Voltage reduction and regulation soft starting device suitable for different loads

Abstract

A voltage reduction and regulation soft starting device suitable for different loads comprises an autotransformer, an adjustable reactance device, a starting switch, an operation switch, a star point switch, an isolation switch, a first gear switch, a second gear switch and a third gear switch, and the high-voltage side of the autotransformer is connected with a power supply through the starting switch; the low-voltage side 1 of the autotransformer is connected to the upper end of the first gear switch, the low-voltage side 2 of the autotransformer is connected to the upper end of the second gear switch, and the low-voltage side 3 of the autotransformer is connected to the upper end of the third gear switch; the lower end of the first gear switch, the lower end of the second gear switch and the lower end of the third gear switch are connected and connected to the input end of the adjustable reactance device. The output end of the adjustable reactance device is connected to the motor through the isolating switch; an operation switch is connected in series between the power supply and the motor; and the tail end sides of the autotransformers are connected into a star shape through star point switches. The problem that an existing starting device cannot be normally started due to the fact that mechanical loads change is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of starting devices, in particular to a soft starting device capable of reducing and regulating voltages to adapt to different loads. Background Art

[0002] The electric motor industry is a traditional one. After more than 200 years of development, it has become an indispensable core foundation for modern production and life, and a vital component of the national economy. As a labor-intensive industry, my country has unique advantages in developing its electric motor manufacturing industry. By now, my country's electric motor manufacturing industry has reached a considerable scale, and electric motors are widely used in large and medium-sized high-voltage motors in equipment such as gates, mills, chippers, crushers, fans, compressors, pumps, and belt conveyors in industries such as water conservancy, metallurgy, building materials, petrochemicals, chemicals, mining, sugar refining, water supply, and drainage. High-voltage motors require high current and voltage when starting. These high-power starting current and voltage are completely dependent on the power grid, resulting in unstable grid current and voltage, which directly affects the safety and normal operation of other electrical loads. The starting of high-power high-voltage motors is particularly detrimental to grid power instability.

[0003] Therefore, a high-voltage soft-start device is needed to stabilize the starting current of high-voltage motors without affecting the normal operation of the power grid and other electrical equipment. Currently, a common method is to use a starting device. Existing starting devices mainly include: reactor starting, autotransformer starting, water resistance starting, solid-state soft starting, and inverter starting. All of the above starting devices have the following disadvantages:

[0004] 1. The starting multiple is too high, such as reactor starting, water resistor starting, and solid-state soft starting;

[0005] 2. Poor online adjustability, such as reactor starting, water resistor starting, and autotransformer starting;

[0006] 3. High cost and low reliability, such as solid-state soft start and inverter start;

[0007] 4. Starting problems can occur when the mechanical load varies. For example, a pump impeller becomes jammed by debris, there is excess material on a conveyor belt, or there is residual material inside a grinder, chipper, or crusher. Even slightly heavier loads can easily cause stalling during starting, leading to a failed start. This requires manual cleaning of the residual material inside the mechanical load, resulting in wasted manpower and financial resources, and even personal injury if careless. To address this issue, a soft-start device with voltage regulation and step-down capability is proposed to adapt to varying loads. Summary of the Invention

[0008] The purpose of the utility model is to address the deficiencies of the existing technology and provide a soft starting device that can adapt to different loads and can step down and regulate the voltage. The utility model combines the advantages of an autotransformer and an adjustable reactance device, has the advantages of a low starting multiple, good online adjustability and low cost, and solves the problem that the existing starting device cannot start normally when the mechanical load becomes heavy, and manual cleaning of residual materials on the mechanical load equipment is required. At the same time, the problems of high starting multiple, poor online adjustability, high cost and low applicability are solved.

[0009] In order to solve the above technical problems, the following technical solution is adopted: a soft starting device capable of stepping down and regulating voltage under different loads, comprising an autotransformer, an adjustable reactor, a starting switch, an operating switch, a star point switch, an isolating switch, a first gear switch, a second gear switch, and a third gear switch, characterized in that: the high-voltage side of the autotransformer is connected to a power supply via the starting switch; the low-voltage side 1 of the autotransformer is connected to the upper end of the first gear switch, the low-voltage side 2 of the autotransformer is connected to the upper end of the second gear switch, and the low-voltage side 3 of the autotransformer is connected to the upper end of the third gear switch; the lower ends of the first gear switch, the second gear switch, and the third gear switch are connected and connected to the input end of the adjustable reactor; the output end of the adjustable reactor is connected to the motor via the isolating switch; the operating switch is connected in series between the power supply and the motor; and the tail ends of the autotransformer are connected in a star shape via the star point switch.

