Apparatus and method for controlling variable-frequency drive to switch to power frequency bypass

Abstract

An apparatus and a method for controlling a variable-frequency drive to switch to a power frequency bypass, relating to the field of variable-frequency drives. The apparatus comprises a controller. The controller is used for: when it is detected that a variable-frequency drive outputs a fault signal and the variable-frequency drive is not successfully reset, determining to switch the variable-frequency drive from a variable-frequency circuit to a power frequency circuit, a power frequency switching instruction output end outputting a switching instruction of switching to the power frequency circuit; and, when it is detected that the variable-frequency drive outputs a fault signal and the variable-frequency drive has been successfully reset, acquiring, by means of an input end of voltage to be measured, the voltage of a power supply to be measured, and determining whether the voltage of the power supply to be measured has a voltage sag change within a first preset time period before it is detected that the variable-frequency drive outputs the fault signal, and if yes, determining to switch the variable-frequency drive from the variable-frequency circuit to the power frequency circuit, the power frequency switching instruction output end outputting a switching instruction of switching to the power frequency circuit. The present invention achieves automatic switching to the power frequency circuit in case of a variable-frequency drive fault, thereby reducing the impact on continuous production.

Description

Device and method for controlling switching between frequency converter and power frequency bypass

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on November 29, 2023, with application number 202311614494.8 and invention name “A device and method for controlling switching between a frequency converter and an industrial frequency bypass”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of frequency converters, and in particular to a device and method for controlling switching between a frequency converter and an industrial frequency bypass. Background Art

[0003] Frequency converters are widely used in industrial control systems. As frequency converters are power electronic products with high protection accuracy, they may stop running due to various protection value limits during use. Some faults may be faults in the frequency converter itself, some faults may be load-side faults that cause the frequency converter to stop for protection, and some faults may be due to instantaneous faults on the power supply side that cause the frequency converter to stop for protection. Regardless of the type of fault, the frequency converter will stop. Some important working conditions require continuous operation and cannot be shut down. Generally, they are equipped with industrial frequency circuits. When the frequency converter itself stops due to a fault, it is manually switched to industrial frequency operation. However, this will still affect production and force interruption, resulting in certain production losses.

[0004] The current situation is that both the variable frequency and industrial frequency circuits are switched manually. This is because when a frequency converter fails, the fault needs to be manually confirmed. Only after confirming that it is not caused by the load side will it be manually switched to industrial frequency startup again. Of course, this also includes failures of the frequency converter itself. However, this will cause a delay in the restart time, which will affect continuous production.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to provide a device and method for controlling the switching between a frequency converter and a power frequency bypass, thereby reducing the impact on continuous production by realizing automatic switching to a power frequency circuit when a frequency converter fails.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] A device for controlling switching between a frequency converter and a power frequency bypass includes a controller, the controller including a voltage input terminal to be detected and a power frequency switching instruction output terminal, the voltage input terminal to be detected being connected to a power supply to be detected, and the power frequency switching instruction output terminal being used to output a switching instruction for switching to a power frequency circuit;

[0009] The controller is configured to determine to switch the frequency converter from the variable frequency circuit to the power frequency circuit when detecting that the frequency converter outputs a fault signal and the frequency converter fails to reset successfully, and output a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal;

[0010] The controller is further configured to, when detecting that the frequency converter outputs a fault signal and the frequency converter is successfully reset, obtain the voltage of the power supply to be detected through the voltage input terminal to be detected, determine whether the voltage of the power supply to be detected has a temporary sag change within a first preset time period before detecting that the frequency converter outputs a fault signal and whether the voltage sag reaches a preset value; if so, determine to switch the frequency converter from the frequency conversion circuit to the power frequency circuit, and output a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal.

