Pumping unit control system and method

Abstract

The invention provides a pumping unit control system and method, and relates to the technical field of oil field oil extraction equipment control. According to the system, a control module is connected with a high-precision sampling module and a high-frequency power module; the high-precision sampling module is used for sampling the oil pumping unit based on the oversampling rate to obtain sampling data; the control module is used for determining state data of the oil pumping unit based on the sampling data and switching between an open-loop control mode and a closed-loop control mode based on the state data; and the high-frequency power module is used for starting a motor of the oil pumping unit in a closed-loop control mode. The high-precision sampling module and the high-frequency power module are cooperated to work, so that the working performance of the oil pumping unit is fundamentally improved, flexible starting of the oil pumping unit can be realized, heavy-load starting can be realized at ultra-low frequency, and the oil pumping unit can be effectively controlled on the basis that the original unit installed power of the oil pumping unit is not increased or even reduced. And strong instantaneous overload capacity is provided for the oil pumping unit, so that the oil pumping unit can reliably cope with various special working conditions.

Description

Technical Field

[0001] This application relates to the field of oilfield production equipment control technology, and more specifically, to a pumping unit control system and method. Background Technology

[0002] Currently, the variable frequency control system for oilfield pumping units generally adopts a technical architecture of "IGBT (Insulated Gate Bipolar Transistor) inverter + sampling circuit based on Hall sensor or isolation amplifier + back EMF observation algorithm". Its core principle is as follows: the motor current is collected by a sensor, and after signal conditioning circuitry, it is converted into a digital signal by an ADC; the controller estimates the rotor position and speed through a back EMF observer, and outputs a PWM (Pulse Width Modulation) wave to drive the IGBT inverter bridge.

[0003] In existing technologies, the frequency conversion control system of oilfield pumping units typically includes voltage-adaptive permanent magnet motors, CNC supercritical pumping units, and dedicated frequency converters for pumping units. However, because the back electromotive force (EMF) amplitude is proportional to the motor speed, when the operating frequency is low, the back EMF signal amplitude is too small, falling below the effective threshold of the detection circuit. This leads to a sharp deterioration in the signal-to-noise ratio, making it impossible for the observer to accurately identify the rotor position. Consequently, the minimum starting frequency is limited. At low speeds, especially during startup, the system output torque is insufficient and fluctuates significantly, making it difficult to reliably overcome the enormous static friction and unbalanced loads of the pumping unit. This can easily cause starting shocks, overcurrent protection failures, or startup failures. When starting and adjusting the position under heavy unbalanced loads, additional auxiliary equipment is often required to complete the startup under heavy load conditions. Furthermore, existing systems generally use silicon-based IGBT power devices, which have high switching frequencies, large switching losses, low overall system efficiency, and severe heat generation. Derated operation is required in high-temperature environments, leading to reduced reliability and increased failure rates. The poor performance of the frequency conversion control system for oilfield pumping units affects the continuous and stable operation of the pumping unit. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a pumping unit control system and method to improve the problem of poor operating performance of the frequency conversion control system for oilfield pumping units in the prior art.

[0005] To address the aforementioned issues, in a first aspect, embodiments of this application provide a pumping unit control system, the 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 pumping unit based on the oversampling rate to obtain sampling data; The control module is used to determine the status data of the pumping unit based on the sampled data, and to switch between open-loop control mode and closed-loop control mode based on the status data. The high-frequency power module is used to start the motor of the oil pumping unit in the closed-loop control mode.

[0006] In the above implementation process, the pumping unit control system can be equipped with a high-precision sampling module with high sampling accuracy. This module can obtain high-precision sampling data without a physical position encoder. Based on this data, the control module determines the pumping unit's state data and switches between open-loop and closed-loop control modes to achieve high-performance closed-loop control across the entire speed range. Furthermore, considering the limited minimum starting frequency of the pumping unit at low operating frequencies, a high-frequency power module can be used to start the pumping unit's motor in closed-loop control mode, achieving ultra-low frequency closed-loop control. The high-precision signal acquisition of the high-precision sampling module and the high-frequency, high-efficiency power drive of the high-frequency power module fundamentally improve the working performance of the pumping unit. It not only enables the pumping unit to start flexibly, but also to start under heavy load at ultra-low frequencies. It can provide the pumping unit with strong instantaneous overload capacity without increasing or even reducing the original unit's installed power, enabling the pumping unit to reliably cope with a variety of special operating conditions. It meets the instantaneous high torque output requirements of the motor in various application scenarios and under various operating conditions, reduces the equipment investment and energy waste caused by blindly increasing the rated power of the motor to cope with occasional operating conditions, and improves the reliability, stability and safety of the pumping unit.

