Protection system and protection method for a compressor

Abstract

The application relates to a protection system and a protection method of a compressor, the system comprising a control module and a voltage offset detection circuit; the voltage offset detection circuit is used for determining the voltage offset condition between any two-phase power supply in the three-phase power supply of the compressor, and sending the voltage offset condition to the control module; the control module is used for controlling the motor of the compressor according to the voltage offset condition between any two-phase power supply in the three-phase power supply of the compressor; wherein, in the case that the voltage offset condition between any two-phase power supply is a first voltage offset condition, the motor of the compressor is controlled to stop, and the first voltage offset condition is that the voltage offset degree between any two-phase power supply is greater than a first set threshold. Through the technical scheme provided by the application, the voltage offset condition of the three-phase power supply of the compressor is detected, the motor of the compressor is stopped in time when the voltage offset of the three-phase power supply occurs, and effective protection of the compressor is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of compressors, in particular to a protection system and a protection method of a compressor. BACKGROUND

[0002] A compressor is a driven fluid machine that raises low-pressure gas to high-pressure gas, and is the heart of a refrigeration system. It sucks in low-temperature and low-pressure refrigerant gas from the suction pipe, and discharges high-temperature and high-pressure refrigerant gas to the exhaust pipe after being compressed by the motor, thereby providing power for the refrigeration cycle.

[0003] When the three-phase power supply of the compressor is unbalanced, the unstable power supply of the three-phase power supply will have a certain impact on the normal operation of the compressor. If the compressor is operated under unbalanced three-phase power supply for a long time, the compressor unit will be damaged.

[0004] Therefore, it is necessary to protect the compressor unit by a certain method to prevent the compressor unit from working under unbalanced three-phase power supply for a long time. SUMMARY

[0005] The present application provides a protection system and a protection method of a compressor to protect the compressor unit and prevent the compressor unit from working under unbalanced three-phase power supply for a long time.

[0006] In a first aspect, the present application provides a protection system of a compressor, which comprises a control module and a voltage offset detection circuit.

[0007] One end of the voltage offset detection circuit is connected with the three-phase power supply of the compressor, and the other end of the voltage offset detection circuit is connected with the input end of the control module. The output end of the control module is connected with the motor of the compressor.

[0008] The voltage offset detection circuit is used to determine the voltage offset between any two-phase power supply in the three-phase power supply of the compressor, and send the voltage offset to the control module.

[0009] The control module is used to control the motor of the compressor according to the voltage offset between any two-phase power supply in the three-phase power supply of the compressor. In the case that the voltage offset between any two-phase power supply is a first voltage offset, the motor of the compressor is stopped, and the first voltage offset is that the voltage offset between any two-phase power supply is greater than a first set threshold.

[0010] In a feasible embodiment of the present application, the three-phase power supply of the compressor comprises a first-phase power supply, a second-phase power supply and a third-phase power supply, and the voltage offset detection circuit comprises a rectifier unit and a detection unit.

[0011] The rectifying unit comprises a first diode, a second diode and a third diode, and the detecting unit comprises a first relay and a second relay;

[0012] The positive electrode of the first diode is connected to the first phase power supply, and the negative electrode of the first diode is connected to the first input end of the first relay; the positive electrode of the second diode is connected to the second phase power supply, and the negative electrode of the second diode is connected to the second input end of the first relay and the first input end of the second relay respectively; the positive electrode of the third diode is connected to the third phase power supply, and the negative electrode of the third diode is connected to the second input end of the second relay;

[0013] The third input end of the first relay and the third input end of the second relay are both connected to the working power supply, and the output end of the first relay and the output end of the second relay are both connected to the input end of the control module;

[0014] The detecting unit outputs the high-low level signals outputted by the output end of the first relay and the output end of the second relay to describe the voltage offset between any two phase power supplies in the three-phase power supply.

[0015] In an available embodiment of the present application, the output end of the first relay comprises first to third output ends, and the output end of the second relay comprises fourth to sixth output ends;

[0016] When the voltage offset between the first phase power supply and the second phase power supply is greater than the first set threshold, the second output end of the first relay outputs a low level signal, and the first output end or the third output end of the first relay outputs a high level signal;

[0017] When the voltage offset between the second phase power supply and the third phase power supply is greater than the first set threshold, the fifth output end of the second relay outputs a low level signal, and the fourth output end or the sixth output end of the first relay outputs a high level signal.

[0018] In an available embodiment of the present application, the control module comprises first to eighth input ends;

[0019] The first input end of the control module is connected to the first output end of the first relay, the second input end of the control module is connected to the second output end of the first relay, and the third input end of the control module is connected to the third output end of the first relay;

[0020] A fourth input end of the control module is connected with a fourth output end of the second relay, a fifth input end of the control module is connected with a fifth output end of the second relay, and a sixth input end of the control module is connected with a sixth output end of the second relay;

[0021] A seventh input end and an eighth input end of the control module are connected with a working power supply;

[0022] In a case where a high-level signal is received at the first input end or the third input end of the control module and a low-level signal is received at the second input end, the control module determines that the voltage offset condition between the first phase power supply and the second phase power supply is the first voltage offset condition, and controls a motor of a compressor to stop running;

[0023] In a case where a high-level signal is received at the fourth input end or the sixth input end of the control module and a low-level signal is received at the fifth input end, it is determined that the voltage offset condition between the second phase power supply and the third phase power supply is the first voltage offset condition, and the motor of the compressor is controlled to stop running.

