A control method, apparatus and storage medium

Abstract

This application discloses a control method for controlling a BLDCM (Block LDCM). The BLDCM's driving circuit includes a DC-DC converter and a three-phase inverter. The method includes: acquiring target values ​​of the controllable parameters of the BLDCM; adjusting the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter based on the target values ​​to obtain a target duty cycle of the DC-DC converter and a target conduction length of the switching transistors in the three-phase inverter; wherein the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM; controlling the DC-DC converter based on the target duty cycle; and controlling the three-phase inverter based on the target conduction length to drive the BLDCM. This application also discloses a control device and a storage medium.

Description

Technical Field

[0001] This application relates to the field of control technology for brushless direct current motors (BLDCM), and in particular to a control method, device and storage medium. Background Technology

[0002] Currently, BLDCMs typically use PWM duty cycle adjustment to regulate motor power / speed, or use PAM-based technology to adjust the duty cycle of the buck circuit to achieve a similar effect to adjusting the PWM duty cycle in a BLDCM, thereby controlling the input voltage of the inverter bridge to regulate motor power / speed. However, in the above solutions, the power / speed adjustment range of the BLDCM is very limited.

[0003] Application content

[0004] This application aims to provide a control method, apparatus, and storage medium to solve the problem of the very limited power / speed adjustment range of BLDCM in related technologies.

[0005] The technical solution of this application is implemented as follows:

[0006] A control method for controlling a BLDCM, the hardware drive circuit of the BLDCM comprising: a DC-DC converter and a three-phase inverter, including:

[0007] Obtain the target value of the controllable parameter of the BLDCM;

[0008] Based on the target value, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter; wherein, the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM;

[0009] The DC-DC converter is controlled based on the target duty cycle, and the three-phase inverter is controlled based on the target conduction length to drive the BLDCM.

[0010] A control device for controlling a BLDCM, the hardware drive circuit of the BLDCM comprising: a DC-DC converter and a three-phase inverter, including:

[0011] The acquisition module is used to acquire the target value of the controllable parameter of the BLDCM;

[0012] An adjustment module is used to adjust the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter based on the target values, respectively, to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter; wherein, the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM;

[0013] The control module is used to control the DC-DC converter based on the target duty cycle and the three-phase inverter based on the target conduction length to drive the BLDCM.

[0014] A control device, comprising:

[0015] The processor and a storage medium storing processor-executable instructions, the storage medium performing operations dependent on the processor via a communication bus, wherein when the instructions are executed by the processor, the control method described in one or more of the above embodiments is executed.

[0016] A storage medium storing one or more programs, which can be executed by one or more processors to implement the control method described in one or more of the above embodiments.

[0017] The control method, apparatus, and storage medium provided in this application embodiment are for controlling a BLDCM. The hardware driving circuit of the BLDCM includes a DC-DC converter and a three-phase inverter. The method includes: acquiring target values ​​of the controllable parameters of the BLDCM; adjusting the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter based on the target values ​​to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter; wherein the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM; controlling the DC-DC converter based on the target duty cycle and controlling the three-phase inverter based on the target conduction length to drive the BLDCM; that is, in this application embodiment, by... The target values ​​of the parameters to be controlled are obtained, and the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter are adjusted accordingly. This yields the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter. Based on this, the BLDCM is controlled so that the parameters to be controlled in the BLDCM get closer and closer to the target values. Here, the target values ​​are used not only to adjust the duty cycle of the DC-DC converter but also to adjust the conduction length of the switching transistors in the three-phase inverter. This allows the effective value of the phase current of the BLDCM to be further reduced even after the output voltage of the DC-DC converter is minimized, thereby expanding the power / speed adjustment range, i.e., improving the power / speed adjustment range of the BLDCM. Attached Figure Description

[0018] Figure 1 A flowchart illustrating an optional control method provided in an embodiment of this application;

[0019] Figure 2 This is a schematic diagram illustrating an optional control method for the BLDCM, provided as an embodiment of this application.

[0020] Figure 3a A flowchart illustrating an example of an optional control method provided in this application.

[0021] Figure 3b A flowchart illustrating an optional control method provided in this application embodiment, as an example two;

[0022] Figure 4a A flowchart illustrating an example of an optional control parameter provided in this application embodiment;

[0023] Figure 4b A flowchart illustrating an example two of optional control parameters provided in this application embodiment;

[0024] Figure 5aA flowchart illustrating an optional control method provided in this application embodiment, specifically Example 3;

[0025] Figure 5b A flowchart illustrating an example four of an optional control method provided in this application embodiment;

[0026] Figure 6 A schematic diagram illustrating optional control parameters for a BLDCM provided in an embodiment of this application;

[0027] Figure 7 A waveform diagram of the phase current of an optional BLDCM provided for an embodiment of this application;

[0028] Figure 8 This is a schematic diagram of an optional control device provided in an embodiment of this application;

[0029] Figure 9 This is a schematic diagram of another optional control device provided in an embodiment of this application. Detailed Implementation

[0030] To better understand the purpose, structure, and function of this application, a control method, apparatus, and storage medium of this application will be described in further detail below with reference to the accompanying drawings.

