Current detection and protection circuit for impact crushers

Abstract

The utility model mentions a kind of current detection and protection circuit for impact crusher, including three-phase current transformer, circuit board mutual inductor, operational amplifier circuit, polarity adjustment circuit, filter circuit, analog-digital conversion chip, protection logic circuit and relay drive circuit, three-phase current transformer is connected in series in the three-phase power supply loop of main motor, for the large current of host computer operation is converted into detectable small current signal, circuit board mutual inductor is sequentially connected with operational amplifier circuit, the voltage signal of operational amplifier circuit output is sent into analog-digital conversion chip after polarity adjustment circuit and filter circuit processing, the output end of protection logic circuit is connected with relay drive circuit by photo-coupler isolation circuit, relay in relay drive circuit normally open contact is connected in series in main motor control loop, in general, the utility model has the advantages of high detection precision, complete operation process, strong anti-interference ability and reliable protection action.

Description

Technical Field

[0001] This utility model belongs to the technical field of impact crusher equipment, specifically relating to a current detection and protection circuit for impact crushers. Background Technology

[0002] Impact crushers are crucial crushing equipment in the mining and building materials industries. Their main motors are typically high-power motors, which experience significant load fluctuations during operation, making them highly susceptible to overload, short circuits, or three-phase imbalance. Failure to detect and implement protective measures promptly can lead to motor winding burnout, damage to power devices, and even system malfunctions or safety accidents.

[0003] Currently, most common current protection methods rely on thermal relays or simple current transformers in conjunction with protective switches. However, thermal relays are slow to operate, and when unconditioned current transformer output signals are used directly for control, misjudgments are likely to occur, making the protection action insufficiently sensitive and unable to reflect rapid changes in current in real time. Existing current detection and protection devices can only achieve single overcurrent protection, lacking hierarchical logic for different operating conditions. They cannot meet the multi-level protection requirements, including alarms, delayed shutdown, and emergency cut-off. At the same time, the circuit's filtering and isolation measures are insufficient, resulting in poor anti-interference capabilities. In high electromagnetic interference environments such as crushers, they are very prone to malfunction, affecting the normal production efficiency of the equipment.

[0004] To address this, we propose a current detection and protection circuit for impact crushers, which solves the problems of insufficient current detection accuracy, simple protection logic, weak anti-interference capability, and inability to achieve linkage with the crusher control system in existing circuits. Utility Model Content

[0005] In view of this, this utility model proposes a current detection and protection circuit for impact crushers, which is applied to the field of impact crusher equipment technology and solves the existing technical problems of insufficient current detection accuracy, simple protection logic, weak anti-interference ability and inability to achieve linkage with the crusher control system.

[0006] To achieve the above-mentioned technical objectives, the specific technical solution adopted by this utility model is as follows: A current detection and protection circuit for an impact crusher includes a three-phase current transformer, a circuit board current transformer, an operational amplifier circuit, a polarity adjustment circuit, a filter circuit, an analog-to-digital converter chip, a protection logic circuit, and a relay drive circuit. The three-phase current transformer is connected in series in the three-phase power supply circuit of the main motor to convert the large current of the main unit into a detectable small current signal. The circuit board current transformer and the operational amplifier circuit are connected in sequence. The voltage signal output by the operational amplifier circuit is processed by the polarity adjustment circuit and the filter circuit and then sent to the analog-to-digital converter chip. The analog-to-digital converter chip digitizes the current signal. The output terminal of the protection logic circuit is connected to the relay drive circuit through an optocoupler isolation circuit. The protection logic circuit determines whether the motor is overloaded or the three-phase is unbalanced based on the sampled data and generates an alarm or shutdown signal. The normally open contact of the relay in the relay drive circuit is connected in series in the main motor control circuit. It can receive the output signal of the protection logic circuit and control the on / off of the main motor circuit, thereby protecting the main motor of the impact crusher when the current is abnormal.

