Three-phase asynchronous motor soft starter and its control method

A three-phase asynchronous, soft starter technology, applied in motor generators/starters, single multi-phase induction motor starters, reactive power compensation, etc., can solve problems such as low power factor and limited resistance, and achieve starting fast effect

Active Publication Date: 2015-09-02
益阳市科技成果转化服务中心 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But only constant current soft start is not enough, because the motor load itself is an inductive load, and its resistance to external electromagnetic interference is limited, so the power factor will be very low during the starting process.

Method used

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  • Three-phase asynchronous motor soft starter and its control method
  • Three-phase asynchronous motor soft starter and its control method
  • Three-phase asynchronous motor soft starter and its control method

Examples

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Embodiment 1

[0026] see figure 1 , the present invention proposes a three-phase asynchronous motor soft starter, including three voltage sensors, three current sensors, three soft starters, three drive circuits and a controller. Among them, the voltage sensor is connected in parallel with each phase winding of the motor to measure the phase voltage of the motor; the current sensor is connected in series with each phase winding of the motor to measure the phase current of the motor; three voltage / current sensors detect the three-phase voltage / current, and real-time Convert them proportionally into weak electric signals and send them to the controller. The soft starter includes a set of thyristors connected in antiparallel and a contactor connected in parallel with the thyristors, and each phase winding of the motor is connected in series with a soft starter. There is a control unit inside the controller, such as figure 2 As shown, the control unit is electrically connected to the voltage...

Embodiment 2

[0035] This embodiment proposes a soft starter for a three-phase asynchronous motor, including three voltage sensors, three current sensors, three soft starters, three drive circuits and a controller. Among them, the voltage sensor is connected in parallel with each phase winding of the motor to measure the phase voltage of the motor. The current sensor is connected in series with each phase winding of the motor to measure the phase current of the motor; three voltage / current sensors detect the three-phase voltage / current, and convert them into weak current signals proportionally in real time and send them to the controller. The soft starter includes a set of thyristors connected in antiparallel and a contactor connected in parallel with the thyristors, and each phase winding of the motor is connected in series with a soft starter. The controller is electrically connected with the voltage sensor for receiving the voltage of each phase of the motor. The controller is electrica...

Embodiment 3

[0045] Based on the three-phase asynchronous motor soft starter proposed in Embodiment 1, this embodiment proposes a control method for the soft starter, such as Image 6 As shown, it specifically includes the following steps:

[0046] Signal acquisition step: the control unit collects the phase voltage and phase current of the motor in real time through the voltage sensor and current sensor; the current change calculation step: the control unit calculates the change value of the current sampling current and the previous sampling current, and the current change rate ( The derivative of the circuit change value); the first trigger signal acquisition step: the control unit queries the two-dimensional fuzzy database of the phase current according to the change value and rate of change of the phase current, and obtains the first trigger pulse variable used to trigger the thyristor; the power factor calculation step : The control unit calculates the power factor of each phase of th...

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PUM

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Abstract

The invention provides a soft starter of a three-phase asynchronous motor and a control method of the soft starter. The starter comprises a voltage transducer, a current transducer, a soft starter, a controller and a driving circuit, wherein the controller is internally provided with a control unit. The voltage transducer and the current transducer are respectively used for measuring phase voltage and phase current of the motor. The soft starter is connected to the winding of each phase of the motor. The control unit is electrically connected with the voltage transducer and is used for receiving the voltage of each phase of the motor; the control unit is electrically connected with the current transducer, and is used for receiving the current of each phase of the motor; the control unit calculates a power factor of each phase through the phase voltage and the phase current; the control unit is electrically connected with a thyristor in the soft starter through the driving circuit to send a triggering signal to the thyristor; and the control unit determines the frequency of the triggering signal through the power factor and the phase current. According to the invention, the current and the power factor can be used as control amounts at the same time; and the current amount in a control process is stabilized to be 2-3 times as much as that of a rated value and the power factor can be stabilized at a high level.

Description

technical field [0001] The invention relates to a soft starter, in particular to a soft starter for a three-phase asynchronous motor and a control method thereof. Background technique [0002] At present, motor soft starters in the domestic and foreign markets generally adopt a topology structure, that is, each phase of the main circuit part uses a set of reverse-parallel thyristors and a contactor, and the controlled parameters of the control circuit part are usually only electric current. Flow rate is a parameter. In the process of soft starting, constant current soft starting is generally used, because this kind of constant current control can make a soft starter a backup starter for other motors at the same time, which can greatly enhance reliability and reduce cost. But only constant current soft start is not enough, because the motor load itself is an inductive load, and its resistance to external electromagnetic interference is limited, so the power factor in the sta...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02P1/26H02J3/18
CPCY02E40/30
Inventor 李智超孙延飞郭继毅
Owner 益阳市科技成果转化服务中心
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