A method and system for driving a peristaltic pump using a direct current polarity reversal of an alternating current stepper motor

Abstract

The application discloses a kind of AC stepper motor direct current polarity commutation peristaltic pump driving method and system, belong to motor control and fluid delivery technical field.The present application aims to solve the problem of short service life, unstable flow of traditional brush DC peristaltic pump, and the interface of conventional step peristaltic pump is incompatible.This method includes: receiving DC polarity switching input through a unique external two-wire DC interface;Utilize the voltage conversion circuit to rectify, divide voltage, step-down and level clamping protection to the input voltage, output the standard high and low level that microcontroller can safely identify;Microcontroller determines input polarity and identifies forward and reverse command according to the high and low level, then outputs corresponding step drive timing signal to motor drive circuit;Motor drive circuit drives AC stepper motor to run according to specified timing, drives peristaltic pump structure to execute delivery or backflow.The present application has high life, high stability of stepper motor and plug and play ease of use of DC motor, and is 100% compatible with existing brush DC pump control interface.

Description

Technical Field

[0001] This invention belongs to the field of motor control and precision fluid transport technology, specifically relating to a peristaltic pump driving method and driving system with AC stepper motor DC polarity reversal. Background Technology

[0002] A peristaltic pump is a precision device that uses a motor-driven roller to compress an elastic pump tube, utilizing the elastic deformation and repositioning of the tube to generate vacuum suction and thrust, thereby achieving contactless fluid transport. Due to its characteristics of zero cross-contamination, low shear force, high sealing performance, and simple maintenance, it is widely used in many scenarios such as medical devices, biochemical analysis instruments, pharmaceuticals, chemical engineering, water treatment, and laboratory fluid micro-dispensing.

[0003] Currently, the mainstream micro peristaltic pump drive solutions on the market can be mainly divided into the following two categories:

[0004] 1. Brushed DC Peristaltic Pump: This type of solution uses a traditional brushed DC motor as the actuator, requiring only two commutation control lines for external control. When the polarity of the external input DC voltage (such as 12V or 24V) is reversed (i.e., DC polarity switching input), the direction of the magnetic field inside the motor changes accordingly, thereby achieving forward and reverse rotation control of the peristaltic pump. This two-wire control interface is extremely simple, and the control logic is highly versatile, making it widely used in many older or low-cost automated devices.

[0005] 2. Stepper motor peristaltic pump: This type of pump uses a stepper motor as the actuator. It has a brushless structure and offers advantages such as long lifespan, precise speed control, and insensitivity to voltage fluctuations. However, the drive control of a conventional stepper motor relies on two independent digital signal lines (usually four-wire or more) for "pulse + direction". The microcontroller or host computer must continuously output high-speed pulse trains to control the speed and control the direction via directional level.

[0006] In existing practices for upgrading and retrofitting industrial and medical equipment, the two traditional technical solutions mentioned above have irreconcilable drawbacks, as detailed below:

[0007] Disadvantage 1 (High lifespan and maintenance costs): Traditional brushed DC peristaltic pumps rely heavily on the mechanical contact between carbon brushes and the commutator for commutation. Under long-term continuous operation, the carbon brushes will wear out rapidly, accompanied by electrical sparking, leading to a rapid deterioration of the motor's internal electrical performance. This results in a continuous operating life of less than 200 hours for the entire machine, with an extremely high failure rate, causing frequent downtime for maintenance and parts replacement costs in medical devices or industrial settings.

[0008] Disadvantage 2 (Poor Flow Stability and Accuracy): The output speed of a brushed DC motor exhibits a strong linear correlation with its terminal voltage. When there are fluctuations in the power grid, a drop in battery voltage, or a voltage drop in the control circuit, the voltage input to the motor will fluctuate accordingly, directly causing the motor speed to vary drastically. In peristaltic pumps, this translates to an inability to guarantee the accuracy of the fluid flow, making it difficult to meet the requirements of high-end medical dispensing or precision analytical instruments.

[0009] Disadvantage 3 (System Modification and Incompatibility Issues): While stepperistaltic pumps can perfectly solve the aforementioned lifespan and stability problems, they require additional pulse and direction control interfaces. Many existing older devices, PLC control systems, or dedicated motherboards only retain the two-wire "DC polarity switching" interface designed specifically for brushed DC pumps. Directly replacing a brushed DC pump with a conventional stepper pump requires extensive modifications to the main control board circuitry, and even rewriting the underlying control program, resulting in extremely high modification costs and very poor versatility.

