A compressor stall protection circuit and integrated system based on real-time current monitoring

Abstract

The application discloses a compressor stall protection circuit and integrated system based on real-time current monitoring, which comprises a protection unit and a control unit. After inputting a compressor current sampling signal 1_1, the protection unit generates a configuration signal 2_1 corresponding to a current power supply system to the control unit for comparison detection, and feeds back a disable signal 1_4 or a common current limiting protection signal 1_3 to disable or enable the compressor. The protection unit comprises several operational amplifiers, several resistors and a multiplier. An operational amplifier U3 in the several operational amplifiers is connected to the output end of an operational amplifier U5 and one end of a resistor R13 in a same-phase mode, connected to one end of a resistor R7 in an opposite-phase mode, connected to the other end of the resistor R7 and the 2_1 end in an output mode. An operational amplifier U4 is connected to one end of a resistor R15 in a same-phase mode, connected to one end of a resistor R8, one end of a resistor R9 and one end of a resistor R10 in an opposite-phase mode, and connected to the X pin of the multiplier A1 and one end of a resistor R11 in an output mode. An operational amplifier U5 is connected to one end of a resistor R14 in a same-phase mode, connected to the other end of the resistor R11 and the other end of the resistor R13 in an opposite-phase mode.

Description

Technical Field

[0001] This invention relates to the field of compressor technology, and in particular to a compressor stall protection circuit and integrated system based on real-time current monitoring. Background Technology

[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 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 fixed ratio current transformer will bring obvious compatibility problems. The wider the system's compatibility range, the lower the effective value of the actual power supply protection capacity. The conventional approach is to replace the current transformer with a different ratio, but this method has two main limitations: on the one hand, the range of selectable ratios is limited by the transformer model and specifications; on the other hand, when compressors with different power are used in combination, cross-influence will lead to a further reduction in the actual protection capacity. Summary of the Invention

[0003] To address the aforementioned technical problems, the purpose of this 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. The protection unit receives a compressor current sampling signal 1_1 and generates a configuration signal 2_1 corresponding to the current power supply system, which is then compared and detected by the control unit. The protection unit then feeds back a start-prohibition signal 1_4 or a shared current-limiting protection signal 1_3 to prevent the compressor from starting. The protection unit includes several operational amplifiers, several resistors, and a multiplier. Among the operational amplifiers, the non-inverting input of operational amplifier U3 is connected to the output terminal of operational amplifier U5 and one end of resistor R13, while its inverting input is connected to one end of resistor R7. The output terminal... Connect the other end of resistor R7 and terminal 2_1; connect the non-inverting input of op-amp U4 to one end of resistor R15, the inverting input to one end of resistor R8, one end of resistor R9, and one end of resistor R10, and connect the output terminal to the X pin of multiplier A1 and one end of resistor R11; connect the non-inverting input of op-amp U5 to one end of resistor R14, the inverting input to the other end of resistor R11 and the other end of resistor R13; connect the inverting input of op-amp U6 to one end of resistor R20, and connect the output terminal to one end of resistor R9 and the other end of resistor R20; connect the output terminal of multiplier A1 to the other end of resistor R8; connect the other end of resistor R10 to terminal 1_1; and ground the other ends of resistors R14 and R15.

[0004] Furthermore, the control unit includes a processor. After receiving the 2_1 signal from the protection unit, the processor performs calculations and compares them with the power supply protection threshold reference signal to detect the compressor that has not started at the corresponding workstation. After exceeding the power supply protection threshold reference signal, the processor feeds back the start-prohibition signal 1_4 for the corresponding workstation to control the compressor to stop starting.

[0005] Furthermore, the protection unit also includes several operational amplifiers, several diodes, several resistors, and a field-effect transistor (FET). The FET is Q1, whose source receives a common current-limiting protection signal 1_3 and generates a corresponding start-stop signal 1_4 to control the compressor to stop starting. The non-inverting input of operational amplifier U1 is connected to the cathodes of diodes D1 and D2, one end of resistor R4, and one end of resistor R6. The inverting input is connected to one end of resistor R2, one end of resistor R3, and input 1_2. The output is connected to the gate of FET Q1 and the anode of diode D2. The non-inverting input of operational amplifier U2 is connected to input 1_1. The inverting input is connected to one end of resistor R5 and one end of resistor R12. The output is connected to the anode of diode D1. The drain of FET Q1 is connected to one end of resistor R1 and input 1_4. The other ends of resistors R3, R6, and R12 are connected to the power supply. The other ends of resistors R1, R2, R4, and R5 are grounded.

