A closed-loop control and monitoring system based on commutation detection of a brush motor

Abstract

The application discloses a closed-loop control and monitoring system based on commutation detection of a brush motor, and belongs to the technical field of DC brush motor control. The system comprises a power supply system, a communication system, a sampling system, a driving output circuit and a main control unit. The power supply system provides multi-stage voltage stabilization and surge protection. The communication system supports double interfaces and standard protocols. The sampling system collects motor working current and commutation back electromotive force. The driving output circuit drives the motor through an H-bridge and a back electromotive force suppression circuit. The main control unit calculates the rotating speed based on the commutation frequency and performs PID adjustment. The system does not need to be additionally provided with an encoder, reduces hardware cost, solves the installation limitation problem, has the advantages of overload protection, stable communication, accurate control and the like, and is suitable for scenes requiring encoder-free rotating speed control.

Description

Technical Field

[0001] This application relates to the field of DC brushed motor control technology, and in particular to a closed-loop control and monitoring system based on brushed motor commutation detection. Background Technology

[0002] A DC brushed motor mainly consists of a stator, rotor, carbon brushes, and commutator plates. The stator and rotor are electrically connected through the carbon brushes and commutator plates. In practical applications, some scenarios require range-based control of the motor speed. However, due to the uncertainty of the motor load, current technologies typically require the addition of an encoder to the motor to achieve speed detection and closed-loop control.

[0003] However, adding an encoder has the following drawbacks: on the one hand, the addition of an encoder will significantly increase hardware costs; on the other hand, some application scenarios (such as small installation spaces and harsh working conditions) cannot meet the installation conditions of the encoder, making it difficult to achieve the speed control requirements. Utility Model Content

[0004] This invention addresses the problems of high cost and limited installation caused by relying on encoders for motor speed control in existing technologies, and provides a closed-loop control and monitoring system based on brushed motor commutation detection.

[0005] The objective of this utility model is mainly achieved through the following solution: A closed-loop control and monitoring system based on brushed motor commutation detection includes a power supply system, a communication system, a sampling system, a drive output circuit, and a main control unit. The power supply system is electrically connected to the communication system, sampling system, drive output circuit and main control unit respectively, and is used to provide stable power supply to each module; The communication system is electrically connected to the main control unit and is used to transmit external control commands and the real-time operating status of the motor. The sampling system is electrically connected to the main control unit and is used to sample the motor's operating current and the reverse electromotive force at the moment of motor commutation, and transmit the processed sampling signal to the main control unit. The drive output circuit is electrically connected to the power supply system and the main control unit respectively, and is used to drive the motor to perform start-stop and forward / reverse rotation actions. The main control unit is used to receive sampling signals, calculate the commutation frequency based on the back electromotive force, obtain the real-time speed by combining the number of motor commutation segments, and drive the output circuit through PID regulation to achieve closed-loop control of motor speed.

[0006] Preferably, the power supply system includes TVS diodes D4 and D5 connected in parallel, a first voltage regulator circuit with DC-DC voltage regulator chip U2 as the core, a second voltage regulator circuit with voltage regulator chip U3 as the core, and a boost circuit. The TVS diodes D4 and D5 are used to absorb surge voltage; the first voltage regulator circuit regulates the input power supply VCC to 5V; the second voltage regulator circuit regulates the 5V voltage to 3.3V to power the main control unit; and the boost circuit boosts the 5V voltage to 12V to power the drive output circuit.

[0007] Preferably, the communication system includes an RS485 interface, a CAN communication interface, and an interface protection circuit consisting of a resettable fuse, a TVS diode, and a resistor; the communication system supports Modbus-RTU protocol and CAN-Open protocol.

[0008] Preferably, the sampling system includes a current sampling circuit and an electromotive force sampling circuit; The current sampling circuit includes a first filter circuit composed of resistors and capacitors, a rail-to-rail high-precision operational amplifier, and a second filter circuit; the motor operating current is transmitted to the AD acquisition interface of the main control unit after passing through the first filter, the operational amplifier amplification, and the second filter. The electromotive force sampling circuit includes a resistor voltage divider circuit and a capacitor filter circuit, which is used to sample the reverse electromotive force at the moment of motor commutation and transmit it to the main control unit.