[0031] Embodiments of this application provide a control method for controlling a BLDCM (Block LDCM), wherein the driving circuit of the BLDCM may include a DC-DC converter and a three-phase inverter. Figure 1 A flowchart illustrating an optional control method provided in an embodiment of this application is shown below. Figure 1 As shown, the method may include:

[0032] S101: Obtain the target value of the controllable parameter of BLDCM;

[0033] Currently, the commonly used high-speed motor control scheme is BLDCM control using PWM technology, especially BLDCM control for 120-degree drive. However, since conventional BLDCM control technology requires adjusting the PWM duty cycle to regulate the motor speed / power, this results in the PWM control frequency being much higher than the motor's operating frequency. When the motor speed is very high, the PWM control frequency will be too high. This will not only significantly increase the switching losses and cost of the inverter, but also require the BLDCM control system to complete the control parameter calculation within a shorter control cycle, thereby increasing the cost of the microcontroller unit (MCU) and the difficulty of software design.

[0034] To address the problems of conventional BLDCM control, a high-speed motor control scheme based on PAM (Pulse Amplitude Regulation) has been proposed. Compared to BLDCM control, the PAM scheme requires a DC-DC converter added to the front end of the inverter bridge. Therefore, the inverter's switching frequency in the PAM scheme can be equal to the motor's operating frequency. The control strategy adjusts the duty cycle of the DC-DC converter (to achieve an effect similar to adjusting the PWM duty cycle in BLDCM) to control the input voltage of the inverter bridge, thereby regulating the motor speed / power. Compared to the traditional BLDCM scheme, the PAM scheme has lower inverter bridge losses and costs due to its lower switching frequency, and it also requires less computational power from the MCU. These advantages become more pronounced as the motor speed increases, so the PAM-based control scheme has been applied in many ultra-high-speed motor systems.

[0035] However, due to cost and size considerations, the front-end DC-DC converter circuit cannot reduce the output voltage (i.e., the inverter input voltage) to a sufficiently small level, resulting in very limited speed regulation capability of the motor system in the low power range and high conduction losses.

[0036] To expand the speed / power adjustment capability of the BLDCM, this application provides a control method. First, the target value of the controllable parameter of the BLDCM is obtained, wherein the controllable parameter includes any one of the following: the speed of the BLDCM, the power of the BLDCM; that is, the target speed of the BLDCM or the target power of the BLDCM is obtained, and these are used as target values ​​to adjust the duty cycle of the DC-DC converter and the conduction length of the switching transistors of the three-phase inverter. In this way, a large range of adjustment of the speed and power of the BLDCM can be achieved.

[0037] S102: Based on the target values, adjust the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter.

[0038] After obtaining the target value, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter can be adjusted based on the target value. The current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter are stored locally and can be obtained directly.

[0039] The current conduction length and target conduction length are conduction lengths relative to the electrical angle of the BLDCM. It is evident that the state of the three-phase inverter's switching transistors is related to the electrical angle of the BLDCM. Taking a 120-degree driven BLDCM as an example, when the rotor has a pair of magnetic poles, the electrical angle equals the mechanical angle, which is 360 degrees. To control the BLDCM, the maximum conduction length of the three-phase inverter's switching transistors is typically set to 120 degrees. That is, the maximum conduction length of the switching transistor within a 360-degree electrical angle is 120 degrees; at other electrical angles, the switching transistor is in the off state. It should be noted that, to achieve control of the BLDCM, the range of electrical angles corresponding to the conduction length of each switching transistor in the three-phase inverter is usually different.

[0040] The aforementioned current conduction length and target conduction length include the current conduction length and target conduction length of each switch.

[0041] Thus, the target duty cycle and target conduction length can be obtained based on the target value.

[0042] S103: Controls the DC-DC converter based on the target duty cycle and the three-phase inverter based on the target conduction length to drive the BLDCM.

[0043] After obtaining the target duty cycle and target conduction length, the state of the switching transistors in the DC-DC converter can be controlled using the target duty cycle to make the duty cycle of the DC-DC converter the target duty cycle. Similarly, the state of the switching transistors in the three-phase inverter can be controlled using the target conduction length to make the conduction length of the switching transistors in the three-phase inverter the target conduction length. This allows for the control of the speed or power of the BLDCM, making the speed of the BLDCM close to the target speed, or making the power of the BLDCM close to the target power.

[0044] For BLDCM startup, in order to adjust the BLDCM's speed or power, in one optional embodiment, the above method further includes:

[0045] Obtain the current voltage supplied by the DC-DC converter to the three-phase inverter;

[0046] Based on the preset mapping relationship, the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter are determined according to the target value and the current voltage.

[0047] Understandably, when BLDCM is first started, a preset mapping relationship can be stored in advance for the duty cycle of the DC-DC converter and the conduction length of the switching transistors in the three-phase inverter. The preset mapping relationship is the relationship between the controllable parameters and voltage and the duty cycle and conduction length. In this way, after obtaining the current voltage supplied by the DC-DC converter to the three-phase inverter, the corresponding duty cycle and conduction length can be found from the preset mapping relationship through the target value and the current voltage. That is, the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter.

[0048] In other words, after the BLDCM starts up, the target value and the current voltage supplied by the DC-DC converter to the three-phase inverter can be obtained through the mapping relationship. The target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter can then be mapped to obtain the target duty cycle and the target conduction length. Based on the target duty cycle and the target conduction length, the BLDCM can be controlled to make it close to the target value.

[0049] It should be noted that the lead angle of the BLDCM can also be adjusted here to control the speed or power of the BLDCM. Therefore, the preset mapping relationship can also be a relationship between the parameters to be controlled and the voltage and the duty cycle, conduction length and lead angle. Using this mapping relationship, the target duty cycle, target conduction length and target lead angle can be obtained.

[0050] In addition, after BLDCM completes startup, besides using the target values ​​to obtain the target duty cycle and target conduction length, in an optional embodiment, the above method further includes:

[0051] When the current voltage is less than the preset voltage threshold, return to execute the preset mapping relationship, and determine the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter based on the target value and the current voltage.