[0007] Optionally, the high-precision sampling module includes a Σ-Δ modulator, and the high-frequency power module includes a SiC inverter power module.

[0008] 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 losses compared to existing IGBT devices, effectively improving startup efficiency and providing a control basis for accurate closed-loop control algorithms.

[0009] Optionally, the oversampling rate OSR of the Σ-Δ modulator is ≥256, and the effective number of bits ENOB is ≥14.

[0010] 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.

[0011] 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℃.

[0012] 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 the high temperature environment. The high temperature resistance significantly improves the reliability of the pumping unit operation.

[0013] Optionally, in the closed-loop control mode, the starting frequency of the motor started by the SiC inverter power module is ≤0.5Hz.

[0014] In the above implementation process, under the closed-loop control mode, 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 pumping unit motor at an ultra-low start-up frequency, so that the system can stably enter the closed-loop control mode at the ultra-low start-up frequency point and achieve ultra-low frequency start-up.

[0015] Optionally, the control module includes: a filter and a controller; The 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 state data of the pumping unit; wherein the state data includes the rotor position of the motor; the detection algorithm includes a phase-locked loop algorithm or a sliding mode observer algorithm; the controller calculates the position error based on the state data; the controller compares the position error with a preset error threshold to determine whether the pumping unit is stable; and if the pumping unit is stable, the controller switches from the open-loop control mode to the closed-loop control mode.

[0016] In the above implementation process, the control module is equipped with corresponding filters and controllers. The filters can filter the received sampled data to sample and reconstruct the data, obtaining more accurate filtered data. The controller can process the filtered data based on various detection algorithms to estimate the rotor position in the pumping unit's motor, obtain the corresponding state data, calculate the position error based on the state data, and compare it with a preset error threshold to determine whether the pumping unit is in a stable operating state. Only when the pumping unit is stable will the control switch from open-loop control mode to closed-loop control mode. The system can extract more accurate filtered data through data filtering and execute high-precision algorithms based on the filtered data to improve the effectiveness and reliability of control mode switching.

[0017] Optionally, the open-loop control mode includes a V / F open-loop control mode; the closed-loop control mode includes a closed-loop control mode based on the FOC control algorithm.

[0018] In the above implementation process, the open-loop control mode can include a V / F open-loop control mode to maintain a constant ratio of voltage V to frequency F. This allows for constant air gap flux of the pumping unit motor at different frequencies, with the voltage varying proportionally with frequency. The control module can directly output a three-phase sinusoidal signal with a given frequency and voltage to the high-frequency power module to drive the motor. This approach involves low computational load and low control cost. The closed-loop control mode can include a closed-loop control mode based on the FOC control algorithm. This mode can decouple the motor's three-phase AC current into two independent DC components—the excitation current component and the torque current component—through coordinate transformation. These two components are then precisely controlled in a closed loop, resulting in high control accuracy.

[0019] Secondly, this application also provides a method for controlling an oil pumping unit, the method being applied to the oil pumping unit control system described in any one of the first aspects, the method comprising: The pumping unit is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data; The control module determines the status data of the pumping unit based on the sampled data, and switches between open-loop control mode and closed-loop control mode based on the status data. The pumping unit's motor is started using a high-frequency power module in the closed-loop control mode.

[0020] In the aforementioned implementation process, high-precision sampling data obtained through a high-precision sampling module can be used without a physical position encoder. The control module then determines the pumping unit's status data based on this sampling data, switching between open-loop and closed-loop control modes accordingly. This achieves high-performance closed-loop control across the entire speed range. Furthermore, considering the limited minimum start-up frequency of the pumping unit at lower operating frequencies, a high-frequency power module can be used to start the pumping unit's motor in closed-loop control mode, enabling ultra-low-frequency closed-loop control. The high-precision signal acquisition by the high-precision sampling module, combined with the high-frequency, high-efficiency power drive of the high-frequency power module, fundamentally improves the pumping unit's performance.

[0021] Optionally, the control module includes: a filter and a controller; The step of determining the status data of the pumping unit based on the sampled data through the control module, and switching between open-loop control mode and closed-loop control mode based on the status data, includes: The received sampled data is filtered using the filter to obtain filtered data. The controller processes the filtered data based on a detection algorithm to determine the state data of the pumping unit; wherein the state data includes the rotor position of the motor; the detection algorithm includes a phase-locked loop algorithm or a sliding mode observer algorithm. The controller calculates the position error based on the state data. The controller compares the preset error threshold with the position error to determine whether the pumping unit is stable. If the pumping unit is determined to be stable, the controller switches from the open-loop control mode to the closed-loop control mode.