[0007] Furthermore, a lubrication motor, a cooling fan, and a heater are installed in addition to the main motor. The current of the lubrication motor, the cooling fan, and the heater is detected by the circuit board current transformer through the through-core current transformer. The circuit board current transformer converts the 0-5 A current signal into a 0-2.5 mA milliampere level signal.

[0008] Furthermore, the operational amplifier circuit includes an OP07 precision operational amplifier with an output voltage range of 0 to ±5 V. The polarity adjustment circuit includes an operational amplifier and a diode, used to automatically adjust the positive and negative half-wave signals.

[0009] Furthermore, the filter circuit is a π-type filter structure, which includes a filter resistor, a filter capacitor, and a filter inductor. The cutoff frequency of the filter circuit is set between 100 Hz and 500 Hz, and the analog-to-digital converter chip uses a high-speed AD chip with a sampling rate of 2.4 MSPS.

[0010] Furthermore, the protection logic circuit employs inverse time characteristics for graded protection. The protection logic circuit includes a comparison circuit for detecting the magnitude of the motor operating current and comparing it with the rated current, and a control circuit for outputting alarm and shutdown signals. When the detected current exceeds 1.5 times the rated current, the protection logic circuit drives the control circuit to output an alarm signal after a 20-second delay, and outputs a shutdown signal after a 42-second delay. When the three-phase current difference exceeds 10%, the protection logic circuit outputs an alarm signal. When the three-phase current difference exceeds 30%, the protection logic circuit outputs a shutdown signal.

[0011] Furthermore, the output of the protection logic circuit is electrically connected to the feeder frequency converter, and the feeding speed is adjusted according to the current magnitude, so that the motor is kept within the set operating current range.

[0012] By adopting the above technical solution, this utility model can also bring the following beneficial effects: 1. This utility model discloses a current detection and protection circuit for an impact crusher. By combining a three-phase current transformer and a circuit board current transformer, it achieves comprehensive acquisition of the current of the main motor and auxiliary motors such as the lubrication system. After the signal is processed step by step by the operational amplifier circuit, polarity adjustment circuit and filter circuit, the ampere-level current can be stably converted into the milliampere-level current, and further output as a standard voltage signal, ensuring the accuracy and anti-interference capability of the signal. This structure not only improves the real-time performance and accuracy of detection, but also enables the circuit to maintain stable operation in the high electromagnetic interference environment of the impact crusher, avoiding the problem of machine shutdown caused by malfunction. It has the advantages of high detection accuracy and strong anti-interference capability.

[0013] 2. This utility model discloses a current detection and protection circuit for an impact crusher, which combines a high-speed analog-to-digital converter chip with an inverse-time protection logic circuit. It can output graded protection signals according to different degrees of current abnormality. When the current exceeds 1.5 times the rated value, it realizes delayed alarm and delayed shutdown. When the three-phase current difference exceeds a set ratio, it promptly alarms or shuts down. The action is executed through an optocoupler isolation circuit and a DC 24V relay to ensure reliable transmission of protection signals. At the same time, the output of the protection logic circuit can also be electrically connected to the feeder frequency converter to automatically adjust the feeding speed according to the current magnitude, realizing closed-loop control of detection and execution. This ensures that the impact crusher operates within the optimal current range, improves equipment operating efficiency and service life, and has the advantages of perfect protection logic, reliable action and linkage control. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a frame connection structure diagram of a current detection and protection circuit for an impact crusher mentioned in this utility model; Figure 2 This is the circuit diagram for the current detection and protection of the impact crusher in this embodiment; Figure 3 This is a partial enlarged view of the impact crusher current detection and protection circuit in this embodiment; Figure 4 This is the main unit start-up circuit diagram of the impact crusher in this embodiment; Figure 5This is the main circuit diagram of the lubrication system of the impact crusher in this embodiment; Figure 6 This is a waveform diagram of the current signal monitoring point in the filter circuit of this embodiment; Figure 7 This is a current curve diagram of the protection logic circuit in this embodiment undergoing inverse time processing; Detailed Implementation

