Power supply method and power supply system for engineering machinery

Abstract

The invention relates to the field of engineering machinery, and discloses a power supply method and a power supply system for engineering machinery, and the power supply method comprises the steps: dividing loads in the engineering machinery into a first-stage load, a second-stage load and a third-stage load according to the power supply priority from high to low; under the condition that it is determined that an engine of the engineering machine is not started, when it is determined that commercial power is input, the commercial power supplies power to the first-stage load and the second-stage load, and when it is determined that no commercial power is input, a storage battery of the engineering machine supplies power to the first-stage load, and the second-stage load supplies power to the second-stage load; and the storage battery selectively supplies power to the secondary load or removes power from the secondary load according to the electric quantity condition. According to the power supply method, on the premise that basic functions of the engineering machinery are maintained, the electricity shortage phenomenon of the storage battery is avoided, and therefore the problem that the electric quantity of the storage battery is insufficient to start the engine is solved.

Description

Technical Field

[0001] The present invention belongs to the field of engineering machinery, and in particular, relates to a power supply method and a power supply system for engineering machinery. Background Art

[0002] In existing construction machinery, such as tower cranes, the operating power is mainly provided by batteries and generators powered by engines. When the construction machinery is stopped, the engine is not started. At this time, the construction machinery will maintain some functions, such as safety monitoring and other functions. The power to maintain these functions is all provided by batteries. Long-term power supply will cause the battery to be depleted, which may easily lead to the situation that the battery power is insufficient to start the engine, affecting the normal use of the construction machinery. Summary of the invention

[0003] In view of the above-mentioned deficiencies or defects in the prior art, the present invention provides a power supply method and a power supply system for engineering machinery, aiming to solve the technical problem that the battery becomes depleted after the engineering machinery is shut down for a long time, resulting in insufficient power to start the engine, thus affecting normal use.

[0004] To achieve the above object, the present invention provides a power supply method for engineering machinery, the power supply method comprising:

[0005] The loads in the construction machinery are divided into primary loads, secondary loads and tertiary loads according to the power supply priority from high to low;

[0006] When it is determined that the engine of the construction machinery is not started, when it is determined that there is AC power input, the AC power is used to power the primary load and the secondary load; when it is determined that there is no AC power input, the battery of the construction machinery is used to power the primary load, and the battery is used to selectively power or remove power from the secondary load according to the power situation.

[0007] Optionally, enabling the storage battery to selectively supply power to or remove power from the secondary load according to power status includes:

[0008] When the power of the battery is greater than a preset value, the battery supplies power to the secondary load; when the power of the battery is less than or equal to the preset value, the battery stops supplying power to the secondary load.

[0009] Optionally, the power supply method further includes:

[0010] When it is determined that the engine is started, the generator connected to the engine is used to supply power to the primary load, the secondary load and the tertiary load.

[0011] The present invention further provides a power supply system for an engineering machine, the engineering machine comprising a primary load, a secondary load and a tertiary load with power supply priorities from high to low, the power supply system comprising:

[0012] Batteries;

[0013] A conversion module, used for connecting to the mains and converting the mains into low-voltage direct current;

[0014] A control switch component, wherein the input end of the control switch component is respectively connected to the battery and the conversion module, and the output end of the control switch component is used to be respectively connected to the primary load and the secondary load. The control switch component is used to make the conversion module conductive with the primary load and the secondary load respectively when the conversion module has a low-voltage direct current input, and to make the battery conductive with the primary load when the conversion module has no low-voltage direct current input, and to selectively make the battery conductive with the secondary load or disconnect it according to the power status of the battery.

[0015] Optionally, the control switch assembly includes:

[0016] a first control switch, wherein an input end of the first control switch is selectively connected to the battery or the conversion module, and an output end of the first control switch is connected to the primary load,

[0017] The second control switch is a normally open switch, the input end of the second control switch is connected to the output end of the first control switch, and the output end of the second control switch is used to be connected to the secondary load.

[0018] Optionally, the first control switch is a relay, the coil of the first control switch is connected to the conversion module, and the first control switch is configured so that the input end is connected to the conversion module when the coil is energized, and the input end is connected to the battery when the coil is de-energized.

