AC (alternating current) supply anomaly preventive variable frequency driving unit

Abstract

The invention discloses an AC (alternating current) supply anomaly preventive variable frequency driving unit mainly comprising a variable frequency functional body module, an AC control power output module, a three-phase alternating boost module, an AC power uncontrolled rectifier module, an external or self-contained DC (direct current) power connection module and a self-contained DC power supply. The variable frequency functional body module comprises a complete converter circuit, a structure and a sub-controller and is capable of automatically keeping a sensitive load to run stably without fluctuation in case that an AC main supply is normal or slightly drops. The AC control power output module services another control part for the sensitive load. The AC control power output module, the three-phase alternating boost module, the AC power uncontrolled rectifier module, the external or self-contained DC power connection module and the self-contained DC power supply can be flexibly selected according to actual conditions of an application site to assist the variable frequency functional body module in allowing the sensitive load to run stably without fluctuation in case that the AC main supply severely drops or transiently drops out.

Description

technical field [0001] The invention belongs to the field of low-voltage variable-frequency drive, and in particular relates to a variable-frequency drive device capable of resisting abnormal AC power supply. It is suitable for power plants, petrochemical, chemical fiber, chip manufacturing and other applications where sensitive loads driven by low-voltage variable frequency motors are used, and fluctuations in sensitive loads or unplanned shutdowns will cause serious losses. Background technique [0002] The low-voltage frequency conversion motor drive system is widely used in various fields of industrial production, and the core component of the system is the frequency converter device. The frequency converter has the characteristics of precise speed regulation, simple use, high degree of automation, and energy saving. The input side of the inverter is connected to the AC power supply, and the AC power is rectified and transformed into a DC power supply inside the inverte...

AI Technical Summary

Problems solved by technology

[0003] In power plants, petrochemical, chemical fiber, chip manufacturing, etc., where low-voltage variable frequency motors are used to drive sensitive loads, accidents of sensitive load fluctuations or unplanned shutdowns often occur due to abnormal AC power supply

In these accidents, lightning strikes in power transmission and transformation or power supply and distribution systems, electrical equipment short-circuit, grounding and other faults, as well as the start-up of heavy-load equipment inside the industrial production site, etc., resulting in abnormal AC power supply at the industrial production site, and the duration is relatively short. Short, it should not cause accidental shutdown, but because the conventional inverter in the frequency conversion drive system of some sensitive loads does not have the ability to resist abnormal AC power supply, the abnormal AC power supply triggers the inverter's own protection and blocks the output, directly leading to shutdown accidents; Power switching and other re-power-on methods combined with the automatic restart of the inverter will also cause fluctuations in the sensitive load of the subsequent stage, resulting in the production process not meeting the requirements or the control system overshooting and forced to stop

This kind of unplanned shutdown destroys the continuity and economy of industrial production, causes damage to industrial production equipment, and may cause a lot of waste of raw materials, so it should be avoided as much as possible

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