Speed-adjustable double-magnetic-field asynchronous motor and operation method thereof

Abstract

The invention provides a speed-adjustable double-magnetic-field asynchronous motor and an operation method thereof, the asynchronous motor is provided with stators and a rotor, and the stators comprise an adjustable stator and a fixed stator; the fixed stator comprises two groups of stator assemblies with the same magnetic pole pair, the two groups of stator assemblies have the same electrical parameters, the fixed stator is directly and fixedly connected to the motor casing, the adjustable stator can be rotatably connected to the motor casing, and the adjustable stator is connected with the stator rotating device; the stator rotating device comprises a mechanical connection structure, and the mechanical connection structure enables the adjustable stator to rotate around the common axis by a preset angle relative to the fixed stator under the driving of the speed regulator. Starting of the asynchronous motor comprises a full-voltage starting mode and a soft starting mode, and shutdown of the asynchronous motor comprises a free shutdown mode and a soft shutdown mode. Stepless speed regulation of the asynchronous motor is achieved, and the method is particularly suitable for speed regulation of a high-voltage and high-power motor.

Description

Technical Field

[0001] This invention belongs to the field of asynchronous motor technology, and particularly relates to a speed-adjustable dual-field asynchronous motor and its operating method. Background Technology

[0002] Existing speed control methods fall into two categories: one is electric motor speed control, such as DC motor speed control, variable pole pair speed control, frequency conversion speed control, voltage conversion speed control, and chopper speed control. Due to the complexity of the equipment, large capacity, and high voltage, these methods are not widely used. The other is mechanical speed control, such as gear shifting, hydraulic speed control, and coupling speed control. Mechanical speed control requires an additional mechanical device, resulting in high investment, high energy consumption, poor sensitivity, high failure rate, and heavy maintenance. Especially for high-power mechanical speed control, it requires the addition of bulky, complex, and expensive equipment such as hydraulic couplings, frequency converters, and choppers to achieve speed control of large machinery, making it highly unfavorable for widespread application.

[0003] Chinese patent CN102163894A discloses a combined torque asynchronous speed-regulating motor. In this motor, the number of turns of enameled wire wound on the first stator is greater than the number of turns of enameled wire wound on the second stator. Magnetic shielding sleeves are provided between the iron cores at both ends of the rotor and the shaft. Magnetic shielding rings are provided at the outer ends of the iron cores. Segmented magnetic shielding is provided between the iron cores. The drive worm gear of this motor, driven by an external actuator, drives either the first or second stator to rotate within an adjustable geometric angle range and can be locked at any position. The rotor consists of two squirrel-cage rotors. The magnetic fields of the two stators cause the combined rotor current in the regulating section of the motor to affect the motor, which can be achieved simply by adjusting the angle between the two stator magnetic fields, thus achieving stepless speed regulation of the asynchronous motor.

[0004] However, Chinese patent CN102163894A has a complex structure and is difficult to manufacture. Therefore, there is a need for a simpler structure, suitable for speed regulation of high-voltage, high-power motors, and capable of stepless speed regulation of asynchronous motors, as well as a speed regulation device and method. Summary of the Invention

[0005] The first aspect of the present invention provides a speed-adjustable dual-field asynchronous motor, wherein the asynchronous motor has a stator and a rotor inside a housing 2, the rotor being located inside a cavity enclosed by the stator, and when the stator is connected to an alternating power supply, an alternating magnetic field is generated to drive the rotor to rotate; the stator includes: an adjustable stator 3 and a fixed stator 5;

[0006] The fixed stator 5 includes a first stator assembly with n magnetic pole pairs, and the adjustable stator 3 includes a second stator assembly with n magnetic pole pairs, where n≥1;

[0007] The first stator assembly and the second stator assembly have the same electrical parameters, which include: the number of magnetic pole pairs and the magnetic pole material; the electrical parameters also include: the winding direction of the wire winding, the current capacity and the winding impedance value;

[0008] The fixed stator 5 is directly fixed to the motor housing, and the adjustable stator 3 is rotatably connected to the motor housing. The adjustable stator 3 is connected to the stator rotation device 10.

[0009] The stator rotation device 10 includes a mechanical connection structure that allows the adjustable stator 3 to rotate by a predetermined angle relative to the fixed stator 5 about the common axis of the fixed stator 5 and the adjustable stator 3 under the drive of the speed regulator 7.