[0024] In an available embodiment of the present application, the voltage offset detection circuit further comprises a first voltage dividing unit and a second voltage dividing unit;

[0025] One end of the first voltage dividing unit is connected with the rectifying unit, the other end of the first voltage dividing unit is respectively connected with a first input end and a second input end of the first relay and a first input end and a second input end of the second relay, and the other end of the first voltage dividing unit is grounded;

[0026] One end of the second voltage dividing unit is respectively connected with an output end of the first relay and an output end of the second relay, and the other end of the second voltage dividing unit is grounded.

[0027] In an available embodiment of the present application, the voltage offset detection circuit further comprises a first current limiting resistor and a second current limiting resistor;

[0028] The first current limiting resistor is connected between the first voltage dividing unit and the first input end of the first relay, and the second current limiting resistor is connected between the first voltage dividing unit and the first input end of the second relay.

[0029] In an available embodiment of the present application, the system further comprises a current detection circuit;

[0030] One end of the current detection circuit is connected with a three-phase power supply of a compressor, and the other end of the current detection circuit is connected with the control module;

[0031] The current detection circuit is configured to detect current values of each phase of the three-phase power supply of the compressor, and send the current values of each phase to the control module, so that the control module calculates current deviation between any two phases according to the current values of each phase, and controls the motor of the compressor according to the current deviation between any two phases.

[0032] In an embodiment of the present application, the current detection circuit comprises a current sensing unit and an amplification unit.

[0033] The current sensing unit is connected with each phase of the three-phase power supply of the compressor, and is configured to detect current values of each phase.

[0034] One end of the amplification unit is connected with the current sensing unit, and the other end of the amplification unit is connected with the control module, and the amplification unit is configured to amplify the current values of each phase detected by the current sensing unit, and send the amplification results to the control module.

[0035] In a second aspect, the present application provides a protection method of a compressor, which is applied to the control module of the protection system of the compressor as described in any one of the embodiments of the first aspect, and the method comprises the following steps of:

[0036] Periodically detecting the level state of each input terminal of the control module;

[0037] Determining whether the voltage deviation between any two phases is a first voltage deviation according to the level state of each input terminal of the control module;

[0038] Generating a shutdown instruction when the voltage deviation between any two phases is the first voltage deviation; wherein the shutdown instruction is configured to control the motor of the compressor connected with the control module to shut down;

[0039] Sending the shutdown instruction to the motor of the compressor connected with the control module.

[0040] In an embodiment of the present application, determining whether the voltage deviation between any two phases is a first voltage deviation according to the level state of each input terminal of the control module comprises the following steps of:

[0041] Determining that the voltage deviation between the first phase and the second phase is the first voltage deviation when the first input terminal or the third input terminal of the control module receives a high-level signal and the second input terminal receives a low-level signal;

[0042] In a case that a high level signal is received at the fourth input end or the sixth input end of the control module, and a low level signal is received at the fifth input end, it is determined that the voltage offset between the second phase power supply and the third phase power supply is the first voltage offset.

[0043] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0044] The present application provides a protection system of a compressor, which comprises a control module and a voltage offset detection circuit; one end of the voltage offset detection circuit is connected with a three-phase power supply of the compressor, the other end of the voltage offset detection circuit is connected with an input end of the control module, and an output end of the control module is connected with a motor of the compressor; the voltage offset detection circuit is used for determining a voltage offset condition between any two phase power supplies of the three-phase power supply of the compressor, and sending the voltage offset condition to the control module; the control module is used for controlling the motor of the compressor according to the voltage offset condition between any two phase power supplies of the three-phase power supply of the compressor; wherein, in a case that the voltage offset condition between any two phase power supplies is a first voltage offset condition, the motor of the compressor is controlled to stop, and the first voltage offset condition is that a voltage offset degree between any two phase power supplies is greater than a first set threshold.

[0045] Through the protection system of the compressor provided by the present application, the voltage offset condition of the three-phase power supply is detected, and the motor of the compressor is controlled based on the voltage offset condition of the three-phase power supply; in a case that the voltage offset degree between any two phase power supplies of the three-phase power supply is greater than the first set threshold, the motor of the compressor is controlled to stop in time, so as to prevent the compressor from working under unbalanced three-phase power supply, and effectively ensure the working safety of the compressor. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0048] One or more embodiments are exemplarily illustrated by pictures in the drawings corresponding thereto, and these exemplary illustrations do not constitute a limitation on the embodiments, and elements with the same reference numerals in the drawings represent similar elements, unless otherwise specified, and the drawings do not constitute a proportional limitation.

[0049] Figure 1A structural schematic diagram of a protection system of a compressor is provided for an embodiment of the present application.

[0050] Figure 2 A connection schematic diagram of a protection system of a compressor is provided for an embodiment of the present application.

[0051] Figure 3 A flow schematic diagram of a protection method of a compressor is provided for an embodiment of the present application.

[0052] Figure 4 A whole flow chart of a protection method of a compressor is provided for an embodiment of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0054] 1, control module; 2, voltage offset detection circuit; 3, current detection circuit; 21, rectification unit; 22, detection unit; 23, first voltage division unit; 24, second voltage division unit; 31, current sensing unit; 32, amplification unit;

[0055] L1, first phase power supply; L2, second phase power supply; L3, third phase power supply; T1, first current sensor; T2, second current sensor; T3, third current sensor; D1, first diode; D2, second diode; D3, third diode; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, first current limiting resistor; R8, second current limiting resistor; K1, first relay; K2, second relay; VCC, working power supply. DETAILED DESCRIPTION

[0056] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0057] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplification, the components and arrangements of the specific examples are described in the following. Of course, they are only examples and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to the numbers and / or letters in different examples. Such repetition is for the purpose of simplification and clarity, and does not indicate the relationship between the various embodiments and / or arrangements discussed.

