Liquid pump control system and method

Abstract

The invention provides a liquid pump control system and method, and relates to the technical field of oil field liquid pump control. The system comprises a high-precision sampling module used for sampling a motor of the liquid pump based on an oversampling rate to obtain sampling data; the control module is used for driving the high-frequency power module to operate at high frequency based on sampling data; and the high-frequency power module is used for executing a multi-section over-modulation strategy to control the motor. The method comprises the following steps: sampling a motor of the liquid pump based on an oversampling rate through a high-precision sampling module to obtain sampling data; the control module drives the high-frequency power module to operate at high frequency based on the sampling data; and through the high-frequency power module, executing a multi-section over-modulation strategy to control the motor. Through cooperation of high-precision sampling and high-frequency driving, the problems that an existing liquid pump control system cannot be started at ultralow frequency, the heavy load is prone to failing, the system efficiency is low, the load fluctuation adaptability is poor, and the reliability is poor are solved.

Description

Technical Field

[0001] This application relates to the field of oilfield liquid pump control technology, and more specifically, to a liquid pump control system and method. Background Technology

[0002] Currently, oilfield water injection pump control systems generally adopt traditional variable frequency control technology, mainly based on the following two schemes: Ordinary power frequency control: The water injection pump motor is directly started at power frequency, and flow and pressure are regulated by valves. The starting current reaches 3-5 times the rated current, causing a large impact on the power grid, and valve throttling losses are as high as 30-40% of energy consumption. Basic variable frequency control: This uses IGBT (Insulated Gate Bipolar Transistor) inverters and pressure closed-loop PID (Proportional-Integral-Derivative) control. Its core principle is: the motor current is collected by a Hall sensor, conditioned by an isolation operational amplifier, and then converted into a digital signal by an ADC (Analog-to-Digital Converter); the controller executes the PID control algorithm based on pressure sensor feedback and outputs a PWM (Pulse Width Modulation) wave to drive the IGBT inverter bridge. Due to low signal detection accuracy, the signal-to-noise ratio of the back EMF signal is too low when the back EMF detection frequency is <3Hz, making it impossible to accurately detect the rotor position for closed-loop control. This limits the minimum starting frequency, typically to 5-10Hz (10%-20% of the rated frequency), making true ultra-low frequency (<1Hz) heavy-load starting impossible. The static friction torque during water pump startup exceeds 150% of the rated value; inaccurate torque control at low frequencies can easily lead to stall or overcurrent protection. Simultaneously, IGBT switching losses are high, and combined with valve throttling losses, the overall system efficiency is ≤85%, resulting in high energy consumption and poor temperature resistance (junction temperature ≤125℃). Reliability drops sharply in high-temperature environments (>75℃). Furthermore, large load fluctuations due to changes in medium viscosity and injection volume lead to poor system adaptability, high energy consumption, and a lack of effective adaptive control mechanisms. Therefore, existing oilfield water injection pump control systems suffer from problems such as inability to start normally at low frequencies, high failure rate of heavy-load start-up, low system efficiency, low reliability at high temperatures, and poor adaptability to load fluctuations. These issues result in poor control performance of the oilfield water injection pump control system, affecting the stable operation of the water injection pump. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a liquid pump control system and method to improve the problem of poor control effect of oilfield water injection pump control systems in the prior art.

[0004] To address the aforementioned issues, this application provides a liquid pump control system, comprising: a high-precision sampling module, a high-frequency power module, and a control module; The control module is connected to the high-precision sampling module and the high-frequency power module; The high-precision sampling module is used to sample the motor of the liquid pump based on the oversampling rate to obtain sampling data; The control module is used to drive the high-frequency power module to operate at high frequency based on the sampled data; The high-frequency power module is used to execute a multi-segment overmodulation strategy to control the motor.

[0005] In the above implementation process, the liquid pump control system can be equipped with a high-precision sampling module with high sampling accuracy and a high-frequency power module with high switching frequency. The high-precision sampling module can obtain high-precision sampling data, which the control module then uses to drive the high-frequency power module to operate at high frequency. This high-frequency power module executes a multi-segment overmodulation strategy to control the liquid pump motor. The synergistic high-precision signal acquisition by the high-precision sampling module and the high-frequency, high-efficiency power drive of the high-frequency power module fundamentally improves the working performance of the liquid pump. It enables heavy-load starting at ultra-low frequencies, allowing the liquid pump to reliably handle various special operating conditions, reducing the current required for startup, improving voltage utilization, increasing overall system efficiency, and enhancing reliability under high-temperature conditions. This improves the reliability, stability, and safety of the liquid pump operation.

[0006] Optionally, the high-precision sampling module includes a Σ-Δ modulator, and the high-frequency power module includes a SiC inverter power module.

[0007] In the above implementation process, the high-precision sampling module can be configured as a Σ-Δ modulator, which can effectively increase the effective number of bits in the detected sampling data through high sampling rate and noise shaping techniques. This enables the control module to accurately extract the weak back electromotive force signal at low frequencies from strong noise based on the sampling data. The high-frequency power module can include a SiC inverter power module, which has a higher switching frequency and lower switching loss compared to existing IGBT devices, effectively improving startup efficiency and providing a basis for multi-segment overmodulation strategies.

[0008] Optionally, the oversampling rate OSR of the Σ-Δ modulator is ≥256, and the effective number of bits ENOB is ≥14.

[0009] In the above implementation process, the Σ-Δ modulator has a high oversampling rate and a high effective bit depth for signal detection, which effectively improves the accuracy of the obtained sampled data to achieve high-precision sampling.

[0010] Optionally, the SiC inverter power module is provided with multiple SiC MOSFETs, and the switching frequency of the SiC inverter power module is ≥40kHz and the junction temperature is ≥175℃.

[0011] In the above implementation process, multiple SiC MOSFETs can be set in the SiC inverter power module as power switching devices. The SiC inverter power module has a high switching frequency and a high junction temperature to adapt to high temperature environments. The high temperature resistance significantly improves the reliability of liquid pump operation.

[0012] Optionally, the starting frequency of the motor started by the SiC inverter power module is ≤0.3Hz.

[0013] In the above implementation process, combined with the coordinated control of the high-precision sampling module, the control module can extract the weak back electromotive force signal at low frequency. Therefore, the SiC inverter power module can start the motor of the liquid pump at an ultra-low starting frequency to achieve ultra-low frequency start-up.

[0014] Optionally, the control module includes: a first filter, a second filter, and a controller; The first filter is used to perform overcurrent detection based on the received sampled data; The second filter is used to filter the received sampled data to obtain filtered data; The controller is used to process the filtered data based on a detection algorithm to determine the rotor position of the motor; when the operating frequency of the liquid pump is less than or equal to a preset low-frequency operating frequency and greater than or equal to the starting frequency, it determines the initial torque of the motor based on the rotor position; when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency, it determines whether the liquid pump is stable based on the rotor position; if the liquid pump is determined to be stable, it switches from open-loop control mode to closed-loop control mode.