[0010] Disadvantage 4 (Lack of Hardware Protection and Voltage Adaptation): In industrial settings, the control voltage for DC polarity switching is typically 12V or 24V high-voltage DC. If a simple acquisition circuit is designed to read this polarity, without high-voltage voltage division and step-down, level clamping, and I / O protection mechanisms, the 12V / 24V high-voltage signal, if directly or due to line surges, is connected to the microcontroller, will far exceed the microcontroller chip's withstand voltage threshold (typically 5V or 3.3V), instantly burning out the microcontroller's I / O ports and causing the entire drive system to malfunction.

[0011] A search of existing technologies, such as Chinese Patent Publication No. CN112751511B and Japanese Patent Publication No. JP7224204B2, reveals that they all employ conventional pulse and direction dual-line control methods to drive stepper motors. Other improvements in the peristaltic pump field (such as the elastic roller combination in CN118167597A and the precise flow control in CN114294207A) focus on optimizing the mechanical structure and do not propose a solution for perfectly replacing brushed DC motors with stepper motors from the perspective of driving methods and control circuits. Summary of the Invention

[0012] To overcome the shortcomings of the prior art, the present invention provides a peristaltic pump driving method and system with DC polarity reversal of AC stepper motor. It can seamlessly replace the existing brushed DC peristaltic pump two-wire control interface with a long life and high stability stepper actuator, while having a complete hardware protection mechanism and wide voltage compatibility.

[0013] The technical solution adopted by this invention to solve its technical problem is as follows:

[0014] A method for driving a peristaltic pump with DC polarity commutation using an AC stepper motor includes the following specific steps:

[0015] Step S100: Receive DC polarity switching input signal. The DC polarity switching input signal is input through a set of two-wire DC control interfaces. The positive and negative terminals of the DC voltage are interchanged to serve as forward and reverse control commands, which is fully compatible with the existing brushed DC peristaltic pump control logic.

[0016] Step S200: The polarity acquisition voltage conversion circuit acquires the positive and negative states of the DC polarity switching input signal, and simultaneously performs voltage division and level clamping protection on the DC polarity switching input signal above 5V, and outputs a standard high or low level within the safety recognition range of the microcontroller.

[0017] Step S300: The microcontroller's I / O port detects the standard high or low level, uniquely determines the input polarity based on the high or low state of the level, and identifies the corresponding forward or reverse instruction;

[0018] Step S400: Based on the identified forward or reverse instruction, the microcontroller internally calls the pre-stored stepper motor drive timing sequence and outputs the corresponding stepper motor drive timing signal to the motor drive circuit. No additional pulses or direction control lines are required from the outside throughout the process.

[0019] Step S500: The motor drive circuit receives the stepper motor drive timing signal and amplifies the power, driving each phase winding of the AC stepper motor powered by DC to operate in a specified timing sequence, thereby driving the peristaltic pump structure to complete the precision fluid delivery or reverse flow action.

[0020] As a preferred embodiment, in step S200, the voltage conversion circuit for polarity acquisition employs the following buck and level clamping logic: when the DC polarity switching input signal is positively connected, after being bucked by a voltage divider network and clamped by a Zener diode, a first standard level of 1.8V~5V (preferably 2.18V) is output to the I / O port of the microcontroller; when the DC polarity switching input signal is negatively connected, the voltage conversion circuit for polarity acquisition outputs a second standard level of 0V~0.8V (preferably 0V) to the I / O port of the microcontroller.

[0021] The present invention also provides a peristaltic pump drive system for implementing the above method with DC polarity reversal of an AC stepper motor, comprising:

[0022] A two-wire DC interface is used to receive external DC polarity switching input signals.

[0023] A polarity acquisition voltage conversion circuit, whose input terminal is electrically connected to the two-wire DC interface, is used to acquire polarity, voltage division and reduction, and level clamping.

[0024] The microcontroller control unit has its I / O detection port electrically connected to the output terminal of the polarity acquisition voltage conversion circuit, which is used to identify polarity and output step drive timing signal;

[0025] The motor drive circuit is electrically connected to the timing output terminal of the microcontroller control unit and is used to amplify and output the stepper drive timing signal.

[0026] An AC stepper motor is electrically connected to the power output terminal of the motor drive circuit and operates at a fixed step angle under the drive of the motor drive circuit.

[0027] The peristaltic pump structure is mechanically connected to the output shaft of the AC stepper motor, and is driven by the AC stepper motor to perform fluid delivery.

