Motor starting circuit

Abstract

The utility model discloses a motor starting circuit, which relates to the technical field of motor control and structurally comprises a main power supply input end, a starting contactor group and a controller. The main power supply input end is connected with a main power supply and provides required electric energy for the motor. The starting contactor group is composed of a first contactor and a second contactor, and the controller is responsible for outputting a control signal to the starting contactor group. T, S and R ports at the bottom end of the first contactor are short-circuited to form a star-shaped connection point, and T, S and R ports at the upper end of the first contactor are connected with corresponding ports at the upper end of the second contactor through metal copper plates to form a switchable path; and R, S and T ports at the lower end of the second contactor are connected with U, V and W phases of a main incoming line of the motor. In the starting process of the motor, the controller firstly controls the first contactor to be closed, so that the motor is started in a star connection mode, starting current is reduced, and impact on a power grid is reduced.

Description

Technical Field

[0001] This utility model relates to the field of motor control technology, specifically a motor starting circuit. Background Technology

[0002] The existing starting method for low-temperature waste heat generator sets is soft starter starting. Its main function is to be a novel motor control device that integrates motor soft starting, soft stopping, and multiple protection functions. The core component of the soft starter is a three-phase anti-parallel thyristor connected in series between the power supply and the controlled motor, along with its electronic control circuit. However, the soft starter circuit currently used in waste heat generator sets is relatively complex, prone to failure, and affects the normal operation of the generator. Utility Model Content

[0003] The purpose of this invention is to provide a motor starting circuit to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution:

[0005] A motor starting circuit, comprising:

[0006] The main power input terminal is configured to connect to the main power supply, providing the electrical energy required for motor startup and operation.

[0007] A starting contactor group, the starting contactor group including a first contactor and a second contactor;

[0008] Controller, the controller being configured to output control signals to the start contactor group;

[0009] Specifically, the bottom T, S, and R ports of the first contactor are short-circuited by a metal copper busbar connector to form a star connection point; the upper T, S, and R ports of the first contactor are connected to the upper T, S, and R ports of the second contactor through a metal copper plate to form a switchable connection path; the lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main input line.

[0010] Preferably, the first contactor is a star contactor and the second contactor is a delta contactor.

[0011] Preferably, it also includes a motor protection unit, which includes three first current transformers, each connected to the three-phase input current circuit of the motor.

[0012] Preferably, it also includes an electrical monitoring unit, which includes two second current transformers and a voltage transformer, respectively in contact with the current and voltage circuits of the motor.

[0013] Preferably, it also includes an alarm module, which outputs a fault alarm signal to the alarm module when the motor protection unit sends a trip signal or the electrical detection unit sends abnormal electrical parameter data.

[0014] Preferably, the alarm module includes an audible and visual alarm component and / or a remote alarm module.

[0015] Preferably, the controller includes a programmable logic controller or a microprocessor controller.

[0016] Compared with the prior art, the beneficial effects of this utility model are:

[0017] This utility model discloses a motor starting circuit, the structure of which includes a main power input terminal, a starting contactor group, and a controller. The main power input terminal is connected to the main power supply to provide the motor with the required electrical energy. The starting contactor group consists of a first contactor and a second contactor, and the controller is responsible for outputting control signals to the starting contactor group. The bottom T, S, and R ports of the first contactor are short-circuited to form a star connection point, and its upper T, S, and R ports are connected to the corresponding upper ports of the second contactor through a copper plate to form a switchable path; the lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main input line. During motor starting, the controller first controls the first contactor to close, so that the motor starts in a star connection, reducing the starting current and minimizing the impact on the power grid. When the motor speed reaches a certain value, the controller controls the first contactor to open, and at the same time the second contactor closes, the motor switches to a delta connection, improving operating efficiency and power. By switching the working state of the contactors, the conversion of the motor from a star connection to a delta connection is realized. Attached Figure Description

[0018] Figure 1 This is a circuit control circuit diagram.

[0019] Figure 2 This is a circuit control circuit diagram in one embodiment.

[0020] Figure 3 This is a schematic diagram of the circuit connection for starting the contactor group in one embodiment.

[0021] Figure 4 This is a schematic diagram of the circuit connection of the first contactor in one embodiment.

[0022] Figure 5 This is a schematic diagram of the second contactor circuit connection in one embodiment.

