An electric shovel starting protection system and a control method thereof

Abstract

The application relates to an electric excavator starting protection system and a control method thereof, and belongs to the technical field of engineering machinery, wherein the electric excavator starting protection system comprises an open-phase relay, a first phase sequence relay, a main controller, a soft starter, a starting button, a safety handle, a first intermediate relay, a stop button, a second intermediate relay, a key switch, a pressure sensor, a second phase sequence relay and a main motor; the method based on the system realizes three-stage starting protection by installing elements such as the open-phase relay, the phase sequence relay, the safety handle and the stop button, increases the safety of operation, prevents starting caused by misoperation, ensures that the main pump operates according to a target steering, improves the working efficiency and service life of the equipment, and adopts a multi-stage starting protection method to detect and process according to different situations, so that the method is safer and more reliable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering machinery, and in particular to a starting protection system of an electric excavator and a control method thereof. BACKGROUND

[0002] With the rapid development of electric technology of engineering machinery and the increasing environmental protection pressure, compared with traditional diesel excavators and pure electric excavators, the electric excavator with external 380V cable is an intermediate state, has the advantages of energy saving and environmental protection, is low in price, can better meet market demand, and has development potential in certain application scenarios. Due to the length limitation of the cable, the electric excavator is often applied to fixed places, and the power supply of the vehicle comes from the power distribution cabinet of the factory building, which is matched with different tools such as suction cups and lotus claw to make the vehicle more suitable for fixed working environments such as factory buildings.

[0003] The 380V cable of the electric excavator needs to be connected in sequence according to the power distribution cabinet-cable reel (or junction box) inlet-cable reel (or junction box) outlet-collector ring inlet-collector ring outlet-electric control cabinet inlet-electric control cabinet outlet-main motor, and the main motor needs to be reversed to drive the main pump to rotate. The main motor of the existing electric excavator or dual-power excavator is usually controlled to start by a soft starter. However, the current starting protection system has the following problems:

[0004] (1) Only overload, overcurrent, overvoltage and open phase and the like starting protection is added at the front end of the soft starter, and there is no starting protection measure for the part from the soft starter main motor to the main motor and then to the shaft connected main pump;

[0005] (2) When the safety handle is not closed, the key cannot start the main motor, but the main motor can be started by the start button at the electric control cabinet, which is easy to cause danger;

[0006] (3) When the electric excavator is started for the first time after being put into operation, the 380V cable may be connected with wrong phase sequence, or the 380V cable may not be correctly installed at the power distribution cabinet due to the fact that the state of the power distribution cabinet on the market cannot be unified, which may cause the main motor to rotate forward and the main pump to rotate reversely, and long-time operation may reduce the service life of the excavator to a certain extent or even damage the excavator, and when the soft starter is in the protection state, the problem is difficult to troubleshoot;

[0007] (4) If the two phases in the 380V cable are not adjusted or the rotation matching of the main motor and the main pump is problematic when the electric excavator is started for the first time after being put into operation, the main pump may also rotate reversely, and there is also no starting protection measure for the part from the soft starter main motor to the main motor and then to the main pump.

[0008] Therefore, it is necessary to study a starting protection system of an electric excavator and a control method thereof. SUMMARY

[0009] The present application aims at overcoming the deficiencies in the prior art, and provides an electric excavator starting protection system and a control method thereof, so that no matter whether the phase sequence wiring is wrong, or the main motor cable is not adjusted, or the main pump does not operate according to the target steering due to the problem of the main motor and the main pump steering matching, the method provided by the present application can ensure that the main motor drives the main pump to operate according to the target steering through the main controller combined with the soft starter, and damage to the excavator caused by the reverse rotation of the main pump is prevented.

[0010] To achieve the above object, the present application provides the following technical solutions.

