A method, device and medium for improving the success rate of open-loop and closed-loop of a non-inductive BLDC

Abstract

This invention discloses a method, device, and medium for improving the success rate of switching from open-loop to closed-loop control in a sensorless BLDC converter. The open-loop to closed-loop switching condition is determined by detecting the zero-crossing point of the back electromotive force to ascertain whether the current state meets the basic conditions for switching the BLDC from open-loop to closed-loop. The high-torque transition involves appropriately extending the commutation time after the zero-crossing point during the initial switching period, providing high torque to the BLDC and preventing failure to switch from open-loop to closed-loop control under heavy load conditions. The overcurrent restart mechanism monitors the BLDC bus current in real time to determine if the motor has failed to switch to closed-loop control; if failure occurs, the motor is restarted. This invention can automatically select the timing for switching to closed-loop control based on the BLDC's operating conditions and, through the establishment of high-torque transition and overcurrent restart mechanisms, ensure a smooth transition from open-loop to closed-loop control in the sensorless BLDC converter, enabling successful startup and entry into closed-loop control.

Description

Technical Field

[0001] This invention relates to a method, device, and medium for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC motor, belonging to the field of three-phase brushless DC motor (BLDC) drive technology. Background Technology

[0002] Sensorless brushless DC motors (BLDC) have advantages such as low cost, small size, and high reliability, and are widely used in the field of industrial control.

[0003] In the process of driving a sensorless BLDC, switching from open-loop to closed-loop is a crucial step in the three-step startup process and is key to the successful startup of the sensorless BLDC. Traditionally, the open-loop to closed-loop switching process typically involves running in open-loop mode for a fixed duration or switching to closed-loop mode after detecting a back EMF signal. However, in practical applications, sensorless BLDCs usually operate under varying load environments, and the traditional open-loop to closed-loop switching method may lead to startup failure under different load conditions.

[0004] Improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] Objective: To overcome the shortcomings of existing technologies, this invention provides a method, device, and medium for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC. It can automatically select the timing for switching to closed-loop based on the BLDC's operating conditions, and ensure a smooth transition from open-loop to closed-loop state and successful startup of the sensorless BLDC by establishing a high-torque transition and overcurrent restart mechanism.

[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0007] Firstly, a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit includes the following steps:

[0008] Step 1: In open-loop condition, detect the zero-crossing state of the back electromotive force of the UVW three phases and calculate the zero-crossing state value. After obtaining the zero-crossing state value, obtain the next position information of the rotor movement by looking up the relationship table.

[0009] Step 2: Compare the next position information of the rotor movement with the rotor position given by the commutation logic. If the next position information of the rotor movement is consistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is incremented by 1. If the next position information of the rotor movement is inconsistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is decremented by 1.

[0010] Step 3: Repeat steps 1 and 2. When the number of times the zero-crossing point is correctly detected is greater than the threshold for switching from open-loop to closed-loop, switch the open-loop state to the closed-loop state.

[0011] Step 4: In closed-loop state, the commutation count is incremented by 1 for each motor commutation. When the updated commutation count is less than the delay judgment threshold, a long delay is used to perform motor commutation when the zero-crossing state value is detected. When the updated commutation count is greater than or equal to the delay judgment threshold, a short delay is used to perform motor commutation when the zero-crossing state value is detected.

[0012] Step 5: In closed-loop mode, monitor the bus current in real time. When the bus current is less than or equal to the bus current overcurrent threshold, the switch to closed-loop mode is successful; when the bus current is greater than the bus current overcurrent threshold, the switch to closed-loop mode is unsuccessful, and the BLDC is restarted.

[0013] As a preferred embodiment, the zero-crossing state value S o The calculation formula is as follows:

[0014] S o =S u ×4+S v ×2+S w

[0015] Wherein: S o The zero-crossing state value; S u This represents the zero-crossing state of the back electromotive force of phase U, with a value of 1 when phase U crosses zero and 0 otherwise; S v This represents the zero-crossing state of the back electromotive force of phase V, with a value of 1 when phase V crosses zero and 0 otherwise; S w This represents the zero-crossing state of the back electromotive force of phase W. Its value is 1 when phase W crosses zero and 0 otherwise.