[0022] In the above implementation process, the control module is equipped with corresponding filters and controllers. The filters process the received sampled data to perform sampling and reconstruction, resulting in more accurate filtered data. The controller processes the filtered data using various detection algorithms to estimate the rotor position in the pumping unit's motor, obtaining corresponding state data. The position error is calculated based on this state data and compared with a preset error threshold to determine if the pumping unit is in a stable operating state. Only when the pumping unit is stable does the controller switch from open-loop control mode to closed-loop control mode. This data filtering method extracts more accurate filtered data, and high-precision algorithms are executed based on this data to improve the effectiveness and reliability of control mode switching.

[0023] Optionally, determining whether the pumping unit is stable by comparing a preset error threshold with the position error using the controller includes: The controller compares the position error with a preset error threshold. If the position error is determined to be less than the error threshold, then a stable count is added via the controller; If the position error is determined to be greater than or equal to the error threshold, the controller will reset the stability count to zero. If the total stable count value is determined to be greater than or equal to the preset count threshold, the controller determines that the pumping unit is stable. If the total stable count is less than the preset count threshold, the controller determines that the pumping unit is unstable.

[0024] In the above implementation process, to improve the effectiveness of determining whether the pumping unit is stable and reduce erroneous judgments caused by sudden data changes, the controller determines that if the current position error is less than the error threshold, it indicates that the current error is small, and a stable count can be added based on the internally set counter. If 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 stable count in the counter can be cleared. If the median value of the current stable count is greater than or equal to the preset count threshold, it indicates that the pumping unit has been in a stable operating state for a relatively long time, i.e., the pumping unit is determined to be stable. If the median value of the current stable count is less than the preset count threshold, it indicates that the pumping unit is in a state transition or a long-term unstable state, i.e., the pumping unit is determined to be unstable. This method of counting to make an overall judgment on the state status at multiple consecutive moments effectively improves the reliability of the pumping unit stability determination result, thereby improving the effectiveness of control mode switching based on the determination result.

[0025] Optionally, the method further includes: The controller is used to determine the suspension point load curve of the pumping unit; The controller determines the torque feedforward command based on the suspension point load curve. The controller adjusts the torque command based on the torque feedforward command.

[0026] In the above implementation process, to eliminate control jitter and reduce the current required for low-frequency startup, the suspension point load curve of the pumping unit can be determined by the controller. Based on this curve, a corresponding torque feedforward command can be determined, thereby adjusting the torque command during control. This load prediction-based control adjustment reduces torque abrupt changes and improves the reliability of ultra-low frequency startup and the smoothness of mode switching.

[0027] Optionally, determining the torque feedforward command based on the suspension point load curve via the controller includes: The controller determines the crank angle of the pumping unit; The controller determines the required torque based on the crank angle and the suspension point load curve. The controller generates the torque feedforward command based on the required torque.

[0028] In the above implementation process, the controller can determine the current crank angle of the pumping unit, and based on the crank angle and the suspension point load curve, calculate the actual torque required. Then, based on the required torque, it generates a corresponding torque feedforward command to adjust the motor control of the pumping unit. Through the torque feedforward command, the torque output of the pumping unit's motor can be matched as smoothly as possible with the torque required by the change in suspension point load, thereby minimizing energy fluctuations and improving the efficiency and stability of the pumping unit.

[0029] Thirdly, embodiments of this application also provide a pumping unit 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 pumping unit based on the oversampling rate to obtain sampled data; The control module is used to determine the status data of the pumping unit based on the sampled data, and to switch between open-loop control mode and closed-loop control mode based on the status data. The SiC inverter power module is used to start the motor of the oil pumping unit in the closed-loop control mode.

[0030] In the above implementation process, without the need for a physical position encoder, the control module can determine the pumping unit's status data based on high-precision sampling data obtained from a Σ-Δ modulator. This status data allows for switching between open-loop and closed-loop control modes, achieving high-performance closed-loop control across the entire speed domain. Furthermore, considering the limited minimum start-up frequency of the pumping unit at lower operating frequencies, a dedicated SiC inverter power module can be used to start the pumping unit's motor in closed-loop control mode, enabling ultra-low frequency closed-loop control. The synergistic use of Σ-Δ ultra-high precision sampling technology and SiC high-frequency high-efficiency power technology fundamentally improves the performance of the pumping unit. It not only enables flexible start-up of the pumping unit but also heavy-load start-up at ultra-low frequencies. It provides the pumping unit with strong instantaneous overload capacity without increasing or even reducing the original installed power of the pumping unit, enabling the pumping unit to reliably cope with a variety of special operating conditions. It meets the instantaneous high torque output requirements of the motor in various application scenarios and under various operating conditions, reduces the equipment investment and energy waste caused by blindly increasing the rated power of the motor to cope with occasional operating conditions, and improves the reliability, stability and safety of the pumping unit.

