Brushless DC motor and control method, control device and computer storage medium

Abstract

The present application relates to a brushless DC motor and a control method, a control device, and a computer storage medium thereof. The control method of the brushless DC motor comprises: obtaining a current position and a target position of a motor rotor, determining a target modulation mode of a power switch device from a plurality of candidate modulation modes according to the current position and the target position, and generating a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position. The method does not need to calculate the rotation speed of the motor rotor, and can directly implement closed-loop control of the position of the motor rotor according to the current position of the motor rotor, thereby solving the problem that the motor rotation speed cannot be accurately calculated when the motor rotor is in a low-speed state, thereby improving the accuracy of the position control of the brushless DC motor.

Description

Technical Field

[0001] The present application relates to the technical field of brushless DC motors, and in particular to a brushless DC motor and a control method, a control device, and a computer storage medium thereof. Background Art

[0002] The control of brushless DC motor (BLDC) relies on Hall sensor that can feedback the motor position information. Hall sensor can feedback the position information of motor rotor in real time. The control system of brushless DC motor equipped with Hall sensor determines the basic commutation control strategy of the motor according to the commutation control truth table containing Hall signal and motor commutation control information. Since the Hall sensor can only feedback 6 motor positions in one motor rotor electrical cycle, the accuracy is low. Therefore, when the motor speed is low (for example, the speed of 5-pole motor is less than 200r / min), the accurate speed of the motor cannot be calculated. Therefore, it is difficult for brushless DC motor to realize position or angle closed-loop control function. Summary of the invention

[0003] Based on this, it is necessary to provide a brushless DC motor and a control method, a control device, and a computer storage medium that can improve the position control accuracy of the brushless DC motor.

[0004] In a first aspect, an embodiment of the present application provides a control method for a brushless DC motor, wherein the brushless DC motor includes a motor rotor and a power switch device, and the control method includes:

[0005] Obtaining the current position and target position of the motor rotor;

[0006] Determine a target modulation mode of the power switch device from a plurality of candidate modulation modes according to the current position and the target position; wherein the plurality of candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode and a combined modulation mode;

[0007] A target pulse width modulation signal is generated according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position; wherein the commutation modulation mode is to control the power switch device based on the current position and the target position, the short-circuit modulation mode is to control the power switch device to short-circuit the DC brushless motor, and the combined force modulation mode is to control the power switch device based on the target position.

[0008] In one embodiment, determining a target modulation mode of a power switch device of the brushless DC motor from a plurality of candidate modulation modes according to the current position and the target position includes:

[0009] Acquire a position absolute difference value according to the current position and the target position, wherein the position absolute difference value is the absolute value of the difference between the current position and the target position;

[0010] When the position absolute difference is greater than a first position threshold, determining that the target modulation mode is the commutation modulation mode;

[0011] In a case where the position absolute difference is greater than or equal to a second position threshold and less than or equal to the first position threshold, determining that the target modulation mode is the short-circuit modulation mode; wherein the second position threshold is less than the first position threshold;

[0012] When the position absolute difference is less than the second position threshold, the target modulation mode is determined to be the combined force modulation mode.

[0013] In one embodiment, the target modulation mode is the phase-changing modulation mode, and generating a target pulse width modulation signal according to the target modulation mode includes:

[0014] Obtaining the three-phase current of the brushless DC motor;

[0015] generating a duty cycle instruction according to the current position, the target position and the three-phase current;

[0016] A first pulse width modulation signal is generated according to the first commutation relationship corresponding to the current position, the duty cycle instruction and the commutation modulation mode; wherein the first commutation relationship at least includes the corresponding relationship between the motor rotor position and the modulation mode of the power switch device.

[0017] In one embodiment, generating a duty cycle instruction according to the current position, the target position and the three-phase current includes:

[0018] Acquire a current current amplitude of the brushless DC motor according to the three-phase current, wherein the current current amplitude is an average value of the absolute value of the sum of the three-phase current;

[0019] Acquire a target current amplitude of the brushless DC motor according to the current position and the target position;

[0020] The duty cycle instruction is generated according to the current current amplitude and the target current amplitude.

[0021] In one embodiment, the target modulation mode is the short-circuit modulation mode, and generating a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device includes:

[0022] A second pulse width modulation signal is generated according to the short-circuit modulation mode to control the conduction of one group of switch tubes in the power switch device and the disconnection of another group of switch tubes; wherein each group of switch tubes is connected to the DC brushless motor and the battery respectively, and the two groups of switch tubes of the power switch device are connected in parallel.

[0023] In one embodiment, the target modulation mode is the combined force modulation mode, and generating a target pulse width modulation signal according to the target modulation mode includes:

[0024] A third pulse width modulation signal is generated according to the second commutation relationship corresponding to the target position and the resultant force modulation mode; wherein the second commutation relationship at least includes the correspondence between the electromagnetic resultant force direction, the motor rotor position and the power switch device modulation.

[0025] In a second aspect, an embodiment of the present application provides a control device for a brushless DC motor, wherein the brushless DC motor includes a motor rotor and a power switch device, including:

[0026] A rotor position processing module, used to obtain the current position and target position of the motor rotor;

[0027] a position closed-loop processing module, configured to determine a target modulation mode of the power switch device from a plurality of candidate modulation modes according to the current position and the target position; wherein the plurality of candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode and a combined force modulation mode;

[0028] A commutation control module is used to generate a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position; wherein,

[0029] The commutation control module is used to control the power switch device based on the current position and the target position in the commutation modulation mode, control the power switch device in the short-circuit modulation mode to short-circuit the DC brushless motor, and control the power switch device based on the target position in the combined force modulation mode.

[0030] In one embodiment, the position closed-loop processing module includes:

[0031] A position difference unit, connected to the rotor position processing module, for obtaining an absolute position difference according to the current position and the target position, wherein the absolute position difference is an absolute value of the difference between the current position and the target position;

[0032] A threshold comparison unit is connected to the position difference unit, and is used to determine that the target modulation mode is the phase-changing modulation mode when the absolute position difference is greater than a first position threshold; to determine that the target modulation mode is the short-circuit modulation mode when the absolute position difference is greater than or equal to a second position threshold and less than or equal to the first position threshold; and to determine that the target modulation mode is the combined force modulation mode when the absolute position difference is less than the second position threshold; wherein the second position threshold is less than the first position threshold.