[0058] In order to solve the technical problem that the compressor unit working under the unbalanced three-phase power supply for a long time is prone to damage in the prior art, the application provides a protection system and a protection method for a compressor, which can protect the compressor unit and prevent the compressor unit from working under the unbalanced three-phase power supply for a long time.

[0059] Figure 1 A structural schematic diagram of a protection system for a compressor provided by an embodiment of the application is shown in Figure 1 The protection system for a compressor provided by the application comprises a control module 1 and a voltage offset detection circuit 2.

[0060] One end of the voltage offset detection circuit 2 is connected to the three-phase power supply of the compressor, and the other end of the voltage offset detection circuit 2 is connected to the input end of the control module 1. The output end of the control module 1 is connected to the motor of the compressor.

[0061] The voltage offset detection circuit 2 is used to determine the voltage offset condition between any two-phase power supplies in the three-phase power supply of the compressor and send the voltage offset condition to the control module 1.

[0062] The control module 1 is used to control the motor of the compressor according to the voltage offset condition between any two-phase power supplies in the three-phase power supply of the compressor. In the case that the voltage offset condition between any two-phase power supplies is a first voltage offset condition, the motor of the compressor is stopped. The first voltage offset condition is that the voltage offset degree between any two-phase power supplies is greater than a first set threshold.

[0063] Specifically, the protection system for a compressor provided by the application can be applied to the compressor and can be arranged between the three-phase power supply of the compressor and the motor of the compressor.

[0064] The protection system for a compressor provided by the application specifically comprises the voltage offset detection circuit 2 and the control module 1. One end of the voltage offset detection circuit 2 is connected to the three-phase power supply of the compressor, and the other end of the voltage offset detection circuit 2 is connected to the control module 1. The voltage offset detection circuit 2 can determine the voltage offset condition between any two-phase power supplies in the three-phase power supply, describe the voltage offset condition through a specific signal, and send the signal to the control module 1.

[0065] The control module 1 is connected to the voltage offset detection circuit 2 and the motor of the compressor. The control module 1 is used to process the signal transmitted by the voltage offset detection circuit 2 and control the motor of the compressor.

[0066] In an embodiment of the present application, the control module 1 controls the motor of the compressor to stop in the case that the voltage offset between any two phases of the three-phase power supply is the first voltage offset condition. The first voltage offset condition refers to the case that the voltage offset between any two phases of the three-phase power supply is greater than the first set threshold.

[0067] In an embodiment of the present application, the control module 1 controls the motor of the compressor to stop in the case that the voltage offset between any two phases of the three-phase power supply is the second voltage offset condition. The second voltage offset condition refers to the case that the voltage offset between any two phases of the three-phase power supply is less than or equal to the first set threshold and greater than the second set threshold.

[0068] In an embodiment of the present application, the first set threshold can be set to 5%, and the second set threshold can be set to 1%.

[0069] In an embodiment of the present application, the voltage offset detection circuit 2 generates a first control signal after determining that the voltage offset between any two phases of the three-phase power supply is greater than the first set threshold, the first control signal can be a digital signal with high and low level characteristics, and the first control signal is sent to the control module 1; the control module 1 analyzes the first control signal and determines that the first control signal corresponds to the first voltage offset condition, and controls the motor of the compressor to stop.

[0070] In an embodiment of the present application, the voltage offset detection circuit 2 generates a second control signal after determining that the voltage offset between any two phases of the three-phase power supply is less than or equal to the first set threshold and greater than the second set threshold, and the second control signal is sent to the control module 1; the control module 1 analyzes the second control signal and controls the motor of the compressor to continue running.

[0071] Figure 2 A connection diagram of a protection system of a compressor according to an embodiment of the present application is shown in FIG. 1. As shown in FIG. 1, the protection system of the compressor includes a voltage offset detection circuit 2 and a control module 1. Figure 2 In an embodiment of the present application, the three-phase power supply of the compressor includes a first phase power supply L1, a second phase power supply L2, and a third phase power supply L3, and the voltage offset detection circuit 2 includes a rectifier unit 21 and a detection unit 22.

[0072] The rectifier unit 21 includes a first diode D1, a second diode D2, and a third diode D3, and the detection unit 22 includes a first relay K1 and a second relay K2.

[0073] The positive electrode of the first diode D1 is connected to the first phase power supply L1, and the negative electrode of the first diode D1 is connected to the first input end of the first relay K1; the positive electrode of the second diode D2 is connected to the second phase power supply L2, and the negative electrode of the second diode D2 is connected to the second input end of the first relay K1 and the first input end of the second relay K2 respectively; the positive electrode of the third diode D3 is connected to the third phase power supply L3, and the negative electrode of the third diode D3 is connected to the second input end of the second relay K2.

[0074] The third input end of the first relay K1 and the third input end of the second relay K2 are both connected to the working power supply VCC, and the output end of the first relay K1 and the output end of the second relay K2 are both connected to the input end of the control module 1.

[0075] The detection unit 22 describes the voltage offset between any two phase power supplies in the three-phase power supply through the high and low level signals output by the output end of the first relay K1 and the output end of the second relay K2.

