Submersible pump variable frequency drive circuit, driving method and submersible pump system

Abstract

The application relates to the technical field of submersible pumps, and provides a submersible pump variable-frequency driving circuit, a driving method and a submersible pump system. The submersible pump driving method comprises the following steps: in response to a first current event and a second current event of a power loop of a motor driving circuit, collecting a first trigger time and a second trigger time through a sampling circuit; wherein the first current event is that a current reaches a preset first threshold value, the second current event is that a current reaches a preset second threshold value, the first trigger time is a trigger time of the first current event, and the second trigger time is a trigger time of the second current event; determining a submersible pump driving mode based on the first trigger time and the second trigger time; wherein the submersible pump driving mode is used for controlling a submersible pump. The submersible pump driving method provided by the application can improve the problem that a single fixed operation mode is used to drive a submersible pump in the related art, which may lead to insufficient scene adaptability.

Description

Technical Field

[0001] This application relates to the field of submersible pump technology, and in particular to a submersible pump frequency conversion drive circuit, drive method and submersible pump system. Background Technology

[0002] A submersible pump is a portable, powered device specifically designed for extracting and transporting oily liquids. It uses a built-in electric drive (usually a DC motor) to rotate an impeller, creating negative pressure at the pump inlet. This draws in the oil, pressurizes it, and then discharges it through a hose. Submersible pumps are widely used in outdoor fuel transfer between oil drums, vehicle refueling, emergency fuel extraction, small oil depot management, and refueling of machinery. They are particularly well-suited for mobile applications powered by vehicle batteries and are a key tool in the modern field of miniaturized, portable oil handling.

[0003] However, traditional submersible pump drive methods mostly adopt a single fixed operating mode, which cannot be dynamically adjusted according to working conditions. Even if some equipment is equipped with basic current protection functions, it can only realize simple overcurrent shutdown operations and does not make full use of the time characteristics of current changes for intelligent control, resulting in insufficient adaptability to different scenarios. Summary of the Invention

[0004] This application provides a variable frequency drive circuit, driving method, and submersible pump system for a submersible pump, which can improve the technical problem in related technologies where using a single fixed operating mode to drive the submersible pump may lead to insufficient scenario adaptability.

[0005] In a first aspect, embodiments of this application provide a variable frequency drive circuit for a submersible pump, applied to a submersible pump system. The variable frequency drive circuit includes a motor drive circuit and a control circuit, wherein the motor drive circuit is connected to the control circuit. The variable frequency drive circuit further includes:

[0006] Isolation operational amplifier module U1;

[0007] The sampling circuit is connected to the power circuit of the motor drive circuit and the input terminal of the isolation operational amplifier module U1, respectively. It is used to collect the current of the power circuit of the motor drive circuit, convert the current of the power circuit into a differential voltage signal proportional to the current, and output it to the input terminal of the isolation operational amplifier module U1.

[0008] Two power supply filtering circuits are provided. One of the power supply filtering circuits is connected to the isolation operational amplifier module U1 and the 5V power supply respectively, and is used to absorb electrostatic pulses on the power side power supply line and stabilize the power side power supply voltage. The other power supply filtering circuit is connected to the isolation operational amplifier module U1 and the 3V3 power supply respectively, and is used to absorb electrostatic pulses on the control side power supply line and stabilize the control side power supply voltage.

[0009] A differential-to-single-ended circuit, connected to the output of the isolated operational amplifier module U1, is used to convert the differential signal output by the isolated operational amplifier module U1 into a single-ended signal; and

[0010] The filtering and protection circuit is connected to the input terminals of the differential-to-single-ended circuit and the control circuit, respectively. It is used to receive the single-ended signal output by the differential-to-single-ended circuit, filter out high-frequency noise of the single-ended signal, absorb electrostatic pulses, and output it to the ADC interface of the control circuit.

[0011] The technical solutions described in this application embodiment have at least the following technical effects:

[0012] The submersible pump frequency converter drive circuit provided in this application embodiment acquires the operating current of the power circuit of the motor drive circuit through a sampling circuit and converts it into a differential voltage signal proportional to the current, which is then output to the input terminal of the isolation operational amplifier module U1. The isolation operational amplifier module U1 performs electrical isolation between the power side and the control side, and simultaneously transmits the input differential voltage signal stably to the output terminal. Two power supply filter circuits respectively serve the power supply of the isolation operational amplifier module U1—one is connected to the 5V power supply and the isolation operational amplifier module U1, responsible for absorbing electrostatic pulses on the power side power line and stabilizing the power side power supply voltage, and the other is connected to the 3V power supply. The power supply and isolation operational amplifier module U1 absorbs electrostatic pulses and stabilizes the power supply voltage on the control side, ensuring the reliable operation of the isolation operational amplifier module U1. The differential-to-single-ended circuit connects to the output of the isolation operational amplifier module U1, converting its output differential signal into a single-ended signal suitable for subsequent circuits. The filter protection circuit connects the differential-to-single-ended circuit to the input of the control circuit, receives the single-ended signal, filters out high-frequency noise and absorbs electrostatic pulses, and finally outputs the processed clean signal to the ADC interface of the control circuit, providing a reliable signal foundation for subsequent current monitoring, fault protection and motor speed control.

[0013] Secondly, embodiments of this application provide a submersible pump driving method, applied to the submersible pump frequency conversion drive circuit described in the first aspect, the method comprising:

[0014] In response to a first current event and a second current event in the power loop of the motor drive circuit, a first trigger time and a second trigger time are acquired by a sampling circuit; the first current event is when the current reaches a preset first threshold, the second current event is when the current reaches a preset second threshold, the first trigger time is the trigger time of the first current event, and the second trigger time is the trigger time of the second current event.

[0015] The submersible pump drive mode is determined based on the first trigger time and the second trigger time; wherein, the submersible pump drive mode is used to control the submersible pump.

[0016] The technical solutions described in this application embodiment have at least the following technical effects:

[0017] In response to a first current event and a second current event triggered in the power output circuit of the submersible pump motor drive circuit, a sampling circuit collects the first trigger time corresponding to the first current event and the second trigger time corresponding to the second current event, respectively. The first current event refers to the current in the power output circuit reaching a preset first threshold (including triggering by a rising edge when the current rises from below the preset first threshold to the threshold, or by a falling edge when the current falls from above the preset first threshold to the threshold). The second current event refers to the current in the power output circuit reaching a preset second threshold (including triggering by a rising edge when the current rises from below the preset second threshold to the threshold, or by a falling edge when the current falls from above the preset second threshold to the threshold). The preset first threshold and preset second threshold are different current quantification standards pre-calibrated based on the submersible pump's operating conditions. Further, based on the timing relationship (sequential order) and time interval parameters of the first and second trigger times, a submersible pump drive mode adapted to the current operating conditions is determined through preset logic judgment rules. The submersible pump drive mode is used to dynamically adjust the submersible pump's operating parameters (such as speed and output power) to achieve precise drive, energy-saving operation, or safety protection in different scenarios, adapting to the multi-condition application requirements of the submersible pump.

[0018] Thirdly, embodiments of this application provide a submersible pump system, the submersible pump system comprising:

[0019] Submersible pumps; and

[0020] The submersible pump frequency conversion drive circuit described in the first aspect is used to implement the submersible pump drive method described in the second aspect. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the submersible pump frequency converter drive circuit provided in the embodiments of this application;

[0023] Figure 2 A schematic flowchart of the submersible pump driving method provided in the embodiments of this application;

[0024] Figure 3 A schematic flowchart of step S200 in the submersible pump driving method provided in the embodiments of this application;

[0025] Figure 4 This is a schematic diagram of the submersible pump drive system provided in an embodiment of this application.

[0026] The following are the labeling elements in the figure:

[0027] 100. Submersible pump frequency converter drive circuit; 10. Sampling circuit; 20. Power supply filter circuit; 30. Differential to single-ended circuit; 40. Filter protection circuit. Detailed Implementation

[0028] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0030] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0031] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0033] In this application, "and / or" is merely a way of describing the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0034] It should be noted that in this application, the words "in some embodiments," "exemplarily," and "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "in some embodiments," "exemplarily," or "for example" should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of words such as "in some embodiments," "exemplarily," and "for example" is intended to present related concepts in a specific manner, meaning that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of this application. The appearance of the above words in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0035] A submersible pump is a portable, powered device specifically designed for extracting and transporting oily liquids. It uses a built-in electric drive (usually a DC motor) to rotate an impeller, creating negative pressure at the pump inlet. This draws in the oil, pressurizes it, and then discharges it through a hose. Submersible pumps are widely used in outdoor fuel transfer between oil drums, vehicle refueling, emergency fuel extraction, small oil depot management, and refueling of machinery. They are particularly well-suited for mobile applications powered by vehicle batteries and are a key tool in the modern field of miniaturized, portable oil handling.

