Transmission system and motor starting control method

Abstract

The invention discloses a transmission system and a motor starting control method. The transmission system comprises a motor; one end of the speed regulator is connected with the motor, and the other end is disconnected with the load before the motor is started and connected with the load after the motor is started; the control system is used for controlling the operation states of the motor and the speed regulator; before the motor is started, the control system controls the motor to be powered off and controls the speed regulator to be powered on, so that the speed regulator drives the motor to rotate, and when the motor reaches the rated rotating speed, the control system controls the speed regulator to be powered off and simultaneously controls the motor to be powered on. According to the invention, the starting impact can be reduced, the influence on the motor and the power grid is reduced, the current demand during starting is reduced, the capacity of a power grid system is reduced, smooth starting can be realized, the motor is driven to rotate through the speed regulator, the motor generates no-load counter electromotive force, and the motor can be started more stably when electrified; the reliability and the stability of motor starting are improved, and the mechanical stress during motor starting is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical engineering, and in particular to a transmission system and a motor starting control method. Background Art

[0002] At present, motors often face problems such as large starting shock and excessive starting capacity during starting, which leads to increased losses in the motor and its drive system and reduced reliability. Existing motor starting solutions fail to effectively solve these problems, limiting the starting efficiency and performance of motors under different working conditions.

[0003] Asynchronous start and synchronous operation means that the motor is directly connected to the power supply for starting. The motor of this starting mode needs to add an asynchronous starting cage, increase the amount of magnetic steel and the core size of the permanent magnet rotor, etc. This starting mode has the following disadvantages: First, the starting capacity requirement is relatively large, generally 9-10 times the rated capacity, and the capacity of load starting may reach 11-13 times, causing impact on the power grid; second, the starting impact is large and the starting time is short. Because the high starting current may exceed the rated bearing capacity of the motor, it is not suitable for high-power motors. Summary of the invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the current motor starting method, such as large starting capacity and large starting impact, thereby providing a transmission system and a motor starting control method.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A transmission system, comprising:

[0007] Motor;

[0008] A speed regulator, one end of which is connected to the motor, and the other end of which is disconnected from the load before the motor is started and connected to the load after the motor is started;

[0009] A control system, the control system is used to control the operating status of the motor and the speed regulator; before the motor is started, the control system controls the motor to be powered off, and the control system controls the speed regulator to be powered on, so that the speed regulator drives the motor to rotate, and when the motor reaches its rated speed, the control system controls the speed regulator to be powered off and controls the motor to be powered on at the same time.

[0010] To further optimize the technical solution, the motor and the power supply are connected via a first line, a first switch is provided on the first line, and the control system is used to control the on and off of the first switch to control the connection between the motor and the power supply.

[0011] Further optimizing the technical solution, the control system includes:

[0012] An inverter, one end of which is electrically connected to a power source, and the other end of which is electrically connected to a speed regulator.

[0013] Further optimize the technical solution, the inverter is a four-quadrant inverter, and the four-quadrant inverter is connected with a second circuit, a third circuit, a fourth circuit and a fifth circuit; one end of the fifth circuit is connected to the power supply, and the other end of the fifth circuit is connected to the input end of the four-quadrant inverter; one end of the second circuit is connected to the output end of the four-quadrant inverter, and the other end of the second circuit is connected to the input end of the speed regulator, and a second switch is provided on the second circuit; one end of the third circuit is connected to the power supply, and the other end of the third circuit is connected to the second circuit located between the output end of the four-quadrant inverter and the second switch, and a third switch is provided on the third circuit; one end of the fourth circuit is connected to the fifth circuit, and the other end of the fourth circuit is connected to the second circuit located between the second switch and the speed regulator, and a fourth switch is provided on the fourth circuit;

[0014] The four-quadrant inverter has a forward use state and a reverse use state; before the motor is started, when the four-quadrant inverter needs to be in the forward use state, the second switch is closed to energize the speed regulator, and when the speed regulator drives the motor to reach the rated speed of the motor, the first switch is closed to energize the motor; after the motor is started, when the four-quadrant inverter needs to be in the reverse use state, the second switch is opened, the first switch, the third switch and the fourth switch are closed, and the slip power generated by the speed regulator is converted into electrical energy through the four-quadrant inverter and fed back to the power supply.

[0015] The technical solution is further optimized, and the inverter feedback capacity of the four-quadrant inverter is 14.8% of the rated capacity of the system.

[0016] To further optimize the technical solution, the control system further includes:

[0017] A three-phase rectifier circuit, wherein the three-phase rectifier circuit is arranged between the power supply and the four-quadrant inverter;

[0018] The power supply is an industrial frequency power supply; before the motor is started, the three-phase rectifier circuit converts the three-phase AC power of the power supply into DC power, and then converts the DC power into AC power through a four-quadrant inverter to drive the speed regulator to rotate; when the motor is not running at full load, the slip power generated by the speed regulator is converted into DC power through a four-quadrant inverter, and then the DC power is converted into AC power through a three-phase rectifier circuit and fed back to the power supply.

[0019] To further optimize the technical solution, the control system further includes:

[0020] The switching power supply circuit is used to control the voltage and current output by the inverter, so that the motor starts with low torque at the initial start-up stage and responds quickly to load changes after the motor starts.

[0021] To further optimize the technical solution, the switching power supply circuit is a PWM circuit or a BOOST boost circuit.