[0016] As a preferred embodiment, the relationship table is the zero-crossing state value S. o The table showing the correspondence between the rotor positions and the next steps is as follows:

[0017] Table 1 Relationship Table

[0018] Zero-crossing state value 0 1 2 3 4 5 6 7 8 The next position of the rotor during forward rotation -- 4 1 5 2 6 3 -- -- The next position of the rotor during reverse rotation -- 1 2 3 4 5 6 -- -- .

[0019] As a preferred embodiment, the threshold for the open-loop to closed-loop condition is determined based on the BLDC characteristics.

[0020] As a preferred embodiment, the long delay time T d1 The calculation formula is as follows:

[0021] T d1 =T l ×Km

[0022] Among them, T l K is the time interval between two commutations. m This is the torque delay factor.

[0023] As the preferred option, K m The value range is 0.4≤Km≤0.7.

[0024] As a preferred embodiment, the short delay time T d2 The calculation formula is as follows:

[0025] T d2 =T l ×K s

[0026] Among them, T l K is the time interval between two commutations. s This is the normal torque delay factor.

[0027] As a preferred option, the value of Ks is in the range of 0.2≤Ks≤0.5.

[0028] In a second aspect, a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit as described in any of the first aspects.

[0029] Thirdly, a computer device comprising:

[0030] Memory is used to store instructions.

[0031] A processor for executing the instructions, causing the computer device to perform operations of a method for improving the success rate of switching from open-loop to closed-loop control in a sensorless BLDC circuit as described in any of the first aspects.

[0032] Beneficial Effects: This invention provides a method, device, and medium for improving the success rate of switching from open-loop to closed-loop control in a sensorless BLDC converter, including open-loop to closed-loop condition judgment, high-torque transition, and overcurrent restart mechanism. The open-loop to closed-loop condition judgment determines whether the current state meets the basic conditions for switching the BLDC from open-loop to closed-loop control by detecting the zero-crossing point of the back EMF. The high-torque transition appropriately extends the commutation time after the zero-crossing point during the initial period of switching the BLDC from open-loop to closed-loop control, providing high torque to the BLDC and preventing failure to switch from open-loop to closed-loop control under heavy load conditions. The overcurrent restart mechanism monitors the BLDC bus current in real time to determine whether the motor has failed to switch to closed-loop control; if a switching failure occurs, the motor is restarted.

[0033] This invention can automatically select the timing for entering the closed loop based on the BLDC's operating status, and ensures a smooth transition from the open-loop state to the closed-loop state by establishing a high-torque transition and overcurrent restart mechanism, thus successfully starting the BLDC into the closed-loop state. Attached Figure Description

[0034] Figure 1 This is a schematic diagram illustrating the working process of a method to improve the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit.

[0035] Figure 2 This is a graph showing the relationship between the three back electromotive force signals and the zero-crossing signal.

[0036] Figure 3 This is a schematic diagram of the rotor position. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0038] The present invention will be further described below with reference to specific embodiments.

[0039] Example 1:

[0040] like Figure 1 As shown in the figure, this embodiment introduces a method to improve the success rate of switching from open-loop to closed-loop in sensorless BLDC. The specific steps are as follows:

[0041] Step 1: In open-loop condition, detect the zero-crossing state of the back electromotive force of the UVW three phases and calculate the zero-crossing state value. After obtaining the zero-crossing state value, obtain the next position information of the rotor movement by looking up the relationship table.

[0042] Step 2: Compare the next position information of the rotor movement with the rotor position given by the commutation logic. If the next position information of the rotor movement is consistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is incremented by 1. If the next position information of the rotor movement is inconsistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is decremented by 1.

[0043] Step 3: Repeat steps 1 and 2. When the number of times the zero-crossing point is correctly detected is greater than the threshold for switching from open-loop to closed-loop, switch the open-loop state to the closed-loop state.

[0044] Step 4: In closed-loop state, the commutation count is incremented by 1 for each motor commutation. When the updated commutation count is less than the delay judgment threshold, a long delay is used to perform motor commutation when the zero-crossing state value is detected. When the updated commutation count is greater than or equal to the delay judgment threshold, a short delay is used to perform motor commutation when the zero-crossing state value is detected.

