Permanent magnet disc type motor for oil pumping unit in oil field

Abstract

The invention relates to the technical field of motors, and discloses a permanent magnet disc type motor for an oil pumping unit in an oil field, which comprises a bracket and a double-disc type permanent magnet motor assembly, the double-disc type permanent magnet motor assembly comprises two disc type permanent magnet motors which are completely symmetrical, a rotor and a stator which are arranged on a main shaft are disc-shaped, disc surfaces are parallel, and the rotor and the stator are correspondingly arranged; the rotor is installed on the main shaft to serve as a rotating body and corresponds to the permanent magnet steel circumferentially distributed on the disc face of the rotor, rotor tooth grooves are located on the disc face and are perpendicular to the main shaft, stator grooves are semi-closed pear-shaped grooves, the widths of the grooves are equal to the inner diameter and the outer diameter of the stator, and teeth are wide at the outer diameter and small at the inner diameter. The stator windings are embedded in tooth grooves distributed in the circumferential direction of the disc face of the stator armature, and the permanent magnets obliquely pass through a stator groove pitch. The back-to-back double-disc permanent magnet motor is adopted to directly drive the oil pumping unit connecting rod, so that energy loss in the mechanical transmission process is reduced, unnecessary mechanical friction is reduced, and the overall efficiency of a system is remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of motors, in particular to a permanent magnet magnetic disc motor for an oil field pumping unit. Background Art

[0002] As oil becomes increasingly important as the world's primary energy source, efficient oilfield extraction has become a key requirement of the oil industry. At present, oilfield pumping units generally adopt the traditional walking beam structure, and their driving parts are mostly realized by three-phase induction motors with gear reduction mechanisms.

[0003] Traditional oilfield pumping drive systems usually include three-phase induction motors and multi-stage gear reduction devices. Due to the mismatch between the motor's output characteristics and the low-speed, high-torque requirements of the pumping process, complex reduction devices are often required to achieve torque amplification. This complex mechanical structure leads to high mechanical losses and low overall system efficiency. According to existing research, the energy loss of traditional pumping units mainly comes from mechanical friction and heat dissipation in the gear reduction mechanism, which makes it difficult for the system's overall efficiency to exceed 30%. The waste of energy is particularly prominent, especially in large-scale oil fields, where traditional pumping systems consume billions of kilowatt-hours of electricity each year. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a permanent magnet disc motor for oilfield pumping units, which solves the problem that the energy loss of traditional pumping units mainly comes from mechanical friction and heat dissipation of the gear reduction mechanism, which makes it difficult for the overall efficiency of the system to exceed 30%. The waste of energy is particularly prominent.

[0005] To achieve the above purpose, the present invention is implemented by the following technical scheme: a permanent magnet disk motor for an oilfield pumping unit, comprising a bracket and a double-disc permanent magnet motor assembly, a walking beam is arranged on the upper side of the bracket, donkey heads are arranged at both ends of the walking beam, a counterweight is arranged at the lower left of the donkey head, the double-disc permanent magnet motor assembly is connected to the walking beam through a connecting rod, and a sucker rod is arranged at the lower right of the donkey head; The double-disc permanent magnet motor assembly includes a main shaft, a stator, a rotor and a permanent magnet. The double-disc permanent magnet motor assembly includes two disk-type permanent magnet motors that are completely symmetrical. The rotor and stator installed on the main shaft are both in the shape of a disk, the disk surfaces are parallel, the two are arranged correspondingly, and there is a certain air gap between them. The stator is fixed to the base, and the rotor is installed on the main shaft as a rotating body, corresponding to the permanent magnet steel distributed circumferentially on the rotor disk surface. The rotor tooth slot is located perpendicular to the disk surface and the main shaft. The connecting rod mechanism is installed on the outer diameter of the rotor. The stator includes a stator core and an armature winding. The stator slot is a semi-closed pear-shaped slot. The slot width is equal at the inner and outer diameters of the stator, while the teeth are wide at the outer diameter and small at the inner diameter. The stator winding is embedded in the tooth slots distributed circumferentially along the stator armature disk surface. The rotor includes a rotor core and a permanent magnet. The permanent magnet is obliquely across a stator slot pitch to weaken the tooth slot effect. The permanent magnet is made of rare earth neodymium iron boron material, providing high remanence B r and high coercivity H c .