[0011] In a first aspect, the present application provides an electric excavator starting protection system, comprising a main motor, a main controller, and a soft starter, an open-phase relay, a first phase sequence relay, a second phase sequence relay, a starting button, a second intermediate relay, a safety handle, a key switch and a pressure sensor connected with the main controller respectively;

[0012] The soft starter is connected between three-phase power and the main motor, and is used for controlling the main motor;

[0013] The open-phase relay is installed at the incoming line end of the soft starter, and is used for detecting whether the three-phase power is open-phase, and transmitting a signal to the main controller;

[0014] The first phase sequence relay is installed at the incoming line end of the soft starter, and is used for detecting whether the electric phase sequence from the power distribution cabinet to the soft starter is wrong, and transmitting a signal to the main controller;

[0015] The second phase sequence relay is installed at the main motor terminal, and is used for detecting whether the electric phase sequence from the soft starter to the main motor is wrong, and transmitting a signal to the main controller;

[0016] The starting button and the second intermediate relay are connected with the soft starter, and are used for controlling the main motor through the soft starter;

[0017] The pressure sensor is used for detecting the main pump pressure connected with the main motor, judging whether the main pump operates according to the target steering, and transmitting a signal to the main controller;

[0018] The main controller is used for receiving signals from the open-phase relay, the first phase sequence relay, the second phase sequence relay and the pressure sensor, and controlling the soft starter and the second intermediate relay to perform corresponding actions.

[0019] Further, the electric excavator starting protection system further comprises a first intermediate relay, which is a starting intermediate relay and comprises a first intermediate relay normally open contact and a first intermediate relay coil, the first intermediate relay coil is connected with the main controller, the first intermediate relay normally open contact is connected with the soft starter at both ends, and the first intermediate relay normally open contact is connected in parallel with the starting button.

[0020] Further, the electric excavator starting protection system further comprises a stop button, the second intermediate relay is a stopping intermediate relay and comprises a second intermediate relay normally closed contact and a second intermediate relay coil, the second intermediate relay coil is connected with the main controller, the second intermediate relay normally closed contact is connected with the soft starter at one end, and the other end is connected in series with the stop button and the soft starter.

[0021] Further, the contact of the phase loss relay is a normally open contact, and both ends of the normally open contact are connected with the main controller.

[0022] Further, the contact of the first phase sequence relay is a normally open contact, and both ends of the normally open contact are connected with the main controller.

[0023] Further, the contact of the second phase sequence relay is a normally closed contact, and both ends of the normally open contact are connected with the main controller.

[0024] In the second aspect, the application further provides a control method of the electric excavator starting protection system, which comprises the following steps:

[0025] After the cable line is connected with the power distribution cabinet, the three-phase starting protection program is started to detect and process the three-phase power in front of the soft starter;

[0026] After the three-phase starting protection program is completed, it is determined whether the starting button or the key switch is started, if not, the electric excavator starting protection program is ended, and if yes, the two-stage starting protection program is started, and the three-phase power from the soft starter to the main motor is detected and processed when the starting button or the key switch is started and the main motor is not started;

[0027] After the two-stage starting protection program is completed, it is determined whether the main pump pressure is greater than or equal to the preset pressure, if yes, the starting is completed, and if not, the one-stage starting protection program is started, and the main motor and the main pump steering matching relationship are detected and processed after the main motor is started; after the one-stage starting protection program is completed, the starting is completed.

[0028] The main motor drives the main pump to run according to the target steering direction, and the electric excavator starting protection program is ended.

[0029] Further, the three-stage starting protection program specifically comprises:

[0030] The main motor is initialized in the steering state;

[0031] After the power distribution cabinet, control cabinet and key are powered on, it is judged whether the safety handle is closed, if the safety handle is not closed, the second intermediate relay coil is powered on, the second intermediate relay normally closed contact is disconnected, the main motor cannot be started through the key switch and the start button, then after the safety handle is closed, the power distribution cabinet, control cabinet and key are powered on, it is judged again whether the safety handle is closed and the subsequent operation is repeated;

[0032] If the safety handle is closed, it is judged whether the soft starter input line is missing phase, if yes, the missing phase fault alarm is given, and then the maintenance is checked, and then after the power distribution cabinet, control cabinet and key are powered on, it is judged again whether the safety handle is closed and the subsequent operation is repeated, if no, the second intermediate relay coil is powered off, the second intermediate relay normally closed contact is closed, and the main motor can be started through the key switch or the start button;

[0033] It is judged whether the electric phase sequence from the power distribution cabinet to the soft starter is wrong, if yes, the main motor steering state is changed, and the state is stored, if no, the current main motor steering state is stored.