[0033] In one embodiment, the rotor position processing module is further used to obtain the three-phase current of the brushless DC motor, and the control device further includes:

[0034] A position closed-loop control module, connected to the rotor position processing module, and configured to obtain a target current amplitude of the brushless DC motor according to the current position and the target position;

[0035] A three-phase current processing module, connected to the rotor position processing module, for obtaining a current current amplitude of the brushless DC motor according to the three-phase current, wherein the current current amplitude is an average value of the absolute value of the sum of the three-phase currents;

[0036] The torque closed-loop control module is connected to the position closed-loop control module and the three-phase current processing module respectively, and is used to generate a duty cycle instruction according to the current current amplitude and the target current amplitude.

[0037] In one embodiment, the position closed-loop processing module is further used to generate a mode switching instruction according to the target modulation mode, and the commutation control module includes:

[0038] a commutation modulation unit, connected to the rotor position processing module and the torque closed-loop control module respectively, for generating a first pulse width modulation signal according to the current position, the duty cycle instruction and a first commutation relationship corresponding to the commutation modulation mode; wherein the first commutation relationship at least includes a corresponding relationship between the motor rotor position and the modulation mode of the power switch device;

[0039] a short-circuit modulation unit, used for generating a second pulse width modulation signal according to the short-circuit modulation mode, wherein the second pulse width modulation signal is used for controlling the conduction of one group of switch tubes in the power switch device and the disconnection of another group of switch tubes; wherein each group of switch tubes is connected to the brushless DC motor and the battery respectively, and the two groups of switch tubes of the power switch device are connected in parallel;

[0040] A resultant force modulation unit connected to the rotor position processing module, configured to generate a third pulse width modulation signal according to the target position and a second commutation relationship corresponding to the resultant force modulation mode; wherein the second commutation relationship at least includes a correspondence between the electromagnetic resultant force direction, the motor rotor position and the power switch device modulation;

[0041] A switching switch unit is respectively connected to the phase-changing modulation unit, the short-circuit modulation unit, the combined force modulation unit, and the position closed-loop processing module, and is used to determine a target pulse width modulation signal from the first pulse width modulation signal, the second pulse width modulation signal, and the third pulse width modulation signal according to the mode switching instruction.

[0042] In a third aspect, an embodiment of the present application provides a brushless DC motor, comprising:

[0043] Motor rotor and coil windings;

[0044] A Hall sensor, used to obtain a Hall signal of the motor rotor;

[0045] a controller connected to the Hall sensor, configured to obtain a target position of the motor rotor, obtain a current position of the motor rotor according to the Hall signal, determine a target modulation mode of a power switch device of the brushless DC motor from a plurality of candidate modulation modes according to the current position and the target position, and generate a target pulse width modulation signal according to the target modulation mode; wherein the plurality of candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode and a combined force modulation mode, the commutation modulation mode is to control the power switch device based on the current position and the target position, the short-circuit modulation mode is to control the power switch device to short-circuit the brushless DC motor, and the combined force modulation mode is to control the power switch device based on the target position;

[0046] The power switch device is connected to the coil winding and the controller respectively, and is used to adjust the working state according to the target pulse width modulation signal and provide a driving current to the coil winding so as to generate an electromagnetic field through the coil winding to drive the motor rotor to move to the target position.

[0047] In a fourth aspect, an embodiment of the present application provides a computer storage medium on which a computer program is stored, and the computer program implements the steps of the above method when executed by a processor.

[0048] The above-mentioned brushless DC motor and its control method, control device, and computer storage medium obtain the current position and target position of the motor rotor, determine the target modulation mode of the power switching device from multiple candidate modulation modes based on the current position and the target position, and generate a target pulse width modulation signal based on the target modulation mode to control the working state of the power switching device so that the motor rotor reaches the target position. This method does not need to calculate the rotation speed of the motor rotor, and can directly achieve closed-loop control of the motor rotor position based on the current position of the motor rotor, thereby solving the problem that the motor rotation speed cannot be accurately calculated when the motor rotor is in a low-speed state, thereby improving the accuracy of the position control of the brushless DC motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. 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.

[0050] Figure 1 A schematic diagram of the structure of a brushless DC motor according to an embodiment;

[0051] Figure 2 This is a flow chart of a method for controlling a brushless DC motor according to an embodiment of the present invention;

[0052] Figure 3 A schematic diagram of the principle of commutation control of a brushless DC motor according to an embodiment;

[0053] Figure 4 The second flowchart of the control method of the brushless DC motor according to one embodiment;

[0054] Figure 5 The third flowchart of the control method of the brushless DC motor according to one embodiment;

[0055] Figure 6 FIG4 is a flow chart of a method for controlling a brushless DC motor according to an embodiment of the present invention;

[0056] Figure 7 A schematic diagram of a process for obtaining the current amplitude of a brushless DC motor according to an embodiment;

[0057] Figure 8 A schematic structural diagram of a control device for a brushless DC motor according to an embodiment;

[0058] Fig. 9 A schematic diagram of a process for determining a target modulation mode according to an embodiment;

[0059] Fig.10A schematic diagram of the structure of a commutation control module according to an embodiment;

[0060] Fig.11 FIG. 4 is a schematic structural diagram of a brushless DC motor according to another embodiment.

[0061] Description of reference numerals:

[0062] Motor body 10, Hall sensor 20, controller 30, power switch device 40, power supply 50, rotor position processing module 810, position closed-loop processing module 820, commutation control module 830, commutation modulation unit 831, short-circuit modulation unit 832, combined force modulation unit 833, switching switch unit 834, position closed-loop control module 840, three-phase current processing module 850, torque closed-loop control module 860. DETAILED DESCRIPTION

[0063] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0065] The control method and control device of the brushless DC motor provided in the embodiments of the present application are applied to brushless DC motors, such as permanent magnet brushless motors, permanent magnet synchronous motors, etc. Figure 1 As shown, the brushless DC motor may include a motor body 10, a detection component, a control component and a power supply. The motor body 10 includes a motor stator, a motor rotor and a coil winding. The detection component includes a Hall sensor 20, which is arranged on the motor body 10 and is used to obtain a Hall signal of the motor rotor.