[0010] As described in the first aspect of the present invention, the rotor of the dual-magnetic field asynchronous motor is composed of silicon steel sheets and conductor bars 14 with insulating layers, and the rotor has a motor rotor shaft 1, which is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor.

[0011] The rotor's guide bar 14 is electrically connected at both ends of the rotor to a first short-circuit end ring 12 and a second short-circuit end ring 13 that surround the outer end of the rotor.

[0012] As described in the first aspect of the present invention, in the dual-magnetic-field asynchronous motor, bearings are provided in the shaft holes of the front and rear end covers, and the motor rotor shaft 1 is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor through the bearings.

[0013] As described in the first aspect of the present invention, in the dual-magnetic-field asynchronous motor, the rotor guide bars 14 are provided with a spacing section in the middle part of the rotor, and the guide bars 14 are separated by the spacing section.

[0014] As described in the first aspect of the present invention, the first stator assembly and the second stator assembly are driven by single-phase AC or three-phase AC.

[0015] The first stator assembly and the second stator assembly have the same number of pole pairs;

[0016] The magnetic pole windings of the first stator assembly and the second stator assembly are arranged in the form of motor windings for a single-phase AC motor or a three-phase AC motor.

[0017] A second aspect of the present invention provides a method for operating a dual-field asynchronous motor as described in any one of the above-mentioned methods, the method comprising the following steps:

[0018] Step 1: Select the dual-field asynchronous motor starting mode; power on and start the dual-field asynchronous motor; the starting modes include: dual-field asynchronous motor full-voltage starting mode and soft-start mode;

[0019] Step 2: Apply power to the external power source of the dual-field asynchronous motor and adjust the speed and power of the dual-field asynchronous motor;

[0020] Step 3, select the shutdown mode of the dual-field asynchronous motor; the shutdown mode includes: the dual-field asynchronous motor free shutdown mode and the soft shutdown mode;

[0021] Step 4: Power off and shut down.

[0022] As described in the second aspect of the present invention, the full-voltage start mode of the dual-field asynchronous motor includes: setting the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 to 0, powering on the power supply, and starting the dual-field asynchronous motor.

[0023] The free shutdown mode of the dual-field asynchronous motor includes: setting the phase difference of the magnetic field of the pole pair of the adjustable stator 3 and the fixed stator 5 to 0, turning off the power supply, and shutting down the dual-field asynchronous motor.

[0024] As described in the second aspect of the present invention, step 2 of the method for operating a dual-magnetic-field asynchronous motor includes the following sub-steps:

[0025] Step 2.1, apply the external power to drive the mechanical connection structure so that the adjustable stator 3 rotates relative to the fixed stator 5 about the common axis of the fixed stator 5 and the adjustable stator 3 by a predetermined angle.

[0026] Step 2.2: Determine whether the motor speed meets the predetermined requirements based on the motor speed and torque detected by the sensor;

[0027] Step 2.3: If the motor speed reaches the predetermined requirement, stop applying external power;

[0028] Step 2.4: If the motor speed does not reach the predetermined requirement, return to step 2.1.

[0029] As described in the second aspect of the present invention, the soft-start mode of the dual-field asynchronous motor includes:

[0030] Step 1.1: Before starting, set the phase difference of the magnetic fields of the adjustable stator 3 and the fixed stator 5 to 180 degrees using external power, and then power on the power supply.

[0031] Step 1.2, proceed to step 2, and adjust the speed of the dual-field asynchronous motor.

[0032] As described in the second aspect of the present invention, step 3 of the dual-field asynchronous motor operation method includes the following sub-steps:

[0033] Step 3.1: The speed controller 7 drives the mechanical connection structure, causing the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 to gradually rotate towards a position with a phase difference of 180 degrees.

[0034] Step 3.2: When the phase difference of the magnetic field of the pole pair of the adjustable stator 3 and the fixed stator 5 is 180 degrees, turn off the motor power supply.

[0035] Step 3.3: The speed controller 7 drives the mechanical connection structure to gradually adjust the adjustable stator 3 so that the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 is 0.

[0036] This invention enables stepless speed regulation of asynchronous motors, and is particularly suitable for speed regulation of high-voltage, high-power motors. Compared with frequency converters, high-voltage, high-power frequency converters have a series of problems, such as high price, large footprint, high operating environment requirements, harmonic pollution, and inconvenient maintenance, which have hindered their market adoption.

