A high-power motor frequency conversion switching system and a control method thereof

Abstract

The invention mainly discloses a high-power motor frequency conversion switching system and a control method thereof. The system comprises an acquisition circuit unit, a judgment circuit unit, a control circuit unit, an execution circuit unit and an electric control loop unit. The acquisition circuit unit is connected with a judging circuit unit, and the judging circuit unit is connected with a control circuit unit and an execution circuit unit. The executing circuit unit is connected with the electric control loop unit; The electric control loop unit is connected with a motor; The collectingcircuit unit comprises a collecting signal module, a rectifying module, a power signal processing module and a comparison signal processing module. The judging circuit unit comprises an amplifying circuit module and a phase detecting circuit module. The patent of the invention effectively improves the success rate of switching, can quickly and accurately capture the phase synchronization, and thesystem is simple and efficient, the stability and the success rate of switching will increase after the system is simple, the system effectively reduces the cost, and can be mass produced and processed.

Description

technical field [0001] The invention relates to the field of frequency converters, in particular to a high-power electrical engineering frequency conversion switching system and a control method thereof. Background technique [0002] In order to save costs, generally only one inverter and two motors are used at the same time in the production site, which requires conversion from power frequency to frequency conversion; low-power motors have low requirements on the phase of the power grid due to their small loads, and power frequency conversion can Successful switching; but for high-power motors, because they run off the grid first, the motor load is large, and the motor will have excitation shock. With the increase of the motor running time, the motor speed drops too much, and the slip shock begins to be significant. The initial phase of the output voltage of the inverter is random and uncertain. Even if the frequency of the output voltage of the inverter is equal to the fre...

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Problems solved by technology

[0002] In order to save costs, generally only one inverter and two motors are used at the same time in the production site, which requires conversion from power frequency to frequency conversion; low-power motors do not have high requirements on the phase of the grid due to their small loads, and power frequency conversion can Successful switching; but for high-power motors, because they are disconnected from the power grid at work, the motor load is large, and the motor will have excitation shock. With the increase of the motor running time, the motor speed drops too much, and the slip shock begins to be significant. The initial phase of the output voltage of the frequency converter is random and uncertain. Even if the frequency of the output voltage of the frequency converter is equal to the frequency of the power frequency voltage, the initial phase of the output three-phase power supply and the power frequency power supply are not consistent. The inconsistency of the phases has caused various problems in the switching process, making the problem of converting the frequency conversion of high-power motors to industrial frequency more complicated. The initial phase of the power frequency power supply is inconsistent, which leads to the randomness of the instantaneous current generated when the motor is switched, and sometimes it is much greater than the rated current of the motor. In the on-site production, the current or voltage of the motor is overloaded, causing the air switch to trip. Burn the fuse, and even damage the motor equipment in severe cases

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