Compressor protection circuit and refrigerating unit

Abstract

The utility model discloses a compressor protection circuit and a refrigerating unit. The circuit comprises a control module, a bus output module, a first fuse, a second fuse, a power switch module, a switch starting module and a plurality of electromagnetic valve modules, the control module comprises a control unit, a first silicon controlled rectifier relay and a plurality of second silicon controlled rectifier relays; the output end of the first silicon controlled relay is electrically connected with the compressor through the first fuse and the switch starting module; the input end is electrically connected with the power switch; the output end of each second silicon controlled rectifier relay is correspondingly and electrically connected with each electromagnetic valve module; each input end is electrically connected with the power switch; the power switch module and each electromagnetic valve module are connected in series between positive and negative buses of the bus output module; the first end of the second fuse is electrically connected with the positive bus input end; the second end of the second fuse is electrically connected with the first end of the power switch module; each silicon controlled rectifier relay is electrically connected with the control unit; and the power switch module is coupled with the switch starting module.

Description

Technical Field

[0001] The present invention relates to a protection circuit, and more particularly to a compressor protection circuit and a refrigeration unit. Background Art

[0002] A compressor is a driven mechanical device that raises low-pressure gas to high-pressure gas. It is an indispensable part of refrigeration systems, air conditioning systems, and many other industrial processes. The working principle of a compressor is to increase the pressure and temperature of the gas by compressing the volume of the gas. Currently, compressor protection is an important part of ensuring the safe operation of the refrigeration system.

[0003] In the prior art, when the compressor is overloaded, breakdown may occur. When breakdown occurs, even if a compressor stop command is given, the compressor still cannot stop, eventually causing system damage. Utility Model Content

[0004] The utility model provides a compressor protection circuit and a refrigeration unit, which can ensure that the compressor stops running in the case of an overload fault, and ensure that the system can prevent a large-scale system fault due to which the compressor cannot be stopped in the case of a fault.

[0005] To achieve the above objectives, in a first aspect, the utility model provides a compressor protection circuit, which includes: a control module, a bus output module, a first fuse, a second fuse, a power switch module, a switch start module and a plurality of solenoid valve modules; the control module includes a control unit, a first thyristor relay and a plurality of second thyristor relays;

[0006] The output end of the first thyristor relay is electrically connected to the compressor through the first fuse and the switch start module; the input end of the first thyristor relay is electrically connected to the power switch; the output end of each of the second thyristor relays is electrically connected to each of the solenoid valve modules; the input end of each of the second thyristor relays is electrically connected to the power switch;

[0007] The power switch module is connected in series between the positive and negative busbars of the bus output module; each of the solenoid valve modules is connected in series between the positive and negative busbars of the bus output module; the first end of the second fuse is electrically connected to the positive bus input end of the bus output module; the second end of the second fuse is electrically connected to the first end of the power switch module; the first thyristor relay and the plurality of the second thyristor relays are electrically connected to the control unit; the power switch module is coupled to the switch start module;

[0008] Wherein, the rated current of the first fuse is less than the rated current of the first thyristor relay; and is greater than the rated current of the switch start module.

[0009] Optionally, the power switch module includes: a first intermediate relay coil and a high and low voltage switch;

[0010] The first end of the high and low voltage switch is electrically connected to the second end of the second fuse; the second end of the high and low voltage switch is electrically connected to the first end of the first intermediate relay coil; the second end of the first intermediate relay coil is electrically connected to the negative bus of the bus output module.

[0011] Optionally, the switch start module includes: a first intermediate relay normally closed switch, a second intermediate relay coil, a second intermediate relay normally closed switch, a second intermediate relay normally open switch, a first AC contactor coil, a first AC contactor normally open switch, a second AC contactor normally closed switch, a third AC contactor coil and a third AC contactor normally closed switch;

[0012] The first end of the normally closed switch of the second intermediate relay is electrically connected to the output end of the first thyristor relay; the second end of the normally closed switch of the second intermediate relay is electrically connected to the first end of the first AC contactor coil and the first end of the normally open switch of the first AC contactor; the second end of the normally open switch of the first AC contactor is electrically connected to the first end of the normally closed switch of the third AC contactor and the first end of the normally closed switch of the second AC contactor;