[0066] The control component includes a controller 30 and a power switch device 40. The controller 30 is connected to the Hall sensor 20, and the controller 30 is used to obtain the target position of the motor rotor and obtain the current position of the motor rotor according to the Hall signal, and determine the target modulation mode of the power switch device of the DC brushless motor from multiple candidate modulation modes according to the current position and the target position, and generate a target pulse width modulation signal according to the mode switching instruction. The multiple candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode, and a combined force modulation mode. The controller 30 controls the power switch device based on the current position and the target position in the commutation modulation mode, controls the power switch device in the short-circuit modulation mode to short-circuit the DC brushless motor, and controls the power switch device based on the target position in the combined force modulation mode to move the motor rotor to the target position.

[0067] The power switch device 40 is connected to the coil winding and the controller 30 respectively. The power switch device 40 is used to adjust the working state according to the target pulse width modulation (PWM) signal, and provide a driving current to the coil winding to generate an electromagnetic field through the coil winding to drive the motor rotor to move to the target position. Exemplarily, the power switch device adopts a three-phase three-bridge arm structure. Specifically, the power switch device includes two groups of switch tubes, wherein the first group of switch tubes (upper three bridges) includes K1, K3 and K5, and the second group of switch tubes (lower three bridges) includes K2, K4 and K6. The first end of each group of three switch tubes is respectively connected to the three-phase coil winding of the DC brushless motor, the second end of each switch tube is connected to the battery, and the control end of each switch tube is connected to the controller. Each switch tube switches the on-off state under the action of the target pulse width modulation signal output by the controller to provide a driving current for the coil winding. Exemplarily, the switch tube can be a MOS tube or an IGBT.

[0068] The above-mentioned DC brushless motor detects the position of the motor rotor through the Hall sensor 20 to generate a Hall signal, and obtains the current position of the motor rotor according to the Hall signal through the controller 30, so that the target modulation mode of the power switching device can be determined from multiple candidate modulation modes according to the current position and target position of the motor rotor, and a corresponding target pulse width modulation signal is generated according to the target modulation mode, and then the power switching device 40 adjusts the working state according to the target pulse width modulation signal, and provides a driving current to the coil winding to generate an electromagnetic force through the coil winding to drive the electrode rotor to the target position. This process does not require the calculation of the rotation speed of the motor rotor, and can directly realize closed-loop control of the motor rotor position according to the current position of the motor rotor, thereby solving the problem that the motor rotation speed cannot be accurately calculated when the motor rotor is in a low-speed state, thereby improving the accuracy of the DC brushless motor position control.

[0069] In one embodiment, Figure 2As shown, a control method for a brushless DC motor is provided, which can be applied to Figure 1 The DC brushless motor shown in the figure comprises the following steps S202 to S206.

[0070] S202: Acquire the current position and target position of the motor rotor.

[0071] For example, the position of the motor rotor can be detected based on a three-phase Hall sensor, and the current position of the motor rotor can be determined based on the Hall signal generated by the three-phase Hall sensor and the correspondence between the pre-stored Hall signal and the motor rotor position. For example, the motor rotor can be represented by sectors or angles. Figure 3 As shown in the figure, the motor rotor position is divided into 6 sectors (Sector 1-6), and each sector corresponds to a different motor rotor angle and Hall signal. For example, the angle range of sector 1 is 0°~60°, and the corresponding Hall signal is HA1 HB0 HC0. In the application, the Hall signal corresponding to each sector can be set according to the type of Hall sensor. Figure 3 This is only an example. The target position refers to the position that the motor rotor needs to reach. In this application, the current position of the motor rotor is recorded as pos_val, and the target position of the motor rotor is recorded as pos_cmd.

[0072] S204: Determine a target modulation mode of the power switch device from a plurality of candidate modulation modes according to the current position and the target position, wherein the plurality of candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode and a combined modulation mode.

[0073] S206: Generate a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position.

[0074] The commutation modulation mode controls the power switch device based on the current position and the target position so that the motor rotor reaches the target position. That is, in the commutation modulation mode, a target pulse width modulation signal is generated according to the current position and the target position of the motor rotor to control the working state of the power switch device, so that the motor rotor moves to the target position. The commutation modulation mode can be understood as a control method that controls the size of the motor torque output and the positive and negative control of the motor to move toward the target position.

[0075] The short-circuit modulation mode is used to control the power switch device to short-circuit the DC brushless motor, so that the motor rotor reaches the target position. That is, in the short-circuit modulation mode, there is no need to directly generate a target pulse width modulation signal to control the working state of the power switch device based on the current position and target position of the motor rotor to short-circuit the DC brushless motor, so that the motor rotor moves to the target position by inertia. The short-circuit modulation mode can be understood as the motor active short-circuit control (Auto Short-Circuit Control, ASC) mode.

[0076] The combined force modulation mode controls the power switch device based on the target position so that the motor rotor reaches the target position. That is, in the combined force modulation mode, a target pulse width modulation signal is generated according to the target position of the motor rotor to control the working state of the power switch device, so that the motor rotor reaches the target position. The combined force modulation mode can be understood as a control method through the direction of the electromagnetic force vector synthesis, and the motor rotor is pulled to the target position through the electromagnetic combined force.

[0077] The gate of each switch tube in the power switch device is used to receive the target pulse width modulation signal, and selects the path between the battery and the DC brushless motor under the control of the target pulse width modulation signal. Specifically, the target pulse width control signal can control the on-off state of the switch tube, and can also control the duration of the switch tube to remain in the on-off state by adjusting the duty cycle of the target pulse width control signal. The target pulse width modulation signal can be set responsively according to the number of switch tubes in the power switch device.

