Electric device and control method thereof

Abstract

The present invention relates to the technical field of electric motors, and in particular to an electric device and a control method thereof, comprising a housing, a generator mechanism for generating electricity, and a first rotor and a second rotor both rotatably connected to the housing, the generator mechanism being provided with a generator rotor, the first rotor being connected with a brake and a clutch, the first rotor being connected to the generator rotor of the generator mechanism through a clutch, the first rotor being arranged inside the second rotor or the second rotor being arranged inside the first rotor. The present invention can not only limit current during starting to reduce the influence of starting current on a power grid and peripheral equipment, but also has a higher torque, and can meet the occasions requiring a larger starting torque.

Description

Technical Field

[0001] The present invention relates to the technical field of electric motors, and in particular to an electric device and a control method thereof. Background Art

[0002] Squirrel cage asynchronous motors are widely used in industry, agriculture, transportation, national defense and other industries due to their simple structure, convenient manufacturing, reliable operation, low price, high efficiency and applicable mechanical characteristics. However, they also have obvious disadvantages, such as poor starting performance, excessive starting current and low starting torque.

[0003] The direct starting method is limited by the motor power and transformer capacity. Generally, small and medium-sized squirrel cage asynchronous motors can be started directly. The direct starting equipment is simple and the method is simple. However, for motors with higher power, the disadvantages of this starting method are: the starting current is large. If the transformer capacity is small, it will cause the grid voltage to drop seriously, threatening the normal operation of other electrical equipment; if it is started frequently, the excessive starting current will also cause the motor to heat up and affect the motor life. When the transformer capacity does not meet the direct starting conditions, the step-down starting method must be used. During step-down starting, the motor is affected by part of the grid voltage. This starting method can limit the starting current, but because the torque is proportional to the square of the voltage, the step-down starting also greatly reduces the starting torque. Therefore, this step-down starting method is suitable for occasions that do not require a large starting torque. Traditional step-down starting methods such as Y / Δ starting and auto-coupling step-down starting have poor starting effects and secondary current shocks, high failure rates, and large losses, and their use is increasingly restricted.

[0004] In the prior art, a soft start method can also be used to start a squirrel cage asynchronous motor. One method is to achieve AC voltage regulation by controlling the thyristor triggering conduction angle inside the soft starter through a microcomputer, which can control the voltage of the motor so that it gradually increases during the starting process. However, the thyristor voltage regulator device has limited use prospects due to its inability to solve the harmonic problem and the impact current during soft starting. Summary of the invention

[0005] The present invention aims at solving the problems in the prior art and provides an electric device which can limit the current and maintain a high starting torque when starting.

[0006] The present invention adopts the following technical solution: an electric device includes a casing, a power generation mechanism for generating electricity, and a first rotor and a second rotor both rotatably connected to the casing, the power generation mechanism is provided with a power generation rotor, the first rotor is connected to a brake and a clutch, the first rotor is connected to the power generation rotor of the power generation mechanism through a clutch, and the first rotor is arranged inside the second rotor or the second rotor is arranged inside the first rotor.

[0007] Preferably, the power generating rotor of the power generating mechanism is made of permanent magnets.

[0008] Preferably, the clutch is a hysteresis clutch, an electromagnetic slip clutch, a magnetic powder clutch, a hydraulic clutch, or a pneumatic clutch.

[0009] Preferably, the first rotor and the second rotor are respectively provided with an armature winding and a cage-type conductive bar, or the first rotor and the second rotor are respectively provided with a cage-type conductive bar and an armature winding; the electric device also includes a processor and a detection unit for detecting the current of the armature winding, and the output end of the detection unit is electrically connected to the control end of the brake and the control end of the clutch through the processor.

[0010] Preferably, the electric device further comprises a slip ring, and an external power source supplies power to the armature winding via the slip ring.

[0011] Preferably, the electric device further comprises a coupling, and the first rotor is connected to the clutch via the coupling.