[0015] In the above implementation process, the control module is equipped with corresponding filters and controllers. The filters can perform overcurrent protection and filtering on the received sampled data to sample and reconstruct the data, obtaining more accurate filtered data. The controller can process the filtered data based on a detection algorithm to estimate the rotor position in the motor. To perform adaptive control under different frequency conditions, the current operating frequency of the liquid pump can be compared with the preset low-frequency operating frequency and the starting frequency. When the operating frequency is less than or equal to the preset low-frequency operating frequency and greater than or equal to the starting frequency, the initial torque of the motor can be determined based on the determined rotor position to enable the motor to output initial torque and overcome static friction. When the operating frequency rises to a level greater than the preset low-frequency operating frequency, the rotor position can be used to determine whether the liquid pump is in a stable operating state. When the liquid pump is stable, the control mode can be switched from open-loop control mode to closed-loop control mode to achieve stable operation based on closed-loop control mode as the operating frequency steadily increases, thus optimizing the control effect. More accurate filtered data can be extracted through data filtering, high-precision algorithms can be executed based on the filtered data, and different frequency ranges can be set to achieve different types of control, improving the effectiveness and reliability of the control.

[0016] Optionally, the system further includes: a pressure sensor; The pressure sensor is connected to the controller; The pressure sensor is used to detect the first inlet pressure information before the liquid pump starts; The controller is used to compare the first inlet pressure information with a first preset pressure threshold. If it is determined that the first inlet pressure information is less than the first preset pressure threshold, a stop-start command is generated. The pressure sensor is also used to detect the second inlet pressure information during the operation of the liquid pump; The controller is also used to compare the second inlet pressure information with a second preset pressure threshold. If it is determined that the second inlet pressure information is less than the second preset pressure threshold, a fault shutdown command is generated.

[0017] In the above implementation process, considering the influence of pressure when controlling the liquid inside the liquid pump, a pressure sensor can also be installed in the liquid pump control system. The pressure sensor is connected to the controller and installed inside the liquid pump. It can detect the first inlet pressure information before the liquid pump starts. The controller can compare the first inlet pressure information with a first preset pressure threshold. If the first inlet pressure is less than the first preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low, and it may not work properly after startup. Therefore, a corresponding stop-start command can be generated to pause the startup operation, and normal startup can resume once the pressure reaches the target level. The pressure sensor can also detect the second inlet pressure information during the operation of the liquid pump. The controller can compare the second inlet pressure information with a second preset pressure threshold. If the second inlet pressure is less than the second preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low, and there may be an abnormal fault. Therefore, a corresponding fault shutdown command can be generated to notify personnel to perform maintenance and other procedures on the liquid pump, so that the liquid pump can operate reliably under normal pressure.

[0018] Secondly, embodiments of this application also provide a liquid pump control method, the method being applied to the liquid pump control system described in any of the above claims, the method comprising: The motor of the liquid pump is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data; The control module drives the high-frequency power module to operate at high frequency based on the sampled data. The motor is controlled by executing a multi-segment overmodulation strategy through a high-frequency power module.

[0019] In the above implementation process, a high-precision sampling module obtains high-precision sampling data. Based on this data, a control module drives a high-frequency power module to operate at high frequency. The high-frequency power module then executes a multi-segment overmodulation strategy to control the liquid pump motor. The synergistic effect of high-precision signal acquisition from the high-precision sampling module and high-frequency, high-efficiency power drive from the high-frequency power module fundamentally improves the liquid pump's performance. This enables heavy-load startup at ultra-low frequencies, allowing the liquid pump to reliably handle various special operating conditions, reducing the current required for startup, improving voltage utilization, enhancing overall system efficiency, and increasing reliability under high-temperature conditions. Ultimately, this improves the reliability, stability, and safety of the liquid pump.

[0020] Optionally, the control module includes: a first filter, a second filter, and a controller; The step of driving the high-frequency power module to operate at high frequency based on the sampled data via the control module includes: Overcurrent detection is performed based on the received sampled data using the first filter; The received sampled data is filtered using the second filter to obtain filtered data. The controller processes the filtered data based on a detection algorithm to determine the rotor position of the motor. The controller determines the initial torque of the motor based on the rotor position when the operating frequency of the liquid pump is less than or equal to a preset low-frequency operating frequency and greater than or equal to the starting frequency. The controller determines whether the liquid pump is stable based on the rotor position when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency. If the liquid pump is determined to be stable, the controller switches from open-loop control mode to closed-loop control mode.

[0021] In the above implementation process, the control module is equipped with corresponding filter banks and controllers. The filters perform overcurrent protection and filtering on the received sampled data, allowing for sampling and reconstruction to obtain more accurate filtered data. The controller processes the filtered data based on a detection algorithm to estimate the rotor position in the motor. For adaptive control at different frequencies, the controller can compare the current operating frequency of the liquid pump with a preset low-frequency operating frequency and a starting frequency. When the operating frequency is less than or equal to the preset low-frequency operating frequency but greater than or equal to the starting frequency, the initial torque of the motor can be determined based on the determined rotor position to overcome static friction. When the operating frequency rises above the preset low-frequency operating frequency, the rotor position can be used to determine whether the liquid pump is in a stable operating state. If the liquid pump is stable, the control can switch from open-loop control mode to closed-loop control mode for stable operation as the operating frequency steadily increases, optimizing the control effect. The system can extract more accurate filtered data through data filtering, execute high-precision algorithms based on the filtered data, and set different frequency ranges to achieve different types of control, improving the effectiveness and reliability of the control.

[0022] Optionally, the system further includes: a pressure sensor; The method further includes: The pressure sensor detects the first inlet pressure information before the liquid pump starts. The controller compares the first inlet pressure information with a first preset pressure threshold. If the first inlet pressure information is determined to be less than the first preset pressure threshold, a stop-start command is generated. The pressure sensor detects the second inlet pressure information during the operation of the liquid pump. The controller compares the second inlet pressure information with a second preset pressure threshold. If the second inlet pressure information is determined to be less than the second preset pressure threshold, a fault shutdown command is generated.

[0023] In the above implementation process, considering the influence of pressure during liquid pump control, a pressure sensor can be installed in the liquid pump control system. This sensor detects the first inlet pressure before pump startup. The controller compares this first inlet pressure with a first preset pressure threshold. If the first inlet pressure is lower than the threshold, it indicates that the pump's current inlet pressure is too low, potentially causing malfunctions after startup. Therefore, a stop-start command can be generated to pause the startup process until the pressure reaches the required level. The pressure sensor can also detect the second inlet pressure during pump operation. The controller compares this second inlet pressure with a second preset pressure threshold. If the second inlet pressure is lower, it indicates that the pump's current inlet pressure is too low, potentially indicating a fault. Therefore, a fault shutdown command can be generated to notify personnel to perform maintenance and other repairs, ensuring reliable operation under normal pressure. Pressure detection can be performed at different operating points of the pump to determine its actual state and generate corresponding control commands, thereby improving pump safety.