[0078] The control method of the brushless DC motor obtains the current position and target position of the motor rotor, determines the target modulation mode of the power switching device from multiple candidate modulation modes according to the current position and the target position, generates a target pulse width modulation signal according to the target modulation mode, so as to control the working state of the power switching device and make the motor rotor reach the target position. The method does not need to calculate the rotation speed of the motor rotor, and can directly realize closed-loop control of the position of the motor rotor according to the current position of the motor rotor, thereby solving the problem that the motor rotation speed cannot be accurately calculated when the motor rotor is in a low-speed state, thereby improving the accuracy of the position control of the brushless DC motor.

[0079] In one embodiment, Figure 4 As shown, step S204, determining a target modulation mode of a power switch device of a brushless DC motor from a plurality of candidate modulation modes according to a current position and a target position, may include the following steps S402 to S408.

[0080] S402: Obtain the absolute position difference according to the current position and the target position, the absolute position difference is the absolute value of the difference between the current position and the target position. That is, the absolute position difference is |pos_cmd - pos_val|. Exemplarily, the current position pos_val of the motor rotor is sector 1, and the target position of the motor rotor is sector 2, then the absolute position difference |pos_cmd - pos_val|=1. Exemplarily, the current position pos_val of the motor rotor is 50°, and the target position of the motor rotor is 110°, then the absolute position difference |pos_cmd - pos_val|=60°.

[0081] S404: When the absolute position difference is greater than the first position threshold, determine that the target modulation mode is a commutation modulation mode.

[0082] The first position threshold is pre-set and is denoted as TH1. Exemplarily, when the position of the motor rotor is expressed in sectors, if the first position threshold is 2, then when the absolute position difference is greater than 2 sectors, that is, |pos_cmd – pos_val|>2, the target modulation mode is determined to be the phase-changing modulation mode. Another exemplary example, when the position of the motor rotor is expressed in angles, if the first position threshold is 120°, then when the absolute position difference is greater than 120°, that is, |pos_cmd – pos_val|>120°, the target modulation mode is determined to be the phase-changing modulation mode. In the application, the first position threshold can also be other suitable values ​​such as 3, 4, etc., which are not limited here.

[0083] S406: When the position absolute difference is greater than or equal to the second position threshold and less than or equal to the first position threshold, determine that the target modulation mode is the short-circuit modulation mode.

[0084] The second position threshold is pre-set, denoted as TH2, and the second position threshold is less than the first position threshold. Exemplarily, when the position of the motor rotor is expressed in sectors, if the first position threshold is 2 and the second position threshold is 1, then when the absolute position difference is less than or equal to 2 and greater than or equal to 1 sector, that is, 1≤|pos_cmd – pos_val|≤2, the target modulation mode is determined to be the short-circuit modulation mode. Another exemplary example, when the position of the motor rotor is expressed in angles, if the first position threshold is 120° and the second position threshold is 60°, then when the absolute position difference is less than or equal to 120° and greater than or equal to 60°, that is, 60°≤|pos_cmd – pos_val|≤120°, the target modulation mode is determined to be the short-circuit modulation mode. In the application, the second position threshold can also be other suitable values ​​such as 2, 3, etc., which are not limited here.

[0085] S408: When the absolute position difference is less than the second position threshold, determine that the target modulation mode is the combined force modulation mode.

[0086] Exemplarily, when the position of the motor rotor is expressed in sectors, if the second position threshold is 1, then when the absolute position difference is less than 1 sector, that is, |pos_cmd – pos_val|<1, the target modulation mode is determined to be the combined force modulation mode. In another exemplary embodiment, when the position of the motor rotor is expressed in angles, if the second position threshold is 60°, then when the absolute position difference is less than 60°, that is, |pos_cmd – pos_val|>60°, the target modulation mode is determined to be the combined force modulation mode.

[0087] The control method of the brushless DC motor calculates the absolute position difference between the current position of the motor rotor and the target position, determines the distance between the current position of the motor rotor and the target position by threshold comparison, and selects a suitable modulation mode according to the distance to control the position of the motor rotor. Specifically, when the absolute position difference is greater than the first position threshold, the phase change modulation mode is used to control the torque, direction, etc. of the motor rotor. When the absolute position difference is less than or equal to the first position threshold and greater than or equal to the second position threshold, the short-circuit modulation mode is used to directly short-circuit the brushless DC motor to stop the motor rotor quickly. When the absolute position difference is less than the second position threshold, it indicates that the current position of the motor rotor is close to the target position, and the resultant force modulation mode is used to control the direction of the electromagnetic resultant force output by the stator winding of the brushless DC motor, thereby achieving precise control of the motor rotor.

[0088] In one embodiment, Figure 5 As shown, when the target modulation mode is the phase-changing modulation mode, step S206, generating a target pulse width modulation signal according to the target modulation mode, may include the following steps S602 to S506.

[0089] S502: Obtain the three-phase current of the brushless DC motor.

[0090] In the application, the three-phase current detection of the brushless DC motor can be obtained by one or more current sensors, or by one or more sampling resistors. In the embodiment of the present application, the three-phase currents are respectively recorded as Iu_val, Iv_val and Iw_val.

[0091] S504: Generate a duty cycle instruction according to the current position, the target position and the three-phase current, wherein the duty cycle instruction includes the duty cycle of the target pulse width modulation signal, and the duty cycle instruction can be recorded as duty_cmd.

[0092] S506: Generate a first pulse width modulation signal according to the current position, the duty cycle instruction and the first commutation relationship corresponding to the commutation modulation mode.

[0093] The first commutation relationship at least includes the correspondence between the motor rotor position and the modulation mode of the power switch device. Among them, the motor rotor position may include at least one of the motor rotor sector and the motor rotor angle. The modulation mode of the power switch device refers to the on-off state of each switch tube in the power switch device. The first commutation relationship may also include at least one of the motor phase current and the Hall signal, wherein the motor phase current refers to the three-phase current of the DC brushless motor. Exemplarily, the first commutation relationship can be represented by a truth table. For example, Table 1 provides a DC brushless motor commutation truth table, which includes the correspondence between the motor rotor sector, the motor rotor angle, the motor phase current, the modulation mode of the power switch device and the Hall signal. Combined with Figure 3 Taking the data in the first column of Table 1 as an example, the motor rotor is in sector 1, the motor rotor angle is between 0° and 60°, the U-phase current in the motor phase current is positive, the V-phase current is 0, and the W-phase current is negative, that is, the current of the brushless DC motor flows into the U-phase and flows out of the W-phase, the switch tubes K1 and K2 in the power switch device are turned on, and the switch tubes K3, K4, K5, and K6 are turned off, and the Hall signal is HA1 HB0 HC0.

