An anti-interference protection circuit for a motor based on relay-based high-voltage control

Abstract

This application discloses a motor anti-interference protection circuit based on relay-based high-voltage control, relating to the field of industrial motor control technology. By connecting a 220V AC relay module to the output of the motor protector, low-voltage control is upgraded to high-voltage control, and an independently wired 220V AC current control circuit drives an AC contactor. This solution utilizes the high noise immunity of the 220V high-voltage signal and the physical isolation effect of the relay to completely solve the signal distortion problem caused by electromagnetic interference in traditional motor protection, while maintaining compatibility with the original protector's functions. It has low modification costs and is suitable for anti-interference retrofitting of industrial motor control systems.

Description

Technical Field

[0001] This application relates to the field of industrial motor control technology, and in particular to an anti-interference protection circuit for a motor based on relay-based high-voltage control. Background Technology

[0002] Traditional methods of motor interference suppression mainly rely on motor protectors or other mechatronic protection devices to protect the motor from interference. Motor protectors can provide manual control, short-circuit protection, and overload protection. At the same time, they can also monitor and control parameters such as motor current, temperature, and voltage to extend the motor's service life and improve system safety.

[0003] However, traditional motor protectors use a DC 24V low-current control circuit. Due to its characteristics, this low-current control circuit is easily affected by electromagnetic interference in complex industrial electromagnetic environments such as near frequency converters and high-power equipment, which can lead to distortion of the control signal.

[0004] Electromagnetic interference can easily cause motor protectors to misjudge the motor, such as the motor failing to stop normally, incorrect status feedback signals, and false triggering or failure of protection functions. At the same time, the transmission distance of weak current signals is limited, and the superposition of line voltage drop and noise will further reduce the stability of the system.

[0005] For traditional motor anti-interference methods, existing solutions reduce electromagnetic interference by adding shielded cables or filters, or upgrading to high-protection-level protectors. However, these solutions have the disadvantages of high cost, limited effectiveness, and inability to completely eliminate interference, making them unsuitable for retrofitting existing equipment. Utility Model Content

[0006] This application provides a motor anti-interference protection circuit based on relay-based high-voltage control, which solves the technical problems of high cost, limited effectiveness, and inability to eradicate electromagnetic interference in existing anti-interference methods for motors. It achieves the technical effect of providing a highly reliable anti-interference control loop in a low-cost manner.

[0007] To achieve the above objectives, this application provides the following technical solution:

[0008] An anti-interference protection circuit for a motor based on relay-based high-voltage control includes a motor protector, a relay module, an AC contactor, and a current control circuit. The input terminal of the motor protector is electrically connected to a three-phase power supply. The coil terminal of the relay module is electrically connected to the output terminal of the motor protector. The coil terminal of the AC contactor is electrically connected to the output terminal of the relay module, and the output terminal of the AC contactor is electrically connected to the motor. The current control circuit is electrically connected to the coil terminal of the relay module.

[0009] Preferably, the relay module includes at least three relays, and the coil terminals of the three relays are respectively electrically connected to the start output terminal, stop output terminal and fault output terminal of the motor protector.

[0010] Preferably, the rated voltage of the coil terminal of each relay is 220V AC, and the contact capacity is not less than 5A.

[0011] Preferably, the current control circuit is powered by 220V AC, the wiring method of the current control circuit is twisted-pair shielded wiring, and the shielding layer of the current control circuit is grounded at a single point.

[0012] Preferably, the distance between the connection line between the motor protector and the relay module and the power cable of the current control circuit is greater than 200mm.

[0013] Preferably, the connection line between the motor protector and the relay module, and the power cable of the current control circuit are laid in separate trenches.

[0014] Preferably, the relay module further includes a feedback relay, the coil terminal of which is electrically connected to the output terminal of the AC contactor, and the output terminal of which is electrically connected to the input terminal of the motor protector.

[0015] One or more technical solutions provided in the embodiments of this application have at least the following technical effects or advantages:

[0016] This application improves the anti-interference capability of the motor protector by changing the control of the motor protector to relay control and connecting the relay to the 220V AC control circuit, thus constructing a two-level isolation control architecture of "protector-relay-contactor". At the same time, it solves the technical problem of the motor protector being susceptible to electromagnetic interference from the root while controlling costs. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the circuit framework for an anti-interference protection circuit for a motor based on relay high-voltage control, provided in an embodiment of this application;

[0019] Figure 2 A circuit block diagram of the modified motor anti-interference protection circuit provided in the embodiments of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] In existing technology, the original ABB motor protector uses a DC 24V low-voltage control circuit. This low-voltage control circuit is highly susceptible to interference in complex industrial environments (such as near frequency converters and high-power equipment), which leads to distortion of the motor protector's control signal to the motor. This results in frequent malfunctions and is prone to misjudgments by the motor protector due to electromagnetic interference.