[0016] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0017] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this utility model, not all of them. This utility model can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0018] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0019] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0020] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details. Example 1

[0021] like Figure 1 , Figure 2 and Figure 3 As shown, a current detection and protection circuit for an impact crusher includes a three-phase current transformer, a circuit board current transformer, an operational amplifier circuit, a polarity adjustment circuit, a filter circuit, an analog-to-digital converter chip, a protection logic circuit, and a relay drive circuit. The three-phase current transformers are connected in series in the three-phase power supply circuit of the main motor to convert the large operating current into a detectable small current signal. The circuit board current transformer further converts the 0-5 A current signal into a milliampere-level signal for subsequent processing. The current detection circuit includes an operational amplifier circuit UL1, a polarity adjustment circuit (composed of UL2, UL3, and diodes DL100 and DL101), a filter circuit, and an analog-to-digital converter chip. The operational amplifier circuit UL1 uses an OP07 precision operational amplifier to amplify the input ±2.5 mA current signal into a 0-±5 V voltage signal to provide a standardized amplitude. The polarity adjustment circuit automatically corrects the positive and negative polarity of the input signal. The filter circuit has a π-type structure to weaken high-frequency interference and output a stable signal. The analog-to-digital converter chip samples the analog signal at high speed and converts it into a digital signal for real-time processing by the protection logic circuit.

[0022] like Figure 4 and Figure 5 As shown, in the three-phase power supply circuit of the main motor, three-phase current transformers TA1, TA2, TA3, and TA4 are connected in series to convert the large current during operation into a small current signal of 0-5 A. The current of auxiliary equipment such as the lubrication motor, cooling fan, and heater of the lubrication station is directly connected to the circuit board transformer through the core to realize the real-time acquisition of the operating current of the auxiliary system. The current detection circuit also includes a circuit board transformer TL1, which further converts the main operating current into a milliampere-level signal of 0-2.5 mA as the input for subsequent circuit processing.

[0023] During polarity adjustment: When the input signal is 0 to -5 V, due to the unidirectional conductivity of diodes DL100 and DL101, the UL2 op-amp does not operate, and the negative input terminal of UL3 receives the negative signal and outputs a corrected positive voltage signal. When the input signal is 0 to +5 V, the UL2 op-amp amplifies it to a 0 to -10 V signal, generating a 0 to -5 V level at the superposition point. This level is then inverted by UL3 and output, ultimately forming a standard 0 to +5 V signal. Therefore, the polarity adjustment circuit can automatically correct the polarity of input signals of different polarities, ensuring accurate sampling in subsequent stages.

[0024] The corrected signal enters the filter circuit, which consists of components such as EZ21, CC1, RC4, EZ1, and CL4. Its cutoff frequency is 100 Hz to 500 Hz, effectively filtering out high-frequency interference and outputting a stable voltage waveform. Figure 6 The waveforms of the circuit signal at each detection node clearly reflect the changes before and after signal processing. The filtered voltage signal is input to a high-speed AD conversion chip (sampling rate of 2.4 MSPS), where it is converted into a digital signal. This digital signal then enters the protection logic circuit for real-time processing.

[0025] like Figure 7 As shown, the protection logic circuit adopts an inverse-time characteristic design. When the detected current exceeds 1.5 times the rated current Ie, an alarm signal is output after a 20-second delay; when the current continues for more than 42 seconds, a shutdown signal is output; when the three-phase current difference exceeds 10%, an alarm signal is output; when the difference exceeds 30%, a shutdown signal is output directly. The output of the protection logic circuit is transmitted through an optocoupler isolation circuit to drive a 24V DC relay. Its normally open contact is connected in series in the main motor control circuit, thereby cutting off the main motor power supply when the current is abnormal. The output of the protection logic circuit is connected to the feeder frequency converter to form a closed-loop control of acquisition-control-execution. When the three-phase current of the motor is less than the set operating current, the system automatically increases the feeding rate; when the motor current exceeds the set operating current, the system automatically reduces the feeding rate, so that the motor always operates within the optimal current range, avoiding overload and underload, and ensuring long-term stable operation of the equipment.

