Compressor locked-rotor protection circuit based on real-time current monitoring and integrated system

Abstract

The invention discloses a compressor locked-rotor protection circuit based on real-time current monitoring and an integrated system, the compressor locked-rotor protection circuit comprises a protection unit and a control unit, the protection unit inputs a compressor current sampling signal 11 and then generates a configuration signal 21 corresponding to a current power supply system to the control unit for comparison detection; the protection unit comprises a plurality of operational amplifiers, a plurality of resistors and a multiplier, the in-phase end of an operational amplifier U3 in the plurality of operational amplifiers is connected with the output end of an operational amplifier U5 and one end of a resistor R13, the anti-phase end of the operational amplifier U3 in the plurality of operational amplifiers is connected with one end of a resistor R7, and the output end of the operational amplifier U3 in the plurality of operational amplifiers is connected with the other end of the resistor R7 and the 21 end; the in-phase end of the operational amplifier U4 is connected with one end of a resistor R15, the anti-phase end is connected with one end of a resistor R8, one end of a resistor R9 and one end of a resistor R10, and the output end is connected with the X pin of the multiplier A1 and one end of a resistor R11; the in-phase end of the operational amplifier U5 is connected with one end of the resistor R14, and the anti-phase end is connected with the other end of the resistor R11 and the other end of the resistor R13.

Description

Technical Field

[0001] The present invention relates to the technical field of compressors, and in particular to a compressor stall protection circuit and integrated system based on real-time current monitoring. Background Art

[0002] In traditional multi-station compressor current detection and protection systems, compressors often need to be started in batches for testing. The number of starts is set according to the maximum power supply current of the power supply system. However, due to the existence of various power supply combination schemes in actual applications, when the system needs to adapt to different power supply configurations, the current transformer with a fixed ratio will bring obvious compatibility issues. The wider the system compatibility range, the lower the effective value of the actual power supply protection capacity. The conventional practice is to replace the current transformer with a different ratio, but this method has two major limitations: on the one hand, the range of selectable ratios is limited due to the transformer model specifications; on the other hand, when compressors of different powers are used in combination, the cross-influence will cause the actual protection capacity to be further reduced. Summary of the Invention

[0003] In view of the above technical problems, the purpose of the present invention is to provide a compressor stall protection circuit and integrated system based on real-time current monitoring, including a protection unit and a control unit. After the protection unit inputs the compressor current sampling signal 1_1, it generates a configuration signal 2_1 corresponding to the current power supply system to the control unit for comparison and detection, and feeds back a disable signal 1_4 or a common current limiting protection signal 1_3 to disable the compressor. The protection unit includes several operational amplifiers, several resistors, and a multiplier. The operational amplifier U3 among the several operational amplifiers is connected to the output end of the operational amplifier U5 and one end of the resistor R13 in the same phase, and is connected to one end of the resistor R7 in the opposite phase. The output end Connect the other end of resistor R7 and terminal 2_1; the op amp U4 is connected to one end of resistor R15 in the same phase, one end of resistor R8, one end of resistor R9, and one end of resistor R10 in the opposite phase, and the output end is connected to the X pin of multiplier A1 and one end of resistor R11; the op amp U5 is connected to one end of resistor R14 in the same phase, and the opposite phase is connected to the other end of resistor R11 and the other end of resistor R13; the op amp U6 is connected to one end of resistor R20 in the opposite phase, and the output end is connected to one end of resistor R9 and the other end of resistor R20; the output end of multiplier A1 is connected to the other end of resistor R8; the other end of resistor R10 is connected to terminal 1_1; the other end of resistor R14 and the other end of resistor R15 are grounded.

[0004] Furthermore, the control unit includes a processor, which receives the 2_1 signal of the protection unit, performs calculations, compares it with the power supply protection threshold reference signal, and detects the compressor that has not been started at the corresponding workstation, and feeds back the disable signal 1_4 signal of the corresponding workstation to perform compressor disable control after exceeding the power supply protection threshold reference signal.

[0005] Furthermore, the protection unit also includes several operational amplifiers, several diodes, several resistors, and field effect transistors. The field effect transistor is Q1, and its source receives the common current limiting protection signal 1_3 and generates a corresponding disable signal 1_4 to control the compressor to disable startup; the operational amplifier U1 is connected to the cathode of the diode D1, the cathode of the diode D2, one end of the resistor R4, and one end of the resistor R6 in the same phase, and is connected to one end of the resistor R2, one end of the resistor R3, and the 1_2 end in the opposite phase, and the output end is connected to the gate of the field effect transistor Q1 and the anode of the diode D2; the operational amplifier U2 is connected to the 1_1 end in the same phase, and is connected to one end of the resistor R5 and one end of the resistor R12 in the opposite phase, and the output end is connected to the anode of the diode D1; the drain of the field effect transistor Q1 is connected to one end of the resistor R1 and the 1-4 end; the other end of the resistor R3, the other end of the resistor R6, and the other end of the resistor R12 are connected to the power supply, and the other end of the resistor R1, the other end of the resistor R2, the other end of the resistor R4, and the other end of the resistor R5 are grounded.