[0028] As a further refined circuit design, the polarity acquisition voltage conversion circuit includes a rectifier bridge, a voltage divider resistor network, and a Zener diode level clamping circuit. The DC input terminals V+ and V- of the two-wire DC interface are connected to the input terminals of the rectifier bridge. The output terminal of the rectifier bridge is connected to a high-voltage step-down processing module to provide the required low-voltage DC power supply for the system. The DC input terminal V+ is also connected to a voltage divider node via a voltage divider resistor network. The voltage divider node is electrically connected to the cathode of the Zener diode D1, while the anode of the Zener diode D1 is grounded. The voltage divider node is also electrically connected to the I / O detection port of the microcontroller control unit.

[0029] More specifically, the voltage divider resistor network includes a first voltage divider resistor R1 and a second voltage divider resistor R2; the DC input terminal V+ is connected to the voltage divider node via the first voltage divider resistor R1, and one end of the second voltage divider resistor R2 is connected to the voltage divider node, while the other end is grounded. The resistance value of the first voltage divider resistor R1 is preferably 100kΩ, the resistance value of the second voltage divider resistor R2 is preferably 10kΩ, and the voltage regulation value of the Zener diode D1 is preferably 5.1V.

[0030] As an alternative circuit implementation, the polarity acquisition voltage conversion circuit can adopt an optocoupler isolation circuit architecture. The input terminal of the two-wire DC interface is connected to the light-emitting diode side of the optocoupler isolator via a current-limiting resistor. The phototransistor side of the optocoupler is electrically connected to the I / O detection port of the microcontroller control unit to achieve complete electrical isolation between the input high-voltage signal and the strong and weak currents of the microcontroller.

[0031] The motor drive circuit has two equivalent alternative implementations:

[0032] 1. Discrete Component Drive Scheme: This scheme includes a transistor preamplifier circuit and a MOSFET power switch circuit. The low-voltage timing output of the microcontroller is connected to the input of the transistor preamplifier circuit, the output of the transistor preamplifier circuit is connected to the gate of the MOSFET power switch circuit, and the drain of the MOSFET power switch circuit is electrically connected to the winding interface of the AC stepper motor. This scheme uses common components and is low in cost.

[0033] 2. Integrated chip driver solution: An integrated dedicated stepper driver chip is adopted. The output timing signal of the microcontroller is directly connected to the signal input terminal of the dedicated driver chip. The chip integrates amplification and power switching functions, making the overall circuit structure simpler and more integrated.

[0034] Compared with the prior art, the technical solution of the present invention has the following significant advantages and beneficial effects:

[0035] 1. Plug and play, extremely compatible: This invention breaks away from the traditional mindset that stepper motors must rely on multi-wire control of "pulse + direction," innovatively establishing a three-in-one polarity acquisition and voltage conversion circuit at the hardware level. This allows the drive system to function as a standard brushed DC motor interface (requiring only two wires) when facing external control, achieving 100% compatibility with existing equipment's brushed pump control interfaces and control logic for switching positive and negative poles and reversing directions. Existing equipment or medical host systems can be directly replaced and seamlessly upgraded without altering any internal wiring or control programs, at zero retrofit cost.

[0036] 2. Maintenance-free and significantly extended service life: By adopting an AC stepper motor-to-DC drive architecture to replace the traditional brushed DC motor, the mechanical friction loss, arcing, and electromagnetic interference failure points between the carbon brushes and commutator of the brushed motor are completely eliminated. Experimental tests have proven that the continuous trouble-free operation time of the peristaltic pump under this drive solution is significantly increased from less than 200 hours for traditional brushed pumps to over 200 hours (reaching the conventional stepper motor-level lifespan of 200-2000 hours), greatly reducing the maintenance frequency and daily replacement costs for end users.

[0037] 3. High operational stability and strong resistance to voltage drop fluctuations: Relying on the inherent physical characteristics of AC stepper motors with fixed step angles and constant torque, their speed is only related to the internal timing frequency output by the microcontroller, and has no direct linear relationship with the magnitude of the supply voltage. When there are ±10% grid fluctuations, line voltage drops, or battery drops in 12V or 24V power supply lines, the flow rate change rate of traditional brushed pumps can reach approximately ±10%, while the flow rate change rate of the solution of this invention can be strictly suppressed within the range of ≤±2%, which greatly improves the quality accuracy of fluid precise delivery and metering.