[0022] Further optimizing the technical solution, the speed regulator is a winding permanent magnet speed regulator, and the winding permanent magnet speed regulator includes:

[0023] Governor housing;

[0024] A winding rotor, the winding rotor is rotatably arranged inside the speed regulator housing, and the winding rotor is coaxially connected to the output shaft of the motor;

[0025] A permanent magnet rotor, which is rotatably arranged inside the speed regulator housing and is coaxially connected to the load;

[0026] The brake is arranged inside the speed regulator housing; the brake has a first position and a second position; before the motor is started, the control system controls the brake to be in the first position, and the permanent magnet rotor is fixedly connected to the speed regulator housing; after the motor is started, the control system controls the brake to be in the second position, the permanent magnet rotor is disconnected from the speed regulator housing, the winding rotor is energized, and the magnetic field generated by the winding rotor interacts with the magnetic field generated by the permanent magnet rotor, so that the permanent magnet rotor drives the load to rotate.

[0027] Further optimizing the technical solution, the winding rotor is fixedly arranged on the rotating component, the rotating component is fixedly connected to the first rotating shaft, and the first rotating shaft is coaxially connected to the output shaft of the motor through the first coupling;

[0028] The permanent magnet rotor is fixedly arranged on the inner side wall of the rotating cylinder, and the permanent magnet rotor is located at the periphery of the winding rotor and has an air gap between the permanent magnet rotor; one side wall of the rotating cylinder is rotatably arranged on the first rotating shaft, and the other side wall of the rotating cylinder is fixedly arranged on the second rotating shaft, and the second rotating shaft is rotatably arranged on the speed regulator housing, and the end of the second rotating shaft extends out of the speed regulator housing and is connected to the load through the second coupling.

[0029] A motor starting control method, the method is performed based on the transmission system, and comprises the following steps:

[0030] Before the motor starts, the control system controls the motor to be powered off, and the control system controls the speed regulator to be powered on, so that the speed regulator drives the motor to rotate and the motor generates no-load back electromotive force; when the motor reaches its rated speed, the control system controls the speed regulator to be powered off and the motor to be powered on at the same time;

[0031] After the motor is started, the speed regulator is connected to the load through the control system.

[0032] To further optimize the technical solution, before the motor starts, while the speed regulator is driving the motor to rotate, the motor status is monitored in real time, the voltage and current output by the inverter are controlled through the switching power supply circuit, and then the voltage and current of the winding rotor of the speed regulator are controlled to control the speed of the motor.

[0033] To further optimize the technical solution, after the speed regulator is connected to the load through the control system, the voltage and current of the speed regulator winding rotor are adjusted based on the load size or production needs to adjust the speed and torque of the motor.

[0034] The technical solution of the present invention has the following advantages:

[0035] 1. The transmission system provided by the present invention can reduce the starting shock and the impact on the motor and the power grid: the motor is first driven to rotate smoothly by the speed regulator, and then the motor can be switched to the direct power supply state after the motor reaches its rated speed. Since the motor has already generated a certain speed when starting, the motor rotor will generate back electromotive force when rotating in the magnetic field. The existence of back electromotive force helps to reduce the starting current, thereby avoiding the starting shock to the power grid when the motor is directly connected to the power supply for starting.

[0036] The transmission system provided by the present invention reduces the current demand at startup and reduces the capacity of the power grid system: since the speed regulator provides part of the torque required by the motor at the initial stage, it actually replaces part of the starting power demand of the motor to some extent. Because the motor has obtained a certain speed and torque through the power supply of the speed regulator before reaching a stable state, the starting capacity demand of the power supply is also reduced.

[0037] The above-mentioned transmission system can start smoothly, and drives the motor to rotate through the speed regulator, so that the motor generates no-load back electromotive force, which helps the motor to start more smoothly when power is supplied, improves the reliability and stability of the motor starting, reduces the mechanical stress during motor starting, and prolongs the service life of the motor.

[0038] 2. The transmission system provided by the present invention can fix the permanent magnet rotor on the speed regulator housing by the brake before the motor starts, so as to avoid direct impact on the load when the motor starts. When the motor reaches the rated speed, the brake is released, the permanent magnet rotor starts to rotate, and then drives the load to rotate, so that a smooth start can be achieved and the mechanical stress during startup can be reduced. Smooth start can reduce the current peak when the motor starts, avoid damage to the motor due to excessive starting current, and extend the service life of the motor. The speed regulator can flexibly adjust the starting and operating parameters of the motor according to different load requirements to adapt to a variety of working environments and load conditions.

[0039] 3. The transmission system and control system provided by the present invention include an inverter, which can convert a stable DC power supply into the required AC power, which is suitable for various types of loads. The speed regulator can adjust the speed of the motor as needed to achieve precise speed control. The combination of the inverter and the speed regulator can quickly respond to load changes and ensure that the motor can operate stably under different working conditions.

[0040] 4. The transmission system provided by the present invention, the four-quadrant inverter can control the rotation of the motor in the forward and reverse directions, which makes it possible to flexibly control the winding rotor in the winding permanent magnet speed regulator, and to achieve precise control of the speed by adjusting the frequency and voltage. The bidirectional energy conversion function of the four-quadrant inverter enables the system to operate efficiently in different working modes, whether it is driving the motor or recovering energy. Through precise control and efficient conversion, the loss of energy during transmission and conversion is reduced. The system can realize two working modes, forward and reverse, by switching the state of the switch, which enhances the flexibility and adaptability of the system. The combination of the four-quadrant inverter and the speed regulator can quickly respond to changes in system requirements and ensure that the system can operate stably under different working conditions. The four-quadrant inverter can realize soft starting of the motor, reduce the impact current and mechanical stress when the motor starts, and improve the running stability of the system.