[0023] Figures 6 to 8 This is a control circuit diagram of a motor protection unit in one embodiment.

[0024] Figure 9 This is a circuit diagram of an electrical monitoring unit in one embodiment. Detailed Implementation

[0025] The technical solution of this patent will be further described in detail below with reference to specific embodiments.

[0026] The embodiments of this patent are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0027] In the description of this patent, it should be understood that the terms "middle", "bottom", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "both sides", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent.

[0028] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "assembly" should be interpreted broadly. For example, they can refer to a fixed connection or installation, a detachable connection or installation, or an integral connection or installation. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0029] Please refer to Figure 1 Currently, the soft starter principle of low-temperature waste heat generator sets utilizes three anti-parallel thyristors connected in series between the power supply and the controlled motor to control the generator's start-up, thereby achieving reduced-voltage starting of the generator, reducing starting current, and reducing the impact on the power grid. However, the soft starter circuit is complex, and the system reliability is low and prone to failure.

[0030] Please refer to Figure 2 One embodiment of this application discloses a motor starting circuit, the structure of which includes:

[0031] The main power input terminal is configured to connect to the main power supply, providing the electrical energy required for motor startup and operation.

[0032] A starting contactor group, the starting contactor group including a first contactor and a second contactor;

[0033] Controller, the controller being configured to output control signals to the start contactor group;

[0034] Specifically, the bottom T, S, and R ports of the first contactor are short-circuited by a metal copper busbar connector to form a star connection point; the upper T, S, and R ports of the first contactor are connected to the upper T, S, and R ports of the second contactor through a metal copper plate to form a switchable connection path; the lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main input line.

[0035] Specifically, during motor startup, the controller first closes the first contactor, starting the motor in a star connection. Because the voltage of each phase winding is lower in a star connection, the starting current is also relatively small, minimizing the impact on the power grid. As the motor speed gradually increases and reaches a certain value, the controller opens the first contactor and simultaneously closes the second contactor. At this point, the motor switches from a star connection to a delta connection, increasing the voltage of each phase winding and resulting in higher operating efficiency and power. Please refer to [reference needed]. Figure 3 The starting contactor group consists of a first contactor and a second contactor. Under the control of the controller, these two contactors are responsible for switching the circuit during motor startup. The bottom T, S, and R ports of the first contactor are short-circuited via a copper busbar connector, forming a star connection. This connection allows the motor to operate in a star configuration during the initial startup phase, reducing starting current and minimizing impact on the power grid. The upper T, S, and R ports of the first contactor are connected to the upper T, S, and R ports of the second contactor via a copper plate, forming a switchable connection path. This means that during motor startup, the motor can be switched from a star connection to a delta connection by changing the contactor's operating state. The lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main power supply. Thus, when the second contactor is closed, the motor will operate in a delta configuration, achieving higher operating efficiency and power.

[0036] Please refer to Figure 4 and Figure 5 Furthermore, the first contactor is a star contactor, and the second contactor is a delta contactor. For specific models, for example, it can be a star contactor AX260 and a delta contactor AX370. When the generator starts, the star contactor AX260 is energized, and the generator coil is connected in a star configuration. After the generator starts, the star contactor AX260 is de-energized, and the delta contactor AX370 is energized, and the generator operates normally to generate electricity. The copper plates on the top of AX370 are connected to the generator's T6 (G6), T4 (G5), and T5 (G4) ports respectively. The three terminals T, S, and R on the left side of AX370 are connected to the T3 (G2), T2 (G3), and T1 (G1) ports respectively.

[0037] Furthermore, the motor starting circuit also includes a motor protection unit, which includes three first current transformers connected to the three-phase input current circuit of the motor. When the motor protection unit sends a trip signal or the electrical detection unit sends abnormal electrical parameter data, the controller outputs a fault alarm signal to the alarm module. The alarm module includes an audible and visual alarm component and / or a remote alarm module. The controller includes a programmable logic controller or a microprocessor controller.