[0006] Furthermore, the protection unit also includes a resistor, one end of the resistor R25 is connected to the 2_1 terminal, and the other end is connected to the 3_1 terminal; the control unit includes several operational amplifiers and several resistors, the operational amplifier U7 among the several operational amplifiers is connected to the 3_1 terminal in the same phase, the inverting terminal is connected to one end of the resistor R21 and one end of the resistor R22, the output terminal is connected to the non-phase terminal of the operational amplifier U8 and the other end of the resistor R22; the output terminal of the operational amplifier U8 is connected to the 1_3 terminal; the other end of the resistor R21 is grounded.

[0007] Furthermore, the protection unit also includes several resistors, one end of the resistor R16 among the several resistors is connected to one end of the resistor R17 and the Y pin of the multiplier A1, and the other end and one end of the resistor R18 are connected to the power supply; the other end of the resistor R18 is connected to the non-inverting end of the operational amplifier U6 and one end of the resistor R19; the other end of the resistor R17 and the other end of the resistor R19 are grounded.

[0008] Furthermore, the control unit also includes a plurality of resistors, one end of the resistor R23 among the plurality of resistors is connected to the power supply, and the other end is connected to the inverting end of the operational amplifier U8 and one end of the resistor R24; the other end of the resistor R24 ​​is grounded.

[0009] Furthermore, an integrated system includes any one of the above-mentioned compressor stall protection circuits based on real-time current monitoring.

[0010] The beneficial effects of the present invention compared with the prior art are:

[0011] The present invention can generate corresponding configuration sampling signals according to different power supply systems to prevent the effective value of the protection capacity from decreasing. It also provides an integrated control method that can be used after physical plugging without occupying processor pins and program changes when adding or reducing workstations. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, a brief introduction is given below to the prior art and 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 any creative work.

[0013] Figure 1 and Figure 2 This is a circuit structure diagram of the protection unit provided by the present invention.

[0014] Figure 3 This is a circuit structure diagram of the control unit provided by the present invention. DETAILED DESCRIPTION

[0015] In order to make the objects and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the embodiments. It should be understood that the following text is only used to describe one or several specific implementation methods of the present invention and does not strictly limit the scope of protection specifically requested by the present invention.

[0016] The present invention discloses a compressor stall protection circuit and integrated system based on real-time current monitoring, including a protection unit and a control unit. After the protection unit inputs the compressor current sampling signal 1_1, it generates a configuration signal 2_1 corresponding to the current power supply system to the control unit for comparison and detection, and feeds back a disable signal 1_4 or a common current limiting protection signal 1_3 to disable the compressor from starting. The protection unit includes several operational amplifiers, several resistors, and a multiplier. The operational amplifier U3 in the several operational amplifiers is connected to the output end of the operational amplifier U5 and one end of the resistor R13 in the same phase, to one end of the resistor R7 in the opposite phase, and to the other end of the output terminal of the resistor R7 in the opposite phase. The op amp U4 is connected to one end of the resistor R15 in the same phase, one end of the resistor R8, one end of the resistor R9, and one end of the resistor R10 in the opposite phase, and the output end is connected to the X pin of the multiplier A1 and one end of the resistor R11; the op amp U5 is connected to one end of the resistor R14 in the same phase, and the opposite phase is connected to the other end of the resistor R11 and the other end of the resistor R13; the op amp U6 is connected to one end of the resistor R20 in the opposite phase, and the output end is connected to one end of the resistor R9 and the other end of the resistor R20; the output end of the multiplier A1 is connected to the other end of the resistor R8; the other end of the resistor R10 is connected to the 1_1 end; the other end of the resistor R14 and the other end of the resistor R15 are grounded.

[0017] Specifically, the control unit includes a processor, which receives the 2_1 signal of the protection unit, performs calculations, compares it with the power supply protection threshold reference signal, and detects the compressor that has not been started at the corresponding workstation, and feeds back the disable signal 1_4 signal of the corresponding workstation to perform compressor disable control after exceeding the power supply protection threshold reference signal.