[0041] 5. The motor starting control method provided by the present invention drives the motor to rotate in advance through the speed regulator, so that the motor has reached a certain speed before power is turned on, reducing the current impact and mechanical stress during starting, and avoiding severe vibration and wear of the motor and related mechanical parts. Smooth starting can significantly reduce the wear of the motor and mechanical parts and extend their service life.

[0042] Through the precise control of the speed regulator, the motor can reach a predetermined speed before starting, ensuring that the motor can smoothly transition to the working state when starting, and can quickly respond to load changes to ensure that the motor can operate stably under different working conditions.

[0043] By pre-starting the motor, it can quickly reach the rated speed when powered on, shortening the start-up time. The pre-start process increases the success rate of motor starting, especially under heavy load conditions.

[0044] After the motor is started, in normal operation, the permanent magnet motor drives the winding permanent magnet speed regulator, and then the winding permanent magnet speed regulator drives the square torque load of fans and water pumps. According to production or process requirements, when the load does not need to run at full load, the winding current in the winding permanent magnet speed regulator can be controlled to adjust the output speed and torque to meet the load requirements. At this time, the winding in the winding permanent magnet speed regulator generates slip power, which can be led out through the collector ring brush holder, and then used in reverse through the four-quadrant inverter to convert DC power into AC power frequency power and feed it back to the power supply end, thereby achieving power saving effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0046] Figure 1 A schematic diagram of the structure of the transmission system provided by the present invention;

[0047] Figure 2 A schematic diagram of a partial structure of a transmission system provided by the present invention;

[0048] Figure 3 This is a control flow chart of the motor starting process of the present invention.

[0049] Reference numerals:

[0050] 1. Motor, 11. First circuit, 12. First switch, 2. First coupling, 3. Speed ​​regulator, 31. Winding rotor, 32. Permanent magnet rotor, 33. Brake, 34. First rotating shaft, 35. Rotating cylinder, 36. Second rotating shaft, 37. First bearing, 39. Speed ​​regulator housing, 310. Rotating part, 311. Second bearing, 312. Third bearing, 313. Fourth bearing, 4. Collector ring brush holder, 5. Second coupling, 6. Four-quadrant inverter, 61. Second switch, 62. Third switch, 63. Fourth switch, 64. Second circuit, 65. Third circuit, 66. Fourth circuit, 67. Fifth circuit, 7. Power supply, 8. Load. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it 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 it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0054] At present, motors often face problems such as large starting shock and excessive starting capacity during the starting process. When the motor starts, the rotor has not yet rotated, and the resistance of the stator winding is relatively low. When the starting current is much larger than the normal motor operating current, a large amount of heat will be generated, causing the motor temperature to rise rapidly. The high starting torque generated when the motor starts will cause a strong mechanical shock to the transmission system, resulting in increased losses in the motor and its drive system and reduced reliability. Existing motor starting solutions have failed to effectively solve these problems, which limits the motor starting efficiency and performance under different working conditions.

[0055] Asynchronous start and synchronous operation means that the motor is directly connected to the power supply for starting. The motor of this starting method needs to add an asynchronous starting cage, increase the amount of magnetic steel and the core size of the permanent magnet rotor, etc. This starting method has the following disadvantages:

[0056] First, because the squirrel cage winding will generate a large induced current at startup, the demand for starting current is further increased. The increased amount of magnetic steel and the core size of the permanent magnet rotor will increase the current demand when the motor starts. The above reasons will lead to a large starting capacity requirement for the motor, generally 9-10 times the rated capacity, and the capacity for load starting may reach 11-13 times, causing an impact on the power grid.

[0057] Second, high starting current will cause high starting torque when the motor starts, and high starting torque will cause large starting impact and short starting time of the motor. Because high starting current may exceed the rated bearing capacity of the motor, it is not suitable for high-power motors.

[0058] The inverter starts and runs by adjusting the frequency and voltage of the motor to achieve smooth start. The inverter is the most common way to accurately control the startup process, reduce the starting current, and provide a wide speed range. However, the high-voltage inverter is expensive, the investment in the inverter is large, and regular maintenance and repair are required. Once the inverter is damaged, the motor cannot obtain the required frequency and voltage to start normally. In addition, the inverter must always be connected in series with the motor system to run, which will increase the complexity of the system and the maintenance workload.

[0059] Based on this, the present invention provides a transmission system and a motor starting control method, which reduces the impact and current consumption during motor starting by combining a four-quadrant inverter and a winding permanent magnet speed regulator, thereby improving the starting performance and overall efficiency of the motor.

[0060] The present invention uses a small-capacity four-quadrant inverter in the forward direction, passes current into the permanent magnet governor winding rotor, starts the governor permanent magnet rotor to the rated speed of the motor, and the governor permanent magnet rotor drives the motor permanent magnet rotor to rotate synchronously, then instantly passes industrial frequency power through the motor winding and disconnects the power supply of the permanent magnet governor winding rotor. The transmission system of the present invention uses a combination of a four-quadrant inverter and a winding permanent magnet governor to optimize the motor starting process. The present invention reduces the starting current and starting impact of the motor by adjusting the output of the four-quadrant inverter.