[0013] The second end of the normally closed switch of the third AC contactor is electrically connected to the first end of the second AC contactor coil; the second end of the normally closed switch of the second AC contactor is electrically connected to the first end of the third AC contactor coil;

[0014] The first end of the second intermediate relay normally closed switch is also electrically connected to the first end of the second intermediate relay normally open switch and the first end of the first intermediate relay normally closed switch; the second end of the second intermediate relay normally open switch and the second end of the first intermediate relay normally closed switch are both electrically connected to the first end of the second intermediate relay coil;

[0015] The second end of the second intermediate relay coil, the second end of the first AC contactor coil, the second end of the second AC contactor coil, and the second end of the third AC contactor coil are electrically connected to the negative bus of the bus output module.

[0016] Optionally, the switch start module further includes: a time relay coil, a time relay normally open switch and a time relay normally closed switch;

[0017] The second end of the normally open switch of the first AC contactor is electrically connected to the first end of the normally open switch of the time relay, the first end of the normally closed switch of the time relay, and the first end of the time relay; the second end of the normally open switch of the time relay is electrically connected to the first end of the normally closed switch of the third AC contactor; the second end of the normally closed switch of the third AC contactor is electrically connected to the first end of the second AC contactor coil;

[0018] The second end of the time relay normally closed switch is electrically connected to the first end of the second AC contactor normally closed switch; the second end of the second AC contactor normally closed switch is electrically connected to the first end of the third AC contactor coil;

[0019] The second end of the time relay coil is electrically connected to the negative bus of the bus output module.

[0020] Optionally, the first fuse includes a semiconductor protection fuse.

[0021] Optionally, the second fuse includes a semiconductor protection type fuse.

[0022] Optionally, the first AC contactor coil includes a main contactor coil; the first AC contactor normally-open switch includes a main contactor normally-open switch;

[0023] The second AC contactor coil includes a delta contactor coil; the second AC contactor normally closed switch includes a delta contactor normally closed switch;

[0024] The third AC contactor coil includes a star-connected contactor coil; the third AC contactor normally closed switch includes a star-connected contactor normally closed switch.

[0025] Optionally, the multiple solenoid valves include an ejection pump solenoid valve, an oil return solenoid valve, an SV1 loading solenoid valve and an SV2 loading solenoid valve.

[0026] In a second aspect, an embodiment of the utility model further provides a refrigeration unit, comprising the compressor protection circuit described in the first aspect.

[0027] In the embodiment of the utility model, when the control unit controls the first thyristor relay to be turned on, the current output by the positive bus of the bus output module passes through the switch start module to drive the switch start module to partially wake up; at the same time, the power switch module is turned on, and since the power switch module is coupled to the switch start module, the switch start module partially wakes up under the control instruction of the power switch module, so that the switch start module starts as a whole, thereby driving the compressor to work; if the compressor is overloaded during the operation of the compressor, the breakdown current will pass through the switch start module and enter the first thyristor relay. Since the rated current of the first fuse is less than the rated current of the first thyristor relay; and greater than the rated current of the switch start module, the first fuse will melt, and the subsequent power switch module will disconnect, thereby driving the switch start module to disconnect, thereby stopping the compressor; avoiding the breakdown current from continuing to the switch start module to enter the first thyristor relay, the switch start module cannot disconnect, and thus the compressor cannot disconnect. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a compressor protection circuit provided by an embodiment of the utility model;

[0029] Figure 2 It is a specific circuit diagram of a compressor protection circuit provided by an embodiment of the utility model;

[0030] Figure 3 It is a specific circuit diagram of another compressor protection circuit provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0032] Figure 1 This is a flow chart of a compressor protection circuit provided by an embodiment of the utility model. Figure 1 As shown, the circuit includes a control module 10, a bus output module 20, a first fuse 30, a second fuse 40, a power switch module 50, a switch start module 60 and a plurality of solenoid valve modules 70; the control module 10 includes a control unit 11, a first thyristor relay 12 and a plurality of second thyristor relays 13;

[0033] The output terminal D01 of the first thyristor relay 12 is electrically connected to the compressor P through the first fuse 30 and the switch start module 20; the input terminal C1 of the first thyristor relay 12 is electrically connected to the power switch module 40; the output terminal D02 of each second thyristor relay 13 is electrically connected to each solenoid valve module 70; the input terminal C1 of each second thyristor relay 13 is electrically connected to the power switch module 40;