[0018] Specifically, the protection unit also includes several operational amplifiers, several diodes, several resistors, and field effect transistors. The field effect transistor is Q1, and its source receives the common current limiting protection signal 1_3 and generates a corresponding disable signal 1_4 to control the compressor to disable startup; the operational amplifier U1 is connected to the cathode of the diode D1, the cathode of the diode D2, one end of the resistor R4, and one end of the resistor R6 in the same phase, and is connected to one end of the resistor R2, one end of the resistor R3, and the 1_2 end in the opposite phase, and the output end is connected to the gate of the field effect transistor Q1 and the anode of the diode D2; the operational amplifier U2 is connected to the 1_1 end in the same phase, and is connected to one end of the resistor R5 and one end of the resistor R12 in the opposite phase, and the output end is connected to the anode of the diode D1; the drain of the field effect transistor Q1 is connected to one end of the resistor R1 and the 1-4 end; the other end of the resistor R3, the other end of the resistor R6, and the other end of the resistor R12 are connected to the power supply, and the other end of the resistor R1, the other end of the resistor R2, the other end of the resistor R4, and the other end of the resistor R5 are grounded.

[0019] Specifically, the protection unit also includes a resistor, one end of the resistor R25 is connected to the 2_1 terminal, and the other end is connected to the 3_1 terminal; the control unit includes several op amps and several resistors, the op amp U7 among the several op amps is connected to the 3_1 terminal in the same phase, the inverting terminal is connected to one end of the resistor R21 and one end of the resistor R22, the output terminal is connected to the non-phase terminal of the op amp U8 and the other end of the resistor R22; the output terminal of the op amp U8 is connected to the 1_3 terminal; the other end of the resistor R21 is grounded.

[0020] Specifically, the protection unit also includes several resistors, one end of the resistor R16 among the several resistors is connected to one end of the resistor R17 and the Y pin of the multiplier A1, and the other end and one end of the resistor R18 are connected to the power supply; the other end of the resistor R18 is connected to the non-inverting end of the operational amplifier U6 and one end of the resistor R19; the other end of the resistor R17 and the other end of the resistor R19 are grounded.

[0021] Specifically, the control unit further includes a plurality of resistors, one end of the resistor R23 of the plurality of resistors is connected to the power supply, and the other end is connected to the inverting end of the operational amplifier U8 and one end of the resistor R24; the other end of the resistor R24 ​​is grounded.

[0022] Specifically, an integrated system includes any one of the above-mentioned compressor stall protection circuits based on real-time current monitoring.

[0023] In the attached figure, 1_1 represents the compressor current sampling signal, 2_1 represents the compressor current sampling signal after automatic configuration, 1_2 represents the reset signal, each protection unit is connected in parallel, 1_3 represents the current limiting protection signal, 1_4 represents the disable signal, 3_1 represents the actual power supply current sampling signal, the protection circuit is composed of protection units and control units corresponding to the number of compressor stations, and the 1_1 signal of each protection unit is input by a current transformer with the same transformation ratio. In the two output forms, the 0-10V output is directly fed back to 1_1, and the 4-20ma output needs to be connected in series with the conversion circuit before being fed back to 1_1. The conversion circuit is not shown in the attached figure. The protection unit is powered by 12V, and the current transformer The transformation ratio is 1:100, and the initial corresponding current limit is 1000A. Assume that the compressor of the current station is started and the current is 100A. The 1V current sampling signal is fed back to the reverse end of the operational amplifier U4 through the resistor R10. After the operational amplifier U4 is inverted, it is fed back to the X pin of the multiplier A1 from the output end. The Y pin of the multiplier A1 is set by the resistor R16 and the resistor R17 to be compatible with the configuration voltage reference signal. In the above example, the resistor R17 is 2K, and the resistor R16 is 10K. When the resistor R16 does not reduce the resistance, the voltage at the resistor R17 end is 2V. After the multiplier A1 product is multiplied, it will be fed back to the inverting end of the operational amplifier U4 by the resistor R8, and the non-inverting end of the operational amplifier U6 is fed back through the resistor R18 and the resistor R19. Under the R19 setting, the voltage reference signal is compatible with the configuration, where the resistance of resistor R19 is 1K, and the resistance of resistor R18 is 11K. When the resistor R18 does not reduce the resistance, the op amp U6 non-inverting terminal is 1V input. At this time, the op amp U6 will be negatively fed back by the resistor R20 and then input to the inverting terminal of the op amp U4 by the resistor R9 before outputting. After the output signal of the op amp U4 is input to the inverting terminal of the op amp U5 through the resistor R11, the op amp U5 will be fed back to the output terminal of the op amp U5 through the resistor R13 and then inverted again to obtain a 1V output signal corresponding to the current transformer ratio under the initial power supply system. The output is fed back to 2_1 after being followed by the op amp U3 and the resistor R7. Assuming that the current limit is changed to 1250A, it is still the same position. The compressor and current, the compressor current sampling signal 1_1 and the non-inverting input of the op amp U6 remain unchanged. After reducing the resistance of the resistor R16 to about 7.56, the op amp U4 outputs 0.8V after the input of 100A. Conversely, when it is compatible, the resistance of the resistor R18 is reduced to complete the configuration of the corresponding output. Compared with the method of achieving upward and downward compatibility based on the difference in the transformer ratio, this method can reduce the attenuation to the corresponding millivolt level. In this embodiment, the 2_1 feedback signal of each protection unit is sent to the processor for calculation and compared with the power supply protection threshold reference signal to detect the compressor that has not been started at the corresponding workstation. After exceeding the power supply protection threshold reference signal, the 1_4 signal of the corresponding workstation is fed back for prohibition control.