[0061] Example 1

[0062] like Figure 1 to Figure 2 As shown, this embodiment discloses a transmission system, including a motor 1, a speed regulator 3, and a control system. The motor 1 is a driving permanent magnet motor. The power supply 7 is used to provide electric energy to the motor 1 and the speed regulator 3. One end of the speed regulator 3 is connected to the motor 1, and the other end of the speed regulator 3 is disconnected from the load before the motor 1 is started, and is connected to the load after the motor 1 is started. The control system is used to control the operating state of the motor 1 and the speed regulator 3. Before the motor 1 is started, the control system controls the motor 1 to be disconnected from the power supply 7, so that the motor 1 is powered off, and the control system controls the speed regulator 3 to be connected to the power supply 7, so that the speed regulator 3 is powered on, and then the speed regulator 3 drives the motor 1 to rotate. When the motor 1 reaches its rated speed, the control system controls the speed regulator 3 to be powered off and controls the motor 1 to be powered on at the same time.

[0063] The above transmission system can reduce the starting shock: the speed regulator 3 first drives the motor 1 to rotate smoothly, and then switches to the direct power supply state of the motor 1 after the motor 1 reaches its rated speed. Since the motor 1 has generated a certain speed when starting, the motor rotor will generate back electromotive force when rotating in the magnetic field. The existence of the back electromotive force helps to reduce the starting current, thereby avoiding the starting shock to the power grid when the motor 1 is directly connected to the power supply for starting.

[0064] Among them, the specific control principle of the transmission system to reduce the starting impact is:

[0065] The voltage equation of a permanent magnet motor can be expressed as:

[0066] V=E+I×R

[0067] Where: V is the terminal voltage (input voltage), E is the back electromotive force (no-load back electromotive force), I is the starting current of the motor, and R is the stator resistance of the motor;

[0068] When the motor 1 starts, the motor rotor rotates in the magnetic field, generating a back electromotive force E. As the angular velocity of the motor 1 increases, the back electromotive force E also increases. When the back electromotive force increases, the terminal voltage V must overcome the back electromotive force and the resistance voltage drop, resulting in a decrease in the starting current:

[0069] I=(VE) / R

[0070] Therefore, during the starting process of the motor 1, the inverter output voltage V is adjusted and the motor speed is increased to increase the back electromotive force E, thereby effectively reducing the starting current and reducing the impact on the power grid. When the motor 1 is already in operation, connecting the motor 1 to the power supply can provide a stable power supply for the motor 1.

[0071] The transmission system described above can reduce the starting capacity: since the speed regulator 3 provides part of the torque required by the motor 1 at the start-up stage, it actually replaces part of the starting power demand of the motor 1 to some extent. Therefore, the starting capacity demand of the power supply is also reduced, because the motor 1 has obtained a certain speed and torque through the power supply of the speed regulator 3 before reaching a stable state.

[0072] Among them, the specific control principle of the transmission system to reduce the starting capacity is:

[0073] Starting torque T of the motor s and inertia load torque T load The relationship can be expressed as:

[0074] T s =K×φ×I

[0075] Where: K is a constant, φ is the magnetic flux of the permanent magnet, and I is the starting current of the motor;

[0076] At the same time, start the angular velocity ω st and start time T st It can be expressed as:

[0077] ω st =(T S -T load )σ / J×T st

[0078] Where: J is the moment of inertia of the motor and load;

[0079] From the above formula, we can see that the starting torque T s Must be greater than or equal to the load torque T load To reduce the starting torque and starting impact, the present invention adopts the following control strategy during the starting process: by adjusting the inverter output voltage and current, the motor 1 starts with a lower torque at the beginning of the start-up to avoid the impact caused by the instantaneous high starting torque. By adjusting the acceleration process of the motor 1, the starting angular velocity ω is controlled. st , so that it changes within a stable range and reduces mechanical shock during startup.

[0080] The transmission system can start smoothly, reduce the mechanical stress of the motor 1 when starting, and extend the service life of the motor.

[0081] In some embodiments, the speed regulator 3 is a winding permanent magnet speed regulator, which includes a speed regulator housing 39, a winding rotor 31, a permanent magnet rotor 32 and a brake 33. The winding rotor 31 is rotatably arranged inside the speed regulator housing 39, and the winding rotor 31 is coaxially connected to the output shaft of the motor 1. The permanent magnet rotor 32 is rotatably arranged inside the speed regulator housing 39, and the permanent magnet rotor 32 is coaxially connected to the load 8. The brake 33 is an electromagnetic brake, or a mechanical brake. The brake 33 is arranged inside the speed regulator housing 39. The brake 33 has a first position and a second position; before the motor 1 is started, the control system controls the brake 33 to be in the first position, and the permanent magnet rotor 32 is fixedly connected to the speed regulator housing 39. After the motor 1 is started, the control system controls the brake 33 to be in the second position, the permanent magnet rotor 32 is disconnected from the speed regulator housing 39, the winding rotor 31 is energized, and the magnetic field generated by the winding rotor 31 interacts with the magnetic field generated by the permanent magnet rotor 32 to generate an electromagnetic torque, so that the permanent magnet rotor 32 drives the load to rotate.