[0038] 4. Robust hardware protection and wide versatility: The specially designed polarity acquisition voltage conversion circuit in this solution is not a simple superposition of single-function circuits, but simultaneously realizes three functions: polarity discrimination, high voltage step-down conversion, and microcontroller I / O port overvoltage clamping protection. It can operate reliably and stably within a wide industrial / medical general voltage input range of 12V to 24V, perfectly avoiding the technical risk of high voltage surges burning out the microcontroller, making it suitable for a wide range of scenarios. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below:

[0040] Figure 1 This is a block diagram of the overall system architecture of the AC stepper motor DC polarity reversing peristaltic pump drive system of the present invention;

[0041] Figure 2 This is a detailed circuit diagram of the polarity acquisition voltage conversion circuit, microcontroller, and discrete device motor drive circuit in Embodiment 1 of the present invention;

[0042] Figure 3 This is a circuit diagram showing the connection between the motor drive circuit with the integrated driver chip and the microcontroller in Embodiment 2 of the present invention.

[0043] Figure 4 This is a three-dimensional exploded view of the peristaltic pump structure controlled by the drive system of the present invention;

[0044] Figure 5 This is a schematic diagram of the overall appearance of the peristaltic pump structure controlled by the drive system of the present invention after assembly.

[0045] Figure 6 This is a flowchart illustrating the peristaltic pump driving method of the present invention, which uses an AC stepper motor with DC polarity reversal. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0047] Example 1

[0048] See Figure 1 and Figure 2 The present invention provides a peristaltic pump drive system with DC polarity reversal of AC stepper motor. Its overall physical architecture is connected in the following order of signal and energy transmission: external DC polarity switching input signal → polarity acquisition voltage conversion circuit → microcontroller control unit → motor drive circuit → AC stepper motor → peristaltic pump structure (6).

[0049] The external DC polarity switching input signal is introduced through a set of two-wire DC interfaces (corresponding to external terminal physical interface J1 in the circuit physical layer, including two terminals 1 and 2). This two-wire DC interface is completely consistent with the existing brushed DC peristaltic pump control physical interface. Users can change the positive and negative polarity of the 12V or 24V DC power supply in the host power supply line (for example, terminal 1 connected to positive and terminal 2 connected to negative is defined as positive connection; terminal 1 connected to negative and terminal 2 connected to positive is defined as reverse connection) as the peristaltic pump forward and reverse rotation switching control command.

[0050] Polarity acquisition voltage conversion circuit (such as) Figure 2 The core innovative module of this system (shown in the dashed box on the left) includes a rectifier bridge, a high-voltage step-down processing module, and a three-in-one polarity acquisition and protection network consisting of a first voltage divider resistor R1, a second voltage divider resistor R2, and a Zener diode D1.

[0051] The two-wire DC interface has terminals 1 (corresponding to DC input V+) and 2 (corresponding to DC input V-) connected to the two AC input terminals of the rectifier bridge. Regardless of the polarity of the external DC power input to terminals 1 and 2, the rectifier bridge always outputs a stable positive DC voltage, which is connected to the high-voltage buck processing module. The high-voltage buck processing module integrates a linear regulator chip or a switching power supply chip to step down the 12V~24V high-voltage DC power to a stable low-voltage DC power supply VCC (such as +5V or +3.3V) to power the microcontroller control unit and other low-voltage components.

[0052] Simultaneously, a signal line is led out from terminal 1 (DC input V+) and connected to the voltage divider resistor network. The voltage divider resistor network includes a first voltage divider resistor R1 connected in series and a second voltage divider resistor R2 connected in parallel to ground. In this embodiment, the resistance value of the first voltage divider resistor R1 is selected as 100kΩ, and the resistance value of the second voltage divider resistor R2 is selected as 10kΩ. The common connection point of R1 and R2 forms a voltage divider node. This voltage divider node is electrically connected to the cathode of a Zener diode D1, and the anode of Zener diode D1 is grounded. The reverse breakdown voltage regulation value (clamping voltage) of Zener diode D1 is selected as 5.1V. The voltage divider node is further directly connected to the I / O detection pin (P1.0) of the microcontroller control unit through a wire.