[0034] The power switch module 40 is connected in series between the positive and negative buses of the bus output module 20; each solenoid valve module 70 is connected in series between the positive and negative buses of the bus output module 20; the first end of the second fuse 40 is electrically connected to the positive bus input end L of the bus output module 20; the second end of the second fuse 40 is electrically connected to the first end of the power switch module 40; the first thyristor relay 12 and the plurality of second thyristor relays 13 are electrically connected to the control unit 11; the power switch module 50 is coupled and connected to the switch start module 60;

[0035] Among them, the rated current of the first fuse 30 is less than the rated current of the first thyristor relay 12; and greater than the rated current of the switch starting module 60; the rated current of the second fuse 40 is greater than the rated current of the first thyristor relay 12 and the sum of the rated currents of multiple second thyristor relays 13.

[0036] Among them, the first fuse 30 can be a semiconductor protection type fuse. The second fuse 40 can be a semiconductor protection type fuse. The basic start-stop working principle of the compressor in this embodiment is: when the control unit 11 controls the first thyristor relay 12 to turn on, the current output by the positive bus of the bus output module 20 passes through the first fuse 30 and the switch start module 60 to drive the switch start module 60 to partially wake up and work; at the same time, the power switch module 50 is turned on. Since the power switch module 50 is coupled with the switch start module 60, the switch start module 60 partially wakes up and works under the control instruction of the power switch module 50, so that the switch start module 60 starts working as a whole, thereby driving the compressor P to work; when the compressor needs to stop working, the power switch module 50 is disconnected. Since the power switch module 50 is coupled with the switch start module 60, the switch start module 60 partially stops working under the control instruction of the power switch module 50, so that the switch start module 60 cannot start working, thereby driving the compressor P to stop working;

[0037] The start and stop working principles of the multiple solenoid valve modules 70 in this embodiment are as follows: when the control unit 11 controls the multiple second thyristor relays 13 to be turned on, the current output by the positive bus of the bus output module 20 directly passes through the solenoid valve module 70, thereby driving the solenoid valve module 70 to work; when the multiple solenoid valve modules 70 need to be disconnected, the control unit 11 controls the multiple second thyristor relays 13 to be disconnected, so that the current output by the positive bus of the bus output module 20 cannot pass through the solenoid valve module 70, thereby driving the solenoid valve module 70 to stop working; optionally, the multiple solenoid valves include an ejection pump solenoid valve, an oil return solenoid valve, an SV1 loading solenoid valve and an SV2 loading solenoid valve; this embodiment does not make specific limitations on this.

[0038] Since the compressor protection circuit includes a compressor and a multi-way solenoid valve module 70, the rated current of the second fuse 40 needs to be greater than the rated current of the first thyristor relay 12 and the sum of the rated currents of the plurality of second thyristor relays 13; in this way, if the compressor is overloaded during operation, the breakdown current will pass through the switch start module 60 and enter the first thyristor relay 12. At this time, since the rated current of the second fuse 40 is greater than the rated current of the first thyristor relay 12 and the sum of the rated currents of the plurality of second thyristor relays 13, the second fuse 40 cannot be blown; this will cause the breakdown current to continue to pass through the switch start module 60 and enter the first thyristor relay 12, and the switch start module 60 The compressor cannot be disconnected from working, and thus the compressor cannot be disconnected from working; in this embodiment, a first fuse 30 is provided, and a rated current of the first fuse 30 is less than a rated current of the first thyristor relay 12; and is greater than a rated current of the switch start module 60, so that when the compressor is overloaded during operation, the first fuse 30 melts, and a breakdown current passes through the switch start module 60 and does not enter the first thyristor relay 12. At this time, the power switch module 50 is disconnected from working, thereby driving the switch start module 60 to disconnect working, thereby shutting down the compressor P, so as to ensure that the compressor can be stopped in the event of an overload fault, and to ensure that the system can prevent a large-scale system fault due to which the compressor cannot be stopped in the event of a fault.

[0039] Optionally, based on the above embodiment, the power switch module 50 and the switch start module 60 are further refined. Figure 2 : is a specific circuit diagram of a compressor protection circuit provided by an embodiment of the utility model; Figure 2 As shown, the power switch module 50 includes: a first intermediate relay coil KA1 and a high and low voltage switch SP1;

[0040] The first end of the high and low voltage switch SP1 is electrically connected to the second end of the second fuse 40 ; the second end of the high and low voltage switch SP1 is electrically connected to the first end of the first intermediate relay coil KA1 ; the second end of the first intermediate relay coil KA1 is electrically connected to the negative bus N of the bus output module 20 .