[0024] Optionally, the method further includes: The controller determines the phase change of the motor's current waveform based on the filtered data. The controller determines the type of medium in the liquid pump based on the phase change. The controller determines a target parameter set from a preset parameter table based on the medium type, and controls the pressure in the liquid pump based on the target parameter set; wherein the preset parameter table has parameter sets corresponding to various medium types.

[0025] In the above implementation process, during the constant pressure control stage in closed-loop control mode, to maintain a stable pressure in the liquid pump, the controller can determine the phase change of the motor current waveform based on filtered data. Since the phase change reflects changes in the motor current, and the liquid medium controlled within the liquid pump affects these changes, the controller can determine the type of liquid medium controlled within the pump based on the phase change. Based on this type, it can then determine the corresponding target parameter set from a preset parameter table containing various different medium types, thereby controlling the pressure within the liquid pump based on the target parameter set. This allows the controller to infer the liquid medium type from the actual condition of the motor, and select appropriate parameters for control based on different medium types. This achieves adaptive control based on changes in medium viscosity, effectively improving the reliability of constant pressure control.

[0026] Thirdly, embodiments of this application provide a liquid pump control system, the system comprising: a Σ-Δ modulator, a SiC inverter power module, and a control module; The control module is connected to the Σ-Δ modulator and the SiC inverter power module; The Σ-Δ modulator is used to sample the motor of the liquid pump based on the oversampling rate to obtain sampled data; The control module is used to drive the SiC inverter power module to operate at high frequency based on the sampled data; The SiC inverter power module is used to control the motor by executing a multi-segment overmodulation strategy.

[0027] The liquid pump control system can be equipped with a high-precision Σ-Δ modulator and a high-frequency SiC inverter power module. The Σ-Δ modulator can obtain high-precision sampling data, which the control module then uses to drive the SiC inverter power module to operate at high frequency. This allows for multi-segment overmodulation strategy control of the liquid pump motor. The combined high-precision signal acquisition of the Σ-Δ modulator and the high-frequency, high-efficiency power drive of the SiC inverter power module fundamentally improves the liquid pump's performance. This enables heavy-load starting at ultra-low frequencies, allowing the liquid pump to reliably handle various special operating conditions, reducing the starting current, improving voltage utilization, enhancing overall system efficiency, and increasing reliability under high-temperature conditions. Ultimately, this improves the reliability, stability, and safety of the liquid pump.

[0028] In summary, the embodiments of this application provide a liquid pump control system and method that, through the coordinated high-precision signal acquisition of a high-precision sampling module and the high-frequency, high-efficiency power drive of a high-frequency power module, fundamentally improves the working performance of the liquid pump. It enables heavy-load startup at ultra-low frequencies, allowing the liquid pump to reliably cope with various special operating conditions, reducing the current required for startup, improving voltage utilization, enhancing the overall efficiency of the system, and increasing reliability under high-temperature conditions, thereby improving the reliability, stability, and safety of the liquid pump. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of a liquid pump control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of another liquid pump control system provided in an embodiment of this application; Figure 3 A schematic flowchart illustrating a liquid pump control method provided in an embodiment of this application; Figure 4 A detailed flowchart of step S220 provided for an embodiment of this application; Figure 5 A schematic flowchart of another liquid pump control method provided in an embodiment of this application; Figure 6 A schematic flowchart illustrating another liquid pump control method provided in this application embodiment; Figure 7 This is a waveform timing diagram provided for an embodiment of this application.

[0031] Icons: 110-High-precision sampling module; 120-High-frequency power module; 130-Control module; A-Motor; 131-First filter; 132-Second filter; 133-Controller; 140-Pressure sensor. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0033] Existing oilfield water injection pump control systems generally employ traditional variable frequency control technology, primarily based on the following two schemes: **Ordinary power frequency control:** The water injection pump motor is directly started at power frequency, with flow and pressure regulated by valves. The starting current reaches 3-5 times the rated current, causing significant impact on the power grid, and valve throttling losses can reach 30-40% of energy consumption. **Basic variable frequency control:** This uses an IGBT inverter and pressure closed-loop PID control. Its core principle is: a Hall sensor collects the motor current, which is then conditioned by an isolation operational amplifier and converted into a digital signal by an ADC; the controller executes the PID control algorithm based on pressure sensor feedback and outputs a PWM wave to drive the IGBT inverter bridge. Due to low signal detection accuracy, when the back EMF detection frequency is <3Hz, the back EMF signal signal-to-noise ratio is too low to accurately detect the rotor position for closed-loop control, resulting in a limited minimum starting frequency, typically 5-10Hz (10%-20% of the rated frequency), making true ultra-low frequency (<1Hz) heavy-load starting impossible. The static friction torque during water injection pump startup exceeds 150% of the rated value. Inaccurate torque control at low frequencies can easily lead to stall or overcurrent protection. Simultaneously, IGBT switching losses are high, and combined with valve throttling losses, the overall system efficiency is ≤85%, resulting in high energy consumption and poor temperature resistance (junction temperature ≤125℃). Reliability drops sharply at high temperatures (>75℃). Furthermore, large load fluctuations due to changes in medium viscosity and injection volume lead to poor system adaptability, high energy consumption, and a lack of effective adaptive control mechanisms. Therefore, existing oilfield water injection pump control systems suffer from problems such as inability to start normally at low frequencies, high failure rate during heavy-load startup, low system efficiency, low high-temperature reliability, and poor adaptability to load fluctuations. These issues result in poor control performance of the oilfield water injection pump control system, affecting the stable operation of the water injection pump.

[0034] To address the aforementioned issues, this application provides a liquid pump control system and method that, through the coordinated high-precision signal acquisition of a high-precision sampling module and the high-frequency, high-efficiency power drive of a high-frequency power module, fundamentally improves the working performance of the liquid pump. This enables heavy-load startup at ultra-low frequencies, allowing the liquid pump to reliably handle various special operating conditions, reducing the current required for startup, improving voltage utilization, enhancing overall system efficiency, and increasing reliability under high-temperature conditions. Ultimately, this improves the reliability, stability, and safety of the liquid pump.

[0035] Please see Figure 1, Figure 1 This is a schematic diagram of a liquid pump control system provided in an embodiment of the present application. The system may include: a high-precision sampling module 110, a high-frequency power module 120, and a control module 130.

[0036] The control module 130 is connected to the high-precision sampling module 110 and the high-frequency power module 120, and both the high-precision sampling module 110 and the high-frequency power module 120 are connected to the motor A of the liquid pump.

[0037] For example, liquid pumps can be various types of oilfield pumps that can transport liquids, such as water injection pumps, polymer pumps, polymer drive pumps, fracturing pumps, mud pumps, feed pumps, and gathering pumps.