[0036] However, traditional submersible pump drive methods mostly adopt a single fixed operating mode, which cannot be dynamically adjusted according to working conditions. Even if some equipment is equipped with basic current protection functions, it can only realize simple overcurrent shutdown operations and does not make full use of the time characteristics of current changes for intelligent control, resulting in insufficient adaptability to different scenarios.

[0037] Based on this, in order to improve the technical problem that the use of a single fixed operating mode to drive the submersible pump may lead to insufficient scenario adaptability in the related technology, the embodiments of this application provide the following solution.

[0038] Please see Figure 1This application provides a submersible pump frequency converter drive circuit 100, applied to a submersible pump system. The submersible pump frequency converter drive circuit 100 includes a motor drive circuit and a control circuit. The submersible pump frequency converter drive circuit 100 includes an isolation operational amplifier module U1, a sampling circuit 10, two power supply filter circuits 20, a differential to single-ended circuit 30, and a filter protection circuit 40, wherein:

[0039] The sampling circuit 10 is connected to the power circuit of the motor drive circuit and the input terminal of the isolation operational amplifier module U1, respectively. It is used to collect the current of the power circuit of the motor drive circuit, convert the current of the power circuit into a differential voltage signal proportional to the current, and then output it to the input terminal of the isolation operational amplifier module U1.

[0040] One of the power filter circuits 20 is connected to the isolation operational amplifier module U1 and the 5V power supply respectively, and is used to absorb electrostatic pulses on the power side power supply line and stabilize the power side power supply voltage. The other power filter circuit 20 is connected to the isolation operational amplifier module U1 and the 3V3 power supply respectively, and is used to absorb electrostatic pulses on the control side power supply line and stabilize the control side power supply voltage.

[0041] The differential-to-single-ended circuit 30 is connected to the output terminal of the isolation operational amplifier module U1 and is used to convert the differential signal output by the isolation operational amplifier module U1 into a single-ended signal.

[0042] The filter protection circuit 40 is connected to the input terminals of the differential-to-single-ended circuit 30 and the control circuit, respectively. It is used to receive the single-ended signal output by the differential-to-single-ended circuit 30, filter out the high-frequency noise of the single-ended signal, absorb electrostatic pulses, and output it to the ADC interface of the control circuit.

[0043] It is understood that the control circuit is a control chip with ADC and PWM functions. For example, the control circuit may include an STM32F103 MCU, an STM8S MCU, or a TMS320F28035 DSP, but is not limited to these. The control circuit may also include peripheral auxiliary circuits, such as power conversion circuits, clock and reset circuits, communication interface circuits, and drive interface circuits, but is not limited to these.

[0044] A motor drive circuit is a circuit that receives PWM (Pulse Width Modulation) control signals from a control circuit and converts the input DC power (or rectified DC power) into a drive current with adjustable frequency and voltage to drive the submersible pump motor to operate at a controlled speed. For example, a motor drive circuit can be an H-bridge circuit, a three-phase inverter bridge circuit, etc., but is not limited to these.

[0045] The isolated op-amp module U1 is an operational amplifier that integrates electrical isolation. Its key difference from a regular op-amp is that the input (power) and output (control) sides of the isolated op-amp module U1 have no direct electrical connection. Signal transmission is achieved through magnetic or optical coupling, effectively blocking current conduction on both sides and transmitting only voltage signals. For example, the isolated op-amp module U1 can be modeled as AMC1200 or ADUM3180, but is not limited to these. The amplification factor of the isolated op-amp module U1 can be 1x, 2x, 4x, 8x, etc., with 8x being the preferred factor. Because submersible pumps often operate in humid and oily environments, if leakage occurs on the power side (motor drive circuit), the isolation operational amplifier can block the conduction path of the leakage current to the control side (such as MCU, operation panel), preventing electric shock to operators. At the same time, it prevents large currents and high voltages from the power side from entering the control side and damaging weak electrical components such as ADC and MCU. Furthermore, the IGBTs in the motor drive circuit generate a large amount of electromagnetic interference when switching at high frequency. This interference will attach to the sampling signal. The isolation structure of the isolation operational amplifier module U1 can effectively filter out common-mode interference and differential-mode interference on the power side, preventing interference signals from entering the control side and affecting the accuracy of functions such as drive mode judgment and overcurrent protection, ensuring stable operation of the circuit in complex electromagnetic environments.

[0046] The sampling circuit 10 is used to convert the real-time changing current signal in the power circuit into a voltage difference that is proportional to the current magnitude, and to filter out high-frequency noise such as electromagnetic interference and power fluctuations generated by the IGBT high-frequency switching in the motor drive circuit, thereby purifying the sampled voltage signal and providing a basic electrical signal for subsequent signal processing.

[0047] Two power supply filter circuits 20 provide power supply guarantees for the power side and control side of the isolated operational amplifier module U1, respectively. Each power supply filter circuit 20 includes a power supply decoupling capacitor, which is connected in parallel between the corresponding power supply (5V power side power supply, 3V3 control side power supply) and ground (power ground GND1, control ground GND2). It can filter out high-frequency ripple and noise on the power line (such as power grid fluctuations, interference generated by high-frequency switching of other devices), provide a clean and stable voltage input to the power supply pins of the isolated operational amplifier module U1, avoid power supply noise coupling into the sampling signal, and ensure the amplification accuracy of the isolated operational amplifier module U1 for differential voltage signals.

[0048] The isolated operational amplifier module U1 outputs a symmetrical differential voltage signal. However, the ADC of the control circuit is usually a single-ended input structure and cannot directly receive differential signals. Therefore, the differential-to-single-ended circuit 30 converts the differential signal with dual-ended input and dual-ended output into a single-ended output voltage signal, thereby completing the signal format adaptation and providing a signal source that meets the input requirements for the ADC's analog-to-digital conversion.

[0049] The filter protection circuit 40 connects the differential-to-single-ended amplifier circuit and the ADC interface of the control circuit. It is used to filter out the high-frequency interference remaining in the single-ended signal output by the differential-to-single-ended amplifier circuit, limit the instantaneous maximum current flowing into the ADC input pin, and play the role of noise reduction, purification and interface protection.

[0050] As can be seen from the above, the submersible pump frequency converter drive circuit 100 provided in this application embodiment collects the operating current of the power circuit of the motor drive circuit through the sampling circuit 10 and converts it into a differential voltage signal proportional to the current, which is then output to the input terminal of the isolation operational amplifier module U1. The isolation operational amplifier module U1 undertakes the electrical isolation function between the power side and the control side, and at the same time stably transmits the input differential voltage signal to the output terminal. The two power supply filter circuits 20 respectively serve the power supply of the isolation operational amplifier module U1—one of which is connected to the 5V power supply and the isolation operational amplifier module U1, responsible for absorbing electrostatic pulses on the power side power line and stabilizing the power side power supply voltage, and the other is connected to the power supply of the isolation operational amplifier module U1. A 3V3 power supply is connected to the isolated operational amplifier module U1 to absorb electrostatic pulses and stabilize the power supply voltage on the control side, ensuring the reliable operation of the isolated operational amplifier module U1. The differential-to-single-ended circuit 30 is connected to the output of the isolated operational amplifier module U1, converting its output differential signal into a single-ended signal suitable for subsequent circuits. The filter protection circuit 40 is connected to the differential-to-single-ended circuit 30 and the input of the control circuit. After receiving the single-ended signal, it filters out high-frequency noise and absorbs electrostatic pulses, and finally outputs the processed clean signal to the ADC interface of the control circuit, providing a reliable signal foundation for subsequent current monitoring, fault protection, and motor speed control.

[0051] In some embodiments, please refer to Figure 1 Pin 4 of the isolation operational amplifier module U1 is connected to power ground, and pin 5 of the isolation operational amplifier module U1 is connected to control ground. The sampling circuit 10 includes resistors R1, R2, and R3, and capacitors C1, C2, and C3, wherein:

[0052] Resistor R1 is connected in series in the power circuit of the motor drive circuit. One end of resistor R1 is connected to the power circuit of the motor drive circuit, and the other end is connected to the power ground. Resistor R1 is used to generate a voltage difference proportional to the current when current flows through it.

[0053] One end of resistor R2 is connected to the common node of resistor R1 and the power loop of the motor drive circuit, and the other end is connected to pin 2 of the isolation operational amplifier module U1.

[0054] One end of resistor R3 is connected to the common node of resistor R1 and power ground, and the other end is connected to pin 3 of the isolation operational amplifier module U1.

[0055] One end of capacitor C1 is connected to the common node of resistor R2 and isolation operational amplifier module U1, and the other end is connected to the common node of resistor R3 and isolation operational amplifier module U1.

[0056] One end of capacitor C2 is connected to the common node of resistor R3 and isolation operational amplifier module U1, and the other end is connected to the common node of isolation operational amplifier module U1 and power ground.

[0057] One end of capacitor C3 is connected to the common node of resistor R2 and isolation operational amplifier module U1, and the other end is connected to the common node of isolation operational amplifier module U1 and power ground.

