A control circuit for precise opening degree realized by motor speed regulation

Abstract

The utility model relates to valve control technical field especially, and more particularly to a kind of control circuit of precision opening degree realized by motor speed regulation. Technical scheme is as follows: a kind of control circuit of precision opening degree realized by motor speed regulation, including power supply circuit, MCU main control circuit, in-place detection circuit, opening degree detection circuit, motor drive circuit and direct current brush motor;Opening degree detection circuit includes the opening degree potentiometer mechanically connected in valve stem or gear box output shaft, and the signal conditioning circuit connected between opening degree potentiometer and MCU main control circuit, for converting the physical opening degree of valve into corresponding voltage signal and transmitting to the AD sampling port of MCU main control circuit;In-place detection circuit includes the opening in-place sensor and the closing in-place sensor mechanically positioned in valve full open and full close position.The control circuit of precision valve control opening degree realized by valve actuator motor speed regulation improves valve opening degree control precision, realizes more accurate system control.

Description

Technical Field

[0001] This utility model relates to the field of valve control technology, and in particular to a control circuit for precise valve opening achieved by adjusting the speed of a motor. Background Technology

[0002] In automatic control systems using valves, such as heating systems, precise control of valve opening is crucial for regulating heating temperature. Currently, traditional valve opening control methods have several shortcomings: The motor drives the actuator. The motor runs at a constant speed. When the set target opening is to be reached, the motor must stop and brake in advance due to inertia. Due to inertia and uncertainties in pipeline resistance, the control accuracy is not high. Dividing it into more gears makes it more difficult, such as 200 gears or more.

[0003] Precise opening adjustment is achieved by adjusting the motor speed. When the distance between the set target opening and the opening position is relatively large, the motor can run quickly. When it is about to reach the target opening, the speed is reduced until it stops at the set opening position. This reduces the running inertia of the motor and the reduction mechanism, achieving more precise control and allowing for more speed settings. Utility Model Content

[0004] This invention proposes a control circuit for precise opening achieved through motor speed regulation, which solves the problems in the prior art where the motor needs to stop and brake in advance due to inertia, and where the control accuracy is not high due to uncertainties in inertia and pipeline resistance.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: A control circuit for precise opening degree achieved by motor speed regulation includes a power supply circuit, an MCU main control circuit, a position detection circuit, an opening degree detection circuit, a motor drive circuit, and a DC brushed motor. The power supply circuit supplies power to each component; The valve opening detection circuit includes an opening potentiometer mechanically connected to the valve stem or gearbox output shaft, and a signal conditioning circuit connected between the opening potentiometer and the MCU main control circuit, used to convert the physical opening of the valve into a corresponding voltage signal and transmit it to the AD sampling port of the MCU main control circuit. The position detection circuit includes an open position sensor and a closed position sensor that are mechanically positioned at the fully open and fully closed positions of the valve, and its signal output terminal is connected to the IO port of the MCU main control circuit. The PWM output port of the MCU main control circuit is connected to the control terminal of the motor drive circuit, and the output terminal of the motor drive circuit drives the DC brushed motor. The MCU main control circuit is configured to: determine the current opening degree based on the voltage signal output by the opening degree detection circuit, and dynamically adjust the duty cycle of the PWM signal output to the motor drive circuit based on the difference between the current opening degree and the target opening degree.

[0006] Furthermore, when the valve is first powered on, the MCU main control circuit controls the motor to run to the fully open and fully closed positions. The position detection circuit triggers and records the voltage values ​​output by the opening detection circuit at the two extreme positions to calculate the voltage range of the entire stroke and complete the self-calibration of the opening level. Furthermore, the specific method by which the MCU main control circuit dynamically adjusts the duty cycle of the PWM signal is as follows: set at least two difference thresholds with respect to the target opening degree; when the actual difference is greater than the first threshold, output a high duty cycle PWM signal; when the actual difference is less than or equal to the first threshold and greater than zero, output a low duty cycle PWM signal. Furthermore, the signal conditioning circuit includes an operational amplifier for amplifying and filtering the output signal of the opening potentiometer. Furthermore, the motor drive circuit is implemented using a DC brushed motor drive chip. Furthermore, the power supply circuit includes a DC-DC step-down chip and a low-dropout linear regulator (LDO).