[0009] Preferably, the drive output circuit includes an H-bridge drive circuit, a reverse electromotive force suppression circuit, and half-bridge drive chips U5, U8, and U13. The H-bridge drive circuit includes MOSFETs Q5, Q6, Q7, and Q8; the reverse electromotive force suppression circuit includes MOSFET Q2 and power resistors R41, R42, and R43; the half-bridge drive chip receives the PWM signal from the main control unit and drives the H-bridge MOSFETs to turn on and off; the drive output circuit adopts unipolar PWM control.

[0010] Preferably, the main control unit adopts an ARM core processor, which allows users to set the motor action steps through the host computer software; the main control unit is also used to monitor the motor operating current, and when the current reaches the maximum current that the system can withstand, it will activate the protection and output alarm information.

[0011] In summary, compared with the prior art, the present invention has the following beneficial technical effects: (1) The present invention reduces costs, eliminates the need for an encoder, and directly utilizes the inherent back electromotive force of the motor to achieve speed detection, thus saving the hardware and installation costs of the encoder. (2) This utility model has wide applicability and solves the speed control needs in scenarios where encoders cannot be installed, such as narrow spaces and harsh working conditions; (3) This utility model has high stability and multiple protection mechanisms for the power supply system, communication system, drive output circuit and sampling system to avoid circuit damage or signal interference; (4) This utility model has precise control. It adjusts the speed through PID algorithm and combines it with a high-precision sampling circuit to ensure stable control of motor speed. (5) This utility model has strong compatibility, supports RS485 / CAN dual communication interface and Modbus-RTU / CAN-Open protocol, can be adapted to a variety of external devices or host computers, and also supports user-defined control modes. Attached Figure Description

[0012] Figure 1 This is a system block diagram of this utility model; Figure 2 This is the circuit diagram of the power supply system in this utility model; Figure 3 This is a circuit diagram of the drive output circuit in this utility model; Figure 4 This is the circuit diagram of the sampling system in this utility model; Figure 5 This is the circuit diagram of the communication system in this utility model; Figure 6 This is the circuit diagram of the main control unit in this utility model. Detailed Implementation

[0013] The technical solution of this utility model will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings. It should be understood that the implementation of this utility model is not limited to the following embodiments, and any modifications and / or alterations made to this utility model will fall within the protection scope of this utility model.

[0014] like Figure 1 As shown, this utility model discloses a technical solution: a closed-loop control and monitoring system based on brushed motor commutation detection, including a power supply system, a communication system, a sampling system, a drive output circuit, and a main control unit. The power supply system is electrically connected to the communication system, sampling system, drive output circuit, and main control unit respectively, and is used to provide stable power supply to each module; The communication system is electrically connected to the main control unit and is used to transmit external control commands and the real-time operating status of the motor. The sampling system is electrically connected to the main control unit and is used to sample the motor's operating current and the back electromotive force at the moment of motor commutation, and transmit the processed sampling signal to the main control unit. The drive output circuit is electrically connected to the power supply system and the main control unit respectively, and is used to drive the motor to perform start-stop, forward and reverse rotation actions; The main control unit is used to receive sampling signals, calculate the commutation frequency based on the back electromotive force, obtain the real-time speed by combining the number of motor commutation segments, and drive the output circuit through PID regulation to achieve closed-loop control of motor speed.

[0015] like Figure 2 As shown, the power supply system uses a DC power supply, and its structure and operation process are as follows: Surge protection: A high-power surge protection circuit is formed by connecting TVS diodes D4 and D5 in parallel to absorb external surge voltage and protect the system circuit. Multi-stage voltage regulation: The input power supply VCC is first regulated to 5V by a circuit with DC-DC voltage regulator chip U2 as the core; the 5V voltage is processed in two ways: one way is regulated to 3.3V by voltage regulator chip U3 to power the main control unit (ARM processor); the other way is boosted to 12V by a boost circuit to power the bridge arm control of the drive output circuit. This design ensures that each module of the system receives a matched and stable voltage, avoiding voltage fluctuations from affecting the motor control accuracy.