[0045] Step 5: In closed-loop mode, monitor the bus current in real time. When the bus current is less than or equal to the bus current overcurrent threshold, the switch to closed-loop mode is successful; when the bus current is greater than the bus current overcurrent threshold, the switch to closed-loop mode is unsuccessful, and the BLDC is restarted.

[0046] like Figure 2 As shown, further, the zero-crossing state value S o The calculation formula is as follows:

[0047] S o =S u ×4+S v ×2+S w

[0048] Wherein: S o The zero-crossing state value; S u This represents the zero-crossing state of the back electromotive force of phase U, with a value of 1 when phase U crosses zero and 0 otherwise; S v This represents the zero-crossing state of the back electromotive force of phase V, with a value of 1 when phase V crosses zero and 0 otherwise; S w This represents the zero-crossing state of the back electromotive force of phase W. Its value is 1 when phase W crosses zero and 0 otherwise.

[0049] Furthermore, the relational table represents the zero-crossing state value S. o The table showing the correspondence between the rotor positions and the next steps is as follows:

[0050] Table 1 Relationship Table

[0051] Zero-crossing state value 0 1 2 3 4 5 6 7 8 The next position of the rotor during forward rotation -- 4 1 5 2 6 3 -- -- The next position of the rotor during reverse rotation -- 1 2 3 4 5 6 -- --

[0052] like Figure 3As shown, based on the six states under BLDC six-step control, the rotor is divided into six equal parts. Hall sensors HA, HB, and HC are assumed to be installed in phases A, B, and C. When the rotor's N pole points, the Hall sensor in that direction feeds a high level, i.e., the digital "1". When the rotor's S pole points, the Hall sensor in that direction feeds a low level, i.e., the digital "0". As shown in the example, the binary number 010 (ABC arrangement) is obtained, which, when converted to decimal, represents the current rotor position 2. Similarly, the possible states of Hall sensors HA, HB, and HC are 001, 010, 011, 100, 101, and 110, respectively, corresponding to current rotor positions 1, 2, 3, 4, 5, and 6.

[0053] Furthermore, the threshold for the open-loop to closed-loop condition is determined based on the BLDC characteristics.

[0054] Furthermore, the long delay time T d1 The calculation formula is as follows:

[0055] T d1 =T l ×K m

[0056] Among them, T l K is the time interval between two commutations. m This is the torque delay factor, which is generally taken as 0.4≤Km≤0.7.

[0057] Furthermore, the short delay time T d2 The calculation formula is as follows:

[0058] T d2 =T l ×K s

[0059] Among them, T l K is the time interval between two commutations. s This is the normal torque delay coefficient, which is generally taken as 0.2≤Ks≤0.5.

[0060] Example 2:

[0061] This embodiment describes a computer-readable storage medium storing a computer program that, when executed by a processor, implements a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit, as described in any of Embodiment 1.

[0062] Example 3:

[0063] This embodiment describes a computer device, including:

[0064] Memory is used to store instructions.

[0065] A processor is configured to execute the instructions, causing the computer device to perform operations as described in any of Embodiment 1 of a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit.

[0066] Example 4:

[0067] This embodiment describes the application process of a method to improve the success rate of switching from open-loop to closed-loop in sensorless BLDC. The specific steps are as follows:

[0068] Step 1: The hardware zero-crossing detection circuit is connected to the microcontroller. The microcontroller acquires the three back electromotive force levels and calculates the zero-crossing state value.

[0069] Step 2: Based on the zero-crossing state value, look up the relationship table to obtain the next rotor position for rotor motion.

[0070] Step 3: Determine whether the next rotor position obtained from the zero-crossing state value is the same as the rotor position obtained during the commutation process. (Because the motor commutation logic is fixed, the next commutation logic and rotor position can be known during this commutation.) If they are the same, it means that the rotor position obtained by zero-crossing detection is accurate, and it is considered that the zero-crossing point has been correctly detected at this time.

[0071] Step 4: Each time a zero-crossing is correctly detected, the counter increments by 1. When the counter reaches the threshold, the closed loop can be switched. For example, if the threshold is set to 100, the closed loop switching condition is met after 100 correct zero-crossings are detected.