[0053] The working principle and dynamic logic of this polarity acquisition voltage conversion circuit are as follows:

[0054] When the external control signal is positively input, terminal 1 is at a high level (taking 24V industrial voltage as an example). The 24V voltage is proportionally divided by the first voltage divider resistor R1 (100kΩ) and the second voltage divider resistor R2 (10kΩ). Without a Zener diode, its theoretical voltage division value is calculated as follows:

[0055]

[0056] The 2.18V voltage is lower than the 5.1V reverse breakdown voltage of the Zener diode D1, so Zener diode D1 is cut off, and the voltage divider node maintains a 2.18V output to the I / O detection pin (P1.0) of the microcontroller control unit. The CMOS logic inside the microcontroller will safely recognize a level higher than 1.8V as a standard high level "1". At this time, if the input voltage surges to above 30V due to industrial power grid fluctuations or surges, the voltage divider will attempt to exceed 3V or even higher. In this case, the 5.1V Zener diode D1 will play a strong level clamping and overvoltage protection role, ensuring that the input voltage of the I / O detection pin (P1.0) will never exceed the 5.1V safety threshold, thus physically isolating the high voltage and perfectly protecting the microcontroller I / O port from being burned out.

[0057] When the external control signal undergoes a DC polarity switch and becomes reversed, terminal 1 becomes the negative terminal, and its potential to ground drops to 0V. At this time, after passing through the voltage divider network, the potential at the voltage divider node quickly drops to 0V. The voltage detected by the I / O detection pin (P1.0) of the microcontroller control unit is approximately 0V, which the microcontroller internally identifies as the standard low level "0".

[0058] By means of the above circuit connection, the microcontroller control unit can determine the DC polarity of the external input in a safe state with complete hardware protection by detecting the high and low level of the I / O detection pin (P1.0), and thus identify whether the host issues a forward or reverse command.

[0059] The microcontroller control unit has a pre-stored dedicated stepper motor winding conduction logic and drive timing program. When the I / O detection pin (P1.0) is high and a forward rotation command is detected, the microcontroller alternately outputs weak electrical pulse control signals at its timing output terminals (such as pins P0.0, P0.1, P0.2, and P0.3) according to a four-phase, eight-beat timing sequence. When the I / O detection pin (P1.0) switches to low and a reverse rotation command is detected, the microcontroller automatically switches to a reverse timing sequence to alternately output weak electrical signals. The entire process is based solely on automatic commutation according to polarity level, requiring no traditional pulse control lines or direction control lines from an external host.

[0060] Because the timing signals output from the microcontroller pins are weak current signals, they cannot directly drive a power motor. Therefore, they must be amplified by a motor drive circuit. In Embodiment 1, the motor drive circuit uses a discrete component solution with good versatility and low mass production cost (such as...). Figure 2 (As shown in the dashed box on the right). The low-voltage timing signals output by the microcontroller are first amplified by the transistor preamplifier circuit. The amplified signals are then connected to the gates of four high-power MOSFETs in the MOSFET power switching circuit. The source of each MOSFET is grounded, and its drain is connected as the power output terminal to the corresponding phase pin of the motor winding interface (JP3). A freewheeling diode is connected in reverse parallel between the drain and source of each MOSFET to protect it from breakdown by the reverse induced electromotive force at the moment the winding is disconnected. By controlling the MOSFETs to conduct in turn according to a specified timing sequence, power energy can be continuously injected into the internal windings of the AC stepper motor.

[0061] The execution unit is an AC stepper motor driven by a DC-modified design. This motor eliminates the carbon brushes and mechanical commutator structure of traditional brushed motors. Relying on its internally fixed step angle characteristic, it rotates precisely at a fixed step angle when the windings receive the amplified sequential current. Its output speed is entirely determined by the timing switching frequency within the microcontroller, resulting in extremely constant speed. Even if the external power supply line experiences a drastic voltage drop or fluctuation due to sudden load changes, the AC stepper motor's speed will not drift erratically.

[0062] The output shaft of the AC stepper motor is mechanically connected to the peristaltic pump structure (6). (See also...) Figure 4 and Figure 5 The specific mechanical structure of the peristaltic pump structure (6) to which this invention is applicable is shown:

[0063] The peristaltic pump structure (6) includes: outer shell (61), supporting outer shell (62), top shell (60), stirring support wheel (63), roller (64), bearing (65), inlet pipe (66) and outlet pipe (67).

[0064] An AC stepper motor is fixedly installed under the support housing (62) by screws. Its power output shaft passes through the central through hole of the support housing (62) and is mechanically connected to the internal stirring support wheel (63).

