Frequency converter soft shutdown control circuit

Abstract

A frequency converter soft shutdown control circuit comprises an input end, the input end is connected with a change-over switch SA, a manual gear end of the change-over switch SA is connected with a switch SS and a switch SF, the switch SF is further connected with the input end through a coil of an intermediate relay KA4, the switch SF is further connected with the input end through a coil of a time-delay relay KT, and the time-delay relay KT is connected with the input end. One end of a conducting end of the intermediate relay KA4 is connected with the input end, the other end of the intermediate relay KA4 is connected with the contactor KM1, one end of a conducting end of the time-delay relay KT is connected with the input end, and the other end of the time-delay relay KT is connected with the contactor KM1.

Description

Technical Field

[0001] The utility model relates to the field of frequency converter control, in particular to a frequency converter soft stop control circuit. Background Art

[0002] At present, in low-voltage motor control systems, frequency converters are widely used to control the start and stop of motors. This can reduce the impact of motor starting current on the power grid. At the same time, frequency converters can realize motor speed regulation.

[0003] When the motor needs to stop, the contactor at the front end of the inverter is disconnected immediately after the stop button is pressed, and the inverter is also powered off immediately, causing the motor to be in an emergency stop state. The danger is that when the motor stops suddenly, it will cause the motor to stop running suddenly, which will cause mechanical rebound and damage some parts of the machine. Therefore, try to avoid emergency stops of the motor. Utility Model Content

[0004] In order to solve the above problems, the present technical solution provides a frequency converter soft stop control circuit.

[0005] To achieve the above purpose, the technical solution is as follows:

[0006] A frequency converter soft stop control circuit comprises an input end, the input end is connected with a conversion switch SA, the manual gear end of the conversion switch SA is connected with a switch SS and a switch SF, the switch SF is also connected to the input end through the coil of an intermediate relay KA4, the switch SF is also connected to the input end through the coil of a delay relay KT, one end of the conduction end of the intermediate relay KA4 is connected to the input end, and the other end is connected to a contactor KM1, one end of the conduction end of the delay relay KT is connected to the input end, and the other end is connected to the contactor KM1.

[0007] In some embodiments, the automatic gear of the conversion switch SA is connected to the intermediate relay KA4 through the switch K1.

[0008] In some embodiments, the input end is also connected to an operation indicator light HG1.

[0009] In some embodiments, the input end is also connected to a stop indicator light HY1.

[0010] In some embodiments, the input terminal is also connected to a fault indicator light.

[0011] The beneficial effects of this application are:

[0012] This application adds a delay relay. When the motor needs to stop, the contactor at the front end of the inverter is controlled by the delay relay and can be disconnected after the inverter (frequency) speed drops to zero, thereby realizing a soft shutdown of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for describing the embodiments.

[0014] Figure 1 This is a schematic diagram of the structure of the embodiment of the utility model Figure 1 ;

[0015] Figure 2 This is a schematic diagram of the structure of the embodiment of the utility model Figure 2 ;

[0016] Figure 3 It is a schematic diagram of the three-phase electrical structure of an embodiment of the utility model. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects solved by the utility model more clearly understood, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0018] Please refer to Figure 1-3 As shown, a frequency converter soft stop control circuit includes an input end, the input end is connected to a conversion switch SA, the manual gear end of the conversion switch SA is connected to a switch SS and a switch SF, the switch SF is also connected to the input end through the coil of an intermediate relay KA4, the switch SF is also connected to the input end through the coil of a delay relay KT, one end of the conduction end of the intermediate relay KA4 is connected to the input end, and the other end is connected to a contactor KM1, one end of the conduction end of the delay relay KT is connected to the input end, and the other end is connected to the contactor KM1.

[0019] In this embodiment, the automatic gear of the conversion switch SA is connected to the intermediate relay KA4 through the switch K1.

[0020] In this embodiment, the input end is also connected to an operation indicator light HG1.

[0021] In this embodiment, the input end is also connected to a stop indicator light HY1.

[0022] In this embodiment, the input end is also connected to a fault indicator light.

[0023] refer to Figure 1-2When the transfer switch is turned to manual gear, the start button SF is pressed, the coil of the intermediate relay KA4 is energized, closed and self-locked, and at the same time, the coil of the power-off time relay KT is energized and closed, a normally open contact of the relay KA4 is closed, the time delay normally open contact of the time relay KT is closed, the coil of the contactor KM1 is energized and closed, the three-phase power supply of the main circuit ABC is connected, and at the same time, another normally open contact of the relay KA4 is closed to start the inverter. The inverter works to make the motor energized and start running, and the running indicator light is on;

[0024] When stopping: press the stop button SS, the coil of the intermediate relay KA4 loses power and disconnects, and the normally open contact of the relay KA4 disconnects to send a stop signal to the inverter. After receiving the stop signal, the inverter slowly reduces the frequency (speed) to zero to achieve a soft stop of the motor. When the stop button SS is pressed, the coil of the power-off time relay KT loses power and its contact is disconnected with a delay (the delay time can be adjusted to be consistent with the frequency drop time of the inverter). After the delay contact of the time relay KT is disconnected, the AC contactor coil loses power, the main contact of the contactor is disconnected, the main power supply is cut off, and the stop indicator light is on;

[0025] refer to Figure 3 In the low-voltage motor control system, the three-phase main power supply circuit is equipped with: circuit breaker QF, AC contactor KM1, and frequency converter VFD. The circuit breaker is used to protect the circuit, the AC contactor is used to connect and disconnect the frequency converter power supply, and the frequency converter is used to control the start and stop of the motor load and the motor speed regulation. In the secondary control circuit, fuses, transfer switches, buttons, intermediate relays, time relays, indicator lights, etc. are set to realize the start and stop control of the motor.

[0026] The above description is only a preferred embodiment of the present application and is not intended to limit the scope of implementation of the present application. Other principles and basic structures that are the same or similar to those of the present application are within the protection scope of the present application.

Claims

1. A frequency converter soft stop control circuit, characterized in that: It includes an input end, the input end is connected to a conversion switch SA, the manual gear end of the conversion switch SA is connected to a switch SS and a switch SF, the switch SF is also connected to the input end through the coil of an intermediate relay KA4, the switch SF is also connected to the input end through the coil of a delay relay KT, one end of the conduction end of the intermediate relay KA4 is connected to the input end, and the other end is connected to a contactor KM1, one end of the conduction end of the delay relay KT is connected to the input end, and the other end is connected to the contactor KM1.

2. The inverter soft stop control circuit according to claim 1, characterized in that: The automatic position of the conversion switch SA is connected to the intermediate relay KA4 via the switch K1.

3. The inverter soft stop control circuit according to claim 2, characterized in that: The input end is also connected to an operation indicator light HG1.

4. The inverter soft stop control circuit according to claim 3, characterized in that: The input end is also connected to a stop indicator light HY1.

5. The inverter soft stop control circuit according to claim 4, characterized in that: The input end is also connected to a fault indicator light.

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