[0019] Optionally, the power supply system further includes a whole machine controller serving as the primary load and used to control the operation of the engineering machinery, the second control switch is a normally open relay, the coil of the second control switch is connected to the voltage signal output end of the whole machine controller, the voltage signal input end of the whole machine controller is connected to the conversion module, and the whole machine controller is configured as follows:

[0020] When it is determined that there is a voltage input at the voltage signal input terminal, a voltage signal is sent to the coil of the second control switch to energize the coil of the second control switch.

[0021] Optionally, the whole machine controller is also connected to the battery and is further configured as follows:

[0022] When it is determined that there is no voltage input to the voltage signal input terminal and when it is determined that the power level of the battery is greater than a preset value, a voltage signal is sent to the coil of the second control switch so that the coil of the second control switch is energized.

[0023] Optionally, the power supply system also includes a generator of the engineering machinery, and the input end of the first control switch is selectively connected to the generator. The power supply system also includes a third control switch, which is a normally open switch. The input end of the third control switch is connected to the generator, and the output end of the third control switch is used to connect to the third-level load.

[0024] Optionally, the power supply system also includes a normally open starting switch and a normally closed emergency stop switch, the third control switch is a normally open relay, the input end of the normally closed emergency stop switch is connected to the generator, and the input end and output end of the normally open starting switch are respectively connected to the output end of the normally closed emergency stop switch and the coil of the third control switch.

[0025] Through the above technical scheme, the loads in the engineering machinery are divided into primary loads, secondary loads and tertiary loads according to the power supply priority from high to low, wherein the primary loads may be some relatively important loads in the engineering machinery with lower power requirements, the secondary loads may be some relatively important loads in the engineering machinery with higher power requirements or loads with lower importance but lower power requirements, and the tertiary loads may be loads in the engineering machinery that only need to be started after the start-up work; when the engineering machinery is shut down, when it is determined that there is AC input, the AC power supplies the primary loads and the secondary loads, and when it is determined that there is no AC input, the battery supplies power to the primary loads, and selectively supplies power to or removes power to the secondary loads according to the power situation. In this way, the battery power loss phenomenon can be avoided while ensuring that the engineering machinery maintains its basic functions, thereby avoiding the problem that the battery power is insufficient to start the engine and affects the normal use of the engineering machinery.

[0026] Other features and advantages of the present invention will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0028] In the attached picture:

[0029] Figure 1 is a flow chart of a power supply method for engineering machinery in one embodiment of the present invention;

[0030] Figure 2A block diagram of a power supply system for an engineering machine in one embodiment of the present invention;

[0031] Figure 3 for Figure 2 Circuit diagram of the power supply system in.

[0032] Description of reference numerals:

[0033] 1 Machine controller 2 Battery

[0034] 3 Conversion module 4 First control switch

[0035] 5 Second control switch 6 Generator

[0036] 7 Third control switch 8 Normally open start switch

[0037] 9 Normally closed emergency stop switch DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0039] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0040] In the present invention, unless otherwise specified, the directions or positional relationships indicated by directional words such as "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the embodiments of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0041] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0042] The present invention firstly provides a power supply method for an engineering machine, where the engineering machine may be a tower crane or the like.

[0043] In one embodiment, referring to the attached Figure 1 As shown, the power supply method includes:

[0044] The loads in the construction machinery are divided into primary loads, secondary loads and tertiary loads according to the power supply priority from high to low;

[0045] Specifically, the division of load priorities can be designed according to actual needs. The first-level load can be some loads in the engineering machinery that are of high importance, low power demand and need to run continuously, such as the whole machine controller. The second-level load can be some loads in the engineering machinery that are of high importance, high power demand and need to run continuously, or loads of low importance, low power demand and need to run continuously, such as display screens or anemometers. The third-level load can be a load in the engineering machinery that only needs to be operated when the engineering machinery is started, such as a pressure sensor.