[0038] Optionally, the control module 130 can be an electronic device with logic computing functions, such as a server, personal computer (PC), tablet computer, smartphone, or personal digital assistant (PDA), which can communicate with the high-precision sampling module 110 and the high-frequency power module 120 via networks, Bluetooth, or other means. Alternatively, it can be a processor or similar structure installed within the liquid pump control system, connected to the high-precision sampling module 110 and the high-frequency power module 120 via electrical cables or other devices. The processor may be an integrated circuit chip with signal processing capabilities, or a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0039] The high-precision sampling module 110 samples the motor A of the liquid pump based on the oversampling rate to obtain sampled data. The control module 130 drives the high-frequency power module 120 to operate at high frequency based on the sampled data. The high-frequency power module 120 executes a multi-segment overmodulation strategy to control the motor A. The liquid pump control system can be equipped with a high-precision sampling module 110 with high sampling accuracy and a high-frequency power module 120 with high switching frequency. The high-precision sampling module 110 can obtain high-precision sampled data, which the control module 130 then uses to drive the high-frequency power module 120 to operate at high frequency. The high-frequency power module 120 then executes a multi-segment overmodulation strategy to control the motor A of the liquid pump. The coordinated high-precision signal acquisition by the high-precision sampling module 110 and the high-frequency, high-efficiency power drive of the high-frequency power module 120 fundamentally improve the working performance of the liquid pump.

[0040] For example, multi-segment overmodulation strategies can include a variety of overmodulation strategies such as five-segment overmodulation strategy, seven-segment SVPWM or specific harmonic elimination PWM (SHEPWM). Taking the five-segment overmodulation strategy as an example, it can utilize the device performance of the high-frequency power module 120 to optimize the PWM waveform during control, dynamically map the waveform reconstruction and dead time, improve the voltage utilization of the DC bus to 98%, and reduce losses.

[0041] Optionally, the high-precision sampling module 110 can be an analog-to-digital converter capable of achieving high oversampling rate (OSR≥256) and noise shaping. The high-frequency power module 120 can be an inverter circuit composed of wide-bandgap semiconductor power switching devices.

[0042] Optionally, the high-precision sampling module 110 may include a Σ-Δ modulator. The Σ-Δ modulator can effectively increase the effective number of bits in the detected sampling data through high sampling rate and noise shaping techniques, enabling the control module 130 to accurately extract the weak back electromotive force signal at low frequencies from strong noise based on the sampling data. The high-frequency power module 120 may include a SiC inverter power module. Compared with existing solutions using IGBT devices, the SiC inverter power module has a higher switching frequency and lower switching losses, effectively improving startup efficiency and providing a basis for multi-segment overmodulation strategies and closed-loop control algorithms.

[0043] Optionally, the Σ-Δ modulator can acquire signals such as phase current, voltage, and position sensor data of motor A with high precision. Through oversampling and noise shaping techniques, it pushes the quantization noise to the high-frequency band, enabling accurate sampling even at low speeds and low currents, thus providing a data foundation for subsequent closed-loop control.

[0044] It should be noted that the oversampling rate is much higher than the Nyquist frequency (twice the highest frequency of the signal). The oversampling rate (OSR) of a Σ-Δ modulator is ≥256, meaning the sampling frequency is 512 times the signal bandwidth. This allows quantization noise to be dispersed over a wider frequency range, significantly reducing noise density within the target signal bandwidth. It also provides sufficient transition band for subsequent data filtering, effectively filtering out out-of-band noise without affecting the signal itself. The effective bit number (ENOB) measures the sampling accuracy. A Σ-Δ modulator with an ENOB ≥14 indicates that its actual performance is equivalent to an ideal 14-bit ADC, enabling it to resolve extremely small voltage changes. For example, within a ±10V range, the smallest voltage change that a Σ-Δ modulator can resolve is approximately 20 / 2^14. With a voltage of approximately 1.22mV, it provides high signal fidelity. Furthermore, the combination of high oversampling rate and high effective bit depth significantly improves the signal-to-noise ratio within the signal bandwidth, enabling the extraction of extremely weak effective signals in strong noise backgrounds. This effectively improves the accuracy and resolution of the sampled data, reduces dead zones and nonlinear distortion, and enhances the efficiency and performance of control based on sampled data.

[0045] Optionally, the SiC inverter power module incorporates multiple SiC MOSFETs (metal-oxide-semiconductor field-effect transistors based on silicon carbide). Due to the extremely high electron saturation drift velocity of SiC material, SiC MOSFETs exhibit very fast switching speeds, meaning extremely short turn-on / turn-off times. Furthermore, SiC devices maintain very low on-state resistance even under high voltage, resulting in low conduction losses. Their switching losses are significantly lower than those of existing IGBT devices, thereby improving the overall control efficiency of the SiC inverter power module through extremely low switching losses. Moreover, for the liquid pump motor A, the SiC inverter power module allows for the use of higher PWM switching frequencies. For example, the switching frequency of the SiC inverter power module used in this application is ≥40kHz, far exceeding the ≤10kHz switching frequency of existing IGBT devices. This higher switching frequency enables a more sinusoidal current waveform in motor A, reducing torque ripple and motor A heating, thereby reducing noise during motor A operation and allowing the liquid pump to respond more quickly to load and command changes, improving the dynamic performance of the liquid pump. Furthermore, the junction temperature of the SiC inverter power module is ≥175℃, making it suitable for various high-temperature operating environments, such as outdoor high-temperature environments with temperatures exceeding 75℃. This high-temperature resistance significantly improves the reliability of liquid pump operation.

[0046] Alternatively, an isolated Σ-Δ modulator, such as the AD7403 isolated Σ-Δ modulator, can be used to suppress common-mode noise. To address the wide-spectrum noise generated by the high switching frequency of the SiC inverter power module, the SiC inverter power module and the Σ-Δ modulator can be isolated to reduce the interference of wide-spectrum noise on the Σ-Δ modulator.

[0047] Optionally, the SiC inverter power module can be packaged at high temperatures. For example, the SiC inverter power module can be packaged using HPD packaging with a thermal resistance of <0.5K / W to improve the reliability of the SiC inverter power module during operation.

[0048] It should be noted that the high-precision sampling module 110 may also include other devices with high-resolution ADC architecture, such as an ultra-high resolution SAR ADC (successive approximation register analog-to-digital converter) + low-noise preamplifier circuit, which can achieve high-precision sampling. The high-frequency power module 120 may also include other devices with high switching frequency, such as GaN HEMT (gallium nitride high electron mobility transistor), which can achieve high-frequency and high-efficiency driving.

[0049] Optionally, in closed-loop control mode, the starting frequency of the SiC inverter power module to start motor A is ≤0.3Hz. Combined with the coordinated control of the high-precision sampling module 110, the control module 130 can extract the weak back electromotive force signal at low frequency. Therefore, the SiC inverter power module can start the liquid pump motor A at an ultra-low starting frequency to achieve ultra-low frequency start-up.

[0050] For example, compared with the lowest startup frequency of 5-10Hz in the prior art, the lowest startup frequency of this application is ≤0.3Hz, which can achieve heavy-load startup at ultra-low frequency and improve efficiency by more than 94%.

[0051] Optionally, please refer to Figure 2 , Figure 2 This is a schematic diagram of another liquid pump control system provided in an embodiment of the present application, wherein the control module 130 may include: a first filter 131, a second filter 132 and a controller 133.