[0031] In summary, the embodiments of this application provide a pumping unit 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 pumping unit. It not only enables flexible starting of the pumping unit but also heavy-load starting at ultra-low frequencies. It provides the pumping unit with strong instantaneous overload capacity without increasing or even reducing its original installed power, allowing it to reliably cope with various special operating conditions. This meets the demand for instantaneous high torque output from the motor under various operating conditions in multiple application scenarios, reducing equipment investment and energy waste caused by blindly increasing the rated power of the motor to cope with occasional operating conditions, and improving the reliability, stability, and safety of the pumping unit. Attached Figure Description

[0032] 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.

[0033] Figure 1 This is a schematic diagram of the structure of a pumping unit control system provided in an embodiment of this application; Figure 2 This is a schematic diagram of another oil pumping unit control system provided in an embodiment of this application; Figure 3 A flowchart illustrating a pumping unit 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 detailed flowchart of step S224 provided for an embodiment of this application; Figure 6 A schematic flowchart of another oil pumping unit control method provided in an embodiment of this application; Figure 7 This is a detailed flowchart illustrating step S242 provided in an embodiment of this application.

[0034] Icons: 110 - High-precision sampling module; 120 - High-frequency power module; 130 - Control module; A - Pumping unit; 131 - Filter; 132 - Controller. Detailed Implementation

[0035] 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.

[0036] Existing variable frequency control systems for oilfield pumping units generally adopt a technical architecture of "IGBT inverter + sampling circuit based on Hall sensor or isolation amplifier + back EMF observation algorithm". Its core principle is: the motor current is collected by a sensor, and after signal conditioning circuitry, it is converted into a digital signal by an ADC; the controller estimates the rotor position and speed through a back EMF observer and outputs a PWM wave to drive the IGBT inverter bridge. Current variable frequency control systems for oilfield pumping units typically include voltage-adaptive permanent magnet motors, CNC supercritical pumping units, and dedicated frequency converters for pumping units. However, because the back EMF amplitude is proportional to the motor speed, when the operating frequency is low, the back EMF signal amplitude is too small, falling below the effective threshold of the detection circuit, causing a sharp deterioration in the signal-to-noise ratio. This results in the observer being unable to accurately identify the rotor position, thus limiting the minimum starting frequency, which is typically no less than 3% of the rated frequency, such as 1.5Hz, making ultra-low frequency closed-loop control impossible. At low speeds, especially during startup, the system output torque is insufficient and fluctuates significantly, making it difficult to reliably overcome the enormous static friction and unbalanced loads (e.g., ≥3 tons or unbalance rate ≥15%) present in the pumping unit. This easily leads to startup shocks, overcurrent protection failures, or startup failures. When starting and adjusting the position under heavy unbalanced loads, additional auxiliary equipment is often required to complete startup under heavy load conditions. Furthermore, existing systems generally use silicon-based IGBT power devices, which have high switching frequencies, large switching losses, low overall system efficiency, and severe heat generation. Derated operation is required in high-temperature environments, leading to reduced reliability and increased failure rates. During pumping unit operation, issues such as loss of synchronization and vibration at extremely low speeds, as well as high starting current, result in poor performance of the oilfield pumping unit's frequency converter control system, affecting the continuous and stable operation of the pumping unit.

[0037] To address the aforementioned issues, this application provides a pumping unit control system and method. By coordinating high-precision signal acquisition from a high-precision sampling module with high-frequency, high-efficiency power drive from a high-frequency power module, the system fundamentally improves the pumping unit's performance. It enables not only flexible startup but also heavy-load startup at ultra-low frequencies. Furthermore, it provides the pumping unit with powerful instantaneous overload capacity without increasing or even reducing its original installed power, allowing it to reliably handle various special operating conditions. This meets the demand for instantaneous high torque output from the motor under diverse application scenarios and conditions, reducing equipment investment and energy waste caused by blindly increasing the motor's rated power to cope with occasional operating conditions, and improving the reliability, stability, and safety of the pumping unit.

[0038] Please see Figure 1 , Figure 1 This is a schematic diagram of the structure of a pumping unit control system provided in an embodiment of this application. The system may include: a high-precision sampling module 110, a high-frequency power module 120, and a control module 130.

[0039] 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 controlled pumping unit A.

[0040] 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). It 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 other structure installed in the pumping unit 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.