[0012] Based on the above-mentioned electric device, the present invention also provides a control method, including the following steps performed in sequence: step a: use an external power supply to energize the first rotor or the second rotor, so that the first rotor and the second rotor rotate in opposite directions; step b: gradually increase the torque transmitted by the clutch, and the generator mechanism generates a braking torque on the first rotor, so that the speed of the first rotor gradually decreases and the speed of the second rotor gradually increases; step c: when the speed of the second rotor reaches a predetermined value, the brake brakes the first rotor.

[0013] Preferably, the control method further comprises the following steps which are performed in sequence after step c: step d1: making the brake no longer brake the first rotor; and step e1: adjusting the torque value transmitted by the clutch.

[0014] Preferably, the first rotor and the second rotor are respectively provided with an armature winding and a cage-type guide bar, or the first rotor and the second rotor are respectively provided with a cage-type guide bar and an armature winding; the electric device also includes a processor and a detection unit for detecting the current of the armature winding, and the output end of the detection unit is electrically connected to the control end of the brake and the control end of the clutch through the processor; the control method also includes the following steps performed after step c: Step d2: When the detection unit detects that the current of the armature winding reaches a set value, the brake no longer brakes the first rotor, and the clutch operates with slip.

[0015] Preferably, the control method also includes the following steps performed in sequence after step c: step d3: stop the brake from braking the first rotor; step e3: gradually reduce the torque value transmitted by the clutch; step f3: when the rotation speed of the second rotor is lower than a certain value, cut off the power supply to the first rotor or the second rotor.

[0016] The beneficial effects of the present invention are as follows: when the electric device is started, it can not only limit the current to reduce the influence of the starting current on the power grid and peripheral equipment, but also has a higher torque, which can meet the occasions requiring a larger starting torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of embodiment 1 of the present invention.

[0018] Figure 2 It is a structural diagram of embodiment 2 of the present invention.

[0019] Figure 3 This is a schematic diagram of the structure of the third embodiment of the present invention.

[0020] Figure 4 This is a structural diagram of embodiment 4 of the present invention.

[0021] The figures are marked as follows: 1, casing; 2, first rotor; 21, second rotor; 3, generator; 4, brake; 5, clutch; 6, armature winding; 7, guide bar; 8, slip ring; 9, coupling. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with the embodiments and drawings, and the contents mentioned in the embodiments are not intended to limit the present invention. The present invention is described in detail below in conjunction with the drawings.

[0023] Embodiment 1

[0024] like Figure 1 As shown, an electric device includes a casing 1, a power generation mechanism 3 for generating electricity, and a first rotor 2 and a second rotor 21 both rotatably connected to the casing 1. The power generation mechanism 3 is provided with a power generation rotor, the first rotor 2 is connected with a brake 4 and a clutch 5, the first rotor 2 is connected to the power generation rotor of the power generation mechanism 3 through the clutch 5, and the second rotor 21 is arranged inside the first rotor 2.

[0025] When a conventional motor starts, the slip rate between the rotor and the air gap magnetic field is large, and the speed at which the air gap magnetic field cuts the rotor conductor is large, so the starting current is large. In this embodiment, the second rotor 21 is used as the output shaft, and the first rotor 2 is provided with an armature winding 6, and the second rotor 21 is provided with a cage-type conductive bar 7. When starting, the first rotor 2 and the second rotor 21 rotate in opposite directions, and the slip rate between the air gap magnetic field and the second rotor 21 is small, so the starting current is small. At the same time, the present invention does not require step-down starting, so the output torque is large.