[0007] The positive effects of this utility model are: the control circuit that achieves precise valve opening control through speed regulation of the valve actuator motor improves the valve opening control accuracy and achieves more accurate system control. Attached Figure Description

[0008] Figure 1 This is a schematic block diagram of the control circuit for precise opening achieved by motor speed regulation according to this utility model. Figure 2 This is a schematic diagram of the power supply circuit structure in this utility model; Figure 3 This is a schematic diagram of the motor drive circuit structure in this utility model; Figure 4 This is a schematic diagram of the MCU main control circuit structure in this utility model; Figure 5 This is a schematic diagram of the opening degree detection circuit structure of this utility model; Figure 6 This is a schematic diagram of the positioning detection circuit in this utility model; Figure 7 This is a schematic diagram of the opening degree detection circuit structure of this utility model; Detailed Implementation

[0009] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0010] Combination Figure 1-7 As shown, a control circuit for precise opening degree achieved by motor speed regulation includes a power supply circuit, an MCU main control circuit, a position detection circuit, an opening degree detection circuit, a motor drive circuit, and a DC brushed motor. The power supply circuit provides power to each component; The valve opening detection circuit includes an opening potentiometer mechanically connected to the valve stem or gearbox output shaft, and a signal conditioning circuit connected between the opening potentiometer and the MCU main control circuit, used to convert the physical opening of the valve into a corresponding voltage signal and transmit it to the AD sampling port of the MCU main control circuit. The position detection circuit includes an open position sensor and a closed position sensor that are mechanically positioned at the fully open and fully closed positions of the valve, and its signal output terminal is connected to the IO port of the MCU main control circuit. The PWM output port of the MCU main control circuit is connected to the control terminal of the motor drive circuit, and the output terminal of the motor drive circuit drives the DC brushed motor. The MCU main control circuit is configured to: determine the current opening degree based on the voltage signal output by the opening degree detection circuit, and dynamically adjust the duty cycle of the PWM signal output to the motor drive circuit based on the difference between the current opening degree and the target opening degree.

[0011] When the valve is powered on for the first time, the MCU main control circuit controls the motor to run to the fully open and fully closed positions. The position detection circuit triggers and records the voltage values ​​output by the opening detection circuit at the two extreme positions to calculate the voltage range of the entire stroke and complete the self-calibration of the opening position. The MCU main control circuit dynamically adjusts the PWM signal duty cycle as follows: At least two threshold differences from the target opening degree are set; when the actual difference is greater than the first threshold, a high duty cycle PWM signal is output; when the actual difference is less than or equal to the first threshold and greater than zero, a low duty cycle PWM signal is output. The signal conditioning circuit includes an operational amplifier for amplifying and filtering the output signal of the opening potentiometer. The motor drive circuit uses a DC brushed motor driver chip. The power supply circuit includes a DC-DC buck converter chip and a low-dropout linear regulator (LDO).

[0012] In this specific embodiment, the position detection circuit is a position sensor, and the opening detection circuit is an opening sensor.

[0013] This utility model provides a control circuit for precise opening degree achieved by motor speed regulation, including a power supply circuit, and an MCU main control circuit, a position sensor, an opening degree sensor, a motor drive circuit, and a DC brushed motor, all of which are connected to the power supply circuit. The MCU main control circuit, position sensor, opening sensor, motor drive circuit, and DC brushed motor are connected.

[0014] The power supply circuit includes chips U9 (ME3116AM6G) and U10 (MD7218A33PA1), which output voltage to power the system and meet its power requirements. +Vin is the 24V DC power supplied by the power supply, etc. U1 is a dedicated DC / DC step-down converter chip, outputting 3.7V (+VFM) to power the valve drive circuit and the +3.3V LDO. U10 is a low-dropout LDO, outputting +3.3V to power the main control circuit, the opening sensor, and the DC brushed motor drive circuit.