[0046] When it is determined that the engine of the construction machinery is not started, when it is determined that there is AC power input, the AC power is used to power the primary load and the secondary load. When it is determined that there is no AC power input, the battery of the construction machinery is used to power the primary load, and the battery is used to selectively power or remove power from the secondary load according to the power situation.

[0047] In this embodiment, when the construction machinery is shut down (i.e., the engine is not started), if there is AC power, it is powered by AC power. If there is no AC power, it is selectively powered by the battery according to the power level. In this way, the battery can be prevented from running out of power while maintaining the basic functions of the construction machinery when it is shut down, thereby avoiding the problem of insufficient battery power to start the engine and affecting the normal use of the construction machinery.

[0048] In one embodiment, when the battery power is greater than a preset value, the battery supplies power to the secondary load; when the battery power is less than or equal to the preset value, the battery stops supplying power to the secondary load. For example, when the battery power is greater than 20%, the battery supplies power to the secondary load; when the battery power is less than or equal to 20%, the battery stops supplying power to the secondary load.

[0049] In this way, the problem of power shortage caused by the battery being too low and having to supply power to a load with a large power demand can be avoided. Of course, the specific value of the preset value can be designed according to actual needs.

[0050] In one embodiment, the power supply method further includes:

[0051] When it is determined that the engine is started, the generator connected to the engine supplies power to the primary load, the secondary load and the tertiary load.

[0052] It can be understood that the starting work of the construction machinery, that is, the engine is started, the operation of the engine drives the generator to operate, thereby supplying power to the load.

[0053] Specifically, when it is determined that the engine is started, the generator can also be enabled to charge the battery at the same time.

[0054] The present invention also provides a power supply system for engineering machinery, and the power supply system can implement the above-mentioned power supply method.

[0055] In one embodiment, referring to the attached Figure 2 and attached Figure 3 , construction machinery includes primary loads, secondary loads and tertiary loads with power supply priorities from high to low, and the power supply system includes:

[0056] Battery 2;

[0057] The conversion module 3 is used to connect to the mains and convert the mains into low-voltage direct current;

[0058] A control switch component, wherein the input end of the control switch component is respectively connected to the battery 2 and the conversion module 3, and the output end of the control switch component is used to be respectively connected to the primary load and the secondary load. The control switch component is used to connect the conversion module 3 to the primary load and the secondary load respectively when the conversion module 3 has a low-voltage DC input, and to connect the battery 2 to the primary load when the conversion module 3 does not have a low-voltage DC input, and selectively connect or disconnect the battery 2 to the secondary load according to the power status of the battery 2.

[0059] In this embodiment, by controlling the switch assembly, it can be achieved that when the engineering machinery is shut down, if there is mains power, power is supplied by the mains power, and if there is no mains power, power is selectively supplied by the battery 2 according to the power level. In this way, the battery 2 can be prevented from running out of power while maintaining the basic functions of the engineering machinery when it is shut down, thereby avoiding the problem that the power level of the battery 2 is insufficient to start the engine and affects the normal use of the engineering machinery.

[0060] In one embodiment, referring to the attached Figure 2 and attached Figure 3 , the control switch assembly includes:

[0061] The first control switch 4, the input end of the first control switch 4 is selectively connected to the battery 2 or the conversion module 3, and the output end of the first control switch 4 is connected to the primary load,

[0062] The second control switch 5 is a normally open switch. The input end of the second control switch 5 is connected to the output end of the first control switch 4. The output end of the second control switch 5 is used to be connected to the secondary load.

[0063] In this embodiment, when the mains power is available, the input end of the first control switch 4 is connected to the conversion module 3, and the second control switch 5 is closed. In this way, the mains power supplies the primary load and the secondary load, that is, the whole machine controller 1. When the mains power is not available, the input end of the first control switch 4 is connected to the battery 2, and then it is determined whether to close the second control switch 5 according to the power of the battery 2. In this way, the battery 2 supplies power to the primary load to maintain the basic functions of the engineering machinery, and the battery 2 selectively supplies power to the secondary load according to the power; that is, when there is mains power, the engineering machinery is powered by the mains power. When there is no mains power, the power supply can be selected according to the power of the battery 2. In this way, the battery 2 can be prevented from running out of power while ensuring that the engineering machinery maintains its basic functions, thereby avoiding the problem that the power of the battery 2 is insufficient to start the engine and affects the normal use of the engineering machinery.