[0026] The torque output by the clutch 5 of the present invention is adjustable. When the clutch 5 is specifically a hysteresis clutch, an electromagnetic slip clutch or a magnetic powder clutch, the torque output by the clutch 5 is adjusted by adjusting the excitation current passed into the clutch 5. When the clutch is a hydraulic clutch, the torque output by the clutch 5 is adjusted by hydraulic pressure. When the clutch 5 is a pneumatic clutch, the torque output by the clutch 5 is controlled by pneumatics. The working process of the present invention is: the armature winding 6 of the first rotor 2 is energized so that the first rotor 2 and the second rotor 21 rotate in the opposite direction, and then the torque output by the clutch 5 is gradually increased, so that the power generation mechanism 3 converts part of the mechanical energy of the first rotor 2 into electrical energy and gradually reduces the speed of the first rotor 2, and the speed of the second rotor 21 gradually increases. When the speed of the second rotor 21 reaches a certain value, the brake 4 is used to brake the first rotor 2 so that the first rotor 2 is stationary, and the second rotor 21 runs at the rated speed. The present invention uses the power generation mechanism 3 to reduce the speed of the first rotor 2 and convert part of the mechanical energy of the first rotor 2 into electrical energy, effectively achieving the effect of energy recovery. When the rotation speed of the air gap magnetic field gradually increases according to the preset acceleration time, the relative speed between the cage bars 7 on the second rotor 21 and the air gap magnetic field is very low, so the starting current is very small.

[0027] When the air gap magnetic field speed between the first rotor 2 and the second rotor 21 is n a The rotating magnetic field speed generated by the armature winding 6 is n0, and the speed of the first rotor 2 is n b When the air gap magnetic field speed is n a =n0-n b Therefore, the air gap magnetic field speed can be adjusted by adjusting the speed of the first rotor 2, thereby realizing the adjustment of the speed of the second rotor 21. The clutch 5 is controlled to output a torque that changes continuously, the electric energy generated by the power generation mechanism 3 and the braking torque generated on the first rotor 2 also change, and the speed of the air gap magnetic field between the first rotor 2 and the second rotor 21 also changes continuously, so that the speed of the second rotor 21 can change continuously. Therefore, the output torque of the clutch 5 can be adjusted to continuously and smoothly adjust the output speed of the second rotor 21.

[0028] The power generation rotor of the power generation mechanism 3 is made of permanent magnets. When the first rotor 2 rotates and the clutch 5 is engaged, the power generation mechanism 3 can generate electricity.

[0029] The present invention can also realize a soft stop function, that is, the speed of the second rotor 21 is gradually reduced from large to small to zero. The specific process is to make the brake 4 no longer brake the first rotor 2 and continuously adjust the output torque of the clutch 5, so that the output torque of the clutch 5 is gradually reduced, so that the speed of the first rotor 2 is gradually increased, and then the speed of the second rotor 21 is gradually reduced. When the speed of the second rotor 21 is very small, the current of the armature winding 6 of the first rotor 2 is cut off.

[0030] like Figure 1 As shown, the electric device also includes a processor and a detection unit for detecting the current of the armature winding 6. The output end of the detection unit is electrically connected to the control end of the brake 4 and the control end of the clutch 5 through the processor. The processor can be a single-chip microcomputer or a PLC. The present invention can also limit the output torque of the electric device. The output torque has a linear relationship with the current of the armature winding 6. When the output torque reaches a certain value, the current of the armature winding 6 also reaches a certain value. At this time, the brake 4 no longer brakes the first rotor 2, and the clutch 5 is operated with slip, so that the first rotor 2 rotates at a certain speed and transmits part of its mechanical energy to the generator 3 to generate electricity, thereby realizing the limitation of the output torque and preventing the electric device from overloading.

[0031] like Figure 1 As shown, the electric device further comprises a slip ring 8, through which an external power source supplies power to the armature winding 6 to prevent the wires from winding.

[0032] like Figure 1 As shown, the electric device further includes a coupling 9 , and the first rotor 2 is connected to the clutch 5 via the coupling 9 , so that the mechanical energy of the first rotor 2 is transmitted to the clutch 5 and the generator 3 .

[0033] Embodiment 2

[0034] like Figure 2 As shown, the difference between this embodiment and the first embodiment is that the first rotor 2 is arranged inside the second rotor 21 .

