PWM to DA automatic speed regulating device suitable for sample needle and reagent needle cleaning pump

Abstract

The utility model discloses a kind of PWM conversion DA automatic speed regulating device suitable for sample needle and reagent needle cleaning pump, including controller, the speed feedback interface of the controlled water pump motor is connected with the speed signal acquisition interface of controller by PWM feedback circuit through the PWM signal output interface of controller, IO interface of controller is connected with electronic switch control end, the power interface of the controlled water pump motor is connected with driving power supply by the electronic switch.The utility model generates duty cycle adjustable PWM signal by STM32 microcontroller, the PWM signal is converted into analog signal after two-stage RC filtering, can support multiple load, with low cost, fast response speed feature, realize real-time automatic high-precision regulation controlled water pump motor speed.

Description

Technical Field

[0001] This utility model relates to an automatic speed control device for cleaning pumps, and more particularly to a PWM to DA automatic speed control device suitable for cleaning pumps for sample needles and reagent needles. Background Technology

[0002] Currently, sample needles and reagent needles require cleaning with purified water. During the cleaning process, the flow rate of the cleaning pump needs to be quickly and accurately adjusted according to the cleaning process requirements. Currently, the speed control method for sample needle and reagent needle cleaning pumps is mostly to adjust the analog quantity using a digital potentiometer or to adjust the voltage using a digital potentiometer to regulate the flow rate. However, real-time flow rate adjustment is slow and prone to error. Using PWM (Pulse Width Modulation) control to control the cleaning pump's operating status has drawbacks such as slow PWM-to-DA (analog) conversion, poor accuracy, and high cost. Summary of the Invention

[0003] In view of this, the present invention provides a PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps, so as to improve the speed control accuracy of the cleaning pump.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps of this utility model includes a controller. The PWM signal output interface of the controller is connected to the speed control interface of the controlled water pump motor via a PWM to DA circuit and an integrated operational amplifier. The speed feedback interface of the controlled water pump motor is connected to the speed signal acquisition interface of the controller via a PWM feedback circuit. The IO interface of the controller is connected to the control terminal of an electronic switch. The power interface of the controlled water pump motor is connected to the drive power supply via the electronic switch.

[0006] Optionally, the PWM to DA circuit consists of a second-order filter composed of resistor R1 and capacitor C1, and resistor R2 and capacitor C2. Compared with a first-order filter, the second-order filter has a lower cutoff frequency and stronger ripple suppression capability. The PWM signal converts the square wave output by the controller into a DC signal during the first RC filter. The subsequent RC filter makes the DC signal more stable and the filtered signal smoother. The high-potential end of resistor R1 is connected to the PWM signal output interface of the controller, the low-potential end of resistor R2 is connected to the non-inverting input of the integrated operational amplifier, the inverting input of the integrated operational amplifier is connected to the ground terminal GND through resistor R4, and the output of the integrated operational amplifier is connected to the speed control interface of the controlled water pump motor through a Zener diode. The amplification factor of the speed control port is flexibly adjustable, and the amplification factor = (R3 + R4) / R4. The amplification factor can be flexibly configured according to different types of controlled water pump motors.

[0007] Optionally, the PWM feedback circuit includes an optocoupler. The positive terminal of the LED at the input of the optocoupler is connected to the operating voltage VDD1 via resistor R5, and the negative terminal of the LED is connected to the speed feedback interface of the controlled water pump motor. After the feedback signal of the controlled water pump motor is transmitted through the optocoupler, the output signal can be effectively electrically isolated from the output signal, and the protection circuit is protected from interference from high voltage or noise, making the speed reading of the controlled water pump motor more accurate.

[0008] The collector of the transistor at the output terminal of the optocoupler is connected to the speed signal acquisition interface of the controller and the operating voltage VDD2, respectively, and the emitter of the transistor is connected to the ground terminal GND.

[0009] Optionally, the controller is an STM32 microcontroller; of course, other controllers may also be used.

[0010] This invention generates a PWM signal with an adjustable duty cycle using an STM32 microcontroller. This PWM signal is converted into an analog signal through two stages of RC filtering, which can support multiple loads and features low cost and fast response speed, enabling real-time automatic high-precision adjustment of the controlled water pump motor speed. Attached Figure Description

[0011] Figure 1 This is a circuit block diagram of an embodiment of the present invention.

[0012] Figure 2 This is a circuit diagram of the PWM to DA circuit and integrated operational amplifier described in an embodiment of this utility model.

[0013] Figure 3 This is a circuit diagram of the PWM feedback circuit described in an embodiment of the present invention. Detailed Implementation

[0014] The embodiments of this utility model will be described in detail below with reference to the accompanying drawings. These embodiments are implemented based on the technical solution of this utility model and provide detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the following embodiments.