[0064] It can be understood that in this embodiment, the control of the first control switch 4 and the second control switch 5 can be manually operated by an operator, or a corresponding controller can be set for control. The first control switch 4 and the second control switch 5 themselves can also be set as automatically controllable switches, such as relays, etc. For details, please refer to the subsequent embodiments.

[0065] Specifically, the negative poles of the battery 2 and the conversion module 3 are both grounded, and the input end of the first control switch 4 is selectively connected to the positive pole of the battery 2 or the positive pole of the conversion module 3 .

[0066] In one embodiment, referring to the attached Figure 2 and attached Figure 3 As shown, the first control switch 4 is a relay, the coil of the first control switch 4 is connected to the conversion module 3, and the first control switch 4 is configured so that the input end is connected to the conversion module 3 when the coil is powered, and the input end is connected to the battery 2 when the coil is de-powered.

[0067] With such a setting, automatic control of the first control switch 4 can be achieved. When there is no AC power access, the coil of the first control switch 4 is in a power-off state, and the input end is connected to the battery 2, and the battery is powered at this time. When the AC power is connected, the coil of the first control switch 4 will be energized, so that the input end is connected to the conversion module 3 and powered by the AC power.

[0068] Specifically, the positive pole of the coil of the first control switch 4 is connected to the positive pole of the conversion module 3, and the negative pole of the coil of the first control switch 4 is grounded. It should be noted that relays are well known to those skilled in the art, so their specific structure and working principle are not described in detail here.

[0069] In one embodiment, referring to the attached Figure 2 and attached Figure 3As shown, the power supply system also includes a whole machine controller 1 as a primary load and used to control the operation of the engineering machinery. The second control switch 5 is a normally open relay. The coil of the second control switch 5 is connected to the voltage signal output end of the whole machine controller 1. The voltage signal input end of the whole machine controller 1 is connected to the conversion module 3. The whole machine controller 1 is configured as follows:

[0070] When it is determined that there is a voltage input at the voltage signal input terminal, a voltage signal is sent to the coil of the second control switch 5 so that the coil of the second control switch 5 is energized.

[0071] With such a setting, automatic control of the second control switch 5 can be achieved. When the AC power is connected, the whole machine controller 1 will energize the coil of the second control switch 5, so that the second control switch 5 is closed. At this time, the secondary load is powered by the AC power, so that more functions of the construction machinery can be maintained after shutdown.

[0072] Specifically, the voltage signal input terminal of the whole machine controller 1 is connected to the positive electrode of the conversion module 3, the positive electrode of the coil of the second control switch 5 is connected to the voltage signal output terminal of the whole machine controller 1, and the negative electrode of the coil of the second control switch 5 and the negative electrode of the whole machine controller are both grounded. It should be noted that the normally open relay is well known to those skilled in the art, so its specific structure and working principle will not be described in detail here.

[0073] In one embodiment, the whole machine controller 1 is also connected to the battery 2 and is further configured as follows:

[0074] When it is determined that there is no voltage input to the voltage signal input terminal and when it is determined that the power level of the storage battery 2 is greater than a preset value, a voltage signal is sent to the coil of the second control switch 5 to energize the coil of the second control switch 5 .

[0075] With such an arrangement, when the battery 2 has sufficient power, the load of the construction machinery is powered by the battery 2, so that more functions of the construction machinery can be maintained after the construction machinery is shut down.

[0076] Specifically, the preset value may be set according to actual needs. For example, the preset value may be 20% of the total power.

[0077] Of course, when the power level of the storage battery 2 is less than or equal to the preset value, the coil of the second control switch 5 remains in the de-energized state.

[0078] In one embodiment, the conversion module 3 is a switching power supply or a rectifier transformer. In actual application, the AC220V input of the mains power is converted into DC24V by the conversion module 3 so that the load of the engineering machinery can be universal. It should be noted that the switching power supply or the rectifier transformer itself is well known to those skilled in the art, so its specific structure and working principle are not described in detail here.