[0006] Preferably, the double-disc permanent magnet motor assembly includes a motor control system based on a digital signal processor, and the motor control system adopts a speed sensorless control scheme based on vector control, and the speed sensorless control scheme specifically includes: The vector control algorithm is established through the stator current mathematical model to control the stator current in a synchronous rotating coordinate system to achieve high dynamic performance control of the motor. The stator current mathematical model is:

[0007] Among them, i s is the stator current, R s is the stator resistance, L s is the stator inductance, e s is the back electromotive force; Based on the combination of model reference adaptive system technology and neural network online identification, the motor speed ω is obtained online by real-time calculation and correction of the motor's stator current and flux. r and rotor position information θ r , precise control of speed sensorless:

[0008] in, is the estimated speed, is the back EMF of the reference model, To estimate the back EMF of the model, is the adaptation law coefficient; The control algorithm is processed in real time by a digital signal processor.

[0009] Preferably, the motor control system controls the main circuit power output of the motor through an intelligent power module, and can dynamically adjust the speed and output torque of the motor according to the operating state of the oil pump, wherein the operating state includes starting, normal operation and deceleration; The control system detects the running current signal of the motor in real time through the current transformer, and the running current signal is input into the digital signal processor after filtering and processing.

[0010] Preferably, the motor control system adopts a method of vector control combined with direct torque control to enhance the response speed of the motor under dynamic conditions. The direct torque control controls the stator flux. and torque Direct regulation is performed, and the control formula is:

[0011] in, is the pole pair number, is the stator flux, is the stator current.

[0012] Preferably, the rotor of the double-disc permanent magnet motor assembly adopts a unique permanent magnet steel arrangement, the magnet steel is installed radially tilted, and the magnet steel arrangement follows a specific pole-to-pole offset angle α, wherein:

[0013] Where p is the number of pole pairs and k is the distribution factor.

[0014] Preferably, the double-disc permanent magnet motor assembly and the motor control system automatically adapt to the workload of the pumping unit by implementing adaptive power regulation, including automatically adjusting the current set value during operation so that the set value complies with the following formula:

[0015] in, is the current load torque, K t is the torque constant.

[0016] The present invention provides a permanent magnet magnetic disc motor for an oil field pumping unit. It has the following beneficial effects: 1. The present invention adopts a back-to-back double-disc permanent magnet motor to directly drive the connecting rod of the oil pump, eliminating the traditional three-phase induction motor and its complex gear reduction device. Through this direct drive method, the energy loss in the mechanical transmission process is greatly reduced, the unnecessary mechanical friction is reduced, and the overall efficiency of the system is significantly improved. Compared with the traditional reduction system, the efficiency of the permanent magnet disk motor is significantly improved, so that the overall efficiency of the system can reach more than 80%, thereby greatly reducing energy waste.

[0017] 2. The permanent magnet disk motor of the present invention is specially designed for low-speed and high-torque working conditions. It adopts back-to-back double stators and optimized permanent magnet steel to ensure that sufficient starting torque can be provided at low speed. This structural design can adapt to the working characteristics of oil field pumping units, reduce the "big horse pulling a small cart" phenomenon, and enable the motor to still operate efficiently under partial load, thereby effectively reducing system energy consumption, especially suitable for occasions where oil field pumping is frequently started and stopped.

[0018] 3. The present invention eliminates the traditional gear reduction device and complex mechanical connecting rods, greatly reducing the mechanical parts of the entire system, significantly reducing wear and maintenance requirements. At the same time, the motor adopts speed sensorless vector control technology, and achieves high-precision speed and position control through a digital signal processor (DSP), which not only improves the control accuracy of the system, but also reduces dependence on sensors, reduces equipment failure points, and enhances the stability and reliability of the system.