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

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

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

[0009] Furthermore, an integrated system includes the compressor stall protection circuit based on real-time current monitoring as described in any of the preceding claims.

[0010] The advantages of this invention compared to the prior art are:

[0011] This invention can generate corresponding configuration sampling signals according to different power supply systems to prevent the effective value of protection capacity from decreasing. It also provides an integrated control method that can be used after physical connection without occupying processor pins or changing the program when adding or removing workstations. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

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

[0014] Figure 3 The circuit structure diagram of the control unit provided by the present invention. Detailed Implementation

[0015] To make the objectives and advantages of the present invention clearer, the present invention will be specifically described below in conjunction with embodiments. It should be understood that the following text is only used to describe one or more specific embodiments of the present invention and does not strictly limit the scope of protection specifically claimed by the present invention.

[0016] This invention discloses a compressor stall protection circuit and integrated system based on real-time current monitoring, including a protection unit and a control unit. The protection unit receives a compressor current sampling signal 1_1 and generates a configuration signal 2_1 corresponding to the current power supply system, which is then compared and detected by the control unit. The protection unit then feeds back a start-prohibition signal 1_4 or a shared current-limiting protection signal 1_3 to prevent the compressor from starting. The protection unit includes several operational amplifiers, several resistors, and a multiplier. Among the operational amplifiers, the non-inverting input of operational amplifier U3 is connected to the output terminal of operational amplifier U5 and one end of resistor R13, the inverting input is connected to one end of resistor R7, and the output terminal is connected to another end of resistor R7. One end, 2_1 end; the non-inverting input of op-amp U4 is connected to one end of resistor R15, the inverting input is connected to one end of resistor R8, one end of resistor R9, and one end of resistor R10, and the output is connected to the X pin of multiplier A1 and one end of resistor R11; the non-inverting input of op-amp U5 is connected to one end of resistor R14, and the inverting input is connected to the other end of resistor R11 and the other end of resistor R13; the inverting input of op-amp U6 is connected to one end of resistor R20, and the output is connected to one end of resistor R9 and the other end of resistor R20; the output of multiplier A1 is connected to the other end of resistor R8; the other end of resistor R10 is connected to 1_1 end; the other ends of resistor R14 and resistor R15 are grounded.

[0017] Specifically, the control unit includes a processor. After receiving the 2_1 signal from the protection unit, the processor performs calculations and compares them with the power supply protection threshold reference signal to detect the compressor that has not started at the corresponding workstation. After exceeding the power supply protection threshold reference signal, the processor feeds back the start-prohibition signal 1_4 for the corresponding workstation to control the compressor to stop starting.

[0018] Specifically, the protection unit further includes several operational amplifiers, several diodes, several resistors, and a field-effect transistor (FET). The FET is Q1, whose source receives a shared current-limiting protection signal 1_3 and generates a corresponding start-stop signal 1_4 to control the compressor to stop starting. The non-inverting input of operational amplifier U1 is connected to the cathodes of diodes D1 and D2, one end of resistor R4, and one end of resistor R6. The inverting input is connected to one end of resistor R2, one end of resistor R3, and input 1_2. The output is connected to the gate of FET Q1 and the anode of diode D2. The non-inverting input of operational amplifier U2 is connected to input 1_1. The inverting input is connected to one end of resistor R5 and one end of resistor R12. The output is connected to the anode of diode D1. The drain of FET Q1 is connected to one end of resistor R1 and input 1_4. The other ends of resistors R3, R6, and R12 are connected to the power supply. The other ends of resistors R1, R2, R4, and R5 are grounded.

[0019] Specifically, the protection unit further includes a resistor, with one end of resistor R25 connected to terminal 2_1 and the other end connected to terminal 3_1; the control unit includes several operational amplifiers and several resistors, with the non-inverting input of operational amplifier U7 connected to terminal 3_1, the inverting input connected to one end of resistor R21 and one end of resistor R22, and the output terminal connected to the non-inverting input of operational amplifier U8 and the other end of resistor R22; the output terminal of operational amplifier U8 is connected to terminal 1_3; and the other end of resistor R21 is grounded.

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

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

[0022] Specifically, an integrated system includes a compressor stall protection circuit based on real-time current monitoring as described in any of the above claims.