[0052] In practical applications, the current voltage decreases as the BLDCM is used. To prevent the current voltage from decreasing and to make the control of the BLDCM more suitable for the actual use of the BLDCM, the control of the BLDCM detects the change in the current voltage. When the current voltage is less than a preset voltage threshold, the process returns to the above-mentioned re-determining of the target duty cycle and target conduction length based on the preset mapping relationship. For the case where the current voltage is greater than or equal to the preset voltage threshold, the above-mentioned S102 and S103 can be used to control the BLDCM to make it closer to the target value.

[0053] To achieve a wide range of speed / power adjustments for the BLDCM, in one optional embodiment, S102 may include:

[0054] Obtain the measured values ​​of the controlled parameters of BLDCM and calculate the difference between the measured values ​​and the target values;

[0055] When the difference is positive and greater than the preset threshold, based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter.

[0056] When the difference is negative and the absolute value of the difference is greater than the preset threshold, the current duty cycle of the DC-DC converter and the current conduction length of the three-phase inverter's switching transistors are adjusted based on the relationship between the current conduction length of the three-phase inverter's switching transistors and the preset conduction length threshold, so as to obtain the target duty cycle of the DC-DC converter and the target conduction length of the three-phase inverter's switching transistors.

[0057] Understandably, the measured values ​​of the parameters to be controlled by the BLDCM are obtained first. After calculating the difference between the target value and the measured value, if the absolute value of the difference is less than the preset threshold, the current duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter are not adjusted, and the original parameters are maintained.

[0058] If the absolute value of the difference is greater than the preset threshold and the difference is positive, in order to adjust the duty cycle and conduction length, the current duty cycle and current conduction length are adjusted based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold to obtain the target duty cycle and target conduction length. Here, the preset first duty cycle threshold is less than the preset second duty cycle threshold.

[0059] If the absolute value of the difference is less than the preset threshold and the difference is negative, in order to adjust the duty cycle and conduction length, the current duty cycle and current conduction length are adjusted based on the relationship between the current conduction length of the switching transistor in the three-phase inverter and the preset conduction length threshold to obtain the target duty cycle and target conduction length. Here, the preset conduction length threshold can be the maximum value of the conduction length. For example, for a 120-degree driven BLDCM, the preset conduction length threshold is 120 degrees.

[0060] When the absolute value of the difference equals a preset threshold, the original duty cycle and conduction length can be maintained. Alternatively, the difference can be categorized according to its sign. When the difference is positive, the current duty cycle and conduction length are adjusted based on the relationship between the current duty cycle of the DC-DC converter and a preset first duty cycle threshold to obtain the target duty cycle and target conduction length. When the difference is negative, the current duty cycle and conduction length are adjusted based on the relationship between the current conduction length of the switching transistors in the three-phase inverter and a preset conduction length threshold to obtain the target duty cycle and target conduction length. In this way, the duty cycle and conduction length can be adjusted. Currently, other methods can also be used to adjust the current duty cycle and current conduction length, but this application embodiment does not specifically limit these methods.

[0061] To obtain the target duty cycle and target conduction length based on the relationship between the current duty cycle and a preset first duty cycle threshold, in an optional embodiment, based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors of the three-phase inverter, including:

[0062] When the current duty cycle of the DC-DC converter is less than the preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0063] When the current duty cycle of the DC-DC converter is greater than the preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

[0064] Here, the current duty cycle is first determined to be smaller than the preset first duty cycle threshold. When the current duty cycle is smaller than the preset first duty cycle threshold, the current duty cycle needs to be reduced to reduce power. The target duty cycle can be obtained by reducing the current duty cycle by a preset duty cycle step size. Of course, other methods can also be used to reduce the current duty cycle to obtain the target duty cycle. Here, this application embodiment does not specifically limit this.

[0065] By determining that when the current duty cycle is greater than a preset first duty cycle threshold, the current duty cycle length needs to be reduced to reduce power. The target duty cycle length can be obtained by reducing the current duty cycle length by a preset duty cycle length step. Of course, other methods can also be used to reduce the current duty cycle length to obtain the target duty cycle length. Here, this application embodiment does not specifically limit this.

[0066] In addition, for the case where the current duty cycle is equal to the preset first duty cycle threshold, the case where the current duty cycle is less than the preset first duty cycle threshold can be handled, or the case where the current duty cycle is greater than the preset first duty cycle threshold can be handled. Here, the embodiments of this application do not make specific limitations on this.

[0067] Furthermore, to expand the speed / power adjustment range, the lead angle of the BLDCM can also be adjusted. In one optional embodiment, when the current duty cycle of the DC-DC converter is less than a preset duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter, including:

[0068] When the current leading angle of BLDCM is greater than the preset angle threshold, the difference between the current leading angle of BLDCM and the preset leading angle step size is determined as the target leading angle of BLDCM.

[0069] When the current lead angle of the BLDCM is less than the preset angle threshold and the current duty cycle of the DC-DC converter is less than the preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0070] During the adjustment of the current duty cycle and the current conduction length, the relationship between the current lead angle of the BLDC and the preset angle threshold is first determined. After the determination, when the current lead angle of the BLDC is greater than the preset angle threshold, the current lead angle needs to be reduced to reduce the power. Here, the target lead angle is obtained by reducing the current lead angle by a preset lead angle step size.