[0016] like Figure 3 As shown, the structure and function of the drive output circuit are as follows: H-bridge drive structure: The core power devices are MOSFETs Q5, Q6, Q7, and Q8, which form an H-bridge circuit; the half-bridge drive chips U5, U8, and U13 are electrically connected to the main control unit and the H-bridge MOSFETs, respectively, and receive the PWM signal output by the main control unit to drive the corresponding MOSFETs to turn on and off, thereby realizing motor start-stop and forward / reverse control. PWM control method: Unipolar PWM signal control is adopted. The voltage across the motor is changed by adjusting the PWM duty cycle, thereby improving the smoothness of motor operation. Reverse EMF suppression: A reverse EMF potential energy absorption network is formed by MOSFET Q2 and power resistors R41, R42, and R43. When the motor stops suddenly or decelerates rapidly, the reverse EMF generated by the inductor coil inside the motor causes a sudden rise in system voltage. After the main control unit detects the voltage abnormality, it controls MOSFET Q2 to conduct, so that the reverse EMF is quickly dissipated through the power resistors. After the voltage returns to normal, MOSFET Q2 is turned off to prevent the reverse EMF from damaging the power supply or circuit.

[0017] like Figure 4 As shown, the sampling system includes a current sampling circuit and an electromotive force sampling circuit. The specific structure and operation process are as follows: Current sampling circuit: The motor operating current first passes through a first-order filter circuit (first filter circuit) composed of resistors and capacitors to filter out high-frequency interference; the filtered current signal is input to a rail-to-rail high-precision operational amplifier, amplified, and then further reduced in noise by a second-order filter circuit; the final processed current signal is transmitted to the AD acquisition interface of the main control unit; the main control unit monitors the current value in real time, and when the current reaches the system's maximum withstand current, it immediately activates the protection mechanism (such as cutting off the drive output) and outputs overload alarm information through the communication system.

[0018] Electromotive force sampling circuit: The reverse electromotive force (voltage spike) generated during motor commutation is reduced in amplitude by a resistor voltage divider circuit and then filtered out by a capacitor filter circuit. The processed electromotive force signal is transmitted to the main control unit. Each voltage spike detected corresponds to one commutation. The main control unit counts the number of spikes per unit time (commutation frequency) and, combined with the inherent number of commutation plates of the motor, calculates the real-time speed of the motor (unit: r / min) using the formula "real-time speed = (commutation frequency × 60) / (number of commutation plates × 2)".

[0019] like Figure 5 As shown, the structure and functional implementation of the communication system are as follows: Interface type: Supports RS485 communication interface and CAN communication interface. The two interfaces are independent of each other and can be selected according to actual needs. Interface protection: Self-resetting fuses, TVS diodes, and current-limiting resistors are integrated at the communication interface to prevent overcurrent and overvoltage damage to the communication circuit and ensure communication stability; Protocol support: The RS485 interface follows the Modbus-RTU protocol, and the CAN interface follows the CAN-Open protocol. External devices or host computers can send motor control commands (such as target speed setting and forward / reverse switching) through the communication interface, and at the same time receive the real-time motor status (such as current speed and overload status) fed back by the main control unit.

[0020] like Figure 6 As shown, the main control unit uses an ARM core processor, and its workflow is as follows: Data reception: Real-time reception of motor operating current signal and commutation electromotive force signal transmitted by the sampling system, and simultaneous reception of external control commands (such as target speed) through the communication system. Speed ​​calculation: The real-time speed is calculated by statistically analyzing the commutation frequency based on the electromotive force signal and combining it with the number of motor commutation plates. PID control: By comparing the target speed with the real-time speed, an adjustment signal is generated through the PID algorithm and sent to the drive output circuit to adjust the PWM duty cycle so that the motor speed approaches the target value; Status feedback and protection: The real-time motor speed, operating current, and other statuses are fed back to the host computer via the communication system; if a motor overload (current exceeding the limit) is detected, the protection mechanism is immediately triggered, cutting off the drive output and triggering an alarm; Customizable control: Users can set motor action steps (such as multi-speed switching, timed start and stop) through host computer software, and the main control unit executes the control according to the set logic.