[0041] Optional, continue to refer to Figure 2 The switch start module 60 includes: a first intermediate relay normally closed switch KA1', a second intermediate relay coil KA2, a second intermediate relay normally open switch KA2', a second intermediate relay normally closed switch KA2", a first AC contactor coil KM1, a first AC contactor normally open switch KM1', a second AC contactor coil KM2, a second AC contactor normally closed switch KM2', a third AC contactor coil KM2 and a third AC contactor normally closed switch KM3';

[0042] The first end of the second intermediate relay normally closed switch KA2" is electrically connected to the output end of the first thyristor relay 12; the second end of the second intermediate relay normally closed switch KA2" is electrically connected to the first end of the first AC contactor coil KM1 and the first end of the first AC contactor normally open switch KM1'; the second end of the first AC contactor normally open switch KM1' is electrically connected to the first end of the third AC contactor normally closed switch KM3' and the first end of the second AC contactor normally closed switch KM2';

[0043] The second end of the third AC contactor normally closed switch KM3' is electrically connected to the first end of the second AC contactor coil KM2'; the second end of the second AC contactor normally closed switch KM2' is electrically connected to the first end of the third AC contactor coil KM3;

[0044] The first end of the second intermediate relay normally closed switch KA2" is also electrically connected to the first end KA2' of the second intermediate relay normally open switch and the first end of the first intermediate relay normally closed switch KA1'; the second end of the second intermediate relay normally open switch KA2' and the second end of the first intermediate relay normally closed switch KA1' are both electrically connected to the first end of the second intermediate relay coil KA2;

[0045] The second end of the second intermediate relay coil KA2 , the second end of the first AC contactor coil KM1 , the second end of the second AC contactor coil KM2 , and the second end of the third AC contactor coil KM3 are electrically connected to the negative bus of the bus output module 20 .

[0046] The starting working principle of the compressor is explained below in conjunction with a specific circuit diagram; during the starting working process, the high and low voltage switches SP1 in the power switch module 50 are turned on, and at the same time, the control unit 11 controls the first thyristor relay 12 to be turned on; specifically, when the high and low voltage switches SP1 in the power switch module 50 are turned on, the corresponding first intermediate relay coil KA1 is energized, and the first intermediate relay normally closed switch KA1' in the switch starting module 60 is disconnected. Since during the starting working process, the control unit 11 controls the first thyristor relay 12 to be turned on, the current output by the positive bus of the bus output module 20 will pass through the first intermediate relay normally closed switch KA1', and the first intermediate relay normally closed switch KA1' is disconnected, then the second intermediate relay coil KA2 loses power, and the second intermediate relay normally open switch KA2' is in a disconnected state, then the branch L4 in the switch starting module 60 remains in a disconnected state;

[0047] When the second intermediate relay coil KA2 loses power and the second intermediate relay normally closed switch KA2" is in a closed state, the first AC contactor coil KM1 is energized, and the branch L1 in the switch start module 60 remains in a conducting state;

[0048] When the first AC contactor coil KM1 is energized, the first AC contactor normally open switch KM1' is in a closed state, and the third AC contactor normally closed switch KM3' is in a normally closed state, the second AC contactor coil KM2 is energized, and the branch L2 in the switch start module 60 remains in a conductive state; because the second AC contactor coil KM2 is energized, the second AC contactor normally closed switch KM2' is disconnected, and the third AC contactor coil KM3 loses power, and the branch L3 in the switch start module 60 remains in a disconnected state; or when the first AC contactor normally open switch KM1' is in a closed state, the second AC contactor normally closed switch KM2' is disconnected. When the switch KM2' is in the normally closed state, the third AC contactor coil KM3 is energized, and the branch L3 in the switch start module 60 remains in the on state; since the third AC contactor coil KM3 is energized, the third AC contactor normally closed switch KM3' is disconnected, the second AC contactor coil KM2 loses power, and the branch L2 in the switch start module 60 remains in the off state; in this way, when the branches L1 and L2 in the switch start module 60 are in the on state, or the branches L1 and L3 are in the on state, the switch start module 60 starts working, thereby driving the compressor to work; the compressor operation in two modes is also realized.