[0071] If, after judgment, the current lead angle of BLDCM is less than the preset angle threshold, it is necessary to further determine the relationship between the current duty cycle and the preset first duty cycle threshold time. If it is less, the current duty cycle needs to be reduced. Here, the current duty cycle is reduced by a preset duty cycle step size to obtain the target duty cycle.

[0072] For cases where the current leading angle is equal to a preset angle threshold, the above-mentioned case of being greater than or less than the aforementioned case can be used for processing. Here, the embodiments of this application do not specifically limit this.

[0073] In adjusting the lead angle of the BLDCM, in one optional embodiment, when the current duty cycle of the DC-DC converter is greater than a preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistors and a preset conduction length step is determined as the target conduction length of the three-phase inverter's switching transistors, including:

[0074] When the current lead angle of the BLDCM is less than the preset angle threshold and the current duty cycle of the DC-DC converter is greater than the preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

[0075] Understandably, when the current lead angle is less than a preset angle threshold and the current duty cycle is greater than a preset first duty cycle threshold, it is necessary to reduce the current conduction length to reduce power. Here, the current conduction length is reduced by a preset conduction length step to obtain the target conduction length. Of course, other methods can also be used to reduce the current conduction length. Here, this application embodiment does not specifically limit this.

[0076] In addition, for the case where the current duty cycle is equal to the preset first duty cycle threshold, it can be handled by referring to the case where it is less than, or by referring to the case where it is greater than. Here, the embodiments of this application do not make specific limitations on this.

[0077] In adjusting the current duty cycle and current conduction length, in one optional embodiment, based on the relationship between the current conduction length of the three-phase inverter's switching transistors and a preset conduction length threshold, the current duty cycle of the DC-DC converter and the current conduction length of the three-phase inverter's switching transistors are adjusted respectively to obtain the target duty cycle of the DC-DC converter or the target conduction length of the three-phase inverter's switching transistors, including:

[0078] When the current conduction length of the switching transistor of the three-phase inverter is less than the preset conduction length threshold, the sum of the current conduction length and the preset conduction length step size is determined as the target conduction length of the switching transistor of the three-phase inverter.

[0079] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0080] Understandably, the relationship between the current conduction length and the preset conduction length threshold is first determined. When the current conduction length is less than the preset conduction length threshold, the current conduction length needs to be increased to increase the power. Therefore, the current conduction length is added to the preset conduction length step size to obtain the target conduction length. Of course, other methods can also be used to increase the current conduction length. Here, this application embodiment does not specifically limit this.

[0081] When the current conduction length is equal to the preset conduction length threshold, it is necessary to further determine the relationship between the current duty cycle and the preset second duty cycle. When the current duty cycle is less than the preset second duty cycle threshold, the current duty cycle is increased to increase the power. This can be done by adding the current duty cycle to the preset duty cycle step size to obtain the target duty cycle. Of course, other methods can also be used to increase the current duty cycle. Here, this application embodiment does not specifically limit this.

[0082] Furthermore, to expand the adjustment range of speed / power, an adjustment of the current lead angle of the BLDCM can be added. In one optional embodiment, when the current conduction length of the three-phase inverter's switching transistors is equal to a preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than a preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and a preset duty cycle step size is determined as the target duty cycle of the DC-DC converter, including:

[0083] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is equal to the preset second duty cycle threshold, the sum of the current lead angle of the BLDCM and the preset lead angle step size is determined as the target lead angle of the BLDCM.

[0084] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0085] In other words, when the current conduction length is equal to the preset conduction length threshold and the current duty cycle is equal to the preset second duty cycle threshold, the current lead angle needs to be increased to increase the power. This can be achieved by adding the current lead angle to the preset lead angle step size to obtain the target lead angle of the BLDCM. Of course, other methods can also be used to increase the current lead angle. Here, this application embodiment does not specifically limit this.

[0086] When the current conduction length is equal to the preset conduction length threshold and the current duty cycle is less than the preset second duty cycle threshold, the current duty cycle needs to be increased. This can be achieved by adding the current duty cycle to the preset duty cycle step size to obtain the target duty cycle and increase the power. Of course, other methods can also be used to increase the current duty cycle. Here, this application embodiment does not specifically limit this.

[0087] The following examples illustrate the control method described in one or more of the above embodiments.

[0088] Figure 2The diagram illustrates an optional control method for the BLDCM, as provided in this application embodiment. Figure 2 As shown, the hardware drive circuit of the BLDCM includes: a battery, a DC-DC converter (also known as a buck circuit), and a three-phase inverter. In this example, the control parameter table and the speed / power closed-loop control system are used to control the drive circuit in order to control the BLDCM.

[0089] The closed-loop control system includes a current and voltage measurement module for input power calculation and a rotor position detection module for motor speed estimation.

[0090] exist Figure 2 In the process, the main software module, "Control Parameter Table and Speed / Power Closed-Loop Control System," receives and processes information such as target power (or target speed), measured voltage, measured power, measured speed, and rotor position to generate parameters such as the duty cycle parameter of the DC-DC converter (equivalent to the aforementioned target duty cycle), the conduction time of the inverter bridge (equivalent to the aforementioned target conduction length), and the lead angle (equivalent to the aforementioned target lead angle), ultimately achieving the purpose of controlling the motor power (or speed).

[0091] Based on the above Figure 2 The structure and control strategy, Figure 3a A flowchart illustrating an example of an optional control method provided in this application is shown below. Figure 3a As shown, the control method may include:

[0092] S3a01: Boot-up acceleration;

[0093] S3a02: Startup process complete;

[0094] S3a03: Obtain the target power value;

[0095] S3a04: Set the initial control parameters using the control parameter table;

[0096] S3a05: Enter the control parameter setting loop for the next control cycle; when a new target power command is received, return to execute S3a03.

