A brushless motor driving circuit and a control method thereof

Abstract

The application discloses a brushless motor driving circuit and a control method thereof, which comprises: an embedded microprocessor coupled with a motor, which is used for setting the running speed and protection parameters of the motor before starting the motor; a rotor position sensor coupled with the motor, which is used for determining the rotor zero position of the motor; and an output position sensor coupled with an electronic clutch module, which is used for determining the output zero position of the output end of the electronic clutch module, wherein: the embedded microprocessor is configured to enable the rotor of the motor and the output end of the electronic clutch module to be automatically zero-position aligned when the motor starts based on the rotor zero position and the output zero position. The application compares the electronic rotor and the clutch output position through the rotor position sensor and the output position sensor, so that the output is not manually returned to zero after the system is started and locked, and the rotor zero position and the output zero position are automatically aligned.

Description

Technical Field

[0001] This invention relates to the field of brushless motor technology, specifically to a brushless motor drive circuit and its control method. Background Technology

[0002] Brushless DC motors (BLDC) overcome the shortcomings of brushed DC motors, which use mechanical commutators, by employing electronic commutators. Their higher operating efficiency, smaller size, and larger torque have led to their widespread use in the industry, including bionic robots, medical devices, home appliances, new energy vehicles, and industrial production. With the development of permanent magnet technology and continuous advancements in motor manufacturing processes in recent years, the weight and size of brushless DC motors have been effectively reduced, greatly expanding their applications in bionic robots, particularly as articulated motors and wheel motors.

[0003] Among them, the FOC control algorithm can achieve high-precision speed, angle and torque control of brushless DC motors. With the continuous development of microelectronics technology, high-performance microcontroller technology and the continuous reduction of microcontroller size in recent years, the FOC control algorithm has achieved smooth operation on microcontrollers and realized high-performance control of brushless DC motors.

[0004] Traditional FOC brushless motor drive circuits use expensive driver chips and lack integrated design, resulting in large size and inconvenient application. Furthermore, under high load operation, the lack of effective heat dissipation leads to poor heat dissipation and overheating, affecting the lifespan and normal operation of the brushless motor drive circuit. Additionally, after lock-up protection, manual zeroing of the output and alignment of the rotor and output zero positions are required. Therefore, this application aims to provide a brushless motor drive circuit and its control method that achieves automatic alignment of the rotor and output zero positions without manual zeroing after system startup and lock-up protection. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a brushless motor drive circuit and its control method.

[0006] The objective of this invention is achieved through the following technical solution: a brushless motor drive circuit, comprising: an embedded microprocessor coupled to a motor, used to set the motor's operating speed and protection parameters before the motor starts; a rotor position sensor coupled to the motor, used to determine the rotor zero position of the motor; and an output position sensor coupled to an electronic clutch module, used to determine the output zero position of the output terminal of the electronic clutch module, wherein: the embedded microprocessor is configured to automatically align the rotor of the motor with the output terminal of the electronic clutch module at the zero position based on the rotor zero position and the output zero position when the motor starts.

[0007] Preferably, the system includes a current detection circuit for acquiring real-time current data of the motor; an output position sensor for acquiring speed and acceleration data at the output of the electronic clutch module; and a temperature detection circuit for acquiring circuit temperature data. The embedded microprocessor determines whether the motor or the electronic clutch module is faulty based on the detection data, including the real-time current data, the speed and acceleration data at the output of the electronic clutch module, and the circuit temperature data. In the event of a fault in the motor or the electronic clutch module, a fault code is generated, and the fault is processed.

[0008] Preferably, the protection parameters are defined by the detection data, wherein determining whether the motor or the electronic clutch module has a fault includes the following steps: generating a first fault code when the real-time current is higher than a set threshold; generating a second fault code when the circuit temperature is higher than a set threshold; generating a third fault code when the speed of the motor rotor is inconsistent with the speed at the output of the electronic clutch module; and generating a fourth fault code when the acceleration at the output of the electronic clutch module is higher than a set threshold.