[0021] This system eliminates the need for an additional encoder, reducing hardware costs and resolving installation limitations. It also offers advantages such as overload protection, stable communication, and precise control, making it suitable for scenarios requiring encoder-free speed control.

[0022] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A closed loop control and monitoring system based on brush motor commutation detection, characterized by: It includes a power supply system, a communication system, a sampling system, a drive output circuit, and a main control unit; The power supply system is electrically connected to the communication system, sampling system, drive output circuit and main control unit respectively, and is used to provide stable power supply to each module; The communication system is electrically connected to the main control unit and is used to transmit external control commands and the real-time operating status of the motor. The sampling system is electrically connected to the main control unit and is used to sample the motor's operating current and the reverse electromotive force at the moment of motor commutation, and transmit the processed sampling signal to the main control unit. The drive output circuit is electrically connected to the power supply system and the main control unit respectively, and is used to drive the motor to perform start-stop and forward / reverse rotation actions. The main control unit is used to receive sampling signals, calculate the commutation frequency based on the back electromotive force, obtain the real-time speed by combining the number of motor commutation segments, and drive the output circuit through PID regulation to achieve closed-loop control of motor speed.

2. The closed-loop control and monitoring system based on brushed motor commutation detection according to claim 1, characterized in that: The power supply system includes parallel TVS diodes D4 and D5, a first voltage regulator circuit with DC-DC voltage regulator chip U2 as the core, a second voltage regulator circuit with voltage regulator chip U3 as the core, and a boost circuit. The TVS diodes D4 and D5 are used to absorb surge voltage; the first voltage regulator circuit regulates the input power supply VCC to 5V; the second voltage regulator circuit regulates the 5V voltage to 3.3V to power the main control unit; and the boost circuit boosts the 5V voltage to 12V to power the drive output circuit.

3. The closed-loop control and monitoring system based on brushed motor commutation detection according to claim 1, characterized in that: The communication system includes an RS485 interface, a CAN communication interface, and an interface protection circuit consisting of a resettable fuse, a TVS diode, and a resistor; the communication system supports Modbus-RTU protocol and CAN-Open protocol.

4. The closed-loop control and monitoring system based on brushed motor commutation detection according to claim 1, characterized in that: The sampling system includes a current sampling circuit and an electromotive force sampling circuit; The current sampling circuit includes a first filter circuit composed of resistors and capacitors, a rail-to-rail high-precision operational amplifier, and a second filter circuit; the motor operating current is transmitted to the AD acquisition interface of the main control unit after passing through the first filter, the operational amplifier amplification, and the second filter. The electromotive force sampling circuit includes a resistor voltage divider circuit and a capacitor filter circuit, which is used to sample the reverse electromotive force at the moment of motor commutation and transmit it to the main control unit.

5. The closed-loop control and monitoring system based on brushed motor commutation detection according to claim 1, characterized in that: The drive output circuit includes an H-bridge drive circuit, a reverse electromotive force suppression circuit, and half-bridge drive chips U5, U8, and U13. The H-bridge drive circuit includes MOSFETs Q5, Q6, Q7, and Q8; the reverse electromotive force suppression circuit includes MOSFET Q2 and power resistors R41, R42, and R43; the half-bridge drive chip receives the PWM signal from the main control unit and drives the H-bridge MOSFETs to turn on and off; the drive output circuit adopts unipolar PWM control.

6. A closed loop control and monitoring system based on commutation detection of a brushed motor as claimed in claim 1, wherein: The main control unit uses an ARM core processor, which allows users to set the motor action steps through host computer software. The main control unit is also used to monitor the motor operating current. When the current reaches the system's maximum withstand current, the protection is activated and an alarm message is output.

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