[0022] Please refer to Figures 1 to 2 To address the aforementioned problems, this application provides a motor anti-interference protection circuit based on relay-based high-voltage control. The circuit block diagram of this protection circuit is shown below. Figure 1 As shown, it includes a motor protector, a relay module, an AC contactor, and a current control circuit.

[0023] The output terminal of the motor protector is electrically connected to a three-phase power supply, which includes L1, L2, L3 and a ground terminal (N).

[0024] The coil terminal of the relay module is electrically connected to the output terminal of the motor protector, and the output terminal of the relay module is electrically connected to the coil terminal of the AC contactor.

[0025] The output terminal of the AC contactor is electrically connected to the motor.

[0026] The current control circuit is electrically connected to the coil terminal of the relay module.

[0027] In this embodiment, the relay module includes at least three relays, and the coil terminals of the three relays are all electrically connected to the output terminal of the motor protector.

[0028] Specifically, the motor protector's output terminals include a start output terminal, a stop output terminal, and a fault output terminal, each of which is electrically connected to a relay. The rated voltage of the coil terminal of each relay is 220V, and all are AC current, with a contact current capacity of not less than 5A.

[0029] The start output terminal is configured to output the start control signal of the motor protector; the stop output terminal is configured to output the stop control signal; and the fault output terminal is configured to issue an emergency stop control signal when the motor malfunctions.

[0030] In this embodiment, the current control circuit is powered by 220V AC, and the wiring method in the current control circuit is twisted-pair shielded wiring, with the shielding layer of the current control circuit grounded at a single point.

[0031] The distance between the connection wire between the motor protector and the relay module and the power cable in the current control circuit is greater than 200mm.

[0032] For example, the connection wire between the motor protector and the relay module can be laid in a separate channel from the power cable.

[0033] In this embodiment, the relay module further includes a feedback relay, the coil of which is electrically connected to the output of the AC contactor, and the output of which is electrically connected to the input of the motor protector.

[0034] This application replaces the control of the motor protector with relay control, connecting the relay to a 220V AC control circuit to construct a two-level isolated control architecture of "protector-relay-contactor". This effectively improves the anti-interference capability of the motor protector and, while controlling costs, fundamentally solves the technical problem of the motor protector's susceptibility to electromagnetic interference.

[0035] Specifically, in this embodiment, a 220V intermediate relay module is connected to the output terminal of the motor protector. Simultaneously, the normally open / normally closed contacts of each relay (including the feedback relay) in the relay module are connected to a 220V AC current control circuit and controlled by the 220V AC high voltage, thereby enabling direct driving of the AC contactor coil terminal via the intermediate relay.

[0036] The connection line between the motor protector and the relay module is wired independently and kept away from the power cable (220V AC high voltage) in the current control circuit and other strong interference sources to avoid electromagnetic interference to the motor protector.

[0037] In this embodiment, by adding a relay module between the motor protector and the AC contactor, and replacing the 24V low voltage with 220V AC high voltage, the anti-interference capability of the motor protector is significantly improved. The principle is that the 220V AC signal has a high amplitude and a large noise tolerance, which can eliminate the risk of distortion of the low voltage signal.

[0038] In this embodiment, the addition of a relay module not only retains the core protection functions of the original motor protector for the motor (such as overload and phase loss), but also achieves the technical effect of low modification cost and applicability to the upgrading of existing equipment.

[0039] Meanwhile, each relay in the relay module uses mechanical contacts, achieving the technical effect of surge resistance and long service life. In practical applications, the failure rate of the control circuit is reduced by 90%.

[0040] In this embodiment, a transparent protective cover can also be added to the outside of the relay module to prevent accidental contact with live parts and make the relay status visible, making the fault diagnosis process more intuitive.

[0041] Specific modifications include, for example Figure 2 As shown. Includes:

[0042] (1) Remove the original low-voltage direct connection line: disconnect the low-voltage connection line between the output terminal of the motor protector and the coil terminal of the original AC contactor.

[0043] (2) Install relay modules: Select multiple industrial-grade relays that match the voltage of the coil terminals of the motor protector and AC contactor, and connect the coil terminals of the multiple relays to the "start output terminal", "stop output terminal" and "fault output terminal" of the motor protector, respectively. It should be noted that the specifications and models of each relay should be the same.

[0044] (3) Construct a 220V AC control circuit: Connect a wire from the 220V AC power supply of the control transformer to the normally open contact input terminal of the relay module. At the same time, connect the output terminal of the relay module to the KM coil in the AC contactor.

[0045] (4) Feedback signal modification: The operating status of the motor is converted by the feedback relay and fed back to the input terminal of the motor protector so as to adjust the output signal of the motor protector in real time.

[0046] (5) Debugging and verification, including power-on test and anti-interference test.

[0047] Power-on test: Perform a power-on test on the entire circuit to simulate the output of start control signal, stop control signal and fault control signal to verify the relay action and the engagement state of the AC contactor.