[0094] Table 1 Brushless DC motor commutation truth table

[0095]

[0096] In one embodiment, Figure 6 As shown, step S504, generating a duty cycle instruction according to the current position, the target position and the three-phase current, may include the following steps S602 to S606.

[0097] S602: Obtain the current amplitude of the brushless DC motor according to the three-phase current.

[0098] Among them, the current current amplitude is recorded as Iamp_val, such as Figure 7 As shown, the current current amplitude is the average value of the absolute value of the sum of the three-phase currents, that is, Iamp_val=1 / 3|Iu_val+Iv_val+Iw_val|.

[0099] S604: Obtain a target current amplitude of the brushless DC motor according to the current position and the target position.

[0100] Exemplarily, the target current amplitude Iamp_cmd of the brushless DC motor may be calculated according to the current position pos_val and the target position pos_cmd by using a proportional-integral (PI) or proportional-integral-derivative (PID) method.

[0101] S606: Generate a duty cycle instruction according to the current current amplitude and the target current amplitude.

[0102] Exemplarily, the duty cycle command duty_cmd may be calculated according to the current current amplitude Iamp_val and the target current amplitude Iamp_cmd by adopting a proportional integral (PI) method.

[0103] The control method of the above-mentioned brushless DC motor obtains the current current amplitude of the brushless DC motor according to the three-phase current, obtains the target current amplitude of the brushless DC motor according to the current position and the target position, and generates a duty cycle instruction according to the current current amplitude and the target current amplitude, so that in the case of a commutation modulation mode, the duty cycle of the pulse width modulation signal can be modulated according to the duty cycle instruction to make the motor rotor move to the target position, thereby realizing closed-loop precise control of the motor rotor position.

[0104] In one embodiment, when the target modulation mode is the combined force modulation mode, step S206, generating a target pulse width modulation signal according to the target modulation mode, may include: generating a third pulse width modulation signal according to the target position and a second commutation relationship corresponding to the combined force modulation mode.

[0105] Please continue reading Figure 1 and Figure 3, taking the forward power supply condition of the brushless DC motor as an example (the motor runs counterclockwise), when the motor rotor is in sector 1 (Sector 1), the U-phase current of the motor is positive and the W-phase current is negative. According to the right-hand spiral duty of the electromagnetic coil winding, the U-phase current is positive, generating a force f1 in the same direction as the U-phase coordinate system. The W-phase current is negative, and according to the right-hand spiral duty of the electromagnetic coil winding, a force f2 in the opposite direction to the W-phase coordinate system is generated. The resultant force of the two forces f1 and f2 is f. The resultant force f is perpendicular to the N pole of the electronic rotor, and this resultant force can push the motor to rotate counterclockwise. According to the basic principle of commutation control, the different flow directions of the motor phase current, that is, different modulation methods of the power switch device, can be used to control the DC brushless motor stator winding to output a force in a specified direction. Taking the motor phase current U as positive and W as negative as an example, when the power devices K1 and K2 are modulated, the direction of the electromagnetic force resultant f output by the motor stator winding is the junction of sector 2 and sector 3. Given this current and power device debugging mode, the motor rotor is subjected to the electromagnetic force, and the N pole will eventually stay at the junction of sectors 2 and 3. By analogy, a second commutation relationship of the final stop position of the motor rotor N pole can be obtained for different currents and power switch device modulation modes. The second commutation relationship at least includes the corresponding relationship between the electromagnetic force direction, the motor rotor position, and the power switch device modulation.

[0106] Exemplarily, Table 2 shows the correspondence between the direction of the electromagnetic force, the motor rotor angle, the motor phase current and the modulation mode of the power switch device. According to the tabular relationship between the motor modulation mode and the direction of the resultant force shown in Table 2, it can be used to realize the position (angle) closed-loop control function of the DC brushless motor. If you want the motor to stop at a position where the rotor electrical angle is 240°, no matter which sector the motor rotor is in, it is modulated by turning on the two tubes K3 and K4, and a suitable duty cycle is given. The motor rotor is subjected to the force at the junction of sectors 4 and 5 in the direction of the resultant force, and will eventually stop at this position. It should be noted that due to the limited accuracy of the DC brushless motor position sensor, the motor position closed-loop control can only realize the closed-loop control function of fixed 6 positions, namely 0°, 60°, 120°, 180°, 240°, 300°, and 360°, with a resolution of 60° electrical angle. Since the number of pole pairs of a brushless DC motor is generally 5 to 7 pairs or even higher, taking 7 pairs as an example, the position closed-loop control accuracy can reach 60° / 7 ≈ 8.6°. Among them, the duty cycle can be pre-set and is not limited here.

[0107] Table 2 Second commutation relationship

[0108]

[0109] The control method of the above-mentioned brushless DC motor, when the target modulation mode is the combined force modulation mode, that is, when the absolute position difference between the current position of the motor rotor and the target position is less than the second position threshold, can generate a second pulse width modulation signal according to the target position and the second commutation relationship, that is, the power switching device is controlled by a modulation method of specifying the synthetic direction of the electromagnetic force vector, and the motor rotor is pulled to the target position by the electromagnetic combined force, thereby realizing position (angle) closed-loop control.

[0110] In one embodiment, when the target modulation mode is the short-circuit modulation mode, step S206, generating a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device, may include: generating a second pulse width modulation signal according to the short-circuit modulation mode to control the conduction of one group of switch tubes in the power switch device and the disconnection of another group of switch tubes. Each group of switch tubes is connected to a brushless DC motor and a battery respectively, and the two groups of switch tubes of the power switch device are connected in parallel.