[0015] The motor drive circuit is implemented using a dedicated DC brushed motor driver chip, and the MCU main control circuit controls the motor's start, stop, and speed adjustment. In this embodiment, the motor drive circuit includes chip U7 (PT2466). The position sensors include an open position sensor and a closed position sensor fixed to the gearbox. By setting the position sensors, the main control MCU circuit can obtain the position information of the limit rod.

[0016] When the opening control is implemented in the form of voltage: the circuit includes an opening sensor Rp1, and the signal is amplified by the U1 chip circuit. The opening sensor is fitted onto the output shaft of the gearbox, and the main control MCU circuit obtains the opening position information through the opening sensor.

[0017] When the opening control is implemented to record the number of motor revolutions, it consists of a motor with a rear axle (including an encoder), a reflective switch, a pulse shaping circuit, etc.

[0018] The motor drive circuit includes chip U7 (PT2466), which drives the motor, adjusts its speed, collects opening and positioning signals, and controls the valve opening through the main control MCU circuit.

[0019] The principle of motor speed control is illustrated below: When the IN1 pin of U5 receives a high level from the MCU and the IN2 pin receives a low level from the MCU, the motor operates at its maximum speed. The IN1 pin receives a PWM signal from the MCU, adjusting the pulse width ratio to regulate the motor's speed. A higher PWM pulse width ratio results in a faster motor. During operation, the MCU monitors the position of the opening potentiometer. When the motor is about to reach the set opening position, the MCU reduces the PWM pulse width ratio, decreasing the motor speed until it stops at the set opening position.

[0020] When the valve opening is achieved via voltage, the working principle is as follows: Upon initial power-up, the MCU collects and calculates the voltage value (self-calibration value) corresponding to each position. After power-up, the MCU controls the valve to operate, collects the voltage value output by the opening circuit when the valve is fully open and fully closed, calculates the relative voltage value of a position, and controls the valve to operate. When the valve moves from fully closed to fully open (or from fully open to fully closed, with full open and full close detected by the position sensor), the MCU collects the voltage value output by the opening circuit (the difference between the voltage output by the opening circuit when the valve is fully open and the voltage output by the opening circuit when the valve is fully closed is the opening voltage range).

[0021] For example: To achieve 100 voltage levels, divide the voltage value by 100 to get the voltage value for one level. For example, to open the valve to 50% (level 50), calculate the voltage output of the circuit at level 50 (voltage value at level 0 + voltage value of one level × 50). This will give you the voltage value for each level. Here are some data examples: When the valve is fully closed, the opening circuit output voltage value collected by the MCU is 1000mV, corresponding to the 0 position.

[0022] When the valve is fully open, the opening circuit output voltage value collected by the MCU is 3000mV, corresponding to the maximum setting, such as setting 100.

[0023] The MCU calculates the opening voltage range as 3000-1000=2000mV.

[0024] To achieve 100 voltage levels, the voltage value of one level is 2000 / 100 = 20mV.

[0025] If the valve is opened to 50%, that is, to the 50 setting, the corresponding opening voltage value is 1000 + 20 * 50 = 2000mV.

[0026] However, in practical applications, due to factors such as the inertia of the motor gearbox and the uncertainty of pipeline resistance, it is difficult to accurately stop at the set gear position. If the motor operates in a constant voltage mode, stopping and braking in advance will not allow it to stop accurately at the set gear position, but only near the set opening degree, and the opening accuracy cannot be guaranteed.

[0027] The opening degree is adjusted by controlling the motor speed. When the current opening position is far from the set opening position (e.g., at position 50), the motor starts at full speed (pulse width ratio 100%). When it gets closer to the set opening position (e.g., 10 positions away from the set position), the speed decreases. The closer to the set opening position, the lower the motor speed. The adjustment of the motor's control pulse width ratio is determined by the change in the voltage value output by the opening circuit. Due to the uncertainty of pipeline resistance, this prevents insufficient drive and shutdown due to high resistance during control.