[0024] In one embodiment, an integrated control method is provided. Compared with the method of using a processor to detect and control the parameters of multiple protection units 2_1 and the corresponding workstations to disable and start, the processor pins and program changes can be avoided when adding or reducing workstations. After physical plugging, only the corresponding protection unit will feedback the 1_4 signal to complete the detection and control of the disable and start. During integration, the protection unit is packaged according to the number of control bits, and the control unit is packaged separately. 3_1 is connected through a pin header, 1_3 is connected in parallel and then connected through a jumper. The compressor current sampling signal 1_1 is first fed back to the in-phase terminal of the operational amplifier U2, and the sampling reference signal is set at the inverting terminal of the operational amplifier U2. After the compressor is started, the output signal of the operational amplifier U2 is fed back to the The op amp U1 non-inverting terminal, the op amp U1 inverting terminal and the non-inverting terminal are first set with different startup reference signals. When powered on, the voltages at the resistor R6 and resistor R4 terminals are less than the voltages at the resistor R3 and resistor R2 terminals. After the op amp U2 outputs, the resistor R4 pulls up the voltage at the non-inverting terminal of the op amp U1. One path of the op amp U1 output signal is fed back to the non-inverting terminal of the op amp U1 through the diode D2, and the other path is output to the gate of the field effect transistor Q1. The field effect transistor Q1 is cut off. At the same time, the 2_1 signal of each protection unit is input to the op amp U7 in parallel by the corresponding resistor R25 and 3_1. The output terminal of the op amp U7 is fed back to the inverting terminal of the op amp U7 through the resistor R22, and the actual power supply current sampling signal 3_1 is superimposed and input to the op amp U8. The op amp U 8. The inverting terminal sets the protection threshold percentage reference voltage signal. When the threshold is exceeded, the operational amplifier U8 compares the voltages of the non-inverting terminal and the inverting terminal and outputs the 1_3 signal to the source of the field effect tube Q1. When each station receives the 1_3 signal and there is no input to the gate of the field effect tube Q1, the 1_4 signal is fed back to the corresponding station to stop and start. The 1_4 signal is uninterrupted. After the compressor of this round of corresponding station is detected, the protection unit 1_2 is input. The voltage potential of the inverting terminal of the operational amplifier U1 is greater than the voltage of the non-inverting terminal of the operational amplifier U1 fed back to the operational amplifier U1 through the diode D2. The operational amplifier U1 is cut off or outputs an offset voltage. The voltage is greater than the negative voltage conduction threshold from the gate to the source of the field effect tube Q1, and the field effect tube Q1 is turned on. The 1_3 signal is fed back to 1_4. The control of 1_4 can be disconnected by connecting the auxiliary contact of the relay to the main contactor coil, or an isolating switch can be used to completely prohibit stopping. The relay and contactor are not shown in the attached drawings. Then, after comparison through the operational amplifier U8, the output current limiting protection signal 1_3 is cut off. In addition to processing the corresponding voltage divider input through the Y pin of the operational amplifier U6 and the multiplier A1, it can also be controlled by the power supply input method. The corresponding voltage can be satisfied after the above-mentioned regulation. In addition to all integration, the multiple prohibition signals 1_4 of the corresponding workstations output after detection by the processor after feedback from 2_1 can be replaced by a common current limiting protection signal 1_3. At this time, the control unit is not encapsulated, and only the protection unit is set.