[0052] Optionally, the first filter 131 and the second filter 132 are connected to the high-precision sampling module 110 and the controller 133. The first filter 131 is used for overcurrent detection based on the received sampling data, and the second filter 132 is used for filtering the received sampling data to obtain filtered data. The controller 133 is used to process the filtered data based on the detection algorithm to determine the rotor position of motor A; when the operating frequency of the liquid pump is less than or equal to the preset low-frequency operating frequency and greater than or equal to the starting frequency, it determines the initial torque of motor A based on the rotor position; when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency, it determines whether the liquid pump is stable based on the rotor position. If the liquid pump is determined to be stable, it switches from open-loop control mode to closed-loop control mode.

[0053] For example, the first filter 131 and the second filter 132 can be configured as a dual filter bank, such as a dual Sinc³ filter bank, providing a high-speed overcurrent protection path and a high-precision control path, respectively. The Sinc³ filter can decode and downsample the sampled data to convert the bitstream sampled data into high-resolution digital code filtered data. Through its notch characteristics, the Sinc³ filter provides good anti-aliasing and noise suppression capabilities, exhibits good anti-PWM interference ability, and effectively improves the accuracy and effectiveness of the filtered data.

[0054] Optionally, the dual Sinc³ filter bank can process high-bandwidth (OSR=8) and high-precision (OSR=256) data streams in the sampled data in parallel. The high-speed path (OSR=8) is used for μs-level overcurrent protection (first filter 131); the high-precision path (OSR=256) is used for the control loop (second filter 132), with a response delay of <2μs. The reconstructed digital signal has an effective bit length (ENOB) ≥14 bits and is used for the control loop to ensure that the error of the final rotor position is less than a preset error threshold. The rotor position error compensation process may include: ; in, This is the change in rotor position angle, i.e., the compensation amount (unit: radians or degrees). Torque constant (unit: (or dimensionless) This is the actual current along the q-axis. The target current along the q-axis (unit: A). For time derivative.

[0055] For example, the controller 133 can be configured as a high-performance DSP to provide sufficient computing power for data processing, execute a variety of high-precision algorithms, and perform parallel data processing through the hard computing power of high-performance multi-core DSP+FPGA, which effectively improves the real-time performance of data processing and thus improves the drive matching accuracy of the high-frequency power module 120.

[0056] Optionally, the detection algorithm can be a phase-locked loop (PLL) algorithm, which compares the phase of the input back electromotive force (EMF) signal (or a signal related to the back EMF) with the position estimate output by the PLL itself to determine a smooth and accurate rotor position estimate as the rotor position. Alternatively, the detection algorithm can be a sliding mode observer (SMO) algorithm, which establishes a current observation model based on the state equations of motor A. This model uses the terminal voltage and the estimated back EMF to predict the current value. The actual measured current is compared with the current predicted by the observer to obtain the current error. This error is processed through a switching function (such as the sign function `sign()`). The switching function generates a high-frequency switching signal, whose equivalent control value contains the back EMF information. After filtering, the switching signal yields a smooth estimated back EMF. Based on the estimated back EMF and the arctangent function, the corresponding rotor position can be calculated.

[0057] Alternatively, the detection algorithm may also include other types of algorithms, such as high-frequency signal injection, that can achieve rotor position identification at low speeds, enabling zero-speed rotor positioning.

[0058] It should be noted that the position error is the rotor position error within multiple consecutive point cycles. The preset error threshold can be set according to the model of motor A, actual conditions and requirements, etc. For example, it can be set to 0.5°. By comparing the magnitude of the error threshold and the position error, the deviation of the rotor position of motor A can be determined, thereby determining whether the liquid pump is stable. If it is stable, the control mode can be switched.

[0059] It should be noted that only with the high-precision sampling data provided by the Σ-Δ modulator can the stability of the liquid pump at ultra-low frequencies be reliably determined, thereby achieving a safe and smooth switch from open-loop control mode to closed-loop control mode and realizing ultra-low frequency start-up.

[0060] It should be noted that the open-loop control mode can include a V / F open-loop control mode, which maintains a constant ratio of voltage V to frequency F. This allows the air gap flux of the liquid pump motor A to remain constant at different frequencies, and the voltage can vary proportionally with the frequency. The control module 130 can directly output a three-phase sine wave signal with a given frequency and voltage to the high-frequency power module 120 to drive the motor A. This approach involves less computation and lower control costs. The closed-loop control mode can include a closed-loop control mode based on the FOC control algorithm. This mode can decouple the three-phase AC current of the motor A into two independent DC components—the excitation current component and the torque current component—through coordinate transformation. These two components can then be precisely controlled in a closed loop, resulting in high control accuracy.

[0061] Optionally, the preset low-frequency operating frequency can be set according to the actual situation and requirements of motor A. For example, it can be set to 1Hz. When the operating frequency of the liquid pump is in the range of [0.3Hz-1Hz], the controller 133 can determine the output torque of motor A, so that the high-frequency power module 120 can control motor A to output initial torque based on the initial torque to overcome static friction and achieve low-frequency start-up through pre-torque injection. When the operating frequency of the liquid pump is greater than 1Hz, the controller 133 switches from open-loop control mode to closed-loop control mode, so that the operating frequency can be smoothly increased at a steady slope (e.g., 2Hz / s), reducing impact and achieving dynamic field weakening frequency increase.

[0062] Optionally, the ultra-low frequency start-up control process of controller 133 may include: a pre-torque injection stage: In the ultra-low frequency range of 0.3Hz to 1Hz, controller 133 accurately estimates the motor rotor position based on high-precision data acquired by the Σ-Δ modulator and reconstructed by the second filter 132, using a phase-locked loop (PLL) or sliding mode observer (SMO) algorithm. Subsequently, controller 133 outputs a command to the SiC inverter power module to output a defined initial torque (e.g., 150% of the rated torque) to overcome the static friction torque of the pump body. Dynamic field weakening and frequency increase stage: When the frequency rises to 1Hz, the system enters closed-loop control mode. Controller 133 smoothly increases the output frequency at a slope of 2Hz / s to avoid impacting the power grid and mechanical system. Constant pressure adaptive control stage: After entering constant pressure operation, controller 133 executes a viscosity-adaptive pressure control algorithm (viscosity-PID). This algorithm indirectly determines the viscosity of the pumped medium (such as water or polymer solution) by analyzing the phase change of the motor current waveform, and automatically adjusts the parameters of the PID controller to maintain a stable outlet pressure (fluctuation less than ±0.1MPa).

[0063] Please continue reading. Figure 2Considering the influence of pressure when controlling the liquid inside the liquid pump, the system may also include a pressure sensor 140. The pressure sensor 140 is connected to the controller 133, and the pressure sensor 140 can be installed at the inlet of the liquid pump to detect the inlet pressure of the liquid pump.

[0064] The pressure sensor 140 is used to detect the first inlet pressure information before the liquid pump starts. The controller 133 compares the first inlet pressure information with a first preset pressure threshold. If the first inlet pressure information is determined to be less than the first preset pressure threshold, a stop-start command is generated. When the first inlet pressure information is less than the first preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low, and it may not work properly after starting. Therefore, a corresponding stop-start command can be generated to pause the start-up operation, and normal start-up can be resumed after the pressure reaches the target level.

