Redundant frequency converter back-switching control system for driving motor

Abstract

The utility model relates to a redundant frequency converter back-switching control system for a driving motor, which comprises two independent frequency converters, output switches and a motor, the two independent frequency converters are connected through a signal line, the output switches and the motor are arranged corresponding to the frequency converters respectively, and the two frequency converters are connected to the same motor after passing through the corresponding output switches. The output switches are respectively switched on and off according to the control signals of the corresponding frequency converters, and only one output switch is in a switched-on state at the same time, so that the other frequency converter is effectively prevented from being influenced when one frequency converter breaks down. When one frequency converter is actively shut down or shut down due to faults, the corresponding output switch is switched off, and meanwhile, the output switch of the other frequency converter is switched off and drives output in time to maintain continuous operation of the motor. According to the utility model, as long as one of the two frequency converters is in a good state, the normal operation of the motor can be ensured, the two frequency converters are ensured not to influence each other, and the reliability of the system is further improved.

Description

Technical Field

[0001] This utility model relates to a frequency converter drive control system, and in particular discloses a redundant frequency converter back-off control system for driving motors. Background Technology

[0002] In modern industrial production, frequency converter (VDC) drive motor systems are widely used in various equipment to achieve speed control and energy-saving operation of motors. However, a single VDC drive motor system has certain reliability risks. Once the VDC fails or actively shuts down, the motor will stop running, potentially leading to production interruptions or equipment damage. To improve system reliability, existing technologies employ redundant designs, but most suffer from problems such as complex switching, slow response speed, low reliability, or poor compatibility, failing to meet the high reliability and flexibility requirements of industry. Furthermore, existing redundancy solutions often use a master-slave hot standby mode, resulting in long-term idle operation of the backup VDC, leading to resource waste.

[0003] To conserve resources, some applications employ a redundancy approach with one main inverter serving as a backup. If any one inverter fails, the backup inverter can take over and continue driving the motor. After the main inverter is repaired, a switchback can be used to restore the backup inverter to hot standby mode. The switchback operation between inverters requires both inverters to be fault-free. During the switching process, both inverter output switches can be simultaneously closed to accelerate the switching speed, enabling rapid output from one inverter when the other stops, or parallel output from both inverters for load transfer. However, if the faulty inverter is not thoroughly repaired and a recurrence of the fault occurs during drive output, it often affects... The drive circuit of another inverter damaged the drive circuit of the previously functioning inverter. In nuclear power projects using a four-in-one redundancy configuration, if any main inverter fails, the system can quickly switch to the backup inverter. The switchback mechanism after repairing the main inverter involves first closing the corresponding output switch of the main inverter. This creates a connection between the outputs of both inverters, allowing for faster switching and a second switching logic if the first attempt fails. However, if the repaired inverter's output is still short-circuited, closing both inverter output switches simultaneously will cause the inverter driving the motor to also fail and shut down. Similarly, if a short circuit occurs in the drive circuit of one inverter during the switching process, both inverters will fail and shut down, ultimately leading to a system shutdown. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects in the existing technology and to solve the shortcomings in the reliability of the existing frequency converter drive motor system. It proposes a redundant frequency converter back-off control system for driving motors. Two independent frequency converters are connected in parallel through high-speed communication protocol cables or signal lines and then connected through separately set output switches to drive a motor. The output switches of the two frequency converters cannot be closed at the same time to ensure that the two frequency converters do not affect each other, thereby further improving the reliability of the system.

[0005] This utility model is implemented as follows: a redundant frequency converter back-off control system for driving motors, characterized in that: it includes two independent frequency converters connected by signal lines, an output switch corresponding to each frequency converter, and a motor. The two frequency converters are connected to the same motor through corresponding output switches. The output switches are opened and closed according to the control signals of the corresponding frequency converters, and only one output switch is closed at any given time.

[0006] The signal lines are high-speed communication protocol cables or associated signal lines, and the output switches of the two inverters are logically interlocked through the high-speed communication protocol cables or associated signal lines.

[0007] The two frequency converters described herein serve as backups for each other, and preferably use frequency converters with the same power rating.

[0008] When one of the two frequency converters fails, the corresponding output switch is in the open state, and the output switch of the other frequency converter is triggered to the closed state via the high-speed communication protocol cable or associated signal line.

[0009] Accordingly, when one of the two frequency converters is manually stopped, the switching and reverting control processes are the same: the output switch corresponding to the manually stopped frequency converter is in the open state, and the output switch corresponding to the other frequency converter is triggered to the closed state via the high-speed communication protocol cable or associated signal line. Simultaneously, when one frequency converter is manually stopped, if a fault is detected in the other frequency converter and its output switch is in the open state, the manually stopped frequency converter will trigger its own corresponding output switch to the closed state again via the high-speed communication protocol cable or associated signal line to continue driving the motor.

[0010] The motor mentioned is an AC motor.

[0011] The beneficial effects of this utility model are:

[0012] 1. High reliability: Through the redundant backup design of two frequency converters and the interlocking design of the output switch, the problem of motor shutdown caused by the failure or shutdown of a single frequency converter is effectively avoided, thus improving the reliability of the system.

[0013] 2. Fast switching: High-speed communication protocol cables or associated signal lines are used to realize fast data exchange and switching actions between frequency converters. The switching time is short, and the switching time depends only on the output switch action time, typically less than 200ms. Attached Figure Description

[0014] Figure 1 This is a simplified structural diagram of the present invention.