[0037] Compared with the speed regulation of wound-rotor motors with series resistance, it has no slip rings connecting the windings and resistors that consume active power, so it has a low failure rate, high efficiency, and can achieve stepless speed regulation.

[0038] Compared to electromagnetic speed regulation, electromagnetic speed-regulating motors do not decrease in speed; only the output of the electromagnetic speed regulating device changes the speed. This results in lower efficiency and a more complex structure at low speeds. However, electromagnetic speed regulation allows for smooth current adjustment of asynchronous motors without the need for high-voltage, high-power power electronic devices, providing a new method for stepless speed regulation of asynchronous motors.

[0039] This invention overcomes some difficulties in the speed regulation of asynchronous motors and has unique advantages compared with various speed regulation methods. In particular, it has a good application prospect for speed regulation of pumps and other motors where the speed regulation accuracy requirement is not high. Attached Figure Description

[0040] Figure 1 This is a schematic cross-sectional view of the speed-adjustable dual-magnetic-field asynchronous motor proposed in this invention.

[0041] Figure 2 This is a schematic diagram of the rotor of the speed-adjustable dual-magnetic-field asynchronous motor proposed in this invention.

[0042] Figure 3 This is a schematic diagram of the magnetic field phase difference of the two-pole motor magnetic field of the dual-magnetic asynchronous motor proposed in this invention when it is 180 degrees.

[0043] Figure 4 This is a schematic diagram of the magnetic field phase difference of the two-pole motor magnetic field of the dual-magnetic asynchronous motor proposed in this invention when it is 0 degrees.

[0044] Figure 5 This is a flowchart of the operation of the dual-magnetic-field asynchronous motor proposed in this invention.

[0045] The components include: 1. Motor rotor shaft, 2. Motor housing, 3. Adjustable stator, and 4. Sliding connector.

[0046] 5. Fixed stator, 6. Fixed connector, 7. Speed ​​controller, 8. Rotor bearing, 9. No short-circuit ring gap, 10. Stator rotation device, 11. Current direction of rotor cross-section, 12. First short-circuit end ring, 13. Second short-circuit end ring, 14. Conductor bar, 15. Rotor cross-section, 16. Fixed stator magnetic field direction, 17. Adjustable stator magnetic field direction, 18. Magnetic field rotation direction. Detailed Implementation

[0047] The inventive point of this invention is: by adjusting the phase difference of the rotating magnetic field of the adjustable stator 3 relative to the fixed stator 5, the magnitude of the induced current in the rotor of the asynchronous motor is changed, thereby changing the slip of the motor and realizing the motor speed regulation.

[0048] By adjusting the rotation angle of the adjustable stator 3, the relative angle of the radial directions of the two stators is changed, causing a phase difference in the rotating magnetic fields of the two stators. The electromotive forces generated by the two rotating magnetic fields with phase difference in the rotor bars 14 are superimposed, causing a change in the current in the rotor bars 14.

[0049] The principle is as follows: After the motor is energized, the two stators generate two sets of rotating magnetic fields. When the phase difference between the two sets of magnetic fields is 0, that is, the N poles and S poles of the two magnetic fields coincide. The electromotive forces generated by the two magnetic fields in the rotor are superimposed, and the current is at its maximum. At this time, the motor operates at its maximum power and full speed. When the adjustable stator 3 rotates a certain angle, a phase difference is generated between the two rotating magnetic fields. At this time, the electromotive forces generated by the two sets of rotating magnetic fields on the rotor bars also have a phase difference. The superposition of the two sets of rotating magnetic fields reduces the current in the rotor. Due to the decrease in the current in the rotor, the slip of the motor will increase, and the speed of the motor will decrease accordingly. Continue to adjust the angle of the adjustable stator 3 until the N pole of the fixed stator 5 coincides with the S pole of the adjustable stator 3. If the electromagnetic parameters of the two stators are exactly the same, the electromotive forces generated by the two sets of rotating magnetic fields in the rotor are equal in magnitude and opposite in direction, canceling each other out. Therefore, the rotor current is 0. At this time, the motor slowly stops under the action of inertia, and only the current that establishes the magnetic field in the stator still flows. At this time, the motor is equivalent to an unloaded transformer.