[0076] Specifically, any one phase power supply of the three-phase power supply is connected with the rectifier unit 21. Specifically, the first diode D1 is connected to the first phase power supply L1, the second diode D2 is connected to the second phase power supply L2, and the third diode D3 is connected to the third phase power supply L3. The first diode D1, the second diode D2 and the third diode D3 are used for rectifying the output of the three-phase power supply.

[0077] The output of the three-phase power supply flows to the detection unit 22 after being rectified. The detection unit 22 specifically includes the first relay K1 and the second relay K2. Referring to Figure 2 , the first relay K1 and the second relay K2 have the same structure and are both composed of a coil and a movable switch.

[0078] For the first relay K1, one end of the coil is connected to the first phase power supply L1, the other end of the coil is connected to the second phase power supply L2, one end of the movable switch is connected to the working power supply VCC, and the other end of the movable switch is connected to the control module 1. In the first relay K1, when there is a voltage value between the two ends of the coil, the movable switch is actuated under the action of the coil, changing the connection circuit of the relay. Therefore, it can be understood that when the voltage offset occurs between the first phase power supply L1 and the second phase power supply L2, the movable switch is actuated.

[0079] For the second relay K2, one end of the coil is connected to the second phase power supply L2, the other end of the coil is connected to the third phase power supply L3, one end of the movable switch is connected to the working power supply VCC, and the other end of the movable switch is connected to the control module 1. In the second relay K2, when there is a voltage value between the two ends of the coil, the movable switch is actuated under the action of the coil, and the connection circuit of the relay is changed. Therefore, it can be understood that when a voltage offset occurs between the second phase power supply L2 and the third phase power supply L3, the movable switch is actuated.

[0080] Since one end of the movable switch is connected to the working power supply VCC, when the movable switch connects any one circuit of the relay, the currently connected circuit outputs a voltage value corresponding to the working power supply VCC at the output end of the relay, that is, outputs a high level; when the movable switch connects any one circuit of the relay, the currently unconnected circuit outputs a low level at the output end of the relay.

[0081] If a voltage offset occurs between the first phase power supply L1 and the third phase power supply L3, a voltage offset occurs between the first phase power supply L1 and the second phase power supply L2 or between the second phase power supply L2 and the third phase power supply L3, and the first relay K1 or the second relay K2 will also output a specific high-low level signal at the output end.

[0082] In summary, the high-low level signals output at the output ends of the first relay K1 and the second relay K2 can describe the voltage offset between any two phase power supplies.

[0083] Through the above embodiment, the voltage offset between any two phase power supplies is converted into a specific high-low level signal output at the output end of the detection unit 22, and different high-low level signals can determine the voltage offset of the current three-phase power supply.

[0084] Continuing to refer to Figure 2 In an embodiment of the present application, the output end of the first relay K1 includes first to third output ends, and the output end of the second relay K2 includes fourth to sixth output ends.

[0085] In the case where the voltage offset between the first phase power supply L1 and the second phase power supply L2 is greater than the first set threshold, the second output end of the first relay K1 outputs a low level signal, and the first output end or the third output end of the first relay K1 outputs a high level signal.

[0086] In the case where the voltage offset between the second phase power supply L2 and the third phase power supply L3 is greater than the first set threshold, the fifth output end of the second relay K2 outputs a low level signal, and the fourth output end or the sixth output end of the first relay K1 outputs a high level signal.

[0087] Specifically, in this embodiment, the movable switch in the first relay K1 and the second relay K2 is a single-pole three-throw switch, the fixed end of the single-pole three-throw switch (i.e., the third input end of the first relay K1 and the second relay K2) is connected with the working power supply VCC, and the three movable ends of the single-pole three-throw switch are used as the first to third output ends of the first relay K1 in the first relay K1 and are used as the fourth to sixth output ends of the first relay K1 in the second relay K2.

[0088] With reference to the foregoing description, the first relay K1 and the second relay K2 are used to detect the voltage offset between the three-phase power supply. Figure 2 In the case where the voltage offset between the first phase power supply L1 and the second phase power supply L2 is greater than the first set threshold, the coil in the first relay K1 generates power and acts on the single-pole three-throw switch in the first relay K1, thereby changing the loop currently turned on by the first relay K1. In this embodiment, in the case where the voltage offset between the first phase power supply L1 and the second phase power supply L2 is greater than the first set threshold, the third input end in the first relay K1 is connected with the first output end or the third output end, so that the second output end of the first relay K1 outputs a low-level signal, and the first output end or the third output end of the first relay K1 outputs a high-level signal.

[0089] In the case where the voltage offset between the second phase power supply L2 and the third phase power supply L3 is greater than the first set threshold, the coil in the second relay K2 generates power and acts on the single-pole three-throw switch in the second relay K2, thereby changing the loop currently turned on by the second relay K2. In this embodiment, in the case where the voltage offset between the second phase power supply L2 and the third phase power supply L3 is greater than the first set threshold, the third input end in the second relay K2 is connected with the fourth output end or the sixth output end, so that the fifth output end of the first relay K1 outputs a low-level signal, and the fourth output end or the sixth output end of the second relay K2 outputs a high-level signal.

[0090] In a feasible embodiment of the present application, if there is no power supply offset between any two phase power supplies of the three-phase power supply, the third input end of the first relay K1 is connected with the second output end, the first relay K1 outputs a high-level signal at the second output end and a low-level signal at the first output end and the third output end; and the third input end of the second relay K2 is connected with the fifth output end, the first relay K1 outputs a high-level signal at the fifth output end and a low-level signal at the fourth output end and the sixth output end.