[0041] The high-precision sampling module 110 is used to sample pumping unit A based on the oversampling rate to obtain sampled data. The control module 130 is used to determine the state data of pumping unit A based on the sampled data and to switch between open-loop control mode and closed-loop control mode based on the state data. The high-frequency power module 120 is used to start the motor of pumping unit A in closed-loop control mode. The pumping unit control system can be equipped with a high-precision sampling module 110, which, without a physical position encoder, uses the high-precision sampled data obtained by the high-precision sampling module 110 to determine the state data of pumping unit A. The control module 130 then switches between open-loop control mode and closed-loop control mode based on the state data, thereby achieving high-performance closed-loop control across the entire speed range. Furthermore, considering that the minimum starting frequency of pumping unit A is limited when the operating frequency is low, the high-frequency power module 120 can be used to start the motor of pumping unit A in closed-loop control mode to achieve ultra-low frequency closed-loop control.

[0042] 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.

[0043] 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 control basis for accurate closed-loop control algorithms.

[0044] Optionally, the Σ-Δ modulator can acquire the motor phase current and position sensor signals of the pumping unit 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.

[0045] 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 a Σ-Δ modulator can resolve is approximately... 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.

[0046] 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 motor of pumping unit 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 motor current waveform, reducing torque ripple and motor heating, thereby reducing noise during pumping unit A's operation and allowing pumping unit A to respond more quickly to load and command changes, thus improving the dynamic performance of pumping unit A. Furthermore, the junction temperature of the SiC inverter power module is ≥175℃, which is suitable for various high-temperature operating environments. The high-temperature resistance significantly improves the reliability of the operation of the pumping unit A.

[0047] 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.

[0048] 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.

[0049] 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 and filter 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.

[0050] Optionally, in closed-loop control mode, the starting frequency of the motor started by the SiC inverter power module is ≤0.5Hz. 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 motor of the pumping unit A at an ultra-low starting frequency, so that the system can stably enter the closed-loop control mode at an ultra-low starting frequency point, achieving ultra-low frequency start-up.

[0051] For example, compared with the lowest startup frequency of 1.5Hz in the prior art, the lowest startup frequency of this application is ≤0.5Hz, which can achieve a truly ultra-low frequency heavy-load startup and improve efficiency by more than 67%.

[0052] Optionally, please refer to Figure 2 , Figure 2 This is a schematic diagram of another oil pumping unit control system provided in an embodiment of this application, wherein the control module 130 may include a filter 131 and a controller 132.

[0053] Optionally, filter 131 connects to high-precision sampling module 110 and controller 132. Filter 131 is used to filter the received sampling data to obtain filtered data. Controller 132 is used to process the filtered data based on a detection algorithm to determine the state data of pumping unit A. The state data may include the rotor position of the motor. The detection algorithm may include a phase-locked loop algorithm or a sliding mode observer algorithm. The controller calculates the position error based on the state data. It compares the position error with a preset error threshold to determine whether pumping unit A is stable. If pumping unit A is stable, it switches from open-loop control mode to closed-loop control mode.

[0054] For example, filter 131 can be filter, Filters can decode and downsample sampled data to convert the sampled data of the bitstream into filtered data of high-resolution digital code. The filter can provide good anti-aliasing and noise suppression functions through its notch characteristics, and has good anti-PWM interference capability, effectively improving the accuracy and effectiveness of the filtered data.

[0055] For example, the controller 132 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 state data may include the rotor position and real-time current signal of pumping unit A motor. A phase-locked loop (PLL) algorithm can compare the phase error between the input back electromotive force (EMF) signal (or a signal related to the back EMF) and the position estimate output by the PLL itself to determine a smooth and highly accurate rotor position estimate as the rotor position. A sliding mode observer (SMO) algorithm can establish a current observation model based on the motor's state equations. 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 includes 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] Optionally, at the control algorithm level, in addition to phase-locked loop (PLL) and sliding mode observer (SMO), the rotor position detection algorithm can also include other types of algorithms that can realize rotor position identification at low speed, such as high-frequency signal injection method and flux linkage observer algorithm. Observation algorithms such as model reference adaptive system (MRAS) or extended Kalman filter (EKF) can also be used to estimate rotor position and speed.

[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 motor model, actual situation and requirements. 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 motor rotor position can be determined, thereby determining whether the pumping unit A 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 pumping unit A 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 pumping unit A's motor 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. This reduces the computational load and lowers the control cost. The closed-loop control mode can include a closed-loop control mode based on the FOC control algorithm. This mode can decouple the motor's three-phase AC current into two independent DC components—the excitation current component and the torque current component—through coordinate transformation. These two components are then precisely controlled in a closed loop, resulting in high control accuracy.