[0035] Embodiment 3

[0036] like Figure 3 As shown, the difference between this embodiment and the first embodiment is that the second rotor 21 is provided with an armature winding 6 , and the first rotor 2 is provided with a cage-type conducting bar 7 .

[0037] Embodiment 4

[0038] like Figure 4 As shown, the difference between this embodiment and the first embodiment is that the second rotor 21 is arranged inside the first rotor 2 and the second rotor 21 is provided with an armature winding 6 , and the first rotor 2 is provided with a cage-type conductive bar 7 .

[0039] Embodiment 5

[0040] This embodiment provides a control method for starting the electric device in Embodiments 1 to 4, comprising the following steps performed in sequence:

[0041] Step a: using an external power source to energize the first rotor 2 or the second rotor 21, so that the first rotor 2 and the second rotor 21 rotate in opposite directions;

[0042] Step b: gradually increasing the output torque of the clutch 5, and the power generation mechanism 3 generates a braking torque on the first rotor 2, so that the rotation speed of the first rotor 2 gradually decreases and the rotation speed of the second rotor 21 gradually increases;

[0043] Step c: when the rotation speed of the second rotor 21 reaches a predetermined value, the brake 4 brakes the first rotor 2 .

[0044] This embodiment takes the second rotor 21 as the output shaft, and the first rotor 2 is provided with an armature winding 6, and the second rotor 21 is provided with a cage-type conductive bar 7 as an example. After the armature winding 6 of the first rotor 2 is energized, electromagnetic torques of equal magnitude and opposite directions are generated between the first rotor 2 and the second rotor 21, so that the first rotor 2 and the second rotor 21 rotate in opposite directions. At this time, the slip rate between the second rotor 21 and the air gap magnetic field is small, so the starting current is small. Then, the output torque of the clutch 5 is gradually increased, and the mechanical energy of the first rotor 2 is transmitted to the generator 3 through the clutch 5. Part of the mechanical energy of the first rotor 2 is converted into electrical energy generated by the generator 3, so that the speed of the first rotor 2 is reduced. Due to the speed n of the air gap magnetic field a is the rotational magnetic field speed n0 generated by the armature winding 6 on the first rotor 2 and the mechanical speed n of the first rotor 2 b The algebraic sum of n a =n0-n b , so the speed of the air gap magnetic field n a The speed of the second rotor 21 gradually increases. When the speed of the second rotor 21 reaches a predetermined value, the brake 4 brakes the first rotor 2, and the second rotor 21 rotates at the rated speed. By controlling the time when the output torque of the clutch 5 rises, the acceleration time of the second rotor 21 can be controlled, thereby controlling the starting current of the armature winding 6.

[0045] Embodiment 6

[0046] This embodiment provides a control method for adjusting the speed of an electric device started by the control method in the fifth embodiment.

[0047] This embodiment includes the following steps performed in sequence after step c:

[0048] Step d1: The brake 4 no longer brakes the first rotor 2;

[0049] Step e1: Adjust the output torque of the clutch 5.

[0050] This embodiment takes the second rotor 21 as the output shaft, and the first rotor 2 is provided with an armature winding 6, and the second rotor 21 is provided with a cage-type guide bar 7 as an example. In step d1, after the brake 4 no longer brakes the first rotor 2, the output torque of the clutch 5 is changed according to the target speed of the second rotor, and the speed of the first rotor 2 gradually increases or decreases, and the speed of the second rotor 21 gradually decreases or increases. The first rotor 2 transfers a part of the mechanical energy to the generator 3 according to the output torque of the clutch 5, and the part of the mechanical energy is converted into electrical energy generated by the generator 3. The remaining mechanical energy enables the first rotor 2 to maintain rotation at a certain speed, thereby enabling the second rotor 21 to maintain rotation at the required speed. Smoothly adjusting the output torque of the clutch 5 can smoothly adjust the output speed of the second rotor 21.