[0091] In an embodiment of the application, the first and second set threshold values can be changed by changing the working voltage of the coils in the first and second relays K1 and K2. For example, if the first set threshold value is 5%, and the input voltage of the three-phase power supply is 380VAC, and the voltage offset between any two phases is ±5%, i.e. ±19VAC, the working voltage of the coils in the first and second relays K1 and K2 can be set to 19VAC. When the voltage across the coils in the first and second relays K1 and K2 reaches 19VAC, the coils control the movable switch to act, i.e. when the voltage offset between any two phases reaches 5%, the high and low level signals output by the first and second relays K1 and K2 at the output end are changed.

[0092] With reference to the foregoing description Figure 2 In an embodiment of the application, the control module 1 comprises first to eighth input ends;

[0093] The first input end of the control module 1 is connected with the first output end of the first relay K1, the second input end of the control module 1 is connected with the second output end of the first relay K1, and the third input end of the control module 1 is connected with the third output end of the first relay K1.

[0094] The fourth input end of the control module 1 is connected with the fourth output end of the second relay K2, the fifth input end of the control module 1 is connected with the fifth output end of the second relay K2, and the sixth input end of the control module 1 is connected with the sixth output end of the second relay K2.

[0095] The seventh and eighth input ends of the control module 1 are connected with the working power supply VCC.

[0096] When the first or third input end of the control module 1 receives a high level signal and the second input end receives a low level signal, the control module 1 determines that the voltage offset between the first and second phase power supplies L1 and L2 is the first voltage offset condition, and controls the motor of the compressor to stop.

[0097] When the fourth or sixth input end of the control module 1 receives a high level signal and the fifth input end receives a low level signal, it is determined that the voltage offset between the second and third phase power supplies L2 and L3 is the first voltage offset condition, and the motor of the compressor is controlled to stop.

[0098] Specifically, in the above embodiment, when the voltage offset occurs between any two phase power supplies, the detection unit 22 outputs different high and low level signals at the output end, and therefore, when the input end of the control module 1 is connected with the output end of the detection unit 22, the control module 1 can also determine the voltage offset condition between any two phase power supplies based on the level of the signals received at the input end.

[0099] The first input end of the control module 1 is connected with the first output end of the first relay K1, the second input end of the control module 1 is connected with the second output end of the first relay K1, the third input end of the control module 1 is connected with the third output end of the first relay K1, the fourth input end of the control module 1 is connected with the fourth output end of the second relay K2, the fifth input end of the control module 1 is connected with the fifth output end of the second relay K2, the sixth input end of the control module 1 is connected with the sixth output end of the second relay K2, based on the above connection mode, the control module 1 recognizes the current high and low levels of the first to sixth input ends, and can determine the voltage offset between any two phase power supplies.

[0100] For example, in the case that the first input end or the third input end of the control module 1 receives a high level signal and other input ends receive low level signals, it can be considered that the voltage offset between the first phase power supply L1 and the second phase power supply L2 is the first voltage offset, that is, the voltage offset degree between the first phase power supply L1 and the second phase power supply L2 is greater than the first set threshold.

[0101] For another example, in the case that the fourth input end or the sixth input end of the control module 1 receives a high level signal and other input ends receive low level signals, it can be considered that the voltage offset between the second phase power supply L2 and the third phase power supply L3 is the first voltage offset, that is, the voltage offset degree between the second phase power supply L2 and the third phase power supply L3 is greater than the first set threshold.

[0102] In a feasible embodiment of the present application, the control module 1 can also determine the voltage offset between any two phase power supplies according to the level high and low changes before and after each input end.

[0103] Taking the first relay K1 as an example, the movable switch of the first relay K1 is arranged to connect the third input end and the second output end of the first relay K1 when the three-phase power supply is normally running, so that the second input end of the control module 1 receives a high level when the three-phase power supply is normally running. If the control module 1 detects that the second input end of the control module 1 changes from high level to low level, and the first input end or the third input end changes from low level to high level, it can be known that the current connection state of the first relay K1 changes, at this time, the coil in the first relay K1 makes the third input end of the first relay K1 connected with the first output end of the first relay K1, or makes the third input end of the first relay K1 connected with the third output end of the first relay K1, the coil of the first relay K1 is working, that is, it can be considered that there is a voltage offset between the first phase power supply L1 and the second phase power supply L2.

[0104] In a feasible embodiment of the present application, after the control module 1 determines that the voltage offset between any two phases of the three-phase power supply is the first voltage offset, a shutdown instruction is generated and sent to the motor of the compressor, so that the motor of the compressor is shut down under the action of the shutdown instruction.

[0105] The seventh input end and the eighth input end of the control module 1 are connected with the working power supply VCC, and based on the above connection mode, the working power supply VCC provides working voltage for the control module 1.

[0106] Based on the above various embodiments, the present application provides an implementation principle of a protection system of a compressor:

[0107] When the voltage offset occurs in any two phases of the three-phase power supply, the coil of the first relay K1 or the second relay K2 starts to work, changes the on-off state of the movable switch of the first relay K1 or the second relay K2, and thus changes the high-low level state of the output end of the first relay K1 and the second relay K2. The first relay K1 or the second relay K2 sends different high-low level signals to the control module 1, and the control module 1 identifies that the voltage offset occurs in any two phases of the three-phase power supply according to the received high-low level signals, and controls the motor of the compressor to shut down.