[0065] The pressure sensor 140 is also used to detect the second inlet pressure information during the operation of the liquid pump. The controller 133 is also used to compare the second inlet pressure information with a second preset pressure threshold. If the second inlet pressure information is determined to be less than the second preset pressure threshold, a fault shutdown command is generated. When the second inlet pressure information is less than the second preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low, which may indicate an abnormal fault. Therefore, a corresponding fault shutdown command can be generated to notify the personnel to perform maintenance and other procedures on the liquid pump, so that the liquid pump can operate reliably under normal pressure.

[0066] For example, the pressure sensor 140 can be a piezoresistive pressure sensor, a diffused silicon pressure sensor, a capacitive pressure sensor, a ceramic piezoresistive pressure sensor, or other types of pressure-detecting devices.

[0067] Optionally, the controller 133 is equipped with a corresponding pressure-PID controller 133, and the system may also be equipped with a corresponding flow meter to detect the flow rate of the liquid medium in the liquid pump and dynamically control the relevant parameters of the pressure-PID controller 133 based on the flow detection results.

[0068] Optionally, this application also provides a liquid pump control system, comprising: a Σ-Δ modulator, a SiC inverter power module, and a control module; the control module is connected to the Σ-Δ modulator and the SiC inverter power module; the Σ-Δ modulator is used to sample the motor of the liquid pump based on the oversampling rate to obtain sampled data; the control module is used to drive the SiC inverter power module to operate at high frequency based on the sampled data; the SiC inverter power module is used to execute a multi-segment overmodulation strategy to control the motor. As the core and preferred technical solution of this application, by using a Σ-Δ modulator and configuring its oversampling rate OSR≥256, the effective number of bits for signal detection can be increased to ENOB≥14 bits, thereby accurately extracting weak back electromotive force signals with frequencies below 0.3Hz from strong noise backgrounds; at the same time, by using a SiC inverter power module and setting its switching frequency ≥40kHz and junction temperature ≥175℃, not only are switching losses significantly reduced, but its high-frequency characteristics also provide a foundation for realizing accurate closed-loop control algorithms. This application is the first to synergistically apply Σ-Δ ultra-high precision sampling technology with SiC high-frequency and high-efficiency power technology to a liquid pump control system. The collaborative work of the Σ-Δ modulator and the SiC inverter power module is the key to achieving high system performance. The two work together to produce an unexpected synergistic effect: the high-precision signal acquisition of the Σ-Δ modulator and the high-frequency and high-efficiency power drive of the SiC inverter power module fundamentally improve the working performance of the liquid pump, enabling heavy-load start-up at ultra-low frequencies. This allows the liquid pump to reliably cope with various special operating conditions, reduces the current required for start-up, improves voltage utilization, enhances the overall efficiency of the system, and increases reliability under high-temperature conditions, thereby improving the reliability, stability, and safety of the liquid pump.

[0069] Optionally, the technical solution of this application achieves the following significant beneficial effects: Ultra-low frequency start-up capability: Based on the oversampling (OSR≥256) and noise shaping technology of the Σ-Δ modulator, the effective number of bits (ENOB) for signal detection is increased to ≥14 bits, which can accurately extract the ultra-weak back electromotive force signal at 0.3Hz from strong noise, realizing ultra-low frequency heavy-load start-up with a minimum of ≤0.3Hz. Compared with the prior art (5-10Hz), the start-up frequency is reduced by more than 94%. High efficiency and high reliability: Using SiC MOSFET power modules with a switching frequency ≥40kHz and a junction temperature ≥175℃, the switching loss is reduced by more than 60%, the system efficiency is increased to more than 95%, and the reliability under high temperature environment is greatly improved, with a mean time between failures (MTBF) ≥15000 hours. Precise and stable control: The dual Sinc filter banks in the control module process data in parallel, realizing μs-level overcurrent protection and high-precision rotor position calculation (error <0.5°). Strong adaptability: Through the viscosity-adaptive pressure control algorithm (viscosity-PID), the control parameters can be automatically tuned according to the viscosity of the medium, effectively coping with load fluctuations.

[0070] It should be noted that the principle behind solving the problem in the above-mentioned liquid pump control system is the same as that described earlier. Figures 1-2 The embodiments are similar, so the implementation of this embodiment can refer to the description in the embodiments of the above system, and the repeated parts will not be repeated.

[0071] Optionally, please refer to Figure 3 , Figure 3 This is a flowchart illustrating a liquid pump control method provided in an embodiment of this application. The method is applied to the liquid pump control system in any of the above embodiments and may include steps S210-S230.

[0072] Step S210: The motor of the liquid pump is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data.

[0073] Step S220: The control module drives the high-frequency power module to operate at high frequency based on the sampled data.

[0074] In step S230, the motor is controlled by executing a multi-segment overmodulation strategy through the high-frequency power module.

[0075] exist Figure 3In the illustrated embodiment, the high-precision signal acquisition of the high-precision sampling module and the high-frequency and high-efficiency power drive of the high-frequency power module fundamentally improve the working performance of the liquid pump, enabling heavy-load start-up at ultra-low frequencies. This allows the liquid pump to reliably cope with various special operating conditions, reduces the current required for start-up, improves voltage utilization, enhances the overall efficiency of the system, and increases reliability under high-temperature conditions, thereby improving the reliability, stability, and safety of the liquid pump.

[0076] Since the principle of the liquid pump control method in this application embodiment is similar to that of the aforementioned liquid pump control system embodiment, the implementation of the method in this embodiment can refer to the description in the above system embodiment, and the repeated parts will not be repeated.

[0077] Optionally, please refer to Figure 4 , Figure 4 The following is a detailed flowchart of step S220 provided in an embodiment of this application, wherein the control module may include a filter and a controller, and step S220 may include steps S221-S225.

[0078] Step S221: Overcurrent detection is performed based on the received sampled data through the first filter.

[0079] Step S222: The received sampled data is filtered by the second filter to obtain filtered data.

[0080] Step S223: The controller processes the filtered data based on the detection algorithm to determine the rotor position of the motor.

[0081] Step S224: Using the controller, when the operating frequency of the liquid pump is less than or equal to the preset low-frequency operating frequency and greater than or equal to the starting frequency, the initial torque of the motor is determined based on the rotor position.

[0082] Step S225: Using the controller, when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency, determine whether the liquid pump is stable based on the rotor position. If the liquid pump is determined to be stable, switch from open-loop control mode to closed-loop control mode.

[0083] Optionally, the first and second filters can be configured as a dual filter bank, balancing response speed and accuracy, to process high-bandwidth (OSR=8) and high-precision (OSR=256) data streams in the sampled data in parallel. The high-speed path (OSR=8) is used for μs-level overcurrent protection; the high-precision path (OSR=256) is used for the control loop, with a response delay of <2μs, to ensure that the error of the final rotor position is less than the preset error threshold.