[0061] Optionally, during startup control, a DC current can be injected to fix the rotor in the initial position, enabling the initial V / F open-loop control mode, and the startup frequency can be slowly increased to 0.5Hz at a slope of 0.1Hz / s.

[0062] Optionally, this application also provides a pumping unit control system, the system including: 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 pumping unit based on the oversampling rate to obtain sampled data; the control module is used to determine the state data of the pumping unit based on the sampled data, and to switch between open-loop control mode and closed-loop control mode based on the state data; the SiC inverter power module is used to start the motor of the pumping unit in closed-loop control mode. 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 0.5Hz from strong noise background; at the same time, by using a SiC inverter power module and setting its switching frequency ≥40kHz, not only is the switching loss significantly reduced, but its high-frequency characteristics also provide a foundation for realizing accurate closed-loop control algorithms. This application is the first to apply Σ-Δ ultra-high precision sampling technology and SiC high-frequency high-efficiency power technology in synergy to the control system of an oil pumping unit. The two work together to produce an unexpected synergistic effect: that is, without the need for physical position sensors, it can stably and smoothly enter the closed-loop control mode at ultra-low frequencies of ≤0.5Hz, fundamentally solving the industry problem of inaccuracy caused by the deterioration of signal-to-noise ratio in traditional sensorless control at extremely low speeds.

[0063] It should be noted that the problem-solving principle in the above-mentioned oil pumping unit 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.

[0064] Optionally, please refer to Figure 3 , Figure 3 This is a flowchart illustrating a pumping unit control method provided in an embodiment of this application. The method is applied to the pumping unit control system in any of the above embodiments and may include steps S210-S230.

[0065] Step S210: The pumping unit is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data.

[0066] In step S220, the control module determines the status data of the pumping unit based on the sampled data, and switches between open-loop control mode and closed-loop control mode based on the status data.

[0067] In step S230, the pumping unit motor is started in closed-loop control mode via the high-frequency power module.

[0068] exist Figure 3 In the illustrated embodiment, high-precision sampling data obtained through a high-precision sampling module can be used without a physical position encoder. The control module then determines the pumping unit's status data based on this sampling data, switching between open-loop and closed-loop control modes to achieve high-performance closed-loop control across the entire speed range. Furthermore, considering the limited minimum start-up frequency of the pumping unit at lower operating frequencies, a high-frequency power module can be used to start the pumping unit's motor in closed-loop control mode, achieving ultra-low-frequency closed-loop control. The high-precision signal acquisition by the high-precision sampling module, combined with the high-frequency, high-efficiency power drive of the high-frequency power module, fundamentally improves the pumping unit's performance.

[0069] Since the principle of the oil pumping unit control method in this embodiment is similar to that of the aforementioned oil pumping unit 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.

[0070] 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.

[0071] Step S221: The received sampled data is filtered using a filter to obtain filtered data; Step S222: The controller processes the filtered data based on the detection algorithm to determine the status data of the pumping unit.

[0072] The status data may include the rotor position of the motor, and the detection algorithm may include algorithms that can determine the rotor position, such as phase-locked loop algorithm or sliding mode observer algorithm.

[0073] Step S223: Calculate the position error based on the status data using the controller; Step S224: The controller compares the preset error threshold with the position error to determine whether the pumping unit is stable. In step S225, if the pumping unit is determined to be stable, the controller switches from open-loop control mode to closed-loop control mode.

[0074] exist Figure 4 In the illustrated embodiment, the control module includes corresponding filters and a controller. The filters process the received sampled data, allowing for sampling and reconstruction to obtain more accurate filtered data. The controller processes the filtered data using various detection algorithms to estimate the rotor position in the pumping unit's motor, obtaining corresponding state data. Based on this state data, the position error is calculated and compared with a preset error threshold to determine if the pumping unit is in a stable operating state. Only when the pumping unit is stable does the controller switch from open-loop control mode to closed-loop control mode. This data filtering method extracts more accurate filtered data, and high-precision algorithms are executed based on this data to improve the effectiveness and reliability of control mode switching.

[0075] Optionally, please refer to Figure 5 , Figure 5 The following is a detailed flowchart of step S224 provided in an embodiment of this application. Step S224 may include steps S2241-S2245.

[0076] Step S2241: The controller compares the position error with a preset error threshold.

[0077] The preset error threshold can be set according to the motor model, actual situation and requirements. For example, it can be set to 0.5 to determine the deviation of the motor rotor position by comparing the magnitude of the error threshold and the position error.

[0078] In step S2242, if the position error is determined to be less than the error threshold, then a stable count is added through the controller.