[0010] Preferably, the transformation ratio between the low-voltage side 1 and the high-voltage side of the autotransformer is K1;

[0011] Preferably, the transformation ratio between the low-voltage side 2 and the high-voltage side of the autotransformer is K2;

[0012] Preferably, the transformation ratio between the low-voltage side 3 and the high-voltage side of the autotransformer is K3.

[0013] Preferably, the adjustable reactance device adjusts the effective number of turns of the inductor by changing the effective position of the high-permeability iron core magnetic medium within the air-core inductor, thereby varying the magnetic field strength of the inductor, thereby changing the impedance of the inductor and gradually increasing the voltage at the motor terminals. The adjustable reactance device has a step-down voltage regulation ratio of K4.

[0014] As a preferred embodiment, the present invention further proposes a soft starting device for voltage reduction and regulation adapted to different loads, comprising the following steps:

[0015] S1. Before the motor starts, the starting switch connected in series between the high-voltage side of the autotransformer and the power supply, the star-point switch on the tail end of the autotransformer, the running switch connected in series between the power supply and the motor, the first-gear switch, the second-gear switch, and the third-gear switch between the autotransformer and the adjustable reactor, and the isolating switch between the adjustable reactor and the motor are all in the disconnected state;

[0016] S2, when starting, gear selection, the first gear switch, the second gear switch, and the third gear switch are interlocked and can only be closed in three positions. If any one switch is closed, the other two switches cannot be closed;

[0017] 1) When the first gear switch is closed, first close the star point switch and the isolating switch, then close the starting switch. The starting switch synchronously triggers the adjustable reactance device to start working. At this time, the motor starts to start, and the starting terminal voltage is K1K4U n , starting current is K1 2 K4 2 Ilr, realizes smooth speed increase of the motor; U n Indicates the rated voltage on the motor nameplate, and Ilr indicates the locked-rotor current on the motor nameplate;

[0018] 2) When the second gear switch is closed, first close the star point switch and the isolating switch, then close the starting switch. The starting switch synchronously triggers the adjustable reactance device to start working. At this time, the motor starts to start, and the starting terminal voltage is K2K4U n , starting current is K2 2 K4 2 Ilr, realizes smooth speed increase of the motor;

[0019] 3) When the third gear switch is closed, first close the star point switch and the isolating switch, then close the starting switch. The starting switch synchronously triggers the adjustable reactance device to start working. At this time, the motor starts to start, and the starting terminal voltage is K3K4U n , starting current is K3 2 K4 2 Ilr, realizes smooth speed increase of the motor;

[0020] S3. After the motor speed is increased, the star point switch is opened first, and then the operation switch is closed, so that the motor switches to operation through a disturbance-free closed-loop operation, and the start is completed;

[0021] S4. Finally, after the operating switch is closed, the starting switch, the isolating switch and one of the first gear switch, the second gear switch and the third gear switch are opened synchronously to isolate the autotransformer and the adjustable reactor from the power supply.

[0022] The above-described technical solution has the following beneficial effects: The present invention is an adaptive step-down soft-start device that combines the advantages of an autotransformer and an adjustable reactor, offering the advantages of a low starting multiple, good online adjustability, and low cost. When the mechanical load fluctuates and the third gear cannot be started, the device can flexibly switch to the other two gears for starting, thereby increasing the starting torque. For example, if the pump impeller is blocked by debris, there is residual material on the belt conveyor, or there is residual material in the grinder, chipper, or crusher, the device cannot start in the third gear. The other two gears can be used to start the device, eliminating the need to clean the residual material from the mechanical load equipment, thereby improving the applicability of the soft-start device.