[0082] In this embodiment, the permanent magnet rotor 32 is fixed to the speed regulator housing 39 by the brake 33 before the motor 1 is started, so that the direct impact on the load when the motor 1 is started can be avoided. When the motor 1 reaches the rated speed, the brake 33 is released, the permanent magnet rotor 32 starts to rotate, and then drives the load to rotate, so that a smooth start can be achieved and the mechanical stress at the start can be reduced. Smooth start can reduce the current peak when the motor 1 is started, avoid the motor from being damaged by excessive starting current, and extend the service life of the motor 1. The speed regulator 3 can flexibly adjust the starting and operating parameters of the motor 1 according to different load requirements to adapt to a variety of working environments and load conditions.

[0083] More specifically, the winding rotor 31 is fixedly disposed on the rotating component 310 , the rotating component 310 is fixedly connected to the first rotating shaft 34 , and the first rotating shaft 34 is coaxially connected to the output shaft of the motor 1 through the first coupling 2 .

[0084] The permanent magnet rotor 32 is fixedly arranged on the inner side wall of the rotating cylinder 35, the first rotating shaft 34 passes through the rotating cylinder 35, and the permanent magnet rotor 32 is located outside the winding rotor 31 and has an air gap with the permanent magnet rotor 32. The air gap can reduce the mechanical contact between the permanent magnet rotor 32 and the winding rotor 31, thereby reducing friction loss. The existence of the air gap enables the magnetic field to be effectively transmitted between the winding rotor 31 and the permanent magnet rotor 32, ensuring the generation of electromagnetic torque.

[0085] One side wall of the rotating cylinder 35 is rotatably arranged on the first rotating shaft 34 through the first bearing 37, and the other side wall of the rotating cylinder 35 is fixedly arranged on the second rotating shaft 36. The second rotating shaft 36 is rotatably arranged on the speed regulator housing 39 through the second bearing 311. The end of the second rotating shaft 36 extends out of the speed regulator housing 39 and is connected to the load through the second coupling 5. A first rotating shaft accommodating cavity is arranged on the second rotating shaft 36. The end of the first rotating shaft 34 is located in the first rotating shaft accommodating cavity and is rotatably connected to the second rotating shaft 36 through the third bearing 312. The other end of the first rotating shaft 34 extends out from the speed regulator housing 39 and is rotatably connected to the speed regulator housing 39 through the fourth bearing 313.

[0086] A collector ring brush holder 4 is provided on the second rotating shaft 36 located outside the speed regulator housing 39, and a rotating part, a collector ring and a carbon brush are provided in the collector ring brush holder 4. The rotating part is fixedly connected to the second rotating shaft 36 and can rotate synchronously with the second rotating shaft 36. The collector ring is provided on the rotating part, and the carbon brush is provided on the collector ring brush holder 4. The carbon brush is in sliding contact with the collector ring, and the carbon brush is electrically connected to the second circuit 64.

[0087] The principle of fixing the winding permanent magnet speed regulator and converting the motor is as follows: the permanent magnet rotor 32 of the winding permanent magnet speed regulator is fixed to convert it into a working state of a permanent magnet motor. By supplying power to the winding on the winding rotor of the winding permanent magnet speed regulator, the permanent magnet rotor 32 is activated, causing it to rotate and connect to the motor output shaft, driving the motor's rotor to rotate.

[0088] In some embodiments, the motor 1 is connected to the power supply 7 via a first line 11 , a first switch 12 is provided on the first line 11 , and the control system is used to control the on and off of the first switch 12 to control the connection between the motor 1 and the power supply 7 .

[0089] In some embodiments, the control system includes an inverter, one end of the inverter is electrically connected to the power supply 7, and the other end of the inverter is electrically connected to the speed regulator 3. The inverter can convert a stable DC power supply into the required AC power, which is suitable for various types of loads. The speed regulator 3 can adjust the speed of the motor 1 as needed to achieve precise speed control. The combination of the inverter and the speed regulator 3 can quickly respond to load changes and ensure that the motor 1 can operate stably under different working conditions.

[0090] More specifically, the inverter is a small-capacity four-quadrant inverter 6. The four-quadrant inverter 6 is connected to a second line 64, a third line 65, a fourth line 66 and a fifth line 67. One end of the fifth line 67 is connected to the power supply 7, and the other end of the fifth line 67 is connected to the input end of the four-quadrant inverter 6. One end of the second line 64 is connected to the output end of the four-quadrant inverter 6, and the other end of the second line 64 is connected to the input end of the speed regulator 3, and a second switch 61 is provided on the second line 64. One end of the third line 65 is connected to the power supply 7, and the other end of the third line 65 is connected to the second line 64 located between the output end of the four-quadrant inverter 6 and the second switch 61, and a third switch 62 is provided on the third line 65. One end of the fourth line 66 is connected to the fifth line 67, and the other end of the fourth line 66 is connected to the second line 64 located between the second switch 61 and the speed regulator 3, and a fourth switch 63 is provided on the fourth line 66.

[0091] The four-quadrant inverter 6 has a forward use state and a reverse use state. Before the motor 1 is started, when the four-quadrant inverter 6 needs to be in the forward use state, the second switch 61 is closed to energize the speed regulator 3. When the speed regulator 3 drives the motor 1 to reach the rated speed of the motor, the first switch 12 is closed to energize the motor 1. After the motor 1 is started, when the four-quadrant inverter 6 needs to be in the reverse use state, the second switch 61 is disconnected, the third switch 62 and the fourth switch 63 are closed, and the slip power generated by the speed regulator 3 is converted into electrical energy through the four-quadrant inverter and fed back to the power supply, which can not only reduce energy waste, but also reduce the operating cost of the system. This bidirectional energy conversion capability improves the energy utilization efficiency of the system.