[0019] 4. The present invention also adopts an intelligent control system based on DSP, which monitors load changes in real time and adaptively adjusts the output power of the motor, so that the motor always works in the high-efficiency area, thereby achieving energy saving and consumption reduction. Different from the traditional method of adjusting the operating state by mechanical structure, the control system of the present invention has the characteristics of rapid response and precise control, which improves the energy saving level of the oil pump while reducing the production cost of the oil field. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A three-dimensional diagram of the double-disc permanent magnet motor of the present invention used in an oil field pumping unit; Figure 2 It is a cross-sectional view of the double-disc permanent magnet motor of the present invention; Figure 3 It is a schematic diagram of the no-load electromotive force and time harmonic spectrum of a single stator coil of the present invention.

[0021] Among them, 1. bracket; 2. walking beam; 3. donkey head; 4. counterweight; 5. double-disc permanent magnet motor assembly; 501. main shaft; 502. stator; 503. rotor; 504. permanent magnet; 6. connecting rod; 7. sucker rod. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Please see attached Figure 1 -Attached Figure 3 The embodiment of the present invention provides a permanent magnet magnetic disc motor for an oilfield pumping unit, comprising a bracket 1 and a double-disc permanent magnet motor assembly 5, a walking beam 2 is arranged on the upper side of the bracket 1, donkey heads 3 are arranged at both ends of the walking beam 2, a counterweight 4 is arranged at the lower left of the donkey head 3, the double-disc permanent magnet motor assembly 5 is connected to the walking beam 2 through a connecting rod 6, and a sucker rod 7 is arranged at the lower right of the donkey head 3; The double-disc permanent magnet motor assembly 5 includes a main shaft 501, a stator 502, a rotor 503 and a permanent magnet 504. The double-disc permanent magnet motor assembly 5 includes two disk-type permanent magnet motors that are completely symmetrical. The rotor 503 and the stator 502 mounted on the main shaft 501 are both in the shape of a disk, and the disk surfaces are parallel. The two are arranged correspondingly, and there is a certain air gap between them. The stator 502 is fixed to the base, and the rotor 503 is mounted on the main shaft 501 as a rotating body, corresponding to the permanent magnet steel distributed circumferentially on the disk surface of the rotor 503. The tooth grooves of the rotor 503 are located on the disk surface and are perpendicular to the main shaft 501. The connecting rod mechanism is installed on the outer diameter of the rotor 503. The stator 502 includes a stator core and an armature winding. The slot of the stator 502 is a semi-closed pear-shaped slot. The slot width is equal at the inner and outer diameters of the stator 502, and the teeth are wide at the outer diameter and small at the inner diameter. The stator 502 winding is embedded in the tooth slots distributed along the circumferential direction of the stator armature disk. The rotor 503 includes a rotor core and a permanent magnet 504. The permanent magnet 504 is obliquely across a stator slot pitch to weaken the tooth slot effect. The permanent magnet 504 is made of rare earth neodymium iron boron material, which provides high remanence Br and high coercive force Hc.

[0024] Specifically, when the stator coil of the disc permanent magnet motor is connected to an alternating current of a certain frequency, a rotating magnetic field is generated in the air gap of the motor, which interacts with the synchronous rotor excitation magnetic field to generate an electromagnetic torque, which drives the walking beam through the connecting rod to drive the pumping rod up and down. Now the inefficient reduction mechanism has been cancelled, which is convenient to replace the original three-phase induction motor and eliminate the loss and limitation of the mechanical reduction mechanism. Although the connecting rod mechanism is still needed, the control system can adjust the output power of the motor in real time, improve the operating efficiency of the motor itself, increase the speed of pumping oil, and keep a good power match between the pumping unit and the motor, which can improve efficiency and save electricity. In addition, the permanent magnet steel adopts rare earth neodymium iron boron material, which has high remanence and high coercive force, and can provide sufficient magnetic flux in a small space, thereby making the motor compact and high in power density.