[0026] In summary, this utility model combines a three-phase current transformer with a circuit board current transformer, and with operational amplification, polarity adjustment, filtering and high-speed sampling, it realizes comprehensive detection and processing of the motor current of the impact crusher. Combined with inverse time protection logic and closed-loop control, it achieves accurate alarm, reliable shutdown and intelligent adjustment. It has the advantages of high detection accuracy, complete operation process, strong anti-interference ability and reliable protection action.

[0027] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A current detection and protection circuit for an impact crusher, characterized in that: The system includes a three-phase current transformer, a circuit board current transformer, an operational amplifier circuit, a polarity adjustment circuit, a filter circuit, an analog-to-digital converter chip, a protection logic circuit, and a relay drive circuit. The three-phase current transformer is connected in series in the three-phase power supply circuit of the main motor to convert the large current of the main unit into a detectable small current signal. The circuit board current transformer is connected in sequence with the operational amplifier circuit. The voltage signal output by the operational amplifier circuit is processed by the polarity adjustment circuit and the filter circuit and then sent to the analog-to-digital converter chip, which digitizes the current signal. The output of the protection logic circuit is connected to the relay drive circuit through an optocoupler isolation circuit. The protection logic circuit determines whether the motor is overloaded or the three phases are unbalanced based on the sampled data and generates an alarm or shutdown signal. The normally open contact of the relay in the relay drive circuit is connected in series in the main motor control circuit. It can receive the output signal of the protection logic circuit and control the on / off of the main motor circuit, thereby protecting the main motor of the impact crusher when the current is abnormal.

2. The current detection and protection circuit for an impact crusher according to claim 1, characterized in that: A lubrication motor, a cooling fan, and a heater are provided outside the main motor. The current of the lubrication motor, the cooling fan, and the heater is detected by a circuit board current transformer connected to a through-core current transformer. The circuit board current transformer converts the 0-5 A current signal into a 0-2.5 mA milliampere level signal.

3. The current detection and protection circuit for an impact crusher according to claim 2, characterized in that: The operational amplifier circuit includes an OP07 precision operational amplifier, the output voltage range of which is 0 to ±5 V. The polarity adjustment circuit includes an operational amplifier and a diode, which is used to automatically adjust the positive and negative half-wave signals.

4. The current detection and protection circuit for an impact crusher according to claim 3, characterized in that: The filtering circuit is a π-type filtering structure, which includes a filter resistor, a filter capacitor, and a filter inductor. The cutoff frequency of the filtering circuit is set between 100 Hz and 500 Hz. The analog-to-digital converter chip is a high-speed AD chip with a sampling rate of 2.4 MSPS.

5. The current detection and protection circuit for an impact crusher according to claim 4, characterized in that: The protection logic circuit employs inverse time characteristics for graded protection. It includes a comparison circuit for detecting the motor's operating current and comparing it to the rated current, and a control circuit for outputting alarm and shutdown signals. When the detected current exceeds 1.5 times the rated current, the protection logic circuit drives the control circuit to output an alarm signal after a 20-second delay, and outputs a shutdown signal after a 42-second delay. When the three-phase current difference exceeds 10%, the protection logic circuit outputs an alarm signal; when the three-phase current difference exceeds 30%, the protection logic circuit outputs a shutdown signal.

6. The current detection and protection circuit for an impact crusher according to claim 5, characterized in that: The output of the protection logic circuit is electrically connected to the feeder frequency converter, and the feeding speed is adjusted according to the current magnitude, so that the motor is kept within the set operating current range.

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