[0058] Among them, the two ends of capacitor C1 are connected to pins 2 and 3 of the isolation operational amplifier module U1, respectively. Capacitors C2 and C3 are both connected to power ground. Resistors R1, R2, R3, C1, C2, and C3 form a differential filter network to filter out high-frequency noise in the sampled signal and match the input impedance of the isolation operational amplifier module U1 to avoid signal reflection.

[0059] It can be understood that resistor R1, as a current-to-voltage conversion element, is connected in series in the power loop of the motor drive circuit. It uses Ohm's law to convert the real-time changing loop current into a voltage difference proportional to the current magnitude, providing the basic electrical signal for subsequent signal processing. For example, resistor R1 can be a sampling resistor, a power precision resistor, etc., but is not limited to these.

[0060] Resistors R2 and R3 form a symmetrical differential signal transmission path, connecting the two ends of sampling resistor R1 to the differential input terminals (pins 2 and 3) of the isolation operational amplifier module U1, respectively. This converts the voltage difference across resistor R1 into a differential input signal recognizable by the isolation operational amplifier module U1, matching its input impedance, reducing signal reflection and attenuation during transmission, avoiding signal distortion caused by impedance mismatch, and ensuring the stability of differential signal transmission. For example, resistors R2 and R3 can be impedance matching resistors, balancing resistors, etc., but are not limited to these.

[0061] Capacitor C1 is connected across the two differential input terminals (pins 2 and 3) of the isolated operational amplifier module U1, forming a differential filter structure. This structure specifically filters out high-frequency differential-mode interference in the differential signal (such as electromagnetic interference generated by the high-frequency switching of IGBTs in motor drive circuits), suppresses common-mode noise components in the differential signal, and further purifies the differential input signal, ensuring the accurate identification of voltage differences by the isolated operational amplifier module U1. For example, capacitor C1 can be a differential coupling capacitor, a high-frequency filter capacitor, etc., but is not limited to these.

[0062] Capacitors C2 and C3 are used to filter out high-frequency noise and power supply ripple coupling noise in the sampled signal, stabilize the potential at the input terminal of the isolation operational amplifier module U1, and work together with resistors R2 and R3 to form a differential filter network to filter out wide-band high-frequency noise and provide a high signal-to-noise ratio input signal for the isolation operational amplifier.

[0063] With this configuration, the sampling circuit 10 converts the power circuit current into a voltage difference proportional to the current by connecting resistor R1 in series in the power loop of the motor drive circuit. Then, resistors R2 and R3 are connected to pins 2 and 3 of the isolation operational amplifier module U1 to construct a differential signal transmission path. In conjunction with capacitor C1 connected across the two input terminals of the isolation operational amplifier module U1 and capacitors C2 and C3 connected to the two input terminals of the isolation operational amplifier module U1 and the power ground, a differential filter network is formed. This network filters out high-frequency noise in the sampling signal, matches the input impedance of the isolation operational amplifier module U1 to avoid signal reflection, and achieves electrical isolation between the power side and the control side by using the dual ground connection of pin 4 of the isolation operational amplifier module U1 to the power ground and pin 5 to the control ground. Finally, it provides a precise and stable differential input signal for the differential-to-single-ended circuit 30.

[0064] In some embodiments, please refer to Figure 1 Pin 1 of the isolation operational amplifier module U1 is connected to a 5V power supply, and pin 8 of the isolation operational amplifier module U1 is connected to a 3V3 power supply. The power supply filter circuit 20 includes a power supply decoupling capacitor and an ESD protection diode, wherein:

[0065] One end of the ESD protection diode is connected to a 5V or 3V3 power supply, and the other end is connected to power ground or control ground. It is used to absorb electrostatic pulses on the power side or control side power lines to prevent electrostatic damage to the power side or control side circuits.

[0066] One end of the power supply decoupling capacitor is connected to the 5V or 3V3 power supply, and the other end is connected to the power ground or control ground. It is used to filter out high-frequency noise from the 5V or 3V3 power supply, stabilize the power side or control side power supply voltage, and ensure the purity of the input power supply of the isolation operational amplifier.

[0067] It is understandable that an ESD protection diode, with one end connected in parallel between the 5V power supply or the 3V control supply and its corresponding ground (power ground / control ground), can quickly respond to electrostatic pulse impacts on the power line. Through instantaneous conduction, it discharges the electrostatic charge to ground, preventing high-voltage electrostatic discharge from damaging the isolation operational amplifier module U1 and other circuit components on the power and control sides, thus improving the circuit's anti-electrostatic interference capability and reliability. For example, the ESD protection diode can be a transient voltage suppressor diode (TVS diode), a dedicated electrostatic discharge protection diode, etc., but is not limited to these.

[0068] One end of the power decoupling capacitor is connected in parallel between the 5V power supply or the 3V3 control supply and the corresponding ground (power ground / control ground). This filters out high-frequency ripple and electromagnetic interference noise on the power line, suppresses instantaneous fluctuations in the power supply voltage, stabilizes the power and control supply voltages, and provides a clean operating power supply to pins 1 (5V supply) and 8 (3V3 supply) of the isolation operational amplifier module U1. This prevents power supply noise from coupling into the sampling signal and affecting the signal transmission accuracy of the isolation operational amplifier. For example, the power decoupling capacitor can be a multilayer ceramic capacitor (MLCC), a tantalum capacitor, etc., but is not limited to these.

[0069] With this configuration, pin 1 of the isolated operational amplifier module U1 is connected to a 5V power supply, and pin 8 is connected to a 3V3 power supply to obtain operating power for the power and control sides. The power filter circuit 20, composed of ESD protection diodes and power decoupling capacitors, connects these two types of components in parallel between the 5V / 3V3 power supply and the power / control ground, respectively. On the one hand, the ESD protection diodes absorb electrostatic pulses on the power lines to prevent electrostatic damage to the power and control side circuits. On the other hand, the power decoupling capacitors filter out high-frequency noise in the power supply and stabilize the supply voltage, providing a clean and stable operating power supply for the isolated operational amplifier module U1 and ensuring signal isolation and transmission functions.

[0070] In some embodiments, please refer to Figure 1 The differential-to-single-ended circuit 30 includes: resistors R4, R5, R6, and R7, and operational amplifier module U2, wherein:

[0071] Pin 3 of op-amp module U2 is connected to pin 7 of isolation op-amp module U1, and resistor R6 is connected in series between pin 3 of op-amp module U2 and pin 7 of isolation op-amp module U1; pin 2 of op-amp module U2 is connected to pin 6 of isolation op-amp module U1, and resistor R4 is connected in series between pin 2 of op-amp module U2 and pin 6 of isolation op-amp module U1; resistors R4 and R6 are used to provide symmetrical input impedance to ensure balanced transmission of differential signals.

[0072] One end of resistor R5 is connected to pin 1 of op-amp module U2, and the other end is connected to pin 2 of op-amp module U2. Resistor R5 is used in conjunction with resistors R4 and R6 to set the gain of op-amp module U2.

[0073] One end of resistor R7 is connected to pin 3 of op-amp module U2, and the other end is connected to a 1V24 reference voltage. Resistor R7 is used to provide a common-mode voltage reference for op-amp module U2 to ensure that op-amp module U2 operates within a suitable linear range.

[0074] Pin 1 of operational amplifier module U2 is connected to filter protection circuit 40, pin 8 of operational amplifier module U2 is connected to 3V3 power supply, and pin 4 of operational amplifier module U2 is connected to control ground. Operational amplifier module U2 is used to convert the differential signal output by isolation operational amplifier module U1 into a single-ended signal and then output it to filter protection circuit 40 through pin 1.

[0075] It can be understood that resistors R4 and R6 are symmetrically connected in series between the output of the isolation operational amplifier module U1 and the differential input of the operational amplifier module U2. This provides a symmetrical input impedance for differential signal transmission, matching the output impedance of the isolation operational amplifier module U1 with the input impedance of the operational amplifier module U2. This ensures balanced transmission of the differential signal, reduces reflection and attenuation during signal transmission, and avoids signal distortion caused by impedance mismatch. For example, resistors R4 and R6 can be impedance matching resistors, differential balancing resistors, etc., but are not limited to these.

[0076] One end of resistor R5 is connected to the output terminal (pin 1) of operational amplifier module U2, and the other end is connected to the inverting input terminal (pin 2) of operational amplifier module U2, forming a negative feedback loop for the operational amplifier. By matching the resistance values ​​of resistors R4 and R6, the voltage amplification gain of operational amplifier module U2 is set, amplifying the differential signal output from isolation operational amplifier module U1 to the voltage range suitable for the subsequent filter protection circuit 40 and the ADC interface, while ensuring the linearity of signal amplification. For example, resistor R5 can be a negative feedback resistor, a gain adjustment resistor, etc., but is not limited to these.