[0025] The double-disc permanent magnet motor assembly 5 includes a motor control system based on a digital signal processor. The motor control system adopts a speed sensorless control scheme based on vector control. The speed sensorless control scheme specifically includes: The vector control algorithm is established through the stator current mathematical model to control the stator current in a synchronous rotating coordinate system to achieve high dynamic performance control of the motor. The stator current mathematical model is:

[0026] Among them, i s is the stator current, R s is the stator resistance, L s is the stator inductance, e s is the back electromotive force; Based on the combination of model reference adaptive system technology and neural network online identification, the motor speed ω is obtained online by real-time calculation and correction of the motor's stator current and flux. r and rotor position information θ r , precise control of speed sensorless:

[0027] in, is the estimated speed, is the back EMF of the reference model, To estimate the back EMF of the model, is the adaptation law coefficient; The control algorithm is processed in real time by a digital signal processor.

[0028] Specifically, the control system adopts a vector control solution with a digital signal processor (DSP) as the core, and the control algorithm is based on the stator current mathematical model in a synchronous rotating coordinate system. By using the model reference adaptive system (MRAS) technology and the neural network online identification method, the stator current and flux of the motor are calculated and corrected in real time to obtain information on the rotor speed and position. This control solution removes the traditional speed sensor, making the control system more compact and easy to install and maintain, while improving the reliability and durability of the system.

[0029] The motor control system controls the main circuit power output of the motor through the intelligent power module, and can dynamically adjust the motor speed and output torque according to the operating status of the pumping unit, including starting, normal operation and deceleration; The control system detects the running current signal of the motor in real time through the current transformer, and the running current signal is input into the digital signal processor after filtering and processing.

[0030] Specifically, the control system adjusts the power of the main circuit through the intelligent power module (IPM) to control the output of the motor. The current transformer is used to detect the stator current in real time. The obtained current signal is input to the DSP after filtering for feedback adjustment. Through feedback adjustment, the DSP can dynamically adjust the motor speed and output torque according to the current operating status of the pumping unit, thereby optimizing the power output of the motor and maximizing the energy saving effect of the system. For example, when the motor starts, the starting current is increased to provide sufficient starting torque; when the load is light, the current is reduced to reduce energy consumption.

[0031] The motor control system adopts a method of vector control combined with direct torque control to enhance the motor's response speed in dynamic conditions. Direct torque control controls the stator flux. and torque Direct regulation is performed, and the control formula is:

[0032] in, is the pole pair number, is the stator flux, is the stator current.

[0033] Specifically, the motor control system uses a combination of vector control and direct torque control (DTC). Vector control is used to optimize the dynamic performance of the motor, while direct torque control improves the response speed of the motor by adjusting the stator flux and torque in real time. The motor control system uses a combination of vector control and direct torque control (DTC). Vector control is used to optimize the dynamic performance of the motor, while direct torque control improves the response speed of the motor by adjusting the stator flux and torque in real time.

[0034] The rotor of the double-disc permanent magnet motor assembly adopts a unique permanent magnet magnet arrangement. The magnets are installed radially tilted, and the magnet arrangement follows a specific pole-to-pole offset angle α, where:

[0035] Where p is the number of pole pairs and k is the distribution factor.

[0036] Specifically, this arrangement can effectively reduce the cogging effect on the rotor, making the air gap flux more uniform, thereby reducing vibration and noise and improving the operating stability of the motor. At the same time, this design can generate greater starting torque at low speeds, which is particularly suitable for the working characteristics of the pumping unit, ensuring stable starting and continuous efficient operation of the system at lower speeds.

[0037] The twin-disc permanent magnet motor assembly and motor control system automatically adapt to the workload of the pumping unit by implementing adaptive power regulation, including automatically adjusting the current setpoint during operation so that the setpoint meets the following formula:

[0038] in, is the current load torque, K t is the torque constant Specifically, in this way, the control system can ensure that the motor always operates in the high-efficiency area, reduce unnecessary energy consumption, and extend the service life of the motor. Through the coordinated control of IPM and DSP, the motor can dynamically adapt to the load changes of the oil field pumping unit, so that the best energy efficiency can be achieved under different working conditions.