[0049] The stopping working principle of the compressor; during the stopping process, the high and low voltage switches SP1 in the power switch module 50 are disconnected. When the high and low voltage switches SP1 in the power switch module 50 are disconnected, the corresponding first intermediate relay coil KA1 loses power, and the first intermediate relay normally closed switch KA1' in the switch start module 60 is closed. If the control unit 11 still controls the first thyristor relay 12 to be turned on at this time; the second intermediate relay coil KA2 is energized, and the second intermediate relay normally closed switch KA2" is disconnected, and the branch L1 of the switch start module 60 is disconnected, and the switch start module 60 stops working, thereby stopping the compressor.

[0050] Optionally, the switch activation module 60 is further refined based on the above embodiment. Figure 3 is a specific circuit diagram of another compressor protection circuit provided by an embodiment of the utility model; Figure 3 As shown, the compressor protection circuit also includes: a time relay coil KT, a time relay normally open switch KT' and a time relay normally closed switch KT";

[0051] The second end of the first AC contactor normally open switch KM1' is electrically connected to the first end of the time relay normally open switch KT', the first end of the time relay normally closed switch KT" and the first end of the time relay coil KT; the second end of the time relay normally open switch KT' is electrically connected to the first end of the third AC contactor normally closed switch KM3'; the second end of the third AC contactor normally closed switch KM3' is electrically connected to the first end of the second AC contactor coil KM2;

[0052] The second end of the time relay normally closed switch KT" is electrically connected to the first end of the second AC contactor normally closed switch KM2'; the second end of the second AC contactor normally closed switch KM2' is electrically connected to the first end of the third AC contactor coil KM3;

[0053] The second end of the time relay coil KT is electrically connected to the negative bus of the bus output module 20 .

[0054] Specifically, since the compressor includes low-pressure starting and high-pressure starting, this embodiment uses the time relay KT to realize low-pressure starting and high-pressure starting at different times; specifically, on the basis of the above embodiment, when the first AC contactor coil KM1 is energized, the time relay coil KT is energized, the time relay coil KT normally closed switch KT' is delayed to disconnect, the time relay coil KT normally closed switch KT' is turned on, the second contactor normally closed switch KM2' is turned on, the third contactor coil is energized KM3, and the branch L3 is in the on state; when the third contactor coil is energized KM3, the third contactor normally closed switch KM3' is disconnected, and the branch L2 is in the off state; in this way, L3 and other branches L1 realize low-pressure starting;

[0055] The time relay coil KT is energized, and after the preset time, the time relay coil KT normally open switch KT'' is turned on, and the third contactor normally closed switch KM3' is turned on, and the second contactor coil is energized KM2, and the branch L2 is in the on state; when the second contactor coil is energized KM2, the second contactor normally closed switch KM2' is disconnected, and the branch L3 is in the off state; in this way, after the preset time, L2 and other branches L1 achieve high voltage startup;

[0056] Optionally, the first AC contactor coil KM1 includes a main contactor coil; the first AC contactor normally open switch KM1' includes a main contactor normally open switch; the second AC contactor coil KM2 includes a delta contactor coil; the second AC contactor normally closed switch KM2' includes a delta contactor normally closed switch; the third AC contactor coil KM3 includes a star contactor coil; the third AC contactor normally closed switch KM3' includes a star contactor normally closed switch.

[0057] Based on the same inventive concept, an embodiment of the utility model also provides a refrigeration unit, which includes the compressor protection circuit described in the above embodiment; the refrigeration unit is such as a spiral chiller; since the refrigeration unit includes the compressor protection circuit described in the above embodiment, it also has the effects of the above embodiment, and this embodiment will not be repeated.