[0009] Preferably, a locking module is included, the signal input terminal of which is connected to the output terminal of the embedded microprocessor, and the torque input terminal of which is connected to the torque output terminal of the electronic clutch module. In the event that the motor malfunctions, the torque output terminal of the electronic clutch module can be separated from the motor rotor, and the locking module can lock the torque output terminal of the electronic clutch module.

[0010] Preferably, the device further includes a gate driving module, wherein the output terminal of the embedded microprocessor is connected to the input terminal of the gate driving module, the output terminal of the gate driving module is connected to the input terminal of the three-phase inverter circuit, and the output terminal of the three-phase inverter circuit is connected to the motor. In the event that the motor is determined to be faulty, the embedded microprocessor can write a high level to the SD pin of the gate driving module.

[0011] Preferably, the output terminal of the rotor position sensor is connected to the input terminal of the embedded microprocessor, the signal input terminal of the electronic clutch module is connected to the output terminal of the embedded microprocessor, the torque input terminal of the electronic clutch module is threaded to the torque output terminal of the motor, and the output terminal of the output position sensor is connected to the input terminal of the embedded microprocessor.

[0012] Preferably, the gate drive module is capable of receiving three PWM pulse width modulation signals and one high / low level signal from the embedded microprocessor.

[0013] Preferably, the SD pin in the gate drive module can simultaneously turn off the high and low MOS transistors in the three half-H bridges of the three-phase inverter circuit.

[0014] Preferably, the electronic clutch module has a signal input terminal, a torque input terminal, and a torque output terminal, wherein the signal input terminal receives a level signal sent by the embedded microprocessor to engage or disengage the torque input terminal and the torque output terminal.

[0015] This application also provides a control method for a brushless motor drive circuit, characterized by the following steps: S100, before starting the motor, setting the motor's running speed and other protection parameters; S200, locking the locking module, releasing the electronic clutch module, and then detecting the torque output terminal of the motor rotor and the electronic clutch module to achieve zero alignment; S300, determining detection data including the motor's real-time current, the motor rotor's speed and acceleration, the speed and acceleration of the electronic clutch module's output terminal, and the circuit temperature; S400, judging whether the motor or the electronic clutch module has malfunctioned based on the detection data; S500, if a malfunction is found, returning a fault code and performing fault handling.

[0016] This invention has the following advantages: By comparing the positions of the electronic rotor and the clutch output using a rotor position sensor and an output position sensor, this invention achieves automatic alignment of the rotor zero position and the output zero position without requiring manual zeroing of the output after system startup and locking protection. Simultaneously, by calculating the speed and acceleration of the motor rotor and clutch output, as well as the temperature and current of the detection circuit, a control method is used to diagnose faults and protect the motor and brushless drive circuit. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the modular structure of the brushless motor drive circuit of the present invention;

[0018] Figure 2 This is a schematic flowchart of the brushless motor drive circuit control method of the present invention.

[0019] In the diagram, 1-embedded microprocessor, 2-motor, 3-rotor position sensor, 4-electronic clutch module, 5-current detection circuit, 6-locking module, 7-gate drive module, 8-three-phase inverter circuit, 9-output position sensor, 10-temperature detection circuit, 11-fan controller, 12-cooling fan, 13-communication module. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the following description:

[0021] like Figure 1 As shown, this application provides a brushless motor drive circuit, including a working module comprising an embedded microprocessor 1, a gate drive module 7, a three-phase inverter circuit 8, a rotor position sensor 3, a motor 2, an electronic clutch module 4, a current detection circuit 5, a locking module 6, an output position sensor 9, a temperature detection circuit 10, a fan controller 11, a cooling fan 12, and a communication module 13. The current detection circuit 5 acquires real-time current data of the motor; the output position sensor 9 acquires speed and acceleration data at the output of the electronic clutch module; and the temperature detection circuit 10 acquires circuit temperature data. The temperature detection circuit 10 is communicatively coupled to the embedded microprocessor 1 to transmit its acquired real-time current data to the embedded microprocessor 1. The embedded microprocessor 1 is connected to the cooling fan via the fan controller 11. When the embedded microprocessor determines that the motor is overheating, it sends a control command to the cooling fan through the fan controller, thereby performing operations such as turning on the cooling fan or increasing its speed. The communication module is communicatively coupled to the embedded microprocessor 1, thus forming an interface for communication with external devices. The output of the embedded microprocessor is connected to the input of the gate drive module, the output of the gate drive module is connected to the input of the three-phase inverter circuit, and the output of the three-phase inverter circuit is connected to the motor. The output of the rotor position sensor is connected to the input of the embedded microprocessor. The signal input of the electronic clutch module is connected to the output of the embedded microprocessor, and the torque input of the electronic clutch module is screwed to the torque output of the motor. The signal input of the locking module is connected to the output of the embedded microprocessor, and the torque input of the locking module is connected to the torque output of the electronic clutch module. The output of the output position sensor is connected to the input of the embedded microprocessor. The input of the communication module is connected to the output of the embedded microprocessor. This invention patent, through the comparison between the electronic rotor and clutch output positions by the rotor position sensor and the output position sensor, achieves automatic alignment of the rotor zero position and the output zero position without manual zeroing after system startup and locking protection. Simultaneously, it can detect the circuit temperature and the motor's operating status, thus protecting the motor and brushless drive circuit.

[0022] Preferably, the gate drive module receives three PWM pulse width modulation signals and one high / low level signal from the embedded microprocessor, and the gate drive chip used has an SD pin. Specifically, the gate drive module only receives three PWM signals and one high / low level signal, reducing the I / O port occupation of the embedded microprocessor and facilitating the connection of the embedded microprocessor to other modules. The high / low level signal is used for the SD function of the gate drive module to simultaneously turn off the high and low MOSFETs in the three half-H bridges of the three-phase inverter circuit, effectively protecting the motor drive circuit.

[0023] Preferably, the electronic clutch module has a signal input terminal, a torque input terminal, and a torque output terminal. The signal input terminal receives a level signal sent by the embedded microprocessor, connecting and disconnecting the torque input terminal and the torque output terminal. Specifically, under the control of the embedded microprocessor, the electronic clutch module can separate the motor rotor from the output phase, facilitating the drive circuit to disconnect the motor rotor from the external load connected to the clutch output terminal when starting the motor for zero-position detection, and then reconnect them after zero-position alignment. Simultaneously, in the event of a collision with the external load, it can disconnect the motor rotor, protecting the motor and the drive circuit.

[0024] Preferably, the motor is a permanent magnet brushless DC motor (BLDC), with a radially magnetized permanent magnet installed on one side of the motor rotor. Specifically, permanent magnet brushless DC motors have the advantages of small size and light weight, enabling them to be used in more applications. Furthermore, the radially magnetized permanent magnet installed on one side of the motor causes the radial magnetic field generated by the magnet to rotate along with the motor rotor, thereby realizing the conversion of position signals into magnetic signals. The radially magnetized permanent magnet is small in size and easy to install.

[0025] Preferably, the rotor position sensor is a magnetic induction position sensor that detects the position of the electronic rotor and is not directly connected to the rotor. Specifically, the rotor position sensor detects the position of the motor rotor by detecting the magnetic field generated by a magnet mounted under the motor rotor. Magnetic encoders are small in size, highly accurate, and easy to integrate onto the PCB board of the motor drive. Since it does not directly contact the rotor, there is no friction, and it is not prone to damage after long-term operation. Furthermore, the speed signal can be obtained by differentiating the position difference detected by the magnetic induction position sensor, eliminating the need for other sensors. Multiple data points are obtained from a single sensor, reducing the number of sensors and lowering costs.