[0039] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A permanent magnet magnetic disc motor for an oil field pumping unit, comprising a bracket (1) and a double-disc permanent magnet motor assembly (5), characterized in that: A walking beam (2) is arranged on the upper side of the support (1), a donkey head (3) is arranged at both ends of the walking beam (2), a counterweight (4) is arranged at the lower left of the donkey head (3), the double-disc permanent magnet motor assembly (5) is connected to the walking beam (2) via a connecting rod (6), and a sucker rod (7) is arranged at the lower right of the donkey head (3); The double-disc permanent magnet motor assembly (5) comprises a main shaft (501), a stator (502), a rotor (503) and a permanent magnet (504). The double-disc permanent magnet motor assembly (5) comprises two disk-type permanent magnet motors that are completely symmetrical. The rotor (503) and the stator (502) mounted on the main shaft (501) are both in the shape of a disk, the disk surfaces are parallel, the two are arranged correspondingly, and there is a certain air gap between them. The stator (502) is fixed to the machine base, and the rotor (503) is mounted on the main shaft (501) as a rotating body, corresponding to the permanent magnet steel distributed circumferentially on the disk surface of the rotor (503). The tooth grooves of the rotor (503) are located on the disk surface and are perpendicular to the main shaft (501). The connecting rod mechanism is mounted on the outer diameter of the rotor (503). The stator (502) comprises a stator core and an armature winding. The slot of the stator (502) is a semi-closed pear-shaped slot. The slot width is equal at the inner and outer diameters of the stator (502). The teeth are wider at the outer diameter and smaller at the inner diameter. The stator (502) winding is embedded in the tooth slots distributed along the circumference of the stator armature disk. The rotor (503) comprises a rotor core and a permanent magnet (504). The permanent magnet (504) is obliquely across a stator slot pitch to weaken the tooth slot effect. The permanent magnet (504) is made of rare earth neodymium iron boron material, providing high remanence B r and high coercivity H c .

2. The permanent magnet disc motor for oilfield pumping unit according to claim 1, characterized in that: The double-disc permanent magnet motor assembly (5) comprises a motor control system based on a digital signal processor, wherein the motor control system adopts a speed sensorless control scheme based on vector control, wherein the speed sensorless control scheme specifically comprises: The vector control algorithm is established through the stator current mathematical model to control the stator current in a synchronous rotating coordinate system to achieve high dynamic performance control of the motor. The stator current mathematical model is: Among them, i s is the stator current, R s is the stator resistance, L s is the stator inductance, e s is the back electromotive force; Based on the combination of model reference adaptive system technology and neural network online identification, the motor speed ω is obtained online by real-time calculation and correction of the motor's stator current and flux. r and rotor position information θ r , precise control of speed sensorless: in, is the estimated speed, is the back EMF of the reference model, To estimate the back EMF of the model, is the adaptation law coefficient; The control algorithm is processed in real time by a digital signal processor.

3. The permanent magnet disc motor for oilfield pumping unit according to claim 2, characterized in that: The motor control system controls the main circuit power output of the motor through the intelligent power module, and can dynamically adjust the speed and output torque of the motor according to the operating state of the pumping unit, wherein the operating state includes starting, normal operation and deceleration; The control system detects the running current signal of the motor in real time through the current transformer, and the running current signal is input into the digital signal processor after filtering and processing.

4. The permanent magnet disc motor for oilfield pumping unit according to claim 2, characterized in that: The motor control system adopts a method of vector control combined with direct torque control to enhance the response speed of the motor in dynamic conditions. The direct torque control controls the stator flux. and torque Direct regulation is performed, and the control formula is: in, is the pole pair number, is the stator flux, is the stator current.

5. The permanent magnet disc motor for oil field pumping unit according to claim 1, characterized in that: The rotor of the double-disc permanent magnet motor assembly adopts a unique permanent magnet steel arrangement, the magnet steel is installed radially and tilted, and the magnet steel arrangement follows a specific pole-to-pole offset angle α, wherein: Where p is the number of pole pairs and k is the distribution factor.

6. The permanent magnet magnetic disc motor for oil field pumping unit according to claim 2, characterized in that: The dual-disc permanent magnet motor assembly and motor control system automatically adapt to the workload of the pumping unit by implementing adaptive power regulation, including automatically adjusting the current set value during operation so that the set value complies with the following formula: in, is the current load torque, K t is the torque constant.

Images