[0097] S3a06: After receiving the shutdown command, the shutdown deceleration is reduced.

[0098] Based on the above Figure 2 The structure and control strategy, Figure 3b A flowchart illustrating an example two of an optional control method provided in this application is shown below. Figure 3b As shown,

[0099] S3b01: Boot-up acceleration;

[0100] S3b02: Startup process complete;

[0101] S3b03: Obtain the target velocity value;

[0102] S3b04: Set initial control parameters using the control parameter table;

[0103] S3b05: Enter the control parameter setting loop for the next control cycle; when a new target speed command is received, return to execute S3b03.

[0104] S3b06: After receiving the shutdown command, the shutdown deceleration is reduced.

[0105] In other words, after powering on, the BLDCM accelerates. After the startup process is complete, it obtains the target power value or target speed value and sets the initial control parameters using the control parameter table. That is, it obtains the duty cycle, conduction length, and lead angle from the control parameter table by looking up the target power value and the current voltage, or it obtains the duty cycle, conduction length, and lead angle from the control parameter table by looking up the target speed value and the current voltage. In the next control cycle, it uses the obtained duty cycle, conduction length, and lead angle to control the hardware drive circuit. When a new target power value or a new target speed value is received, it returns to execute the setting of the duty cycle, conduction length, and lead angle.

[0106] It should be noted that, Figure 3a and Figure 3b Two startup / running / shutdown processes based on power control and speed control were demonstrated respectively. After the initial startup process is completed or the system receives a new target power / target speed command, the system will use the control parameter table to look up the initial control parameters in order to quickly approach the target power / speed. After that, the system will enter the control parameter setting process for the next control cycle.

[0107] The aforementioned control cycle is a cycle that includes at least one electrical angle or more electrical angles.

[0108] Based on the above Figure 3a , Figure 4a A flowchart illustrating an example of an optional control parameter provided in this application is shown below. Figure 4a As shown, the output items of the control parameter table are the duty cycle of the DC-DC converter, the conduction length of the switching transistors of the three-phase inverter (which can be indicated as a percentage), and the lead angle of the BLDCM. In power control mode, the input items of the control parameter table are the target power and the current voltage, where the current voltage is the output voltage of the DC-DC converter (the input voltage of the three-phase inverter).

[0109] Based on the above Figure 3b , Figure 4bA flowchart illustrating an example two of optional control parameters provided in this application is shown below. Figure 4b As shown, the output items of the control parameter table are the duty cycle of the DC-DC converter, the conduction length of the switching transistors of the three-phase inverter, and the lead angle of the three-phase inverter. In the speed control mode, the input items of the control parameter table are the target speed and the current voltage, as shown in Figure 4(b).

[0110] After the control parameters for the current control cycle are set, the system enters the control parameter setting process for the next control cycle. Figure 5a A flowchart illustrating an example three of an optional control method provided in this application is shown below. Figure 5a As shown, the control method may include:

[0111] S5a01: Start setting the control parameters for the next control cycle;

[0112] S5a02: Acquire Hall signals and update speed information based on the latest acquired signals;

[0113] S5a03: Obtain the target power and the measured power, and calculate the power difference (measured power is calculated from - target power);

[0114] S5a04: Determine if the power difference is greater than the preset threshold. If yes, execute S5a05; if no, execute S5a06.

[0115] S5a05: Determine if the power difference is positive? If yes, proceed to S5a07; if no, proceed to S5a08.

[0116] S5a06: The next control cycle will use the same control parameters as this control cycle, and S5a17 will be executed.

[0117] S5a07: Determine if the leading angle is the minimum value of the leading angle? If yes, execute S5a09; if no, execute S5a11.

[0118] S5a08: Determine if the conduction length reaches 120 degrees? If yes, execute S5a10; if no, execute S5a16.

[0119] S5a09: Determine if the duty cycle has reached the lower limit. If yes, execute S5a13; if no, execute S5a12.

[0120] S5a10: Determine if the duty cycle has reached its upper limit. If yes, execute S5a14; if no, execute S5a15.

[0121] S5a11: In the next control cycle, the lead angle decreases by a preset lead angle step, and S5a17 is executed.

[0122] S5a12: In the next control cycle, the duty cycle decreases by a preset duty cycle step, and S5a17 is executed.

[0123] S5a13: In the next control cycle, the conduction length decreases by a preset conduction length step, and S5a17 is executed.

[0124] S5a14: In the next control cycle, the lead angle increases by a preset lead angle step, and S5a17 is executed.

[0125] S5a15: In the next control cycle, the duty cycle increases by a preset duty cycle step, and S5a17 is executed.

[0126] S5a16: In the next control cycle, the conduction length increases by a preset conduction length step, and S5a17 is executed.

[0127] S5a17: End setting of control parameters.

[0128] Figure 5b A flowchart illustrating an example four of an optional control method provided in this application is shown below. Figure 5b As shown,

[0129] S5b01: Start setting control parameters for the next control cycle;

[0130] S5b02: Acquires Hall signals and updates speed information based on the latest acquired signals;

[0131] S5b03: Obtain the target speed and measured speed of the current motor, and calculate the power difference (measured speed from - target speed);

[0132] S5b04: Determine if the speed difference is greater than the preset threshold. If yes, execute S5b05; if no, execute S5b06.

[0133] S5b05: Determine if the speed difference is positive. If yes, proceed to S5b07; if no, proceed to S5b08.