[0111] by Figure 1 Taking the brushless DC motor shown as an example, Table 3 shows two modulation modes of the active short-circuit modulation mode. Specifically, the active short-circuit function can be achieved by controlling the upper three bridges K1, K3, and K5 of the power switch device to be normally open or modulated, and the lower three bridges K2, K4, and K6 to be closed, or by controlling the lower three bridges K2, K4, and K6 to be normally open or modulated, and the upper three bridges K1, K3, and K5 to be closed. Among them, normally open means that the duty cycle is 1, and modulation means controlling the switch tube to open and close according to a preset duty cycle. In this way, according to the characteristics of the active short-circuit function, the brushless DC motor will generate a braking force to stop the motor after entering the active short-circuit mode. The active short-circuit mode can be used to control the brushless DC motor to stop as soon as possible, thereby increasing the speed of the closed-loop position control of the brushless DC motor.

[0112] Table 3 Active short circuit modulation method

[0113]

[0114] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0115] Based on the same inventive concept, the embodiment of the present application also provides a control device for a brushless DC motor for implementing the control method for a brushless DC motor involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in the embodiments of the control device for one or more brushless DC motors provided below can refer to the limitations of the control method for a brushless DC motor above, and will not be repeated here.

[0116] In one embodiment, Figure 8 As shown, a control device for a brushless DC motor is provided, which can be applied to Figure 1 The DC brushless motor shown in the figure, the control device of the DC brushless motor may include a rotor position processing module 810, a position closed-loop processing module 820 and a commutation control module 830. The rotor position processing module 810 is used to obtain the current position and target position of the motor rotor. Exemplarily, the rotor position processing module 810 is used to obtain the current position of the motor rotor according to the received Hall signal.

[0117] The position closed-loop processing module 820 is used to determine the target modulation mode of the power switch device from multiple candidate modulation modes according to the current position and the target position. The multiple candidate modulation modes include at least one of a commutation modulation mode, a short-circuit modulation mode and a combined modulation mode.

[0118] The commutation control module 830 is used to generate a target pulse width modulation signal according to the mode switching instruction to control the working state of the power switch device so that the motor rotor reaches the target position. The commutation control module 830 is used to control the power switch device based on the current position and the target position in the commutation modulation mode, control the power switch device to short-circuit the DC brushless motor in the short-circuit modulation mode, and control the power switch device based on the target position in the combined force modulation mode.

[0119] The control device of the brushless DC motor obtains the current position and target position of the motor rotor through the rotor position processing module 810, determines the target modulation mode of the power switch device from multiple candidate modulation modes according to the current position and the target position through the position closed-loop processing module 820, and generates a target pulse width modulation signal according to the target modulation mode through the commutation control module 830 to control the working state of the power switch device so that the motor rotor reaches the target position. This method does not need to calculate the rotation speed of the motor rotor, and can directly realize closed-loop control of the motor rotor position according to the current position of the motor rotor, thereby solving the problem that the motor rotation speed cannot be accurately calculated when the motor rotor is in a low-speed state, thereby improving the accuracy of the position control of the brushless DC motor.

[0120] In one embodiment, the position closed-loop processing module 820 includes a position difference unit and a threshold comparison unit. The position difference unit is connected to the rotor position processing module, and is used to obtain the absolute position difference according to the current position and the target position, and the absolute position difference is the absolute value of the difference between the current position and the target position. The threshold comparison unit is connected to the position difference unit, and the threshold comparison unit is used to determine that the target modulation mode is a phase-changing modulation mode when the absolute position difference is greater than the first position threshold; the threshold comparison unit is also used to determine that the target modulation mode is a short-circuit modulation mode when the absolute position difference is greater than or equal to the second position threshold and less than or equal to the first position threshold; the threshold comparison unit is also used to determine that the target modulation mode is a combined force modulation mode when the absolute position difference is less than the second position threshold. The second position threshold is less than the first position threshold.

[0121] For example, Fig. 9 As shown, the threshold comparison unit can determine the target modulation mode according to the absolute position difference, the first position threshold and the second position threshold, and generate a mode switching instruction PwmMod_cmd, which is used to represent the target modulation mode. Exemplarily, when the threshold comparison unit determines that the absolute position difference is greater than the first position threshold, that is, |pos_cmd-pos_val|>TH1, the target modulation mode is determined to be the phase-changing modulation mode, and the mode switching instruction PwmMod_cmd=1 is generated; when the threshold comparison unit determines that the absolute position difference is less than or equal to the first position threshold and greater than or equal to the second position threshold, that is, TH1≤|pos_cmd-pos_val|≤TH2, the target modulation mode is determined to be the short-circuit modulation mode, and the mode switching instruction PwmMod_cmd=2 is generated; when the threshold comparison unit determines that the absolute position difference is less than the second position threshold, that is, |pos_cmd-pos_val|<TH2, the target modulation mode is determined to be the combined force modulation mode, and the mode switching instruction PwmMod_cmd=3 is generated.

[0122] In one embodiment, the rotor position processing module 810 is also used to obtain the three-phase current of the DC brushless motor. The control device also includes a position closed-loop control module 840, a three-phase current processing module 850 and a torque closed-loop control module 860. Among them, the position closed-loop control module 840 is connected to the rotor position processing module 810, and the position closed-loop control module 840 is used to obtain the target current amplitude of the DC brushless motor according to the current position and the target position. The three-phase current processing module 850 is connected to the rotor position processing module 810, and the three-phase current processing module 850 is used to obtain the current current amplitude of the DC brushless motor according to the three-phase current, and the current current amplitude is the average value of the absolute value of the sum of the three-phase currents. The torque closed-loop control module 860 is respectively connected to the position closed-loop control module 840 and the three-phase current processing module 850, and the torque closed-loop control module 860 is used to generate a duty cycle instruction according to the current current amplitude and the target current amplitude.

[0123] In one embodiment, the position closed-loop processing module 820 is further configured to generate a mode switching instruction according to the target modulation mode. Fig.10 As shown, the commutation control module 830 includes a commutation modulation unit 831 , a short circuit modulation unit 832 , a combined force modulation unit 833 and a switching switch unit 834 .