[0065] Several rollers (64) and matching miniature bearings (65) are symmetrically installed on the circumferential edge of the stirring support wheel (63). A highly elastic soft pump tube (68) is laid in a U-shape in the groove of the inner wall of the support shell (62). The two ends of the elastic pump tube (68) extend outward and are fixedly connected to the inlet pipe (66) and the outlet pipe (67), respectively.

[0066] When the AC stepper motor rotates under the timing drive of the motor drive circuit, it drives the stirring support wheel (63) to rotate synchronously. The roller (64) and bearing (65) on the stirring support wheel (63) then continuously and locally mechanically squeeze the elastic pump tube (68). The inner cavity of the hose in the squeezed part is completely closed. As the roller rolls, the fluid in the hose is continuously pushed forward and output. The pump tube part after the roller rolls quickly returns to its original shape due to its own elasticity, forming a local negative pressure vacuum inside, thereby continuously drawing the external fluid at the water inlet pipe (66) into the elastic pump tube (68).

[0067] When the microcontroller detects that the external DC polarity switching input has become reversed, the microcontroller outputs the reverse drive timing, the AC stepper motor immediately reverses its rotation, and the rollers then reverse the pressure on the pump tube, so that the peristaltic pump structure (6) completes the reverse flow of fluid from the outlet pipe (67) to the inlet pipe (66).

[0068] Example 2

[0069] See Figure 3 Embodiment 2 of the present invention provides another drive system implementation scheme with higher integration and simpler circuit structure. The core architecture, working method and polarity acquisition voltage conversion circuit of Embodiment 2 are exactly the same as those of Embodiment 1. The only difference is the specific circuit implementation of the motor drive circuit.

[0070] In Embodiment 2, the motor drive circuit no longer uses a discrete device network composed of multiple transistors and MOSFETs, but instead employs an integrated dedicated stepper driver chip (such as...). Figure 3 (As shown in the dashed box on the right). Figure 3 As shown, the timing output pins of the microcontroller control unit are directly connected to the logic control input pins of the integrated dedicated stepper driver chip. The power output terminals of the integrated dedicated stepper driver chip are directly connected to the windings of each phase of the AC stepper motor. Inside the chip, a preamplifier circuit, an overcurrent protection circuit, and a high-power DMOS transistor power switch matrix are highly integrated.

[0071] The microcontroller outputs a weak timing waveform signal, which is directly fed into the integrated dedicated stepper driver chip. The chip's internal circuitry synchronously amplifies the current and switches the high voltage, thereby driving the AC stepper motor to operate stably. This second embodiment significantly reduces the PCB board area and the number of discrete components, effectively improving the overall hardware reliability and anti-interference capability of the drive system.

[0072] Example 3

[0073] As another technical alternative to improve the anti-interference capability of this invention in harsh industrial environments, this third embodiment improves the architecture of the polarity acquisition voltage conversion circuit. In this third embodiment, the polarity acquisition voltage conversion circuit adopts a high-speed optocoupler isolation circuit architecture.

[0074] After the DC input terminal V+ of the external two-wire DC interface is led out, it is first connected to a current-limiting resistor, and then to the positive input terminal of the LED inside the optocoupler isolator. The negative input terminal of the LED is connected to the other end V-. The collector of the phototransistor inside the optocoupler is connected to the low-voltage power supply VCC of the microcontroller system via a pull-up resistor. The emitter of the phototransistor is grounded, and the collector is also led out as a signal line to the I / O detection pin (P1.0) of the microcontroller control unit.

[0075] When the external control signal is positively connected, the high-voltage DC power drives the LED inside the optocoupler to emit light through the current-limiting resistor. The phototransistor conducts under light, pulling the potential of the I / O detection pin (P1.0) down to 0V (output low level "0"). When the external DC polarity is switched to reverse connection, the LED is reverse-biased and does not emit light. The phototransistor is also turned off, and the I / O detection pin (P1.0) is kept high by the pull-up resistor (output high level "1"). The optocoupler isolation circuit architecture achieves complete electrical isolation between the high-voltage side control signal and the microcontroller's low-voltage system, giving the entire device extremely high anti-interference protection capabilities.

[0076] To clearly quantify and verify the outstanding substantive features and significant technological advancements of the present invention compared to traditional technical solutions, the inventors conducted detailed comparative tests. Under rated load and a standard laboratory environment of 25°C, a conventional brushed DC peristaltic pump and the drive system described in this invention (equipped with the same specification stepper motor and pump head) were compared in various performance indicators. Specific experimental data are recorded in the table below:

[0077] Continuous trouble-free operation time Typically <200 hours ≥200 hours Rated load, 25℃ environment, continuous uninterrupted operation Rate of change of flow rate when voltage fluctuation is ±10% Approximately ±10% ≤±2% 12V / 24V reference power supply, simulating grid fluctuations at the same set speed. Physical interface compatibility — 100% compatible with existing two-wire interfaces Direct and seamless replacement, no cable changes or host program modifications required.