[0051] Embodiment 7

[0052] This embodiment provides a control method for limiting the torque of an electric device started by the control method in the fifth embodiment.

[0053] Specifically, the first rotor 2 and the second rotor 21 are respectively provided with an armature winding 6 and a cage-type conductive bar 7, or the first rotor 2 and the second rotor 21 are respectively provided with a cage-type conductive bar 7 and an armature winding 6; the electric device also includes a processor and a detection unit for detecting the current of the armature winding 6, and the output end of the detection unit is electrically connected to the control end of the brake 4 and the control end of the clutch 5 through the processor.

[0054] This embodiment includes the following steps performed after step c:

[0055] Step d2: When the detection unit detects that the current of the armature winding 6 reaches the set value, the brake 4 is controlled to stop braking the first rotor 2 and the clutch 5 is controlled to operate with slip.

[0056] The current of the armature winding 6 has a linear relationship with the output torque of the second rotor 21. This embodiment takes the second rotor 21 as the output shaft, and the first rotor 2 is provided with the armature winding 6, and the second rotor 21 is provided with the cage-type guide bar 7 as an example. When the current of the armature winding 6 reaches the set value, the output torque of the second rotor 21 reaches the limit value. At this time, the brake 4 no longer brakes the first rotor 2, and the clutch 5 is operated with slip, the speed of the first rotor 2 increases, and the second rotor 21 slows down. The clutch 5 operates with slip so that the first rotor 2 transfers part of the mechanical energy to the generator 3, and the part of the mechanical energy is converted into the electrical energy generated by the generator 3. The remaining mechanical energy allows the first rotor 2 to maintain rotation at a certain speed, and the second rotor 21 to maintain rotation at a speed corresponding to the limited torque value. At this time, the speed of the second rotor 21 is smaller than the speed of the second rotor 21 when the current of the armature winding 6 reaches the set value. For the dragged load, as the speed of the second rotor 21 decreases, the output torque of the second rotor 21 also decreases, and the current of the armature winding 6 decreases. Therefore, this embodiment can achieve the effect of reducing the output torque of the second rotor 21.

[0057] Embodiment 8

[0058] This embodiment provides a control method for soft-stopping an electric device started by the control method in the fifth embodiment.

[0059] This embodiment includes the following steps performed in sequence after step c:

[0060] Step d3: The brake 4 is no longer braking the first rotor 2;

[0061] Step e3: gradually reducing the output torque of the clutch 5;

[0062] Step f3: When the rotation speed of the second rotor 21 is lower than a certain value, the power supply to the first rotor 2 or the second rotor 21 is cut off.

[0063] Soft parking means that the speed of the second rotor 21 is gradually reduced until it stops. This embodiment takes the second rotor 21 as the output shaft, and the first rotor 2 is provided with an armature winding 6, and the second rotor 21 is provided with a cage-type guide bar 7 as an example. During soft parking, when the brake 4 no longer brakes the first rotor 2, the clutch 5 is input with an excitation current from large to small, the speed of the first rotor 2 gradually increases, and the speed of the second rotor 21 gradually decreases. This embodiment controls the acceleration of the second rotor 21 by controlling the output torque of the clutch 5. In the process of gradually decreasing the output torque of the clutch 5, the speed of the first rotor 2 gradually increases, so that the speed of the second rotor 21 gradually decreases. When the speed of the second rotor 21 is lower than a certain value, the power supply to the first rotor 2 is cut off, so that the second rotor 21 gradually stops, thereby achieving soft parking.

[0064] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention is disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments according to the technology of the present invention are within the scope of the technical solution of the present invention without departing from the content of the technical solution of the present invention.