[0084] Optionally, the specific method for determining whether the liquid pump is stable may include: comparing the position error with a preset error threshold using the controller; if the position error is determined to be less than the error threshold, adding a stability count using the controller; if the position error is determined to be greater than or equal to the error threshold, resetting the stability count to zero using the controller; if the total stability count is determined to be greater than or equal to a preset count threshold, determining that the liquid pump is stable using the controller; if the total stability count is determined to be less than the preset count threshold, determining that the liquid pump is unstable using the controller. To improve the effectiveness of determining whether the liquid pump is stable and reduce erroneous judgments caused by sudden data changes, when the controller determines that the current position error is less than the error threshold, it indicates that the current error is small, and a stability count can be added based on an internally set counter. For example, incrementing the count by 1 each time the position error is less than the error threshold. When the controller determines that the current position error is greater than or equal to the error threshold, it indicates that the current error is large, and the stability count in the counter can be reset to zero. The preset counting threshold can be set according to the determination period of position error, actual conditions, and requirements. For example, it can be set to 3. If the current median stable count is greater than or equal to the preset counting threshold, it indicates that the position error detected by the liquid pump for more than three consecutive times is small, meaning that the liquid pump has been in a stable operating state for a relatively long time, and thus the liquid pump is determined to be stable. If the current median stable count is less than the preset counting threshold, it indicates that the liquid pump is in a state transition or in an unstable state for a long time, and thus the liquid pump is determined to be unstable. This method can comprehensively determine the state status at multiple consecutive moments by counting, effectively improving the reliability of the determination result of whether the liquid pump is stable, thereby improving the effectiveness of control mode switching based on the determination result.

[0085] exist Figure 4In the illustrated embodiment, the control module includes a corresponding filter bank and controller. The filters perform overcurrent protection and filtering on the received sampled data, allowing for sampling and reconstruction to obtain more accurate filtered data. The controller processes the filtered data based on a detection algorithm to estimate the rotor position in the motor. For adaptive control at different frequencies, the controller compares the current operating frequency of the liquid pump with a preset low-frequency operating frequency and a starting frequency. When the operating frequency is less than or equal to the preset low-frequency operating frequency but greater than or equal to the starting frequency, the initial torque of the motor can be determined based on the determined rotor position to overcome static friction. When the operating frequency rises above the preset low-frequency operating frequency, the rotor position determines whether the liquid pump is in a stable operating state. If the liquid pump is stable, the control can switch from open-loop to closed-loop mode for stable operation as the operating frequency steadily increases, optimizing the control effect. By extracting more accurate filtered data through data filtering, executing high-precision algorithms based on the filtered data, and setting different frequency ranges to achieve different types of control, the effectiveness and reliability of the control are improved.

[0086] Alternatively, considering the effect of pressure on the liquid pump during internal control of the liquid, please refer to... Figure 5 , Figure 5 This is a flowchart illustrating another liquid pump control method provided in an embodiment of this application. The method may further include steps S241-S244.

[0087] Step S241: Detect the first inlet pressure information before the liquid pump starts using a pressure sensor.

[0088] Step S242: The controller compares the first inlet pressure information with the first preset pressure threshold. If the first inlet pressure information is determined to be less than the first preset pressure threshold, a stop-start command is generated.

[0089] If the first inlet pressure is less than the first preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low and it may not work properly after startup. Therefore, a corresponding stop-start command can be generated to pause the startup operation and start normally again after the pressure reaches the target level.

[0090] Step S243: The pressure sensor detects the second inlet pressure information during the operation of the liquid pump.

[0091] Step S244: The controller compares the second inlet pressure information with the second preset pressure threshold. If the second inlet pressure information is determined to be less than the second preset pressure threshold, a fault shutdown command is generated.

[0092] Specifically, the liquid pump is only allowed to start and enter the operation process if the first inlet pressure is greater than or equal to the first preset pressure threshold. If the second inlet pressure is less than the second preset pressure threshold, it indicates that the current inlet pressure of the liquid pump is too low, which may indicate an abnormal fault. Therefore, a corresponding fault shutdown command can be generated to notify the personnel to carry out maintenance and other procedures on the liquid pump, so that the liquid pump can operate reliably under normal pressure.

[0093] Optionally, the first preset pressure threshold and the second preset pressure threshold can be set according to the actual situation and requirements of the liquid pump. For example, the first preset pressure threshold can be set to 0.1 MPa and the second preset pressure threshold can be set to 0.08 MPa.

[0094] It should be noted that in this embodiment of the application, the pump inlet pressure is continuously monitored before and during the operation of the liquid pump. If the pressure is insufficient, the pump must not be started. If the pressure is too low during operation, the pump must be stopped immediately. This effectively prevents the pump body from being damaged by dry running due to cavitation and protects the equipment assets.

[0095] exist Figure 5 In the described embodiment, pressure detection can be performed at different operating points of the liquid pump to determine the actual state of the liquid pump based on the detected inlet pressure, thereby generating corresponding commands for control and improving the safety of the liquid pump operation.

[0096] Optionally, please refer to Figure 6 , Figure 6 This is a flowchart illustrating another liquid pump control method provided in an embodiment of this application. The method may further include steps S251-S253.

[0097] Step S251: The controller determines the phase change of the motor's current waveform based on the filtered data.

[0098] In the constant pressure control stage of the closed-loop control mode, in order to maintain a stable pressure for the liquid pump, the controller can determine the phase change of the motor current waveform based on the filtered data.

[0099] Optionally, the controller can activate a visibility-PID algorithm to maintain constant pressure, determine the three-phase current of the motor from the filtered data, and calculate the corresponding phase change based on the current waveform of the three-phase current, denoted as... .

[0100] Step S252: The controller determines the type of medium in the liquid pump based on the phase change.

[0101] Since the phase change can reflect the change in motor current, and the liquid medium controlled in the liquid pump can affect the change in current, the controller can determine the type of liquid medium controlled in the liquid pump based on the phase change.

[0102] Optionally, based on the historical data of the liquid pump, one or more phase change thresholds can be determined to characterize the viscosity of the liquid medium. Taking a phase change threshold as an example, the phase change is compared with the phase change threshold. If the phase change is greater than or equal to the phase change threshold, the liquid medium is characterized as having a high viscosity, and the corresponding medium type is a polymer. If the phase change is less than the phase change threshold, the liquid medium is characterized as having a low viscosity, and the corresponding medium type is water.

[0103] Step S253: The controller determines the target parameter set in the preset parameter table based on the medium type, and controls the pressure in the liquid pump based on the target parameter set.

[0104] Among them, based on the medium type, the corresponding target parameter group can be determined in the preset parameter table with multiple different medium types, so as to control the pressure in the liquid pump based on the target parameter group and ensure that a control accuracy of ±0.1MPa can be obtained under different types of liquid media.

[0105] Optionally, the preset parameter table has parameter groups corresponding to various media types, and multiple parameter groups are set based on historical data. For example, the preset parameter table may include high-viscosity PID parameter groups and low-viscosity PID parameter groups to adapt to liquid media of polymer type and clear water type, respectively.