[0048] Anti-interference test: The anti-interference protection circuit of the motor based on relay high-voltage control described in the embodiments of this application is continuously run for 72 hours near the frequency converter group or other high-power electrical appliances in operation to conduct an anti-interference test.

[0049] exist Figure 2 In this circuit, the input terminals of the motor protector QF are connected to the three-phase power supply terminals L1, L2, and L3. At the same time, the motor protector QF also needs to be connected to the ground terminal N of the three-phase power supply.

[0050] Meanwhile, the input terminal of the motor protector QF is also connected to three fuses FU, and the other end of the fuse FU is connected to a voltage and current transformer TA. In this embodiment, the voltage and current transformer TA is selected as the BDCTAD-01 voltage and current transformer.

[0051] The voltage and current transformer TA is controlled by the central controller MCU. In this embodiment, the central controller MCU is selected as a low-voltage motor microcomputer protection and monitoring integrated device with model BDM100-T+D. This device can protect and monitor the motor and feed back the monitoring results to the motor protector QF, so that the motor protector QF outputs the corresponding signal.

[0052] The central controller MCU is also connected to an AC contactor KM, which is used to operate the AC contactor based on monitoring results. Simultaneously, the central controller MCU is also connected to an RS485 communication terminal, which is used for digital communication with other devices (such as servers).

[0053] The central controller MCU is also connected to a transfer switch SA, which is used to switch between local and remote terminals.

[0054] like Figure 2 As shown, for example, the relay module includes relay KA1 and relay KA2. Relay KA1 and relay KA2 are connected in series with the central controller MCU. Meanwhile, relay KA1 is connected in parallel with AC contactor KM, so as to realize the operation of AC contactor KM by controlling the on and off of relay KA1 and relay KA2.

[0055] The AC contactor KM is connected in series with the control panel, which includes switches SB1, SB2, SB3, SB4, DCS, and 1HA. One end of switches DCS and SB3 is connected to the changeover switch SA, and the other end is grounded.

[0056] Switch SB1 is a normally closed switch. When a fault occurs during operation and an emergency stop is required, switch SB1 is opened, causing the AC contactor KM to disconnect and the motor to stop running urgently.

[0057] Switch SB2 is a normally open switch used for the electromagnetic control switch DCS. When switch SB2 is closed, switch DCS also closes. At this time, AC contactor KM is closed, and the motor starts running.

[0058] Switch SB4 is a normally open switch used to electromagnetically control switch SB3. When switch SB4 is closed, switch SB3 also closes, at which point the motor stops running. Switch DCS is then open.

[0059] Switch 1HA is a thermal protection switch used to protect the motor from overheating. When the motor overheats, switch 1HA disconnects, and the entire system stops working. It should be noted that when protecting the drain pump motor in this embodiment of the application, switch 1HA is not used.

[0060] Applying the embodiments of this application to the control modification of the condensate pump, tests showed that the failure rate decreased from an average of 10 times per month to an average of 0 times per month. The shutdown response time was improved from 2-5 seconds (signal jitter) to less than 0.5 seconds, and the shutdown response time became stable.

[0061] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0062] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A motor anti-interference protection circuit based on relay-based high-voltage control, characterized in that, Includes motor protectors, relay modules, AC contactors, and current control circuits; The input terminal of the motor protector is electrically connected to a three-phase power supply. The coil terminal of the relay module is electrically connected to the output terminal of the motor protector; The coil terminal of the AC contactor is electrically connected to the output terminal of the relay module, and the output terminal of the AC contactor is electrically connected to the motor. The current control circuit is electrically connected to the coil terminal of the relay module.

2. The motor anti-interference protection circuit based on relay strong current control according to claim 1, characterized in that, The relay module includes at least three relays, and the coil terminals of the three relays are respectively electrically connected to the start output terminal, stop output terminal and fault output terminal of the motor protector.

3. The motor anti-interference protection circuit based on relay strong current control according to claim 2, characterized in that, The rated voltage of the relay coil terminal is 220V AC, and the contact capacity is not less than 5A.

4. The motor anti-interference protection circuit based on relay strong current control according to claim 1, characterized in that, The current control circuit is powered by 220V AC, and the wiring method of the current control circuit is twisted-pair shielded wiring, with the shielding layer of the current control circuit having a single-point ground contact.

5. The motor anti-interference protection circuit based on relay strong current control according to claim 1, characterized in that, The distance between the connection line between the motor protector and the relay module and the power cable of the current control circuit is greater than 200mm.

6. The motor anti-interference protection circuit based on relay high-voltage control according to claim 1, characterized in that, The connection lines between the motor protector and the relay module, and the power cables of the current control circuit are laid in separate trenches.

7. The motor anti-interference protection circuit based on relay strong current control according to claim 1, characterized in that, The relay module also includes a feedback relay, the coil of which is electrically connected to the output of the AC contactor, and the output of which is electrically connected to the input of the motor protector.

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