[0079] In order to improve the effectiveness of determining whether the pumping unit is stable and reduce erroneous judgment results caused by sudden data changes, the controller determines that when the current position error is less than the error threshold, it indicates that the current error is small. The controller can add a stability count based on the internally set counter. For example, each time the position error is less than the error threshold, the counter is incremented by 1.

[0080] Step S2243: If the position error is determined to be greater than or equal to the error threshold, the stable count is cleared by the controller.

[0081] 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 stable count in the counter can be cleared.

[0082] Step S2244: If the total stable count value is greater than or equal to the preset count threshold, the oil pumping unit is determined to be stable by the controller.

[0083] The preset counting threshold can be set according to the determination period of position error, actual situation and needs. For example, it can be set to 3. If the current stable count median is greater than or equal to the preset counting threshold, it indicates that the position error detected by the pumping unit for more than 3 consecutive times is small, that is, the pumping unit is in a stable operating state for a long time, and the pumping unit is judged to be stable.

[0084] In step S2245, if the total stable count value is less than the preset count threshold, the pumping unit is determined to be unstable by the controller.

[0085] If the current median stable count is less than the preset count threshold, it indicates that the pumping unit is in a state transition or a long-term unstable state, and the pumping unit is determined to be unstable.

[0086] exist Figure 5 In the illustrated embodiment, the state status at multiple consecutive moments can be determined as a whole by counting, which effectively improves the reliability of the determination result of whether the pumping unit is stable, thereby improving the effectiveness of control mode switching based on the determination result.

[0087] Optionally, to eliminate control jitter and reduce the current required for low-frequency startup, please refer to [link to relevant documentation]. Figure 6 , Figure 6 This is a flowchart illustrating another oil pumping unit control method provided in an embodiment of this application. The method may further include steps S241-S243.

[0088] Step S241: Determine the suspension point load curve of the pumping unit through the controller.

[0089] In the closed-loop control mode, the suspension point load curve of the pumping unit can be determined by the controller.

[0090] Optionally, the suspension point load curve can be determined based on design parameters during the design process of the pumping unit and stored in a corresponding database. The controller can then query the database based on the pumping unit's model, code, or other identification information to obtain the corresponding suspension point load curve. Alternatively, load and displacement signals can be collected using load sensors, displacement sensors, and other detection devices installed on the pumping unit, and the controller can plot and determine the corresponding suspension point load curve based on these signals. The suspension point load curve visually displays the changes in static, dynamic, and frictional loads borne by the suspension point within one working cycle, providing data support for control adjustments.

[0091] Optionally, when implementing torque feedforward compensation, the suspension point load curve can be obtained by querying a pre-stored database, or the suspension point load curve can be estimated online using an adaptive algorithm based on the real-time output torque of the motor and the crank angle.

[0092] Step S242: The controller determines the torque feedforward command based on the suspension point load curve.

[0093] Step S243: Adjust the torque command based on the torque feedforward command via the controller.

[0094] The controller can determine the corresponding torque feedforward command based on the suspension point load curve, and then adjust the torque command during control based on the torque feedforward command.

[0095] Optionally, the torque command is the q-axis current command of the pumping unit motor. The FOC algorithm can directly and linearly control the output torque of the motor based on the q-axis current command.

[0096] exist Figure 6 In the illustrated embodiment, control adjustments can be made through load prediction to reduce torque abrupt changes and improve the reliability of startup at ultra-low frequencies and the smoothness of mode switching.

[0097] Optionally, please refer to Figure 7 , Figure 7 The following is a detailed flowchart of step S242 provided in an embodiment of this application. Step S242 may include steps S2421-S2423.

[0098] Step S2421: Determine the crank angle of the pumping unit via the controller.

[0099] Step S2422: Determine the required torque using the controller, based on the crank angle and suspension load curve.

[0100] Step S2423: The controller generates a torque feedforward command based on the required torque.

[0101] The controller can determine the current crank angle of the pumping unit, calculate the actual torque demand based on the crank angle and suspension point load curve, and then generate corresponding torque feedforward commands based on the torque demand to adjust the motor control of the pumping unit.

[0102] Optionally, in a beam pumping unit, the crank angle is the rotational angle of the crankshaft relative to a fixed zero point (usually defined as a 0° reference point). The crank angle uniquely determines the position and geometry of the entire transmission system of the pumping unit, including: the position of the suspension point (e.g., whether it is in the upstroke or downstroke, and at which specific point); the velocity direction of the suspension point (e.g., whether it is upward or downward); and the acceleration of the suspension point (e.g., whether it is accelerating or decelerating). A rotary encoder can be installed on the motor shaft or crankshaft to measure the crank angle and send the measured crank angle to the controller for processing. The required torque is the torque that the motor needs to output (or absorb) to overcome the current suspension point load. The controller can calculate the net torque corresponding to the crankshaft based on the crank angle and suspension point load curve, and then determine the total load torque of the crankshaft by combining the balance and friction conditions. The total load torque is then converted into the required torque of the motor shaft, and a corresponding torque feedforward command is generated based on the required torque for control adjustment.