[0134] S5b06: The next control cycle uses the same control parameters as this control cycle, and executes S5b17.

[0135] S5b07: Determine if the leading angle is the minimum value of the leading angle? If yes, execute S5b09; if no, execute S5b11.

[0136] S5b08: Determine if the conduction length reaches 120 degrees? If yes, execute S5b10; if no, execute S5b16.

[0137] S5b09: Determine if the duty cycle has reached the lower limit. If yes, execute S5b13; if no, execute S5b12.

[0138] S5b10: Determine if the duty cycle has reached its upper limit. If yes, execute S5b14; if no, execute S5b15.

[0139] S5b11: In the next control cycle, the lead angle decreases by a preset lead angle step, and S5b17 is executed.

[0140] S5b12: In the next control cycle, the duty cycle decreases by a preset duty cycle step, and S5b17 is executed.

[0141] S5b13: In the next control cycle, the conduction length decreases by a preset conduction length step, and S5b17 is executed.

[0142] S5b14: In the next control cycle, the lead angle increases by a preset lead angle step, and S5b17 is executed.

[0143] S5b15: In the next control cycle, the duty cycle increases by a preset duty cycle step, and S5b17 is executed.

[0144] S5b16: In the next control cycle, the conduction length increases by a preset conduction length step, and S5b17 is executed.

[0145] S5b17: End setting of control parameters.

[0146] In response to the above Figure 5a and Figure 5b It can be seen that in order to reduce system disturbances, when the difference between the target power or target speed and the measured power or measured speed is less than the set threshold, the control parameters of the next control cycle will continue to use the current control parameters, and the control parameter setting process will end.

[0147] When the system determines that the difference between power or speed is positive and exceeds a threshold, if the current BLDCM's lead angle has not reached the preset minimum lead angle, the system will decrease the lead angle by one step size and end the control parameter setting process in the next control cycle. Otherwise, if the current BLDCM's lead angle has reached the preset minimum lead angle, the system will continue to determine whether the current DC-DC converter's duty cycle has reached the preset lower limit of the duty cycle. If yes, the system will decrease the duty cycle by one preset step size and end the control parameter setting process in the next control cycle. Otherwise, the system will decrease the conduction length by one preset step size and end the control parameter setting process in the next control cycle.

[0148] When the system determines that the difference between power or speed is negative and exceeds a preset threshold, if the current conduction length of the BLDCM has not reached the preset maximum conduction length (120 electrical degrees in 120-degree BLDCM control), the system will increase the conduction length by a preset step size in the next control cycle and end the control parameter setting process; otherwise, if the current conduction length of the BLDCM has reached the preset maximum conduction length, the system will continue to determine whether the duty cycle of the current DC-DC converter has reached the preset upper limit of the duty cycle. If yes, it will increase the lead angle by a preset step size in the next control cycle and end the control parameter setting process; otherwise, it will increase the duty cycle by a preset step size in the next control cycle and end the control parameter setting process.

[0149] Figure 6 A schematic diagram of optional control parameters for BLDCM provided in an embodiment of this application is shown below. Figure 6 As shown, the conduction lengths of switches S1, S2, S3, S4, S5, and S6 in a 360-degree electrical angle are determined. After the lead angle and conduction length parameters of the BLDCM in the next control cycle are determined, the system will estimate the back EMF zero-crossing point position in the next control cycle based on the speed and rotor position signals of the current control cycle, and turn on the corresponding switches in the inverter bridge in advance according to the pre-set control parameters. The conduction length of each switch is less than or equal to 120 electrical degrees.

[0150] Figure 7 A waveform diagram of the phase current of an optional BLDCM provided for an embodiment of this application, such as... Figure 7 As shown, the dashed line represents the minimum current waveform in the traditional PAM scheme, and the solid line represents the minimum current waveform after adjusting the conduction length. It can be seen that the conduction length of the switching transistors of the three-phase inverter is adjustable. Compared with the traditional PAM control, this can further reduce the effective value of the phase current after the DC-DC converter output voltage is at its minimum, so as to achieve the purpose of expanding the lower limit of the debugging range. Moreover, this beneficial effect will not lead to an increase in system cost or a decrease in efficiency.

[0151] It should be noted that the above-mentioned adjustment and control of control parameters can be achieved by using a proportional-integral (PI) controller.

[0152] The control method provided in this application embodiment is used to control a BLDCM. The hardware driving circuit of the BLDCM includes a DC-DC converter and a three-phase inverter. The method includes: acquiring target values ​​of the controllable parameters of the BLDCM; adjusting the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter based on the target values ​​to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter; wherein the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM; controlling the DC-DC converter based on the target duty cycle and controlling the three-phase inverter based on the target conduction length to drive the BLDCM; that is, in this application embodiment, by acquiring the target values ​​of the controllable parameters of the BLDCM, the method adjusts the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter to drive the BLDCM. The target values ​​of the parameters to be controlled are obtained by adjusting the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter. This yields the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter. Based on this, the BLDCM is controlled so that the parameters to be controlled in the BLDCM get closer and closer to the target values. Here, the target values ​​are used not only to adjust the duty cycle of the DC-DC converter but also to adjust the conduction length of the switching transistors in the three-phase inverter. This allows the effective value of the phase current in the BLDCM to be further reduced even after the output voltage of the DC-DC converter has reached its minimum, thereby expanding the power / speed adjustment range, i.e., increasing the power / speed adjustment range of the BLDCM.