[0108] Continuing to refer to Figure 2 In a feasible embodiment of the present application, the voltage offset detection circuit 2 further includes a first voltage dividing unit 23 and a second voltage dividing unit 24.

[0109] One end of the first voltage dividing unit 23 is connected with the rectifying unit 21, the other end of the first voltage dividing unit 23 is respectively connected with the first input end and the second input end of the first relay K1 and the first input end and the second input end of the second relay K2, and the other end of the first voltage dividing unit 23 is grounded.

[0110] One end of the second voltage dividing unit 24 is respectively connected with the output end of the first relay K1 and the output end of the second relay K2, and the other end of the second voltage dividing unit 24 is grounded.

[0111] Specifically, the first voltage dividing unit 23 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6, wherein the first resistor R1 and the fourth resistor R4 are connected to the first-phase power supply L1, the second resistor R2 and the fifth resistor R5 are connected to the second-phase power supply L2, and the third resistor R3 and the sixth resistor R6 are connected to the third-phase power supply L3.

[0112] The first input end of the first relay K1 is connected between the first resistor R1 and the fourth resistor R4, the second input end of the first relay K1 is connected between the second resistor R2 and the fifth resistor R5, the first input end of the second relay K2 is connected between the second resistor R2 and the fifth resistor R5, and the second input end of the second relay K2 is connected between the third resistor R3 and the sixth resistor R6.

[0113] The voltage value input into the first relay K1 and the second relay K2 is reduced through the voltage division of the first voltage division unit 23, so as to prevent the first relay K1 and the second relay K2 from being damaged due to a large voltage.

[0114] The second voltage division unit 24 includes a plurality of voltage division resistors, and the voltage value input into the control module 1 is reduced through the voltage division of the second voltage division unit 24, so as to prevent the control module 1 from being damaged due to a large voltage.

[0115] The first voltage division unit 23 and the second voltage division unit 24 are arranged to ensure the reliability of the voltage offset detection circuit 2, and further ensure the reliability of the protection system of the compressor.

[0116] Continuing to refer to Figure 2 In an embodiment of the present application, the voltage offset detection circuit 2 further includes a first current limiting resistor R7 and a second current limiting resistor R8.

[0117] The first current limiting resistor R7 is connected between the first voltage division unit 23 and the first input end of the first relay K1, and the second current limiting resistor R8 is connected between the first voltage division unit 23 and the first input end of the second relay K2.

[0118] Specifically, the first current limiting resistor and the second current limiting resistor are used for current limiting, so as to prevent a large current impact from occurring in the voltage offset detection circuit 2, and damage the components in the circuit, and further ensure the reliability of the voltage offset detection circuit 2.

[0119] In order to comprehensively detect the three-phase power supply, so as to provide more comprehensive protection for the compressor, referring to Figure 1 In an embodiment of the present application, the system further includes a current detection circuit 3.

[0120] One end of the current detection circuit 3 is connected with the three-phase power supply of the compressor, and the other end of the current detection circuit 3 is connected with the control module 1.

[0121] The current detection circuit 3 is configured to detect the current value of each phase of the three-phase power supply of the compressor, and send the current value of each phase to the control module 1, so that the control module 1 calculates the current deviation between any two phases according to the current value of each phase, and controls the motor of the compressor according to the current deviation between any two phases.

[0122] Specifically, the current value of the three-phase power supply is detected, and the working state of the three-phase power supply is further determined based on the current value of each phase of the three-phase power supply.

[0123] In an embodiment of the present application, the current detection circuit 3 detects the current value of each phase of the three-phase power supply, and the control module 1 can determine whether the compressor is currently in a current imbalance state (i.e., the current value of any two phases is significantly different) based on the current value sent by the current detection circuit 3.

[0124] When the compressor is currently in a current imbalance state, the current imbalance degree of any two phases is calculated, and when the current imbalance degree of any two phases is greater than a second set threshold, it is considered that the compressor currently needs to be stopped, and the motor of the compressor is controlled to stop.

[0125] Reference Figure 2 In an embodiment of the present application, the current detection circuit 3 includes a current sensing unit 31 and an amplification unit 32.

[0126] The current sensing unit 31 is connected to each phase of the three-phase power supply of the compressor, and is configured to detect the current value of each phase.

[0127] One end of the amplification unit 32 is connected to the current sensing unit 31, and the other end of the amplification unit 32 is connected to the control module 1, and is configured to amplify the current value of each phase detected by the current sensing unit 31, and send the amplification result to the control module 1.

[0128] Specifically, the current sensing unit 31 includes a first current sensor T1, a second current sensor T2, and a third current sensor T3, the first current sensor T1 is arranged on the first phase current, the second current sensor T2 is arranged on the second phase power supply L2, and the third current sensor T3 is arranged on the third phase power supply L3.

[0129] The first current sensor T1, the second current sensor T2, and the third current sensor T3 respectively detect the current value when the first phase power supply L1, the second phase power supply L2, and the third phase power supply L3 work, and transmit the detected current value to the amplification unit 32.

[0130] The amplification unit 32 is configured to amplify the current value of each phase power detected by the current sensing unit 31 and send the amplified result to the control module 1. In some possible embodiments of the present application, the amplification unit 32 can be an amplification circuit. The specific connection mode of the amplification unit 32 and the related components can be set by those skilled in the art according to the amplification requirement, which is not described here.