[0077] One end of resistor R7 is connected to the non-inverting input (pin 3) of operational amplifier module U2, and the other end is connected to a 1V24 reference voltage. This provides a stable DC common-mode bias voltage for operational amplifier module U2, ensuring that operational amplifier module U2 operates in its optimal linear amplification range, effectively suppressing common-mode interference in differential signals, avoiding signal distortion due to common-mode voltage drift, and improving the signal-to-noise ratio of signal transmission. For example, resistor R7 can be a bias resistor, a common-mode voltage setting resistor, etc., but is not limited to these.

[0078] Operational amplifier module U2, as the core component of the differential-to-single-ended circuit 30, receives the output signal from isolation operational amplifier module U1 transmitted via resistors R4 and R6 at its differential input terminal. Utilizing its own amplification characteristics and the feedback and biasing effect of the external resistors, it converts the differential signal from a dual-ended input into a single-ended output voltage signal, which is then output to the filter protection circuit 40 via pin 1, achieving format adaptation between the differential signal and the single-ended input device. For example, operational amplifier module U2 can be a general-purpose operational amplifier, a dedicated differential-to-single-ended operational amplifier, etc., but is not limited to these.

[0079] With this configuration, the differential-to-single-ended circuit 30 provides symmetrical input impedance to the operational amplifier module U2 through resistors R4 and R6 to ensure balanced transmission of the differential signal. The amplification gain of the operational amplifier module U2 is set by the ratio of resistor R5 to resistors R4 and R6. The 1V24 reference voltage connected to resistor R7 provides a stable common-mode bias for the operational amplifier module U2. Finally, the operational amplifier module U2 converts the differential signal output from the isolation operational amplifier module U1 into a single-ended signal that is compatible with the subsequent circuit and outputs it to the filter protection circuit 40, providing a signal source that meets the input requirements for the ADC acquisition of the subsequent control circuit.

[0080] In some embodiments, please refer to Figure 1 The filter protection circuit 40 includes: resistor R8, capacitor C5, capacitor C6, and diode D3, wherein:

[0081] One end of resistor R8 is connected to the output of differential-to-single-ended circuit 30, and the other end is connected to the ADC input of the control circuit. Resistor R8 is used to limit the input current of the ADC interface of the control circuit.

[0082] One end of capacitor C5 is connected to the 3V3 power supply, and the other end is connected to the control ground. Capacitor C5 is used to filter out high-frequency noise from the 3V3 power supply and stabilize the power supply voltage on the control side.

[0083] One end of capacitor C6 is connected to the common node of resistor R8 and the ADC interface of the control circuit, and the other end is connected to control ground. Capacitor C6 is used to filter out high-frequency noise in the single-ended signal output by the differential-to-single-ended circuit 30.

[0084] One end of diode D3 is connected to the ADC input terminal of the control circuit, and the other end is connected to control ground. Diode D3 is used to absorb electrostatic pulses at the ADC input terminal of the control circuit.

[0085] It is understandable that resistor R8 is connected in series between the output of the differential-to-single-ended circuit 30 and the input of the ADC in the control circuit. Its impedance limits the instantaneous maximum current flowing into the ADC input pin, preventing large currents caused by sudden signal changes or electrostatic discharges from entering the ADC and thus avoiding damage or burnout of the ADC input stage chip. This provides hardware protection for the ADC interface. For example, resistor R8 can be a current-limiting resistor, a precision surface-mount resistor, etc., but is not limited to these.

[0086] Capacitor C5 is connected in parallel between the 3V3 power supply and control ground. It can quickly filter out high-frequency ripple and electromagnetic interference noise on the 3V3 power supply line, suppress instantaneous fluctuations in the power supply voltage, stabilize the power supply voltage on the control side, prevent power supply noise from coupling to the subsequent signal link, and ensure the stable operation of the control circuit and ADC. For example, capacitor C5 can be a signal filter capacitor, a low-pass filter capacitor, etc., but is not limited to these.

[0087] One end of capacitor C6 is connected to the common node of resistor R8 and the ADC input, and the other end is grounded, forming a low-pass filter network to ground. This filters out residual high-frequency interference (such as op-amp switching noise and motor electromagnetic radiation interference) in the single-ended output signal of the differential-to-single-ended circuit 30, making the input signal to the ADC smoother and improving the accuracy of current sampling. For example, capacitor C6 can be a signal filter capacitor, a low-pass filter capacitor, etc., but is not limited to these.

[0088] Diode D3 is connected in parallel between the ADC input and control ground. It can quickly respond to and absorb externally introduced electrostatic pulses or transient voltage spikes. When there is electrostatic charge at the ADC interface, the diode conducts instantaneously to discharge the charge to ground, preventing electrostatic discharge from damaging the ADC input pin and enhancing the circuit's anti-interference capability and reliability in environments with high electrostatic discharge and humidity. For example, diode D3 can be an ESD protection diode, a transient voltage suppressor diode (TVS diode), etc., but is not limited to these.

[0089] With this configuration, the filter protection circuit 40 limits the input current of the ADC interface of the control circuit through the series resistor R8, stabilizes the control side power supply voltage using the capacitor C5 connected in parallel between the 3V3 power supply and the control ground, filters out high-frequency noise of the single-ended signal using the capacitor C6 connected between the ADC input node and the control ground, and absorbs electrostatic pulses using the diode D3 connected in parallel between the ADC input terminal and the control ground. Ultimately, it provides a stable, clean and safe input signal for the ADC of the control circuit, ensuring the accurate realization of the current sampling and drive mode judgment functions.

[0090] Please see Figure 2 This application also provides a submersible pump driving method, applied to the submersible pump frequency converter drive circuit 100 of any of the above embodiments. The submersible pump driving method includes:

[0091] In response to a first current event and a second current event in the power loop of the motor drive circuit, a first trigger time and a second trigger time are acquired by a sampling circuit; the first current event is when the current reaches a preset first threshold, the second current event is when the current reaches a preset second threshold, the first trigger time is the trigger time of the first current event, and the second trigger time is the trigger time of the second current event.

[0092] The submersible pump drive mode is determined based on the first trigger time and the second trigger time; wherein, the submersible pump drive mode is used to control the submersible pump.

[0093] As can be seen from the above, the submersible pump driving method provided in this application responds to a first current event and a second current event triggered in the power output circuit of the submersible pump motor drive circuit. A sampling circuit collects the first trigger time corresponding to the first current event and the second trigger time corresponding to the second current event, respectively. The first current event refers to the current in the power output circuit reaching a preset first threshold (including triggering when the current rises from below the preset first threshold to the threshold via a rising edge, or triggering when the current falls from above the preset first threshold to the threshold via a falling edge). The second current event refers to the current in the power output circuit reaching a preset second threshold (including triggering when the current rises from below the preset first threshold to the threshold via a falling edge). The second threshold is triggered by the rising edge of the threshold or by the falling edge of the threshold. The preset first threshold and the preset second threshold are different current quantization standards pre-calibrated based on the operating conditions of the submersible pump. Further, based on the timing relationship (order) between the first trigger time and the second trigger time and the time interval parameter, the submersible pump drive mode adapted to the current operating conditions is determined by the preset logic judgment rules. The submersible pump drive mode is used to dynamically adjust the operating parameters of the submersible pump (such as speed, output power, etc.) to achieve precise drive, energy-saving operation or safety protection in different scenarios, and adapt to the multi-condition application requirements of the submersible pump.

[0094] To better understand the submersible pump driving method provided in the embodiments of this application, the specific implementation process of the submersible pump driving method provided in the embodiments of this application will be described by way of example below.

[0095] Figure 2 A schematic flowchart of a submersible pump driving method provided in an embodiment of this application is shown. The submersible pump driving method includes:

[0096] S100, in response to a first current event and a second current event in the power loop of the motor drive circuit, a first trigger time and a second trigger time are acquired through a sampling circuit; the first current event is when the current reaches a preset first threshold, the second current event is when the current reaches a preset second threshold, the first trigger time is the trigger time of the first current event, and the second trigger time is the trigger time of the second current event.

[0097] It is understood that the preset first threshold corresponds to the light-load / no-load current after the motor starts, used to determine whether the motor has entered an effective operating state. For example, the preset first threshold can be 5A, 6A, or can be set by the user based on the rated current and overload current, etc., but is not limited to these. The preset second threshold corresponds to the rated load current of the motor or the critical current close to overload, used to determine whether the motor has entered a high-load operating state. For example, the preset second threshold can be 9A, 10A, or can be set by the user based on the rated current and overload current, etc., but is not limited to these. The preset first threshold is less than the preset second threshold. The method of acquiring the first trigger time and the second trigger time can be the current timestamp read by the internal timer of the MCU with an ADC interface, etc., but is not limited to these. The sampling circuit can include sampling circuit 10, differential to single-ended circuit 30 and filter protection circuit 40, or it can be sampling circuit 10, etc., but is not limited to these.