[0078] The experimental comparison data in the table above clearly demonstrates that, while maintaining the strong compatibility advantages of traditional brushed DC peristaltic pumps—"two-wire polarity reversal, plug and play"—this invention increases the continuous fault-free operating life by more than an order of magnitude (completely overcoming the industry pain point of 200 hours for brushed pumps). Furthermore, it exhibits exceptionally excellent flow stability under fluctuating power supply conditions (flow error drastically reduced from ±10% to ≤±2%). These significant advancements cannot be expected through simple conventional circuit superposition, but are achieved through systematic innovation in control methods and the separate design of polarity acquisition and conversion with the stepper drive architecture.

[0079] Example 4

[0080] See Figure 6 This paper demonstrates the workflow of the peristaltic pump driving method with DC polarity commutation of AC stepper motor according to the present invention. The specific control method steps are as follows:

[0081] Step S601: System initialization, power on the microcontroller control unit, configure the input / output mode of the I / O port, and load the pre-stored stepper motor forward and reverse timing table into the memory buffer.

[0082] Step S602: Real-time detection of the output level of the polarity acquisition voltage conversion circuit. The microcontroller reads the potential state of the I / O detection pin (P1.0) at a fixed frequency through internal timer interrupts or the main loop program.

[0083] Step S603: Determine the high / low state of the pin. The microcontroller determines whether the voltage read is greater than the preset logic high-level threshold: if yes (i.e., the level is "1"), it determines that the polarity of the current input from the external host is positive, and the program jumps to step S604; if no (i.e., the level is "0"), it determines that the polarity of the current input from the external host has been switched to reverse, and the program jumps to step S605.

[0084] Step S604: The instruction is identified as a forward rotation control command. The microcontroller calls the forward stepping timing control logic and alternately outputs weak electrical timing pulse signals to the motor drive circuit to control the AC stepping motor and peristaltic pump structure (6) to perform forward precision fluid delivery. Then the program returns to step S602 to continue the loop monitoring.

[0085] Step S605: If the instruction is identified as a reverse control instruction, the microcontroller will immediately switch to call the reverse stepping timing control logic and output pulse signals to the motor drive circuit alternately to drive the AC stepper motor to reverse so as to drive the peristaltic pump structure (6) to perform fluid backflow and cleaning action. Then the program returns to step S602 to continue the loop monitoring.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for driving a peristaltic pump with DC polarity commutation of an AC stepper motor, characterized in that, Includes the following steps: Step S100: Receive DC polarity switching input signal. The DC polarity switching input signal is input through a set of two-wire DC control interfaces and is used as a forward and reverse control command by swapping the positive and negative terminals of the DC voltage. Step S200: The polarity acquisition voltage conversion circuit acquires the positive and negative states of the DC polarity switching input signal, and simultaneously performs voltage division and level clamping protection on the DC polarity switching input signal above 5V, and outputs a standard high or low level within the safety recognition range of the microcontroller. Step S300: The microcontroller's I / O port detects the standard high or low level, uniquely determines the input polarity based on the high or low state of the level, and identifies the corresponding forward or reverse instruction; Step S400: The microcontroller outputs the corresponding stepper motor drive timing signal to the motor drive circuit according to the identified forward or reverse rotation command; Step S500: The motor drive circuit receives the stepper motor drive timing signal and amplifies the power, driving each phase winding of the AC stepper motor powered by DC to operate in a specified timing sequence, thereby driving the peristaltic pump structure to complete the fluid transport or return action.

2. The peristaltic pump driving method with DC polarity commutation of AC stepper motor according to claim 1, characterized in that: In step S200, the buck and level clamping logic used in the polarity acquisition voltage conversion circuit is as follows: When the DC polarity switching input signal is positive, it is stepped down by the voltage divider network in the polarity acquisition voltage conversion circuit and then clamped by the Zener diode to output a first standard level of 1.8V~5V to the I / O port of the microcontroller. When the DC polarity switching input signal is reversed, the polarity acquisition voltage conversion circuit outputs a second standard level of 0V~0.8V to the I / O port of the microcontroller.