[0028] Example: The voltage change of the output of the opening circuit at full speed is 100mV / s; From gear 0 to gear 50, the MCU calculates the corresponding voltage value and issues a command. The MCU controls the motor to run at 100% pulse width ratio (full voltage, full speed) and continuously reads the voltage value output by the tracking opening circuit.

[0029] For example, when the opening reaches the 40th position (10 positions away from the set opening), the voltage change of the opening circuit is adjusted to 80mV / S. The MCU controls the reduction of the motor control pulse width ratio to reduce the speed, such as adjusting it to 80% (determined according to the voltage change of the opening).

[0030] When the opening reaches the 45th position (5 positions away from the set opening), the voltage change of the opening circuit is adjusted to 40mV / S. The MCU controls the reduction of the motor control pulse width ratio to reduce the speed, such as adjusting it to 40% (determined according to the voltage change of the opening).

[0031] For example, when the opening reaches position 48 (two positions away from the set opening), the voltage change of the opening circuit is adjusted to 10mV / S. The MCU controls the reduction of the motor control pulse width ratio to reduce the speed, such as adjusting it to 20% (determined according to the voltage change of the opening).

[0032] For example, when the opening reaches the 50 level (0 levels away from the set opening), the MCU controls the motor to stop and brake, reaching the set level.

[0033] The logic for shifting from 50 to 0 is the same as above.

[0034] The working principle is that the opening degree is achieved by the number of revolutions of the motor: Upon power-up, the MCU collects and calculates the number of motor revolutions corresponding to each gear position (self-calibration value): After power-up, the MCU controls the valve operation. From fully closed to fully open (or from fully open to fully closed, with full open and full close determined by position sensors), the MCU collects and records the total number of motor revolutions. To achieve 100 gear positions, the total number of motor revolutions divided by 100 gives the number of motor revolutions for one gear position. For example, to open the valve to 50% (gear position 50), the number of motor revolutions at position 50 is calculated (number of motor revolutions for one gear position × 50, starting from when the valve is fully closed). This allows the calculation of the voltage value corresponding to each gear position.

[0035] example: When the valve is fully closed, the number of motor revolutions collected by the MCU is 0, corresponding to gear 0.

[0036] When the valve is fully open, the MCU collects 1500 motor revolutions, which corresponds to the maximum gear, such as gear 100.

[0037] To achieve 100 speeds, the motor would need to rotate 1500 / 100 = 15 times per speed.

[0038] If the valve is opened to 50%, that is, to the 50th position, the corresponding number of motor rotations is 15 * 50 = 750.

[0039] At the same time, the MCU records the number of motor revolutions at this opening degree for use when adjusting the opening degree next time.

[0040] However, in practical applications, due to factors such as the inertia of the motor gearbox and the uncertainty of pipeline resistance, it is difficult to accurately stop at the set gear position. If the motor operates in a constant voltage mode, stopping and braking in advance will not allow it to stop accurately at the set gear position, but only near the set opening degree, and the opening accuracy cannot be guaranteed.

[0041] The opening is adjusted using motor speed control. When the current opening position is far from the set opening position (e.g., at position 50), the motor starts at full speed (pulse width ratio 100%). As it gets closer to the set opening position (e.g., 10 positions away from the set position), the speed decreases. The closer to the set opening position, the lower the motor speed. The adjustment of the motor's control pulse width ratio is determined by the change in the number of motor revolutions. This is to prevent insufficient drive and shutdown due to high resistance during the control process, given the uncertainty of pipeline resistance.

[0042] For example, a motor running at full speed rotates 50 revolutions per second.

[0043] From gear 0 to gear 50, the MCU calculates the corresponding number of revolutions. After issuing the command, the MCU controls the motor to run at 100% pulse width ratio (full voltage, full speed) and records the number of revolutions of the motor.

[0044] For example, when the opening reaches the 40th position (10 positions away from the set opening), the change in the number of motor revolutions is adjusted to 40 revolutions / second. The MCU control reduces the pulse width ratio of the motor control to reduce the speed, such as adjusting it to 80% (determined based on the change in the number of motor revolutions).