[0026] Example 2

[0027] like Figure 2 As shown, this application also provides a brushless motor drive circuit control method, including the following steps:

[0028] Step 100: Before starting the motor, set the motor running speed and other protection parameters;

[0029] Step 200: Lock the locking module, release the clutch, and align the zero position;

[0030] Step 300: Determine the detection data, including the real-time current of the motor, the speed and acceleration of the motor rotor, the speed and acceleration of the output terminal of the electronic clutch module, and the circuit temperature.

[0031] Step 400: Determine whether a fault has occurred based on the test data;

[0032] Step 500: If a fault is detected, return the fault code and proceed with fault handling. If there is no fault, control the motor to operate normally (FOC).

[0033] In this embodiment, by locking the clutch output end during motor startup and disengaging the motor from the output end, the output position does not need to be manually zeroed each time the motor starts. The drive circuit and control method automatically align the rotor with the zero position of the clutch output end, simplifying the startup steps and shortening the startup time. During operation, speed and acceleration are obtained by performing first and second derivatives on the position, enabling better control of motor operation and reducing overshoot. Simultaneously, by judging acceleration and detecting the temperature and current of the circuit, the control method diagnoses faults and protects the motor and brushless drive circuit from overload, overheating, collisions, clutch slippage, and other conditions, protecting the drive circuit hardware and extending the system's service life.

[0034] Preferably, in this embodiment, step 400 includes the following steps:

[0035] Step 410: Determine whether the real-time current is higher than the threshold value, which is the current threshold value set in step 100. If it is, it is determined to be an overload, and the fault code is assigned the value 0x01.

[0036] Step 420: Determine whether the real-time temperature is higher than the threshold value set in step 100. If it is, it is determined to be an overload, and the fault code is assigned the value 0x02.

[0037] Step 430: Determine whether the speed of the motor rotor is consistent with the speed of the clutch torque output end. If not, determine that the electronic clutch module is slipping and assign the fault code 0x03.

[0038] Step 430: Determine whether the acceleration of the torque output of the electronic clutch module is higher than the threshold value, which is the acceleration threshold value set in step 100. If it is, it is determined that a collision has occurred, and the fault code value 0x04 is assigned.

[0039] Specifically, when the real-time current is below the threshold current, it indicates that the motor is operating within the range that the drive circuit can withstand, and the system will continue to operate without reliability issues. When the real-time current is above the threshold current, the excessive current will generate a large amount of heat in the drive circuit, which may damage the drive circuit and the motor. Under normal operation, the current should be below the threshold. When it exceeds the threshold, it is highly likely that a stalled rotor, overload, or other fault conditions have occurred. These conditions are not included in the design conditions. To protect the circuit and the motor, they are identified as faults and marked with fault code 0x01 indicating that the current is above the threshold.

[0040] Since current flows through a conductor, according to the formula:

[0041] P = I 2 R

[0042] When the drive circuit operates under high load, it generates a significant amount of heat. When the temperature is below the threshold temperature, it indicates that the real-time temperature is within the cooling capacity of the drive system's fan, allowing the drive circuit to continue operating and maintain good heat dissipation performance. However, if the real-time temperature exceeds the threshold temperature, continued operation of the drive system could damage the drive system and motor. Therefore, a fault code of 0x02 is used to indicate that the temperature is above the threshold.

[0043] When the motor is running, the positions of the motor rotor and the clutch output terminal are detected, and the first and second derivatives are performed to obtain the position, velocity, and acceleration of the motor rotor and the clutch output terminal respectively. When the clutch is tightly engaged, the velocity and acceleration between the motor rotor and the output terminal of the electronic clutch module should be consistent. At this time, there is no relative slippage within the electronic clutch module, and the system is operating normally. When the velocity and acceleration are inconsistent, it indicates that relative slippage has occurred within the electronic clutch module, meaning that the system's precise control of the motor rotor is not well reflected at the output terminal. This indicates a fault in the electronic clutch module. Prolonged clutch slippage will cause the electronic clutch module to overheat, which can lead to burnout in severe cases. To protect the drive circuit, this will be identified as a clutch module fault and marked with fault code 0x03.

