aforementioned limitations of the commutation method for a brushless DC motor in a braking state, and will not be further elaborated here.

[0083] In an exemplary embodiment, a commutation device for a brushless DC motor in a braking state is provided, such as Figure 6 Shown, including:

[0084] The chopping combination generation module is used to construct multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes the duty cycle of the non-commutation phase corresponding to the modulation mode, the duty cycle of the exit phase corresponding to the modulation mode, and the duty cycle of the entry phase corresponding to the modulation mode; in a chopping combination, at least one of the non-commutation phase, the exit phase, and the entry phase corresponding to the modulation mode is a PWM modulation mode.

[0085] A commutation time calculation module is configured to input each chopping combination and the steady-state values ​​of the angular velocity, bus voltage, and non-commutation phase current of the brushless DC motor at the current moment into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the general formula of the non-commutation phase current change rate to 0.

[0086] The commutation module is used to commutate the brushless DC motor at the current moment according to the chopping combination with the shortest commutation time.

[0087] In an exemplary embodiment, a specific embodiment, such as Figure 3As shown, the system consists of two parts: the main power circuit (brushless DC motor) and the control circuit. The control part is composed of the above-mentioned commutation device, wherein the commutation time calculation module includes: a duty cycle calculation module, a commutation area determination, commutation time calculation and chopping combination selection module, and a non-commutation phase current selection module.

[0088] The duty cycle calculation module is used to substitute each chopping combination and the angular velocity and bus voltage of the brushless DC motor at the current moment into the PWM duty cycle calculation formula to obtain the value of the PWM duty cycle d in each chopping combination.

[0089] The commutation zone judgment, commutation time calculation, and chopping combination selection module is used to screen out the chopping combinations corresponding to the PWM duty cycle d value that meets the duty cycle constraint as candidate chopping combinations. The candidate chopping combinations and the steady-state value of the non-commutation phase current are then input into the commutation time calculation formula to obtain the commutation time corresponding to each candidate chopping combination. The brushless DC motor at the current moment is commutated according to the candidate chopping combination with the shortest commutation time.

[0090] The non-commutation phase current selection module determines which phase is the non-commutation phase according to the Hall signal of the main power circuit and collects the phase current as current feedback, that is, Figure 3 i in n_ctm , then calculate the current given value I ref With current feedback i n_ctm The difference is used to determine whether to continue executing the duty cycle calculation module and the commutation zone judgment, commutation time calculation and chopping combination selection modules. ref Output from the speed loop.

[0091] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 7As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store commutation data of a brushless DC motor in a braking state. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a commutation method of a brushless DC motor in a braking state is implemented.

[0092] Those skilled in the art will understand that Figure 7 The structure shown in the figure is merely a block diagram of a portion of the structure related to the solution of the present application and does not constitute a limitation on the computer device to which the solution of the present application is applied. A specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement. In an exemplary embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor implements the above-mentioned method embodiments when executing the computer program.

[0093] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, which implements the above-mentioned method embodiments when executed by a processor.

[0094] In an exemplary embodiment, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the above method embodiments are implemented.

[0095] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0096] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0097] The databases involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processors involved in the various embodiments provided herein may include, but are not limited to, general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic units, data processing logic units based on quantum computing, and the like.

[0098] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] This document uses specific examples to illustrate the principles and implementation methods of this application. The description of the above examples is only intended to help understand the method and core concept of this application. At the same time, for those skilled in the art, based on the concept of this application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A commutation method for a brushless DC motor in a braking state, characterized in that: The commutation method of the brushless DC motor in the braking state includes: Constructing multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes a duty cycle of a modulation mode corresponding to a non-commutation phase, a duty cycle of exiting the corresponding modulation mode, and a duty cycle of entering the corresponding modulation mode; at least one of the non-commutation phase, the exit phase, and the corresponding modulation mode in a chopping combination is a PWM modulation mode; Inputting each chopping combination and the current steady-state values ​​of the brushless DC motor's angular velocity, bus voltage, and non-commutating phase current into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the non-commutating phase current rate of change formula to 0; The brushless DC motor at the current moment is commutated according to the chopping combination with the shortest commutation time.

2. The commutation method of the brushless DC motor in the braking state according to claim 1, characterized in that: The PWM duty cycle calculation formula is: Among them, d a Indicates the duty cycle of the corresponding modulation mode, d b Indicates the duty cycle of exiting the corresponding modulation mode, d c Indicates the duty cycle of the non-commutation modulation mode, U d Indicates the current moment of the brushless DC motor bus voltage, k e represents the back EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

3. The commutation method of a brushless DC motor in a braking state according to claim 1, characterized in that: Duty cycle constraint: 0 <d<1; Where d represents the PWM duty cycle.

4. The commutation method of a brushless DC motor in a braking state according to claim 1, characterized in that: The formula for calculating the commutation time is: Among them, t ctm represents the commutation time, L represents the equivalent phase inductance of the brushless DC motor, I represents the steady-state value of the non-commutation phase current of the brushless DC motor at the current moment, and d a Indicates the duty cycle of the corresponding modulation mode, d b Indicates the duty cycle of exiting the corresponding modulation mode, d c Indicates the duty cycle of the non-commutation modulation mode, U d Indicates the current moment of the brushless DC motor bus voltage, k e represents the back EMF coefficient, and ω represents the angular velocity of the brushless DC motor at the current moment.

5. The commutation method of a brushless DC motor in a braking state according to claim 1, characterized in that: The general process for determining the non-commutating phase current change rate is: Construct the terminal voltage equation for the brushless DC motor; The general formula of the non-commutating phase current change rate is obtained based on the terminal voltage equation.

6. The commutation method of a brushless DC motor in a braking state according to claim 1, characterized in that: After inputting each chopping combination and the current angular velocity, bus voltage, and steady-state value of the non-commutating phase current of the brushless DC motor into the modulation mode selection model, the commutation time corresponding to each chopping combination is obtained. The above also includes: The speed range of the brushless DC motor at the current moment is obtained according to the angular velocity and bus voltage of the brushless DC motor at the current moment; the speed range is a low speed range and a high speed range.

7. A commutation device for a brushless DC motor in a braking state, characterized in that: The commutation device in the braking state of the brushless DC motor includes: A chopping combination generation module is used to construct multiple chopping combinations corresponding to the brushless DC motor at the current moment; a chopping combination includes a duty cycle of a modulation mode corresponding to a non-commutation phase, a duty cycle of an exit phase corresponding to the modulation mode, and a duty cycle of an entry phase corresponding to the modulation mode; at least one of the non-commutation phase, the exit phase, and the entry phase corresponding to the modulation mode in a chopping combination is a PWM modulation mode; A commutation time calculation module is configured to input each chopping combination and the current steady-state values ​​of the brushless DC motor's angular velocity, bus voltage, and non-commutation phase current into a modulation mode selection model to obtain the commutation time corresponding to each chopping combination; the modulation mode selection model includes a commutation time calculation formula, a PWM duty cycle calculation formula, and a duty cycle constraint; the PWM duty cycle calculation formula is an equation obtained by setting the non-commutation phase current rate of change formula to 0; The commutation module is used to commutate the brushless DC motor at the current moment according to the chopping combination with the shortest commutation time.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the commutation method in the braking state of the brushless DC motor according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the commutation method of the brushless DC motor in a braking state according to any one of claims 1 to 6 is implemented.

10. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the commutation method of the brushless DC motor in a braking state according to any one of claims 1 to 6 is implemented.

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