[0045] When the opening reaches the 45 setting (5 settings away from the set opening), the change in the number of motor revolutions is adjusted to 20 revolutions / second. The MCU control reduces the pulse width ratio of the motor control to decrease the speed, such as adjusting it to 40% (determined based on the change in the number of motor revolutions).

[0046] For example, when the opening reaches position 48 (two positions away from the set opening), the change in the number of motor revolutions is adjusted to 10 revolutions / second. The MCU control reduces the pulse width ratio of the motor control to reduce the speed, such as adjusting it to 20% (determined based on the change in the number of motor revolutions).

[0047] For example, when the opening reaches the 50 level (0 levels away from the set opening), the MCU controls the motor to stop and brake, reaching the set level.

[0048] The logic for shifting from 50 to 0 is the same as above.

[0049] In this embodiment, the MCU main control circuit completes the signal acquisition and control processing, and its main control chip U11 is model FM33LG048.

[0050] The above-described embodiments are detailed and specific, illustrating preferred embodiments of the present utility model. They are only used to illustrate the technical ideas and features of the present utility model, with the aim of enabling those skilled in the art to understand the content of the present utility model and implement it accordingly. However, they are not limited to the present utility model, and the patent scope of the present utility model cannot be limited by this embodiment alone. That is, any equivalent changes or modifications made to the spirit disclosed in the present utility model, without departing from the structure of the present utility model, such as local improvements within the system and modifications or transformations between subsystems, are still within the patent scope of the present utility model.

Claims

1. A control circuit for precise opening degree achieved through motor speed regulation, characterized in that, This includes a power supply circuit, an MCU main control circuit, a position detection circuit, an opening detection circuit, a motor drive circuit, and a DC brushed motor; The power supply circuit supplies power to each component; The valve opening detection circuit includes an opening potentiometer mechanically connected to the valve stem or gearbox output shaft, and a signal conditioning circuit connected between the opening potentiometer and the MCU main control circuit, used to convert the physical opening of the valve into a corresponding voltage signal and transmit it to the AD sampling port of the MCU main control circuit. The position detection circuit includes an open position sensor and a closed position sensor that are mechanically positioned at the fully open and fully closed positions of the valve, and its signal output terminal is connected to the IO port of the MCU main control circuit. The PWM output port of the MCU main control circuit is connected to the control terminal of the motor drive circuit, and the output terminal of the motor drive circuit drives the DC brushed motor. The MCU main control circuit is configured to: determine the current opening degree based on the voltage signal output by the opening degree detection circuit, and dynamically adjust the duty cycle of the PWM signal output to the motor drive circuit based on the difference between the current opening degree and the target opening degree.

2. The control circuit for precise opening degree achieved by motor speed regulation according to claim 1, characterized in that, When the valve is first powered on, the MCU main control circuit controls the motor to run to the fully open and fully closed positions. The position detection circuit triggers and records the voltage values ​​output by the opening detection circuit at the two extreme positions to calculate the voltage range of the entire stroke and complete the self-calibration of the opening position.

3. The control circuit for precise opening degree achieved by motor speed regulation according to claim 2, characterized in that, The specific method for the MCU main control circuit to dynamically adjust the duty cycle of the PWM signal is as follows: set at least two difference thresholds with the target opening degree; when the actual difference is greater than the first threshold, output a high duty cycle PWM signal; when the actual difference is less than or equal to the first threshold and greater than zero, output a low duty cycle PWM signal.

4. The control circuit for precise opening degree achieved by motor speed regulation according to claim 1, characterized in that, The signal conditioning circuit includes an operational amplifier for amplifying and filtering the output signal of the potentiometer.

5. The control circuit for precise opening degree achieved by motor speed regulation according to claim 1, characterized in that, The motor drive circuit is implemented using a DC brushed motor drive chip.

6. The control circuit for precise opening degree achieved by motor speed regulation according to claim 1, characterized in that, The power supply circuit includes a DC-DC step-down chip and a low-dropout linear regulator (LDO).

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