[0023] Especially in some chemical enterprises, the fans are used in special environments. The soft start device installed at the beginning can be used. However, as the damper is in a corrosive gas environment for a long time, it is corroded and damaged and cannot be closed normally. The increase in load makes the existing soft start equipment unusable. The utility model can solve this problem very well. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings:

[0025] Figure 1 The utility model is a connection diagram of a voltage-reducing and voltage-regulating soft-starting device adapted to different loads. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and examples. However, it should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Furthermore, descriptions of known structures and technologies are omitted in the following description to avoid unnecessary confusion regarding the concepts of the present invention.

[0027] like Figure 1As shown, the embodiment of the utility model proposes a soft starting device that can adapt to different loads and step down and regulate voltage, including an autotransformer (QZB), an adjustable reactance device (RYZQ), a starting switch (KM1), a running switch (KM2), a star point switch (KM3), an isolating switch (KM4), a first gear switch (KM5), a second gear switch (KM6), and a third gear switch (KM7), wherein the device is characterized in that: the high voltage side of the autotransformer (QZB) is connected to the power supply through the starting switch (KM1); the low voltage side 1 of the autotransformer (QZB) is connected to the upper end of the first gear switch (KM5); and the autotransformer (QZB) is connected to the upper end of the first gear switch (KM6). The low-voltage side 2 of the power supply (ZB) is connected to the upper end of the second gear switch (KM6), and the low-voltage side 3 of the autotransformer (QZB) is connected to the upper end of the third gear switch (KM7); the lower end of the first gear switch (KM5), the lower end of the second gear switch (KM6) and the lower end of the third gear switch (KM7) are connected, and are also connected to the input end of the adjustable reactance device (RYZQ); the output end of the adjustable reactance device (RYZQ) is connected to the motor through the isolating switch (KM4); an operating switch (KM2) is connected in series between the power supply and the motor; and the tail end side of the autotransformer (QZB) is connected in a star shape through a star point switch (KM3).

[0028] As a preference, the transformation ratio of the low-voltage side 1 to the high-voltage side of the autotransformer (QZB) is K1=0.95

[0029] As a preference, the transformation ratio of the low voltage side 2 to the high voltage side of the autotransformer (QZB) is K2=0.8

[0030] As a preference, the transformation ratio of the low voltage side 3 to the high voltage side of the autotransformer (QZB) is K3=0.65

[0031] Preferably, the adjustable reactance device (RYZQ) adjusts the effective number of turns of the inductor by varying the effective position of the high-permeability iron-core magnetic medium within the air-core inductor, thereby varying the magnetic field strength of the inductor and thereby changing the impedance of the inductor, thereby gradually increasing the voltage at the motor terminals. The step-down voltage regulation ratio (K4) of the adjustable reactance device (RYZQ) is in the range of 0.7-0.97.

[0032] The present invention also provides a soft-start device for voltage reduction and regulation adapted to different loads, comprising the following steps:

[0033] S1. Before the motor starts, the starting switch (KM1) connected in series between the high-voltage side of the autotransformer (QZB) and the power supply, the star-point switch (KM3) on the star-point side of the autotransformer (QZB), the running switch (KM2) connected in series between the power supply and the motor, the three position switches between the autotransformer (QZB) and the adjustable reactor device (RYZQ), and the isolating switch (KM4) between the adjustable reactor device and the motor are all in the disconnected state;

[0034] S2. When starting, the gear selection, the first gear switch (KM5), the second gear switch (KM6), and the third gear switch (KM7) are interlocked and can only be three-in-one. If any one switch is closed, the other two switches cannot be closed.

[0035] When the first gear switch (KM5) is closed, the star point switch (KM3) and the isolating switch (KM4) are closed first, and then the starting switch (KM1) is closed. The starting switch (KM1) synchronously triggers the adjustable reactance device (RYZQ) to start working. At this time, the motor starts to start. The starting terminal voltage of the motor is 0.665Un, the initial starting current is 0.4422Ilr, and the motor terminal voltage is adjusted between 0.665Un and 0.921Un to achieve smooth speed increase of the motor.

[0036] When the second gear switch (KM6) is closed, the star point switch (KM3) and the isolating switch (KM4) are closed first, and then the starting switch (KM1) is closed. The starting switch (KM1) synchronously triggers the adjustable reactance device (RYZQ) to start working. At this time, the motor starts to start. The starting terminal voltage of the motor is 0.56Un, the initial starting current is 0.3136Ilr, and the motor terminal voltage is adjusted between 0.56Un and 0.7761Un to achieve smooth speed increase of the motor.