[0098] In response to a first current event and a second current event triggered in the power output circuit of the submersible pump motor drive circuit, a sampling circuit collects the first trigger time corresponding to the first current event and the second trigger time corresponding to the second current event, respectively. The first current event refers to the current in the power output circuit reaching a preset first threshold (including triggering by a rising edge when the current rises from below the preset first threshold to the threshold, or triggering by a falling edge when the current falls from above the preset first threshold to the threshold), and the second current event refers to the current in the power output circuit reaching a preset second threshold (including triggering by a rising edge when the current rises from below the preset second threshold to the threshold, or triggering by a falling edge when the current falls from above the preset second threshold to the threshold). These events provide a basis for subsequent steps.

[0099] S200, the submersible pump drive mode is determined based on the first trigger time and the second trigger time; wherein, the submersible pump drive mode is used to control the submersible pump.

[0100] It is understandable that the method of determining the submersible pump drive mode based on the first trigger time and the second trigger time can be based on the first current event (including rising edge or falling edge trigger) and the second current event (including rising edge or falling edge trigger) triggered by the current in the power circuit of the submersible pump motor drive circuit reaching the preset first threshold and the preset second threshold. After obtaining the corresponding first trigger time and second trigger time through the sampling circuit, the timing relationship between the two (the first trigger time is earlier or later than the second trigger time) and the time interval quantization value are the core judgment dimensions. Combined with the dual conditions of whether the time interval is less than the preset threshold and whether the time interval is within the preset range, according to the preset logic rules, the submersible pump drive mode is corresponding to different application scenarios to realize the working condition adaptive drive control based on the current timing characteristics. Alternatively, the first trigger time and the second trigger time can be sent to the user and the user can determine the submersible pump drive mode, etc., but it is not limited to these.

[0101] Based on the dual parameters of the first trigger time and the second trigger time (including their timing relationship and time interval), and combined with preset logical judgment rules, a submersible pump drive mode suitable for the current operating conditions is determined. The submersible pump drive mode dynamically adjusts the operating parameters of the submersible pump (such as motor speed, output power, operating frequency, etc.) to achieve precise drive, energy-saving operation, or safety protection functions in different scenarios. It adapts to various application requirements such as large-volume rapid oil pumping, small-volume quantitative transfer, low-power energy saving, and anti-dry-burning protection, ensuring the adaptability and operational reliability of the submersible pump under different environmental conditions.

[0102] In one possible implementation, please refer to Figure 3 S100, in response to a first current event and a second current event in the power loop of the motor drive circuit, the sampling circuit acquires the first trigger time and the second trigger time, including:

[0103] S110a, in response to the current in the power circuit of the motor drive circuit increasing from below the preset first threshold to the preset first threshold, the sampling circuit collects this moment as the first trigger time.

[0104] It can be understood that the current in the power circuit of the motor drive circuit rises from below the preset first threshold to the preset first threshold as the current rising edge trigger. The emphasis is on the instant the current crosses the preset first threshold, reflecting the motor's transition from a standby / no-load low-current state to a light-load effective operating state (when the submersible pump is not started, the current in the power circuit of the motor drive circuit is close to 0 (or only has a small leakage current in the control circuit), far below the preset first threshold; when the current rises to the preset first threshold, it indicates that the motor has successfully been energized and is running, overcoming the static friction of the rotor and the starting resistance of the pump body, switching from a static standby state to a mechanical rotation state, which is the judgment signal for normal motor startup). Defining the instant the current crosses the preset first threshold as the first trigger time provides a precise current rising edge trigger timing reference for the subsequent timing determination of the submersible pump drive mode.

[0105] S120a, in response to the current in the power circuit of the motor drive circuit rising from below the preset second threshold to the preset second threshold, the sampling circuit collects this moment as the second trigger time.

[0106] It can be understood that the current in the power circuit of the motor drive circuit rises from below the preset second threshold to the preset second threshold, which is the current rising edge trigger. The second trigger time is the instant when the current in the power circuit of the motor drive circuit rises from a state that is continuously below the preset second threshold to equal the preset second threshold. This reflects that the motor has entered a stable high-load operation state from a light-load state. (After the submersible pump starts, the current first rises to the first threshold (light load, the pump body initially pumps oil). As the oil pressure in the pipeline stabilizes and the flow rate reaches the rated value, the motor load continues to increase, and the current rises to the second threshold. At this time, the motor has left the light-load starting stage and entered a stable state of full-load oil pumping. Or, if viscous oil such as machine oil is being pumped, or if there is a slight blockage in the pipeline, the pump body's resistance will increase, and the motor needs to output higher power to maintain the oil pumping flow. The current will rise rapidly from the first threshold to the second threshold, reflecting that the motor is overcoming a high-resistance load.)

[0107] Defining the moment when the current crosses the preset second threshold as the second trigger time can provide an accurate current rising edge trigger timing reference for the timing determination of the subsequent submersible pump drive mode.

[0108] In one possible implementation, please refer to Figure 3 S200, determining the submersible pump drive mode based on the first trigger time and the second trigger time, including:

[0109] S210a, if the time interval between the first trigger time and the second trigger time is less than the preset time interval, the submersible pump drive mode is confirmed as the first drive mode; wherein, the first drive mode is a rapid oil pumping mode, which is suitable for rapid transfer of large-capacity oil tanks.

[0110] It is understandable that the preset time interval is used to determine the speed at which the motor transitions from light load operation (reaching the first threshold) to high load operation (reaching the second threshold). The shorter the preset time interval, the faster the load increases. For example, the preset time interval could be 500ms, 1s, etc., or it could be a value defined by the user based on the submersible pump power specifications and oil conditions, but it is not limited to these. If the time interval between the first trigger time and the second trigger time is less than the preset time interval, it indicates that the load increases rapidly (no blockage in the pipeline and good oil flow). The submersible pump drive mode is then confirmed as the first drive mode. By adjusting the motor output power and speed, the oil flow rate is increased, adapting to scenarios involving large-capacity oil tanks and rapid transfer of low-viscosity oil, thus efficiently completing oil transfer operations.

[0111] S220a, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is earlier than the second trigger time, then the submersible pump drive mode is confirmed as the second drive mode; wherein, the second drive mode is a precise volume control mode, which is suitable for quantitative transfer of small volume oil drums.

[0112] It's understandable that if the time interval between the first and second trigger times is greater than the preset time interval, it might indicate that the motor's process from light load start-up to stable high load operation is slower. The pump body doesn't quickly build up a high load, but rather gradually increases the flow rate and pressure. In this state, the motor speed and flow rate are highly controllable, preventing sudden increases in flow rate. This can match the quantitative and overflow prevention requirements of small-capacity oil tanks. It could also indicate that there is some resistance in the oil pumping condition. For example, when pumping high-viscosity oils (such as engine oil or gear oil), the oil has poor fluidity, resulting in high pump resistance and an inability to quickly increase the load. Or, when connecting long / thin pipelines, the pipeline resistance is high, requiring the pump body to gradually increase pressure to push the oil flow. Forcibly activating the rapid oil pumping mode under these conditions can easily lead to excessively high pipeline pressure and oil splashing. A first trigger time earlier than the second trigger time indicates that the current gradually increases from a low threshold to a high threshold, rather than abnormal current fluctuations (such as instantaneous spikes). If the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is earlier than the second trigger time, then the submersible pump drive mode will be confirmed as the second drive mode. In this mode, the pump will operate at a stable and controllable low flow rate to avoid overflow or over-pumping when pumping oil from small-capacity oil tanks, thus meeting the quantitative transfer requirements of small-capacity oil tanks.

[0113] S230a, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is later than the second trigger time, then the submersible pump drive mode is confirmed as the third drive mode; wherein, the third drive mode is a low power protection mode, which is suitable for energy-saving operation when the battery power is insufficient.

[0114] Under normal load conditions, the current first reaches the first threshold (light load) and then the second threshold (high load). This corresponds to the first trigger time being earlier than the second trigger time, and vice versa. This indicates the current rises to the second threshold first and then falls back to the first threshold, completely violating the normal current change logic during load increases. This is an abnormal timing characteristic. The vehicle battery voltage decreases as the battery is consumed. When the battery is low, the motor may experience a surge in current to the second threshold upon startup due to a large instantaneous current. However, the increased battery resistance prevents it from continuously providing the stable current required for a high load, causing the motor load to drop rapidly, and the current to fall back to the first threshold. The time interval between the first and second trigger times being greater than the preset time interval indicates a slow battery voltage drop, not a momentary short circuit or other fault, but a typical characteristic of insufficient range due to low battery. Therefore, the current reaching the second threshold first and then falling back to the first threshold indicates that the motor briefly reaches a high load and is forced to reduce its load. The pump's oil suction pressure will fluctuate, experiencing a surge followed by a sharp drop, significantly reducing pumping efficiency. If a high load is forcibly maintained, the battery voltage may drop further, potentially leading to motor shutdown or battery overheating. Therefore, when the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is later than the second trigger time, the submersible pump is switched to the third drive mode. This reduces battery energy consumption by reducing motor speed, limiting maximum current, and shortening the duration of a single run, thereby preventing battery over-discharge damage and adapting to emergency oil pumping needs when battery power is insufficient.