[0044] When the motor is running normally, the motor acceleration is below the threshold. When the motor acceleration is above the threshold, it indicates that the motor speed has changed abruptly. At this time, there may be a collision or other issues at the motor output. Therefore, the fault code is marked as 0x04.

[0045] By using different modules within the drive circuit to monitor and assess its operation in real time, and by identifying faults in different parts of the circuit, the system effectively improves fault detection and protection capabilities. This allows for early detection of system problems, minimizing the risk of entire circuit failure due to a single component issue. Furthermore, the labeling of different faults pinpoints the problem to the specific module, facilitating manual analysis and repair.

[0046] Preferably, in this embodiment, step 500 includes the following steps:

[0047] Step 510: If a fault occurs, write a high level to the SD pin of the gate drive module. The locking module locks the clutch torque output terminal, and the clutch disengages. A fault code is sent via the communication module, and the loop program exits.

[0048] Step 520: If there is no fault, control the motor to run normally (FOC) and return to step 300 to repeat the cycle.

[0049] Specifically, when the control method does not detect a fault, the drive continues to run the FOC algorithm, driving the motor to work. However, when the control method determines that a fault has occurred in the drive circuit, it writes a high level to the SD pin of the gate drive module. At this time, the gate drive module will simultaneously turn off the six NMOS transistors on the three and a half H-bridges inside the three-phase drive circuit, thereby cutting off the power to the motor. This completely disconnects the power supply to the motor, stops its operation, cuts off its continued heat generation, and prevents it from continuing to work after the locking device is engaged, causing a stall and damaging the circuit, thus better protecting the circuit.

[0050] Preferably, in step 200, the locking module is locked first, the clutch is released, and then the motor rotor and the clutch torque output end are checked to find the zero position.

[0051] Specifically, when starting the motor, the clutch output end is locked, separating the motor from the output end. This ensures that the clutch output end remains fixed each time the motor starts due to the locking device. Thanks to the clutch module, the motor's operation does not affect the output end. Furthermore, because the motor rotor and clutch output end can be separated, the rotor automatically aligns with the zero position of the clutch output end, eliminating the need for manual zeroing of the output position, simplifying the starting process and reducing start-up time.

[0052] Preferably, in step 300, the position change within a small time interval is differentiated once and twice to determine the speed and acceleration of the motor rotor and the torque output terminal of the electronic clutch module, respectively.

[0053] Specifically, by measuring the angular change of the motor rotor and the output of the electronic clutch module within a tiny time interval, the embedded microcontroller performs first and second differentiation to obtain their respective speeds and accelerations. The calculation of speed and acceleration can better help control the motor, enhance its dynamic response capability, and reduce overshoot during operation.

[0054] Preferably, in step 500, if a fault is detected, the locking module locks the torque output terminal of the electronic clutch module and releases the clutch. Specifically, when a fault is detected, the electronic clutch module separates the motor rotor from the torque output terminal of the electronic clutch module to prevent the load connected to the torque output terminal of the electronic clutch module from damaging the motor, thereby protecting the motor. At the same time, the locking module locks the torque output terminal of the electronic clutch module, stopping the connected load as quickly as possible and preventing it from continuing to move under inertia.

[0055] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brushless motor drive circuit, characterized in that, Includes: an embedded microprocessor (1) coupled to the motor (2) for setting the running speed and protection parameters of the motor (2) before the motor (2) is started; The rotor position sensor (3) coupled to the motor (2) has a radially magnetized permanent magnet on one side of the rotor of the motor (2). The rotor position sensor (3) is a magnetic induction sensor used to determine the zero position of the rotor of the motor (2). The electronic clutch module (4) has a signal input terminal, a torque input terminal and a torque output terminal. The signal input terminal receives a level signal sent by the embedded microprocessor (1) to engage or disengage the torque input terminal and the torque output terminal. The output position sensor (9) coupled to the electronic clutch module (4) is used to determine the zero position of the torque output terminal of the electronic clutch module (4) and to acquire the speed and acceleration data of the torque output terminal of the electronic clutch module (4). The locking module (6) has its signal input terminal connected to the output terminal of the embedded microprocessor (1), and its torque input terminal is connected to the torque output terminal of the electronic clutch module (4). Wherein: the embedded microprocessor (1) is configured to, based on the rotor zero position and the output zero position, when the motor (2) starts, first control the locking module (6) to lock the torque output end of the electronic clutch module (4), and then control the electronic clutch module (4) to release the connection between the torque input end and the torque output end of the electronic clutch module (4), so that the rotor of the motor (2) and the external load of the torque output end of the electronic clutch module (4) are disconnected, automatically align the zero position, and after alignment, control the electronic clutch module (4) to engage its torque input end and torque output end.