[0011] Optionally, the controller further includes a frequency converter status signal input terminal, a frequency converter fault signal input terminal and a reset pulse signal output terminal, wherein the frequency converter status signal input terminal is used to input the frequency converter status signal, the frequency converter fault signal input terminal is used to receive the frequency converter fault signal, and the reset pulse signal output terminal is used to send a reset pulse signal to the frequency converter;

[0012] The controller is also used for:

[0013] Real-time detection of whether the frequency converter outputs a fault signal through the frequency converter fault signal input terminal;

[0014] When it is detected that the frequency converter outputs a fault signal, a reset pulse is sent to the frequency converter via the reset pulse signal output terminal within a preset reset time period;

[0015] Whether the inverter is reset is determined according to the inverter status signal input terminal.

[0016] Optionally, the controller is further configured to issue an instruction to restart the power frequency circuit after a second preset time delay after the power frequency switching instruction output terminal outputs a switching instruction to switch to the power frequency circuit.

[0017] Optionally, the controller further includes a voltage recording module for the power supply to be detected, and the voltage recording module for the power supply to be detected is used to record the voltage of the power supply to be detected at each moment.

[0018] The present invention also discloses a method for controlling the switching between a frequency converter and a power frequency bypass. The method for controlling the switching between a frequency converter and a power frequency bypass is applied to the device for controlling the switching between a frequency converter and a power frequency bypass. The method for controlling the switching between a frequency converter and a power frequency bypass comprises:

[0019] When the controller detects that the frequency converter outputs a fault signal and the frequency converter fails to reset successfully, it determines to switch the frequency converter from the variable frequency circuit to the power frequency circuit, and outputs a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal;

[0020] When the controller detects that the inverter outputs a fault signal and the inverter is successfully reset, the controller obtains the voltage of the power supply to be detected through the voltage input terminal to be detected, and determines whether the voltage of the power supply to be detected has a temporary sag change within a first preset time period before the inverter output fault signal is detected and the voltage sag reaches a preset value. If so, it is determined that the inverter is switched from the frequency conversion circuit to the power frequency circuit, and the power frequency switching instruction output terminal outputs a switching instruction to switch to the power frequency circuit.

[0021] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0022] The present invention uses a controller to detect the reset status of the frequency converter and the voltage change of the power supply to be detected to determine whether to switch the frequency converter from the frequency conversion circuit to the power frequency circuit, thereby realizing automatic switching to the power frequency circuit when a frequency conversion failure occurs, reducing the impact of forced production interruption on continuous production.

[0023] Figures in the specification

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] FIG1 is a schematic structural diagram of a device for controlling switching between a frequency converter and a power frequency bypass according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The purpose of the present invention is to provide a device and method for controlling the switching between a frequency converter and a power frequency bypass, thereby reducing the impact on continuous production by realizing automatic switching to a power frequency circuit when a frequency converter fails.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] As shown in Figure 1, the present invention provides a device for controlling the switching between a frequency converter and an industrial frequency bypass, comprising: a controller, wherein the controller includes a voltage input terminal to be detected, a frequency converter status signal input terminal, a frequency converter fault signal input terminal, an industrial frequency switching instruction output terminal and a reset pulse signal output terminal; the voltage input terminal to be detected is connected to the power supply to be detected, the frequency converter status signal input terminal is used to input the status signal of the frequency converter, the frequency converter fault signal input terminal is used to receive the fault signal of the frequency converter, the reset pulse signal output terminal is used to send a reset pulse signal to the frequency converter, and the industrial frequency switching instruction output terminal is used to output a switching instruction to switch to the industrial frequency circuit.

[0031] The frequency converter is connected to the power supply to be detected and the load respectively. The voltage of the power supply to be detected is converted by the frequency converter to supply power to the load.

[0032] The controller is used to:

[0033] When it is detected that the inverter outputs a fault signal and the inverter fails to reset successfully, it is determined that the inverter is switched from the variable frequency circuit to the power frequency circuit, and the power frequency switching instruction output terminal outputs a switching instruction to switch to the power frequency circuit.

[0034] The controller is also used to obtain the voltage of the power supply to be detected through the voltage input terminal to be detected after detecting that the inverter outputs a fault signal and the inverter is successfully reset, and determine whether the voltage of the power supply to be detected has a temporary sag change within a first preset time period before detecting that the inverter outputs a fault signal and whether the voltage sag reaches a preset value; if so, determine to switch the inverter from the frequency conversion circuit to the power frequency circuit, and output a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal, and issue an instruction to restart the power frequency circuit after a delay of a second preset time; if not, do not output the power frequency switching instruction and the instruction to restart the power frequency circuit.