[0115] In one possible implementation, please refer to Figure 3 S100, in response to a first current event and a second current event in the power loop of the motor drive circuit, the sampling circuit acquires the first trigger time and the second trigger time, including:

[0116] S110b, in response to the current in the power circuit of the motor drive circuit decreasing from above a preset first threshold to a preset first threshold, the sampling circuit collects this moment as the first trigger time.

[0117] It can be understood that the first trigger time is the instant when the current in the power circuit of the motor drive circuit drops from a state that has been continuously higher than the preset first threshold to the instant when it equals the preset first threshold (current falling edge trigger), emphasizing the instant when the current crosses the preset first threshold. The current in the power circuit of the motor drive circuit dropping from above the preset first threshold to the preset first threshold reflects the transition of the motor from a loaded operating state to a low-load / no-load transition state. This could be when the oil in the tank is about to be completely pumped out, the submersible pump body changes from pumping liquid oil to pumping a mixture of oil and air, the resistance to work is greatly reduced, and the motor load decreases accordingly; it could also be that the submersible pump was previously in a high-load operating state (such as rapid oil pumping mode), and when the system determines that it needs to switch to precise quantity control or battery energy saving mode, it will actively reduce the motor drive voltage, limit the motor power output, causing the load to gradually decrease, and the current to smoothly drop from above the first threshold back to the first threshold.

[0118] The sampling circuit identifies the moment when the current in the power circuit of the motor drive circuit drops from above a preset first threshold to the preset first threshold as the first trigger time, which can provide a basis for subsequent steps.

[0119] S120b, in response to the current in the power circuit of the motor drive circuit dropping from above the preset second threshold to the preset second threshold, the sampling circuit collects this moment as the second trigger time.

[0120] It can be understood that the second trigger time is the instant when the current in the power circuit of the motor drive circuit drops from a state that is continuously higher than the preset second threshold to equal the preset second threshold (current falling edge trigger), emphasizing the instant the current just drops to the threshold. The current in the power circuit of the motor drive circuit dropping from above the preset second threshold to the preset second threshold reflects the motor's return from a high load / critical overload state to a stable operating state. This could be when the oil in the tank is about to be emptied, the pump body changes from full-load oil pumping to idling / air pumping, the resistance to work decreases sharply, and the motor current will quickly drop from above the second threshold of high load to the second threshold; it could also be that the submersible pump was previously in a high-load mode of rapid oil pumping, and when the system determines that it needs to switch to precise flow control or battery energy saving mode, it will actively reduce the motor drive voltage and limit the power output, causing the motor load to decrease steadily, and the current to gradually drop from above the second threshold to the second threshold.

[0121] The sampling circuit identifies the moment when the current in the power circuit of the motor drive circuit drops from above the preset second threshold to the preset second threshold as the second trigger time, which can provide a basis for subsequent steps.

[0122] In one possible implementation, please refer to Figure 3 S200, determining the submersible pump drive mode based on the first trigger time and the second trigger time, including:

[0123] S210b, if the time interval between the first trigger time and the second trigger time is less than the preset time interval, the submersible pump drive mode is confirmed as the fourth drive mode; wherein, the fourth drive mode is the anti-dry burning protection mode, which is suitable for shutdown protection when the oil in the oil tank is about to be pumped out and the current drops suddenly.

[0124] It is understandable that when the oil tank is full, the pump draws liquid oil, the load is stable, and the current remains above the first threshold. When the oil is about to be completely drawn out, the pump begins to mix the oil and air, eventually drawing out all the air. The resistance to work drops sharply, and the motor load decreases rapidly. The current will drop rapidly from above the second threshold to the first threshold in a stepped manner. The interval between the two falling edges is extremely short. This is a typical current characteristic of oil depletion. If the protection is not triggered in time, the pump will continue to run and completely draw out air, entering an idling state. On the one hand, the mechanical parts of the pump (such as the impeller and bearings) may experience significantly accelerated wear due to lack of oil lubrication. On the other hand, although the current is small when the motor is running under no-load, prolonged idling will still cause the windings to overheat due to insufficient heat dissipation, potentially leading to motor burnout. Therefore, the time interval between the first and second trigger times being less than the preset time interval is a warning signal of the risk of dry burning. Therefore, switching the submersible pump to the fourth drive mode controls the motor to slow down until it stops, avoiding mechanical wear and motor overheating damage caused by the pump running dry (air extraction), and adapting to the emergency protection needs when the oil in the tank is about to be pumped out.

[0125] S220b, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range, and the first trigger time is later than the second trigger time, then the submersible pump drive mode is confirmed as the fifth drive mode; wherein, the fifth drive mode is the overload recovery mode, which is suitable for stable operation after the current drops back after a brief overload.

[0126] It is understandable that the preset interval refers to the reasonable time range allowed between the trigger times of two current falling edges. It is a time range with clear upper and lower limits. The lower limit of the preset interval must be greater than the time threshold of the anti-dry burning mode (to avoid confusion with the working conditions of oil depletion and sudden current drop). For example, the lower limit of the preset interval can be 800ms, 1s, etc., but it is not limited to these. The upper limit of the preset interval must be less than the abnormal fallback time caused by motor failure (to avoid misjudging faults such as jamming and insufficient power supply as stable recovery). For example, the upper limit of the preset interval can be 2s, 3s, etc., but it is not limited to these.

[0127] The first and second trigger times here are both triggered at the falling edge of the current. The first trigger time is when the current drops from above the first threshold to the first threshold (rated load drops back to the light load threshold), and the second trigger time is when the current drops from above the second threshold to the second threshold (overload state drops back to the rated load threshold). The interval is greater than the preset time interval, indicating that the current drop is a gradual process, rather than a sudden drop when the oil is completely drained (excluding the anti-dry burning condition). The time interval is within the preset range, reflecting that the drop process is within a safe and stable speed range. Because the second threshold is greater than the first threshold, when the current drops from the overload state, it must first drop to the second threshold (high threshold) and then drop to the first threshold (low threshold). This timing sequence is a characteristic of normal step-like drop, eliminating false triggering caused by current fluctuations. Therefore, the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range. Furthermore, the fact that the first trigger time is later than the second trigger time reflects the state of the motor's condition easing and recovering smoothly after a brief overload. The submersible pump is switched to the fifth drive mode (overload recovery mode) to maintain the motor's stable speed and limit the maximum output power, preventing the motor from entering the overload state again. This mode is suitable for the condition of recovering to stable operation after a brief overload (a brief overload will cause the motor winding temperature to rise slightly. If the high-power mode is turned on immediately after recovery, it may overload again due to insufficient cooling of the windings. The fifth drive mode maintains a stable speed and limits the maximum current, allowing the motor to complete cooling under low load while ensuring basic oil pumping flow, thus achieving a balance between recovery operation and oil pumping efficiency).

[0128] S230b, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range, and the first trigger time is earlier than the second trigger time, then the submersible pump drive mode is confirmed as the sixth drive mode; wherein, the sixth drive mode is a low flow flushing mode, which is suitable for flushing and transferring residual oil in the oil drum.

[0129] Under normal circumstances, since the second threshold is greater than the first threshold, the timing of the current falling edge must be that the second threshold falls first (the second trigger time is earlier), and then the first threshold falls (the first trigger time is later). The first trigger time is later than the second trigger time, while the first trigger time is earlier than the second trigger time, which indicates that there is load fluctuation during the current drop-off process, and it is not a smooth step-like drop-off. The time interval between the first trigger time and the second trigger time is within the preset range, which eliminates abnormal fluctuations caused by motor jamming, unstable power supply, and the anti-dry burning condition of sudden oil depletion.

[0130] Therefore, the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range. Furthermore, the first trigger time being earlier than the second trigger time reflects the final condition where only residual oil remains in the oil drum and the pump load fluctuates violently. At this time, the pump cannot continuously draw in enough oil, resulting in an alternating state where the load increases when oil is drawn in (current surges to near the second threshold) and the load drops sharply when air is drawn in (current drops below the first threshold). This causes the current drop-off sequence to be reversed, switching the submersible pump to the sixth drive mode (low flow flushing mode). The motor is controlled to run intermittently at low speed, slowly stirring the residual oil at the bottom of the oil drum so that it can be collected and then extracted. This prevents the residual oil from being unable to be transferred due to the pump running dry, thus meeting the residual oil flushing requirements in the final stage of the oil drum operation.

[0131] In one possible implementation, please refer to Figure 3 S100, in response to a first current event and a second current event in the power loop of the motor drive circuit, the sampling circuit acquires the first trigger time and the second trigger time, including:

[0132] S110c, in response to the current in the power circuit of the motor drive circuit rising from below the preset first threshold to the preset first threshold, the sampling circuit collects this moment as the first trigger time.

[0133] It can be understood that the first trigger time is the instant when the current in the power circuit of the motor drive circuit rises from a state that is continuously below the preset first threshold to equal the preset first threshold, reflecting the motor's transition from a static standby state to a light-load effective operating state. Identifying the instant when the current in the power circuit of the motor drive circuit rises from a state that is continuously below the preset first threshold to equal the preset first threshold as the first trigger time through a sampling circuit can provide a basis for subsequent steps.