[0015] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0016] like Figure 1-3As shown, the PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps of this utility model includes a controller, which is an STM32 microcontroller; of course, other controllers can also be used.

[0017] The controller's PWM signal output interface is connected to the speed control interface of the controlled water pump motor (model: D30LE) via a PWM to DA circuit and an integrated operational amplifier. The speed feedback interface of the controlled water pump motor is connected to the controller's speed signal acquisition interface via a PWM feedback circuit. The controller's IO interface is connected to the electronic switch control terminal. The power interface of the controlled water pump motor is connected to the drive power supply via the electronic switch.

[0018] Beneficially or exemplaryly, such as Figure 2 As shown, the PWM to DA circuit consists of a second-order filter composed of resistor R1 and capacitor C1, and resistor R2 and capacitor C2. Compared with the first-order filter, the second-order filter has a lower cutoff frequency and stronger ripple suppression capability. The high-potential end of resistor R1 is connected to the PWM signal output interface of the controller, and the low-potential end of resistor R2 is connected to the non-inverting input of integrated operational amplifier U1. The inverting input of integrated operational amplifier U1 is connected to the ground terminal GND through resistor R4. The output of integrated operational amplifier U1 amplifies the DC voltage output by the second-order filter by a set factor and then connects to the speed control interface of the controlled water pump motor through a Zener diode. A feedback resistor R3 is connected between the output and inverting input of integrated operational amplifier U1.

[0019] Beneficially or exemplaryly, such as Figure 3 As shown, the PWM feedback circuit includes an optocoupler U2. The positive terminal of the LED at the input end of the optocoupler U2 is connected to the working voltage VDD1 via resistor R5, and the negative terminal of the LED is connected to the speed feedback interface FG of the controlled water pump motor. The collector of the transistor at the output end of the optocoupler U2 is connected to the speed signal acquisition interface PO of the controller and the working voltage VDD2, respectively, and the emitter of the transistor is connected to the ground terminal GND.

[0020] The controller generates a PWM signal with an adjustable duty cycle. The PWM signal is converted into a DA signal through two stages of RC filtering. After setting the speed Va of the controlled water pump motor, the controller controls the rotation of the controlled water pump motor with an initial duty cycle value, and obtains the real-time speed Vb of the controlled water pump motor through the PWM feedback circuit. If the speed Va = speed Vb, the duty cycle of the PWM signal remains unchanged; if the speed Va < speed Vb, the duty cycle of the PWM signal is decreased until Va = Vb; if the speed Va > speed Vb, the duty cycle of the PWM signal is increased until Va = Vb.

[0021] Finally, it should be emphasized that the above description is merely a preferred embodiment of this utility model and is not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still make modifications to the technical solutions described in the foregoing embodiments without creative effort, or make equivalent substitutions for some of the technical features. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps, comprising a controller, characterized in that: The controller's PWM signal output interface is connected to the speed control interface of the controlled water pump motor via a PWM-to-DA circuit and an integrated operational amplifier. The speed feedback interface of the controlled water pump motor is connected to the controller's speed signal acquisition interface via a PWM feedback circuit. The controller's I / O interface is connected to the electronic switch control terminal. The controlled water pump motor's power interface is connected to the drive power supply via the electronic switch.

2. The PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps according to claim 1, characterized in that: The PWM to DA circuit consists of a second-order filter composed of resistor R1 and capacitor C1, and resistor R2 and capacitor C2. The high-potential end of resistor R1 is connected to the PWM signal output interface of the controller, the low-potential end of resistor R2 is connected to the non-inverting input of the integrated operational amplifier, the inverting input of the integrated operational amplifier is connected to ground GND via resistor R4, and the output of the integrated operational amplifier is connected to the speed control interface of the controlled water pump motor via a Zener diode. A feedback resistor R3 is connected between the output and inverting input of the integrated operational amplifier.

3. The PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps according to claim 1 or 2, characterized in that: The PWM feedback circuit includes an optocoupler. The positive terminal of the LED at the input end of the optocoupler is connected to the operating voltage VDD1 via resistor R5, and the negative terminal of the LED is connected to the speed feedback interface of the controlled water pump motor. The collector of the transistor at the output end of the optocoupler is connected to the speed signal acquisition interface of the controller and the operating voltage VDD2, respectively, and the emitter of the transistor is connected to the ground terminal GND.

4. The PWM to DA automatic speed control device suitable for sample needle and reagent needle cleaning pumps according to claim 1 or 2, characterized in that: The controller is an STM32 microcontroller.

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