[0153] Based on the same inventive concept, embodiments of this application provide a control device. Figure 8 This is a schematic diagram of an optional control device provided in an embodiment of this application, with reference to... Figure 8 As shown, it includes: an acquisition module 81, an adjustment module 82, and a control module 83; wherein,

[0154] The acquisition module 81 is used to acquire the target value of the controllable parameter of BLDCM;

[0155] The adjustment module 82 is used to adjust the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors in the three-phase inverter based on the target values, so as to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter; wherein, the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the BLDCM.

[0156] The control module 83 is used to control the DC-DC converter based on the target duty cycle and the three-phase inverter based on the target conduction length to drive the BLDCM.

[0157] In other embodiments of this application, the parameter to be controlled includes any one of the following:

[0158] The rotational speed and power of the BLDCM.

[0159] In other embodiments of this application, the control device is further used for:

[0160] Obtain the current voltage supplied by the DC-DC converter to the three-phase inverter;

[0161] Based on the preset mapping relationship, the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter are determined according to the target value and the current voltage.

[0162] The preset mapping relationship is a relationship between the controlled parameters and voltage and the duty cycle and conduction length.

[0163] In other embodiments of this application, the control device is further used for:

[0164] When the current voltage is less than the preset voltage threshold, return to execute the preset mapping relationship, and determine the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter according to the target value and the current voltage.

[0165] In other embodiments of this application, the adjustment module 82 is specifically used for:

[0166] Obtain the measured values ​​of the controlled parameters of BLDCM and calculate the difference between the measured values ​​and the target values;

[0167] When the difference is positive and greater than the preset threshold, based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter.

[0168] When the difference is negative and the absolute value of the difference is greater than the preset threshold, the current duty cycle of the DC-DC converter and the current conduction length of the three-phase inverter's switching transistors are adjusted based on the relationship between the current conduction length of the three-phase inverter's switching transistors and the preset conduction length threshold, so as to obtain the target duty cycle of the DC-DC converter and the target conduction length of the three-phase inverter's switching transistors.

[0169] In other embodiments of this application, the adjustment module 82 adjusts the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter based on the relationship between the current duty cycle of the DC-DC converter and a preset first duty cycle threshold, respectively, to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors of the three-phase inverter, including:

[0170] When the current duty cycle of the DC-DC converter is less than the preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0171] When the current duty cycle of the DC-DC converter is greater than the preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

[0172] In other embodiments of this application, when the current duty cycle of the DC-DC converter is less than a preset duty cycle threshold, the adjustment module 82 determines the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size as the target duty cycle of the DC-DC converter, including:

[0173] When the current leading angle of BLDCM is greater than the preset angle threshold, the difference between the current leading angle of BLDCM and the preset leading angle step size is determined as the target leading angle of BLDCM.

[0174] When the current lead angle of the BLDCM is less than the preset angle threshold and the current duty cycle of the DC-DC converter is less than the preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0175] In other embodiments of this application, when the current duty cycle of the DC-DC converter is greater than a preset first duty cycle threshold, the adjustment module 82 determines the difference between the current conduction length of the three-phase inverter's switching transistors and a preset turn-on length step as the target conduction length of the three-phase inverter's switching transistors, including:

[0176] When the current lead angle of the BLDCM is less than the preset angle threshold and the current duty cycle of the DC-DC converter is greater than the preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

[0177] In other embodiments of this application, the adjustment module 82 adjusts the current duty cycle of the DC-DC converter and the current conduction length of the three-phase inverter's switching transistors based on the relationship between the current conduction length of the three-phase inverter's switching transistors and a preset conduction length threshold, respectively, to obtain the target duty cycle of the DC-DC converter or the target conduction length of the three-phase inverter's switching transistors, including:

[0178] When the current conduction length of the switching transistor of the three-phase inverter is less than the preset conduction length threshold, the sum of the current conduction length and the preset conduction length step size is determined as the target conduction length of the switching transistor of the three-phase inverter.

[0179] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0180] In other embodiments of this application, when the current conduction length of the switching transistor of the three-phase inverter is equal to a preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than a preset second duty cycle threshold, the adjustment module 82 determines the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size as the target duty cycle of the DC-DC converter, including:

[0181] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is equal to the preset second duty cycle threshold, the sum of the current lead angle of the BLDCM and the preset lead angle step size is determined as the target lead angle of the BLDCM.

[0182] When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

[0183] In practical applications, the aforementioned acquisition module 81, adjustment module 82, and control module 83 can be implemented by a processor located on the control device, specifically a central processing unit (CPU), microprocessor (MPU), digital signal processor (DSP), or field programmable gate array (FPGA), etc.

[0184] Figure 9 This is a schematic diagram of an optional control device provided in an embodiment of this application, such as... Figure 9 As shown, this application embodiment provides a control device 900, including:

[0185] The processor 91 and the storage medium 92 storing instructions executable by the processor 91, the storage medium 92 performing operations via a communication bus 93 dependent on the processor 91, and when the instructions are executed by the processor 91, the control method described in one or more of the above embodiments is executed.

[0186] It should be noted that in practical applications, the various components in the terminal are coupled together via the communication bus 93. It can be understood that the communication bus 93 is used to achieve communication between these components. In addition to the data bus, the communication bus 93 also includes a power bus, a control bus, and a status signal bus. However, for clarity, in... Figure 9 The general labeled all buses as communication bus 93.

[0187] Embodiments of this application provide a storage medium that stores one or more programs, which can be executed by one or more processors using the control method provided in the embodiments of this application.

[0188] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0189] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0190] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0191] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0192] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application.