[0037] When the third gear switch (KM7 is closed), first close the star point switch (KM3) and the isolating switch (KM4), and then close the starting switch (KM1). The starting switch (KM1) synchronously triggers the adjustable reactance device (RYZQ) to start working. At this time, the motor starts to start. The starting terminal voltage of the motor is 0.455Un, the initial starting current is 0.2070Ilr, and the motor terminal voltage is adjusted between 0.455Un and 0.6305Un to achieve smooth speed increase of the motor.

[0038] S3. After the motor speed is increased, first open the star point switch (KM3), then close the operation switch (KM2), so that the motor switches to operation through a disturbance-free closed mode, and the start is completed;

[0039] S4. Finally, after the running switch (KM2) is closed, the starting switch (KM1), the isolating switch (KM4) and the gear switch are opened synchronously to isolate the autotransformer (QZB) and the adjustable reactor device (RYZQ) from the power supply.

[0040] When mechanical loads vary, such as when the pump impeller becomes clogged with weeds, when there's excess material on the conveyor belt, when there's excess material in the grinder, chipper, or crusher, or when the fan damper is corroded and unable to close properly, the motor can be started by adjusting the motor terminal voltage between 0.455Un and 0.6305Un in the third gear. Alternatively, the motor terminal voltage can be adjusted between 0.665Un and 0.921Un in the first gear, or between 0.56Un and 0.7761Un in the second gear, to successfully start the motor and the mechanical load. This new soft starter eliminates the need to clean excess material from mechanical loads and improves the applicability of the soft starter.

[0041] The utility model proposes a soft starting device that can adapt to different loads and can realize soft starting in voltage ramp mode. Through closed loop control, it can also realize soft starting in current limiting mode. In addition, the autotransformer (QZB) K 1、 K 2、 K3 can select a lower transformation ratio, thereby achieving a lower starting current, overcoming the problem that the conventional autotransformer (QZB) cannot complete acceleration due to the low transformation ratio; on the other hand, different starting torques of the motor and mechanical load can be achieved by changing the step-down and voltage regulation ratio K4 of the adjustable inductor device (RYZQ) at the beginning of the starting stage.

[0042] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention that solve essentially the same technical problems and achieve essentially the same technical effects are included within the scope of protection of the present invention.

Claims

1. A soft-start device capable of stepping down and regulating voltage under different loads, comprising an autotransformer, an adjustable reactance device, a start switch, a run switch, a star point switch, an isolating switch, a first gear switch, a second gear switch, and a third gear switch, characterized in that: The high-voltage side of the autotransformer is connected to the power supply through the starting switch; the low-voltage side 1 of the autotransformer is connected to the upper end of the first gear switch, the low-voltage side 2 of the autotransformer is connected to the upper end of the second gear switch, and the low-voltage side 3 of the autotransformer is connected to the upper end of the third gear switch; the lower ends of the first gear switch, the second gear switch and the third gear switch are connected, and are connected to the input end of the adjustable reactance device; the output end of the adjustable reactance device is connected to the motor through the isolating switch; an operating switch is connected in series between the power supply and the motor; and the tail end side of the autotransformer is connected in a star shape through a star point switch.

2. The soft starting device capable of stepping down and regulating voltage under different loads according to claim 1, characterized in that: The transformation ratio of the low-voltage side 1 to the high-voltage side of the autotransformer is K1; the transformation ratio of the low-voltage side 2 to the high-voltage side of the autotransformer is K2; the transformation ratio of the low-voltage side 3 to the high-voltage side of the autotransformer is K 3。 3. The soft starting device capable of stepping down and regulating voltage according to claim 1, wherein: The adjustable reactance device adjusts the effective number of turns of the inductor coil by changing the effective position of the high-permeability iron core magnetic medium in the air-core inductor coil, thereby changing the magnetic field strength of the inductor coil to achieve the purpose of changing the impedance value of the inductor coil and gradually increasing the voltage at the motor terminal; the voltage reduction and regulation ratio of the adjustable reactance device is K4.

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