[0134] S120c, in response to the current in the power circuit of the motor drive circuit dropping from above the preset second threshold to the preset second threshold, the sampling circuit collects this moment as the second trigger time.

[0135] It can be understood that the second trigger time is the instant when the current in the power circuit of the motor drive circuit drops from a state that is continuously higher than the preset second threshold to equal the preset second threshold, reflecting the motor's return from an overload / high load state to the rated load level. Identifying the instant when the current in the power circuit of the motor drive circuit drops from a state that is continuously higher than the preset second threshold to equal the preset second threshold as the second trigger time through the sampling circuit can provide a basis for subsequent steps.

[0136] In one possible implementation, please refer to Figure 3 S200, determining the submersible pump drive mode based on the first trigger time and the second trigger time, including:

[0137] S210c, if the time interval between the first trigger time and the second trigger time is less than the minimum time interval, the submersible pump drive mode is confirmed as the seventh drive mode; wherein, the seventh drive mode is the emergency stop mode, which is suitable for rapid stop when there is a sudden abnormal current fluctuation.

[0138] It is understandable that the minimum time interval can be less than the preset time interval to distinguish between the anti-dry burning condition and the fault condition. For example, the minimum time interval can be 20ms, 50ms, etc., but it is not limited to this. The time interval between the first and second trigger times being less than the minimum time interval reflects a sudden surge in current (e.g., a jump from below the first threshold to above the second threshold), followed by a sudden drop in current (e.g., a drop from above the second threshold to below the first threshold). The normal load increase / decrease interval is several hundred milliseconds to seconds (greater than the preset time interval). Only a fault will compress the interval between the two trigger times to a minimum (less than the preset time interval). For example, the pump impeller may be stuck by foreign objects (e.g., metal shavings, clumps of oil), or the motor rotor may be stuck. When the motor starts, the stalled rotor will generate an impact current several times the rated current, and the current will surge from a low current to above the second threshold in a very short time, compressing the interval between the two trigger times to a minimum. It may also be due to damage to the insulation layer of the motor drive circuit, a short circuit in the terminal, or a fault in the sampling circuit causing a false alarm in the current signal, resulting in irregular fluctuations in the current, such as a sudden surge or drop in current. For example, during a short circuit, the current may momentarily exceed the second threshold and then briefly drop back due to the action of the circuit protection. The interval between the two trigger times is extremely short, reflecting a fault in the electrical system.

[0139] Therefore, when the time interval between the first trigger time and the second trigger time is less than the preset time interval, the submersible pump will be immediately switched to the seventh drive mode (emergency stop mode) to cut off the power supply to the motor drive circuit and force the motor to stop, so as to avoid the fault from escalating.

[0140] S220c, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range, and the first trigger time is earlier than the second trigger time, then the submersible pump drive mode is confirmed as the eighth drive mode; wherein, the eighth drive mode is an adaptive flow mode, which is suitable for automatic adaptation operation of oils with different viscosities.

[0141] It is understandable that if the time interval between the first and second trigger times is within the preset range, it indicates a controllable load fluctuation process (too short indicates a sudden fault, too long indicates abnormal conditions such as motor jamming or unstable power supply); if the time interval between the first and second trigger times is greater than the preset time interval, but the time interval between the first and second trigger times is within the preset range, it indicates that the process of the motor starting from a light load and falling back to a high load is not abrupt. It is neither a rapid load increase without falling back for low-viscosity oil, nor a difficult load increase for high-viscosity oil, but a general working condition for medium-low to medium-high viscosity oil (such as mixed oil or light engine oil), excluding fault conditions such as sudden current changes (such as short circuits or jamming, corresponding to the minimum interval of the seventh drive mode); if the first trigger time is earlier than the second trigger time, it indicates a normal load change timing characteristic (the motor first completes the start-up and load increase (first trigger time), and then due to changes in the oil extraction conditions (such as oil viscosity fluctuations or changes in pipeline resistance), the load increases to exceed the second threshold, and then smoothly falls back to the second threshold (second trigger time)).

[0142] Therefore, when the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range, and the first trigger time is earlier than the second trigger time, the submersible pump is switched to the eighth drive mode (adaptive flow mode) to monitor the load change of the current feedback in real time and dynamically adjust the motor speed and power (for example, when the oil viscosity is too high and the load increases, the speed is reduced and the torque is increased to avoid overload; when the oil viscosity is too low and the load decreases, the speed is increased to ensure oil pumping efficiency).

[0143] S230c, if the time interval between the first trigger time and the second trigger time is greater than the preset time interval and is within the preset range, and the first trigger time is later than the second trigger time, then the submersible pump drive mode is confirmed as the ninth drive mode; wherein, the ninth drive mode is the battery energy saving mode, which is suitable for power reduction operation when the battery is low.

[0144] Under normal operating conditions, the motor logic is to first start and increase load (first trigger time, early), then reduce load (second trigger time, late). The fact that the first trigger time is later than the second trigger time indicates that the motor experienced a high load reduction before barely triggering a light load start, a typical manifestation of insufficient battery power (possibly because the motor briefly surged above the second threshold due to high oil extraction resistance, but the increased battery internal resistance prevented it from continuously providing the current required for high load, causing the current to drop back to the second threshold (second trigger time); subsequently, the battery could only support the motor to attempt starting at extremely low power, with the current slowly rising to the first threshold (first trigger time)). Therefore, when the time interval between the first and second trigger times is greater than a preset time interval but within a preset range, and the first trigger time is later than the second trigger time, the submersible pump is switched to the ninth drive mode (battery energy-saving mode). This actively reduces the motor's rated power, limits the maximum speed, and extends the single start-stop interval. By reducing energy consumption per unit time, it prevents battery damage due to over-discharge caused by high power output, while simultaneously extending the oil extraction time under low battery conditions to complete the transfer of residual oil.

[0145] Please see Figure 4 This application also provides a submersible pump drive system for implementing the submersible pump drive method of any of the above embodiments. The submersible pump drive system includes:

[0146] The acquisition unit is used to respond to a first current event and a second current event in the power loop of the motor drive circuit, and to acquire a first trigger time and a second trigger time through a sampling circuit; wherein, the first current event is when the current reaches a preset first threshold, the second current event is when the current reaches a preset second threshold, the first trigger time is the trigger time of the first current event, and the second trigger time is the trigger time of the second current event.

[0147] A drive unit is used to determine the submersible pump drive mode based on a first trigger time and a second trigger time; wherein the submersible pump drive mode is used to control the submersible pump.

[0148] The execution subject of the submersible pump driving method provided in this application embodiment can be a submersible pump system, specifically a control circuit of the submersible pump system (including STM32F103 MCU, STM8S MCU or TMS320F28035 DSP, etc.). The control circuit can include: at least one processor, at least one memory, and a computer program stored in at least one memory and capable of running on at least one processor. When the processor executes the computer program, it causes the submersible pump to implement the steps in any of the above-described submersible pump driving method embodiments.

[0149] For example, a computer program can be divided into one or more modules / units, one or more of which are stored in memory and executed by a processor to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the control unit.

[0150] The processor can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0151] In some embodiments, the memory may be an internal storage unit of the control unit, such as the hard disk or RAM of the control unit. In other embodiments, the memory may be an external storage device of the control unit, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the control unit. Furthermore, the memory may include both internal storage units and external storage devices of the control unit. The memory is used to store the operating system, applications, bootloader, data, and other programs, such as program code for computer programs. The memory can also be used to temporarily store data that has been output or will be output.

[0152] This application also provides a submersible pump system, which includes the submersible pump frequency conversion drive circuit of any of the above embodiments, for implementing the submersible pump drive method of any of the above embodiments.

[0153] The submersible pump system also includes the submersible pump, a portable power device specifically designed for extracting and transporting oily liquids. It uses a built-in electric drive (usually a DC motor) to rotate an impeller, creating negative pressure at the pump inlet to draw in the oil, pressurize it, and then discharge it through an output hose. For example, the positive and negative terminals of the DC power supply can be connected to the power input terminal of the motor drive circuit of the frequency converter drive circuit 100, and the power output interface of the frequency converter drive circuit 100 (such as the power output terminal of the motor drive circuit) can be connected to the two ends of the armature winding of the DC motor built into the submersible pump, providing a frequency-adjustable / voltage-adjustable drive current to the DC motor built into the submersible pump.