[0092] Capacity of four-quadrant inverter 6:

[0093] According to the characteristics of permanent magnet winding speed regulation for fans and water pumps,

[0094] P n =(n n / nN) 3 ×P N ,

[0095] P n =T n ×n n

[0096] Among them, P n -Load shaft power, T n - Load shaft torque, P N - Load rated power, n N - Load rated speed, n n -Speed ​​under speed regulation n;

[0097] available

[0098] When the wind friction and other losses are ignored, T mn =T n ;

[0099] When n mN =n N hour,

[0100] Among them, T mn - Motor output torque, P mn - Motor output power, n mN - rated motor speed;

[0101] The slip power at speed n can be obtained

[0102] Since the speed ratio i = n n / n N × 100%, we can get ΔP = P mn -P n =(i 2 -i 3 )×P N , take the derivative and set it equal to zero, then we can find the extreme point, dΔP / di=(2i-3i 2 )×P N =0, that is, i=0, i=0.667, then the maximum slip power loss is ΔP=0.148P N Therefore, the inverter feedback capacity of the four-quadrant inverter is approximately 14.8% of the rated capacity of the system.

[0103] In the present embodiment, the four-quadrant inverter 6 can control the rotation of the motor in the forward and reverse directions, which makes it possible to flexibly control the winding rotor in the winding permanent magnet speed regulator, and to achieve accurate control of the speed by adjusting the frequency and voltage. The bidirectional energy conversion function of the four-quadrant inverter 6 enables the system to operate efficiently under different operating modes, whether it is driving the motor or recovering energy. Through precise control and efficient conversion, the loss of energy during transmission and conversion is reduced. The system can realize forward and reverse operating modes by switching the state of the switch, which enhances the flexibility and adaptability of the system. The combination of the four-quadrant inverter 6 and the speed regulator 3 can quickly respond to changes in system requirements, ensuring that the system can operate stably under different working conditions. The four-quadrant inverter 6 can realize the soft start of the motor, reduce the inrush current and mechanical stress when the motor starts, and improve the running stability of the system.

[0104] In some embodiments, the control system further includes a three-phase rectifier circuit, which is arranged between the power supply 7 and the four-quadrant inverter. The power supply is an industrial frequency power supply, that is, the power supply in this embodiment is an AC power supply. Before the motor 1 is started, the three-phase rectifier circuit converts the three-phase AC power of the power supply 7 into DC power, and then converts the DC power into AC power through the four-quadrant inverter to drive the speed regulator 3 to rotate. This two-stage conversion ensures the power quality and stability when the motor is started. When the motor 1 is not running at full load, the slip power generated by the speed regulator 3 is converted into DC power through the four-quadrant inverter, and then the DC power is converted into AC power through the three-phase rectifier circuit and fed back to the power supply 7, which not only reduces energy waste, but also reduces the operating cost of the system. This two-way conversion improves the energy utilization efficiency of the system.

[0105] In this embodiment, a three-phase rectifier circuit is added to the control system, so that the system can more efficiently perform energy conversion and energy recovery when the motor starts and is not running at full load. The combination of the three-phase rectifier circuit and the four-quadrant inverter enables the system to operate efficiently in different operating modes.

[0106] In some embodiments, the control system further includes a switching power supply circuit, which is used to control the voltage and current output by the inverter, so that the motor 1 starts with low torque at the initial start-up stage, which can significantly reduce the impact current and mechanical stress during startup and avoid damage to the motor and related mechanical components. Reducing the startup impact can extend the service life of the motor and other mechanical components and reduce maintenance costs. Low-torque starting makes the motor 1 more stable during the startup process and avoids system instability caused by high starting torque. Low-torque starting can reduce the impact on the power grid and avoid the impact of voltage fluctuations on other equipment.

[0107] After the motor 1 is started, the voltage and current output by the inverter are controlled so that the system can quickly respond to load changes to adapt to different load requirements and ensure that the motor can operate stably under different working conditions.

[0108] The switching power supply circuit is a PWM circuit or a BOOST boost circuit.

[0109] The PWM circuit adjusts the output voltage and current by changing the pulse width to achieve precise control of the motor torque and speed. In the early stage of motor startup, the PWM circuit can output a lower duty cycle, thereby achieving low-torque startup of the motor and reducing startup shock.

[0110] The BOOST boost circuit can increase the input voltage to a higher output voltage, which is suitable for occasions that require high voltage drive. The BOOST boost circuit achieves precise control of the output voltage and current by adjusting the on-time and off-time of the switch tube. When the motor starts, the BOOST boost circuit can provide higher starting torque to help the motor reach the rated speed faster.

[0111] Both the PWM circuit and the BOOST boost circuit can monitor the load changes in real time and quickly adjust the output voltage and current to adapt to different load requirements. Both the PWM circuit and the BOOST boost circuit have fast response capabilities, reducing the system's lag time to load changes and ensuring that the motor always runs in the best condition.

[0112] Example 2

[0113] Combination Figure 3 As shown, this embodiment discloses a motor starting control method, which is based on a transmission system. The method adopts a control strategy combining a four-quadrant inverter with a winding permanent magnet speed regulator. During the motor starting process, the state of the motor 1 is monitored in real time, and the inverter output is adjusted through an intelligent control algorithm to optimize the starting process of the motor 1.