[0124] Among them, the commutation modulation unit 831 is connected to the rotor position processing module 810 and the torque closed-loop control module 860 respectively, and the commutation modulation unit 831 is used to generate a first pulse width modulation signal according to the first commutation relationship corresponding to the current position, duty cycle instruction and commutation modulation mode; wherein the first commutation relationship at least includes the correspondence between the motor rotor position and the modulation mode of the power switching device.

[0125] The short-circuit modulation unit 832 is used to generate a second pulse width modulation signal according to the short-circuit modulation mode, and the second pulse width modulation signal is used to control the conduction of one group of switch tubes in the power switching device and the disconnection of another group of switch tubes; wherein each group of switch tubes is respectively connected to the DC brushless motor and the battery, and the two groups of switch tubes of the power switching device are connected in parallel.

[0126] The resultant force modulation unit 833 is connected to the rotor position processing module 810, and the resultant force modulation unit 833 is used to generate a third pulse width modulation signal according to the second commutation relationship corresponding to the target position and the resultant force modulation mode; wherein the second commutation relationship at least includes the correspondence between the direction of the electromagnetic resultant force, the motor rotor position and the modulation of the power switching device.

[0127] The switching switch unit 834 is respectively connected to the phase-changing modulation unit 831, the short-circuit modulation unit 832, the combined force modulation unit 833, and the position closed-loop processing module 820. The switching switch unit 834 is used to determine the target pulse width modulation signal from the first pulse width modulation signal, the second pulse width modulation signal, and the third pulse width modulation signal according to the mode switching instruction.

[0128] Each module in the control device of the brushless DC motor can be implemented in whole or in part by software, hardware or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0129] In one embodiment, a brushless DC motor is provided. The internal structure of the brushless DC motor can be as follows: Fig.11 As shown. The brushless DC motor includes a controller, a memory and a network interface connected through a system bus. Among them, the controller of the brushless DC motor is used to provide computing and control capabilities. The memory of the brushless DC motor 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 the computer program in the non-volatile storage medium. The database of the brushless DC motor is used to store data such as the first commutation relationship, the second commutation relationship, the Hall signal, and the three-phase current. The network interface of the brushless DC motor is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a control method for a brushless DC motor is implemented.

[0130] Those skilled in the art will understand that Fig.11 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present application, and does not constitute a limitation on the DC brushless motor to which the scheme of the present application is applied. The specific DC brushless motor may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0131] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the control method of the brushless DC motor provided in any of the above embodiments are implemented.

[0132] In one embodiment, a computer program product is provided, including a computer program, which, when executed by a processor, implements the steps of the method for controlling a brushless DC motor provided in any of the above embodiments.

[0133] 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.

[0134] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed 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 the memory, database or other medium used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0135] The technical features of the above embodiments may 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.

[0136] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for controlling a brushless DC motor, characterized in that: The brushless DC motor comprises a motor rotor and a power switch device, and the control method comprises: Obtaining the current position and target position of the motor rotor; Determine a target modulation mode of the power switch device from a plurality of candidate modulation modes according to the current position and the target position; wherein the plurality of candidate modulation modes include a commutation modulation mode, a short-circuit modulation mode and a combined modulation mode; Generate a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position; wherein the commutation modulation mode is to control the power switch device based on the current position, the target position and a first commutation relationship corresponding to the commutation modulation mode, the short-circuit modulation mode is to control the power switch device to short-circuit the DC brushless motor, and the resultant force modulation mode is to control the power switch device based on the target position and a second commutation relationship corresponding to the resultant force modulation mode; the first commutation relationship at least includes a corresponding relationship between the motor rotor position and the power switch device modulation mode; the second commutation relationship at least includes a corresponding relationship between the electromagnetic resultant force direction, the motor rotor position and the power switch device modulation; Wherein, determining the target modulation mode of the power switch device of the brushless DC motor from a plurality of candidate modulation modes according to the current position and the target position includes: Acquire a position absolute difference value according to the current position and the target position, wherein the position absolute difference value is an absolute value of a difference between the current position and the target position; When the position absolute difference is greater than a first position threshold, determining that the target modulation mode is the commutation modulation mode; In a case where the position absolute difference is greater than or equal to a second position threshold and less than or equal to the first position threshold, determining that the target modulation mode is the short-circuit modulation mode; wherein the second position threshold is less than the first position threshold; When the position absolute difference is less than the second position threshold, the target modulation mode is determined to be the combined force modulation mode.

2. The control method of the brushless DC motor according to claim 1, characterized in that: The target modulation mode is the commutation modulation mode, and generating a target pulse width modulation signal according to the target modulation mode includes: Obtaining the three-phase current of the brushless DC motor; generating a duty cycle instruction according to the current position, the target position and the three-phase current; A first pulse width modulation signal is generated according to the current position, the duty cycle instruction and a first commutation relationship corresponding to the commutation modulation mode.

3. The control method of the brushless DC motor according to claim 2, characterized in that: The step of generating a duty cycle instruction according to the current position, the target position and the three-phase current comprises: Acquire a current current amplitude of the brushless DC motor according to the three-phase current, wherein the current current amplitude is an average value of the absolute value of the sum of the three-phase current; Acquire a target current amplitude of the brushless DC motor according to the current position and the target position; The duty cycle instruction is generated according to the current current amplitude and the target current amplitude.

4. The control method of a brushless DC motor according to claim 1, characterized in that: The target modulation mode is the short-circuit modulation mode, and generating a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device includes: A second pulse width modulation signal is generated according to the short-circuit modulation mode to control the conduction of one group of switch tubes in the power switch device and the disconnection of another group of switch tubes; wherein each group of switch tubes is connected to the DC brushless motor and the battery respectively, and the two groups of switch tubes of the power switch device are connected in parallel.

5. The control method of a brushless DC motor according to claim 1, characterized in that: The target modulation mode is the combined force modulation mode, and generating a target pulse width modulation signal according to the target modulation mode includes: A third pulse width modulation signal is generated according to the target position and a second commutation relationship corresponding to the resultant force modulation mode.