[0050] The above description illustrates how adjusting the angles of the two stators allows for convenient adjustment of the rotor current, thereby achieving speed regulation of the asynchronous motor. The technical solutions of the embodiments of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0051] It should be noted that in the description of this invention, the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc., indicate the orientation or positional relationship based only on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0052] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through intermediate plugs; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0053] As attached Figure 1 The figure shown is a schematic diagram of the external shape of the speed-adjustable dual-magnetic asynchronous motor proposed in this invention.

[0054] The first aspect of the present invention provides a speed-adjustable dual-field asynchronous motor, wherein the asynchronous motor has a stator and a rotor inside a housing 2, the rotor being located inside a cavity enclosed by the stator, and when the stator is connected to an alternating power supply, an alternating magnetic field is generated to drive the rotor to rotate; the stator includes: an adjustable stator 3 and a fixed stator 5;

[0055] The fixed stator 5 includes a first stator assembly with n magnetic pole pairs, and the adjustable stator 3 includes a second stator assembly with n magnetic pole pairs, where n≥1;

[0056] The first stator assembly and the second stator assembly have the same electrical parameters, which include: the number of magnetic pole pairs and the magnetic pole material; the electrical parameters also include: the winding direction of the wire winding, the current capacity and the winding impedance value;

[0057] The fixed stator 5 is directly fixed to the motor housing, and the adjustable stator 3 is rotatably connected to the motor housing. The adjustable stator 3 is connected to the stator rotation device 10.

[0058] The stator rotation device 10 includes a mechanical connection structure that allows the adjustable stator 3 to rotate by a predetermined angle relative to the fixed stator 5 about the common axis of the fixed stator 5 and the adjustable stator 3 under the drive of the speed regulator 7.

[0059] As described in the first aspect of the present invention, the rotor of the dual-magnetic field asynchronous motor is composed of silicon steel sheets and conductor bars 14 with insulating layers, and the rotor has a motor rotor shaft 1, which is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor.

[0060] The rotor's guide bar 14 is electrically connected at both ends of the rotor to a first short-circuit end ring 12 and a second short-circuit end ring 13 that surround the outer end of the rotor.

[0061] As described in the first aspect of the present invention, in the dual-magnetic-field asynchronous motor, bearings are provided in the shaft holes of the front and rear end covers, and the motor rotor shaft 1 is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor through the bearings.

[0062] Example 1

[0063] The first embodiment of the present invention is a single-phase asynchronous motor, which has a cylindrical configuration. The single-phase asynchronous motor has a cylindrical outer casing made of ordinary steel, and the stator and rotor of the asynchronous motor are installed inside the casing. The two ends of the cylindrical casing are disc-shaped front and rear end covers. The rotor is an approximately cylindrical body surrounding the motor rotor shaft. The motor rotor shaft is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor via bearings. The center of these shaft holes is also the axis of the rotating magnetic field generated when the stator of the asynchronous motor is energized. Bearings should be installed in the shaft holes of the front and rear end covers to connect the motor rotor shaft to the front and rear end covers of the motor. Small-power motors can use ball bearings, while high-power motors use roller bearings or self-lubricating bearings. The motor rotor is made of silicon steel sheets and insulating conductor bars 14. The rotor shaft extends out of the front end cover for connection with mechanical equipment to provide rotational power to the equipment. This asynchronous motor can be a three-phase AC asynchronous motor or a single-phase AC asynchronous motor. The stator located inside the cylindrical casing is divided into a fixed stator 5 and an adjustable stator 3. Both stators are cylindrical in shape and are coaxially mounted. The fixed stator 5 and the adjustable stator 3 have essentially the same structure, both including a stator assembly with n magnetic pole pairs, where n≥1.

[0064] The fixed stator 5 is directly fixed to the motor housing via a fixed connector 6. The adjustable stator 3 is connected to the motor housing via a sliding connector 4 that can rotate relative to the motor housing. This sliding connector 4 is required to reliably connect the adjustable stator 3 to the motor housing while minimizing radial vibration to prevent collision between the adjustable stator and the rotor.

[0065] The electrical parameters of the two stator assemblies are identical, which simplifies the manufacturing process and reduces production costs. The electromagnetic parameters of the stator assembly include: the number of pole pairs, winding material, winding direction of the wires, current capacity, and winding impedance. Asynchronous motors can typically have pole structures of 2, 4, 6, 8, or even more than 10 poles, which translates to different configurations ranging from one to five pole pairs.