[0058] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A compressor protection circuit, characterized in that: include: A control module, a bus output module, a first fuse, a second fuse, a power switch module, a switch start module and a plurality of solenoid valve modules; the control module includes a control unit, a first thyristor relay and a plurality of second thyristor relays; The output end of the first thyristor relay is electrically connected to the compressor through the first fuse and the switch start module; the input end of the first thyristor relay is electrically connected to the power switch; The output end of each second thyristor relay is electrically connected to each solenoid valve module; the input end of each second thyristor relay is electrically connected to the power switch; The power switch module is connected in series between the positive and negative busbars of the bus output module; each of the solenoid valve modules is connected in series between the positive and negative busbars of the bus output module; the first end of the second fuse is electrically connected to the positive bus input end of the bus output module; the second end of the second fuse is electrically connected to the first end of the power switch module; the first thyristor relay and the plurality of the second thyristor relays are electrically connected to the control unit; the power switch module is coupled to the switch start module; Wherein, the rated current of the first fuse is less than the rated current of the first thyristor relay; and is greater than the rated current of the switch start module.

2. The compressor protection circuit according to claim 1, characterized in that: The power switch module includes: a first intermediate relay coil and a high and low voltage switch; The first end of the high and low voltage switch is electrically connected to the second end of the second fuse; the second end of the high and low voltage switch is electrically connected to the first end of the first intermediate relay coil; the second end of the first intermediate relay coil is electrically connected to the negative bus of the bus output module.

3. The compressor protection circuit according to claim 2, characterized in that: The switch start module includes: a first intermediate relay normally closed switch, a second intermediate relay coil, a second intermediate relay normally closed switch, a second intermediate relay normally open switch, a first AC contactor coil, a first AC contactor normally open switch, a second AC contactor coil, a second AC contactor normally closed switch, a third AC contactor coil and a third AC contactor normally closed switch; The first end of the normally closed switch of the second intermediate relay is electrically connected to the output end of the first thyristor relay; the second end of the normally closed switch of the second intermediate relay is electrically connected to the first end of the first AC contactor coil and the first end of the normally open switch of the first AC contactor; the second end of the normally open switch of the first AC contactor is electrically connected to the first end of the normally closed switch of the third AC contactor and the first end of the normally closed switch of the second AC contactor; The second end of the normally closed switch of the third AC contactor is electrically connected to the first end of the second AC contactor coil; the second end of the normally closed switch of the second AC contactor is electrically connected to the first end of the third AC contactor coil; The first end of the second intermediate relay normally closed switch is also electrically connected to the first end of the second intermediate relay normally open switch and the first end of the first intermediate relay normally closed switch; the second end of the second intermediate relay normally open switch and the second end of the first intermediate relay normally closed switch are both electrically connected to the first end of the second intermediate relay coil; The second end of the second intermediate relay coil, the second end of the first AC contactor coil, the second end of the second AC contactor coil, and the second end of the third AC contactor coil are electrically connected to the negative bus of the bus output module.

4. The compressor protection circuit according to claim 3, characterized in that: The switch start module also includes: a time relay coil, a time relay normally open switch and a time relay normally closed switch; The second end of the normally open switch of the first AC contactor is electrically connected to the first end of the normally open switch of the time relay, the first end of the normally closed switch of the time relay, and the first end of the time relay; the second end of the normally open switch of the time relay is electrically connected to the first end of the normally closed switch of the third AC contactor; the second end of the normally closed switch of the third AC contactor is electrically connected to the first end of the second AC contactor coil; The second end of the time relay normally closed switch is electrically connected to the first end of the second AC contactor normally closed switch; the second end of the second AC contactor normally closed switch is electrically connected to the first end of the third AC contactor coil; The second end of the time relay coil is electrically connected to the negative bus of the bus output module.

5. The compressor protection circuit according to claim 1, characterized in that: The first fuse includes a semiconductor protection type fuse.

6. The compressor protection circuit according to claim 1, characterized in that: The second fuse includes a semiconductor protection type fuse.

7. The compressor protection circuit according to claim 3, characterized in that: The first AC contactor coil includes a main contactor coil; the first AC contactor normally-open switch includes a main contactor normally-open switch; The second AC contactor coil includes a delta contactor coil; the second AC contactor normally closed switch includes a delta contactor normally closed switch; The third AC contactor coil includes a star-connected contactor coil; the third AC contactor normally closed switch includes a star-connected contactor normally closed switch.

8. The compressor protection circuit according to claim 1, characterized in that: The plurality of solenoid valves include an ejection pump solenoid valve, an oil return solenoid valve, an SV1 loading solenoid valve and an SV2 loading solenoid valve.

9. A refrigeration unit, characterized in that: The compressor protection circuit comprises the compressor protection circuit as described in any one of claims 1 to 8.

Images