[0079] In one embodiment, referring to the attached Figure 2 As shown, the power supply system also includes a generator 6 of the engineering machinery, and the input end of the first control switch 4 is selectively connected to the generator 6. The power supply system also includes a third control switch 7, which is a normally open switch. The input end of the third control switch 7 is connected to the generator 6, and the output end of the third control switch 7 is used to connect to the third-level load.

[0080] It can be understood that the generator 6 of the engineering machinery is connected to the engine, and when the engine is started, it can drive the generator 6 to operate to generate low-voltage direct current to achieve power supply.

[0081] With such an arrangement, when the construction machinery is started and the engine starts running, the connection with the mains power can be disconnected, and the generator 6 can supply power to the primary load through the first control switch 4, to the secondary load through the first control switch 4 and the second control switch 5, and to the tertiary load through the third control switch 7.

[0082] Specifically, the positive pole of the generator 6 can be connected to the positive pole of the battery 2 to form a common output terminal, and the input terminal of the first control switch 4 can be connected to the common output terminal to simultaneously connect to the positive pole of the generator 6 and the positive pole of the battery 2.

[0083] In this embodiment, the whole machine controller 1 is configured as follows:

[0084] When it is determined that the engine of the construction machinery is started, a voltage signal is sent to the coil of the second control switch 5 to energize the coil of the second control switch 5, so that the generator 6 can normally supply power to the load of the construction machinery.

[0085] In this embodiment, when the engine is started and the generator 6 is driven to start running, the third control switch 7 can be closed so that the generator 6 can supply power to the three-level load. When the engine is not started and the generator 6 is not started, the third control switch 7 can remain open.

[0086] The third control switch 7 may be controlled manually by an operator, or by setting a corresponding controller. The third control switch 7 itself may also be set as an automatically controllable switch, such as a relay, etc. For details, please refer to the subsequent embodiments.

[0087] In one embodiment, referring to the attached Figure 2 and attached Figure 3 As shown, the power supply system also includes a normally open starting switch 8 and a normally closed emergency stop switch 9. The third control switch 7 is a normally open relay. The input end of the normally closed emergency stop switch 9 is respectively connected to the battery 2 and the generator 6. The input end and output end of the normally open starting switch 8 are respectively connected to the output end of the normally closed emergency stop switch 9 and the coil of the third control switch 7.

[0088] With such an arrangement, automatic control of the third control switch 7 can be achieved. When the engine is not started and the generator 6 is not started, since the normally open starting switch 8 is disconnected, the coil of the third control switch 7 is in a power-off state, and the third control switch 7 remains disconnected. When the engine is started and the generator 6 is started, the normally open starting switch 8 can be closed, and the coil of the third control switch 7 can be energized, thereby closing and conducting the third control switch 7, so that the generator 6 continues to supply power to the tertiary load. In addition, in an emergency, the normally closed emergency stop switch 9 can be opened, so that the coil of the third control switch 7 loses power, the third control switch 7 is disconnected, and the power supply of the generator 6 to the tertiary load is disconnected.

[0089] Specifically, the normally open start switch 8 and the normally closed emergency stop switch 9 are manually operated push button switches.

[0090] Specifically, the input end of the normally closed emergency stop switch 9 is connected to the positive poles of the battery 2 and the generator 6 respectively, the output end of the normally open start switch 8 is connected to the positive pole of the coil of the third control switch 7, and the negative pole of the coil of the third control switch 7 is grounded. It should be noted that relays are well known to those skilled in the art, so their specific structure and working principle will not be described in detail here.

[0091] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0092] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0094] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A power supply method for engineering machinery, characterized in that: The power supply method comprises: The loads in the construction machinery are divided into primary loads, secondary loads and tertiary loads according to the power supply priority from high to low; When it is determined that the engine of the construction machinery is not started, when it is determined that there is AC power input, the AC power is used to power the primary load and the secondary load; when it is determined that there is no AC power input, the battery of the construction machinery is used to power the primary load, and the battery is used to selectively power or remove power from the secondary load according to the power situation.