[0066] In this invention, the fixed stator 5 is directly fixed to the motor housing, while the adjustable stator 3 is rotatably connected to the motor housing. A stator rotation device 10 is provided between the fixed stator 5 and the adjustable stator 3; the stator rotation device 10 is also connected to a speed regulator 7, which applies power to drive the adjustable stator 3 to rotate. The speed regulator 7 and the stator rotation device 10 include various structures, such as a stepper motor, a stepper motor-driven rack and worm gear transmission structure, or a gear and rack combination structure. Under the drive of external power, the stator rotation device 10 can drive the adjustable stator 3 to rotate. When the asynchronous motor is powered on, after the adjustable stator 3 rotates by a predetermined angle, a rotating magnetic field with a predetermined angle difference from the fixed stator 5 is generated for speed regulation of the asynchronous motor rotor.

[0067] The motor housing of the present invention can adopt a two-section structure to facilitate opening and maintenance. During maintenance, the adjustable stator 3 or the fixed stator 5 can be replaced separately. The motor housing can adopt a two-section structure with an outer fixing frame. The fixing frame has fixing bolts for locking the fixing frame.

[0068] The adjustable stator 3 and fixed stator 5 of this invention are equipped with cylindrical motor rotors that span the axial length of both stators, typically squirrel-cage rotors. Taking a squirrel-cage asynchronous motor as an example, the rotor part is composed of high-silicon steel sheets and conductor bars 14 with insulating layers, used to improve the rotor's permeability and reduce the influence of eddy currents, thereby improving the efficiency of the motor at low speeds. The conductor bars 14 are made of non-magnetic conductive metallic material and are embedded in grooves on the rotor. Typically, the conductor bars 14 are made of oxygen-free copper or high-purity aluminum. There is a gap in the middle part of the conductor bars 14 on the rotor, and the spacing of this gap is set. Firstly, because of the winding arrangement of the two stators, there is no iron core at this position; secondly, it prevents the magnetic fields of the two stators from affecting each other. No short-circuit ring is provided at this gap, as shown in the attached figure. Figure 1Position 9 without a short-circuit ring is shown. The rotor's guide bar 14 is electrically connected at both ends of the rotor to the first short-circuit end ring 12 and the second short-circuit end ring 13 surrounding the outer end of the rotor, respectively.

[0069] The first stator assembly and the second stator assembly have the same electrical parameters, which include: the number of magnetic pole pairs and the winding material; the electrical parameters also include: the winding direction of the wire winding, the current capacity and the winding impedance value;

[0070] As described in the first aspect of the present invention, in the dual-magnetic-field asynchronous motor, the rotor guide bars 14 are provided with a spacing section in the middle part of the rotor, and the guide bars 14 are separated by the spacing section.

[0071] As described in the first aspect of the present invention, the first stator assembly and the second stator assembly are driven by single-phase AC or three-phase AC.

[0072] The first stator assembly and the second stator assembly have the same number of pole pairs;

[0073] The magnetic pole windings of the first stator assembly and the second stator assembly are arranged in the form of motor windings for a single-phase AC motor or a three-phase AC motor.

[0074] Example 2

[0075] A second aspect of the present invention provides a method for operating a dual-field asynchronous motor as described in any one of the preceding descriptions, the method comprising the following steps:

[0076] Step 1: Select the dual-field asynchronous motor starting mode; power on and start the dual-field asynchronous motor; the starting modes include: dual-field asynchronous motor full-voltage starting mode and soft-start mode;

[0077] Step 2: Apply power to the external power source of the dual-field asynchronous motor and adjust the speed and power of the dual-field asynchronous motor;

[0078] Step 3, select the shutdown mode of the dual-field asynchronous motor; the shutdown mode includes: the dual-field asynchronous motor free shutdown mode and the soft shutdown mode;

[0079] Step 4: Power off and shut down.

[0080] This invention adjusts the rotation angle of the adjustable stator body, changing the relative angle of the two stator radial directions, thus creating a phase difference in the rotating magnetic fields of the two stators. The electromotive forces generated at the ends of the rotor bars by the two rotating magnetic fields with phase difference are superimposed, causing a change in the current in the rotor bars, thereby achieving motor speed regulation.