[0131] The protection system of the compressor provided in the present application can detect the voltage offset condition of the three-phase power supply and control the motor of the compressor based on the voltage offset condition of the three-phase power supply. In the case that the voltage offset degree between any two phase power supplies is greater than the first set threshold, the motor of the compressor is controlled to stop working in time, so as to prevent the compressor from working under the unbalanced three-phase power supply, and effectively ensure the working safety of the compressor.

[0132] Figure 3 The method flowchart of the protection method of the compressor provided in the present application, the protection method of the compressor provided in the present application can be applied to the control module 1 in any one of the above embodiments. The method specifically includes the following steps:

[0133] S01: periodically detecting the level state of each input end of the control module 1;

[0134] S02: determining whether the voltage offset condition between any two phase power supplies is the first voltage offset condition according to the level state of each input end of the control module 1;

[0135] S03: generating a stop working instruction in the case that the voltage offset condition between any two phase power supplies is the first voltage offset condition; wherein the stop working instruction is used to control the motor of the compressor connected to the control module 1 to stop working;

[0136] S04: sending the stop working instruction to the motor of the compressor connected to the control module 1.

[0137] Specifically, the protection method of the compressor provided in the present application is implemented based on the protection system of the compressor described in the above embodiments. The method is specifically applied to the control module 1 of the protection system of the compressor and can be stored in the control module 1 in the form of software.

[0138] The control module 1 periodically scans each input end of the control module 1 to identify the level state of each input end of each control module 1; after determining the level state of the input end, the control module 1 determines whether the voltage offset between any two-phase power supplies is the first voltage offset according to the level state of each input end, wherein the first voltage offset is that the voltage offset between any two-phase power supplies is greater than a first set threshold; when the voltage offset between any two-phase power supplies is the first voltage offset, the control module 1 generates a shutdown instruction; and the control module 1 sends the shutdown instruction to the motor of the compressor, and the motor of the compressor stops after receiving the shutdown instruction.

[0139] In an embodiment of the present application, when determining whether the voltage offset between any two-phase power supplies is the first voltage offset according to the level state of each input end of the control module 1 in step S3, the following steps can be included:

[0140] When the first input end or the third input end of the control module 1 receives a high-level signal and the second input end receives a low-level signal, it is determined that the voltage offset between the first-phase power supply L1 and the second-phase power supply L2 is the first voltage offset;

[0141] When the fourth input end or the sixth input end of the control module 1 receives a high-level signal and the fifth input end receives a low-level signal, it is determined that the voltage offset between the second-phase power supply L2 and the third-phase power supply L3 is the first voltage offset.

[0142] Figure 4 The overall flowchart of the protection method of the compressor provided in an embodiment of the present application is described with reference to Figure 4 The overall flow of the protection method of the compressor provided in the present application is described.

[0143] In an embodiment of the present application, the protection system of the compressor includes a voltage offset detection circuit 2, a current detection circuit 3, and a control module 1. Based on this embodiment, the overall flow of the protection method of the compressor provided in the present application is as follows:

[0144] S1: The voltage detection circuit outputs a high-low level signal to the control module 1;

[0145] S2: The current detection circuit 3 outputs the current value of each phase power supply of the three-phase power supply to the control module 1;

[0146] S3: The control module 1 determines the voltage offset of any two-phase power supply in the three-phase power supply according to the received high-low level signal;

[0147] S4: The control module 1 determines the current offset of any two-phase power supply in the three-phase power supply according to the received current value;

[0148] S5: judging whether the voltage offset condition between any two phase power supplies is the second voltage offset condition? If the judging result is yes, jump to step S9; if the judging result is no, continue step S6;

[0149] S6: judging whether the voltage offset condition between any two phase power supplies is the first voltage offset condition? If the judging result is yes, jump to step S8; if the judging result is no, continue step S7;

[0150] S7: judging whether the current offset degree between any two phase power supplies is greater than the third set threshold? If the judging result is no, jump to step S9; if the judging result is yes, continue step S8;

[0151] S8: generating a shutdown instruction and sending the shutdown instruction to the motor of the compressor;

[0152] S9: not generating a shutdown instruction.

[0153] It should be noted that the second voltage offset condition is that the voltage offset degree between any two phase power supplies is greater than the second set threshold and less than or equal to the first set threshold; the first voltage offset condition is that the voltage offset degree between any two phase power supplies is greater than the first set threshold; and the third set threshold can be set by those skilled in the art according to actual conditions.

[0154] It should be understood that the terms used herein are for the purpose of describing particular example embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described unless specifically identified as an order dependent step. It is also to be understood that additional or alternative steps can be employed.

[0155] The foregoing is considered only as illustrative of the principles of the application. Numerous modifications and adaptations will be apparent to those skilled in the art in view of the above descriptions and drawings without departing from the spirit and scope thereof. Therefore, the application should not be limited to the examples contained herein but should be given the full scope of the appended claims and their equivalents.