Claims

1. An electric device, characterized in that: The invention comprises a housing (1), a power generation mechanism (3) for generating electricity, and a first rotor (2) and a second rotor (21) both of which are rotatably connected to the housing (1); the power generation mechanism (3) is provided with a power generation rotor; the first rotor (2) is connected with a brake (4) and a clutch (5); the first rotor (2) is connected to the power generation rotor of the power generation mechanism (3) via the clutch (5); the power generation mechanism (3) generates a braking torque on the first rotor (2) so that the rotation speed of the first rotor (2) is reduced; the first rotor (2) is arranged inside the second rotor (21) or outside the second rotor (21) is arranged inside the first rotor (2), and the electric device is used to use an external power supply to energize the first rotor (2) or the second rotor (21), so that the first rotor (2) and the second rotor (21) rotate in opposite directions; the output torque of the clutch (5) is gradually increased, and the power generation mechanism (3) generates a braking torque on the first rotor (2), so that the rotation speed of the first rotor (2) is gradually reduced and the rotation speed of the second rotor (21) is gradually increased; when the rotation speed of the second rotor (21) reaches a predetermined value, the brake (4) brakes the first rotor (2).

2. An electric device according to claim 1, characterized in that: The power generating rotor of the power generating mechanism (3) is made of permanent magnets.

3. An electric device according to claim 1, characterized in that: The clutch (5) is a hysteresis clutch, an electromagnetic slip clutch, a magnetic powder clutch, a hydraulic clutch, or a pneumatic clutch.

4. An electric device according to claim 3, characterized in that: The first rotor (2) and the second rotor (21) are respectively provided with an armature winding (6) and a cage-type conducting bar (7), or the first rotor (2) and the second rotor (21) are respectively provided with a cage-type conducting bar (7) and an armature winding (6); The electric device also includes a processor and a detection unit for detecting the current of the armature winding (6), and the output end of the detection unit is electrically connected to the control end of the brake (4) and the control end of the clutch (5) through the processor.

5. An electric device according to claim 1, characterized in that: The electric device further comprises a slip ring (8), and an external power source supplies power to the armature winding (6) via the slip ring (8).

6. An electric device according to claim 1, characterized in that: The electric device also includes a coupling (9), and the first rotor (2) is connected to the clutch (5) via the coupling (9).

7. A control method for the electric device according to claim 1, characterized in that: The process includes the following steps: Step a: using an external power source to energize the first rotor (2) or the second rotor (21), so that the first rotor (2) and the second rotor (21) rotate in opposite directions; Step b: gradually increasing the output torque of the clutch (5), so that the power generation mechanism (3) generates a braking torque on the first rotor (2), so that the rotation speed of the first rotor (2) gradually decreases and the rotation speed of the second rotor (21) gradually increases; Step c: When the rotation speed of the second rotor (21) reaches a predetermined value, the brake (4) is used to brake the first rotor (2).

8. The control method according to claim 7, characterized in that: The control method further comprises the following steps which are performed in sequence after step c: Step d1: The brake (4) is no longer braking the first rotor (2); Step e1: Regulating the output torque of the clutch (5).

9. The control method according to claim 7, characterized in that: The first rotor (2) and the second rotor (21) are respectively provided with an armature winding (6) and a cage-type conducting bar (7), or the first rotor (2) and the second rotor (21) are respectively provided with a cage-type conducting bar (7) and an armature winding (6); The electric device also includes a processor and a detection unit for detecting the current of the armature winding (6), wherein the output end of the detection unit is electrically connected to the control end of the brake (4) and the control end of the clutch (5) through the processor; The control method further comprises the following steps performed after step c: Step d2: When the detection unit detects that the current of the armature winding (6) reaches a set value, the brake (4) is stopped from braking the first rotor (2), and the clutch (5) is operated in a slipping manner.

10. The control method according to claim 7, characterized in that: The control method further comprises the following steps which are performed in sequence after step c: Step d3: The brake (4) is no longer braking the first rotor (2); Step e3: gradually reducing the torque value transmitted by the clutch (5); Step f3: When the rotation speed of the second rotor (21) is lower than a certain value, the power supply to the first rotor (2) or the second rotor (21) is cut off.

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