[0081] When the motor is energized, the two stators generate a rotating magnetic field, as shown in the attached diagram. Figure 3 and 4The diagram shows the direction of current in the rotor bars at a certain moment. ⊙ indicates current flowing out along the normal direction of the paper, and ⊙ indicates current flowing in along the normal direction of the paper. When the phase difference between the two magnetic fields in the stator is 0, that is, the N poles and S poles of the two magnetic fields coincide, the electromotive forces generated by the two magnetic fields in the rotor are superimposed, resulting in the maximum current. At this time, the motor operates at maximum power and full speed. When the adjustable stator rotates by a certain angle, a phase difference is generated between the two rotating magnetic fields. The electromotive forces generated by these two rotating magnetic fields in the rotor also have a phase difference, and their superposition causes the current to decrease. Due to the decrease in rotor current, the motor slip increases, and thus the motor speed decreases. Continuing to adjust the angle of the adjustable stator, when the N pole of the fixed stator coincides with the S pole of the adjustable stator, the electromotive forces generated by the two rotating magnetic fields in the rotor are equal in magnitude and opposite in direction, canceling each other out. Therefore, the rotor current is 0, and the motor speed is 0. By adjusting the angle of the two stators, the rotor current can be easily adjusted, thereby achieving speed regulation of the motor.

[0082] When the phase difference between the magnetic fields of a 2-pole motor is 180 degrees, the electromotive forces generated by the two stator magnetic fields in the rotor bars are equal in magnitude and opposite in direction, so no current flows through the rotor bars.

[0083] Stator section: Consists of a fixed stator body and an adjustable stator body. The adjustable rotor body can rotate around the central axis at a certain angle. The magnitude of the rotation angle is related to the number of poles of the motor, i.e., the adjustable angle α = 360 degrees / 2n, where n is the number of pole pairs. For example, a 2-pole motor can rotate from 0 to 180 degrees, and a 4-pole motor can rotate from 0 to 90 degrees. When the two stator parameters and wiring are exactly the same, the rated power of the motor is the sum of the power of A + B.

[0084] Example 3

[0085] Taking a two-pole asynchronous motor as an example, the starting and stopping modes of the asynchronous motor of the present invention are explained.

[0086] There are two modes for starting an electric motor:

[0087] Full-pressure start-up mode: The phase difference between the two magnetic fields is 0, as shown in the attached diagram. Figure 4 As shown, the combined power of the two stators at this point is equivalent to the full-voltage starting of a typical asynchronous motor. When the motor is connected to the power supply, the power grid and starting equipment experience a current surge of 6 to 8 times the rated current. After starting, the current returns to the normal operating current, which is no different from the starting process of a typical motor.

[0088] Soft start mode: Before starting, adjust the adjustable stator 3 to make the phase difference between the two magnetic fields 180 degrees, as shown in the attached diagram. Figure 3 As shown:

[0089] When the motor is powered on, the rotating magnetic fields generated by the two stators cancel each other out, resulting in a theoretically zero rotor current. At this point, the starting current borne by the power grid and starting equipment is equivalent to closing an unloaded transformer, or can be considered as a motor without conductor bars 14; the inrush current is very small. Adjusting the angle of the adjustable stator 3 changes the phase difference between the two magnetic fields towards 0 degrees, generating current in the rotor conductor bars 14, and the rotor begins to rotate. Regardless of the adjustment direction, the rotor will always move in the same direction as the rotating magnetic fields, with no possibility of reversal. As the adjustment angle gradually increases, the rotor current also gradually increases, and the speed continues to increase. When the phase difference between the two magnetic fields returns to 0, the rotor current reaches its maximum, and the motor reaches full speed. The adjustment time of the adjustable stator is the motor's acceleration time; too short an acceleration time will cause excessive motor current, similar to the acceleration time setting of a frequency converter. The rotation of the adjustable stator 3 is accomplished by the speed controller 7 and the stator rotation device 10, both controlled by a servo system.

[0090] Speed ​​control: When the angle of the adjustable stator 3 is adjusted between 0 and 180 degrees, it is within the motor speed control range. The motor speed is related to the load and motor current, and the motor stator current changes with the magnitude of the rotor current. The acceleration and deceleration times are set by the servo system.

[0091] Shutdown: Shutdown is divided into free shutdown and soft shutdown.

[0092] Free stop: When the power is cut off while the motor is running at any speed, the two stators lose power, the rotating magnetic field disappears, and no current can be generated in the rotor bars 14. At this time, the motor gradually stops under the influence of load inertia until it comes to a complete stop.