Claims

1. A protection system for a compressor, characterized in that, The system includes a control module and a voltage offset detection circuit; One end of the voltage offset detection circuit is connected to the three-phase power supply of the compressor, the other end of the voltage offset detection circuit is connected to the input terminal of the control module, and the output terminal of the control module is connected to the motor of the compressor. The voltage offset detection circuit is used to determine the voltage offset between any two phases of the three-phase power supply of the compressor, and sends the voltage offset information to the control module. The control module is used to control the compressor motor according to the voltage deviation between any two phases of the three-phase power supply of the compressor; wherein, when the voltage deviation between any two phases is a first voltage deviation, the compressor motor is controlled to stop, and the first voltage deviation is when the voltage deviation between any two phases is greater than a first set threshold. The compressor's three-phase power supply includes a first-phase power supply, a second-phase power supply, and a third-phase power supply. The voltage deviation detection circuit includes a rectifier unit and a detection unit. The rectifier unit includes a first diode, a second diode, and a third diode; the detection unit includes a first relay and a second relay. The anode of the first diode is connected to the first phase power supply, and the cathode of the first diode is connected to the first input terminal of the first relay; the anode of the second diode is connected to the second phase power supply, and the cathode of the second diode is connected to both the second input terminal of the first relay and the first input terminal of the second relay; the anode of the third diode is connected to the third phase power supply, and the cathode of the third diode is connected to the second input terminal of the second relay. The third input terminal of the first relay and the third input terminal of the second relay are both connected to the operating power supply, and the output terminal of the first relay and the output terminal of the second relay are both connected to the input terminal of the control module. The detection unit describes the voltage deviation between any two phases of the three-phase power supply by outputting high and low level signals from the output terminals of the first and second relays.

2. The system according to claim 1, characterized in that, The first relay has a first to a third output terminal, and the second relay has a fourth to a sixth output terminal. When the voltage offset between the first phase power supply and the second phase power supply is greater than the first set threshold, the second output terminal of the first relay outputs a low-level signal, and the first output terminal or the third output terminal of the first relay outputs a high-level signal. When the voltage offset between the second phase power supply and the third phase power supply is greater than the first set threshold, the fifth output terminal of the second relay outputs a low-level signal, and the fourth or sixth output terminal of the first relay outputs a high-level signal.

3. The system according to claim 2, characterized in that, The control module includes first to eighth input terminals; The first input terminal of the control module is connected to the first output terminal of the first relay, the second input terminal of the control module is connected to the second output terminal of the first relay, and the third input terminal of the control module is connected to the third output terminal of the first relay. The fourth input terminal of the control module is connected to the fourth output terminal of the second relay, the fifth input terminal of the control module is connected to the fifth output terminal of the second relay, and the sixth input terminal of the control module is connected to the sixth output terminal of the second relay. The seventh and eighth input terminals of the control module are both connected to the power supply. When the control module receives a high-level signal at its first or third input terminal and a low-level signal at its second input terminal, the control module determines the voltage offset between the first phase power supply and the second phase power supply as the first voltage offset condition and controls the compressor motor to stop. When the control module receives a high-level signal at its fourth or sixth input terminal and a low-level signal at its fifth input terminal, it determines that the voltage offset between the second phase power supply and the third phase power supply is the first voltage offset condition, and controls the compressor motor to stop.

4. The system according to claim 1, characterized in that, The voltage offset detection circuit further includes a first voltage divider unit and a second voltage divider unit; One end of the first voltage divider unit is connected to the rectifier unit, and the other end of the first voltage divider unit is connected to the first input terminal and the second input terminal of the first relay and the first input terminal and the second input terminal of the second relay, respectively. The other end of the first voltage divider unit is grounded. One end of the second voltage divider unit is connected to the output terminal of the first relay and the output terminal of the second relay, respectively, and the other end of the second voltage divider unit is grounded.

5. The system according to claim 4, characterized in that, The voltage offset detection circuit further includes a first current-limiting resistor and a second current-limiting resistor; The first current-limiting resistor is connected between the first voltage divider unit and the first input terminal of the first relay, and the second current-limiting resistor is connected between the first voltage divider unit and the first input terminal of the second relay.

6. The system according to claim 1, characterized in that, The system also includes a current detection circuit; One end of the current detection circuit is connected to the three-phase power supply of the compressor, and the other end of the current detection circuit is connected to the control module. The current detection circuit is used to detect the current value of each phase of the three-phase power supply of the compressor, and send the current value of each phase to the control module, so that the control module can calculate the current offset between any two phases based on the current value of each phase, and control the compressor motor based on the current offset between any two phases.

7. The system according to claim 6, characterized in that, The current detection circuit includes a current sensing unit and an amplification unit; The current sensing unit is connected to each phase of the compressor's three-phase power supply and is used to detect the current value of each phase. One end of the amplification unit is connected to the current sensing unit, and the other end of the amplification unit is connected to the control module. It is used to amplify the current value of each phase power supply detected by the current sensing unit and send the amplification result to the control module.

8. A method for protecting a compressor, characterized in that, The method is applied to the control module of the compressor protection system as described in any one of claims 1-7, and the method includes: The level status of each input terminal of the control module is periodically detected; Based on the level status of each input terminal of the control module, determine whether the voltage deviation between any two phase power supplies is the first voltage deviation condition; When the voltage deviation between any two phases of the power supply is the first voltage deviation, a shutdown command is generated; wherein, the shutdown command is used to control the motor of the compressor connected to the control module to stop. The shutdown command is sent to the motor of the compressor connected to the control module.

9. The method according to claim 8, characterized in that, Determining whether the voltage deviation between any two phases of the power supply is a first voltage deviation condition based on the level states of each input terminal of the control module includes: When the control module receives a high-level signal at its first or third input terminal and a low-level signal at its second input terminal, the voltage offset between the first phase power supply and the second phase power supply is determined to be the first voltage offset condition. When the control module receives a high-level signal at its fourth or sixth input terminal and a low-level signal at its fifth input terminal, the voltage offset between the second-phase power supply and the third-phase power supply is determined to be the first voltage offset.

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