[0035] The controller is also used to:

[0036] Real-time detection of whether the frequency converter outputs a fault signal through the frequency converter fault signal input terminal;

[0037] When it is detected that the frequency converter outputs a fault signal, a reset pulse is sent to the frequency converter via the reset pulse signal output terminal within a preset reset time period;

[0038] Whether the inverter is reset is determined according to the inverter status signal input terminal.

[0039] If the inverter is successfully reset, it is determined whether the voltage of the power supply to be detected has a temporary sag change within a first preset time period before the inverter outputs a fault signal, and whether the temporary sag change reaches a preset threshold. If so, it is determined to switch the inverter from the frequency conversion circuit to the power frequency circuit.

[0040] The inverter reset is successful when the inverter no longer outputs a fault signal within the preset reset time period after receiving the reset pulse signal.

[0041] The inverter fails to reset successfully, which means that the inverter still outputs a fault signal within the preset reset time period after receiving the reset pulse signal.

[0042] Under normal conditions, the inverter's power frequency circuit is disconnected.

[0043] If the inverter fault signal is detected to have returned, but the power supply voltage under test has not shown a temporary drop trend within the first preset time period after the fault signal has changed, the controller will not issue a switch command or a restart command. A switch command is an instruction for the inverter to switch to the power frequency circuit, and a restart command is an instruction to start the power frequency circuit.

[0044] The controller further comprises a voltage recording module for a power supply to be detected, and the voltage recording module for the power supply to be detected is used to record the voltage of the power supply to be detected at each moment.

[0045] As shown in Figure 1, the controller includes three-phase input terminals L1, L2, and L3. Terminals 1 and 2 are single-phase power input terminals to be detected. Depending on actual needs, the controller can detect single-phase voltage or three-phase voltage.

[0046] When the power supply voltage to be detected is a single-phase voltage, the voltage input terminal to be detected includes a wiring terminal 1 and a wiring terminal 2 .

[0047] When the power supply voltage to be detected is a three-phase voltage, the voltage input end to be detected includes three-phase input terminals L1, L2, and L3, namely, terminal 1, terminal B, and terminal C.

[0048] Terminals 3 and 4 are the inverter status signal input terminals, which detect the operating status of the inverter.

[0049] Terminals 5 and 6 are the start-up instructions (restart instructions) for the inverter to switch to the industrial frequency.

[0050] Terminals 7 and 8 are the power frequency switching command output terminals, and are the switching circuits for converting variable frequency and power frequency.

[0051] Terminals 9 and 10 are the inverter fault signal input terminals.

[0052] Terminals 11 and 12 are pulse signal output terminals, used to output reset pulse signals to the inverter.

[0053] Terminals 13 and 14 are used for status output, that is, for maintaining the output operation signal when the inverter switches to the power frequency.

[0054] Only one of the variable frequency circuit and the power frequency circuit can be connected. When the variable frequency circuit is connected, the power frequency circuit is disconnected. When the power frequency circuit is connected, the variable frequency circuit is connected. The two circuits are interlocked. Therefore, after the controller issues a switch command to switch to the power frequency circuit (specifically, switching the variable frequency circuit to the power frequency circuit via terminals 7 and 8), it will delay for a second preset time before issuing a command to restart the power frequency circuit, specifically via terminals 5 and 6.

[0055] Example 2

[0056] The present invention also discloses a method for controlling the switching between a frequency converter and a power frequency bypass. The method for controlling the switching between a frequency converter and a power frequency bypass is applied to the device for controlling the switching between a frequency converter and a power frequency bypass described in Example 1.

[0057] The method for controlling the switching between the frequency converter and the power frequency bypass includes:

[0058] When the controller detects that the inverter outputs a fault signal and the inverter fails to reset successfully, it determines to switch the inverter from the variable frequency circuit to the power frequency circuit, and outputs a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal.