[0093] Soft stop: When stopping, the adjustable stator 3 is gradually rotated to a position where the magnetic field phase difference is 180 degrees, as shown in the attached diagram. Figure 4 As shown, the time required for rotation is the deceleration time of the motor. This can be set according to the load characteristics and requirements (the acceleration time is similar). When the motor reaches the 180-degree position, the current in the rotor bar 14 is 0. Since the two magnetic fields are out of phase, even if the motor continues to rotate under inertia, no current flows through the bar 14, and the stator current reaches its minimum. At this point, disconnecting the power supply completes the soft-stop process. As described in the second aspect of this invention, the full-voltage starting mode of the dual-field asynchronous motor includes: setting the phase difference between the magnetic fields of the adjustable stator 3 and the fixed stator 5 to 0, powering on the motor, and starting the dual-field asynchronous motor. A key feature of this invention is that the variable frequency speed control time is not too short, because an excessively short deceleration time would generate a power generation effect, causing overvoltage on the DC bus of the frequency converter. The structure of this invention is superior to that of a variable frequency speed control motor.

[0094] The free shutdown mode of the dual-field asynchronous motor includes: setting the phase difference of the magnetic field of the pole pair of the adjustable stator 3 and the fixed stator 5 to 0, turning off the power supply, and shutting down the dual-field asynchronous motor.

[0095] As described in the second aspect of the present invention, the full-voltage start mode of the dual-field asynchronous motor includes: setting the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 to 0, powering on the power supply, and starting the dual-field asynchronous motor.

[0096] The free shutdown mode of the dual-field asynchronous motor includes: setting the phase difference of the magnetic field of the pole pair of the adjustable stator 3 and the fixed stator 5 to 0, turning off the power supply, and shutting down the dual-field asynchronous motor.

[0097] As described in the second aspect of the present invention, step 2 of the method for operating a dual-magnetic-field asynchronous motor includes the following sub-steps:

[0098] Step 2.1, apply the external power to drive the mechanical connection structure so that the adjustable stator 3 rotates relative to the fixed stator 5 about the common axis of the fixed stator 5 and the adjustable stator 3 by a predetermined angle.

[0099] Step 2.2: Determine whether the motor speed meets the predetermined requirements based on the motor speed and torque detected by the sensor;

[0100] Step 2.3: If the motor speed reaches the predetermined requirement, stop applying external power;

[0101] Step 2.4: If the motor speed does not reach the predetermined requirement, return to step 2.1.

[0102] As described in the second aspect of the present invention, the soft-start mode of the dual-field asynchronous motor includes:

[0103] Step 1.1: Before starting, set the phase difference of the magnetic fields of the adjustable stator 3 and the fixed stator 5 to 180 degrees using external power, and then power on the power supply.

[0104] Step 1.2, proceed to step 2, and adjust the speed of the dual-field asynchronous motor.

[0105] As described in the second aspect of the present invention, step 3 of the dual-field asynchronous motor operation method includes the following sub-steps:

[0106] Step 3.1: The speed controller 7 drives the mechanical connection structure, causing the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 to gradually rotate towards a position with a phase difference of 180 degrees.

[0107] Step 3.2: When the phase difference of the magnetic field of the pole pair of the adjustable stator 3 and the fixed stator 5 is 180 degrees, turn off the motor power supply.

[0108] Step 3.3: The speed controller 7 drives the mechanical connection structure to gradually adjust the adjustable stator 3 so that the magnetic field phase difference between the magnetic pole pairs of the adjustable stator 3 and the fixed stator 5 is 0.

[0109] The two stators of the electric motor of this invention are powered by the same power source, requiring no additional equipment, and are simple and reliable in structure.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the embodiments of the present invention have been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the embodiments of the present invention should not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A speed-regulating dual-field asynchronous motor, wherein the motor housing (2) has a stator and a rotor, the rotor being located inside a cavity enclosed by the stator, and when the stator is connected to an alternating power supply, an alternating magnetic field is generated to drive the rotor to rotate; characterized in that, The stator comprises an adjustable stator (3) and a fixed stator (5); The fixed stator (5) comprises a first stator assembly with n magnetic pole pairs, and the adjustable stator (3) comprises a second stator assembly with n magnetic pole pairs, wherein n≥1; The first stator assembly and the second stator assembly have the same electrical parameters, which include the number of magnetic pole pairs, the material of magnetic poles, the winding direction of wire winding, the current capacity, and the winding impedance value; The fixed stator (5) is directly fixedly connected to the motor housing, and the adjustable stator (3) is rotatably connected to the motor housing and connected to the stator rotating device (10); The stator rotating device (10) comprises a mechanical connection structure, which enables the adjustable stator (3) to rotate relative to the fixed stator (5) around the common axis of the fixed stator (5) and the adjustable stator (3) by a predetermined angle under the drive of the speed regulator (7).