[0034] Further, the secondary starting protection program specifically comprises:

[0035] It is judged whether the electric phase sequence from the soft starter to the main motor is wrong, if no, the main motor steering state is changed, the state is stored, and then the current stored main motor steering control signal is output to the soft starter, the main motor is started and drives the main pump to rotate, if yes, the current stored main motor steering control signal is output to the soft starter, the main motor is started and drives the main pump to rotate.

[0036] Further, the primary starting protection program specifically comprises: changing the current main motor steering state, storing the state, outputting the current stored main motor steering control signal to the soft starter, and making the main motor drive the main pump to rotate in the opposite direction.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] (1) The present application sets a missing phase relay for detecting whether the three-phase power is missing phase, a phase sequence relay for detecting whether the electric phase sequence is wrong, and a pressure sensor for detecting whether the main pump is running according to the target steering, the main controller receives signals from the missing phase relay, the first phase sequence relay, the second phase sequence relay and the pressure sensor, and controls the soft starter and the second intermediate relay to perform corresponding actions, so that multiple detection and protection can be ensured during the starting process, and damage to the equipment or dangerous situations caused by missing phase of three-phase power or wrong electric phase sequence can be avoided.

[0039] (2) The electric excavator starting protection system provided by the application is provided with safety handle, key switch and starting button and the like, and the main motor can only be started under the condition that these devices are correctly operated, for example, the main motor cannot be started under the condition that the safety handle is opened, no matter whether the key or the starting button is started, so that the accidents caused by misoperation or no one operation are avoided, and the safety handle and the stop button can also be used for emergency stop operation, so that the safety of the operator and the equipment is ensured.

[0040] (3) The main pump pressure is monitored by the pressure sensor, and whether the main pump is operated according to the target steering is judged, and through the monitoring of the main pump pressure, the abnormal condition can be found in time and the corresponding measures can be taken, so that the equipment failure or damage is avoided, the normal operation of the main pump is ensured, and the operation reliability of the main pump is improved.

[0041] (4) The three-stage starting protection method is adopted, different starting protection detection methods are adopted according to different conditions, and the three-stage starting protection detection methods are processed, specifically, the system judges and processes the three-stage, two-stage and one-stage starting protection programs according to the state of the cable line after being connected to the power distribution cabinet, each stage of program has clear operation steps, the operator can quickly judge the problem, and the corresponding measures can be taken in time, so that the safety is more reliable, the multiple protection of the starting process of the electric excavator is realized, and the service life of the equipment is improved.

[0042] (5) In the application, the main controller is connected with the soft starter, has the function of controlling the forward and reverse rotation of the main motor, and can store the main motor steering control signal, so that the operation state of the main motor can be accurately controlled, and the operation performance and efficiency of the electric excavator are improved.

[0043] (6) Overall, the electric excavator starting protection system provided by the application improves the safety and operation performance of the equipment through various protection measures and optimized control functions, ensures that the main motor and the main pump operate safely as expected, plays an important role in the starting process of the excavator, and improves the reliability of starting and the convenience of operation. BRIEF DESCRIPTION OF DRAWINGS

[0044] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0045] The application can be more clearly understood and appreciated from the following detailed description, taken in conjunction with the accompanying drawings, in which:

[0046] Figure 1 is a control principle schematic diagram of the electric excavator starting protection system provided by the embodiment of the application;

[0047] Figure 2 is a control flow chart of the electric excavator starting protection system provided by the embodiment of the application;

[0048] Figure 3 This is a flowchart of the three-level start-up protection program for electric excavators provided in an embodiment of the present invention;

[0049] Figure 4 This is a flowchart of the secondary start-up protection program for an electric excavator provided in an embodiment of the present invention;

[0050] Figure 5 This is a flowchart of the first-level start-up protection program for an electric excavator provided in an embodiment of the present invention;

[0051] Labeling Explanation: 1-Phase Loss Relay, 2-First Phase Sequence Relay, 3-Main Controller, 4-Soft Starter, 5-Start Button, 6-Safety Handle, 7-First Intermediate Relay, 701-Normally Open Contact of First Intermediate Relay, 702-First Intermediate Relay Coil, 8-Stop Button, 9-Second Intermediate Relay, 901-Normally Closed Contact of Second Intermediate Relay, 902-Second Intermediate Relay Coil, 10-Key Switch, 11-Pressure Sensor, 12-Second Phase Sequence Relay, 13-Main Motor. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] In the description of the invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] Example 1

[0056] like Figure 1 As shown, this embodiment provides an electric excavator start-up protection system, including a main motor 13, a main controller 3, and a soft starter 4, a phase loss relay 1, a first phase sequence relay 2, a second phase sequence relay 12, a start button 5, a second intermediate relay 9, a safety handle 6, a key switch 10, and a pressure sensor 11, all connected to the main controller 3.