2. The brushless motor drive circuit according to claim 1, characterized in that, include: The current detection circuit (5) is used to acquire the real-time current data of the motor; Temperature detection circuit (10) is used to acquire circuit temperature data; The embedded microprocessor (1) determines whether the motor (2) or the electronic clutch module (4) has a fault based on the detection data including the real-time current data, the speed and acceleration data of the torque output terminal of the electronic clutch module (4), and the circuit temperature data. In the event of a fault in the motor (2) or the electronic clutch module (4), a fault code is generated and the fault is processed.

3. The brushless motor drive circuit according to claim 2, characterized in that, The protection parameters are defined by the detection data, wherein determining whether the motor (2) or the electronic clutch module (4) is faulty includes the following steps: If the real-time current exceeds a set threshold, a first fault code is generated; If the circuit temperature exceeds a set threshold, a second fault code is generated. A third fault code is generated when the speed of the motor rotor is inconsistent with the speed of the torque output terminal of the electronic clutch module (4); If the acceleration at the torque output end of the electronic clutch module (4) exceeds the set threshold, a fourth fault code is generated.

4. The brushless motor drive circuit according to claim 2, characterized in that, In the event that the motor is found to be malfunctioning, the torque output terminal of the electronic clutch module (4) can be separated from the rotor of the motor (2), and the locking module (6) can lock the torque output terminal of the electronic clutch module (4).

5. The brushless motor drive circuit according to claim 4, characterized in that, It also includes a gate drive module (7), the output of the embedded microprocessor (1) is connected to the input of the gate drive module (7), the output of the gate drive module (7) is connected to the input of the three-phase inverter circuit (8), and the output of the three-phase inverter circuit (8) is connected to the motor (2). In the event that the motor (2) is determined to be faulty, the embedded microprocessor (1) can write a high level to the SD pin of the gate drive module (7).

6. The brushless motor drive circuit according to claim 5, characterized in that, The output of the rotor position sensor (3) is connected to the input of the embedded microprocessor (1), the signal input of the electronic clutch module (4) is connected to the output of the embedded microprocessor (1), the torque input of the electronic clutch module (4) is threaded to the torque output of the motor (2), and the output of the output position sensor is connected to the input of the embedded microprocessor (1).

7. The brushless motor drive circuit according to claim 6, characterized in that, The gate drive module (7) can receive three PWM pulse width modulation signals and one high and low level signal from the embedded microprocessor (1).

8. The brushless motor drive circuit according to claim 6, characterized in that, The SD pin in the gate drive module (7) can simultaneously turn off the high and low MOS transistors in the three half-H bridges of the three-phase inverter circuit.

9. A control method based on the brushless motor drive circuit according to any one of claims 1-8, characterized in that, Includes the following steps: S100, before starting the motor (2), set the running speed of the motor (2) and other protection parameters; S200, after locking the locking module and releasing the electronic clutch module (4), the torque output end of the motor rotor and the electronic clutch module (4) is detected to achieve zero alignment; S300, determine the detection data including the real-time current of the motor (2), the speed and acceleration of the motor rotor, the speed and acceleration of the torque output terminal of the electronic clutch module (4), and the circuit temperature; S400, determine whether the motor (2) or the electronic clutch module (4) has malfunctioned based on the detection data; If an S500 malfunctions, it will return a fault code, and the fault will be handled accordingly.

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