[0023] In the attached diagram, 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 start-stop signal, and 3_1 represents the actual power supply current sampling signal. The protection circuit consists of protection units corresponding to the number of compressor stations and a control unit. The 1_1 signal of each protection unit is input by a current transformer with the same ratio. In the two output forms, the 0-10V output is directly fed back to 1_1, while the 4-20mA output requires a series conversion circuit before being fed back to 1_1. The conversion circuit is not shown in the attached diagram. The protection unit is powered by 12V. Taking a transformation ratio of 1:100 and an initial current limit of 1000A as an example, assuming the compressor at one workstation starts and the current is 100A, a 1V current sampling signal is fed back to the inverting input of op-amp U4 via resistor R10. After inversion, op-amp U4's output is fed back to the X pin of multiplier A1. The Y pin of multiplier A1 is set with a compatible configuration voltage reference signal by resistors R16 and R17. In the above example, resistor R17 is 2K and resistor R16 is 10K. When resistor R16 is not reduced, the voltage at the end of resistor R17 is 2V. The product of multiplier A1 will be fed back to the inverting input of op-amp U4 via resistor R8, while the non-inverting input of op-amp U6 is fed back via resistor R18 and resistor R17. R19 is set to the compatible configuration voltage reference signal, where the resistance of R19 is 1K and the resistance of R18 is 11K. When the resistance of R18 is not reduced, the non-inverting input of op-amp U6 is 1V. At this time, op-amp U6, after negative feedback through resistor R20, will be input to the inverting input of op-amp U4 through resistor R9 before outputting. The output signal of op-amp U4 is input to the inverting input of op-amp U5 through resistor R11. Op-amp U5 will then be fed back to its output through resistor R13 and inverted again to obtain the 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 op-amp U3 and resistor R7. Assuming the current limit is changed to 1250A, the same operating position is maintained. The compressor and current are sampled. The compressor current sampling signal 1_1 and the non-inverting input of op-amp U6 remain unchanged. After reducing the resistance of resistor R16 to about 7.56, op-amp U4 outputs 0.8V after a 100A input. Conversely, for downward compatibility, the resistance of resistor R18 is reduced to complete the corresponding output configuration. This method can reduce the attenuation to the millivolt level compared with the method of using the transformer ratio difference for upward and downward compatibility. In this embodiment, the 2_1 feedback signal of each protection unit is processed by the processor and compared with the power supply protection threshold reference signal to detect the compressor that has not started in the corresponding station. After exceeding the power supply protection threshold reference signal, the 1_4 signal of the corresponding station is fed back to control the start-stop function.