[0154] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0155] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for driving a submersible pump, characterized in that, This is applied to a variable frequency drive circuit for submersible pumps. The variable frequency drive circuit is used in a submersible pump system. The variable frequency drive circuit includes a motor drive circuit and a control circuit. The motor drive circuit is connected to the control circuit. The variable frequency drive circuit also includes: Isolation operational amplifier module U1; The sampling circuit is connected to the power circuit of the motor drive circuit and the input terminal of the isolation operational amplifier module U1, respectively. It is used to collect the current of the power circuit of the motor drive circuit, convert the current of the power circuit into a differential voltage signal proportional to the current, and output it to the input terminal of the isolation operational amplifier module U1. Two power supply filtering circuits are provided. One of the power supply filtering circuits is connected to the isolation operational amplifier module U1 and the 5V power supply respectively, and is used to absorb electrostatic pulses on the power side power supply line and stabilize the power side power supply voltage. The other power supply filtering circuit is connected to the isolation operational amplifier module U1 and the 3V3 power supply respectively, and is used to absorb electrostatic pulses on the control side power supply line and stabilize the control side power supply voltage. A differential-to-single-ended circuit, connected to the output of the isolated operational amplifier module U1, is used to convert the differential signal output by the isolated operational amplifier module U1 into a single-ended signal; and A filtering and protection circuit is connected to the input terminals of the differential-to-single-ended circuit and the control circuit, respectively. It is used to receive the single-ended signal output by the differential-to-single-ended circuit, filter out high-frequency noise of the single-ended signal, absorb electrostatic pulses, and output it to the ADC interface of the control circuit. The method includes: In response to a first current event and a second current event in the power loop of the motor drive circuit, a first trigger time and a second trigger time are acquired by a sampling circuit; wherein, the first current event is when the current reaches a preset first threshold, the second current event is when the current reaches a preset second threshold, the first trigger time is the trigger time of the first current event, and the second trigger time is the trigger time of the second current event. The submersible pump drive mode is determined based on the first trigger time and the second trigger time; wherein, the submersible pump drive mode is used to control the submersible pump.

2. The submersible pump driving method as described in claim 1, characterized in that, Pin 4 of the isolated operational amplifier module U1 is connected to power ground, and pin 5 of the isolated operational amplifier module U1 is connected to control ground. The sampling circuit includes resistors R1, R2, and R3, and capacitors C1, C2, and C3, wherein: The resistor R1 is connected in series in the power circuit of the motor drive circuit. One end of the resistor R1 is connected to the power circuit of the motor drive circuit, and the other end is connected to the power ground. The resistor R1 is used to generate a voltage difference proportional to the current when the current flows through it. One end of the resistor R2 is connected to the common node of the power loop of the resistor R1 and the motor drive circuit, and the other end is connected to pin 2 of the isolation operational amplifier module U1. One end of the resistor R3 is connected to the common node of the resistor R1 and the power ground, and the other end is connected to pin 3 of the isolation operational amplifier module U1. One end of the capacitor C1 is connected to the common node of the resistor R2 and the isolation operational amplifier module U1, and the other end is connected to the common node of the resistor R3 and the isolation operational amplifier module U1. One end of the capacitor C2 is connected to the common node of the resistor R3 and the isolation operational amplifier module U1, and the other end is connected to the common node of the isolation operational amplifier module U1 and the power ground. One end of the capacitor C3 is connected to the common node of the resistor R2 and the isolation operational amplifier module U1, and the other end is connected to the common node of the isolation operational amplifier module U1 and the power ground. The two ends of capacitor C1 are connected to pins 2 and 3 of the isolation operational amplifier module U1, respectively. Capacitors C2 and C3 are both connected to power ground. Resistors R1, R2, R3, C1, C2, and C3 form a differential filter network to filter out high-frequency noise in the sampled signal and match the input impedance of the isolation operational amplifier module U1 to avoid signal reflection.

3. The submersible pump driving method as described in claim 1, characterized in that, Pin 1 of the isolated operational amplifier module U1 is connected to a 5V power supply, and pin 8 of the isolated operational amplifier module U1 is connected to a 3V3 power supply. The power supply filtering circuit includes a power supply decoupling capacitor and an ESD protection diode, wherein: One end of the ESD protection diode is connected to a 5V power supply or a 3V3 power supply, and the other end is connected to power ground or control ground. It is used to absorb electrostatic pulses on the power side or control side power lines to prevent electrostatic damage to the power side or control side circuits. One end of the power supply decoupling capacitor is connected to a 5V power supply or a 3V3 power supply, and the other end is connected to power ground or control ground. It is used to filter out high-frequency noise from the 5V power supply or the 3V3 power supply, stabilize the power supply voltage on the power side or the control side, and ensure the purity of the input power supply to the isolation operational amplifier.

4. The submersible pump driving method as described in claim 1, characterized in that, The differential-to-single-ended circuit includes: resistors R4, R5, R6, and R7, and operational amplifier module U2, wherein: Pin 3 of operational amplifier module U2 is connected to pin 7 of isolation operational amplifier module U1, and resistor R6 is connected in series between pin 3 of operational amplifier module U2 and pin 7 of isolation operational amplifier module U1; pin 2 of operational amplifier module U2 is connected to pin 6 of isolation operational amplifier module U1, and resistor R4 is connected in series between pin 2 of operational amplifier module U2 and pin 6 of isolation operational amplifier module U1; resistors R4 and R6 are used to provide symmetrical input impedance to ensure balanced transmission of differential signals; One end of the resistor R5 is connected to pin 1 of the operational amplifier module U2, and the other end is connected to pin 2 of the operational amplifier module U2. The resistor R5 is used in conjunction with the resistors R4 and R6 to set the gain of the operational amplifier module U2. One end of the resistor R7 is connected to pin 3 of the operational amplifier module U2, and the other end is connected to a 1V24 reference voltage. The resistor R7 is used to provide a common-mode voltage reference for the operation of the operational amplifier module U2, ensuring that the operational amplifier module U2 operates within a suitable linear range. Pin 1 of the operational amplifier module U2 is connected to the filter protection circuit, pin 8 of the operational amplifier module U2 is connected to a 3V3 power supply, and pin 4 of the operational amplifier module U2 is connected to control ground. The operational amplifier module U2 is used to convert the differential signal output by the isolation operational amplifier module U1 into a single-ended signal and then output it to the filter protection circuit through pin 1.

5. The submersible pump driving method as described in claim 1, characterized in that, The filter protection circuit includes: resistor R8, capacitor C5, capacitor C6, and diode D3, wherein: One end of the resistor R8 is connected to the output terminal of the differential-to-single-ended circuit, and the other end is connected to the ADC input terminal of the control circuit. The resistor R8 is used to limit the input current of the ADC interface of the control circuit. One end of the capacitor C5 is connected to the 3V3 power supply, and the other end is connected to the control ground. The capacitor C5 is used to filter out high-frequency noise from the 3V3 power supply and stabilize the power supply voltage on the control side. One end of the capacitor C6 is connected to the common node of the resistor R8 and the ADC interface of the control circuit, and the other end is connected to the control ground. The capacitor C6 is used to filter out high-frequency noise in the single-ended signal output by the differential to single-ended circuit. One end of the diode D3 is connected to the ADC input terminal of the control circuit, and the other end is connected to the control ground. The diode D3 is used to absorb electrostatic pulses at the ADC input terminal of the control circuit.

6. The submersible pump driving method as described in claim 1, characterized in that, The first current event and the second current event in response to the power circuit of the motor drive circuit are sampled by a sampling circuit to acquire the first trigger time and the second trigger time, including: When the current in the power loop of the motor drive circuit increases from below the preset first threshold to the preset first threshold, the moment when this increase is collected by the sampling circuit is the first trigger time. In response to the current in the power loop of the motor drive circuit rising from below the preset second threshold to the preset second threshold, the sampling circuit collects this moment as the second trigger time.

7. The submersible pump driving method as described in claim 6, characterized in that, The step of determining the submersible pump drive mode based on the first trigger time and the second trigger time includes: If the time interval between the first trigger time and the second trigger time is less than a preset time interval, then the submersible pump drive mode is confirmed as the first drive mode; wherein, the first drive mode is a rapid oil pumping mode, which is suitable for rapid transfer of large-capacity oil tanks; If the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is earlier than the second trigger time, then the submersible pump drive mode is confirmed as the second drive mode; wherein, the second drive mode is a precise volume control mode, which is suitable for quantitative transfer of small-capacity oil drums; If the time interval between the first trigger time and the second trigger time is greater than the preset time interval, and the first trigger time is later than the second trigger time, then the submersible pump drive mode is confirmed as the third drive mode; wherein, the third drive mode is a low power protection mode, which is suitable for energy-saving operation when the battery power is insufficient.

8. The submersible pump driving method as described in claim 1, characterized in that, The first current event and the second current event in response to the power circuit of the motor drive circuit are sampled by a sampling circuit to acquire the first trigger time and the second trigger time, including: In response to the current in the power loop of the motor drive circuit dropping from above the preset first threshold to the preset first threshold, the moment when this is collected by the sampling circuit is taken as the first trigger time. In response to the current in the power circuit of the motor drive circuit dropping from above the preset second threshold to the preset second threshold, the sampling circuit collects this moment as the second trigger time.

9. A submersible pump system, characterized in that, The submersible pump system includes: Submersible pumps; and A submersible pump frequency converter drive circuit is used to implement the submersible pump drive method as described in any one of claims 1 to 8.

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