[0059] When the controller detects that the frequency converter outputs a fault signal and the frequency converter is successfully reset, the controller obtains the voltage of the power supply to be detected through the voltage input terminal to be detected, and determines whether the voltage of the power supply to be detected has a temporary sag change within a first preset time period before the frequency converter outputs a fault signal and whether the voltage sag reaches a preset value. If so, the controller determines to switch the frequency converter from the frequency conversion circuit to the power frequency circuit, and outputs a switching instruction to switch to the power frequency circuit from the power frequency switching instruction output terminal.

[0060] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0061] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the device and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A device for controlling the switching between a frequency converter and an industrial frequency bypass, characterized in that: The controller includes a voltage input terminal to be detected and a power frequency switching instruction output terminal, wherein the voltage input terminal to be detected is connected to the power supply to be detected, and the power frequency switching instruction output terminal is used to output a switching instruction to switch to the power frequency circuit; The controller is used for determining to switch the frequency converter from the variable frequency circuit to the power frequency circuit when it is detected that the frequency converter outputs a fault signal and the frequency converter fails to reset successfully, and outputting a switching instruction for switching to the power frequency circuit from the power frequency switching instruction output terminal; The controller is also used to obtain the voltage of the power supply to be detected through the voltage input terminal to be detected after detecting that the frequency converter outputs a fault signal and the frequency converter is successfully reset, and to determine whether the voltage of the power supply to be detected has a temporary drop change within a first preset time period before detecting that the frequency converter outputs a fault signal and whether the voltage drop reaches a preset value. If so, determine to switch the frequency converter from the variable frequency circuit to the industrial frequency circuit, and output a switching instruction to switch to the industrial frequency circuit from the industrial frequency switching instruction output terminal.

2. The device for controlling the switching between the frequency converter and the power frequency bypass according to claim 1, characterized in that: The controller further comprises a frequency converter state signal input terminal, a frequency converter fault signal input terminal and a reset pulse signal output terminal. The frequency converter state signal input terminal is used to input the state signal of the frequency converter, the frequency converter fault signal input terminal is used to receive the fault signal of the frequency converter, and the reset pulse signal output terminal is used to send a reset pulse signal to the frequency converter; The controller is also used for: Real-time detection of whether the frequency converter outputs a fault signal through the frequency converter fault signal input terminal; When it is detected that the frequency converter outputs a fault signal, a reset pulse is sent to the frequency converter through the reset pulse signal output terminal within a preset reset time period; Whether the inverter is reset is determined according to the inverter status signal input terminal.

3. The device for controlling the switching between the frequency converter and the power frequency bypass according to claim 1, characterized in that: The controller is also used for issuing an instruction to restart the power frequency circuit after a second preset time delay after the power frequency switching instruction output terminal outputs a switching instruction to switch to the power frequency circuit.

4. The device for controlling the switching between the frequency converter and the power frequency bypass according to claim 1, characterized in that: The controller further comprises a power supply voltage recording module to be detected, and the power supply voltage recording module to be detected is used to record the voltage of the power supply to be detected at each moment.

5. A method for controlling the switching between a frequency converter and an industrial frequency bypass, characterized in that: The method for controlling the switching between the frequency converter and the power frequency bypass is applied to the device for controlling the switching between the frequency converter and the power frequency bypass according to claims 1 to 4, and the method for controlling the switching between the frequency converter and the power frequency bypass includes: When the controller detects that the inverter outputs a fault signal and the inverter fails to reset successfully, it determines to switch the inverter from the variable frequency circuit to the power frequency circuit, and the power frequency switching instruction output terminal outputs a switching instruction to switch to the power frequency circuit; When the controller detects that the frequency converter outputs a fault signal and the frequency converter is successfully reset, the controller obtains the voltage of the power supply to be detected through the voltage input terminal to be detected, and determines whether the voltage of the power supply to be detected has a temporary drop change within a first preset time period before the frequency converter output fault signal is detected and the voltage drop reaches a preset value. If so, it is determined to switch the frequency converter from the variable frequency circuit to the industrial frequency circuit, and the industrial frequency switching instruction output terminal outputs a switching instruction to switch to the industrial frequency circuit.

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