[0106] Optionally, the controller can also directly determine the viscosity of the liquid medium in the liquid pump from the flow rate collected by the set flow meter, so as to select an appropriate set of target parameters for control based on the viscosity.

[0107] exist Figure 6 In the illustrated embodiment, the type of liquid medium can be deduced from the actual condition of the motor, thereby selecting appropriate parameters for control based on different types of media, achieving the technical effect of adaptive control based on changes in medium viscosity, and effectively improving the reliability of constant pressure.

[0108] Optionally, please refer to Figure 7 , Figure 7This is a waveform timing diagram provided in an embodiment of this application. While the traditional SPWM modulation wave on the left has good sinusoidal strength, its output voltage amplitude is limited, torque ripple is large, and energy consumption is high. The right side shows the five-segment overmodulation strategy used in this embodiment. To fully utilize the high-frequency performance of SiC devices, this application uses a five-segment overmodulation strategy. This algorithm reconstructs the modulation wave and dynamically compresses the dead time, inserting a zero vector (V0) within a 120° interval to smooth the waveform, forming a five-segment sequence composed of effective vectors (V1, V2) and a zero vector (V0). This results in stable torque, high efficiency, and a higher fundamental voltage amplitude under the same DC bus voltage (increasing voltage utilization to 98%). This allows motors in liquid pumps such as water pumps to obtain greater torque, operate more smoothly, and achieve higher efficiency.

[0109] In summary, the liquid pump control system and method provided in this application effectively reduce the minimum starting frequency of the liquid pump, lowering it from 5-10Hz to below 0.3Hz, achieving ultra-low frequency starting, reducing the peak current required for starting, and improving pressure control accuracy, system efficiency, and system reliability at high temperatures.

[0110] In the several embodiments provided in this application, it should be understood that the disclosed device can also be implemented in other ways. The system embodiments described above are merely illustrative; for example, the block diagrams in the accompanying drawings show the architecture, functionality, and operation of possible implementations of the device according to various embodiments of this application. In this regard, each block in the block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram, and combinations of block diagrams, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0111] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0112] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0113] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0114] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

[0115] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A liquid pump control system, characterized in that, The system includes: a high-precision sampling module, a high-frequency power module, and a control module; The control module is connected to the high-precision sampling module and the high-frequency power module; The high-precision sampling module is used to sample the motor of the liquid pump based on the oversampling rate to obtain sampling data; The control module is used to drive the high-frequency power module to operate at high frequency based on the sampled data; The high-frequency power module is used to execute a multi-segment overmodulation strategy to control the motor.

2. The system according to claim 1, characterized in that, The high-precision sampling module includes a Σ-Δ modulator, and the high-frequency power module includes a SiC inverter power module.

3. The system according to claim 2, characterized in that, in, The Σ-Δ modulator has an oversampling rate OSR ≥ 256 and an effective number of bits ENOB ≥ 14.

4. The system according to claim 2, characterized in that, The SiC inverter power module is equipped with multiple SiC MOSFETs, and the switching frequency of the SiC inverter power module is ≥40kHz, and the junction temperature is ≥175℃.

5. The system according to claim 2, characterized in that, in, The starting frequency of the motor by the SiC inverter power module is ≤0.3Hz.

6. The system according to any one of claims 1-5, characterized in that, The control module includes: a first filter, a second filter, and a controller; The first filter is used to perform overcurrent detection based on the received sampled data; The second filter is used to filter the received sampled data to obtain filtered data; The controller is used to process the filtered data based on a detection algorithm to determine the rotor position of the motor; when the operating frequency of the liquid pump is less than or equal to a preset low-frequency operating frequency and greater than or equal to the starting frequency, it determines the initial torque of the motor based on the rotor position; when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency, it determines whether the liquid pump is stable based on the rotor position; if the liquid pump is determined to be stable, it switches from open-loop control mode to closed-loop control mode.

7. The system according to claim 6, characterized in that, The system also includes: a pressure sensor; The pressure sensor is connected to the controller; The pressure sensor is used to detect the first inlet pressure information before the liquid pump starts; The controller is used to compare the first inlet pressure information with a first preset pressure threshold. If it is determined that the first inlet pressure information is less than the first preset pressure threshold, a stop-start command is generated. The pressure sensor is also used to detect the second inlet pressure information during the operation of the liquid pump; The controller is also used to compare the second inlet pressure information with a second preset pressure threshold. If it is determined that the second inlet pressure information is less than the second preset pressure threshold, a fault shutdown command is generated.

8. A liquid pump control method, characterized in that, The method is applied to the liquid pump control system according to any one of claims 1-7, and the method includes: The motor of the liquid pump is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data; The control module drives the high-frequency power module to operate at high frequency based on the sampled data. The motor is controlled by executing a multi-segment overmodulation strategy through a high-frequency power module.

9. The method according to claim 8, characterized in that, in, The control module includes: a first filter, a second filter, and a controller; The step of driving the high-frequency power module to operate at high frequency based on the sampled data via the control module includes: Overcurrent detection is performed based on the received sampled data using the first filter; The received sampled data is filtered using the second filter to obtain filtered data. The controller processes the filtered data based on a detection algorithm to determine the rotor position of the motor. The controller determines the initial torque of the motor based on the rotor position when the operating frequency of the liquid pump is less than or equal to a preset low-frequency operating frequency and greater than or equal to the starting frequency. The controller determines whether the liquid pump is stable based on the rotor position when the operating frequency of the liquid pump is greater than the preset low-frequency operating frequency. If the liquid pump is determined to be stable, the controller switches from open-loop control mode to closed-loop control mode.

10. The method according to claim 9, characterized in that, The system also includes: a pressure sensor; The method further includes: The pressure sensor detects the first inlet pressure information before the liquid pump starts. The controller compares the first inlet pressure information with a first preset pressure threshold. If the first inlet pressure information is determined to be less than the first preset pressure threshold, a stop-start command is generated. The pressure sensor detects the second inlet pressure information during the operation of the liquid pump. The controller compares the second inlet pressure information with a second preset pressure threshold. If the second inlet pressure information is determined to be less than the second preset pressure threshold, a fault shutdown command is generated.

11. The method according to claim 9, characterized in that, The method further includes: The controller determines the phase change of the motor's current waveform based on the filtered data. The controller determines the type of medium in the liquid pump based on the phase change. The controller determines a target parameter set from a preset parameter table based on the medium type, and controls the pressure in the liquid pump based on the target parameter set; wherein the preset parameter table has parameter sets corresponding to various medium types.

12. A liquid pump control system, characterized in that, The system includes: a Σ-Δ modulator, a SiC inverter power module, and a control module; The control module is connected to the Σ-Δ modulator and the SiC inverter power module; The Σ-Δ modulator is used to sample the motor of the liquid pump based on the oversampling rate to obtain sampled data; The control module is used to drive the SiC inverter power module to operate at high frequency based on the sampled data; The SiC inverter power module is used to control the motor by executing a multi-segment overmodulation strategy.

Images