6. A control device for a brushless DC motor, characterized in that: The brushless DC motor comprises a motor rotor and a power switch device, including: A rotor position processing module, used to obtain the current position and target position of the motor rotor; A position closed-loop processing module, configured to determine a target modulation mode of the power switch device from a plurality of candidate modulation modes according to the current position and the target position; wherein the plurality of candidate modulation modes include a commutation modulation mode, a short-circuit modulation mode and a combined force modulation mode; A commutation control module is used to generate a target pulse width modulation signal according to the target modulation mode to control the working state of the power switch device so that the motor rotor reaches the target position; wherein, The commutation control module is used to control the power switch device in the commutation modulation mode based on the current position, the target position and a first commutation relationship corresponding to the commutation modulation mode, control the power switch device in the short-circuit modulation mode to short-circuit the DC brushless motor, and control the power switch device in the resultant force modulation mode based on the target position and a second commutation relationship corresponding to the resultant force modulation mode; the first commutation relationship at least includes a corresponding relationship between the motor rotor position and the power switch device modulation mode; the second commutation relationship at least includes a corresponding relationship between the electromagnetic resultant force direction, the motor rotor position and the power switch device modulation; Wherein, the position closed-loop processing module includes: A position difference unit, connected to the rotor position processing module, for obtaining an absolute position difference according to the current position and the target position, wherein the absolute position difference is an absolute value of the difference between the current position and the target position; A threshold comparison unit is connected to the position difference unit, and is used to determine that the target modulation mode is the phase-changing modulation mode when the absolute position difference is greater than a first position threshold; to determine that the target modulation mode is the short-circuit modulation mode when the absolute position difference is greater than or equal to a second position threshold and less than or equal to the first position threshold; and to determine that the target modulation mode is the combined force modulation mode when the absolute position difference is less than the second position threshold; wherein the second position threshold is less than the first position threshold.

7. The control device for a brushless DC motor according to claim 6, characterized in that: The rotor position processing module is also used to obtain the three-phase current of the brushless DC motor. The control device also includes: A position closed-loop control module, connected to the rotor position processing module, and configured to obtain a target current amplitude of the brushless DC motor according to the current position and the target position; A three-phase current processing module, connected to the rotor position processing module, for obtaining a current current amplitude of the brushless DC motor according to the three-phase current, wherein the current current amplitude is an average value of the absolute value of the sum of the three-phase currents; The torque closed-loop control module is connected to the position closed-loop control module and the three-phase current processing module respectively, and is used to generate a duty cycle instruction according to the current current amplitude and the target current amplitude.

8. The control device of the brushless DC motor according to claim 7, characterized in that: The position closed-loop processing module is further used to generate a mode switching instruction according to the target modulation mode, and the phase switching control module includes: a commutation modulation unit, connected to the rotor position processing module and the torque closed-loop control module respectively, for generating a first pulse width modulation signal according to the current position, the duty cycle instruction and a first commutation relationship corresponding to the commutation modulation mode; wherein the first commutation relationship at least includes a corresponding relationship between the motor rotor position and the modulation mode of the power switch device; a short-circuit modulation unit, used for generating a second pulse width modulation signal according to the short-circuit modulation mode, wherein the second pulse width modulation signal is used for controlling the conduction of one group of switch tubes in the power switch device and the disconnection of another group of switch tubes; wherein each group of switch tubes is connected to the brushless DC motor and the battery respectively, and the two groups of switch tubes of the power switch device are connected in parallel; A resultant force modulation unit connected to the rotor position processing module, configured to generate a third pulse width modulation signal according to the target position and a second commutation relationship corresponding to the resultant force modulation mode; wherein the second commutation relationship at least includes a correspondence between the electromagnetic resultant force direction, the motor rotor position and the power switch device modulation; A switching switch unit is respectively connected to the phase-changing modulation unit, the short-circuit modulation unit, the combined force modulation unit, and the position closed-loop processing module, and is used to determine a target pulse width modulation signal from the first pulse width modulation signal, the second pulse width modulation signal, and the third pulse width modulation signal according to the mode switching instruction.

9. A brushless DC motor, characterized in that: include: Motor rotor and coil windings; A Hall sensor, used to obtain a Hall signal of the motor rotor; a controller connected to the Hall sensor, configured to obtain a target position of the motor rotor, obtain a current position of the motor rotor according to the Hall signal, determine a target modulation mode of the power switch device of the brushless DC motor from a plurality of candidate modulation modes according to the current position and the target position, and generate a target pulse width modulation signal according to the target modulation mode; wherein the plurality of candidate modulation modes include a commutation modulation mode, a short-circuit modulation mode, and a combined force modulation mode, wherein the commutation modulation mode controls the power switch device based on a first commutation relationship corresponding to the current position, the target position, and the commutation modulation mode, wherein the short-circuit modulation mode controls the power switch device to short-circuit the brushless DC motor, and wherein the combined force modulation mode controls the power switch device based on a second commutation relationship corresponding to the target position and the combined force modulation mode; wherein the first commutation relationship at least includes a corresponding relationship between the motor rotor position and the modulation mode of the power switch device; and wherein the second commutation relationship at least includes a corresponding relationship between the electromagnetic combined force direction, the motor rotor position, and the modulation of the power switch device. A power switch device is connected to the coil winding and the controller respectively, and is used to adjust the working state according to the target pulse width modulation signal and provide a driving current to the coil winding, so as to generate an electromagnetic field through the coil winding to drive the motor rotor to move to the target position; wherein, The controller is also used to obtain an absolute position difference according to the current position and the target position, wherein the absolute position difference is the absolute value of the difference between the current position and the target position; when the absolute position difference is greater than a first position threshold, the target modulation mode is determined to be the phase-changing modulation mode; when the absolute position difference is greater than or equal to a second position threshold and less than or equal to the first position threshold, the target modulation mode is determined to be the short-circuit modulation mode; wherein the second position threshold is less than the first position threshold; when the absolute position difference is less than the second position threshold, the target modulation mode is determined to be the combined force modulation mode.

10. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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