2. The dual field asynchronous motor of claim 1, wherein, The rotor is composed of silicon steel sheets and conducting bars (14) with an insulation layer, and has a motor rotor shaft (1) rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor; The conducting bars (14) of the rotor are electrically connected to the first short-circuit end ring (12) and the second short-circuit end ring (13) surrounding the outer ends of the rotor at both ends of the rotor.

3. The dual field asynchronous motor of claim 2, wherein, Bearings are arranged in the shaft holes of the front and rear end covers, and the motor rotor shaft (1) is rotatably fixed in the shaft holes of the front and rear end covers of the asynchronous motor through the bearings.

4. The dual field asynchronous motor of claim 3, wherein, The conducting bars (14) of the rotor are separated by a spacing section arranged at the middle part of the rotor.

5. The dual field asynchronous motor of claim 1, wherein, The first stator assembly and the second stator assembly are driven by single-phase alternating current or three-phase alternating current; The first stator assembly and the second stator assembly have the same number of magnetic pole pairs; The magnetic pole windings of the first stator assembly and the second stator assembly are arranged in the form of motor windings of a single-phase alternating current motor or a three-phase alternating current motor.

6. A method of operating a dual field asynchronous motor as claimed in any one of claims 1 to 5, characterized in that, The method comprises the following steps: Step 1: selecting a double magnetic field asynchronous motor starting mode; starting the double magnetic field asynchronous motor; the starting mode includes a double magnetic field asynchronous motor full voltage starting mode and a soft starting mode; Step 2: applying power to the double magnetic field asynchronous motor, and adjusting the speed and power of the double magnetic field asynchronous motor; Step 3: selecting a double magnetic field asynchronous motor shutdown mode; the shutdown mode includes a double magnetic field asynchronous motor free shutdown mode and a soft shutdown mode; Step 4: power off and stop.

7. The method of operating a dual field asynchronous motor of claim 6, wherein, The full voltage starting mode of the double magnetic field asynchronous motor includes setting the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) to 0, powering on, and starting the double magnetic field asynchronous motor; The free shutdown mode of the double magnetic field asynchronous motor includes setting the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) to 0, turning off the power supply, and shutting down the double magnetic field asynchronous motor.

8. The method of operating a dual field asynchronous motor of claim 6, wherein, Step 2 comprises the following sub-steps: Step 2.1, the external power driving mechanical connection structure is applied so that the adjustable stator (3) rotates relative to the fixed stator (5) around the common axis of the fixed stator (5) and the adjustable stator (3) by a predetermined angle. Step 2.2, whether the motor speed reaches the predetermined requirement is determined according to the motor speed and torque detected by the sensor; Step 2.3, if the motor speed reaches the predetermined requirement, stop applying external power; Step 2.4, if the motor speed does not reach the predetermined requirement, return to step 2.

1.

9. The method of operating a dual field asynchronous motor of claim 6, wherein, The soft start mode of the dual magnetic field asynchronous motor includes: Step 1.1, before starting, the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) is set to 180 degrees by external power, and the power supply is powered on, Step 1.2, go to step 2 to adjust the speed of the dual magnetic field asynchronous motor.

10. The method of operating a dual field asynchronous motor of claim 6, wherein, Step 3 includes the following sub-steps: Step 3.1, the speed regulator (7) drives the mechanical connection structure so that the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) gradually rotates to the position where the magnetic field phase difference is 180 degrees, Step 3.2, when the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) is 180 degrees, the motor power supply is turned off. Step 3.3, the speed regulator (7) drives the mechanical connection structure to gradually adjust the adjustable stator (3) so that the magnetic field phase difference of the magnetic pole pairs of the adjustable stator (3) and the fixed stator (5) is 0.

Images