[0057] The soft starter 4 is connected between the three-phase power supply and the main motor 13 to control the forward and reverse rotation of the main motor 13, and the main controller 3 stores the control signals for controlling the forward and reverse rotation of the main motor 13.

[0058] The phase loss relay 1 is installed at the input terminal of the soft starter 4. Its contacts are normally open, and the two ends of the normally open contacts are connected to the controller 2 respectively. It is used to detect whether the 380V three-phase power is missing a phase and transmit the signal to the main controller 3.

[0059] The first phase sequence relay 2 is installed at the input terminal of the soft starter 4. Its contacts are normally open, and the two ends of the normally open contacts are connected to the main controller 3 respectively. It is used to detect whether the electrical phase sequence 1 from the distribution cabinet to the soft starter 4 is incorrect, that is, whether it is VUW / UWV / WVU, and transmit the signal to the main controller 3.

[0060] The second phase sequence relay 12 is installed at the terminal of the main motor 13. Its contacts are normally closed contacts. The two ends of the normally closed contacts are connected to the main controller 3 respectively. It is used to detect whether the electrical phase sequence 2 from the soft starter 4 to the main motor 13 is incorrect, that is, whether it is VUW / UWV / WVU, and transmit the signal to the main controller 3.

[0061] The start button 5 and the second intermediate relay 9 are both connected to the soft starter 4 and are used to control the main motor 13 through the soft starter 4; the pressure sensor 11 is used to detect the pressure of the main pump connected to the main motor 13, determine whether the main pump is running in the target direction, and transmit the signal to the main controller 3.

[0062] Specifically, the main controller 3 is used to receive signals from the phase loss relay 1, the first phase sequence relay 2, the second phase sequence relay 12 and the pressure sensor 11, and control the soft starter 4 and the second intermediate relay 9 to perform corresponding actions.

[0063] The electric excavator start protection system provided in this embodiment also includes a first intermediate relay 7, which is a start intermediate relay, including a first intermediate relay normally open contact 701 and a first intermediate relay coil 702. The first intermediate relay coil 702 is connected to the main controller 3, and both ends of the first intermediate relay normally open contact 701 are connected to the soft starter 4. The first intermediate relay normally open contact 701 is connected in parallel with the start button 5.

[0064] The electric excavator start protection system provided in this embodiment also includes a stop button 8 and a second intermediate relay 9, which is a stop intermediate relay, including a normally closed contact 901 and a coil 902. The coil 902 is connected to the main controller 3. One end of the normally closed contact 901 is connected to the soft starter 4, and the other end is connected in series with the stop button 8 to the soft starter 4.

[0065] Example 2

[0066] like Figures 1-5 As shown in the figure, this embodiment provides a control method for an electric excavator start-up protection system, and the specific steps are as follows:

[0067] Step 1: After the three-phase cable is connected to the distribution cabinet, the three-phase start-up protection program is initiated to detect and process the three-phase power supply at the front end of the soft starter 4. The three-phase start-up protection program specifically includes the following steps:

[0068] Step 1.1: The main controller 3 initializes the steering state of the main motor 13.

[0069] Step 1.2: After powering on the distribution cabinet, control cabinet, and key, determine whether safety handle 6 is closed. If safety handle 6 is not closed, then the second intermediate relay 9 ( Figure 3 When the coil 902 of the second intermediate relay (represented by intermediate relay 2) is energized, the normally closed contact 901 of the second intermediate relay is opened, and the main motor 13 cannot be started by the key switch 10 and the start button 5. The safety handle 6 needs to be closed, and the process returns to step 1.2. If the safety handle 6 is already closed, the process returns to step 1.3.

[0070] Step 1.3: Determine if there is a phase loss at the input terminal of the soft starter 4. If so, a phase loss fault alarm will be triggered, and the fault will be checked and repaired. Then return to step 1.2. If not, the second intermediate relay coil 902 will be de-energized, the normally closed contact 901 of the second intermediate relay will be closed, and the main motor 13 can be started by the key switch 10 or the start button 5. Proceed to step 1.4.