3. The peristaltic pump driving method with DC polarity commutation of AC stepper motor according to claim 2, characterized in that: The voltage range of the DC polarity switching input signal is 12V~24V wide voltage input, the first standard level is 2.18V, and the second standard level is 0V.

4. The peristaltic pump driving method with DC polarity commutation of AC stepper motor according to claim 1, characterized in that: In step S500, the motor drive circuit adopts a discrete device drive scheme combining a transistor preamplifier circuit and a MOSFET power switch circuit, or an integrated dedicated stepper drive chip drive scheme, to achieve timing control of the AC stepper motor windings.

5. A peristaltic pump drive system with DC polarity commutation of an AC stepper motor implementing the method of any one of claims 1 to 4, characterized in that, include: A two-wire DC interface is used to receive external DC polarity switching input signals. A polarity acquisition voltage conversion circuit, whose input terminal is electrically connected to the two-wire DC interface, is used to acquire polarity, voltage division and reduction, and level clamping. The microcontroller control unit has its I / O detection port electrically connected to the output terminal of the polarity acquisition voltage conversion circuit, used to identify polarity and output step drive timing signals; the motor drive circuit is electrically connected to the timing output terminal of the microcontroller control unit, used to amplify and output the step drive timing signals; the AC stepper motor is electrically connected to the power output terminal of the motor drive circuit, and operates at a fixed step angle under the drive of the motor drive circuit; the peristaltic pump structure (6) is mechanically connected to the output shaft of the AC stepper motor, and is driven by the AC stepper motor to perform fluid transport.

6. The peristaltic pump drive system with AC stepper motor DC polarity reversal according to claim 5, characterized in that: The polarity acquisition voltage conversion circuit includes a rectifier bridge, a voltage divider resistor network, and a Zener diode level clamping circuit; the DC input terminals V+ and V- of the two-wire DC interface are connected to the input terminals of the rectifier bridge, and the output terminals of the rectifier bridge are connected to a high-voltage step-down processing module; the DC input terminal V+ is also connected to a voltage divider node via the voltage divider resistor network, the voltage divider node is electrically connected to the cathode of the Zener diode D1, the anode of the Zener diode D1 is grounded, and the voltage divider node is also electrically connected to the I / O detection port of the microcontroller control unit.

7. The peristaltic pump drive system with AC stepper motor DC polarity reversal according to claim 6, characterized in that: The voltage divider resistor network includes a first voltage divider resistor R1 and a second voltage divider resistor R2; the DC input terminal V+ is connected to the voltage divider node via the first voltage divider resistor R1, one end of the second voltage divider resistor R2 is connected to the voltage divider node, and the other end is grounded; the resistance of the first voltage divider resistor R1 is 100kΩ, the resistance of the second voltage divider resistor R2 is 10kΩ, and the voltage regulation value of the Zener diode D1 is 5.1V.

8. The peristaltic pump drive system with AC stepper motor DC polarity reversal according to claim 5, characterized in that: The polarity acquisition voltage conversion circuit adopts an optocoupler isolation circuit architecture. The input terminal of the two-wire DC interface is connected to the light-emitting diode side of the optocoupler isolator via a current-limiting resistor. The phototransistor side of the optocoupler is electrically connected to the I / O detection port of the microcontroller control unit to achieve electrical isolation between the input signal and the microcontroller.

9. The peristaltic pump drive system with AC stepper motor DC polarity reversal according to claim 5, characterized in that: The motor drive circuit includes a transistor preamplifier circuit and a MOSFET power switch circuit; the timing output terminal of the microcontroller control unit is connected to the input terminal of the transistor preamplifier circuit, the output terminal of the transistor preamplifier circuit is connected to the gate of the MOSFET power switch circuit, and the drain of the MOSFET power switch circuit is electrically connected to the winding interface of the AC stepper motor.

10. The peristaltic pump drive system with AC stepper motor DC polarity reversal according to claim 5, characterized in that: The peristaltic pump structure (6) includes a housing, a supporting housing, a top housing, a stirring support wheel, a roller, a bearing, an inlet pipe, and an outlet pipe; the AC stepper motor is fixed below the supporting housing, and its output shaft passes through the supporting housing and is connected to the stirring support wheel; the stirring support wheel is equipped with the roller and the bearing, which are used to squeeze the pump pipe that passes through the supporting housing when rotating, and the two ends of the pump pipe are respectively connected to the inlet pipe and the outlet pipe.

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