[0025] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A compressor stall protection circuit based on real-time current monitoring, characterized in that: It includes a protection unit and a control unit. After the protection unit inputs the compressor current sampling signal 1_1, it generates a configuration signal 2_1 corresponding to the current power supply system to the control unit for comparison and detection, and feeds back a disable signal 1_4 or a common current limiting protection signal 1_3 to disable the compressor. The protection unit includes several operational amplifiers, several resistors, and a multiplier. The operational amplifier U3 in the several operational amplifiers is connected to the output end of the operational amplifier U5 and one end of the resistor R13 in the same phase, to one end of the resistor R7 in the opposite phase, and to the other end of the resistor R7 and the end 2_1 in the output; the operational amplifier U4 is connected to the same phase One end of resistor R15 is connected to one end of resistor R8, one end of resistor R9, and one end of resistor R10 with an inverting terminal, and the output terminal is connected to the X pin of multiplier A1 and one end of resistor R11; the non-inverting terminal of op amp U5 is connected to one end of resistor R14, and the inverting terminal is connected to the other end of resistor R11 and the other end of resistor R13; the inverting terminal of op amp U6 is connected to one end of resistor R20, and the output terminal is connected to one end of resistor R9 and the other end of resistor R20; the output terminal of multiplier A1 is connected to the other end of resistor R8; the other end of resistor R10 is connected to terminal 1_1; the other end of resistor R14 and the other end of resistor R15 are grounded.

2. The compressor stall protection circuit based on real-time current monitoring according to claim 1, characterized in that: The control unit includes a processor, which receives the 2_1 signal of the protection unit, performs calculations, compares the signal with the power supply protection threshold reference signal, and detects the compressor that has not been started at the corresponding workstation. After exceeding the power supply protection threshold reference signal, the processor feeds back the disable signal 1_4 signal of the corresponding workstation to perform compressor disable control.

3. The compressor stall protection circuit based on real-time current monitoring according to claim 1, characterized in that: The protection unit also includes several operational amplifiers, several diodes, several resistors, and field-effect transistors. The field-effect transistor is Q1, and its source receives the common current limiting protection signal 1_3 and generates the corresponding disable signal 1_4 to control the compressor to disable startup; the operational amplifier U1 is connected to the cathode of the diode D1, the cathode of the diode D2, one end of the resistor R4, and one end of the resistor R6 in the same phase, and is connected to one end of the resistor R2, one end of the resistor R3, and the 1_2 end in the opposite phase, and the output end is connected to the gate of the field-effect transistor Q1 and the anode of the diode D2; the operational amplifier U2 is connected to the 1_1 end in the same phase, and is connected to one end of the resistor R5 and one end of the resistor R12 in the opposite phase, and the output end is connected to the anode of the diode D1; the drain of the field-effect transistor Q1 is connected to one end of the resistor R1 and the 1-4 ends; the other end of the resistor R3, the other end of the resistor R6, and the other end of the resistor R12 are connected to the power supply, and the other end of the resistor R1, the other end of the resistor R2, the other end of the resistor R4, and the other end of the resistor R5 are grounded.

4. The compressor stall protection circuit based on real-time current monitoring according to claim 1, characterized in that: The protection unit also includes a resistor, one end of the resistor R25 is connected to the 2_1 terminal, and the other end is connected to the 3_1 terminal; the control unit includes several operational amplifiers and several resistors, the operational amplifier U7 among the several operational amplifiers is connected to the 3_1 terminal in the same phase, the inverting terminal is connected to one end of the resistor R21 and one end of the resistor R22, the output terminal is connected to the non-inverting terminal of the operational amplifier U8 and the other end of the resistor R22; the output terminal of the operational amplifier U8 is connected to the 1_3 terminal; the other end of the resistor R21 is grounded.

5. The compressor stall protection circuit based on real-time current monitoring according to claim 1, characterized in that: The protection unit also includes several resistors, one end of the resistor R16 among the several resistors is connected to one end of the resistor R17 and the Y pin of the multiplier A1, and the other end and one end of the resistor R18 are connected to the power supply; the other end of the resistor R18 is connected to the non-inverting end of the operational amplifier U6 and one end of the resistor R19; the other end of the resistor R17 and the other end of the resistor R19 are grounded.

6. The compressor stall protection circuit based on real-time current monitoring according to claim 5, characterized in that: The control unit further includes a plurality of resistors, one end of the resistor R23 of the plurality of resistors is connected to the power supply, and the other end is connected to the inverting end of the operational amplifier U8 and one end of the resistor R24; the other end of the resistor R24 ​​is grounded.

7. An integrated system, characterized in that: Including a compressor stall protection circuit based on real-time current monitoring as described in any one of Claims 1 to 7.

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