[0015] Among them: 1. First frequency converter VFD1; 2. Second frequency converter VFD2; 3. Interaction signal line; 4. Motor. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] According to the appendix Figure 1 This utility model is a redundant inverter switching control system for driving a motor, including two independent inverters (i.e., the first inverter VFD1 and the second inverter VFD2) connected by signal lines, two output switches (i.e., the first output switch K1 and the second output switch K2), and a motor M. The signal lines adopt high-speed communication protocol cables or associated signal lines. The first inverter VFD1 is connected to the motor M through the first output switch K1, and the second inverter VFD2 is connected to the motor M through the second output switch K2. The first output switch K1 and the second output switch K2 are respectively opened and closed according to the control signals of the corresponding inverters, and only one output switch is allowed to be closed at the same time, that is, only one inverter drives the motor 4 at the same time.

[0018] According to the appendix Figure 1 In this embodiment, two frequency converters with the same power are used. The two frequency converters can serve as backups for each other and are connected to the power grid through their respective input switches (i.e., the first input switch QF1 and the second input switch QF2). The motor is an AC motor.

[0019] Taking the first frequency converter VFD1 as the main frequency converter driving the motor M as an example, in the initial state, the first output switch K1 is closed, the second output switch K2 is open, and the second frequency converter VFD2 is in the ready state. In this embodiment, the first frequency converter VFD1 and the second frequency converter VFD2 are connected through the interactive signal line 3, and the second frequency converter VFD2 is in the hot standby state.

[0020] When the first frequency converter VFD1 malfunctions and needs to be stopped, it first blocks the output drive and switches to the ready state. Then, it disconnects the corresponding first output switch K1. At the same time, the stop signal of the first frequency converter VFD1 is transmitted to the second frequency converter VFD2 through the interaction signal line 3. The second frequency converter VFD2 closes the corresponding second output switch K2, so that the second frequency converter VFD2 and the motor M are connected. After detecting that the second output switch K2 is closed, the second frequency converter VFD2 outputs the drive voltage to drive the motor M to continue running.

[0021] When the first inverter VFD1 completes its fault repair and needs to switch back to drive the motor M as the main inverter, or when the second inverter VFD2 malfunctions while driving the motor M and needs to switch to drive the motor M by the first inverter VFD1, the second inverter VFD2 stops malfunctioning or actively stops via a signal, and then disconnects the corresponding second output switch K2. At the same time, it transmits the signal to the first inverter VFD1 through the interaction signal line 3. The first inverter VFD1 closes the corresponding first output switch K1, so that the first inverter VFD1 and the motor M are connected. After detecting that the first output switch K1 is closed, the first inverter VFD1 outputs a drive voltage to drive the motor M to continue running.

[0022] The second frequency converter VFD2, which has malfunctioned, can be repaired after the input power supply is disconnected. After the repair is completed, it can be powered on again to restore the hot standby status of the first frequency converter VFD1.

[0023] When one of the two inverters is manually stopped, the switching and reversal control processes of the two inverters are the same. If a fault is detected in the other inverter during the switching process and its output switch is disconnected, the inverter that was manually stopped will close its corresponding output switch again and continue to drive the motor.

[0024] Generally, the detection of inverter faults and the opening and closing control of switches are all automatically completed by the automation control system according to the control logic.

[0025] This invention effectively avoids motor shutdown caused by a single inverter failure or shutdown through redundant backup of two inverters and interlocking design of the output switches, thus improving system reliability. Furthermore, only one inverter is allowed to drive the motor at a time, ensuring stable operation of the redundant inverter system during switchover. Simultaneously, this invention uses high-speed communication protocol cables or associated signal lines to achieve rapid data exchange and switching between inverters, with a short switching time that depends solely on the output switch's action time.

[0026] The above description is merely a preferred embodiment of the present utility model, used to provide a detailed explanation of the present utility model, and is not intended to limit the present utility model. Those skilled in the art will obviously make various equivalent modifications, variations, or equivalent substitutions to the specific embodiments based on the disclosure of the present utility model, and all such equivalent modifications, variations, or equivalent substitutions should fall within the protection scope of the present utility model. The protection scope of the present utility model is determined by the description in the claims of this application.

Claims

1. A redundant frequency converter switchback control system for driving motors, characterized in that: It includes two independent frequency converters connected by signal lines, an output switch corresponding to each frequency converter, and a motor. The two frequency converters are connected to the same motor through their respective output switches. The output switches are opened and closed according to the control signals of the corresponding frequency converters, and only one output switch is closed at any given time.

2. The redundant frequency converter switchback control system for a drive motor according to claim 1, characterized in that: The signal lines are high-speed communication protocol cables or associated signal lines, and the output switches of the two inverters are logically interlocked through the high-speed communication protocol cables or associated signal lines.

3. The redundant frequency converter switchback control system for a drive motor according to claim 1, characterized in that: The two frequency converters described herein serve as backups for each other.

4. A redundant frequency converter switchback control system for a drive motor according to claim 2, characterized in that: When one of the two frequency converters fails, the corresponding output switch is in the open state, and the output switch of the other frequency converter is triggered to the closed state via the high-speed communication protocol cable or associated signal line.

5. A redundant frequency converter switchback control system for a drive motor according to claim 2, characterized in that: When one of the two frequency converters is manually stopped, the corresponding output switch is in the open state, and the output switch of the other frequency converter is triggered to the closed state via the high-speed communication protocol cable or associated signal line to drive the motor to continue running.

6. A redundant frequency converter switchback control system for a drive motor according to claim 2, characterized in that: When one of the two inverters is manually stopped, and the other inverter is faulty and its output switch is open, the manually stopped inverter will trigger its corresponding output switch to close again via the high-speed communication protocol cable or associated signal line to continue driving the motor.

7. A redundant frequency converter switchback control system for a drive motor according to claim 1, characterized in that: The motor mentioned is an AC motor.

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