[0071] Step 1.4: Determine whether the phase sequence 1 from the distribution cabinet to the soft starter 4 is incorrect (i.e., VUW / UWV / WVU). If yes, change the direction of rotation of the main motor 13 and store the state, then proceed to step 2; otherwise, store the current direction of rotation of the main motor 13 and proceed to step 2.

[0072] Step 2: Determine if the start button 5 or key switch 10 is activated. If not, end the electric excavator start protection program; if yes, enter the secondary start protection program. At the instant when the start button 5 or key switch 10 is activated but the main motor 13 is not activated, detect and process the three-phase power supply from the soft starter 4 to the main motor 13. The secondary start protection program includes the following steps:

[0073] Step 2.1: Determine whether the electrical phase sequence 2 from the soft starter 4 to the main motor 13 is incorrect (i.e., VUW / UWV / WVU). If yes, proceed to step 2.2; if no, change the direction of rotation of the main motor 13, store the state, and then proceed to step 2.2.

[0074] Step 2.2: The main controller 3 outputs the currently stored main motor 13 steering control signal to the soft starter 4, starts the main motor 13 and drives the main pump to rotate in the steering direction controlled by the main controller 3, and then proceeds to step 3.

[0075] Step 3: Determine if the main pump pressure is greater than or equal to the preset pressure ≥ b. If yes, the startup is complete, proceed to Step 4; otherwise, enter the first-level startup protection program. After the main motor 13 starts, the rotational direction matching relationship between the main motor 13 and the main pump is detected and processed. The first-level startup protection program includes the following steps:

[0076] Step 3.1: The main controller 3 changes the current direction of the main motor 13 and stores the state. It outputs the currently stored direction control signal of the main motor 13 to the soft starter 4, so that the main motor 13 drives the main pump to rotate in the opposite direction. The start-up is complete. Proceed to step 4.

[0077] Step 4: The main motor 13 drives the main pump to rotate in the target direction, ending the electric excavator start-up protection program.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A starting protection system for an electric excavator, characterized in that, It includes a main motor, a main controller, and a soft starter, a phase loss relay, a first phase sequence relay, a second phase sequence relay, a start button, a second intermediate relay, a safety handle, a key switch, and a pressure sensor, all connected to the main controller. The soft starter is connected between the three-phase power supply and the main motor and is used to control the main motor; The phase loss relay is installed at the soft starter input terminal to detect whether the three-phase power is missing a phase and transmit the signal to the main controller. The first phase sequence relay is installed at the soft starter input terminal to detect whether the electrical phase sequence from the distribution cabinet to the soft starter is incorrect and to transmit the signal to the main controller. The second phase sequence relay is installed at the main motor terminal to detect whether the electrical phase sequence from the soft starter to the main motor is incorrect and to transmit the signal to the main controller. The start button and the second intermediate relay are both connected to the soft starter and are used to control the main motor through the soft starter; The pressure sensor is used to detect the pressure of the main pump connected to the main motor, determine whether the main pump is running in the target direction, and transmit the signal to the main controller. The main controller is used to receive signals from the phase loss relay, the first phase sequence relay, the second phase sequence relay and the pressure sensor, and control the soft starter and the second intermediate relay to perform corresponding actions. The control soft starter and the second intermediate relay perform corresponding actions, including: In the three-level start protection procedure, if the safety handle is not closed, the second intermediate relay coil is energized, the normally closed contact of the second intermediate relay opens, and the main motor cannot be started by the key switch or the start button; if the safety handle is closed, and it is determined that there is no phase loss at the soft starter input terminal, the second intermediate relay coil is de-energized, the normally closed contact of the second intermediate relay closes, and the main motor can be started by the key switch or the start button; it is determined whether the phase sequence from the distribution cabinet to the soft starter is incorrect, and if so, the direction of rotation of the main motor is changed; In the secondary start-up protection program, it is determined whether the electrical phase sequence from the soft starter to the main motor is incorrect. If not, the main motor rotation state is changed and stored. Then, the currently stored main motor rotation control signal is output to the soft starter to start the main motor and drive the main pump to rotate. If yes, the currently stored main motor rotation control signal is output to the soft starter to start the main motor and drive the main pump to rotate. In the first-level start-up protection program, the current main motor rotation state is changed and stored. The stored main motor rotation control signal is then output to the soft starter, causing the main motor to drive the main pump to rotate in the opposite direction.