[0024] In one embodiment, an integrated control method is provided. Compared to the method of using a processor to detect and control the parameters of multiple protection units 2_1 and disable the corresponding workstations, this method avoids occupying processor pins and changing the program when adding or removing workstations. After physical connection, only the corresponding protection unit feeds back the 1_4 signal to complete the detection and control of disabling the workstations. During integration, the protection units are packaged according to the number of control bits, the control unit is packaged separately, and the connection at 3_1 is made through a header. The parallel connection of 1_3 is made through a jumper. The compressor current sampling signal 1_1 is first fed back to the non-inverting input of the operational amplifier U2. The inverting input of the operational amplifier U2 is set with a sampling reference signal. After the compressor starts, the output signal of the operational amplifier U2 is fed back through diode D1 to The non-inverting and inverting inputs of op-amp U1 are initially set with different start-up reference signals. Upon power-up, the voltage across resistors R6 and R4 is less than the voltage across resistors R3 and R2. After op-amp U2 outputs, resistor R4 pulls up the voltage at the non-inverting input of op-amp U1. The output signal of op-amp U1 is fed back to the non-inverting input via diode D2, and output to the gate of MOSFET Q1, causing Q1 to be cut off. Simultaneously, the 2_1 signal of each protection unit is input to op-amp U7 via the corresponding resistor R25 and 3_1 in parallel. The output of op-amp U7 is fed back to the inverting input via resistor R22, and then the actual power supply current sampling signal 3_1 is superimposed and input to op-amp U8. The inverting input of op-amp U8 sets a protection threshold percentage reference voltage signal. When the threshold is exceeded, op-amp U8 compares the voltages at the non-inverting and inverting inputs and outputs signal 1_3 to the source of MOSFET Q1. Each station, upon receiving signal 1_3 and without input to the gate of MOSFET Q1, feeds back signal 1_4 to the corresponding station for start / stop. Signal 1_4 is uninterrupted. After the compressor at the corresponding station completes its detection, it inputs a signal to protection unit 1_2. If the voltage potential at the inverting input of op-amp U1 is greater than the voltage at the non-inverting input of op-amp U1 fed back through diode D2, op-amp U1 is turned off or outputs an offset voltage. If this voltage is greater than the negative voltage conduction threshold from the gate to the source of MOSFET Q1, MOSFET Q1 conducts. Signal 1_3 is fed back to 1_4. The control of 1_4 can be disconnected by connecting the main contactor coil through the relay auxiliary contact, or completely disabled by using an isolating switch. The relay and contactor are not shown in the attached diagram. After comparison by operational amplifier U8, the current limiting protection signal 1_3 is cut off. Operational amplifier U6 and multiplier A1 can be controlled by the corresponding voltage divider input or by the power supply input, as long as the corresponding voltage is satisfied after the above regulation. In addition to full integration, multiple start / stop signals 1_4 corresponding to the corresponding workstation can be replaced by a common current limiting protection signal 1_3 after being fed back to the processor by 2_1 for detection. In this case, 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 implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the 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 the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A compressor stall protection circuit based on real-time current monitoring, characterized in that, The system includes a protection unit and a control unit. The protection unit receives a compressor current sampling signal 1_1 and generates a configuration signal 2_1 corresponding to the current power supply system. This signal is then sent to the control unit for comparison and detection. The protection unit also feeds back a start-prohibition signal 1_4 or a shared current-limiting protection signal 1_3 to prevent the compressor from starting. In the protection unit, the non-inverting input of operational amplifier U3 is connected to the output of operational amplifier U5 and one end of resistor R13, the inverting input is connected to one end of resistor R7, and the output is connected to the other end of resistor R7 and terminal 2_1. Operational amplifier U4 has its non-inverting input connected to one end of resistor R15, and its inverting input connected to one end of resistor R8 and... One end of resistor R9 and one end of resistor R10 are connected to the output terminal of multiplier A1 and one end of resistor R11; the non-inverting input of operational amplifier U5 is connected to one end of resistor R14, and the inverting input is connected to the other end of resistor R11 and the other end of resistor R13; the inverting input of operational amplifier 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 I-I; the other ends of resistor R14 and the other end of resistor R15 are grounded; the protection unit also includes a field-effect transistor Q1, the field-effect transistor... The source of the field-effect transistor Q1 receives the shared current limiting protection signal 1_3 and generates the corresponding start-prevention signal 1_4 to control the compressor to prevent it from starting. The non-inverting input of operational amplifier U1 is connected to the cathodes of diodes D1 and D2, one end of resistor R4, and one end of resistor R6; the inverting input is connected to one end of resistor R2, one end of resistor R3, and terminal 1_2; the output terminal is connected to the gate of field-effect transistor Q1 and the anode of diode D2. The non-inverting input of operational amplifier U2 is connected to terminal 1_1; the inverting input is connected to one end of resistor R5 and one end of resistor R12; the output terminal is connected to the anode of diode D1. The drain of field-effect transistor Q1 is connected to... One end of resistor R1 and ends 1-4; the other ends of resistors R3, R6, and R12 are connected to the power supply, and the other ends of resistors R1, R2, R4, and R5 are grounded; the control unit includes a processor, which receives the 2_1 signal from the protection unit, performs calculations, compares it with the power supply protection threshold reference signal, detects the compressor that has not started at the corresponding workstation, and feeds back the start-prohibition signal 1_4 for the corresponding workstation to prevent the compressor from starting after the power supply protection threshold reference signal is exceeded.

2. 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 R25, one end of which is connected to terminal 2_1 and the other end of which is connected to terminal 3_1; the non-inverting input of the operational amplifier U7 in the control unit is connected to terminal 3_1, the inverting input is connected to one end of resistor R21 and one end of resistor R22, and the output is connected to the non-inverting input of operational amplifier U8 and the other end of resistor R22; the output of operational amplifier U8 is connected to terminal 1_3; and the other end of resistor R21 is grounded.

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

4. The compressor stall protection circuit based on real-time current monitoring according to claim 3, characterized in that, In the control unit, one end of resistor R23 is connected to the power supply, and the other end is connected to the inverting input of operational amplifier U8 and one end of resistor R24; the other end of resistor R24 ​​is grounded.

5. An integrated system, characterized in that, Includes a compressor stall protection circuit based on real-time current monitoring as described in any one of claims 1 to 4.

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