[0038] In the above embodiments, the controller's control signal changes the on / off state of the star contactor and delta contactor to achieve switching between star and delta starting of the star-delta starting device. Specifically, current transformers and voltage transformers are connected to the soft starter. When the equipment starts, the soft starter monitors the generator's starting current and starting voltage data in real time. When the generator's electrical parameters are abnormal, the normally open contact of the soft starter's generator alarm signal closes, sending a generator alarm signal to the controller. Figure 6 , Figure 7 As shown, after the controller receives the generator alarm signal, the generator main circuit breaker trips:

[0039] In this embodiment, due to the lack of generator alarm signals after using a star-delta contactor to replace the soft starter, this solution provides a motor protector to replace the generator alarm signals of the soft starter. The motor protector is an electrical component that can protect against various situations that may occur during motor operation, such as starting timeout, overload, phase loss, imbalance, underload, grounding / leakage, blockage, short circuit, and external faults. Its main wiring is as follows: Figure 8 As shown, 3CT1-3CT3 are three current transformers, whose important function is to measure the three-phase input current signal of the generator and provide protection for generator operation. The motor protector's ports 95 and 96 are normally closed dry contact inputs, mainly used for generator protection signal tripping. When the motor protector's ports 95 and 96 are connected to the controller, when the generator starts and triggers the alarm, the normally closed contacts 95 and 96 open, the controller receives the alarm signal, and thus stops the generator from starting. By using the function of the motor protector, the protection function of the soft starter is replaced.

[0040] Furthermore, it also includes an electrical monitoring unit, which comprises two second current transformers and a voltage transformer, respectively contacting the current and voltage circuits of the motor. In one embodiment, the electrical monitoring unit is a multi-function meter, such as... Figure 9 As shown, the three-phase voltages of generator A, B, and C are connected to UA, UB, and UC respectively for measuring the voltage of each phase of the generator's main incoming line. Current transformers are connected to I... A * I A I c * Ic Used to measure the main incoming current of the generator, the controller reads the meter data through RS485 communication to obtain voltage and current parameters.

[0041] In summary, this utility model discloses a motor starting circuit, the structure of which includes a main power input terminal, a starting contactor group, and a controller. The main power input terminal is connected to the main power supply to provide the motor with the required electrical energy. The starting contactor group consists of a first contactor and a second contactor, and the controller is responsible for outputting control signals to the starting contactor group. The bottom T, S, and R ports of the first contactor are short-circuited to form a star connection point, and its upper T, S, and R ports are connected to the corresponding upper ports of the second contactor through a metal copper plate to form a switchable path; the lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main input line. During motor starting, the controller first controls the first contactor to close, enabling the motor to start in a star connection, reducing the starting current and minimizing the impact on the power grid. When the motor speed reaches a certain value, the controller controls the first contactor to open, while the second contactor closes, switching the motor to a delta connection, improving operating efficiency and power. By switching the working state of the contactors, the motor can be switched from a star connection to a delta connection.

[0042] The above are merely preferred embodiments of this utility model. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of this utility model, and these should also be considered within the scope of protection of this utility model. These will not affect the implementation effect of this utility model or the practicality of the patent.

Claims

1. A motor starting circuit, characterized in that, include: The main power input terminal is configured to connect to the main power supply, providing the electrical energy required for motor startup and operation. A starting contactor group, the starting contactor group including a first contactor and a second contactor; Controller, the controller being configured to output control signals to the start contactor group; Specifically, the bottom T, S, and R ports of the first contactor are short-circuited by a copper busbar connector to form a star connection point; the upper T, S, and R ports of the first contactor are connected to the upper T, S, and R ports of the second contactor through a copper plate to form a switchable connection path; the lower R, S, and T ports of the second contactor are connected to the U, V, and W phases of the motor's main input line.

2. The motor starting circuit according to claim 1, characterized in that, The first contactor is a star contactor, and the second contactor is a delta contactor.

3. The motor starting circuit according to claim 1, characterized in that, It also includes a motor protection unit, which includes three first current transformers, each connected to the three-phase input current circuit of the motor.

4. A motor starting circuit according to claim 3, characterized in that, It also includes an electrical monitoring unit, which includes two second current transformers and a voltage transformer, respectively in contact with the current and voltage circuits of the motor.

5. A motor starting circuit according to claim 4, characterized in that, It also includes an alarm module. When the motor protection unit sends a trip signal or the electrical detection unit sends abnormal electrical parameter data, the controller outputs a fault alarm signal to the alarm module.

6. A motor starting circuit according to claim 5, characterized in that, The alarm module includes an audible and visual alarm component and / or a remote alarm module.

7. A motor starting circuit according to claim 5, characterized in that, The controller includes a programmable logic controller or a microprocessor controller.

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