[0072] Step 5: After entering the closed loop, initially operate at high torque. High torque operation refers to appropriately extending the commutation delay time after detecting the zero-crossing point. For example, during normal motor operation, the commutation cycle is 100µs; after detecting the zero-crossing point, the commutation should be delayed by 50µs. During the first 100 commutations after entering the closed loop, to ensure smooth motor switching, increase the motor output torque by increasing the delay time to 80µs. After the first 100 commutations are completed, switch back to the normal 50µs delayed commutation.

[0073] Step 6: After entering the closed loop, current detection is activated to monitor the bus current status in real time. For example, under normal circumstances, the bus current is less than 1A. If the detected bus current is continuously greater than 1A, the motor is not running normally, and the closed loop switching is determined to have failed. At this time, the motor needs to be restarted until the motor successfully enters the closed loop.

[0074] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0076] 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.

[0077] 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.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the success rate of switching from open-loop to closed-loop control in a sensorless BLDC circuit, characterized in that: Includes the following steps: Step 1: In open-loop condition, detect the zero-crossing state of the back electromotive force of the three phases UVW and calculate the zero-crossing state value. After obtaining the zero-crossing state value, obtain the next position information of the rotor movement by looking up the relationship table. Step 2: Compare the next position information of the rotor movement with the rotor position given by the commutation logic. If the next position information of the rotor movement is consistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is incremented by 1. If the next position information of the rotor movement is inconsistent with the rotor position given by the commutation logic, the number of correct zero-crossing detections is decremented by 1. Step 3: Repeat steps 1 and 2. When the number of times the zero-crossing point is correctly detected is greater than the threshold for switching from open-loop to closed-loop, switch the open-loop state to the closed-loop state. Step 4: In closed-loop state, the commutation count is incremented by 1 for each motor commutation. When the updated commutation count is less than the delay judgment threshold, a long delay is used to perform motor commutation when the zero-crossing state value is detected. When the updated commutation count is greater than or equal to the delay judgment threshold, a short delay is used to perform motor commutation when the zero-crossing state value is detected.

2. The method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 1, characterized in that: Also includes: Step 5: In the closed-loop state, the bus current is monitored in real time. When the bus current is less than or equal to the bus current overcurrent threshold, the switch to the closed-loop state is successful; when the bus current is greater than the bus current overcurrent threshold, the switch to the closed-loop state is unsuccessful, and the BLDC is restarted.

3. A method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 1 or 2, characterized in that: The zero-crossing state value S o The calculation formula is as follows: S o =S u ×4+S v ×2+S w Wherein: S o The zero-crossing state value; S u This represents the zero-crossing state of the back electromotive force of phase U, with a value of 1 when phase U crosses zero and 0 otherwise; S v This represents the zero-crossing state of the back electromotive force of phase V, with a value of 1 when phase V crosses zero and 0 otherwise; S w This represents the zero-crossing state of the back electromotive force of phase W. Its value is 1 when phase W crosses zero and 0 otherwise.

4. A method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 1 or 2, characterized in that: The relational table represents the zero-crossing state value S. o The table showing the correspondence between the rotor positions and the next steps is as follows: Table 1 Relationship Table Zero-crossing state value 0 1 2 3 4 5 6 7 8 The next position of the rotor during forward rotation -- 4 1 5 2 6 3 -- -- The next position of the rotor during reverse rotation -- 1 2 3 4 5 6 -- -- 。 5. A method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 1 or 2, characterized in that: The long delay time T d1 The calculation formula is as follows: T d1 =T l ×K m Among them, T l K is the time interval between two commutations. m This is the torque delay factor.

6. The method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 5, characterized in that: The K m The value range is 0.4≤Km≤0.

7.

7. A method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 1 or 2, characterized in that: The short delay time T d2 The calculation formula is as follows: T d2 =T l ×K s Among them, T l K is the time interval between two commutations. s This is the normal torque delay factor.

8. The method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit according to claim 7, characterized in that: The value of Ks is in the range of 0.2 ≤ Ks ≤ 0.

5.

9. A computer-readable storage medium, characterized in that: It stores a computer program that, when executed by a processor, implements a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit as described in any one of claims 1-8.

10. A computer device, characterized in that... include: Memory, used to store instructions; A processor for executing the instructions, causing the computer device to perform the operation of a method for improving the success rate of switching from open-loop to closed-loop in a sensorless BLDC circuit as described in any one of claims 1-8.

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