2. The electric excavator start-up protection system according to claim 1, characterized in that, It also includes a first intermediate relay, which is a starting intermediate relay, including a first intermediate relay normally open contact and a first intermediate relay coil. The first intermediate relay coil is connected to the main controller. Both ends of the first intermediate relay normally open contact are connected to the soft starter. The first intermediate relay normally open contact is connected in parallel with the start button.

3. The electric excavator start-up protection system according to claim 1, characterized in that, It also includes a stop button. The second intermediate relay is a stop intermediate relay, which includes a normally closed contact and a coil. The coil is connected to the main controller. One end of the normally closed contact is connected to the soft starter, and the other end is connected in series with the stop button to the soft starter.

4. The electric excavator start-up protection system according to claim 1, characterized in that, The contacts of the phase loss relay are normally open contacts, and both ends of the normally open contacts are connected to the main controller.

5. The electric excavator start-up protection system according to claim 1, characterized in that, The contacts of the first phase sequence relay are normally open contacts, and the two ends of the normally open contacts are respectively connected to the main controller.

6. The electric excavator start-up protection system according to claim 1, characterized in that, The contacts of the second phase sequence relay are normally closed contacts, and the two ends of the normally closed contacts are connected to the main controller.

7. A control method for the electric excavator start-up protection system according to any one of claims 1 to 6, characterized in that, include: After the three-phase cable is connected to the distribution cabinet, a three-level start protection program is entered to detect and process the three-phase power at the front end of the soft starter. After the three-level start protection program ends, it is determined whether the start button or key switch is activated. If not, the start protection program for the electric excavator ends; if so, the two-level start protection program is entered. At the moment when the start button or key switch is activated but the main motor is not activated, the three-phase power from the soft starter to the main motor is detected and processed. After the secondary start-up protection procedure is completed, it is determined whether the main pump pressure is greater than or equal to the preset pressure. If so, the start-up is complete; otherwise, the primary start-up protection procedure is entered, and the rotational matching relationship between the main motor and the main pump is detected and processed after the main motor starts. After the first-level startup protection procedure ends, startup is complete; The main motor drives the main pump to rotate in the target direction, ending the electric excavator's start-up protection program.

8. The control method for the electric excavator start-up protection system according to claim 7, characterized in that, The three-level startup protection procedure specifically includes: Initialize the main motor's steering state; After powering on the distribution cabinet, control cabinet, and key, check if the safety handle is closed. If the safety handle is not closed, the coil of the second intermediate relay is energized, the normally closed contact of the second intermediate relay is opened, and the main motor cannot be started by the key switch and start button. Then, after closing the safety handle and powering on the distribution cabinet, control cabinet, and key, check if the safety handle is closed again and repeat the subsequent operation. If the safety handle is closed, check if there is a phase loss at the soft starter input terminal. If so, a phase loss fault alarm will be triggered, and the fault will be checked and repaired. After powering on the distribution cabinet, control cabinet, and key, check again if the safety handle is closed and repeat the subsequent operation. If not, the second intermediate relay coil will be de-energized, the normally closed contact of the second intermediate relay will be closed, and the main motor can be started by the key switch or the start button. Determine if the phase sequence from the distribution cabinet to the soft starter is incorrect. If so, change the main motor rotation state and store the state; otherwise, store the current main motor rotation state.

9. The control method for the electric excavator start-up protection system according to claim 7, characterized in that, The secondary startup protection procedure specifically includes: Determine if the electrical phase sequence from the soft starter to the main motor is incorrect. If not, change the main motor rotation state, store the state, and then output the currently stored main motor rotation control signal to the soft starter to start the main motor and drive the main pump to rotate. If yes, output the currently stored main motor rotation control signal to the soft starter to start the main motor and drive the main pump to rotate.

10. The control method for the electric excavator start-up protection system according to claim 7, characterized in that, The first-level start-up protection program specifically includes: changing the current main motor rotation state and storing the state, outputting the currently stored main motor rotation control signal to the soft starter, so that the main motor drives the main pump to rotate in the opposite direction.

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