2. The power supply method for engineering machinery according to claim 1, characterized in that: The method of enabling the storage battery to selectively supply power to the secondary load or remove power supply according to the power status includes: When the power of the battery is greater than a preset value, the battery supplies power to the secondary load; when the power of the battery is less than or equal to the preset value, the battery stops supplying power to the secondary load.

3. The power supply method for construction machinery according to claim 1, characterized in that: The power supply method further comprises: When it is determined that the engine is started, a generator connected to the engine is enabled to supply power to the primary load, the secondary load, and the tertiary load.

4. A power supply system for engineering machinery, the engineering machinery comprising primary loads, secondary loads and tertiary loads with power supply priorities from high to low, characterized in that: The power supply system comprises: Battery (2); A conversion module (3), used for connecting to the mains power and converting the mains power into low-voltage direct current; A control switch component, wherein the input end of the control switch component is respectively connected to the storage battery (2) and the conversion module (3), and the output end of the control switch component is used to be respectively connected to the primary load and the secondary load. The control switch component is used to connect the conversion module (3) to the primary load and the secondary load respectively when the conversion module (3) has a low-voltage direct current input, and to connect the storage battery (2) to the primary load when the conversion module (3) does not have a low-voltage direct current input, and selectively connect or disconnect the storage battery (2) from the secondary load according to the power level of the storage battery (2).

5. The power supply system for engineering machinery according to claim 4, characterized in that: The control switch assembly comprises: a first control switch (4), wherein an input end of the first control switch (4) is selectively connected to the storage battery (2) or the conversion module (3), and an output end of the first control switch (4) is connected to the primary load, A second control switch (5), wherein the second control switch (5) is a normally open switch, wherein an input end of the second control switch (5) is connected to an output end of the first control switch (4), and an output end of the second control switch (5) is used to be connected to the secondary load.

6. The power supply system for engineering machinery according to claim 5, characterized in that: The first control switch (4) is a relay, the coil of the first control switch (4) is connected to the conversion module (3), and the first control switch (4) is configured such that an input end is connected to the conversion module (3) when the coil is energized, and the input end is connected to the storage battery (2) when the coil is de-energized.

7. The power supply system for engineering machinery according to claim 5, characterized in that: The power supply system further comprises a whole machine controller (1) serving as the primary load and used to control the operation of the engineering machinery; the second control switch (5) is a normally open relay; the coil of the second control switch (5) is connected to the voltage signal output end of the whole machine controller (1); the voltage signal input end of the whole machine controller (1) is connected to the conversion module (3); the whole machine controller (1) is configured as follows: When it is determined that there is a voltage input at the voltage signal input terminal, a voltage signal is sent to the coil of the second control switch (5) so that the coil of the second control switch (5) is energized.

8. The power supply system for engineering machinery according to claim 7, characterized in that: The whole machine controller (1) is also connected to the storage battery (2) and is further configured as follows: When it is determined that there is no voltage input at the voltage signal input terminal and when it is determined that the power level of the storage battery (2) is greater than a preset value, a voltage signal is sent to the coil of the second control switch (5) so that the coil of the second control switch (5) is energized.

9. The power supply system for engineering machinery according to claim 5, characterized in that: The power supply system further comprises a generator (6) of the engineering machinery, the input end of the first control switch (4) is selectively connected to the generator (6), and the power supply system further comprises a third control switch (7), the third control switch (7) is a normally open switch, the input end of the third control switch (7) is connected to the generator (6), and the output end of the third control switch (7) is used to be connected to the three-level load.

10. The power supply system for engineering machinery according to claim 9, characterized in that: The power supply system further comprises a normally open start switch (8) and a normally closed emergency stop switch (9); the third control switch (7) is a normally open relay; the input end of the normally closed emergency stop switch (9) is connected to the generator (6); the input end and the output end of the normally open start switch (8) are respectively connected to the output end of the normally closed emergency stop switch (9) and the coil of the third control switch (7).

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