Claims

1. A control method characterized by, The method is used to control a brushless DC motor. The hardware drive circuit of the brushless DC motor includes a DC-DC converter and a three-phase inverter, comprising: Obtain the target values ​​of the controllable parameters of the brushless DC motor; Obtain the measured values ​​of the controllable parameters of the brushless DC motor, and calculate the difference between the measured values ​​and the target values; When the difference is positive and greater than a preset threshold, based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter. When the difference is negative and the absolute value of the difference is greater than a preset threshold, based on the relationship between the current conduction length of the switching transistor of the three-phase inverter and the preset conduction length threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter; wherein, the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the brushless DC motor; The DC-DC converter is controlled based on the target duty cycle, and the three-phase inverter is controlled based on the target conduction length to drive the brushless DC motor.

2. The method of claim 1, wherein, The parameter to be controlled includes any one of the following: The rotational speed of the brushless DC motor and the power of the brushless DC motor.

3. The method of claim 1, wherein, The method further includes: Obtain the current voltage supplied by the DC-DC converter to the three-phase inverter; Based on a preset mapping relationship, the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter are determined according to the target value and the current voltage. The preset mapping relationship is a relationship between the controllable parameters and voltage and the duty cycle and conduction length.

4. The method according to claim 3, characterized in that, The method further includes: When the current voltage is less than a preset voltage threshold, the process returns to the preset mapping relationship and determines the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors in the three-phase inverter based on the target value and the current voltage.

5. The method of claim 1, wherein, The method, based on the relationship between the current duty cycle of the DC-DC converter and a preset first duty cycle threshold, adjusts the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistors of the three-phase inverter, including: When the current duty cycle of the DC-DC converter is less than a preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter. When the current duty cycle of the DC-DC converter is greater than the preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

6. The method of claim 5, wherein, When the current duty cycle of the DC-DC converter is less than a preset duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter, including: When the current lead angle of the brushless DC motor is greater than the preset angle threshold, the difference between the current lead angle of the brushless DC motor and the preset lead angle step size is determined as the target lead angle of the brushless DC motor. When the current lead angle of the brushless DC motor is less than a preset angle threshold, and the current duty cycle of the DC-DC converter is less than a preset first duty cycle threshold, the difference between the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

7. The method of claim 6, wherein, When the current duty cycle of the DC-DC converter is greater than a preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and a preset turn-on length step size is determined as the target conduction length of the three-phase inverter's switching transistor, including: When the current lead angle of the brushless DC motor is less than a preset angle threshold and the current duty cycle of the DC-DC converter is greater than a preset first duty cycle threshold, the difference between the current conduction length of the three-phase inverter's switching transistor and the preset conduction length step size is determined as the target conduction length of the three-phase inverter's switching transistor.

8. The method of claim 1, wherein, The relationship between the current conduction length of the switching transistors of the three-phase inverter and a preset conduction length threshold is used to adjust the current duty cycle of the DC-DC converter and the current conduction length of the switching transistors of the three-phase inverter, respectively, to obtain the target duty cycle of the DC-DC converter or the target conduction length of the switching transistors of the three-phase inverter, including: When the current conduction length of the switching transistor of the three-phase inverter is less than the preset conduction length threshold, the sum of the current conduction length and the preset conduction length step size is determined as the target conduction length of the switching transistor of the three-phase inverter. When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

9. The method of claim 8, wherein, When the current conduction length of the switching transistor of the three-phase inverter is equal to a preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than a preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and a preset duty cycle step size is determined as the target duty cycle of the DC-DC converter, including: When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is equal to the preset second duty cycle threshold, the sum of the current lead angle of the brushless DC motor and the preset lead angle step size is determined as the target lead angle of the brushless DC motor. When the current conduction length of the switching transistor of the three-phase inverter is equal to the preset conduction length threshold, and the current duty cycle of the DC-DC converter is less than the preset second duty cycle threshold, the sum of the current duty cycle of the DC-DC converter and the preset duty cycle step size is determined as the target duty cycle of the DC-DC converter.

10. A control device, characterized in that, The device is used to control a brushless DC motor. The hardware drive circuit of the brushless DC motor includes a DC-DC converter and a three-phase inverter, comprising: The acquisition module is used to acquire the target values ​​of the controllable parameters of the brushless DC motor; Adjustment module, used for: Obtain the measured values ​​of the controllable parameters of the brushless DC motor, and calculate the difference between the measured values ​​and the target values; When the difference is positive and greater than a preset threshold, based on the relationship between the current duty cycle of the DC-DC converter and the preset first duty cycle threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter. When the difference is negative and the absolute value of the difference is greater than a preset threshold, based on the relationship between the current conduction length of the switching transistor of the three-phase inverter and the preset conduction length threshold, the current duty cycle of the DC-DC converter and the current conduction length of the switching transistor of the three-phase inverter are adjusted respectively to obtain the target duty cycle of the DC-DC converter and the target conduction length of the switching transistor of the three-phase inverter; wherein, the current conduction length and the target conduction length are conduction lengths relative to the electrical angle of the brushless DC motor; The control module is used to control the DC-DC converter based on the target duty cycle and the three-phase inverter based on the target conduction length to drive the brushless DC motor.

11. A control device characterized by comprising: include: The processor and a storage medium storing processor-executable instructions, the storage medium performing operations dependent on the processor via a communication bus, wherein when the instructions are executed by the processor, the control method according to any one of claims 1 to 9 is performed.

12. A storage medium, characterized by The storage medium stores one or more programs, which can be executed by one or more processors to implement the control method as described in any one of claims 1 to 9.

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