[0114] A motor starting control method specifically comprises the following steps:

[0115] Before the motor 1 is started, the control system controls the first switch 12 between the motor 1 and the power supply 7 to be disconnected, so that the motor 1 is powered off; the four-quadrant inverter in the control system is used in the forward direction (the four-quadrant inverter is used as a frequency converter) to supply power to the winding rotor 31 in the winding permanent magnet speed regulator, and the brake 33 is controlled to fix the permanent magnet rotor 32 on the speed regulator housing 39. At this time, the winding permanent magnet speed regulator becomes a permanent magnet motor, and the winding rotor 31 of the winding permanent magnet speed regulator drives the rotor of the motor 1 to rotate, so that the motor 1 generates no-load back electromotive force. It is judged whether the speed of the motor 1 rotor reaches its rated speed; when the motor 1 rotor does not reach its rated speed, the current and voltage of the winding rotor 31 of the winding permanent magnet speed regulator are regulated; when the motor 1 reaches its rated speed, the speed regulator 3 is controlled to be powered off by the control system, and the motor 1 is powered on, so that the motor 1 is started, so as to reduce the starting impact and starting capacity of the permanent magnet motor.

[0116] Before the motor 1 is started, while the speed regulator 3 is driving the motor 1 to rotate, the state of the motor 1 is monitored in real time, and the voltage and current output by the inverter are controlled through the switching power supply circuit, and then the voltage and current of the winding rotor 31 of the speed regulator 3 are controlled to control the speed of the motor 1. By adjusting the inverter output voltage and current, the motor is started with a lower torque at the initial start-up to avoid the impact caused by the instantaneous high starting torque. By adjusting the acceleration process of the motor 1, the starting angular velocity ω is controlled st , so that it changes within a stable range and reduces the mechanical shock during the startup process. The starting current of the motor can be gradually increased to avoid the shock caused by sudden changes.

[0117] After the motor 1 is started, the current and voltage of the speed regulator winding rotor are controlled by the inverter, and then the load is slowly started, so as to realize the soft start and speed regulation operation of the motor. The specific method is: the brake 33 is controlled to be in the second position by the control system, and the rotating cylinder 35 connected to the permanent magnet rotor 32 is no longer fixedly connected to the speed regulator housing 39. The winding rotor 31 is powered on again, and the magnetic field generated by the winding rotor 31 interacts with the magnetic field generated by the permanent magnet rotor 32, so that the permanent magnet rotor 32 drives the load to rotate synchronously with the winding rotor 31 and the motor rotor.

[0118] After the motor 1 is started, in normal operation, the permanent magnet motor drives the winding permanent magnet speed regulator, and then the winding permanent magnet speed regulator drives the square torque load such as the fan and the water pump. According to production or process requirements, when the load does not need to run at full load, the winding current in the winding permanent magnet speed regulator can be controlled to adjust the output speed and torque to meet the load requirements. At this time, the winding in the winding permanent magnet speed regulator generates slip power, which can be led out through the collector ring brush holder, and then used in reverse through the four-quadrant inverter to convert DC power into AC power frequency power and feed it back to the power supply end, thereby achieving power saving effect.

[0119] After the motor 1 is started, the control system controls the speed regulator 3 to connect to the load, and then adjusts the voltage and current of the speed regulator winding rotor based on the size of the load to adjust the speed and torque of the motor 1. By adjusting the voltage and current of the speed regulator 3 in real time, the motor 1 can respond quickly to changes in the load and ensure stable operation under different load conditions. When the load suddenly increases or decreases, the speed and torque of the motor 1 can be adjusted quickly to avoid mechanical shock and current fluctuations caused by sudden changes in the load. Through real-time adjustment, it is ensured that the motor 1 can operate stably under various load conditions and reduce fluctuations and instability. The control system can automatically adjust according to the load conditions to avoid overload and overheating, provide multiple protection functions, and improve the safety of the system.

[0120] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A transmission system, characterized in that: include: Motor (1); A speed regulator (3), one end of the speed regulator (3) is connected to the motor (1), and the other end of the speed regulator (3) is disconnected from the load before the motor (1) is started and is connected to the load after the motor (1) is started; A control system, the control system is used to control the operating states of a motor (1) and a speed regulator (3); before the motor (1) is started, the control system controls the motor (1) to be powered off, and the control system controls the speed regulator (3) to be powered on, so that the speed regulator (3) drives the motor (1) to rotate; when the motor (1) reaches its rated speed, the control system controls the speed regulator (3) to be powered off and simultaneously controls the motor (1) to be powered on.

2. The transmission system according to claim 1, characterized in that: The motor (1) and the power source (7) are connected via a first line (11), a first switch (12) is provided on the first line (11), and the control system is used to control the on and off of the first switch (12) to control the connection between the motor (1) and the power source (7).

3. The transmission system according to claim 2, characterized in that: The control system comprises: An inverter, one end of which is electrically connected to a power source (7), and the other end of which is electrically connected to a speed regulator (3).