[0103] Figure 7 In the illustrated embodiment, the torque output of the pumping unit's motor can be matched as smoothly as possible to the torque required for changes in the suspension point load, thereby minimizing energy fluctuations and improving the efficiency and stability of the pumping unit.

[0104] In summary, the oil pumping unit control system and method provided in this application effectively reduce the minimum starting frequency of the oil pumping unit from 1.5Hz to below 0.5Hz, achieving truly ultra-flexible and smooth starting, completely eliminating starting shock, reducing the starting current of the oil pumping unit by more than 50%, achieving high torque with low current, improving the working efficiency of the oil pumping unit, and reducing the starting time and energy consumption required by the oil pumping unit.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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 pumping unit 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 pumping unit based on the oversampling rate to obtain sampling data; The control module is used to determine the status data of the pumping unit based on the sampled data, and to switch between open-loop control mode and closed-loop control mode based on the status data. The high-frequency power module is used to start the motor of the oil pumping unit in the closed-loop control mode.

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, In the closed-loop control mode, the starting frequency of the motor started by the SiC inverter power module is ≤0.5Hz.

6. The system according to any one of claims 1-5, characterized in that, The control module includes: a filter and a controller; The 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 state data of the pumping unit; wherein the state data includes the rotor position of the motor; the detection algorithm includes a phase-locked loop algorithm or a sliding mode observer algorithm; the controller calculates the position error based on the state data; the controller compares the position error with a preset error threshold to determine whether the pumping unit is stable; and if the pumping unit is stable, the controller switches from the open-loop control mode to the closed-loop control mode.

7. The system according to any one of claims 1-5, characterized in that, in, The open-loop control mode includes: V / F open-loop control mode; the closed-loop control mode includes: closed-loop control mode based on FOC control algorithm.

8. A method for controlling an oil pumping unit, characterized in that, The method is applied to the pumping unit control system according to any one of claims 1-7, and the method includes: The pumping unit is sampled using a high-precision sampling module based on the oversampling rate to obtain sampling data; The control module determines the status data of the pumping unit based on the sampled data, and switches between open-loop control mode and closed-loop control mode based on the status data. The pumping unit's motor is started using a high-frequency power module in the closed-loop control mode.

9. The method according to claim 8, characterized in that, in, The control module includes: a filter and a controller; The step of determining the status data of the pumping unit based on the sampled data through the control module, and switching between open-loop control mode and closed-loop control mode based on the status data, includes: The received sampled data is filtered using the filter to obtain filtered data. The controller processes the filtered data based on a detection algorithm to determine the state data of the pumping unit; wherein the state data includes the rotor position of the motor; the detection algorithm includes a phase-locked loop algorithm or a sliding mode observer algorithm. The controller calculates the position error based on the state data. The controller compares the preset error threshold with the position error to determine whether the pumping unit is stable. If the pumping unit is determined to be stable, the controller switches from the open-loop control mode to the closed-loop control mode.

10. The method according to claim 9, characterized in that, The step of determining whether the pumping unit is stable by comparing a preset error threshold with the position error through the controller includes: The controller compares the position error with a preset error threshold. If the position error is determined to be less than the error threshold, then a stable count is added via the controller; If the position error is determined to be greater than or equal to the error threshold, the controller will reset the stability count to zero. If the total stable count value is determined to be greater than or equal to the preset count threshold, the controller determines that the pumping unit is stable. If the total stable count is less than the preset count threshold, the controller determines that the pumping unit is unstable.

11. The method according to claim 9, characterized in that, The method further includes: The controller is used to determine the suspension point load curve of the pumping unit; The controller determines the torque feedforward command based on the suspension point load curve. The controller adjusts the torque command based on the torque feedforward command.

12. The method according to claim 11, characterized in that, The step of determining the torque feedforward command based on the suspension point load curve through the controller includes: The controller determines the crank angle of the pumping unit; The controller determines the required torque based on the crank angle and the suspension point load curve. The controller generates the torque feedforward command based on the required torque.

13. A pumping unit 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 pumping unit based on the oversampling rate to obtain sampled data; The control module is used to determine the status data of the pumping unit based on the sampled data, and to switch between open-loop control mode and closed-loop control mode based on the status data. The SiC inverter power module is used to start the motor of the oil pumping unit in the closed-loop control mode.

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