4. The transmission system according to claim 3, characterized in that: The inverter is a four-quadrant inverter (6), and the four-quadrant inverter (6) is connected to a second line (64), a third line (65), a fourth line (66) and a fifth line (67); one end of the fifth line (67) is connected to a power source (7), and the other end of the fifth line (67) is connected to an input end of the four-quadrant inverter (6); one end of the second line (64) is connected to an output end of the four-quadrant inverter (6), and the other end of the second line (64) is connected to an input end of a speed regulator (3); a second switch ( 61); one end of the third line (65) is connected to the power source (7), the other end of the third line (65) is connected to the second line (64) located between the output end of the four-quadrant inverter (6) and the second switch (61), and the third line (65) is provided with a third switch (62); one end of the fourth line (66) is connected to the fifth line (67), the other end of the fourth line (66) is connected to the second line (64) located between the second switch (61) and the speed regulator (3), and the fourth line (66) is provided with a fourth switch (63); The four-quadrant inverter (6) has a forward use state and a reverse use state; before the motor (1) is started, when the four-quadrant inverter (6) needs to be in the forward use state, the second switch (61) is closed to energize the speed regulator (3); when the speed regulator (3) drives the motor (1) to reach the rated speed of the motor, the first switch (12) is closed to energize the motor (1); after the motor (1) is started, when the four-quadrant inverter (6) needs to be in the reverse use state, the second switch (61) is opened, the first switch (12), the third switch (62) and the fourth switch (63) are closed, and the slip power generated by the speed regulator (3) is converted into electric energy through the four-quadrant inverter and fed back to the power supply.

5. The transmission system according to claim 4, characterized in that: The inverter feedback capacity of the four-quadrant inverter (6) is 14.8% of the rated capacity of the system.

6. The transmission system according to claim 3, characterized in that: The control system further comprises: A three-phase rectifier circuit, wherein the three-phase rectifier circuit is arranged between the power supply (7) and the four-quadrant inverter; The power supply is an industrial frequency power supply; before the motor (1) is started, the three-phase rectifier circuit converts the three-phase alternating current of the power supply (7) into direct current, and then converts the direct current into alternating current through a four-quadrant inverter to drive the speed regulator (3) to rotate; when the motor (1) is not running at full load, the slip power generated by the speed regulator (3) is converted into direct current through a four-quadrant inverter, and then the direct current is converted into alternating current through a three-phase rectifier circuit and fed back to the power supply (7).

7. The transmission system according to claim 3, characterized in that: The control system further comprises: A switching power supply circuit is used to control the voltage and current output by an inverter, so that the motor (1) starts with low torque at the initial start-up stage and quickly responds to load changes after the motor (1) starts.

8. The transmission system according to claim 7, characterized in that: The switching power supply circuit is a PWM circuit or a BOOST boost circuit.

9. The transmission system according to any one of claims 1 to 8, characterized in that: The speed regulator (3) is a winding permanent magnet speed regulator, and the winding permanent magnet speed regulator comprises: Governor housing (39); A winding rotor (31), the winding rotor (31) being rotatably disposed inside a speed regulator housing (39), and the winding rotor (31) being coaxially connected to an output shaft of the motor (1); A permanent magnet rotor (32), the permanent magnet rotor (32) being rotatably disposed inside a speed regulator housing (39), and the permanent magnet rotor (32) being coaxially connected to a load (8); A brake (33), wherein the brake (33) is arranged inside a speed regulator housing (39); the brake (33) has a first position and a second position; before the motor (1) is started, the control system controls the brake (33) to be in the first position, and the permanent magnet rotor (32) is fixedly connected to the speed regulator housing (39); after the motor (1) is started, the control system controls the brake (33) to be in the second position, and the permanent magnet rotor (32) is disconnected from the speed regulator housing (39), the winding rotor (31) is energized, and the magnetic field generated by the winding rotor (31) interacts with the magnetic field generated by the permanent magnet rotor (32), so that the permanent magnet rotor (32) drives the load to rotate.

10. The transmission system according to claim 9, characterized in that: The winding rotor (31) is fixedly arranged on a rotating component (310), the rotating component (310) is fixedly connected to a first rotating shaft (34), and the first rotating shaft (34) is coaxially connected to an output shaft of the motor (1) via a first coupling (2); The permanent magnet rotor (32) is fixedly arranged on the inner side wall of the rotating cylinder (35); the permanent magnet rotor (32) is located outside the winding rotor (31) and has an air gap between the permanent magnet rotor (32); one side wall of the rotating cylinder (35) is rotatably arranged on a first rotating shaft (34); the other side wall of the rotating cylinder (35) is fixedly arranged on a second rotating shaft (36); the second rotating shaft (36) is rotatably arranged on a speed regulator housing (39); an end of the second rotating shaft (36) extends out of the speed regulator housing (39) and is connected to a load via a second coupling (5).

11. A motor starting control method, characterized in that: The method is performed based on the transmission system according to any one of claims 1 to 10, and comprises the following steps: Before the motor (1) is started, the control system controls the motor (1) to be powered off, and the control system controls the speed regulator (3) to be powered on, so that the speed regulator (3) drives the motor (1) to rotate, and the motor (1) generates a no-load back electromotive force; when the motor (1) reaches its rated speed, the control system controls the speed regulator (3) to be powered off and simultaneously controls the motor (1) to be powered on; After the motor (1) is started, the speed regulator (3) is connected to the load through the control system.

12. The motor starting control method according to claim 11, characterized in that: Before the motor (1) is started, while the speed regulator (3) is driving the motor (1) to rotate, the state of the motor (1) is monitored in real time, and the voltage and current output by the inverter are controlled through a switching power supply circuit, thereby controlling the voltage and current of the winding rotor (31) of the speed regulator (3) to control the rotation speed of the motor (1).

13. The motor starting control method according to claim 11 or 12, characterized in that: After the speed regulator (3) is connected to the load through the control system, the voltage and current of the speed regulator winding rotor are adjusted based on the size of the load to adjust the speed and torque of the motor (1).

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